Add test for Trac #4356

testsuite/tests/ghc-regress/indexed-types/should_compile/T4356.hs

+{-# LANGUAGE TypeFamilies #-}
+module T4356 where
+
+type family T t :: * -> * -> *
+type instance T Bool = (->)
+
+f :: T Bool Bool Bool
+f = not

testsuite/tests/ghc-regress/indexed-types/should_compile/all.T

@@ -155,3 +155,4 @@ test('T3851', normal, compile, [''])
 test('T4178', normal, compile, [''])
 test('T3023', normal, compile, [''])
 test('T4358', normal, compile, [''])
+test('T4356', normal, compile, [''])