Test Trac #7939

testsuite/tests/ghci/scripts/T7939.hs

+{-# LANGUAGE TypeFamilies, PolyKinds #-}
+
+module T7939 where
+
+class Foo a where
+   type Bar a
+
+

testsuite/tests/ghci/scripts/T7939.script

+:l T7939
+:i Bar
+:k Bar

testsuite/tests/ghci/scripts/T7939.stdout

+class Foo (k :: BOX) (a :: k) where
+  type family Bar (k :: BOX) (k :: BOX) (a :: k) :: k
+  	-- Defined at T7939.hs:6:9
+Bar :: k1 -> k

testsuite/tests/ghci/scripts/all.T

@@ -149,4 +149,5 @@ test('T7586', normal, ghci_script, ['T7586.script'])
 test('T4175', normal, ghci_script, ['T4175.script'])
 test('T7872', normal, ghci_script, ['T7872.script'])
 test('T7873', normal, ghci_script, ['T7873.script'])
+test('T7939', normal, ghci_script, ['T7939.script'])