Currently, internal classes are registered with the following code:
INIT_CLASS_ENTRY(ce, "InternalClass", class_InternalClass_methods);
class_entry = zend_register_internal_class_ex(&ce, NULL);
class_entry->ce_flags |= ...;
This has worked well so far, except if InternalClass is readonly. It is because some inheritance checks are run by zend_register_internal_class_ex before ZEND_ACC_READONLY_CLASS is added to ce_flags.
The issue is fixed by adding a zend_register_internal_class_with_flags() zend API function that stubs can use from now on. This function makes sure to add the flags before running any checks. Since the new API is not available in lower PHP versions, gen_stub.php has to keep support for the existing API for PHP 8.3 and below.
This moves the new method from magically being added to the PDO class from the driver to just be available on the dedicated subclass.
Drive-by fixes to NEWS and UPGRADING
Máté Kocsis