1 files changed, 22 insertions, 0 deletions
diff --git a/lib/dialyzer/test/small_tests_SUITE_data/src/confusing_warning.erl b/lib/dialyzer/test/small_tests_SUITE_data/src/confusing_warning.erl
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index 0000000000..c82df0f056
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+++ b/lib/dialyzer/test/small_tests_SUITE_data/src/confusing_warning.erl
@@ -0,0 +1,22 @@
+%% Test case that results in a confusing warning -- created from a
+%% very stripped down actual application. The second case clause of
+%% test/1 cannot possibly match because all a-pairs match with the
+%% first clause. Dialyzer complains that the second argument of the
+%% second 2-tuple has type 'aaa' | 'bbb'. This is mucho confusing
+%% since there is no 'a'-pair whose second element is 'aaa' | 'bbb'.
+%% Pattern matching compilation is of course what's to blame here.
+
+-module(confusing_warning).
+-export([test/1]).
+
+test(N) when is_integer(N) ->
+  case foo(N) of
+    {a, I} when is_integer(I) ->
+      I;
+    {a, {_, L}} ->	% this clause cannot possibly match
+      L
+  end.
+
+foo(1) -> {a, 42};
+foo(2) -> {b, aaa};	% this is really unused
+foo(3) -> {b, bbb}.	% this is really unused