From 351987be44e11e6eb9e5841adb197ec8e49bc49d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn-Egil=20Dahlberg?= <egil@erlang.org>
Date: Wed, 6 Nov 2013 09:01:30 +0100
Subject: dialyzer,hipe,stdlib: Add Maps understanding to Dialyzer

---
 lib/dialyzer/src/dialyzer_cl.erl       |   2 +-
 lib/dialyzer/src/dialyzer_dataflow.erl |  56 ++++++++++++++++-
 lib/dialyzer/src/dialyzer_dep.erl      |  12 ++++
 lib/dialyzer/src/dialyzer_typesig.erl  |  34 ++++++++++-
 lib/hipe/cerl/cerl_prettypr.erl        |  29 ++++++++-
 lib/hipe/cerl/erl_bif_types.erl        |  17 +++++-
 lib/hipe/cerl/erl_types.erl            | 108 ++++++++++++++++++++++++---------
 lib/stdlib/src/erl_lint.erl            |   8 +++
 lib/stdlib/src/erl_parse.yrl           |   9 +++
 9 files changed, 239 insertions(+), 36 deletions(-)

diff --git a/lib/dialyzer/src/dialyzer_cl.erl b/lib/dialyzer/src/dialyzer_cl.erl
index a7be6e0d05..cda801bf6c 100644
--- a/lib/dialyzer/src/dialyzer_cl.erl
+++ b/lib/dialyzer/src/dialyzer_cl.erl
@@ -603,7 +603,7 @@ cl_loop(State, LogCache) ->
       Msg = failed_anal_msg(Reason, LogCache),
       cl_error(State, Msg);
     {'EXIT', BackendPid, Reason} when Reason =/= 'normal' ->
-      Msg = failed_anal_msg(io_lib:format("~P", [Reason, 12]), LogCache),
+      Msg = failed_anal_msg(io_lib:format("~p", [Reason]), LogCache),
       cl_error(State, Msg);
     _Other ->
       %% io:format("Received ~p\n", [_Other]),
diff --git a/lib/dialyzer/src/dialyzer_dataflow.erl b/lib/dialyzer/src/dialyzer_dataflow.erl
index 3591d5be8e..4d614320c2 100644
--- a/lib/dialyzer/src/dialyzer_dataflow.erl
+++ b/lib/dialyzer/src/dialyzer_dataflow.erl
@@ -67,7 +67,9 @@
          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_unit/0, t_unopaque/2,
+	 t_map/1
+     ]).
 
 %%-define(DEBUG, true).
 %%-define(DEBUG_PP, true).
@@ -305,6 +307,12 @@ traverse(Tree, Map, State) ->
       handle_try(Tree, Map, State);
     tuple ->
       handle_tuple(Tree, Map, State);
+    map ->
+      handle_map(Tree, Map, State);
+    map_pair_assoc ->
+      handle_map_pair_assoc(Tree, Map, State);
+    map_pair_exact ->
+      handle_map_pair_exact(Tree, Map, State);
     values ->
       Elements = cerl:values_es(Tree),
       {State1, Map1, EsType} = traverse_list(Elements, Map, State),
@@ -657,7 +665,8 @@ is_opaque_type_test_problem(Fun, Args, ArgTypes, State) ->
 			 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_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);
@@ -1054,6 +1063,23 @@ handle_try(Tree, Map, State) ->
 
 %%----------------------------------------
 
+handle_map(Tree,Map,State) ->
+    Pairs = cerl:map_es(Tree),
+    {State1, Map1, TypePairs} = traverse_list(Pairs,Map,State),
+    {State1, Map1, t_map(TypePairs)}.
+
+handle_map_pair_assoc(Tree,Map,State) ->
+  Elements = cerl:map_pair_assoc_es(Tree),
+  {State1, Map1, [K,V]} = traverse_list(Elements,Map,State),
+  {State1, Map1, {K,V}}.
+
+handle_map_pair_exact(Tree,Map,State) ->
+  Elements = cerl:map_pair_exact_es(Tree),
+  {State1, Map1, [K,V]} = traverse_list(Elements,Map,State),
+  {State1, Map1, {K,V}}.
+
+%%----------------------------------------
+
 handle_tuple(Tree, Map, State) ->
   Elements = cerl:tuple_es(Tree),
   {State1, Map1, EsType} = traverse_list(Elements, Map, State),
@@ -1431,6 +1457,30 @@ bind_pat_vars([Pat|PatLeft], [Type|TypeLeft], Acc, Map, State, Rev) ->
 	    bind_opaque_pats(Literal, Type, Pat, Map, State, Rev);
 	  false -> {Map, Literal}
 	end;
+      map ->
+	  {Map, t_map([])};
+%	Pairs = [ cerl:map_pair_es(Pair) || Pair <- cerl:map_es(Pat) ],
+%	MapType = t_inf(t_map([]), Type),
+%	case t_is_none(MapType) of
+%	    true ->
+%		bind_opaque_pats(MapType, Type, Pat, Map, State, Rev);
+%	    false ->
+%		MapJ = join_maps_begin(Map),
+%		Results = case Rev of
+%		    true ->
+%			[bind_pat_vars_reverse(Pair, [t_any(),t_any()], [], MapJ, State) || Pair <- Pairs];
+%		    false ->
+%			[bind_pat_vars(Pair, [t_any(),t_any()], [], MapJ, State) || Pair <- Pairs]
+%		end,
+%		case [M || {M, _} <- Results, M =/= error] of
+%		    [] -> bind_error([Pat], MapType, t_none(), bind);
+%		    Maps ->
+%			Map1 = join_maps_end(Maps, MapJ),
+%			_PairTypes = [{Ktype,Vtype} || {M, [Ktype,Vtype]} <- Results, M =/= error],
+%			% add t_sup
+%			{Map1, t_map([])}
+%		end
+%	end;
       tuple ->
 	Es = cerl:tuple_es(Pat),
 	{TypedRecord, Prototype} =
@@ -1641,6 +1691,8 @@ bind_guard(Guard, Map, Env, Eval, State) ->
       Es0 = cerl:tuple_es(Guard),
       {Map1, Es} = bind_guard_list(Es0, Map, Env, dont_know, State),
       {Map1, t_tuple(Es)};
+    map ->
+      {Map, t_map([])};
     'let' ->
       Arg = cerl:let_arg(Guard),
       [Var] = cerl:let_vars(Guard),
diff --git a/lib/dialyzer/src/dialyzer_dep.erl b/lib/dialyzer/src/dialyzer_dep.erl
index 05f81399fb..12833b49c7 100644
--- a/lib/dialyzer/src/dialyzer_dep.erl
+++ b/lib/dialyzer/src/dialyzer_dep.erl
@@ -182,6 +182,18 @@ traverse(Tree, Out, State, CurrentFun) ->
       Args = cerl:tuple_es(Tree),
       {List, State1} = traverse_list(Args, Out, State, CurrentFun),
       {merge_outs(List), State1};
+    map ->
+      Args = cerl:map_es(Tree),
+      {List, State1} = traverse_list(Args, Out, State, CurrentFun),
+      {merge_outs(List), State1};
+    map_pair_assoc ->
+      Args = cerl:map_pair_assoc_es(Tree),
+      {List, State1} = traverse_list(Args, Out, State, CurrentFun),
+      {merge_outs(List), State1};
+    map_pair_exact ->
+      Args = cerl:map_pair_exact_es(Tree),
+      {List, State1} = traverse_list(Args, Out, State, CurrentFun),
+      {merge_outs(List), State1};
     values ->      
       traverse_list(cerl:values_es(Tree), Out, State, CurrentFun);
     var ->
diff --git a/lib/dialyzer/src/dialyzer_typesig.erl b/lib/dialyzer/src/dialyzer_typesig.erl
index db7875704a..4e18e9c7d2 100644
--- a/lib/dialyzer/src/dialyzer_typesig.erl
+++ b/lib/dialyzer/src/dialyzer_typesig.erl
@@ -55,7 +55,9 @@
 	 t_subst/2,
 	 t_timeout/0, t_tuple/0, t_tuple/1,
          t_var/1, t_var_name/1,
-	 t_none/0, t_unit/0]).
+	 t_none/0, t_unit/0,
+	 t_map/1
+     ]).
 
 -include("dialyzer.hrl").
 
@@ -470,6 +472,33 @@ traverse(Tree, DefinedVars, State) ->
           end;
 	[] -> {State2, TupleType}
       end;
+    map ->
+	{State, t_map([])};
+%      Pairs = cerl:map_es(Tree),
+%      {State1, EVars} = traverse_list(Pairs, DefinedVars, State),
+%      case cerl:is_literal(cerl:fold_literal(Tree)) of
+%	  true ->
+%	    %% We do not need to do anything more here.
+%	    {State, t_map([])};
+%	  false ->
+%	    Fun = fun(Var, AccState) ->
+%		      case t_has_var(Var) of
+%			true ->
+%			  {AccState1, NewVar} = state__mk_var(AccState),
+%			  {NewVar,
+%			   state__store_conj(Var, eq, NewVar, AccState1)};
+%			false ->
+%			  {Var, AccState}
+%		      end
+%		  end,
+%	    {_NewEvars, State2} = lists:mapfoldl(Fun, State1, EVars),
+%	    {State2, t_map([])}
+%	end;
+%    map_pair_assoc ->
+%	[K,V] = cerl:map_pair_assoc_es(Tree),
+%	{State1,_} = traverse(K,DefinedVars,State),
+%	{State2,_} = traverse(V,DefinedVars,State),
+%	{_,State2};
     values ->
       %% We can get into trouble when unifying products that have the
       %% same element appearing several times. Handle these cases by
@@ -1037,6 +1066,9 @@ get_safe_underapprox_1([Pat|Left], Acc, Map) ->
       {Ts, Map1} = get_safe_underapprox_1(Es, [], Map),
       Type = t_tuple(Ts),
       get_safe_underapprox_1(Left, [Type|Acc], Map1);
+    map ->
+      %% TODO: Can maybe do something here
+      throw(dont_know);
     values ->
       Es = cerl:values_es(Pat),
       {Ts, Map1} = get_safe_underapprox_1(Es, [], Map),
diff --git a/lib/hipe/cerl/cerl_prettypr.erl b/lib/hipe/cerl/cerl_prettypr.erl
index fba9a48cda..60926e16e1 100644
--- a/lib/hipe/cerl/cerl_prettypr.erl
+++ b/lib/hipe/cerl/cerl_prettypr.erl
@@ -62,7 +62,10 @@
 	       receive_action/1, receive_clauses/1, receive_timeout/1,
 	       seq_arg/1, seq_body/1, string_lit/1, try_arg/1,
 	       try_body/1, try_vars/1, try_evars/1, try_handler/1,
-	       tuple_es/1, type/1, values_es/1, var_name/1]).
+	       tuple_es/1, type/1, values_es/1, var_name/1,
+	   
+	       map_es/1, map_pair_assoc_es/1, map_pair_exact_es/1
+	   ]).
 
 -define(PAPER, 76).
 -define(RIBBON, 45).
@@ -424,6 +427,12 @@ lay_1(Node, Ctxt) ->
 	    lay_cons(Node, Ctxt);
 	tuple ->
 	    lay_tuple(Node, Ctxt);
+	map ->
+	    lay_map(Node, Ctxt);
+	map_pair_assoc ->
+	    lay_map_pair_assoc(Node, Ctxt);
+	map_pair_exact ->
+	    lay_map_pair_exact(Node, Ctxt);
 	'let' ->
 	    lay_let(Node, Ctxt);
 	seq ->
@@ -589,6 +598,24 @@ lay_tuple(Node, Ctxt) ->
 			  Ctxt, fun lay/2)),
 		  floating(text("}")))).
 
+lay_map(Node, Ctxt) ->
+    beside(floating(text("~{")),
+	   beside(par(seq(map_es(Node), floating(text(",")),
+			  Ctxt, fun lay/2)),
+		  floating(text("}~")))).
+
+lay_map_pair_assoc(Node, Ctxt) ->
+    [K,V] = map_pair_assoc_es(Node),
+    beside(floating(text("::<")),
+	beside(lay(K,Ctxt),beside(floating(text(",")), beside(lay(V,Ctxt),
+		    floating(text(">")))))).
+
+lay_map_pair_exact(Node, Ctxt) ->
+    [K,V] = map_pair_exact_es(Node),
+    beside(floating(text("~<")),
+	beside(lay(K,Ctxt),beside(floating(text(",")), beside(lay(V,Ctxt),
+		    floating(text(">")))))).
+
 lay_let(Node, Ctxt) ->
     V = lay_value_list(let_vars(Node), Ctxt),
     D1 = par([follow(text("let"),
diff --git a/lib/hipe/cerl/erl_bif_types.erl b/lib/hipe/cerl/erl_bif_types.erl
index 32a502e212..8b610ac893 100644
--- a/lib/hipe/cerl/erl_bif_types.erl
+++ b/lib/hipe/cerl/erl_bif_types.erl
@@ -114,7 +114,9 @@
 		    t_tuple/1,
 		    t_tuple_args/2,
 		    t_tuple_size/2,
-		    t_tuple_subtypes/2
+		    t_tuple_subtypes/2,
+		    t_is_map/2,
+		    t_map/0
 		   ]).
 
 -ifdef(DO_ERL_BIF_TYPES_TEST).
@@ -654,6 +656,11 @@ type(erlang, is_list, 1, Xs, Opaques) ->
 	    check_guard(X, Fun2, t_maybe_improper_list(), Opaques)
 	end,
   strict(erlang, is_list, 1, Xs, Fun, Opaques);
+type(erlang, is_map, 1, Xs, Opaques) ->
+  Fun = fun (X) -> 
+	    check_guard(X, fun (Y) -> t_is_map(Y, Opaques) end,
+	    t_map(), Opaques) end,
+  strict(erlang, is_map, 1, Xs, Fun, Opaques);
 type(erlang, is_number, 1, Xs, Opaques) ->
   Fun = fun (X) ->
 	    check_guard(X, fun (Y) -> t_is_number(Y, Opaques) end,
@@ -756,6 +763,9 @@ type(erlang, is_tuple, 1, Xs, Opaques) ->
 %% Guard bif, needs to be here.
 type(erlang, length, 1, Xs, Opaques) ->
   strict(erlang, length, 1, Xs, fun (_) -> t_non_neg_fixnum() end, Opaques);
+%% Guard bif, needs to be here.
+type(erlang, map_size, 1, Xs, Opaques) ->
+  strict(erlang, map_size, 1, Xs, fun (_) -> t_non_neg_integer() end, Opaques);
 type(erlang, make_tuple, 2, Xs, Opaques) ->
   strict(erlang, make_tuple, 2, Xs,
 	 fun ([Int, _]) ->
@@ -2297,6 +2307,8 @@ arg_types(erlang, is_integer, 1) ->
   [t_any()];
 arg_types(erlang, is_list, 1) ->
   [t_any()];
+arg_types(erlang, is_map, 1) ->
+  [t_any()];
 arg_types(erlang, is_number, 1) ->
   [t_any()];
 arg_types(erlang, is_pid, 1) ->
@@ -2314,6 +2326,9 @@ arg_types(erlang, is_tuple, 1) ->
 %% Guard bif, needs to be here.
 arg_types(erlang, length, 1) ->
   [t_list()];
+%% Guard bif, needs to be here.
+arg_types(erlang, map_size, 1) ->
+  [t_map()];
 arg_types(erlang, make_tuple, 2) ->
   [t_non_neg_fixnum(), t_any()];  % the value 0 is OK as first argument
 arg_types(erlang, make_tuple, 3) ->
diff --git a/lib/hipe/cerl/erl_types.erl b/lib/hipe/cerl/erl_types.erl
index cfa72d85b7..af34e355bb 100644
--- a/lib/hipe/cerl/erl_types.erl
+++ b/lib/hipe/cerl/erl_types.erl
@@ -208,7 +208,11 @@
 	 lift_list_to_pos_empty/1,
          is_opaque_type/2,
 	 is_erl_type/1,
-	 atom_to_string/1
+	 atom_to_string/1,
+
+	 t_is_map/2,
+	 t_map/1,
+	 t_map/0
 	]).
 
 %%-define(DO_ERL_TYPES_TEST, true).
@@ -266,6 +270,7 @@
 -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).
@@ -278,7 +283,7 @@
 -define(var_tag,        var).
 
 -type tag()  :: ?atom_tag | ?binary_tag | ?function_tag | ?identifier_tag
-              | ?list_tag | ?matchstate_tag | ?nil_tag | ?number_tag
+              | ?list_tag | ?map_tag | ?matchstate_tag | ?nil_tag | ?number_tag
               | ?opaque_tag | ?product_tag | ?remote_tag
               | ?tuple_tag | ?tuple_set_tag | ?union_tag | ?var_tag.
 
@@ -338,6 +343,7 @@
 -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),                #c{tag=?map_tag, elements=Pairs}).
 -define(opaque(Optypes),           #c{tag=?opaque_tag, elements=Optypes}).
 -define(product(Types),            #c{tag=?product_tag, elements=Types}).
 -define(remote(RemTypes),          #c{tag=?remote_tag, elements=RemTypes}).
@@ -361,18 +367,19 @@
 %% 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(remote_union(T),     ?union([?none,?none,?none,?none,?none,?none,?none,?none,?none,T])).
+-define(union(List), #c{tag=?union_tag, elements=[_,_,_,_,_,_,_,_,_,_,_]=List}).
+
+-define(atom_union(T),       ?union([T,?none,?none,?none,?none,?none,?none,?none,?none,?none,?none])).
+-define(bitstr_union(T),     ?union([?none,T,?none,?none,?none,?none,?none,?none,?none,?none,?none])).
+-define(function_union(T),   ?union([?none,?none,T,?none,?none,?none,?none,?none,?none,?none,?none])).
+-define(identifier_union(T), ?union([?none,?none,?none,T,?none,?none,?none,?none,?none,?none,?none])).
+-define(list_union(T),       ?union([?none,?none,?none,?none,T,?none,?none,?none,?none,?none,?none])).
+-define(number_union(T),     ?union([?none,?none,?none,?none,?none,T,?none,?none,?none,?none,?none])).
+-define(tuple_union(T),      ?union([?none,?none,?none,?none,?none,?none,T,?none,?none,?none,?none])).
+-define(matchstate_union(T), ?union([?none,?none,?none,?none,?none,?none,?none,T,?none,?none,?none])).
+-define(opaque_union(T),     ?union([?none,?none,?none,?none,?none,?none,?none,?none,T,?none,?none])).
+-define(remote_union(T),     ?union([?none,?none,?none,?none,?none,?none,?none,?none,?none,T,?none])).
+-define(map_union(T),        ?union([?none,?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)).
@@ -482,6 +489,9 @@ 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(Pairs), Opaques) ->
+  list_contains_opaque([V||{_,V}<-Pairs], Opaques) orelse
+  list_contains_opaque([K||{K,_}<-Pairs], Opaques);
 t_contains_opaque(?matchstate(_P, _Slots), _Opaques) -> false;
 t_contains_opaque(?nil, _Opaques) -> false;
 t_contains_opaque(?number(_Set, _Tag), _Opaques) -> false;
@@ -655,9 +665,9 @@ list_decorate(List, L, Opaques) ->
 
 union_decorate(U1, U2, Opaques) ->
   Union = union_decorate(U1, U2, Opaques, 0, []),
-  [A,B,F,I,L,N,T,M,_,_R] = U1,
-  [_,_,_,_,_,_,_,_,Opaque,_] = U2,
-  List = [A,B,F,I,L,N,T,M],
+  [A,B,F,I,L,N,T,M,_,_R,Map] = U1,
+  [_,_,_,_,_,_,_,_,Opaque,_,_] = U2,
+  List = [A,B,F,I,L,N,T,M,Map],
   DecList = [Dec ||
               E <- List,
               not t_is_none(Dec = decorate(E, Opaque, Opaques))],
@@ -1694,6 +1704,29 @@ lift_list_to_pos_empty(?nil) -> ?nil;
 lift_list_to_pos_empty(?list(Content, Termination, _)) -> 
   ?list(Content, Termination, ?unknown_qual).
 
+%%-----------------------------------------------------------------------------
+%% Maps
+%%
+
+-spec t_map() -> erl_type().
+
+t_map() ->
+  ?map([]).
+
+-spec t_map([{erl_type(),erl_type()}]) -> erl_type().
+
+t_map(_) ->
+  ?map([]).
+
+-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.
+
+
 %%-----------------------------------------------------------------------------
 %% Tuples
 %%
@@ -2517,6 +2550,7 @@ force_union(T = ?nil) ->              ?list_union(T);
 force_union(T = ?number(_,_)) ->      ?number_union(T);
 force_union(T = ?opaque(_)) ->        ?opaque_union(T);
 force_union(T = ?remote(_)) ->        ?remote_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);
@@ -2553,6 +2587,7 @@ t_elements(?number(_, _) = T) ->
   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
@@ -2914,9 +2949,9 @@ 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,_,_R] = Union2,
-        List = [A,B,F,I,L,N,T,M],
+	[_,_,_,_,_,_,_,_,Opaque,_,_] = Union1,
+        [A,B,F,I,L,N,T,M,_,_R,Map] = Union2,
+        List = [A,B,F,I,L,N,T,M,Map],
         inf_union_collect(List, Opaque, InfFun, [], [])
     end,
   O1 = OpaqueFun(U1, U2, fun(E, Opaque) -> t_inf(Opaque, E, Opaques) end),
@@ -3182,11 +3217,11 @@ unify_union1(?union(List), T1, T2) ->
   end.
 
 unify_union(List) ->
-  [A,B,F,I,L,N,T,M,O,R] = List,
+  [A,B,F,I,L,N,T,M,O,R,Map] = List,
   if O =:= ?none -> no;
     true ->
       S = t_opaque_structure(O),
-      {yes, t_sup([A,B,F,I,L,N,T,M,S,R])}
+      {yes, t_sup([A,B,F,I,L,N,T,M,S,R,Map])}
   end.
 
 -spec is_opaque_type(erl_type(), [erl_type()]) -> boolean().
@@ -3537,10 +3572,10 @@ t_subtract_lists([], [], Acc) ->
 -spec subtract_union([erl_type(),...], [erl_type(),...]) -> erl_type().
 
 subtract_union(U1, U2) ->
-  [A1,B1,F1,I1,L1,N1,T1,M1,O1,R1] = U1,
-  [A2,B2,F2,I2,L2,N2,T2,M2,O2,R2] = U2,
-  List1 = [A1,B1,F1,I1,L1,N1,T1,M1,?none,R1],
-  List2 = [A2,B2,F2,I2,L2,N2,T2,M2,?none,R2],
+  [A1,B1,F1,I1,L1,N1,T1,M1,O1,R1,Map1] = U1,
+  [A2,B2,F2,I2,L2,N2,T2,M2,O2,R2,Map2] = U2,
+  List1 = [A1,B1,F1,I1,L1,N1,T1,M1,?none,R1,Map1],
+  List2 = [A2,B2,F2,I2,L2,N2,T2,M2,?none,R2,Map2],
   Sub1 = subtract_union(List1, List2, 0, []),
   O = if O1 =:= ?none -> O1;
          true -> t_subtract(O1, ?union(U2))
@@ -3656,7 +3691,7 @@ 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,R]), Opaques) ->
+t_unopaque(?union([A,B,F,I,L,N,T,M,O,R,Map]), Opaques) ->
   UL = t_unopaque(L, Opaques),
   UT = t_unopaque(T, Opaques),
   UF = t_unopaque(F, Opaques),
@@ -3664,7 +3699,7 @@ t_unopaque(?union([A,B,F,I,L,N,T,M,O,R]), Opaques) ->
               ?opaque(_) = O1 -> {O1, []};
               Type -> {?none, [Type]}
             end,
-  t_sup([?union([A,B,UF,I,UL,N,UT,M,OF,R])|UO]);
+  t_sup([?union([A,B,UF,I,UL,N,UT,M,OF,R,Map])|UO]);
 t_unopaque(T, _) ->
   T.
 
@@ -3941,6 +3976,8 @@ t_to_string(?remote(Set), RecDict) ->
 	       || #remote{mod = Mod, name = Name, args = Args} <-
 		    set_to_list(Set)],
 	      " | ");
+t_to_string(?map(Pairs), RecDict) ->
+    "#{" ++ map_pairs_to_string(Pairs,RecDict) ++ "}";
 t_to_string(?tuple(?any, ?any, ?any), _RecDict) -> "tuple()";
 t_to_string(?tuple(Elements, _Arity, ?any), RecDict) ->   
   "{" ++ comma_sequence(Elements, RecDict) ++ "}";
@@ -3960,6 +3997,13 @@ t_to_string(?var(Id), _RecDict) when is_atom(Id) ->
 t_to_string(?var(Id), _RecDict) when is_integer(Id) ->
   flat_format("var(~w)", [Id]).
 
+
+map_pairs_to_string([],_) -> [];
+map_pairs_to_string(Pairs,RecDict) ->
+    StrPairs = [{t_to_string(K,RecDict),t_to_string(V,RecDict)}||{K,V}<-Pairs],
+    string:join([K ++ "=>" ++ V||{K,V}<-StrPairs], ", ").
+
+
 record_to_string(Tag, [_|Fields], FieldNames, RecDict) ->
   FieldStrings = record_fields_to_string(Fields, FieldNames, RecDict, []),
   "#" ++ atom_to_string(Tag) ++ "{" ++ string:join(FieldStrings, ",") ++ "}".
@@ -4153,6 +4197,8 @@ t_from_form({type, _L, list, []}, _TypeNames, _RecDict, _VarDict) ->
 t_from_form({type, _L, list, [Type]}, TypeNames, RecDict,  VarDict) ->
   {T, R} = t_from_form(Type, TypeNames, RecDict, VarDict),
   {t_list(T), R};
+t_from_form({type, _L, map, _}, _TypeNames, _RecDict, _VarDict) ->
+  {t_map([]), []};
 t_from_form({type, _L, mfa, []}, _TypeNames, _RecDict, _VarDict) ->
   {t_mfa(), []};
 t_from_form({type, _L, module, []}, _TypeNames, _RecDict, _VarDict) ->
@@ -4437,6 +4483,8 @@ 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, _}) ->
+  "#{}";
 t_form_to_string({type, _L, mfa, []}) -> "mfa()";
 t_form_to_string({type, _L, module, []}) -> "module()";
 t_form_to_string({type, _L, node, []}) -> "node()";
@@ -4566,13 +4614,13 @@ do_opaque(?opaque(_) = Type, Opaques, Pred) ->
     false -> Pred(Type)
   end;
 do_opaque(?union(List) = Type, Opaques, Pred) ->
-  [A,B,F,I,L,N,T,M,O,R] = List,
+  [A,B,F,I,L,N,T,M,O,R,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,R]), Opaques, Pred);
+          do_opaque(t_sup([A,B,F,I,L,N,T,M,S,R,Map]), Opaques, Pred);
         false -> Pred(Type)
       end
   end;
diff --git a/lib/stdlib/src/erl_lint.erl b/lib/stdlib/src/erl_lint.erl
index a41bcb91cc..f630db6032 100644
--- a/lib/stdlib/src/erl_lint.erl
+++ b/lib/stdlib/src/erl_lint.erl
@@ -2607,6 +2607,13 @@ check_type({type, L, range, [From, To]}, SeenVars, St) ->
 	    _ -> add_error(L, {type_syntax, range}, St)
 	end,
     {SeenVars, St1};
+check_type({type, _L, map, any}, SeenVars, St) -> {SeenVars, St};
+check_type({type, _L, map, Pairs}, SeenVars, St) ->
+    lists:foldl(fun(Pair, {AccSeenVars, AccSt}) ->
+			check_type(Pair, AccSeenVars, AccSt)
+		end, {SeenVars, St}, Pairs);
+check_type({type, _L, map_field_assoc, Dom, Range}, SeenVars, St) ->
+    check_type({type, -1, product, [Dom, Range]}, SeenVars, St);
 check_type({type, _L, tuple, any}, SeenVars, St) -> {SeenVars, St};
 check_type({type, _L, any}, SeenVars, St) -> {SeenVars, St};
 check_type({type, L, binary, [Base, Unit]}, SeenVars, St) ->
@@ -2712,6 +2719,7 @@ is_default_type({iodata, 0}) -> true;
 is_default_type({iolist, 0}) -> true;
 is_default_type({list, 0}) -> true;
 is_default_type({list, 1}) -> true;
+is_default_type({map, 0}) -> true;
 is_default_type({maybe_improper_list, 0}) -> true;
 is_default_type({maybe_improper_list, 2}) -> true;
 is_default_type({mfa, 0}) -> true;
diff --git a/lib/stdlib/src/erl_parse.yrl b/lib/stdlib/src/erl_parse.yrl
index c04a1aeb89..6d9aafa980 100644
--- a/lib/stdlib/src/erl_parse.yrl
+++ b/lib/stdlib/src/erl_parse.yrl
@@ -48,6 +48,7 @@ opt_bit_size_expr bit_size_expr opt_bit_type_list bit_type_list bit_type
 top_type top_type_100 top_types type typed_expr typed_attr_val
 type_sig type_sigs type_guard type_guards fun_type fun_type_100 binary_type
 type_spec spec_fun typed_exprs typed_record_fields field_types field_type
+map_pair_types map_pair_type
 bin_base_type bin_unit_type type_200 type_300 type_400 type_500.
 
 Terminals
@@ -155,6 +156,8 @@ type -> '[' ']'                           : {type, ?line('$1'), nil, []}.
 type -> '[' top_type ']'                  : {type, ?line('$1'), list, ['$2']}.
 type -> '[' top_type ',' '...' ']'        : {type, ?line('$1'),
                                              nonempty_list, ['$2']}.
+type -> '#' '{' '}'                       : {type, ?line('$1'), map, []}.
+type -> '#' '{' map_pair_types '}'        : {type, ?line('$1'), map, '$3'}.
 type -> '{' '}'                           : {type, ?line('$1'), tuple, []}.
 type -> '{' top_types '}'                 : {type, ?line('$1'), tuple, '$2'}.
 type -> '#' atom '{' '}'                  : {type, ?line('$1'), record, ['$2']}.
@@ -176,6 +179,10 @@ fun_type -> '(' top_types ')' '->' top_type
                                    : {type, ?line('$1'), 'fun',
                                       [{type, ?line('$1'), product, '$2'},'$5']}.
 
+map_pair_types -> map_pair_type                    : ['$1'].
+map_pair_types -> map_pair_type ',' map_pair_types : ['$1'|'$3'].
+map_pair_type  -> top_type '=>' top_type           : {type, ?line('$2'), map_field_assoc,'$1','$3'}.
+
 field_types -> field_type                 : ['$1'].
 field_types -> field_type ',' field_types : ['$1'|'$3'].
 
@@ -674,6 +681,8 @@ skip_paren(Type) ->
 
 build_gen_type({atom, La, tuple}) ->
     {type, La, tuple, any};
+build_gen_type({atom, La, map}) ->
+    {type, La, map, any};
 build_gen_type({atom, La, Name}) ->
     {type, La, Name, []}.
 
-- 
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