dialyzer: Fix another pattern literal bug

dialyzer_typesig:traverse/3 would perform an unsafe optimisation when
given a cons pattern that contained a map and could be folded into a
literal with cerl:fold_literal/1. In this case, when traversing the map
a type variable would be generated, but this variable would be dropped
by the erl_types:t_cons/2 constructor by in turn calling t_sup(),
producing the overapproximation any(). However, in this particular case,
dialyzer_typesig:traverse/3 is not allowed to overapproximate, since its
result is used in an EQ-constraint.

Although erl_types:t_tuple/1 does not overapproximate like t_cons/2,
which makes the bug unlikely to affect tuples too, the fix was
nevertheless applied defensively to the case of tuples as well.

Also, fix a bug where dialyzer_utils:refold_pattern/1 would generate
syntax nodes with two {label, _} attributes.

1 files changed, 50 insertions, 1 deletions

diff --git a/lib/dialyzer/test/map_SUITE_data/src/bug.erl b/lib/dialyzer/test/map_SUITE_data/src/bug.erl
index 9e152bf461..fc32f5641a 100644
--- a/lib/dialyzer/test/map_SUITE_data/src/bug.erl
+++ b/lib/dialyzer/test/map_SUITE_data/src/bug.erl
@@ -1,6 +1,11 @@
 -module(bug).
 
--export([t1/0, f1/1]).
+-export([t1/0, f1/1
+	,t2/0, f2/1
+	,t3/0, f3/1
+	,t4/0, f4/1
+	,t5/0, f5/1
+	]).
 
 t1() ->
     V = f1(#{a=>b}),
@@ -12,3 +17,47 @@ t1() ->
 
 f1(M) -> %% Should get map() succ typing
     #{} = M.
+
+t2() ->
+    V = f2([#{a=>b}]),
+    case V of
+	[#{a := P}] -> P; %% Must not warn here
+	_ -> ok
+    end,
+    ok.
+
+f2(M) -> %% Should get [map(),...] succ typing
+    [#{}] = M.
+
+t3() ->
+    V = f3([#{a=>b},a]),
+    case V of
+	[#{a := P}, _Q] -> P; %% Must not warn here
+	_ -> ok
+    end,
+    ok.
+
+f3(M) -> %% Should get [map()|a,...] succ typing
+    [#{},a] = M.
+
+t4() ->
+    V = f4({#{a=>b},{}}),
+    case V of
+	{#{a := P},{}} -> P; %% Must not warn here
+	_ -> ok
+    end,
+    ok.
+
+f4(M) -> %% Should get {map(),{}} succ typing
+    {#{},{}} = M.
+
+t5() ->
+    V = f5(#{k=>q,a=>b}),
+    case V of
+	#{k := q, a := P} -> P; %% Must not warn here
+	_ -> ok
+    end,
+    ok.
+
+f5(M) -> %% Should get #{k:=q, ...} succ typing
+    #{k:=q} = M.