Add test for #11319

testsuite/tests/typecheck/should_compile/T11319.hs

+{-# LANGUAGE ImpredicativeTypes #-}
+
+module T11319 where
+
+f :: Monad m => m (Maybe a)
+f = return Nothing

testsuite/tests/typecheck/should_compile/all.T

@@ -500,6 +500,7 @@ test('T11462',
 test('T11480', normal, compile, [''])
 test('RebindHR', normal, compile, [''])
 test('RebindNegate', normal, compile, [''])
+test('T11319', expect_broken(11319), compile, [''])
 test('T11397', normal, compile, [''])
 test('T11458', normal, compile, [''])
 test('T11524', normal, compile, [''])