1 files changed, 30 insertions, 0 deletions
diff --git a/testsuite/tests/gadt/equal.hs b/testsuite/tests/gadt/equal.hs
new file mode 100644
index 0000000000..b6c0bf572e
--- /dev/null
+++ b/testsuite/tests/gadt/equal.hs
@@ -0,0 +1,30 @@
+{-# LANGUAGE GADTs #-}
+
+module ShouldCompile where
+
+data Rep t where
+  Rint :: Rep Int
+  Rchar :: Rep Char
+  Runit :: Rep ()
+  Rpair :: Rep a -> Rep b -> Rep (a,b)
+  Rsum  :: Rep a -> Rep b -> Rep (Either a b)
+  Rcon  :: String -> Rep t -> Rep t
+
+data Equal a b where
+   Eq :: Equal c c 
+
+test :: Rep a -> Rep b -> Maybe (Equal a b)
+test Rint  Rint  = return Eq
+test Rchar Rchar = return Eq
+test Runit Runit = return Eq
+test (Rpair x y) (Rpair a b)
+  = do { Eq <- test x a; Eq <- test y b; return Eq }
+test (Rsum x y) (Rsum a b)
+  = do { Eq <- test x a; Eq <- test y b; return Eq }
+test (Rcon s1 x) (Rcon s2 y)
+  = if s1==s2 then test x y else Nothing
+test _ _ = Nothing
+
+f :: Equal a b -> a -> b -> b
+f Eq x y = x
+