Replace zend_object object with its header to prevent the "using flexible array in the middle of another struct" problem in its inheritted classes (static analyzer report)

Class zend_object is defined as a flexible array of length 1. The flexible array defined with size 1 and 0 is not the standard behavior. It is suggested to use the unsized definition (https://people.kernel.org/kees/bounded-flexible-arrays-in-c). Besides, not all its subclasses will use the array field properties_table of the zend_object class. If I understand the code correctly, when the properties_table[0] field is not used, it will store a ZVAL_UNDEF zval indicating the end of the iteration. Whereas when the properties_table[0] field is used, the flags and array length are checked first before accessing the data in the array.

If the properties_table[0] field is not used in these sub-classes, will it be better to replace the zend_object in these classes with only the header part of zend_object?

i.e. (as suggested in case 2 of https://lpc.events/event/18/contributions/1722/attachments/1591/3303/Wfamnae_lpceu2024.pdf)
We can define another struct with only the header part (let's name it zend_object_header_part), but leave the zend_object struct with both the header and the flexible array part.
When only the header is needed, we can use the zend_object_header_part (e.g. in the class inheritance), whereas for those requiring the array part, or using the object through a zend_object pointer, we can still use the full definition.

Usages of zend_object in the middle of other structs whose array field is potentially never used through the composite struct:

• https://github.com/php/php-src/blob/c2fddac8ca2c13b53dfe1044e9355355ae602e30/Zend/zend_generators.h#L58-L59
• https://github.com/php/php-src/blob/c2fddac8ca2c13b53dfe1044e9355355ae602e30/Zend/zend_interfaces.c#L490-L491
• https://github.com/php/php-src/blob/c2fddac8ca2c13b53dfe1044e9355355ae602e30/Zend/zend_closures.c#L31-L32
• https://github.com/php/php-src/blob/c2fddac8ca2c13b53dfe1044e9355355ae602e30/Zend/zend_fibers.h#L102-L104
• https://github.com/php/php-src/blob/c2fddac8ca2c13b53dfe1044e9355355ae602e30/Zend/zend_iterators.h#L64-L65
• https://github.com/php/php-src/blob/c2fddac8ca2c13b53dfe1044e9355355ae602e30/ext/opcache/jit/zend_jit_ir.c#L8451-L8452
• https://github.com/php/php-src/blob/c2fddac8ca2c13b53dfe1044e9355355ae602e30/ext/com_dotnet/com_saproxy.c#L35-L36
• https://github.com/php/php-src/blob/c2fddac8ca2c13b53dfe1044e9355355ae602e30/ext/com_dotnet/php_com_dotnet_internal.h#L28-L29
• https://github.com/php/php-src/blob/c2fddac8ca2c13b53dfe1044e9355355ae602e30/ext/com_dotnet/com_persist.c#L278-L279
• https://github.com/php/php-src/blob/c2fddac8ca2c13b53dfe1044e9355355ae602e30/ext/ffi/ffi.c#L169-L170
• https://github.com/php/php-src/blob/c2fddac8ca2c13b53dfe1044e9355355ae602e30/ext/ffi/ffi.c#L191-L192
• https://github.com/php/php-src/blob/c2fddac8ca2c13b53dfe1044e9355355ae602e30/ext/ffi/ffi.c#L199-L200
• https://github.com/php/php-src/blob/c2fddac8ca2c13b53dfe1044e9355355ae602e30/ext/pdo/php_pdo_driver.h#L645-L646
• https://github.com/php/php-src/blob/c2fddac8ca2c13b53dfe1044e9355355ae602e30/ext/zend_test/fiber.h#L24-L25
• https://github.com/php/php-src/blob/c2fddac8ca2c13b53dfe1044e9355355ae602e30/ext/intl/normalizer/normalizer_class.h#L25-L26
• https://github.com/php/php-src/blob/c2fddac8ca2c13b53dfe1044e9355355ae602e30/ext/intl/locale/locale_class.h#L25-L26

report ids: 250106-1639:1-6,8-17 (16 reports in total)

Comienza con la definición de zend_object y compara los usos comprobados en Zend/zend_generators.h y ext/pdo/php_pdo_driver.h con las estructuras compuestas no comprobadas enumeradas en Zend y ext. Determina qué clases necesitan properties_table, conserva después el objeto completo cuando sea necesario y utiliza en los demás casos una representación que contenga solo la cabecera. La tarea estará completada cuando se hayan resuelto los informes de static-analyzer enumerados sin cambiar el comportamiento.