1 files changed, 20 insertions, 0 deletions
diff --git a/testsuite/tests/gadt/T15009.hs b/testsuite/tests/gadt/T15009.hs
new file mode 100644
index 0000000000..58e17af864
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+++ b/testsuite/tests/gadt/T15009.hs
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+{-# LANGUAGE GADTs #-}
+
+module T15009 where
+
+-- T2 is an ordinary H98 data type,
+-- and f2 should typecheck with no problem
+data T2 a where
+  MkT2 :: a -> T2 a
+
+f2 (MkT2 x) = not x
+
+-- T1 is a GADT, but the equality is really just a 'let'
+-- so f1 should also typecheck no problem
+data T1 a where
+  MkT1 :: b ~ a => b -> T1 a
+
+f1 (MkT1 x) = not x
+
+
+