W.I.P. variance checks for associated types

Author: Girgias

Diff for: Zend/zend_inheritance.c

@@ -675,6 +675,22 @@ static inheritance_status zend_is_intersection_subtype_of_type(
 	return early_exit_status == INHERITANCE_ERROR ? INHERITANCE_SUCCESS : INHERITANCE_ERROR;
 }
 
+static inheritance_status zend_is_type_subtype_of_associated_type(
+	zend_class_entry *concrete_scope,
+	const zend_type *concrete_type_ptr,
+	const zend_type *associated_type_ptr,
+	HashTable *associated_types
+) {
+	const zend_type associated_type = *associated_type_ptr;
+	const zend_type concrete_type = *concrete_type_ptr;
+
+	ZEND_ASSERT(ZEND_TYPE_HAS_NAME(associated_type));
+
+	zend_string *associated_type_name = ZEND_TYPE_NAME(associated_type);
+
+	return INHERITANCE_ERROR;
+}
+
 ZEND_API inheritance_status zend_perform_covariant_type_check(
 		zend_class_entry *fe_scope, const zend_type *fe_type_ptr,
 		zend_class_entry *proto_scope, const zend_type *proto_type_ptr)
@@ -690,6 +706,11 @@ ZEND_API inheritance_status zend_perform_covariant_type_check(
 		return INHERITANCE_SUCCESS;
 	}
 
+	if (ZEND_TYPE_IS_ASSOCIATED(proto_type)) {
+		return zend_is_type_subtype_of_associated_type(
+			fe_scope, fe_type_ptr, proto_type_ptr, proto_scope->associated_types);
+	}
+
 	/* Builtin types may be removed, but not added */
 	uint32_t fe_type_mask = ZEND_TYPE_PURE_MASK(fe_type);
 	uint32_t proto_type_mask = ZEND_TYPE_PURE_MASK(proto_type);