Test Trac #6021

testsuite/tests/polykinds/T6021.hs

+{-# LANGUAGE KindSignatures, MultiParamTypeClasses #-}
+module T6021 where
+
+class Panic a b
+instance Panic (a :: b) b

testsuite/tests/polykinds/T6021.stderr

+
+T6021.hs:5:22:
+    Type variable `b' used as a kind
+    In the kind `b'
+    In the instance declaration for `Panic (a :: b) b'

testsuite/tests/polykinds/all.T

@@ -40,3 +40,4 @@ test('T6036', normal, compile, [''])
 test('T6025', normal, run_command, ['$MAKE -s --no-print-directory T6025'])
 test('T6002', normal, compile, [''])
 test('T6039', normal, compile_fail, [''])
+test('T6021', normal, compile_fail, [''])