Fix crash when using remote types in the tail of list types

Hans Bolider reported a dialyzer crash when using a remote type in
the tail position of a maybe_improper_list() declaration. A test
was created (by extending an existing module of the testsuite)
and erl_types was modified to expand the remote type and not pass
it unexpanded to subsequent phases in the processing.

2 files changed, 21 insertions, 9 deletions

diff --git a/lib/dialyzer/test/small_SUITE_data/src/maybe_improper.erl b/lib/dialyzer/test/small_SUITE_data/src/maybe_improper.erl
index 1743d81493..6d2a35b7c8 100644
--- a/lib/dialyzer/test/small_SUITE_data/src/maybe_improper.erl
+++ b/lib/dialyzer/test/small_SUITE_data/src/maybe_improper.erl
@@ -1,7 +1,18 @@
+%%%========================================================================
+%%% Tests handling of maybe improper lists
+%%%========================================================================
 -module(maybe_improper).
 
--export([s/1]).
+-export([s/1, t/0]).
 
 -spec s(maybe_improper_list(X,Y)) -> {[X], maybe_improper_list(X,Y)}.
-s(A) ->
-    lists:split(2,A).
+s(L) ->
+    lists:split(2, L).
+
+%% Having a remote type in the 'tail' of the list crashed dialyzer.
+%% The problem was fixed for R16B03.
+-type t_mil() :: maybe_improper_list(integer(), orddict:orddict()).
+
+-spec t() -> t_mil().
+t() ->
+    [42 | []].
diff --git a/lib/hipe/cerl/erl_types.erl b/lib/hipe/cerl/erl_types.erl
index d1243b2325..d7d8a878c5 100644
--- a/lib/hipe/cerl/erl_types.erl
+++ b/lib/hipe/cerl/erl_types.erl
@@ -671,8 +671,9 @@ t_solve_remote(?function(Domain, Range), ET, R, C) ->
   {RT2, RR2} = t_solve_remote(Range, ET, R, C),
   {?function(RT1, RT2), RR1 ++ RR2};
 t_solve_remote(?list(Types, Term, Size), ET, R, C) ->
-  {RT, RR} = t_solve_remote(Types, ET, R, C),
-  {?list(RT, Term, Size), RR};
+  {RT1, RR1} = t_solve_remote(Types, ET, R, C),
+  {RT2, RR2} = t_solve_remote(Term, ET, R, C),
+  {?list(RT1, RT2, Size), RR1 ++ RR2};
 t_solve_remote(?product(Types), ET, R, C) ->
   {RL, RR} = list_solve_remote(Types, ET, R, C),
   {?product(RL), RR};
@@ -1349,8 +1350,8 @@ t_maybe_improper_list() ->
 t_maybe_improper_list(_Content, ?unit) -> ?none;
 t_maybe_improper_list(?unit, _Termination) -> ?none;
 t_maybe_improper_list(Content, Termination) ->
-  %% Safety check
-  true = t_is_subtype(t_nil(), Termination),
+  %% Safety check: would be nice to have but does not work with remote types
+  %% true = t_is_subtype(t_nil(), Termination),
   ?list(Content, Termination, ?unknown_qual).
 
 -spec t_is_maybe_improper_list(erl_type()) -> boolean().
@@ -1365,8 +1366,8 @@ t_is_maybe_improper_list(_) -> false.
 %% t_improper_list(?unit, _Termination) -> ?none;
 %% t_improper_list(_Content, ?unit) -> ?none;
 %% t_improper_list(Content, Termination) ->
-%%   %% Safety check
-%%   false = t_is_subtype(t_nil(), Termination),
+%%   %% Safety check: would be nice to have but does not work with remote types
+%%   %% false = t_is_subtype(t_nil(), Termination),
 %%   ?list(Content, Termination, ?any).  
 
 -spec lift_list_to_pos_empty(erl_type()) -> erl_type().