1 files changed, 28 insertions, 0 deletions
diff --git a/testsuite/tests/pmcheck/should_compile/T4139.hs b/testsuite/tests/pmcheck/should_compile/T4139.hs
new file mode 100644
index 0000000000..4f6d4abab5
--- /dev/null
+++ b/testsuite/tests/pmcheck/should_compile/T4139.hs
@@ -0,0 +1,28 @@
+{-# LANGUAGE GADTs #-}
+{-# OPTIONS_GHC -fwarn-incomplete-patterns #-}
+
+module T4139 where
+
+data F a where
+  FInt :: F Int
+  FBool :: F Bool
+
+class Baz a where
+  baz :: F a -> G a
+instance Baz Int where
+  baz _ = GInt
+instance Baz Bool where
+  baz _ = GBool
+
+data G a where
+  GInt :: G Int
+  GBool :: G Bool
+
+bar :: Baz a => F a -> ()
+bar a@(FInt) =
+  case baz a of
+    GInt -> ()
+    -- GBool -> ()
+bar _ = ()
+
+