Test Trac #8963

testsuite/tests/deriving/should_compile/T8963.hs

+{-# LANGUAGE TypeFamilies, GeneralizedNewtypeDeriving #-}
+
+module T8963 where
+
+class C c where
+   data F c r
+
+instance C Int where
+   newtype F Int r = F (IO r) deriving (Functor)

testsuite/tests/deriving/should_compile/all.T

@@ -48,3 +48,4 @@ test('T8678', normal, compile, [''])
 test('T8865', normal, compile, [''])
 test('T8893', normal, compile, [''])
 test('T8950', expect_broken(8950), compile, [''])
+test('T8963', normal, compile, [''])