anchor.diff:  main() {
     defineReflectiveSuite(() {
       defineReflectiveTests(ConflictingGenericInterfacesTest);
  -    defineReflectiveTests(ConflictingGenericInterfacesWithNullSafetyTest);
     });
   }
   
   @reflectiveTest
   class ConflictingGenericInterfacesTest extends PubPackageResolutionTest
  -    with WithoutNullSafetyMixin {
  +    with WithNonFunctionTypeAliasesMixin {
     test_class_extends_implements() async {
       await assertErrorsInCode('''
   class I<T> {}
  
positive.code: 
  class C extends B implements A<int> {}
  ''');
    }
  
    test_class_mixed_viaLegacy() async {
  
negative.code:     ]);
    }
  
    test_class_extends_implements_never() async {
      await assertNoErrorsInCode('''
  class I<T> {}
  