Type families: test type family with higher kinded parameters

testsuite/tests/ghc-regress/indexed-types/should_compile/Simple6.hs

@@ -2,6 +2,8 @@
 
 module ShouldCompile where
 
+import Data.IORef
+
 data family T a
 data instance T a = T
 
@@ -10,3 +12,6 @@ foo T = T
 
 type family S a
 type instance S a = a
+
+type family SMRef (m:: * -> *) :: * -> *
+type instance SMRef IO = IORef 
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