Warn for opaque types that are not exported

2 files changed, 49 insertions, 9 deletions

diff --git a/lib/stdlib/src/erl_lint.erl b/lib/stdlib/src/erl_lint.erl
index 97dacac0a4..a03abfaf80 100644
--- a/lib/stdlib/src/erl_lint.erl
+++ b/lib/stdlib/src/erl_lint.erl
@@ -365,6 +365,9 @@ format_error(callback_wrong_arity) ->
 format_error({imported_predefined_type, Name}) ->
     io_lib:format("referring to built-in type ~w as a remote type; "
 		  "please take out the module name", [Name]);
+format_error({not_exported_opaque, {TypeName, Arity}}) ->
+    io_lib:format("opaque type ~w~s is not exported",
+                  [TypeName, gen_type_paren(Arity)]);
 %% --- obsolete? unused? ---
 format_error({format_error, {Fmt, Args}}) ->
     io_lib:format(Fmt, Args);
@@ -851,7 +854,8 @@ post_traversal_check(Forms, St0) ->
     StC = check_untyped_records(Forms, StB),
     StD = check_on_load(StC),
     StE = check_unused_records(Forms, StD),
-    check_callback_information(StE).
+    StF = check_local_opaque_types(StE),
+    check_callback_information(StF).
 
 %% check_behaviour(State0) -> State
 %% Check that the behaviour attribute is valid.
@@ -2554,15 +2558,18 @@ find_field(_F, []) -> error.
 %%    Attr :: 'type' | 'opaque'
 %% Checks that a type definition is valid.
 
+-record(typeinfo, {attr, line}).
+
 type_def(_Attr, _Line, {record, _RecName}, Fields, [], St0) ->
     %% The record field names and such are checked in the record format.
     %% We only need to check the types.
     Types = [T || {typed_record_field, _, T} <- Fields],
     check_type({type, -1, product, Types}, St0);
-type_def(_Attr, Line, TypeName, ProtoType, Args, St0) ->
+type_def(Attr, Line, TypeName, ProtoType, Args, St0) ->
     TypeDefs = St0#lint.types,
     Arity = length(Args),
     TypePair = {TypeName, Arity},
+    Info = #typeinfo{attr = Attr, line = Line},
     case (dict:is_key(TypePair, TypeDefs) orelse is_var_arity_type(TypeName)) of
 	true ->
 	    case dict:is_key(TypePair, default_types()) of
@@ -2572,7 +2579,7 @@ type_def(_Attr, Line, TypeName, ProtoType, Args, St0) ->
 			true ->
 			    Warn = {new_builtin_type, TypePair},
 			    St1 = add_warning(Line, Warn, St0),
-			    NewDefs = dict:store(TypePair, Line, TypeDefs),
+			    NewDefs = dict:store(TypePair, Info, TypeDefs),
 			    CheckType = {type, -1, product, [ProtoType|Args]},
 			    check_type(CheckType, St1#lint{types=NewDefs});
 			false ->
@@ -2581,7 +2588,7 @@ type_def(_Attr, Line, TypeName, ProtoType, Args, St0) ->
 	        false -> add_error(Line, {redefine_type, TypePair}, St0)
 	    end;
 	false ->
-	    NewDefs = dict:store(TypePair, Line, TypeDefs),
+	    NewDefs = dict:store(TypePair, Info, TypeDefs),
 	    CheckType = {type, -1, product, [ProtoType|Args]},
 	    check_type(CheckType, St0#lint{types=NewDefs})
     end.
@@ -2895,7 +2902,7 @@ check_unused_types(Forms, #lint{usage=Usage, types=Ts, exp_types=ExpTs}=St) ->
 		fun(_Type, -1, AccSt) ->
 			%% Default type
 			AccSt;
-		   (Type, FileLine, AccSt) ->
+		   (Type, #typeinfo{line = FileLine}, AccSt) ->
                         case loc(FileLine) of
 			    {FirstFile, _} ->
 				case gb_sets:is_member(Type, UsedTypes) of
@@ -2914,6 +2921,24 @@ check_unused_types(Forms, #lint{usage=Usage, types=Ts, exp_types=ExpTs}=St) ->
 	    St
     end.
 
+check_local_opaque_types(St) ->
+    #lint{types=Ts, exp_types=ExpTs} = St,
+    FoldFun =
+        fun(_Type, -1, AccSt) ->
+                %% Default type
+                AccSt;
+           (_Type, #typeinfo{attr = type}, AccSt) ->
+                AccSt;
+           (Type, #typeinfo{attr = opaque, line = FileLine}, AccSt) ->
+                case gb_sets:is_element(Type, ExpTs) of
+                    true -> AccSt;
+                    false ->
+                        Warn = {not_exported_opaque,Type},
+                        add_warning(FileLine, Warn, AccSt)
+                end
+        end,
+    dict:fold(FoldFun, St, Ts).
+
 %% icrt_clauses(Clauses, In, ImportVarTable, State) ->
 %%      {NewVts,State}.
 
diff --git a/lib/stdlib/test/erl_lint_SUITE.erl b/lib/stdlib/test/erl_lint_SUITE.erl
index 944d8ebd6a..2a9163b6c4 100644
--- a/lib/stdlib/test/erl_lint_SUITE.erl
+++ b/lib/stdlib/test/erl_lint_SUITE.erl
@@ -50,7 +50,8 @@
 	  unsafe_vars_try/1,
 	  guard/1, otp_4886/1, otp_4988/1, otp_5091/1, otp_5276/1, otp_5338/1,
 	  otp_5362/1, otp_5371/1, otp_7227/1, otp_5494/1, otp_5644/1, otp_5878/1,
-	  otp_5917/1, otp_6585/1, otp_6885/1, export_all/1,
+	  otp_5917/1, otp_6585/1, otp_6885/1, otp_10436/1,
+          export_all/1,
 	  bif_clash/1,
 	  behaviour_basic/1, behaviour_multiple/1,
 	  otp_7550/1,
@@ -80,7 +81,7 @@ all() ->
      unsafe_vars, unsafe_vars2, unsafe_vars_try, guard,
      otp_4886, otp_4988, otp_5091, otp_5276, otp_5338,
      otp_5362, otp_5371, otp_7227, otp_5494, otp_5644,
-     otp_5878, otp_5917, otp_6585, otp_6885, export_all,
+     otp_5878, otp_5917, otp_6585, otp_6885, otp_10436, export_all,
      bif_clash, behaviour_basic, behaviour_multiple,
      otp_7550, otp_8051, format_warn, {group, on_load},
      too_many_arguments].
@@ -2386,6 +2387,20 @@ otp_6885(Config) when is_list(Config) ->
 	   []} = run_test2(Config, Ts, []),
     ok.
 
+otp_10436(doc) ->
+    "OTP-6885. Warnings for opaque types.";
+otp_10436(suite) -> [];
+otp_10436(Config) when is_list(Config) ->
+    Ts = <<"-module(otp_10436).
+            -export_type([t1/0]).
+            -opaque t1() :: {i, integer()}.
+            -opaque t2() :: {a, atom()}.
+         ">>,
+    {warnings,[{4,erl_lint,{not_exported_opaque,{t2,0}}},
+               {4,erl_lint,{unused_type,{t2,0}}}]} =
+        run_test2(Config, Ts, []),
+    ok.
+
 export_all(doc) ->
     "OTP-7392. Warning for export_all.";
 export_all(Config) when is_list(Config) ->
@@ -2834,10 +2849,10 @@ otp_8051(doc) ->
 otp_8051(Config) when is_list(Config) ->
     Ts = [{otp_8051,
            <<"-opaque foo() :: bar().
+              -export_type([foo/0]).
              ">>,
            [],
-           {error,[{1,erl_lint,{undefined_type,{bar,0}}}],
-            [{1,erl_lint,{unused_type,{foo,0}}}]}}],
+           {errors,[{1,erl_lint,{undefined_type,{bar,0}}}],[]}}],
     ?line [] = run(Config, Ts),
     ok.