1 files changed, 21 insertions, 0 deletions
diff --git a/testsuite/tests/typecheck/should_compile/T4917.hs b/testsuite/tests/typecheck/should_compile/T4917.hs
new file mode 100644
index 0000000000..f6d51d4c27
--- /dev/null
+++ b/testsuite/tests/typecheck/should_compile/T4917.hs
@@ -0,0 +1,21 @@
+{-# LANGUAGE GADTs, ScopedTypeVariables, EmptyDataDecls, RankNTypes #-}
+
+module T4917 where
+
+-- only works on ghc6 but not on ghc7
+type Const a b = a
+
+newtype Fix f n = In { out :: f (Fix f) n }
+
+mcata :: forall f a b .
+         (forall x c . (forall d . x d -> Const b d) -> f x c -> Const b c)
+      -> Fix f a -> Const b a
+mcata f x = f {- x=(Fix f), c=a -} mcataf outx
+  where
+    outx :: f (Fix f) a
+    outx = out x
+
+    mcataf :: forall d. Fix f d -> Const b d
+    mcataf y = mcata {- f=f, a=d, b=b0 -} f (y :: Fix f d)
+    -- Const b d ~ Const b0 d
+    -- Expected type of f :: forall x c. (forall d. x d -> Const b0 d) -> f x c -> Const b0 c