dialyzer: fix a -Wunderspecs bug

Sometimes bogus warnings were generated for parametrized types.

Thanks to Krzesimir Sarnecki for pointing the bug out.

Also corrected warnings where the structure of opaque types were
exposed (thanks to Kostis for pointing the bug out).

2 files changed, 45 insertions, 0 deletions

diff --git a/lib/dialyzer/test/underspecs_SUITE_data/results/arr b/lib/dialyzer/test/underspecs_SUITE_data/results/arr
new file mode 100644
index 0000000000..9497d12eec
--- /dev/null
+++ b/lib/dialyzer/test/underspecs_SUITE_data/results/arr
@@ -0,0 +1,4 @@
+
+arr.erl:14: Type specification arr:test2(array:array(T),non_neg_integer(),T) -> array:array(T) is a supertype of the success typing: arr:test2(array:array(_),pos_integer(),_) -> array:array(_)
+arr.erl:24: Type specification arr:test4(array:array(T),non_neg_integer(),_) -> array:array(T) is a supertype of the success typing: arr:test4(array:array(_),pos_integer(),_) -> array:array(_)
+arr.erl:29: Type specification arr:test5(array:array(T),non_neg_integer(),T) -> array:array(T) is a supertype of the success typing: arr:test5(array:array(_),non_neg_integer(),integer()) -> array:array(_)
diff --git a/lib/dialyzer/test/underspecs_SUITE_data/src/arr.erl b/lib/dialyzer/test/underspecs_SUITE_data/src/arr.erl
new file mode 100644
index 0000000000..3b265ccec2
--- /dev/null
+++ b/lib/dialyzer/test/underspecs_SUITE_data/src/arr.erl
@@ -0,0 +1,41 @@
+-module(arr).
+
+%% http://erlang.org/pipermail/erlang-questions/2014-August/080445.html
+
+-define(A, array).
+
+-export([test/3, test2/3, test3/3, test4/3, test5/3, test6/3]).
+
+-spec test(?A:array(T), non_neg_integer(), T) -> ?A:array(T).
+
+test(Array, N, Value) ->
+    ?A:set(N, Value, Array).
+
+-spec test2(?A:array(T), non_neg_integer(), T) -> ?A:array(T).
+
+test2(Array, N, Value) when N > 0 ->
+    ?A:set(N, Value, Array).
+
+-spec test3(?A:array(T), non_neg_integer(), _) -> ?A:array(T).
+
+test3(Array, N, Value) ->
+    ?A:set(N, Value, Array).
+
+-spec test4(?A:array(T), non_neg_integer(), _) -> ?A:array(T).
+
+test4(Array, N, Value) when N > 0 ->
+    ?A:set(N, Value, Array).
+
+-spec test5(?A:array(T), non_neg_integer(), T) -> ?A:array(T).
+
+test5(Array, N, Value) when is_integer(Value) ->
+    ?A:set(N, Value, Array).
+
+%% One would ideally want a warning also for test6(), but the current
+%% analysis of parametrized opaque types is not strong enough to
+%% discover this.
+-spec test6(?A:array(integer()), non_neg_integer(), integer()) ->
+                   ?A:array(any()).
+
+test6(Array, N, Value) ->
+     ?A:set(N, Value, Array).