Test Trac #6022

testsuite/tests/typecheck/should_fail/T6022.hs

+module T6022 where
+
+f x = x == head

testsuite/tests/typecheck/should_fail/T6022.stderr

+
+T6022.hs:3:9:
+    No instance for (Eq ([a] -> a)) arising from a use of `=='
+    Possible fix: add an instance declaration for (Eq ([a] -> a))
+    In the expression: x == head
+    In an equation for `f': f x = x == head

testsuite/tests/typecheck/should_fail/all.T

@@ -273,3 +273,4 @@ test('T5684', normal, compile_fail, [''])
 test('T5858', normal, compile_fail, [''])
 test('T5957', normal, compile_fail, [''])
 test('T6001', normal, compile_fail, [''])
+test('T6022', normal, compile_fail, [''])