Merge branch 'dev' into bmk/inets/ftp/missing_spec_causes_dialyxer_problems/OTP-9114

Also fixed a bunch of "end-years" (was 2010 but should have been 2011,
which the commit hook not happy with).

1 files changed, 603 insertions, 0 deletions

diff --git a/lib/edoc/src/edoc_specs.erl b/lib/edoc/src/edoc_specs.erl
new file mode 100644
index 0000000000..45016ef85a
--- /dev/null
+++ b/lib/edoc/src/edoc_specs.erl
@@ -0,0 +1,603 @@
+%
+%% %CopyrightBegin%
+%%
+%% Copyright Ericsson AB 1996-2011. All Rights Reserved.
+%%
+%% The contents of this file are subject to the Erlang Public License,
+%% Version 1.1, (the "License"); you may not use this file except in
+%% compliance with the License. You should have received a copy of the
+%% Erlang Public License along with this software. If not, it can be
+%% retrieved online at http://www.erlang.org/.
+%%
+%% Software distributed under the License is distributed on an "AS IS"
+%% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
+%% the License for the specific language governing rights and limitations
+%% under the License.
+%%
+%% %CopyrightEnd%
+
+%% @doc EDoc interface to Erlang specifications and types.
+
+-module(edoc_specs).
+
+-export([type/2, spec/2, dummy_spec/1, docs/2]).
+
+-export([add_data/4, tag/1, is_tag/1]).
+
+-include("edoc.hrl").
+-include("edoc_types.hrl").
+
+-type proplist() :: [proplists:property()].
+-type syntaxTree() :: erl_syntax:syntaxTree().
+
+-define(TOP_TYPE, term).
+
+%%
+%%  Exported functions
+%%
+
+-spec type(Form::syntaxTree(), TypeDocs::dict()) -> #tag{}.
+
+%% @doc Convert an Erlang type to EDoc representation.
+%% TypeDocs is a dict of {Name, Doc}.
+%% Note: #t_typedef.name is set to {record, R} for record types.
+type(Form, TypeDocs) ->
+    {Name, Data0} = erl_syntax_lib:analyze_wild_attribute(Form),
+    type = tag(Name),
+    {TypeName, Type, Args, Doc} =
+        case Data0 of
+            {{record, R}, Fs, []} ->
+                L = erl_syntax:get_pos(Form),
+                {{record, R}, {type, L, record, [{atom,L,R} | Fs]}, [], ""};
+            {N,T,As} ->
+                Doc0 =
+                    case dict:find({N, length(As)}, TypeDocs) of
+                        {ok, Doc1} ->
+                            Doc1;
+                        error ->
+                            ""
+                    end,
+                {#t_name{name = N}, T, As, Doc0}
+        end,
+    #tag{name = type, line = element(2, Type),
+         origin = code,
+         data = {#t_typedef{name = TypeName,
+                            args = d2e(Args),
+                            type = d2e(opaque2abstr(Name, Type))},
+                 Doc}}.
+
+-spec spec(Form::syntaxTree(), ClauseN::pos_integer()) -> #tag{}.
+
+%% @doc Convert an Erlang spec to EDoc representation.
+spec(Form, Clause) ->
+    {Name, _Arity, TypeSpecs} = get_spec(Form),
+    TypeSpec = lists:nth(Clause, TypeSpecs),
+    #tag{name = spec, line = element(2, TypeSpec),
+         origin = code,
+         data = aspec(d2e(TypeSpec), Name)}.
+
+-spec dummy_spec(Form::syntaxTree()) -> #tag{}.
+
+%% @doc Create a #tag{} record where data is a string with the name of
+%% the given Erlang spec and an empty list of arguments.
+dummy_spec(Form) ->
+    {#t_name{name = Name}, Arity, TypeSpecs} = get_spec(Form),
+    As = string:join(lists:duplicate(Arity, "_X"), ","),
+    S = lists:flatten(io_lib:format("~p(~s) -> true\n", [Name, As])),
+    #tag{name = spec, line = element(2, hd(TypeSpecs)),
+         origin = code, data = S}.
+
+-spec docs(Forms::[syntaxTree()], CommentFun) -> dict() when
+      CommentFun :: fun(([syntaxTree()], Line :: term()) -> #tag{}).
+
+%% @doc Find comments after -type/-opaque declarations.
+%% Postcomments "inside" the type are skipped.
+docs(Forms, CommentFun) ->
+    find_type_docs(Forms, [], CommentFun).
+
+-type entry() :: #entry{}.
+-type module_info() :: #module{}.
+-type entries() :: [entry()].
+-spec add_data(Entries::entries(), Options::proplist(),
+               File::file:filename(), Module::module_info()) -> entries().
+
+%% @doc Create tags a la EDoc for Erlang specifications and types.
+%% Exported types and types used (indirectly) by Erlang specs are
+%% added to the entries.
+add_data(Entries, Opts, File, Module) ->
+    TypeDefs0 = espec_types(Entries),
+    TypeTable = ets:new(etypes, [ordered_set]),
+    Es1 = expand_records(Entries, TypeDefs0, TypeTable, Opts, File, Module),
+    Es = [use_tags(E, TypeTable) || E <- Es1],
+    true = ets:delete(TypeTable),
+    Es.
+
+%%
+%%  Local functions
+%%
+
+aspec(#t_spec{}=Spec, Name) ->
+    Spec#t_spec{name = Name};
+aspec(Type, Name) ->
+    #t_spec{name = Name, type = Type}.
+
+get_spec(Form) ->
+    {spec, Data0} = erl_syntax_lib:analyze_wild_attribute(Form),
+    case Data0 of
+        {{F,A}, D} ->
+            {#t_name{name = F}, A, D};
+        {{M,F,A}, D} ->
+            {#t_name{module = M, name = F}, A, D}
+    end.
+
+find_type_docs([], Cs, _Fun) ->
+    dict:from_list(Cs);
+find_type_docs([F | Fs], Cs, Fun) ->
+    try get_name_and_last_line(F) of
+        {Name, LastTypeLine} ->
+            C0 = erl_syntax:comment(["% @type f(). "]),
+            C1 = erl_syntax:set_pos(C0, LastTypeLine),
+            %% Postcomments before the dot after the typespec are ignored.
+            C2 = [C1 | [C ||
+                           C <- erl_syntax:get_postcomments(F),
+                           get_line(erl_syntax:get_pos(C)) >= LastTypeLine]],
+            C3 = collect_comments(Fs, LastTypeLine),
+            #tag{data = Doc0} = Fun(lists:reverse(C2 ++ C3), LastTypeLine),
+            case strip(Doc0) of % Strip away "f(). \n"
+                "" ->
+                    find_type_docs(Fs, Cs, Fun);
+                Doc ->
+                    W = edoc_wiki:parse_xml(Doc, LastTypeLine),
+                    find_type_docs(Fs, [{Name, W}|Cs], Fun)
+            end
+    catch _:_ ->
+            find_type_docs(Fs, Cs, Fun)
+    end.
+
+collect_comments([], _Line) ->
+    [];
+collect_comments([F | Fs], Line) ->
+    L1 = get_line(erl_syntax:get_pos(F)),
+    if
+        L1 =:= Line + 1;
+        L1 =:= Line -> % a separate postcomment
+            case is_comment(F) of
+                true ->
+                    [F | collect_comments(Fs, L1)];
+                false ->
+                    []
+            end;
+        true ->
+            []
+    end.
+%% Note: there is a creepy bug concerning an include file terminated
+%% by a -type attribute and the include statement is followed by a
+%% comment (which is not meant to be documentation of the type).
+
+is_comment(F) ->
+    erl_syntax_lib:analyze_form(F) =:= comment.
+
+strip("") ->
+    "";
+strip([$\n | S]) ->
+    S;
+strip([_ | S]) ->
+    strip(S).
+
+%% Find the type name and the greatest line number of a type spec.
+%% Should use syntax_tools but this has to do for now.
+get_name_and_last_line(F) ->
+    {Name, Data} = erl_syntax_lib:analyze_wild_attribute(F),
+    type = edoc_specs:tag(Name),
+    Attr = {attribute, erl_syntax:get_pos(F), Name, Data},
+    Ref = make_ref(),
+    Fun = fun(L) -> {Ref, get_line(L)} end,
+    TypeName = case Data of
+                   {N, _T, As} when is_atom(N) -> % skip records
+                       {N, length(As)}
+               end,
+    Line = gll(erl_lint:modify_line(Attr, Fun), Ref),
+    {TypeName, Line}.
+
+gll({Ref, Line}, Ref) ->
+    Line;
+gll([], _Ref) ->
+    0;
+gll(List, Ref) when is_list(List) ->
+    lists:max([gll(E, Ref) || E <- List]);
+gll(Tuple, Ref) when is_tuple(Tuple) ->
+    gll(tuple_to_list(Tuple), Ref);
+gll(_, _) ->
+    0.
+
+get_line(Pos) ->
+    {line, Line} = erl_scan:attributes_info(Pos, line),
+    Line.
+
+%% Collect all Erlang types. Types in comments (@type) shadow Erlang
+%% types (-spec/-opaque).
+espec_types(Entries) ->
+    Tags = get_all_tags(Entries),
+    CommTs = [type_name(T) ||
+                 #tag{name = type, origin = comment}=T <- Tags],
+    CT = sets:from_list(CommTs),
+    [T || #tag{name = Name, origin = code}=T <- Tags,
+          tag(Name) =:= type,
+          not sets:is_element(type_name(T), CT)].
+
+get_all_tags(Es) ->
+    lists:flatmap(fun (#entry{data = Ts}) -> Ts end, Es).
+
+%% Turns an opaque type into an abstract datatype.
+%% Note: top level annotation is ignored.
+opaque2abstr(opaque, _T) -> undefined;
+opaque2abstr(type, T) -> T.
+
+%% Replaces the parameters extracted from the source (by
+%% edoc_extract:parameters/1) by annotations and variable names, using
+%% the source parameters as default values
+%% Selects seen types (exported types, types used by specs),
+%% skips records and unused types.
+use_tags(#entry{data = Ts}=E, TypeTable) ->
+    use_tags(Ts, E, TypeTable, []).
+
+use_tags([], E, _TypeTable, NTs) ->
+    E#entry{data = lists:reverse(NTs)};
+use_tags([#tag{origin = code}=T | Ts], E, TypeTable, NTs) ->
+    case tag(T#tag.name) of
+        spec ->
+            Args = params(T, E#entry.args),
+            use_tags(Ts, E#entry{args = Args}, TypeTable, [T | NTs]);
+        type ->
+            TypeName = type_name(T),
+            case ets:lookup(TypeTable, TypeName) of
+                [{{{record,_},_},_,_}] ->
+                    use_tags(Ts, E, TypeTable, NTs);
+                [{_,_,not_seen}] ->
+                    use_tags(Ts, E, TypeTable, NTs);
+                [] ->
+                    use_tags(Ts, E, TypeTable, NTs);
+                [{TypeName, Tag, seen}] ->
+                    use_tags(Ts, E, TypeTable, [Tag | NTs])
+            end
+    end;
+use_tags([T | Ts], E, TypeTable, NTs) ->
+    use_tags(Ts, E, TypeTable, [T | NTs]).
+
+params(#tag{name = spec, data=#t_spec{type = #t_fun{args = As}}}, Default) ->
+    parms(As, Default).
+
+parms([], []) ->
+    [];
+parms([A | As], [D | Ds]) ->
+    [param(A, D) | parms(As, Ds)].
+
+param(#t_list{type = Type}, Default) ->
+    param(Type, Default);
+param(#t_paren{type = Type}, Default) ->
+    param(Type, Default);
+param(#t_nonempty_list{type = Type}, Default) ->
+    param(Type, Default);
+param(#t_record{name = #t_atom{val = Name}}, _Default) ->
+    list_to_atom(capitalize(atom_to_list(Name)));
+param(T, Default) ->
+    arg_name(?t_ann(T), Default).
+
+capitalize([C | Cs]) when C >= $a, C =< $z -> [C - 32 | Cs];
+capitalize(Cs) -> Cs.
+
+%% Like edoc_types:arg_name/1
+arg_name([], Default) ->
+    Default;
+arg_name([A | As], Default) ->
+    case is_name(A) of
+        true -> A;
+        false -> arg_name(As, Default)
+    end.
+
+is_name(A) ->
+    is_atom(A).
+
+d2e({ann_type,_,[V, T0]}) ->
+    %% Note: the -spec/-type syntax allows annotations everywhere, but
+    %% EDoc does not. The fact that the annotation is added to the
+    %% type here does not necessarily mean that it will be used by the
+    %% layout module.
+    T = d2e(T0),
+    ?add_t_ann(T, element(3, V));
+d2e({type,_,no_return,[]}) ->
+    #t_type{name = #t_name{name = none}};
+d2e({remote_type,_,[{atom,_,M},{atom,_,F},Ts0]}) ->
+    Ts = d2e(Ts0),
+    typevar_anno(#t_type{name = #t_name{module = M, name = F}, args = Ts}, Ts);
+d2e({type,_,'fun',[{type,_,product,As0},Ran0]}) ->
+    Ts = [Ran|As] = d2e([Ran0|As0]),
+    %% Assume that the linter has checked type variables.
+    typevar_anno(#t_fun{args = As, range = Ran}, Ts);
+d2e({type,_,'fun',[A0={type,_,any},Ran0]}) ->
+    Ts = [A, Ran] = d2e([A0, Ran0]),
+    typevar_anno(#t_fun{args = [A], range = Ran}, Ts);
+d2e({type,_,'fun',[]}) ->
+    #t_type{name = #t_name{name = function}, args = []};
+d2e({type,_,any}) ->
+    #t_var{name = '...'}; % Kludge... not a type variable!
+d2e({type,_,nil,[]}) ->
+    #t_nil{};
+d2e({paren_type,_,[T]}) ->
+    #t_paren{type = d2e(T)};
+d2e({type,_,list,[T0]}) ->
+    T = d2e(T0),
+    typevar_anno(#t_list{type = T}, [T]);
+d2e({type,_,nonempty_list,[T0]}) ->
+    T = d2e(T0),
+    typevar_anno(#t_nonempty_list{type = T}, [T]);
+d2e({type,_,bounded_fun,[T,Gs]}) ->
+    [F0|Defs] = d2e([T|Gs]),
+    F = ?set_t_ann(F0, lists:keydelete(type_variables, 1, ?t_ann(F0))),
+    %% Assume that the linter has checked type variables.
+    #t_spec{type = typevar_anno(F, [F0]), defs = Defs};
+d2e({type,_,range,[V1,V2]}) ->
+    {integer,_,I1} = erl_eval:partial_eval(V1),
+    {integer,_,I2} = erl_eval:partial_eval(V2),
+    #t_integer_range{from = I1, to = I2};
+d2e({type,_,constraint,[Sub,Ts0]}) ->
+    case {Sub,Ts0} of
+        {{atom,_,is_subtype},[{var,_,N},T0]} ->
+            Ts = [T] = d2e([T0]),
+            #t_def{name = #t_var{name = N}, type = typevar_anno(T, Ts)};
+        {{atom,_,is_subtype},[ST0,T0]} ->
+            %% Should not happen.
+            Ts = [ST,T] = d2e([ST0,T0]),
+            #t_def{name = ST, type = typevar_anno(T, Ts)};
+        _ ->
+            throw_error(element(2, Sub), "cannot handle guard", [])
+    end;
+d2e({type,_,union,Ts0}) ->
+    Ts = d2e(Ts0),
+    typevar_anno(#t_union{types = Ts}, Ts);
+d2e({type,_,tuple,any}) ->
+    #t_type{name = #t_name{name = tuple}, args = []};
+d2e({type,_,binary,[Base,Unit]}) ->
+    #t_binary{base_size = element(3, Base),
+              unit_size = element(3, Unit)};
+d2e({type,_,tuple,Ts0}) ->
+    Ts = d2e(Ts0),
+    typevar_anno(#t_tuple{types = Ts}, Ts);
+d2e({type,_,record,[Name|Fs0]}) ->
+    Atom = #t_atom{val = element(3, Name)},
+    Fs = d2e(Fs0),
+    typevar_anno(#t_record{name = Atom, fields = Fs}, Fs);
+d2e({type,_,field_type,[Name,Type0]}) ->
+    Type = d2e(Type0),
+    typevar_anno(#t_field{name = #t_atom{val = element(3, Name)}, type = Type},
+                 [Type]);
+d2e({typed_record_field,{record_field,L,Name},Type}) ->
+    d2e({type,L,field_type,[Name,Type]});
+d2e({typed_record_field,{record_field,L,Name,_E},Type}) ->
+    d2e({type,L,field_type,[Name,Type]});
+d2e({record_field,L,_Name,_E}=F) ->
+    d2e({typed_record_field,F,{type,L,any,[]}}); % Maybe skip...
+d2e({record_field,L,_Name}=F) ->
+    d2e({typed_record_field,F,{type,L,any,[]}}); % Maybe skip...
+d2e({type,_,Name,Types0}) ->
+    Types = d2e(Types0),
+    typevar_anno(#t_type{name = #t_name{name = Name}, args = Types}, Types);
+d2e({var,_,'_'}) ->
+    #t_type{name = #t_name{name = ?TOP_TYPE}};
+d2e({var,_,TypeName}) ->
+    TypeVar = ordsets:from_list([TypeName]),
+    T = #t_var{name = TypeName},
+    %% Annotate type variables with the name of the variable.
+    %% Doing so will stop edoc_layout (and possibly other layout modules)
+    %% from using the argument name from the source or to invent a new name.
+    T1 = ?add_t_ann(T, {type_variables, TypeVar}),
+    ?add_t_ann(T1, TypeName);
+d2e(L) when is_list(L) ->
+    [d2e(T) || T <- L];
+d2e({atom,_,A}) ->
+    #t_atom{val = A};
+d2e(undefined = U) -> % opaque
+    U;
+d2e(Expr) ->
+    {integer,_,I} = erl_eval:partial_eval(Expr),
+    #t_integer{val = I}.
+
+%% A type annotation (a tuple; neither an atom nor a list).
+typevar_anno(Type, Ts) ->
+    Vs = typevars(Ts),
+    case ordsets:to_list(Vs) of
+        [] -> Type;
+        _ -> ?add_t_ann(Type, {type_variables, Vs})
+    end.
+
+typevars(Ts) ->
+    ordsets:union(get_typevars(Ts)).
+
+get_typevars(Ts) ->
+    [Vs || T <- Ts, T =/= undefined, {type_variables, Vs} <- ?t_ann(T)].
+
+-record(parms, {tab, warn, file, line}).
+
+%% Expands record references. Explicitly given record fields are kept,
+%% but otherwise the fields from the record definition are substituted
+%% for the reference. The reason is that there are no record types.
+%% It is recommended to introduce types like "r() :: r{}" and then use
+%% r() everywhere. The right hand side, r{}, is expanded in order to
+%% show all fields.
+%% Returns updated types in the ETS table DT.
+expand_records(Entries, TypeDefs, DT, Opts, File, Module) ->
+    TypeList = [{type_name(T), T, not_seen} || T <- TypeDefs],
+    true = ets:insert(DT, TypeList),
+    Warn = proplists:get_value(report_missing_type, Opts,
+                               ?REPORT_MISSING_TYPE) =:= true,
+    P = #parms{tab = DT, warn = Warn, file = File, line = 0},
+    ExportedTypes = [Name ||
+                        {export_type,Ts} <- Module#module.attributes,
+                        is_list(Ts),
+                        {N,I} <- Ts,
+                        ets:member(DT, Name = {#t_name{name = N}, I})],
+    _ = lists:foreach(fun({N,A}) -> true = seen_type(N, A, P)
+                      end, ExportedTypes),
+    entries(Entries, P, Opts).
+
+entries([E0 | Es], P, Opts) ->
+    E = case edoc_data:hidden_filter([E0], Opts) of
+            [] ->
+                E0;
+            [_] ->
+                E0#entry{data = specs(E0#entry.data, P)}
+        end,
+    [E | entries(Es, P, Opts)];
+entries([], _P, _Opts) ->
+    [].
+
+specs([#tag{line = L, name = spec, origin = code, data = Spec}=Tag0 | Tags],
+      P0) ->
+    #t_spec{type = Type0, defs = Defs0} = Spec,
+    P = P0#parms{line = L},
+    Type = xrecs(Type0, P),
+    Defs = xrecs(Defs0, P),
+    Tag = Tag0#tag{data = Spec#t_spec{type = Type, defs = Defs}},
+    [Tag | specs(Tags, P)];
+specs([Tag | Tags], P) ->
+    [Tag | specs(Tags, P)];
+specs([], _P) ->
+    [].
+
+xrecs(#t_def{type = Type0}=T, P) ->
+    Type = xrecs(Type0, P),
+    T#t_def{type = Type};
+xrecs(#t_type{name = Name, args = Args0}=T, P) ->
+    Args = xrecs(Args0, P),
+    NArgs = length(Args),
+    true = seen_type(Name, NArgs, P),
+    T#t_type{args = Args};
+xrecs(#t_var{}=T, _P) ->
+    T;
+xrecs(#t_fun{args = Args0, range = Range0}=T, P) ->
+    Args = xrecs(Args0, P),
+    Range = xrecs(Range0, P),
+    T#t_fun{args = Args, range = Range};
+xrecs(#t_tuple{types = Types0}=T, P) ->
+    Types = xrecs(Types0, P),
+    T#t_tuple{types = Types};
+xrecs(#t_list{type = Type0}=T, P) ->
+    Type = xrecs(Type0, P),
+    T#t_list{type = Type};
+xrecs(#t_nil{}=T, _P) ->
+    T;
+xrecs(#t_paren{type = Type0}=T, P) ->
+    Type = xrecs(Type0, P),
+    T#t_paren{type = Type};
+xrecs(#t_nonempty_list{type = Type0}=T, P) ->
+    Type = xrecs(Type0, P),
+    T#t_nonempty_list{type = Type};
+xrecs(#t_atom{}=T, _P) ->
+    T;
+xrecs(#t_integer{}=T, _P) ->
+    T;
+xrecs(#t_integer_range{}=T, _P) ->
+    T;
+xrecs(#t_binary{}=T, _P) ->
+    T;
+xrecs(#t_float{}=T, _P) ->
+    T;
+xrecs(#t_union{types = Types0}=T, P) ->
+    Types = xrecs(Types0, P),
+    T#t_union{types = Types};
+xrecs(#t_record{fields = Fields0}=T, P) ->
+    Fields1 = xrecs(Fields0, P),
+    #t_record{name = #t_atom{val = Name}} = T,
+    RName = {record, Name},
+    true = seen_type(RName, 0, P),
+    Fields = select_fields(Fields1, RName, P#parms.tab),
+    T#t_record{fields = Fields};
+xrecs(#t_field{type = Type0}=T, P) ->
+    Type = xrecs(Type0, P),
+    T#t_field{type = Type};
+xrecs(undefined=T, _P) -> % opaque
+    T;
+xrecs([]=T, _P) ->
+    T;
+xrecs([E0 | Es0], P) ->
+    [xrecs(E0, P) | xrecs(Es0, P)].
+
+seen_type(N, NArgs, P) ->
+    TypeName = {N, NArgs},
+    #parms{tab = DT} = P,
+    case {ets:lookup(DT, TypeName), N} of
+        {[{TypeName, _, seen}], _} ->
+            true;
+        {[{TypeName, TagType, not_seen}], _} when N#t_name.module =:= [] ->
+            expand_datatype(TagType, proper_type, DT, P);
+        {[{TypeName, TagType, not_seen}], {record, _}} ->
+            expand_datatype(TagType, record_type, DT, P);
+        {[], {record, R}} ->
+            #parms{warn = W, line = L, file = File} = P,
+            [edoc_report:warning(L, File, "reference to untyped record ~w",
+                                 [R]) || W],
+            ets:insert(DT, {TypeName, fake, seen});
+        {[], _} -> % External type or missing type.
+            true
+    end.
+
+expand_datatype(Tag0, Kind, DT, P0) ->
+    #tag{line = L, data = {T0, Doc}} = Tag0,
+    #t_typedef{type = Type0, defs = []} = T0,
+    TypeName = type_name(Tag0),
+    true = ets:update_element(DT, TypeName, {3, seen}),
+    P = P0#parms{line = L},
+    Type = case Kind of
+               record_type ->
+                   #t_record{fields = Fields0} = Type0,
+                   Fields = xrecs(Fields0, P),
+                   Type0#t_record{fields = Fields};
+               proper_type ->
+                   xrecs(Type0, P)
+           end,
+    Tag = Tag0#tag{data={T0#t_typedef{type=Type}, Doc}},
+    ets:insert(DT, {TypeName, Tag, seen}).
+
+select_fields(Fields, Name, DT) ->
+    RecordName = {Name, 0},
+    case ets:lookup(DT, RecordName) of
+        [{RecordName, fake, seen}] ->
+            Fields;
+        [{RecordName, #tag{data = {T, _Doc}}, seen}] ->
+            #t_typedef{args = [], type = #t_record{fields = Fs}, defs = []}=T,
+            [find_field(F, Fields) || F <- Fs]
+    end.
+
+find_field(F, Fs) ->
+    case lists:keyfind(F#t_field.name, #t_field.name, Fs) of
+        false -> F;
+        NF -> NF
+    end.
+
+type_name(#tag{name = type,
+               data = {#t_typedef{name = Name, args = As},_}}) ->
+    {Name, length(As)}.
+
+%% @doc Return `true' if `Tag' is one of the specification and type
+%% attribute tags recognized by the Erlang compiler.
+
+-spec is_tag(Tag::atom()) -> boolean().
+
+is_tag(opaque) -> true;
+is_tag(spec) -> true;
+is_tag(type) -> true;
+is_tag(_) -> false.
+
+%% @doc Return the kind of the attribute tag.
+
+-type tag_kind() :: 'type' | 'spec' | 'unknown'.
+-spec tag(Tag::atom()) -> tag_kind().
+
+tag(opaque) -> type;
+tag(spec) -> spec;
+tag(type) -> type;
+tag(_) -> unknown.
+
+throw_error(Line, S, A) ->
+    edoc_report:error(Line, "", io_lib:format(S, A)),
+    throw(error).