dialyzer: Fix opaque bugs

t_from_form() sometimes returned a more general type than it should
have done due to a bug in from_form_loop(): it stopped when the limit
was exceeded, which could mean a collapsed type. Returning a type with
smaller depth should fix this.

is_specialization() now handles opaque types before unions, which
should fix another problem.

The bugs reported by Kostis.

7 files changed, 16942 insertions, 1 deletions

diff --git a/lib/dialyzer/test/opaque_SUITE_data/dialyzer_options b/lib/dialyzer/test/opaque_SUITE_data/dialyzer_options
index ffdf8270c8..06ed52043a 100644
--- a/lib/dialyzer/test/opaque_SUITE_data/dialyzer_options
+++ b/lib/dialyzer/test/opaque_SUITE_data/dialyzer_options
@@ -1,2 +1,2 @@
 {dialyzer_options, [{warnings, [no_unused, no_return]}]}.
-{time_limit, 2}.
+{time_limit, 20}.
diff --git a/lib/dialyzer/test/opaque_SUITE_data/src/recrec/cerl.erl b/lib/dialyzer/test/opaque_SUITE_data/src/recrec/cerl.erl
new file mode 100644
index 0000000000..a4fdbfd5f0
--- /dev/null
+++ b/lib/dialyzer/test/opaque_SUITE_data/src/recrec/cerl.erl
@@ -0,0 +1,4602 @@
+%%
+%% %CopyrightBegin%
+%%
+%% Copyright Ericsson AB 2001-2016. All Rights Reserved.
+%%
+%% Licensed under the Apache License, Version 2.0 (the "License");
+%% you may not use this file except in compliance with the License.
+%% You may obtain a copy of the License at
+%%
+%%     http://www.apache.org/licenses/LICENSE-2.0
+%%
+%% Unless required by applicable law or agreed to in writing, software
+%% distributed under the License is distributed on an "AS IS" BASIS,
+%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+%% See the License for the specific language governing permissions and
+%% limitations under the License.
+%%
+%% %CopyrightEnd%
+
+%% =====================================================================
+%% @doc Core Erlang abstract syntax trees.
+%%
+%% <p> This module defines an abstract data type for representing Core
+%% Erlang source code as syntax trees.</p>
+%%
+%% <p>A recommended starting point for the first-time user is the
+%% documentation of the function <a
+%% href="#type-1"><code>type/1</code></a>.</p>
+%%
+%% <h3><b>NOTES:</b></h3>
+%%
+%% <p>This module deals with the composition and decomposition of
+%% <em>syntactic</em> entities (as opposed to semantic ones); its
+%% purpose is to hide all direct references to the data structures
+%% used to represent these entities. With few exceptions, the
+%% functions in this module perform no semantic interpretation of
+%% their inputs, and in general, the user is assumed to pass
+%% type-correct arguments - if this is not done, the effects are not
+%% defined.</p>
+%%
+%% <p>Currently, the internal data structure used is the same as
+%% the record-based data structures used traditionally in the Beam
+%% compiler.</p>
+%% 
+%% <p>The internal representations of abstract syntax trees are
+%% subject to change without notice, and should not be documented
+%% outside this module. Furthermore, we do not give any guarantees on
+%% how an abstract syntax tree may or may not be represented, <em>with
+%% the following exceptions</em>: no syntax tree is represented by a
+%% single atom, such as <code>none</code>, by a list constructor
+%% <code>[X | Y]</code>, or by the empty list <code>[]</code>. This
+%% can be relied on when writing functions that operate on syntax
+%% trees.</p>
+%%
+%% @type cerl(). An abstract Core Erlang syntax tree.
+%%
+%% <p>Every abstract syntax tree has a <em>type</em>, given by the
+%% function <a href="#type-1"><code>type/1</code></a>.  In addition,
+%% each syntax tree has a list of <em>user annotations</em> (cf.  <a
+%% href="#get_ann-1"><code>get_ann/1</code></a>), which are included
+%% in the Core Erlang syntax.</p>
+
+-module(cerl).
+
+-export([abstract/1, add_ann/2, alias_pat/1, alias_var/1,
+	 ann_abstract/2, ann_c_alias/3, ann_c_apply/3, ann_c_atom/2,
+	 ann_c_call/4, ann_c_case/3, ann_c_catch/2, ann_c_char/2,
+	 ann_c_clause/3, ann_c_clause/4, ann_c_cons/3, ann_c_float/2,
+	 ann_c_fname/3, ann_c_fun/3, ann_c_int/2, ann_c_let/4,
+	 ann_c_letrec/3, ann_c_module/4, ann_c_module/5, ann_c_nil/1,
+	 ann_c_cons_skel/3, ann_c_tuple_skel/2, ann_c_primop/3,
+	 ann_c_receive/2, ann_c_receive/4, ann_c_seq/3, ann_c_string/2,
+	 ann_c_try/6, ann_c_tuple/2, ann_c_values/2, ann_c_var/2,
+	 ann_make_data/3, ann_make_list/2, ann_make_list/3,
+	 ann_make_data_skel/3, ann_make_tree/3, apply_args/1,
+	 apply_arity/1, apply_op/1, atom_lit/1, atom_name/1, atom_val/1,
+	 c_alias/2, c_apply/2, c_atom/1, c_call/3, c_case/2, c_catch/1,
+	 c_char/1, c_clause/2, c_clause/3, c_cons/2, c_float/1,
+	 c_fname/2, c_fun/2, c_int/1, c_let/3, c_letrec/2, c_module/3,
+	 c_module/4, c_nil/0, c_cons_skel/2, c_tuple_skel/1, c_primop/2,
+	 c_receive/1, c_receive/3, c_seq/2, c_string/1, c_try/5,
+	 c_tuple/1, c_values/1, c_var/1, call_args/1, call_arity/1,
+	 call_module/1, call_name/1, case_arg/1, case_arity/1,
+	 case_clauses/1, catch_body/1, char_lit/1, char_val/1,
+	 clause_arity/1, clause_body/1, clause_guard/1, clause_pats/1,
+	 clause_vars/1, concrete/1, cons_hd/1, cons_tl/1, copy_ann/2,
+	 data_arity/1, data_es/1, data_type/1, float_lit/1, float_val/1,
+	 fname_arity/1, fname_id/1, fold_literal/1, from_records/1,
+	 fun_arity/1, fun_body/1, fun_vars/1, get_ann/1, int_lit/1,
+	 int_val/1, is_c_alias/1, is_c_apply/1, is_c_atom/1,
+	 is_c_call/1, is_c_case/1, is_c_catch/1, is_c_char/1,
+	 is_c_clause/1, is_c_cons/1, is_c_float/1, is_c_fname/1,
+	 is_c_fun/1, is_c_int/1, is_c_let/1, is_c_letrec/1, is_c_list/1,
+	 is_c_module/1, is_c_nil/1, is_c_primop/1, is_c_receive/1,
+	 is_c_seq/1, is_c_string/1, is_c_try/1, is_c_tuple/1,
+	 is_c_values/1, is_c_var/1, is_data/1, is_leaf/1, is_literal/1,
+	 is_literal_term/1, is_print_char/1, is_print_string/1,
+	 let_arg/1, let_arity/1, let_body/1, let_vars/1, letrec_body/1,
+	 letrec_defs/1, letrec_vars/1, list_elements/1, list_length/1,
+	 make_data/2, make_list/1, make_list/2, make_data_skel/2,
+	 make_tree/2, meta/1, module_attrs/1, module_defs/1,
+	 module_exports/1, module_name/1, module_vars/1,
+	 pat_list_vars/1, pat_vars/1, primop_args/1, primop_arity/1,
+	 primop_name/1, receive_action/1, receive_clauses/1,
+	 receive_timeout/1, seq_arg/1, seq_body/1, set_ann/2,
+	 string_lit/1, string_val/1, subtrees/1, to_records/1,
+	 try_arg/1, try_body/1, try_vars/1, try_evars/1, try_handler/1,
+	 tuple_arity/1, tuple_es/1, type/1, unfold_literal/1,
+	 update_c_alias/3, update_c_apply/3, update_c_call/4,
+	 update_c_case/3, update_c_catch/2, update_c_clause/4,
+	 update_c_cons/3, update_c_cons_skel/3, update_c_fname/2,
+	 update_c_fname/3, update_c_fun/3, update_c_let/4,
+	 update_c_letrec/3, update_c_module/5, update_c_primop/3,
+	 update_c_receive/4, update_c_seq/3, update_c_try/6,
+	 update_c_tuple/2, update_c_tuple_skel/2, update_c_values/2,
+	 update_c_var/2, update_data/3, update_list/2, update_list/3,
+	 update_data_skel/3, update_tree/2, update_tree/3,
+	 values_arity/1, values_es/1, var_name/1, c_binary/1,
+	 update_c_binary/2, ann_c_binary/2, is_c_binary/1,
+	 binary_segments/1, c_bitstr/3, c_bitstr/4, c_bitstr/5,
+	 update_c_bitstr/5, update_c_bitstr/6, ann_c_bitstr/5,
+	 ann_c_bitstr/6, is_c_bitstr/1, bitstr_val/1, bitstr_size/1,
+	 bitstr_bitsize/1, bitstr_unit/1, bitstr_type/1, bitstr_flags/1,
+
+	 %% keep map exports here for now
+	 c_map_pattern/1,
+	 is_c_map/1,
+	 is_c_map_pattern/1,
+	 map_es/1,
+	 map_arg/1,
+	 update_c_map/3,
+	 c_map/1, is_c_map_empty/1,
+	 ann_c_map/2, ann_c_map/3,
+	 ann_c_map_pattern/2,
+	 map_pair_op/1,map_pair_key/1,map_pair_val/1,
+	 update_c_map_pair/4,
+	 c_map_pair/2, c_map_pair_exact/2,
+	 ann_c_map_pair/4
+     ]).
+
+-export_type([c_binary/0, c_bitstr/0, c_call/0, c_clause/0, c_cons/0, c_fun/0,
+	      c_let/0, c_literal/0, c_map/0, c_map_pair/0,
+	      c_module/0, c_tuple/0,
+	      c_values/0, c_var/0, cerl/0,
+	      anns/0, attrs/0, defs/0, litval/0, var_name/0]).
+
+-include("core_parse.hrl").
+
+-type c_alias()   :: #c_alias{}.
+-type c_apply()   :: #c_apply{}.
+-type c_binary()  :: #c_binary{}.
+-type c_bitstr()  :: #c_bitstr{}.
+-type c_call()    :: #c_call{}.
+-type c_case()    :: #c_case{}.
+-type c_catch()   :: #c_catch{}.
+-type c_clause()  :: #c_clause{}.
+-type c_cons()    :: #c_cons{}.
+-type c_fun()     :: #c_fun{}.
+-type c_let()     :: #c_let{}.
+-type c_letrec()  :: #c_letrec{}.
+-type c_literal() :: #c_literal{}.
+-type c_map()     :: #c_map{}.
+-type c_map_pair() :: #c_map_pair{}.
+-type c_module()  :: #c_module{}.
+-type c_primop()  :: #c_primop{}.
+-type c_receive() :: #c_receive{}.
+-type c_seq()     :: #c_seq{}.
+-type c_try()     :: #c_try{}.
+-type c_tuple()   :: #c_tuple{}.
+-type c_values()  :: #c_values{}.
+-type c_var()     :: #c_var{}.
+
+-type cerl() :: c_alias()  | c_apply()  | c_binary()  | c_bitstr()
+              | c_call()   | c_case()   | c_catch()   | c_clause()  | c_cons()
+              | c_fun()    | c_let()    | c_letrec()  | c_literal()
+	      | c_map()    | c_map_pair()
+	      | c_module() | c_primop() | c_receive() | c_seq()
+              | c_try()    | c_tuple()  | c_values()  | c_var().
+
+-type anns()  :: [term()].
+-type attr()  :: {c_literal(), c_literal()}.
+-type attrs() :: [attr()].
+-type def()   :: {c_var(), c_fun()}.
+-type defs()  :: [def()].
+
+-type litval() :: atom() | bitstring() | map() | number()
+		| string() | tuple() | [litval()].
+
+-type var_name() :: integer() | atom() | {atom(), arity()}.
+
+
+%% =====================================================================
+%% Representation (general)
+%%
+%% All nodes are represented by tuples of arity 2 or (generally)
+%% greater, whose first element is an atom which uniquely identifies the
+%% type of the node, and whose second element is a (proper) list of
+%% annotation terms associated with the node - this is by default empty.
+%%
+%% For most node constructor functions, there are analogous functions
+%% named 'ann_...', taking one extra argument 'As' (always the first
+%% argument), specifying an annotation list at node creation time.
+%% Similarly, there are also functions named 'update_...', taking one
+%% extra argument 'Old', specifying a node from which all fields not
+%% explicitly given as arguments should be copied (generally, this is
+%% the annotation field only).
+%% =====================================================================
+
+%% @spec type(Node::cerl()) -> atom()
+%%
+%% @doc Returns the type tag of <code>Node</code>. Current node types
+%% are:
+%%	    
+%% <p><center><table border="1">
+%%  <tr>
+%%    <td>alias</td>
+%%    <td>apply</td>
+%%    <td>binary</td>
+%%    <td>bitstr</td>
+%%    <td>call</td>
+%%    <td>case</td>
+%%    <td>catch</td>
+%%    <td>clause</td>
+%%  </tr><tr>
+%%    <td>cons</td>
+%%    <td>fun</td>
+%%    <td>let</td>
+%%    <td>letrec</td>
+%%    <td>literal</td>
+%%    <td>map</td>
+%%    <td>map_pair</td>
+%%    <td>module</td>
+%%  </tr><tr>
+%%    <td>primop</td>
+%%    <td>receive</td>
+%%    <td>seq</td>
+%%    <td>try</td>
+%%    <td>tuple</td>
+%%    <td>values</td>
+%%    <td>var</td>
+%%  </tr>
+%% </table></center></p>
+%%
+%% <p>Note: The name of the primary constructor function for a node
+%% type is always the name of the type itself, prefixed by
+%% "<code>c_</code>"; recognizer predicates are correspondingly
+%% prefixed by "<code>is_c_</code>". Furthermore, to simplify
+%% preservation of annotations (cf. <code>get_ann/1</code>), there are
+%% analogous constructor functions prefixed by "<code>ann_c_</code>"
+%% and "<code>update_c_</code>", for setting the annotation list of
+%% the new node to either a specific value or to the annotations of an
+%% existing node, respectively.</p>
+%%
+%% @see abstract/1
+%% @see c_alias/2
+%% @see c_apply/2
+%% @see c_binary/1
+%% @see c_bitstr/5
+%% @see c_call/3
+%% @see c_case/2
+%% @see c_catch/1
+%% @see c_clause/3
+%% @see c_cons/2
+%% @see c_fun/2
+%% @see c_let/3
+%% @see c_letrec/2
+%% @see c_module/3
+%% @see c_primop/2
+%% @see c_receive/1
+%% @see c_seq/2
+%% @see c_try/5
+%% @see c_tuple/1
+%% @see c_values/1
+%% @see c_var/1
+%% @see get_ann/1
+%% @see to_records/1
+%% @see from_records/1
+%% @see data_type/1
+%% @see subtrees/1
+%% @see meta/1
+
+-type ctype() :: 'alias'   | 'apply'  | 'binary' | 'bitrst' | 'call' | 'case'
+               | 'catch'   | 'clause' | 'cons'   | 'fun'    | 'let'  | 'letrec'
+               | 'literal' | 'map'  | 'map_pair' | 'module' | 'primop'
+               | 'receive' | 'seq'    | 'try'    | 'tuple'  | 'values' | 'var'.
+
+-spec type(cerl()) -> ctype().
+
+type(#c_alias{}) -> alias;
+type(#c_apply{}) -> apply;
+type(#c_binary{}) -> binary;
+type(#c_bitstr{}) -> bitstr;
+type(#c_call{}) -> call;
+type(#c_case{}) -> 'case';
+type(#c_catch{}) -> 'catch';
+type(#c_clause{}) -> clause;
+type(#c_cons{}) -> cons;
+type(#c_fun{}) -> 'fun';
+type(#c_let{}) -> 'let';
+type(#c_letrec{}) -> letrec;
+type(#c_literal{}) -> literal;
+type(#c_map{}) -> map;
+type(#c_map_pair{}) -> map_pair;
+type(#c_module{}) -> module;
+type(#c_primop{}) -> primop;
+type(#c_receive{}) -> 'receive';
+type(#c_seq{}) -> seq;
+type(#c_try{}) -> 'try';
+type(#c_tuple{}) -> tuple;
+type(#c_values{}) -> values;
+type(#c_var{}) -> var.
+
+
+%% @spec is_leaf(Node::cerl()) -> boolean()
+%%
+%% @doc Returns <code>true</code> if <code>Node</code> is a leaf node,
+%% otherwise <code>false</code>. The current leaf node types are
+%% <code>literal</code> and <code>var</code>.
+%%
+%% <p>Note: all literals (cf. <code>is_literal/1</code>) are leaf
+%% nodes, even if they represent structured (constant) values such as
+%% <code>{foo, [bar, baz]}</code>. Also note that variables are leaf
+%% nodes but not literals.</p>
+%%
+%% @see type/1
+%% @see is_literal/1
+
+-spec is_leaf(cerl()) -> boolean().
+
+is_leaf(Node) ->
+    case type(Node) of
+	literal -> true;
+	var -> true;
+	_ -> false
+    end.
+
+
+%% @spec get_ann(cerl()) -> anns()
+%%
+%% @doc Returns the list of user annotations associated with a syntax
+%% tree node. For a newly created node, this is the empty list. The
+%% annotations may be any terms.
+%%
+%% @see set_ann/2
+
+-spec get_ann(cerl()) -> anns().
+
+get_ann(Node) ->
+    element(2, Node).
+
+
+%% @spec set_ann(Node::cerl(), Annotations::anns()) -> cerl()
+%%
+%% @doc Sets the list of user annotations of <code>Node</code> to
+%% <code>Annotations</code>.
+%%
+%% @see get_ann/1
+%% @see add_ann/2
+%% @see copy_ann/2
+
+-spec set_ann(cerl(), anns()) -> cerl().
+
+set_ann(Node, List) ->
+    setelement(2, Node, List).
+
+
+%% @spec add_ann(Annotations::anns(), Node::cerl()) -> cerl()
+%%
+%% @doc Appends <code>Annotations</code> to the list of user
+%% annotations of <code>Node</code>.
+%%
+%% <p>Note: this is equivalent to <code>set_ann(Node, Annotations ++
+%% get_ann(Node))</code>, but potentially more efficient.</p>
+%%
+%% @see get_ann/1
+%% @see set_ann/2
+
+-spec add_ann(anns(), cerl()) -> cerl().
+
+add_ann(Terms, Node) ->
+    set_ann(Node, Terms ++ get_ann(Node)).
+
+
+%% @spec copy_ann(Source::cerl(), Target::cerl()) -> cerl()
+%%
+%% @doc Copies the list of user annotations from <code>Source</code>
+%% to <code>Target</code>.
+%%
+%% <p>Note: this is equivalent to <code>set_ann(Target,
+%% get_ann(Source))</code>, but potentially more efficient.</p>
+%%
+%% @see get_ann/1
+%% @see set_ann/2
+
+-spec copy_ann(cerl(), cerl()) -> cerl().
+
+copy_ann(Source, Target) ->
+    set_ann(Target, get_ann(Source)).
+
+
+%% @spec abstract(Term::litval()) -> cerl()
+%%
+%% @doc Creates a syntax tree corresponding to an Erlang term.
+%% <code>Term</code> must be a literal term, i.e., one that can be
+%% represented as a source code literal. Thus, it may not contain a
+%% process identifier, port, reference or function value as a subterm.
+%%
+%% <p>Note: This is a constant time operation.</p>
+%%
+%% @see ann_abstract/2
+%% @see concrete/1
+%% @see is_literal/1
+%% @see is_literal_term/1
+
+-spec abstract(litval()) -> c_literal().
+
+abstract(T) ->
+    #c_literal{val = T}.
+
+
+%% @spec ann_abstract(Annotations::anns(), Term::litval()) -> cerl()
+%% @see abstract/1
+
+-spec ann_abstract(anns(), litval()) -> c_literal().
+
+ann_abstract(As, T) ->
+    #c_literal{val = T, anno = As}.
+
+
+%% @spec is_literal_term(Term::term()) -> boolean()
+%%
+%% @doc Returns <code>true</code> if <code>Term</code> can be
+%% represented as a literal, otherwise <code>false</code>. This
+%% function takes time proportional to the size of <code>Term</code>.
+%%
+%% @see abstract/1
+
+-spec is_literal_term(term()) -> boolean().
+
+is_literal_term(T) when is_integer(T) -> true;
+is_literal_term(T) when is_float(T) -> true;
+is_literal_term(T) when is_atom(T) -> true;
+is_literal_term([]) -> true;
+is_literal_term([H | T]) ->
+    is_literal_term(H) andalso is_literal_term(T);
+is_literal_term(T) when is_tuple(T) ->
+    is_literal_term_list(tuple_to_list(T));
+is_literal_term(B) when is_bitstring(B) -> true;
+is_literal_term(M) when is_map(M) ->
+    is_literal_term_list(maps:to_list(M));
+is_literal_term(_) ->
+    false.
+
+-spec is_literal_term_list([term()]) -> boolean().
+
+is_literal_term_list([T | Ts]) ->
+    case is_literal_term(T) of
+	true ->
+	    is_literal_term_list(Ts);
+	false ->
+	    false
+    end;
+is_literal_term_list([]) ->
+    true.
+
+
+%% @spec concrete(Node::c_literal()) -> litval()
+%%
+%% @doc Returns the Erlang term represented by a syntax tree.  An
+%% exception is thrown if <code>Node</code> does not represent a
+%% literal term.
+%%
+%% <p>Note: This is a constant time operation.</p>
+%%
+%% @see abstract/1
+%% @see is_literal/1
+
+%% Because the normal tuple and list constructor operations always
+%% return a literal if the arguments are literals, 'concrete' and
+%% 'is_literal' never need to traverse the structure.
+
+-spec concrete(c_literal()) -> litval().
+
+concrete(#c_literal{val = V}) ->
+    V.
+
+
+%% @spec is_literal(Node::cerl()) -> boolean()
+%%
+%% @doc Returns <code>true</code> if <code>Node</code> represents a
+%% literal term, otherwise <code>false</code>. This function returns
+%% <code>true</code> if and only if the value of
+%% <code>concrete(Node)</code> is defined.
+%%
+%% <p>Note: This is a constant time operation.</p>
+%%
+%% @see abstract/1
+%% @see concrete/1
+%% @see fold_literal/1
+
+-spec is_literal(cerl()) -> boolean().
+
+is_literal(#c_literal{}) ->
+    true;
+is_literal(_) ->
+    false.
+
+
+%% @spec fold_literal(Node::cerl()) -> cerl()
+%%
+%% @doc Assures that literals have a compact representation. This is
+%% occasionally useful if <code>c_cons_skel/2</code>,
+%% <code>c_tuple_skel/1</code> or <code>unfold_literal/1</code> were
+%% used in the construction of <code>Node</code>, and you want to revert
+%% to the normal "folded" representation of literals. If
+%% <code>Node</code> represents a tuple or list constructor, its
+%% elements are rewritten recursively, and the node is reconstructed
+%% using <code>c_cons/2</code> or <code>c_tuple/1</code>, respectively;
+%% otherwise, <code>Node</code> is not changed.
+%%
+%% @see is_literal/1
+%% @see c_cons_skel/2
+%% @see c_tuple_skel/1
+%% @see c_cons/2
+%% @see c_tuple/1
+%% @see unfold_literal/1
+
+-spec fold_literal(cerl()) -> cerl().
+
+fold_literal(Node) ->
+    case type(Node) of
+	tuple ->
+	    update_c_tuple(Node, fold_literal_list(tuple_es(Node)));
+	cons ->
+	    update_c_cons(Node, fold_literal(cons_hd(Node)),
+			  fold_literal(cons_tl(Node)));
+	_ ->
+	    Node    
+    end.
+
+fold_literal_list([E | Es]) ->
+    [fold_literal(E) | fold_literal_list(Es)];
+fold_literal_list([]) ->
+    [].
+
+
+%% @spec unfold_literal(Node::cerl()) -> cerl()
+%%
+%% @doc Assures that literals have a fully expanded representation. If
+%% <code>Node</code> represents a literal tuple or list constructor, its
+%% elements are rewritten recursively, and the node is reconstructed
+%% using <code>c_cons_skel/2</code> or <code>c_tuple_skel/1</code>,
+%% respectively; otherwise, <code>Node</code> is not changed. The {@link
+%% fold_literal/1} can be used to revert to the normal compact
+%% representation.
+%%
+%% @see is_literal/1
+%% @see c_cons_skel/2
+%% @see c_tuple_skel/1
+%% @see c_cons/2
+%% @see c_tuple/1
+%% @see fold_literal/1
+
+-spec unfold_literal(cerl()) -> cerl().
+
+unfold_literal(Node) ->
+    case type(Node) of
+	literal ->
+	    copy_ann(Node, unfold_concrete(concrete(Node)));
+	_ ->
+	    Node
+    end.
+
+unfold_concrete(Val) ->
+    case Val of
+	_ when is_tuple(Val) ->
+	    c_tuple_skel(unfold_concrete_list(tuple_to_list(Val)));
+	[H|T] ->
+	    c_cons_skel(unfold_concrete(H), unfold_concrete(T));
+	_ ->
+	    abstract(Val)
+    end.
+
+unfold_concrete_list([E | Es]) ->
+    [unfold_concrete(E) | unfold_concrete_list(Es)];
+unfold_concrete_list([]) ->
+    [].
+
+
+%% ---------------------------------------------------------------------
+
+%% @spec c_module(Name::c_literal(), Exports, Definitions) -> c_module()
+%%
+%%     Exports = [c_var()]
+%%     Definitions = defs()
+%%
+%% @equiv c_module(Name, Exports, [], Definitions)
+
+-spec c_module(c_literal(), [c_var()], defs()) -> c_module().
+
+c_module(Name, Exports, Defs) ->
+    #c_module{name = Name, exports = Exports, attrs = [], defs = Defs}.
+
+
+%% @spec c_module(Name::c_literal(), Exports, Attributes, Definitions) ->
+%%           c_module()
+%%
+%%     Exports = [c_var()]
+%%     Attributes = attrs()
+%%     Definitions = defs()
+%%
+%% @doc Creates an abstract module definition. The result represents
+%% <pre>
+%%   module <em>Name</em> [<em>E1</em>, ..., <em>Ek</em>]
+%%     attributes [<em>K1</em> = <em>T1</em>, ...,
+%%                 <em>Km</em> = <em>Tm</em>]
+%%     <em>V1</em> = <em>F1</em>
+%%     ...
+%%     <em>Vn</em> = <em>Fn</em>
+%%   end</pre>
+%%
+%% if <code>Exports</code> = <code>[E1, ..., Ek]</code>,
+%% <code>Attributes</code> = <code>[{K1, T1}, ..., {Km, Tm}]</code>,
+%% and <code>Definitions</code> = <code>[{V1, F1}, ..., {Vn,
+%% Fn}]</code>.
+%%
+%% <p><code>Name</code> and all the <code>Ki</code> must be atom
+%% literals, and all the <code>Ti</code> must be constant literals. All
+%% the <code>Vi</code> and <code>Ei</code> must have type
+%% <code>var</code> and represent function names. All the
+%% <code>Fi</code> must have type <code>'fun'</code>.</p>
+%%
+%% @see c_module/3
+%% @see module_name/1
+%% @see module_exports/1
+%% @see module_attrs/1
+%% @see module_defs/1
+%% @see module_vars/1
+%% @see ann_c_module/4
+%% @see ann_c_module/5
+%% @see update_c_module/5
+%% @see c_atom/1
+%% @see c_var/1
+%% @see c_fun/2
+%% @see is_literal/1
+
+-spec c_module(c_literal(), [c_var()], attrs(), defs()) -> c_module().
+
+c_module(Name, Exports, Attrs, Defs) ->
+    #c_module{name = Name, exports = Exports, attrs = Attrs, defs = Defs}.
+
+
+%% @spec ann_c_module(As::anns(), Name::c_literal(), Exports,
+%%                    Definitions) -> c_module()
+%%
+%%     Exports = [c_var()]
+%%     Definitions = defs()
+%%
+%% @see c_module/3
+%% @see ann_c_module/5
+
+-spec ann_c_module(anns(), c_literal(), [c_var()], defs()) -> c_module().
+
+ann_c_module(As, Name, Exports, Defs) ->
+    #c_module{name = Name, exports = Exports, attrs = [], defs = Defs,
+	      anno = As}.
+
+
+%% @spec ann_c_module(As::anns(), Name::c_literal(), Exports,
+%%                    Attributes, Definitions) -> c_module()
+%%
+%%     Exports = [c_var()]
+%%     Attributes = attrs()
+%%     Definitions = defs()
+%%
+%% @see c_module/4
+%% @see ann_c_module/4
+
+-spec ann_c_module(anns(), c_literal(), [c_var()], attrs(), defs()) ->
+	c_module().
+
+ann_c_module(As, Name, Exports, Attrs, Defs) ->
+    #c_module{name = Name, exports = Exports, attrs = Attrs, defs = Defs,
+	      anno = As}.
+
+
+%% @spec update_c_module(Old::cerl(), Name::c_literal(), Exports,
+%%                       Attributes, Definitions) -> c_module()
+%%
+%%     Exports = [c_var()]
+%%     Attributes = attrs()
+%%     Definitions = defs()
+%%
+%% @see c_module/4
+
+-spec update_c_module(c_module(), c_literal(), [c_var()], attrs(), defs()) ->
+	c_module().
+
+update_c_module(Node, Name, Exports, Attrs, Defs) ->
+    #c_module{name = Name, exports = Exports, attrs = Attrs, defs = Defs,
+	      anno = get_ann(Node)}.
+
+
+%% @spec is_c_module(Node::cerl()) -> boolean()
+%%
+%% @doc Returns <code>true</code> if <code>Node</code> is an abstract
+%% module definition, otherwise <code>false</code>.
+%%
+%% @see type/1
+
+-spec is_c_module(cerl()) -> boolean().
+
+is_c_module(#c_module{}) ->
+    true;
+is_c_module(_) ->
+    false.
+
+
+%% @spec module_name(Node::c_module()) -> c_literal()
+%%
+%% @doc Returns the name subtree of an abstract module definition.
+%%
+%% @see c_module/4
+
+-spec module_name(c_module()) -> c_literal().
+
+module_name(Node) ->
+    Node#c_module.name.
+
+
+%% @spec module_exports(Node::c_module()) -> [c_var()]
+%%
+%% @doc Returns the list of exports subtrees of an abstract module
+%% definition.
+%%
+%% @see c_module/4
+
+-spec module_exports(c_module()) -> [c_var()].
+
+module_exports(Node) ->
+    Node#c_module.exports.
+
+
+%% @spec module_attrs(Node::c_module()) -> [{cerl(), cerl()}]
+%%
+%% @doc Returns the list of pairs of attribute key/value subtrees of
+%% an abstract module definition.
+%%
+%% @see c_module/4
+
+-spec module_attrs(c_module()) -> attrs().
+
+module_attrs(Node) ->
+    Node#c_module.attrs.
+
+
+%% @spec module_defs(Node::c_module()) -> defs()
+%%
+%% @doc Returns the list of function definitions of an abstract module
+%% definition.
+%%
+%% @see c_module/4
+
+-spec module_defs(c_module()) -> defs().
+
+module_defs(Node) ->
+    Node#c_module.defs.
+
+
+%% @spec module_vars(Node::c_module()) -> [c_var()]
+%%
+%% @doc Returns the list of left-hand side function variable subtrees
+%% of an abstract module definition.
+%%
+%% @see c_module/4
+
+-spec module_vars(c_module()) -> [c_var()].
+
+module_vars(Node) ->
+    [F || {F, _} <- module_defs(Node)].
+
+
+%% ---------------------------------------------------------------------
+
+%% @spec c_int(Value::integer()) -> c_literal()
+%%
+%% @doc Creates an abstract integer literal. The lexical
+%% representation is the canonical decimal numeral of
+%% <code>Value</code>.
+%%
+%% @see ann_c_int/2
+%% @see is_c_int/1
+%% @see int_val/1
+%% @see int_lit/1
+%% @see c_char/1
+
+-spec c_int(integer()) -> c_literal().
+
+c_int(Value) ->
+    #c_literal{val = Value}.
+
+
+%% @spec ann_c_int(As::anns(), Value::integer()) -> c_literal()
+%% @see c_int/1
+
+-spec ann_c_int(anns(), integer()) -> c_literal().
+
+ann_c_int(As, Value) ->
+    #c_literal{val = Value, anno = As}.
+
+
+%% @spec is_c_int(Node::cerl()) -> boolean()
+%%
+%% @doc Returns <code>true</code> if <code>Node</code> represents an
+%% integer literal, otherwise <code>false</code>.
+%% @see c_int/1
+
+-spec is_c_int(cerl()) -> boolean().
+
+is_c_int(#c_literal{val = V}) when is_integer(V) ->
+    true;
+is_c_int(_) ->
+    false.
+
+
+%% @spec int_val(c_literal()) -> integer()
+%%
+%% @doc Returns the value represented by an integer literal node.
+%% @see c_int/1
+
+-spec int_val(c_literal()) -> integer().
+
+int_val(Node) ->
+    Node#c_literal.val.
+
+
+%% @spec int_lit(c_literal()) -> string()
+%%
+%% @doc Returns the numeral string represented by an integer literal
+%% node.
+%% @see c_int/1
+
+-spec int_lit(c_literal()) -> string().
+
+int_lit(Node) ->
+    integer_to_list(int_val(Node)).
+
+
+%% ---------------------------------------------------------------------
+
+%% @spec c_float(Value::float()) -> c_literal()
+%%
+%% @doc Creates an abstract floating-point literal.  The lexical
+%% representation is the decimal floating-point numeral of
+%% <code>Value</code>.
+%%
+%% @see ann_c_float/2
+%% @see is_c_float/1
+%% @see float_val/1
+%% @see float_lit/1
+
+%% Note that not all floating-point numerals can be represented with
+%% full precision.
+
+-spec c_float(float()) -> c_literal().
+
+c_float(Value) ->
+    #c_literal{val = Value}.
+
+
+%% @spec ann_c_float(As::anns(), Value::float()) -> c_literal()
+%% @see c_float/1
+
+-spec ann_c_float(anns(), float()) -> c_literal().
+
+ann_c_float(As, Value) ->
+    #c_literal{val = Value, anno = As}.
+
+
+%% @spec is_c_float(Node::cerl()) -> boolean()
+%%
+%% @doc Returns <code>true</code> if <code>Node</code> represents a
+%% floating-point literal, otherwise <code>false</code>.
+%% @see c_float/1
+
+-spec is_c_float(cerl()) -> boolean().
+
+is_c_float(#c_literal{val = V}) when is_float(V) ->
+    true;
+is_c_float(_) ->
+    false.
+
+
+%% @spec float_val(c_literal()) -> float()
+%%
+%% @doc Returns the value represented by a floating-point literal
+%% node.
+%% @see c_float/1
+
+-spec float_val(c_literal()) -> float().
+
+float_val(Node) ->
+    Node#c_literal.val.
+
+
+%% @spec float_lit(c_literal()) -> string()
+%%
+%% @doc Returns the numeral string represented by a floating-point
+%% literal node.
+%% @see c_float/1
+
+-spec float_lit(c_literal()) -> string().
+
+float_lit(Node) ->
+    float_to_list(float_val(Node)).
+
+
+%% ---------------------------------------------------------------------
+
+%% @spec c_atom(Name) -> c_literal()
+%%	    Name = atom() | string()
+%%
+%% @doc Creates an abstract atom literal.  The print name of the atom
+%% is the character sequence represented by <code>Name</code>.
+%%
+%% <p>Note: passing a string as argument to this function causes a
+%% corresponding atom to be created for the internal representation.</p>
+%%
+%% @see ann_c_atom/2
+%% @see is_c_atom/1
+%% @see atom_val/1
+%% @see atom_name/1
+%% @see atom_lit/1
+
+-spec c_atom(atom() | string()) -> c_literal().
+
+c_atom(Name) when is_atom(Name) ->
+    #c_literal{val = Name};
+c_atom(Name) ->
+    #c_literal{val = list_to_atom(Name)}.
+
+
+%% @spec ann_c_atom(As::anns(), Name) -> cerl()
+%%	    Name = atom() | string()
+%% @see c_atom/1
+
+-spec ann_c_atom(anns(), atom() | string()) -> c_literal().
+
+ann_c_atom(As, Name) when is_atom(Name) ->
+    #c_literal{val = Name, anno = As};
+ann_c_atom(As, Name) ->
+    #c_literal{val = list_to_atom(Name), anno = As}.
+
+
+%% @spec is_c_atom(Node::cerl()) -> boolean()
+%%
+%% @doc Returns <code>true</code> if <code>Node</code> represents an
+%% atom literal, otherwise <code>false</code>.
+%%
+%% @see c_atom/1
+
+-spec is_c_atom(cerl()) -> boolean().
+
+is_c_atom(#c_literal{val = V}) when is_atom(V) ->
+    true;
+is_c_atom(_) ->
+    false.
+
+%% @spec atom_val(c_literal()) -> atom()
+%%
+%% @doc Returns the value represented by an abstract atom.
+%%
+%% @see c_atom/1
+
+-spec atom_val(c_literal()) -> atom().
+
+atom_val(Node) ->
+    Node#c_literal.val.
+
+
+%% @spec atom_name(c_literal()) -> string()
+%%
+%% @doc Returns the printname of an abstract atom.
+%%
+%% @see c_atom/1
+
+-spec atom_name(c_literal()) -> string().
+
+atom_name(Node) ->
+    atom_to_list(atom_val(Node)).
+
+
+%% @spec atom_lit(cerl()) -> string()
+%%
+%% @doc Returns the literal string represented by an abstract
+%% atom. This always includes surrounding single-quote characters.
+%%
+%% <p>Note that an abstract atom may have several literal
+%% representations, and that the representation yielded by this
+%% function is not fixed; e.g.,
+%% <code>atom_lit(c_atom("a\012b"))</code> could yield the string
+%% <code>"\'a\\nb\'"</code>.</p>
+%%
+%% @see c_atom/1
+
+%% TODO: replace the use of the unofficial 'write_string/2'.
+
+-spec atom_lit(cerl()) -> nonempty_string().
+
+atom_lit(Node) ->
+    io_lib:write_string(atom_name(Node), $'). %' stupid Emacs.
+
+
+%% ---------------------------------------------------------------------
+
+%% @spec c_char(Value) -> c_literal()
+%%
+%%    Value = char() | integer()
+%%
+%% @doc Creates an abstract character literal. If the local
+%% implementation of Erlang defines <code>char()</code> as a subset of
+%% <code>integer()</code>, this function is equivalent to
+%% <code>c_int/1</code>. Otherwise, if the given value is an integer,
+%% it will be converted to the character with the corresponding
+%% code. The lexical representation of a character is
+%% "<code>$<em>Char</em></code>", where <code>Char</code> is a single
+%% printing character or an escape sequence.
+%%
+%% @see c_int/1
+%% @see c_string/1
+%% @see ann_c_char/2
+%% @see is_c_char/1
+%% @see char_val/1
+%% @see char_lit/1
+%% @see is_print_char/1
+
+-spec c_char(non_neg_integer()) -> c_literal().
+
+c_char(Value) when is_integer(Value), Value >= 0 ->
+    #c_literal{val = Value}.
+
+
+%% @spec ann_c_char(As::anns(), Value::char()) -> c_literal()
+%% @see c_char/1
+
+-spec ann_c_char(anns(), char()) -> c_literal().
+
+ann_c_char(As, Value) ->
+    #c_literal{val = Value, anno = As}.
+
+
+%% @spec is_c_char(Node::c_literal()) -> boolean()
+%%
+%% @doc Returns <code>true</code> if <code>Node</code> may represent a
+%% character literal, otherwise <code>false</code>.
+%%
+%% <p>If the local implementation of Erlang defines
+%% <code>char()</code> as a subset of <code>integer()</code>, then
+%% <code>is_c_int(<em>Node</em>)</code> will also yield
+%% <code>true</code>.</p>
+%%
+%% @see c_char/1
+%% @see is_print_char/1
+
+-spec is_c_char(c_literal()) -> boolean().
+
+is_c_char(#c_literal{val = V}) when is_integer(V), V >= 0 ->
+    is_char_value(V);
+is_c_char(_) ->
+    false.
+
+
+%% @spec is_print_char(Node::cerl()) -> boolean()
+%%
+%% @doc Returns <code>true</code> if <code>Node</code> may represent a
+%% "printing" character, otherwise <code>false</code>. (Cf.
+%% <code>is_c_char/1</code>.)  A "printing" character has either a
+%% given graphical representation, or a "named" escape sequence such
+%% as "<code>\n</code>". Currently, only ISO 8859-1 (Latin-1)
+%% character values are recognized.
+%%
+%% @see c_char/1
+%% @see is_c_char/1
+
+-spec is_print_char(cerl()) -> boolean().
+
+is_print_char(#c_literal{val = V}) when is_integer(V), V >= 0 ->
+    is_print_char_value(V);
+is_print_char(_) ->
+    false.
+
+
+%% @spec char_val(c_literal()) -> char()
+%%
+%% @doc Returns the value represented by an abstract character literal.
+%%
+%% @see c_char/1
+
+-spec char_val(c_literal()) -> char().
+
+char_val(Node) ->
+    Node#c_literal.val.
+
+
+%% @spec char_lit(c_literal()) -> string()
+%%
+%% @doc Returns the literal string represented by an abstract
+%% character. This includes a leading <code>$</code>
+%% character. Currently, all characters that are not in the set of ISO
+%% 8859-1 (Latin-1) "printing" characters will be escaped.
+%%
+%% @see c_char/1
+
+-spec char_lit(c_literal()) -> nonempty_string().
+
+char_lit(Node) ->
+    io_lib:write_char(char_val(Node)).
+
+
+%% ---------------------------------------------------------------------
+
+%% @spec c_string(Value::string()) -> c_literal()
+%%
+%% @doc Creates an abstract string literal. Equivalent to creating an
+%% abstract list of the corresponding character literals
+%% (cf. <code>is_c_string/1</code>), but is typically more
+%% efficient. The lexical representation of a string is
+%% "<code>"<em>Chars</em>"</code>", where <code>Chars</code> is a
+%% sequence of printing characters or spaces.
+%%
+%% @see c_char/1
+%% @see ann_c_string/2
+%% @see is_c_string/1
+%% @see string_val/1
+%% @see string_lit/1
+%% @see is_print_string/1
+
+-spec c_string(string()) -> c_literal().
+
+c_string(Value) ->
+    #c_literal{val = Value}.
+
+
+%% @spec ann_c_string(As::anns(), Value::string()) -> c_literal()
+%% @see c_string/1
+
+-spec ann_c_string(anns(), string()) -> c_literal().
+
+ann_c_string(As, Value) ->
+    #c_literal{val = Value, anno = As}.
+
+
+%% @spec is_c_string(Node::cerl()) -> boolean()
+%%
+%% @doc Returns <code>true</code> if <code>Node</code> may represent a
+%% string literal, otherwise <code>false</code>. Strings are defined
+%% as lists of characters; see <code>is_c_char/1</code> for details.
+%%
+%% @see c_string/1
+%% @see is_c_char/1
+%% @see is_print_string/1
+
+-spec is_c_string(cerl()) -> boolean().
+
+is_c_string(#c_literal{val = V}) ->
+    is_char_list(V);
+is_c_string(_) ->
+    false.
+
+
+%% @spec is_print_string(Node::cerl()) -> boolean()
+%%
+%% @doc Returns <code>true</code> if <code>Node</code> may represent a
+%% string literal containing only "printing" characters, otherwise
+%% <code>false</code>. See <code>is_c_string/1</code> and
+%% <code>is_print_char/1</code> for details. Currently, only ISO
+%% 8859-1 (Latin-1) character values are recognized.
+%%
+%% @see c_string/1
+%% @see is_c_string/1
+%% @see is_print_char/1
+
+-spec is_print_string(cerl()) -> boolean().
+
+is_print_string(#c_literal{val = V}) ->
+    is_print_char_list(V);
+is_print_string(_) ->
+    false.
+
+
+%% @spec string_val(cerl()) -> string()
+%%
+%% @doc Returns the value represented by an abstract string literal.
+%%
+%% @see c_string/1
+
+-spec string_val(c_literal()) -> string().
+
+string_val(Node) ->
+    Node#c_literal.val.
+
+
+%% @spec string_lit(cerl()) -> string()
+%%
+%% @doc Returns the literal string represented by an abstract string.
+%% This includes surrounding double-quote characters
+%% <code>"..."</code>. Currently, characters that are not in the set
+%% of ISO 8859-1 (Latin-1) "printing" characters will be escaped,
+%% except for spaces.
+%%
+%% @see c_string/1
+
+-spec string_lit(c_literal()) -> nonempty_string().
+
+string_lit(Node) ->
+    io_lib:write_string(string_val(Node)).
+
+
+%% ---------------------------------------------------------------------
+
+%% @spec c_nil() -> cerl()
+%%
+%% @doc Creates an abstract empty list. The result represents
+%% "<code>[]</code>". The empty list is traditionally called "nil".
+%%
+%% @see ann_c_nil/1
+%% @see is_c_list/1
+%% @see c_cons/2
+
+-spec c_nil() -> c_literal().
+
+c_nil() ->
+    #c_literal{val = []}.
+
+
+%% @spec ann_c_nil(As::anns()) -> cerl()
+%% @see c_nil/0
+
+-spec ann_c_nil(anns()) -> c_literal().
+
+ann_c_nil(As) ->
+    #c_literal{val = [], anno = As}.
+
+
+%% @spec is_c_nil(Node::cerl()) -> boolean()
+%%
+%% @doc Returns <code>true</code> if <code>Node</code> is an abstract
+%% empty list, otherwise <code>false</code>.
+
+-spec is_c_nil(cerl()) -> boolean().
+
+is_c_nil(#c_literal{val = []}) ->
+    true;
+is_c_nil(_) ->
+    false.
+
+
+%% ---------------------------------------------------------------------
+
+%% @spec c_cons(Head::cerl(), Tail::cerl()) -> cerl()
+%%
+%% @doc Creates an abstract list constructor. The result represents
+%% "<code>[<em>Head</em> | <em>Tail</em>]</code>". Note that if both
+%% <code>Head</code> and <code>Tail</code> have type
+%% <code>literal</code>, then the result will also have type
+%% <code>literal</code>, and annotations on <code>Head</code> and
+%% <code>Tail</code> are lost.
+%%
+%% <p>Recall that in Erlang, the tail element of a list constructor is
+%% not necessarily a list.</p>
+%%
+%% @see ann_c_cons/3
+%% @see update_c_cons/3
+%% @see c_cons_skel/2
+%% @see is_c_cons/1
+%% @see cons_hd/1
+%% @see cons_tl/1
+%% @see is_c_list/1
+%% @see c_nil/0
+%% @see list_elements/1
+%% @see list_length/1
+%% @see make_list/2
+
+%% *Always* collapse literals.
+
+-spec c_cons(cerl(), cerl()) -> c_literal() | c_cons().
+
+c_cons(#c_literal{val = Head}, #c_literal{val = Tail}) ->
+    #c_literal{val = [Head | Tail]};
+c_cons(Head, Tail) ->
+    #c_cons{hd = Head, tl = Tail}.
+
+
+%% @spec ann_c_cons(As::anns(), Head::cerl(), Tail::cerl()) -> cerl()
+%% @see c_cons/2
+
+-spec ann_c_cons(anns(), cerl(), cerl()) -> c_literal() | c_cons().
+
+ann_c_cons(As, #c_literal{val = Head}, #c_literal{val = Tail}) ->
+    #c_literal{val = [Head | Tail], anno = As};
+ann_c_cons(As, Head, Tail) ->
+    #c_cons{hd = Head, tl = Tail, anno = As}.
+
+
+%% @spec update_c_cons(Old::cerl(), Head::cerl(), Tail::cerl()) ->
+%%           cerl()
+%% @see c_cons/2
+
+-spec update_c_cons(c_literal() | c_cons(), cerl(), cerl()) ->
+        c_literal() | c_cons().
+
+update_c_cons(Node, #c_literal{val = Head}, #c_literal{val = Tail}) ->
+    #c_literal{val = [Head | Tail], anno = get_ann(Node)};
+update_c_cons(Node, Head, Tail) ->
+    #c_cons{hd = Head, tl = Tail, anno = get_ann(Node)}.
+
+
+%% @spec c_cons_skel(Head::cerl(), Tail::cerl()) -> c_cons()
+%%
+%% @doc Creates an abstract list constructor skeleton. Does not fold
+%% constant literals, i.e., the result always has type
+%% <code>cons</code>, representing "<code>[<em>Head</em> |
+%% <em>Tail</em>]</code>".
+%%
+%% <p>This function is occasionally useful when it is necessary to have
+%% annotations on the subnodes of a list constructor node, even when the
+%% subnodes are constant literals. Note however that
+%% <code>is_literal/1</code> will yield <code>false</code> and
+%% <code>concrete/1</code> will fail if passed the result from this
+%% function.</p>
+%%
+%% <p><code>fold_literal/1</code> can be used to revert a node to the
+%% normal-form representation.</p>
+%%
+%% @see ann_c_cons_skel/3
+%% @see update_c_cons_skel/3
+%% @see c_cons/2
+%% @see is_c_cons/1
+%% @see is_c_list/1
+%% @see c_nil/0
+%% @see is_literal/1
+%% @see fold_literal/1
+%% @see concrete/1
+
+%% *Never* collapse literals.
+
+-spec c_cons_skel(cerl(), cerl()) -> c_cons().
+
+c_cons_skel(Head, Tail) ->
+    #c_cons{hd = Head, tl = Tail}.
+
+
+%% @spec ann_c_cons_skel(As::anns(), Head::cerl(), Tail::cerl()) ->
+%%           c_cons()
+%% @see c_cons_skel/2
+
+-spec ann_c_cons_skel(anns(), cerl(), cerl()) -> c_cons().
+
+ann_c_cons_skel(As, Head, Tail) ->
+    #c_cons{hd = Head, tl = Tail, anno = As}.
+
+
+%% @spec update_c_cons_skel(Old::cerl(), Head::cerl(), Tail::cerl()) ->
+%%           c_cons()
+%% @see c_cons_skel/2
+
+-spec update_c_cons_skel(c_cons() | c_literal(), cerl(), cerl()) -> c_cons().
+
+update_c_cons_skel(Node, Head, Tail) ->
+    #c_cons{hd = Head, tl = Tail, anno = get_ann(Node)}.
+
+
+%% @spec is_c_cons(Node::cerl()) -> boolean()
+%%
+%% @doc Returns <code>true</code> if <code>Node</code> is an abstract
+%% list constructor, otherwise <code>false</code>.
+
+-spec is_c_cons(cerl()) -> boolean().
+
+is_c_cons(#c_cons{}) ->
+    true;
+is_c_cons(#c_literal{val = [_ | _]}) ->
+    true;
+is_c_cons(_) ->
+    false.
+
+
+%% @spec cons_hd(cerl()) -> cerl()
+%%
+%% @doc Returns the head subtree of an abstract list constructor.
+%%
+%% @see c_cons/2
+
+-spec cons_hd(c_cons() | c_literal()) -> cerl().
+
+cons_hd(#c_cons{hd = Head}) ->
+    Head;
+cons_hd(#c_literal{val = [Head | _]}) ->
+    #c_literal{val = Head}.
+
+
+%% @spec cons_tl(c_cons() | c_literal()) -> cerl()
+%%
+%% @doc Returns the tail subtree of an abstract list constructor.
+%%
+%% <p>Recall that the tail does not necessarily represent a proper
+%% list.</p>
+%%
+%% @see c_cons/2
+
+-spec cons_tl(c_cons() | c_literal()) -> cerl().
+
+cons_tl(#c_cons{tl = Tail}) ->
+    Tail;
+cons_tl(#c_literal{val = [_ | Tail]}) ->
+    #c_literal{val = Tail}.
+
+
+%% @spec is_c_list(Node::cerl()) -> boolean()
+%%
+%% @doc Returns <code>true</code> if <code>Node</code> represents a
+%% proper list, otherwise <code>false</code>. A proper list is either
+%% the empty list <code>[]</code>, or a cons cell <code>[<em>Head</em> |
+%% <em>Tail</em>]</code>, where recursively <code>Tail</code> is a
+%% proper list.
+%% 
+%% <p>Note: Because <code>Node</code> is a syntax tree, the actual
+%% run-time values corresponding to its subtrees may often be partially
+%% or completely unknown. Thus, if <code>Node</code> represents e.g.
+%% "<code>[... | Ns]</code>" (where <code>Ns</code> is a variable), then
+%% the function will return <code>false</code>, because it is not known
+%% whether <code>Ns</code> will be bound to a list at run-time. If
+%% <code>Node</code> instead represents e.g. "<code>[1, 2, 3]</code>" or
+%% "<code>[A | []]</code>", then the function will return
+%% <code>true</code>.</p>
+%%
+%% @see c_cons/2
+%% @see c_nil/0
+%% @see list_elements/1
+%% @see list_length/1
+
+-spec is_c_list(cerl()) -> boolean().
+
+is_c_list(#c_cons{tl = Tail}) ->
+    is_c_list(Tail);
+is_c_list(#c_literal{val = V}) ->
+    is_proper_list(V);
+is_c_list(_) ->
+    false.
+
+is_proper_list([_ | Tail]) ->
+    is_proper_list(Tail);
+is_proper_list([]) ->
+    true;
+is_proper_list(_) ->
+    false.
+
+%% @spec list_elements(c_cons() | c_literal()) -> [cerl()]
+%%
+%% @doc Returns the list of element subtrees of an abstract list.
+%% <code>Node</code> must represent a proper list. E.g., if
+%% <code>Node</code> represents "<code>[<em>X1</em>, <em>X2</em> |
+%% [<em>X3</em>, <em>X4</em> | []]</code>", then
+%% <code>list_elements(Node)</code> yields the list <code>[X1, X2, X3,
+%% X4]</code>.
+%%
+%% @see c_cons/2
+%% @see c_nil/0
+%% @see is_c_list/1
+%% @see list_length/1
+%% @see make_list/2
+
+-spec list_elements(c_cons() | c_literal()) -> [cerl()].
+
+list_elements(#c_cons{hd = Head, tl = Tail}) ->
+    [Head | list_elements(Tail)];
+list_elements(#c_literal{val = V}) ->
+    abstract_list(V).
+
+abstract_list([X | Xs]) ->
+    [abstract(X) | abstract_list(Xs)];
+abstract_list([]) ->
+    [].
+
+
+%% @spec list_length(Node::c_cons() | c_literal()) -> integer()
+%%
+%% @doc Returns the number of element subtrees of an abstract list.
+%% <code>Node</code> must represent a proper list. E.g., if
+%% <code>Node</code> represents "<code>[X1 | [X2, X3 | [X4, X5,
+%% X6]]]</code>", then <code>list_length(Node)</code> returns the
+%% integer 6.
+%%
+%% <p>Note: this is equivalent to
+%% <code>length(list_elements(Node))</code>, but potentially more
+%% efficient.</p>
+%%
+%% @see c_cons/2
+%% @see c_nil/0
+%% @see is_c_list/1
+%% @see list_elements/1
+
+-spec list_length(c_cons() | c_literal()) -> non_neg_integer().
+
+list_length(L) ->
+    list_length(L, 0).
+
+list_length(#c_cons{tl = Tail}, A) ->
+    list_length(Tail, A + 1);
+list_length(#c_literal{val = V}, A) ->
+    A + length(V).
+
+
+%% @spec make_list(List) -> Node
+%% @equiv make_list(List, none)
+
+-spec make_list([cerl()]) -> cerl().
+
+make_list(List) ->
+    ann_make_list([], List).
+
+
+%% @spec make_list(List::[cerl()], Tail) -> cerl()
+%%
+%%	    Tail = cerl() | none
+%%
+%% @doc Creates an abstract list from the elements in <code>List</code>
+%% and the optional <code>Tail</code>. If <code>Tail</code> is
+%% <code>none</code>, the result will represent a nil-terminated list,
+%% otherwise it represents "<code>[... | <em>Tail</em>]</code>".
+%%
+%% @see c_cons/2
+%% @see c_nil/0
+%% @see ann_make_list/3
+%% @see update_list/3
+%% @see list_elements/1
+
+-spec make_list([cerl()], cerl() | 'none') -> cerl().
+
+make_list(List, Tail) ->
+    ann_make_list([], List, Tail).
+
+
+%% @spec update_list(Old::cerl(), List::[cerl()]) -> cerl()
+%% @equiv update_list(Old, List, none)
+
+-spec update_list(cerl(), [cerl()]) -> cerl().
+
+update_list(Node, List) ->
+    ann_make_list(get_ann(Node), List).
+
+
+%% @spec update_list(Old::cerl(), List::[cerl()], Tail) -> cerl()
+%%
+%%	    Tail = cerl() | none
+%%
+%% @see make_list/2
+%% @see update_list/2
+
+-spec update_list(cerl(), [cerl()], cerl() | 'none') -> cerl().
+
+update_list(Node, List, Tail) ->
+    ann_make_list(get_ann(Node), List, Tail).
+
+
+%% @spec ann_make_list(As::anns(), List::[cerl()]) -> cerl()
+%% @equiv ann_make_list(As, List, none)
+
+-spec ann_make_list(anns(), [cerl()]) -> cerl().
+
+ann_make_list(As, List) ->
+    ann_make_list(As, List, none).
+
+
+%% @spec ann_make_list(As::anns(), List::[cerl()], Tail) -> cerl()
+%%
+%%	    Tail = cerl() | none
+%%
+%% @see make_list/2
+%% @see ann_make_list/2
+
+-spec ann_make_list(anns(), [cerl()], cerl() | 'none') -> cerl().
+
+ann_make_list(As, [H | T], Tail) ->
+    ann_c_cons(As, H, make_list(T, Tail));    % `c_cons' folds literals
+ann_make_list(As, [], none) ->
+    ann_c_nil(As);
+ann_make_list(_, [], Node) ->
+    Node.
+
+
+%% ---------------------------------------------------------------------
+%% maps
+
+%% @spec is_c_map(Node::cerl()) -> boolean()
+%%
+%% @doc Returns <code>true</code> if <code>Node</code> is an abstract
+%% map constructor, otherwise <code>false</code>.
+
+-spec is_c_map(cerl()) -> boolean().
+
+is_c_map(#c_map{}) ->
+    true;
+is_c_map(#c_literal{val = V}) when is_map(V) ->
+    true;
+is_c_map(_) ->
+    false.
+
+-spec map_es(c_map() | c_literal()) -> [c_map_pair()].
+
+map_es(#c_literal{anno=As,val=M}) when is_map(M) ->
+    [ann_c_map_pair(As,
+                    #c_literal{anno=As,val='assoc'},
+                    #c_literal{anno=As,val=K},
+                    #c_literal{anno=As,val=V}) || {K,V} <- maps:to_list(M)];
+map_es(#c_map{es = Es}) ->
+    Es.
+
+-spec map_arg(c_map() | c_literal()) -> c_map() | c_literal().
+
+map_arg(#c_literal{anno=As,val=M}) when is_map(M) ->
+    #c_literal{anno=As,val=#{}};
+map_arg(#c_map{arg=M}) ->
+    M.
+
+-spec c_map([c_map_pair()]) -> c_map().
+
+c_map(Pairs) ->
+    ann_c_map([], Pairs).
+
+-spec c_map_pattern([c_map_pair()]) -> c_map().
+
+c_map_pattern(Pairs) ->
+    #c_map{es=Pairs, is_pat=true}.
+
+-spec ann_c_map_pattern([term()], [c_map_pair()]) -> c_map().
+
+ann_c_map_pattern(As, Pairs) ->
+    #c_map{anno=As, es=Pairs, is_pat=true}.
+
+-spec is_c_map_empty(c_map() | c_literal()) -> boolean().
+
+is_c_map_empty(#c_map{ es=[] }) -> true;
+is_c_map_empty(#c_literal{val=M}) when is_map(M),map_size(M) =:= 0 -> true;
+is_c_map_empty(_) -> false.
+
+-spec is_c_map_pattern(c_map()) -> boolean().
+
+is_c_map_pattern(#c_map{is_pat=IsPat}) ->
+    IsPat.
+
+-spec ann_c_map([term()], [c_map_pair()]) -> c_map() | c_literal().
+
+ann_c_map(As, Es) ->
+    ann_c_map(As, #c_literal{val=#{}}, Es).
+
+-spec ann_c_map(anns(), c_map() | c_literal(), [c_map_pair()]) -> c_map() | c_literal().
+
+ann_c_map(As, #c_literal{val=M}, Es) when is_map(M) ->
+    fold_map_pairs(As,Es,M);
+ann_c_map(As, M, Es) ->
+    #c_map{arg=M, es=Es, anno=As}.
+
+fold_map_pairs(As,[],M) -> #c_literal{anno=As,val=M};
+%% M#{ K => V}
+fold_map_pairs(As,[#c_map_pair{op=#c_literal{val=assoc},key=Ck,val=Cv}=E|Es],M) ->
+    case is_lit_list([Ck,Cv]) of
+	true ->
+	    [K,V] = lit_list_vals([Ck,Cv]),
+	    fold_map_pairs(As,Es,maps:put(K,V,M));
+	false ->
+	    #c_map{arg=#c_literal{val=M,anno=As}, es=[E|Es], anno=As}
+    end;
+%% M#{ K := V}
+fold_map_pairs(As,[#c_map_pair{op=#c_literal{val=exact},key=Ck,val=Cv}=E|Es],M) ->
+    case is_lit_list([Ck,Cv]) of
+	true ->
+	    [K,V] = lit_list_vals([Ck,Cv]),
+	    case maps:is_key(K,M) of
+		true -> fold_map_pairs(As,Es,maps:put(K,V,M));
+		false ->
+		    #c_map{arg=#c_literal{val=M,anno=As}, es=[E|Es], anno=As }
+	    end;
+	false ->
+	    #c_map{arg=#c_literal{val=M,anno=As}, es=[E|Es], anno=As }
+    end.
+
+-spec update_c_map(c_map(), cerl(), [cerl()]) -> c_map() | c_literal().
+
+update_c_map(#c_map{is_pat=true}=Old, M, Es) ->
+    Old#c_map{arg=M, es=Es};
+update_c_map(#c_map{is_pat=false}=Old, M, Es) ->
+    ann_c_map(get_ann(Old), M, Es).
+
+map_pair_key(#c_map_pair{key=K}) -> K.
+map_pair_val(#c_map_pair{val=V}) -> V.
+map_pair_op(#c_map_pair{op=Op}) -> Op.
+
+-spec c_map_pair(cerl(), cerl()) -> c_map_pair().
+
+c_map_pair(Key,Val) ->
+    #c_map_pair{op=#c_literal{val=assoc},key=Key,val=Val}.
+
+-spec c_map_pair_exact(cerl(), cerl()) -> c_map_pair().
+
+c_map_pair_exact(Key,Val) ->
+    #c_map_pair{op=#c_literal{val=exact},key=Key,val=Val}.
+
+-spec ann_c_map_pair(anns(), cerl(), cerl(), cerl()) ->
+        c_map_pair().
+
+ann_c_map_pair(As,Op,K,V) ->
+    #c_map_pair{op = Op, key = K, val = V, anno = As}.
+
+update_c_map_pair(Old,Op,K,V) ->
+    #c_map_pair{op = Op, key = K, val = V, anno = get_ann(Old)}.
+
+
+%% ---------------------------------------------------------------------
+
+%% @spec c_tuple(Elements::[cerl()]) -> cerl()
+%%
+%% @doc Creates an abstract tuple. If <code>Elements</code> is
+%% <code>[E1, ..., En]</code>, the result represents
+%% "<code>{<em>E1</em>, ..., <em>En</em>}</code>".  Note that if all
+%% nodes in <code>Elements</code> have type <code>literal</code>, or if
+%% <code>Elements</code> is empty, then the result will also have type
+%% <code>literal</code> and annotations on nodes in
+%% <code>Elements</code> are lost.
+%%
+%% <p>Recall that Erlang has distinct 1-tuples, i.e., <code>{X}</code>
+%% is always distinct from <code>X</code> itself.</p>
+%%
+%% @see ann_c_tuple/2
+%% @see update_c_tuple/2
+%% @see is_c_tuple/1
+%% @see tuple_es/1
+%% @see tuple_arity/1
+%% @see c_tuple_skel/1
+
+%% *Always* collapse literals.
+
+-spec c_tuple([cerl()]) -> c_tuple() | c_literal().
+
+c_tuple(Es) ->
+    case is_lit_list(Es) of
+	false ->
+	    #c_tuple{es = Es};
+	true ->
+	    #c_literal{val = list_to_tuple(lit_list_vals(Es))}
+    end.
+
+
+%% @spec ann_c_tuple(As::anns(), Elements::[cerl()]) -> cerl()
+%% @see c_tuple/1
+
+-spec ann_c_tuple(anns(), [cerl()]) -> c_tuple() | c_literal().
+
+ann_c_tuple(As, Es) ->
+    case is_lit_list(Es) of
+	false ->
+	    #c_tuple{es = Es, anno = As};
+	true ->
+	    #c_literal{val = list_to_tuple(lit_list_vals(Es)), anno = As}
+    end.
+
+
+%% @spec update_c_tuple(Old::cerl(), Elements::[cerl()]) -> cerl()
+%% @see c_tuple/1
+
+-spec update_c_tuple(c_tuple() | c_literal(), [cerl()]) -> c_tuple() | c_literal().
+
+update_c_tuple(Node, Es) ->
+    case is_lit_list(Es) of
+	false ->
+	    #c_tuple{es = Es, anno = get_ann(Node)};
+	true ->
+	    #c_literal{val = list_to_tuple(lit_list_vals(Es)),
+		       anno = get_ann(Node)}
+    end.
+
+
+%% @spec c_tuple_skel(Elements::[cerl()]) -> cerl()
+%%
+%% @doc Creates an abstract tuple skeleton. Does not fold constant
+%% literals, i.e., the result always has type <code>tuple</code>,
+%% representing "<code>{<em>E1</em>, ..., <em>En</em>}</code>", if
+%% <code>Elements</code> is <code>[E1, ..., En]</code>.
+%% 
+%% <p>This function is occasionally useful when it is necessary to have
+%% annotations on the subnodes of a tuple node, even when all the
+%% subnodes are constant literals. Note however that
+%% <code>is_literal/1</code> will yield <code>false</code> and
+%% <code>concrete/1</code> will fail if passed the result from this
+%% function.</p>
+%%
+%% <p><code>fold_literal/1</code> can be used to revert a node to the
+%% normal-form representation.</p>
+%%
+%% @see ann_c_tuple_skel/2
+%% @see update_c_tuple_skel/2
+%% @see c_tuple/1
+%% @see tuple_es/1
+%% @see is_c_tuple/1
+%% @see is_literal/1
+%% @see fold_literal/1
+%% @see concrete/1
+
+%% *Never* collapse literals.
+
+-spec c_tuple_skel([cerl()]) -> c_tuple().
+
+c_tuple_skel(Es) ->
+    #c_tuple{es = Es}.
+
+
+%% @spec ann_c_tuple_skel(As::anns(), Elements::[cerl()]) -> cerl()
+%% @see c_tuple_skel/1
+
+-spec ann_c_tuple_skel(anns(), [cerl()]) -> c_tuple().
+
+ann_c_tuple_skel(As, Es) ->
+    #c_tuple{es = Es, anno = As}.
+
+
+%% @spec update_c_tuple_skel(Old::cerl(), Elements::[cerl()]) -> cerl()
+%% @see c_tuple_skel/1
+
+-spec update_c_tuple_skel(c_tuple(), [cerl()]) -> c_tuple().
+
+update_c_tuple_skel(Old, Es) ->
+    #c_tuple{es = Es, anno = get_ann(Old)}.
+
+
+%% @spec is_c_tuple(Node::cerl()) -> boolean()
+%%
+%% @doc Returns <code>true</code> if <code>Node</code> is an abstract
+%% tuple, otherwise <code>false</code>.
+%%
+%% @see c_tuple/1
+
+-spec is_c_tuple(cerl()) -> boolean().
+
+is_c_tuple(#c_tuple{}) ->
+    true;
+is_c_tuple(#c_literal{val = V}) when is_tuple(V) ->
+    true;
+is_c_tuple(_) ->
+    false.
+
+
+%% @spec tuple_es(cerl()) -> [cerl()]
+%%
+%% @doc Returns the list of element subtrees of an abstract tuple.
+%%
+%% @see c_tuple/1
+
+-spec tuple_es(c_tuple() | c_literal()) -> [cerl()].
+
+tuple_es(#c_tuple{es = Es}) ->
+    Es;
+tuple_es(#c_literal{val = V}) ->
+    make_lit_list(tuple_to_list(V)).
+
+
+%% @spec tuple_arity(Node::cerl()) -> integer()
+%%
+%% @doc Returns the number of element subtrees of an abstract tuple.
+%%
+%% <p>Note: this is equivalent to <code>length(tuple_es(Node))</code>,
+%% but potentially more efficient.</p>
+%%
+%% @see tuple_es/1
+%% @see c_tuple/1
+
+-spec tuple_arity(c_tuple() | c_literal()) -> non_neg_integer().
+
+tuple_arity(#c_tuple{es = Es}) ->
+    length(Es);
+tuple_arity(#c_literal{val = V}) when is_tuple(V) ->
+    tuple_size(V).
+
+
+%% ---------------------------------------------------------------------
+
+%% @spec c_var(Name::var_name()) -> cerl()
+%%
+%%     var_name() = integer() | atom() | {atom(), arity()}
+%%
+%% @doc Creates an abstract variable. A variable is identified by its
+%% name, given by the <code>Name</code> parameter.
+%%
+%% <p>If a name is given by a single atom, it should either be a
+%% "simple" atom which does not need to be single-quoted in Erlang, or
+%% otherwise its print name should correspond to a proper Erlang
+%% variable, i.e., begin with an uppercase character or an
+%% underscore. Names on the form <code>{A, N}</code> represent
+%% function name variables "<code><em>A</em>/<em>N</em></code>"; these
+%% are special variables which may be bound only in the function
+%% definitions of a module or a <code>letrec</code>.  They may not be
+%% bound in <code>let</code> expressions and cannot occur in clause
+%% patterns. The atom <code>A</code> in a function name may be any
+%% atom; the integer <code>N</code> must be nonnegative. The functions
+%% <code>c_fname/2</code> etc. are utilities for handling function
+%% name variables.</p>
+%%
+%% <p>When printing variable names, they must have the form of proper
+%% Core Erlang variables and function names. E.g., a name represented
+%% by an integer such as <code>42</code> could be formatted as
+%% "<code>_42</code>", an atom <code>'Xxx'</code> simply as
+%% "<code>Xxx</code>", and an atom <code>foo</code> as
+%% "<code>_foo</code>". However, one must assure that any two valid
+%% distinct names are never mapped to the same strings.  Tuples such
+%% as <code>{foo, 2}</code> representing function names can simply by
+%% formatted as "<code>'foo'/2</code>", with no risk of conflicts.</p>
+%%
+%% @see ann_c_var/2
+%% @see update_c_var/2
+%% @see is_c_var/1
+%% @see var_name/1
+%% @see c_fname/2
+%% @see c_module/4
+%% @see c_letrec/2
+
+-spec c_var(var_name()) -> c_var().
+
+c_var(Name) ->
+    #c_var{name = Name}.
+
+
+%% @spec ann_c_var(As::anns(), Name::var_name()) -> c_var()
+%%
+%% @see c_var/1
+
+-spec ann_c_var(anns(), var_name()) -> c_var().
+
+ann_c_var(As, Name) ->
+    #c_var{name = Name, anno = As}.
+
+%% @spec update_c_var(Old::cerl(), Name::var_name()) -> c_var()
+%%
+%% @see c_var/1
+
+-spec update_c_var(c_var(), var_name()) -> c_var().
+
+update_c_var(Node, Name) ->
+    #c_var{name = Name, anno = get_ann(Node)}.
+
+
+%% @spec is_c_var(Node::cerl()) -> boolean()
+%%
+%% @doc Returns <code>true</code> if <code>Node</code> is an abstract
+%% variable, otherwise <code>false</code>.
+%%
+%% @see c_var/1
+
+-spec is_c_var(cerl()) -> boolean().
+
+is_c_var(#c_var{}) ->
+    true;
+is_c_var(_) ->
+    false.
+
+
+%% @spec c_fname(Name::atom(), Arity::arity()) -> c_var()
+%% @equiv c_var({Name, Arity})
+%% @see fname_id/1
+%% @see fname_arity/1
+%% @see is_c_fname/1
+%% @see ann_c_fname/3
+%% @see update_c_fname/3
+
+-spec c_fname(atom(), arity()) -> c_var().
+
+c_fname(Atom, Arity) ->
+    c_var({Atom, Arity}).
+
+
+%% @spec ann_c_fname(As::anns(), Name::atom(), Arity::arity()) -> c_var()
+%%
+%% @equiv ann_c_var(As, {Atom, Arity})
+%% @see c_fname/2
+
+-spec ann_c_fname(anns(), atom(), arity()) -> c_var().
+
+ann_c_fname(As, Atom, Arity) ->
+    ann_c_var(As, {Atom, Arity}).
+
+
+%% @spec update_c_fname(Old::c_var(), Name::atom()) -> c_var()
+%% @doc Like <code>update_c_fname/3</code>, but takes the arity from
+%% <code>Node</code>.
+%% @see update_c_fname/3
+%% @see c_fname/2
+
+-spec update_c_fname(c_var(), atom()) -> c_var().
+
+update_c_fname(#c_var{name = {_, Arity}, anno = As}, Atom) ->
+    #c_var{name = {Atom, Arity}, anno = As}.
+
+
+%% @spec update_c_fname(Old::var(), Name::atom(), Arity::arity()) -> c_var()
+%%
+%% @equiv update_c_var(Old, {Atom, Arity})
+%% @see update_c_fname/2
+%% @see c_fname/2
+
+-spec update_c_fname(c_var(), atom(), arity()) -> c_var().
+
+update_c_fname(Node, Atom, Arity) ->
+    update_c_var(Node, {Atom, Arity}).
+
+
+%% @spec is_c_fname(Node::cerl()) -> boolean()
+%%
+%% @doc Returns <code>true</code> if <code>Node</code> is an abstract
+%% function name variable, otherwise <code>false</code>.
+%%
+%% @see c_fname/2
+%% @see c_var/1
+%% @see var_name/1
+
+-spec is_c_fname(cerl()) -> boolean().
+
+is_c_fname(#c_var{name = {A, N}}) when is_atom(A), is_integer(N), N >= 0 ->
+    true;
+is_c_fname(_) ->
+    false.
+
+
+%% @spec var_name(c_var()) -> var_name()
+%%
+%% @doc Returns the name of an abstract variable.
+%%
+%% @see c_var/1
+
+-spec var_name(c_var()) -> var_name().
+
+var_name(Node) ->
+    Node#c_var.name.
+
+
+%% @spec fname_id(c_var()) -> atom()
+%%
+%% @doc Returns the identifier part of an abstract function name
+%% variable.
+%% 
+%% @see fname_arity/1
+%% @see c_fname/2
+
+-spec fname_id(c_var()) -> atom().
+
+fname_id(#c_var{name={A,_}}) ->
+    A.
+
+
+%% @spec fname_arity(c_var()) -> arity()
+%%
+%% @doc Returns the arity part of an abstract function name variable.
+%%
+%% @see fname_id/1
+%% @see c_fname/2
+
+-spec fname_arity(c_var()) -> arity().
+
+fname_arity(#c_var{name={_,N}}) ->
+    N.
+
+
+%% ---------------------------------------------------------------------
+
+%% @spec c_values(Elements::[cerl()]) -> c_values()
+%%
+%% @doc Creates an abstract value list. If <code>Elements</code> is
+%% <code>[E1, ..., En]</code>, the result represents
+%% "<code>&lt;<em>E1</em>, ..., <em>En</em>&gt;</code>".
+%%
+%% @see ann_c_values/2
+%% @see update_c_values/2
+%% @see is_c_values/1
+%% @see values_es/1
+%% @see values_arity/1
+
+-spec c_values([cerl()]) -> c_values().
+
+c_values(Es) ->
+    #c_values{es = Es}.
+
+
+%% @spec ann_c_values(As::anns(), Elements::[cerl()]) -> c_values()
+%% @see c_values/1
+
+-spec ann_c_values(anns(), [cerl()]) -> c_values().
+
+ann_c_values(As, Es) ->
+    #c_values{es = Es, anno = As}.
+
+
+%% @spec update_c_values(Old::cerl(), Elements::[cerl()]) -> c_values()
+%% @see c_values/1
+
+-spec update_c_values(c_values(), [cerl()]) -> c_values().
+
+update_c_values(Node, Es) ->
+    #c_values{es = Es, anno = get_ann(Node)}.
+
+
+%% @spec is_c_values(Node::cerl()) -> boolean()
+%%
+%% @doc Returns <code>true</code> if <code>Node</code> is an abstract
+%% value list; otherwise <code>false</code>.
+%%
+%% @see c_values/1
+
+-spec is_c_values(cerl()) -> boolean().
+
+is_c_values(#c_values{}) ->
+    true;
+is_c_values(_) ->
+    false.
+
+
+%% @spec values_es(c_values()) -> [cerl()]
+%%
+%% @doc Returns the list of element subtrees of an abstract value
+%% list.
+%%
+%% @see c_values/1
+%% @see values_arity/1
+
+-spec values_es(c_values()) -> [cerl()].
+
+values_es(Node) ->
+    Node#c_values.es.
+
+
+%% @spec values_arity(Node::c_values()) -> non_neg_integer()
+%%
+%% @doc Returns the number of element subtrees of an abstract value
+%% list.
+%% 
+%% <p>Note: This is equivalent to
+%% <code>length(values_es(Node))</code>, but potentially more
+%% efficient.</p>
+%%
+%% @see c_values/1
+%% @see values_es/1
+
+-spec values_arity(c_values()) -> non_neg_integer().
+
+values_arity(Node) ->
+    length(values_es(Node)).
+
+
+%% ---------------------------------------------------------------------
+
+%% @spec c_binary(Segments::[c_bitstr()]) -> c_binary()
+%%
+%% @doc Creates an abstract binary-template. A binary object is a
+%% sequence of 8-bit bytes. It is specified by zero or more bit-string
+%% template <em>segments</em> of arbitrary lengths (in number of bits),
+%% such that the sum of the lengths is evenly divisible by 8. If
+%% <code>Segments</code> is <code>[S1, ..., Sn]</code>, the result
+%% represents "<code>#{<em>S1</em>, ..., <em>Sn</em>}#</code>". All the
+%% <code>Si</code> must have type <code>bitstr</code>.
+%%
+%% @see ann_c_binary/2
+%% @see update_c_binary/2
+%% @see is_c_binary/1
+%% @see binary_segments/1
+%% @see c_bitstr/5
+
+-spec c_binary([c_bitstr()]) -> c_binary().
+
+c_binary(Segments) ->
+    #c_binary{segments = Segments}.
+
+
+%% @spec ann_c_binary(As::anns(), Segments::[c_bitstr()]) -> c_binary()
+%% @see c_binary/1
+
+-spec ann_c_binary(anns(), [c_bitstr()]) -> c_binary().
+
+ann_c_binary(As, Segments) ->
+    #c_binary{segments = Segments, anno = As}.
+
+
+%% @spec update_c_binary(Old::cerl(), Segments::[c_bitstr()]) -> cerl()
+%% @see c_binary/1
+
+-spec update_c_binary(c_binary(), [c_bitstr()]) -> c_binary().
+
+update_c_binary(Node, Segments) ->
+    #c_binary{segments = Segments, anno = get_ann(Node)}.
+
+
+%% @spec is_c_binary(Node::cerl()) -> boolean()
+%%
+%% @doc Returns <code>true</code> if <code>Node</code> is an abstract
+%% binary-template; otherwise <code>false</code>.
+%%
+%% @see c_binary/1
+
+-spec is_c_binary(cerl()) -> boolean().
+
+is_c_binary(#c_binary{}) ->
+    true;
+is_c_binary(_) ->
+    false.
+
+
+%% @spec binary_segments(cerl()) -> [c_bitstr()]
+%%
+%% @doc Returns the list of segment subtrees of an abstract
+%% binary-template.
+%%
+%% @see c_binary/1
+%% @see c_bitstr/5
+
+-spec binary_segments(c_binary()) -> [c_bitstr()].
+
+binary_segments(Node) ->
+    Node#c_binary.segments.
+
+
+%% @spec c_bitstr(Value::cerl(), Size::cerl(), Unit::cerl(),
+%%                Type::cerl(), Flags::cerl()) -> c_bitstr()
+%%
+%% @doc Creates an abstract bit-string template. These can only occur as
+%% components of an abstract binary-template (see {@link c_binary/1}).
+%% The result represents "<code>#&lt;<em>Value</em>&gt;(<em>Size</em>,
+%% <em>Unit</em>, <em>Type</em>, <em>Flags</em>)</code>", where
+%% <code>Unit</code> must represent a positive integer constant,
+%% <code>Type</code> must represent a constant atom (one of
+%% <code>'integer'</code>, <code>'float'</code>, or
+%% <code>'binary'</code>), and <code>Flags</code> must represent a
+%% constant list <code>"[<em>F1</em>, ..., <em>Fn</em>]"</code> where
+%% all the <code>Fi</code> are atoms.
+%% 
+%% @see c_binary/1
+%% @see ann_c_bitstr/6
+%% @see update_c_bitstr/6
+%% @see is_c_bitstr/1
+%% @see bitstr_val/1
+%% @see bitstr_size/1
+%% @see bitstr_unit/1
+%% @see bitstr_type/1
+%% @see bitstr_flags/1
+
+-spec c_bitstr(cerl(), cerl(), cerl(), cerl(), cerl()) -> c_bitstr().
+
+c_bitstr(Val, Size, Unit, Type, Flags) ->
+    #c_bitstr{val = Val, size = Size, unit = Unit, type = Type,
+	      flags = Flags}.
+
+
+%% @spec c_bitstr(Value::cerl(), Size::cerl(), Type::cerl(),
+%%                Flags::cerl()) -> c_bitstr()
+%% @equiv c_bitstr(Value, Size, abstract(1), Type, Flags)
+
+-spec c_bitstr(cerl(), cerl(), cerl(), cerl()) -> c_bitstr().
+
+c_bitstr(Val, Size, Type, Flags) ->
+    c_bitstr(Val, Size, abstract(1), Type, Flags).
+
+
+%% @spec c_bitstr(Value::cerl(), Type::cerl(),
+%%                Flags::cerl()) -> c_bitstr()
+%% @equiv c_bitstr(Value, abstract(all), abstract(1), Type, Flags)
+
+-spec c_bitstr(cerl(), cerl(), cerl()) -> c_bitstr().
+
+c_bitstr(Val, Type, Flags) ->
+    c_bitstr(Val, abstract(all), abstract(1), Type, Flags).
+
+
+%% @spec ann_c_bitstr(As::anns(), Value::cerl(), Size::cerl(),
+%%                    Unit::cerl(), Type::cerl(), Flags::cerl()) -> cerl()
+%% @see c_bitstr/5
+%% @see ann_c_bitstr/5
+
+-spec ann_c_bitstr(anns(), cerl(), cerl(), cerl(), cerl(), cerl()) ->
+        c_bitstr().
+
+ann_c_bitstr(As, Val, Size, Unit, Type, Flags) ->
+    #c_bitstr{val = Val, size = Size, unit = Unit, type = Type,
+	      flags = Flags, anno = As}.
+
+%% @spec ann_c_bitstr(As::anns(), Value::cerl(), Size::cerl(),
+%%                    Type::cerl(), Flags::cerl()) -> c_bitstr()
+%% @equiv ann_c_bitstr(As, Value, Size, abstract(1), Type, Flags)
+
+-spec ann_c_bitstr(anns(), cerl(), cerl(), cerl(), cerl()) -> c_bitstr().
+
+ann_c_bitstr(As, Value, Size, Type, Flags) ->
+    ann_c_bitstr(As, Value, Size, abstract(1), Type, Flags).
+
+
+%% @spec update_c_bitstr(Old::c_bitstr(), Value::cerl(), Size::cerl(),
+%%           Unit::cerl(), Type::cerl(), Flags::cerl()) -> c_bitstr()
+%% @see c_bitstr/5
+%% @see update_c_bitstr/5
+
+-spec update_c_bitstr(c_bitstr(), cerl(), cerl(), cerl(), cerl(), cerl()) ->
+        c_bitstr().
+
+update_c_bitstr(Node, Val, Size, Unit, Type, Flags) ->
+    #c_bitstr{val = Val, size = Size, unit = Unit, type = Type,
+	     flags = Flags, anno = get_ann(Node)}.
+
+
+%% @spec update_c_bitstr(Old::c_bitstr(), Value::cerl(), Size::cerl(),
+%%                       Type::cerl(), Flags::cerl()) -> c_bitstr()
+%% @equiv update_c_bitstr(Node, Value, Size, abstract(1), Type, Flags)
+
+-spec update_c_bitstr(c_bitstr(), cerl(), cerl(), cerl(), cerl()) -> c_bitstr().
+
+update_c_bitstr(Node, Value, Size, Type, Flags) ->
+    update_c_bitstr(Node, Value, Size, abstract(1), Type, Flags).
+
+%% @spec is_c_bitstr(Node::cerl()) -> boolean()
+%%
+%% @doc Returns <code>true</code> if <code>Node</code> is an abstract
+%% bit-string template; otherwise <code>false</code>.
+%%
+%% @see c_bitstr/5
+
+-spec is_c_bitstr(cerl()) -> boolean().
+
+is_c_bitstr(#c_bitstr{}) ->
+    true;
+is_c_bitstr(_) ->
+    false.
+
+
+%% @spec bitstr_val(c_bitstr()) -> cerl()
+%%
+%% @doc Returns the value subtree of an abstract bit-string template.
+%%
+%% @see c_bitstr/5
+
+-spec bitstr_val(c_bitstr()) -> cerl().
+
+bitstr_val(Node) ->
+    Node#c_bitstr.val.
+
+
+%% @spec bitstr_size(c_bitstr()) -> cerl()
+%%
+%% @doc Returns the size subtree of an abstract bit-string template.
+%%
+%% @see c_bitstr/5
+
+-spec bitstr_size(c_bitstr()) -> cerl().
+
+bitstr_size(Node) ->
+    Node#c_bitstr.size.
+
+
+%% @spec bitstr_bitsize(c_bitstr()) -> any | all | utf | integer()
+%%
+%% @doc Returns the total size in bits of an abstract bit-string
+%% template. If the size field is an integer literal, the result is the
+%% product of the size and unit values; if the size field is the atom
+%% literal <code>all</code>, the atom <code>all</code> is returned.
+%% If the size is not a literal, the atom <code>any</code> is returned.
+%%
+%% @see c_bitstr/5
+
+-spec bitstr_bitsize(c_bitstr()) -> 'all' | 'any' | 'utf' | non_neg_integer().
+
+bitstr_bitsize(Node) ->
+    Size = Node#c_bitstr.size,
+    case is_literal(Size) of
+	true ->
+	    case concrete(Size) of
+		all ->
+		    all;
+		undefined ->
+		     %% just an assertion below
+		    "utf" ++ _ = atom_to_list(concrete(Node#c_bitstr.type)),
+		    utf;
+		S when is_integer(S) ->
+		    S * concrete(Node#c_bitstr.unit)
+	    end;
+	false ->
+	    any
+    end.
+
+
+%% @spec bitstr_unit(c_bitstr()) -> cerl()
+%%
+%% @doc Returns the unit subtree of an abstract bit-string template.
+%%
+%% @see c_bitstr/5
+
+-spec bitstr_unit(c_bitstr()) -> cerl().
+
+bitstr_unit(Node) ->
+    Node#c_bitstr.unit.
+
+
+%% @spec bitstr_type(c_bitstr()) -> cerl()
+%%
+%% @doc Returns the type subtree of an abstract bit-string template.
+%%
+%% @see c_bitstr/5
+
+-spec bitstr_type(c_bitstr()) -> cerl().
+
+bitstr_type(Node) ->
+    Node#c_bitstr.type.
+
+
+%% @spec bitstr_flags(c_bitstr()) -> cerl()
+%%
+%% @doc Returns the flags subtree of an abstract bit-string template.
+%%
+%% @see c_bitstr/5
+
+-spec bitstr_flags(c_bitstr()) -> cerl().
+
+bitstr_flags(Node) ->
+    Node#c_bitstr.flags.
+
+
+%% ---------------------------------------------------------------------
+
+%% @spec c_fun(Variables::[c_var()], Body::cerl()) -> c_fun()
+%%
+%% @doc Creates an abstract fun-expression. If <code>Variables</code>
+%% is <code>[V1, ..., Vn]</code>, the result represents "<code>fun
+%% (<em>V1</em>, ..., <em>Vn</em>) -> <em>Body</em></code>". All the
+%% <code>Vi</code> must have type <code>var</code>.
+%%
+%% @see ann_c_fun/3
+%% @see update_c_fun/3
+%% @see is_c_fun/1
+%% @see fun_vars/1
+%% @see fun_body/1
+%% @see fun_arity/1
+
+-spec c_fun([c_var()], cerl()) -> c_fun().
+
+c_fun(Variables, Body) ->
+    #c_fun{vars = Variables, body = Body}.
+
+
+%% @spec ann_c_fun(As::anns(), Variables::[c_var()], Body::cerl()) ->
+%%           c_fun()
+%% @see c_fun/2
+
+-spec ann_c_fun(anns(), [c_var()], cerl()) -> c_fun().
+
+ann_c_fun(As, Variables, Body) ->
+    #c_fun{vars = Variables, body = Body, anno = As}.
+
+
+%% @spec update_c_fun(Old::c_fun(), Variables::[c_var()],
+%%                    Body::cerl()) -> c_fun()
+%% @see c_fun/2
+
+-spec update_c_fun(c_fun(), [c_var()], cerl()) -> c_fun().
+
+update_c_fun(Node, Variables, Body) ->
+    #c_fun{vars = Variables, body = Body, anno = get_ann(Node)}.
+
+
+%% @spec is_c_fun(Node::cerl()) -> boolean()
+%%
+%% @doc Returns <code>true</code> if <code>Node</code> is an abstract
+%% fun-expression, otherwise <code>false</code>.
+%%
+%% @see c_fun/2
+
+-spec is_c_fun(cerl()) -> boolean().
+
+is_c_fun(#c_fun{}) ->
+    true;		% Now this is fun!
+is_c_fun(_) ->
+    false.
+
+
+%% @spec fun_vars(c_fun()) -> [c_var()]
+%%
+%% @doc Returns the list of parameter subtrees of an abstract
+%% fun-expression.
+%%
+%% @see c_fun/2
+%% @see fun_arity/1
+
+-spec fun_vars(c_fun()) -> [c_var()].
+
+fun_vars(Node) ->
+    Node#c_fun.vars.
+
+
+%% @spec fun_body(c_fun()) -> cerl()
+%%
+%% @doc Returns the body subtree of an abstract fun-expression.
+%%
+%% @see c_fun/2
+
+-spec fun_body(c_fun()) -> cerl().
+
+fun_body(Node) ->
+    Node#c_fun.body.
+
+
+%% @spec fun_arity(Node::c_fun()) -> arity()
+%%
+%% @doc Returns the number of parameter subtrees of an abstract
+%% fun-expression.
+%% 
+%% <p>Note: this is equivalent to <code>length(fun_vars(Node))</code>,
+%% but potentially more efficient.</p>
+%%
+%% @see c_fun/2
+%% @see fun_vars/1
+
+-spec fun_arity(c_fun()) -> arity().
+
+fun_arity(Node) ->
+    length(fun_vars(Node)).
+
+
+%% ---------------------------------------------------------------------
+
+%% @spec c_seq(Argument::cerl(), Body::cerl()) -> c_seq()
+%%
+%% @doc Creates an abstract sequencing expression. The result
+%% represents "<code>do <em>Argument</em> <em>Body</em></code>".
+%%
+%% @see ann_c_seq/3
+%% @see update_c_seq/3
+%% @see is_c_seq/1
+%% @see seq_arg/1
+%% @see seq_body/1
+
+-spec c_seq(cerl(), cerl()) -> c_seq().
+
+c_seq(Argument, Body) ->
+    #c_seq{arg = Argument, body = Body}.
+
+
+%% @spec ann_c_seq(As::anns(), Argument::cerl(), Body::cerl()) -> c_seq()
+%%
+%% @see c_seq/2
+
+-spec ann_c_seq(anns(), cerl(), cerl()) -> c_seq().
+
+ann_c_seq(As, Argument, Body) ->
+    #c_seq{arg = Argument, body = Body, anno = As}.
+
+
+%% @spec update_c_seq(Old::c_seq(), Argument::cerl(), Body::cerl()) ->
+%%           c_seq()
+%% @see c_seq/2
+
+-spec update_c_seq(c_seq(), cerl(), cerl()) -> c_seq().
+
+update_c_seq(Node, Argument, Body) ->
+    #c_seq{arg = Argument, body = Body, anno = get_ann(Node)}.
+
+
+%% @spec is_c_seq(Node::cerl()) -> boolean()
+%%
+%% @doc Returns <code>true</code> if <code>Node</code> is an abstract
+%% sequencing expression, otherwise <code>false</code>.
+%%
+%% @see c_seq/2
+
+-spec is_c_seq(cerl()) -> boolean().
+
+is_c_seq(#c_seq{}) ->
+    true;
+is_c_seq(_) ->
+    false.
+
+
+%% @spec seq_arg(c_seq()) -> cerl()
+%%
+%% @doc Returns the argument subtree of an abstract sequencing
+%% expression.
+%%
+%% @see c_seq/2
+
+-spec seq_arg(c_seq()) -> cerl().
+
+seq_arg(Node) ->
+    Node#c_seq.arg.
+
+
+%% @spec seq_body(c_seq()) -> cerl()
+%%
+%% @doc Returns the body subtree of an abstract sequencing expression.
+%%
+%% @see c_seq/2
+
+-spec seq_body(c_seq()) -> cerl().
+
+seq_body(Node) ->
+    Node#c_seq.body.
+
+
+%% ---------------------------------------------------------------------
+
+%% @spec c_let(Variables::[c_var()], Argument::cerl(), Body::cerl()) ->
+%%           c_let()
+%%
+%% @doc Creates an abstract let-expression. If <code>Variables</code>
+%% is <code>[V1, ..., Vn]</code>, the result represents "<code>let
+%% &lt;<em>V1</em>, ..., <em>Vn</em>&gt; = <em>Argument</em> in
+%% <em>Body</em></code>".  All the <code>Vi</code> must have type
+%% <code>var</code>.
+%%
+%% @see ann_c_let/4
+%% @see update_c_let/4
+%% @see is_c_let/1
+%% @see let_vars/1
+%% @see let_arg/1
+%% @see let_body/1
+%% @see let_arity/1
+
+-spec c_let([c_var()], cerl(), cerl()) -> c_let().
+
+c_let(Variables, Argument, Body) ->
+    #c_let{vars = Variables, arg = Argument, body = Body}.
+
+
+%% ann_c_let(As, Variables, Argument, Body) -> c_let()
+%% @see c_let/3
+
+-spec ann_c_let(anns(), [c_var()], cerl(), cerl()) -> c_let().
+
+ann_c_let(As, Variables, Argument, Body) ->
+    #c_let{vars = Variables, arg = Argument, body = Body, anno = As}.
+
+
+%% update_c_let(Old, Variables, Argument, Body) -> c_let()
+%% @see c_let/3
+
+-spec update_c_let(c_let(), [c_var()], cerl(), cerl()) -> c_let().
+
+update_c_let(Node, Variables, Argument, Body) ->
+    #c_let{vars = Variables, arg = Argument, body = Body,
+	   anno = get_ann(Node)}.
+
+
+%% @spec is_c_let(Node::cerl()) -> boolean()
+%%
+%% @doc Returns <code>true</code> if <code>Node</code> is an abstract
+%% let-expression, otherwise <code>false</code>.
+%%
+%% @see c_let/3
+
+-spec is_c_let(cerl()) -> boolean().
+
+is_c_let(#c_let{}) ->
+    true;
+is_c_let(_) ->
+    false.
+
+
+%% @spec let_vars(c_let()) -> [c_var()]
+%%
+%% @doc Returns the list of left-hand side variables of an abstract
+%% let-expression.
+%%
+%% @see c_let/3
+%% @see let_arity/1
+
+-spec let_vars(c_let()) -> [c_var()].
+
+let_vars(Node) ->
+    Node#c_let.vars.
+
+
+%% @spec let_arg(c_let()) -> cerl()
+%%
+%% @doc Returns the argument subtree of an abstract let-expression.
+%%
+%% @see c_let/3
+
+-spec let_arg(c_let()) -> cerl().
+
+let_arg(Node) ->
+    Node#c_let.arg.
+
+
+%% @spec let_body(c_let()) -> cerl()
+%%
+%% @doc Returns the body subtree of an abstract let-expression.
+%%
+%% @see c_let/3
+
+-spec let_body(c_let()) -> cerl().
+
+let_body(Node) ->
+    Node#c_let.body.
+
+
+%% @spec let_arity(Node::c_let()) -> non_neg_integer()
+%%
+%% @doc Returns the number of left-hand side variables of an abstract
+%% let-expression.
+%% 
+%% <p>Note: this is equivalent to <code>length(let_vars(Node))</code>,
+%% but potentially more efficient.</p>
+%%
+%% @see c_let/3
+%% @see let_vars/1
+
+-spec let_arity(c_let()) -> non_neg_integer().
+
+let_arity(Node) ->
+    length(let_vars(Node)).
+
+
+%% ---------------------------------------------------------------------
+
+%% @spec c_letrec(Definitions::defs(), Body::cerl()) -> c_letrec()
+%%
+%% @doc Creates an abstract letrec-expression. If
+%% <code>Definitions</code> is <code>[{V1, F1}, ..., {Vn, Fn}]</code>,
+%% the result represents "<code>letrec <em>V1</em> = <em>F1</em>
+%% ... <em>Vn</em> = <em>Fn</em> in <em>Body</em></code>.  All the
+%% <code>Vi</code> must have type <code>var</code> and represent
+%% function names.  All the <code>Fi</code> must have type
+%% <code>'fun'</code>.
+%%
+%% @see ann_c_letrec/3
+%% @see update_c_letrec/3
+%% @see is_c_letrec/1
+%% @see letrec_defs/1
+%% @see letrec_body/1
+%% @see letrec_vars/1
+
+-spec c_letrec(defs(), cerl()) -> c_letrec().
+
+c_letrec(Defs, Body) ->
+    #c_letrec{defs = Defs, body = Body}.
+
+
+%% @spec ann_c_letrec(As::anns(), Definitions::defs(),
+%%                    Body::cerl()) -> c_letrec()
+%% @see c_letrec/2
+
+-spec ann_c_letrec(anns(), defs(), cerl()) -> c_letrec().
+
+ann_c_letrec(As, Defs, Body) ->
+    #c_letrec{defs = Defs, body = Body, anno = As}.
+
+
+%% @spec update_c_letrec(Old::c_letrec(), Definitions::defs(),
+%%                       Body::cerl()) -> c_letrec()
+%% @see c_letrec/2
+
+-spec update_c_letrec(c_letrec(), defs(), cerl()) -> c_letrec().
+
+update_c_letrec(Node, Defs, Body) ->
+    #c_letrec{defs = Defs, body = Body, anno = get_ann(Node)}.
+
+
+%% @spec is_c_letrec(Node::cerl()) -> boolean()
+%%
+%% @doc Returns <code>true</code> if <code>Node</code> is an abstract
+%% letrec-expression, otherwise <code>false</code>.
+%%
+%% @see c_letrec/2
+
+-spec is_c_letrec(cerl()) -> boolean().
+
+is_c_letrec(#c_letrec{}) ->
+    true;
+is_c_letrec(_) ->
+    false.
+
+
+%% @spec letrec_defs(Node::c_letrec()) -> defs()
+%%
+%% @doc Returns the list of definitions of an abstract
+%% letrec-expression. If <code>Node</code> represents "<code>letrec
+%% <em>V1</em> = <em>F1</em> ... <em>Vn</em> = <em>Fn</em> in
+%% <em>Body</em></code>", the returned value is <code>[{V1, F1}, ...,
+%% {Vn, Fn}]</code>.
+%%
+%% @see c_letrec/2
+
+-spec letrec_defs(c_letrec()) -> defs().
+
+letrec_defs(Node) ->
+    Node#c_letrec.defs.
+
+
+%% @spec letrec_body(c_letrec()) -> cerl()
+%%
+%% @doc Returns the body subtree of an abstract letrec-expression.
+%%
+%% @see c_letrec/2
+
+-spec letrec_body(c_letrec()) -> cerl().
+
+letrec_body(Node) ->
+    Node#c_letrec.body.
+
+
+%% @spec letrec_vars(c_letrec()) -> [cerl()]
+%%
+%% @doc Returns the list of left-hand side function variable subtrees
+%% of a letrec-expression. If <code>Node</code> represents
+%% "<code>letrec <em>V1</em> = <em>F1</em> ... <em>Vn</em> =
+%% <em>Fn</em> in <em>Body</em></code>", the returned value is
+%% <code>[V1, ..., Vn]</code>.
+%%
+%% @see c_letrec/2
+
+-spec letrec_vars(c_letrec()) -> [cerl()].
+
+letrec_vars(Node) ->
+    [F || {F, _} <- letrec_defs(Node)].
+
+
+%% ---------------------------------------------------------------------
+
+%% @spec c_case(Argument::cerl(), Clauses::[cerl()]) -> c_case()
+%%
+%% @doc Creates an abstract case-expression. If <code>Clauses</code>
+%% is <code>[C1, ..., Cn]</code>, the result represents "<code>case
+%% <em>Argument</em> of <em>C1</em> ... <em>Cn</em>
+%% end</code>". <code>Clauses</code> must not be empty.
+%%
+%% @see ann_c_case/3
+%% @see update_c_case/3
+%% @see is_c_case/1
+%% @see c_clause/3
+%% @see case_arg/1
+%% @see case_clauses/1
+%% @see case_arity/1
+
+-spec c_case(cerl(), [cerl()]) -> c_case().
+
+c_case(Expr, Clauses) ->
+    #c_case{arg = Expr, clauses = Clauses}.
+
+
+%% @spec ann_c_case(As::anns(), Argument::cerl(),
+%%                  Clauses::[cerl()]) -> c_case()
+%% @see c_case/2
+
+-spec ann_c_case(anns(), cerl(), [cerl()]) -> c_case().
+
+ann_c_case(As, Expr, Clauses) ->
+    #c_case{arg = Expr, clauses = Clauses, anno = As}.
+
+
+%% @spec update_c_case(Old::cerl(), Argument::cerl(),
+%%                     Clauses::[cerl()]) -> c_case()
+%% @see c_case/2
+
+-spec update_c_case(c_case(), cerl(), [cerl()]) -> c_case().
+
+update_c_case(Node, Expr, Clauses) ->
+    #c_case{arg = Expr, clauses = Clauses, anno = get_ann(Node)}.
+
+
+%% is_c_case(Node) -> boolean()
+%%
+%%	    Node = cerl()
+%%
+%% @doc Returns <code>true</code> if <code>Node</code> is an abstract
+%% case-expression; otherwise <code>false</code>.
+%%
+%% @see c_case/2
+
+-spec is_c_case(cerl()) -> boolean().
+
+is_c_case(#c_case{}) ->
+    true;
+is_c_case(_) ->
+    false.
+
+
+%% @spec case_arg(c_case()) -> cerl()
+%%
+%% @doc Returns the argument subtree of an abstract case-expression.
+%%
+%% @see c_case/2
+
+-spec case_arg(c_case()) -> cerl().
+
+case_arg(Node) ->
+    Node#c_case.arg.
+
+
+%% @spec case_clauses(c_case()) -> [cerl()]
+%%
+%% @doc Returns the list of clause subtrees of an abstract
+%% case-expression.
+%%
+%% @see c_case/2
+%% @see case_arity/1
+
+-spec case_clauses(c_case()) -> [cerl()].
+
+case_clauses(Node) ->
+    Node#c_case.clauses.
+
+
+%% @spec case_arity(Node::c_case()) -> non_neg_integer()
+%%
+%% @doc Equivalent to
+%% <code>clause_arity(hd(case_clauses(Node)))</code>, but potentially
+%% more efficient.
+%%
+%% @see c_case/2
+%% @see case_clauses/1
+%% @see clause_arity/1
+
+-spec case_arity(c_case()) -> non_neg_integer().
+
+case_arity(Node) ->
+    clause_arity(hd(case_clauses(Node))).
+
+
+%% ---------------------------------------------------------------------
+
+%% @spec c_clause(Patterns::[cerl()], Body::cerl()) -> c_clause()
+%% @equiv c_clause(Patterns, c_atom(true), Body)
+%% @see c_atom/1
+
+-spec c_clause([cerl()], cerl()) -> c_clause().
+
+c_clause(Patterns, Body) ->
+    c_clause(Patterns, c_atom(true), Body).
+
+
+%% @spec c_clause(Patterns::[cerl()], Guard::cerl(), Body::cerl()) ->
+%%           c_clause()
+%%
+%% @doc Creates an an abstract clause. If <code>Patterns</code> is
+%% <code>[P1, ..., Pn]</code>, the result represents
+%% "<code>&lt;<em>P1</em>, ..., <em>Pn</em>&gt; when <em>Guard</em> ->
+%% <em>Body</em></code>".
+%%
+%% @see c_clause/2
+%% @see ann_c_clause/4
+%% @see update_c_clause/4
+%% @see is_c_clause/1
+%% @see c_case/2
+%% @see c_receive/3
+%% @see clause_pats/1
+%% @see clause_guard/1
+%% @see clause_body/1
+%% @see clause_arity/1
+%% @see clause_vars/1
+
+-spec c_clause([cerl()], cerl(), cerl()) -> c_clause().
+
+c_clause(Patterns, Guard, Body) ->
+    #c_clause{pats = Patterns, guard = Guard, body = Body}.
+
+
+%% @spec ann_c_clause(As::anns(), Patterns::[cerl()],
+%%                    Body::cerl()) -> c_clause()
+%% @equiv ann_c_clause(As, Patterns, c_atom(true), Body)
+%% @see c_clause/3
+
+-spec ann_c_clause(anns(), [cerl()], cerl()) -> c_clause().
+
+ann_c_clause(As, Patterns, Body) ->
+    ann_c_clause(As, Patterns, c_atom(true), Body).
+
+
+%% @spec ann_c_clause(As::anns(), Patterns::[cerl()], Guard::cerl(),
+%%                    Body::cerl()) -> c_clause()
+%% @see ann_c_clause/3
+%% @see c_clause/3
+
+-spec ann_c_clause(anns(), [cerl()], cerl(), cerl()) -> c_clause().
+
+ann_c_clause(As, Patterns, Guard, Body) ->
+    #c_clause{pats = Patterns, guard = Guard, body = Body, anno = As}.
+
+
+%% @spec update_c_clause(Old::c_clause(), Patterns::[cerl()],
+%%                       Guard::cerl(), Body::cerl()) -> c_clause()
+%% @see c_clause/3
+
+-spec update_c_clause(c_clause(), [cerl()], cerl(), cerl()) -> c_clause().
+
+update_c_clause(Node, Patterns, Guard, Body) ->
+    #c_clause{pats = Patterns, guard = Guard, body = Body,
+	      anno = get_ann(Node)}.
+
+
+%% @spec is_c_clause(Node::cerl()) -> boolean()
+%%
+%% @doc Returns <code>true</code> if <code>Node</code> is an abstract
+%% clause, otherwise <code>false</code>.
+%%
+%% @see c_clause/3
+
+-spec is_c_clause(cerl()) -> boolean().
+
+is_c_clause(#c_clause{}) ->
+    true;
+is_c_clause(_) ->
+    false.
+
+
+%% @spec clause_pats(c_clause()) -> [cerl()]
+%%
+%% @doc Returns the list of pattern subtrees of an abstract clause.
+%%
+%% @see c_clause/3
+%% @see clause_arity/1
+
+-spec clause_pats(c_clause()) -> [cerl()].
+
+clause_pats(Node) ->
+    Node#c_clause.pats.
+
+
+%% @spec clause_guard(c_clause()) -> cerl()
+%%
+%% @doc Returns the guard subtree of an abstract clause.
+%% 
+%% @see c_clause/3
+
+-spec clause_guard(c_clause()) -> cerl().
+
+clause_guard(Node) ->
+    Node#c_clause.guard.
+
+
+%% @spec clause_body(c_clause()) -> cerl()
+%%
+%% @doc Returns the body subtree of an abstract clause.
+%%
+%% @see c_clause/3
+
+-spec clause_body(c_clause()) -> cerl().
+
+clause_body(Node) ->
+    Node#c_clause.body.
+
+
+%% @spec clause_arity(Node::c_clause()) -> non_neg_integer()
+%%
+%% @doc Returns the number of pattern subtrees of an abstract clause.
+%%
+%% <p>Note: this is equivalent to
+%% <code>length(clause_pats(Node))</code>, but potentially more
+%% efficient.</p>
+%%
+%% @see c_clause/3
+%% @see clause_pats/1
+
+-spec clause_arity(c_clause()) -> non_neg_integer().
+
+clause_arity(Node) ->
+    length(clause_pats(Node)).
+
+
+%% @spec clause_vars(c_clause()) -> [cerl()]
+%%
+%% @doc Returns the list of all abstract variables in the patterns of
+%% an abstract clause. The order of listing is not defined.
+%%
+%% @see c_clause/3
+%% @see pat_list_vars/1
+
+-spec clause_vars(c_clause()) -> [cerl()].
+
+clause_vars(Clause) ->
+    pat_list_vars(clause_pats(Clause)).
+
+
+%% @spec pat_vars(Pattern::cerl()) -> [cerl()]
+%%
+%% @doc Returns the list of all abstract variables in a pattern. An
+%% exception is thrown if <code>Node</code> does not represent a
+%% well-formed Core Erlang clause pattern. The order of listing is not
+%% defined.
+%%
+%% @see pat_list_vars/1
+%% @see clause_vars/1
+
+-spec pat_vars(cerl()) -> [cerl()].
+
+pat_vars(Node) ->
+    pat_vars(Node, []).
+
+pat_vars(Node, Vs) ->
+    case type(Node) of
+	var ->
+	    [Node | Vs];
+	literal ->
+	    Vs;
+	cons ->
+	    pat_vars(cons_hd(Node), pat_vars(cons_tl(Node), Vs));
+	tuple ->
+	    pat_list_vars(tuple_es(Node), Vs);
+	map ->
+	    pat_list_vars(map_es(Node), Vs);
+	map_pair ->
+	    %% map_pair_key is not a pattern var, excluded
+	    pat_list_vars([map_pair_op(Node),map_pair_val(Node)],Vs);
+	binary ->
+	    pat_list_vars(binary_segments(Node), Vs);
+	bitstr ->
+	    %% bitstr_size is not a pattern var, excluded
+	    pat_vars(bitstr_val(Node), Vs);
+	alias ->
+	    pat_vars(alias_pat(Node), [alias_var(Node) | Vs])
+    end.
+
+
+%% @spec pat_list_vars(Patterns::[cerl()]) -> [cerl()]
+%%
+%% @doc Returns the list of all abstract variables in the given
+%% patterns. An exception is thrown if some element in
+%% <code>Patterns</code> does not represent a well-formed Core Erlang
+%% clause pattern. The order of listing is not defined.
+%%
+%% @see pat_vars/1
+%% @see clause_vars/1
+
+-spec pat_list_vars([cerl()]) -> [cerl()].
+
+pat_list_vars(Ps) ->
+    pat_list_vars(Ps, []).
+
+pat_list_vars([P | Ps], Vs) ->
+    pat_list_vars(Ps, pat_vars(P, Vs));
+pat_list_vars([], Vs) ->
+    Vs.
+
+
+%% ---------------------------------------------------------------------
+
+%% @spec c_alias(Variable::c_var(), Pattern::cerl()) -> c_alias()
+%%
+%% @doc Creates an abstract pattern alias. The result represents
+%% "<code><em>Variable</em> = <em>Pattern</em></code>".
+%%
+%% @see ann_c_alias/3
+%% @see update_c_alias/3
+%% @see is_c_alias/1
+%% @see alias_var/1
+%% @see alias_pat/1
+%% @see c_clause/3
+
+-spec c_alias(c_var(), cerl()) -> c_alias().
+
+c_alias(Var, Pattern) ->
+    #c_alias{var = Var, pat = Pattern}.
+
+
+%% @spec ann_c_alias(As::anns(), Variable::c_var(),
+%%                   Pattern::cerl()) -> c_alias()
+%% @see c_alias/2
+
+-spec ann_c_alias(anns(), c_var(), cerl()) -> c_alias().
+
+ann_c_alias(As, Var, Pattern) ->
+    #c_alias{var = Var, pat = Pattern, anno = As}.
+
+
+%% @spec update_c_alias(Old::cerl(), Variable::c_var(),
+%%                      Pattern::cerl()) -> c_alias()
+%% @see c_alias/2
+
+-spec update_c_alias(c_alias(), c_var(), cerl()) -> c_alias().
+
+update_c_alias(Node, Var, Pattern) ->
+    #c_alias{var = Var, pat = Pattern, anno = get_ann(Node)}.
+
+
+%% @spec is_c_alias(Node::cerl()) -> boolean()
+%%
+%% @doc Returns <code>true</code> if <code>Node</code> is an abstract
+%% pattern alias, otherwise <code>false</code>.
+%%
+%% @see c_alias/2
+
+-spec is_c_alias(cerl()) -> boolean().
+
+is_c_alias(#c_alias{}) ->
+    true;
+is_c_alias(_) ->
+    false.
+
+
+%% @spec alias_var(c_alias()) -> c_var()
+%%
+%% @doc Returns the variable subtree of an abstract pattern alias.
+%%
+%% @see c_alias/2
+
+-spec alias_var(c_alias()) -> c_var().
+
+alias_var(Node) ->
+    Node#c_alias.var.
+
+
+%% @spec alias_pat(c_alias()) -> cerl()
+%%
+%% @doc Returns the pattern subtree of an abstract pattern alias.
+%%
+%% @see c_alias/2
+
+-spec alias_pat(c_alias()) -> cerl().
+
+alias_pat(Node) ->
+    Node#c_alias.pat.
+
+
+%% ---------------------------------------------------------------------
+
+%% @spec c_receive(Clauses::[cerl()]) -> c_receive()
+%% @equiv c_receive(Clauses, c_atom(infinity), c_atom(true))
+%% @see c_atom/1
+
+-spec c_receive([cerl()]) -> c_receive().
+
+c_receive(Clauses) ->
+    c_receive(Clauses, c_atom(infinity), c_atom(true)).
+
+
+%% @spec c_receive(Clauses::[cerl()], Timeout::cerl(),
+%%                 Action::cerl()) -> c_receive()
+%%
+%% @doc Creates an abstract receive-expression. If
+%% <code>Clauses</code> is <code>[C1, ..., Cn]</code>, the result
+%% represents "<code>receive <em>C1</em> ... <em>Cn</em> after
+%% <em>Timeout</em> -> <em>Action</em> end</code>".
+%%
+%% @see c_receive/1
+%% @see ann_c_receive/4
+%% @see update_c_receive/4
+%% @see is_c_receive/1
+%% @see receive_clauses/1
+%% @see receive_timeout/1
+%% @see receive_action/1
+
+-spec c_receive([cerl()], cerl(), cerl()) -> c_receive().
+
+c_receive(Clauses, Timeout, Action) ->
+    #c_receive{clauses = Clauses, timeout = Timeout, action = Action}.
+
+
+%% @spec ann_c_receive(As::anns(), Clauses::[cerl()]) -> c_receive()
+%% @equiv ann_c_receive(As, Clauses, c_atom(infinity), c_atom(true))
+%% @see c_receive/3
+%% @see c_atom/1
+
+-spec ann_c_receive(anns(), [cerl()]) -> c_receive().
+
+ann_c_receive(As, Clauses) ->
+    ann_c_receive(As, Clauses, c_atom(infinity), c_atom(true)).
+
+
+%% @spec ann_c_receive(As::anns(), Clauses::[cerl()],
+%%                     Timeout::cerl(), Action::cerl()) -> c_receive()
+%% @see ann_c_receive/2
+%% @see c_receive/3
+
+-spec ann_c_receive(anns(), [cerl()], cerl(), cerl()) -> c_receive().
+
+ann_c_receive(As, Clauses, Timeout, Action) ->
+    #c_receive{clauses = Clauses, timeout = Timeout, action = Action,
+	       anno = As}.
+
+
+%% @spec update_c_receive(Old::cerl(), Clauses::[cerl()],
+%%                        Timeout::cerl(), Action::cerl()) -> c_receive()
+%% @see c_receive/3
+
+-spec update_c_receive(c_receive(), [cerl()], cerl(), cerl()) -> c_receive().
+
+update_c_receive(Node, Clauses, Timeout, Action) ->
+    #c_receive{clauses = Clauses, timeout = Timeout, action = Action,
+	       anno = get_ann(Node)}.
+
+
+%% @spec is_c_receive(Node::cerl()) -> boolean()
+%%
+%% @doc Returns <code>true</code> if <code>Node</code> is an abstract
+%% receive-expression, otherwise <code>false</code>.
+%%
+%% @see c_receive/3
+
+-spec is_c_receive(cerl()) -> boolean().
+
+is_c_receive(#c_receive{}) ->
+    true;
+is_c_receive(_) ->
+    false.
+
+
+%% @spec receive_clauses(c_receive()) -> [cerl()]
+%%
+%% @doc Returns the list of clause subtrees of an abstract
+%% receive-expression.
+%%
+%% @see c_receive/3
+
+-spec receive_clauses(c_receive()) -> [cerl()].
+
+receive_clauses(Node) ->
+    Node#c_receive.clauses.
+
+
+%% @spec receive_timeout(c_receive()) -> cerl()
+%%
+%% @doc Returns the timeout subtree of an abstract receive-expression.
+%%
+%% @see c_receive/3
+
+-spec receive_timeout(c_receive()) -> cerl().
+
+receive_timeout(Node) ->
+    Node#c_receive.timeout.
+
+
+%% @spec receive_action(c_receive()) -> cerl()
+%%
+%% @doc Returns the action subtree of an abstract receive-expression.
+%%
+%% @see c_receive/3
+
+-spec receive_action(c_receive()) -> cerl().
+
+receive_action(Node) ->
+    Node#c_receive.action.
+
+
+%% ---------------------------------------------------------------------
+
+%% @spec c_apply(Operator::c_var(), Arguments::[cerl()]) -> c_apply()
+%%
+%% @doc Creates an abstract function application. If
+%% <code>Arguments</code> is <code>[A1, ..., An]</code>, the result
+%% represents "<code>apply <em>Operator</em>(<em>A1</em>, ...,
+%% <em>An</em>)</code>".
+%%
+%% @see ann_c_apply/3
+%% @see update_c_apply/3
+%% @see is_c_apply/1
+%% @see apply_op/1
+%% @see apply_args/1
+%% @see apply_arity/1
+%% @see c_call/3
+%% @see c_primop/2
+
+-spec c_apply(c_var(), [cerl()]) -> c_apply().
+
+c_apply(Operator, Arguments) ->
+    #c_apply{op = Operator, args = Arguments}.
+
+
+%% @spec ann_c_apply(As::anns(), Operator::c_var(),
+%%                   Arguments::[cerl()]) -> c_apply()
+%% @see c_apply/2
+
+-spec ann_c_apply(anns(), c_var(), [cerl()]) -> c_apply().
+
+ann_c_apply(As, Operator, Arguments) ->
+    #c_apply{op = Operator, args = Arguments, anno = As}.
+
+
+%% @spec update_c_apply(Old::c_apply(), Operator::cerl(),
+%%                      Arguments::[cerl()]) -> c_apply()
+%% @see c_apply/2
+
+-spec update_c_apply(c_apply(), c_var(), [cerl()]) -> c_apply().
+
+update_c_apply(Node, Operator, Arguments) ->
+    #c_apply{op = Operator, args = Arguments, anno = get_ann(Node)}.
+
+
+%% @spec is_c_apply(Node::cerl()) -> boolean()
+%%
+%% @doc Returns <code>true</code> if <code>Node</code> is an abstract
+%% function application, otherwise <code>false</code>.
+%%
+%% @see c_apply/2
+
+-spec is_c_apply(cerl()) -> boolean().
+
+is_c_apply(#c_apply{}) ->
+    true;
+is_c_apply(_) ->
+    false.
+
+
+%% @spec apply_op(c_apply()) -> c_var()
+%%
+%% @doc Returns the operator subtree of an abstract function
+%% application.
+%%
+%% @see c_apply/2
+
+-spec apply_op(c_apply()) -> c_var().
+
+apply_op(Node) ->
+    Node#c_apply.op.
+
+
+%% @spec apply_args(c_apply()) -> [cerl()]
+%%
+%% @doc Returns the list of argument subtrees of an abstract function
+%% application.
+%%
+%% @see c_apply/2
+%% @see apply_arity/1
+
+-spec apply_args(c_apply()) -> [cerl()].
+
+apply_args(Node) ->
+    Node#c_apply.args.
+
+
+%% @spec apply_arity(Node::c_apply()) -> arity()
+%%
+%% @doc Returns the number of argument subtrees of an abstract
+%% function application.
+%%
+%% <p>Note: this is equivalent to
+%% <code>length(apply_args(Node))</code>, but potentially more
+%% efficient.</p>
+%%
+%% @see c_apply/2
+%% @see apply_args/1
+
+-spec apply_arity(c_apply()) -> arity().
+
+apply_arity(Node) ->
+    length(apply_args(Node)).
+
+
+%% ---------------------------------------------------------------------
+
+%% @spec c_call(Module::cerl(), Name::cerl(), Arguments::[cerl()]) ->
+%%           c_call()
+%%
+%% @doc Creates an abstract inter-module call. If
+%% <code>Arguments</code> is <code>[A1, ..., An]</code>, the result
+%% represents "<code>call <em>Module</em>:<em>Name</em>(<em>A1</em>,
+%% ..., <em>An</em>)</code>".
+%%
+%% @see ann_c_call/4
+%% @see update_c_call/4
+%% @see is_c_call/1
+%% @see call_module/1
+%% @see call_name/1
+%% @see call_args/1
+%% @see call_arity/1
+%% @see c_apply/2
+%% @see c_primop/2
+
+-spec c_call(cerl(), cerl(), [cerl()]) -> c_call().
+
+c_call(Module, Name, Arguments) ->
+    #c_call{module = Module, name = Name, args = Arguments}.
+
+
+%% @spec ann_c_call(As::anns(), Module::cerl(), Name::cerl(),
+%%                  Arguments::[cerl()]) -> c_call()
+%% @see c_call/3
+
+-spec ann_c_call(anns(), cerl(), cerl(), [cerl()]) -> c_call().
+
+ann_c_call(As, Module, Name, Arguments) ->
+    #c_call{module = Module, name = Name, args = Arguments, anno = As}.
+
+
+%% @spec update_c_call(Old::cerl(), Module::cerl(), Name::cerl(),
+%%                  Arguments::[cerl()]) -> c_call()
+%% @see c_call/3
+
+-spec update_c_call(cerl(), cerl(), cerl(), [cerl()]) -> c_call().
+
+update_c_call(Node, Module, Name, Arguments) ->
+    #c_call{module = Module, name = Name, args = Arguments,
+	    anno = get_ann(Node)}.
+
+
+%% @spec is_c_call(Node::cerl()) -> boolean()
+%%
+%% @doc Returns <code>true</code> if <code>Node</code> is an abstract
+%% inter-module call expression; otherwise <code>false</code>.
+%%
+%% @see c_call/3
+
+-spec is_c_call(cerl()) -> boolean().
+
+is_c_call(#c_call{}) ->
+    true;
+is_c_call(_) ->
+    false.
+
+
+%% @spec call_module(c_call()) -> cerl()
+%%
+%% @doc Returns the module subtree of an abstract inter-module call.
+%%
+%% @see c_call/3
+
+-spec call_module(c_call()) -> cerl().
+
+call_module(Node) ->
+    Node#c_call.module.
+
+
+%% @spec call_name(c_call()) -> cerl()
+%%
+%% @doc Returns the name subtree of an abstract inter-module call.
+%%
+%% @see c_call/3
+
+-spec call_name(c_call()) -> cerl().
+
+call_name(Node) ->
+    Node#c_call.name.
+
+
+%% @spec call_args(c_call()) -> [cerl()]
+%%
+%% @doc Returns the list of argument subtrees of an abstract
+%% inter-module call.
+%%
+%% @see c_call/3
+%% @see call_arity/1
+
+-spec call_args(c_call()) -> [cerl()].
+
+call_args(Node) ->
+    Node#c_call.args.
+
+
+%% @spec call_arity(Node::c_call()) -> arity()
+%%
+%% @doc Returns the number of argument subtrees of an abstract
+%% inter-module call.
+%%
+%% <p>Note: this is equivalent to
+%% <code>length(call_args(Node))</code>, but potentially more
+%% efficient.</p>
+%%
+%% @see c_call/3
+%% @see call_args/1
+
+-spec call_arity(c_call()) -> arity().
+
+call_arity(Node) ->
+    length(call_args(Node)).
+
+
+%% ---------------------------------------------------------------------
+
+%% @spec c_primop(Name::c_literal(), Arguments::[cerl()]) -> c_primop()
+%%
+%% @doc Creates an abstract primitive operation call. If
+%% <code>Arguments</code> is <code>[A1, ..., An]</code>, the result
+%% represents "<code>primop <em>Name</em>(<em>A1</em>, ...,
+%% <em>An</em>)</code>". <code>Name</code> must be an atom literal.
+%%
+%% @see ann_c_primop/3
+%% @see update_c_primop/3
+%% @see is_c_primop/1
+%% @see primop_name/1
+%% @see primop_args/1
+%% @see primop_arity/1
+%% @see c_apply/2
+%% @see c_call/3
+
+-spec c_primop(c_literal(), [cerl()]) -> c_primop().
+
+c_primop(Name, Arguments) ->
+    #c_primop{name = Name, args = Arguments}.
+
+
+%% @spec ann_c_primop(As::anns(), Name::c_literal(),
+%%                    Arguments::[cerl()]) -> c_primop()
+%% @see c_primop/2
+
+-spec ann_c_primop(anns(), c_literal(), [cerl()]) -> c_primop().
+
+ann_c_primop(As, Name, Arguments) ->
+    #c_primop{name = Name, args = Arguments, anno = As}.
+
+
+%% @spec update_c_primop(Old::cerl(), Name::c_literal(),
+%%                       Arguments::[cerl()]) -> c_primop()
+%% @see c_primop/2
+
+-spec update_c_primop(cerl(), c_literal(), [cerl()]) -> c_primop().
+
+update_c_primop(Node, Name, Arguments) ->
+    #c_primop{name = Name, args = Arguments, anno = get_ann(Node)}.
+
+
+%% @spec is_c_primop(Node::cerl()) -> boolean()
+%%
+%% @doc Returns <code>true</code> if <code>Node</code> is an abstract
+%% primitive operation call, otherwise <code>false</code>.
+%%
+%% @see c_primop/2
+
+-spec is_c_primop(cerl()) -> boolean().
+
+is_c_primop(#c_primop{}) ->
+    true;
+is_c_primop(_) ->
+    false.
+
+
+%% @spec primop_name(c_primop()) -> c_literal()
+%%
+%% @doc Returns the name subtree of an abstract primitive operation
+%% call.
+%%
+%% @see c_primop/2
+
+-spec primop_name(c_primop()) -> c_literal().
+
+primop_name(Node) ->
+    Node#c_primop.name.
+
+
+%% @spec primop_args(c_primop()) -> [cerl()]
+%%
+%% @doc Returns the list of argument subtrees of an abstract primitive
+%% operation call.
+%%
+%% @see c_primop/2
+%% @see primop_arity/1
+
+-spec primop_args(c_primop()) -> [cerl()].
+
+primop_args(Node) ->
+    Node#c_primop.args.
+
+
+%% @spec primop_arity(Node::c_primop()) -> arity()
+%%
+%% @doc Returns the number of argument subtrees of an abstract
+%% primitive operation call.
+%%
+%% <p>Note: this is equivalent to
+%% <code>length(primop_args(Node))</code>, but potentially more
+%% efficient.</p>
+%%
+%% @see c_primop/2
+%% @see primop_args/1
+
+-spec primop_arity(c_primop()) -> arity().
+
+primop_arity(Node) ->
+    length(primop_args(Node)).
+
+
+%% ---------------------------------------------------------------------
+
+%% @spec c_try(Argument::cerl(), Variables::[c_var()], Body::cerl(),
+%%             ExceptionVars::[c_var()], Handler::cerl()) -> c_try()
+%%
+%% @doc Creates an abstract try-expression. If <code>Variables</code> is
+%% <code>[V1, ..., Vn]</code> and <code>ExceptionVars</code> is
+%% <code>[X1, ..., Xm]</code>, the result represents "<code>try
+%% <em>Argument</em> of &lt;<em>V1</em>, ..., <em>Vn</em>&gt; ->
+%% <em>Body</em> catch &lt;<em>X1</em>, ..., <em>Xm</em>&gt; ->
+%% <em>Handler</em></code>". All the <code>Vi</code> and <code>Xi</code>
+%% must have type <code>var</code>.
+%%
+%% @see ann_c_try/6
+%% @see update_c_try/6
+%% @see is_c_try/1
+%% @see try_arg/1
+%% @see try_vars/1
+%% @see try_body/1
+%% @see c_catch/1
+
+-spec c_try(cerl(), [c_var()], cerl(), [c_var()], cerl()) -> c_try().
+
+c_try(Expr, Vs, Body, Evs, Handler) ->
+    #c_try{arg = Expr, vars = Vs, body = Body,
+	   evars = Evs, handler = Handler}.
+
+
+%% @spec ann_c_try(As::[term()], Expression::cerl(),
+%%                 Variables::[c_var()], Body::cerl(),
+%%                 EVars::[c_var()], Handler::cerl()) -> c_try()
+%% @see c_try/5
+
+-spec ann_c_try(anns(), cerl(), [c_var()], cerl(), [c_var()], cerl()) ->
+        c_try().
+
+ann_c_try(As, Expr, Vs, Body, Evs, Handler) ->
+    #c_try{arg = Expr, vars = Vs, body = Body,
+	   evars = Evs, handler = Handler, anno = As}.
+
+
+%% @spec update_c_try(Old::c_try(), Expression::cerl(),
+%%                    Variables::[c_var()], Body::cerl(),
+%%                    EVars::[c_var()], Handler::cerl()) -> cerl()
+%% @see c_try/5
+
+-spec update_c_try(c_try(), cerl(), [c_var()], cerl(), [c_var()], cerl()) ->
+        c_try().
+
+update_c_try(Node, Expr, Vs, Body, Evs, Handler) ->
+    #c_try{arg = Expr, vars = Vs, body = Body,
+	   evars = Evs, handler = Handler, anno = get_ann(Node)}.
+
+
+%% @spec is_c_try(Node::cerl()) -> boolean()
+%%
+%% @doc Returns <code>true</code> if <code>Node</code> is an abstract
+%% try-expression, otherwise <code>false</code>.
+%%
+%% @see c_try/5
+
+-spec is_c_try(cerl()) -> boolean().
+
+is_c_try(#c_try{}) ->
+    true;
+is_c_try(_) ->
+    false.
+
+
+%% @spec try_arg(c_try()) -> cerl()
+%%
+%% @doc Returns the expression subtree of an abstract try-expression.
+%%
+%% @see c_try/5
+
+-spec try_arg(c_try()) -> cerl().
+
+try_arg(Node) ->
+    Node#c_try.arg.
+
+
+%% @spec try_vars(c_try()) -> [c_var()]
+%%
+%% @doc Returns the list of success variable subtrees of an abstract
+%% try-expression.
+%%
+%% @see c_try/5
+
+-spec try_vars(c_try()) -> [c_var()].
+
+try_vars(Node) ->
+    Node#c_try.vars.
+
+
+%% @spec try_body(c_try()) -> cerl()
+%%
+%% @doc Returns the success body subtree of an abstract try-expression.
+%%
+%% @see c_try/5
+
+-spec try_body(c_try()) -> cerl().
+
+try_body(Node) ->
+    Node#c_try.body.
+
+
+%% @spec try_evars(c_try()) -> [c_var()]
+%%
+%% @doc Returns the list of exception variable subtrees of an abstract
+%% try-expression.
+%%
+%% @see c_try/5
+
+-spec try_evars(c_try()) -> [c_var()].
+
+try_evars(Node) ->
+    Node#c_try.evars.
+
+
+%% @spec try_handler(c_try()) -> cerl()
+%%
+%% @doc Returns the exception body subtree of an abstract
+%% try-expression.
+%%
+%% @see c_try/5
+
+-spec try_handler(c_try()) -> cerl().
+
+try_handler(Node) ->
+    Node#c_try.handler.
+
+
+%% ---------------------------------------------------------------------
+
+%% @spec c_catch(Body::cerl()) -> c_catch()
+%%
+%% @doc Creates an abstract catch-expression. The result represents
+%% "<code>catch <em>Body</em></code>".
+%%
+%% <p>Note: catch-expressions can be rewritten as try-expressions, and
+%% will eventually be removed from Core Erlang.</p>
+%%
+%% @see ann_c_catch/2
+%% @see update_c_catch/2
+%% @see is_c_catch/1
+%% @see catch_body/1
+%% @see c_try/5
+
+-spec c_catch(cerl()) -> c_catch().
+
+c_catch(Body) ->
+    #c_catch{body = Body}.
+
+
+%% @spec ann_c_catch(As::anns(), Body::cerl()) -> c_catch()
+%% @see c_catch/1
+
+-spec ann_c_catch(anns(), cerl()) -> c_catch().
+
+ann_c_catch(As, Body) ->
+    #c_catch{body = Body, anno = As}.
+
+
+%% @spec update_c_catch(Old::c_catch(), Body::cerl()) -> c_catch()
+%% @see c_catch/1
+
+-spec update_c_catch(c_catch(), cerl()) -> c_catch().
+
+update_c_catch(Node, Body) ->
+    #c_catch{body = Body, anno = get_ann(Node)}.
+
+
+%% @spec is_c_catch(Node::cerl()) -> boolean()
+%%
+%% @doc Returns <code>true</code> if <code>Node</code> is an abstract
+%% catch-expression, otherwise <code>false</code>.
+%%
+%% @see c_catch/1
+
+-spec is_c_catch(cerl()) -> boolean().
+
+is_c_catch(#c_catch{}) ->
+    true;
+is_c_catch(_) ->
+    false.
+
+
+%% @spec catch_body(Node::c_catch()) -> cerl()
+%%
+%% @doc Returns the body subtree of an abstract catch-expression.
+%%
+%% @see c_catch/1
+
+-spec catch_body(c_catch()) -> cerl().
+
+catch_body(Node) ->
+    Node#c_catch.body.
+
+
+%% ---------------------------------------------------------------------
+
+%% @spec to_records(Tree::cerl()) -> record(record_types())
+%%
+%% @doc Translates an abstract syntax tree to a corresponding explicit
+%% record representation. The records are defined in the file
+%% "<code>cerl.hrl</code>".
+%%
+%% @see type/1
+%% @see from_records/1
+
+-spec to_records(cerl()) -> cerl().
+
+to_records(Node) ->
+    Node.
+
+%% @spec from_records(Tree::record(record_types())) -> cerl()
+%%
+%%     record_types() = c_alias | c_apply | c_binary | c_bitstr | c_call |
+%%                      c_case | c_catch | c_clause | c_cons | c_fun |
+%%                      c_let | c_letrec | c_literal | c_map | c_map_pair |
+%%                      c_module | c_primop | c_receive | c_seq |
+%%                      c_try | c_tuple | c_values | c_var
+%%
+%% @doc Translates an explicit record representation to a
+%% corresponding abstract syntax tree.  The records are defined in the
+%% file "<code>core_parse.hrl</code>".
+%%
+%% @see type/1
+%% @see to_records/1
+
+-spec from_records(cerl()) -> cerl().
+
+from_records(Node) ->
+    Node.
+
+
+%% ---------------------------------------------------------------------
+
+%% @spec is_data(Node::cerl()) -> boolean()
+%%
+%% @doc Returns <code>true</code> if <code>Node</code> represents a
+%% data constructor, otherwise <code>false</code>. Data constructors
+%% are cons cells, tuples, and atomic literals.
+%%
+%% @see data_type/1
+%% @see data_es/1
+%% @see data_arity/1
+
+-spec is_data(cerl()) -> boolean().
+
+is_data(#c_literal{}) ->
+    true;
+is_data(#c_cons{}) ->
+    true;
+is_data(#c_tuple{}) ->
+    true;
+is_data(_) ->
+    false.
+
+
+%% @spec data_type(Node::cerl()) -> dtype()
+%%
+%%     dtype() = cons | tuple | {atomic, Value}
+%%     Value = integer() | float() | atom() | []
+%%
+%% @doc Returns a type descriptor for a data constructor
+%% node. (Cf. <code>is_data/1</code>.) This is mainly useful for
+%% comparing types and for constructing new nodes of the same type
+%% (cf. <code>make_data/2</code>). If <code>Node</code> represents an
+%% integer, floating-point number, atom or empty list, the result is
+%% <code>{atomic, Value}</code>, where <code>Value</code> is the value
+%% of <code>concrete(Node)</code>, otherwise the result is either
+%% <code>cons</code> or <code>tuple</code>.
+%%
+%% <p>Type descriptors can be compared for equality or order (in the
+%% Erlang term order), but remember that floating-point values should
+%% in general never be tested for equality.</p>
+%%
+%% @see is_data/1
+%% @see make_data/2
+%% @see type/1
+%% @see concrete/1
+
+-type value() :: integer() | float() | atom() | [].
+-type dtype() :: 'cons' | 'tuple' | {'atomic', value()}.
+-type c_lct() :: c_literal() | c_cons() | c_tuple().
+
+-spec data_type(c_lct()) -> dtype().
+
+data_type(#c_literal{val = V}) ->
+    case V of
+	[_ | _] ->
+	    cons;
+	_ when is_tuple(V) ->
+	    tuple;
+	_ ->
+	    {atomic, V}
+    end;
+data_type(#c_cons{}) ->
+    cons;
+data_type(#c_tuple{}) ->
+    tuple.
+
+%% @spec data_es(Node::cerl()) -> [cerl()]
+%%
+%% @doc Returns the list of subtrees of a data constructor node. If
+%% the arity of the constructor is zero, the result is the empty list.
+%%
+%% <p>Note: if <code>data_type(Node)</code> is <code>cons</code>, the
+%% number of subtrees is exactly two. If <code>data_type(Node)</code>
+%% is <code>{atomic, Value}</code>, the number of subtrees is
+%% zero.</p>
+%%
+%% @see is_data/1
+%% @see data_type/1
+%% @see data_arity/1
+%% @see make_data/2
+
+-spec data_es(c_lct()) -> [cerl()].
+
+data_es(#c_literal{val = V}) ->
+    case V of
+	[Head | Tail] ->
+	    [#c_literal{val = Head}, #c_literal{val = Tail}];
+	_ when is_tuple(V) ->
+	    make_lit_list(tuple_to_list(V));
+	_ ->
+	    []
+    end;
+data_es(#c_cons{hd = H, tl = T}) ->
+    [H, T];
+data_es(#c_tuple{es = Es}) ->
+    Es.
+
+%% @spec data_arity(Node::cerl()) -> non_neg_integer()
+%%
+%% @doc Returns the number of subtrees of a data constructor
+%% node. This is equivalent to <code>length(data_es(Node))</code>, but
+%% potentially more efficient.
+%%
+%% @see is_data/1
+%% @see data_es/1
+
+-spec data_arity(c_lct()) -> non_neg_integer().
+
+data_arity(#c_literal{val = V}) ->
+    case V of
+	[_ | _] ->
+	    2;
+	_ when is_tuple(V) ->
+	    tuple_size(V);
+	_ ->
+	    0
+    end;
+data_arity(#c_cons{}) ->
+    2;
+data_arity(#c_tuple{es = Es}) ->
+    length(Es).
+
+
+%% @spec make_data(Type::dtype(), Elements::[cerl()]) -> cerl()
+%%
+%% @doc Creates a data constructor node with the specified type and
+%% subtrees. (Cf. <code>data_type/1</code>.)  An exception is thrown
+%% if the length of <code>Elements</code> is invalid for the given
+%% <code>Type</code>; see <code>data_es/1</code> for arity constraints
+%% on constructor types.
+%%
+%% @see data_type/1
+%% @see data_es/1
+%% @see ann_make_data/3
+%% @see update_data/3
+%% @see make_data_skel/2
+
+-spec make_data(dtype(), [cerl()]) -> c_lct().
+
+make_data(CType, Es) ->
+    ann_make_data([], CType, Es).
+
+
+%% @spec ann_make_data(As::anns(), Type::dtype(),
+%%                     Elements::[cerl()]) -> cerl()
+%% @see make_data/2
+
+-spec ann_make_data(anns(), dtype(), [cerl()]) -> c_lct().
+
+ann_make_data(As, {atomic, V}, []) -> #c_literal{val = V, anno = As};
+ann_make_data(As, cons, [H, T]) -> ann_c_cons(As, H, T);
+ann_make_data(As, tuple, Es) -> ann_c_tuple(As, Es).
+
+%% @spec update_data(Old::cerl(), Type::dtype(),
+%%                   Elements::[cerl()]) -> cerl()
+%% @see make_data/2
+
+-spec update_data(cerl(), dtype(), [cerl()]) -> c_lct().
+
+update_data(Node, CType, Es) ->
+    ann_make_data(get_ann(Node), CType, Es).
+
+
+%% @spec make_data_skel(Type::dtype(), Elements::[cerl()]) -> cerl()
+%%
+%% @doc Like <code>make_data/2</code>, but analogous to
+%% <code>c_tuple_skel/1</code> and <code>c_cons_skel/2</code>.
+%%
+%% @see ann_make_data_skel/3
+%% @see update_data_skel/3
+%% @see make_data/2
+%% @see c_tuple_skel/1
+%% @see c_cons_skel/2
+
+-spec make_data_skel(dtype(), [cerl()]) -> c_lct().
+
+make_data_skel(CType, Es) ->
+    ann_make_data_skel([], CType, Es).
+
+
+%% @spec ann_make_data_skel(As::anns(), Type::dtype(),
+%%                          Elements::[cerl()]) -> cerl()
+%% @see make_data_skel/2
+
+-spec ann_make_data_skel(anns(), dtype(), [cerl()]) -> c_lct().
+
+ann_make_data_skel(As, {atomic, V}, []) -> #c_literal{val = V, anno = As};
+ann_make_data_skel(As, cons, [H, T]) -> ann_c_cons_skel(As, H, T);
+ann_make_data_skel(As, tuple, Es) -> ann_c_tuple_skel(As, Es).
+
+
+%% @spec update_data_skel(Old::cerl(), Type::dtype(),
+%%                        Elements::[cerl()]) -> cerl()
+%% @see make_data_skel/2
+
+-spec update_data_skel(cerl(), dtype(), [cerl()]) -> c_lct().
+
+update_data_skel(Node, CType, Es) ->
+    ann_make_data_skel(get_ann(Node), CType, Es).
+
+
+%% ---------------------------------------------------------------------
+
+%% @spec subtrees(Node::cerl()) -> [[cerl()]]
+%%
+%% @doc Returns the grouped list of all subtrees of a node. If
+%% <code>Node</code> is a leaf node (cf. <code>is_leaf/1</code>), this
+%% is the empty list, otherwise the result is always a nonempty list,
+%% containing the lists of subtrees of <code>Node</code>, in
+%% left-to-right order as they occur in the printed program text, and
+%% grouped by category. Often, each group contains only a single
+%% subtree.
+%%
+%% <p>Depending on the type of <code>Node</code>, the size of some
+%% groups may be variable (e.g., the group consisting of all the
+%% elements of a tuple), while others always contain the same number
+%% of elements - usually exactly one (e.g., the group containing the
+%% argument expression of a case-expression). Note, however, that the
+%% exact structure of the returned list (for a given node type) should
+%% in general not be depended upon, since it might be subject to
+%% change without notice.</p>
+%%
+%% <p>The function <code>subtrees/1</code> and the constructor functions
+%% <code>make_tree/2</code> and <code>update_tree/2</code> can be a
+%% great help if one wants to traverse a syntax tree, visiting all its
+%% subtrees, but treat nodes of the tree in a uniform way in most or all
+%% cases. Using these functions makes this simple, and also assures that
+%% your code is not overly sensitive to extensions of the syntax tree
+%% data type, because any node types not explicitly handled by your code
+%% can be left to a default case.</p>
+%%
+%% <p>For example:
+%% <pre>
+%%   postorder(F, Tree) ->
+%%       F(case subtrees(Tree) of
+%%           [] -> Tree;
+%%           List -> update_tree(Tree,
+%%                               [[postorder(F, Subtree)
+%%                                 || Subtree &lt;- Group]
+%%                                || Group &lt;- List])
+%%         end).
+%% </pre>
+%% maps the function <code>F</code> on <code>Tree</code> and all its
+%% subtrees, doing a post-order traversal of the syntax tree. (Note
+%% the use of <code>update_tree/2</code> to preserve annotations.) For
+%% a simple function like:
+%% <pre>
+%%   f(Node) ->
+%%       case type(Node) of
+%%           atom -> atom("a_" ++ atom_name(Node));
+%%           _ -> Node
+%%       end.
+%% </pre>
+%% the call <code>postorder(fun f/1, Tree)</code> will yield a new
+%% representation of <code>Tree</code> in which all atom names have
+%% been extended with the prefix "a_", but nothing else (including
+%% annotations) has been changed.</p>
+%%
+%% @see is_leaf/1
+%% @see make_tree/2
+%% @see update_tree/2
+
+-spec subtrees(cerl()) -> [[cerl()]].
+
+subtrees(T) ->
+    case is_leaf(T) of
+	true ->
+	    [];
+	false ->
+	    case type(T) of
+		values ->
+		    [values_es(T)];
+		binary ->
+		    [binary_segments(T)];
+		bitstr ->
+		    [[bitstr_val(T)], [bitstr_size(T)],
+		     [bitstr_unit(T)], [bitstr_type(T)],
+		     [bitstr_flags(T)]];
+		cons ->
+		    [[cons_hd(T)], [cons_tl(T)]];
+		tuple ->
+		    [tuple_es(T)];
+		map ->
+		    [map_es(T)];
+		map_pair ->
+		    [[map_pair_op(T)],[map_pair_key(T)],[map_pair_val(T)]];
+		'let' ->
+		    [let_vars(T), [let_arg(T)], [let_body(T)]];
+		seq ->
+		    [[seq_arg(T)], [seq_body(T)]];
+		apply ->
+		    [[apply_op(T)], apply_args(T)];
+		call ->
+		    [[call_module(T)], [call_name(T)],
+		     call_args(T)];
+		primop ->
+		    [[primop_name(T)], primop_args(T)];
+		'case' ->
+		    [[case_arg(T)], case_clauses(T)];
+		clause ->
+		    [clause_pats(T), [clause_guard(T)],
+		     [clause_body(T)]];
+		alias ->
+		    [[alias_var(T)], [alias_pat(T)]];
+		'fun' ->
+		    [fun_vars(T), [fun_body(T)]];
+		'receive' ->
+		    [receive_clauses(T), [receive_timeout(T)],
+		     [receive_action(T)]];
+		'try' ->
+		    [[try_arg(T)], try_vars(T), [try_body(T)],
+		     try_evars(T), [try_handler(T)]];
+		'catch' ->
+		    [[catch_body(T)]];
+		letrec ->
+		    Es = unfold_tuples(letrec_defs(T)),
+		    [Es, [letrec_body(T)]];
+		module ->
+		    As = unfold_tuples(module_attrs(T)),
+		    Es = unfold_tuples(module_defs(T)),
+		    [[module_name(T)], module_exports(T), As, Es]
+	    end
+    end.
+
+
+%% @spec update_tree(Old::cerl(), Groups::[[cerl()]]) -> cerl()
+%%
+%% @doc Creates a syntax tree with the given subtrees, and the same
+%% type and annotations as the <code>Old</code> node. This is
+%% equivalent to <code>ann_make_tree(get_ann(Node), type(Node),
+%% Groups)</code>, but potentially more efficient.
+%%
+%% @see update_tree/3
+%% @see ann_make_tree/3
+%% @see get_ann/1
+%% @see type/1
+
+-spec update_tree(cerl(), [[cerl()],...]) -> cerl().
+
+update_tree(Node, Gs) ->
+    ann_make_tree(get_ann(Node), type(Node), Gs).
+
+
+%% @spec update_tree(Old::cerl(), Type::ctype(), Groups::[[cerl()]]) ->
+%%           cerl()
+%%
+%% @doc Creates a syntax tree with the given type and subtrees, and
+%% the same annotations as the <code>Old</code> node. This is
+%% equivalent to <code>ann_make_tree(get_ann(Node), Type,
+%% Groups)</code>, but potentially more efficient.
+%%
+%% @see update_tree/2
+%% @see ann_make_tree/3
+%% @see get_ann/1
+
+-spec update_tree(cerl(), ctype(), [[cerl()],...]) -> cerl().
+
+update_tree(Node, Type, Gs) ->
+    ann_make_tree(get_ann(Node), Type, Gs).
+
+
+%% @spec make_tree(Type::ctype(), Groups::[[cerl()]]) -> cerl()
+%%
+%% @doc Creates a syntax tree with the given type and subtrees.
+%% <code>Type</code> must be a node type name
+%% (cf. <code>type/1</code>) that does not denote a leaf node type
+%% (cf. <code>is_leaf/1</code>).  <code>Groups</code> must be a
+%% <em>nonempty</em> list of groups of syntax trees, representing the
+%% subtrees of a node of the given type, in left-to-right order as
+%% they would occur in the printed program text, grouped by category
+%% as done by <code>subtrees/1</code>.
+%%
+%% <p>The result of <code>ann_make_tree(get_ann(Node), type(Node),
+%% subtrees(Node))</code> (cf. <code>update_tree/2</code>) represents
+%% the same source code text as the original <code>Node</code>,
+%% assuming that <code>subtrees(Node)</code> yields a nonempty
+%% list. However, it does not necessarily have the exact same data
+%% representation as <code>Node</code>.</p>
+%%
+%% @see ann_make_tree/3
+%% @see type/1
+%% @see is_leaf/1
+%% @see subtrees/1
+%% @see update_tree/2
+
+-spec make_tree(ctype(), [[cerl()],...]) -> cerl().
+
+make_tree(Type, Gs) ->
+    ann_make_tree([], Type, Gs).
+
+
+%% @spec ann_make_tree(As::anns(), Type::ctype(),
+%%                     Groups::[[cerl()]]) -> cerl()
+%%
+%% @doc Creates a syntax tree with the given annotations, type and
+%% subtrees. See <code>make_tree/2</code> for details.
+%%
+%% @see make_tree/2
+
+-spec ann_make_tree(anns(), ctype(), [[cerl()],...]) -> cerl().
+
+ann_make_tree(As, values, [Es]) -> ann_c_values(As, Es);
+ann_make_tree(As, binary, [Ss]) -> ann_c_binary(As, Ss);
+ann_make_tree(As, bitstr, [[V],[S],[U],[T],[Fs]]) ->
+    ann_c_bitstr(As, V, S, U, T, Fs);
+ann_make_tree(As, cons, [[H], [T]]) -> ann_c_cons(As, H, T);
+ann_make_tree(As, tuple, [Es]) -> ann_c_tuple(As, Es);
+ann_make_tree(As, map, [Es]) -> ann_c_map(As, Es);
+ann_make_tree(As, map, [[A], Es]) -> ann_c_map(As, A, Es);
+ann_make_tree(As, map_pair, [[Op], [K], [V]]) -> ann_c_map_pair(As, Op, K, V);
+ann_make_tree(As, 'let', [Vs, [A], [B]]) -> ann_c_let(As, Vs, A, B);
+ann_make_tree(As, seq, [[A], [B]]) -> ann_c_seq(As, A, B);
+ann_make_tree(As, apply, [[Op], Es]) -> ann_c_apply(As, Op, Es);
+ann_make_tree(As, call, [[M], [N], Es]) -> ann_c_call(As, M, N, Es);
+ann_make_tree(As, primop, [[N], Es]) -> ann_c_primop(As, N, Es);
+ann_make_tree(As, 'case', [[A], Cs]) -> ann_c_case(As, A, Cs);
+ann_make_tree(As, clause, [Ps, [G], [B]]) -> ann_c_clause(As, Ps, G, B);
+ann_make_tree(As, alias, [[V], [P]]) -> ann_c_alias(As, V, P);
+ann_make_tree(As, 'fun', [Vs, [B]]) -> ann_c_fun(As, Vs, B);
+ann_make_tree(As, 'receive', [Cs, [T], [A]]) ->
+    ann_c_receive(As, Cs, T, A);
+ann_make_tree(As, 'try', [[E], Vs, [B], Evs, [H]]) ->
+    ann_c_try(As, E, Vs, B, Evs, H);
+ann_make_tree(As, 'catch', [[B]]) -> ann_c_catch(As, B);
+ann_make_tree(As, letrec, [Es, [B]]) ->
+    ann_c_letrec(As, fold_tuples(Es), B);
+ann_make_tree(As, module, [[N], Xs, Es, Ds]) ->
+    ann_c_module(As, N, Xs, fold_tuples(Es), fold_tuples(Ds)).
+
+
+%% ---------------------------------------------------------------------
+
+%% @spec meta(Tree::cerl()) -> cerl()
+%%
+%% @doc Creates a meta-representation of a syntax tree. The result
+%% represents an Erlang expression "<code><em>MetaTree</em></code>"
+%% which, if evaluated, will yield a new syntax tree representing the
+%% same source code text as <code>Tree</code> (although the actual
+%% data representation may be different). The expression represented
+%% by <code>MetaTree</code> is <em>implementation independent</em>
+%% with regard to the data structures used by the abstract syntax tree
+%% implementation.
+%%
+%% <p>Any node in <code>Tree</code> whose node type is
+%% <code>var</code> (cf. <code>type/1</code>), and whose list of
+%% annotations (cf. <code>get_ann/1</code>) contains the atom
+%% <code>meta_var</code>, will remain unchanged in the resulting tree,
+%% except that exactly one occurrence of <code>meta_var</code> is
+%% removed from its annotation list.</p>
+%%
+%% <p>The main use of the function <code>meta/1</code> is to transform
+%% a data structure <code>Tree</code>, which represents a piece of
+%% program code, into a form that is <em>representation independent
+%% when printed</em>. E.g., suppose <code>Tree</code> represents a
+%% variable named "V". Then (assuming a function <code>print/1</code>
+%% for printing syntax trees), evaluating
+%% <code>print(abstract(Tree))</code> - simply using
+%% <code>abstract/1</code> to map the actual data structure onto a
+%% syntax tree representation - would output a string that might look
+%% something like "<code>{var, ..., 'V'}</code>", which is obviously
+%% dependent on the implementation of the abstract syntax trees. This
+%% could e.g. be useful for caching a syntax tree in a file. However,
+%% in some situations like in a program generator generator (with two
+%% "generator"), it may be unacceptable.  Using
+%% <code>print(meta(Tree))</code> instead would output a
+%% <em>representation independent</em> syntax tree generating
+%% expression; in the above case, something like
+%% "<code>cerl:c_var('V')</code>".</p>
+%%
+%% <p>The implementation tries to generate compact code with respect
+%% to literals and lists.</p>
+%%
+%% @see abstract/1
+%% @see type/1
+%% @see get_ann/1
+
+-spec meta(cerl()) -> cerl().
+
+meta(Node) ->
+    %% First of all we check for metavariables:
+    case type(Node) of
+	var ->
+	    case lists:member(meta_var, get_ann(Node)) of
+		false ->
+		    meta_0(var, Node);
+		true ->
+		    %% A meta-variable: remove the first found
+		    %% 'meta_var' annotation, but otherwise leave
+		    %% the node unchanged.
+		    set_ann(Node, lists:delete(meta_var, get_ann(Node)))
+	    end;
+	Type ->
+	    meta_0(Type, Node)
+    end.
+
+meta_0(Type, Node) ->
+    case get_ann(Node) of
+	[] ->
+	    meta_1(Type, Node);
+	As ->
+	    meta_call(set_ann, [meta_1(Type, Node), abstract(As)])
+    end.
+
+meta_1(literal, Node) ->
+    %% We handle atomic literals separately, to get a bit
+    %% more compact code. For the rest, we use 'abstract'.
+    case concrete(Node) of
+	V when is_atom(V) ->
+	    meta_call(c_atom, [Node]);
+	V when is_integer(V) ->
+	    meta_call(c_int, [Node]);
+	V when is_float(V) ->
+	    meta_call(c_float, [Node]);
+	[] ->
+	    meta_call(c_nil, []);
+	_ ->
+	    meta_call(abstract, [Node])
+    end;
+meta_1(var, Node) ->
+    %% A normal variable or function name.
+    meta_call(c_var, [abstract(var_name(Node))]);
+meta_1(values, Node) ->
+    meta_call(c_values,
+	      [make_list(meta_list(values_es(Node)))]);
+meta_1(binary, Node) ->
+    meta_call(c_binary,
+	      [make_list(meta_list(binary_segments(Node)))]);
+meta_1(bitstr, Node) ->
+    meta_call(c_bitstr,
+	      [meta(bitstr_val(Node)),
+	       meta(bitstr_size(Node)),
+	       meta(bitstr_unit(Node)),
+	       meta(bitstr_type(Node)),
+	       meta(bitstr_flags(Node))]);
+meta_1(cons, Node) ->
+    %% The list is split up if some sublist has annotatations. If
+    %% we get exactly one element, we generate a 'c_cons' call
+    %% instead of 'make_list' to reconstruct the node.
+    case split_list(Node) of
+	{[H], Node1} ->
+	    meta_call(c_cons, [meta(H), meta(Node1)]);
+	{L, Node1} ->
+	    meta_call(make_list,
+		      [make_list(meta_list(L)), meta(Node1)])
+    end;
+meta_1(tuple, Node) ->
+    meta_call(c_tuple,
+	      [make_list(meta_list(tuple_es(Node)))]);
+meta_1('let', Node) ->
+    meta_call(c_let,
+	      [make_list(meta_list(let_vars(Node))),
+	       meta(let_arg(Node)), meta(let_body(Node))]);
+meta_1(seq, Node) ->
+    meta_call(c_seq,
+	      [meta(seq_arg(Node)), meta(seq_body(Node))]);
+meta_1(apply, Node) ->
+    meta_call(c_apply,
+	      [meta(apply_op(Node)),
+	       make_list(meta_list(apply_args(Node)))]);
+meta_1(call, Node) ->
+    meta_call(c_call,
+	      [meta(call_module(Node)), meta(call_name(Node)),
+	       make_list(meta_list(call_args(Node)))]);
+meta_1(primop, Node) ->
+    meta_call(c_primop,
+	      [meta(primop_name(Node)),
+	       make_list(meta_list(primop_args(Node)))]);
+meta_1('case', Node) ->
+    meta_call(c_case,
+	      [meta(case_arg(Node)),
+	       make_list(meta_list(case_clauses(Node)))]);
+meta_1(clause, Node) ->
+    meta_call(c_clause,
+	      [make_list(meta_list(clause_pats(Node))),
+	       meta(clause_guard(Node)),
+	       meta(clause_body(Node))]);
+meta_1(alias, Node) ->
+    meta_call(c_alias,
+	      [meta(alias_var(Node)), meta(alias_pat(Node))]);
+meta_1('fun', Node) ->
+    meta_call(c_fun,
+	      [make_list(meta_list(fun_vars(Node))),
+	       meta(fun_body(Node))]);
+meta_1('receive', Node) ->
+    meta_call(c_receive,
+	      [make_list(meta_list(receive_clauses(Node))),
+	       meta(receive_timeout(Node)),
+	       meta(receive_action(Node))]);
+meta_1('try', Node) ->
+    meta_call(c_try,
+	      [meta(try_arg(Node)),
+	       make_list(meta_list(try_vars(Node))),
+	       meta(try_body(Node)),
+	       make_list(meta_list(try_evars(Node))),
+	       meta(try_handler(Node))]);
+meta_1('catch', Node) ->
+    meta_call(c_catch, [meta(catch_body(Node))]);
+meta_1(letrec, Node) ->
+    meta_call(c_letrec,
+	      [make_list([c_tuple([meta(N), meta(F)])
+			  || {N, F} <- letrec_defs(Node)]),
+	       meta(letrec_body(Node))]);
+meta_1(module, Node) ->
+    meta_call(c_module,
+	      [meta(module_name(Node)),
+	       make_list(meta_list(module_exports(Node))),
+	       make_list([c_tuple([meta(A), meta(V)])
+			  || {A, V} <- module_attrs(Node)]),
+	       make_list([c_tuple([meta(N), meta(F)])
+			  || {N, F} <- module_defs(Node)])]).
+
+meta_call(F, As) ->
+    c_call(c_atom(?MODULE), c_atom(F), As).
+
+meta_list([T | Ts]) ->
+    [meta(T) | meta_list(Ts)];
+meta_list([]) ->
+    [].
+
+split_list(Node) ->
+    split_list(set_ann(Node, []), []).
+
+split_list(Node, L) ->
+    A = get_ann(Node),
+    case type(Node) of
+	cons when A =:= [] ->
+	    split_list(cons_tl(Node), [cons_hd(Node) | L]);
+	_ ->
+	    {lists:reverse(L), Node}
+    end.
+
+
+%% ---------------------------------------------------------------------
+
+%% General utilities
+
+is_lit_list([#c_literal{} | Es]) ->
+    is_lit_list(Es);
+is_lit_list([_ | _]) ->
+    false;
+is_lit_list([]) ->
+    true.
+
+lit_list_vals([#c_literal{val = V} | Es]) ->
+    [V | lit_list_vals(Es)];
+lit_list_vals([]) ->
+    [].
+
+-spec make_lit_list([litval()]) -> [c_literal()].
+
+make_lit_list([V | Vs]) ->
+    [#c_literal{val = V} | make_lit_list(Vs)];
+make_lit_list([]) ->
+    [].
+
+%% The following tests are the same as done by 'io_lib:char_list' and
+%% 'io_lib:printable_list', respectively, but for a single character.
+
+is_char_value(V) when V >= $\000, V =< $\377 -> true;
+is_char_value(_) -> false.
+
+is_print_char_value(V) when V >= $\040, V =< $\176 -> true;
+is_print_char_value(V) when V >= $\240, V =< $\377 -> true;
+is_print_char_value(V) when V =:= $\b -> true;
+is_print_char_value(V) when V =:= $\d -> true;
+is_print_char_value(V) when V =:= $\e -> true;
+is_print_char_value(V) when V =:= $\f -> true;
+is_print_char_value(V) when V =:= $\n -> true;
+is_print_char_value(V) when V =:= $\r -> true;
+is_print_char_value(V) when V =:= $\s -> true;
+is_print_char_value(V) when V =:= $\t -> true;
+is_print_char_value(V) when V =:= $\v -> true;
+is_print_char_value(V) when V =:= $\" -> true;
+is_print_char_value(V) when V =:= $\' -> true;      %' stupid Emacs.
+is_print_char_value(V) when V =:= $\\ -> true;
+is_print_char_value(_) -> false.
+
+is_char_list([V | Vs]) when is_integer(V) ->
+    is_char_value(V) andalso is_char_list(Vs);
+is_char_list([]) ->
+    true;
+is_char_list(_) ->
+    false.
+
+is_print_char_list([V | Vs]) when is_integer(V) ->
+    is_print_char_value(V) andalso is_print_char_list(Vs);
+is_print_char_list([]) ->
+    true;
+is_print_char_list(_) ->
+    false.
+
+unfold_tuples([{X, Y} | Ps]) ->
+    [X, Y | unfold_tuples(Ps)];
+unfold_tuples([]) ->
+    [].
+
+fold_tuples([X, Y | Es]) ->
+    [{X, Y} | fold_tuples(Es)];
+fold_tuples([]) ->
+    [].
diff --git a/lib/dialyzer/test/opaque_SUITE_data/src/recrec/core_parse.hrl b/lib/dialyzer/test/opaque_SUITE_data/src/recrec/core_parse.hrl
new file mode 100644
index 0000000000..5823622f05
--- /dev/null
+++ b/lib/dialyzer/test/opaque_SUITE_data/src/recrec/core_parse.hrl
@@ -0,0 +1,122 @@
+%%
+%% %CopyrightBegin%
+%% 
+%% Copyright Ericsson AB 1999-2016. All Rights Reserved.
+%% 
+%% Licensed under the Apache License, Version 2.0 (the "License");
+%% you may not use this file except in compliance with the License.
+%% You may obtain a copy of the License at
+%%
+%%     http://www.apache.org/licenses/LICENSE-2.0
+%%
+%% Unless required by applicable law or agreed to in writing, software
+%% distributed under the License is distributed on an "AS IS" BASIS,
+%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+%% See the License for the specific language governing permissions and
+%% limitations under the License.
+%% 
+%% %CopyrightEnd%
+%%
+%% Purpose : Core Erlang syntax trees as records.
+
+%% It would be nice to incorporate some generic functions as well but
+%% this could make including this file difficult.
+
+%% Note: the annotation list is *always* the first record field.
+%% Thus it is possible to define the macros:
+%% -define(get_ann(X), element(2, X)).
+%% -define(set_ann(X, Y), setelement(2, X, Y)).
+
+%% The record definitions appear alphabetically
+
+-record(c_alias, {anno=[] :: cerl:anns(),
+		  var     :: cerl:c_var(),
+		  pat     :: cerl:cerl()}).
+
+-record(c_apply, {anno=[] :: cerl:anns(),
+		  op      :: cerl:c_var(),
+		  args    :: [cerl:cerl()]}).
+
+-record(c_binary, {anno=[]  :: cerl:anns(),
+		   segments :: [cerl:c_bitstr()]}).
+
+-record(c_bitstr, {anno=[], val,	% val :: Tree,
+		   size,	       	% size :: Tree,
+		   unit,	       	% unit :: Tree,
+		   type,	       	% type :: Tree,
+		   flags}).	       	% flags :: Tree
+
+-record(c_call, {anno=[], module,	% module :: cerl:cerl(),
+		 name,			% name :: cerl:cerl(),
+		 args}).		% args :: [cerl:cerl()]
+
+-record(c_case, {anno=[] :: cerl:anns(),
+		 arg     :: cerl:cerl(),
+		 clauses :: [cerl:cerl()]}).
+
+-record(c_catch, {anno=[] :: cerl:anns(), body :: cerl:cerl()}).
+
+-record(c_clause, {anno=[] :: cerl:anns(),
+		   pats,    % :: [cerl:cerl()],	% pats :: [Tree],
+		   guard,   % :: cerl:cerl(),		% guard :: Tree,
+		   body}).  % :: cerl:cerl()}).		% body :: Tree
+
+-record(c_cons, {anno=[] :: cerl:anns(),
+		 hd      :: cerl:cerl(),
+		 tl      :: cerl:cerl()}).
+
+-record(c_fun, {anno=[] :: cerl:anns(),
+		vars    :: [cerl:c_var()],
+		body    :: cerl:cerl()}).
+
+-record(c_let, {anno=[] :: cerl:anns(),
+		vars    :: [cerl:c_var()],
+		arg     :: cerl:cerl(),
+		body    :: cerl:cerl()}).
+
+-record(c_letrec, {anno=[] :: cerl:anns(),
+		   defs    :: cerl:defs(),
+		   body    :: cerl:cerl()}).
+
+-record(c_literal, {anno=[] :: cerl:anns(), val :: cerl:litval()}).
+
+-record(c_map, {anno=[] :: cerl:anns(),
+		arg=#c_literal{val=#{}} :: cerl:c_var() | cerl:c_literal(),
+		es :: [cerl:c_map_pair()],
+		is_pat=false :: boolean()}).
+
+-record(c_map_pair, {anno=[] :: cerl:anns(),
+	             op, %:: #c_literal{val::'assoc'} | #c_literal{val::'exact'},
+		     key,
+		     val}).
+
+-record(c_module, {anno=[] :: cerl:anns(),
+		   name    :: cerl:c_literal(),
+		   exports :: [cerl:c_var()],
+		   attrs   :: cerl:attrs(),
+		   defs    :: cerl:defs()}).
+
+-record(c_primop, {anno=[] :: cerl:anns(),
+		   name    :: cerl:c_literal(),
+		   args    :: [cerl:cerl()]}).
+
+-record(c_receive, {anno=[]:: cerl:anns(),
+                    clauses,	% clauses :: [Tree],
+		    timeout,		% timeout :: Tree,
+		    action}).		% action :: Tree
+
+-record(c_seq, {anno=[] :: cerl:anns(),
+                arg,		% arg :: cerl:cerl(),
+		body}).			% body :: cerl:cerl()
+
+-record(c_try, {anno=[], arg,		% arg :: cerl:cerl(),
+		vars,			% vars :: [cerl:c_var()],
+		body,			% body :: cerl:cerl(),
+		evars,			% evars :: [cerl:c_var()],
+		handler}).		% handler :: cerl:cerl()
+
+-record(c_tuple, {anno=[] :: cerl:anns(), es :: [cerl:cerl()]}).
+
+-record(c_values, {anno=[] :: cerl:anns(), es :: [cerl:cerl()]}).
+
+-record(c_var, {anno=[] :: cerl:anns(), name :: cerl:var_name()}).
diff --git a/lib/dialyzer/test/opaque_SUITE_data/src/recrec/dialyzer.hrl b/lib/dialyzer/test/opaque_SUITE_data/src/recrec/dialyzer.hrl
new file mode 100644
index 0000000000..ea6a71217c
--- /dev/null
+++ b/lib/dialyzer/test/opaque_SUITE_data/src/recrec/dialyzer.hrl
@@ -0,0 +1,180 @@
+%%% This is an -*- Erlang -*- file.
+%%%
+%%% %CopyrightBegin%
+%%%
+%%% Copyright Ericsson AB 2006-2015. All Rights Reserved.
+%%%
+%%% Licensed under the Apache License, Version 2.0 (the "License");
+%%% you may not use this file except in compliance with the License.
+%%% You may obtain a copy of the License at
+%%%
+%%%     http://www.apache.org/licenses/LICENSE-2.0
+%%%
+%%% Unless required by applicable law or agreed to in writing, software
+%%% distributed under the License is distributed on an "AS IS" BASIS,
+%%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+%%% See the License for the specific language governing permissions and
+%%% limitations under the License.
+%%%
+%%% %CopyrightEnd%
+%%%
+%%%-------------------------------------------------------------------
+%%% File    : dialyzer.hrl
+%%% Author  : Tobias Lindahl <[email protected]>
+%%%           Kostis Sagonas <[email protected]>
+%%% Description : Header file for Dialyzer.
+%%%
+%%% Created : 1 Oct 2004 by Kostis Sagonas <[email protected]>
+%%%-------------------------------------------------------------------
+
+-define(RET_NOTHING_SUSPICIOUS, 0).
+-define(RET_INTERNAL_ERROR, 1).
+-define(RET_DISCREPANCIES, 2).
+
+-type dial_ret() :: ?RET_NOTHING_SUSPICIOUS
+                  | ?RET_INTERNAL_ERROR
+                  | ?RET_DISCREPANCIES.
+
+%%--------------------------------------------------------------------
+%% Warning classification
+%%--------------------------------------------------------------------
+
+-define(WARN_RETURN_NO_RETURN, warn_return_no_exit).
+-define(WARN_RETURN_ONLY_EXIT, warn_return_only_exit).
+-define(WARN_NOT_CALLED, warn_not_called).
+-define(WARN_NON_PROPER_LIST, warn_non_proper_list).
+-define(WARN_FUN_APP, warn_fun_app).
+-define(WARN_MATCHING, warn_matching).
+-define(WARN_OPAQUE, warn_opaque).
+-define(WARN_FAILING_CALL, warn_failing_call).
+-define(WARN_BIN_CONSTRUCTION, warn_bin_construction).
+-define(WARN_CONTRACT_TYPES, warn_contract_types).
+-define(WARN_CONTRACT_SYNTAX, warn_contract_syntax).
+-define(WARN_CONTRACT_NOT_EQUAL, warn_contract_not_equal).
+-define(WARN_CONTRACT_SUBTYPE, warn_contract_subtype).
+-define(WARN_CONTRACT_SUPERTYPE, warn_contract_supertype).
+-define(WARN_CONTRACT_RANGE, warn_contract_range).
+-define(WARN_CALLGRAPH, warn_callgraph).
+-define(WARN_UNMATCHED_RETURN, warn_umatched_return).
+-define(WARN_RACE_CONDITION, warn_race_condition).
+-define(WARN_BEHAVIOUR, warn_behaviour).
+-define(WARN_UNDEFINED_CALLBACK, warn_undefined_callbacks).
+-define(WARN_UNKNOWN, warn_unknown).
+-define(WARN_MAP_CONSTRUCTION, warn_map_construction).
+
+%%
+%% The following type has double role:
+%%   1. It is the set of warnings that will be collected.
+%%   2. It is also the set of tags for warnings that will be returned.
+%%
+-type dial_warn_tag() :: ?WARN_RETURN_NO_RETURN | ?WARN_RETURN_ONLY_EXIT
+                       | ?WARN_NOT_CALLED | ?WARN_NON_PROPER_LIST
+                       | ?WARN_MATCHING | ?WARN_OPAQUE | ?WARN_FUN_APP
+                       | ?WARN_FAILING_CALL | ?WARN_BIN_CONSTRUCTION
+                       | ?WARN_CONTRACT_TYPES | ?WARN_CONTRACT_SYNTAX
+                       | ?WARN_CONTRACT_NOT_EQUAL | ?WARN_CONTRACT_SUBTYPE
+                       | ?WARN_CONTRACT_SUPERTYPE | ?WARN_CALLGRAPH
+                       | ?WARN_UNMATCHED_RETURN | ?WARN_RACE_CONDITION
+                       | ?WARN_BEHAVIOUR | ?WARN_CONTRACT_RANGE
+		       | ?WARN_UNDEFINED_CALLBACK | ?WARN_UNKNOWN
+		       | ?WARN_MAP_CONSTRUCTION.
+
+%%
+%% This is the representation of each warning as they will be returned
+%% to dialyzer's callers
+%%
+-type file_line()    :: {file:filename(), non_neg_integer()}.
+-type dial_warning() :: {dial_warn_tag(), file_line(), {atom(), [term()]}}.
+
+%%
+%% This is the representation of each warning before suppressions have
+%% been applied
+%%
+-type m_or_mfa()     :: module() % warnings not associated with any function
+                      | mfa().
+-type warning_info() :: {file:filename(), non_neg_integer(), m_or_mfa()}.
+-type raw_warning()  :: {dial_warn_tag(), warning_info(), {atom(), [term()]}}.
+
+%%
+%% This is the representation of dialyzer's internal errors
+%%
+-type dial_error()   :: any().    %% XXX: underspecified
+
+%%--------------------------------------------------------------------
+%% Basic types used either in the record definitions below or in other
+%% parts of the application
+%%--------------------------------------------------------------------
+
+-type anal_type()     :: 'succ_typings' | 'plt_build'.
+-type anal_type1()    :: anal_type() | 'plt_add' | 'plt_check' | 'plt_remove'.
+-type contr_constr()  :: {'subtype', erl_types:erl_type(), erl_types:erl_type()}.
+-type contract_pair() :: {erl_types:erl_type(), [contr_constr()]}.
+-type dial_define()   :: {atom(), term()}.
+-type dial_option()   :: {atom(), term()}.
+-type dial_options()  :: [dial_option()].
+-type fopt()          :: 'basename' | 'fullpath'.
+-type format()        :: 'formatted' | 'raw'.
+-type label()	      :: non_neg_integer().
+-type dial_warn_tags():: ordsets:ordset(dial_warn_tag()).
+-type rep_mode()      :: 'quiet' | 'normal' | 'verbose'.
+-type start_from()    :: 'byte_code' | 'src_code'.
+-type mfa_or_funlbl() :: label() | mfa().
+-type solver()        :: 'v1' | 'v2'.
+
+%%--------------------------------------------------------------------
+%% Record declarations used by various files
+%%--------------------------------------------------------------------
+
+-type doc_plt() :: 'undefined' | dialyzer_plt:plt().
+
+-record(analysis, {analysis_pid			   :: pid() | 'undefined',
+		   type		  = succ_typings   :: anal_type(),
+		   defines	  = []		   :: [dial_define()],
+		   doc_plt                         :: doc_plt(),
+		   files          = []		   :: [file:filename()],
+		   include_dirs	  = []		   :: [file:filename()],
+		   start_from     = byte_code	   :: start_from(),
+		   plt                             :: dialyzer_plt:plt(),
+		   use_contracts  = true           :: boolean(),
+		   race_detection = false	   :: boolean(),
+		   behaviours_chk = false          :: boolean(),
+		   timing         = false          :: boolean() | 'debug',
+		   timing_server  = none           :: dialyzer_timing:timing_server(),
+		   callgraph_file = ""             :: file:filename(),
+                   solvers                         :: [solver()]}).
+
+-record(options, {files           = []		   :: [file:filename()],
+		  files_rec       = []		   :: [file:filename()],
+		  analysis_type   = succ_typings   :: anal_type1(),
+		  timing          = false          :: boolean() | 'debug',
+		  defines         = []		   :: [dial_define()],
+		  from            = byte_code	   :: start_from(),
+		  get_warnings    = maybe          :: boolean() | 'maybe',
+		  init_plts       = []	           :: [file:filename()],
+		  include_dirs    = []		   :: [file:filename()],
+		  output_plt      = none           :: 'none' | file:filename(),
+		  legal_warnings  = ordsets:new()  :: dial_warn_tags(),
+		  report_mode     = normal	   :: rep_mode(),
+		  erlang_mode     = false	   :: boolean(),
+		  use_contracts   = true           :: boolean(),
+		  output_file     = none	   :: 'none' | file:filename(),
+		  output_format   = formatted      :: format(),
+		  filename_opt	  = basename       :: fopt(),
+		  callgraph_file  = ""             :: file:filename(),
+		  check_plt       = true           :: boolean(),
+                  solvers         = []             :: [solver()]}).
+
+-record(contract, {contracts	  = []		   :: [contract_pair()],
+		   args		  = []		   :: [erl_types:erl_type()],
+		   forms	  = []		   :: [{_, _}]}).
+
+%%--------------------------------------------------------------------
+
+-define(timing(Server, Msg, Var, Expr),
+	begin
+	    dialyzer_timing:start_stamp(Server, Msg),
+	    Var = Expr,
+	    dialyzer_timing:end_stamp(Server),
+	    Var
+	end).
+-define(timing(Server, Msg, Expr), ?timing(Server, Msg, _T, Expr)).
diff --git a/lib/dialyzer/test/opaque_SUITE_data/src/recrec/dialyzer_dataflow.erl b/lib/dialyzer/test/opaque_SUITE_data/src/recrec/dialyzer_dataflow.erl
new file mode 100644
index 0000000000..9399789464
--- /dev/null
+++ b/lib/dialyzer/test/opaque_SUITE_data/src/recrec/dialyzer_dataflow.erl
@@ -0,0 +1,3802 @@
+%% -*- erlang-indent-level: 2 -*-
+%%--------------------------------------------------------------------
+%% %CopyrightBegin%
+%%
+%% Copyright Ericsson AB 2006-2016. All Rights Reserved.
+%%
+%% Licensed under the Apache License, Version 2.0 (the "License");
+%% you may not use this file except in compliance with the License.
+%% You may obtain a copy of the License at
+%%
+%%     http://www.apache.org/licenses/LICENSE-2.0
+%%
+%% Unless required by applicable law or agreed to in writing, software
+%% distributed under the License is distributed on an "AS IS" BASIS,
+%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+%% See the License for the specific language governing permissions and
+%% limitations under the License.
+%%
+%% %CopyrightEnd%
+%%
+
+%%%-------------------------------------------------------------------
+%%% File    : dialyzer_dataflow.erl
+%%% Author  : Tobias Lindahl <[email protected]>
+%%% Description :
+%%%
+%%% Created : 19 Apr 2005 by Tobias Lindahl <[email protected]>
+%%%-------------------------------------------------------------------
+
+-module(dialyzer_dataflow).
+
+-export([get_fun_types/5, get_warnings/5, format_args/3]).
+
+%% Data structure interfaces.
+-export([state__add_warning/2, state__cleanup/1,
+	 state__duplicate/1, dispose_state/1,
+         state__get_callgraph/1, state__get_races/1,
+         state__get_records/1, state__put_callgraph/2,
+         state__put_races/2, state__records_only/1,
+         state__find_function/2]).
+
+-export_type([state/0]).
+
+-include("dialyzer.hrl").
+
+-import(erl_types,
+        [t_inf/2, t_inf/3, t_inf_lists/2, t_inf_lists/3,
+         t_inf_lists/3, t_is_equal/2, t_is_subtype/2, t_subtract/2,
+         t_sup/1, t_sup/2]).
+
+-import(erl_types,
+	[any_none/1, t_any/0, t_atom/0, t_atom/1, t_atom_vals/1, t_atom_vals/2,
+	 t_binary/0, t_boolean/0,
+	 t_bitstr/0, t_bitstr/2, t_bitstr_concat/1, t_bitstr_match/2,
+	 t_cons/0, t_cons/2, t_cons_hd/2, t_cons_tl/2,
+         t_contains_opaque/2,
+	 t_find_opaque_mismatch/3, t_float/0, t_from_range/2, t_from_term/1,
+	 t_fun/0, t_fun/2, t_fun_args/1, t_fun_args/2, t_fun_range/1,
+	 t_fun_range/2, t_integer/0, t_integers/1,
+	 t_is_any/1, t_is_atom/1, t_is_atom/2, t_is_any_atom/3,
+         t_is_boolean/2,
+	 t_is_integer/2, t_is_list/1,
+	 t_is_nil/2, t_is_none/1, t_is_none_or_unit/1,
+	 t_is_number/2, t_is_reference/2, t_is_pid/2, t_is_port/2,
+         t_is_unit/1,
+	 t_limit/2, t_list/0, t_list_elements/2,
+	 t_maybe_improper_list/0, t_module/0,
+	 t_none/0, t_non_neg_integer/0, t_number/0, t_number_vals/2,
+	 t_pid/0, t_port/0, t_product/1, t_reference/0,
+         t_to_string/2, t_to_tlist/1,
+	 t_tuple/0, t_tuple/1, t_tuple_args/1, t_tuple_args/2,
+         t_tuple_subtypes/2,
+	 t_unit/0, t_unopaque/2,
+	 t_map/0, t_map/1, t_is_singleton/2
+     ]).
+
+%%-define(DEBUG, true).
+%%-define(DEBUG_PP, true).
+%%-define(DEBUG_TIME, true).
+
+-ifdef(DEBUG).
+-import(erl_types, [t_to_string/1]).
+-define(debug(S_, L_), io:format(S_, L_)).
+-else.
+-define(debug(S_, L_), ok).
+-endif.
+
+%%--------------------------------------------------------------------
+
+-type type()      :: erl_types:erl_type().
+-type types()     :: erl_types:type_table().
+
+-type curr_fun()  :: 'undefined' | 'top' | mfa_or_funlbl().
+
+-define(no_arg, no_arg).
+
+-define(TYPE_LIMIT, 3).
+
+-define(BITS, 128).
+
+%% Types with comment 'race' are due to dialyzer_races.erl.
+-record(state, {callgraph            :: dialyzer_callgraph:callgraph()
+                                      | 'undefined', % race
+                codeserver           :: dialyzer_codeserver:codeserver()
+                                      | 'undefined', % race
+		envs                 :: env_tab()
+                                      | 'undefined', % race
+		fun_tab		     :: fun_tab()
+                                      | 'undefined', % race
+                fun_homes            :: dict:dict(label(), mfa())
+                                      | 'undefined', % race
+		plt		     :: dialyzer_plt:plt()
+                                      | 'undefined', % race
+		opaques              :: [type()]
+                                      | 'undefined', % race
+		races = dialyzer_races:new() :: dialyzer_races:races(),
+		records = dict:new() :: types(),
+		tree_map	     :: dict:dict(label(), cerl:cerl())
+                                      | 'undefined', % race
+		warning_mode = false :: boolean(),
+		warnings = []        :: [raw_warning()],
+		work                 :: {[_], [_], sets:set()}
+                                      | 'undefined', % race
+		module               :: module(),
+                curr_fun             :: curr_fun()
+               }).
+
+-record(map, {map = maps:new()    :: type_tab(),
+              subst = maps:new()  :: subst_tab(),
+              modified = []       :: [Key :: term()],
+              modified_stack = [] :: [{[Key :: term()],reference()}],
+              ref = undefined     :: reference() | undefined}).
+
+-type env_tab()   :: dict:dict(label(), #map{}).
+-type fun_entry() :: {Args :: [type()], RetType :: type()}.
+-type fun_tab()   :: dict:dict('top' | label(),
+                               {'not_handled', fun_entry()} | fun_entry()).
+-type key()       :: label() | cerl:cerl().
+-type type_tab()  :: #{key() => type()}.
+-type subst_tab() :: #{key() => cerl:cerl()}.
+
+%% Exported Types
+
+-opaque state() :: #state{}.
+
+%%--------------------------------------------------------------------
+
+-type fun_types() :: dict:dict(label(), type()).
+
+-spec get_warnings(cerl:c_module(), dialyzer_plt:plt(),
+                   dialyzer_callgraph:callgraph(),
+                   dialyzer_codeserver:codeserver(),
+                   types()) ->
+	{[raw_warning()], fun_types()}.
+
+get_warnings(Tree, Plt, Callgraph, Codeserver, Records) ->
+  State1 = analyze_module(Tree, Plt, Callgraph, Codeserver, Records, true),
+  State2 = state__renew_warnings(state__get_warnings(State1), State1),
+  State3 = state__get_race_warnings(State2),
+  {State3#state.warnings, state__all_fun_types(State3)}.
+
+-spec get_fun_types(cerl:c_module(), dialyzer_plt:plt(),
+                    dialyzer_callgraph:callgraph(),
+                    dialyzer_codeserver:codeserver(),
+                    types()) -> fun_types().
+
+get_fun_types(Tree, Plt, Callgraph, Codeserver, Records) ->
+  State = analyze_module(Tree, Plt, Callgraph, Codeserver, Records, false),
+  state__all_fun_types(State).
+
+%%% ===========================================================================
+%%%
+%%%  The analysis.
+%%%
+%%% ===========================================================================
+
+analyze_module(Tree, Plt, Callgraph, Codeserver, Records, GetWarnings) ->
+  debug_pp(Tree, false),
+  Module = cerl:atom_val(cerl:module_name(Tree)),
+  TopFun = cerl:ann_c_fun([{label, top}], [], Tree),
+  State = state__new(Callgraph, Codeserver, TopFun, Plt, Module, Records),
+  State1 = state__race_analysis(not GetWarnings, State),
+  State2 = analyze_loop(State1),
+  case GetWarnings of
+    true ->
+      State3 = state__set_warning_mode(State2),
+      State4 = analyze_loop(State3),
+      dialyzer_races:race(State4);
+    false ->
+      State2
+  end.
+
+analyze_loop(State) ->
+  case state__get_work(State) of
+    none -> state__set_curr_fun(undefined, State);
+    {Fun, NewState0} ->
+      NewState1 = state__set_curr_fun(get_label(Fun), NewState0),
+      {ArgTypes, IsCalled} = state__get_args_and_status(Fun, NewState1),
+      case not IsCalled of
+	true ->
+	  ?debug("Not handling (not called) ~w: ~s\n",
+		 [NewState1#state.curr_fun,
+		  t_to_string(t_product(ArgTypes))]),
+	  analyze_loop(NewState1);
+	false ->
+	  case state__fun_env(Fun, NewState1) of
+	    none ->
+	      ?debug("Not handling (no env) ~w: ~s\n",
+		     [NewState1#state.curr_fun,
+		      t_to_string(t_product(ArgTypes))]),
+	      analyze_loop(NewState1);
+	    Map ->
+	      ?debug("Handling fun ~p: ~s\n",
+		     [NewState1#state.curr_fun,
+		      t_to_string(state__fun_type(Fun, NewState1))]),
+	      Vars = cerl:fun_vars(Fun),
+	      Map1 = enter_type_lists(Vars, ArgTypes, Map),
+	      Body = cerl:fun_body(Fun),
+              FunLabel = get_label(Fun),
+	      IsRaceAnalysisEnabled = is_race_analysis_enabled(State),
+              NewState3 =
+                case IsRaceAnalysisEnabled of
+                  true ->
+                    NewState2 = state__renew_curr_fun(
+                      state__lookup_name(FunLabel, NewState1), FunLabel,
+                      NewState1),
+                    state__renew_race_list([], 0, NewState2);
+		  false -> NewState1
+                end,
+	      {NewState4, _Map2, BodyType} =
+		traverse(Body, Map1, NewState3),
+	      ?debug("Done analyzing: ~w:~s\n",
+		     [NewState1#state.curr_fun,
+		      t_to_string(t_fun(ArgTypes, BodyType))]),
+              NewState5 =
+                case IsRaceAnalysisEnabled of
+                  true -> renew_race_code(NewState4);
+                  false -> NewState4
+                end,
+              NewState6 =
+                state__update_fun_entry(Fun, ArgTypes, BodyType, NewState5),
+              ?debug("done adding stuff for ~w\n",
+                     [state__lookup_name(get_label(Fun), State)]),
+              analyze_loop(NewState6)
+	  end
+      end
+  end.
+
+traverse(Tree, Map, State) ->
+  ?debug("Handling ~p\n", [cerl:type(Tree)]),
+  %% debug_pp_map(Map),
+  case cerl:type(Tree) of
+    alias ->
+      %% This only happens when checking for illegal record patterns
+      %% so the handling is a bit rudimentary.
+      traverse(cerl:alias_pat(Tree), Map, State);
+    apply ->
+      handle_apply(Tree, Map, State);
+    binary ->
+      Segs = cerl:binary_segments(Tree),
+      {State1, Map1, SegTypes} = traverse_list(Segs, Map, State),
+      {State1, Map1, t_bitstr_concat(SegTypes)};
+    bitstr ->
+      handle_bitstr(Tree, Map, State);
+    call ->
+      handle_call(Tree, Map, State);
+    'case' ->
+      handle_case(Tree, Map, State);
+    'catch' ->
+      {State1, _Map1, _} = traverse(cerl:catch_body(Tree), Map, State),
+      {State1, Map, t_any()};
+    cons ->
+      handle_cons(Tree, Map, State);
+    'fun' ->
+      Type = state__fun_type(Tree, State),
+      case state__warning_mode(State) of
+        true -> {State, Map, Type};
+        false ->
+          State2 = state__add_work(get_label(Tree), State),
+          State3 = state__update_fun_env(Tree, Map, State2),
+          {State3, Map, Type}
+      end;
+    'let' ->
+      handle_let(Tree, Map, State);
+    letrec ->
+      Defs = cerl:letrec_defs(Tree),
+      Body = cerl:letrec_body(Tree),
+      %% By not including the variables in scope we can assure that we
+      %% will get the current function type when using the variables.
+      FoldFun = fun({Var, Fun}, {AccState, AccMap}) ->
+		    {NewAccState, NewAccMap0, FunType} =
+		      traverse(Fun, AccMap, AccState),
+		    NewAccMap = enter_type(Var, FunType, NewAccMap0),
+		    {NewAccState, NewAccMap}
+		end,
+      {State1, Map1} = lists:foldl(FoldFun, {State, Map}, Defs),
+      traverse(Body, Map1, State1);
+    literal ->
+      Type = literal_type(Tree),
+      {State, Map, Type};
+    module ->
+      handle_module(Tree, Map, State);
+    primop ->
+      Type =
+	case cerl:atom_val(cerl:primop_name(Tree)) of
+	  match_fail -> t_none();
+	  raise -> t_none();
+	  bs_init_writable -> t_from_term(<<>>);
+	  Other -> erlang:error({'Unsupported primop', Other})
+	end,
+      {State, Map, Type};
+    'receive' ->
+      handle_receive(Tree, Map, State);
+    seq ->
+      Arg = cerl:seq_arg(Tree),
+      Body = cerl:seq_body(Tree),
+      {State1, Map1, ArgType} = SMA = traverse(Arg, Map, State),
+      case t_is_none_or_unit(ArgType) of
+	true ->
+	  SMA;
+	false ->
+	  State2 =
+	    case
+              t_is_any(ArgType)
+              orelse t_is_simple(ArgType, State)
+              orelse is_call_to_send(Arg)
+	      orelse is_lc_simple_list(Arg, ArgType, State)
+            of
+	      true -> % do not warn in these cases
+		State1;
+	      false ->
+		state__add_warning(State1, ?WARN_UNMATCHED_RETURN, Arg,
+				   {unmatched_return,
+				    [format_type(ArgType, State1)]})
+	    end,
+	  traverse(Body, Map1, State2)
+      end;
+    'try' ->
+      handle_try(Tree, Map, State);
+    tuple ->
+      handle_tuple(Tree, Map, State);
+    map ->
+      handle_map(Tree, Map, State);
+    values ->
+      Elements = cerl:values_es(Tree),
+      {State1, Map1, EsType} = traverse_list(Elements, Map, State),
+      Type = t_product(EsType),
+      {State1, Map1, Type};
+    var ->
+      ?debug("Looking up unknown variable: ~p\n", [Tree]),
+      case state__lookup_type_for_letrec(Tree, State) of
+	error ->
+	  LType = lookup_type(Tree, Map),
+          {State, Map, LType};
+	{ok, Type} -> {State, Map, Type}
+      end;
+    Other ->
+      erlang:error({'Unsupported type', Other})
+  end.
+
+traverse_list(Trees, Map, State) ->
+  traverse_list(Trees, Map, State, []).
+
+traverse_list([Tree|Tail], Map, State, Acc) ->
+  {State1, Map1, Type} = traverse(Tree, Map, State),
+  traverse_list(Tail, Map1, State1, [Type|Acc]);
+traverse_list([], Map, State, Acc) ->
+  {State, Map, lists:reverse(Acc)}.
+
+%%________________________________________
+%%
+%% Special instructions
+%%
+
+handle_apply(Tree, Map, State) ->
+  Args = cerl:apply_args(Tree),
+  Op = cerl:apply_op(Tree),
+  {State0, Map1, ArgTypes} = traverse_list(Args, Map, State),
+  {State1, Map2, OpType} = traverse(Op, Map1, State0),
+  case any_none(ArgTypes) of
+    true ->
+      {State1, Map2, t_none()};
+    false ->
+      FunList =
+	case state__lookup_call_site(Tree, State) of
+	  error -> [external]; %% so that we go directly in the fallback
+	  {ok, List} -> List
+	end,
+      FunInfoList = [{local, state__fun_info(Fun, State)} || Fun <- FunList],
+      case
+        handle_apply_or_call(FunInfoList, Args, ArgTypes, Map2, Tree, State1)
+      of
+	{had_external, State2} ->
+	  %% Fallback: use whatever info we collected from traversing the op
+	  %% instead of the result that has been generalized to t_any().
+	  Arity = length(Args),
+	  OpType1 = t_inf(OpType, t_fun(Arity, t_any())),
+	  case t_is_none(OpType1) of
+	    true ->
+	      Msg = {fun_app_no_fun,
+		     [format_cerl(Op), format_type(OpType, State2), Arity]},
+	      State3 = state__add_warning(State2, ?WARN_FAILING_CALL,
+					  Tree, Msg),
+	      {State3, Map2, t_none()};
+	    false ->
+	      NewArgs = t_inf_lists(ArgTypes,
+                                    t_fun_args(OpType1, 'universe')),
+	      case any_none(NewArgs) of
+		true ->
+		  Msg = {fun_app_args,
+			 [format_args(Args, ArgTypes, State),
+			  format_type(OpType, State)]},
+		  State3 = state__add_warning(State2, ?WARN_FAILING_CALL,
+					      Tree, Msg),
+		  {State3, enter_type(Op, OpType1, Map2), t_none()};
+		false ->
+		  Map3 = enter_type_lists(Args, NewArgs, Map2),
+		  Range0 = t_fun_range(OpType1, 'universe'),
+		  Range =
+		    case t_is_unit(Range0) of
+		      true  -> t_none();
+		      false -> Range0
+		    end,
+		  {State2, enter_type(Op, OpType1, Map3), Range}
+	      end
+	  end;
+	Normal -> Normal
+      end
+  end.
+
+handle_apply_or_call(FunInfoList, Args, ArgTypes, Map, Tree, State) ->
+  None = t_none(),
+  %% Call-site analysis may be inaccurate and consider more funs than those that
+  %% are actually possible. If all of them are incorrect, then warnings can be
+  %% emitted. If at least one fun is ok, however, then no warning is emitted,
+  %% just in case the bad ones are not really possible. The last argument is
+  %% used for this, with the following encoding:
+  %%   Initial value: {none, []}
+  %%   First fun checked: {one, <List of warns>}
+  %%   More funs checked: {many, <List of warns>}
+  %% A '{one, []}' can only become '{many, []}'.
+  %% If at any point an fun does not add warnings, then the list is also
+  %% replaced with an empty list.
+  handle_apply_or_call(FunInfoList, Args, ArgTypes, Map, Tree, State,
+		       [None || _ <- ArgTypes], None, false, {none, []}).
+
+handle_apply_or_call([{local, external}|Left], Args, ArgTypes, Map, Tree, State,
+		     _AccArgTypes, _AccRet, _HadExternal, Warns) ->
+  {HowMany, _} = Warns,
+  NewHowMany =
+    case HowMany of
+      none -> one;
+      _ -> many
+    end,
+  NewWarns = {NewHowMany, []},      
+  handle_apply_or_call(Left, Args, ArgTypes, Map, Tree, State,
+		       ArgTypes, t_any(), true, NewWarns);
+handle_apply_or_call([{TypeOfApply, {Fun, Sig, Contr, LocalRet}}|Left],
+		     Args, ArgTypes, Map, Tree,
+                     #state{opaques = Opaques} = State,
+                     AccArgTypes, AccRet, HadExternal, Warns) ->
+  Any = t_any(),
+  AnyArgs = [Any || _ <- Args],
+  GenSig = {AnyArgs, fun(_) -> t_any() end},
+  {CArgs, CRange} =
+    case Contr of
+      {value, #contract{args = As} = C} ->
+	{As, fun(FunArgs) ->
+		 dialyzer_contracts:get_contract_return(C, FunArgs)
+	     end};
+      none -> GenSig
+    end,
+  {BifArgs, BifRange} =
+    case TypeOfApply of
+      remote ->
+	{M, F, A} = Fun,
+	case erl_bif_types:is_known(M, F, A) of
+	  true ->
+	    BArgs = erl_bif_types:arg_types(M, F, A),
+	    BRange =
+	      fun(FunArgs) ->
+		  erl_bif_types:type(M, F, A, FunArgs, Opaques)
+	      end,
+	    {BArgs, BRange};
+          false ->
+            GenSig
+	end;
+      local -> GenSig
+    end,
+  {SigArgs, SigRange} =
+    case Sig of
+      {value, {SR, SA}} -> {SA, SR};
+      none -> {AnyArgs, t_any()}
+    end,
+
+  ?debug("--------------------------------------------------------\n", []),
+  ?debug("Fun: ~p\n", [state__lookup_name(Fun, State)]),
+  ?debug("Module ~p\n", [State#state.module]),
+  ?debug("CArgs ~s\n", [erl_types:t_to_string(t_product(CArgs))]),
+  ?debug("ArgTypes ~s\n", [erl_types:t_to_string(t_product(ArgTypes))]),
+  ?debug("BifArgs ~p\n", [erl_types:t_to_string(t_product(BifArgs))]),
+
+  NewArgsSig = t_inf_lists(SigArgs, ArgTypes, Opaques),
+  ?debug("SigArgs ~s\n", [erl_types:t_to_string(t_product(SigArgs))]),
+  ?debug("NewArgsSig: ~s\n", [erl_types:t_to_string(t_product(NewArgsSig))]),
+  NewArgsContract = t_inf_lists(CArgs, ArgTypes, Opaques),
+  ?debug("NewArgsContract: ~s\n",
+	 [erl_types:t_to_string(t_product(NewArgsContract))]),
+  NewArgsBif = t_inf_lists(BifArgs, ArgTypes, Opaques),
+  ?debug("NewArgsBif: ~s\n", [erl_types:t_to_string(t_product(NewArgsBif))]),
+  NewArgTypes0 = t_inf_lists(NewArgsSig, NewArgsContract),
+  NewArgTypes = t_inf_lists(NewArgTypes0, NewArgsBif, Opaques),
+  ?debug("NewArgTypes ~s\n", [erl_types:t_to_string(t_product(NewArgTypes))]),
+  ?debug("\n", []),
+
+  BifRet = BifRange(NewArgTypes),
+  ContrRet = CRange(NewArgTypes),
+  RetWithoutContr = t_inf(SigRange, BifRet),
+  RetWithoutLocal = t_inf(ContrRet, RetWithoutContr),
+
+  ?debug("RetWithoutContr: ~s\n",[erl_types:t_to_string(RetWithoutContr)]),
+  ?debug("RetWithoutLocal: ~s\n", [erl_types:t_to_string(RetWithoutLocal)]),
+  ?debug("BifRet: ~s\n", [erl_types:t_to_string(BifRange(NewArgTypes))]),
+  ?debug("SigRange: ~s\n", [erl_types:t_to_string(SigRange)]),
+  ?debug("ContrRet: ~s\n", [erl_types:t_to_string(ContrRet)]),
+  ?debug("LocalRet: ~s\n", [erl_types:t_to_string(LocalRet)]),
+
+  State1 =
+    case is_race_analysis_enabled(State) of
+      true ->
+        Ann = cerl:get_ann(Tree),
+        File = get_file(Ann),
+        Line = abs(get_line(Ann)),
+        dialyzer_races:store_race_call(Fun, ArgTypes, Args,
+                                       {File, Line}, State);
+      false -> State
+    end,
+  FailedConj = any_none([RetWithoutLocal|NewArgTypes]),
+  IsFailBif = t_is_none(BifRange(BifArgs)),
+  IsFailSig = t_is_none(SigRange),
+  ?debug("FailedConj: ~p~n", [FailedConj]),
+  ?debug("IsFailBif: ~p~n", [IsFailBif]),
+  ?debug("IsFailSig: ~p~n", [IsFailSig]),
+  State2 =
+    case FailedConj andalso not (IsFailBif orelse IsFailSig) of
+      true ->
+	case t_is_none(RetWithoutLocal) andalso
+	  not t_is_none(RetWithoutContr) andalso
+	  not any_none(NewArgTypes) of
+	  true ->
+	    {value, C1} = Contr,
+	    Contract = dialyzer_contracts:contract_to_string(C1),
+	    {M1, F1, A1} = state__lookup_name(Fun, State),
+	    ArgStrings = format_args(Args, ArgTypes, State),
+	    CRet = erl_types:t_to_string(RetWithoutContr),
+	    %% This Msg will be post_processed by dialyzer_succ_typings
+	    Msg =
+	      {contract_range, [Contract, M1, F1, A1, ArgStrings, CRet]},
+	    state__add_warning(State1, ?WARN_CONTRACT_RANGE, Tree, Msg);
+	  false ->
+	    FailedSig = any_none(NewArgsSig),
+	    FailedContract =
+	      any_none([CRange(NewArgsContract)|NewArgsContract]),
+	    FailedBif = any_none([BifRange(NewArgsBif)|NewArgsBif]),
+	    InfSig = t_inf(t_fun(SigArgs, SigRange),
+                           t_fun(BifArgs, BifRange(BifArgs))),
+	    FailReason =
+	      apply_fail_reason(FailedSig, FailedBif, FailedContract),
+	    Msg = get_apply_fail_msg(Fun, Args, ArgTypes, NewArgTypes, InfSig,
+				     Contr, CArgs, State1, FailReason, Opaques),
+	    WarnType = case Msg of
+			 {call, _} -> ?WARN_FAILING_CALL;
+			 {apply, _} -> ?WARN_FAILING_CALL;
+			 {call_with_opaque, _} -> ?WARN_OPAQUE;
+			 {call_without_opaque, _} -> ?WARN_OPAQUE;
+			 {opaque_type_test, _} -> ?WARN_OPAQUE
+		       end,
+            Frc = {erlang, is_record, 3} =:= state__lookup_name(Fun, State),
+	    state__add_warning(State1, WarnType, Tree, Msg, Frc)
+	end;
+      false -> State1
+    end,
+  State3 =
+    case TypeOfApply of
+      local ->
+        case state__is_escaping(Fun, State2) of
+          true -> State2;
+          false ->
+            ForwardArgs = [t_limit(X, ?TYPE_LIMIT) || X <- ArgTypes],
+            forward_args(Fun, ForwardArgs, State2)
+        end;
+      remote ->
+        add_bif_warnings(Fun, NewArgTypes, Tree, State2)
+    end,
+  NewAccArgTypes =
+    case FailedConj of
+      true -> AccArgTypes;
+      false -> [t_sup(X, Y) || {X, Y} <- lists:zip(NewArgTypes, AccArgTypes)]
+    end,
+  TotalRet =
+    case t_is_none(LocalRet) andalso t_is_unit(RetWithoutLocal) of
+      true -> RetWithoutLocal;
+      false -> t_inf(RetWithoutLocal, LocalRet)
+    end,
+  NewAccRet = t_sup(AccRet, TotalRet),
+  ?debug("NewAccRet: ~s\n", [t_to_string(NewAccRet)]),
+  {NewWarnings, State4} = state__remove_added_warnings(State, State3),
+  {HowMany, OldWarnings} = Warns,
+  NewWarns =
+    case HowMany of
+      none -> {one, NewWarnings};
+      _ ->
+        case OldWarnings =:= [] of
+          true -> {many, []};
+          false ->
+            case NewWarnings =:= [] of
+              true -> {many, []};
+              false -> {many, NewWarnings ++ OldWarnings}
+            end
+        end
+    end,
+  handle_apply_or_call(Left, Args, ArgTypes, Map, Tree,
+		       State4, NewAccArgTypes, NewAccRet, HadExternal, NewWarns);
+handle_apply_or_call([], Args, _ArgTypes, Map, _Tree, State,
+		     AccArgTypes, AccRet, HadExternal, {_, Warnings}) ->
+  State1 = state__add_warnings(Warnings, State),
+  case HadExternal of
+    false ->
+      NewMap = enter_type_lists(Args, AccArgTypes, Map),
+      {State1, NewMap, AccRet};
+    true ->
+      {had_external, State1}
+  end.
+
+apply_fail_reason(FailedSig, FailedBif, FailedContract) ->
+  if
+    (FailedSig orelse FailedBif) andalso (not FailedContract) -> only_sig;
+    FailedContract andalso (not (FailedSig orelse FailedBif)) -> only_contract;
+    true                                                      -> both
+  end.
+
+get_apply_fail_msg(Fun, Args, ArgTypes, NewArgTypes,
+		   Sig, Contract, ContrArgs, State, FailReason, Opaques) ->
+  ArgStrings = format_args(Args, ArgTypes, State),
+  ContractInfo =
+    case Contract of
+      {value, #contract{} = C} ->
+	{dialyzer_contracts:is_overloaded(C),
+	 dialyzer_contracts:contract_to_string(C)};
+      none -> {false, none}
+    end,
+  EnumArgTypes = lists:zip(lists:seq(1, length(NewArgTypes)), NewArgTypes),
+  ArgNs = [Arg || {Arg, Type} <- EnumArgTypes, t_is_none(Type)],
+  case state__lookup_name(Fun, State) of
+    {M, F, A} ->
+      case is_opaque_type_test_problem(Fun, Args, NewArgTypes, State) of
+	{yes, Arg, ArgType} ->
+	  {opaque_type_test, [atom_to_list(F), ArgStrings,
+                              format_arg(Arg), format_type(ArgType, State)]};
+	no ->
+	  SigArgs = t_fun_args(Sig),
+          BadOpaque =
+            opaque_problems([SigArgs, ContrArgs], ArgTypes, Opaques, ArgNs),
+          %% In fact *both* 'call_with_opaque' and
+          %% 'call_without_opaque' are possible.
+          case lists:keyfind(decl, 1, BadOpaque) of
+            {decl, BadArgs} ->
+              %% a structured term is used where an opaque is expected
+              ExpectedTriples =
+                case FailReason of
+                  only_sig -> expected_arg_triples(BadArgs, SigArgs, State);
+                  _ -> expected_arg_triples(BadArgs, ContrArgs, State)
+                end,
+              {call_without_opaque, [M, F, ArgStrings, ExpectedTriples]};
+            false ->
+              case lists:keyfind(use, 1, BadOpaque) of
+                {use, BadArgs} ->
+                  %% an opaque term is used where a structured term is expected
+                  ExpectedArgs =
+                    case FailReason of
+                      only_sig -> SigArgs;
+                      _ -> ContrArgs
+                    end,
+                  {call_with_opaque, [M, F, ArgStrings, BadArgs, ExpectedArgs]};
+                false ->
+                  case
+                    erl_bif_types:opaque_args(M, F, A, ArgTypes, Opaques)
+                  of
+                    [] ->  %% there is a structured term clash in some argument
+                      {call, [M, F, ArgStrings,
+                              ArgNs, FailReason,
+                              format_sig_args(Sig, State),
+                              format_type(t_fun_range(Sig), State),
+                              ContractInfo]};
+                    Ns ->
+                      {call_with_opaque, [M, F, ArgStrings, Ns, ContrArgs]}
+                  end
+	      end
+	  end
+      end;
+    Label when is_integer(Label) ->
+      {apply, [ArgStrings,
+	       ArgNs, FailReason,
+	       format_sig_args(Sig, State),
+	       format_type(t_fun_range(Sig), State),
+	       ContractInfo]}
+  end.
+
+%% -> [{ElementI, [ArgN]}] where [ArgN] is a non-empty list of
+%% arguments containing unknown opaque types and Element is 1 or 2.
+opaque_problems(ContractOrSigList, ArgTypes, Opaques, ArgNs) ->
+  ArgElementList = find_unknown(ContractOrSigList, ArgTypes, Opaques, ArgNs),
+  F = fun(1) -> decl; (2) -> use end,
+  [{F(ElementI), lists:usort([ArgN || {ArgN, EI} <- ArgElementList,
+                                      EI =:= ElementI])} ||
+    ElementI <- lists:usort([EI || {_, EI} <- ArgElementList])].
+
+%% -> [{ArgN, ElementI}] where ElementI = 1 means there is an unknown
+%% opaque type in argument ArgN of the the contract/signature,
+%% and ElementI = 2 means that there is an unknown opaque type in
+%% argument ArgN of the the (current) argument types.
+find_unknown(ContractOrSigList, ArgTypes, Opaques, NoneArgNs) ->
+  ArgNs = lists:seq(1, length(ArgTypes)),
+  [{ArgN, ElementI} ||
+    ContractOrSig <- ContractOrSigList,
+    {E1, E2, ArgN} <- lists:zip3(ContractOrSig, ArgTypes, ArgNs),
+    lists:member(ArgN, NoneArgNs),
+    ElementI <- erl_types:t_find_unknown_opaque(E1, E2, Opaques)].
+
+is_opaque_type_test_problem(Fun, Args, ArgTypes, State) ->
+  case Fun of
+    {erlang, FN, 1} when FN =:= is_atom;      FN =:= is_boolean;
+			 FN =:= is_binary;    FN =:= is_bitstring;
+			 FN =:= is_float;     FN =:= is_function;
+			 FN =:= is_integer;   FN =:= is_list;
+			 FN =:= is_number;    FN =:= is_pid; FN =:= is_port;
+			 FN =:= is_reference; FN =:= is_tuple;
+			 FN =:= is_map ->
+      type_test_opaque_arg(Args, ArgTypes, State#state.opaques);
+    {erlang, FN, 2} when FN =:= is_function ->
+      type_test_opaque_arg(Args, ArgTypes, State#state.opaques);
+    _ -> no
+  end.
+
+type_test_opaque_arg([], [], _Opaques) ->
+  no;
+type_test_opaque_arg([Arg|Args], [ArgType|ArgTypes], Opaques) ->
+  case erl_types:t_has_opaque_subtype(ArgType, Opaques) of
+    true -> {yes, Arg, ArgType};
+    false -> type_test_opaque_arg(Args, ArgTypes, Opaques)
+  end.
+
+expected_arg_triples(ArgNs, ArgTypes, State) ->
+  [begin
+     Arg = lists:nth(N, ArgTypes),
+     {N, Arg, format_type(Arg, State)}
+   end || N <- ArgNs].
+
+add_bif_warnings({erlang, Op, 2}, [T1, T2] = Ts, Tree, State)
+  when Op =:= '=:='; Op =:= '==' ->
+  Opaques = State#state.opaques,
+  Inf = t_inf(T1, T2, Opaques),
+  case
+    t_is_none(Inf) andalso (not any_none(Ts))
+    andalso (not is_int_float_eq_comp(T1, Op, T2, Opaques))
+  of
+    true ->
+      %% Give priority to opaque warning (as usual).
+      case erl_types:t_find_unknown_opaque(T1, T2, Opaques) of
+        [] ->
+          Args = comp_format_args([], T1, Op, T2, State),
+          state__add_warning(State, ?WARN_MATCHING, Tree, {exact_eq, Args});
+        Ns ->
+          Args = comp_format_args(Ns, T1, Op, T2, State),
+	  state__add_warning(State, ?WARN_OPAQUE, Tree, {opaque_eq, Args})
+      end;
+    false ->
+      State
+  end;
+add_bif_warnings({erlang, Op, 2}, [T1, T2] = Ts, Tree, State)
+  when Op =:= '=/='; Op =:= '/=' ->
+  Opaques = State#state.opaques,
+  case
+    (not any_none(Ts))
+    andalso (not is_int_float_eq_comp(T1, Op, T2, Opaques))
+  of
+    true ->
+      case erl_types:t_find_unknown_opaque(T1, T2, Opaques) of
+        [] -> State;
+        Ns ->
+          Args = comp_format_args(Ns, T1, Op, T2, State),
+	  state__add_warning(State, ?WARN_OPAQUE, Tree, {opaque_neq, Args})
+      end;
+    false ->
+      State
+  end;
+add_bif_warnings(_, _, _, State) ->
+  State.
+
+is_int_float_eq_comp(T1, Op, T2, Opaques) ->
+  (Op =:= '==' orelse Op =:= '/=') andalso
+    ((erl_types:t_is_float(T1, Opaques)
+      andalso t_is_integer(T2, Opaques)) orelse
+     (t_is_integer(T1, Opaques)
+      andalso erl_types:t_is_float(T2, Opaques))).
+
+comp_format_args([1|_], T1, Op, T2, State) ->
+  [format_type(T2, State), Op, format_type(T1, State)];
+comp_format_args(_, T1, Op, T2, State) ->
+  [format_type(T1, State), Op, format_type(T2, State)].
+
+%%----------------------------------------
+
+handle_bitstr(Tree, Map, State) ->
+  %% Construction of binaries.
+  Size = cerl:bitstr_size(Tree),
+  Val = cerl:bitstr_val(Tree),
+  BitstrType = cerl:concrete(cerl:bitstr_type(Tree)),
+  {State1, Map1, SizeType0} = traverse(Size, Map, State),
+  {State2, Map2, ValType0} = traverse(Val, Map1, State1),
+  case cerl:bitstr_bitsize(Tree) of
+    BitSz when BitSz =:= all orelse BitSz =:= utf ->
+      ValType =
+	case BitSz of
+	  all ->
+	    true = (BitstrType =:= binary),
+	    t_inf(ValType0, t_bitstr());
+	  utf ->
+	    true = lists:member(BitstrType, [utf8, utf16, utf32]),
+	    t_inf(ValType0, t_integer())
+	end,
+      Map3 = enter_type(Val, ValType, Map2),
+      case t_is_none(ValType) of
+	true ->
+	  Msg = {bin_construction, ["value",
+				    format_cerl(Val), format_cerl(Tree),
+				    format_type(ValType0, State2)]},
+	  State3 = state__add_warning(State2, ?WARN_BIN_CONSTRUCTION, Val, Msg),
+	  {State3, Map3, t_none()};
+	false ->
+	  {State2, Map3, t_bitstr()}
+      end;
+    BitSz when is_integer(BitSz) orelse BitSz =:= any ->
+      SizeType = t_inf(SizeType0, t_non_neg_integer()),
+      ValType =
+	case BitstrType of
+	  binary -> t_inf(ValType0, t_bitstr());
+	  float -> t_inf(ValType0, t_number());
+	  integer -> t_inf(ValType0, t_integer())
+	end,
+      case any_none([SizeType, ValType]) of
+	true ->
+	  {Msg, Offending} =
+	    case t_is_none(SizeType) of
+	      true ->
+		{{bin_construction,
+		  ["size", format_cerl(Size), format_cerl(Tree),
+		   format_type(SizeType0, State2)]},
+		 Size};
+	      false ->
+		{{bin_construction,
+		  ["value", format_cerl(Val), format_cerl(Tree),
+		   format_type(ValType0, State2)]},
+		 Val}
+	    end,
+	  State3 = state__add_warning(State2, ?WARN_BIN_CONSTRUCTION,
+				      Offending, Msg),
+	  {State3, Map2, t_none()};
+	false ->
+	  UnitVal = cerl:concrete(cerl:bitstr_unit(Tree)),
+          Opaques = State2#state.opaques,
+          NumberVals = t_number_vals(SizeType, Opaques),
+          {State3, Type} =
+            case t_contains_opaque(SizeType, Opaques) of
+              true ->
+                Msg = {opaque_size, [format_type(SizeType, State2),
+                                     format_cerl(Size)]},
+                {state__add_warning(State2, ?WARN_OPAQUE, Size, Msg),
+                 t_none()};
+              false ->
+                case NumberVals of
+                  [OneSize] -> {State2, t_bitstr(0, OneSize * UnitVal)};
+                  unknown -> {State2, t_bitstr()};
+                  _ ->
+                    MinSize = erl_types:number_min(SizeType, Opaques),
+                    {State2, t_bitstr(UnitVal, UnitVal * MinSize)}
+                end
+            end,
+	  Map3 = enter_type_lists([Val, Size, Tree],
+				  [ValType, SizeType, Type], Map2),
+	  {State3, Map3, Type}
+      end
+  end.
+
+%%----------------------------------------
+
+handle_call(Tree, Map, State) ->
+  M = cerl:call_module(Tree),
+  F = cerl:call_name(Tree),
+  Args = cerl:call_args(Tree),
+  MFAList = [M, F|Args],
+  {State1, Map1, [MType0, FType0|As]} = traverse_list(MFAList, Map, State),
+  Opaques = State#state.opaques,
+  MType = t_inf(t_module(), MType0, Opaques),
+  FType = t_inf(t_atom(), FType0, Opaques),
+  Map2 = enter_type_lists([M, F], [MType, FType], Map1),
+  MOpaque = t_is_none(MType) andalso (not t_is_none(MType0)),
+  FOpaque = t_is_none(FType) andalso (not t_is_none(FType0)),
+  case any_none([MType, FType|As]) of
+    true ->
+      State2 =
+        if
+          MOpaque -> % This is a problem we just detected; not a known one
+            MS = format_cerl(M),
+            case t_is_none(t_inf(t_module(), MType0)) of
+              true ->
+                Msg = {app_call, [MS, format_cerl(F),
+                                  format_args(Args, As, State1),
+                                  MS, format_type(t_module(), State1),
+                                  format_type(MType0, State1)]},
+                state__add_warning(State1, ?WARN_FAILING_CALL, Tree, Msg);
+              false ->
+                Msg = {opaque_call, [MS, format_cerl(F),
+                                     format_args(Args, As, State1),
+                                     MS, format_type(MType0, State1)]},
+                state__add_warning(State1, ?WARN_FAILING_CALL, Tree, Msg)
+            end;
+          FOpaque ->
+            FS = format_cerl(F),
+            case t_is_none(t_inf(t_atom(), FType0)) of
+              true ->
+                Msg = {app_call, [format_cerl(M), FS,
+                                  format_args(Args, As, State1),
+                                  FS, format_type(t_atom(), State1),
+                                  format_type(FType0, State1)]},
+                state__add_warning(State1, ?WARN_FAILING_CALL, Tree, Msg);
+              false ->
+                Msg = {opaque_call, [format_cerl(M), FS,
+                                     format_args(Args, As, State1),
+                                     FS, format_type(FType0, State1)]},
+                state__add_warning(State1, ?WARN_FAILING_CALL, Tree, Msg)
+            end;
+          true -> State1
+	end,
+      {State2, Map2, t_none()};
+    false ->
+      case t_is_atom(MType) of
+	true ->
+	  %% XXX: Consider doing this for all combinations of MF
+	  case {t_atom_vals(MType), t_atom_vals(FType)} of
+	    {[MAtom], [FAtom]} ->
+	      FunInfo = [{remote, state__fun_info({MAtom, FAtom, length(Args)},
+						  State1)}],
+	      handle_apply_or_call(FunInfo, Args, As, Map2, Tree, State1);
+	    {_MAtoms, _FAtoms} ->
+	      {State1, Map2, t_any()}
+	  end;
+	false ->
+	  {State1, Map2, t_any()}
+      end
+  end.
+
+%%----------------------------------------
+
+handle_case(Tree, Map, State) ->
+  Arg = cerl:case_arg(Tree),
+  Clauses = filter_match_fail(cerl:case_clauses(Tree)),
+  {State1, Map1, ArgType} = SMA = traverse(Arg, Map, State),
+  case t_is_none_or_unit(ArgType) of
+    true -> SMA;
+    false ->
+      State2 =
+        case is_race_analysis_enabled(State) of
+          true ->
+	    {RaceList, RaceListSize} = get_race_list_and_size(State1),
+            state__renew_race_list([beg_case|RaceList],
+                                   RaceListSize + 1, State1);
+          false -> State1
+        end,
+      Map2 = join_maps_begin(Map1),
+      {MapList, State3, Type} =
+	handle_clauses(Clauses, Arg, ArgType, ArgType, State2,
+		       [], Map2, [], []),
+      Map3 = join_maps_end(MapList, Map2),
+      debug_pp_map(Map3),
+      {State3, Map3, Type}
+  end.
+
+%%----------------------------------------
+
+handle_cons(Tree, Map, State) ->
+  Hd = cerl:cons_hd(Tree),
+  Tl = cerl:cons_tl(Tree),
+  {State1, Map1, HdType} = traverse(Hd, Map, State),
+  {State2, Map2, TlType} = traverse(Tl, Map1, State1),
+  State3 =
+    case t_is_none(t_inf(TlType, t_list(), State2#state.opaques)) of
+      true ->
+	Msg = {improper_list_constr, [format_type(TlType, State2)]},
+	state__add_warning(State2, ?WARN_NON_PROPER_LIST, Tree, Msg);
+      false ->
+	State2
+    end,
+  Type = t_cons(HdType, TlType),
+  {State3, Map2, Type}.
+
+%%----------------------------------------
+
+handle_let(Tree, Map, State) ->
+  IsRaceAnalysisEnabled = is_race_analysis_enabled(State),
+  Arg = cerl:let_arg(Tree),
+  Vars = cerl:let_vars(Tree),
+  {Map0, State0} =
+    case cerl:is_c_var(Arg) of
+      true ->
+	[Var] = Vars,
+	{enter_subst(Var, Arg, Map),
+         case IsRaceAnalysisEnabled of
+           true ->
+	    {RaceList, RaceListSize} = get_race_list_and_size(State),
+             state__renew_race_list(
+               [dialyzer_races:let_tag_new(Var, Arg)|RaceList],
+               RaceListSize + 1, State);
+           false -> State
+         end};
+      false -> {Map, State}
+    end,
+  Body = cerl:let_body(Tree),
+  {State1, Map1, ArgTypes} = SMA = traverse(Arg, Map0, State0),
+  State2 =
+    case IsRaceAnalysisEnabled andalso cerl:is_c_call(Arg) of
+      true ->
+        Mod = cerl:call_module(Arg),
+        Name = cerl:call_name(Arg),
+        case cerl:is_literal(Mod) andalso
+             cerl:concrete(Mod) =:= ets andalso
+             cerl:is_literal(Name) andalso
+             cerl:concrete(Name) =:= new of
+          true -> renew_race_public_tables(Vars, State1);
+          false -> State1
+        end;
+      false -> State1
+    end,
+  case t_is_none_or_unit(ArgTypes) of
+    true -> SMA;
+    false ->
+      Map2 = enter_type_lists(Vars, t_to_tlist(ArgTypes), Map1),
+      traverse(Body, Map2, State2)
+  end.
+
+%%----------------------------------------
+
+handle_module(Tree, Map, State) ->
+  %% By not including the variables in scope we can assure that we
+  %% will get the current function type when using the variables.
+  Defs = cerl:module_defs(Tree),
+  PartFun = fun({_Var, Fun}) ->
+		state__is_escaping(get_label(Fun), State)
+	    end,
+  {Defs1, Defs2} = lists:partition(PartFun, Defs),
+  Letrec = cerl:c_letrec(Defs1, cerl:c_int(42)),
+  {State1, Map1, _FunTypes} = traverse(Letrec, Map, State),
+  %% Also add environments for the other top-level functions.
+  VarTypes = [{Var, state__fun_type(Fun, State1)} || {Var, Fun} <- Defs],
+  EnvMap = enter_type_list(VarTypes, Map),
+  FoldFun = fun({_Var, Fun}, AccState) ->
+		state__update_fun_env(Fun, EnvMap, AccState)
+	    end,
+  State2 = lists:foldl(FoldFun, State1, Defs2),
+  {State2, Map1, t_any()}.
+
+%%----------------------------------------
+
+handle_receive(Tree, Map, State) ->
+  Clauses = filter_match_fail(cerl:receive_clauses(Tree)),
+  Timeout = cerl:receive_timeout(Tree),
+  State1 =
+    case is_race_analysis_enabled(State) of
+      true ->
+	{RaceList, RaceListSize} = get_race_list_and_size(State),
+        state__renew_race_list([beg_case|RaceList],
+                               RaceListSize + 1, State);
+      false -> State
+    end,
+  {MapList, State2, ReceiveType} =
+    handle_clauses(Clauses, ?no_arg, t_any(), t_any(), State1, [], Map,
+                   [], []),
+  Map1 = join_maps(MapList, Map),
+  {State3, Map2, TimeoutType} = traverse(Timeout, Map1, State2),
+  Opaques = State3#state.opaques,
+  case (t_is_atom(TimeoutType, Opaques) andalso
+	(t_atom_vals(TimeoutType, Opaques) =:= ['infinity'])) of
+    true ->
+      {State3, Map2, ReceiveType};
+    false ->
+      Action = cerl:receive_action(Tree),
+      {State4, Map3, ActionType} = traverse(Action, Map, State3),
+      Map4 = join_maps([Map3, Map1], Map),
+      Type = t_sup(ReceiveType, ActionType),
+      {State4, Map4, Type}
+  end.
+
+%%----------------------------------------
+
+handle_try(Tree, Map, State) ->
+  Arg = cerl:try_arg(Tree),
+  EVars = cerl:try_evars(Tree),
+  Vars = cerl:try_vars(Tree),
+  Body = cerl:try_body(Tree),
+  Handler = cerl:try_handler(Tree),
+  {State1, Map1, ArgType} = traverse(Arg, Map, State),
+  Map2 = mark_as_fresh(Vars, Map1),
+  {SuccState, SuccMap, SuccType} =
+    case bind_pat_vars(Vars, t_to_tlist(ArgType), [], Map2, State1) of
+      {error, _, _, _, _} ->
+	{State1, map__new(), t_none()};
+      {SuccMap1, VarTypes} ->
+	%% Try to bind the argument. Will only succeed if
+	%% it is a simple structured term.
+	SuccMap2 =
+	  case bind_pat_vars_reverse([Arg], [t_product(VarTypes)], [],
+				     SuccMap1, State1) of
+	    {error, _, _, _, _} -> SuccMap1;
+	    {SM, _} -> SM
+	  end,
+	traverse(Body, SuccMap2, State1)
+    end,
+  ExcMap1 = mark_as_fresh(EVars, Map),
+  {State2, ExcMap2, HandlerType} = traverse(Handler, ExcMap1, SuccState),
+  TryType = t_sup(SuccType, HandlerType),
+  {State2, join_maps([ExcMap2, SuccMap], Map1), TryType}.
+
+%%----------------------------------------
+
+handle_map(Tree,Map,State) ->
+  Pairs = cerl:map_es(Tree),
+  Arg = cerl:map_arg(Tree),
+  {State1, Map1, ArgType} = traverse(Arg, Map, State),
+  ArgType1 = t_inf(t_map(), ArgType),
+  case t_is_none_or_unit(ArgType1) of
+    true ->
+      {State1, Map1, ArgType1};
+    false ->
+      {State2, Map2, TypePairs, ExactKeys} =
+	traverse_map_pairs(Pairs, Map1, State1, t_none(), [], []),
+      InsertPair = fun({KV,assoc,_},Acc) -> erl_types:t_map_put(KV,Acc);
+		      ({KV,exact,KVTree},Acc) ->
+		       case t_is_none(T=erl_types:t_map_update(KV,Acc)) of
+			 true -> throw({none, Acc, KV, KVTree});
+			 false -> T
+		       end
+		   end,
+      try lists:foldl(InsertPair, ArgType1, TypePairs)
+      of ResT ->
+	  BindT = t_map([{K, t_any()} || K <- ExactKeys]),
+	  case bind_pat_vars_reverse([Arg], [BindT], [], Map2, State2) of
+	    {error, _, _, _, _} -> {State2, Map2, ResT};
+	    {Map3, _} ->           {State2, Map3, ResT}
+	  end
+      catch {none, MapType, {K,_}, KVTree} ->
+	  Msg2 = {map_update, [format_type(MapType, State2),
+			       format_type(K, State2)]},
+	  {state__add_warning(State2, ?WARN_MAP_CONSTRUCTION, KVTree, Msg2),
+	   Map2, t_none()}
+      end
+  end.
+
+traverse_map_pairs([], Map, State, _ShadowKeys, PairAcc, KeyAcc) ->
+  {State, Map, lists:reverse(PairAcc), KeyAcc};
+traverse_map_pairs([Pair|Pairs], Map, State, ShadowKeys, PairAcc, KeyAcc) ->
+  Key = cerl:map_pair_key(Pair),
+  Val = cerl:map_pair_val(Pair),
+  Op = cerl:map_pair_op(Pair),
+  {State1, Map1, [K,V]} = traverse_list([Key,Val],Map,State),
+  KeyAcc1 =
+    case cerl:is_literal(Op) andalso cerl:concrete(Op) =:= exact andalso
+      t_is_singleton(K, State#state.opaques) andalso
+      t_is_none(t_inf(ShadowKeys, K)) of
+      true -> [K|KeyAcc];
+      false -> KeyAcc
+  end,
+  traverse_map_pairs(Pairs, Map1, State1, t_sup(K, ShadowKeys),
+		     [{{K,V},cerl:concrete(Op),Pair}|PairAcc], KeyAcc1).
+
+%%----------------------------------------
+
+handle_tuple(Tree, Map, State) ->
+  Elements = cerl:tuple_es(Tree),
+  {State1, Map1, EsType} = traverse_list(Elements, Map, State),
+  TupleType = t_tuple(EsType),
+  case t_is_none(TupleType) of
+    true ->
+      {State1, Map1, t_none()};
+    false ->
+      %% Let's find out if this is a record
+      case Elements of
+	[Tag|Left] ->
+	  case cerl:is_c_atom(Tag) andalso is_literal_record(Tree) of
+	    true ->
+	      TagVal = cerl:atom_val(Tag),
+              case state__lookup_record(TagVal, length(Left), State1) of
+                error -> {State1, Map1, TupleType};
+                {ok, RecType} ->
+                  InfTupleType = t_inf(RecType, TupleType),
+                  case t_is_none(InfTupleType) of
+                    true ->
+                      RecC = format_type(TupleType, State1),
+                      FieldDiffs = format_field_diffs(TupleType, State1),
+                      Msg = {record_constr, [RecC, FieldDiffs]},
+                      State2 = state__add_warning(State1, ?WARN_MATCHING,
+                                                  Tree, Msg),
+                      {State2, Map1, t_none()};
+                    false ->
+                      case bind_pat_vars(Elements, t_tuple_args(RecType),
+                                         [], Map1, State1) of
+                        {error, bind, ErrorPat, ErrorType, _} ->
+                          Msg = {record_constr,
+                                 [TagVal, format_patterns(ErrorPat),
+                                  format_type(ErrorType, State1)]},
+                          State2 = state__add_warning(State1, ?WARN_MATCHING,
+                                                      Tree, Msg),
+                          {State2, Map1, t_none()};
+                        {error, opaque, ErrorPat, ErrorType, OpaqueType} ->
+                          Msg = {opaque_match,
+                                 [format_patterns(ErrorPat),
+                                  format_type(ErrorType, State1),
+                                  format_type(OpaqueType, State1)]},
+                          State2 = state__add_warning(State1, ?WARN_OPAQUE,
+                                                      Tree, Msg),
+                          {State2, Map1, t_none()};
+                        {Map2, ETypes} ->
+                          {State1, Map2, t_tuple(ETypes)}
+                      end
+                  end
+	      end;
+	    false ->
+	      {State1, Map1, t_tuple(EsType)}
+	  end;
+	[] ->
+	  {State1, Map1, t_tuple([])}
+      end
+  end.
+
+%%----------------------------------------
+%% Clauses
+%%
+handle_clauses([C|Left], Arg, ArgType, OrigArgType, State, CaseTypes, MapIn,
+	       Acc, ClauseAcc) ->
+  IsRaceAnalysisEnabled = is_race_analysis_enabled(State),
+  State1 =
+    case IsRaceAnalysisEnabled of
+      true ->
+	{RaceList, RaceListSize} = get_race_list_and_size(State),
+        state__renew_race_list(
+          [dialyzer_races:beg_clause_new(Arg, cerl:clause_pats(C),
+                                         cerl:clause_guard(C))|
+           RaceList], RaceListSize + 1,
+          State);
+      false -> State
+    end,
+  {State2, ClauseMap, BodyType, NewArgType} =
+    do_clause(C, Arg, ArgType, OrigArgType, MapIn, State1),
+  {NewClauseAcc, State3} =
+    case IsRaceAnalysisEnabled of
+      true ->
+	{RaceList1, RaceListSize1} = get_race_list_and_size(State2),
+        EndClause = dialyzer_races:end_clause_new(Arg, cerl:clause_pats(C),
+                                                  cerl:clause_guard(C)),
+        {[EndClause|ClauseAcc],
+         state__renew_race_list([EndClause|RaceList1],
+                                RaceListSize1 + 1, State2)};
+      false -> {ClauseAcc, State2}
+    end,
+  {NewCaseTypes, NewAcc} =
+    case t_is_none(BodyType) of
+      true -> {CaseTypes, Acc};
+      false -> {[BodyType|CaseTypes], [ClauseMap|Acc]}
+    end,
+  handle_clauses(Left, Arg, NewArgType, OrigArgType, State3,
+                 NewCaseTypes, MapIn, NewAcc, NewClauseAcc);
+handle_clauses([], _Arg, _ArgType, _OrigArgType, State, CaseTypes, _MapIn, Acc,
+	       ClauseAcc) ->
+  State1 =
+    case is_race_analysis_enabled(State) of
+      true ->
+	{RaceList, RaceListSize} = get_race_list_and_size(State),
+        state__renew_race_list(
+          [dialyzer_races:end_case_new(ClauseAcc)|RaceList],
+	  RaceListSize + 1, State);
+      false -> State
+    end,
+  {lists:reverse(Acc), State1, t_sup(CaseTypes)}.
+
+do_clause(C, Arg, ArgType0, OrigArgType, Map, State) ->
+  Pats = cerl:clause_pats(C),
+  Guard = cerl:clause_guard(C),
+  Body = cerl:clause_body(C),
+  State1 =
+    case is_race_analysis_enabled(State) of
+      true ->
+        state__renew_fun_args(Pats, State);
+      false -> State
+    end,
+  Map0 = mark_as_fresh(Pats, Map),
+  Map1 = if Arg =:= ?no_arg -> Map0;
+	    true -> bind_subst(Arg, Pats, Map0)
+	 end,
+  BindRes =
+    case t_is_none(ArgType0) of
+      true ->
+	{error, bind, Pats, ArgType0, ArgType0};
+      false ->
+	ArgTypes =
+	  case t_is_any(ArgType0) of
+	    true -> [ArgType0 || _ <- Pats];
+	    false -> t_to_tlist(ArgType0)
+	  end,
+	bind_pat_vars(Pats, ArgTypes, [], Map1, State1)
+    end,
+  case BindRes of
+    {error, ErrorType, NewPats, Type, OpaqueTerm} ->
+      ?debug("Failed binding pattern: ~s\nto ~s\n",
+	     [cerl_prettypr:format(C), format_type(ArgType0, State1)]),
+      case state__warning_mode(State1) of
+        false ->
+          {State1, Map, t_none(), ArgType0};
+	true ->
+	  {Msg, Force} =
+	    case t_is_none(ArgType0) of
+	      true ->
+                PatString = format_patterns(Pats),
+		PatTypes = [PatString, format_type(OrigArgType, State1)],
+		%% See if this is covered by an earlier clause or if it
+		%% simply cannot match
+		OrigArgTypes =
+		  case t_is_any(OrigArgType) of
+		    true -> Any = t_any(), [Any || _ <- Pats];
+		    false -> t_to_tlist(OrigArgType)
+		  end,
+		Tag =
+		  case bind_pat_vars(Pats, OrigArgTypes, [], Map1, State1) of
+		    {error,   bind, _, _, _} -> pattern_match;
+		    {error, record, _, _, _} -> record_match;
+		    {error, opaque, _, _, _} -> opaque_match;
+		    {_, _} -> pattern_match_cov
+		  end,
+		{{Tag, PatTypes}, false};
+	      false ->
+		%% Try to find out if this is a default clause in a list
+		%% comprehension and supress this. A real Hack(tm)
+		Force0 =
+		  case is_compiler_generated(cerl:get_ann(C)) of
+		    true ->
+		      case Pats of
+			[Pat] ->
+			  case cerl:is_c_cons(Pat) of
+			    true ->
+			      not (cerl:is_c_var(cerl:cons_hd(Pat)) andalso
+				   cerl:is_c_var(cerl:cons_tl(Pat)) andalso
+				   cerl:is_literal(Guard) andalso
+				   (cerl:concrete(Guard) =:= true));
+			    false ->
+			      true
+			  end;
+			[Pat0, Pat1] -> % binary comprehension
+			  case cerl:is_c_cons(Pat0) of
+			    true ->
+			      not (cerl:is_c_var(cerl:cons_hd(Pat0)) andalso
+				   cerl:is_c_var(cerl:cons_tl(Pat0)) andalso
+                                   cerl:is_c_var(Pat1) andalso
+				   cerl:is_literal(Guard) andalso
+				   (cerl:concrete(Guard) =:= true));
+			    false ->
+			      true
+			  end;
+			_ -> true
+		      end;
+		    false ->
+		      true
+		  end,
+                PatString =
+                  case ErrorType of
+                    bind   -> format_patterns(Pats);
+                    record -> format_patterns(NewPats);
+                    opaque -> format_patterns(NewPats)
+                  end,
+		PatTypes = case ErrorType of
+			     bind -> [PatString, format_type(ArgType0, State1)];
+			     record -> [PatString, format_type(Type, State1)];
+			     opaque -> [PatString, format_type(Type, State1),
+					format_type(OpaqueTerm, State1)]
+			   end,
+		FailedTag = case ErrorType of
+			      bind  -> pattern_match;
+			      record -> record_match;
+			      opaque -> opaque_match
+			    end,
+		{{FailedTag, PatTypes}, Force0}
+	    end,
+	  WarnType = case Msg of
+		       {opaque_match, _} -> ?WARN_OPAQUE;
+		       {pattern_match, _} -> ?WARN_MATCHING;
+		       {record_match, _} -> ?WARN_MATCHING;
+		       {pattern_match_cov, _} -> ?WARN_MATCHING
+		     end,
+          {state__add_warning(State1, WarnType, C, Msg, Force),
+           Map, t_none(), ArgType0}
+      end;
+    {Map2, PatTypes} ->
+      Map3 =
+	case Arg =:= ?no_arg of
+	  true -> Map2;
+	  false ->
+	    %% Try to bind the argument. Will only succeed if
+	    %% it is a simple structured term.
+	    case bind_pat_vars_reverse([Arg], [t_product(PatTypes)],
+				       [], Map2, State1) of
+	      {error, _, _, _, _} -> Map2;
+	      {NewMap, _} -> NewMap
+	    end
+	end,
+      NewArgType =
+	case Arg =:= ?no_arg of
+	  true -> ArgType0;
+	  false ->
+	    GenType = dialyzer_typesig:get_safe_underapprox(Pats, Guard),
+	    t_subtract(t_product(t_to_tlist(ArgType0)), GenType)
+	end,
+      case bind_guard(Guard, Map3, State1) of
+	{error, Reason} ->
+	  ?debug("Failed guard: ~s\n",
+		 [cerl_prettypr:format(C, [{hook, cerl_typean:pp_hook()}])]),
+	  PatString = format_patterns(Pats),
+	  DefaultMsg =
+	    case Pats =:= [] of
+	      true -> {guard_fail, []};
+	      false ->
+		{guard_fail_pat, [PatString, format_type(ArgType0, State1)]}
+	    end,
+	  State2 =
+	    case Reason of
+	      none -> state__add_warning(State1, ?WARN_MATCHING, C, DefaultMsg);
+	      {FailGuard, Msg} ->
+		case is_compiler_generated(cerl:get_ann(FailGuard)) of
+		  false ->
+		    WarnType = case Msg of
+				 {guard_fail, _} -> ?WARN_MATCHING;
+				 {neg_guard_fail, _} -> ?WARN_MATCHING;
+				 {opaque_guard, _} -> ?WARN_OPAQUE
+			       end,
+		    state__add_warning(State1, WarnType, FailGuard, Msg);
+		  true ->
+		    state__add_warning(State1, ?WARN_MATCHING, C, Msg)
+		end
+	    end,
+          {State2, Map, t_none(), NewArgType};
+        Map4 ->
+          {RetState, RetMap, BodyType} = traverse(Body, Map4, State1),
+          {RetState, RetMap, BodyType, NewArgType}
+      end
+  end.
+
+bind_subst(Arg, Pats, Map) ->
+  case cerl:type(Arg) of
+    values ->
+      bind_subst_list(cerl:values_es(Arg), Pats, Map);
+    var ->
+      [Pat] = Pats,
+      enter_subst(Arg, Pat, Map);
+    _ ->
+      Map
+  end.
+
+bind_subst_list([Arg|ArgLeft], [Pat|PatLeft], Map) ->
+  NewMap =
+    case {cerl:type(Arg), cerl:type(Pat)} of
+      {var, var} ->         enter_subst(Arg, Pat, Map);
+      {var, alias} ->       enter_subst(Arg, cerl:alias_pat(Pat), Map);
+      {literal, literal} -> Map;
+      {T, T} ->             bind_subst_list(lists:flatten(cerl:subtrees(Arg)),
+					    lists:flatten(cerl:subtrees(Pat)),
+					    Map);
+      _ ->                  Map
+    end,
+  bind_subst_list(ArgLeft, PatLeft, NewMap);
+bind_subst_list([], [], Map) ->
+  Map.
+
+%%----------------------------------------
+%% Patterns
+%%
+
+bind_pat_vars(Pats, Types, Acc, Map, State) ->
+  try
+    bind_pat_vars(Pats, Types, Acc, Map, State, false)
+  catch
+    throw:Error -> 
+      %% Error = {error, bind | opaque | record, ErrorPats, ErrorType}
+      Error 
+  end.
+
+bind_pat_vars_reverse(Pats, Types, Acc, Map, State) ->
+  try
+    bind_pat_vars(Pats, Types, Acc, Map, State, true)
+  catch
+    throw:Error -> 
+      %% Error = {error, bind | opaque | record, ErrorPats, ErrorType}
+      Error
+  end.
+
+bind_pat_vars([Pat|PatLeft], [Type|TypeLeft], Acc, Map, State, Rev) ->
+  ?debug("Binding pat: ~w to ~s\n", [cerl:type(Pat), format_type(Type, State)]
+),
+  Opaques = State#state.opaques,
+  {NewMap, TypeOut} =
+    case cerl:type(Pat) of
+      alias ->
+	%% Map patterns are more allowing than the type of their literal. We
+	%% must unfold AliasPat if it is a literal.
+	AliasPat = dialyzer_utils:refold_pattern(cerl:alias_pat(Pat)),
+	Var = cerl:alias_var(Pat),
+	Map1 = enter_subst(Var, AliasPat, Map),
+	{Map2, [PatType]} = bind_pat_vars([AliasPat], [Type], [],
+					  Map1, State, Rev),
+	{enter_type(Var, PatType, Map2), PatType};
+      binary ->
+	%% Cannot bind the binary if we are in reverse match since
+	%% binary patterns and binary construction are not symmetric.
+	case Rev of
+	  true -> {Map, t_bitstr()};
+	  false ->
+	    BinType = t_inf(t_bitstr(), Type, Opaques),
+	    case t_is_none(BinType) of
+	      true ->
+                case t_find_opaque_mismatch(t_bitstr(), Type, Opaques) of
+                  {ok, T1, T2}  ->
+                    bind_error([Pat], T1, T2, opaque);
+                  error ->
+                    bind_error([Pat], Type, t_none(), bind)
+                end;
+	      false ->
+		Segs = cerl:binary_segments(Pat),
+		{Map1, SegTypes} = bind_bin_segs(Segs, BinType, Map, State),
+		{Map1, t_bitstr_concat(SegTypes)}
+	    end
+	end;
+      cons ->
+	Cons = t_inf(Type, t_cons(), Opaques),
+	case t_is_none(Cons) of
+	  true ->
+	    bind_opaque_pats(t_cons(), Type, Pat, State);
+	  false ->
+	    {Map1, [HdType, TlType]} =
+	      bind_pat_vars([cerl:cons_hd(Pat), cerl:cons_tl(Pat)],
+			    [t_cons_hd(Cons, Opaques),
+                             t_cons_tl(Cons, Opaques)],
+			    [], Map, State, Rev),
+	    {Map1, t_cons(HdType, TlType)}
+	end;
+      literal ->
+	Pat0 = dialyzer_utils:refold_pattern(Pat),
+	case cerl:is_literal(Pat0) of
+	  true ->
+	    Literal = literal_type(Pat),
+	    case t_is_none(t_inf(Literal, Type, Opaques)) of
+	      true ->
+		bind_opaque_pats(Literal, Type, Pat, State);
+	      false -> {Map, Literal}
+	    end;
+	  false ->
+	    %% Retry with the unfolded pattern
+	    {Map1, [PatType]}
+	      = bind_pat_vars([Pat0], [Type], [], Map, State, Rev),
+	    {Map1, PatType}
+	end;
+      map ->
+	MapT = t_inf(Type, t_map(), Opaques),
+	case t_is_none(MapT) of
+	  true ->
+	    bind_opaque_pats(t_map(), Type, Pat, State);
+	  false ->
+	    case Rev of
+	      %% TODO: Reverse matching (propagating a matched subset back to a value)
+	      true -> {Map, MapT};
+	      false ->
+		FoldFun =
+		  fun(Pair, {MapAcc, ListAcc}) ->
+		      %% Only exact (:=) can appear in patterns
+		      exact = cerl:concrete(cerl:map_pair_op(Pair)),
+		      Key = cerl:map_pair_key(Pair),
+		      KeyType =
+			case cerl:type(Key) of
+			  var ->
+			    case state__lookup_type_for_letrec(Key, State) of
+			      error -> lookup_type(Key, MapAcc);
+			      {ok, RecType} -> RecType
+			    end;
+			  literal ->
+			    literal_type(Key)
+			end,
+		      Bind = erl_types:t_map_get(KeyType, MapT),
+		      {MapAcc1, [ValType]} =
+			bind_pat_vars([cerl:map_pair_val(Pair)],
+				      [Bind], [], MapAcc, State, Rev),
+		      case t_is_singleton(KeyType, Opaques) of
+			true  -> {MapAcc1, [{KeyType, ValType}|ListAcc]};
+			false -> {MapAcc1, ListAcc}
+		      end
+		  end,
+		{Map1, Pairs} = lists:foldl(FoldFun, {Map, []}, cerl:map_es(Pat)),
+		{Map1, t_inf(MapT, t_map(Pairs))}
+	    end
+	end;
+      tuple ->
+	Es = cerl:tuple_es(Pat),
+	{TypedRecord, Prototype} =
+	  case Es of
+	    [] -> {false, t_tuple([])};
+	    [Tag|Left] ->
+	      case cerl:is_c_atom(Tag) andalso is_literal_record(Pat) of
+		true ->
+		  TagAtom = cerl:atom_val(Tag),
+		  case state__lookup_record(TagAtom, length(Left), State) of
+		    error -> {false, t_tuple(length(Es))};
+		    {ok, Record} ->
+		      [_Head|AnyTail] = [t_any() || _ <- Es],
+		      UntypedRecord = t_tuple([t_atom(TagAtom)|AnyTail]),
+		      {not t_is_equal(Record, UntypedRecord), Record}
+		  end;
+		false -> {false, t_tuple(length(Es))}
+	      end
+	  end,
+	Tuple = t_inf(Prototype, Type, Opaques),
+	case t_is_none(Tuple) of
+	  true ->
+	    bind_opaque_pats(Prototype, Type, Pat, State);
+	  false ->
+	    SubTuples = t_tuple_subtypes(Tuple, Opaques),
+	    %% Need to call the top function to get the try-catch wrapper
+            MapJ = join_maps_begin(Map),
+	    Results =
+	      case Rev of
+		true ->
+		  [bind_pat_vars_reverse(Es, t_tuple_args(SubTuple, Opaques),
+                                         [], MapJ, State)
+		   || SubTuple <- SubTuples];
+		false ->
+		  [bind_pat_vars(Es, t_tuple_args(SubTuple, Opaques), [],
+                                 MapJ, State)
+		   || SubTuple <- SubTuples]
+	      end,
+	    case lists:keyfind(opaque, 2, Results) of
+	      {error, opaque, _PatList, _Type, Opaque} ->
+		bind_error([Pat], Tuple, Opaque, opaque);
+	      false ->
+		case [M || {M, _} <- Results, M =/= error] of
+		  [] ->
+		    case TypedRecord of
+		      true -> bind_error([Pat], Tuple, Prototype, record);
+		      false -> bind_error([Pat], Tuple, t_none(), bind)
+		    end;
+		  Maps ->
+		    Map1 = join_maps_end(Maps, MapJ),
+		    TupleType = t_sup([t_tuple(EsTypes)
+				       || {M, EsTypes} <- Results, M =/= error]),
+		    {Map1, TupleType}
+		end
+	    end
+	end;
+      values ->
+	Es = cerl:values_es(Pat),
+	{Map1, EsTypes} =
+	  bind_pat_vars(Es, t_to_tlist(Type), [], Map, State, Rev),
+	{Map1, t_product(EsTypes)};
+      var ->
+	VarType1 =
+	  case state__lookup_type_for_letrec(Pat, State) of
+	    error -> lookup_type(Pat, Map);
+	    {ok, RecType} -> RecType
+	  end,
+	%% Must do inf when binding args to pats. Vars in pats are fresh.
+	VarType2 = t_inf(VarType1, Type, Opaques),
+	case t_is_none(VarType2) of
+	  true ->
+	    case t_find_opaque_mismatch(VarType1, Type, Opaques) of
+	      {ok, T1, T2}  ->
+		bind_error([Pat], T1, T2, opaque);
+	      error ->
+		bind_error([Pat], Type, t_none(), bind)
+	    end;
+	  false ->
+	    Map1 = enter_type(Pat, VarType2, Map),
+	    {Map1, VarType2}
+	end;
+      _Other ->
+	%% Catch all is needed when binding args to pats
+	?debug("Failed match for ~p\n", [_Other]),
+	bind_error([Pat], Type, t_none(), bind)
+    end,
+  bind_pat_vars(PatLeft, TypeLeft, [TypeOut|Acc], NewMap, State, Rev);
+bind_pat_vars([], [], Acc, Map, _State, _Rev) ->
+  {Map, lists:reverse(Acc)}.
+
+bind_bin_segs(BinSegs, BinType, Map, State) ->
+  bind_bin_segs(BinSegs, BinType, [], Map, State).
+
+bind_bin_segs([Seg|Segs], BinType, Acc, Map, State) ->
+  Val = cerl:bitstr_val(Seg),
+  SegType = cerl:concrete(cerl:bitstr_type(Seg)),
+  UnitVal = cerl:concrete(cerl:bitstr_unit(Seg)),
+  case cerl:bitstr_bitsize(Seg) of
+    all ->
+      binary = SegType, [] = Segs, %% just an assert
+      T = t_inf(t_bitstr(UnitVal, 0), BinType),
+      {Map1, [Type]} = bind_pat_vars([Val], [T], [], Map, State, false),
+      Type1 = remove_local_opaque_types(Type, State#state.opaques),
+      bind_bin_segs(Segs, t_bitstr(0, 0), [Type1|Acc], Map1, State);
+    utf -> % XXX: possibly can be strengthened
+      true = lists:member(SegType, [utf8, utf16, utf32]),
+      {Map1, [_]} = bind_pat_vars([Val], [t_integer()], [], Map, State, false),
+      Type = t_binary(),
+      bind_bin_segs(Segs, BinType, [Type|Acc], Map1, State);
+    BitSz when is_integer(BitSz) orelse BitSz =:= any ->
+      Size = cerl:bitstr_size(Seg),
+      {Map1, [SizeType]} =
+	bind_pat_vars([Size], [t_non_neg_integer()], [], Map, State, false),
+      Opaques = State#state.opaques,
+      NumberVals = t_number_vals(SizeType, Opaques),
+      case t_contains_opaque(SizeType, Opaques) of
+        true -> bind_error([Seg], SizeType, t_none(), opaque);
+        false -> ok
+      end,
+      Type =
+	case NumberVals of
+	  [OneSize] -> t_bitstr(0, UnitVal * OneSize);
+	  _ -> % 'unknown' too
+	    MinSize = erl_types:number_min(SizeType, Opaques),
+	    t_bitstr(UnitVal, UnitVal * MinSize)
+	end,
+      ValConstr =
+	case SegType of
+	  binary -> Type; %% The same constraints as for the whole bitstr
+	  float -> t_float();
+	  integer ->
+	    case NumberVals of
+	      unknown -> t_integer();
+	      List ->
+		SizeVal = lists:max(List),
+		Flags = cerl:concrete(cerl:bitstr_flags(Seg)),
+		N = SizeVal * UnitVal,
+                case N >= ?BITS  of
+                  true ->
+                    case lists:member(signed, Flags) of
+                      true -> t_from_range(neg_inf, pos_inf);
+                      false -> t_from_range(0, pos_inf)
+                    end;
+                  false ->
+                    case lists:member(signed, Flags) of
+                      true -> t_from_range(-(1 bsl (N - 1)), 1 bsl (N - 1) - 1);
+                      false -> t_from_range(0, 1 bsl N - 1)
+                    end
+                end
+	    end
+	end,
+      {Map2, [_]} = bind_pat_vars([Val], [ValConstr], [], Map1, State, false),
+      NewBinType = t_bitstr_match(Type, BinType),
+      case t_is_none(NewBinType) of
+	true -> bind_error([Seg], BinType, t_none(), bind);
+	false -> bind_bin_segs(Segs, NewBinType, [Type|Acc], Map2, State)
+      end
+  end;
+bind_bin_segs([], _BinType, Acc, Map, _State) ->
+  {Map, lists:reverse(Acc)}.
+
+bind_error(Pats, Type, OpaqueType, Error0) ->
+  Error = case {Error0, Pats} of
+            {bind, [Pat]} ->
+              case is_literal_record(Pat) of
+                true -> record;
+                false -> Error0
+              end;
+            _ -> Error0
+          end,
+  throw({error, Error, Pats, Type, OpaqueType}).
+
+-spec bind_opaque_pats(type(), type(), cerl:c_literal(), state()) ->
+                          no_return().
+
+bind_opaque_pats(GenType, Type, Pat, State) ->
+  case t_find_opaque_mismatch(GenType, Type, State#state.opaques) of
+    {ok, T1, T2}  ->
+	bind_error([Pat], T1, T2, opaque);
+    error ->
+      bind_error([Pat], Type, t_none(), bind)
+  end.
+
+%%----------------------------------------
+%% Guards
+%%
+
+bind_guard(Guard, Map, State) ->
+  try bind_guard(Guard, Map, maps:new(), pos, State) of
+    {Map1, _Type} -> Map1
+  catch
+    throw:{fail, Warning} -> {error, Warning};
+    throw:{fatal_fail, Warning} -> {error, Warning}
+  end.
+
+bind_guard(Guard, Map, Env, Eval, State) ->
+  ?debug("Handling ~w guard: ~s\n",
+	 [Eval, cerl_prettypr:format(Guard, [{noann, true}])]),
+  case cerl:type(Guard) of
+    binary ->
+      {Map, t_binary()};
+    'case' ->
+      Arg = cerl:case_arg(Guard),
+      Clauses = cerl:case_clauses(Guard),
+      bind_guard_case_clauses(Arg, Clauses, Map, Env, Eval, State);
+    cons ->
+      Hd = cerl:cons_hd(Guard),
+      Tl = cerl:cons_tl(Guard),
+      {Map1, HdType} = bind_guard(Hd, Map, Env, dont_know, State),
+      {Map2, TlType} = bind_guard(Tl, Map1, Env, dont_know, State),
+      {Map2, t_cons(HdType, TlType)};
+    literal ->
+      {Map, literal_type(Guard)};
+    'try' ->
+      Arg = cerl:try_arg(Guard),
+      [Var] = cerl:try_vars(Guard),
+      EVars = cerl:try_evars(Guard),
+      %%?debug("Storing: ~w\n", [Var]),
+      Map1 = join_maps_begin(Map),
+      Map2 = mark_as_fresh(EVars, Map1),
+      %% Visit handler first so we know if it should be ignored
+      {{HandlerMap, HandlerType}, HandlerE} =
+	try {bind_guard(cerl:try_handler(Guard), Map2, Env, Eval, State), none}
+	catch throw:HE ->
+	    {{Map2, t_none()}, HE}
+	end,
+      BodyEnv = maps:put(get_label(Var), Arg, Env),
+      Wanted = case Eval of pos -> t_atom(true); neg -> t_atom(false);
+		 dont_know -> t_any() end,
+      case t_is_none(t_inf(HandlerType, Wanted)) of
+	%% Handler won't save us; pretend it does not exist
+	true -> bind_guard(cerl:try_body(Guard), Map, BodyEnv, Eval, State);
+	false ->
+	  {{BodyMap, BodyType}, BodyE} =
+	    try {bind_guard(cerl:try_body(Guard), Map1, BodyEnv,
+			    Eval, State), none}
+	    catch throw:BE ->
+		{{Map1, t_none()}, BE}
+	    end,
+	  Map3 = join_maps_end([BodyMap, HandlerMap], Map1),
+	  case t_is_none(Sup = t_sup(BodyType, HandlerType)) of
+	    true ->
+	      %% Pick a reason. N.B. We assume that the handler is always
+	      %% compiler-generated if the body is; that way, we won't need to
+	      %% check.
+	      Fatality = case {BodyE, HandlerE} of
+			   {{fatal_fail, _}, _} -> fatal_fail;
+			   {_, {fatal_fail, _}} -> fatal_fail;
+			   _ -> fail
+			 end,
+	      throw({Fatality,
+		     case {BodyE, HandlerE} of
+		       {{_, Rsn}, _} when Rsn =/= none -> Rsn;
+		       {_, {_,Rsn}} -> Rsn;
+		       _ -> none
+		     end});
+	    false -> {Map3, Sup}
+	  end
+      end;
+    tuple ->
+      Es0 = cerl:tuple_es(Guard),
+      {Map1, Es} = bind_guard_list(Es0, Map, Env, dont_know, State),
+      {Map1, t_tuple(Es)};
+    map ->
+      case Eval of
+	dont_know -> handle_guard_map(Guard, Map, Env, State);
+	_PosOrNeg -> {Map, t_none()}  %% Map exprs do not produce bools
+      end;
+    'let' ->
+      Arg = cerl:let_arg(Guard),
+      [Var] = cerl:let_vars(Guard),
+      %%?debug("Storing: ~w\n", [Var]),
+      NewEnv = maps:put(get_label(Var), Arg, Env),
+      bind_guard(cerl:let_body(Guard), Map, NewEnv, Eval, State);
+    values ->
+      Es = cerl:values_es(Guard),
+      List = [bind_guard(V, Map, Env, dont_know, State) || V <- Es],
+      Type = t_product([T || {_, T} <- List]),
+      {Map, Type};
+    var ->
+      ?debug("Looking for var(~w)...", [cerl_trees:get_label(Guard)]),
+      case maps:find(get_label(Guard), Env) of
+	error ->
+	  ?debug("Did not find it\n", []),
+	  Type = lookup_type(Guard, Map),
+	  Constr =
+	    case Eval of
+	      pos -> t_atom(true);
+	      neg -> t_atom(false);
+	      dont_know -> Type
+	    end,
+	  Inf = t_inf(Constr, Type),
+	  {enter_type(Guard, Inf, Map), Inf};
+	{ok, Tree} ->
+	  ?debug("Found it\n", []),
+	  {Map1, Type} = bind_guard(Tree, Map, Env, Eval, State),
+	  {enter_type(Guard, Type, Map1), Type}
+      end;
+    call ->
+      handle_guard_call(Guard, Map, Env, Eval, State)
+  end.
+
+handle_guard_call(Guard, Map, Env, Eval, State) ->
+  MFA = {cerl:atom_val(cerl:call_module(Guard)),
+	 cerl:atom_val(cerl:call_name(Guard)),
+	 cerl:call_arity(Guard)},
+  case MFA of
+    {erlang, F, 1} when F =:= is_atom; F =:= is_boolean;
+			F =:= is_binary; F =:= is_bitstring;
+			F =:= is_float; F =:= is_function;
+			F =:= is_integer; F =:= is_list; F =:= is_map;
+			F =:= is_number; F =:= is_pid; F =:= is_port;
+			F =:= is_reference; F =:= is_tuple ->
+      handle_guard_type_test(Guard, F, Map, Env, Eval, State);
+    {erlang, is_function, 2} ->
+      handle_guard_is_function(Guard, Map, Env, Eval, State);
+    MFA when (MFA =:= {erlang, internal_is_record, 3}) or
+	     (MFA =:= {erlang, is_record, 3}) ->
+      handle_guard_is_record(Guard, Map, Env, Eval, State);
+    {erlang, '=:=', 2} ->
+      handle_guard_eqeq(Guard, Map, Env, Eval, State);
+    {erlang, '==', 2} ->
+      handle_guard_eq(Guard, Map, Env, Eval, State);
+    {erlang, 'and', 2} ->
+      handle_guard_and(Guard, Map, Env, Eval, State);
+    {erlang, 'or', 2} ->
+      handle_guard_or(Guard, Map, Env, Eval, State);
+    {erlang, 'not', 1} ->
+      handle_guard_not(Guard, Map, Env, Eval, State);
+    {erlang, Comp, 2} when Comp =:= '<'; Comp =:= '=<';
+                           Comp =:= '>'; Comp =:= '>=' ->
+      handle_guard_comp(Guard, Comp, Map, Env, Eval, State);
+    _ ->
+      handle_guard_gen_fun(MFA, Guard, Map, Env, Eval, State)
+  end.
+
+handle_guard_gen_fun({M, F, A}, Guard, Map, Env, Eval, State) ->
+  Args = cerl:call_args(Guard),
+  {Map1, As} = bind_guard_list(Args, Map, Env, dont_know, State),
+  Opaques = State#state.opaques,
+  BifRet = erl_bif_types:type(M, F, A, As, Opaques),
+  case t_is_none(BifRet) of
+    true ->
+      %% Is this an error-bif?
+      case t_is_none(erl_bif_types:type(M, F, A)) of
+	true -> signal_guard_fail(Eval, Guard, As, State);
+	false -> signal_guard_fatal_fail(Eval, Guard, As, State)
+      end;
+    false ->
+      BifArgs = bif_args(M, F, A),
+      Map2 = enter_type_lists(Args, t_inf_lists(BifArgs, As, Opaques), Map1),
+      Ret =
+	case Eval of
+	  pos -> t_inf(t_atom(true), BifRet);
+	  neg -> t_inf(t_atom(false), BifRet);
+	  dont_know -> BifRet
+	end,
+      case t_is_none(Ret) of
+	true ->
+	  case Eval =:= pos of
+	    true -> signal_guard_fail(Eval, Guard, As, State);
+	    false -> throw({fail, none})
+	  end;
+	false -> {Map2, Ret}
+      end
+  end.
+
+handle_guard_type_test(Guard, F, Map, Env, Eval, State) ->
+  [Arg] = cerl:call_args(Guard),
+  {Map1, ArgType} = bind_guard(Arg, Map, Env, dont_know, State),
+  case bind_type_test(Eval, F, ArgType, State) of
+    error ->
+      ?debug("Type test: ~w failed\n", [F]),
+      signal_guard_fail(Eval, Guard, [ArgType], State);
+    {ok, NewArgType, Ret} ->
+      ?debug("Type test: ~w succeeded, NewType: ~s, Ret: ~s\n",
+	     [F, t_to_string(NewArgType), t_to_string(Ret)]),
+      {enter_type(Arg, NewArgType, Map1), Ret}
+  end.
+
+bind_type_test(Eval, TypeTest, ArgType, State) ->
+  Type = case TypeTest of
+	   is_atom -> t_atom();
+	   is_boolean -> t_boolean();
+	   is_binary -> t_binary();
+	   is_bitstring -> t_bitstr();
+	   is_float -> t_float();
+	   is_function -> t_fun();
+	   is_integer -> t_integer();
+	   is_list -> t_maybe_improper_list();
+	   is_map -> t_map();
+	   is_number -> t_number();
+	   is_pid -> t_pid();
+	   is_port -> t_port();
+	   is_reference -> t_reference();
+	   is_tuple -> t_tuple()
+	 end,
+  case Eval of
+    pos ->
+      Inf = t_inf(Type, ArgType, State#state.opaques),
+      case t_is_none(Inf) of
+	true -> error;
+	false -> {ok, Inf, t_atom(true)}
+      end;
+    neg ->
+      Sub = t_subtract(ArgType, Type),
+      case t_is_none(Sub) of
+        true -> error;
+        false -> {ok, Sub, t_atom(false)}
+      end;
+    dont_know ->
+      {ok, ArgType, t_boolean()}
+  end.
+
+handle_guard_comp(Guard, Comp, Map, Env, Eval, State) ->
+  Args = cerl:call_args(Guard),
+  [Arg1, Arg2] = Args,
+  {Map1, ArgTypes} = bind_guard_list(Args, Map, Env, dont_know, State),
+  Opaques = State#state.opaques,
+  [Type1, Type2] = ArgTypes,
+  IsInt1 = t_is_integer(Type1, Opaques),
+  IsInt2 = t_is_integer(Type2, Opaques),
+  case {type(Arg1), type(Arg2)} of
+    {{literal, Lit1}, {literal, Lit2}} ->
+      case erlang:Comp(cerl:concrete(Lit1), cerl:concrete(Lit2)) of
+	true  when Eval =:= pos ->       {Map, t_atom(true)};
+	true  when Eval =:= dont_know -> {Map, t_atom(true)};
+	true  when Eval =:= neg ->       {Map, t_atom(true)};
+	false when Eval =:= pos ->
+	  signal_guard_fail(Eval, Guard, ArgTypes, State);
+	false when Eval =:= dont_know -> {Map, t_atom(false)};
+	false when Eval =:= neg ->       {Map, t_atom(false)}
+      end;
+    {{literal, Lit1}, var} when IsInt1 andalso IsInt2 andalso (Eval =:= pos) ->
+      case bind_comp_literal_var(Lit1, Arg2, Type2, Comp, Map1, Opaques) of
+	error -> signal_guard_fail(Eval, Guard, ArgTypes, State);
+	{ok, NewMap} -> {NewMap, t_atom(true)}
+      end;
+    {var, {literal, Lit2}} when IsInt1 andalso IsInt2 andalso (Eval =:= pos) ->
+      case bind_comp_literal_var(Lit2, Arg1, Type1, invert_comp(Comp),
+                                 Map1, Opaques) of
+	error -> signal_guard_fail(Eval, Guard, ArgTypes, State);
+	{ok, NewMap} -> {NewMap, t_atom(true)}
+      end;
+    {_, _} ->
+      handle_guard_gen_fun({erlang, Comp, 2}, Guard, Map, Env, Eval, State)
+  end.
+
+invert_comp('=<') -> '>=';
+invert_comp('<')  -> '>';
+invert_comp('>=') -> '=<';
+invert_comp('>')  -> '<'.
+
+bind_comp_literal_var(Lit, Var, VarType, CompOp, Map, Opaques) ->
+  LitVal = cerl:concrete(Lit),
+  NewVarType =
+    case t_number_vals(VarType, Opaques) of
+      unknown ->
+	Range =
+	  case CompOp of
+	    '=<' -> t_from_range(LitVal, pos_inf);
+	    '<'  -> t_from_range(LitVal + 1, pos_inf);
+	    '>=' -> t_from_range(neg_inf, LitVal);
+	    '>'  -> t_from_range(neg_inf, LitVal - 1)
+	  end,
+	t_inf(Range, VarType, Opaques);
+      NumberVals ->
+	NewNumberVals = [X || X <- NumberVals, erlang:CompOp(LitVal, X)],
+	t_integers(NewNumberVals)
+    end,
+  case t_is_none(NewVarType) of
+    true -> error;
+    false -> {ok, enter_type(Var, NewVarType, Map)}
+  end.
+
+handle_guard_is_function(Guard, Map, Env, Eval, State) ->
+  Args = cerl:call_args(Guard),
+  {Map1, ArgTypes0} = bind_guard_list(Args, Map, Env, dont_know, State),
+  [FunType0, ArityType0] = ArgTypes0,
+  Opaques = State#state.opaques,
+  ArityType = t_inf(ArityType0, t_integer(), Opaques),
+  case t_is_none(ArityType) of
+    true -> signal_guard_fail(Eval, Guard, ArgTypes0, State);
+    false ->
+      FunTypeConstr =
+	case t_number_vals(ArityType, State#state.opaques) of
+	  unknown -> t_fun();
+	  Vals ->
+	    t_sup([t_fun(lists:duplicate(X, t_any()), t_any()) || X <- Vals])
+	end,
+      FunType = t_inf(FunType0, FunTypeConstr, Opaques),
+      case t_is_none(FunType) of
+	true ->
+	  case Eval of
+	    pos -> signal_guard_fail(Eval, Guard, ArgTypes0, State);
+	    neg -> {Map1, t_atom(false)};
+	    dont_know -> {Map1, t_atom(false)}
+	  end;
+	false ->
+	  case Eval of
+	    pos -> {enter_type_lists(Args, [FunType, ArityType], Map1),
+		    t_atom(true)};
+	    neg -> {Map1, t_atom(false)};
+	    dont_know -> {Map1, t_boolean()}
+	  end
+      end
+  end.
+
+handle_guard_is_record(Guard, Map, Env, Eval, State) ->
+  Args = cerl:call_args(Guard),
+  [Rec, Tag0, Arity0] = Args,
+  Tag = cerl:atom_val(Tag0),
+  Arity = cerl:int_val(Arity0),
+  {Map1, RecType} = bind_guard(Rec, Map, Env, dont_know, State),
+  ArityMin1 = Arity - 1,
+  Opaques = State#state.opaques,
+  Tuple = t_tuple([t_atom(Tag)|lists:duplicate(ArityMin1, t_any())]),
+  case t_is_none(t_inf(Tuple, RecType, Opaques)) of
+    true ->
+      case erl_types:t_has_opaque_subtype(RecType, Opaques) of
+        true ->
+          signal_guard_fail(Eval, Guard,
+                            [RecType, t_from_term(Tag),
+                             t_from_term(Arity)],
+                            State);
+        false ->
+          case Eval of
+            pos -> signal_guard_fail(Eval, Guard,
+                                     [RecType, t_from_term(Tag),
+                                      t_from_term(Arity)],
+                                     State);
+            neg -> {Map1, t_atom(false)};
+            dont_know -> {Map1, t_atom(false)}
+          end
+      end;
+    false ->
+      TupleType =
+        case state__lookup_record(Tag, ArityMin1, State) of
+          error -> Tuple;
+          {ok, Prototype} -> Prototype
+        end,
+      Type = t_inf(TupleType, RecType, State#state.opaques),
+      case t_is_none(Type) of
+        true ->
+          %% No special handling of opaque errors.
+          FArgs = "record " ++ format_type(RecType, State),
+          Msg = {record_matching, [FArgs, Tag]},
+          throw({fail, {Guard, Msg}});
+        false ->
+          case Eval of
+            pos -> {enter_type(Rec, Type, Map1), t_atom(true)};
+            neg -> {Map1, t_atom(false)};
+            dont_know -> {Map1, t_boolean()}
+          end
+      end
+  end.
+
+handle_guard_eq(Guard, Map, Env, Eval, State) ->
+  [Arg1, Arg2] = cerl:call_args(Guard),
+  case {type(Arg1), type(Arg2)} of
+    {{literal, Lit1}, {literal, Lit2}} ->
+      case cerl:concrete(Lit1) =:= cerl:concrete(Lit2) of
+	true ->
+	  if
+	    Eval =:= pos -> {Map, t_atom(true)};
+	    Eval =:= neg ->
+	      ArgTypes = [t_from_term(cerl:concrete(Lit1)),
+			  t_from_term(cerl:concrete(Lit2))],
+	      signal_guard_fail(Eval, Guard, ArgTypes, State);
+	    Eval =:= dont_know -> {Map, t_atom(true)}
+	  end;
+	false ->
+	  if
+	    Eval =:= neg -> {Map, t_atom(false)};
+	    Eval =:= dont_know -> {Map, t_atom(false)};
+	    Eval =:= pos ->
+	      ArgTypes = [t_from_term(cerl:concrete(Lit1)),
+			  t_from_term(cerl:concrete(Lit2))],
+	      signal_guard_fail(Eval, Guard, ArgTypes, State)
+	  end
+      end;
+    {{literal, Lit1}, _} when Eval =:= pos ->
+      case cerl:concrete(Lit1) of
+	Atom when is_atom(Atom) ->
+	  bind_eqeq_guard_lit_other(Guard, Lit1, Arg2, Map, Env, State);
+	[] ->
+	  bind_eqeq_guard_lit_other(Guard, Lit1, Arg2, Map, Env, State);
+	_ ->
+	  bind_eq_guard(Guard, Lit1, Arg2, Map, Env, Eval, State)
+      end;
+    {_, {literal, Lit2}} when Eval =:= pos ->
+      case cerl:concrete(Lit2) of
+	Atom when is_atom(Atom) ->
+	  bind_eqeq_guard_lit_other(Guard, Lit2, Arg1, Map, Env, State);
+	[] ->
+	  bind_eqeq_guard_lit_other(Guard, Lit2, Arg1, Map, Env, State);
+	_ ->
+	  bind_eq_guard(Guard, Arg1, Lit2, Map, Env, Eval, State)
+      end;
+    {_, _} ->
+      bind_eq_guard(Guard, Arg1, Arg2, Map, Env, Eval, State)
+  end.
+
+bind_eq_guard(Guard, Arg1, Arg2, Map, Env, Eval, State) ->
+  {Map1, Type1} = bind_guard(Arg1, Map, Env, dont_know, State),
+  {Map2, Type2} = bind_guard(Arg2, Map1, Env, dont_know, State),
+  Opaques = State#state.opaques,
+  case
+    t_is_nil(Type1, Opaques) orelse t_is_nil(Type2, Opaques)
+    orelse t_is_atom(Type1, Opaques) orelse t_is_atom(Type2, Opaques)
+  of
+    true -> bind_eqeq_guard(Guard, Arg1, Arg2, Map, Env, Eval, State);
+    false ->
+      %% XXX. Is this test OK?
+      OpArgs = erl_types:t_find_unknown_opaque(Type1, Type2, Opaques),
+      case OpArgs =:= [] of
+        true ->
+          case Eval of
+            pos -> {Map2, t_atom(true)};
+            neg -> {Map2, t_atom(false)};
+            dont_know -> {Map2, t_boolean()}
+          end;
+        false ->
+          signal_guard_fail(Eval, Guard, [Type1, Type2], State)
+      end
+  end.
+
+handle_guard_eqeq(Guard, Map, Env, Eval, State) ->
+  [Arg1, Arg2] = cerl:call_args(Guard),
+  case {type(Arg1), type(Arg2)} of
+    {{literal, Lit1}, {literal, Lit2}} ->
+
+      case cerl:concrete(Lit1) =:= cerl:concrete(Lit2) of
+	true ->
+	  if Eval =:= neg ->
+	      ArgTypes = [t_from_term(cerl:concrete(Lit1)),
+			  t_from_term(cerl:concrete(Lit2))],
+	      signal_guard_fail(Eval, Guard, ArgTypes, State);
+	     Eval =:= pos -> {Map, t_atom(true)};
+	     Eval =:= dont_know -> {Map, t_atom(true)}
+	  end;
+	false ->
+	  if Eval =:= neg -> {Map, t_atom(false)};
+	     Eval =:= dont_know -> {Map, t_atom(false)};
+	     Eval =:= pos ->
+	      ArgTypes = [t_from_term(cerl:concrete(Lit1)),
+			  t_from_term(cerl:concrete(Lit2))],
+	      signal_guard_fail(Eval, Guard, ArgTypes, State)
+	  end
+      end;
+    {{literal, Lit1}, _} when Eval =:= pos ->
+      bind_eqeq_guard_lit_other(Guard, Lit1, Arg2, Map, Env, State);
+    {_, {literal, Lit2}} when Eval =:= pos ->
+      bind_eqeq_guard_lit_other(Guard, Lit2, Arg1, Map, Env, State);
+    {_, _} ->
+      bind_eqeq_guard(Guard, Arg1, Arg2, Map, Env, Eval, State)
+  end.
+
+bind_eqeq_guard(Guard, Arg1, Arg2, Map, Env, Eval, State) ->
+  {Map1, Type1} = bind_guard(Arg1, Map, Env, dont_know, State),
+  {Map2, Type2} = bind_guard(Arg2, Map1, Env, dont_know, State),
+  ?debug("Types are:~s =:= ~s\n", [t_to_string(Type1),
+				   t_to_string(Type2)]),
+  Opaques = State#state.opaques,
+  Inf = t_inf(Type1, Type2, Opaques),
+  case t_is_none(Inf) of
+    true ->
+      OpArgs = erl_types:t_find_unknown_opaque(Type1, Type2, Opaques),
+      case OpArgs =:= [] of
+        true ->
+          case Eval of
+            neg -> {Map2, t_atom(false)};
+            dont_know -> {Map2, t_atom(false)};
+            pos -> signal_guard_fail(Eval, Guard, [Type1, Type2], State)
+          end;
+        false ->
+          signal_guard_fail(Eval, Guard, [Type1, Type2], State)
+      end;
+    false ->
+      case Eval of
+        pos ->
+          case {cerl:type(Arg1), cerl:type(Arg2)} of
+            {var, var} ->
+              Map3 = enter_subst(Arg1, Arg2, Map2),
+              Map4 = enter_type(Arg2, Inf, Map3),
+              {Map4, t_atom(true)};
+            {var, _} ->
+              Map3 = enter_type(Arg1, Inf, Map2),
+              {Map3, t_atom(true)};
+            {_, var} ->
+              Map3 = enter_type(Arg2, Inf, Map2),
+              {Map3, t_atom(true)};
+            {_, _} ->
+              {Map2, t_atom(true)}
+          end;
+        neg ->
+          {Map2, t_atom(false)};
+        dont_know ->
+          {Map2, t_boolean()}
+      end
+  end.
+
+bind_eqeq_guard_lit_other(Guard, Arg1, Arg2, Map, Env, State) ->
+  Eval = dont_know,
+  Opaques = State#state.opaques,
+  case cerl:concrete(Arg1) of
+    true ->
+      {_, Type} = MT = bind_guard(Arg2, Map, Env, pos, State),
+      case t_is_any_atom(true, Type, Opaques) of
+	true -> MT;
+	false ->
+	  {_, Type0} = bind_guard(Arg2, Map, Env, Eval, State),
+	  signal_guard_fail(Eval, Guard, [Type0, t_atom(true)], State)
+      end;
+    false ->
+      {Map1, Type} = bind_guard(Arg2, Map, Env, neg, State),
+      case t_is_any_atom(false, Type, Opaques) of
+	true -> {Map1, t_atom(true)};
+	false ->
+	  {_, Type0} = bind_guard(Arg2, Map, Env, Eval, State),
+	  signal_guard_fail(Eval, Guard, [Type0, t_atom(false)], State)
+      end;
+    Term ->
+      LitType = t_from_term(Term),
+      {Map1, Type} = bind_guard(Arg2, Map, Env, Eval, State),
+      case t_is_subtype(LitType, Type) of
+	false -> signal_guard_fail(Eval, Guard, [Type, LitType], State);
+	true ->
+	  case cerl:is_c_var(Arg2) of
+	    true -> {enter_type(Arg2, LitType, Map1), t_atom(true)};
+	    false -> {Map1, t_atom(true)}
+	  end
+      end
+  end.
+
+handle_guard_and(Guard, Map, Env, Eval, State) ->
+  [Arg1, Arg2] = cerl:call_args(Guard),
+  Opaques = State#state.opaques,
+  case Eval of
+    pos ->
+      {Map1, Type1} = bind_guard(Arg1, Map, Env, Eval, State),
+      case t_is_any_atom(true, Type1, Opaques) of
+	false -> signal_guard_fail(Eval, Guard, [Type1, t_any()], State);
+	true ->
+	  {Map2, Type2} = bind_guard(Arg2, Map1, Env, Eval, State),
+	  case t_is_any_atom(true, Type2, Opaques) of
+	    false -> signal_guard_fail(Eval, Guard, [Type1, Type2], State);
+	    true -> {Map2, t_atom(true)}
+	  end
+      end;
+    neg ->
+      MapJ = join_maps_begin(Map),
+      {Map1, Type1} =
+	try bind_guard(Arg1, MapJ, Env, neg, State)
+	catch throw:{fail, _} -> bind_guard(Arg2, MapJ, Env, pos, State)
+	end,
+      {Map2, Type2} =
+	try bind_guard(Arg2, MapJ, Env, neg, State)
+	catch throw:{fail, _} -> bind_guard(Arg1, MapJ, Env, pos, State)
+	end,
+      case
+        t_is_any_atom(false, Type1, Opaques)
+        orelse t_is_any_atom(false, Type2, Opaques)
+      of
+	true -> {join_maps_end([Map1, Map2], MapJ), t_atom(false)};
+	false -> signal_guard_fail(Eval, Guard, [Type1, Type2], State)
+      end;
+    dont_know ->
+      MapJ = join_maps_begin(Map),
+      {Map1, Type1} = bind_guard(Arg1, MapJ, Env, dont_know, State),
+      {Map2, Type2} = bind_guard(Arg2, MapJ, Env, dont_know, State),
+      Bool1 = t_inf(Type1, t_boolean()),
+      Bool2 = t_inf(Type2, t_boolean()),
+      case t_is_none(Bool1) orelse t_is_none(Bool2) of
+	true -> throw({fatal_fail, none});
+	false ->
+	  NewMap = join_maps_end([Map1, Map2], MapJ),
+	  NewType =
+	    case {t_atom_vals(Bool1, Opaques), t_atom_vals(Bool2, Opaques)} of
+	      {['true'] , ['true'] } -> t_atom(true);
+	      {['false'], _        } -> t_atom(false);
+	      {_        , ['false']} -> t_atom(false);
+              {unknown  , _        } ->
+                signal_guard_fail(Eval, Guard, [Type1, Type2], State);
+              {_        , unknown  } ->
+                signal_guard_fail(Eval, Guard, [Type1, Type2], State);
+	      {_        , _        } -> t_boolean()
+
+	    end,
+	  {NewMap, NewType}
+      end
+  end.
+
+handle_guard_or(Guard, Map, Env, Eval, State) ->
+  [Arg1, Arg2] = cerl:call_args(Guard),
+  Opaques = State#state.opaques,
+  case Eval of
+    pos ->
+      MapJ = join_maps_begin(Map),
+      {Map1, Bool1} =
+	try bind_guard(Arg1, MapJ, Env, pos, State)
+	catch
+	  throw:{fail,_} -> bind_guard(Arg1, MapJ, Env, dont_know, State)
+	end,
+      {Map2, Bool2} =
+	try bind_guard(Arg2, MapJ, Env, pos, State)
+	catch
+	  throw:{fail,_} -> bind_guard(Arg2, MapJ, Env, dont_know, State)
+	end,
+      case
+        ((t_is_any_atom(true, Bool1, Opaques)
+          andalso t_is_boolean(Bool2, Opaques))
+         orelse
+           (t_is_any_atom(true, Bool2, Opaques)
+            andalso t_is_boolean(Bool1, Opaques)))
+      of
+	true -> {join_maps_end([Map1, Map2], MapJ), t_atom(true)};
+	false -> signal_guard_fail(Eval, Guard, [Bool1, Bool2], State)
+      end;
+    neg ->
+      {Map1, Type1} = bind_guard(Arg1, Map, Env, neg, State),
+      case t_is_any_atom(false, Type1, Opaques) of
+	false -> signal_guard_fail(Eval, Guard, [Type1, t_any()], State);
+	true ->
+	  {Map2, Type2} = bind_guard(Arg2, Map1, Env, neg, State),
+	  case t_is_any_atom(false, Type2, Opaques) of
+	    false -> signal_guard_fail(Eval, Guard, [Type1, Type2], State);
+	    true -> {Map2, t_atom(false)}
+	  end
+      end;
+    dont_know ->
+      MapJ = join_maps_begin(Map),
+      {Map1, Type1} = bind_guard(Arg1, MapJ, Env, dont_know, State),
+      {Map2, Type2} = bind_guard(Arg2, MapJ, Env, dont_know, State),
+      Bool1 = t_inf(Type1, t_boolean()),
+      Bool2 = t_inf(Type2, t_boolean()),
+      case t_is_none(Bool1) orelse t_is_none(Bool2) of
+	true -> throw({fatal_fail, none});
+	false ->
+	  NewMap = join_maps_end([Map1, Map2], MapJ),
+	  NewType =
+	    case {t_atom_vals(Bool1, Opaques), t_atom_vals(Bool2, Opaques)} of
+	      {['false'], ['false']} -> t_atom(false);
+	      {['true'] , _        } -> t_atom(true);
+	      {_        , ['true'] } -> t_atom(true);
+              {unknown  , _        } ->
+                signal_guard_fail(Eval, Guard, [Type1, Type2], State);
+              {_        , unknown  } ->
+                signal_guard_fail(Eval, Guard, [Type1, Type2], State);
+	      {_        , _        } -> t_boolean()
+	    end,
+	  {NewMap, NewType}
+      end
+  end.
+
+handle_guard_not(Guard, Map, Env, Eval, State) ->
+  [Arg] = cerl:call_args(Guard),
+  Opaques = State#state.opaques,
+  case Eval of
+    neg ->
+      {Map1, Type} = bind_guard(Arg, Map, Env, pos, State),
+      case t_is_any_atom(true, Type, Opaques) of
+	true -> {Map1, t_atom(false)};
+	false ->
+	  {_, Type0} = bind_guard(Arg, Map, Env, Eval, State),
+	  signal_guard_fail(Eval, Guard, [Type0], State)
+      end;
+    pos ->
+      {Map1, Type} = bind_guard(Arg, Map, Env, neg, State),
+      case t_is_any_atom(false, Type, Opaques) of
+	true -> {Map1, t_atom(true)};
+	false ->
+	  {_, Type0} = bind_guard(Arg, Map, Env, Eval, State),
+	  signal_guard_fail(Eval, Guard, [Type0], State)
+      end;
+    dont_know ->
+      {Map1, Type} = bind_guard(Arg, Map, Env, dont_know, State),
+      Bool = t_inf(Type, t_boolean()),
+      case t_is_none(Bool) of
+	true -> throw({fatal_fail, none});
+	false ->
+	  case t_atom_vals(Bool, Opaques) of
+	    ['true'] -> {Map1, t_atom(false)};
+	    ['false'] -> {Map1, t_atom(true)};
+	    [_, _] -> {Map1, Bool};
+            unknown -> signal_guard_fail(Eval, Guard, [Type], State)
+	  end
+      end
+  end.
+
+bind_guard_list(Guards, Map, Env, Eval, State) ->
+  bind_guard_list(Guards, Map, Env, Eval, State, []).
+
+bind_guard_list([G|Gs], Map, Env, Eval, State, Acc) ->
+  {Map1, T} = bind_guard(G, Map, Env, Eval, State),
+  bind_guard_list(Gs, Map1, Env, Eval, State, [T|Acc]);
+bind_guard_list([], Map, _Env, _Eval, _State, Acc) ->
+  {Map, lists:reverse(Acc)}.
+
+handle_guard_map(Guard, Map, Env, State) ->
+  Pairs = cerl:map_es(Guard),
+  Arg = cerl:map_arg(Guard),
+  {Map1, ArgType0} = bind_guard(Arg, Map, Env, dont_know, State),
+  ArgType1 = t_inf(t_map(), ArgType0),
+  case t_is_none_or_unit(ArgType1) of
+    true -> {Map1, t_none()};
+    false ->
+      {Map2, TypePairs} = bind_guard_map_pairs(Pairs, Map1, Env, State, []),
+      {Map2, lists:foldl(fun({KV,assoc},Acc) -> erl_types:t_map_put(KV,Acc);
+			    ({KV,exact},Acc) -> erl_types:t_map_update(KV,Acc)
+			 end, ArgType1, TypePairs)}
+  end.
+
+bind_guard_map_pairs([], Map, _Env, _State, PairAcc) ->
+  {Map, lists:reverse(PairAcc)};
+bind_guard_map_pairs([Pair|Pairs], Map, Env, State, PairAcc) ->
+  Key = cerl:map_pair_key(Pair),
+  Val = cerl:map_pair_val(Pair),
+  Op = cerl:map_pair_op(Pair),
+  {Map1, [K,V]} = bind_guard_list([Key,Val],Map,Env,dont_know,State),
+  bind_guard_map_pairs(Pairs, Map1, Env, State,
+		       [{{K,V},cerl:concrete(Op)}|PairAcc]).
+
+-type eval() :: 'pos' | 'neg' | 'dont_know'.
+
+-spec signal_guard_fail(eval(), cerl:c_call(), [type()],
+			state()) -> no_return().
+
+signal_guard_fail(Eval, Guard, ArgTypes, State) ->
+  signal_guard_failure(Eval, Guard, ArgTypes, fail, State).
+
+-spec signal_guard_fatal_fail(eval(), cerl:c_call(), [erl_types:erl_type()],
+			      state()) -> no_return().
+
+signal_guard_fatal_fail(Eval, Guard, ArgTypes, State) ->
+  signal_guard_failure(Eval, Guard, ArgTypes, fatal_fail, State).
+
+signal_guard_failure(Eval, Guard, ArgTypes, Tag, State) ->
+  Args = cerl:call_args(Guard),
+  F = cerl:atom_val(cerl:call_name(Guard)),
+  {M, F, A} = MFA = {cerl:atom_val(cerl:call_module(Guard)), F, length(Args)},
+  Opaques = State#state.opaques,
+  {Kind, XInfo} =
+    case erl_bif_types:opaque_args(M, F, A, ArgTypes, Opaques) of
+      [] ->
+        {case Eval of
+           neg -> neg_guard_fail;
+           pos -> guard_fail;
+           dont_know -> guard_fail
+         end,
+         []};
+      Ns -> {opaque_guard, [Ns]}
+    end,
+  FArgs =
+    case is_infix_op(MFA) of
+      true ->
+	[ArgType1, ArgType2] = ArgTypes,
+	[Arg1, Arg2] = Args,
+	[format_args_1([Arg1], [ArgType1], State),
+         atom_to_list(F),
+         format_args_1([Arg2], [ArgType2], State)] ++ XInfo;
+      false ->
+        [F, format_args(Args, ArgTypes, State)]
+    end,
+  Msg = {Kind, FArgs},
+  throw({Tag, {Guard, Msg}}).
+
+is_infix_op({erlang, '=:=', 2}) -> true;
+is_infix_op({erlang, '==', 2}) -> true;
+is_infix_op({erlang, '=/=', 2}) -> true;
+is_infix_op({erlang, '=/', 2}) -> true;
+is_infix_op({erlang, '<', 2}) -> true;
+is_infix_op({erlang, '=<', 2}) -> true;
+is_infix_op({erlang, '>', 2}) -> true;
+is_infix_op({erlang, '>=', 2}) -> true;
+is_infix_op({M, F, A}) when is_atom(M), is_atom(F),
+			    is_integer(A), 0 =< A, A =< 255 -> false.
+
+bif_args(M, F, A) ->
+  case erl_bif_types:arg_types(M, F, A) of
+    unknown -> lists:duplicate(A, t_any());
+    List -> List
+  end.
+
+bind_guard_case_clauses(Arg, Clauses, Map0, Env, Eval, State) ->
+  Clauses1 = filter_fail_clauses(Clauses),
+  Map = join_maps_begin(Map0),
+  {GenMap, GenArgType} = bind_guard(Arg, Map, Env, dont_know, State),
+  bind_guard_case_clauses(GenArgType, GenMap, Arg, Clauses1, Map, Env, Eval,
+			  t_none(), [], State).
+
+filter_fail_clauses([Clause|Left]) ->
+  case (cerl:clause_pats(Clause) =:= []) of
+    true ->
+      Body = cerl:clause_body(Clause),
+      case cerl:is_literal(Body) andalso (cerl:concrete(Body) =:= fail) orelse
+	cerl:is_c_primop(Body) andalso
+	(cerl:atom_val(cerl:primop_name(Body)) =:= match_fail) of
+	true -> filter_fail_clauses(Left);
+	false -> [Clause|filter_fail_clauses(Left)]
+      end;
+    false ->
+      [Clause|filter_fail_clauses(Left)]
+  end;
+filter_fail_clauses([]) ->
+  [].
+
+bind_guard_case_clauses(GenArgType, GenMap, ArgExpr, [Clause|Left],
+			Map, Env, Eval, AccType, AccMaps, State) ->
+  Pats = cerl:clause_pats(Clause),
+  {NewMap0, ArgType} =
+    case Pats of
+      [Pat] ->
+	case cerl:is_literal(Pat) of
+	  true ->
+	    try
+	      case cerl:concrete(Pat) of
+		true -> bind_guard(ArgExpr, Map, Env, pos, State);
+		false -> bind_guard(ArgExpr, Map, Env, neg, State);
+		_ -> {GenMap, GenArgType}
+	      end
+	    catch
+	      throw:{fail, _} -> {none, GenArgType}
+	    end;
+	  false ->
+	    {GenMap, GenArgType}
+	end;
+      _ -> {GenMap, GenArgType}
+    end,
+  NewMap1 =
+    case Pats =:= [] of
+      true -> NewMap0;
+      false ->
+	case t_is_none(ArgType) of
+	  true -> none;
+	  false ->
+	    ArgTypes = case t_is_any(ArgType) of
+			 true -> Any = t_any(), [Any || _ <- Pats];
+			 false -> t_to_tlist(ArgType)
+		       end,
+	    case bind_pat_vars(Pats, ArgTypes, [], NewMap0, State) of
+	      {error, _, _, _, _} -> none;
+	      {PatMap, _PatTypes} -> PatMap
+	    end
+	end
+    end,
+  Guard = cerl:clause_guard(Clause),
+  GenPatType = dialyzer_typesig:get_safe_underapprox(Pats, Guard),
+  NewGenArgType = t_subtract(GenArgType, GenPatType),
+  case (NewMap1 =:= none) orelse t_is_none(GenArgType) of
+    true ->
+      bind_guard_case_clauses(NewGenArgType, GenMap, ArgExpr, Left, Map, Env,
+			      Eval, AccType, AccMaps, State);
+    false ->
+      {NewAccType, NewAccMaps} =
+	try
+	  {NewMap2, GuardType} = bind_guard(Guard, NewMap1, Env, pos, State),
+	  case t_is_none(t_inf(t_atom(true), GuardType)) of
+	    true -> throw({fail, none});
+	    false -> ok
+	  end,
+	  {NewMap3, CType} = bind_guard(cerl:clause_body(Clause), NewMap2,
+					Env, Eval, State),
+          Opaques = State#state.opaques,
+	  case Eval of
+	    pos ->
+	      case t_is_any_atom(true, CType, Opaques) of
+		true -> ok;
+		false -> throw({fail, none})
+	      end;
+	    neg ->
+	      case t_is_any_atom(false, CType, Opaques) of
+		true -> ok;
+		false -> throw({fail, none})
+	      end;
+	    dont_know ->
+	      ok
+	  end,
+	  {t_sup(AccType, CType), [NewMap3|AccMaps]}
+	catch
+	  throw:{fail, _What} -> {AccType, AccMaps}
+	end,
+      bind_guard_case_clauses(NewGenArgType, GenMap, ArgExpr, Left, Map, Env,
+			      Eval, NewAccType, NewAccMaps, State)
+  end;
+bind_guard_case_clauses(_GenArgType, _GenMap, _ArgExpr, [], Map, _Env, _Eval,
+			AccType, AccMaps, _State) ->
+  case t_is_none(AccType) of
+    true -> throw({fail, none});
+    false -> {join_maps_end(AccMaps, Map), AccType}
+  end.
+
+%%% ===========================================================================
+%%%
+%%%  Maps and types.
+%%%
+%%% ===========================================================================
+
+map__new() ->
+  #map{}.
+
+%% join_maps_begin pushes 'modified' to the stack; join_maps pops
+%% 'modified' from the stack.
+
+join_maps_begin(#map{modified = M, modified_stack = S, ref = Ref} = Map) ->
+  Map#map{ref = make_ref(), modified = [], modified_stack = [{M,Ref} | S]}.
+
+join_maps_end(Maps, MapOut) ->
+  #map{ref = Ref, modified_stack = [{M1,R1} | S]} = MapOut,
+  true = lists:all(fun(M) -> M#map.ref =:= Ref end, Maps), % sanity
+  Keys0 = lists:usort(lists:append([M#map.modified || M <- Maps])),
+  #map{map = Map, subst = Subst} = MapOut,
+  Keys = [Key ||
+           Key <- Keys0,
+           maps:is_key(Key, Map) orelse maps:is_key(Key, Subst)],
+  Out = case Maps of
+          [] -> join_maps(Maps, MapOut);
+          _ -> join_maps(Keys, Maps, MapOut)
+        end,
+  debug_join_check(Maps, MapOut, Out),
+  Out#map{ref = R1,
+          modified = Out#map.modified ++ M1, % duplicates possible
+          modified_stack = S}.
+
+join_maps(Maps, MapOut) ->
+  #map{map = Map, subst = Subst} = MapOut,
+  Keys = ordsets:from_list(maps:keys(Map) ++ maps:keys(Subst)),
+  join_maps(Keys, Maps, MapOut).
+
+join_maps(Keys, Maps, MapOut) ->
+  KTs = join_maps_collect(Keys, Maps, MapOut),
+  lists:foldl(fun({K, T}, M) -> enter_type(K, T, M) end, MapOut, KTs).
+
+join_maps_collect([Key|Left], Maps, MapOut) ->
+  Type = join_maps_one_key(Maps, Key, t_none()),
+  case t_is_equal(lookup_type(Key, MapOut), Type) of
+    true ->  join_maps_collect(Left, Maps, MapOut);
+    false -> [{Key, Type} | join_maps_collect(Left, Maps, MapOut)]
+  end;
+join_maps_collect([], _Maps, _MapOut) ->
+  [].
+
+join_maps_one_key([Map|Left], Key, AccType) ->
+  case t_is_any(AccType) of
+    true ->
+      %% We can stop here
+      AccType;
+    false ->
+      join_maps_one_key(Left, Key, t_sup(lookup_type(Key, Map), AccType))
+  end;
+join_maps_one_key([], _Key, AccType) ->
+  AccType.
+
+-ifdef(DEBUG).
+debug_join_check(Maps, MapOut, Out) ->
+  #map{map = Map, subst = Subst} = Out,
+  #map{map = Map2, subst = Subst2} = join_maps(Maps, MapOut),
+  F = fun(D) -> lists:keysort(1, maps:to_list(D)) end,
+  [throw({bug, join_maps}) ||
+    F(Map) =/= F(Map2) orelse F(Subst) =/= F(Subst2)].
+-else.
+debug_join_check(_Maps, _MapOut, _Out) -> ok.
+-endif.
+
+enter_type_lists([Key|KeyTail], [Val|ValTail], Map) ->
+  Map1 = enter_type(Key, Val, Map),
+  enter_type_lists(KeyTail, ValTail, Map1);
+enter_type_lists([], [], Map) ->
+  Map.
+
+enter_type_list([{Key, Val}|Left], Map) ->
+  Map1 = enter_type(Key, Val, Map),
+  enter_type_list(Left, Map1);
+enter_type_list([], Map) ->
+  Map.
+
+enter_type(Key, Val, MS) ->
+  case cerl:is_literal(Key) of
+    true -> MS;
+    false ->
+      case cerl:is_c_values(Key) of
+	true ->
+          Keys = cerl:values_es(Key),
+	  case t_is_any(Val) orelse t_is_none(Val) of
+	    true ->
+	      enter_type_lists(Keys, [Val || _ <- Keys], MS);
+	    false ->
+	      enter_type_lists(Keys, t_to_tlist(Val), MS)
+	  end;
+	false ->
+          #map{map = Map, subst = Subst} = MS,
+	  KeyLabel = get_label(Key),
+	  case maps:find(KeyLabel, Subst) of
+	    {ok, NewKey} ->
+	      ?debug("Binding ~p to ~p\n", [KeyLabel, NewKey]),
+	      enter_type(NewKey, Val, MS);
+	    error ->
+	      ?debug("Entering ~p :: ~s\n", [KeyLabel, t_to_string(Val)]),
+	      case maps:find(KeyLabel, Map) of
+		{ok, Value} ->
+                  case erl_types:t_is_equal(Val, Value) of
+                    true -> MS;
+                    false -> store_map(KeyLabel, Val, MS)
+                  end;
+		error -> store_map(KeyLabel, Val, MS)
+	      end
+	  end
+      end
+  end.
+
+store_map(Key, Val, #map{map = Map, ref = undefined} = MapRec) ->
+  MapRec#map{map = maps:put(Key, Val, Map)};
+store_map(Key, Val, #map{map = Map, modified = Mod} = MapRec) ->
+  MapRec#map{map = maps:put(Key, Val, Map), modified = [Key | Mod]}.
+
+enter_subst(Key, Val0, #map{subst = Subst} = MS) ->
+  KeyLabel = get_label(Key),
+  Val = dialyzer_utils:refold_pattern(Val0),
+  case cerl:is_literal(Val) of
+    true ->
+      store_map(KeyLabel, literal_type(Val), MS);
+    false ->
+      case cerl:is_c_var(Val) of
+	false -> MS;
+	true ->
+	  ValLabel = get_label(Val),
+	  case maps:find(ValLabel, Subst) of
+	    {ok, NewVal} ->
+	      enter_subst(Key, NewVal, MS);
+	    error ->
+	      if KeyLabel =:= ValLabel -> MS;
+		 true ->
+		  ?debug("Subst: storing ~p = ~p\n", [KeyLabel, ValLabel]),
+                  store_subst(KeyLabel, ValLabel, MS)
+	      end
+	  end
+      end
+  end.
+
+store_subst(Key, Val, #map{subst = S, ref = undefined} = Map) ->
+  Map#map{subst = maps:put(Key, Val, S)};
+store_subst(Key, Val, #map{subst = S, modified = Mod} = Map) ->
+  Map#map{subst = maps:put(Key, Val, S), modified = [Key | Mod]}.
+
+lookup_type(Key, #map{map = Map, subst = Subst}) ->
+  lookup(Key, Map, Subst, t_none()).
+
+lookup(Key, Map, Subst, AnyNone) ->
+  case cerl:is_literal(Key) of
+    true -> literal_type(Key);
+    false ->
+      Label = get_label(Key),
+      case maps:find(Label, Subst) of
+	{ok, NewKey} -> lookup(NewKey, Map, Subst, AnyNone);
+	error ->
+	  case maps:find(Label, Map) of
+	    {ok, Val} -> Val;
+	    error -> AnyNone
+	  end
+      end
+  end.
+
+lookup_fun_sig(Fun, Callgraph, Plt) ->
+  MFAorLabel =
+    case dialyzer_callgraph:lookup_name(Fun, Callgraph) of
+      error -> Fun;
+      {ok, MFA} -> MFA
+    end,
+  dialyzer_plt:lookup(Plt, MFAorLabel).
+
+literal_type(Lit) ->
+  t_from_term(cerl:concrete(Lit)).
+
+mark_as_fresh([Tree|Left], Map) ->
+  SubTrees1 = lists:append(cerl:subtrees(Tree)),
+  {SubTrees2, Map1} =
+    case cerl:type(Tree) of
+      bitstr ->
+	%% The Size field is not fresh.
+	{SubTrees1 -- [cerl:bitstr_size(Tree)], Map};
+      map_pair ->
+	%% The keys are not fresh
+	{SubTrees1 -- [cerl:map_pair_key(Tree)], Map};
+      var ->
+	{SubTrees1, enter_type(Tree, t_any(), Map)};
+      _ ->
+	{SubTrees1, Map}
+    end,
+  mark_as_fresh(SubTrees2 ++ Left, Map1);
+mark_as_fresh([], Map) ->
+  Map.
+
+-ifdef(DEBUG).
+debug_pp_map(#map{map = Map}=MapRec) ->
+  Keys = maps:keys(Map),
+  io:format("Map:\n", []),
+  lists:foreach(fun (Key) ->
+		    io:format("\t~w :: ~s\n",
+			      [Key, t_to_string(lookup_type(Key, MapRec))])
+		end, Keys),
+  ok.
+-else.
+debug_pp_map(_Map) -> ok.
+-endif.
+
+%%% ===========================================================================
+%%%
+%%%  Utilities
+%%%
+%%% ===========================================================================
+
+get_label(L) when is_integer(L) ->
+  L;
+get_label(T) ->
+  cerl_trees:get_label(T).
+
+t_is_simple(ArgType, State) ->
+  Opaques = State#state.opaques,
+  t_is_atom(ArgType, Opaques) orelse t_is_number(ArgType, Opaques)
+    orelse t_is_port(ArgType, Opaques)
+    orelse t_is_pid(ArgType, Opaques) orelse t_is_reference(ArgType, Opaques)
+    orelse t_is_nil(ArgType, Opaques).
+
+remove_local_opaque_types(Type, Opaques) ->
+  t_unopaque(Type, Opaques).
+
+%% t_is_structured(ArgType) ->
+%%   case t_is_nil(ArgType) of
+%%     true -> false;
+%%     false ->
+%%       SType = t_inf(t_sup([t_list(), t_tuple(), t_binary()]), ArgType),
+%%       t_is_equal(ArgType, SType)
+%%   end.
+
+is_call_to_send(Tree) ->
+  case cerl:is_c_call(Tree) of
+    false -> false;
+    true ->
+      Mod = cerl:call_module(Tree),
+      Name = cerl:call_name(Tree),
+      Arity = cerl:call_arity(Tree),
+      cerl:is_c_atom(Mod)
+	andalso cerl:is_c_atom(Name)
+        andalso is_send(cerl:atom_val(Name))
+	andalso (cerl:atom_val(Mod) =:= erlang)
+	andalso (Arity =:= 2)
+  end.
+
+is_send('!') -> true;
+is_send(send) -> true;
+is_send(_) -> false.
+
+is_lc_simple_list(Tree, TreeType, State) ->
+  Opaques = State#state.opaques,
+  Ann = cerl:get_ann(Tree),
+  lists:member(list_comprehension, Ann)
+    andalso t_is_list(TreeType)
+    andalso t_is_simple(t_list_elements(TreeType, Opaques), State).
+
+filter_match_fail([Clause] = Cls) ->
+  Body = cerl:clause_body(Clause),
+  case cerl:type(Body) of
+    primop ->
+      case cerl:atom_val(cerl:primop_name(Body)) of
+	match_fail -> [];
+	raise -> [];
+	_ -> Cls
+      end;
+    _ -> Cls
+  end;
+filter_match_fail([H|T]) ->
+  [H|filter_match_fail(T)];
+filter_match_fail([]) ->
+  %% This can actually happen, for example in
+  %%      receive after 1 -> ok end
+  [].
+
+%%% ===========================================================================
+%%%
+%%%  The State.
+%%%
+%%% ===========================================================================
+
+state__new(Callgraph, Codeserver, Tree, Plt, Module, Records) ->
+  Opaques = erl_types:t_opaque_from_records(Records),
+  {TreeMap, FunHomes} = build_tree_map(Tree, Callgraph),
+  Funs = dict:fetch_keys(TreeMap),
+  FunTab = init_fun_tab(Funs, dict:new(), TreeMap, Callgraph, Plt),
+  ExportedFuns =
+    [Fun || Fun <- Funs--[top], dialyzer_callgraph:is_escaping(Fun, Callgraph)],
+  Work = init_work(ExportedFuns),
+  Env = lists:foldl(fun(Fun, Env) -> dict:store(Fun, map__new(), Env) end,
+		    dict:new(), Funs),
+  #state{callgraph = Callgraph, codeserver = Codeserver,
+         envs = Env, fun_tab = FunTab, fun_homes = FunHomes, opaques = Opaques,
+	 plt = Plt, races = dialyzer_races:new(), records = Records,
+	 warning_mode = false, warnings = [], work = Work, tree_map = TreeMap,
+	 module = Module}.
+
+state__warning_mode(#state{warning_mode = WM}) ->
+  WM.
+
+state__set_warning_mode(#state{tree_map = TreeMap, fun_tab = FunTab,
+                               races = Races} = State) ->
+  ?debug("==========\nStarting warning pass\n==========\n", []),
+  Funs = dict:fetch_keys(TreeMap),
+  State#state{work = init_work([top|Funs--[top]]),
+	      fun_tab = FunTab, warning_mode = true,
+              races = dialyzer_races:put_race_analysis(true, Races)}.
+
+state__race_analysis(Analysis, #state{races = Races} = State) ->
+  State#state{races = dialyzer_races:put_race_analysis(Analysis, Races)}.
+
+state__renew_curr_fun(CurrFun, CurrFunLabel,
+                      #state{races = Races} = State) ->
+  State#state{races = dialyzer_races:put_curr_fun(CurrFun, CurrFunLabel,
+                                                  Races)}.
+
+state__renew_fun_args(Args, #state{races = Races} = State) ->
+  case state__warning_mode(State) of
+    true -> State;
+    false ->
+      State#state{races = dialyzer_races:put_fun_args(Args, Races)}
+  end.
+
+state__renew_race_list(RaceList, RaceListSize,
+                       #state{races = Races} = State) ->
+  State#state{races = dialyzer_races:put_race_list(RaceList, RaceListSize,
+                                                   Races)}.
+
+state__renew_warnings(Warnings, State) ->
+  State#state{warnings = Warnings}.
+
+-spec state__add_warning(raw_warning(), state()) -> state().
+
+state__add_warning(Warn, #state{warnings = Warnings} = State) ->
+  State#state{warnings = [Warn|Warnings]}.
+
+state__add_warning(State, Tag, Tree, Msg) ->
+  state__add_warning(State, Tag, Tree, Msg, false).
+
+state__add_warning(#state{warning_mode = false} = State, _, _, _, _) ->
+  State;
+state__add_warning(#state{warnings = Warnings, warning_mode = true} = State,
+		   Tag, Tree, Msg, Force) ->
+  Ann = cerl:get_ann(Tree),
+  case Force of
+    true ->
+      WarningInfo = {get_file(Ann),
+                     abs(get_line(Ann)),
+                     State#state.curr_fun},
+      Warn = {Tag, WarningInfo, Msg},
+      ?debug("MSG ~s\n", [dialyzer:format_warning(Warn)]),
+      State#state{warnings = [Warn|Warnings]};
+    false ->
+      case is_compiler_generated(Ann) of
+        true -> State;
+        false ->
+          WarningInfo = {get_file(Ann), get_line(Ann), State#state.curr_fun},
+          Warn = {Tag, WarningInfo, Msg},
+          case Tag of
+            ?WARN_CONTRACT_RANGE -> ok;
+            _ -> ?debug("MSG ~s\n", [dialyzer:format_warning(Warn)])
+          end,
+          State#state{warnings = [Warn|Warnings]}
+      end
+  end.
+
+state__remove_added_warnings(OldState, NewState) ->
+  #state{warnings = OldWarnings} = OldState,
+  #state{warnings = NewWarnings} = NewState,
+  {NewWarnings -- OldWarnings, NewState#state{warnings = OldWarnings}}.
+
+state__add_warnings(Warns, #state{warnings = Warnings} = State) ->
+  State#state{warnings = Warns ++ Warnings}.
+
+-spec state__set_curr_fun(curr_fun(), state()) -> state().
+
+state__set_curr_fun(undefined, State) ->
+  State#state{curr_fun = undefined};
+state__set_curr_fun(FunLbl, State) ->
+  State#state{curr_fun = find_function(FunLbl, State)}.
+
+-spec state__find_function(mfa_or_funlbl(), state()) -> mfa_or_funlbl().
+
+state__find_function(FunLbl, State) ->
+  find_function(FunLbl, State).
+
+state__get_race_warnings(#state{races = Races} = State) ->
+  {Races1, State1} = dialyzer_races:get_race_warnings(Races, State),
+  State1#state{races = Races1}.
+
+state__get_warnings(#state{tree_map = TreeMap, fun_tab = FunTab,
+			   callgraph = Callgraph, plt = Plt} = State) ->
+  FoldFun =
+    fun({top, _}, AccState) -> AccState;
+       ({FunLbl, Fun}, AccState) ->
+        AccState1 = state__set_curr_fun(FunLbl, AccState),
+	{NotCalled, Ret} =
+	  case dict:fetch(get_label(Fun), FunTab) of
+	    {not_handled, {_Args0, Ret0}} -> {true, Ret0};
+	    {_Args0, Ret0} -> {false, Ret0}
+	  end,
+	case NotCalled of
+	  true ->
+            case dialyzer_callgraph:lookup_name(FunLbl, Callgraph) of
+              error -> AccState1;
+              {ok, {_M, F, A}} ->
+                Msg = {unused_fun, [F, A]},
+                state__add_warning(AccState1, ?WARN_NOT_CALLED, Fun, Msg)
+            end;
+	  false ->
+	    {Name, Contract} =
+	      case dialyzer_callgraph:lookup_name(FunLbl, Callgraph) of
+		error -> {[], none};
+		{ok, {_M, F, A} = MFA} ->
+		  {[F, A], dialyzer_plt:lookup_contract(Plt, MFA)}
+	      end,
+	    case t_is_none(Ret) of
+	      true ->
+		%% Check if the function has a contract that allows this.
+		Warn =
+		  case Contract of
+		    none -> not parent_allows_this(FunLbl, AccState1);
+		    {value, C} ->
+		      GenRet = dialyzer_contracts:get_contract_return(C),
+		      not t_is_unit(GenRet)
+		  end,
+		case Warn of
+		  true ->
+		    case classify_returns(Fun) of
+		      no_match ->
+			Msg = {no_return, [no_match|Name]},
+			state__add_warning(AccState1, ?WARN_RETURN_NO_RETURN,
+					   Fun, Msg);
+		      only_explicit ->
+			Msg = {no_return, [only_explicit|Name]},
+			state__add_warning(AccState1, ?WARN_RETURN_ONLY_EXIT,
+					   Fun, Msg);
+		      only_normal ->
+			Msg = {no_return, [only_normal|Name]},
+			state__add_warning(AccState1, ?WARN_RETURN_NO_RETURN,
+					   Fun, Msg);
+		      both ->
+			Msg = {no_return, [both|Name]},
+			state__add_warning(AccState1, ?WARN_RETURN_NO_RETURN,
+					   Fun, Msg)
+		    end;
+		  false ->
+		    AccState
+		end;
+	      false ->
+		AccState
+	    end
+	end
+    end,
+  #state{warnings = Warn} = lists:foldl(FoldFun, State, dict:to_list(TreeMap)),
+  Warn.
+
+state__is_escaping(Fun, #state{callgraph = Callgraph}) ->
+  dialyzer_callgraph:is_escaping(Fun, Callgraph).
+
+state__lookup_type_for_letrec(Var, #state{callgraph = Callgraph} = State) ->
+  Label = get_label(Var),
+  case dialyzer_callgraph:lookup_letrec(Label, Callgraph) of
+    error -> error;
+    {ok, FunLabel} ->
+      {ok, state__fun_type(FunLabel, State)}
+  end.
+
+state__lookup_name({_, _, _} = MFA, #state{}) ->
+  MFA;
+state__lookup_name(top, #state{}) ->
+  top;
+state__lookup_name(Fun, #state{callgraph = Callgraph}) ->
+  case dialyzer_callgraph:lookup_name(Fun, Callgraph) of
+    {ok, MFA} -> MFA;
+    error -> Fun
+  end.
+
+state__lookup_record(Tag, Arity, #state{records = Records}) ->
+  case erl_types:lookup_record(Tag, Arity, Records) of
+    {ok, Fields} ->
+      RecType =
+        t_tuple([t_atom(Tag)|
+                 [FieldType || {_FieldName, _Abstr, FieldType} <- Fields]]),
+      {ok, RecType};
+    error ->
+      error
+  end.
+
+state__get_args_and_status(Tree, #state{fun_tab = FunTab}) ->
+  Fun = get_label(Tree),
+  case dict:find(Fun, FunTab) of
+    {ok, {not_handled, {ArgTypes, _}}} -> {ArgTypes, false};
+    {ok, {ArgTypes, _}} -> {ArgTypes, true}
+  end.
+
+build_tree_map(Tree, Callgraph) ->
+  Fun =
+    fun(T, {Dict, Homes, FunLbls} = Acc) ->
+	case cerl:is_c_fun(T) of
+	  true ->
+            FunLbl = get_label(T),
+	    Dict1 = dict:store(FunLbl, T, Dict),
+            case catch dialyzer_callgraph:lookup_name(FunLbl, Callgraph) of
+              {ok, MFA} ->
+                F2 =
+                  fun(Lbl, Dict0) ->
+                      dict:store(Lbl, MFA, Dict0)
+                  end,
+                Homes1 = lists:foldl(F2, Homes, [FunLbl|FunLbls]),
+                {Dict1, Homes1, []};
+              _ ->
+                {Dict1, Homes, [FunLbl|FunLbls]}
+            end;
+	  false ->
+            Acc
+	end
+    end,
+  Dict0 = dict:new(),
+  {Dict, Homes, _} = cerl_trees:fold(Fun, {Dict0, Dict0, []}, Tree),
+  {Dict, Homes}.
+
+init_fun_tab([top|Left], Dict, TreeMap, Callgraph, Plt) ->
+  NewDict = dict:store(top, {[], t_none()}, Dict),
+  init_fun_tab(Left, NewDict, TreeMap, Callgraph, Plt);
+init_fun_tab([Fun|Left], Dict, TreeMap, Callgraph, Plt) ->
+  Arity = cerl:fun_arity(dict:fetch(Fun, TreeMap)),
+  FunEntry =
+    case dialyzer_callgraph:is_escaping(Fun, Callgraph) of
+      true ->
+        Args = lists:duplicate(Arity, t_any()),
+	case lookup_fun_sig(Fun, Callgraph, Plt) of
+	  none -> {Args, t_unit()};
+	  {value, {RetType, _}} ->
+	    case t_is_none(RetType) of
+	      true -> {Args, t_none()};
+	      false -> {Args, t_unit()}
+	    end
+	end;
+      false -> {not_handled, {lists:duplicate(Arity, t_none()), t_unit()}}
+    end,
+  NewDict = dict:store(Fun, FunEntry, Dict),
+  init_fun_tab(Left, NewDict, TreeMap, Callgraph, Plt);
+init_fun_tab([], Dict, _TreeMap, _Callgraph, _Plt) ->
+  ?debug("DICT:~p\n",[dict:to_list(Dict)]),
+  Dict.
+
+state__update_fun_env(Tree, Map, #state{envs = Envs} = State) ->
+  NewEnvs = dict:store(get_label(Tree), Map, Envs),
+  State#state{envs = NewEnvs}.
+
+state__fun_env(Tree, #state{envs = Envs}) ->
+  Fun = get_label(Tree),
+  case dict:find(Fun, Envs) of
+    error -> none;
+    {ok, Map} -> Map
+  end.
+
+state__clean_not_called(#state{fun_tab = FunTab} = State) ->
+  NewFunTab =
+    dict:map(fun(top, Entry) -> Entry;
+		(_Fun, {not_handled, {Args, _}}) -> {Args, t_none()};
+		(_Fun, Entry) -> Entry
+	     end, FunTab),
+  State#state{fun_tab = NewFunTab}.
+
+state__all_fun_types(State) ->
+  #state{fun_tab = FunTab} = state__clean_not_called(State),
+  Tab1 = dict:erase(top, FunTab),
+  dict:map(fun(_Fun, {Args, Ret}) -> t_fun(Args, Ret)end, Tab1).
+
+state__fun_type(Fun, #state{fun_tab = FunTab}) ->
+  Label =
+    if is_integer(Fun) -> Fun;
+       true -> get_label(Fun)
+    end,
+  Entry = dict:find(Label, FunTab),
+  ?debug("FunType ~p:~p\n",[Label, Entry]),
+  case Entry of
+    {ok, {not_handled, {A, R}}} ->
+      t_fun(A, R);
+    {ok, {A, R}} ->
+      t_fun(A, R)
+  end.
+
+state__update_fun_entry(Tree, ArgTypes, Out0,
+			#state{fun_tab=FunTab, callgraph=CG, plt=Plt} = State)->
+  Fun = get_label(Tree),
+  Out1 =
+    if Fun =:= top -> Out0;
+       true ->
+	case lookup_fun_sig(Fun, CG, Plt) of
+	  {value, {SigRet, _}} -> t_inf(SigRet, Out0);
+	  none -> Out0
+	end
+    end,
+  Out = t_limit(Out1, ?TYPE_LIMIT),
+  {ok, {OldArgTypes, OldOut}} = dict:find(Fun, FunTab),
+  SameArgs = lists:all(fun({A, B}) -> erl_types:t_is_equal(A, B)
+                       end, lists:zip(OldArgTypes, ArgTypes)),
+  SameOut = t_is_equal(OldOut, Out),
+  if
+    SameArgs, SameOut ->
+      ?debug("Fixpoint for ~w: ~s\n",
+	     [state__lookup_name(Fun, State),
+	      t_to_string(t_fun(ArgTypes, Out))]),
+      State;
+    true ->
+      %% Can only happen in self-recursive functions.
+      NewEntry = {OldArgTypes, Out},
+      ?debug("New Entry for ~w: ~s\n",
+	     [state__lookup_name(Fun, State),
+	      t_to_string(t_fun(OldArgTypes, Out))]),
+      NewFunTab = dict:store(Fun, NewEntry, FunTab),
+      State1 = State#state{fun_tab = NewFunTab},
+      state__add_work_from_fun(Tree, State1)
+  end.
+
+state__add_work_from_fun(_Tree, #state{warning_mode = true} = State) ->
+  State;
+state__add_work_from_fun(Tree, #state{callgraph = Callgraph,
+				      tree_map = TreeMap} = State) ->
+  case get_label(Tree) of
+    top -> State;
+    Label when is_integer(Label) ->
+      case dialyzer_callgraph:in_neighbours(Label, Callgraph) of
+	none -> State;
+	MFAList ->
+	  LabelList = [dialyzer_callgraph:lookup_label(MFA, Callgraph)
+		       || MFA <- MFAList],
+	  %% Must filter the result for results in this module.
+	  FilteredList = [L || {ok, L} <- LabelList, dict:is_key(L, TreeMap)],
+	  ?debug("~w: Will try to add:~w\n",
+		 [state__lookup_name(Label, State), MFAList]),
+	  lists:foldl(fun(L, AccState) ->
+			  state__add_work(L, AccState)
+		      end, State, FilteredList)
+      end
+  end.
+
+state__add_work(external, State) ->
+  State;
+state__add_work(top, State) ->
+  State;
+state__add_work(Fun, #state{work = Work} = State) ->
+  NewWork = add_work(Fun, Work),
+  State#state{work = NewWork}.
+
+state__get_work(#state{work = Work, tree_map = TreeMap} = State) ->
+  case get_work(Work) of
+    none -> none;
+    {Fun, NewWork} ->
+      {dict:fetch(Fun, TreeMap), State#state{work = NewWork}}
+  end.
+
+state__lookup_call_site(Tree, #state{callgraph = Callgraph}) ->
+  Label = get_label(Tree),
+  dialyzer_callgraph:lookup_call_site(Label, Callgraph).
+
+state__fun_info(external, #state{}) ->
+  external;
+state__fun_info({_, _, _} = MFA, #state{plt = PLT}) ->
+  {MFA,
+   dialyzer_plt:lookup(PLT, MFA),
+   dialyzer_plt:lookup_contract(PLT, MFA),
+   t_any()};
+state__fun_info(Fun, #state{callgraph = CG, fun_tab = FunTab, plt = PLT}) ->
+  {Sig, Contract} =
+    case dialyzer_callgraph:lookup_name(Fun, CG) of
+      error ->
+	{dialyzer_plt:lookup(PLT, Fun), none};
+      {ok, MFA} ->
+	{dialyzer_plt:lookup(PLT, MFA), dialyzer_plt:lookup_contract(PLT, MFA)}
+    end,
+  LocalRet =
+    case dict:fetch(Fun, FunTab) of
+      {not_handled, {_Args, Ret}} -> Ret;
+      {_Args, Ret} -> Ret
+    end,
+  ?debug("LocalRet: ~s\n", [t_to_string(LocalRet)]),
+  {Fun, Sig, Contract, LocalRet}.
+
+forward_args(Fun, ArgTypes, #state{work = Work, fun_tab = FunTab} = State) ->
+  {OldArgTypes, OldOut, Fixpoint} =
+    case dict:find(Fun, FunTab) of
+      {ok, {not_handled, {OldArgTypes0, OldOut0}}} ->
+	{OldArgTypes0, OldOut0, false};
+      {ok, {OldArgTypes0, OldOut0}} ->
+	{OldArgTypes0, OldOut0,
+	 t_is_subtype(t_product(ArgTypes), t_product(OldArgTypes0))}
+    end,
+  case Fixpoint of
+    true -> State;
+    false ->
+      NewArgTypes = [t_sup(X, Y) ||
+                      {X, Y} <- lists:zip(ArgTypes, OldArgTypes)],
+      NewWork = add_work(Fun, Work),
+      ?debug("~w: forwarding args ~s\n",
+	     [state__lookup_name(Fun, State),
+	      t_to_string(t_product(NewArgTypes))]),
+      NewFunTab = dict:store(Fun, {NewArgTypes, OldOut}, FunTab),
+      State#state{work = NewWork, fun_tab = NewFunTab}
+  end.
+
+-spec state__cleanup(state()) -> state().
+
+state__cleanup(#state{callgraph = Callgraph,
+                      races = Races,
+                      records = Records}) ->
+  #state{callgraph = dialyzer_callgraph:cleanup(Callgraph),
+         races = dialyzer_races:cleanup(Races),
+         records = Records}.
+
+-spec state__duplicate(state()) -> state().
+
+state__duplicate(#state{callgraph = Callgraph} = State) ->
+  State#state{callgraph = dialyzer_callgraph:duplicate(Callgraph)}.
+
+-spec dispose_state(state()) -> ok.
+
+dispose_state(#state{callgraph = Callgraph}) ->
+  dialyzer_callgraph:dispose_race_server(Callgraph).
+
+-spec state__get_callgraph(state()) -> dialyzer_callgraph:callgraph().
+
+state__get_callgraph(#state{callgraph = Callgraph}) ->
+  Callgraph.
+
+-spec state__get_races(state()) -> dialyzer_races:races().
+
+state__get_races(#state{races = Races}) ->
+  Races.
+
+-spec state__get_records(state()) -> types().
+
+state__get_records(#state{records = Records}) ->
+  Records.
+
+-spec state__put_callgraph(dialyzer_callgraph:callgraph(), state()) ->
+  state().
+
+state__put_callgraph(Callgraph, State) ->
+  State#state{callgraph = Callgraph}.
+
+-spec state__put_races(dialyzer_races:races(), state()) -> state().
+
+state__put_races(Races, State) ->
+  State#state{races = Races}.
+
+-spec state__records_only(state()) -> state().
+
+state__records_only(#state{records = Records}) ->
+  #state{records = Records}.
+
+%%% ===========================================================================
+%%%
+%%%  Races
+%%%
+%%% ===========================================================================
+
+is_race_analysis_enabled(#state{races = Races, callgraph = Callgraph}) ->
+  RaceDetection = dialyzer_callgraph:get_race_detection(Callgraph),
+  RaceAnalysis = dialyzer_races:get_race_analysis(Races),
+  RaceDetection andalso RaceAnalysis.
+
+get_race_list_and_size(#state{races = Races}) ->
+  dialyzer_races:get_race_list_and_size(Races).
+
+renew_race_code(#state{races = Races, callgraph = Callgraph,
+		       warning_mode = WarningMode} = State) ->
+  case WarningMode of
+    true -> State;
+    false ->
+      NewCallgraph = dialyzer_callgraph:renew_race_code(Races, Callgraph),
+      State#state{callgraph = NewCallgraph}
+  end.
+
+renew_race_public_tables([Var], #state{races = Races, callgraph = Callgraph,
+				      warning_mode = WarningMode} = State) ->
+  case WarningMode of
+    true -> State;
+    false ->
+      Table = dialyzer_races:get_new_table(Races),
+      case Table of
+	no_t -> State;
+	_Other ->
+	  VarLabel = get_label(Var),
+	  NewCallgraph =
+	    dialyzer_callgraph:renew_race_public_tables(VarLabel, Callgraph),
+	  State#state{callgraph = NewCallgraph}
+      end
+  end.
+
+%%% ===========================================================================
+%%%
+%%%  Worklist
+%%%
+%%% ===========================================================================
+
+init_work(List) ->
+  {List, [], sets:from_list(List)}.
+
+get_work({[], [], _Set}) ->
+  none;
+get_work({[H|T], Rev, Set}) ->
+  {H, {T, Rev, sets:del_element(H, Set)}};
+get_work({[], Rev, Set}) ->
+  get_work({lists:reverse(Rev), [], Set}).
+
+add_work(New, {List, Rev, Set} = Work) ->
+  case sets:is_element(New, Set) of
+    true -> Work;
+    false -> {List, [New|Rev], sets:add_element(New, Set)}
+  end.
+
+%%% ===========================================================================
+%%%
+%%%  Utilities.
+%%%
+%%% ===========================================================================
+
+get_line([Line|_]) when is_integer(Line) -> Line;
+get_line([_|Tail]) -> get_line(Tail);
+get_line([]) -> -1.
+
+get_file([]) -> [];
+get_file([{file, File}|_]) -> File;
+get_file([_|Tail]) -> get_file(Tail).
+
+is_compiler_generated(Ann) ->
+  lists:member(compiler_generated, Ann) orelse (get_line(Ann) < 1).
+
+is_literal_record(Tree) ->
+  Ann = cerl:get_ann(Tree),
+  lists:member(record, Ann).
+
+-spec format_args([cerl:cerl()], [type()], state()) ->
+  nonempty_string().
+
+format_args([], [], _State) ->
+  "()";
+format_args(ArgList0, TypeList, State) ->
+  ArgList = fold_literals(ArgList0),
+  "(" ++ format_args_1(ArgList, TypeList, State) ++ ")".
+
+format_args_1([Arg], [Type], State) ->
+  format_arg(Arg) ++ format_type(Type, State);
+format_args_1([Arg|Args], [Type|Types], State) ->
+  String =
+    case cerl:is_literal(Arg) of
+      true -> format_cerl(Arg);
+      false -> format_arg(Arg) ++ format_type(Type, State)
+    end,
+  String ++ "," ++ format_args_1(Args, Types, State).
+
+format_arg(Arg) ->
+  Default = "",
+  case cerl:is_c_var(Arg) of
+    true ->
+      case cerl:var_name(Arg) of
+	Atom when is_atom(Atom) ->
+	  case atom_to_list(Atom) of
+	    "cor"++_ -> Default;
+	    "rec"++_ -> Default;
+	    Name -> Name ++ "::"
+	  end;
+	_What -> Default
+      end;
+    false ->
+      Default
+  end.
+
+-spec format_type(type(), state()) -> string().
+
+format_type(Type, #state{records = R}) ->
+  t_to_string(Type, R).
+
+-spec format_field_diffs(type(), state()) -> string().
+
+format_field_diffs(RecConstruction, #state{records = R}) ->
+  erl_types:record_field_diffs_to_string(RecConstruction, R).
+
+-spec format_sig_args(type(), state()) -> string().
+
+format_sig_args(Type, #state{opaques = Opaques} = State) ->
+  SigArgs = t_fun_args(Type, Opaques),
+  case SigArgs of
+    [] -> "()";
+    [SArg|SArgs] ->
+      lists:flatten("(" ++ format_type(SArg, State)
+		        ++ ["," ++ format_type(T, State) || T <- SArgs] ++ ")")
+    end.
+
+format_cerl(Tree) ->
+  cerl_prettypr:format(cerl:set_ann(Tree, []),
+		       [{hook, dialyzer_utils:pp_hook()},
+			{noann, true},
+			{paper, 100000}, %% These guys strip
+			{ribbon, 100000} %% newlines.
+		       ]).
+
+format_patterns(Pats0) ->
+  Pats = fold_literals(Pats0),
+  NewPats = map_pats(cerl:c_values(Pats)),
+  String = format_cerl(NewPats),
+  case Pats of
+    [PosVar] ->
+      case cerl:is_c_var(PosVar) andalso (cerl:var_name(PosVar) =/= '') of
+	true -> "variable "++String;
+	false -> "pattern "++String
+      end;
+    _ ->
+      "pattern "++String
+  end.
+
+map_pats(Pats) ->
+  Fun = fun(Tree) ->
+	    case cerl:is_c_var(Tree) of
+	      true ->
+		case cerl:var_name(Tree) of
+		  Atom when is_atom(Atom) ->
+		    case atom_to_list(Atom) of
+		      "cor"++_ -> cerl:c_var('');
+		      "rec"++_ -> cerl:c_var('');
+		      _ -> cerl:set_ann(Tree, [])
+		    end;
+		  _What -> cerl:c_var('')
+		end;
+	      false ->
+		cerl:set_ann(Tree, [])
+	    end
+	end,
+  cerl_trees:map(Fun, Pats).
+
+fold_literals(TreeList) ->
+  [cerl:fold_literal(Tree) || Tree <- TreeList].
+
+type(Tree) ->
+  Folded = cerl:fold_literal(Tree),
+  case cerl:type(Folded) of
+    literal -> {literal, Folded};
+    Type -> Type
+  end.
+
+is_literal(Tree) ->
+  Folded = cerl:fold_literal(Tree),
+  case cerl:is_literal(Folded) of
+    true -> {yes, Folded};
+    false -> no
+  end.
+
+parent_allows_this(FunLbl, #state{callgraph = Callgraph, plt = Plt} =State) ->
+  case state__is_escaping(FunLbl, State) of
+    false -> false; % if it isn't escaping it can't be a return value
+    true ->
+      case state__lookup_name(FunLbl, State) of
+	{_M, _F, _A} -> false; % if it has a name it is not a fun
+	_ ->
+	  case dialyzer_callgraph:in_neighbours(FunLbl, Callgraph) of
+	    [Parent] ->
+	      case state__lookup_name(Parent, State) of
+		{_M, _F, _A} = PMFA ->
+		  case dialyzer_plt:lookup_contract(Plt, PMFA) of
+		    none -> false;
+		    {value, C} ->
+		      GenRet = dialyzer_contracts:get_contract_return(C),
+		      case erl_types:t_is_fun(GenRet) of
+			false -> false; % element of structure? far-fetched...
+			true -> t_is_unit(t_fun_range(GenRet))
+		      end
+		  end;
+		_ -> false % parent should have a name to have a contract
+	      end;
+	    _ -> false % called in other funs? far-fetched...
+	  end
+      end
+  end.
+
+find_function({_, _, _} = MFA, _State) ->
+  MFA;
+find_function(top, _State) ->
+  top;
+find_function(FunLbl, #state{fun_homes = Homes}) ->
+  dict:fetch(FunLbl, Homes).
+
+classify_returns(Tree) ->
+  case find_terminals(cerl:fun_body(Tree)) of
+    {false, false} -> no_match;
+    {true, false} -> only_explicit;
+    {false, true} -> only_normal;
+    {true, true} -> both
+  end.
+
+find_terminals(Tree) ->
+  case cerl:type(Tree) of
+    apply -> {false, true};
+    binary -> {false, true};
+    bitstr -> {false, true};
+    call ->
+      M0 = cerl:call_module(Tree),
+      F0 = cerl:call_name(Tree),
+      A = length(cerl:call_args(Tree)),
+      case {is_literal(M0), is_literal(F0)} of
+        {{yes, LitM}, {yes, LitF}} ->
+	  M = cerl:concrete(LitM),
+	  F = cerl:concrete(LitF),
+	  case (erl_bif_types:is_known(M, F, A)
+		andalso t_is_none(erl_bif_types:type(M, F, A))) of
+	    true -> {true, false};
+	    false -> {false, true}
+	  end;
+        _ ->
+	  %% We cannot make assumptions. Say that both are true.
+	  {true, true}
+      end;
+    'case' -> find_terminals_list(cerl:case_clauses(Tree));
+    'catch' -> find_terminals(cerl:catch_body(Tree));
+    clause -> find_terminals(cerl:clause_body(Tree));
+    cons -> {false, true};
+    'fun' -> {false, true};
+    'let' -> find_terminals(cerl:let_body(Tree));
+    letrec -> find_terminals(cerl:letrec_body(Tree));
+    literal -> {false, true};
+    map -> {false, true};
+    primop -> {false, false}; %% match_fail, etc. are not explicit exits.
+    'receive' ->
+      Timeout = cerl:receive_timeout(Tree),
+      Clauses = cerl:receive_clauses(Tree),
+      case (cerl:is_literal(Timeout) andalso
+	    (cerl:concrete(Timeout) =:= infinity)) of
+	true ->
+	  if Clauses =:= [] -> {false, true}; %% A never ending receive.
+	     true -> find_terminals_list(Clauses)
+	  end;
+	false -> find_terminals_list([cerl:receive_action(Tree)|Clauses])
+      end;
+    seq -> find_terminals(cerl:seq_body(Tree));
+    'try' ->
+      find_terminals_list([cerl:try_handler(Tree), cerl:try_body(Tree)]);
+    tuple -> {false, true};
+    values -> {false, true};
+    var -> {false, true}
+  end.
+
+find_terminals_list(List) ->
+  find_terminals_list(List, false, false).
+
+find_terminals_list([Tree|Left], Explicit1, Normal1) ->
+  {Explicit2, Normal2} = find_terminals(Tree),
+  case {Explicit1 or Explicit2, Normal1 or Normal2} of
+    {true, true} = Ans -> Ans;
+    {NewExplicit, NewNormal} ->
+      find_terminals_list(Left, NewExplicit, NewNormal)
+  end;
+find_terminals_list([], Explicit, Normal) ->
+  {Explicit, Normal}.
+
+%%----------------------------------------------------------------------------
+
+-ifdef(DEBUG_PP).
+debug_pp(Tree, true) ->
+  io:put_chars(cerl_prettypr:format(Tree, [{hook, cerl_typean:pp_hook()}])),
+  io:nl(),
+  ok;
+debug_pp(Tree, false) ->
+  io:put_chars(cerl_prettypr:format(strip_annotations(Tree))),
+  io:nl(),
+  ok.
+
+strip_annotations(Tree) ->
+  Fun = fun(T) ->
+	    case cerl:type(T) of
+	      var ->
+		cerl:set_ann(T, [{label, cerl_trees:get_label(T)}]);
+	      'fun' ->
+		cerl:set_ann(T, [{label, cerl_trees:get_label(T)}]);
+	      _ ->
+		cerl:set_ann(T, [])
+	    end
+	end,
+  cerl_trees:map(Fun, Tree).
+
+-else.
+
+debug_pp(_Tree, _UseHook) ->
+  ok.
+-endif.
diff --git a/lib/dialyzer/test/opaque_SUITE_data/src/recrec/dialyzer_races.erl b/lib/dialyzer/test/opaque_SUITE_data/src/recrec/dialyzer_races.erl
new file mode 100644
index 0000000000..bb43d1dcb8
--- /dev/null
+++ b/lib/dialyzer/test/opaque_SUITE_data/src/recrec/dialyzer_races.erl
@@ -0,0 +1,2494 @@
+%% -*- erlang-indent-level: 2 -*-
+%%-----------------------------------------------------------------------
+%% %CopyrightBegin%
+%%
+%% Copyright Ericsson AB 2008-2015. All Rights Reserved.
+%%
+%% Licensed under the Apache License, Version 2.0 (the "License");
+%% you may not use this file except in compliance with the License.
+%% You may obtain a copy of the License at
+%%
+%%     http://www.apache.org/licenses/LICENSE-2.0
+%%
+%% Unless required by applicable law or agreed to in writing, software
+%% distributed under the License is distributed on an "AS IS" BASIS,
+%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+%% See the License for the specific language governing permissions and
+%% limitations under the License.
+%%
+%% %CopyrightEnd%
+%%
+
+%%%----------------------------------------------------------------------
+%%% File    : dialyzer_races.erl
+%%% Author  : Maria Christakis <[email protected]>
+%%% Description : Utility functions for race condition detection
+%%%
+%%% Created : 21 Nov 2008 by Maria Christakis <[email protected]>
+%%%----------------------------------------------------------------------
+-module(dialyzer_races).
+
+%% Race Analysis
+
+-export([store_race_call/5, race/1, get_race_warnings/2, format_args/4]).
+
+%% Record Interfaces
+
+-export([beg_clause_new/3, cleanup/1, end_case_new/1, end_clause_new/3,
+         get_curr_fun/1, get_curr_fun_args/1, get_new_table/1,
+         get_race_analysis/1, get_race_list/1, get_race_list_size/1,
+	 get_race_list_and_size/1,
+         let_tag_new/2, new/0, put_curr_fun/3, put_fun_args/2,
+         put_race_analysis/2, put_race_list/3]).
+
+-export_type([races/0, core_vars/0]).
+
+-include("dialyzer.hrl").
+
+%%% ===========================================================================
+%%%
+%%%  Definitions
+%%%
+%%% ===========================================================================
+
+-define(local, 5).
+-define(no_arg, no_arg).
+-define(no_label, no_label).
+-define(bypassed, bypassed).
+
+-define(WARN_WHEREIS_REGISTER, warn_whereis_register).
+-define(WARN_WHEREIS_UNREGISTER, warn_whereis_unregister).
+-define(WARN_ETS_LOOKUP_INSERT, warn_ets_lookup_insert).
+-define(WARN_MNESIA_DIRTY_READ_WRITE, warn_mnesia_dirty_read_write).
+-define(WARN_NO_WARN, warn_no_warn).
+
+%%% ===========================================================================
+%%%
+%%%  Local Types
+%%%
+%%% ===========================================================================
+
+-type label_type()  :: label() | [label()] | {label()} | ?no_label.
+-type args()        :: [label_type() | [string()]].
+-type core_vars()   :: cerl:cerl() | ?no_arg | ?bypassed.
+-type var_to_map1() :: core_vars() | [cerl:cerl()].
+-type var_to_map2() :: cerl:cerl() | [cerl:cerl()] | ?bypassed.
+-type core_args()   :: [core_vars()] | 'empty'.
+-type op()          :: 'bind' | 'unbind'.
+
+-type dep_calls()  :: 'whereis' | 'ets_lookup' | 'mnesia_dirty_read'.
+-type warn_calls() :: 'register' | 'unregister' | 'ets_insert'
+                    | 'mnesia_dirty_write'.
+-type call()       :: 'whereis' | 'register' | 'unregister' | 'ets_new'
+                    | 'ets_lookup' | 'ets_insert' | 'mnesia_dirty_read1'
+                    | 'mnesia_dirty_read2' | 'mnesia_dirty_write1'
+                    | 'mnesia_dirty_write2' | 'function_call'.
+-type race_tag()   :: 'whereis_register' | 'whereis_unregister'
+                    | 'ets_lookup_insert' | 'mnesia_dirty_read_write'.
+
+%% The following type is similar to the raw_warning() type but has a
+%% tag which is local to this module and is not propagated to outside
+-type dial_race_warning() :: {race_warn_tag(), warning_info(), {atom(), [term()]}}.
+-type race_warn_tag() :: ?WARN_WHEREIS_REGISTER | ?WARN_WHEREIS_UNREGISTER
+                      | ?WARN_ETS_LOOKUP_INSERT | ?WARN_MNESIA_DIRTY_READ_WRITE.
+
+-record(beg_clause, {arg        :: var_to_map1() | 'undefined',
+                     pats       :: var_to_map1() | 'undefined',
+                     guard      :: cerl:cerl() | 'undefined'}).
+-record(end_clause, {arg        :: var_to_map1() | 'undefined',
+                     pats       :: var_to_map1() | 'undefined',
+                     guard      :: cerl:cerl() | 'undefined'}).
+-record(end_case,   {clauses    :: [#end_clause{}]}).
+-record(curr_fun,   {status     :: 'in' | 'out' | 'undefined',
+                     mfa        :: dialyzer_callgraph:mfa_or_funlbl()
+                                 | 'undefined',
+                     label      :: label() | 'undefined',
+                     def_vars   :: [core_vars()] | 'undefined',
+                     arg_types  :: [erl_types:erl_type()] | 'undefined',
+                     call_vars  :: [core_vars()] | 'undefined',
+                     var_map    :: dict:dict() | 'undefined'}).
+-record(dep_call,   {call_name  :: dep_calls(),
+                     args       :: args() | 'undefined',
+                     arg_types  :: [erl_types:erl_type()],
+                     vars       :: [core_vars()],
+                     state      :: dialyzer_dataflow:state(),
+                     file_line  :: file_line(),
+                     var_map    :: dict:dict() | 'undefined'}).
+-record(fun_call,   {caller     :: dialyzer_callgraph:mfa_or_funlbl(),
+                     callee     :: dialyzer_callgraph:mfa_or_funlbl(),
+                     arg_types  :: [erl_types:erl_type()],
+                     vars       :: [core_vars()]}).
+-record(let_tag,    {var        :: var_to_map1(),
+                     arg        :: var_to_map1()}).
+-record(warn_call,  {call_name  :: warn_calls(),
+                     args       :: args(),
+                     var_map    :: dict:dict() | 'undefined'}).
+
+-type case_tags()  :: 'beg_case' | #beg_clause{} | #end_clause{} | #end_case{}.
+-type code()       :: [#dep_call{} | #fun_call{} | #warn_call{} |
+                       #curr_fun{} | #let_tag{} | case_tags() | race_tag()].
+
+-type table_var()  :: label() | ?no_label.
+-type table()      :: {'named', table_var(), [string()]} | 'other' | 'no_t'.
+
+-record(race_fun,   {mfa        :: mfa(),
+                     args       :: args(),
+                     arg_types  :: [erl_types:erl_type()],
+                     vars       :: [core_vars()],
+                     file_line  :: file_line(),
+                     index      :: non_neg_integer(),
+                     fun_mfa    :: dialyzer_callgraph:mfa_or_funlbl(),
+                     fun_label  :: label()}).
+
+-record(races, {curr_fun                :: dialyzer_callgraph:mfa_or_funlbl()
+                                         | 'undefined',
+                curr_fun_label          :: label() | 'undefined',
+                curr_fun_args = 'empty' :: core_args(),
+                new_table = 'no_t'      :: table(),
+                race_list = []          :: code(),
+                race_list_size = 0      :: non_neg_integer(),
+                race_tags = []          :: [#race_fun{}],
+                %% true for fun types and warning mode
+                race_analysis = false   :: boolean(),
+                race_warnings = []      :: [dial_race_warning()]}).
+
+%%% ===========================================================================
+%%%
+%%%  Exported Types
+%%%
+%%% ===========================================================================
+
+-opaque races() :: #races{}.
+
+%%% ===========================================================================
+%%%
+%%%  Race Analysis
+%%%
+%%% ===========================================================================
+
+-spec store_race_call(dialyzer_callgraph:mfa_or_funlbl(),
+		      [erl_types:erl_type()], [core_vars()],
+                      file_line(), dialyzer_dataflow:state()) ->
+  dialyzer_dataflow:state().
+
+store_race_call(Fun, ArgTypes, Args, FileLine, State) ->
+  Races = dialyzer_dataflow:state__get_races(State),
+  CurrFun = Races#races.curr_fun,
+  CurrFunLabel = Races#races.curr_fun_label,
+  RaceTags = Races#races.race_tags,
+  CleanState = dialyzer_dataflow:state__records_only(State),
+  {NewRaceList, NewRaceListSize, NewRaceTags, NewTable} =
+    case CurrFun of
+      {_Module, module_info, A} when A =:= 0 orelse A =:= 1 ->
+        {[], 0, RaceTags, no_t};
+      _Thing ->
+        RaceList = Races#races.race_list,
+        RaceListSize = Races#races.race_list_size,
+        case Fun of
+          {erlang, get_module_info, A} when A =:= 1 orelse A =:= 2 ->
+            {[], 0, RaceTags, no_t};
+          {erlang, register, 2} ->
+            VarArgs = format_args(Args, ArgTypes, CleanState, register),
+            RaceFun = #race_fun{mfa = Fun, args = VarArgs,
+                                arg_types = ArgTypes, vars = Args,
+                                file_line = FileLine, index = RaceListSize,
+                                fun_mfa = CurrFun, fun_label = CurrFunLabel},
+            {[#warn_call{call_name = register, args = VarArgs}|
+              RaceList], RaceListSize + 1, [RaceFun|RaceTags], no_t};
+          {erlang, unregister, 1} ->
+            VarArgs = format_args(Args, ArgTypes, CleanState, unregister),
+            RaceFun = #race_fun{mfa = Fun, args = VarArgs,
+                                arg_types = ArgTypes, vars = Args,
+                                file_line = FileLine, index = RaceListSize,
+                                fun_mfa = CurrFun, fun_label = CurrFunLabel},
+            {[#warn_call{call_name = unregister, args = VarArgs}|
+              RaceList], RaceListSize + 1, [RaceFun|RaceTags], no_t};
+	  {erlang, whereis, 1} ->
+            VarArgs = format_args(Args, ArgTypes, CleanState, whereis),
+	    {[#dep_call{call_name = whereis, args = VarArgs,
+                        arg_types = ArgTypes, vars = Args,
+                        state = CleanState, file_line = FileLine}|
+              RaceList], RaceListSize + 1, RaceTags, no_t};
+	  {ets, insert, 2} ->
+            VarArgs = format_args(Args, ArgTypes, CleanState, ets_insert),
+            RaceFun = #race_fun{mfa = Fun, args = VarArgs,
+                                arg_types = ArgTypes, vars = Args,
+                                file_line = FileLine, index = RaceListSize,
+                                fun_mfa = CurrFun, fun_label = CurrFunLabel},
+            {[#warn_call{call_name = ets_insert, args = VarArgs}|
+              RaceList], RaceListSize + 1, [RaceFun|RaceTags], no_t};
+          {ets, lookup, 2} ->
+            VarArgs = format_args(Args, ArgTypes, CleanState, ets_lookup),
+            {[#dep_call{call_name = ets_lookup, args = VarArgs,
+                        arg_types = ArgTypes, vars = Args,
+                        state = CleanState, file_line = FileLine}|
+              RaceList], RaceListSize + 1, RaceTags, no_t};
+	  {ets, new, 2} ->
+	    VarArgs = format_args(Args, ArgTypes, CleanState, ets_new),
+            [VarArgs1, VarArgs2, _, Options] = VarArgs,
+            NewTable1 =
+              case lists:member("'public'", Options) of
+                true ->
+                  case lists:member("'named_table'", Options) of
+                    true ->
+                      {named, VarArgs1, VarArgs2};
+                    false -> other
+                  end;
+                false -> no_t
+              end,
+	    {RaceList, RaceListSize, RaceTags, NewTable1};
+	  {mnesia, dirty_read, A} when A =:= 1 orelse A =:= 2 ->
+            VarArgs =
+              case A of
+                1 ->
+                  format_args(Args, ArgTypes, CleanState, mnesia_dirty_read1);
+                2 ->
+                  format_args(Args, ArgTypes, CleanState, mnesia_dirty_read2)
+              end,
+            {[#dep_call{call_name = mnesia_dirty_read, args = VarArgs,
+                        arg_types = ArgTypes, vars = Args,
+                        state = CleanState, file_line = FileLine}|RaceList],
+	     RaceListSize + 1, RaceTags, no_t};
+          {mnesia, dirty_write, A} when A =:= 1 orelse A =:= 2 ->
+            VarArgs =
+              case A of
+                1 ->
+                  format_args(Args, ArgTypes, CleanState, mnesia_dirty_write1);
+                2 ->
+                  format_args(Args, ArgTypes, CleanState, mnesia_dirty_write2)
+              end,
+            RaceFun = #race_fun{mfa = Fun, args = VarArgs,
+                                arg_types = ArgTypes, vars = Args,
+                                file_line = FileLine, index = RaceListSize,
+                                fun_mfa = CurrFun, fun_label = CurrFunLabel},
+            {[#warn_call{call_name = mnesia_dirty_write,
+			 args = VarArgs}|RaceList],
+	     RaceListSize + 1, [RaceFun|RaceTags], no_t};
+          Int when is_integer(Int) ->
+            {[#fun_call{caller = CurrFun, callee = Int, arg_types =  ArgTypes,
+                        vars = Args}|RaceList],
+	     RaceListSize + 1, RaceTags, no_t};
+          _Other ->
+            Callgraph = dialyzer_dataflow:state__get_callgraph(State),
+            case digraph:vertex(dialyzer_callgraph:get_digraph(Callgraph),
+                                Fun) of
+              {Fun, confirmed} ->
+                {[#fun_call{caller = CurrFun, callee = Fun,
+                            arg_types = ArgTypes, vars = Args}|RaceList],
+		 RaceListSize + 1, RaceTags, no_t};
+              false ->
+                {RaceList, RaceListSize, RaceTags, no_t}
+            end
+        end
+    end,
+  state__renew_info(NewRaceList, NewRaceListSize, NewRaceTags, NewTable, State).
+
+-spec race(dialyzer_dataflow:state()) -> dialyzer_dataflow:state().
+
+race(State) ->
+  Races = dialyzer_dataflow:state__get_races(State),
+  RaceTags = Races#races.race_tags,
+  RetState =
+    case RaceTags of
+      [] -> State;
+      [#race_fun{mfa = Fun,
+                 args = VarArgs, arg_types = ArgTypes,
+                 vars = Args, file_line = FileLine,
+                 index = Index, fun_mfa = CurrFun,
+                 fun_label = CurrFunLabel}|T] ->
+        Callgraph = dialyzer_dataflow:state__get_callgraph(State),
+        {ok, [_Args, Code]} =
+          dict:find(CurrFun, dialyzer_callgraph:get_race_code(Callgraph)),
+        RaceList = lists:reverse(Code),
+        RaceWarnTag =
+          case Fun of
+            {erlang, register, 2} -> ?WARN_WHEREIS_REGISTER;
+            {erlang, unregister, 1} -> ?WARN_WHEREIS_UNREGISTER;
+            {ets, insert, 2} -> ?WARN_ETS_LOOKUP_INSERT;
+            {mnesia, dirty_write, _A} -> ?WARN_MNESIA_DIRTY_READ_WRITE
+          end,
+        State1 =
+          state__renew_curr_fun(CurrFun,
+          state__renew_curr_fun_label(CurrFunLabel,
+          state__renew_race_list(lists:nthtail(length(RaceList) - Index,
+					       RaceList), State))),
+        DepList = fixup_race_list(RaceWarnTag, VarArgs, State1),
+        {State2, RaceWarn} =
+          get_race_warn(Fun, Args, ArgTypes, DepList, State),
+        {File, Line} = FileLine,
+        CurrMFA = dialyzer_dataflow:state__find_function(CurrFun, State),
+        WarningInfo = {File, Line, CurrMFA},
+        race(
+          state__add_race_warning(
+            state__renew_race_tags(T, State2), RaceWarn, RaceWarnTag,
+            WarningInfo))
+    end,
+  state__renew_race_tags([], RetState).
+
+fixup_race_list(RaceWarnTag, WarnVarArgs, State) ->
+  Races = dialyzer_dataflow:state__get_races(State),
+  CurrFun = Races#races.curr_fun,
+  CurrFunLabel = Races#races.curr_fun_label,
+  RaceList = Races#races.race_list,
+  Callgraph = dialyzer_dataflow:state__get_callgraph(State),
+  Digraph = dialyzer_callgraph:get_digraph(Callgraph),
+  Calls = digraph:edges(Digraph),
+  RaceTag =
+    case RaceWarnTag of
+      ?WARN_WHEREIS_REGISTER -> whereis_register;
+      ?WARN_WHEREIS_UNREGISTER -> whereis_unregister;
+      ?WARN_ETS_LOOKUP_INSERT -> ets_lookup_insert;
+      ?WARN_MNESIA_DIRTY_READ_WRITE -> mnesia_dirty_read_write
+    end,
+  NewRaceList = [RaceTag|RaceList],
+  CleanState = dialyzer_dataflow:state__cleanup(State),
+  NewState = state__renew_race_list(NewRaceList, CleanState),
+  DepList1 =
+    fixup_race_forward_pullout(CurrFun, CurrFunLabel, Calls,
+                               lists:reverse(NewRaceList), [], CurrFun,
+                               WarnVarArgs, RaceWarnTag, dict:new(),
+                               [], [], [], 2 * ?local, NewState),
+  Parents = fixup_race_backward(CurrFun, Calls, Calls, [], ?local),
+  UParents = lists:usort(Parents),
+  Filtered = filter_parents(UParents, UParents, Digraph),
+  NewParents =
+    case lists:member(CurrFun, Filtered) of
+      true -> Filtered;
+      false -> [CurrFun|Filtered]
+    end,
+  DepList2 =
+    fixup_race_list_helper(NewParents, Calls, CurrFun, WarnVarArgs,
+                           RaceWarnTag, NewState),
+  dialyzer_dataflow:dispose_state(CleanState),
+  lists:usort(cleanup_dep_calls(DepList1 ++ DepList2)).
+
+fixup_race_list_helper(Parents, Calls, CurrFun, WarnVarArgs, RaceWarnTag,
+		       State) ->
+  case Parents of
+    [] -> [];
+    [Head|Tail] ->
+      Callgraph = dialyzer_dataflow:state__get_callgraph(State),
+      Code =
+        case dict:find(Head, dialyzer_callgraph:get_race_code(Callgraph)) of
+          error -> [];
+          {ok, [_A, C]} -> C
+        end,
+      {ok, FunLabel} = dialyzer_callgraph:lookup_label(Head, Callgraph),
+      DepList1 =
+        fixup_race_forward_pullout(Head, FunLabel, Calls, Code, [], CurrFun,
+                                   WarnVarArgs, RaceWarnTag, dict:new(),
+                                   [], [], [], 2 * ?local, State),
+      DepList2 =
+        fixup_race_list_helper(Tail, Calls, CurrFun, WarnVarArgs,
+			       RaceWarnTag, State),
+      DepList1 ++ DepList2
+  end.
+
+%%% ===========================================================================
+%%%
+%%%  Forward Analysis
+%%%
+%%% ===========================================================================
+
+fixup_race_forward_pullout(CurrFun, CurrFunLabel, Calls, Code, RaceList,
+                           InitFun, WarnVarArgs, RaceWarnTag, RaceVarMap,
+                           FunDefVars, FunCallVars, FunArgTypes, NestingLevel,
+                           State) ->
+  TState = dialyzer_dataflow:state__duplicate(State),
+  {DepList, NewCurrFun, NewCurrFunLabel, NewCalls,
+   NewCode, NewRaceList, NewRaceVarMap, NewFunDefVars,
+   NewFunCallVars, NewFunArgTypes, NewNestingLevel} =
+    fixup_race_forward(CurrFun, CurrFunLabel, Calls, Code, RaceList,
+                       InitFun, WarnVarArgs, RaceWarnTag, RaceVarMap,
+                       FunDefVars, FunCallVars, FunArgTypes, NestingLevel,
+                       cleanup_race_code(TState)),
+  dialyzer_dataflow:dispose_state(TState),
+  case NewCode of
+    [] -> DepList;
+    [#fun_call{caller = NewCurrFun, callee = Call, arg_types = FunTypes,
+               vars = FunArgs}|Tail] ->
+      Callgraph = dialyzer_dataflow:state__get_callgraph(State),
+      OkCall = {ok, Call},
+      {Name, Label} =
+        case is_integer(Call) of
+          true ->
+            case dialyzer_callgraph:lookup_name(Call, Callgraph) of
+              error -> {OkCall, OkCall};
+              N -> {N, OkCall}
+            end;
+          false ->
+            {OkCall, dialyzer_callgraph:lookup_label(Call, Callgraph)}
+        end,
+      {NewCurrFun1, NewCurrFunLabel1, NewCalls1, NewCode1, NewRaceList1,
+       NewRaceVarMap1, NewFunDefVars1, NewFunCallVars1, NewFunArgTypes1,
+       NewNestingLevel1} =
+        case Label =:= error of
+          true ->
+            {NewCurrFun, NewCurrFunLabel, NewCalls, Tail, NewRaceList,
+             NewRaceVarMap, NewFunDefVars, NewFunCallVars, NewFunArgTypes,
+             NewNestingLevel};
+          false ->
+            {ok, Fun} = Name,
+            {ok, Int} = Label,
+            case dict:find(Fun, dialyzer_callgraph:get_race_code(Callgraph)) of
+              error ->
+                {NewCurrFun, NewCurrFunLabel, NewCalls, Tail, NewRaceList,
+                 NewRaceVarMap, NewFunDefVars, NewFunCallVars, NewFunArgTypes,
+                 NewNestingLevel};
+              {ok, [Args, CodeB]} ->
+                Races = dialyzer_dataflow:state__get_races(State),
+                {RetCurrFun, RetCurrFunLabel, RetCalls, RetCode,
+                 RetRaceList, RetRaceVarMap, RetFunDefVars, RetFunCallVars,
+                 RetFunArgTypes, RetNestingLevel} =
+                  fixup_race_forward_helper(NewCurrFun,
+                      NewCurrFunLabel, Fun, Int, NewCalls, NewCalls,
+                      [#curr_fun{status = out, mfa = NewCurrFun,
+                                 label = NewCurrFunLabel,
+                                 var_map = NewRaceVarMap,
+                                 def_vars = NewFunDefVars,
+                                 call_vars = NewFunCallVars,
+                                 arg_types = NewFunArgTypes}|
+                       Tail],
+                      NewRaceList, InitFun, FunArgs, FunTypes, RaceWarnTag,
+                      NewRaceVarMap, NewFunDefVars, NewFunCallVars,
+                      NewFunArgTypes, NewNestingLevel, Args, CodeB,
+                      Races#races.race_list),
+                case RetCode of
+                  [#curr_fun{}|_CodeTail] ->
+                    {NewCurrFun, NewCurrFunLabel, RetCalls, RetCode,
+                     RetRaceList, NewRaceVarMap, NewFunDefVars,
+                     NewFunCallVars, NewFunArgTypes, RetNestingLevel};
+                  _Else ->
+                    {RetCurrFun, RetCurrFunLabel, RetCalls, RetCode,
+                     RetRaceList, RetRaceVarMap, RetFunDefVars,
+                     RetFunCallVars, RetFunArgTypes, RetNestingLevel}
+                end
+            end
+        end,
+      DepList ++
+        fixup_race_forward_pullout(NewCurrFun1, NewCurrFunLabel1, NewCalls1,
+                                   NewCode1, NewRaceList1, InitFun, WarnVarArgs,
+                                   RaceWarnTag, NewRaceVarMap1, NewFunDefVars1,
+                                   NewFunCallVars1, NewFunArgTypes1,
+                                   NewNestingLevel1, State)
+  end.
+
+fixup_race_forward(CurrFun, CurrFunLabel, Calls, Code, RaceList,
+                   InitFun, WarnVarArgs, RaceWarnTag, RaceVarMap,
+                   FunDefVars, FunCallVars, FunArgTypes, NestingLevel,
+                   State) ->
+  case Code of
+    [] ->
+      {[], CurrFun, CurrFunLabel, Calls, Code, RaceList, RaceVarMap,
+       FunDefVars, FunCallVars, FunArgTypes, NestingLevel};
+    [Head|Tail] ->
+      Callgraph = dialyzer_dataflow:state__get_callgraph(State),
+      {NewRL, DepList, NewNL, Return} =
+        case Head of
+          #dep_call{call_name = whereis} ->
+            case RaceWarnTag of
+              WarnWhereis when WarnWhereis =:= ?WARN_WHEREIS_REGISTER orelse
+                               WarnWhereis =:= ?WARN_WHEREIS_UNREGISTER ->
+    	        {[Head#dep_call{var_map = RaceVarMap}|RaceList],
+                 [], NestingLevel, false};
+              _Other ->
+                {RaceList, [], NestingLevel, false}
+            end;
+          #dep_call{call_name = ets_lookup} ->
+            case RaceWarnTag of
+              ?WARN_ETS_LOOKUP_INSERT ->
+                {[Head#dep_call{var_map = RaceVarMap}|RaceList],
+                 [], NestingLevel, false};
+              _Other ->
+                {RaceList, [], NestingLevel, false}
+            end;
+          #dep_call{call_name = mnesia_dirty_read} ->
+            case RaceWarnTag of
+              ?WARN_MNESIA_DIRTY_READ_WRITE ->
+     	        {[Head#dep_call{var_map = RaceVarMap}|RaceList],
+                 [], NestingLevel, false};
+              _Other ->
+                {RaceList, [], NestingLevel, false}
+            end;
+	  #warn_call{call_name = RegCall} when RegCall =:= register orelse
+                                               RegCall =:= unregister ->
+            case RaceWarnTag of
+              WarnWhereis when WarnWhereis =:= ?WARN_WHEREIS_REGISTER orelse
+                               WarnWhereis =:= ?WARN_WHEREIS_UNREGISTER ->
+     	        {[Head#warn_call{var_map = RaceVarMap}|RaceList],
+                 [], NestingLevel, false};
+              _Other ->
+                {RaceList, [], NestingLevel, false}
+            end;
+  	  #warn_call{call_name = ets_insert} ->
+            case RaceWarnTag of
+              ?WARN_ETS_LOOKUP_INSERT ->
+                {[Head#warn_call{var_map = RaceVarMap}|RaceList],
+                 [], NestingLevel, false};
+              _Other ->
+                {RaceList, [], NestingLevel, false}
+            end;
+  	  #warn_call{call_name = mnesia_dirty_write} ->
+            case RaceWarnTag of
+              ?WARN_MNESIA_DIRTY_READ_WRITE ->
+     	        {[Head#warn_call{var_map = RaceVarMap}|RaceList],
+                 [], NestingLevel, false};
+              _Other ->
+                {RaceList, [], NestingLevel, false}
+            end;
+          #fun_call{caller = CurrFun, callee = InitFun} ->
+            {RaceList, [], NestingLevel, false};
+	  #fun_call{caller = CurrFun} ->
+            {RaceList, [], NestingLevel - 1, false};
+          beg_case ->
+            {[Head|RaceList], [], NestingLevel, false};
+          #beg_clause{} ->
+            {[#beg_clause{}|RaceList], [], NestingLevel, false};
+          #end_clause{} ->
+            {[#end_clause{}|RaceList], [], NestingLevel, false};
+          #end_case{} ->
+            {[Head|RaceList], [], NestingLevel, false};
+          #let_tag{} ->
+            {RaceList, [], NestingLevel, false};
+          #curr_fun{status = in, mfa = InitFun,
+                    label = _InitFunLabel, var_map = _NewRVM,
+                    def_vars = NewFDV, call_vars = NewFCV,
+                    arg_types = _NewFAT} ->
+            {[#curr_fun{status = out, var_map = RaceVarMap,
+                        def_vars = NewFDV, call_vars = NewFCV}|
+              RaceList], [], NestingLevel - 1, false};
+          #curr_fun{status = in, def_vars = NewFDV,
+                    call_vars = NewFCV} ->
+            {[#curr_fun{status = out, var_map = RaceVarMap,
+                        def_vars = NewFDV, call_vars = NewFCV}|
+              RaceList],
+             [], NestingLevel - 1, false};
+          #curr_fun{status = out} ->
+            {[#curr_fun{status = in, var_map = RaceVarMap}|RaceList], [],
+             NestingLevel + 1, false};
+          RaceTag ->
+            PublicTables = dialyzer_callgraph:get_public_tables(Callgraph),
+            NamedTables = dialyzer_callgraph:get_named_tables(Callgraph),
+            WarnVarArgs1 =
+              var_type_analysis(FunDefVars, FunArgTypes, WarnVarArgs,
+                                RaceWarnTag, RaceVarMap,
+                                dialyzer_dataflow:state__records_only(State)),
+            {NewDepList, IsPublic, _Return} =
+              get_deplist_paths(RaceList, WarnVarArgs1, RaceWarnTag,
+                                RaceVarMap, 0, PublicTables, NamedTables),
+            {NewHead, NewDepList1} =
+              case RaceTag of
+                whereis_register ->
+                  {[#warn_call{call_name = register, args = WarnVarArgs,
+                              var_map = RaceVarMap}],
+                   NewDepList};
+                 whereis_unregister ->
+                  {[#warn_call{call_name = unregister, args = WarnVarArgs,
+                              var_map = RaceVarMap}],
+                   NewDepList};
+                ets_lookup_insert ->
+                  NewWarnCall =
+                    [#warn_call{call_name = ets_insert, args = WarnVarArgs,
+                                var_map = RaceVarMap}],
+                  [Tab, Names, _, _] = WarnVarArgs,
+                  case IsPublic orelse
+                    compare_var_list(Tab, PublicTables, RaceVarMap)
+                    orelse
+                    length(Names -- NamedTables) < length(Names) of
+                    true ->
+                      {NewWarnCall, NewDepList};
+                    false -> {NewWarnCall, []}
+                  end;
+                mnesia_dirty_read_write ->
+                  {[#warn_call{call_name = mnesia_dirty_write,
+                               args = WarnVarArgs, var_map = RaceVarMap}],
+                   NewDepList}
+              end,
+            {NewHead ++ RaceList, NewDepList1, NestingLevel,
+             is_last_race(RaceTag, InitFun, Tail, Callgraph)}
+        end,
+      {NewCurrFun, NewCurrFunLabel, NewCode, NewRaceList, NewRaceVarMap,
+       NewFunDefVars, NewFunCallVars, NewFunArgTypes, NewNestingLevel,
+       PullOut} =
+        case Head of
+          #fun_call{caller = CurrFun} ->
+            case NewNL =:= 0 of
+              true ->
+                {CurrFun, CurrFunLabel, Tail, NewRL, RaceVarMap,
+                 FunDefVars, FunCallVars, FunArgTypes, NewNL, false};
+              false ->
+                {CurrFun, CurrFunLabel, Code, NewRL, RaceVarMap,
+                 FunDefVars, FunCallVars, FunArgTypes, NewNL, true}
+            end;
+          #beg_clause{arg = Arg, pats = Pats, guard = Guard} ->
+            {RaceVarMap1, RemoveClause} =
+              race_var_map_guard(Arg, Pats, Guard, RaceVarMap, bind),
+            case RemoveClause of
+              true ->
+                {RaceList2,
+                 #curr_fun{mfa = CurrFun2, label = CurrFunLabel2,
+                           var_map = RaceVarMap2, def_vars = FunDefVars2,
+                           call_vars = FunCallVars2, arg_types = FunArgTypes2},
+                 Code2, NestingLevel2} =
+                  remove_clause(NewRL,
+                                #curr_fun{mfa = CurrFun, label = CurrFunLabel,
+                                          var_map = RaceVarMap1,
+                                          def_vars = FunDefVars,
+                                          call_vars = FunCallVars,
+                                          arg_types = FunArgTypes},
+                                Tail, NewNL),
+                {CurrFun2, CurrFunLabel2, Code2, RaceList2,
+                 RaceVarMap2, FunDefVars2, FunCallVars2, FunArgTypes2,
+                 NestingLevel2, false};
+              false ->
+                {CurrFun, CurrFunLabel, Tail, NewRL, RaceVarMap1,
+                 FunDefVars, FunCallVars, FunArgTypes, NewNL, false}
+            end;
+          #end_clause{arg = Arg, pats = Pats, guard = Guard} ->
+            {RaceVarMap1, _RemoveClause} =
+              race_var_map_guard(Arg, Pats, Guard, RaceVarMap, unbind),
+            {CurrFun, CurrFunLabel, Tail, NewRL, RaceVarMap1,
+             FunDefVars, FunCallVars, FunArgTypes, NewNL,
+             false};
+          #end_case{clauses = Clauses} ->
+            RaceVarMap1 =
+              race_var_map_clauses(Clauses, RaceVarMap),
+            {CurrFun, CurrFunLabel, Tail, NewRL, RaceVarMap1,
+             FunDefVars, FunCallVars, FunArgTypes, NewNL,
+             false};
+          #let_tag{var = Var, arg = Arg} ->
+            {CurrFun, CurrFunLabel, Tail, NewRL,
+             race_var_map(Var, Arg, RaceVarMap, bind), FunDefVars,
+             FunCallVars, FunArgTypes, NewNL, false};
+          #curr_fun{mfa = CurrFun1, label = CurrFunLabel1,
+                    var_map = RaceVarMap1, def_vars = FunDefVars1,
+                    call_vars = FunCallVars1, arg_types = FunArgTypes1} ->
+             case NewNL =:= 0 of
+               true ->
+                 {CurrFun, CurrFunLabel,
+                  remove_nonlocal_functions(Tail, 1), NewRL, RaceVarMap,
+                  FunDefVars, FunCallVars, FunArgTypes, NewNL, false};
+               false ->
+                 {CurrFun1, CurrFunLabel1, Tail, NewRL, RaceVarMap1,
+                  FunDefVars1, FunCallVars1, FunArgTypes1, NewNL, false}
+             end;
+          _Thing ->
+            {CurrFun, CurrFunLabel, Tail, NewRL, RaceVarMap,
+             FunDefVars, FunCallVars, FunArgTypes, NewNL, false}
+        end,
+      case Return of
+        true ->
+          {DepList, NewCurrFun, NewCurrFunLabel, Calls,
+           [], NewRaceList, NewRaceVarMap, NewFunDefVars,
+           NewFunCallVars, NewFunArgTypes, NewNestingLevel};
+        false ->
+          NewNestingLevel1 =
+            case NewNestingLevel =:= 0 of
+              true -> NewNestingLevel + 1;
+              false -> NewNestingLevel
+            end,
+          case PullOut of
+            true ->
+              {DepList, NewCurrFun, NewCurrFunLabel, Calls,
+               NewCode, NewRaceList, NewRaceVarMap, NewFunDefVars,
+               NewFunCallVars, NewFunArgTypes, NewNestingLevel1};
+            false ->
+              {RetDepList, NewCurrFun1,  NewCurrFunLabel1, NewCalls1,
+               NewCode1, NewRaceList1, NewRaceVarMap1, NewFunDefVars1,
+               NewFunCallVars1, NewFunArgTypes1, NewNestingLevel2} =
+                fixup_race_forward(NewCurrFun, NewCurrFunLabel, Calls,
+                                   NewCode, NewRaceList, InitFun, WarnVarArgs,
+                                   RaceWarnTag, NewRaceVarMap, NewFunDefVars,
+                                   NewFunCallVars, NewFunArgTypes,
+                                   NewNestingLevel1, State),
+              {DepList ++ RetDepList,  NewCurrFun1,  NewCurrFunLabel1,
+               NewCalls1, NewCode1, NewRaceList1, NewRaceVarMap1,
+               NewFunDefVars1, NewFunCallVars1, NewFunArgTypes1,
+               NewNestingLevel2}
+          end
+      end
+  end.
+
+get_deplist_paths(RaceList, WarnVarArgs, RaceWarnTag, RaceVarMap, CurrLevel,
+                  PublicTables, NamedTables) ->
+  case RaceList of
+    [] -> {[], false, true};
+    [Head|Tail] ->
+      case Head of
+        #end_case{} ->
+          {RaceList1, DepList1, IsPublic1, Continue1} =
+            handle_case(Tail, WarnVarArgs, RaceWarnTag, RaceVarMap, CurrLevel,
+                        PublicTables, NamedTables),
+          case Continue1 of
+            true ->
+              {DepList2, IsPublic2, Continue2} =
+                get_deplist_paths(RaceList1, WarnVarArgs, RaceWarnTag,
+                                  RaceVarMap, CurrLevel, PublicTables,
+                                  NamedTables),
+              {DepList1 ++ DepList2, IsPublic1 orelse IsPublic2, Continue2};
+            false -> {DepList1, IsPublic1, false}
+          end;
+        #beg_clause{} ->
+          get_deplist_paths(fixup_before_case_path(Tail), WarnVarArgs,
+                            RaceWarnTag, RaceVarMap, CurrLevel, PublicTables,
+                            NamedTables);
+        #curr_fun{status = in, var_map = RaceVarMap1} ->
+          {DepList, IsPublic, Continue} =
+            get_deplist_paths(Tail, WarnVarArgs, RaceWarnTag, RaceVarMap,
+                              CurrLevel + 1, PublicTables, NamedTables),
+          IsPublic1 =
+            case RaceWarnTag of
+              ?WARN_ETS_LOOKUP_INSERT ->
+                [Tabs, Names, _, _] = WarnVarArgs,
+                IsPublic orelse
+                  lists:any(
+                    fun (T) ->
+                        compare_var_list(T, PublicTables, RaceVarMap1)
+                    end, Tabs)
+                  orelse
+                  length(Names -- NamedTables) < length(Names);
+              _ -> true
+            end,
+          {DepList, IsPublic1, Continue};
+        #curr_fun{status = out, var_map = RaceVarMap1, def_vars = FunDefVars,
+                  call_vars = FunCallVars} ->
+          WarnVarArgs1 =
+            var_analysis([format_arg(DefVar) || DefVar <- FunDefVars],
+                         [format_arg(CallVar) || CallVar <- FunCallVars],
+                         WarnVarArgs, RaceWarnTag),
+          {WarnVarArgs2, Stop} =
+            case RaceWarnTag of
+              ?WARN_WHEREIS_REGISTER ->
+                [WVA1, WVA2, WVA3, WVA4] = WarnVarArgs1,
+                Vars =
+                  lists:flatten(
+                    [find_all_bound_vars(V, RaceVarMap1) || V <- WVA1]),
+                case {Vars, CurrLevel} of
+                  {[], 0} ->
+                    {WarnVarArgs, true};
+                  {[], _} ->
+                    {WarnVarArgs, false};
+                  _ ->
+                    {[Vars, WVA2, WVA3, WVA4], false}
+                end;
+              ?WARN_WHEREIS_UNREGISTER ->
+                [WVA1, WVA2] = WarnVarArgs1,
+                Vars =
+                  lists:flatten(
+                    [find_all_bound_vars(V, RaceVarMap1) || V <- WVA1]),
+                case {Vars, CurrLevel} of
+                  {[], 0} ->
+                    {WarnVarArgs, true};
+                  {[], _} ->
+                    {WarnVarArgs, false};
+                  _ ->
+                    {[Vars, WVA2], false}
+                end;
+              ?WARN_ETS_LOOKUP_INSERT ->
+                [WVA1, WVA2, WVA3, WVA4] = WarnVarArgs1,
+                Vars1 =
+                  lists:flatten(
+                    [find_all_bound_vars(V1, RaceVarMap1) || V1 <- WVA1]),
+                Vars2 =
+                  lists:flatten(
+                    [find_all_bound_vars(V2, RaceVarMap1) || V2 <- WVA3]),
+                case {Vars1, Vars2, CurrLevel} of
+                  {[], _, 0} ->
+                    {WarnVarArgs, true};
+                  {[], _, _} ->
+                    {WarnVarArgs, false};
+                  {_, [], 0} ->
+                    {WarnVarArgs, true};
+                  {_, [], _} ->
+                    {WarnVarArgs, false};
+                  _ ->
+                    {[Vars1, WVA2, Vars2, WVA4], false}
+                end;
+              ?WARN_MNESIA_DIRTY_READ_WRITE ->
+                [WVA1, WVA2|T] = WarnVarArgs1,
+                Vars =
+                  lists:flatten(
+                    [find_all_bound_vars(V, RaceVarMap1) || V <- WVA1]),
+                case {Vars, CurrLevel} of
+                  {[], 0} ->
+                    {WarnVarArgs, true};
+                  {[], _} ->
+                    {WarnVarArgs, false};
+                  _ ->
+                    {[Vars, WVA2|T], false}
+                end
+            end,
+          case Stop of
+            true -> {[], false, false};
+            false ->
+              CurrLevel1 =
+                case CurrLevel of
+                  0 -> CurrLevel;
+                  _ -> CurrLevel - 1
+                end,
+              get_deplist_paths(Tail, WarnVarArgs2, RaceWarnTag, RaceVarMap1,
+                                CurrLevel1, PublicTables, NamedTables)
+          end;
+        #warn_call{call_name = RegCall, args = WarnVarArgs1,
+                   var_map = RaceVarMap1} when RegCall =:= register orelse
+                                               RegCall =:= unregister ->
+          case compare_first_arg(WarnVarArgs, WarnVarArgs1, RaceVarMap1) of
+            true -> {[], false, false};
+            NewWarnVarArgs ->
+              get_deplist_paths(Tail, NewWarnVarArgs, RaceWarnTag, RaceVarMap,
+                                CurrLevel, PublicTables, NamedTables)
+          end;
+        #warn_call{call_name = ets_insert, args = WarnVarArgs1,
+                   var_map = RaceVarMap1} ->
+          case compare_ets_insert(WarnVarArgs, WarnVarArgs1, RaceVarMap1) of
+            true -> {[], false, false};
+            NewWarnVarArgs ->
+              get_deplist_paths(Tail, NewWarnVarArgs, RaceWarnTag, RaceVarMap,
+                                CurrLevel, PublicTables, NamedTables)
+          end;
+        #warn_call{call_name = mnesia_dirty_write, args = WarnVarArgs1,
+                   var_map = RaceVarMap1} ->
+          case compare_first_arg(WarnVarArgs, WarnVarArgs1, RaceVarMap1) of
+            true -> {[], false, false};
+            NewWarnVarArgs ->
+              get_deplist_paths(Tail, NewWarnVarArgs, RaceWarnTag, RaceVarMap,
+                                CurrLevel, PublicTables, NamedTables)
+          end;
+        #dep_call{var_map = RaceVarMap1} ->
+          {DepList, IsPublic, Continue} =
+            get_deplist_paths(Tail, WarnVarArgs, RaceWarnTag, RaceVarMap,
+                              CurrLevel, PublicTables, NamedTables),
+          {refine_race(Head, WarnVarArgs, RaceWarnTag, DepList, RaceVarMap1),
+	   IsPublic, Continue}
+     end
+  end.
+
+handle_case(RaceList, WarnVarArgs, RaceWarnTag, RaceVarMap, CurrLevel,
+            PublicTables, NamedTables) ->
+  case RaceList of
+    [] -> {[], [], false, true};
+    [Head|Tail] ->
+      case Head of
+        #end_clause{} ->
+          {RestRaceList, DepList1, IsPublic1, Continue1} =
+            do_clause(Tail, WarnVarArgs, RaceWarnTag, RaceVarMap, CurrLevel,
+                      PublicTables, NamedTables),
+          {RetRaceList, DepList2, IsPublic2, Continue2} =
+            handle_case(RestRaceList, WarnVarArgs, RaceWarnTag, RaceVarMap,
+                        CurrLevel, PublicTables, NamedTables),
+          {RetRaceList, DepList1 ++ DepList2, IsPublic1 orelse IsPublic2,
+           Continue1 orelse Continue2};
+        beg_case -> {Tail, [], false, false}
+      end
+  end.
+
+do_clause(RaceList, WarnVarArgs, RaceWarnTag, RaceVarMap, CurrLevel,
+          PublicTables, NamedTables) ->
+  {DepList, IsPublic, Continue} =
+    get_deplist_paths(fixup_case_path(RaceList, 0), WarnVarArgs,
+		      RaceWarnTag, RaceVarMap, CurrLevel,
+                      PublicTables, NamedTables),
+  {fixup_case_rest_paths(RaceList, 0), DepList, IsPublic, Continue}.
+
+fixup_case_path(RaceList, NestingLevel) ->
+  case RaceList of
+    [] -> [];
+    [Head|Tail] ->
+      {NewNestingLevel, Return} =
+        case Head of
+          beg_case -> {NestingLevel - 1, false};
+          #end_case{} -> {NestingLevel + 1, false};
+          #beg_clause{} ->
+            case NestingLevel =:= 0 of
+              true -> {NestingLevel, true};
+              false -> {NestingLevel, false}
+            end;
+          _Other -> {NestingLevel, false}
+        end,
+      case Return of
+        true -> [];
+        false -> [Head|fixup_case_path(Tail, NewNestingLevel)]
+      end
+  end.
+
+%% Gets the race list before a case clause.
+fixup_before_case_path(RaceList) ->
+  case RaceList of
+    [] -> [];
+    [Head|Tail] ->
+      case Head of
+        #end_clause{} ->
+          fixup_before_case_path(fixup_case_rest_paths(Tail, 0));
+        beg_case -> Tail
+      end
+  end.
+
+fixup_case_rest_paths(RaceList, NestingLevel) ->
+  case RaceList of
+    [] -> [];
+    [Head|Tail] ->
+      {NewNestingLevel, Return} =
+        case Head of
+          beg_case -> {NestingLevel - 1, false};
+          #end_case{} -> {NestingLevel + 1, false};
+          #beg_clause{} ->
+            case NestingLevel =:= 0 of
+              true -> {NestingLevel, true};
+              false -> {NestingLevel, false}
+            end;
+          _Other -> {NestingLevel, false}
+        end,
+      case Return of
+        true -> Tail;
+        false -> fixup_case_rest_paths(Tail, NewNestingLevel)
+      end
+  end.
+
+fixup_race_forward_helper(CurrFun, CurrFunLabel, Fun, FunLabel,
+                          Calls, CallsToAnalyze, Code, RaceList,
+                          InitFun, NewFunArgs, NewFunTypes,
+                          RaceWarnTag, RaceVarMap, FunDefVars,
+                          FunCallVars, FunArgTypes, NestingLevel,
+                          Args, CodeB, StateRaceList) ->
+  case Calls of
+    [] ->
+      {NewRaceList,
+       #curr_fun{mfa = NewCurrFun, label = NewCurrFunLabel,
+                 var_map = NewRaceVarMap, def_vars = NewFunDefVars,
+                 call_vars = NewFunCallVars, arg_types = NewFunArgTypes},
+       NewCode, NewNestingLevel} =
+        remove_clause(RaceList,
+        #curr_fun{mfa = CurrFun, label = CurrFunLabel, var_map = RaceVarMap,
+                  def_vars = FunDefVars, call_vars = FunCallVars,
+                  arg_types = FunArgTypes},
+        Code, NestingLevel),
+      {NewCurrFun, NewCurrFunLabel, CallsToAnalyze, NewCode, NewRaceList,
+       NewRaceVarMap, NewFunDefVars, NewFunCallVars, NewFunArgTypes,
+       NewNestingLevel};
+    [Head|Tail] ->
+      case Head of
+        {InitFun, InitFun} when CurrFun =:= InitFun, Fun =:= InitFun ->
+          NewCallsToAnalyze = lists:delete(Head, CallsToAnalyze),
+          NewRaceVarMap =
+            race_var_map(Args, NewFunArgs, RaceVarMap, bind),
+          RetC =
+            fixup_all_calls(InitFun, InitFun, FunLabel, Args,
+            CodeB ++
+            [#curr_fun{status = out, mfa =  InitFun,
+                       label = CurrFunLabel, var_map = RaceVarMap,
+                       def_vars = FunDefVars, call_vars = FunCallVars,
+                       arg_types = FunArgTypes}],
+            Code, RaceVarMap),
+          NewCode =
+            fixup_all_calls(InitFun, InitFun, FunLabel, Args,
+            CodeB ++
+            [#curr_fun{status = out, mfa =  InitFun,
+                       label = CurrFunLabel, var_map = NewRaceVarMap,
+                       def_vars = Args, call_vars = NewFunArgs,
+                       arg_types = NewFunTypes}],
+            [#curr_fun{status = in, mfa = Fun,
+                       label = FunLabel, var_map = NewRaceVarMap,
+                       def_vars = Args, call_vars = NewFunArgs,
+                       arg_types = NewFunTypes}|
+            lists:reverse(StateRaceList)] ++
+            RetC, NewRaceVarMap),
+          {InitFun, FunLabel, NewCallsToAnalyze, NewCode, RaceList,
+           NewRaceVarMap, Args, NewFunArgs, NewFunTypes, NestingLevel};
+        {CurrFun, Fun} ->
+          NewCallsToAnalyze = lists:delete(Head, CallsToAnalyze),
+          NewRaceVarMap = race_var_map(Args, NewFunArgs, RaceVarMap, bind),
+          RetC =
+            case Fun of
+              InitFun ->
+                fixup_all_calls(CurrFun, Fun, FunLabel, Args,
+                  lists:reverse(StateRaceList) ++
+                  [#curr_fun{status = out, mfa = CurrFun,
+                             label = CurrFunLabel, var_map = RaceVarMap,
+                             def_vars = FunDefVars, call_vars = FunCallVars,
+                             arg_types = FunArgTypes}],
+                  Code, RaceVarMap);
+              _Other1 ->
+                fixup_all_calls(CurrFun, Fun, FunLabel, Args,
+                  CodeB ++
+                  [#curr_fun{status = out, mfa = CurrFun,
+                             label = CurrFunLabel, var_map = RaceVarMap,
+                             def_vars = FunDefVars, call_vars = FunCallVars,
+                             arg_types = FunArgTypes}],
+                  Code, RaceVarMap)
+            end,
+          NewCode =
+            case Fun of
+              InitFun ->
+                [#curr_fun{status = in, mfa = Fun,
+                           label = FunLabel, var_map = NewRaceVarMap,
+                           def_vars = Args, call_vars = NewFunArgs,
+                           arg_types = NewFunTypes}|
+                 lists:reverse(StateRaceList)] ++ RetC;
+              _ ->
+                [#curr_fun{status = in, mfa = Fun,
+                           label = FunLabel, var_map = NewRaceVarMap,
+                           def_vars = Args, call_vars = NewFunArgs,
+                           arg_types = NewFunTypes}|CodeB] ++
+                  RetC
+            end,
+          {Fun, FunLabel, NewCallsToAnalyze, NewCode, RaceList, NewRaceVarMap,
+           Args, NewFunArgs, NewFunTypes, NestingLevel};
+	{_TupleA, _TupleB} ->
+	  fixup_race_forward_helper(CurrFun, CurrFunLabel, Fun, FunLabel,
+            Tail, CallsToAnalyze, Code, RaceList, InitFun, NewFunArgs,
+            NewFunTypes, RaceWarnTag, RaceVarMap, FunDefVars, FunCallVars,
+            FunArgTypes, NestingLevel, Args, CodeB, StateRaceList)
+      end
+  end.
+
+%%% ===========================================================================
+%%%
+%%%  Backward Analysis
+%%%
+%%% ===========================================================================
+
+fixup_race_backward(CurrFun, Calls, CallsToAnalyze, Parents, Height) ->
+  case Height =:= 0 of
+    true -> Parents;
+    false ->
+      case Calls of
+        [] ->
+          case is_integer(CurrFun) orelse lists:member(CurrFun, Parents) of
+            true -> Parents;
+            false -> [CurrFun|Parents]
+          end;
+        [Head|Tail] ->
+	  {Parent, TupleB} = Head,
+	  case TupleB =:= CurrFun of
+            true ->  % more paths are needed
+              NewCallsToAnalyze = lists:delete(Head, CallsToAnalyze),
+              NewParents =
+                fixup_race_backward(Parent, NewCallsToAnalyze,
+				    NewCallsToAnalyze, Parents, Height - 1),
+              fixup_race_backward(CurrFun, Tail, NewCallsToAnalyze, NewParents,
+				  Height);
+            false ->
+              fixup_race_backward(CurrFun, Tail, CallsToAnalyze, Parents,
+                                  Height)
+          end
+      end
+  end.
+
+%%% ===========================================================================
+%%%
+%%%  Utilities
+%%%
+%%% ===========================================================================
+
+are_bound_labels(Label1, Label2, RaceVarMap) ->
+  case dict:find(Label1, RaceVarMap) of
+    error -> false;
+    {ok, Labels} ->
+      lists:member(Label2, Labels) orelse
+        are_bound_labels_helper(Labels, Label1, Label2, RaceVarMap)
+  end.
+
+are_bound_labels_helper(Labels, OldLabel, CompLabel, RaceVarMap) ->
+  case dict:size(RaceVarMap) of
+    0 -> false;
+    _ ->
+      case Labels of
+        [] -> false;
+        [Head|Tail] ->
+          NewRaceVarMap = dict:erase(OldLabel, RaceVarMap),
+          are_bound_labels(Head, CompLabel, NewRaceVarMap) orelse
+	    are_bound_labels_helper(Tail, Head, CompLabel, NewRaceVarMap)
+      end
+  end.
+
+are_bound_vars(Vars1, Vars2, RaceVarMap) ->
+  case is_list(Vars1) andalso is_list(Vars2) of
+    true ->
+      case Vars1 of
+	[] -> false;
+	[AHead|ATail] ->
+	  case Vars2 of
+	    [] -> false;
+	    [PHead|PTail] ->
+	      are_bound_vars(AHead, PHead, RaceVarMap) andalso
+		are_bound_vars(ATail, PTail, RaceVarMap)
+	  end
+      end;
+    false ->
+      {NewVars1, NewVars2, IsList} =
+	case is_list(Vars1) of
+	  true ->
+	    case Vars1 of
+	      [Var1] -> {Var1, Vars2, true};
+	      _Thing -> {Vars1, Vars2, false}
+	    end;
+	  false ->
+	    case is_list(Vars2) of
+	      true ->
+		case Vars2 of
+		  [Var2] -> {Vars1, Var2, true};
+		  _Thing -> {Vars1, Vars2, false}
+		end;
+	      false -> {Vars1, Vars2, true}
+	    end
+	end,
+      case IsList of
+	true ->
+	  case cerl:type(NewVars1) of
+	    var ->
+	      case cerl:type(NewVars2) of
+		var ->
+		  ALabel = cerl_trees:get_label(NewVars1),
+		  PLabel = cerl_trees:get_label(NewVars2),
+		  are_bound_labels(ALabel, PLabel, RaceVarMap) orelse
+		    are_bound_labels(PLabel, ALabel, RaceVarMap);
+		alias ->
+		  are_bound_vars(NewVars1, cerl:alias_var(NewVars2),
+				 RaceVarMap);
+		values ->
+		  are_bound_vars(NewVars1, cerl:values_es(NewVars2),
+				 RaceVarMap);
+		_Other -> false
+	      end;
+	    tuple ->
+	      case cerl:type(NewVars2) of
+		tuple ->
+		  are_bound_vars(cerl:tuple_es(NewVars1),
+				 cerl:tuple_es(NewVars2), RaceVarMap);
+		alias ->
+		  are_bound_vars(NewVars1, cerl:alias_var(NewVars2),
+				 RaceVarMap);
+		values ->
+		  are_bound_vars(NewVars1, cerl:values_es(NewVars2),
+				 RaceVarMap);
+		_Other -> false
+	      end;
+	    cons ->
+	      case cerl:type(NewVars2) of
+		cons ->
+		  are_bound_vars(cerl:cons_hd(NewVars1),
+				 cerl:cons_hd(NewVars2), RaceVarMap)
+		    andalso
+		    are_bound_vars(cerl:cons_tl(NewVars1),
+				   cerl:cons_tl(NewVars2), RaceVarMap);
+		alias ->
+		  are_bound_vars(NewVars1, cerl:alias_var(NewVars2),
+				 RaceVarMap);
+		values ->
+		  are_bound_vars(NewVars1, cerl:values_es(NewVars2),
+				 RaceVarMap);
+		_Other -> false
+	      end;
+	    alias ->
+	      case cerl:type(NewVars2) of
+		alias ->
+		  are_bound_vars(cerl:alias_var(NewVars1),
+				 cerl:alias_var(NewVars2), RaceVarMap);
+		_Other ->
+		  are_bound_vars(cerl:alias_var(NewVars1),
+				 NewVars2, RaceVarMap)
+	      end;
+	    values ->
+	      case cerl:type(NewVars2) of
+		values ->
+		  are_bound_vars(cerl:values_es(NewVars1),
+				 cerl:values_es(NewVars2), RaceVarMap);
+		_Other ->
+		  are_bound_vars(cerl:values_es(NewVars1),
+				 NewVars2, RaceVarMap)
+	      end;
+	    _Other -> false
+	  end;
+	false -> false
+      end
+  end.
+
+callgraph__renew_tables(Table, Callgraph) ->
+  case Table of
+    {named, NameLabel, Names} ->
+      PTablesToAdd =
+        case NameLabel of
+          ?no_label -> [];
+          _Other -> [NameLabel]
+        end,
+      NamesToAdd = filter_named_tables(Names),
+      PTables = dialyzer_callgraph:get_public_tables(Callgraph),
+      NTables = dialyzer_callgraph:get_named_tables(Callgraph),
+      dialyzer_callgraph:put_public_tables(
+        lists:usort(PTablesToAdd ++ PTables),
+        dialyzer_callgraph:put_named_tables(
+        NamesToAdd ++ NTables, Callgraph));
+    _Other ->
+      Callgraph
+  end.
+
+cleanup_clause_code(#curr_fun{mfa = CurrFun} = CurrTuple, Code,
+                    NestingLevel, LocalNestingLevel) ->
+  case Code of
+    [] -> {CurrTuple, []};
+    [Head|Tail] ->
+      {NewLocalNestingLevel, NewNestingLevel, NewCurrTuple, Return} =
+        case Head of
+          beg_case ->
+            {LocalNestingLevel, NestingLevel + 1, CurrTuple, false};
+          #end_case{} ->
+            {LocalNestingLevel, NestingLevel - 1, CurrTuple, false};
+          #end_clause{} ->
+            case NestingLevel =:= 0 of
+              true ->
+                {LocalNestingLevel, NestingLevel, CurrTuple, true};
+              false ->
+                {LocalNestingLevel, NestingLevel, CurrTuple, false}
+            end;
+          #fun_call{caller = CurrFun} ->
+            {LocalNestingLevel - 1, NestingLevel, CurrTuple, false};
+          #curr_fun{status = in} ->
+            {LocalNestingLevel - 1, NestingLevel, Head, false};
+          #curr_fun{status = out} ->
+            {LocalNestingLevel + 1, NestingLevel, Head, false};
+          Other when Other =/= #fun_call{} ->
+            {LocalNestingLevel, NestingLevel, CurrTuple, false}
+        end,
+      case Return of
+        true -> {NewCurrTuple, Tail};
+        false ->
+          cleanup_clause_code(NewCurrTuple, Tail, NewNestingLevel,
+                              NewLocalNestingLevel)
+      end
+  end.
+
+cleanup_dep_calls(DepList) ->
+  case DepList of
+    [] -> [];
+    [#dep_call{call_name = CallName, arg_types = ArgTypes,
+               vars = Vars, state = State, file_line = FileLine}|T] ->
+      [#dep_call{call_name = CallName, arg_types = ArgTypes,
+                 vars = Vars, state = State, file_line = FileLine}|
+       cleanup_dep_calls(T)]
+  end.
+
+cleanup_race_code(State) ->
+  Callgraph = dialyzer_dataflow:state__get_callgraph(State),
+  dialyzer_dataflow:state__put_callgraph(
+    dialyzer_callgraph:race_code_new(Callgraph), State).
+
+filter_named_tables(NamesList) ->
+  case NamesList of
+    [] -> [];
+    [Head|Tail] ->
+      NewHead =
+        case string:rstr(Head, "()") of
+          0 -> [Head];
+          _Other -> []
+        end,
+      NewHead ++ filter_named_tables(Tail)
+  end.
+
+filter_parents(Parents, NewParents, Digraph) ->
+  case Parents of
+    [] -> NewParents;
+    [Head|Tail] ->
+      NewParents1 = filter_parents_helper1(Head, Tail, NewParents, Digraph),
+      filter_parents(Tail, NewParents1, Digraph)
+  end.
+
+filter_parents_helper1(First, Rest, NewParents, Digraph) ->
+  case Rest of
+    [] -> NewParents;
+    [Head|Tail] ->
+      NewParents1 = filter_parents_helper2(First, Head, NewParents, Digraph),
+      filter_parents_helper1(First, Tail, NewParents1, Digraph)
+  end.
+
+filter_parents_helper2(Parent1, Parent2, NewParents, Digraph) ->
+  case digraph:get_path(Digraph, Parent1, Parent2) of
+    false ->
+      case digraph:get_path(Digraph, Parent2, Parent1) of
+        false -> NewParents;
+        _Vertices -> NewParents -- [Parent1]
+      end;
+    _Vertices -> NewParents -- [Parent2]
+  end.
+
+find_all_bound_vars(Label, RaceVarMap) ->
+  case dict:find(Label, RaceVarMap) of
+    error -> [Label];
+    {ok, Labels} ->
+      lists:usort(Labels ++
+                  find_all_bound_vars_helper(Labels, Label, RaceVarMap))
+  end.
+
+find_all_bound_vars_helper(Labels, Label, RaceVarMap) ->
+  case dict:size(RaceVarMap) of
+    0 -> [];
+    _ ->
+      case Labels of
+        [] -> [];
+        [Head|Tail] ->
+          NewRaceVarMap = dict:erase(Label, RaceVarMap),
+          find_all_bound_vars(Head, NewRaceVarMap) ++
+	    find_all_bound_vars_helper(Tail, Head, NewRaceVarMap)
+      end
+  end.
+
+fixup_all_calls(CurrFun, NextFun, NextFunLabel, Args, CodeToReplace,
+                Code, RaceVarMap) ->
+  case Code of
+    [] -> [];
+    [Head|Tail] ->
+      NewCode =
+        case Head of
+          #fun_call{caller = CurrFun, callee = Callee,
+                    arg_types = FunArgTypes, vars = FunArgs}
+          when Callee =:= NextFun orelse Callee =:= NextFunLabel ->
+            RaceVarMap1 = race_var_map(Args, FunArgs, RaceVarMap, bind),
+            [#curr_fun{status = in, mfa = NextFun, label = NextFunLabel,
+                       var_map = RaceVarMap1, def_vars = Args,
+                       call_vars = FunArgs, arg_types = FunArgTypes}|
+              CodeToReplace];
+          _Other -> [Head]
+        end,
+      RetCode =
+        fixup_all_calls(CurrFun, NextFun, NextFunLabel, Args, CodeToReplace,
+                        Tail, RaceVarMap),
+      NewCode ++ RetCode
+  end.
+
+is_last_race(RaceTag, InitFun, Code, Callgraph) ->
+  case Code of
+    [] -> true;
+    [Head|Tail] ->
+      case Head of
+        RaceTag -> false;
+        #fun_call{callee = Fun} ->
+          FunName =
+            case is_integer(Fun) of
+              true ->
+                case dialyzer_callgraph:lookup_name(Fun, Callgraph) of
+                  error -> Fun;
+                  {ok, Name} -> Name
+                end;
+              false -> Fun
+            end,
+          Digraph = dialyzer_callgraph:get_digraph(Callgraph),
+          case FunName =:= InitFun orelse
+               digraph:get_path(Digraph, FunName, InitFun) of
+            false -> is_last_race(RaceTag, InitFun, Tail, Callgraph);
+            _Vertices -> false
+          end;
+        _Other -> is_last_race(RaceTag, InitFun, Tail, Callgraph)
+      end
+  end.
+
+lists_key_member(Member, List, N) when is_integer(Member) ->
+  case List of
+    [] -> 0;
+    [Head|Tail] ->
+      NewN = N + 1,
+      case Head of
+        Member -> NewN;
+        _Other -> lists_key_member(Member, Tail, NewN)
+      end
+  end;
+lists_key_member(_M, _L, _N) ->
+  0.
+
+lists_key_member_lists(MemberList, List) ->
+  case MemberList of
+    [] -> 0;
+    [Head|Tail] ->
+      case lists_key_member(Head, List, 0) of
+        0 -> lists_key_member_lists(Tail, List);
+        Other -> Other
+      end
+  end.
+
+lists_key_members_lists(MemberList, List) ->
+  case MemberList of
+    [] -> [];
+    [Head|Tail] ->
+      lists:usort(
+        lists_key_members_lists_helper(Head, List, 1) ++
+        lists_key_members_lists(Tail, List))
+  end.
+
+lists_key_members_lists_helper(Elem, List, N) when is_integer(Elem) ->
+  case List of
+    [] -> [];
+    [Head|Tail] ->
+      NewHead =
+        case Head =:= Elem of
+          true -> [N];
+          false -> []
+        end,
+      NewHead ++ lists_key_members_lists_helper(Elem, Tail, N + 1)
+  end;
+lists_key_members_lists_helper(_Elem, _List, _N) ->
+  [0].
+
+lists_key_replace(N, List, NewMember) ->
+  {Before, [_|After]} = lists:split(N - 1, List),
+  Before ++ [NewMember|After].
+
+lists_get(0, _List) -> ?no_label;
+lists_get(N, List) -> lists:nth(N, List).
+
+refine_race(RaceCall, WarnVarArgs, RaceWarnTag, DependencyList, RaceVarMap) ->
+  case RaceWarnTag of
+    WarnWhereis when WarnWhereis =:= ?WARN_WHEREIS_REGISTER orelse
+                     WarnWhereis =:= ?WARN_WHEREIS_UNREGISTER ->
+      case RaceCall of
+        #dep_call{call_name = ets_lookup} ->
+          DependencyList;
+        #dep_call{call_name = mnesia_dirty_read} ->
+          DependencyList;
+        #dep_call{call_name = whereis, args = VarArgs} ->
+          refine_race_helper(RaceCall, VarArgs, WarnVarArgs, RaceWarnTag,
+                             DependencyList, RaceVarMap)
+      end;
+    ?WARN_ETS_LOOKUP_INSERT ->
+      case RaceCall of
+        #dep_call{call_name = whereis} ->
+          DependencyList;
+        #dep_call{call_name = mnesia_dirty_read} ->
+          DependencyList;
+        #dep_call{call_name = ets_lookup, args = VarArgs} ->
+          refine_race_helper(RaceCall, VarArgs, WarnVarArgs, RaceWarnTag,
+                             DependencyList, RaceVarMap)
+      end;
+    ?WARN_MNESIA_DIRTY_READ_WRITE ->
+      case RaceCall of
+        #dep_call{call_name = whereis} ->
+          DependencyList;
+        #dep_call{call_name = ets_lookup} ->
+          DependencyList;
+        #dep_call{call_name = mnesia_dirty_read, args = VarArgs} ->
+          refine_race_helper(RaceCall, VarArgs, WarnVarArgs, RaceWarnTag,
+                             DependencyList, RaceVarMap)
+      end
+  end.
+
+refine_race_helper(RaceCall, VarArgs, WarnVarArgs, RaceWarnTag, DependencyList,
+                   RaceVarMap) ->
+  case compare_types(VarArgs, WarnVarArgs, RaceWarnTag, RaceVarMap) of
+    true -> [RaceCall|DependencyList];
+    false -> DependencyList
+  end.
+
+remove_clause(RaceList, CurrTuple, Code, NestingLevel) ->
+  NewRaceList = fixup_case_rest_paths(RaceList, 0),
+  {NewCurrTuple, NewCode} =
+    cleanup_clause_code(CurrTuple, Code, 0, NestingLevel),
+  ReturnTuple = {NewRaceList, NewCurrTuple, NewCode, NestingLevel},
+  case NewRaceList of
+    [beg_case|RTail] ->
+      case NewCode of
+        [#end_case{}|CTail] ->
+          remove_clause(RTail, NewCurrTuple, CTail, NestingLevel);
+        _Other -> ReturnTuple
+      end;
+    _Else -> ReturnTuple
+  end.
+
+remove_nonlocal_functions(Code, NestingLevel) ->
+  case Code of
+    [] -> [];
+    [H|T] ->
+      NewNL =
+        case H of
+          #curr_fun{status = in} ->
+            NestingLevel + 1;
+          #curr_fun{status = out} ->
+            NestingLevel - 1;
+          _Other ->
+            NestingLevel
+        end,
+      case NewNL =:= 0 of
+        true -> T;
+        false -> remove_nonlocal_functions(T, NewNL)
+      end
+  end.
+
+renew_curr_fun(CurrFun, Races) ->
+  Races#races{curr_fun = CurrFun}.
+
+renew_curr_fun_label(CurrFunLabel, Races) ->
+  Races#races{curr_fun_label = CurrFunLabel}.
+
+renew_race_list(RaceList, Races) ->
+  Races#races{race_list = RaceList}.
+
+renew_race_list_size(RaceListSize, Races) ->
+  Races#races{race_list_size = RaceListSize}.
+
+renew_race_tags(RaceTags, Races) ->
+  Races#races{race_tags = RaceTags}.
+
+renew_table(Table, Races) ->
+  Races#races{new_table = Table}.
+
+state__renew_curr_fun(CurrFun, State) ->
+  Races = dialyzer_dataflow:state__get_races(State),
+  dialyzer_dataflow:state__put_races(renew_curr_fun(CurrFun, Races), State).
+
+state__renew_curr_fun_label(CurrFunLabel, State) ->
+  Races = dialyzer_dataflow:state__get_races(State),
+  dialyzer_dataflow:state__put_races(
+    renew_curr_fun_label(CurrFunLabel, Races), State).
+
+state__renew_race_list(RaceList, State) ->
+  Races = dialyzer_dataflow:state__get_races(State),
+  dialyzer_dataflow:state__put_races(renew_race_list(RaceList, Races), State).
+
+state__renew_race_tags(RaceTags, State) ->
+  Races = dialyzer_dataflow:state__get_races(State),
+  dialyzer_dataflow:state__put_races(renew_race_tags(RaceTags, Races), State).
+
+state__renew_info(RaceList, RaceListSize, RaceTags, Table, State) ->
+  Callgraph = dialyzer_dataflow:state__get_callgraph(State),
+  Races = dialyzer_dataflow:state__get_races(State),
+  dialyzer_dataflow:state__put_callgraph(
+    callgraph__renew_tables(Table, Callgraph),
+    dialyzer_dataflow:state__put_races(
+      renew_table(Table,
+      renew_race_list(RaceList,
+      renew_race_list_size(RaceListSize,
+      renew_race_tags(RaceTags, Races)))), State)).
+
+%%% ===========================================================================
+%%%
+%%%  Variable and Type Utilities
+%%%
+%%% ===========================================================================
+
+any_args(StrList) ->
+  case StrList of
+    [] -> false;
+    [Head|Tail] ->
+      case string:rstr(Head, "()") of
+        0 -> any_args(Tail);
+        _Other -> true
+      end
+  end.
+
+-spec bind_dict_vars(label(), label(), dict:dict()) -> dict:dict().
+
+bind_dict_vars(Key, Label, RaceVarMap) ->
+  case Key =:= Label of
+    true -> RaceVarMap;
+    false ->
+      case dict:find(Key, RaceVarMap) of
+	error -> dict:store(Key, [Label], RaceVarMap);
+	{ok, Labels} ->
+	  case lists:member(Label, Labels) of
+	    true -> RaceVarMap;
+	    false -> dict:store(Key, [Label|Labels], RaceVarMap)
+	  end
+      end
+  end.
+
+bind_dict_vars_list(Key, Labels, RaceVarMap) ->
+  case Labels of
+    [] -> RaceVarMap;
+    [Head|Tail] ->
+      bind_dict_vars_list(Key, Tail, bind_dict_vars(Key, Head, RaceVarMap))
+  end.
+
+compare_ets_insert(OldWarnVarArgs, NewWarnVarArgs, RaceVarMap) ->
+  [Old1, Old2, Old3, Old4] = OldWarnVarArgs,
+  [New1, New2, New3, New4] = NewWarnVarArgs,
+  Bool =
+    case any_args(Old2) of
+      true -> compare_var_list(New1, Old1, RaceVarMap);
+      false ->
+        case any_args(New2) of
+          true -> compare_var_list(New1, Old1, RaceVarMap);
+          false -> compare_var_list(New1, Old1, RaceVarMap)
+                     orelse (Old2 =:= New2)
+        end
+    end,
+  case Bool of
+    true ->
+      case any_args(Old4) of
+        true ->
+          case compare_list_vars(Old3, ets_list_args(New3), [], RaceVarMap) of
+            true -> true;
+            Args3 -> lists_key_replace(3, OldWarnVarArgs, Args3)
+          end;
+        false ->
+           case any_args(New4) of
+             true ->
+               case compare_list_vars(Old3, ets_list_args(New3), [],
+                                      RaceVarMap) of
+                 true -> true;
+                 Args3 -> lists_key_replace(3, OldWarnVarArgs, Args3)
+               end;
+             false ->
+               case compare_list_vars(Old3, ets_list_args(New3), [],
+                                      RaceVarMap) of
+                 true -> true;
+                 Args3 ->
+                   lists_key_replace(4,
+                     lists_key_replace(3, OldWarnVarArgs, Args3), Old4 -- New4)
+               end
+           end
+      end;
+    false -> OldWarnVarArgs
+  end.
+
+compare_first_arg(OldWarnVarArgs, NewWarnVarArgs, RaceVarMap) ->
+  [Old1, Old2|_OldT] = OldWarnVarArgs,
+  [New1, New2|_NewT] = NewWarnVarArgs,
+  case any_args(Old2) of
+    true ->
+      case compare_var_list(New1, Old1, RaceVarMap) of
+        true -> true;
+        false -> OldWarnVarArgs
+      end;
+    false ->
+      case any_args(New2) of
+        true ->
+          case compare_var_list(New1, Old1, RaceVarMap) of
+            true -> true;
+            false -> OldWarnVarArgs
+          end;
+        false ->
+          case compare_var_list(New1, Old1, RaceVarMap) of
+            true -> true;
+            false -> lists_key_replace(2, OldWarnVarArgs, Old2 -- New2)
+          end
+      end
+  end.
+
+compare_argtypes(ArgTypes, WarnArgTypes) ->
+  lists:any(fun (X) -> lists:member(X, WarnArgTypes) end, ArgTypes).
+
+%% Compares the argument types of the two suspicious calls.
+compare_types(VarArgs, WarnVarArgs, RaceWarnTag, RaceVarMap) ->
+  case RaceWarnTag of
+    ?WARN_WHEREIS_REGISTER ->
+      [VA1, VA2] = VarArgs,
+      [WVA1, WVA2, _, _] = WarnVarArgs,
+      case any_args(VA2) of
+        true -> compare_var_list(VA1, WVA1, RaceVarMap);
+        false ->
+          case any_args(WVA2) of
+            true -> compare_var_list(VA1, WVA1, RaceVarMap);
+            false ->
+              compare_var_list(VA1, WVA1, RaceVarMap) orelse
+                compare_argtypes(VA2, WVA2)
+          end
+      end;
+    ?WARN_WHEREIS_UNREGISTER ->
+      [VA1, VA2] = VarArgs,
+      [WVA1, WVA2] = WarnVarArgs,
+      case any_args(VA2) of
+        true -> compare_var_list(VA1, WVA1, RaceVarMap);
+        false ->
+          case any_args(WVA2) of
+            true -> compare_var_list(VA1, WVA1, RaceVarMap);
+            false ->
+              compare_var_list(VA1, WVA1, RaceVarMap) orelse
+                compare_argtypes(VA2, WVA2)
+          end
+      end;
+    ?WARN_ETS_LOOKUP_INSERT ->
+      [VA1, VA2, VA3, VA4] = VarArgs,
+      [WVA1, WVA2, WVA3, WVA4] = WarnVarArgs,
+      Bool =
+        case any_args(VA2) of
+          true -> compare_var_list(VA1, WVA1, RaceVarMap);
+          false ->
+            case any_args(WVA2) of
+              true -> compare_var_list(VA1, WVA1, RaceVarMap);
+              false ->
+                compare_var_list(VA1, WVA1, RaceVarMap) orelse
+                  compare_argtypes(VA2, WVA2)
+            end
+        end,
+      Bool andalso
+        (case any_args(VA4) of
+           true ->
+             compare_var_list(VA3, WVA3, RaceVarMap);
+           false ->
+             case any_args(WVA4) of
+               true ->
+                 compare_var_list(VA3, WVA3, RaceVarMap);
+               false ->
+                 compare_var_list(VA3, WVA3, RaceVarMap) orelse
+                   compare_argtypes(VA4, WVA4)
+             end
+         end);
+    ?WARN_MNESIA_DIRTY_READ_WRITE ->
+      [VA1, VA2|_] = VarArgs, %% Two or four elements
+      [WVA1, WVA2|_] = WarnVarArgs,
+      case any_args(VA2) of
+        true -> compare_var_list(VA1, WVA1, RaceVarMap);
+        false ->
+          case any_args(WVA2) of
+            true -> compare_var_list(VA1, WVA1, RaceVarMap);
+            false ->
+              compare_var_list(VA1, WVA1, RaceVarMap) orelse
+                compare_argtypes(VA2, WVA2)
+          end
+      end
+  end.
+
+compare_list_vars(VarList1, VarList2, NewVarList1, RaceVarMap) ->
+  case VarList1 of
+    [] ->
+      case NewVarList1 of
+        [] -> true;
+        _Other -> NewVarList1
+      end;
+    [Head|Tail] ->
+      NewHead =
+        case compare_var_list(Head, VarList2, RaceVarMap) of
+          true -> [];
+          false -> [Head]
+        end,
+      compare_list_vars(Tail, VarList2, NewHead ++ NewVarList1, RaceVarMap)
+  end.
+
+compare_vars(Var1, Var2, RaceVarMap) when is_integer(Var1), is_integer(Var2) ->
+  Var1 =:= Var2 orelse
+    are_bound_labels(Var1, Var2, RaceVarMap) orelse
+    are_bound_labels(Var2, Var1, RaceVarMap);
+compare_vars(_Var1, _Var2, _RaceVarMap) ->
+  false.
+
+-spec compare_var_list(label_type(), [label_type()], dict:dict()) -> boolean().
+
+compare_var_list(Var, VarList, RaceVarMap) ->
+  lists:any(fun (V) -> compare_vars(Var, V, RaceVarMap) end, VarList).
+
+ets_list_args(MaybeList) ->
+  case is_list(MaybeList) of
+    true ->
+      try [ets_tuple_args(T) || T <- MaybeList]
+      catch _:_ -> [?no_label]
+      end;
+    false -> [ets_tuple_args(MaybeList)]
+  end.
+
+ets_list_argtypes(ListStr) ->
+  ListStr1 = string:strip(ListStr, left, $[),
+  ListStr2 = string:strip(ListStr1, right, $]),
+  ListStr3 = string:strip(ListStr2, right, $.),
+  string:strip(ListStr3, right, $,).
+
+ets_tuple_args(MaybeTuple) ->
+  case is_tuple(MaybeTuple) of
+    true -> element(1, MaybeTuple);
+    false -> ?no_label
+  end.
+
+ets_tuple_argtypes2(TupleList, ElemList) ->
+  case TupleList of
+    [] -> ElemList;
+    [H|T] ->
+      ets_tuple_argtypes2(T,
+                          ets_tuple_argtypes2_helper(H, [], 0) ++ ElemList)
+  end.
+
+ets_tuple_argtypes2_helper(TupleStr, ElemStr, NestingLevel) ->
+  case TupleStr of
+    [] -> [];
+    [H|T] ->
+      {NewElemStr, NewNestingLevel, Return} =
+        case H of
+          ${ when NestingLevel =:= 0 ->
+            {ElemStr, NestingLevel + 1, false};
+          ${ ->
+            {[H|ElemStr], NestingLevel + 1, false};
+          $[ ->
+            {[H|ElemStr], NestingLevel + 1, false};
+          $( ->
+            {[H|ElemStr], NestingLevel + 1, false};
+          $} ->
+            {[H|ElemStr], NestingLevel - 1, false};
+          $] ->
+            {[H|ElemStr], NestingLevel - 1, false};
+          $) ->
+            {[H|ElemStr], NestingLevel - 1, false};
+          $, when NestingLevel =:= 1 ->
+            {lists:reverse(ElemStr), NestingLevel, true};
+          _Other ->
+            {[H|ElemStr], NestingLevel, false}
+        end,
+      case Return of
+        true -> string:tokens(NewElemStr, " |");
+        false ->
+          ets_tuple_argtypes2_helper(T, NewElemStr, NewNestingLevel)
+      end
+  end.
+
+ets_tuple_argtypes1(Str, Tuple, TupleList, NestingLevel) ->
+  case Str of
+    [] -> TupleList;
+    [H|T] ->
+      {NewTuple, NewNestingLevel, Add} =
+        case H of
+          ${ ->
+            {[H|Tuple], NestingLevel + 1, false};
+          $} ->
+            case NestingLevel of
+              1 ->
+                {[H|Tuple], NestingLevel - 1, true};
+              _Else ->
+                {[H|Tuple], NestingLevel - 1, false}
+            end;
+          _Other1 when NestingLevel =:= 0 ->
+            {Tuple, NestingLevel, false};
+          _Other2 ->
+            {[H|Tuple], NestingLevel, false}
+        end,
+        case Add of
+          true ->
+            ets_tuple_argtypes1(T, [],
+                                [lists:reverse(NewTuple)|TupleList],
+                                NewNestingLevel);
+          false ->
+            ets_tuple_argtypes1(T, NewTuple, TupleList, NewNestingLevel)
+        end
+  end.
+
+format_arg(?bypassed) -> ?no_label;
+format_arg(Arg0) ->
+  Arg = cerl:fold_literal(Arg0),
+  case cerl:type(Arg) of
+    var -> cerl_trees:get_label(Arg);
+    tuple -> list_to_tuple([format_arg(A) || A <- cerl:tuple_es(Arg)]);
+    cons -> [format_arg(cerl:cons_hd(Arg))|format_arg(cerl:cons_tl(Arg))];
+    alias -> format_arg(cerl:alias_var(Arg));
+    literal ->
+      case cerl:is_c_nil(Arg) of
+        true -> [];
+        false -> ?no_label
+      end;
+    _Other -> ?no_label
+  end.
+
+-spec format_args([core_vars()], [erl_types:erl_type()],
+                  dialyzer_dataflow:state(), call()) ->
+  args().
+
+format_args([], [], _State, _Call) ->
+  [];
+format_args(ArgList, TypeList, CleanState, Call) ->
+  format_args_2(format_args_1(ArgList, TypeList, CleanState), Call).
+
+format_args_1([Arg], [Type], CleanState) ->
+  [format_arg(Arg), format_type(Type, CleanState)];
+format_args_1([Arg|Args], [Type|Types], CleanState) ->
+  List =
+    case Arg =:= ?bypassed of
+      true -> [?no_label, format_type(Type, CleanState)];
+      false ->
+        case cerl:is_literal(cerl:fold_literal(Arg)) of
+          true -> [?no_label, format_cerl(Arg)];
+          false -> [format_arg(Arg), format_type(Type, CleanState)]
+        end
+    end,
+  List ++ format_args_1(Args, Types, CleanState).
+
+format_args_2(StrArgList, Call) ->
+  case Call of
+    whereis ->
+      lists_key_replace(2, StrArgList,
+	string:tokens(lists:nth(2, StrArgList), " |"));
+    register ->
+      lists_key_replace(2, StrArgList,
+	string:tokens(lists:nth(2, StrArgList), " |"));
+    unregister ->
+      lists_key_replace(2, StrArgList,
+	string:tokens(lists:nth(2, StrArgList), " |"));
+    ets_new ->
+      StrArgList1 = lists_key_replace(2, StrArgList,
+	string:tokens(lists:nth(2, StrArgList), " |")),
+      lists_key_replace(4, StrArgList1,
+        string:tokens(ets_list_argtypes(lists:nth(4, StrArgList1)), " |"));
+    ets_lookup ->
+      StrArgList1 = lists_key_replace(2, StrArgList,
+        string:tokens(lists:nth(2, StrArgList), " |")),
+      lists_key_replace(4, StrArgList1,
+        string:tokens(lists:nth(4, StrArgList1), " |"));
+    ets_insert ->
+      StrArgList1 = lists_key_replace(2, StrArgList,
+        string:tokens(lists:nth(2, StrArgList), " |")),
+      lists_key_replace(4, StrArgList1,
+        ets_tuple_argtypes2(
+        ets_tuple_argtypes1(lists:nth(4, StrArgList1), [], [], 0),
+        []));
+    mnesia_dirty_read1 ->
+      lists_key_replace(2, StrArgList,
+        [mnesia_tuple_argtypes(T) || T <- string:tokens(
+        lists:nth(2, StrArgList), " |")]);
+    mnesia_dirty_read2 ->
+      lists_key_replace(2, StrArgList,
+        string:tokens(lists:nth(2, StrArgList), " |"));
+    mnesia_dirty_write1 ->
+      lists_key_replace(2, StrArgList,
+        [mnesia_record_tab(R) || R <- string:tokens(
+        lists:nth(2, StrArgList), " |")]);
+    mnesia_dirty_write2 ->
+      lists_key_replace(2, StrArgList,
+        string:tokens(lists:nth(2, StrArgList), " |"));
+    function_call -> StrArgList
+  end.
+
+format_cerl(Tree) ->
+  cerl_prettypr:format(cerl:set_ann(Tree, []),
+                       [{hook, dialyzer_utils:pp_hook()},
+                        {noann, true},
+                        {paper, 100000},
+                        {ribbon, 100000}
+                       ]).
+
+format_type(Type, State) ->
+  R = dialyzer_dataflow:state__get_records(State),
+  erl_types:t_to_string(Type, R).
+
+mnesia_record_tab(RecordStr) ->
+  case string:str(RecordStr, "#") =:= 1 of
+    true ->
+      "'" ++
+        string:sub_string(RecordStr, 2, string:str(RecordStr, "{") - 1) ++
+        "'";
+    false -> RecordStr
+  end.
+
+mnesia_tuple_argtypes(TupleStr) ->
+  TupleStr1 = string:strip(TupleStr, left, ${),
+  [TupleStr2|_T] = string:tokens(TupleStr1, " ,"),
+  lists:flatten(string:tokens(TupleStr2, " |")).
+
+-spec race_var_map(var_to_map1(), var_to_map2(), dict:dict(), op()) ->
+        dict:dict().
+
+race_var_map(Vars1, Vars2, RaceVarMap, Op) ->
+  case Vars1 =:= ?no_arg orelse Vars1 =:= ?bypassed
+                         orelse Vars2 =:= ?bypassed of
+    true -> RaceVarMap;
+    false ->
+      case is_list(Vars1) andalso is_list(Vars2) of
+        true ->
+          case Vars1 of
+            [] -> RaceVarMap;
+            [AHead|ATail] ->
+              case Vars2 of
+                [] -> RaceVarMap;
+                [PHead|PTail] ->
+                  NewRaceVarMap = race_var_map(AHead, PHead, RaceVarMap, Op),
+                  race_var_map(ATail, PTail, NewRaceVarMap, Op)
+              end
+          end;
+        false ->
+          {NewVars1, NewVars2, Bool} =
+            case is_list(Vars1) of
+              true ->
+                case Vars1 of
+                  [Var1] -> {Var1, Vars2, true};
+                  _Thing -> {Vars1, Vars2, false}
+                end;
+              false ->
+                case is_list(Vars2) of
+                  true ->
+                    case Vars2 of
+                      [Var2] -> {Vars1, Var2, true};
+                      _Thing -> {Vars1, Vars2, false}
+                    end;
+                  false -> {Vars1, Vars2, true}
+                end
+            end,
+          case Bool of
+            true ->
+              case cerl:type(NewVars1) of
+                var ->
+                  case cerl:type(NewVars2) of
+                    var ->
+                      ALabel = cerl_trees:get_label(NewVars1),
+                      PLabel = cerl_trees:get_label(NewVars2),
+                      case Op of
+                        bind ->
+                          TempRaceVarMap =
+                            bind_dict_vars(ALabel, PLabel, RaceVarMap),
+                          bind_dict_vars(PLabel, ALabel, TempRaceVarMap);
+                        unbind ->
+                          TempRaceVarMap =
+                            unbind_dict_vars(ALabel, PLabel, RaceVarMap),
+                          unbind_dict_vars(PLabel, ALabel, TempRaceVarMap)
+                      end;
+                    alias ->
+                      race_var_map(NewVars1, cerl:alias_var(NewVars2),
+				   RaceVarMap, Op);
+                    values ->
+                      race_var_map(NewVars1, cerl:values_es(NewVars2),
+				   RaceVarMap, Op);
+                    _Other -> RaceVarMap
+                  end;
+                tuple ->
+                  case cerl:type(NewVars2) of
+                    tuple ->
+                      race_var_map(cerl:tuple_es(NewVars1),
+				   cerl:tuple_es(NewVars2), RaceVarMap, Op);
+                    alias ->
+                      race_var_map(NewVars1, cerl:alias_var(NewVars2),
+				   RaceVarMap, Op);
+                    values ->
+                      race_var_map(NewVars1, cerl:values_es(NewVars2),
+				   RaceVarMap, Op);
+                    _Other -> RaceVarMap
+                  end;
+                cons ->
+                  case cerl:type(NewVars2) of
+                    cons ->
+                      NewRaceVarMap = race_var_map(cerl:cons_hd(NewVars1),
+                        cerl:cons_hd(NewVars2), RaceVarMap, Op),
+                      race_var_map(cerl:cons_tl(NewVars1),
+                        cerl:cons_tl(NewVars2), NewRaceVarMap, Op);
+                    alias ->
+                      race_var_map(NewVars1, cerl:alias_var(NewVars2),
+				   RaceVarMap, Op);
+                    values ->
+                      race_var_map(NewVars1, cerl:values_es(NewVars2),
+				   RaceVarMap, Op);
+                    _Other -> RaceVarMap
+                  end;
+                alias ->
+                  case cerl:type(NewVars2) of
+                    alias ->
+                      race_var_map(cerl:alias_var(NewVars1),
+				   cerl:alias_var(NewVars2), RaceVarMap, Op);
+                    _Other ->
+                      race_var_map(cerl:alias_var(NewVars1),
+                        NewVars2, RaceVarMap, Op)
+                  end;
+                values ->
+                  case cerl:type(NewVars2) of
+                    values ->
+                      race_var_map(cerl:values_es(NewVars1),
+				   cerl:values_es(NewVars2), RaceVarMap, Op);
+                    _Other ->
+                      race_var_map(cerl:values_es(NewVars1),
+                        NewVars2, RaceVarMap, Op)
+                  end;
+                _Other -> RaceVarMap
+              end;
+            false -> RaceVarMap
+          end
+      end
+  end.
+
+race_var_map_clauses(Clauses, RaceVarMap) ->
+  case Clauses of
+    [] -> RaceVarMap;
+    [#end_clause{arg = Arg, pats = Pats, guard = Guard}|T] ->
+      {RaceVarMap1, _RemoveClause} =
+        race_var_map_guard(Arg, Pats, Guard, RaceVarMap, bind),
+      race_var_map_clauses(T, RaceVarMap1)
+  end.
+
+race_var_map_guard(Arg, Pats, Guard, RaceVarMap, Op) ->
+  {NewRaceVarMap, RemoveClause} =
+    case cerl:type(Guard) of
+      call ->
+        CallName = cerl:call_name(Guard),
+        case cerl:is_literal(CallName) of
+          true ->
+            case cerl:concrete(CallName) of
+              '=:=' ->
+                [Arg1, Arg2] = cerl:call_args(Guard),
+                {race_var_map(Arg1, Arg2, RaceVarMap, Op), false};
+              '==' ->
+                [Arg1, Arg2] = cerl:call_args(Guard),
+                {race_var_map(Arg1, Arg2, RaceVarMap, Op), false};
+              '=/=' ->
+                case Op of
+                  bind ->
+                    [Arg1, Arg2] = cerl:call_args(Guard),
+                    {RaceVarMap, are_bound_vars(Arg1, Arg2, RaceVarMap)};
+                  unbind -> {RaceVarMap, false}
+                end;
+              _Other -> {RaceVarMap, false}
+            end;
+          false -> {RaceVarMap, false}
+        end;
+      _Other -> {RaceVarMap, false}
+    end,
+  {RaceVarMap1, RemoveClause1} =
+    race_var_map_guard_helper1(Arg, Pats,
+    race_var_map(Arg, Pats, NewRaceVarMap, Op), Op),
+  {RaceVarMap1, RemoveClause orelse RemoveClause1}.
+
+race_var_map_guard_helper1(Arg, Pats, RaceVarMap, Op) ->
+  case Arg =:= ?no_arg orelse Arg =:= ?bypassed of
+    true -> {RaceVarMap, false};
+    false ->
+      case cerl:type(Arg) of
+        call ->
+          case Pats of
+            [NewPat] ->
+              ModName = cerl:call_module(Arg),
+              CallName = cerl:call_name(Arg),
+              case cerl:is_literal(ModName) andalso
+                cerl:is_literal(CallName) of
+                true ->
+                  case {cerl:concrete(ModName),
+                        cerl:concrete(CallName)} of
+                    {erlang, '=:='} ->
+                      race_var_map_guard_helper2(Arg, NewPat, true,
+                                                 RaceVarMap, Op);
+                    {erlang, '=='} ->
+                      race_var_map_guard_helper2(Arg, NewPat, true,
+                                                 RaceVarMap, Op);
+                    {erlang, '=/='} ->
+                      race_var_map_guard_helper2(Arg, NewPat, false,
+                                                 RaceVarMap, Op);
+                    _Else -> {RaceVarMap, false}
+                  end;
+                false -> {RaceVarMap, false}
+              end;
+            _Other -> {RaceVarMap, false}
+          end;
+        _Other -> {RaceVarMap, false}
+      end
+  end.
+
+race_var_map_guard_helper2(Arg, Pat0, Bool, RaceVarMap, Op) ->
+  Pat = cerl:fold_literal(Pat0),
+  case cerl:type(Pat) of
+    literal ->
+      [Arg1, Arg2] = cerl:call_args(Arg),
+      case cerl:concrete(Pat) of
+        Bool ->
+          {race_var_map(Arg1, Arg2, RaceVarMap, Op), false};
+        _Else ->
+          case Op of
+            bind ->
+              {RaceVarMap, are_bound_vars(Arg1, Arg2, RaceVarMap)};
+            unbind -> {RaceVarMap, false}
+          end
+      end;
+    _Else -> {RaceVarMap, false}
+  end.
+
+unbind_dict_vars(Var, Var, RaceVarMap) ->
+  RaceVarMap;
+unbind_dict_vars(Var1, Var2, RaceVarMap) ->
+  case dict:find(Var1, RaceVarMap) of
+    error -> RaceVarMap;
+    {ok, Labels} ->
+      case Labels of
+        [] -> dict:erase(Var1, RaceVarMap);
+        _Else ->
+          case lists:member(Var2, Labels) of
+            true ->
+              unbind_dict_vars(Var1, Var2,
+                bind_dict_vars_list(Var1, Labels -- [Var2],
+				    dict:erase(Var1, RaceVarMap)));
+            false ->
+              unbind_dict_vars_helper(Labels, Var1, Var2, RaceVarMap)
+          end
+      end
+  end.
+
+unbind_dict_vars_helper(Labels, Key, CompLabel, RaceVarMap) ->
+  case dict:size(RaceVarMap) of
+    0 -> RaceVarMap;
+    _ ->
+      case Labels of
+        [] -> RaceVarMap;
+        [Head|Tail] ->
+          NewRaceVarMap =
+            case are_bound_labels(Head, CompLabel, RaceVarMap) orelse
+                 are_bound_labels(CompLabel, Head, RaceVarMap) of
+              true ->
+                bind_dict_vars_list(Key, Labels -- [Head],
+				      dict:erase(Key, RaceVarMap));
+              false -> RaceVarMap
+            end,
+          unbind_dict_vars_helper(Tail, Key, CompLabel, NewRaceVarMap)
+      end
+  end.
+
+var_analysis(FunDefArgs, FunCallArgs, WarnVarArgs, RaceWarnTag) ->
+  case RaceWarnTag of
+    ?WARN_WHEREIS_REGISTER ->
+      [WVA1, WVA2, WVA3, WVA4] = WarnVarArgs,
+      ArgNos = lists_key_members_lists(WVA1, FunDefArgs),
+      [[lists_get(N, FunCallArgs) || N <- ArgNos], WVA2, WVA3, WVA4];
+    ?WARN_WHEREIS_UNREGISTER ->
+      [WVA1, WVA2] = WarnVarArgs,
+      ArgNos = lists_key_members_lists(WVA1, FunDefArgs),
+      [[lists_get(N, FunCallArgs) || N <- ArgNos], WVA2];
+    ?WARN_ETS_LOOKUP_INSERT ->
+      [WVA1, WVA2, WVA3, WVA4] = WarnVarArgs,
+      ArgNos1 = lists_key_members_lists(WVA1, FunDefArgs),
+      ArgNos2 = lists_key_members_lists(WVA3, FunDefArgs),
+      [[lists_get(N1, FunCallArgs) || N1 <- ArgNos1], WVA2,
+       [lists_get(N2, FunCallArgs) || N2 <- ArgNos2], WVA4];
+    ?WARN_MNESIA_DIRTY_READ_WRITE ->
+      [WVA1, WVA2|T] = WarnVarArgs,
+      ArgNos = lists_key_members_lists(WVA1, FunDefArgs),
+      [[lists_get(N, FunCallArgs) || N <- ArgNos], WVA2|T]
+  end.
+
+var_type_analysis(FunDefArgs, FunCallTypes, WarnVarArgs, RaceWarnTag,
+                  RaceVarMap, CleanState) ->
+  FunVarArgs = format_args(FunDefArgs, FunCallTypes, CleanState, function_call),
+  case RaceWarnTag of
+    ?WARN_WHEREIS_REGISTER ->
+      [WVA1, WVA2, WVA3, WVA4] = WarnVarArgs,
+      Vars = find_all_bound_vars(WVA1, RaceVarMap),
+      case lists_key_member_lists(Vars, FunVarArgs) of
+        0 -> [Vars, WVA2, WVA3, WVA4];
+        N when is_integer(N) ->
+          NewWVA2 = string:tokens(lists:nth(N + 1, FunVarArgs), " |"),
+          [Vars, NewWVA2, WVA3, WVA4]
+      end;
+    ?WARN_WHEREIS_UNREGISTER ->
+      [WVA1, WVA2] = WarnVarArgs,
+      Vars = find_all_bound_vars(WVA1, RaceVarMap),
+      case lists_key_member_lists(Vars, FunVarArgs) of
+        0 -> [Vars, WVA2];
+        N when is_integer(N) ->
+          NewWVA2 = string:tokens(lists:nth(N + 1, FunVarArgs), " |"),
+          [Vars, NewWVA2]
+      end;
+    ?WARN_ETS_LOOKUP_INSERT ->
+      [WVA1, WVA2, WVA3, WVA4] = WarnVarArgs,
+      Vars1 = find_all_bound_vars(WVA1, RaceVarMap),
+      FirstVarArg =
+        case lists_key_member_lists(Vars1, FunVarArgs) of
+          0 -> [Vars1, WVA2];
+          N1 when is_integer(N1) ->
+            NewWVA2 = string:tokens(lists:nth(N1 + 1, FunVarArgs), " |"),
+            [Vars1, NewWVA2]
+        end,
+      Vars2 =
+        lists:flatten(
+          [find_all_bound_vars(A, RaceVarMap) || A <- ets_list_args(WVA3)]),
+      case lists_key_member_lists(Vars2, FunVarArgs) of
+        0 -> FirstVarArg ++ [Vars2, WVA4];
+        N2 when is_integer(N2) ->
+          NewWVA4 =
+            ets_tuple_argtypes2(
+            ets_tuple_argtypes1(lists:nth(N2 + 1, FunVarArgs), [], [], 0),
+            []),
+          FirstVarArg ++ [Vars2, NewWVA4]
+
+      end;
+    ?WARN_MNESIA_DIRTY_READ_WRITE ->
+      [WVA1, WVA2|T] = WarnVarArgs,
+      Arity =
+        case T of
+          [] -> 1;
+          _Else -> 2
+        end,
+      Vars = find_all_bound_vars(WVA1, RaceVarMap),
+      case lists_key_member_lists(Vars, FunVarArgs) of
+        0 -> [Vars, WVA2|T];
+        N when is_integer(N) ->
+          NewWVA2 =
+            case Arity of
+              1 ->
+                [mnesia_record_tab(R) || R <- string:tokens(
+                  lists:nth(2, FunVarArgs), " |")];
+              2 ->
+                string:tokens(lists:nth(N + 1, FunVarArgs), " |")
+            end,
+          [Vars, NewWVA2|T]
+      end
+  end.
+
+%%% ===========================================================================
+%%%
+%%%  Warning Format Utilities
+%%%
+%%% ===========================================================================
+
+add_race_warning(Warn, #races{race_warnings = Warns} = Races) ->
+  Races#races{race_warnings = [Warn|Warns]}.
+
+get_race_warn(Fun, Args, ArgTypes, DepList, State) ->
+  {M, F, _A} = Fun,
+  case DepList of
+    [] -> {State, no_race};
+    _Other ->
+      {State, {race_condition, [M, F, Args, ArgTypes, State, DepList]}}
+  end.
+
+-spec get_race_warnings(races(), dialyzer_dataflow:state()) ->
+  {races(), dialyzer_dataflow:state()}.
+
+get_race_warnings(#races{race_warnings = RaceWarnings}, State) ->
+  get_race_warnings_helper(RaceWarnings, State).
+
+get_race_warnings_helper(Warnings, State) ->
+  case Warnings of
+    [] ->
+      {dialyzer_dataflow:state__get_races(State), State};
+    [H|T] ->
+      {RaceWarnTag, WarningInfo, {race_condition, [M, F, A, AT, S, DepList]}} = H,
+      Reason =
+        case RaceWarnTag of
+          ?WARN_WHEREIS_REGISTER ->
+            get_reason(lists:keysort(7, DepList),
+                       "might fail due to a possible race condition "
+                       "caused by its combination with ");
+          ?WARN_WHEREIS_UNREGISTER ->
+            get_reason(lists:keysort(7, DepList),
+                       "might fail due to a possible race condition "
+                       "caused by its combination with ");
+          ?WARN_ETS_LOOKUP_INSERT ->
+            get_reason(lists:keysort(7, DepList),
+                       "might have an unintended effect due to " ++
+                       "a possible race condition " ++
+                       "caused by its combination with ");
+          ?WARN_MNESIA_DIRTY_READ_WRITE ->
+            get_reason(lists:keysort(7, DepList),
+                       "might have an unintended effect due to " ++
+                       "a possible race condition " ++
+                       "caused by its combination with ")
+        end,
+      W =
+        {?WARN_RACE_CONDITION, WarningInfo,
+         {race_condition,
+          [M, F, dialyzer_dataflow:format_args(A, AT, S), Reason]}},
+      get_race_warnings_helper(T,
+        dialyzer_dataflow:state__add_warning(W, State))
+  end.
+
+get_reason(DependencyList, Reason) ->
+  case DependencyList of
+    [] -> "";
+    [#dep_call{call_name = Call, arg_types = ArgTypes, vars = Args,
+               state = State, file_line = {File, Line}}|T] ->
+      R =
+        Reason ++
+        case Call of
+          whereis -> "the erlang:whereis";
+          ets_lookup -> "the ets:lookup";
+          mnesia_dirty_read -> "the mnesia:dirty_read"
+        end ++
+        dialyzer_dataflow:format_args(Args, ArgTypes, State) ++
+        " call in " ++
+        filename:basename(File) ++
+        " on line " ++
+        lists:flatten(io_lib:write(Line)),
+      case T of
+        [] -> R;
+        _ -> get_reason(T, R ++ ", ")
+      end
+  end.
+
+state__add_race_warning(State, RaceWarn, RaceWarnTag, WarningInfo) ->
+  case RaceWarn of
+    no_race -> State;
+    _Else ->
+      Races = dialyzer_dataflow:state__get_races(State),
+      Warn = {RaceWarnTag, WarningInfo, RaceWarn},
+      dialyzer_dataflow:state__put_races(add_race_warning(Warn, Races), State)
+  end.
+
+%%% ===========================================================================
+%%%
+%%%  Record Interfaces
+%%%
+%%% ===========================================================================
+
+-spec beg_clause_new(var_to_map1(), var_to_map1(), cerl:cerl()) ->
+   #beg_clause{}.
+
+beg_clause_new(Arg, Pats, Guard) ->
+  #beg_clause{arg = Arg, pats = Pats, guard = Guard}.
+
+-spec cleanup(races()) -> races().
+
+cleanup(#races{race_list = RaceList}) ->
+  #races{race_list = RaceList}.
+
+-spec end_case_new([#end_clause{}]) -> #end_case{}.
+
+end_case_new(Clauses) ->
+  #end_case{clauses = Clauses}.
+
+-spec end_clause_new(var_to_map1(), var_to_map1(), cerl:cerl()) ->
+   #end_clause{}.
+
+end_clause_new(Arg, Pats, Guard) ->
+  #end_clause{arg = Arg, pats = Pats, guard = Guard}.
+
+-spec get_curr_fun(races()) -> dialyzer_callgraph:mfa_or_funlbl().
+
+get_curr_fun(#races{curr_fun = CurrFun}) ->
+  CurrFun.
+
+-spec get_curr_fun_args(races()) -> core_args().
+
+get_curr_fun_args(#races{curr_fun_args = CurrFunArgs}) ->
+  CurrFunArgs.
+
+-spec get_new_table(races()) -> table().
+
+get_new_table(#races{new_table = Table}) ->
+  Table.
+
+-spec get_race_analysis(races()) -> boolean().
+
+get_race_analysis(#races{race_analysis = RaceAnalysis}) ->
+  RaceAnalysis.
+
+-spec get_race_list(races()) -> code().
+
+get_race_list(#races{race_list = RaceList}) ->
+  RaceList.
+
+-spec get_race_list_size(races()) -> non_neg_integer().
+
+get_race_list_size(#races{race_list_size = RaceListSize}) ->
+  RaceListSize.
+
+-spec get_race_list_and_size(races()) -> {code(), non_neg_integer()}.
+
+get_race_list_and_size(#races{race_list = RaceList,
+			      race_list_size = RaceListSize}) ->
+  {RaceList, RaceListSize}.
+
+-spec let_tag_new(var_to_map1(), var_to_map1()) -> #let_tag{}.
+
+let_tag_new(Var, Arg) ->
+  #let_tag{var = Var, arg = Arg}.
+
+-spec new() -> races().
+
+new() -> #races{}.
+
+-spec put_curr_fun(dialyzer_callgraph:mfa_or_funlbl(), label(), races()) ->
+  races().
+
+put_curr_fun(CurrFun, CurrFunLabel, Races) ->
+  Races#races{curr_fun = CurrFun,
+              curr_fun_label = CurrFunLabel,
+              curr_fun_args = empty}.
+
+-spec put_fun_args(core_args(), races()) -> races().
+
+put_fun_args(Args, #races{curr_fun_args = CurrFunArgs} = Races) ->
+  case CurrFunArgs of
+    empty -> Races#races{curr_fun_args = Args};
+    _Other -> Races
+  end.
+
+-spec put_race_analysis(boolean(), races()) ->
+  races().
+
+put_race_analysis(Analysis, Races) ->
+  Races#races{race_analysis = Analysis}.
+
+-spec put_race_list(code(), non_neg_integer(), races()) ->
+  races().
+
+put_race_list(RaceList, RaceListSize, Races) ->
+  Races#races{race_list = RaceList, race_list_size = RaceListSize}.
diff --git a/lib/dialyzer/test/opaque_SUITE_data/src/recrec/erl_types.erl b/lib/dialyzer/test/opaque_SUITE_data/src/recrec/erl_types.erl
new file mode 100644
index 0000000000..7826dada9d
--- /dev/null
+++ b/lib/dialyzer/test/opaque_SUITE_data/src/recrec/erl_types.erl
@@ -0,0 +1,5741 @@
+%% -*- erlang-indent-level: 2 -*-
+%%
+%% %CopyrightBegin%
+%%
+%% Copyright Ericsson AB 2003-2016. All Rights Reserved.
+%%
+%% Licensed under the Apache License, Version 2.0 (the "License");
+%% you may not use this file except in compliance with the License.
+%% You may obtain a copy of the License at
+%%
+%%     http://www.apache.org/licenses/LICENSE-2.0
+%%
+%% Unless required by applicable law or agreed to in writing, software
+%% distributed under the License is distributed on an "AS IS" BASIS,
+%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+%% See the License for the specific language governing permissions and
+%% limitations under the License.
+%%
+%% %CopyrightEnd%
+%%
+%% ======================================================================
+%% Copyright (C) 2000-2003 Richard Carlsson
+%%
+%% ======================================================================
+%% Provides a representation of Erlang types.
+%%
+%% The initial author of this file is Richard Carlsson (2000-2004).
+%% In July 2006, the type representation was totally re-designed by
+%% Tobias Lindahl. This is the representation which is used currently.
+%% In late 2008, Manouk Manoukian and Kostis Sagonas added support for
+%% opaque types to the structure-based representation of types.
+%% During February and March 2009, Kostis Sagonas significantly
+%% cleaned up the type representation and added spec declarations.
+%%
+%% Author contact: [email protected], [email protected], [email protected]
+%% ======================================================================
+
+-module(erl_types).
+
+-export([any_none/1,
+	 any_none_or_unit/1,
+	 lookup_record/3,
+	 max/2,
+	 min/2,
+	 number_max/1, number_max/2,
+	 number_min/1, number_min/2,
+	 t_abstract_records/2,
+	 t_any/0,
+	 t_arity/0,
+	 t_atom/0,
+	 t_atom/1,
+	 t_atoms/1,
+	 t_atom_vals/1, t_atom_vals/2,
+	 t_binary/0,
+	 t_bitstr/0,
+	 t_bitstr/2,
+	 t_bitstr_base/1,
+	 t_bitstr_concat/1,
+	 t_bitstr_concat/2,
+	 t_bitstr_match/2,
+	 t_bitstr_unit/1,
+	 t_bitstrlist/0,
+	 t_boolean/0,
+	 t_byte/0,
+	 t_char/0,
+	 t_collect_vars/1,
+	 t_cons/0,
+	 t_cons/2,
+	 t_cons_hd/1, t_cons_hd/2,
+	 t_cons_tl/1, t_cons_tl/2,
+         t_contains_opaque/1, t_contains_opaque/2,
+         t_decorate_with_opaque/3,
+	 t_elements/1,
+	 t_find_opaque_mismatch/3,
+         t_find_unknown_opaque/3,
+	 t_fixnum/0,
+	 t_map/2,
+	 t_non_neg_fixnum/0,
+	 t_pos_fixnum/0,
+	 t_float/0,
+         t_var_names/1,
+	 t_form_to_string/1,
+         t_from_form/6,
+         t_from_form_without_remote/3,
+         t_check_record_fields/6,
+	 t_from_range/2,
+	 t_from_range_unsafe/2,
+	 t_from_term/1,
+	 t_fun/0,
+	 t_fun/1,
+	 t_fun/2,
+	 t_fun_args/1, t_fun_args/2,
+	 t_fun_arity/1, t_fun_arity/2,
+	 t_fun_range/1, t_fun_range/2,
+	 t_has_opaque_subtype/2,
+	 t_has_var/1,
+	 t_identifier/0,
+	 %% t_improper_list/2,
+         t_inf/1,
+         t_inf/2,
+         t_inf/3,
+         t_inf_lists/2,
+         t_inf_lists/3,
+	 t_integer/0,
+	 t_integer/1,
+	 t_non_neg_integer/0,
+	 t_pos_integer/0,
+	 t_integers/1,
+	 t_iodata/0,
+	 t_iolist/0,
+	 t_is_any/1,
+	 t_is_atom/1, t_is_atom/2,
+	 t_is_any_atom/2, t_is_any_atom/3,
+	 t_is_binary/1, t_is_binary/2,
+	 t_is_bitstr/1, t_is_bitstr/2,
+	 t_is_bitwidth/1,
+	 t_is_boolean/1, t_is_boolean/2,
+	 %% t_is_byte/1,
+	 %% t_is_char/1,
+	 t_is_cons/1, t_is_cons/2,
+	 t_is_equal/2,
+	 t_is_fixnum/1,
+	 t_is_float/1, t_is_float/2,
+	 t_is_fun/1, t_is_fun/2,
+	 t_is_instance/2,
+	 t_is_integer/1, t_is_integer/2,
+	 t_is_list/1,
+	 t_is_map/1,
+	 t_is_map/2,
+	 t_is_matchstate/1,
+	 t_is_nil/1, t_is_nil/2,
+	 t_is_non_neg_integer/1,
+	 t_is_none/1,
+	 t_is_none_or_unit/1,
+	 t_is_number/1, t_is_number/2,
+	 t_is_opaque/1, t_is_opaque/2,
+	 t_is_pid/1, t_is_pid/2,
+	 t_is_port/1, t_is_port/2,
+	 t_is_maybe_improper_list/1, t_is_maybe_improper_list/2,
+	 t_is_reference/1, t_is_reference/2,
+	 t_is_singleton/1,
+	 t_is_singleton/2,
+	 t_is_string/1,
+	 t_is_subtype/2,
+	 t_is_tuple/1, t_is_tuple/2,
+	 t_is_unit/1,
+	 t_is_var/1,
+	 t_limit/2,
+	 t_list/0,
+	 t_list/1,
+	 t_list_elements/1, t_list_elements/2,
+	 t_list_termination/1, t_list_termination/2,
+	 t_map/0,
+	 t_map/1,
+	 t_map/3,
+	 t_map_entries/2, t_map_entries/1,
+	 t_map_def_key/2, t_map_def_key/1,
+	 t_map_def_val/2, t_map_def_val/1,
+	 t_map_get/2, t_map_get/3,
+	 t_map_is_key/2, t_map_is_key/3,
+	 t_map_update/2, t_map_update/3,
+	 t_map_put/2, t_map_put/3,
+	 t_matchstate/0,
+	 t_matchstate/2,
+	 t_matchstate_present/1,
+	 t_matchstate_slot/2,
+	 t_matchstate_slots/1,
+	 t_matchstate_update_present/2,
+	 t_matchstate_update_slot/3,
+	 t_mfa/0,
+	 t_module/0,
+	 t_nil/0,	 
+	 t_node/0,
+	 t_none/0,
+	 t_nonempty_list/0,
+	 t_nonempty_list/1,
+	 t_nonempty_string/0,
+	 t_number/0,
+	 t_number/1,
+	 t_number_vals/1, t_number_vals/2,
+	 t_opaque_from_records/1,
+	 t_opaque_structure/1,
+	 t_pid/0,
+	 t_port/0,
+	 t_maybe_improper_list/0,
+	 %% t_maybe_improper_list/2,
+	 t_product/1,
+	 t_reference/0,
+	 t_singleton_to_term/2,
+	 t_string/0,
+	 t_struct_from_opaque/2,
+	 t_subst/2,
+	 t_subtract/2,
+	 t_subtract_list/2,
+	 t_sup/1,
+	 t_sup/2,
+	 t_timeout/0,
+	 t_to_string/1,
+	 t_to_string/2,
+	 t_to_tlist/1,
+	 t_tuple/0,
+	 t_tuple/1,
+	 t_tuple_args/1, t_tuple_args/2,
+	 t_tuple_size/1, t_tuple_size/2,
+	 t_tuple_sizes/1,
+	 t_tuple_subtypes/1,
+         t_tuple_subtypes/2,
+	 t_unify/2,
+	 t_unit/0,
+	 t_unopaque/1, t_unopaque/2,
+	 t_var/1,
+	 t_var_name/1,
+	 %% t_assign_variables_to_subtype/2,
+	 type_is_defined/4,
+	 record_field_diffs_to_string/2,
+	 subst_all_vars_to_any/1,
+         lift_list_to_pos_empty/1, lift_list_to_pos_empty/2,
+         is_opaque_type/2,
+	 is_erl_type/1,
+	 atom_to_string/1,
+	 var_table__new/0,
+         cache__new/0,
+	 map_pairwise_merge/3
+	]).
+
+%%-define(DO_ERL_TYPES_TEST, true).
+-compile({no_auto_import,[min/2,max/2]}).
+
+-ifdef(DO_ERL_TYPES_TEST).
+-export([test/0]).
+-else.
+-define(NO_UNUSED, true).
+-endif.
+
+-ifndef(NO_UNUSED).
+-export([t_is_identifier/1]).
+-endif.
+
+-export_type([erl_type/0, opaques/0, type_table/0, var_table/0, cache/0]).
+
+%%-define(DEBUG, true).
+
+-ifdef(DEBUG).
+-define(debug(__A), __A).
+-else.
+-define(debug(__A), ok).
+-endif.
+
+%%=============================================================================
+%%
+%% Definition of the type structure
+%%
+%%=============================================================================
+
+%%-----------------------------------------------------------------------------
+%% Limits
+%%
+
+-define(REC_TYPE_LIMIT, 2).
+-define(EXPAND_DEPTH, 16).
+-define(EXPAND_LIMIT, 10000).
+
+-define(TUPLE_TAG_LIMIT, 5).
+-define(TUPLE_ARITY_LIMIT, 8).
+-define(SET_LIMIT, 13).
+-define(MAX_BYTE, 255).
+-define(MAX_CHAR, 16#10ffff).
+
+-define(UNIT_MULTIPLIER, 8).
+
+-define(TAG_IMMED1_SIZE, 4).
+-define(BITS, (erlang:system_info(wordsize) * 8) - ?TAG_IMMED1_SIZE).
+
+-define(MAX_TUPLE_SIZE, (1 bsl 10)).
+
+%%-----------------------------------------------------------------------------
+%% Type tags and qualifiers
+%%
+
+-define(atom_tag,       atom).
+-define(binary_tag,     binary).
+-define(function_tag,   function).
+-define(identifier_tag, identifier).
+-define(list_tag,       list).
+-define(map_tag,        map).
+-define(matchstate_tag, matchstate).
+-define(nil_tag,        nil).
+-define(number_tag,     number).
+-define(opaque_tag,     opaque).
+-define(product_tag,    product).
+-define(tuple_set_tag,  tuple_set).
+-define(tuple_tag,      tuple).
+-define(union_tag,      union).
+-define(var_tag,        var).
+
+-type tag()  :: ?atom_tag | ?binary_tag | ?function_tag | ?identifier_tag
+              | ?list_tag | ?map_tag | ?matchstate_tag | ?nil_tag | ?number_tag
+              | ?opaque_tag | ?product_tag
+              | ?tuple_tag | ?tuple_set_tag | ?union_tag | ?var_tag.
+
+-define(float_qual,     float).
+-define(integer_qual,   integer).
+-define(nonempty_qual,  nonempty).
+-define(pid_qual,       pid).
+-define(port_qual,      port).
+-define(reference_qual, reference).
+-define(unknown_qual,   unknown).
+
+-type qual() :: ?float_qual | ?integer_qual | ?nonempty_qual | ?pid_qual
+              | ?port_qual | ?reference_qual | ?unknown_qual | {_, _}.
+
+%%-----------------------------------------------------------------------------
+%% The type representation
+%%
+
+-define(any,  any).
+-define(none, none).
+-define(unit, unit).
+%% Generic constructor - elements can be many things depending on the tag.
+-record(c, {tag			      :: tag(),
+	    elements  = []	      :: term(),
+	    qualifier = ?unknown_qual :: qual()}).
+
+-opaque erl_type() :: ?any | ?none | ?unit | #c{}.
+
+%%-----------------------------------------------------------------------------
+%% Auxiliary types and convenient macros
+%%
+
+-type parse_form() :: erl_parse:abstract_type().
+-type rng_elem()   :: 'pos_inf' | 'neg_inf' | integer().
+
+-record(int_set, {set :: [integer()]}).
+-record(int_rng, {from :: rng_elem(), to :: rng_elem()}).
+%% Note: the definition of #opaque{} was changed to 'mod' and 'name';
+%% it used to be an ordsets of {Mod, Name} pairs. The Dialyzer version
+%% was updated to 2.7 due to this change.
+-record(opaque,  {mod :: module(), name :: atom(),
+		  args = [] :: [erl_type()], struct :: erl_type()}).
+
+-define(atom(Set),                 #c{tag=?atom_tag, elements=Set}).
+-define(bitstr(Unit, Base),        #c{tag=?binary_tag, elements=[Unit,Base]}).
+-define(float,                     ?number(?any, ?float_qual)).
+-define(function(Domain, Range),   #c{tag=?function_tag, 
+				      elements=[Domain, Range]}).
+-define(identifier(Types),         #c{tag=?identifier_tag, elements=Types}).
+-define(integer(Types),            ?number(Types, ?integer_qual)).
+-define(int_range(From, To),       ?integer(#int_rng{from=From, to=To})).
+-define(int_set(Set),              ?integer(#int_set{set=Set})).
+-define(list(Types, Term, Size),   #c{tag=?list_tag, elements=[Types,Term],
+				      qualifier=Size}).
+-define(nil,                       #c{tag=?nil_tag}).
+-define(nonempty_list(Types, Term),?list(Types, Term, ?nonempty_qual)).
+-define(number(Set, Qualifier),    #c{tag=?number_tag, elements=Set, 
+				      qualifier=Qualifier}).
+-define(map(Pairs,DefKey,DefVal),
+	#c{tag=?map_tag, elements={Pairs,DefKey,DefVal}}).
+-define(opaque(Optypes),           #c{tag=?opaque_tag, elements=Optypes}).
+-define(product(Types),            #c{tag=?product_tag, elements=Types}).
+-define(tuple(Types, Arity, Qual), #c{tag=?tuple_tag, elements=Types, 
+				      qualifier={Arity, Qual}}).
+-define(tuple_set(Tuples),         #c{tag=?tuple_set_tag, elements=Tuples}).
+-define(var(Id),                   #c{tag=?var_tag, elements=Id}).
+
+-define(matchstate(P, Slots),	   #c{tag=?matchstate_tag, elements=[P,Slots]}).
+-define(any_matchstate,            ?matchstate(t_bitstr(), ?any)).
+
+-define(byte,                      ?int_range(0, ?MAX_BYTE)).
+-define(char,                      ?int_range(0, ?MAX_CHAR)).
+-define(integer_pos,               ?int_range(1, pos_inf)).
+-define(integer_non_neg,           ?int_range(0, pos_inf)).
+-define(integer_neg,               ?int_range(neg_inf, -1)).
+
+-type opaques() :: [erl_type()] | 'universe'.
+
+-type record_key()   :: {'record', atom()}.
+-type type_key()     :: {'type' | 'opaque', mfa()}.
+-type record_value() :: [{atom(), erl_parse:abstract_expr(), erl_type()}].
+-type type_value()   :: {{module(), {file:name(), erl_anno:line()},
+                          erl_parse:abstract_type(), ArgNames :: [atom()]},
+                         erl_type()}.
+-type type_table() :: dict:dict(record_key() | type_key(),
+                                record_value() | type_value()).
+
+-opaque var_table() :: #{atom() => erl_type()}.
+
+%%-----------------------------------------------------------------------------
+%% Unions
+%%
+
+-define(union(List), #c{tag=?union_tag, elements=[_,_,_,_,_,_,_,_,_,_]=List}).
+
+-define(atom_union(T),       ?union([T,?none,?none,?none,?none,?none,?none,?none,?none,?none])).
+-define(bitstr_union(T),     ?union([?none,T,?none,?none,?none,?none,?none,?none,?none,?none])).
+-define(function_union(T),   ?union([?none,?none,T,?none,?none,?none,?none,?none,?none,?none])).
+-define(identifier_union(T), ?union([?none,?none,?none,T,?none,?none,?none,?none,?none,?none])).
+-define(list_union(T),       ?union([?none,?none,?none,?none,T,?none,?none,?none,?none,?none])).
+-define(number_union(T),     ?union([?none,?none,?none,?none,?none,T,?none,?none,?none,?none])).
+-define(tuple_union(T),      ?union([?none,?none,?none,?none,?none,?none,T,?none,?none,?none])).
+-define(matchstate_union(T), ?union([?none,?none,?none,?none,?none,?none,?none,T,?none,?none])).
+-define(opaque_union(T),     ?union([?none,?none,?none,?none,?none,?none,?none,?none,T,?none])).
+-define(map_union(T),        ?union([?none,?none,?none,?none,?none,?none,?none,?none,?none,T])).
+-define(integer_union(T),    ?number_union(T)).
+-define(float_union(T),      ?number_union(T)).
+-define(nil_union(T),        ?list_union(T)).
+
+
+%%=============================================================================
+%%
+%% Primitive operations such as type construction and type tests
+%%
+%%=============================================================================
+
+%%-----------------------------------------------------------------------------
+%% Top and bottom
+%%
+
+-spec t_any() -> erl_type().
+
+t_any() ->
+  ?any.
+
+-spec t_is_any(erl_type()) -> boolean().
+
+t_is_any(Type) ->
+  do_opaque(Type, 'universe', fun is_any/1).
+
+is_any(?any) -> true;
+is_any(_) -> false.
+
+-spec t_none() -> erl_type().
+
+t_none() ->
+  ?none.
+
+-spec t_is_none(erl_type()) -> boolean().
+
+t_is_none(?none) -> true;
+t_is_none(_) -> false.
+
+%%-----------------------------------------------------------------------------
+%% Opaque types
+%%
+
+-spec t_opaque(module(), atom(), [_], erl_type()) -> erl_type().
+
+t_opaque(Mod, Name, Args, Struct) ->
+  O = #opaque{mod = Mod, name = Name, args = Args, struct = Struct},
+  ?opaque(set_singleton(O)).
+
+-spec t_is_opaque(erl_type(), [erl_type()]) -> boolean().
+
+t_is_opaque(?opaque(_) = Type, Opaques) ->
+  not is_opaque_type(Type, Opaques);
+t_is_opaque(_Type, _Opaques) -> false.
+
+-spec t_is_opaque(erl_type()) -> boolean().
+
+t_is_opaque(?opaque(_)) -> true;
+t_is_opaque(_) -> false.
+
+-spec t_has_opaque_subtype(erl_type(), opaques()) -> boolean().
+
+t_has_opaque_subtype(Type, Opaques) ->
+  do_opaque(Type, Opaques, fun has_opaque_subtype/1).
+
+has_opaque_subtype(?union(Ts)) ->
+  lists:any(fun t_is_opaque/1, Ts);
+has_opaque_subtype(T) ->
+  t_is_opaque(T).
+
+-spec t_opaque_structure(erl_type()) -> erl_type().
+
+t_opaque_structure(?opaque(Elements)) ->
+  t_sup([Struct || #opaque{struct = Struct} <- ordsets:to_list(Elements)]).
+
+-spec t_contains_opaque(erl_type()) -> boolean().
+
+t_contains_opaque(Type) ->
+  t_contains_opaque(Type, []).
+
+%% Returns 'true' iff there is an opaque type that is *not* one of
+%% the types of the second argument.
+
+-spec t_contains_opaque(erl_type(), [erl_type()]) -> boolean().
+
+t_contains_opaque(?any, _Opaques) -> false;
+t_contains_opaque(?none, _Opaques) -> false;
+t_contains_opaque(?unit, _Opaques) -> false;
+t_contains_opaque(?atom(_Set), _Opaques) -> false;
+t_contains_opaque(?bitstr(_Unit, _Base), _Opaques) -> false;
+t_contains_opaque(?float, _Opaques) -> false;
+t_contains_opaque(?function(Domain, Range), Opaques) ->
+  t_contains_opaque(Domain, Opaques)
+  orelse t_contains_opaque(Range, Opaques);
+t_contains_opaque(?identifier(_Types), _Opaques) -> false;
+t_contains_opaque(?integer(_Types), _Opaques) -> false;
+t_contains_opaque(?int_range(_From, _To), _Opaques) -> false;
+t_contains_opaque(?int_set(_Set), _Opaques) -> false;
+t_contains_opaque(?list(Type, Tail, _), Opaques) ->
+  t_contains_opaque(Type, Opaques) orelse t_contains_opaque(Tail, Opaques);
+t_contains_opaque(?map(_, _, _) = Map, Opaques) ->
+  list_contains_opaque(map_all_types(Map), Opaques);
+t_contains_opaque(?matchstate(_P, _Slots), _Opaques) -> false;
+t_contains_opaque(?nil, _Opaques) -> false;
+t_contains_opaque(?number(_Set, _Tag), _Opaques) -> false;
+t_contains_opaque(?opaque(_)=T, Opaques) ->
+  not is_opaque_type(T, Opaques)
+  orelse t_contains_opaque(t_opaque_structure(T));
+t_contains_opaque(?product(Types), Opaques) ->
+  list_contains_opaque(Types, Opaques);
+t_contains_opaque(?tuple(?any, _, _), _Opaques) -> false;
+t_contains_opaque(?tuple(Types, _, _), Opaques) ->
+  list_contains_opaque(Types, Opaques);
+t_contains_opaque(?tuple_set(_Set) = T, Opaques) ->
+  list_contains_opaque(t_tuple_subtypes(T), Opaques);
+t_contains_opaque(?union(List), Opaques) ->
+  list_contains_opaque(List, Opaques);
+t_contains_opaque(?var(_Id), _Opaques) -> false.
+
+-spec list_contains_opaque([erl_type()], [erl_type()]) -> boolean().
+
+list_contains_opaque(List, Opaques) ->
+  lists:any(fun(E) -> t_contains_opaque(E, Opaques) end, List).
+
+%% t_find_opaque_mismatch/2 of two types should only be used if their
+%% t_inf is t_none() due to some opaque type violation.
+%%
+%% The first argument of the function is the pattern and its second
+%% argument the type we are matching against the pattern.
+
+-spec t_find_opaque_mismatch(erl_type(), erl_type(), [erl_type()]) ->
+                                'error' | {'ok', erl_type(), erl_type()}.
+
+t_find_opaque_mismatch(T1, T2, Opaques) ->
+  t_find_opaque_mismatch(T1, T2, T2, Opaques).
+
+t_find_opaque_mismatch(?any, _Type, _TopType, _Opaques) -> error;
+t_find_opaque_mismatch(?none, _Type, _TopType, _Opaques) -> error;
+t_find_opaque_mismatch(?list(T1, Tl1, _), ?list(T2, Tl2, _), TopType, Opaques) ->
+  t_find_opaque_mismatch_ordlists([T1, Tl1], [T2, Tl2], TopType, Opaques);
+t_find_opaque_mismatch(T1, ?opaque(_) = T2, TopType, Opaques) ->
+  case is_opaque_type(T2, Opaques) of
+    false -> {ok, TopType, T2};
+    true ->
+      t_find_opaque_mismatch(T1, t_opaque_structure(T2), TopType, Opaques)
+  end;
+t_find_opaque_mismatch(?opaque(_) = T1, T2, TopType, Opaques) ->
+  %% The generated message is somewhat misleading:
+  case is_opaque_type(T1, Opaques) of
+    false -> {ok, TopType, T1};
+    true ->
+      t_find_opaque_mismatch(t_opaque_structure(T1), T2, TopType, Opaques)
+  end;
+t_find_opaque_mismatch(?product(T1), ?product(T2), TopType, Opaques) ->
+  t_find_opaque_mismatch_ordlists(T1, T2, TopType, Opaques);
+t_find_opaque_mismatch(?tuple(T1, Arity, _), ?tuple(T2, Arity, _),
+                       TopType, Opaques) ->
+  t_find_opaque_mismatch_ordlists(T1, T2, TopType, Opaques);
+t_find_opaque_mismatch(?tuple(_, _, _) = T1, ?tuple_set(_) = T2,
+                       TopType, Opaques) ->
+  Tuples1 = t_tuple_subtypes(T1),
+  Tuples2 = t_tuple_subtypes(T2),
+  t_find_opaque_mismatch_lists(Tuples1, Tuples2, TopType, Opaques);
+t_find_opaque_mismatch(T1, ?union(U2), TopType, Opaques) ->
+  t_find_opaque_mismatch_lists([T1], U2, TopType, Opaques);
+t_find_opaque_mismatch(_T1, _T2, _TopType, _Opaques) -> error.
+
+t_find_opaque_mismatch_ordlists(L1, L2, TopType, Opaques) ->
+  List = lists:zipwith(fun(T1, T2) ->
+			   t_find_opaque_mismatch(T1, T2, TopType, Opaques)
+		       end, L1, L2),
+  t_find_opaque_mismatch_list(List).
+
+t_find_opaque_mismatch_lists(L1, L2, _TopType, Opaques) ->
+  List = [t_find_opaque_mismatch(T1, T2, T2, Opaques) || T1 <- L1, T2 <- L2],
+  t_find_opaque_mismatch_list(List).
+
+t_find_opaque_mismatch_list([]) -> error;
+t_find_opaque_mismatch_list([H|T]) ->
+  case H of
+    {ok, _T1, _T2} -> H;
+    error -> t_find_opaque_mismatch_list(T)
+  end.
+
+-spec t_find_unknown_opaque(erl_type(), erl_type(), opaques()) ->
+                               [pos_integer()].
+
+%% The nice thing about using two types and t_inf() as compared to
+%% calling t_contains_opaque/2 is that the traversal stops when
+%% there is a mismatch which means that unknown opaque types "below"
+%% the mismatch are not found.
+t_find_unknown_opaque(_T1, _T2, 'universe') -> [];
+t_find_unknown_opaque(T1, T2, Opaques) ->
+  try t_inf(T1, T2, {match, Opaques}) of
+    _ -> []
+  catch throw:{pos, Ns} -> Ns
+  end.
+
+-spec t_decorate_with_opaque(erl_type(), erl_type(), [erl_type()]) -> erl_type().
+
+%% The first argument can contain opaque types. The second argument
+%% is assumed to be taken from the contract.
+
+t_decorate_with_opaque(T1, T2, Opaques) ->
+  case t_is_equal(T1, T2) orelse not t_contains_opaque(T2) of
+    true -> T1;
+    false ->
+      T = t_inf(T1, T2),
+      case t_contains_opaque(T) of
+        false -> T1;
+        true ->
+          R = decorate(T1, T, Opaques),
+          ?debug(case catch t_is_equal(t_unopaque(R), t_unopaque(T1)) of
+                   true -> ok;
+                   false ->
+                     io:format("T1 = ~p,\n", [T1]),
+                     io:format("T2 = ~p,\n", [T2]),
+                     io:format("O = ~p,\n", [Opaques]),
+                     io:format("erl_types:t_decorate_with_opaque(T1,T2,O).\n"),
+                     throw({error, "Failed to handle opaque types"})
+                 end),
+          R
+      end
+  end.
+
+decorate(Type, ?none, _Opaques) -> Type;
+decorate(?function(Domain, Range), ?function(D, R), Opaques) ->
+  ?function(decorate(Domain, D, Opaques), decorate(Range, R, Opaques));
+decorate(?list(Types, Tail, Size), ?list(Ts, Tl, _Sz), Opaques) ->
+  ?list(decorate(Types, Ts, Opaques), decorate(Tail, Tl, Opaques), Size);
+decorate(?product(Types), ?product(Ts), Opaques) ->
+  ?product(list_decorate(Types, Ts, Opaques));
+decorate(?tuple(_, _, _)=T, ?tuple(?any, _, _), _Opaques) -> T;
+decorate(?tuple(?any, _, _)=T, ?tuple(_, _, _), _Opaques) -> T;
+decorate(?tuple(Types, Arity, Tag), ?tuple(Ts, Arity, _), Opaques) ->
+  ?tuple(list_decorate(Types, Ts, Opaques), Arity, Tag);
+decorate(?tuple_set(List), ?tuple(_, Arity, _) = T, Opaques) ->
+  decorate_tuple_sets(List, [{Arity, [T]}], Opaques);
+decorate(?tuple_set(List), ?tuple_set(L), Opaques) ->
+  decorate_tuple_sets(List, L, Opaques);
+decorate(?union(List), T, Opaques) when T =/= ?any ->
+  ?union(L) = force_union(T),
+  union_decorate(List, L, Opaques);
+decorate(?opaque(_)=T, _, _Opaques) -> T;
+decorate(T, ?union(L), Opaques) when T =/= ?any ->
+  ?union(List) = force_union(T),
+  union_decorate(List, L, Opaques);
+decorate(Type, ?opaque(_)=T, Opaques) ->
+  decorate_with_opaque(Type, T, Opaques);
+decorate(Type, _T, _Opaques) -> Type.
+
+%% Note: it is important that #opaque.struct is a subtype of the
+%% opaque type.
+decorate_with_opaque(Type, ?opaque(Set2), Opaques) ->
+  case decoration(set_to_list(Set2), Type, Opaques, [], false) of
+    {[], false} -> Type;
+    {List, All} when List =/= [] ->
+      NewType = ?opaque(ordsets:from_list(List)),
+      case All of
+        true -> NewType;
+        false -> t_sup(NewType, Type)
+      end
+  end.
+
+decoration([#opaque{struct = S} = Opaque|OpaqueTypes], Type, Opaques,
+           NewOpaqueTypes0, All) ->
+  IsOpaque = is_opaque_type2(Opaque, Opaques),
+  I = t_inf(Type, S),
+  case not IsOpaque orelse t_is_none(I) of
+    true -> decoration(OpaqueTypes, Type, Opaques, NewOpaqueTypes0, All);
+    false ->
+      NewOpaque = Opaque#opaque{struct = decorate(I, S, Opaques)},
+      NewAll = All orelse t_is_equal(I, Type),
+      NewOpaqueTypes = [NewOpaque|NewOpaqueTypes0],
+      decoration(OpaqueTypes, Type, Opaques, NewOpaqueTypes, NewAll)
+  end;
+decoration([], _Type, _Opaques, NewOpaqueTypes, All) ->
+  {NewOpaqueTypes, All}.
+
+-spec list_decorate([erl_type()], [erl_type()], opaques()) -> [erl_type()].
+
+list_decorate(List, L, Opaques) ->
+  [decorate(Elem, E, Opaques) || {Elem, E} <- lists:zip(List, L)].
+
+union_decorate(U1, U2, Opaques) ->
+  Union = union_decorate(U1, U2, Opaques, 0, []),
+  [A,B,F,I,L,N,T,M,_,Map] = U1,
+  [_,_,_,_,_,_,_,_,Opaque,_] = U2,
+  List = [A,B,F,I,L,N,T,M,Map],
+  DecList = [Dec ||
+              E <- List,
+              not t_is_none(E),
+              not t_is_none(Dec = decorate(E, Opaque, Opaques))],
+  t_sup([Union|DecList]).
+
+union_decorate([?none|Left1], [_|Left2], Opaques, N, Acc) ->
+  union_decorate(Left1, Left2, Opaques, N, [?none|Acc]);
+union_decorate([T1|Left1], [?none|Left2], Opaques, N, Acc) ->
+  union_decorate(Left1, Left2, Opaques, N+1, [T1|Acc]);
+union_decorate([T1|Left1], [T2|Left2], Opaques, N, Acc) ->
+  union_decorate(Left1, Left2, Opaques, N+1, [decorate(T1, T2, Opaques)|Acc]);
+union_decorate([], [], _Opaques, N, Acc) ->
+  if N =:= 0 -> ?none;
+     N =:= 1 ->
+      [Type] = [T || T <- Acc, T =/= ?none],
+      Type;
+     N >= 2  -> ?union(lists:reverse(Acc))
+  end.
+
+decorate_tuple_sets(List, L, Opaques) ->
+  decorate_tuple_sets(List, L, Opaques, []).
+
+decorate_tuple_sets([{Arity, Tuples}|List], [{Arity, Ts}|L], Opaques, Acc) ->
+  DecTs = decorate_tuples_in_sets(Tuples, Ts, Opaques),
+  decorate_tuple_sets(List, L, Opaques, [{Arity, DecTs}|Acc]);
+decorate_tuple_sets([ArTup|List], L, Opaques, Acc) ->
+  decorate_tuple_sets(List, L, Opaques, [ArTup|Acc]);
+decorate_tuple_sets([], _L, _Opaques, Acc) ->
+  ?tuple_set(lists:reverse(Acc)).
+
+decorate_tuples_in_sets([?tuple(Elements, _, ?any)], Ts, Opaques) ->
+  NewList = [list_decorate(Elements, Es, Opaques) || ?tuple(Es, _, _) <- Ts],
+  case t_sup([t_tuple(Es) || Es <- NewList]) of
+    ?tuple_set([{_Arity, Tuples}]) -> Tuples;
+    ?tuple(_, _, _)=Tuple -> [Tuple]
+  end;
+decorate_tuples_in_sets(Tuples, Ts, Opaques) ->
+  decorate_tuples_in_sets(Tuples, Ts, Opaques, []).
+
+decorate_tuples_in_sets([?tuple(Elements, Arity, Tag1) = T1|Tuples] = L1,
+                        [?tuple(Es, Arity, Tag2)|Ts] = L2, Opaques, Acc) ->
+  if
+    Tag1 < Tag2   -> decorate_tuples_in_sets(Tuples, L2, Opaques, [T1|Acc]);
+    Tag1 > Tag2   -> decorate_tuples_in_sets(L1, Ts, Opaques, Acc);
+    Tag1 =:= Tag2 ->
+      NewElements = list_decorate(Elements, Es, Opaques),
+      NewAcc = [?tuple(NewElements, Arity, Tag1)|Acc],
+      decorate_tuples_in_sets(Tuples, Ts, Opaques, NewAcc)
+  end;
+decorate_tuples_in_sets([T1|Tuples], L2, Opaques, Acc) ->
+  decorate_tuples_in_sets(Tuples, L2, Opaques, [T1|Acc]);
+decorate_tuples_in_sets([], _L, _Opaques, Acc) ->
+  lists:reverse(Acc).
+
+-spec t_opaque_from_records(type_table()) -> [erl_type()].
+
+t_opaque_from_records(RecDict) ->
+  OpaqueRecDict =
+    dict:filter(fun(Key, _Value) ->
+		    case Key of
+		      {opaque, _Name, _Arity} -> true;
+		      _  -> false
+		    end
+		end, RecDict),
+  OpaqueTypeDict =
+    dict:map(fun({opaque, Name, _Arity},
+                 {{Module, _FileLine, _Form, ArgNames}, _Type}) ->
+                 %% Args = args_to_types(ArgNames),
+                 %% List = lists:zip(ArgNames, Args),
+                 %% TmpVarTab = maps:to_list(List),
+                 %% Rep = t_from_form(Type, RecDict, TmpVarTab),
+                 Rep = t_any(), % not used for anything right now
+                 Args = [t_any() || _ <- ArgNames],
+                 t_opaque(Module, Name, Args, Rep)
+	     end, OpaqueRecDict),
+  [OpaqueType || {_Key, OpaqueType} <- dict:to_list(OpaqueTypeDict)].
+
+%% Decompose opaque instances of type arg2 to structured types, in arg1
+%% XXX: Same as t_unopaque
+-spec t_struct_from_opaque(erl_type(), [erl_type()]) -> erl_type().
+
+t_struct_from_opaque(?function(Domain, Range), Opaques) ->
+  ?function(t_struct_from_opaque(Domain, Opaques),
+	    t_struct_from_opaque(Range, Opaques));
+t_struct_from_opaque(?list(Types, Term, Size), Opaques) ->
+  ?list(t_struct_from_opaque(Types, Opaques),
+        t_struct_from_opaque(Term, Opaques), Size);
+t_struct_from_opaque(?opaque(_) = T, Opaques) ->
+  case is_opaque_type(T, Opaques) of
+    true  -> t_opaque_structure(T);
+    false -> T
+  end;
+t_struct_from_opaque(?product(Types), Opaques) ->
+  ?product(list_struct_from_opaque(Types, Opaques));
+t_struct_from_opaque(?tuple(?any, _, _) = T, _Opaques) -> T;
+t_struct_from_opaque(?tuple(Types, Arity, Tag), Opaques) ->
+  ?tuple(list_struct_from_opaque(Types, Opaques), Arity, Tag);
+t_struct_from_opaque(?tuple_set(Set), Opaques) ->
+  NewSet = [{Sz, [t_struct_from_opaque(T, Opaques) || T <- Tuples]}
+	    || {Sz, Tuples} <- Set],
+  ?tuple_set(NewSet);
+t_struct_from_opaque(?union(List), Opaques) ->
+  t_sup(list_struct_from_opaque(List, Opaques));
+t_struct_from_opaque(Type, _Opaques) -> Type.
+
+list_struct_from_opaque(Types, Opaques) ->
+  [t_struct_from_opaque(Type, Opaques) || Type <- Types].
+
+%%-----------------------------------------------------------------------------
+
+-type mod_records() :: dict:dict(module(), type_table()).
+
+%%-----------------------------------------------------------------------------
+%% Unit type. Signals non termination.
+%%
+
+-spec t_unit() -> erl_type().
+
+t_unit() ->
+  ?unit.
+
+-spec t_is_unit(erl_type()) -> boolean().
+
+t_is_unit(?unit) -> true;
+t_is_unit(_) -> false.
+
+-spec t_is_none_or_unit(erl_type()) -> boolean().
+
+t_is_none_or_unit(?none) -> true;
+t_is_none_or_unit(?unit) -> true;
+t_is_none_or_unit(_) -> false.
+
+%%-----------------------------------------------------------------------------
+%% Atoms and the derived type boolean
+%%
+
+-spec t_atom() -> erl_type().
+
+t_atom() ->
+  ?atom(?any).
+
+-spec t_atom(atom()) -> erl_type().
+
+t_atom(A) when is_atom(A) ->
+  ?atom(set_singleton(A)).
+
+-spec t_atoms([atom()]) -> erl_type().
+
+t_atoms(List) when is_list(List) ->
+  t_sup([t_atom(A) || A <- List]).
+
+-spec t_atom_vals(erl_type()) -> 'unknown' | [atom(),...].
+
+t_atom_vals(Type) ->
+  t_atom_vals(Type, 'universe').
+
+-spec t_atom_vals(erl_type(), opaques()) -> 'unknown' | [atom(),...].
+
+t_atom_vals(Type, Opaques) ->
+  do_opaque(Type, Opaques, fun atom_vals/1).
+
+atom_vals(?atom(?any)) -> unknown;
+atom_vals(?atom(Set)) -> set_to_list(Set);
+atom_vals(?opaque(_)) -> unknown;
+atom_vals(Other) ->
+  ?atom(_) = Atm = t_inf(t_atom(), Other),
+  atom_vals(Atm).
+
+-spec t_is_atom(erl_type()) -> boolean().
+
+t_is_atom(Type) ->
+  t_is_atom(Type, 'universe').
+
+-spec t_is_atom(erl_type(), opaques()) -> boolean().
+
+t_is_atom(Type, Opaques) ->
+  do_opaque(Type, Opaques, fun is_atom1/1).
+
+is_atom1(?atom(_)) -> true;
+is_atom1(_) -> false.
+
+-spec t_is_any_atom(atom(), erl_type()) -> boolean().
+
+t_is_any_atom(Atom, SomeAtomsType) ->
+  t_is_any_atom(Atom, SomeAtomsType, 'universe').
+
+-spec t_is_any_atom(atom(), erl_type(), opaques()) -> boolean().
+
+t_is_any_atom(Atom, SomeAtomsType, Opaques) ->
+  do_opaque(SomeAtomsType, Opaques,
+            fun(AtomsType) -> is_any_atom(Atom, AtomsType) end).
+
+is_any_atom(Atom, ?atom(?any)) when is_atom(Atom) -> false;
+is_any_atom(Atom, ?atom(Set)) when is_atom(Atom) ->
+  set_is_singleton(Atom, Set);
+is_any_atom(Atom, _) when is_atom(Atom) -> false.
+
+%%------------------------------------
+
+-spec t_is_boolean(erl_type()) -> boolean().
+
+t_is_boolean(Type) ->
+  t_is_boolean(Type, 'universe').
+
+-spec t_is_boolean(erl_type(), opaques()) -> boolean().
+
+t_is_boolean(Type, Opaques) ->
+  do_opaque(Type, Opaques, fun is_boolean/1).
+
+-spec t_boolean() -> erl_type().
+
+t_boolean() ->
+  ?atom(set_from_list([false, true])).
+
+is_boolean(?atom(?any)) -> false;
+is_boolean(?atom(Set)) ->
+  case set_size(Set) of
+    1 -> set_is_element(true, Set) orelse set_is_element(false, Set);
+    2 -> set_is_element(true, Set) andalso set_is_element(false, Set);
+    N when is_integer(N), N > 2 -> false
+  end;
+is_boolean(_) -> false.
+
+%%-----------------------------------------------------------------------------
+%% Binaries
+%%
+
+-spec t_binary() -> erl_type().
+
+t_binary() ->
+  ?bitstr(8, 0).
+
+-spec t_is_binary(erl_type()) -> boolean().
+
+t_is_binary(Type) ->
+  t_is_binary(Type, 'universe').
+
+-spec t_is_binary(erl_type(), opaques()) -> boolean().
+
+t_is_binary(Type, Opaques) ->
+    do_opaque(Type, Opaques, fun is_binary/1).
+
+is_binary(?bitstr(U, B)) ->
+  ((U rem 8) =:= 0) andalso ((B rem 8) =:= 0);
+is_binary(_) -> false.
+
+%%-----------------------------------------------------------------------------
+%% Bitstrings
+%%
+
+-spec t_bitstr() -> erl_type().
+
+t_bitstr() ->
+  ?bitstr(1, 0).
+
+-spec t_bitstr(non_neg_integer(), non_neg_integer()) -> erl_type().
+
+t_bitstr(U, B) ->
+  NewB = 
+    if
+      U =:= 0 -> B;
+      B >= (U * (?UNIT_MULTIPLIER + 1)) ->
+	(B rem U) + U * ?UNIT_MULTIPLIER;
+      true ->
+	B
+    end,
+  ?bitstr(U, NewB).
+
+-spec t_bitstr_unit(erl_type()) -> non_neg_integer().
+
+t_bitstr_unit(?bitstr(U, _)) -> U.
+
+-spec t_bitstr_base(erl_type()) -> non_neg_integer().
+
+t_bitstr_base(?bitstr(_, B)) -> B.
+
+-spec t_bitstr_concat([erl_type()]) -> erl_type().
+
+t_bitstr_concat(List) ->
+  t_bitstr_concat_1(List, t_bitstr(0, 0)).
+
+t_bitstr_concat_1([T|Left], Acc) ->
+  t_bitstr_concat_1(Left, t_bitstr_concat(Acc, T));
+t_bitstr_concat_1([], Acc) ->
+  Acc.
+
+-spec t_bitstr_concat(erl_type(), erl_type()) -> erl_type().
+
+t_bitstr_concat(T1, T2) ->
+  T1p = t_inf(t_bitstr(), T1),
+  T2p = t_inf(t_bitstr(), T2),
+  bitstr_concat(t_unopaque(T1p), t_unopaque(T2p)).
+
+-spec t_bitstr_match(erl_type(), erl_type()) -> erl_type().
+
+t_bitstr_match(T1, T2) ->
+  T1p = t_inf(t_bitstr(), T1),
+  T2p = t_inf(t_bitstr(), T2),
+  bitstr_match(t_unopaque(T1p), t_unopaque(T2p)).
+
+-spec t_is_bitstr(erl_type()) -> boolean().
+
+t_is_bitstr(Type) ->
+  t_is_bitstr(Type, 'universe').
+
+-spec t_is_bitstr(erl_type(), opaques()) -> boolean().
+
+t_is_bitstr(Type, Opaques) ->
+    do_opaque(Type, Opaques, fun is_bitstr/1).
+
+is_bitstr(?bitstr(_, _)) -> true;
+is_bitstr(_) -> false.
+
+%%-----------------------------------------------------------------------------
+%% Matchstates
+%%
+
+-spec t_matchstate() -> erl_type().
+
+t_matchstate() ->
+  ?any_matchstate.
+
+-spec t_matchstate(erl_type(), non_neg_integer()) -> erl_type().
+
+t_matchstate(Init, 0) ->
+  ?matchstate(Init, Init);
+t_matchstate(Init, Max) when is_integer(Max) ->
+  Slots = [Init|[?none || _ <- lists:seq(1, Max)]],
+  ?matchstate(Init, t_product(Slots)).
+
+-spec t_is_matchstate(erl_type()) -> boolean().
+
+t_is_matchstate(?matchstate(_, _)) -> true;
+t_is_matchstate(_) -> false.
+
+-spec t_matchstate_present(erl_type()) -> erl_type().
+
+t_matchstate_present(Type) ->
+  case t_inf(t_matchstate(), Type) of
+    ?matchstate(P, _) -> P;
+    _ -> ?none
+  end.
+
+-spec t_matchstate_slot(erl_type(), non_neg_integer()) -> erl_type().
+
+t_matchstate_slot(Type, Slot) ->
+  RealSlot = Slot + 1,
+  case t_inf(t_matchstate(), Type) of
+    ?matchstate(_, ?any) -> ?any;
+    ?matchstate(_, ?product(Vals)) when length(Vals) >= RealSlot ->
+      lists:nth(RealSlot, Vals);
+    ?matchstate(_, ?product(_)) ->
+      ?none;
+    ?matchstate(_, SlotType) when RealSlot =:= 1 ->
+      SlotType;
+    _ ->
+      ?none
+  end.
+
+-spec t_matchstate_slots(erl_type()) -> erl_type().
+
+t_matchstate_slots(?matchstate(_, Slots)) ->
+  Slots.
+
+-spec t_matchstate_update_present(erl_type(), erl_type()) -> erl_type().
+
+t_matchstate_update_present(New, Type) -> 
+  case t_inf(t_matchstate(), Type) of
+    ?matchstate(_, Slots) ->
+      ?matchstate(New, Slots);
+    _ -> ?none
+  end.
+
+-spec t_matchstate_update_slot(erl_type(), erl_type(), non_neg_integer()) -> erl_type().
+
+t_matchstate_update_slot(New, Type, Slot) -> 
+  RealSlot = Slot + 1,
+  case t_inf(t_matchstate(), Type) of
+    ?matchstate(Pres, Slots) ->
+      NewSlots = 
+	case Slots of
+	  ?any ->
+	    ?any;
+	  ?product(Vals) when length(Vals) >= RealSlot ->
+	    NewTuple = setelement(RealSlot, list_to_tuple(Vals), New),
+	    NewVals = tuple_to_list(NewTuple),
+	    ?product(NewVals);
+	  ?product(_) ->
+	    ?none;
+	  _ when RealSlot =:= 1 ->
+	    New;
+	  _ ->
+	    ?none
+	end,
+      ?matchstate(Pres, NewSlots);
+    _ ->
+      ?none
+  end.
+
+%%-----------------------------------------------------------------------------
+%% Functions
+%%
+
+-spec t_fun() -> erl_type().
+
+t_fun() ->
+  ?function(?any, ?any).
+
+-spec t_fun(erl_type()) -> erl_type().
+
+t_fun(Range) ->
+  ?function(?any, Range).
+
+-spec t_fun([erl_type()] | arity(), erl_type()) -> erl_type().
+
+t_fun(Domain, Range) when is_list(Domain) ->
+  ?function(?product(Domain), Range);
+t_fun(Arity, Range) when is_integer(Arity), 0 =< Arity, Arity =< 255 ->
+  ?function(?product(lists:duplicate(Arity, ?any)), Range).
+
+-spec t_fun_args(erl_type()) -> 'unknown' | [erl_type()].
+
+t_fun_args(Type) ->
+  t_fun_args(Type, 'universe').
+
+-spec t_fun_args(erl_type(), opaques()) -> 'unknown' | [erl_type()].
+
+t_fun_args(Type, Opaques) ->
+  do_opaque(Type, Opaques, fun fun_args/1).
+
+fun_args(?function(?any, _)) ->
+  unknown;
+fun_args(?function(?product(Domain), _)) when is_list(Domain) ->
+  Domain.
+
+-spec t_fun_arity(erl_type()) -> 'unknown' | non_neg_integer().
+
+t_fun_arity(Type) ->
+  t_fun_arity(Type, 'universe').
+
+-spec t_fun_arity(erl_type(), opaques()) -> 'unknown' | non_neg_integer().
+
+t_fun_arity(Type, Opaques) ->
+  do_opaque(Type, Opaques, fun fun_arity/1).
+
+fun_arity(?function(?any, _)) ->
+  unknown;
+fun_arity(?function(?product(Domain), _)) ->
+  length(Domain).
+
+-spec t_fun_range(erl_type()) -> erl_type().
+
+t_fun_range(Type) ->
+  t_fun_range(Type, 'universe').
+
+-spec t_fun_range(erl_type(), opaques()) -> erl_type().
+
+t_fun_range(Type, Opaques) ->
+  do_opaque(Type, Opaques, fun fun_range/1).
+
+fun_range(?function(_, Range)) ->
+  Range.
+
+-spec t_is_fun(erl_type()) -> boolean().
+
+t_is_fun(Type) ->
+  t_is_fun(Type, 'universe').
+
+-spec t_is_fun(erl_type(), opaques()) -> boolean().
+
+t_is_fun(Type, Opaques) ->
+  do_opaque(Type, Opaques, fun is_fun/1).
+
+is_fun(?function(_, _)) -> true;
+is_fun(_) -> false.
+
+%%-----------------------------------------------------------------------------
+%% Identifiers. Includes ports, pids and refs.
+%% 
+
+-spec t_identifier() -> erl_type().
+
+t_identifier() ->
+  ?identifier(?any).
+
+-ifdef(DO_ERL_TYPES_TEST).
+-spec t_is_identifier(erl_type()) -> erl_type().
+
+t_is_identifier(?identifier(_)) -> true;
+t_is_identifier(_) -> false.
+-endif.
+
+%%------------------------------------
+
+-spec t_port() -> erl_type().
+
+t_port() ->
+  ?identifier(set_singleton(?port_qual)).
+
+-spec t_is_port(erl_type()) -> boolean().
+
+t_is_port(Type) ->
+  t_is_port(Type, 'universe').
+
+-spec t_is_port(erl_type(), opaques()) -> boolean().
+
+t_is_port(Type, Opaques) ->
+  do_opaque(Type, Opaques, fun is_port1/1).
+
+is_port1(?identifier(?any)) -> false;
+is_port1(?identifier(Set)) -> set_is_singleton(?port_qual, Set);
+is_port1(_) -> false.
+
+%%------------------------------------
+
+-spec t_pid() -> erl_type().
+
+t_pid() ->
+  ?identifier(set_singleton(?pid_qual)).
+
+-spec t_is_pid(erl_type()) -> boolean().
+
+t_is_pid(Type) ->
+  t_is_pid(Type, 'universe').
+
+-spec t_is_pid(erl_type(), opaques()) -> boolean().
+
+t_is_pid(Type, Opaques) ->
+  do_opaque(Type, Opaques, fun is_pid1/1).
+
+is_pid1(?identifier(?any)) -> false;
+is_pid1(?identifier(Set)) -> set_is_singleton(?pid_qual, Set);
+is_pid1(_) -> false.
+
+%%------------------------------------
+
+-spec t_reference() -> erl_type().
+
+t_reference() ->
+  ?identifier(set_singleton(?reference_qual)).
+
+-spec t_is_reference(erl_type()) -> boolean().
+
+t_is_reference(Type) ->
+  t_is_reference(Type, 'universe').
+
+-spec t_is_reference(erl_type(), opaques()) -> boolean().
+
+t_is_reference(Type, Opaques) ->
+  do_opaque(Type, Opaques, fun is_reference1/1).
+
+is_reference1(?identifier(?any)) -> false;
+is_reference1(?identifier(Set)) -> set_is_singleton(?reference_qual, Set);
+is_reference1(_) -> false.
+
+%%-----------------------------------------------------------------------------
+%% Numbers are divided into floats, integers, chars and bytes.
+%%
+
+-spec t_number() -> erl_type().
+
+t_number() ->
+  ?number(?any, ?unknown_qual).
+
+-spec t_number(integer()) -> erl_type().
+
+t_number(X) when is_integer(X) ->
+  t_integer(X).
+
+-spec t_is_number(erl_type()) -> boolean().
+
+t_is_number(Type) ->
+  t_is_number(Type, 'universe').
+
+-spec t_is_number(erl_type(), opaques()) -> boolean().
+
+t_is_number(Type, Opaques) ->
+  do_opaque(Type, Opaques, fun is_number/1).
+
+is_number(?number(_, _)) -> true;
+is_number(_) -> false.
+
+%% Currently, the type system collapses all floats to ?float and does
+%% not keep any information about their values. As a result, the list
+%% that this function returns contains only integers.
+
+-spec t_number_vals(erl_type()) -> 'unknown' | [integer(),...].
+
+t_number_vals(Type) ->
+  t_number_vals(Type, 'universe').
+
+-spec t_number_vals(erl_type(), opaques()) -> 'unknown' | [integer(),...].
+
+t_number_vals(Type, Opaques) ->
+  do_opaque(Type, Opaques, fun number_vals/1).
+
+number_vals(?int_set(Set)) -> set_to_list(Set);
+number_vals(?number(_, _)) -> unknown;
+number_vals(?opaque(_)) -> unknown;
+number_vals(Other) ->
+  Inf = t_inf(Other, t_number()),
+  false = t_is_none(Inf), % sanity check
+  number_vals(Inf).
+
+%%------------------------------------
+
+-spec t_float() -> erl_type().
+
+t_float() ->
+  ?float.
+
+-spec t_is_float(erl_type()) -> boolean().
+
+t_is_float(Type) ->
+  t_is_float(Type, 'universe').
+
+-spec t_is_float(erl_type(), opaques()) -> boolean().
+
+t_is_float(Type, Opaques) ->
+  do_opaque(Type, Opaques, fun is_float1/1).
+
+is_float1(?float) -> true;
+is_float1(_) -> false.
+
+%%------------------------------------
+
+-spec t_integer() -> erl_type().
+
+t_integer() ->
+  ?integer(?any).
+
+-spec t_integer(integer()) -> erl_type().
+
+t_integer(I) when is_integer(I) ->
+  ?int_set(set_singleton(I)).
+
+-spec t_integers([integer()]) -> erl_type().
+
+t_integers(List) when is_list(List) ->
+  t_sup([t_integer(I) || I <- List]).
+
+-spec t_is_integer(erl_type()) -> boolean().
+
+t_is_integer(Type) ->
+  t_is_integer(Type, 'universe').
+
+-spec t_is_integer(erl_type(), opaques()) -> boolean().
+
+t_is_integer(Type, Opaques) ->
+  do_opaque(Type, Opaques, fun is_integer1/1).
+
+is_integer1(?integer(_)) -> true;
+is_integer1(_) -> false.
+
+%%------------------------------------
+
+-spec t_byte() -> erl_type().
+
+t_byte() ->
+  ?byte.
+
+-ifdef(DO_ERL_TYPES_TEST).
+-spec t_is_byte(erl_type()) -> boolean().
+
+t_is_byte(?int_range(neg_inf, _)) -> false;
+t_is_byte(?int_range(_, pos_inf)) -> false;
+t_is_byte(?int_range(From, To))
+  when is_integer(From), From >= 0, is_integer(To), To =< ?MAX_BYTE -> true;
+t_is_byte(?int_set(Set)) -> 
+  (set_min(Set) >= 0) andalso (set_max(Set) =< ?MAX_BYTE);
+t_is_byte(_) -> false.
+-endif.
+
+%%------------------------------------
+
+-spec t_char() -> erl_type().
+
+t_char() ->
+  ?char.
+
+-spec t_is_char(erl_type()) -> boolean().
+
+t_is_char(?int_range(neg_inf, _)) -> false;
+t_is_char(?int_range(_, pos_inf)) -> false;
+t_is_char(?int_range(From, To))
+  when is_integer(From), From >= 0, is_integer(To), To =< ?MAX_CHAR -> true;
+t_is_char(?int_set(Set)) -> 
+  (set_min(Set) >= 0) andalso (set_max(Set) =< ?MAX_CHAR);
+t_is_char(_) -> false.
+
+%%-----------------------------------------------------------------------------
+%% Lists
+%%
+
+-spec t_cons() -> erl_type().
+
+t_cons() ->
+  ?nonempty_list(?any, ?any).
+
+%% Note that if the tail argument can be a list, we must collapse the
+%% content of the list to include both the content of the tail list
+%% and the head of the cons. If for example the tail argument is any()
+%% then there can be any list in the tail and the content of the
+%% returned list must be any().
+
+-spec t_cons(erl_type(), erl_type()) -> erl_type().
+
+t_cons(?none,  _) -> ?none;
+t_cons(_, ?none) -> ?none;
+t_cons(?unit, _) -> ?none;
+t_cons(_, ?unit) -> ?none;
+t_cons(Hd, ?nil) ->
+  ?nonempty_list(Hd, ?nil);
+t_cons(Hd, ?list(Contents, Termination, _)) ->
+  ?nonempty_list(t_sup(Contents, Hd), Termination);
+t_cons(Hd, Tail) ->
+  case cons_tail(t_inf(Tail, t_maybe_improper_list())) of
+    ?list(Contents, Termination, _Size) ->
+      %% Collapse the list part of the termination but keep the
+      %% non-list part intact.
+      NewTermination = t_sup(t_subtract(Tail, t_maybe_improper_list()), 
+			     Termination),
+      ?nonempty_list(t_sup(Hd, Contents), NewTermination);
+    ?nil -> ?nonempty_list(Hd, Tail);
+    ?none -> ?nonempty_list(Hd, Tail);
+    ?unit -> ?none
+  end.
+
+cons_tail(Type) ->
+  do_opaque(Type, 'universe', fun(T) -> T end).
+
+-spec t_is_cons(erl_type()) -> boolean().
+
+t_is_cons(Type) ->
+  t_is_cons(Type, 'universe').
+
+-spec t_is_cons(erl_type(), opaques()) -> boolean().
+
+t_is_cons(Type, Opaques) ->
+  do_opaque(Type, Opaques, fun is_cons/1).
+
+is_cons(?nonempty_list(_, _)) -> true;
+is_cons(_) -> false.
+
+-spec t_cons_hd(erl_type()) -> erl_type().
+
+t_cons_hd(Type) ->
+  t_cons_hd(Type, 'universe').
+
+-spec t_cons_hd(erl_type(), opaques()) -> erl_type().
+
+t_cons_hd(Type, Opaques) ->
+  do_opaque(Type, Opaques, fun cons_hd/1).
+
+cons_hd(?nonempty_list(Contents, _Termination)) -> Contents.
+
+-spec t_cons_tl(erl_type()) -> erl_type().
+
+t_cons_tl(Type) ->
+  t_cons_tl(Type, 'universe').
+
+-spec t_cons_tl(erl_type(), opaques()) -> erl_type().
+
+t_cons_tl(Type, Opaques) ->
+  do_opaque(Type, Opaques, fun cons_tl/1).
+
+cons_tl(?nonempty_list(_Contents, Termination) = T) ->
+  t_sup(Termination, T).
+
+-spec t_nil() -> erl_type().
+
+t_nil() ->
+  ?nil.
+
+-spec t_is_nil(erl_type()) -> boolean().
+
+t_is_nil(Type) ->
+  t_is_nil(Type, 'universe').
+
+-spec t_is_nil(erl_type(), opaques()) -> boolean().
+
+t_is_nil(Type, Opaques) ->
+  do_opaque(Type, Opaques, fun is_nil/1).
+
+is_nil(?nil) -> true;
+is_nil(_) -> false.
+
+-spec t_list() -> erl_type().
+
+t_list() ->
+  ?list(?any, ?nil, ?unknown_qual).
+
+-spec t_list(erl_type()) -> erl_type().
+
+t_list(?none) -> ?none;
+t_list(?unit) -> ?none;
+t_list(Contents) ->
+  ?list(Contents, ?nil, ?unknown_qual).
+
+-spec t_list_elements(erl_type()) -> erl_type().
+
+t_list_elements(Type) ->
+  t_list_elements(Type, 'universe').
+
+-spec t_list_elements(erl_type(), opaques()) -> erl_type().
+
+t_list_elements(Type, Opaques) ->
+  do_opaque(Type, Opaques, fun list_elements/1).
+
+list_elements(?list(Contents, _, _)) -> Contents;
+list_elements(?nil) -> ?none.
+
+-spec t_list_termination(erl_type(), opaques()) -> erl_type().
+
+t_list_termination(Type, Opaques) ->
+  do_opaque(Type, Opaques, fun t_list_termination/1).
+
+-spec t_list_termination(erl_type()) -> erl_type().
+
+t_list_termination(?nil) -> ?nil;
+t_list_termination(?list(_, Term, _)) -> Term.
+
+-spec t_is_list(erl_type()) -> boolean().
+
+t_is_list(?list(_Contents, ?nil, _)) -> true;
+t_is_list(?nil) -> true;
+t_is_list(_) -> false.
+
+-spec t_nonempty_list() -> erl_type().
+
+t_nonempty_list() ->
+  t_cons(?any, ?nil).
+
+-spec t_nonempty_list(erl_type()) -> erl_type().
+
+t_nonempty_list(Type) ->
+  t_cons(Type, ?nil).
+
+-spec t_nonempty_string() -> erl_type().
+
+t_nonempty_string() ->
+  t_nonempty_list(t_char()).
+
+-spec t_string() -> erl_type().
+
+t_string() ->
+  t_list(t_char()).
+
+-spec t_is_string(erl_type()) -> boolean().
+
+t_is_string(X) ->
+  t_is_list(X) andalso t_is_char(t_list_elements(X)).
+
+-spec t_maybe_improper_list() -> erl_type().
+
+t_maybe_improper_list() ->
+  ?list(?any, ?any, ?unknown_qual).
+
+%% Should only be used if you know what you are doing. See t_cons/2
+-spec t_maybe_improper_list(erl_type(), erl_type()) -> erl_type().
+
+t_maybe_improper_list(_Content, ?unit) -> ?none;
+t_maybe_improper_list(?unit, _Termination) -> ?none;
+t_maybe_improper_list(Content, Termination) ->
+  %% Safety check: would be nice to have but does not work with remote types
+  %% true = t_is_subtype(t_nil(), Termination),
+  ?list(Content, Termination, ?unknown_qual).
+
+-spec t_is_maybe_improper_list(erl_type()) -> boolean().
+
+t_is_maybe_improper_list(Type) ->
+  t_is_maybe_improper_list(Type, 'universe').
+
+-spec t_is_maybe_improper_list(erl_type(), opaques()) -> boolean().
+
+t_is_maybe_improper_list(Type, Opaques) ->
+  do_opaque(Type, Opaques, fun is_maybe_improper_list/1).
+
+is_maybe_improper_list(?list(_, _, _)) -> true;
+is_maybe_improper_list(?nil) -> true;
+is_maybe_improper_list(_) -> false.
+
+%% %% Should only be used if you know what you are doing. See t_cons/2
+%% -spec t_improper_list(erl_type(), erl_type()) -> erl_type().
+%%
+%% t_improper_list(?unit, _Termination) -> ?none;
+%% t_improper_list(_Content, ?unit) -> ?none;
+%% t_improper_list(Content, Termination) ->
+%%   %% Safety check: would be nice to have but does not work with remote types
+%%   %% false = t_is_subtype(t_nil(), Termination),
+%%   ?list(Content, Termination, ?any).  
+
+-spec lift_list_to_pos_empty(erl_type(), opaques()) -> erl_type().
+
+lift_list_to_pos_empty(Type, Opaques) ->
+  do_opaque(Type, Opaques, fun lift_list_to_pos_empty/1).
+
+-spec lift_list_to_pos_empty(erl_type()) -> erl_type().
+
+lift_list_to_pos_empty(?nil) -> ?nil;
+lift_list_to_pos_empty(?list(Content, Termination, _)) -> 
+  ?list(Content, Termination, ?unknown_qual).
+
+%%-----------------------------------------------------------------------------
+%% Maps
+%%
+%% Representation:
+%%  ?map(Pairs, DefaultKey, DefaultValue)
+%%
+%% Pairs is a sorted dictionary of types with a mandatoriness tag on each pair
+%% (t_map_dict()). DefaultKey and DefaultValue are plain types.
+%%
+%% A map M belongs to this type iff
+%%   For each pair {KT, mandatory, VT} in Pairs, there exists a pair {K, V} in M
+%%     such that K \in KT and V \in VT.
+%%   For each pair {KT, optional, VT} in Pairs, either there exists no key K in
+%%     M s.t. K in KT, or there exists a pair {K, V} in M such that K \in KT and
+%%     V \in VT.
+%%   For each remaining pair {K, V} in M (where remaining means that there is no
+%%     key KT in Pairs s.t. K \in KT), K \in DefaultKey and V \in DefaultValue.
+%%
+%% Invariants:
+%%  * The keys in Pairs are singleton types.
+%%  * The values of Pairs must not be unit, and may only be none if the
+%%      mandatoriness tag  is 'optional'.
+%%  * Optional must contain no pair {K,V} s.t. K is a subtype of DefaultKey and
+%%    V is equal to DefaultKey.
+%%  * DefaultKey must be the empty type iff DefaultValue is the empty type.
+%%  * DefaultKey must not be a singleton type.
+%%  * For every key K in Pairs, DefaultKey - K must not be representable; i.e.
+%%    t_subtract(DefaultKey, K) must return DefaultKey.
+%%  * For every pair {K, 'optional', ?none} in Pairs, K must be a subtype of
+%%    DefaultKey.
+%%  * Pairs must be sorted and not contain any duplicate keys.
+%%
+%% These invariants ensure that equal map types are represented by equal terms.
+
+-define(mand, mandatory).
+-define(opt, optional).
+
+-type t_map_mandatoriness() :: ?mand | ?opt.
+-type t_map_pair() :: {erl_type(), t_map_mandatoriness(), erl_type()}.
+-type t_map_dict() :: [t_map_pair()].
+
+-spec t_map() -> erl_type().
+
+t_map() ->
+  t_map([], t_any(), t_any()).
+
+-spec t_map([{erl_type(), erl_type()}]) -> erl_type().
+
+t_map(L) ->
+  lists:foldl(fun t_map_put/2, t_map(), L).
+
+-spec t_map(t_map_dict(), erl_type(), erl_type()) -> erl_type().
+
+t_map(Pairs0, DefK0, DefV0) ->
+  DefK1 = lists:foldl(fun({K,_,_},Acc)->t_subtract(Acc,K)end, DefK0, Pairs0),
+  {DefK2, DefV1} =
+    case t_is_none_or_unit(DefK1) orelse t_is_none_or_unit(DefV0) of
+      true  -> {?none, ?none};
+      false -> {DefK1, DefV0}
+    end,
+  {Pairs1, DefK, DefV}
+    = case is_singleton_type(DefK2) of
+	true  -> {mapdict_insert({DefK2, ?opt, DefV1}, Pairs0), ?none, ?none};
+	false -> {Pairs0,                                       DefK2, DefV1}
+      end,
+  Pairs = normalise_map_optionals(Pairs1, DefK, DefV),
+  %% Validate invariants of the map representation.
+  %% Since we needed to iterate over the arguments in order to normalise anyway,
+  %% we might as well save us some future pain and do this even without
+  %% define(DEBUG, true).
+  try
+    validate_map_elements(Pairs)
+  catch error:badarg ->      error(badarg,      [Pairs0,DefK0,DefV0]);
+	error:{badarg, E} -> error({badarg, E}, [Pairs0,DefK0,DefV0])
+  end,
+  ?map(Pairs, DefK, DefV).
+
+normalise_map_optionals([], _, _) -> [];
+normalise_map_optionals([E={K,?opt,?none}|T], DefK, DefV) ->
+  Diff = t_subtract(DefK, K),
+  case t_is_subtype(K, DefK) andalso DefK =:= Diff of
+    true -> [E|normalise_map_optionals(T, DefK, DefV)];
+    false -> normalise_map_optionals(T, Diff, DefV)
+  end;
+normalise_map_optionals([E={K,?opt,V}|T], DefK, DefV) ->
+  case t_is_equal(V, DefV) andalso t_is_subtype(K, DefK) of
+    true -> normalise_map_optionals(T, DefK, DefV);
+    false -> [E|normalise_map_optionals(T, DefK, DefV)]
+  end;
+normalise_map_optionals([E|T], DefK, DefV) ->
+  [E|normalise_map_optionals(T, DefK, DefV)].
+
+validate_map_elements([{_,?mand,?none}|_]) -> error({badarg, none_in_mand});
+validate_map_elements([{K1,_,_}|Rest=[{K2,_,_}|_]]) ->
+  case is_singleton_type(K1) andalso K1 < K2 of
+    false -> error(badarg);
+    true -> validate_map_elements(Rest)
+  end;
+validate_map_elements([{K,_,_}]) ->
+  case is_singleton_type(K) of
+    false -> error(badarg);
+    true -> true
+  end;
+validate_map_elements([]) -> true.
+
+-spec t_is_map(erl_type()) -> boolean().
+
+t_is_map(Type) ->
+  t_is_map(Type, 'universe').
+
+-spec t_is_map(erl_type(), opaques()) -> boolean().
+
+t_is_map(Type, Opaques) ->
+  do_opaque(Type, Opaques, fun is_map1/1).
+
+is_map1(?map(_, _, _)) -> true;
+is_map1(_) -> false.
+
+-spec t_map_entries(erl_type()) -> t_map_dict().
+
+t_map_entries(M) ->
+  t_map_entries(M, 'universe').
+
+-spec t_map_entries(erl_type(), opaques()) -> t_map_dict().
+
+t_map_entries(M, Opaques) ->
+  do_opaque(M, Opaques, fun map_entries/1).
+
+map_entries(?map(Pairs,_,_)) ->
+  Pairs.
+
+-spec t_map_def_key(erl_type()) -> erl_type().
+
+t_map_def_key(M) ->
+  t_map_def_key(M, 'universe').
+
+-spec t_map_def_key(erl_type(), opaques()) -> erl_type().
+
+t_map_def_key(M, Opaques) ->
+  do_opaque(M, Opaques, fun map_def_key/1).
+
+map_def_key(?map(_,DefK,_)) ->
+  DefK.
+
+-spec t_map_def_val(erl_type()) -> erl_type().
+
+t_map_def_val(M) ->
+  t_map_def_val(M, 'universe').
+
+-spec t_map_def_val(erl_type(), opaques()) -> erl_type().
+
+t_map_def_val(M, Opaques) ->
+  do_opaque(M, Opaques, fun map_def_val/1).
+
+map_def_val(?map(_,_,DefV)) ->
+  DefV.
+
+-spec mapdict_store(t_map_pair(), t_map_dict()) -> t_map_dict().
+
+mapdict_store(E={K,_,_}, [{K,_,_}|T]) -> [E|T];
+mapdict_store(E1={K1,_,_}, [E2={K2,_,_}|T]) when K1 > K2 ->
+  [E2|mapdict_store(E1, T)];
+mapdict_store(E={_,_,_}, T) -> [E|T].
+
+-spec mapdict_insert(t_map_pair(), t_map_dict()) -> t_map_dict().
+
+mapdict_insert(E={K,_,_}, D=[{K,_,_}|_]) -> error(badarg, [E, D]);
+mapdict_insert(E1={K1,_,_}, [E2={K2,_,_}|T]) when K1 > K2 ->
+  [E2|mapdict_insert(E1, T)];
+mapdict_insert(E={_,_,_}, T) -> [E|T].
+
+%% Merges the pairs of two maps together. Missing pairs become (?opt, DefV) or
+%% (?opt, ?none), depending on whether K \in DefK.
+-spec map_pairwise_merge(fun((erl_type(),
+			      t_map_mandatoriness(), erl_type(),
+			      t_map_mandatoriness(), erl_type())
+			     -> t_map_pair() | false),
+			 erl_type(), erl_type()) -> t_map_dict().
+map_pairwise_merge(F, ?map(APairs, ADefK, ADefV),
+		       ?map(BPairs, BDefK, BDefV)) ->
+  map_pairwise_merge(F, APairs, ADefK, ADefV, BPairs, BDefK, BDefV).
+
+map_pairwise_merge(_, [], _, _, [], _, _) -> [];
+map_pairwise_merge(F, As0, ADefK, ADefV, Bs0, BDefK, BDefV) ->
+  {K1, AMNess1, AV1, As1, BMNess1, BV1, Bs1} =
+    case {As0, Bs0} of
+      {[{K,AMNess,AV}|As], [{K, BMNess,BV}|Bs]} ->
+	{K, AMNess, AV, As, BMNess, BV, Bs};
+      {[{K,AMNess,AV}|As], [{BK,_,     _ }|_]=Bs} when K < BK ->
+        {K, AMNess, AV, As, ?opt, mapmerge_otherv(K, BDefK, BDefV), Bs};
+      {As,                 [{K, BMNess,BV}|Bs]} ->
+        {K, ?opt, mapmerge_otherv(K, ADefK, ADefV), As, BMNess, BV, Bs};
+      {[{K,AMNess,AV}|As], []=Bs} ->
+        {K, AMNess, AV, As, ?opt, mapmerge_otherv(K, BDefK, BDefV), Bs}
+    end,
+  MK = K1, %% Rename to make clear that we are matching below
+  case F(K1, AMNess1, AV1, BMNess1, BV1) of
+    false ->         map_pairwise_merge(F,As1,ADefK,ADefV,Bs1,BDefK,BDefV);
+    {MK,_,_}=M -> [M|map_pairwise_merge(F,As1,ADefK,ADefV,Bs1,BDefK,BDefV)]
+  end.
+
+%% Folds over the pairs in two maps simultaneously in reverse key order. Missing
+%% pairs become (?opt, DefV) or (?opt, ?none), depending on whether K \in DefK.
+-spec map_pairwise_merge_foldr(fun((erl_type(),
+				    t_map_mandatoriness(), erl_type(),
+				    t_map_mandatoriness(), erl_type(),
+				    Acc) -> Acc),
+			       Acc, erl_type(), erl_type()) -> Acc.
+
+map_pairwise_merge_foldr(F, AccIn, ?map(APairs, ADefK, ADefV),
+			 ?map(BPairs, BDefK, BDefV)) ->
+  map_pairwise_merge_foldr(F, AccIn, APairs, ADefK, ADefV, BPairs, BDefK, BDefV).
+
+map_pairwise_merge_foldr(_, Acc,   [],  _,     _,     [],  _,     _) -> Acc;
+map_pairwise_merge_foldr(F, AccIn, As0, ADefK, ADefV, Bs0, BDefK, BDefV) ->
+  {K1, AMNess1, AV1, As1, BMNess1, BV1, Bs1} =
+    case {As0, Bs0} of
+      {[{K,AMNess,AV}|As], [{K,BMNess,BV}|Bs]} ->
+	{K, AMNess, AV, As, BMNess, BV, Bs};
+      {[{K,AMNess,AV}|As], [{BK,_,     _ }|_]=Bs} when K < BK ->
+	{K, AMNess, AV, As, ?opt, mapmerge_otherv(K, BDefK, BDefV), Bs};
+      {As,                 [{K,BMNess,BV}|Bs]} ->
+        {K, ?opt, mapmerge_otherv(K, ADefK, ADefV), As, BMNess, BV, Bs};
+      {[{K,AMNess,AV}|As], []=Bs} ->
+        {K, AMNess, AV, As, ?opt, mapmerge_otherv(K, BDefK, BDefV), Bs}
+    end,
+  F(K1, AMNess1, AV1, BMNess1, BV1,
+    map_pairwise_merge_foldr(F,AccIn,As1,ADefK,ADefV,Bs1,BDefK,BDefV)).
+
+%% By observing that a missing pair in a map is equivalent to an optional pair,
+%% with ?none or DefV value, depending on whether K \in DefK, we can simplify
+%% merging by denormalising the map pairs temporarily, removing all 'false'
+%% cases, at the cost of the creation of more tuples:
+mapmerge_otherv(K, ODefK, ODefV) ->
+  case t_inf(K, ODefK) of
+    ?none      -> ?none;
+    _KOrOpaque -> ODefV
+  end.
+
+-spec t_map_put({erl_type(), erl_type()}, erl_type()) -> erl_type().
+
+t_map_put(KV, Map) ->
+  t_map_put(KV, Map, 'universe').
+
+-spec t_map_put({erl_type(), erl_type()}, erl_type(), opaques()) -> erl_type().
+
+t_map_put(KV, Map, Opaques) ->
+  do_opaque(Map, Opaques, fun(UM) -> map_put(KV, UM, Opaques) end).
+
+%% Key and Value are *not* unopaqued, but the map is
+map_put(_, ?none, _) -> ?none;
+map_put({Key, Value}, ?map(Pairs,DefK,DefV), Opaques) ->
+  case t_is_none_or_unit(Key) orelse t_is_none_or_unit(Value) of
+    true -> ?none;
+    false ->
+      case is_singleton_type(Key) of
+	true ->
+	  t_map(mapdict_store({Key, ?mand, Value}, Pairs), DefK, DefV);
+	false ->
+	  t_map([{K, MNess, case t_is_none(t_inf(K, Key, Opaques)) of
+			      true -> V;
+			      false -> t_sup(V, Value)
+			    end} || {K, MNess, V} <- Pairs],
+		t_sup(DefK, Key),
+		t_sup(DefV, Value))
+      end
+  end.
+
+-spec t_map_update({erl_type(), erl_type()}, erl_type()) -> erl_type().
+
+t_map_update(KV, Map) ->
+  t_map_update(KV, Map, 'universe').
+
+-spec t_map_update({erl_type(), erl_type()}, erl_type(), opaques()) -> erl_type().
+
+t_map_update(_, ?none, _) -> ?none;
+t_map_update(KV={Key, _}, M, Opaques) ->
+  case t_is_subtype(t_atom('true'), t_map_is_key(Key, M, Opaques)) of
+    false -> ?none;
+    true -> t_map_put(KV, M, Opaques)
+  end.
+
+-spec t_map_get(erl_type(), erl_type()) -> erl_type().
+
+t_map_get(Key, Map) ->
+  t_map_get(Key, Map, 'universe').
+
+-spec t_map_get(erl_type(), erl_type(), opaques()) -> erl_type().
+
+t_map_get(Key, Map, Opaques) ->
+  do_opaque(Map, Opaques,
+	    fun(UM) ->
+		do_opaque(Key, Opaques, fun(UK) -> map_get(UK, UM) end)
+	    end).
+
+map_get(_, ?none) -> ?none;
+map_get(Key, ?map(Pairs, DefK, DefV)) ->
+  DefRes =
+    case t_do_overlap(DefK, Key) of
+      false -> t_none();
+      true -> DefV
+    end,
+  case is_singleton_type(Key) of
+    false ->
+      lists:foldl(fun({K, _, V}, Res) ->
+		      case t_do_overlap(K, Key) of
+			false -> Res;
+			true -> t_sup(Res, V)
+		      end
+		  end, DefRes, Pairs);
+    true ->
+      case lists:keyfind(Key, 1, Pairs) of
+	false -> DefRes;
+	{_, _, ValType} -> ValType
+      end
+  end.
+
+-spec t_map_is_key(erl_type(), erl_type()) -> erl_type().
+
+t_map_is_key(Key, Map) ->
+  t_map_is_key(Key, Map, 'universe').
+
+-spec t_map_is_key(erl_type(), erl_type(), opaques()) -> erl_type().
+
+t_map_is_key(Key, Map, Opaques) ->
+  do_opaque(Map, Opaques,
+	    fun(UM) ->
+		do_opaque(Key, Opaques, fun(UK) -> map_is_key(UK, UM) end)
+	    end).
+
+map_is_key(_, ?none) -> ?none;
+map_is_key(Key, ?map(Pairs, DefK, _DefV)) ->
+  case is_singleton_type(Key) of
+    true ->
+      case lists:keyfind(Key, 1, Pairs) of
+	{Key, ?mand, _}     -> t_atom(true);
+	{Key, ?opt,  ?none} -> t_atom(false);
+	{Key, ?opt,  _}     -> t_boolean();
+	false ->
+	  case t_do_overlap(DefK, Key) of
+	    false -> t_atom(false);
+	    true -> t_boolean()
+	  end
+      end;
+    false ->
+      case t_do_overlap(DefK, Key)
+	orelse lists:any(fun({_,_,?none}) -> false;
+			    ({K,_,_}) -> t_do_overlap(K, Key)
+			 end, Pairs)
+      of
+	true -> t_boolean();
+	false -> t_atom(false)
+      end
+  end.
+
+%%-----------------------------------------------------------------------------
+%% Tuples
+%%
+
+-spec t_tuple() -> erl_type().
+
+t_tuple() ->
+  ?tuple(?any, ?any, ?any).
+
+-spec t_tuple(non_neg_integer() | [erl_type()]) -> erl_type().
+
+t_tuple(N) when is_integer(N), N > ?MAX_TUPLE_SIZE  ->
+  t_tuple();
+t_tuple(N) when is_integer(N) ->
+  ?tuple(lists:duplicate(N, ?any), N, ?any);
+t_tuple(List) ->
+  case any_none_or_unit(List) of
+    true -> t_none();
+    false ->
+      Arity = length(List),
+      case get_tuple_tags(List) of
+	[Tag] -> ?tuple(List, Arity, Tag);  %% Tag can also be ?any here
+	TagList ->
+	  SortedTagList = lists:sort(TagList),
+	  Tuples = [?tuple([T|tl(List)], Arity, T) || T <- SortedTagList],
+	  ?tuple_set([{Arity, Tuples}])
+      end
+  end.
+
+-spec get_tuple_tags([erl_type()]) -> [erl_type(),...].
+
+get_tuple_tags([Tag|_]) ->
+  do_opaque(Tag, 'universe', fun tuple_tags/1);
+get_tuple_tags(_) -> [?any].
+
+tuple_tags(?atom(?any)) -> [?any];
+tuple_tags(?atom(Set)) ->
+  case set_size(Set) > ?TUPLE_TAG_LIMIT of
+    true -> [?any];
+    false -> [t_atom(A) || A <- set_to_list(Set)]
+  end;
+tuple_tags(_) -> [?any].
+
+%% to be used for a tuple with known types for its arguments (not ?any)
+-spec t_tuple_args(erl_type()) -> [erl_type()].
+
+t_tuple_args(Type) ->
+  t_tuple_args(Type, 'universe').
+
+%% to be used for a tuple with known types for its arguments (not ?any)
+-spec t_tuple_args(erl_type(), opaques()) -> [erl_type()].
+
+t_tuple_args(Type, Opaques) ->
+  do_opaque(Type, Opaques, fun tuple_args/1).
+
+tuple_args(?tuple(Args, _, _)) when is_list(Args) -> Args.
+
+%% to be used for a tuple with a known size (not ?any)
+-spec t_tuple_size(erl_type()) -> non_neg_integer().
+
+t_tuple_size(Type) ->
+  t_tuple_size(Type, 'universe').
+
+%% to be used for a tuple with a known size (not ?any)
+-spec t_tuple_size(erl_type(), opaques()) -> non_neg_integer().
+
+t_tuple_size(Type, Opaques) ->
+  do_opaque(Type, Opaques, fun tuple_size1/1).
+
+tuple_size1(?tuple(_, Size, _)) when is_integer(Size) -> Size.
+
+-spec t_tuple_sizes(erl_type()) -> 'unknown' | [non_neg_integer(),...].
+
+t_tuple_sizes(Type) ->
+  do_opaque(Type, 'universe', fun tuple_sizes/1).
+
+tuple_sizes(?tuple(?any, ?any, ?any)) -> unknown;
+tuple_sizes(?tuple(_, Size, _)) when is_integer(Size) -> [Size];
+tuple_sizes(?tuple_set(List)) -> [Size || {Size, _} <- List].
+
+-spec t_tuple_subtypes(erl_type(), opaques()) ->
+         'unknown' | [erl_type(),...].
+
+t_tuple_subtypes(Type, Opaques) ->
+  Fun = fun(?tuple_set(List)) ->
+            t_tuple_subtypes_tuple_list(List, Opaques);
+           (?opaque(_)) -> unknown;
+           (T) -> t_tuple_subtypes(T)
+        end,
+  do_opaque(Type, Opaques, Fun).
+
+t_tuple_subtypes_tuple_list(List, Opaques) ->
+  lists:append([t_tuple_subtypes_list(Tuples, Opaques) ||
+                 {_Size, Tuples} <- List]).
+
+t_tuple_subtypes_list(List, Opaques) ->
+  ListOfLists = [t_tuple_subtypes(E, Opaques) || E <- List, E =/= ?none],
+  lists:append([L || L <- ListOfLists, L =/= 'unknown']).
+
+-spec t_tuple_subtypes(erl_type()) -> 'unknown' | [erl_type(),...].
+
+%% XXX. Not the same as t_tuple_subtypes(T, 'universe')...
+t_tuple_subtypes(?tuple(?any, ?any, ?any)) -> unknown;
+t_tuple_subtypes(?tuple(_, _, _) = T) -> [T];
+t_tuple_subtypes(?tuple_set(List)) ->
+  lists:append([Tuples || {_Size, Tuples} <- List]).
+
+-spec t_is_tuple(erl_type()) -> boolean().
+
+t_is_tuple(Type) ->
+  t_is_tuple(Type, 'universe').
+
+-spec t_is_tuple(erl_type(), opaques()) -> boolean().
+
+t_is_tuple(Type, Opaques) ->
+  do_opaque(Type, Opaques, fun is_tuple1/1).
+
+is_tuple1(?tuple(_, _, _)) -> true;
+is_tuple1(?tuple_set(_)) -> true;
+is_tuple1(_) -> false.
+
+%%-----------------------------------------------------------------------------
+%% Non-primitive types, including some handy syntactic sugar types
+%%
+
+-spec t_bitstrlist() -> erl_type().
+
+t_bitstrlist() ->
+  t_iolist(1, t_bitstr()).
+
+-spec t_arity() -> erl_type().
+
+t_arity() ->
+  t_from_range(0, 255).	% was t_byte().
+
+-spec t_pos_integer() -> erl_type().
+
+t_pos_integer() ->
+  t_from_range(1, pos_inf).
+
+-spec t_non_neg_integer() -> erl_type().
+
+t_non_neg_integer() ->
+  t_from_range(0, pos_inf).
+
+-spec t_is_non_neg_integer(erl_type()) -> boolean().
+
+t_is_non_neg_integer(?integer(_) = T) ->
+  t_is_subtype(T, t_non_neg_integer());
+t_is_non_neg_integer(_) -> false.
+
+-spec t_neg_integer() -> erl_type().
+
+t_neg_integer() ->
+  t_from_range(neg_inf, -1).
+
+-spec t_fixnum() -> erl_type().
+
+t_fixnum() ->
+  t_integer(). % Gross over-approximation
+
+-spec t_pos_fixnum() -> erl_type().
+
+t_pos_fixnum() ->
+  t_pos_integer().  % Gross over-approximation
+
+-spec t_non_neg_fixnum() -> erl_type().
+
+t_non_neg_fixnum() ->
+  t_non_neg_integer().  % Gross over-approximation
+
+-spec t_mfa() -> erl_type().
+
+t_mfa() ->
+  t_tuple([t_atom(), t_atom(), t_arity()]).
+
+-spec t_module() -> erl_type().
+
+t_module() ->
+  t_atom().
+
+-spec t_node() -> erl_type().
+
+t_node() ->
+  t_atom().
+
+-spec t_iodata() -> erl_type().
+
+t_iodata() ->
+  t_sup(t_iolist(), t_binary()).
+
+-spec t_iolist() -> erl_type().
+
+t_iolist() ->
+  t_iolist(1, t_binary()).
+
+%% Added a second argument which currently is t_binary() | t_bitstr()
+-spec t_iolist(non_neg_integer(), erl_type()) -> erl_type().
+
+t_iolist(N, T) when N > 0 ->
+  t_maybe_improper_list(t_sup([t_iolist(N-1, T), T, t_byte()]),
+		        t_sup(T, t_nil()));
+t_iolist(0, T) ->
+  t_maybe_improper_list(t_any(), t_sup(T, t_nil())).
+
+-spec t_timeout() -> erl_type().
+
+t_timeout() ->
+  t_sup(t_non_neg_integer(), t_atom('infinity')).
+
+%%------------------------------------
+
+%% ?none is allowed in products. A product of size 1 is not a product.
+
+-spec t_product([erl_type()]) -> erl_type().
+
+t_product([T]) -> T;
+t_product(Types) when is_list(Types) ->
+  ?product(Types).
+
+%% This function is intended to be the inverse of the one above.
+%% It should NOT be used with ?any, ?none or ?unit as input argument.
+
+-spec t_to_tlist(erl_type()) -> [erl_type()].
+
+t_to_tlist(?product(Types)) -> Types;
+t_to_tlist(T) when T =/= ?any orelse T =/= ?none orelse T =/= ?unit -> [T].
+
+%%------------------------------------
+
+-spec t_var(atom() | integer()) -> erl_type().
+
+t_var(Atom) when is_atom(Atom) -> ?var(Atom);
+t_var(Int) when is_integer(Int) -> ?var(Int).
+
+-spec t_is_var(erl_type()) -> boolean().
+
+t_is_var(?var(_)) -> true;
+t_is_var(_) -> false.
+
+-spec t_var_name(erl_type()) -> atom() | integer().
+
+t_var_name(?var(Id)) -> Id.
+
+-spec t_has_var(erl_type()) -> boolean().
+
+t_has_var(?var(_)) -> true;
+t_has_var(?function(Domain, Range)) ->
+  t_has_var(Domain) orelse t_has_var(Range);
+t_has_var(?list(Contents, Termination, _)) ->
+  t_has_var(Contents) orelse t_has_var(Termination);
+t_has_var(?product(Types)) -> t_has_var_list(Types);
+t_has_var(?tuple(?any, ?any, ?any)) -> false;
+t_has_var(?tuple(Elements, _, _)) ->
+  t_has_var_list(Elements);
+t_has_var(?tuple_set(_) = T) ->
+  t_has_var_list(t_tuple_subtypes(T));
+t_has_var(?map(_, DefK, _)= Map) ->
+  t_has_var_list(map_all_values(Map)) orelse
+    t_has_var(DefK);
+t_has_var(?opaque(Set)) ->
+  %% Assume variables in 'args' are also present i 'struct'
+  t_has_var_list([O#opaque.struct || O <- set_to_list(Set)]);
+t_has_var(?union(List)) ->
+  t_has_var_list(List);
+t_has_var(_) -> false.
+
+-spec t_has_var_list([erl_type()]) -> boolean().
+
+t_has_var_list([T|Ts]) ->
+  t_has_var(T) orelse t_has_var_list(Ts);
+t_has_var_list([]) -> false.
+
+-spec t_collect_vars(erl_type()) -> [erl_type()].
+
+t_collect_vars(T) ->
+  t_collect_vars(T, []).
+
+-spec t_collect_vars(erl_type(), [erl_type()]) -> [erl_type()].
+
+t_collect_vars(?var(_) = Var, Acc) ->
+  ordsets:add_element(Var, Acc);
+t_collect_vars(?function(Domain, Range), Acc) ->
+  ordsets:union(t_collect_vars(Domain, Acc), t_collect_vars(Range, []));
+t_collect_vars(?list(Contents, Termination, _), Acc) ->
+  ordsets:union(t_collect_vars(Contents, Acc), t_collect_vars(Termination, []));
+t_collect_vars(?product(Types), Acc) ->
+  t_collect_vars_list(Types, Acc);
+t_collect_vars(?tuple(?any, ?any, ?any), Acc) ->
+  Acc;
+t_collect_vars(?tuple(Types, _, _), Acc) ->
+  t_collect_vars_list(Types, Acc);
+t_collect_vars(?tuple_set(_) = TS, Acc) ->
+  t_collect_vars_list(t_tuple_subtypes(TS), Acc);
+t_collect_vars(?map(_, DefK, _) = Map, Acc0) ->
+  Acc = t_collect_vars_list(map_all_values(Map), Acc0),
+  t_collect_vars(DefK, Acc);
+t_collect_vars(?opaque(Set), Acc) ->
+  %% Assume variables in 'args' are also present i 'struct'
+  t_collect_vars_list([O#opaque.struct || O <- set_to_list(Set)], Acc);
+t_collect_vars(?union(List), Acc) ->
+  t_collect_vars_list(List, Acc);
+t_collect_vars(_, Acc) ->
+  Acc.
+
+t_collect_vars_list([T|Ts], Acc0) ->
+  Acc = t_collect_vars(T, Acc0),
+  t_collect_vars_list(Ts, Acc);
+t_collect_vars_list([], Acc) -> Acc.
+
+%%=============================================================================
+%%
+%% Type construction from Erlang terms.
+%%
+%%=============================================================================
+
+%%-----------------------------------------------------------------------------
+%% Make a type from a term. No type depth is enforced.
+%%
+
+-spec t_from_term(term()) -> erl_type().
+
+t_from_term([H|T]) ->                  t_cons(t_from_term(H), t_from_term(T));
+t_from_term([]) ->                     t_nil();
+t_from_term(T) when is_atom(T) ->      t_atom(T);
+t_from_term(T) when is_bitstring(T) -> t_bitstr(0, erlang:bit_size(T));
+t_from_term(T) when is_float(T) ->     t_float();
+t_from_term(T) when is_function(T) ->
+  {arity, Arity} = erlang:fun_info(T, arity),
+  t_fun(Arity, t_any());
+t_from_term(T) when is_integer(T) ->   t_integer(T);
+t_from_term(T) when is_map(T) ->
+  Pairs = [{t_from_term(K), ?mand, t_from_term(V)}
+	   || {K, V} <- maps:to_list(T)],
+  {Stons, Rest} = lists:partition(fun({K,_,_}) -> is_singleton_type(K) end,
+				  Pairs),
+  {DefK, DefV}
+    = lists:foldl(fun({K,_,V},{AK,AV}) -> {t_sup(K,AK), t_sup(V,AV)} end,
+		  {t_none(), t_none()}, Rest),
+  t_map(lists:keysort(1, Stons), DefK, DefV);
+t_from_term(T) when is_pid(T) ->       t_pid();
+t_from_term(T) when is_port(T) ->      t_port();
+t_from_term(T) when is_reference(T) -> t_reference();
+t_from_term(T) when is_tuple(T) ->
+  t_tuple([t_from_term(E) || E <- tuple_to_list(T)]).
+
+%%-----------------------------------------------------------------------------
+%% Integer types from a range.
+%%-----------------------------------------------------------------------------
+
+%%-define(USE_UNSAFE_RANGES, true).
+
+-spec t_from_range(rng_elem(), rng_elem()) -> erl_type().
+
+-ifdef(USE_UNSAFE_RANGES).
+
+t_from_range(X, Y) ->
+  t_from_range_unsafe(X, Y).
+
+-else.
+
+t_from_range(neg_inf, pos_inf) -> t_integer();
+t_from_range(neg_inf, Y) when is_integer(Y), Y < 0  -> ?integer_neg;
+t_from_range(neg_inf, Y) when is_integer(Y), Y >= 0 -> t_integer();
+t_from_range(X, pos_inf) when is_integer(X), X >= 1 -> ?integer_pos;
+t_from_range(X, pos_inf) when is_integer(X), X >= 0 -> ?integer_non_neg;
+t_from_range(X, pos_inf) when is_integer(X), X < 0  -> t_integer();
+t_from_range(X, Y) when is_integer(X), is_integer(Y), X > Y -> t_none();
+t_from_range(X, Y) when is_integer(X), is_integer(Y) ->
+  case ((Y - X) < ?SET_LIMIT) of 
+    true -> t_integers(lists:seq(X, Y));
+    false ->
+      case X >= 0 of
+	false -> 
+	  if Y < 0 -> ?integer_neg;
+	     true -> t_integer()
+	  end;
+	true ->
+	  if Y =< ?MAX_BYTE, X >= 1 -> ?int_range(1, ?MAX_BYTE);
+	     Y =< ?MAX_BYTE -> t_byte();
+	     Y =< ?MAX_CHAR, X >= 1 -> ?int_range(1, ?MAX_CHAR);
+	     Y =< ?MAX_CHAR -> t_char();
+	     X >= 1         -> ?integer_pos;
+	     X >= 0         -> ?integer_non_neg
+	  end
+      end
+  end;
+t_from_range(pos_inf, neg_inf) -> t_none().
+
+-endif.
+
+-spec t_from_range_unsafe(rng_elem(), rng_elem()) -> erl_type().
+
+t_from_range_unsafe(neg_inf, pos_inf) -> t_integer();
+t_from_range_unsafe(neg_inf, Y) -> ?int_range(neg_inf, Y);
+t_from_range_unsafe(X, pos_inf) -> ?int_range(X, pos_inf);
+t_from_range_unsafe(X, Y) when is_integer(X), is_integer(Y), X =< Y ->
+  if (Y - X) < ?SET_LIMIT -> t_integers(lists:seq(X, Y));
+     true -> ?int_range(X, Y)
+  end;
+t_from_range_unsafe(X, Y) when is_integer(X), is_integer(Y) -> t_none();
+t_from_range_unsafe(pos_inf, neg_inf) -> t_none().
+
+-spec t_is_fixnum(erl_type()) -> boolean().
+
+t_is_fixnum(?int_range(neg_inf, _)) -> false;
+t_is_fixnum(?int_range(_, pos_inf)) -> false;
+t_is_fixnum(?int_range(From, To)) ->
+  is_fixnum(From) andalso is_fixnum(To);
+t_is_fixnum(?int_set(Set)) ->
+  is_fixnum(set_min(Set)) andalso is_fixnum(set_max(Set));
+t_is_fixnum(_) -> false.
+
+-spec is_fixnum(integer()) -> boolean().
+
+is_fixnum(N) when is_integer(N) ->
+  Bits = ?BITS,
+  (N =< ((1 bsl (Bits - 1)) - 1)) andalso (N >= -(1 bsl (Bits - 1))).
+
+infinity_geq(pos_inf, _) -> true;
+infinity_geq(_, pos_inf) -> false;
+infinity_geq(_, neg_inf) -> true;
+infinity_geq(neg_inf, _) -> false;
+infinity_geq(A, B) -> A >= B.
+
+-spec t_is_bitwidth(erl_type()) -> boolean().
+
+t_is_bitwidth(?int_range(neg_inf, _)) -> false;
+t_is_bitwidth(?int_range(_, pos_inf)) -> false;
+t_is_bitwidth(?int_range(From, To)) ->
+  infinity_geq(From, 0) andalso infinity_geq(?BITS, To);
+t_is_bitwidth(?int_set(Set)) ->
+  infinity_geq(set_min(Set), 0) andalso infinity_geq(?BITS, set_max(Set));
+t_is_bitwidth(_) -> false.
+
+-spec number_min(erl_type()) -> rng_elem().
+
+number_min(Type) ->
+  number_min(Type, 'universe').
+
+-spec number_min(erl_type(), opaques()) -> rng_elem().
+
+number_min(Type, Opaques) ->
+  do_opaque(Type, Opaques, fun number_min2/1).
+
+number_min2(?int_range(From, _)) -> From;
+number_min2(?int_set(Set)) -> set_min(Set);
+number_min2(?number(?any, _Tag)) -> neg_inf.
+
+-spec number_max(erl_type()) -> rng_elem().
+
+number_max(Type) ->
+  number_max(Type, 'universe').
+
+-spec number_max(erl_type(), opaques()) -> rng_elem().
+
+number_max(Type, Opaques) ->
+  do_opaque(Type, Opaques, fun number_max2/1).
+
+number_max2(?int_range(_, To)) -> To;
+number_max2(?int_set(Set)) -> set_max(Set);
+number_max2(?number(?any, _Tag)) -> pos_inf.
+
+%% -spec int_range(rgn_elem(), rng_elem()) -> erl_type().
+%%
+%% int_range(neg_inf, pos_inf)         -> t_integer();
+%% int_range(neg_inf, To)              -> ?int_range(neg_inf, To);
+%% int_range(From, pos_inf)            -> ?int_range(From, pos_inf);
+%% int_range(From, To) when From =< To -> t_from_range(From, To);
+%% int_range(From, To) when To < From  -> ?none.  
+
+in_range(_, ?int_range(neg_inf, pos_inf)) -> true;
+in_range(X, ?int_range(From, pos_inf))    -> X >= From;
+in_range(X, ?int_range(neg_inf, To))      -> X =< To;
+in_range(X, ?int_range(From, To))         -> (X >= From) andalso (X =< To).
+
+-spec min(rng_elem(), rng_elem()) -> rng_elem().
+
+min(neg_inf, _) -> neg_inf;
+min(_, neg_inf) -> neg_inf;
+min(pos_inf, Y) -> Y;
+min(X, pos_inf) -> X;
+min(X, Y) when X =< Y -> X;
+min(_, Y) -> Y.
+
+-spec max(rng_elem(), rng_elem()) -> rng_elem().
+
+max(neg_inf, Y) -> Y;
+max(X, neg_inf) -> X;
+max(pos_inf, _) -> pos_inf;
+max(_, pos_inf) -> pos_inf;
+max(X, Y) when X =< Y -> Y;
+max(X, _) -> X.
+
+expand_range_from_set(Range = ?int_range(From, To), Set) ->
+  Min = min(set_min(Set), From),
+  Max = max(set_max(Set), To),
+  if From =:= Min, To =:= Max -> Range;
+     true -> t_from_range(Min, Max)
+  end.
+
+%%=============================================================================
+%%
+%% Lattice operations
+%%
+%%=============================================================================
+
+%%-----------------------------------------------------------------------------
+%% Supremum
+%%
+
+-spec t_sup([erl_type()]) -> erl_type().
+
+t_sup([]) -> ?none;
+t_sup(Ts) ->
+  case lists:any(fun is_any/1, Ts) of
+    true -> ?any;
+    false ->
+      t_sup1(Ts, [])
+  end.
+
+t_sup1([H1, H2|T], L) ->
+  t_sup1(T, [t_sup(H1, H2)|L]);
+t_sup1([T], []) -> subst_all_vars_to_any(T);
+t_sup1(Ts, L) ->
+  t_sup1(Ts++L, []).
+
+-spec t_sup(erl_type(), erl_type()) -> erl_type().
+
+t_sup(?any, _) -> ?any;
+t_sup(_, ?any) -> ?any;
+t_sup(?none, T) -> T;
+t_sup(T, ?none) -> T;
+t_sup(?unit, T) -> T;
+t_sup(T, ?unit) -> T;
+t_sup(T, T) -> subst_all_vars_to_any(T);
+t_sup(?var(_), _) -> ?any;
+t_sup(_, ?var(_)) -> ?any;
+t_sup(?atom(Set1), ?atom(Set2)) ->
+  ?atom(set_union(Set1, Set2));
+t_sup(?bitstr(U1, B1), ?bitstr(U2, B2)) ->
+  t_bitstr(gcd(gcd(U1, U2), abs(B1-B2)), lists:min([B1, B2]));
+t_sup(?function(Domain1, Range1), ?function(Domain2, Range2)) ->
+  %% The domain is either a product or any.
+  ?function(t_sup(Domain1, Domain2), t_sup(Range1, Range2));
+t_sup(?identifier(Set1), ?identifier(Set2)) ->
+  ?identifier(set_union(Set1, Set2));
+t_sup(?opaque(Set1), ?opaque(Set2)) ->
+  sup_opaque(set_to_list(ordsets:union(Set1, Set2)));
+%%Disallow unions with opaque types
+%%t_sup(T1=?opaque(_,_,_), T2) ->
+%%  io:format("Debug: t_sup executed with args ~w and ~w~n",[T1, T2]), ?none;
+%%t_sup(T1, T2=?opaque(_,_,_)) ->
+%%  io:format("Debug: t_sup executed with args ~w and ~w~n",[T1, T2]), ?none;
+t_sup(?matchstate(Pres1, Slots1), ?matchstate(Pres2, Slots2)) ->
+  ?matchstate(t_sup(Pres1, Pres2), t_sup(Slots1, Slots2));
+t_sup(?nil, ?nil) -> ?nil;
+t_sup(?nil, ?list(Contents, Termination, _)) ->
+  ?list(Contents, t_sup(?nil, Termination), ?unknown_qual);
+t_sup(?list(Contents, Termination, _), ?nil) ->
+  ?list(Contents, t_sup(?nil, Termination), ?unknown_qual);
+t_sup(?list(Contents1, Termination1, Size1), 
+      ?list(Contents2, Termination2, Size2)) ->
+  NewSize =
+    case {Size1, Size2} of
+      {?unknown_qual, ?unknown_qual} -> ?unknown_qual;
+      {?unknown_qual, ?nonempty_qual} -> ?unknown_qual;
+      {?nonempty_qual, ?unknown_qual} -> ?unknown_qual;
+      {?nonempty_qual, ?nonempty_qual} -> ?nonempty_qual
+    end,
+  NewContents = t_sup(Contents1, Contents2),
+  NewTermination = t_sup(Termination1, Termination2),
+  TmpList = t_cons(NewContents, NewTermination),
+  case NewSize of
+    ?nonempty_qual -> TmpList;
+    ?unknown_qual ->
+      ?list(FinalContents, FinalTermination, _) = TmpList,
+      ?list(FinalContents, FinalTermination, ?unknown_qual)
+  end;
+t_sup(?number(_, _), ?number(?any, ?unknown_qual) = T) -> T;  
+t_sup(?number(?any, ?unknown_qual) = T, ?number(_, _)) -> T;
+t_sup(?float, ?float) -> ?float;
+t_sup(?float, ?integer(_)) -> t_number();
+t_sup(?integer(_), ?float) -> t_number();
+t_sup(?integer(?any) = T, ?integer(_)) -> T;
+t_sup(?integer(_), ?integer(?any) = T) -> T;
+t_sup(?int_set(Set1), ?int_set(Set2)) ->
+  case set_union(Set1, Set2) of
+    ?any ->
+      t_from_range(min(set_min(Set1), set_min(Set2)), 
+		   max(set_max(Set1), set_max(Set2)));
+    Set -> ?int_set(Set)
+  end;
+t_sup(?int_range(From1, To1), ?int_range(From2, To2)) ->
+  t_from_range(min(From1, From2), max(To1, To2));
+t_sup(Range = ?int_range(_, _), ?int_set(Set)) ->
+  expand_range_from_set(Range, Set);
+t_sup(?int_set(Set), Range = ?int_range(_, _)) ->
+  expand_range_from_set(Range, Set);
+t_sup(?product(Types1), ?product(Types2)) ->
+  L1 = length(Types1),
+  L2 = length(Types2),
+  if L1 =:= L2 -> ?product(t_sup_lists(Types1, Types2));
+     true -> ?any
+  end;
+t_sup(?product(_), _) ->
+  ?any;
+t_sup(_, ?product(_)) ->
+  ?any;
+t_sup(?tuple(?any, ?any, ?any) = T, ?tuple(_, _, _)) -> T;
+t_sup(?tuple(_, _, _), ?tuple(?any, ?any, ?any) = T) -> T;
+t_sup(?tuple(?any, ?any, ?any) = T, ?tuple_set(_)) -> T;
+t_sup(?tuple_set(_), ?tuple(?any, ?any, ?any) = T) -> T;
+t_sup(?tuple(Elements1, Arity, Tag1) = T1,
+      ?tuple(Elements2, Arity, Tag2) = T2) ->
+  if Tag1 =:= Tag2 -> t_tuple(t_sup_lists(Elements1, Elements2));
+     Tag1 =:= ?any -> t_tuple(t_sup_lists(Elements1, Elements2));
+     Tag2 =:= ?any -> t_tuple(t_sup_lists(Elements1, Elements2));
+     Tag1 < Tag2 -> ?tuple_set([{Arity, [T1, T2]}]);
+     Tag1 > Tag2 -> ?tuple_set([{Arity, [T2, T1]}])
+  end;
+t_sup(?tuple(_, Arity1, _) = T1, ?tuple(_, Arity2, _) = T2) ->
+  sup_tuple_sets([{Arity1, [T1]}], [{Arity2, [T2]}]);
+t_sup(?tuple_set(List1), ?tuple_set(List2)) ->
+  sup_tuple_sets(List1, List2);
+t_sup(?tuple_set(List1), T2 = ?tuple(_, Arity, _)) ->
+  sup_tuple_sets(List1, [{Arity, [T2]}]);
+t_sup(?tuple(_, Arity, _) = T1, ?tuple_set(List2)) ->
+  sup_tuple_sets([{Arity, [T1]}], List2);
+t_sup(?map(_, ADefK, ADefV) = A, ?map(_, BDefK, BDefV) = B) ->
+  Pairs =
+    map_pairwise_merge(
+      fun(K, MNess, V1, MNess, V2) -> {K, MNess, t_sup(V1, V2)};
+	 (K, _,     V1, _,     V2) -> {K, ?opt,  t_sup(V1, V2)}
+      end, A, B),
+  t_map(Pairs, t_sup(ADefK, BDefK), t_sup(ADefV, BDefV));
+t_sup(T1, T2) ->
+  ?union(U1) = force_union(T1),
+  ?union(U2) = force_union(T2),
+  sup_union(U1, U2).
+
+sup_opaque([]) -> ?none;
+sup_opaque(List) ->
+  L = sup_opaq(List),
+  ?opaque(ordsets:from_list(L)).
+
+sup_opaq(L0) ->
+  L1 = [{{Mod,Name,Args}, T} ||
+         #opaque{mod = Mod, name = Name, args = Args}=T <- L0],
+  F = family(L1),
+  [supl(Ts) || {_, Ts} <- F].
+
+supl([O]) -> O;
+supl(Ts) -> supl(Ts, t_none()).
+
+supl([#opaque{struct = S}=O|L], S0) ->
+  S1 = t_sup(S, S0),
+  case L =:= [] of
+    true -> O#opaque{struct = S1};
+    false -> supl(L, S1)
+  end.
+
+-spec t_sup_lists([erl_type()], [erl_type()]) -> [erl_type()].
+
+t_sup_lists([T1|Left1], [T2|Left2]) ->
+  [t_sup(T1, T2)|t_sup_lists(Left1, Left2)];
+t_sup_lists([], []) ->
+  [].
+
+sup_tuple_sets(L1, L2) ->
+  TotalArities = ordsets:union([Arity || {Arity, _} <- L1],
+			       [Arity || {Arity, _} <- L2]),
+  if length(TotalArities) > ?TUPLE_ARITY_LIMIT -> t_tuple();
+     true ->
+      case sup_tuple_sets(L1, L2, []) of
+	[{_Arity, [OneTuple = ?tuple(_, _, _)]}] -> OneTuple;
+	List -> ?tuple_set(List)
+      end
+  end.
+
+sup_tuple_sets([{Arity, Tuples1}|Left1], [{Arity, Tuples2}|Left2], Acc) ->
+  NewAcc = [{Arity, sup_tuples_in_set(Tuples1, Tuples2)}|Acc],
+  sup_tuple_sets(Left1, Left2, NewAcc);
+sup_tuple_sets([{Arity1, _} = T1|Left1] = L1, 
+	       [{Arity2, _} = T2|Left2] = L2, Acc) ->
+  if Arity1 < Arity2 -> sup_tuple_sets(Left1, L2, [T1|Acc]);
+     Arity1 > Arity2 -> sup_tuple_sets(L1, Left2, [T2|Acc])
+  end;
+sup_tuple_sets([], L2, Acc) -> lists:reverse(Acc, L2);
+sup_tuple_sets(L1, [], Acc) -> lists:reverse(Acc, L1).
+
+sup_tuples_in_set([?tuple(_, _, ?any) = T], L) ->
+  [t_tuple(sup_tuple_elements([T|L]))];
+sup_tuples_in_set(L, [?tuple(_, _, ?any) = T]) ->
+  [t_tuple(sup_tuple_elements([T|L]))];
+sup_tuples_in_set(L1, L2) ->
+  FoldFun = fun(?tuple(_, _, Tag), AccTag) -> t_sup(Tag, AccTag) end,
+  TotalTag0 = lists:foldl(FoldFun, ?none, L1),
+  TotalTag  = lists:foldl(FoldFun, TotalTag0, L2),
+  case TotalTag of
+    ?atom(?any) -> 
+      %% We will reach the set limit. Widen now.
+      [t_tuple(sup_tuple_elements(L1 ++ L2))];
+    ?atom(Set) ->
+      case set_size(Set) > ?TUPLE_TAG_LIMIT of
+	true ->
+	  %% We will reach the set limit. Widen now.
+	  [t_tuple(sup_tuple_elements(L1 ++ L2))];
+	false ->
+	  %% We can go on and build the tuple set.
+	  sup_tuples_in_set(L1, L2, [])
+      end
+  end.
+
+sup_tuple_elements([?tuple(Elements, _, _)|L]) ->
+  lists:foldl(fun (?tuple(Es, _, _), Acc) -> t_sup_lists(Es, Acc) end,
+	      Elements, L).
+
+sup_tuples_in_set([?tuple(Elements1, Arity, Tag1) = T1|Left1] = L1,
+		  [?tuple(Elements2, Arity, Tag2) = T2|Left2] = L2, Acc) ->
+  if 
+    Tag1 < Tag2   -> sup_tuples_in_set(Left1, L2, [T1|Acc]);
+    Tag1 > Tag2   -> sup_tuples_in_set(L1, Left2, [T2|Acc]);
+    Tag2 =:= Tag2 -> NewElements = t_sup_lists(Elements1, Elements2),
+		     NewAcc = [?tuple(NewElements, Arity, Tag1)|Acc],
+		     sup_tuples_in_set(Left1, Left2, NewAcc)
+  end;
+sup_tuples_in_set([], L2, Acc) -> lists:reverse(Acc, L2);
+sup_tuples_in_set(L1, [], Acc) -> lists:reverse(Acc, L1).
+
+sup_union(U1, U2) ->
+  sup_union(U1, U2, 0, []).
+
+sup_union([?none|Left1], [?none|Left2], N, Acc) ->
+  sup_union(Left1, Left2, N, [?none|Acc]);
+sup_union([T1|Left1], [T2|Left2], N, Acc) ->
+  sup_union(Left1, Left2, N+1, [t_sup(T1, T2)|Acc]);
+sup_union([], [], N, Acc) ->
+  if N =:= 0 -> ?none;
+     N =:= 1 -> 
+      [Type] = [T || T <- Acc, T =/= ?none],
+      Type;
+     N =:= length(Acc) -> ?any;
+     true -> ?union(lists:reverse(Acc))
+  end.
+
+force_union(T = ?atom(_)) ->          ?atom_union(T);
+force_union(T = ?bitstr(_, _)) ->     ?bitstr_union(T); 
+force_union(T = ?function(_, _)) ->   ?function_union(T);
+force_union(T = ?identifier(_)) ->    ?identifier_union(T);
+force_union(T = ?list(_, _, _)) ->    ?list_union(T);
+force_union(T = ?nil) ->              ?list_union(T);
+force_union(T = ?number(_, _)) ->     ?number_union(T);
+force_union(T = ?opaque(_)) ->        ?opaque_union(T);
+force_union(T = ?map(_,_,_)) ->       ?map_union(T);
+force_union(T = ?tuple(_, _, _)) ->   ?tuple_union(T);
+force_union(T = ?tuple_set(_)) ->     ?tuple_union(T);
+force_union(T = ?matchstate(_, _)) -> ?matchstate_union(T);
+force_union(T = ?union(_)) ->         T.
+
+%%-----------------------------------------------------------------------------
+%% An attempt to write the inverse operation of t_sup/1 -- XXX: INCOMPLETE !!
+%%
+
+-spec t_elements(erl_type()) -> [erl_type()].
+
+t_elements(?none) -> [];
+t_elements(?unit) -> [];
+t_elements(?any = T) -> [T];
+t_elements(?nil = T) -> [T];
+t_elements(?atom(?any) = T) -> [T];
+t_elements(?atom(Atoms)) ->
+  [t_atom(A) || A <- Atoms];
+t_elements(?bitstr(_, _) = T) -> [T];
+t_elements(?function(_, _) = T) -> [T];
+t_elements(?identifier(?any) = T) -> [T];
+t_elements(?identifier(IDs)) ->
+  [?identifier([T]) || T <- IDs];
+t_elements(?list(_, _, _) = T) -> [T];
+t_elements(?number(_, _) = T) ->
+  case T of
+    ?number(?any, ?unknown_qual) ->
+      [?float, ?integer(?any)];
+    ?float -> [T];
+    ?integer(?any) -> [T];
+    ?int_range(_, _) -> [T];
+    ?int_set(Set) ->
+      [t_integer(I) || I <- Set]
+  end;
+t_elements(?opaque(_) = T) ->
+  do_elements(T);
+t_elements(?map(_,_,_) = T) -> [T];
+t_elements(?tuple(_, _, _) = T) -> [T];
+t_elements(?tuple_set(_) = TS) ->
+  case t_tuple_subtypes(TS) of
+    unknown -> [];
+    Elems -> Elems
+  end;
+t_elements(?union(_) = T) ->
+  do_elements(T);
+t_elements(?var(_)) -> [?any].  %% yes, vars exist -- what else to do here?
+%% t_elements(T) ->
+%%   io:format("T_ELEMENTS => ~p\n", [T]).
+
+do_elements(Type0) ->
+  case do_opaque(Type0, 'universe', fun(T) -> T end) of
+    ?union(List) -> lists:append([t_elements(T) || T <- List]);
+    Type -> t_elements(Type)
+  end.
+
+%%-----------------------------------------------------------------------------
+%% Infimum
+%%
+
+-spec t_inf([erl_type()]) -> erl_type().
+
+t_inf([H1, H2|T]) ->
+  case t_inf(H1, H2) of
+    ?none -> ?none;
+    NewH -> t_inf([NewH|T])
+  end;
+t_inf([H]) -> H;
+t_inf([]) -> ?none.
+
+-spec t_inf(erl_type(), erl_type()) -> erl_type().
+
+t_inf(T1, T2) ->
+  t_inf(T1, T2, 'universe').
+
+%% 'match' should be used from t_find_unknown_opaque() only
+-type t_inf_opaques() :: opaques() | {'match', [erl_type() | 'universe']}.
+
+-spec t_inf(erl_type(), erl_type(), t_inf_opaques()) -> erl_type().
+
+t_inf(?var(_), ?var(_), _Opaques) -> ?any;
+t_inf(?var(_), T, _Opaques) -> subst_all_vars_to_any(T);
+t_inf(T, ?var(_), _Opaques) -> subst_all_vars_to_any(T);
+t_inf(?any, T, _Opaques) -> subst_all_vars_to_any(T);
+t_inf(T, ?any, _Opaques) -> subst_all_vars_to_any(T);
+t_inf(?none, _, _Opaques) -> ?none;
+t_inf(_, ?none, _Opaques) -> ?none;
+t_inf(?unit, _, _Opaques) -> ?unit;	% ?unit cases should appear below ?none
+t_inf(_, ?unit, _Opaques) -> ?unit;
+t_inf(T, T, _Opaques) -> subst_all_vars_to_any(T);
+t_inf(?atom(Set1), ?atom(Set2), _) ->
+  case set_intersection(Set1, Set2) of
+    ?none ->  ?none;
+    NewSet -> ?atom(NewSet)
+  end;
+t_inf(?bitstr(U1, B1), ?bitstr(0, B2), _Opaques) ->
+  if B2 >= B1 andalso (B2-B1) rem U1 =:= 0 -> t_bitstr(0, B2);
+     true -> ?none
+  end;
+t_inf(?bitstr(0, B1), ?bitstr(U2, B2), _Opaques) ->
+  if B1 >= B2 andalso (B1-B2) rem U2 =:= 0 -> t_bitstr(0, B1);
+     true -> ?none
+  end;
+t_inf(?bitstr(U1, B1), ?bitstr(U1, B1), _Opaques) ->
+  t_bitstr(U1, B1);
+t_inf(?bitstr(U1, B1), ?bitstr(U2, B2), _Opaques) when U2 > U1 ->
+  inf_bitstr(U2, B2, U1, B1);
+t_inf(?bitstr(U1, B1), ?bitstr(U2, B2), _Opaques) ->
+  inf_bitstr(U1, B1, U2, B2);
+t_inf(?function(Domain1, Range1), ?function(Domain2, Range2), Opaques) ->
+  case t_inf(Domain1, Domain2, Opaques) of
+    ?none -> ?none;
+    Domain -> ?function(Domain, t_inf(Range1, Range2, Opaques))
+  end;
+t_inf(?identifier(Set1), ?identifier(Set2), _Opaques) ->
+  case set_intersection(Set1, Set2) of
+    ?none -> ?none;
+    Set -> ?identifier(Set)
+  end;
+t_inf(?map(_, ADefK, ADefV) = A, ?map(_, BDefK, BDefV) = B, _Opaques) ->
+  %% Because it simplifies the anonymous function, we allow Pairs to temporarily
+  %% contain mandatory pairs with none values, since all such cases should
+  %% result in a none result.
+  Pairs =
+    map_pairwise_merge(
+      %% For optional keys in both maps, when the infinimum is none, we have
+      %% essentially concluded that K must not be a key in the map.
+      fun(K, ?opt, V1, ?opt, V2) -> {K, ?opt, t_inf(V1, V2)};
+	 %% When a key is optional in one map, but mandatory in another, it
+	 %% becomes mandatory in the infinumum
+	 (K, _, V1, _, V2) -> {K, ?mand, t_inf(V1, V2)}
+      end, A, B),
+  %% If the infinimum of any mandatory values is ?none, the entire map infinimum
+  %% is ?none.
+  case lists:any(fun({_,?mand,?none})->true; ({_,_,_}) -> false end, Pairs) of
+    true -> t_none();
+    false -> t_map(Pairs, t_inf(ADefK, BDefK), t_inf(ADefV, BDefV))
+  end;
+t_inf(?matchstate(Pres1, Slots1), ?matchstate(Pres2, Slots2), _Opaques) ->
+  ?matchstate(t_inf(Pres1, Pres2), t_inf(Slots1, Slots2));
+t_inf(?nil, ?nil, _Opaques) -> ?nil;
+t_inf(?nil, ?nonempty_list(_, _), _Opaques) ->
+  ?none;
+t_inf(?nonempty_list(_, _), ?nil, _Opaques) ->
+  ?none;
+t_inf(?nil, ?list(_Contents, Termination, _), Opaques) ->
+  t_inf(?nil, t_unopaque(Termination), Opaques);
+t_inf(?list(_Contents, Termination, _), ?nil, Opaques) ->
+  t_inf(?nil, t_unopaque(Termination), Opaques);
+t_inf(?list(Contents1, Termination1, Size1),
+      ?list(Contents2, Termination2, Size2), Opaques) ->
+  case t_inf(Termination1, Termination2, Opaques) of
+    ?none -> ?none;
+    Termination ->
+      case t_inf(Contents1, Contents2, Opaques) of
+	?none ->
+	  %% If none of the lists are nonempty, then the infimum is nil.
+	  case (Size1 =:= ?unknown_qual) andalso (Size2 =:= ?unknown_qual) of
+	    true -> t_nil();
+	    false -> ?none
+	  end;
+	Contents ->
+	  Size =
+	    case {Size1, Size2} of
+	      {?unknown_qual, ?unknown_qual} -> ?unknown_qual;
+	      {?unknown_qual, ?nonempty_qual} -> ?nonempty_qual;
+	      {?nonempty_qual, ?unknown_qual} -> ?nonempty_qual;
+	      {?nonempty_qual, ?nonempty_qual} -> ?nonempty_qual
+	    end,
+	  ?list(Contents, Termination, Size)
+      end
+  end;
+t_inf(?number(_, _) = T1, ?number(_, _) = T2, _Opaques) ->
+  case {T1, T2} of
+    {T, T}                            -> T;
+    {_, ?number(?any, ?unknown_qual)} -> T1;
+    {?number(?any, ?unknown_qual), _} -> T2;
+    {?float, ?integer(_)}             -> ?none;
+    {?integer(_), ?float}             -> ?none;
+    {?integer(?any), ?integer(_)}     -> T2;
+    {?integer(_), ?integer(?any)}     -> T1;
+    {?int_set(Set1), ?int_set(Set2)}  ->
+      case set_intersection(Set1, Set2) of
+	?none -> ?none;
+	Set -> ?int_set(Set)
+      end;
+    {?int_range(From1, To1), ?int_range(From2, To2)} ->
+      t_from_range(max(From1, From2), min(To1, To2));
+    {Range = ?int_range(_, _), ?int_set(Set)} ->
+      %% io:format("t_inf range, set args ~p ~p ~n", [T1, T2]),
+      Ans2 =
+	case set_filter(fun(X) -> in_range(X, Range) end, Set) of
+	  ?none -> ?none;
+	  NewSet -> ?int_set(NewSet)
+	end,
+      %% io:format("Ans2 ~p ~n", [Ans2]),
+      Ans2;
+    {?int_set(Set), ?int_range(_, _) = Range} ->
+      case set_filter(fun(X) -> in_range(X, Range) end, Set) of
+	?none -> ?none;
+	NewSet -> ?int_set(NewSet)
+      end
+  end;
+t_inf(?product(Types1), ?product(Types2), Opaques) ->
+  L1 = length(Types1),
+  L2 = length(Types2),
+  if L1 =:= L2 -> ?product(t_inf_lists(Types1, Types2, Opaques));
+     true -> ?none
+  end;
+t_inf(?product(_), _, _Opaques) ->
+  ?none;
+t_inf(_, ?product(_), _Opaques) ->
+  ?none;
+t_inf(?tuple(?any, ?any, ?any), ?tuple(_, _, _) = T, _Opaques) ->
+  subst_all_vars_to_any(T);
+t_inf(?tuple(_, _, _) = T, ?tuple(?any, ?any, ?any), _Opaques) ->
+  subst_all_vars_to_any(T);
+t_inf(?tuple(?any, ?any, ?any), ?tuple_set(_) = T, _Opaques) ->
+  subst_all_vars_to_any(T);
+t_inf(?tuple_set(_) = T, ?tuple(?any, ?any, ?any), _Opaques) ->
+  subst_all_vars_to_any(T);
+t_inf(?tuple(Elements1, Arity, _Tag1), ?tuple(Elements2, Arity, _Tag2), Opaques) ->
+  case t_inf_lists_strict(Elements1, Elements2, Opaques) of
+    bottom -> ?none;
+    NewElements -> t_tuple(NewElements)
+  end;
+t_inf(?tuple_set(List1), ?tuple_set(List2), Opaques) ->
+  inf_tuple_sets(List1, List2, Opaques);
+t_inf(?tuple_set(List), ?tuple(_, Arity, _) = T, Opaques) ->
+  inf_tuple_sets(List, [{Arity, [T]}], Opaques);
+t_inf(?tuple(_, Arity, _) = T, ?tuple_set(List), Opaques) ->
+  inf_tuple_sets(List, [{Arity, [T]}], Opaques);
+%% be careful: here and in the next clause T can be ?opaque
+t_inf(?union(U1), T, Opaques) ->
+  ?union(U2) = force_union(T),
+  inf_union(U1, U2, Opaques);
+t_inf(T, ?union(U2), Opaques) ->
+  ?union(U1) = force_union(T),
+  inf_union(U1, U2, Opaques);
+t_inf(?opaque(Set1), ?opaque(Set2), Opaques) ->
+  inf_opaque(Set1, Set2, Opaques);
+t_inf(?opaque(_) = T1, T2, Opaques) ->
+  inf_opaque1(T2, T1, 1, Opaques);
+t_inf(T1, ?opaque(_) = T2, Opaques) ->
+  inf_opaque1(T1, T2, 2, Opaques);
+%% and as a result, the cases for ?opaque should appear *after* ?union
+t_inf(#c{}, #c{}, _) ->
+  ?none.
+
+inf_opaque1(T1, ?opaque(Set2)=T2, Pos, Opaques) ->
+  case Opaques =:= 'universe' orelse inf_is_opaque_type(T2, Pos, Opaques) of
+    false -> ?none;
+    true ->
+      List2 = set_to_list(Set2),
+      case inf_collect(T1, List2, Opaques, []) of
+        [] -> ?none;
+        OpL -> ?opaque(ordsets:from_list(OpL))
+      end
+  end.
+
+inf_is_opaque_type(T, Pos, {match, Opaques}) ->
+  is_opaque_type(T, Opaques) orelse throw({pos, [Pos]});
+inf_is_opaque_type(T, _Pos, Opaques) ->
+  is_opaque_type(T, Opaques).
+
+inf_collect(T1, [T2|List2], Opaques, OpL) ->
+  #opaque{struct = S2} = T2,
+  case t_inf(T1, S2, Opaques) of
+    ?none -> inf_collect(T1, List2, Opaques, OpL);
+    Inf ->
+      Op = T2#opaque{struct = Inf},
+      inf_collect(T1, List2, Opaques, [Op|OpL])
+  end;
+inf_collect(_T1, [], _Opaques, OpL) ->
+  OpL.
+
+combine(S, T1, T2) ->
+  #opaque{mod = Mod1, name = Name1, args = Args1} = T1,
+  #opaque{mod = Mod2, name = Name2, args = Args2} = T2,
+  Comb1 = comb(Mod1, Name1, Args1, S, T1),
+  case is_compat_opaque_names({Mod1, Name1, Args1}, {Mod2, Name2, Args2}) of
+    true  -> Comb1;
+    false -> Comb1 ++ comb(Mod2, Name2, Args2, S, T2)
+  end.
+
+comb(Mod, Name, Args, S, T) ->
+  case can_combine_opaque_names(Mod, Name, Args, S) of
+    true ->
+      ?opaque(Set) = S,
+      Set;
+    false ->
+      [T#opaque{struct = S}]
+  end.
+
+can_combine_opaque_names(Mod1, Name1, Args1,
+               ?opaque([#opaque{mod = Mod2, name = Name2, args = Args2}])) ->
+  is_compat_opaque_names({Mod1, Name1, Args1}, {Mod2, Name2, Args2});
+can_combine_opaque_names(_, _, _, _) -> false.
+
+%% Combining two lists this way can be very time consuming...
+%% Note: two parameterized opaque types are not the same if their
+%% actual parameters differ
+inf_opaque(Set1, Set2, Opaques) ->
+  List1 = inf_look_up(Set1, Opaques),
+  List2 = inf_look_up(Set2, Opaques),
+  List0 = [combine(Inf, T1, T2) ||
+            {Is1, ModNameArgs1, T1} <- List1,
+            {Is2, ModNameArgs2, T2} <- List2,
+            not t_is_none(Inf = inf_opaque_types(Is1, ModNameArgs1, T1,
+                                                 Is2, ModNameArgs2, T2,
+                                                 Opaques))],
+  List = lists:sort(lists:append(List0)),
+  sup_opaque(List).
+
+%% Optimization: do just one lookup.
+inf_look_up(Set, Opaques) ->
+  [{Opaques =:= 'universe' orelse inf_is_opaque_type2(T, Opaques),
+    {M, N, Args}, T} ||
+    #opaque{mod = M, name = N, args = Args} = T <- set_to_list(Set)].
+
+inf_is_opaque_type2(T, {match, Opaques}) ->
+  is_opaque_type2(T, Opaques);
+inf_is_opaque_type2(T, Opaques) ->
+  is_opaque_type2(T, Opaques).
+
+inf_opaque_types(IsOpaque1, ModNameArgs1, T1,
+                 IsOpaque2, ModNameArgs2, T2, Opaques) ->
+  #opaque{struct = S1}=T1,
+  #opaque{struct = S2}=T2,
+  case
+    Opaques =:= 'universe' orelse
+    is_compat_opaque_names(ModNameArgs1, ModNameArgs2)
+  of
+    true -> t_inf(S1, S2, Opaques);
+    false ->
+      case {IsOpaque1, IsOpaque2} of
+        {true, true}  -> t_inf(S1, S2, Opaques);
+        {true, false} -> t_inf(S1, ?opaque(set_singleton(T2)), Opaques);
+        {false, true} -> t_inf(?opaque(set_singleton(T1)), S2, Opaques);
+        {false, false} when element(1, Opaques) =:= match ->
+          throw({pos, [1, 2]});
+        {false, false} -> t_none()
+      end
+  end.
+
+is_compat_opaque_names(ModNameArgs, ModNameArgs) -> true;
+is_compat_opaque_names({Mod,Name,Args1}, {Mod,Name,Args2}) ->
+  is_compat_args(Args1, Args2);
+is_compat_opaque_names(_, _) -> false.
+
+is_compat_args([A1|Args1], [A2|Args2]) ->
+  is_compat_arg(A1, A2) andalso is_compat_args(Args1, Args2);
+is_compat_args([], []) -> true;
+is_compat_args(_, _) -> false.
+
+is_compat_arg(A1, A2) ->
+  is_specialization(A1, A2) orelse is_specialization(A2, A1).
+
+-spec is_specialization(erl_type(), erl_type()) -> boolean().
+
+%% Returns true if the first argument is a specialization of the
+%% second argument in the sense that every type is a specialization of
+%% any(). For example, {_,_} is a specialization of any(), but not of
+%% tuple(). Does not handle variables, but any() and unions (sort of).
+
+is_specialization(T, T) -> true;
+is_specialization(_, ?any) -> true;
+is_specialization(?any, _) -> false;
+is_specialization(?function(Domain1, Range1), ?function(Domain2, Range2)) ->
+  (is_specialization(Domain1, Domain2) andalso
+   is_specialization(Range1, Range2));
+is_specialization(?list(Contents1, Termination1, Size1),
+                  ?list(Contents2, Termination2, Size2)) ->
+  (Size1 =:= Size2 andalso
+   is_specialization(Contents1, Contents2) andalso
+   is_specialization(Termination1, Termination2));
+is_specialization(?product(Types1), ?product(Types2)) ->
+  specialization_list(Types1, Types2);
+is_specialization(?tuple(?any, ?any, ?any), ?tuple(_, _, _)) -> false;
+is_specialization(?tuple(_, _, _), ?tuple(?any, ?any, ?any)) -> false;
+is_specialization(?tuple(Elements1, Arity, _), 
+                  ?tuple(Elements2, Arity, _)) when Arity =/= ?any ->
+  specialization_list(Elements1, Elements2);
+is_specialization(?tuple_set([{Arity, List}]), 
+                  ?tuple(Elements2, Arity, _)) when Arity =/= ?any ->
+  specialization_list(sup_tuple_elements(List), Elements2);
+is_specialization(?tuple(Elements1, Arity, _),
+                  ?tuple_set([{Arity, List}])) when Arity =/= ?any ->
+  specialization_list(Elements1, sup_tuple_elements(List));
+is_specialization(?tuple_set(List1), ?tuple_set(List2)) ->
+  try
+    specialization_list_list([sup_tuple_elements(T) || {_Arity, T} <- List1],
+                             [sup_tuple_elements(T) || {_Arity, T} <- List2])
+  catch _:_ -> false
+  end;
+is_specialization(?union(List1)=T1, ?union(List2)=T2) ->
+  case specialization_union2(T1, T2) of
+    {yes, Type1, Type2} -> is_specialization(Type1, Type2);
+    no -> specialization_list(List1, List2)
+  end;
+is_specialization(?union(List), T2) ->
+  case unify_union(List) of
+      {yes, Type} -> is_specialization(Type, T2);
+      no -> false
+  end;
+is_specialization(T1, ?union(List)) ->
+  case unify_union(List) of
+      {yes, Type} -> is_specialization(T1, Type);
+      no -> false
+  end;
+is_specialization(?opaque(_) = T1, T2) ->
+  is_specialization(t_opaque_structure(T1), T2);
+is_specialization(T1, ?opaque(_) = T2) ->
+  is_specialization(T1, t_opaque_structure(T2));
+is_specialization(?var(_), _) -> exit(error);
+is_specialization(_, ?var(_)) -> exit(error);
+is_specialization(?none, _) -> false;
+is_specialization(_, ?none) -> false;
+is_specialization(?unit, _) -> false;
+is_specialization(_, ?unit) -> false;
+is_specialization(#c{}, #c{}) -> false.
+
+specialization_list_list(LL1, LL2) ->
+  length(LL1) =:= length(LL2) andalso specialization_list_list1(LL1, LL2).
+
+specialization_list_list1([], []) -> true;
+specialization_list_list1([L1|LL1], [L2|LL2]) ->
+  specialization_list(L1, L2) andalso specialization_list_list1(LL1, LL2).
+
+specialization_list(L1, L2) ->
+  length(L1) =:= length(L2) andalso specialization_list1(L1, L2).
+
+specialization_list1([], []) -> true;
+specialization_list1([T1|L1], [T2|L2]) ->
+  is_specialization(T1, T2) andalso specialization_list1(L1, L2).
+
+specialization_union2(?union(List1)=T1, ?union(List2)=T2) ->
+  case {unify_union(List1), unify_union(List2)} of
+    {{yes, Type1}, {yes, Type2}} -> {yes, Type1, Type2};
+    {{yes, Type1}, no} -> {yes, Type1, T2};
+    {no, {yes, Type2}} -> {yes, T1, Type2};
+    {no, no} -> no
+  end.
+
+-spec t_inf_lists([erl_type()], [erl_type()]) -> [erl_type()].
+
+t_inf_lists(L1, L2) ->
+  t_inf_lists(L1, L2, 'universe').
+
+-spec t_inf_lists([erl_type()], [erl_type()], t_inf_opaques()) -> [erl_type()].
+
+t_inf_lists(L1, L2, Opaques) ->
+  t_inf_lists(L1, L2, [], Opaques).
+
+-spec t_inf_lists([erl_type()], [erl_type()], [erl_type()], [erl_type()]) -> [erl_type()].
+
+t_inf_lists([T1|Left1], [T2|Left2], Acc, Opaques) ->
+  t_inf_lists(Left1, Left2, [t_inf(T1, T2, Opaques)|Acc], Opaques);
+t_inf_lists([], [], Acc, _Opaques) ->
+  lists:reverse(Acc).
+
+%% Infimum of lists with strictness.
+%% If any element is the ?none type, the value 'bottom' is returned.
+
+-spec t_inf_lists_strict([erl_type()], [erl_type()], [erl_type()]) -> 'bottom' | [erl_type()].
+
+t_inf_lists_strict(L1, L2, Opaques) ->
+  t_inf_lists_strict(L1, L2, [], Opaques).
+
+-spec t_inf_lists_strict([erl_type()], [erl_type()], [erl_type()], [erl_type()]) -> 'bottom' | [erl_type()].
+
+t_inf_lists_strict([T1|Left1], [T2|Left2], Acc, Opaques) ->
+  case t_inf(T1, T2, Opaques) of
+    ?none -> bottom;
+    T -> t_inf_lists_strict(Left1, Left2, [T|Acc], Opaques)
+  end;
+t_inf_lists_strict([], [], Acc, _Opaques) ->
+  lists:reverse(Acc).
+
+inf_tuple_sets(L1, L2, Opaques) ->
+  case inf_tuple_sets(L1, L2, [], Opaques) of
+    [] -> ?none;
+    [{_Arity, [?tuple(_, _, _) = OneTuple]}] -> OneTuple;
+    List -> ?tuple_set(List)
+  end.
+
+inf_tuple_sets([{Arity, Tuples1}|Ts1], [{Arity, Tuples2}|Ts2], Acc, Opaques) ->
+  case inf_tuples_in_sets(Tuples1, Tuples2, Opaques) of
+    [] -> inf_tuple_sets(Ts1, Ts2, Acc, Opaques);
+    [?tuple_set([{Arity, NewTuples}])] ->
+      inf_tuple_sets(Ts1, Ts2, [{Arity, NewTuples}|Acc], Opaques);
+    NewTuples -> inf_tuple_sets(Ts1, Ts2, [{Arity, NewTuples}|Acc], Opaques)
+  end;
+inf_tuple_sets([{Arity1, _}|Ts1] = L1, [{Arity2, _}|Ts2] = L2, Acc, Opaques) ->
+  if Arity1 < Arity2 -> inf_tuple_sets(Ts1, L2, Acc, Opaques);
+     Arity1 > Arity2 -> inf_tuple_sets(L1, Ts2, Acc, Opaques)
+  end;
+inf_tuple_sets([], _, Acc, _Opaques) -> lists:reverse(Acc);
+inf_tuple_sets(_, [], Acc, _Opaques) -> lists:reverse(Acc).
+
+inf_tuples_in_sets([?tuple(Elements1, _, ?any)], L2, Opaques) ->
+  NewList = [t_inf_lists_strict(Elements1, Elements2, Opaques)
+	     || ?tuple(Elements2, _, _) <- L2],
+  [t_tuple(Es) || Es <- NewList, Es =/= bottom];
+inf_tuples_in_sets(L1, [?tuple(Elements2, _, ?any)], Opaques) ->
+  NewList = [t_inf_lists_strict(Elements1, Elements2, Opaques)
+	     || ?tuple(Elements1, _, _) <- L1],
+  [t_tuple(Es) || Es <- NewList, Es =/= bottom];
+inf_tuples_in_sets(L1, L2, Opaques) ->
+  inf_tuples_in_sets2(L1, L2, [], Opaques).
+
+inf_tuples_in_sets2([?tuple(Elements1, Arity, Tag)|Ts1],
+                    [?tuple(Elements2, Arity, Tag)|Ts2], Acc, Opaques) ->
+  case t_inf_lists_strict(Elements1, Elements2, Opaques) of
+    bottom -> inf_tuples_in_sets2(Ts1, Ts2, Acc, Opaques);
+    NewElements ->
+      inf_tuples_in_sets2(Ts1, Ts2, [?tuple(NewElements, Arity, Tag)|Acc],
+                          Opaques)
+  end;
+inf_tuples_in_sets2([?tuple(_, _, Tag1)|Ts1] = L1,
+                    [?tuple(_, _, Tag2)|Ts2] = L2, Acc, Opaques) ->
+  if Tag1 < Tag2 -> inf_tuples_in_sets2(Ts1, L2, Acc, Opaques);
+     Tag1 > Tag2 -> inf_tuples_in_sets2(L1, Ts2, Acc, Opaques)
+  end;
+inf_tuples_in_sets2([], _, Acc, _Opaques) -> lists:reverse(Acc);
+inf_tuples_in_sets2(_, [], Acc, _Opaques) -> lists:reverse(Acc).
+
+inf_union(U1, U2, Opaques) ->
+  OpaqueFun =
+    fun(Union1, Union2, InfFun) ->
+	[_,_,_,_,_,_,_,_,Opaque,_] = Union1,
+        [A,B,F,I,L,N,T,M,_,Map] = Union2,
+        List = [A,B,F,I,L,N,T,M,Map],
+        inf_union_collect(List, Opaque, InfFun, [], [])
+    end,
+  {O1, ThrowList1} =
+    OpaqueFun(U1, U2, fun(E, Opaque) -> t_inf(Opaque, E, Opaques) end),
+  {O2, ThrowList2}
+    = OpaqueFun(U2, U1, fun(E, Opaque) -> t_inf(E, Opaque, Opaques) end),
+  {Union, ThrowList3} = inf_union(U1, U2, 0, [], [], Opaques),
+  ThrowList = lists:merge3(ThrowList1, ThrowList2, ThrowList3),
+  case t_sup([O1, O2, Union]) of
+    ?none when ThrowList =/= [] -> throw({pos, lists:usort(ThrowList)});
+    Sup -> Sup
+  end.
+
+inf_union_collect([], _Opaque, _InfFun, InfList, ThrowList) ->
+  {t_sup(InfList), lists:usort(ThrowList)};
+inf_union_collect([?none|L], Opaque, InfFun, InfList, ThrowList) ->
+  inf_union_collect(L, Opaque, InfFun, [?none|InfList], ThrowList);
+inf_union_collect([E|L], Opaque, InfFun, InfList, ThrowList) ->
+  try InfFun(E, Opaque)of
+    Inf ->
+      inf_union_collect(L, Opaque, InfFun, [Inf|InfList], ThrowList)
+  catch throw:{pos, Ns} ->
+      inf_union_collect(L, Opaque, InfFun, InfList, Ns ++ ThrowList)
+  end.
+
+inf_union([?none|Left1], [?none|Left2], N, Acc, ThrowList, Opaques) ->
+  inf_union(Left1, Left2, N, [?none|Acc], ThrowList, Opaques);
+inf_union([T1|Left1], [T2|Left2], N, Acc, ThrowList, Opaques) ->
+  try t_inf(T1, T2, Opaques) of
+    ?none -> inf_union(Left1, Left2, N, [?none|Acc], ThrowList, Opaques);
+    T     -> inf_union(Left1, Left2, N+1, [T|Acc], ThrowList, Opaques)
+  catch throw:{pos, Ns} ->
+      inf_union(Left1, Left2, N, [?none|Acc], Ns ++ ThrowList, Opaques)
+  end;
+inf_union([], [], N, Acc, ThrowList, _Opaques) ->
+  if N =:= 0 -> {?none, ThrowList};
+     N =:= 1 ->
+      [Type] = [T || T <- Acc, T =/= ?none],
+      {Type, ThrowList};
+     N >= 2  -> {?union(lists:reverse(Acc)), ThrowList}
+  end.
+
+inf_bitstr(U1, B1, U2, B2) ->
+  GCD = gcd(U1, U2),
+  case (B2-B1) rem GCD of
+    0 ->
+      U = (U1*U2) div GCD,
+      B = findfirst(0, 0, U1, B1, U2, B2),
+      t_bitstr(U, B);
+    _ ->
+      ?none
+  end.
+
+findfirst(N1, N2, U1, B1, U2, B2) ->
+  Val1 = U1*N1+B1,
+  Val2 = U2*N2+B2,
+  if Val1 =:= Val2 ->
+      Val1;
+     Val1 > Val2 ->
+      findfirst(N1, N2+1, U1, B1, U2, B2);
+     Val1 < Val2 ->
+      findfirst(N1+1, N2, U1, B1, U2, B2)
+  end.
+
+%%-----------------------------------------------------------------------------
+%% Substitution of variables
+%%
+
+-type subst_table() :: #{any() => erl_type()}.
+
+-spec t_subst(erl_type(), subst_table()) -> erl_type().
+
+t_subst(T, Map) ->
+  case t_has_var(T) of
+    true -> t_subst_aux(T, Map);
+    false -> T
+  end.
+
+-spec subst_all_vars_to_any(erl_type()) -> erl_type().
+
+subst_all_vars_to_any(T) ->
+  t_subst(T, #{}).
+
+t_subst_aux(?var(Id), Map) ->
+  case maps:find(Id, Map) of
+    error -> ?any;
+    {ok, Type} -> Type
+  end;
+t_subst_aux(?list(Contents, Termination, Size), Map) ->
+  case t_subst_aux(Contents, Map) of
+    ?none -> ?none;
+    NewContents ->
+      %% Be careful here to make the termination collapse if necessary.
+      case t_subst_aux(Termination, Map) of
+	?nil -> ?list(NewContents, ?nil, Size);
+	?any -> ?list(NewContents, ?any, Size);
+	Other ->
+	  ?list(NewContents2, NewTermination, _) = t_cons(NewContents, Other),
+	  ?list(NewContents2, NewTermination, Size)
+      end
+  end;
+t_subst_aux(?function(Domain, Range), Map) ->
+  ?function(t_subst_aux(Domain, Map), t_subst_aux(Range, Map));
+t_subst_aux(?product(Types), Map) ->
+  ?product([t_subst_aux(T, Map) || T <- Types]);
+t_subst_aux(?tuple(?any, ?any, ?any) = T, _Map) ->
+  T;
+t_subst_aux(?tuple(Elements, _Arity, _Tag), Map) ->
+  t_tuple([t_subst_aux(E, Map) || E <- Elements]);
+t_subst_aux(?tuple_set(_) = TS, Map) ->
+  t_sup([t_subst_aux(T, Map) || T <- t_tuple_subtypes(TS)]);
+t_subst_aux(?map(Pairs, DefK, DefV), Map) ->
+  t_map([{K, MNess, t_subst_aux(V, Map)} || {K, MNess, V} <- Pairs],
+	t_subst_aux(DefK, Map), t_subst_aux(DefV, Map));
+t_subst_aux(?opaque(Es), Map) ->
+  List = [Opaque#opaque{args = [t_subst_aux(Arg, Map) || Arg <- Args],
+                        struct = t_subst_aux(S, Map)} ||
+           Opaque = #opaque{args = Args, struct = S} <- set_to_list(Es)],
+  ?opaque(ordsets:from_list(List));
+t_subst_aux(?union(List), Map) ->
+  ?union([t_subst_aux(E, Map) || E <- List]);
+t_subst_aux(T, _Map) ->
+  T.
+
+%%-----------------------------------------------------------------------------
+%% Unification
+%%
+
+-type t_unify_ret() :: {erl_type(), [{_, erl_type()}]}.
+
+-spec t_unify(erl_type(), erl_type()) -> t_unify_ret().
+
+t_unify(T1, T2) ->
+  {T, VarMap} = t_unify(T1, T2, #{}),
+  {t_subst(T, VarMap), lists:keysort(1, maps:to_list(VarMap))}.
+
+t_unify(?var(Id) = T, ?var(Id), VarMap) ->
+  {T, VarMap};
+t_unify(?var(Id1) = T, ?var(Id2), VarMap) ->
+  case maps:find(Id1, VarMap) of
+    error ->
+      case maps:find(Id2, VarMap) of
+	error -> {T, VarMap#{Id2 => T}};
+	{ok, Type} -> t_unify(T, Type, VarMap)
+      end;
+    {ok, Type1} ->
+      case maps:find(Id2, VarMap) of
+	error -> {Type1, VarMap#{Id2 => T}};
+	{ok, Type2} -> t_unify(Type1, Type2, VarMap)
+      end
+  end;
+t_unify(?var(Id), Type, VarMap) ->
+  case maps:find(Id, VarMap) of
+    error -> {Type, VarMap#{Id => Type}};
+    {ok, VarType} -> t_unify(VarType, Type, VarMap)
+  end;
+t_unify(Type, ?var(Id), VarMap) ->
+  case maps:find(Id, VarMap) of
+    error -> {Type, VarMap#{Id => Type}};
+    {ok, VarType} -> t_unify(VarType, Type, VarMap)
+  end;
+t_unify(?function(Domain1, Range1), ?function(Domain2, Range2), VarMap) ->
+  {Domain, VarMap1} = t_unify(Domain1, Domain2, VarMap),
+  {Range, VarMap2} = t_unify(Range1, Range2, VarMap1),
+  {?function(Domain, Range), VarMap2};
+t_unify(?list(Contents1, Termination1, Size), 
+	?list(Contents2, Termination2, Size), VarMap) ->
+  {Contents, VarMap1} = t_unify(Contents1, Contents2, VarMap),
+  {Termination, VarMap2} = t_unify(Termination1, Termination2, VarMap1),
+  {?list(Contents, Termination, Size), VarMap2};
+t_unify(?product(Types1), ?product(Types2), VarMap) ->
+  {Types, VarMap1} = unify_lists(Types1, Types2, VarMap),
+  {?product(Types), VarMap1};
+t_unify(?tuple(?any, ?any, ?any) = T, ?tuple(?any, ?any, ?any), VarMap) ->
+  {T, VarMap};
+t_unify(?tuple(Elements1, Arity, _), 
+	?tuple(Elements2, Arity, _), VarMap) when Arity =/= ?any ->
+  {NewElements, VarMap1} = unify_lists(Elements1, Elements2, VarMap),
+  {t_tuple(NewElements), VarMap1};
+t_unify(?tuple_set([{Arity, _}]) = T1, 
+	?tuple(_, Arity, _) = T2, VarMap) when Arity =/= ?any ->
+  unify_tuple_set_and_tuple1(T1, T2, VarMap);
+t_unify(?tuple(_, Arity, _) = T1,
+	?tuple_set([{Arity, _}]) = T2, VarMap) when Arity =/= ?any ->
+  unify_tuple_set_and_tuple2(T1, T2, VarMap);
+t_unify(?tuple_set(List1) = T1, ?tuple_set(List2) = T2, VarMap) ->
+  try
+    unify_lists(lists:append([T || {_Arity, T} <- List1]),
+                lists:append([T || {_Arity, T} <- List2]), VarMap)
+  of
+    {Tuples, NewVarMap} -> {t_sup(Tuples), NewVarMap}
+  catch _:_ -> throw({mismatch, T1, T2})
+  end;
+t_unify(?map(_, ADefK, ADefV) = A, ?map(_, BDefK, BDefV) = B, VarMap0) ->
+  {DefK, VarMap1} = t_unify(ADefK, BDefK, VarMap0),
+  {DefV, VarMap2} = t_unify(ADefV, BDefV, VarMap1),
+  {Pairs, VarMap} =
+    map_pairwise_merge_foldr(
+      fun(K, MNess, V1, MNess, V2, {Pairs0, VarMap3}) ->
+	  %% We know that the keys unify and do not contain variables, or they
+	  %% would not be singletons
+	  %% TODO: Should V=?none (known missing keys) be handled special?
+	  {V, VarMap4} = t_unify(V1, V2, VarMap3),
+	  {[{K,MNess,V}|Pairs0], VarMap4};
+	 (K, _, V1, _, V2, {Pairs0, VarMap3}) ->
+	  %% One mandatory and one optional; what should be done in this case?
+	  {V, VarMap4} = t_unify(V1, V2, VarMap3),
+	  {[{K,?mand,V}|Pairs0], VarMap4}
+      end, {[], VarMap2}, A, B),
+  {t_map(Pairs, DefK, DefV), VarMap};
+t_unify(?opaque(_) = T1, ?opaque(_) = T2, VarMap) ->
+  t_unify(t_opaque_structure(T1), t_opaque_structure(T2), VarMap);
+t_unify(T1, ?opaque(_) = T2, VarMap) ->
+  t_unify(T1, t_opaque_structure(T2), VarMap);
+t_unify(?opaque(_) = T1, T2, VarMap) ->
+  t_unify(t_opaque_structure(T1), T2, VarMap);
+t_unify(T, T, VarMap) ->
+  {T, VarMap};
+t_unify(?union(_)=T1, ?union(_)=T2, VarMap) ->
+  {Type1, Type2} = unify_union2(T1, T2),
+  t_unify(Type1, Type2, VarMap);
+t_unify(?union(_)=T1, T2, VarMap) ->
+  t_unify(unify_union1(T1, T1, T2), T2, VarMap);
+t_unify(T1, ?union(_)=T2, VarMap) ->
+  t_unify(T1, unify_union1(T2, T1, T2), VarMap);
+t_unify(T1, T2, _) ->
+  throw({mismatch, T1, T2}).
+
+unify_union2(?union(List1)=T1, ?union(List2)=T2) ->
+  case {unify_union(List1), unify_union(List2)} of
+    {{yes, Type1}, {yes, Type2}} -> {Type1, Type2};
+    {{yes, Type1}, no} -> {Type1, T2};
+    {no, {yes, Type2}} -> {T1, Type2};
+    {no, no} -> throw({mismatch, T1, T2})
+  end.
+
+unify_union1(?union(List), T1, T2) ->
+  case unify_union(List) of
+    {yes, Type} -> Type;
+    no -> throw({mismatch, T1, T2})
+  end.
+
+unify_union(List) ->
+  [A,B,F,I,L,N,T,M,O,Map] = List,
+  if O =:= ?none -> no;
+    true ->
+      S = t_opaque_structure(O),
+      {yes, t_sup([A,B,F,I,L,N,T,M,S,Map])}
+  end.
+
+-spec is_opaque_type(erl_type(), [erl_type()]) -> boolean().
+
+%% An opaque type is a union of types. Returns true iff any of the type
+%% names (Module and Name) of the first argument (the opaque type to
+%% check) occurs in any of the opaque types of the second argument.
+is_opaque_type(?opaque(Elements), Opaques) ->
+  lists:any(fun(Opaque) -> is_opaque_type2(Opaque, Opaques) end, Elements).
+
+is_opaque_type2(#opaque{mod = Mod1, name = Name1, args = Args1}, Opaques) ->
+  F1 = fun(?opaque(Es)) ->
+           F2 = fun(#opaque{mod = Mod, name = Name, args = Args}) ->
+                    is_type_name(Mod1, Name1, Args1, Mod, Name, Args)
+                end,
+           lists:any(F2, Es)
+       end,
+  lists:any(F1, Opaques).
+
+is_type_name(Mod, Name, Args1, Mod, Name, Args2) ->
+  length(Args1) =:= length(Args2);
+is_type_name(_Mod1, _Name1, _Args1, _Mod2, _Name2, _Args2) ->
+  false.
+
+%% Two functions since t_unify is not symmetric.
+unify_tuple_set_and_tuple1(?tuple_set([{Arity, List}]),
+                           ?tuple(Elements2, Arity, _), VarMap) ->
+  %% Can only work if the single tuple has variables at correct places.
+  %% Collapse the tuple set.
+  {NewElements, VarMap1} =
+    unify_lists(sup_tuple_elements(List), Elements2, VarMap),
+  {t_tuple(NewElements), VarMap1}.
+
+unify_tuple_set_and_tuple2(?tuple(Elements2, Arity, _),
+                           ?tuple_set([{Arity, List}]), VarMap) ->
+  %% Can only work if the single tuple has variables at correct places.
+  %% Collapse the tuple set.
+  {NewElements, VarMap1} =
+    unify_lists(Elements2, sup_tuple_elements(List), VarMap),
+  {t_tuple(NewElements), VarMap1}.
+
+unify_lists(L1, L2, VarMap) ->
+  unify_lists(L1, L2, VarMap, []).
+
+unify_lists([T1|Left1], [T2|Left2], VarMap, Acc) ->
+  {NewT, NewVarMap} = t_unify(T1, T2, VarMap),
+  unify_lists(Left1, Left2, NewVarMap, [NewT|Acc]);
+unify_lists([], [], VarMap, Acc) ->
+  {lists:reverse(Acc), VarMap}.
+
+%%t_assign_variables_to_subtype(T1, T2) ->
+%%  try 
+%%    Dict = assign_vars(T1, T2, dict:new()),
+%%    {ok, dict:map(fun(_Param, List) -> t_sup(List) end, Dict)}
+%%  catch
+%%    throw:error -> error
+%%  end.
+
+%%assign_vars(_, ?var(_), _Dict) ->
+%%  erlang:error("Variable in right hand side of assignment");
+%%assign_vars(?any, _, Dict) ->
+%%  Dict;
+%%assign_vars(?var(_) = Var, Type, Dict) ->
+%%  store_var(Var, Type, Dict);
+%%assign_vars(?function(Domain1, Range1), ?function(Domain2, Range2), Dict) ->
+%%  DomainList =
+%%    case Domain2 of
+%%      ?any -> [];
+%%      ?product(List) -> List
+%%    end,
+%%  case any_none([Range2|DomainList]) of
+%%    true -> throw(error);
+%%    false ->
+%%      Dict1 = assign_vars(Domain1, Domain2, Dict),
+%%      assign_vars(Range1, Range2, Dict1)
+%%  end;
+%%assign_vars(?list(_Contents, _Termination, ?any), ?nil, Dict) ->
+%%  Dict;
+%%assign_vars(?list(Contents1, Termination1, Size1), 
+%%	    ?list(Contents2, Termination2, Size2), Dict) ->
+%%  Dict1 = assign_vars(Contents1, Contents2, Dict),
+%%  Dict2 = assign_vars(Termination1, Termination2, Dict1),
+%%  case {Size1, Size2} of
+%%    {S, S} -> Dict2;
+%%    {?any, ?nonempty_qual} -> Dict2;
+%%    {_, _} -> throw(error)
+%%  end;
+%%assign_vars(?product(Types1), ?product(Types2), Dict) -> 
+%%  case length(Types1) =:= length(Types2) of
+%%    true -> assign_vars_lists(Types1, Types2, Dict);
+%%    false -> throw(error)
+%%  end;
+%%assign_vars(?tuple(?any, ?any, ?any), ?tuple(?any, ?any, ?any), Dict) ->
+%%  Dict;
+%%assign_vars(?tuple(?any, ?any, ?any), ?tuple(_, _, _), Dict) ->
+%%  Dict;
+%%assign_vars(?tuple(Elements1, Arity, _), 
+%%	    ?tuple(Elements2, Arity, _), Dict) when Arity =/= ?any ->
+%%  assign_vars_lists(Elements1, Elements2, Dict);
+%%assign_vars(?tuple_set(_) = T, ?tuple_set(List2), Dict) ->
+%%  %% All Rhs tuples must already be subtypes of Lhs, so we can take
+%%  %% each one separatly.
+%%  assign_vars_lists([T || _ <- List2], List2, Dict);
+%%assign_vars(?tuple(?any, ?any, ?any), ?tuple_set(_), Dict) ->
+%%  Dict;
+%%assign_vars(?tuple(_, Arity, _) = T1, ?tuple_set(List), Dict) ->
+%%  case reduce_tuple_tags(List) of
+%%    [Tuple = ?tuple(_, Arity, _)] -> assign_vars(T1, Tuple, Dict);
+%%    _ -> throw(error)
+%%  end;
+%%assign_vars(?tuple_set(List), ?tuple(_, Arity, Tag) = T2, Dict) ->
+%%  case [T || ?tuple(_, Arity1, Tag1) = T <- List, 
+%%	     Arity1 =:= Arity, Tag1 =:= Tag] of
+%%    [] -> throw(error);
+%%    [T1] -> assign_vars(T1, T2, Dict)
+%%  end;
+%%assign_vars(?union(U1), T2, Dict) ->
+%%  ?union(U2) = force_union(T2),
+%%  assign_vars_lists(U1, U2, Dict);
+%%assign_vars(T, T, Dict) ->
+%%  Dict;
+%%assign_vars(T1, T2, Dict) ->
+%%  case t_is_subtype(T2, T1) of
+%%    false -> throw(error);
+%%    true -> Dict
+%%  end.
+
+%%assign_vars_lists([T1|Left1], [T2|Left2], Dict) ->
+%%  assign_vars_lists(Left1, Left2, assign_vars(T1, T2, Dict));
+%%assign_vars_lists([], [], Dict) ->
+%%  Dict.
+
+%%store_var(?var(Id), Type, Dict) ->
+%%  case dict:find(Id, Dict) of
+%%    error -> dict:store(Id, [Type], Dict);
+%%    {ok, _VarType0} -> dict:update(Id, fun(X) -> [Type|X] end, Dict)
+%%  end.
+
+%%-----------------------------------------------------------------------------
+%% Subtraction. 
+%%
+%% Note that the subtraction is an approximation since we do not have
+%% negative types. Also, tuples and products should be handled using
+%% the cartesian product of the elements, but this is not feasible to
+%% do.
+%% 
+%% Example: {a|b,c|d}\{a,d} = {a,c}|{a,d}|{b,c}|{b,d} \ {a,d} = 
+%%                          = {a,c}|{b,c}|{b,d} = {a|b,c|d}
+%%
+%% Instead, we can subtract if all elements but one becomes none after
+%% subtracting element-wise.
+%% 
+%% Example: {a|b,c|d}\{a|b,d} = {a,c}|{a,d}|{b,c}|{b,d} \ {a,d}|{b,d} = 
+%%                            = {a,c}|{b,c} = {a|b,c}
+
+-spec t_subtract_list(erl_type(), [erl_type()]) -> erl_type().
+
+t_subtract_list(T1, [T2|Left]) ->
+  t_subtract_list(t_subtract(T1, T2), Left);
+t_subtract_list(T, []) ->
+  T.
+
+-spec t_subtract(erl_type(), erl_type()) -> erl_type().
+
+t_subtract(_, ?any) -> ?none;
+t_subtract(T, ?var(_)) -> T;
+t_subtract(?any, _) -> ?any;
+t_subtract(?var(_) = T, _) -> T;
+t_subtract(T, ?unit) -> T;
+t_subtract(?unit, _) -> ?unit;
+t_subtract(?none, _) -> ?none;
+t_subtract(T, ?none) -> T;
+t_subtract(?atom(Set1), ?atom(Set2)) ->
+  case set_subtract(Set1, Set2) of
+    ?none -> ?none;
+    Set -> ?atom(Set)
+  end;
+t_subtract(?bitstr(U1, B1), ?bitstr(U2, B2)) ->
+  subtract_bin(t_bitstr(U1, B1), t_inf(t_bitstr(U1, B1), t_bitstr(U2, B2)));
+t_subtract(?function(_, _) = T1, ?function(_, _) = T2) ->
+  case t_is_subtype(T1, T2) of
+    true -> ?none;
+    false -> T1
+  end;
+t_subtract(?identifier(Set1), ?identifier(Set2)) ->
+  case set_subtract(Set1, Set2) of
+    ?none -> ?none;
+    Set -> ?identifier(Set)
+  end;
+t_subtract(?opaque(_)=T1, ?opaque(_)=T2) ->
+  opaque_subtract(T1, t_opaque_structure(T2));
+t_subtract(?opaque(_)=T1, T2) ->
+  opaque_subtract(T1, T2);
+t_subtract(T1, ?opaque(_)=T2) ->
+  t_subtract(T1, t_opaque_structure(T2));
+t_subtract(?matchstate(Pres1, Slots1), ?matchstate(Pres2, _Slots2)) ->
+  Pres = t_subtract(Pres1, Pres2),
+  case t_is_none(Pres) of
+    true -> ?none;
+    false -> ?matchstate(Pres, Slots1)
+  end;
+t_subtract(?matchstate(Present, Slots), _) ->
+  ?matchstate(Present, Slots);
+t_subtract(?nil, ?nil) ->
+  ?none;
+t_subtract(?nil, ?nonempty_list(_, _)) ->
+  ?nil;
+t_subtract(?nil, ?list(_, _, _)) ->
+  ?none;
+t_subtract(?list(Contents, Termination, _Size) = T, ?nil) ->
+  case Termination =:= ?nil of
+    true -> ?nonempty_list(Contents, Termination);
+    false -> T
+  end;
+t_subtract(?list(Contents1, Termination1, Size1) = T, 
+	   ?list(Contents2, Termination2, Size2)) ->
+  case t_is_subtype(Contents1, Contents2) of
+    true ->
+      case t_is_subtype(Termination1, Termination2) of
+	true ->
+	  case {Size1, Size2} of
+	    {?nonempty_qual, ?unknown_qual} -> ?none;
+	    {?unknown_qual, ?nonempty_qual} -> ?nil;
+	    {S, S} -> ?none
+	  end;
+	false ->
+	  %% If the termination is not covered by the subtracted type
+	  %% we cannot really say anything about the result.
+	  T
+      end;
+    false ->
+      %% All contents must be covered if there is going to be any
+      %% change to the list.
+      T
+  end;
+t_subtract(?float, ?float) -> ?none;
+t_subtract(?number(_, _) = T1, ?float) -> t_inf(T1, t_integer());
+t_subtract(?float, ?number(_Set, Tag)) ->
+  case Tag of
+    ?unknown_qual -> ?none;
+    _ -> ?float
+  end;
+t_subtract(?number(_, _), ?number(?any, ?unknown_qual)) -> ?none;
+t_subtract(?number(_, _) = T1, ?integer(?any)) -> t_inf(?float, T1);
+t_subtract(?int_set(Set1), ?int_set(Set2)) ->
+  case set_subtract(Set1, Set2) of
+    ?none -> ?none;
+    Set -> ?int_set(Set)
+  end;
+t_subtract(?int_range(From1, To1) = T1, ?int_range(_, _) = T2) ->
+  case t_inf(T1, T2) of
+    ?none -> T1;
+    ?int_range(From1, To1) -> ?none;
+    ?int_range(neg_inf, To) -> t_from_range(To + 1, To1);
+    ?int_range(From, pos_inf) -> t_from_range(From1, From - 1);
+    ?int_range(From, To) -> t_sup(t_from_range(From1, From - 1), 
+				  t_from_range(To + 1, To))
+  end;
+t_subtract(?int_range(From, To) = T1, ?int_set(Set)) ->
+  NewFrom = case set_is_element(From, Set) of
+	      true -> From + 1;
+	      false -> From
+	    end,
+  NewTo = case set_is_element(To, Set) of
+	    true -> To - 1;
+	    false -> To
+	  end,
+  if (NewFrom =:= From) and (NewTo =:= To) -> T1;
+     true -> t_from_range(NewFrom, NewTo)
+  end;
+t_subtract(?int_set(Set), ?int_range(From, To)) ->
+  case set_filter(fun(X) -> not ((X =< From) orelse (X >= To)) end, Set) of
+    ?none -> ?none;
+    NewSet -> ?int_set(NewSet)
+  end;
+t_subtract(?integer(?any) = T1, ?integer(_)) -> T1;
+t_subtract(?number(_, _) = T1, ?number(_, _)) -> T1;
+t_subtract(?tuple(_, _, _), ?tuple(?any, ?any, ?any)) -> ?none;
+t_subtract(?tuple_set(_), ?tuple(?any, ?any, ?any)) -> ?none;
+t_subtract(?tuple(?any, ?any, ?any) = T1, ?tuple_set(_)) -> T1;
+t_subtract(?tuple(Elements1, Arity1, _Tag1) = T1,
+	   ?tuple(Elements2, Arity2, _Tag2)) ->
+  if Arity1 =/= Arity2 -> T1;
+     Arity1 =:= Arity2 ->
+      NewElements = t_subtract_lists(Elements1, Elements2),
+      case [E || E <- NewElements, E =/= ?none] of
+	[] -> ?none;
+	[_] -> t_tuple(replace_nontrivial_element(Elements1, NewElements));
+	_ -> T1
+      end
+  end;
+t_subtract(?tuple_set(List1) = T1, ?tuple(_, Arity, _) = T2) ->
+  case orddict:find(Arity, List1) of
+    error -> T1;
+    {ok, List2} ->
+      TuplesLeft0 = [Tuple || {_Arity, Tuple} <- orddict:erase(Arity, List1)],
+      TuplesLeft1 = lists:append(TuplesLeft0),
+      t_sup([t_subtract(L, T2) || L <- List2] ++ TuplesLeft1)
+  end;
+t_subtract(?tuple(_, Arity, _) = T1, ?tuple_set(List1)) ->
+  case orddict:find(Arity, List1) of
+    error -> T1;
+    {ok, List2} -> t_inf([t_subtract(T1, L) || L <- List2])
+  end;
+t_subtract(?tuple_set(_) = T1, ?tuple_set(_) = T2) ->
+  t_sup([t_subtract(T, T2) || T <- t_tuple_subtypes(T1)]);
+t_subtract(?product(Elements1) = T1, ?product(Elements2)) ->
+  Arity1 = length(Elements1),
+  Arity2 = length(Elements2),
+  if Arity1 =/= Arity2 -> T1;
+     Arity1 =:= Arity2 ->
+      NewElements = t_subtract_lists(Elements1, Elements2),
+      case [E || E <- NewElements, E =/= ?none] of
+	[] -> ?none;
+	[_] -> t_product(replace_nontrivial_element(Elements1, NewElements));
+	_ -> T1
+      end
+  end;
+t_subtract(?map(APairs, ADefK, ADefV) = A, ?map(_, BDefK, BDefV) = B) ->
+  case t_is_subtype(ADefK, BDefK) andalso t_is_subtype(ADefV, BDefV) of
+    false -> A;
+    true ->
+      %% We fold over the maps to produce a list of constraints, where
+      %% constraints are additional key-value pairs to put in Pairs. Only one
+      %% constraint need to be applied to produce a type that excludes the
+      %% right-hand-side type, so if more than one constraint is produced, we
+      %% just return the left-hand-side argument.
+      %%
+      %% Each case of the fold may either conclude that
+      %%  * The arguments constrain A at least as much as B, i.e. that A so far
+      %%    is a subtype of B. In that case they return false
+      %%  * That for the particular arguments, A being a subtype of B does not
+      %%    hold, but the infinimum of A and B is nonempty, and by narrowing a
+      %%    pair in A, we can create a type that excludes some elements in the
+      %%    infinumum. In that case, they will return that pair.
+      %%  * That for the particular arguments, A being a subtype of B does not
+      %%    hold, and either the infinumum of A and B is empty, or it is not
+      %%    possible with the current representation to create a type that
+      %%    excludes elements from B without also excluding elements that are
+      %%    only in A. In that case, it will return the pair from A unchanged.
+      case
+	map_pairwise_merge(
+	  %% If V1 is a subtype of V2, the case that K does not exist in A
+	  %% remain.
+	  fun(K, ?opt, V1, ?mand, V2) -> {K, ?opt, t_subtract(V1, V2)};
+	     (K, _,    V1, _,     V2) ->
+	      %% If we subtract an optional key, that leaves a mandatory key
+	      case t_subtract(V1, V2) of
+		?none -> false;
+		Partial -> {K, ?mand, Partial}
+	      end
+	  end, A, B)
+      of
+	  %% We produce a list of keys that are constrained. As only one of
+	  %% these should apply at a time, we can't represent the difference if
+	  %% more than one constraint is produced. If we applied all of them,
+	  %% that would make an underapproximation, which we must not do.
+	  [] -> ?none; %% A is a subtype of B
+	  [E] -> t_map(mapdict_store(E, APairs), ADefK, ADefV);
+	  _ -> A
+      end
+  end;
+t_subtract(?product(P1), _) ->
+  ?product(P1);
+t_subtract(T, ?product(_)) ->
+  T;
+t_subtract(?union(U1), ?union(U2)) ->
+  subtract_union(U1, U2);
+t_subtract(T1, T2) ->
+  ?union(U1) = force_union(T1),
+  ?union(U2) = force_union(T2),
+  subtract_union(U1, U2).
+
+-spec opaque_subtract(erl_type(), erl_type()) -> erl_type().
+
+opaque_subtract(?opaque(Set1), T2) ->
+  List = [T1#opaque{struct = Sub} ||
+           #opaque{struct = S1}=T1 <- set_to_list(Set1),
+           not t_is_none(Sub = t_subtract(S1, T2))],
+  case List of
+    [] -> ?none;
+    _ -> ?opaque(ordsets:from_list(List))
+  end.
+
+-spec t_subtract_lists([erl_type()], [erl_type()]) -> [erl_type()].
+
+t_subtract_lists(L1, L2) ->
+  t_subtract_lists(L1, L2, []).
+
+-spec t_subtract_lists([erl_type()], [erl_type()], [erl_type()]) -> [erl_type()].
+
+t_subtract_lists([T1|Left1], [T2|Left2], Acc) ->
+  t_subtract_lists(Left1, Left2, [t_subtract(T1, T2)|Acc]);
+t_subtract_lists([], [], Acc) ->
+  lists:reverse(Acc).
+
+-spec subtract_union([erl_type(),...], [erl_type(),...]) -> erl_type().
+
+subtract_union(U1, U2) ->
+  [A1,B1,F1,I1,L1,N1,T1,M1,O1,Map1] = U1,
+  [A2,B2,F2,I2,L2,N2,T2,M2,O2,Map2] = U2,
+  List1 = [A1,B1,F1,I1,L1,N1,T1,M1,?none,Map1],
+  List2 = [A2,B2,F2,I2,L2,N2,T2,M2,?none,Map2],
+  Sub1 = subtract_union(List1, List2, 0, []),
+  O = if O1 =:= ?none -> O1;
+         true -> t_subtract(O1, ?union(U2))
+      end,
+  Sub2 = if O2 =:= ?none -> Sub1;
+            true -> t_subtract(Sub1, t_opaque_structure(O2))
+         end,
+  t_sup(O, Sub2).
+
+-spec subtract_union([erl_type()], [erl_type()], non_neg_integer(), [erl_type()]) -> erl_type().
+
+subtract_union([T1|Left1], [T2|Left2], N, Acc) ->
+  case t_subtract(T1, T2) of
+    ?none -> subtract_union(Left1, Left2, N, [?none|Acc]);
+    T ->     subtract_union(Left1, Left2, N+1, [T|Acc])
+  end;
+subtract_union([], [], 0, _Acc) ->
+  ?none;
+subtract_union([], [], 1, Acc) ->
+  [T] = [X || X <- Acc, X =/= ?none],
+  T;
+subtract_union([], [], N, Acc) when is_integer(N), N > 1 ->
+  ?union(lists:reverse(Acc)).
+
+replace_nontrivial_element(El1, El2) ->
+  replace_nontrivial_element(El1, El2, []).
+
+replace_nontrivial_element([T1|Left1], [?none|Left2], Acc) ->
+  replace_nontrivial_element(Left1, Left2, [T1|Acc]);
+replace_nontrivial_element([_|Left1], [T2|_], Acc) ->
+  lists:reverse(Acc) ++ [T2|Left1].
+
+subtract_bin(?bitstr(U1, B1), ?bitstr(U1, B1)) ->
+  ?none;
+subtract_bin(?bitstr(U1, B1), ?none) ->
+  t_bitstr(U1, B1);
+subtract_bin(?bitstr(U1, B1), ?bitstr(0, B1)) ->
+  t_bitstr(U1, B1+U1);
+subtract_bin(?bitstr(U1, B1), ?bitstr(U1, B2)) ->
+  if (B1+U1) =/= B2 -> t_bitstr(0, B1);
+     true -> t_bitstr(U1, B1)
+  end;
+subtract_bin(?bitstr(U1, B1), ?bitstr(U2, B2)) ->
+  if (2 * U1) =:= U2 ->
+      if B1 =:= B2 ->
+	  t_bitstr(U2, B1+U1);
+	 (B1 + U1) =:= B2 ->
+	  t_bitstr(U2, B1);
+	 true ->
+	  t_bitstr(U1, B1)
+      end;
+     true ->
+      t_bitstr(U1, B1)
+  end.
+
+%%-----------------------------------------------------------------------------
+%% Relations
+%%
+
+-spec t_is_equal(erl_type(), erl_type()) -> boolean().
+
+t_is_equal(T, T)  -> true;
+t_is_equal(_, _) -> false.
+
+-spec t_is_subtype(erl_type(), erl_type()) -> boolean().
+
+t_is_subtype(T1, T2) ->
+  Inf = t_inf(T1, T2),
+  subtype_is_equal(T1, Inf).
+
+%% The subtype relation has to behave correctly irrespective of opaque
+%% types.
+subtype_is_equal(T, T)   -> true;
+subtype_is_equal(T1, T2) ->
+  t_is_equal(case t_contains_opaque(T1) of
+               true  -> t_unopaque(T1);
+               false -> T1
+             end,
+             case t_contains_opaque(T2) of
+               true  -> t_unopaque(T2);
+               false -> T2
+             end).
+
+-spec t_is_instance(erl_type(), erl_type()) -> boolean().
+
+%% XXX. To be removed.
+t_is_instance(ConcreteType, Type) ->
+  t_is_subtype(ConcreteType, t_unopaque(Type)).
+
+-spec t_do_overlap(erl_type(), erl_type()) -> boolean().
+
+t_do_overlap(TypeA, TypeB) ->
+  not (t_is_none_or_unit(t_inf(TypeA, TypeB))).
+
+-spec t_unopaque(erl_type()) -> erl_type().
+
+t_unopaque(T) ->
+  t_unopaque(T, 'universe').
+
+-spec t_unopaque(erl_type(), opaques()) -> erl_type().
+
+t_unopaque(?opaque(_) = T, Opaques) ->
+  case Opaques =:= 'universe' orelse is_opaque_type(T, Opaques) of
+    true -> t_unopaque(t_opaque_structure(T), Opaques);
+    false -> T
+  end;
+t_unopaque(?list(ElemT, Termination, Sz), Opaques) ->
+  ?list(t_unopaque(ElemT, Opaques), t_unopaque(Termination, Opaques), Sz);
+t_unopaque(?tuple(?any, _, _) = T, _) -> T;
+t_unopaque(?tuple(ArgTs, Sz, Tag), Opaques) when is_list(ArgTs) ->
+  NewArgTs = [t_unopaque(A, Opaques) || A <- ArgTs],
+  ?tuple(NewArgTs, Sz, Tag);
+t_unopaque(?tuple_set(Set), Opaques) ->
+  NewSet = [{Sz, [t_unopaque(T, Opaques) || T <- Tuples]}
+	    || {Sz, Tuples} <- Set],
+  ?tuple_set(NewSet);
+t_unopaque(?product(Types), Opaques) ->
+  ?product([t_unopaque(T, Opaques) || T <- Types]);
+t_unopaque(?function(Domain, Range), Opaques) ->
+  ?function(t_unopaque(Domain, Opaques), t_unopaque(Range, Opaques));
+t_unopaque(?union([A,B,F,I,L,N,T,M,O,Map]), Opaques) ->
+  UL = t_unopaque(L, Opaques),
+  UT = t_unopaque(T, Opaques),
+  UF = t_unopaque(F, Opaques),
+  UM = t_unopaque(M, Opaques),
+  UMap = t_unopaque(Map, Opaques),
+  {OF,UO} = case t_unopaque(O, Opaques) of
+              ?opaque(_) = O1 -> {O1, []};
+              Type -> {?none, [Type]}
+            end,
+  t_sup([?union([A,B,UF,I,UL,N,UT,UM,OF,UMap])|UO]);
+t_unopaque(?map(Pairs,DefK,DefV), Opaques) ->
+  t_map([{K, MNess, t_unopaque(V, Opaques)} || {K, MNess, V} <- Pairs],
+	t_unopaque(DefK, Opaques),
+	t_unopaque(DefV, Opaques));
+t_unopaque(T, _) ->
+  T.
+
+%%-----------------------------------------------------------------------------
+%% K-depth abstraction.
+%%
+%% t_limit/2 is the exported function, which checks the type of the
+%% second argument and calls the module local t_limit_k/2 function.
+%%
+
+-spec t_limit(erl_type(), integer()) -> erl_type().
+
+t_limit(Term, K) when is_integer(K) ->
+  t_limit_k(Term, K).
+
+t_limit_k(_, K) when K =< 0 -> ?any;
+t_limit_k(?tuple(?any, ?any, ?any) = T, _K) -> T;
+t_limit_k(?tuple(Elements, Arity, _), K) ->
+  if K =:= 1 -> t_tuple(Arity);
+     true -> t_tuple([t_limit_k(E, K-1) || E <- Elements])
+  end;
+t_limit_k(?tuple_set(_) = T, K) ->
+  t_sup([t_limit_k(Tuple, K) || Tuple <- t_tuple_subtypes(T)]);
+t_limit_k(?list(Elements, Termination, Size), K) ->
+  NewTermination =
+    if K =:= 1 ->
+	%% We do not want to lose the termination information.
+	t_limit_k(Termination, K);
+       true -> t_limit_k(Termination, K - 1)
+    end,
+  NewElements = t_limit_k(Elements, K - 1),
+  TmpList = t_cons(NewElements, NewTermination),
+  case Size of
+    ?nonempty_qual -> TmpList;
+    ?unknown_qual -> 
+      ?list(NewElements1, NewTermination1, _) = TmpList,
+      ?list(NewElements1, NewTermination1, ?unknown_qual)
+  end;
+t_limit_k(?function(Domain, Range), K) ->
+  %% The domain is either a product or any() so we do not decrease the K.
+  ?function(t_limit_k(Domain, K), t_limit_k(Range, K-1));
+t_limit_k(?product(Elements), K) ->
+  ?product([t_limit_k(X, K - 1) || X <- Elements]);
+t_limit_k(?union(Elements), K) ->
+  ?union([t_limit_k(X, K) || X <- Elements]);
+t_limit_k(?opaque(Es), K) ->
+  List = [begin
+            NewS = t_limit_k(S, K),
+            Opaque#opaque{struct = NewS}
+          end || #opaque{struct = S} = Opaque <- set_to_list(Es)],
+  ?opaque(ordsets:from_list(List));
+t_limit_k(?map(Pairs0, DefK0, DefV0), K) ->
+  Fun = fun({EK, MNess, EV}, {Exact, DefK1, DefV1}) ->
+	    LV = t_limit_k(EV, K - 1),
+	    case t_limit_k(EK, K - 1) of
+	      EK -> {[{EK,MNess,LV}|Exact], DefK1, DefV1};
+	      LK -> {Exact, t_sup(LK, DefK1), t_sup(LV, DefV1)}
+	    end
+	end,
+  {Pairs, DefK2, DefV2} = lists:foldr(Fun, {[], DefK0, DefV0}, Pairs0),
+  t_map(Pairs, t_limit_k(DefK2, K - 1), t_limit_k(DefV2, K - 1));
+t_limit_k(T, _K) -> T.
+
+%%============================================================================
+%% 
+%% Abstract records. Used for comparing contracts.
+%%
+%%============================================================================
+
+-spec t_abstract_records(erl_type(), type_table()) -> erl_type().
+
+t_abstract_records(?list(Contents, Termination, Size), RecDict) ->
+  case t_abstract_records(Contents, RecDict) of
+    ?none -> ?none;
+    NewContents ->
+      %% Be careful here to make the termination collapse if necessary.
+      case t_abstract_records(Termination, RecDict) of
+	?nil -> ?list(NewContents, ?nil, Size);
+	?any -> ?list(NewContents, ?any, Size);
+	Other ->
+	  ?list(NewContents2, NewTermination, _) = t_cons(NewContents, Other),
+	  ?list(NewContents2, NewTermination, Size)
+      end
+  end;
+t_abstract_records(?function(Domain, Range), RecDict) ->
+  ?function(t_abstract_records(Domain, RecDict), 
+	    t_abstract_records(Range, RecDict));
+t_abstract_records(?product(Types), RecDict) -> 
+  ?product([t_abstract_records(T, RecDict) || T <- Types]);
+t_abstract_records(?union(Types), RecDict) -> 
+  t_sup([t_abstract_records(T, RecDict) || T <- Types]);
+t_abstract_records(?tuple(?any, ?any, ?any) = T, _RecDict) ->
+  T;
+t_abstract_records(?tuple(Elements, Arity, ?atom(_) = Tag), RecDict) ->
+  [TagAtom] = atom_vals(Tag),
+  case lookup_record(TagAtom, Arity - 1, RecDict) of
+    error -> t_tuple([t_abstract_records(E, RecDict) || E <- Elements]);
+    {ok, Fields} -> t_tuple([Tag|[T || {_Name, _Abstr, T} <- Fields]])
+  end;
+t_abstract_records(?tuple(Elements, _Arity, _Tag), RecDict) ->
+  t_tuple([t_abstract_records(E, RecDict) || E <- Elements]);
+t_abstract_records(?tuple_set(_) = Tuples, RecDict) ->
+  t_sup([t_abstract_records(T, RecDict) || T <- t_tuple_subtypes(Tuples)]);
+t_abstract_records(?opaque(_)=Type, RecDict) ->
+  t_abstract_records(t_opaque_structure(Type), RecDict);
+t_abstract_records(T, _RecDict) -> 
+  T.
+
+%% Map over types. Depth first. Used by the contract checker. ?list is
+%% not fully implemented so take care when changing the type in Termination.
+
+-spec t_map(fun((erl_type()) -> erl_type()), erl_type()) -> erl_type().
+
+t_map(Fun, ?list(Contents, Termination, Size)) ->
+  Fun(?list(t_map(Fun, Contents), t_map(Fun, Termination), Size));
+t_map(Fun, ?function(Domain, Range)) ->
+  Fun(?function(t_map(Fun, Domain), t_map(Fun, Range)));
+t_map(Fun, ?product(Types)) -> 
+  Fun(?product([t_map(Fun, T) || T <- Types]));
+t_map(Fun, ?union(Types)) ->
+  Fun(t_sup([t_map(Fun, T) || T <- Types]));
+t_map(Fun, ?tuple(?any, ?any, ?any) = T) ->
+  Fun(T);
+t_map(Fun, ?tuple(Elements, _Arity, _Tag)) ->
+  Fun(t_tuple([t_map(Fun, E) || E <- Elements]));
+t_map(Fun, ?tuple_set(_) = Tuples) ->
+  Fun(t_sup([t_map(Fun, T) || T <- t_tuple_subtypes(Tuples)]));
+t_map(Fun, ?opaque(Set)) ->
+  L = [Opaque#opaque{struct = NewS} ||
+        #opaque{struct = S} = Opaque <- set_to_list(Set),
+        not t_is_none(NewS = t_map(Fun, S))],
+  Fun(case L of
+        [] -> ?none;
+        _ -> ?opaque(ordsets:from_list(L))
+      end);
+t_map(Fun, ?map(Pairs,DefK,DefV)) ->
+  %% TODO:
+  Fun(t_map(Pairs, Fun(DefK), Fun(DefV)));
+t_map(Fun, T) ->
+  Fun(T).
+
+%%=============================================================================
+%%
+%% Prettyprinter
+%%
+%%=============================================================================
+
+-spec t_to_string(erl_type()) -> string().
+
+t_to_string(T) ->
+  t_to_string(T, dict:new()).
+
+-spec t_to_string(erl_type(), type_table()) -> string().
+
+t_to_string(?any, _RecDict) ->
+  "any()";
+t_to_string(?none, _RecDict) ->
+  "none()";
+t_to_string(?unit, _RecDict) ->
+  "no_return()";
+t_to_string(?atom(?any), _RecDict) -> 
+  "atom()";
+t_to_string(?atom(Set), _RecDict) ->
+  case set_size(Set) of
+    2 ->
+      case set_is_element(true, Set) andalso set_is_element(false, Set) of
+	true -> "boolean()";
+	false -> set_to_string(Set)
+      end;
+    _ ->
+      set_to_string(Set)
+  end;
+t_to_string(?bitstr(0, 0), _RecDict) ->
+  "<<>>";
+t_to_string(?bitstr(8, 0), _RecDict) ->
+  "binary()";
+t_to_string(?bitstr(1, 0), _RecDict) ->
+  "bitstring()";
+t_to_string(?bitstr(0, B), _RecDict) ->
+  flat_format("<<_:~w>>", [B]);
+t_to_string(?bitstr(U, 0), _RecDict) ->
+  flat_format("<<_:_*~w>>", [U]);
+t_to_string(?bitstr(U, B), _RecDict) ->
+  flat_format("<<_:~w,_:_*~w>>", [B, U]);
+t_to_string(?function(?any, ?any), _RecDict) ->
+  "fun()";
+t_to_string(?function(?any, Range), RecDict) ->
+  "fun((...) -> " ++ t_to_string(Range, RecDict) ++ ")";
+t_to_string(?function(?product(ArgList), Range), RecDict) ->
+  "fun((" ++ comma_sequence(ArgList, RecDict) ++ ") -> "
+    ++ t_to_string(Range, RecDict) ++ ")";
+t_to_string(?identifier(Set), _RecDict) ->
+  case Set of
+    ?any -> "identifier()";
+    _ ->
+      string:join([flat_format("~w()", [T]) || T <- set_to_list(Set)], " | ")
+  end;
+t_to_string(?opaque(Set), RecDict) ->
+  string:join([opaque_type(Mod, Name, Args, S, RecDict) ||
+                #opaque{mod = Mod, name = Name, struct = S, args = Args}
+                  <- set_to_list(Set)],
+	      " | ");
+t_to_string(?matchstate(Pres, Slots), RecDict) ->
+  flat_format("ms(~s,~s)", [t_to_string(Pres, RecDict),
+                            t_to_string(Slots,RecDict)]);
+t_to_string(?nil, _RecDict) ->
+  "[]";
+t_to_string(?nonempty_list(Contents, Termination), RecDict) ->
+  ContentString = t_to_string(Contents, RecDict),
+  case Termination of
+    ?nil ->
+      case Contents of
+	?char -> "nonempty_string()";
+	_ -> "["++ContentString++",...]"
+      end;
+    ?any -> 
+      %% Just a safety check.
+      case Contents =:= ?any of
+	true -> ok;
+	false ->
+          %% XXX. See comment below.
+          %% erlang:error({illegal_list, ?nonempty_list(Contents, Termination)})
+          ok
+      end,
+      "nonempty_maybe_improper_list()";
+    _ ->
+      case t_is_subtype(t_nil(), Termination) of
+	true ->
+	  "nonempty_maybe_improper_list("++ContentString++","
+	    ++t_to_string(Termination, RecDict)++")";
+	false ->
+	  "nonempty_improper_list("++ContentString++","
+	    ++t_to_string(Termination, RecDict)++")"
+      end
+  end;
+t_to_string(?list(Contents, Termination, ?unknown_qual), RecDict) ->
+  ContentString = t_to_string(Contents, RecDict),
+  case Termination of
+    ?nil ->
+      case Contents of
+	?char -> "string()";
+	_ -> "["++ContentString++"]"
+      end;
+    ?any ->
+      %% Just a safety check.      
+      %% XXX. Types such as "maybe_improper_list(integer(), any())"
+      %% are OK, but cannot be printed!?
+      case Contents =:= ?any of
+	true -> ok;
+	false ->
+          ok
+          %% L = ?list(Contents, Termination, ?unknown_qual),
+          %% erlang:error({illegal_list, L})
+      end,
+      "maybe_improper_list()";
+    _ -> 
+      case t_is_subtype(t_nil(), Termination) of
+	true ->
+	  "maybe_improper_list("++ContentString++","
+	    ++t_to_string(Termination, RecDict)++")";
+	false ->
+	  "improper_list("++ContentString++","
+	    ++t_to_string(Termination, RecDict)++")"
+      end
+  end;
+t_to_string(?int_set(Set), _RecDict) ->
+  set_to_string(Set);
+t_to_string(?byte, _RecDict) -> "byte()";
+t_to_string(?char, _RecDict) -> "char()";
+t_to_string(?integer_pos, _RecDict) -> "pos_integer()";
+t_to_string(?integer_non_neg, _RecDict) -> "non_neg_integer()";
+t_to_string(?integer_neg, _RecDict) -> "neg_integer()";
+t_to_string(?int_range(From, To), _RecDict) ->
+  flat_format("~w..~w", [From, To]);
+t_to_string(?integer(?any), _RecDict) -> "integer()";
+t_to_string(?float, _RecDict) -> "float()";
+t_to_string(?number(?any, ?unknown_qual), _RecDict) -> "number()";
+t_to_string(?product(List), RecDict) -> 
+  "<" ++ comma_sequence(List, RecDict) ++ ">";
+t_to_string(?map([],?any,?any), _RecDict) -> "map()";
+t_to_string(?map(Pairs0,DefK,DefV), RecDict) ->
+  {Pairs, ExtraEl} =
+    case {DefK, DefV} of
+      {?none, ?none} -> {Pairs0, []};
+      _ -> {Pairs0 ++ [{DefK,?opt,DefV}], []}
+    end,
+  Tos = fun(T) -> case T of
+		    ?any -> "_";
+		    _ -> t_to_string(T, RecDict)
+		  end end,
+  StrMand = [{Tos(K),Tos(V)}||{K,?mand,V}<-Pairs],
+  StrOpt  = [{Tos(K),Tos(V)}||{K,?opt,V}<-Pairs],
+  "#{" ++ string:join([K ++ ":=" ++ V||{K,V}<-StrMand]
+		      ++ [K ++ "=>" ++ V||{K,V}<-StrOpt]
+		      ++ ExtraEl, ", ") ++ "}";
+t_to_string(?tuple(?any, ?any, ?any), _RecDict) -> "tuple()";
+t_to_string(?tuple(Elements, _Arity, ?any), RecDict) ->   
+  "{" ++ comma_sequence(Elements, RecDict) ++ "}";
+t_to_string(?tuple(Elements, Arity, Tag), RecDict) ->
+  [TagAtom] = atom_vals(Tag),
+  case lookup_record(TagAtom, Arity-1, RecDict) of
+    error -> "{" ++ comma_sequence(Elements, RecDict) ++ "}";
+    {ok, FieldNames} ->
+      record_to_string(TagAtom, Elements, FieldNames, RecDict)
+  end;
+t_to_string(?tuple_set(_) = T, RecDict) ->
+  union_sequence(t_tuple_subtypes(T), RecDict);
+t_to_string(?union(Types), RecDict) ->
+  union_sequence([T || T <- Types, T =/= ?none], RecDict);
+t_to_string(?var(Id), _RecDict) when is_atom(Id) ->
+  flat_format("~s", [atom_to_list(Id)]);
+t_to_string(?var(Id), _RecDict) when is_integer(Id) ->
+  flat_format("var(~w)", [Id]).
+
+
+record_to_string(Tag, [_|Fields], FieldNames, RecDict) ->
+  FieldStrings = record_fields_to_string(Fields, FieldNames, RecDict, []),
+  "#" ++ atom_to_string(Tag) ++ "{" ++ string:join(FieldStrings, ",") ++ "}".
+
+record_fields_to_string([F|Fs], [{FName, _Abstr, DefType}|FDefs],
+                        RecDict, Acc) ->
+  NewAcc =
+    case
+      t_is_equal(F, t_any()) orelse
+      (t_is_any_atom('undefined', F) andalso
+       not t_is_none(t_inf(F, DefType)))
+    of
+      true -> Acc;
+      false ->
+	StrFV = atom_to_string(FName) ++ "::" ++ t_to_string(F, RecDict),
+	[StrFV|Acc]
+    end,
+  record_fields_to_string(Fs, FDefs, RecDict, NewAcc);
+record_fields_to_string([], [], _RecDict, Acc) ->
+  lists:reverse(Acc).
+
+-spec record_field_diffs_to_string(erl_type(), type_table()) -> string().
+
+record_field_diffs_to_string(?tuple([_|Fs], Arity, Tag), RecDict) ->
+  [TagAtom] = atom_vals(Tag),
+  {ok, FieldNames} = lookup_record(TagAtom, Arity-1, RecDict),
+  %% io:format("RecCElems = ~p\nRecTypes = ~p\n", [Fs, FieldNames]),
+  FieldDiffs = field_diffs(Fs, FieldNames, RecDict, []),
+  string:join(FieldDiffs, " and ").
+
+field_diffs([F|Fs], [{FName, _Abstr, DefType}|FDefs], RecDict, Acc) ->
+  %% Don't care about opaqueness for now.
+  NewAcc =
+    case not t_is_none(t_inf(F, DefType)) of
+      true -> Acc;
+      false ->
+	Str = atom_to_string(FName) ++ "::" ++ t_to_string(DefType, RecDict),
+	[Str|Acc]
+    end,
+  field_diffs(Fs, FDefs, RecDict, NewAcc);
+field_diffs([], [], _, Acc) ->
+  lists:reverse(Acc).
+
+comma_sequence(Types, RecDict) ->
+  List = [case T =:= ?any of
+	    true -> "_";
+	    false -> t_to_string(T, RecDict)
+	  end || T <- Types],
+  string:join(List, ",").
+
+union_sequence(Types, RecDict) ->
+  List = [t_to_string(T, RecDict) || T <- Types], 
+  string:join(List, " | ").
+
+-ifdef(DEBUG).
+opaque_type(Mod, Name, _Args, S, RecDict) ->
+  ArgsString = comma_sequence(_Args, RecDict),
+  String = t_to_string(S, RecDict),
+  opaque_name(Mod, Name, ArgsString) ++ "[" ++ String ++ "]".
+-else.
+opaque_type(Mod, Name, Args, _S, RecDict) ->
+  ArgsString = comma_sequence(Args, RecDict),
+  opaque_name(Mod, Name, ArgsString).
+-endif.
+
+opaque_name(Mod, Name, Extra) ->
+  S = mod_name(Mod, Name),
+  flat_format("~s(~s)", [S, Extra]).
+
+mod_name(Mod, Name) ->
+  flat_format("~w:~w", [Mod, Name]).
+
+%%=============================================================================
+%% 
+%% Build a type from parse forms.
+%%
+%%=============================================================================
+
+-type type_names() :: [type_key() | record_key()].
+
+-type mta()   :: {module(), atom(), arity()}.
+-type mra()   :: {module(), atom(), arity()}.
+-type site()  :: {'type', mta()} | {'spec', mfa()} | {'record', mra()}.
+-type cache_key() :: {module(), atom(), expand_depth(),
+                      [erl_type()], type_names()}.
+-opaque cache() :: #{cache_key() => {erl_type(), expand_limit()}}.
+
+-spec t_from_form(parse_form(), sets:set(mfa()), site(), mod_records(),
+                  var_table(), cache()) -> {erl_type(), cache()}.
+
+t_from_form(Form, ExpTypes, Site, RecDict, VarTab, Cache) ->
+  t_from_form1(Form, ExpTypes, Site, RecDict, VarTab, Cache).
+
+%% Replace external types with with none().
+-spec t_from_form_without_remote(parse_form(), site(), type_table()) ->
+                                    {erl_type(), cache()}.
+
+t_from_form_without_remote(Form, Site, TypeTable) ->
+  Module = site_module(Site),
+  RecDict = dict:from_list([{Module, TypeTable}]),
+  ExpTypes = replace_by_none,
+  VarTab = var_table__new(),
+  Cache = cache__new(),
+  t_from_form1(Form, ExpTypes, Site, RecDict, VarTab, Cache).
+
+%% REC_TYPE_LIMIT is used for limiting the depth of recursive types.
+%% EXPAND_LIMIT is used for limiting the size of types by
+%% limiting the number of elements of lists within one type form.
+%% EXPAND_DEPTH is used in conjunction with EXPAND_LIMIT to make the
+%% types balanced (unions will otherwise collapse to any()) by limiting
+%% the depth the same way as t_limit/2 does.
+
+-type expand_limit() :: integer().
+
+-type expand_depth() :: integer().
+
+-record(from_form, {site   :: site(),
+                    xtypes :: sets:set(mfa()) | 'replace_by_none',
+                    mrecs  :: mod_records(),
+                    vtab   :: var_table(),
+                    tnames :: type_names()}).
+
+-spec t_from_form1(parse_form(), sets:set(mfa()) | 'replace_by_none',
+                   site(), mod_records(), var_table(), cache()) ->
+                      {erl_type(), cache()}.
+
+t_from_form1(Form, ET, Site, MR, V, C) ->
+  TypeNames = initial_typenames(Site),
+  State = #from_form{site   = Site,
+                     xtypes = ET,
+                     mrecs  = MR,
+                     vtab   = V,
+                     tnames = TypeNames},
+  L = ?EXPAND_LIMIT,
+  {T1, L1, C1} = from_form(Form, State, ?EXPAND_DEPTH, L, C),
+  if
+    L1 =< 0 ->
+      from_form_loop(Form, State, 1, L, C1);
+    true ->
+       {T1, C1}
+  end.
+
+initial_typenames({type, _MTA}=Site) -> [Site];
+initial_typenames({spec, _MFA}) -> [];
+initial_typenames({record, _MRA}) -> [].
+
+from_form_loop(Form, State, D, Limit, C) ->
+  {T1, L1, C1} = from_form(Form, State, D, Limit, C),
+  Delta = Limit - L1,
+  if
+    %% Save some time by assuming next depth will exceed the limit.
+    Delta * 8 > Limit ->
+      {T1, C1};
+    true ->
+      D1 = D + 1,
+      from_form_loop(Form, State, D1, Limit, C1)
+  end.
+
+-spec from_form(parse_form(),
+                #from_form{},
+                expand_depth(),
+                expand_limit(),
+                cache()) -> {erl_type(), expand_limit(), cache()}.
+
+%% If there is something wrong with parse_form()
+%% throw({error, io_lib:chars()} is called;
+%% for unknown remote types
+%% self() ! {self(), ext_types, {RemMod, Name, ArgsLen}}
+%% is called, unless 'replace_by_none' is given.
+%%
+%% It is assumed that site_module(S) can be found in MR.
+
+from_form(_, _S, D, L, C) when D =< 0 ; L =< 0 ->
+  {t_any(), L, C};
+from_form({var, _L, '_'}, _S, _D, L, C) ->
+  {t_any(), L, C};
+from_form({var, _L, Name}, S, _D, L, C) ->
+  V = S#from_form.vtab,
+  case maps:find(Name, V) of
+    error -> {t_var(Name), L, C};
+    {ok, Val} -> {Val, L, C}
+  end;
+from_form({ann_type, _L, [_Var, Type]}, S, D, L, C) ->
+  from_form(Type, S, D, L, C);
+from_form({paren_type, _L, [Type]}, S, D, L, C) ->
+  from_form(Type, S, D, L, C);
+from_form({remote_type, _L, [{atom, _, Module}, {atom, _, Type}, Args]},
+	    S, D, L, C) ->
+  remote_from_form(Module, Type, Args, S, D, L, C);
+from_form({atom, _L, Atom}, _S, _D, L, C) ->
+  {t_atom(Atom), L, C};
+from_form({integer, _L, Int}, _S, _D, L, C) ->
+  {t_integer(Int), L, C};
+from_form({op, _L, _Op, _Arg} = Op, _S, _D, L, C) ->
+  case erl_eval:partial_eval(Op) of
+    {integer, _, Val} ->
+      {t_integer(Val), L, C};
+    _ -> throw({error, io_lib:format("Unable to evaluate type ~w\n", [Op])})
+  end;
+from_form({op, _L, _Op, _Arg1, _Arg2} = Op, _S, _D, L, C) ->
+  case erl_eval:partial_eval(Op) of
+    {integer, _, Val} ->
+      {t_integer(Val), L, C};
+    _ -> throw({error, io_lib:format("Unable to evaluate type ~w\n", [Op])})
+  end;
+from_form({type, _L, any, []}, _S, _D, L, C) ->
+  {t_any(), L, C};
+from_form({type, _L, arity, []}, _S, _D, L, C) ->
+  {t_arity(), L, C};
+from_form({type, _L, atom, []}, _S, _D, L, C) ->
+  {t_atom(), L, C};
+from_form({type, _L, binary, []}, _S, _D, L, C) ->
+  {t_binary(), L, C};
+from_form({type, _L, binary, [Base, Unit]} = Type, _S, _D, L, C) ->
+  case {erl_eval:partial_eval(Base), erl_eval:partial_eval(Unit)} of
+    {{integer, _, B}, {integer, _, U}} when B >= 0, U >= 0 ->
+      {t_bitstr(U, B), L, C};
+    _ -> throw({error, io_lib:format("Unable to evaluate type ~w\n", [Type])})
+  end;
+from_form({type, _L, bitstring, []}, _S, _D, L, C) ->
+  {t_bitstr(), L, C};
+from_form({type, _L, bool, []}, _S, _D, L, C) ->
+  {t_boolean(), L, C};	% XXX: Temporarily
+from_form({type, _L, boolean, []}, _S, _D, L, C) ->
+  {t_boolean(), L, C};
+from_form({type, _L, byte, []}, _S, _D, L, C) ->
+  {t_byte(), L, C};
+from_form({type, _L, char, []}, _S, _D, L, C) ->
+  {t_char(), L, C};
+from_form({type, _L, float, []}, _S, _D, L, C) ->
+  {t_float(), L, C};
+from_form({type, _L, function, []}, _S, _D, L, C) ->
+  {t_fun(), L, C};
+from_form({type, _L, 'fun', []}, _S, _D, L, C) ->
+  {t_fun(), L, C};
+from_form({type, _L, 'fun', [{type, _, any}, Range]}, S, D, L, C) ->
+  {T, L1, C1} = from_form(Range, S, D - 1, L - 1, C),
+  {t_fun(T), L1, C1};
+from_form({type, _L, 'fun', [{type, _, product, Domain}, Range]},
+          S, D, L, C) ->
+  {Dom1, L1, C1} = list_from_form(Domain, S, D, L, C),
+  {Ran1, L2, C2} = from_form(Range, S, D, L1, C1),
+  {t_fun(Dom1, Ran1), L2, C2};
+from_form({type, _L, identifier, []}, _S, _D, L, C) ->
+  {t_identifier(), L, C};
+from_form({type, _L, integer, []}, _S, _D, L, C) ->
+  {t_integer(), L, C};
+from_form({type, _L, iodata, []}, _S, _D, L, C) ->
+  {t_iodata(), L, C};
+from_form({type, _L, iolist, []}, _S, _D, L, C) ->
+  {t_iolist(), L, C};
+from_form({type, _L, list, []}, _S, _D, L, C) ->
+  {t_list(), L, C};
+from_form({type, _L, list, [Type]}, S, D, L, C) ->
+  {T, L1, C1} = from_form(Type, S, D - 1, L - 1, C),
+  {t_list(T), L1, C1};
+from_form({type, _L, map, any}, S, D, L, C) ->
+  builtin_type(map, t_map(), S, D, L, C);
+from_form({type, _L, map, List}, S, D0, L, C) ->
+  {Pairs1, L5, C5} =
+    fun PairsFromForm(_, L1, C1) when L1 =< 0 -> {[{?any,?opt,?any}], L1, C1};
+	PairsFromForm([], L1, C1) -> {[], L1, C1};
+	PairsFromForm([{type, _, Oper, [KF, VF]}|T], L1, C1) ->
+        D = D0 - 1,
+	{Key, L2, C2} = from_form(KF, S, D, L1, C1),
+	{Val, L3, C3} = from_form(VF, S, D, L2, C2),
+	{Pairs0, L4, C4} = PairsFromForm(T, L3 - 1, C3),
+	case Oper of
+	  map_field_assoc -> {[{Key,?opt, Val}|Pairs0], L4, C4};
+	  map_field_exact -> {[{Key,?mand,Val}|Pairs0], L4, C4}
+	end
+    end(List, L, C),
+  try
+    {Pairs, DefK, DefV} = map_from_form(Pairs1, [], [], [], ?none, ?none),
+    {t_map(Pairs, DefK, DefV), L5, C5}
+  catch none -> {t_none(), L5, C5}
+  end;
+from_form({type, _L, mfa, []}, _S, _D, L, C) ->
+  {t_mfa(), L, C};
+from_form({type, _L, module, []}, _S, _D, L, C) ->
+  {t_module(), L, C};
+from_form({type, _L, nil, []}, _S, _D, L, C) ->
+  {t_nil(), L, C};
+from_form({type, _L, neg_integer, []}, _S, _D, L, C) ->
+  {t_neg_integer(), L, C};
+from_form({type, _L, non_neg_integer, []}, _S, _D, L, C) ->
+  {t_non_neg_integer(), L, C};
+from_form({type, _L, no_return, []}, _S, _D, L, C) ->
+  {t_unit(), L, C};
+from_form({type, _L, node, []}, _S, _D, L, C) ->
+  {t_node(), L, C};
+from_form({type, _L, none, []}, _S, _D, L, C) ->
+  {t_none(), L, C};
+from_form({type, _L, nonempty_list, []}, _S, _D, L, C) ->
+  {t_nonempty_list(), L, C};
+from_form({type, _L, nonempty_list, [Type]}, S, D, L, C) ->
+  {T, L1, C1} = from_form(Type, S, D, L - 1, C),
+  {t_nonempty_list(T), L1, C1};
+from_form({type, _L, nonempty_improper_list, [Cont, Term]}, S, D, L, C) ->
+  {T1, L1, C1} = from_form(Cont, S, D, L - 1, C),
+  {T2, L2, C2} = from_form(Term, S, D, L1, C1),
+  {t_cons(T1, T2), L2, C2};
+from_form({type, _L, nonempty_maybe_improper_list, []}, _S, _D, L, C) ->
+  {t_cons(?any, ?any), L, C};
+from_form({type, _L, nonempty_maybe_improper_list, [Cont, Term]},
+          S, D, L, C) ->
+  {T1, L1, C1} = from_form(Cont, S, D, L - 1, C),
+  {T2, L2, C2} = from_form(Term, S, D, L1, C1),
+  {t_cons(T1, T2), L2, C2};
+from_form({type, _L, nonempty_string, []}, _S, _D, L, C) ->
+  {t_nonempty_string(), L, C};
+from_form({type, _L, number, []}, _S, _D, L, C) ->
+  {t_number(), L, C};
+from_form({type, _L, pid, []}, _S, _D, L, C) ->
+  {t_pid(), L, C};
+from_form({type, _L, port, []}, _S, _D, L, C) ->
+  {t_port(), L, C};
+from_form({type, _L, pos_integer, []}, _S, _D, L, C) ->
+  {t_pos_integer(), L, C};
+from_form({type, _L, maybe_improper_list, []}, _S, _D, L, C) ->
+  {t_maybe_improper_list(), L, C};
+from_form({type, _L, maybe_improper_list, [Content, Termination]},
+          S, D, L, C) ->
+  {T1, L1, C1} = from_form(Content, S, D, L - 1, C),
+  {T2, L2, C2} = from_form(Termination, S, D, L1, C1),
+  {t_maybe_improper_list(T1, T2), L2, C2};
+from_form({type, _L, product, Elements}, S, D, L, C) ->
+  {Lst, L1, C1} = list_from_form(Elements, S, D - 1, L, C),
+  {t_product(Lst), L1, C1};
+from_form({type, _L, range, [From, To]} = Type, _S, _D, L, C) ->
+  case {erl_eval:partial_eval(From), erl_eval:partial_eval(To)} of
+    {{integer, _, FromVal}, {integer, _, ToVal}} ->
+      {t_from_range(FromVal, ToVal), L, C};
+    _ -> throw({error, io_lib:format("Unable to evaluate type ~w\n", [Type])})
+  end;
+from_form({type, _L, record, [Name|Fields]}, S, D, L, C) ->
+  record_from_form(Name, Fields, S, D, L, C);
+from_form({type, _L, reference, []}, _S, _D, L, C) ->
+  {t_reference(), L, C};
+from_form({type, _L, string, []}, _S, _D, L, C) ->
+  {t_string(), L, C};
+from_form({type, _L, term, []}, _S, _D, L, C) ->
+  {t_any(), L, C};
+from_form({type, _L, timeout, []}, _S, _D, L, C) ->
+  {t_timeout(), L, C};
+from_form({type, _L, tuple, any}, _S, _D, L, C) ->
+  {t_tuple(), L, C};
+from_form({type, _L, tuple, Args}, S, D, L, C) ->
+  {Lst, L1, C1} = list_from_form(Args, S, D - 1, L, C),
+  {t_tuple(Lst), L1, C1};
+from_form({type, _L, union, Args}, S, D, L, C) ->
+  {Lst, L1, C1} = list_from_form(Args, S, D, L, C),
+  {t_sup(Lst), L1, C1};
+from_form({user_type, _L, Name, Args}, S, D, L, C) ->
+  type_from_form(Name, Args, S, D, L, C);
+from_form({type, _L, Name, Args}, S, D, L, C) ->
+  %% Compatibility: modules compiled before Erlang/OTP 18.0.
+  type_from_form(Name, Args, S, D, L, C);
+from_form({opaque, _L, Name, {Mod, Args, Rep}}, _S, _D, L, C) ->
+  %% XXX. To be removed.
+  {t_opaque(Mod, Name, Args, Rep), L, C}.
+
+builtin_type(Name, Type, S, D, L, C) ->
+  #from_form{site = Site, mrecs = MR} = S,
+  M = site_module(Site),
+  case dict:find(M, MR) of
+    {ok, R} ->
+      case lookup_type(Name, 0, R) of
+        {_, {{_M, _FL, _F, _A}, _T}} ->
+          type_from_form(Name, [], S, D, L, C);
+        error ->
+          {Type, L, C}
+      end;
+    error ->
+      {Type, L, C}
+  end.
+
+type_from_form(Name, Args, S, D, L, C) ->
+  #from_form{site = Site, mrecs = MR, tnames = TypeNames} = S,
+  ArgsLen = length(Args),
+  Module = site_module(Site),
+  TypeName = {type, {Module, Name, ArgsLen}},
+  case can_unfold_more(TypeName, TypeNames) of
+    true ->
+      {ok, R} = dict:find(Module, MR),
+      type_from_form1(Name, Args, ArgsLen, R, TypeName, TypeNames,
+                      S, D, L, C);
+    false ->
+      {t_any(), L, C}
+  end.
+
+type_from_form1(Name, Args, ArgsLen, R, TypeName, TypeNames, S, D, L, C) ->
+  case lookup_type(Name, ArgsLen, R) of
+    {Tag, {{Module, _FileName, Form, ArgNames}, Type}} ->
+      NewTypeNames = [TypeName|TypeNames],
+      S1 = S#from_form{tnames = NewTypeNames},
+      {ArgTypes, L1, C1} = list_from_form(Args, S1, D, L, C),
+      CKey = cache_key(Module, Name, ArgTypes, TypeNames, D),
+      case cache_find(CKey, C) of
+        {CachedType, DeltaL} ->
+          {CachedType, L1 - DeltaL, C};
+        error ->
+          List = lists:zip(ArgNames, ArgTypes),
+          TmpV = maps:from_list(List),
+          S2 = S1#from_form{site = TypeName, vtab = TmpV},
+          Fun = fun(DD, LL) -> from_form(Form, S2, DD, LL, C1) end,
+          {NewType, L3, C3} =
+            case Tag of
+              type ->
+                recur_limit(Fun, D, L1, TypeName, TypeNames);
+              opaque ->
+                {Rep, L2, C2} = recur_limit(Fun, D, L1, TypeName, TypeNames),
+                Rep1 = choose_opaque_type(Rep, Type),
+                Rep2 = case cannot_have_opaque(Rep1, TypeName, TypeNames) of
+                         true -> Rep1;
+                         false ->
+                           ArgTypes2 = subst_all_vars_to_any_list(ArgTypes),
+                           t_opaque(Module, Name, ArgTypes2, Rep1)
+                       end,
+                {Rep2, L2, C2}
+            end,
+          C4 = cache_put(CKey, NewType, L1 - L3, C3),
+          {NewType, L3, C4}
+      end;
+    error ->
+      Msg = io_lib:format("Unable to find type ~w/~w\n",
+                          [Name, ArgsLen]),
+      throw({error, Msg})
+  end.
+
+remote_from_form(RemMod, Name, Args, S, D, L, C) ->
+  #from_form{xtypes = ET, mrecs = MR, tnames = TypeNames} = S,
+  if
+    ET =:= replace_by_none ->
+      {t_none(), L, C};
+    true ->
+      ArgsLen = length(Args),
+      MFA = {RemMod, Name, ArgsLen},
+      case dict:find(RemMod, MR) of
+        error ->
+          self() ! {self(), ext_types, MFA},
+          {t_any(), L, C};
+        {ok, RemDict} ->
+          case sets:is_element(MFA, ET) of
+            true ->
+              RemType = {type, MFA},
+              case can_unfold_more(RemType, TypeNames) of
+                true ->
+                  remote_from_form1(RemMod, Name, Args, ArgsLen, RemDict,
+                                    RemType, TypeNames, S, D, L, C);
+                false ->
+                  {t_any(), L, C}
+              end;
+            false ->
+              self() ! {self(), ext_types, {RemMod, Name, ArgsLen}},
+              {t_any(), L, C}
+          end
+      end
+  end.
+
+remote_from_form1(RemMod, Name, Args, ArgsLen, RemDict, RemType, TypeNames,
+                  S, D, L, C) ->
+  case lookup_type(Name, ArgsLen, RemDict) of
+    {Tag, {{Mod, _FileLine, Form, ArgNames}, Type}} ->
+      NewTypeNames = [RemType|TypeNames],
+      S1 = S#from_form{tnames = NewTypeNames},
+      {ArgTypes, L1, C1} = list_from_form(Args, S1, D, L, C),
+      CKey = cache_key(RemMod, Name, ArgTypes, TypeNames, D),
+      %% case error of
+      case cache_find(CKey, C) of
+        {CachedType, DeltaL} ->
+          {CachedType, L - DeltaL, C};
+        error ->
+          List = lists:zip(ArgNames, ArgTypes),
+          TmpVarTab = maps:from_list(List),
+          S2 = S1#from_form{site = RemType, vtab = TmpVarTab},
+          Fun = fun(DD, LL) -> from_form(Form, S2, DD, LL, C1) end,
+          {NewType, L3, C3} =
+            case Tag of
+              type ->
+                recur_limit(Fun, D, L1, RemType, TypeNames);
+              opaque ->
+                {NewRep, L2, C2} = recur_limit(Fun, D, L1, RemType, TypeNames),
+                NewRep1 = choose_opaque_type(NewRep, Type),
+                NewRep2 =
+                  case cannot_have_opaque(NewRep1, RemType, TypeNames) of
+                    true -> NewRep1;
+                    false ->
+                      ArgTypes2 = subst_all_vars_to_any_list(ArgTypes),
+                      t_opaque(Mod, Name, ArgTypes2, NewRep1)
+                  end,
+                {NewRep2, L2, C2}
+            end,
+          C4 = cache_put(CKey, NewType, L1 - L3, C3),
+          {NewType, L3, C4}
+      end;
+    error ->
+      Msg = io_lib:format("Unable to find remote type ~w:~w()\n",
+                          [RemMod, Name]),
+      throw({error, Msg})
+  end.
+
+subst_all_vars_to_any_list(Types) ->
+  [subst_all_vars_to_any(Type) || Type <- Types].
+
+%% Opaque types (both local and remote) are problematic when it comes
+%% to the limits (TypeNames, D, and L). The reason is that if any() is
+%% substituted for a more specialized subtype of an opaque type, the
+%% property stated along with decorate_with_opaque() (the type has to
+%% be a subtype of the declared type) no longer holds.
+%%
+%% The less than perfect remedy: if the opaque type created from a
+%% form is not a subset of the declared type, the declared type is
+%% used instead, effectively bypassing the limits, and potentially
+%% resulting in huge types.
+choose_opaque_type(Type, DeclType) ->
+  case
+    t_is_subtype(subst_all_vars_to_any(Type),
+                 subst_all_vars_to_any(DeclType))
+  of
+    true -> Type;
+    false -> DeclType
+  end.
+
+record_from_form({atom, _, Name}, ModFields, S, D0, L0, C) ->
+  #from_form{site = Site, mrecs = MR, tnames = TypeNames} = S,
+  RecordType = {record, Name},
+  case can_unfold_more(RecordType, TypeNames) of
+    true ->
+      M = site_module(Site),
+      {ok, R} = dict:find(M, MR),
+      case lookup_record(Name, R) of
+        {ok, DeclFields} ->
+          NewTypeNames = [RecordType|TypeNames],
+          Site1 = {record, {M, Name, length(DeclFields)}},
+          S1 = S#from_form{site = Site1, tnames = NewTypeNames},
+          Fun = fun(D, L) ->
+                    {GetModRec, L1, C1} =
+                      get_mod_record(ModFields, DeclFields, S1, D, L, C),
+                    case GetModRec of
+                      {error, FieldName} ->
+                        throw({error,
+                               io_lib:format("Illegal declaration of #~w{~w}\n",
+                                             [Name, FieldName])});
+                      {ok, NewFields} ->
+                        S2 = S1#from_form{vtab = var_table__new()},
+                        {NewFields1, L2, C2} =
+                          fields_from_form(NewFields, S2, D, L1, C1),
+                        Rec = t_tuple(
+                                [t_atom(Name)|[Type
+                                               || {_FieldName, Type} <- NewFields1]]),
+                        {Rec, L2, C2}
+                    end
+                end,
+          recur_limit(Fun, D0, L0, RecordType, TypeNames);
+        error ->
+          throw({error, io_lib:format("Unknown record #~w{}\n", [Name])})
+      end;
+    false ->
+       {t_any(), L0, C}
+  end.
+
+get_mod_record([], DeclFields, _S, _D, L, C) ->
+  {{ok, DeclFields}, L, C};
+get_mod_record(ModFields, DeclFields, S, D, L, C) ->
+  DeclFieldsDict = lists:keysort(1, DeclFields),
+  {ModFieldsDict, L1, C1} = build_field_dict(ModFields, S, D, L, C),
+  case get_mod_record_types(DeclFieldsDict, ModFieldsDict, []) of
+    {error, _FieldName} = Error -> {Error, L1, C1};
+    {ok, FinalKeyDict} ->
+      Fields = [lists:keyfind(FieldName, 1, FinalKeyDict)
+             || {FieldName, _, _} <- DeclFields],
+      {{ok, Fields}, L1, C1}
+  end.
+
+build_field_dict(FieldTypes, S, D, L, C) ->
+  build_field_dict(FieldTypes, S, D, L, C, []).
+
+build_field_dict([{type, _, field_type, [{atom, _, Name}, Type]}|Left],
+		 S, D, L, C, Acc) ->
+  {T, L1, C1} = from_form(Type, S, D, L - 1, C),
+  NewAcc = [{Name, Type, T}|Acc],
+  build_field_dict(Left, S, D, L1, C1, NewAcc);
+build_field_dict([], _S, _D, L, C, Acc) ->
+  {lists:keysort(1, Acc), L, C}.
+
+get_mod_record_types([{FieldName, _Abstr, _DeclType}|Left1],
+                     [{FieldName, TypeForm, ModType}|Left2],
+                     Acc) ->
+  get_mod_record_types(Left1, Left2, [{FieldName, TypeForm, ModType}|Acc]);
+get_mod_record_types([{FieldName1, _Abstr, _DeclType} = DT|Left1],
+                     [{FieldName2, _FormType, _ModType}|_] = List2,
+                     Acc) when FieldName1 < FieldName2 ->
+  get_mod_record_types(Left1, List2, [DT|Acc]);
+get_mod_record_types(Left1, [], Acc) ->
+  {ok, lists:keysort(1, Left1++Acc)};
+get_mod_record_types(_, [{FieldName2, _FormType, _ModType}|_], _Acc) ->
+  {error, FieldName2}.
+
+%% It is important to create a limited version of the record type
+%% since nested record types can otherwise easily result in huge
+%% terms.
+fields_from_form([], _S, _D, L, C) ->
+  {[], L, C};
+fields_from_form([{Name, Abstr, _Type}|Tail], S, D, L, C) ->
+  {T, L1, C1} = from_form(Abstr, S, D, L, C),
+  {F, L2, C2} = fields_from_form(Tail, S, D, L1, C1),
+  {[{Name, T}|F], L2, C2}.
+
+list_from_form([], _S, _D, L, C) ->
+  {[], L, C};
+list_from_form([H|Tail], S, D, L, C) ->
+  {H1, L1, C1} = from_form(H, S, D, L - 1, C),
+  {T1, L2, C2} = list_from_form(Tail, S, D, L1, C1),
+  {[H1|T1], L2, C2}.
+
+%% Sorts, combines non-singleton pairs, and applies precendence and
+%% mandatoriness rules.
+map_from_form([], ShdwPs, MKs, Pairs, DefK, DefV) ->
+  verify_possible(MKs, ShdwPs),
+  {promote_to_mand(MKs, Pairs), DefK, DefV};
+map_from_form([{SKey,MNess,Val}|SPairs], ShdwPs0, MKs0, Pairs0, DefK0, DefV0) ->
+  Key = lists:foldl(fun({K,_},S)->t_subtract(S,K)end, SKey, ShdwPs0),
+  ShdwPs = case Key of ?none -> ShdwPs0; _ -> [{Key,Val}|ShdwPs0] end,
+  MKs = case MNess of ?mand -> [SKey|MKs0]; ?opt -> MKs0 end,
+  if MNess =:= ?mand, SKey =:= ?none -> throw(none);
+     true -> ok
+  end,
+  {Pairs, DefK, DefV} =
+    case is_singleton_type(Key) of
+      true ->
+	MNess1 = case Val =:= ?none of true -> ?opt; false -> MNess end,
+	{mapdict_insert({Key,MNess1,Val}, Pairs0), DefK0, DefV0};
+      false ->
+	case Key =:= ?none orelse Val =:= ?none of
+	  true  -> {Pairs0, DefK0,             DefV0};
+	  false -> {Pairs0, t_sup(DefK0, Key), t_sup(DefV0, Val)}
+	end
+    end,
+  map_from_form(SPairs, ShdwPs, MKs, Pairs, DefK, DefV).
+
+%% Verifies that all mandatory keys are possible, throws 'none' otherwise
+verify_possible(MKs, ShdwPs) ->
+  lists:foreach(fun(M) -> verify_possible_1(M, ShdwPs) end, MKs).
+
+verify_possible_1(M, ShdwPs) ->
+  case lists:any(fun({K,_}) -> t_inf(M, K) =/= ?none end, ShdwPs) of
+    true -> ok;
+    false -> throw(none)
+  end.
+
+-spec promote_to_mand([erl_type()], t_map_dict()) -> t_map_dict().
+
+promote_to_mand(_, []) -> [];
+promote_to_mand(MKs, [E={K,_,V}|T]) ->
+  [case lists:any(fun(M) -> t_is_equal(K,M) end, MKs) of
+     true -> {K, ?mand, V};
+     false -> E
+   end|promote_to_mand(MKs, T)].
+
+-define(RECUR_EXPAND_LIMIT, 10).
+-define(RECUR_EXPAND_DEPTH, 2).
+
+%% If more of the limited resources is spent on the non-recursive
+%% forms, more warnings are found. And the analysis is also a bit
+%% faster.
+%%
+%% Setting REC_TYPE_LIMIT to 1 would work also work well.
+
+recur_limit(Fun, D, L, _, _) when L =< ?RECUR_EXPAND_DEPTH,
+                                  D =< ?RECUR_EXPAND_LIMIT ->
+  Fun(D, L);
+recur_limit(Fun, D, L, TypeName, TypeNames) ->
+  case is_recursive(TypeName, TypeNames) of
+    true ->
+      {T, L1, C1} = Fun(?RECUR_EXPAND_DEPTH, ?RECUR_EXPAND_LIMIT),
+      {T, L - L1, C1};
+    false ->
+      Fun(D, L)
+  end.
+
+-spec t_check_record_fields(parse_form(), sets:set(mfa()), site(),
+                            mod_records(), var_table(), cache()) -> cache().
+
+t_check_record_fields(Form, ExpTypes, Site, RecDict, VarTable, Cache) ->
+  State = #from_form{site   = Site,
+                     xtypes = ExpTypes,
+                     mrecs  = RecDict,
+                     vtab   = VarTable,
+                     tnames = []},
+  check_record_fields(Form, State, Cache).
+
+-spec check_record_fields(parse_form(), #from_form{}, cache()) -> cache().
+
+%% If there is something wrong with parse_form()
+%% throw({error, io_lib:chars()} is called.
+
+check_record_fields({var, _L, _}, _S, C) -> C;
+check_record_fields({ann_type, _L, [_Var, Type]}, S, C) ->
+  check_record_fields(Type, S, C);
+check_record_fields({paren_type, _L, [Type]}, S, C) ->
+  check_record_fields(Type, S, C);
+check_record_fields({remote_type, _L, [{atom, _, _}, {atom, _, _}, Args]},
+                    S, C) ->
+  list_check_record_fields(Args, S, C);
+check_record_fields({atom, _L, _}, _S, C) -> C;
+check_record_fields({integer, _L, _}, _S, C) -> C;
+check_record_fields({op, _L, _Op, _Arg}, _S, C) -> C;
+check_record_fields({op, _L, _Op, _Arg1, _Arg2}, _S, C) -> C;
+check_record_fields({type, _L, tuple, any}, _S, C) -> C;
+check_record_fields({type, _L, map, any}, _S, C) -> C;
+check_record_fields({type, _L, binary, [_Base, _Unit]}, _S, C) -> C;
+check_record_fields({type, _L, 'fun', [{type, _, any}, Range]}, S, C) ->
+  check_record_fields(Range, S, C);
+check_record_fields({type, _L, range, [_From, _To]}, _S, C) -> C;
+check_record_fields({type, _L, record, [Name|Fields]}, S, C) ->
+  check_record(Name, Fields, S, C);
+check_record_fields({type, _L, _, Args}, S, C) ->
+  list_check_record_fields(Args, S, C);
+check_record_fields({user_type, _L, _Name, Args}, S, C) ->
+  list_check_record_fields(Args, S, C).
+
+check_record({atom, _, Name}, ModFields, S, C) ->
+  #from_form{site = Site, mrecs = MR} = S,
+  M = site_module(Site),
+  {ok, R} = dict:find(M, MR),
+  {ok, DeclFields} = lookup_record(Name, R),
+  case check_fields(Name, ModFields, DeclFields, S, C) of
+    {error, FieldName} ->
+       throw({error, io_lib:format("Illegal declaration of #~w{~w}\n",
+                                   [Name, FieldName])});
+    C1 -> C1
+  end.
+
+check_fields(RecName, [{type, _, field_type, [{atom, _, Name}, Abstr]}|Left],
+             DeclFields, S, C) ->
+  #from_form{site = Site0, xtypes = ET, mrecs = MR, vtab = V} = S,
+  M = site_module(Site0),
+  Site = {record, {M, RecName, length(DeclFields)}},
+  {Type, C1} = t_from_form(Abstr, ET, Site, MR, V, C),
+  {Name, _, DeclType} = lists:keyfind(Name, 1, DeclFields),
+  TypeNoVars = subst_all_vars_to_any(Type),
+  case t_is_subtype(TypeNoVars, DeclType) of
+    false -> {error, Name};
+    true -> check_fields(RecName, Left, DeclFields, S, C1)
+  end;
+check_fields(_RecName, [], _Decl, _S, C) ->
+  C.
+
+list_check_record_fields([], _S, C) ->
+  C;
+list_check_record_fields([H|Tail], S, C) ->
+  C1 = check_record_fields(H, S, C),
+  list_check_record_fields(Tail, S, C1).
+
+site_module({_, {Module, _, _}}) ->
+  Module.
+
+-spec cache__new() -> cache().
+
+cache__new() ->
+  maps:new().
+
+-spec cache_key(module(), atom(), [erl_type()],
+                type_names(), expand_depth()) -> cache_key().
+
+%% If TypeNames is left out from the key, the cache is smaller, and
+%% the form-to-type translation is faster. But it would be a shame if,
+%% for example, any() is used, where a more complex type should be
+%% used. There is also a slight risk of creating unnecessarily big
+%% types.
+
+cache_key(Module, Name, ArgTypes, TypeNames, D) ->
+  {Module, Name, D, ArgTypes, TypeNames}.
+
+-spec cache_find(cache_key(), cache()) ->
+                    {erl_type(), expand_limit()} | 'error'.
+
+cache_find(Key, Cache) ->
+  case maps:find(Key, Cache) of
+    {ok, Value} ->
+      Value;
+    error ->
+      error
+  end.
+
+-spec cache_put(cache_key(), erl_type(), expand_limit(), cache()) -> cache().
+
+cache_put(_Key, _Type, DeltaL, Cache) when DeltaL < 0 ->
+  %% The type is truncated; do not reuse it.
+  Cache;
+cache_put(Key, Type, DeltaL, Cache) ->
+  maps:put(Key, {Type, DeltaL}, Cache).
+
+-spec t_var_names([erl_type()]) -> [atom()].
+
+t_var_names([{var, _, Name}|L]) when L =/= '_' ->
+  [Name|t_var_names(L)];
+t_var_names([]) ->
+  [].
+
+-spec t_form_to_string(parse_form()) -> string().
+
+t_form_to_string({var, _L, '_'}) -> "_";
+t_form_to_string({var, _L, Name}) -> atom_to_list(Name);
+t_form_to_string({atom, _L, Atom}) -> 
+  io_lib:write_string(atom_to_list(Atom), $'); % To quote or not to quote... '
+t_form_to_string({integer, _L, Int}) -> integer_to_list(Int);
+t_form_to_string({op, _L, _Op, _Arg} = Op) ->
+  case erl_eval:partial_eval(Op) of
+    {integer, _, _} = Int -> t_form_to_string(Int);
+    _ -> io_lib:format("Badly formed type ~w", [Op])
+  end;
+t_form_to_string({op, _L, _Op, _Arg1, _Arg2} = Op) ->
+  case erl_eval:partial_eval(Op) of
+    {integer, _, _} = Int -> t_form_to_string(Int);
+    _ -> io_lib:format("Badly formed type ~w", [Op])
+  end;
+t_form_to_string({ann_type, _L, [Var, Type]}) ->
+  t_form_to_string(Var) ++ "::" ++ t_form_to_string(Type);
+t_form_to_string({paren_type, _L, [Type]}) ->
+  flat_format("(~s)", [t_form_to_string(Type)]);
+t_form_to_string({remote_type, _L, [{atom, _, Mod}, {atom, _, Name}, Args]}) ->
+  ArgString = "(" ++ string:join(t_form_to_string_list(Args), ",") ++ ")",
+  flat_format("~w:~w", [Mod, Name]) ++ ArgString;
+t_form_to_string({type, _L, arity, []}) -> "arity()";
+t_form_to_string({type, _L, binary, []}) -> "binary()";
+t_form_to_string({type, _L, binary, [Base, Unit]} = Type) ->
+  case {erl_eval:partial_eval(Base), erl_eval:partial_eval(Unit)} of
+    {{integer, _, B}, {integer, _, U}} ->
+      %% the following mirrors the clauses of t_to_string/2
+      case {U, B} of
+	{0, 0} -> "<<>>";
+	{8, 0} -> "binary()";
+	{1, 0} -> "bitstring()";
+	{0, B} -> flat_format("<<_:~w>>", [B]);
+	{U, 0} -> flat_format("<<_:_*~w>>", [U]);
+	{U, B} -> flat_format("<<_:~w,_:_*~w>>", [B, U])
+      end;
+    _ -> io_lib:format("Badly formed bitstr type ~w", [Type])
+  end;
+t_form_to_string({type, _L, bitstring, []}) -> "bitstring()";
+t_form_to_string({type, _L, 'fun', []}) -> "fun()";
+t_form_to_string({type, _L, 'fun', [{type, _, any}, Range]}) ->
+  "fun(...) -> " ++ t_form_to_string(Range);
+t_form_to_string({type, _L, 'fun', [{type, _, product, Domain}, Range]}) ->
+  "fun((" ++ string:join(t_form_to_string_list(Domain), ",") ++ ") -> "
+    ++ t_form_to_string(Range) ++ ")";
+t_form_to_string({type, _L, iodata, []}) -> "iodata()";
+t_form_to_string({type, _L, iolist, []}) -> "iolist()";
+t_form_to_string({type, _L, list, [Type]}) -> 
+  "[" ++ t_form_to_string(Type) ++ "]";
+t_form_to_string({type, _L, map, any}) -> "map()";
+t_form_to_string({type, _L, map, Args}) ->
+  "#{" ++ string:join(t_form_to_string_list(Args), ",") ++ "}";
+t_form_to_string({type, _L, map_field_assoc, [Key, Val]}) ->
+  t_form_to_string(Key) ++ "=>" ++ t_form_to_string(Val);
+t_form_to_string({type, _L, map_field_exact, [Key, Val]}) ->
+  t_form_to_string(Key) ++ ":=" ++ t_form_to_string(Val);
+t_form_to_string({type, _L, mfa, []}) -> "mfa()";
+t_form_to_string({type, _L, module, []}) -> "module()";
+t_form_to_string({type, _L, node, []}) -> "node()";
+t_form_to_string({type, _L, nonempty_list, [Type]}) ->
+  "[" ++ t_form_to_string(Type) ++ ",...]";
+t_form_to_string({type, _L, nonempty_string, []}) -> "nonempty_string()";
+t_form_to_string({type, _L, product, Elements}) ->
+  "<" ++ string:join(t_form_to_string_list(Elements), ",") ++ ">";
+t_form_to_string({type, _L, range, [From, To]} = Type) ->
+  case {erl_eval:partial_eval(From), erl_eval:partial_eval(To)} of
+    {{integer, _, FromVal}, {integer, _, ToVal}} ->
+      flat_format("~w..~w", [FromVal, ToVal]);
+    _ -> flat_format("Badly formed type ~w",[Type])
+  end;
+t_form_to_string({type, _L, record, [{atom, _, Name}]}) ->
+  flat_format("#~w{}", [Name]);
+t_form_to_string({type, _L, record, [{atom, _, Name}|Fields]}) ->
+  FieldString = string:join(t_form_to_string_list(Fields), ","),
+  flat_format("#~w{~s}", [Name, FieldString]);
+t_form_to_string({type, _L, field_type, [{atom, _, Name}, Type]}) ->
+  flat_format("~w::~s", [Name, t_form_to_string(Type)]);
+t_form_to_string({type, _L, term, []}) -> "term()";
+t_form_to_string({type, _L, timeout, []}) -> "timeout()";
+t_form_to_string({type, _L, tuple, any}) -> "tuple()";
+t_form_to_string({type, _L, tuple, Args}) ->
+  "{" ++ string:join(t_form_to_string_list(Args), ",") ++ "}";
+t_form_to_string({type, _L, union, Args}) ->
+  string:join(t_form_to_string_list(Args), " | ");
+t_form_to_string({type, _L, Name, []} = T) ->
+   try
+     M = mod,
+     D0 = dict:new(),
+     MR = dict:from_list([{M, D0}]),
+     Site = {type, {M,Name,0}},
+     V = var_table__new(),
+     C = cache__new(),
+     State = #from_form{site   = Site,
+                        xtypes = sets:new(),
+                        mrecs  = MR,
+                        vtab   = V,
+                        tnames = []},
+     {T1, _, _} = from_form(T, State, _Deep=1000, _ALot=1000000, C),
+     t_to_string(T1)
+  catch throw:{error, _} -> atom_to_string(Name) ++ "()"
+  end;
+t_form_to_string({user_type, _L, Name, List}) ->
+  flat_format("~w(~s)",
+              [Name, string:join(t_form_to_string_list(List), ",")]);
+t_form_to_string({type, L, Name, List}) ->
+  %% Compatibility: modules compiled before Erlang/OTP 18.0.
+  t_form_to_string({user_type, L, Name, List}).
+
+t_form_to_string_list(List) ->
+  t_form_to_string_list(List, []).
+
+t_form_to_string_list([H|T], Acc) ->
+  t_form_to_string_list(T, [t_form_to_string(H)|Acc]);
+t_form_to_string_list([], Acc) ->
+  lists:reverse(Acc).
+
+-spec atom_to_string(atom()) -> string().
+
+atom_to_string(Atom) ->
+  flat_format("~w", [Atom]).
+
+%%=============================================================================
+%% 
+%% Utilities
+%%
+%%=============================================================================
+
+-spec any_none([erl_type()]) -> boolean().
+
+any_none([?none|_Left]) -> true;
+any_none([_|Left]) -> any_none(Left);
+any_none([]) -> false.
+
+-spec any_none_or_unit([erl_type()]) -> boolean().
+
+any_none_or_unit([?none|_]) -> true;
+any_none_or_unit([?unit|_]) -> true;
+any_none_or_unit([_|Left]) -> any_none_or_unit(Left);
+any_none_or_unit([]) -> false.
+
+-spec is_erl_type(any()) -> boolean().
+
+is_erl_type(?any) -> true;
+is_erl_type(?none) -> true;
+is_erl_type(?unit) -> true;
+is_erl_type(#c{}) -> true;
+is_erl_type(_) -> false.
+
+-spec lookup_record(atom(), type_table()) ->
+        'error' | {'ok', [{atom(), parse_form(), erl_type()}]}.
+
+lookup_record(Tag, RecDict) when is_atom(Tag) ->
+  case dict:find({record, Tag}, RecDict) of
+    {ok, {_FileLine, [{_Arity, Fields}]}} ->
+      {ok, Fields};
+    {ok, {_FileLine, List}} when is_list(List) ->
+      %% This will have to do, since we do not know which record we
+      %% are looking for.
+      error;
+    error ->
+      error
+  end.
+
+-spec lookup_record(atom(), arity(), type_table()) ->
+        'error' | {'ok', [{atom(), parse_form(), erl_type()}]}.
+
+lookup_record(Tag, Arity, RecDict) when is_atom(Tag) ->
+  case dict:find({record, Tag}, RecDict) of
+    {ok, {_FileLine, [{Arity, Fields}]}} -> {ok, Fields};
+    {ok, {_FileLine, OrdDict}} -> orddict:find(Arity, OrdDict);
+    error -> error
+  end.
+
+-spec lookup_type(_, _, _) -> {'type' | 'opaque', type_value()} | 'error'.
+lookup_type(Name, Arity, RecDict) ->
+  case dict:find({type, Name, Arity}, RecDict) of
+    error ->
+      case dict:find({opaque, Name, Arity}, RecDict) of
+	error -> error;
+	{ok, Found} -> {opaque, Found}
+      end;
+    {ok, Found} -> {type, Found}
+  end.
+
+-spec type_is_defined('type' | 'opaque', atom(), arity(), type_table()) ->
+        boolean().
+
+type_is_defined(TypeOrOpaque, Name, Arity, RecDict) ->
+  dict:is_key({TypeOrOpaque, Name, Arity}, RecDict).
+
+cannot_have_opaque(Type, TypeName, TypeNames) ->
+  t_is_none(Type) orelse is_recursive(TypeName, TypeNames).
+
+is_recursive(TypeName, TypeNames) ->
+  lists:member(TypeName, TypeNames).
+
+can_unfold_more(TypeName, TypeNames) ->
+  Fun = fun(E, Acc) -> case E of TypeName -> Acc + 1; _ -> Acc end end,
+  lists:foldl(Fun, 0, TypeNames) < ?REC_TYPE_LIMIT.
+
+-spec do_opaque(erl_type(), opaques(), fun((_) -> T)) -> T.
+
+%% Probably a little faster than calling t_unopaque/2.
+%% Unions that are due to opaque types are unopaqued.
+do_opaque(?opaque(_) = Type, Opaques, Pred) ->
+  case Opaques =:= 'universe' orelse is_opaque_type(Type, Opaques) of
+    true -> do_opaque(t_opaque_structure(Type), Opaques, Pred);
+    false -> Pred(Type)
+  end;
+do_opaque(?union(List) = Type, Opaques, Pred) ->
+  [A,B,F,I,L,N,T,M,O,Map] = List,
+  if O =:= ?none -> Pred(Type);
+    true ->
+      case Opaques =:= 'universe' orelse is_opaque_type(O, Opaques) of
+        true ->
+          S = t_opaque_structure(O),
+          do_opaque(t_sup([A,B,F,I,L,N,T,M,S,Map]), Opaques, Pred);
+        false -> Pred(Type)
+      end
+  end;
+do_opaque(Type, _Opaques, Pred) ->
+  Pred(Type).
+
+map_all_values(?map(Pairs,_,DefV)) ->
+  [DefV|[V || {V, _, _} <- Pairs]].
+
+map_all_keys(?map(Pairs,DefK,_)) ->
+  [DefK|[K || {_, _, K} <- Pairs]].
+
+map_all_types(M) ->
+  map_all_keys(M) ++ map_all_values(M).
+
+%% Tests if a type has exactly one possible value.
+-spec t_is_singleton(erl_type()) -> boolean().
+
+t_is_singleton(Type) ->
+  t_is_singleton(Type, 'universe').
+
+-spec t_is_singleton(erl_type(), opaques()) -> boolean().
+
+t_is_singleton(Type, Opaques) ->
+  do_opaque(Type, Opaques, fun is_singleton_type/1).
+
+%% Incomplete; not all representable singleton types are included.
+is_singleton_type(?nil) -> true;
+is_singleton_type(?atom(?any)) -> false;
+is_singleton_type(?atom(Set)) ->
+  ordsets:size(Set) =:= 1;
+is_singleton_type(?int_range(V, V)) -> true;
+is_singleton_type(?int_set(Set)) ->
+  ordsets:size(Set) =:= 1;
+is_singleton_type(?tuple(Types, Arity, _)) when is_integer(Arity) ->
+  lists:all(fun is_singleton_type/1, Types);
+is_singleton_type(?tuple_set([{Arity, [OnlyTuple]}])) when is_integer(Arity) ->
+  is_singleton_type(OnlyTuple);
+is_singleton_type(?map(Pairs, ?none, ?none)) ->
+  lists:all(fun({_,MNess,V}) -> MNess =:= ?mand andalso is_singleton_type(V)
+	    end, Pairs);
+is_singleton_type(_) ->
+  false.
+
+%% Returns the only possible value of a singleton type.
+-spec t_singleton_to_term(erl_type(), opaques()) -> term().
+
+t_singleton_to_term(Type, Opaques) ->
+  do_opaque(Type, Opaques, fun singleton_type_to_term/1).
+
+singleton_type_to_term(?nil) -> [];
+singleton_type_to_term(?atom(Set)) when Set =/= ?any ->
+  case ordsets:size(Set) of
+    1 -> hd(ordsets:to_list(Set));
+    _ -> error(badarg)
+  end;
+singleton_type_to_term(?int_range(V, V)) -> V;
+singleton_type_to_term(?int_set(Set)) ->
+  case ordsets:size(Set) of
+    1 -> hd(ordsets:to_list(Set));
+    _ -> error(badarg)
+  end;
+singleton_type_to_term(?tuple(Types, Arity, _)) when is_integer(Arity) ->
+  lists:map(fun singleton_type_to_term/1, Types);
+singleton_type_to_term(?tuple_set([{Arity, [OnlyTuple]}]))
+  when is_integer(Arity) ->
+  singleton_type_to_term(OnlyTuple);
+singleton_type_to_term(?map(Pairs, ?none, ?none)) ->
+  maps:from_list([{singleton_type_to_term(K), singleton_type_to_term(V)}
+		  || {K,?mand,V} <- Pairs]).
+
+%% -----------------------------------
+%% Set
+%%
+
+set_singleton(Element) ->
+  ordsets:from_list([Element]).
+
+set_is_singleton(Element, Set) ->
+  set_singleton(Element) =:= Set.
+  
+set_is_element(Element, Set) ->
+  ordsets:is_element(Element, Set).
+
+set_union(?any, _) -> ?any;
+set_union(_, ?any) -> ?any;
+set_union(S1, S2)  -> 
+  case ordsets:union(S1, S2) of
+    S when length(S) =< ?SET_LIMIT -> S;
+    _ -> ?any
+  end.
+
+%% The intersection and subtraction can return ?none. 
+%% This should always be handled right away since ?none is not a valid set.
+%% However, ?any is considered a valid set.
+
+set_intersection(?any, S) -> S;
+set_intersection(S, ?any) -> S;
+set_intersection(S1, S2)  -> 
+  case ordsets:intersection(S1, S2) of
+    [] -> ?none;
+    S -> S
+  end.      
+
+set_subtract(_, ?any) -> ?none;
+set_subtract(?any, _) -> ?any;
+set_subtract(S1, S2) ->
+  case ordsets:subtract(S1, S2) of
+    [] -> ?none;
+    S -> S
+  end.
+
+set_from_list(List) ->
+  case length(List) of
+    L when L =< ?SET_LIMIT -> ordsets:from_list(List);
+    L when L > ?SET_LIMIT -> ?any
+  end.
+
+set_to_list(Set) ->
+  ordsets:to_list(Set).
+
+set_filter(Fun, Set) ->
+  case ordsets:filter(Fun, Set) of
+    [] -> ?none;
+    NewSet -> NewSet
+  end.
+
+set_size(Set) ->
+  ordsets:size(Set).
+
+set_to_string(Set) ->
+  L = [case is_atom(X) of
+	 true -> io_lib:write_string(atom_to_list(X), $'); % stupid emacs '
+	 false -> flat_format("~w", [X])
+       end || X <- set_to_list(Set)],
+  string:join(L, " | ").
+
+set_min([H|_]) -> H.
+
+set_max(Set) ->
+  hd(lists:reverse(Set)).
+
+flat_format(F, S) ->
+  lists:flatten(io_lib:format(F, S)).
+
+%%=============================================================================
+%% 
+%% Utilities for the binary type
+%%
+%%=============================================================================
+
+-spec gcd(integer(), integer()) -> integer().
+
+gcd(A, B) when B > A ->
+  gcd1(B, A);
+gcd(A, B) ->
+  gcd1(A, B).
+
+-spec gcd1(integer(), integer()) -> integer().
+
+gcd1(A, 0) -> A;
+gcd1(A, B) ->
+  case A rem B of
+    0 -> B;
+    X -> gcd1(B, X)
+  end.
+
+-spec bitstr_concat(erl_type(), erl_type()) -> erl_type().
+
+bitstr_concat(?none, _) -> ?none;
+bitstr_concat(_, ?none) -> ?none;
+bitstr_concat(?bitstr(U1, B1), ?bitstr(U2, B2)) ->
+  t_bitstr(gcd(U1, U2), B1+B2).
+
+-spec bitstr_match(erl_type(), erl_type()) -> erl_type().
+
+bitstr_match(?none, _) -> ?none;
+bitstr_match(_, ?none) -> ?none;
+bitstr_match(?bitstr(0, B1), ?bitstr(0, B2)) when B1 =< B2 ->
+  t_bitstr(0, B2-B1);
+bitstr_match(?bitstr(0, _B1), ?bitstr(0, _B2)) ->
+  ?none;
+bitstr_match(?bitstr(0, B1), ?bitstr(U2, B2)) when B1 =< B2 ->
+  t_bitstr(U2, B2-B1);
+bitstr_match(?bitstr(0, B1), ?bitstr(U2, B2))  ->
+  t_bitstr(U2, handle_base(U2, B2-B1));
+bitstr_match(?bitstr(_, B1), ?bitstr(0, B2)) when B1 > B2 ->
+  ?none;
+bitstr_match(?bitstr(U1, B1), ?bitstr(U2, B2)) ->
+  GCD = gcd(U1, U2),
+  t_bitstr(GCD, handle_base(GCD, B2-B1)).
+
+-spec handle_base(integer(), integer()) -> integer().
+
+handle_base(Unit, Pos) when Pos >= 0 ->
+  Pos rem Unit;
+handle_base(Unit, Neg) ->
+  (Unit+(Neg rem Unit)) rem Unit.
+  
+family(L) ->
+  R = sofs:relation(L),
+  F = sofs:relation_to_family(R),
+  sofs:to_external(F).
+
+%%=============================================================================
+%%
+%% Interface functions for abstract data types defined in this module
+%%
+%%=============================================================================
+
+-spec var_table__new() -> var_table().
+
+var_table__new() ->
+  maps:new().
+
+%%=============================================================================
+%% Consistency-testing function(s) below
+%%=============================================================================
+
+-ifdef(DO_ERL_TYPES_TEST).		  
+
+test() ->
+  Atom1  = t_atom(),
+  Atom2  = t_atom(foo),
+  Atom3  = t_atom(bar),
+  true   = t_is_atom(Atom2),
+
+  True   = t_atom(true),
+  False  = t_atom(false),
+  Bool   = t_boolean(),
+  true   = t_is_boolean(True),
+  true   = t_is_boolean(Bool),
+  false  = t_is_boolean(Atom1),
+
+  Binary = t_binary(),
+  true   = t_is_binary(Binary),
+
+  Bitstr = t_bitstr(),
+  true   = t_is_bitstr(Bitstr),
+  
+  Bitstr1 = t_bitstr(7, 3),
+  true   = t_is_bitstr(Bitstr1),
+  false  = t_is_binary(Bitstr1),
+
+  Bitstr2 = t_bitstr(16, 8),
+  true   = t_is_bitstr(Bitstr2),
+  true   = t_is_binary(Bitstr2),
+  
+  ?bitstr(8, 16) = t_subtract(t_bitstr(4, 12), t_bitstr(8, 12)),
+  ?bitstr(8, 16) = t_subtract(t_bitstr(4, 12), t_bitstr(8, 12)),
+
+  Int1   = t_integer(),
+  Int2   = t_integer(1),
+  Int3   = t_integer(16#ffffffff),
+  true   = t_is_integer(Int2),
+  true   = t_is_byte(Int2),
+  false  = t_is_byte(Int3),
+  false  = t_is_byte(t_from_range(-1, 1)),
+  true   = t_is_byte(t_from_range(1, ?MAX_BYTE)),
+  
+  Tuple1 = t_tuple(),
+  Tuple2 = t_tuple(3),
+  Tuple3 = t_tuple([Atom1, Int1]),
+  Tuple4 = t_tuple([Tuple1, Tuple2]),
+  Tuple5 = t_tuple([Tuple3, Tuple4]),
+  Tuple6 = t_limit(Tuple5, 2),
+  Tuple7 = t_limit(Tuple5, 3),
+  true   = t_is_tuple(Tuple1),  
+  
+  Port   = t_port(),
+  Pid    = t_pid(),
+  Ref    = t_reference(),
+  Identifier = t_identifier(),
+  false  = t_is_reference(Port),
+  true   = t_is_identifier(Port),
+
+  Function1 = t_fun(),
+  Function2 = t_fun(Pid),
+  Function3 = t_fun([], Pid),
+  Function4 = t_fun([Port, Pid], Pid),
+  Function5 = t_fun([Pid, Atom1], Int2),
+  true      = t_is_fun(Function3),  
+
+  List1 = t_list(),
+  List2 = t_list(t_boolean()),
+  List3 = t_cons(t_boolean(), List2),
+  List4 = t_cons(t_boolean(), t_atom()),
+  List5 = t_cons(t_boolean(), t_nil()),
+  List6 = t_cons_tl(List5),
+  List7 = t_sup(List4, List5),
+  List8 = t_inf(List7, t_list()),
+  List9 = t_cons(),
+  List10 = t_cons_tl(List9),
+  true  = t_is_boolean(t_cons_hd(List5)),
+  true  = t_is_list(List5),
+  false = t_is_list(List4),
+
+  Product1 = t_product([Atom1, Atom2]),
+  Product2 = t_product([Atom3, Atom1]),
+  Product3 = t_product([Atom3, Atom2]),
+
+  Union1 = t_sup(Atom2, Atom3),
+  Union2 = t_sup(Tuple2, Tuple3),
+  Union3 = t_sup(Int2, Atom3),
+  Union4 = t_sup(Port, Pid),
+  Union5 = t_sup(Union4, Int1),
+  Union6 = t_sup(Function1, Function2),
+  Union7 = t_sup(Function4, Function5),
+  Union8 = t_sup(True, False),
+  true   = t_is_boolean(Union8),
+  Union9 = t_sup(Int2, t_integer(2)),
+  true   = t_is_byte(Union9),
+  Union10 = t_sup(t_tuple([t_atom(true), ?any]), 
+		  t_tuple([t_atom(false), ?any])),
+  
+  ?any   = t_sup(Product3, Function5),
+
+  Atom3  = t_inf(Union3, Atom1),
+  Union2 = t_inf(Union2, Tuple1),
+  Int2   = t_inf(Int1, Union3),
+  Union4 = t_inf(Union4, Identifier),
+  Port   = t_inf(Union5, Port),
+  Function4 = t_inf(Union7, Function4),
+  ?none  = t_inf(Product2, Atom1),
+  Product3 = t_inf(Product1, Product2),
+  Function5 = t_inf(Union7, Function5),
+  true   = t_is_byte(t_inf(Union9, t_number())),
+  true   = t_is_char(t_inf(Union9, t_number())),
+
+  io:format("3? ~p ~n", [?int_set([3])]),
+
+  RecDict = dict:store({foo, 2}, [bar, baz], dict:new()),
+  Record1 = t_from_term({foo, [1,2], {1,2,3}}),
+  
+  Types = [
+	   Atom1,
+	   Atom2,
+	   Atom3,
+	   Binary,
+	   Int1,
+	   Int2,
+	   Tuple1,
+	   Tuple2,
+	   Tuple3,
+	   Tuple4,
+	   Tuple5,
+	   Tuple6,
+	   Tuple7,
+	   Ref,
+	   Port,
+	   Pid,
+	   Identifier,
+	   List1,
+	   List2,
+	   List3,
+	   List4,
+	   List5,
+	   List6,
+	   List7,
+	   List8,
+	   List9,
+	   List10,
+	   Function1,
+	   Function2,
+	   Function3,
+	   Function4,
+	   Function5,
+	   Product1,
+	   Product2,
+	   Record1,
+	   Union1,
+	   Union2,
+	   Union3,
+	   Union4,
+	   Union5,
+	   Union6,
+	   Union7,
+	   Union8,
+	   Union10,
+	   t_inf(Union10, t_tuple([t_atom(true), t_integer()]))
+	  ],
+  io:format("~p\n", [[t_to_string(X, RecDict) || X <- Types]]).
+       
+-endif.