1 files changed, 21 insertions, 0 deletions
diff --git a/testsuite/tests/indexed-types/should_fail/NoMatchErr.hs b/testsuite/tests/indexed-types/should_fail/NoMatchErr.hs
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index 0000000000..304e11613e
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+++ b/testsuite/tests/indexed-types/should_fail/NoMatchErr.hs
@@ -0,0 +1,21 @@
+{-# LANGUAGE NoMonomorphismRestriction #-}
+{-# LANGUAGE TypeFamilies #-}
+
+-- Type error message looks like
+-- 	TF.hs:12:11:
+--    Couldn't match expected type `Memo d'
+--           against inferred type `Memo d1'
+--      NB: `Memo' is a (non-injective) type function
+--
+-- Note the "NB", which helps point out the problem
+
+module Foo where
+
+class Fun d where
+    type Memo d :: * -> *
+    abst :: (d -> a) -> Memo d a
+    appl :: Memo d a -> (d -> a)
+
+f ::  (Fun d) => Memo d a -> Memo d a    -- (1)
+f = abst . appl
+