4 files changed, 46 insertions, 16 deletions
diff --git a/lib/dialyzer/src/dialyzer_dataflow.erl b/lib/dialyzer/src/dialyzer_dataflow.erl
index 6bd3c2f9a6..c5f93a3392 100644
--- a/lib/dialyzer/src/dialyzer_dataflow.erl
+++ b/lib/dialyzer/src/dialyzer_dataflow.erl
@@ -3444,19 +3444,19 @@ state__fun_info(Fun, #state{callgraph = CG, fun_tab = FunTab, plt = PLT}) ->
   {Fun, Sig, Contract, LocalRet}.
 
 forward_args(Fun, ArgTypes, #state{work = Work, fun_tab = FunTab} = State) ->
-  {OldArgTypes, OldOut, Fixpoint} =
+  {NewArgTypes, OldOut, Fixpoint} =
     case dict:find(Fun, FunTab) of
-      {ok, {not_handled, {OldArgTypes0, OldOut0}}} ->
-	{OldArgTypes0, OldOut0, false};
+      {ok, {not_handled, {_OldArgTypesAreNone, OldOut0}}} ->
+	{ArgTypes, OldOut0, false};
       {ok, {OldArgTypes0, OldOut0}} ->
-	{OldArgTypes0, OldOut0,
-	 t_is_subtype(t_product(ArgTypes), t_product(OldArgTypes0))}
+        NewArgTypes0 = [t_sup(X, Y) ||
+                         {X, Y} <- lists:zip(ArgTypes, OldArgTypes0)],
+	{NewArgTypes0, OldOut0,
+         t_is_equal(t_product(NewArgTypes0), 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("~tw: forwarding args ~ts\n",
 	     [state__lookup_name(Fun, State),
diff --git a/lib/dialyzer/src/dialyzer_plt.erl b/lib/dialyzer/src/dialyzer_plt.erl
index 95c8b5ebce..2af4534396 100644
--- a/lib/dialyzer/src/dialyzer_plt.erl
+++ b/lib/dialyzer/src/dialyzer_plt.erl
@@ -531,17 +531,19 @@ compute_md5_from_files(Files) ->
   lists:keysort(1, [{F, compute_md5_from_file(F)} || F <- Files]).
 
 compute_md5_from_file(File) ->
-  case filelib:is_regular(File) of
-    false ->
+  case beam_lib:all_chunks(File) of
+    {ok, _, Chunks} ->
+      %% We cannot use beam_lib:md5 because it does not consider
+      %% the debug_info chunk, where typespecs are likely stored.
+      %% So we consider almost all chunks except the useless ones.
+      Filtered = [[ID, Chunk] || {ID, Chunk} <- Chunks, ID =/= "CInf", ID =/= "Docs"],
+      erlang:md5(lists:sort(Filtered));
+    {error, beam_lib, {file_error, _, enoent}} ->
       Msg = io_lib:format("Not a regular file: ~ts\n", [File]),
       throw({dialyzer_error, Msg});
-    true ->
-      case dialyzer_utils:get_core_from_beam(File) of
-	{error, Error} ->
-	  throw({dialyzer_error, Error});
-	{ok, Core} ->
-	  erlang:md5(term_to_binary(Core))
-      end
+    {error, beam_lib, _} ->
+      Msg = io_lib:format("Could not compute MD5 for .beam: ~ts\n", [File]),
+      throw({dialyzer_error, Msg})
   end.
 
 init_diff_list(RemoveFiles, AddFiles) ->
diff --git a/lib/dialyzer/test/opaque_SUITE_data/src/para_bug/same.erl b/lib/dialyzer/test/opaque_SUITE_data/src/para_bug/same.erl
new file mode 100644
index 0000000000..44149f4199
--- /dev/null
+++ b/lib/dialyzer/test/opaque_SUITE_data/src/para_bug/same.erl
@@ -0,0 +1,15 @@
+-module(same).
+
+-export([baz/1]).
+
+-record(bar, {
+          a :: same_type:st(integer()),
+          b :: same_type:st(atom())
+         }).
+
+baz(Bar) ->
+    _ = wrap_find(0, Bar#bar.a),
+    wrap_find(0, Bar#bar.b).
+
+wrap_find(K, D) ->
+  same_type:t(K, D).
diff --git a/lib/dialyzer/test/opaque_SUITE_data/src/para_bug/same_type.erl b/lib/dialyzer/test/opaque_SUITE_data/src/para_bug/same_type.erl
new file mode 100644
index 0000000000..855a5d30be
--- /dev/null
+++ b/lib/dialyzer/test/opaque_SUITE_data/src/para_bug/same_type.erl
@@ -0,0 +1,13 @@
+-module(same_type).
+
+-export([t/2]).
+
+-export_type([st/1]).
+
+%% When unopaqued all specializations of st/1 are equal.
+-opaque st(_A) :: {st, tuple()}.
+
+-spec t(_, st(_)) -> _.
+
+t(K, V) ->
+    {K, V}.