From d57f5e34e58a49298c2c2d6210392df6629a740b Mon Sep 17 00:00:00 2001
From: Hans Bolinder <hasse@erlang.org>
Date: Wed, 2 Sep 2015 15:21:47 +0200
Subject: dialyzer: Correct the handling of parameters of opaque types

Prior to this commit, the fact that parameters of opaque types are
expanded differently depending on the current values of limits used
during expansion, caused problems later when the types of parameters
are used for determining if opaque types are comparable.
---
 lib/hipe/cerl/erl_types.erl | 82 ++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 81 insertions(+), 1 deletion(-)

diff --git a/lib/hipe/cerl/erl_types.erl b/lib/hipe/cerl/erl_types.erl
index 56ec757dbf..cd2d2fe207 100644
--- a/lib/hipe/cerl/erl_types.erl
+++ b/lib/hipe/cerl/erl_types.erl
@@ -2712,7 +2712,87 @@ is_compat_args([], []) -> true;
 is_compat_args(_, _) -> false.
 
 is_compat_arg(A, A) -> true;
-is_compat_arg(A1, A2) -> t_is_any(A1) orelse t_is_any(A2).
+is_compat_arg(A1, A2) ->
+  is_specialization(A1, A2) orelse is_specialization(A2, A1).
+
+-spec is_specialization(erl_type(), erl_type()) -> boolean().
+
+%% Returns true if the first argument is a specialization of the
+%% second argument in the sense that every type is a specialization of
+%% any(). For example, {_,_} is a specialization of any(), but not of
+%% tuple(). Does not handle variables, but any() and unions (sort of).
+
+is_specialization(_, ?any) -> true;
+is_specialization(?any, _) -> false;
+is_specialization(?function(Domain1, Range1), ?function(Domain2, Range2)) ->
+  (is_specialization(Domain1, Domain2) andalso
+   is_specialization(Range1, Range2));
+is_specialization(?list(Contents1, Termination1, Size1),
+                  ?list(Contents2, Termination2, Size2)) ->
+  (Size1 =:= Size2 andalso
+   is_specialization(Contents1, Contents2) andalso
+   is_specialization(Termination1, Termination2));
+is_specialization(?product(Types1), ?product(Types2)) ->
+  specialization_list(Types1, Types2);
+is_specialization(?tuple(?any, ?any, ?any), ?tuple(_, _, _)) -> false;
+is_specialization(?tuple(_, _, _), ?tuple(?any, ?any, ?any)) -> false;
+is_specialization(?tuple(Elements1, Arity, _), 
+                  ?tuple(Elements2, Arity, _)) when Arity =/= ?any ->
+  specialization_list(Elements1, Elements2);
+is_specialization(?tuple_set([{Arity, List}]), 
+                  ?tuple(Elements2, Arity, _)) when Arity =/= ?any ->
+  specialization_list(sup_tuple_elements(List), Elements2);
+is_specialization(?tuple(Elements1, Arity, _),
+                  ?tuple_set([{Arity, List}])) when Arity =/= ?any ->
+  specialization_list(Elements1, sup_tuple_elements(List));
+is_specialization(?tuple_set(List1), ?tuple_set(List2)) ->
+  try
+    specialization_list(lists:append([T || {_Arity, T} <- List1]),
+                        lists:append([T || {_Arity, T} <- List2]))
+  catch _:_ -> false
+  end;
+is_specialization(?union(List1)=T1, ?union(List2)=T2) ->
+  case specialization_union2(T1, T2) of
+    {yes, Type1, Type2} -> is_specialization(Type1, Type2);
+    no -> specialization_list(List1, List2)
+  end;
+is_specialization(?union(List), T2) ->
+  case unify_union(List) of
+      {yes, Type} -> is_specialization(Type, T2);
+      no -> false
+  end;
+is_specialization(T1, ?union(List)) ->
+  case unify_union(List) of
+      {yes, Type} -> is_specialization(T1, Type);
+      no -> false
+  end;
+is_specialization(?opaque(_) = T1, T2) ->
+  is_specialization(t_opaque_structure(T1), T2);
+is_specialization(T1, ?opaque(_) = T2) ->
+  is_specialization(T1, t_opaque_structure(T2));
+is_specialization(?var(_), _) -> exit(error);
+is_specialization(_, ?var(_)) -> exit(error);
+is_specialization(T, T) -> true;
+is_specialization(?none, _) -> false;
+is_specialization(_, ?none) -> false;
+is_specialization(?unit, _) -> false;
+is_specialization(_, ?unit) -> false;
+is_specialization(#c{}, #c{}) -> false.
+
+specialization_list(L1, L2) ->
+  length(L1) =:= length(L2) andalso specialization_list1(L1, L2).
+
+specialization_list1([], []) -> true;
+specialization_list1([T1|L1], [T2|L2]) ->
+  is_specialization(T1, T2) andalso specialization_list1(L1, L2).
+
+specialization_union2(?union(List1)=T1, ?union(List2)=T2) ->
+  case {unify_union(List1), unify_union(List2)} of
+    {{yes, Type1}, {yes, Type2}} -> {yes, Type1, Type2};
+    {{yes, Type1}, no} -> {yes, Type1, T2};
+    {no, {yes, Type2}} -> {yes, T1, Type2};
+    {no, no} -> no
+  end.
 
 -spec t_inf_lists([erl_type()], [erl_type()]) -> [erl_type()].
 
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