1 files changed, 23 insertions, 0 deletions
diff --git a/testsuite/tests/indexed-types/should_compile/T4338.hs b/testsuite/tests/indexed-types/should_compile/T4338.hs
new file mode 100644
index 0000000000..6fa2ae85ac
--- /dev/null
+++ b/testsuite/tests/indexed-types/should_compile/T4338.hs
@@ -0,0 +1,23 @@
+{-# LANGUAGE MultiParamTypeClasses, TypeFamilies, FlexibleContexts #-}
+
+module Main where
+
+class (There a ~ b, BackAgain b ~ a) => Foo a b where
+     type There a
+     type BackAgain b
+     there :: a -> b
+     back :: b -> a
+     tickle :: b -> b
+
+instance Foo Char Int where
+     type There Char = Int
+     type BackAgain Int = Char
+     there = fromEnum
+     back = toEnum
+     tickle = (+1)
+
+test :: (Foo a b) => a -> a
+test = back . tickle . there
+
+main :: IO ()
+main = print $ test 'F'