Test Trac #12867

testsuite/tests/indexed-types/should_fail/T12867.hs

+{-# LANGUAGE TypeFamilies #-}
+{-# LANGUAGE ConstraintKinds #-}
+{-# LANGUAGE FlexibleContexts #-}
+
+module T12866 where
+
+type Test2 a = (Eq (TestM a))
+
+class Test a where
+    type TestM :: *

testsuite/tests/indexed-types/should_fail/T12867.stderr

+
+T12867.hs:7:21: error:
+    • Expecting one fewer arguments to ‘TestM’
+      Expected kind ‘k0 -> *’, but ‘TestM’ has kind ‘*’
+    • In the first argument of ‘Eq’, namely ‘TestM a’
+      In the type ‘Eq (TestM a)’
+      In the type declaration for ‘Test2’
+
+T12867.hs:9:1: error:
+    • The associated type ‘TestM’
+      mentions none of the type or kind variables of the class ‘Test a’
+    • In the class declaration for ‘Test’

testsuite/tests/indexed-types/should_fail/all.T

@@ -139,3 +139,4 @@ test('T7788', normal, compile_fail, [''])
 test('T11450', normal, compile_fail, [''])
 test('T12041', normal, compile_fail, [''])
 test('T12522a', normal, compile_fail, [''])
+test('T12867', normal, compile_fail, [''])