Test Trac #8391

testsuite/tests/polykinds/T8391.hs

+{-# LANGUAGE FunctionalDependencies, FlexibleInstances, 
+             TypeFamilies,
+             PolyKinds #-}
+
+module T8391 where
+
+type  Foo a = a
+
+class Bar a b | a -> b
+
+instance Bar a (Foo a)

testsuite/tests/polykinds/all.T

@@ -91,3 +91,4 @@ test('T7973', normal, compile,['-O'])
 test('T7939a', normal, compile_fail, [''])
 test('T8132', normal, compile_fail, [''])
 test('T8359', normal, compile, [''])
+test('T8391', normal, compile, [''])