stdlib: warn if the type map() is redefined

4 files changed, 47 insertions, 23 deletions

diff --git a/lib/dialyzer/test/small_SUITE_data/src/maps_redef.erl b/lib/dialyzer/test/small_SUITE_data/src/maps_redef.erl
new file mode 100644
index 0000000000..70059f73b6
--- /dev/null
+++ b/lib/dialyzer/test/small_SUITE_data/src/maps_redef.erl
@@ -0,0 +1,12 @@
+-module(maps_redef).
+
+-export([t/0]).
+
+%% OK in Erlang/OTP 17, at least.
+
+-type map() :: atom(). % redefine built-in type
+
+-spec t() -> map().
+
+t() ->
+    a. % OK
diff --git a/lib/hipe/cerl/erl_types.erl b/lib/hipe/cerl/erl_types.erl
index 2c6a1aa506..ae333f4b1a 100644
--- a/lib/hipe/cerl/erl_types.erl
+++ b/lib/hipe/cerl/erl_types.erl
@@ -4257,8 +4257,8 @@ 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, map, _}, TypeNames, RecDict, VarDict) ->
+  builtin_type(map, t_map([]), TypeNames, RecDict, VarDict);
 t_from_form({type, _L, mfa, []}, _TypeNames, _RecDict, _VarDict) ->
   {t_mfa(), []};
 t_from_form({type, _L, module, []}, _TypeNames, _RecDict, _VarDict) ->
diff --git a/lib/stdlib/src/erl_lint.erl b/lib/stdlib/src/erl_lint.erl
index 0d2092da50..c4c94fbee4 100644
--- a/lib/stdlib/src/erl_lint.erl
+++ b/lib/stdlib/src/erl_lint.erl
@@ -331,10 +331,14 @@ format_error({undefined_type, {TypeName, Arity}}) ->
     io_lib:format("type ~w~s undefined", [TypeName, gen_type_paren(Arity)]);
 format_error({unused_type, {TypeName, Arity}}) ->
     io_lib:format("type ~w~s is unused", [TypeName, gen_type_paren(Arity)]);
-format_error({new_builtin_type, {TypeName, Arity}}) ->
-    io_lib:format("type ~w~s is a new builtin type; "
+%% format_error({new_builtin_type, {TypeName, Arity}}) ->
+%%     io_lib:format("type ~w~s is a new builtin type; "
+%% 		  "its (re)definition is allowed only until the next release",
+%% 		  [TypeName, gen_type_paren(Arity)]);
+format_error({new_var_arity_type, TypeName}) ->
+    io_lib:format("type ~w is a new builtin type; "
 		  "its (re)definition is allowed only until the next release",
-		  [TypeName, gen_type_paren(Arity)]);
+		  [TypeName]);
 format_error({builtin_type, {TypeName, Arity}}) ->
     io_lib:format("type ~w~s is a builtin type; it cannot be redefined",
 		  [TypeName, gen_type_paren(Arity)]);
@@ -2606,23 +2610,30 @@ type_def(Attr, Line, TypeName, ProtoType, Args, St0) ->
         true ->
             case is_obsolete_builtin_type(TypePair) of
                 true -> StoreType(St0);
-                false ->
-                    case is_newly_introduced_builtin_type(TypePair) of
-                        %% allow some types just for bootstrapping
-                        true ->
-                            Warn = {new_builtin_type, TypePair},
-                            St1 = add_warning(Line, Warn, St0),
-                            StoreType(St1);
-                        false ->
-                            add_error(Line, {builtin_type, TypePair}, St0)
-                    end
+                false -> add_error(Line, {builtin_type, TypePair}, St0)
+%%                     case is_newly_introduced_builtin_type(TypePair) of
+%%                         %% allow some types just for bootstrapping
+%%                         true ->
+%%                             Warn = {new_builtin_type, TypePair},
+%%                             St1 = add_warning(Line, Warn, St0),
+%%                             StoreType(St1);
+%%                         false ->
+%%                             add_error(Line, {builtin_type, TypePair}, St0)
+%%                     end
             end;
         false ->
             case
-                dict:is_key(TypePair, TypeDefs)
-                orelse is_var_arity_type(TypeName)
+                dict:is_key(TypePair, TypeDefs) orelse
+                is_var_arity_type(TypeName)
             of
-                true -> add_error(Line, {redefine_type, TypePair}, St0);
+                true ->
+                    case is_newly_introduced_var_arity_type(TypeName) of
+                        true ->
+                            Warn = {new_var_arity_type, TypeName},
+                            add_warning(Line, Warn, St0);
+                        false ->
+                            add_error(Line, {redefine_type, TypePair}, St0)
+                    end;
                 false ->
                     St1 = case
                               Attr =:= opaque andalso
@@ -2857,8 +2868,10 @@ is_default_type({timeout, 0}) -> true;
 is_default_type({var, 1}) -> true;
 is_default_type(_) -> false.
 
-%% OTP 17.0
-is_newly_introduced_builtin_type({Name, _}) when is_atom(Name) -> false.
+is_newly_introduced_var_arity_type(map) -> true;
+is_newly_introduced_var_arity_type(_) -> false.
+
+%% is_newly_introduced_builtin_type({Name, _}) when is_atom(Name) -> false.
 
 is_obsolete_builtin_type(TypePair) ->
     obsolete_builtin_type(TypePair) =/= no.
diff --git a/lib/stdlib/test/erl_lint_SUITE.erl b/lib/stdlib/test/erl_lint_SUITE.erl
index 673a3cf159..f822986981 100644
--- a/lib/stdlib/test/erl_lint_SUITE.erl
+++ b/lib/stdlib/test/erl_lint_SUITE.erl
@@ -92,7 +92,7 @@ all() ->
      bif_clash, behaviour_basic, behaviour_multiple,
      otp_7550, otp_8051, format_warn, {group, on_load},
      too_many_arguments, basic_errors, bin_syntax_errors, predef,
-     maps,maps_type].
+     maps, maps_type].
 
 groups() -> 
     [{unused_vars_warn, [],
@@ -3439,11 +3439,10 @@ maps_type(Config) when is_list(Config) ->
 	    t(M) -> M.
 	 ">>,
 	 [],
-	 {errors,[{3,erl_lint,{redefine_type,{map,0}}}],[]}}],
+	 {warnings,[{3,erl_lint,{new_var_arity_type,map}}]}}],
     [] = run(Config, Ts),
     ok.
 
-
 run(Config, Tests) ->
     F = fun({N,P,Ws,E}, BadL) ->
                 case catch run_test(Config, P, Ws) of