Co-authored-by: wazelin <contact@sergeimikhailov.com>

…sses if the appropriate methods are present

This introduces the class flag ZEND_ACC_SUBCLASS_SERIALIZABLE, which
allows classes which are not serializable / deserializable to become
that if a subclass implements the appropriate methods.
Setting this flag through the stubs can be done using
@subclass-serializable.
Introducing this through behaviour a new flag allows for opt-in
behaviour, which is backwards compatible.

Fixes phpGH-8996

Co-authored-by: wazelin <contact@sergeimikhailov.com>

…sses if the appropriate methods are present

This introduces the class flag ZEND_ACC_SUBCLASS_SERIALIZABLE, which
allows classes which are not serializable / deserializable to become
that if a subclass implements the appropriate methods.
Setting this flag through the stubs can be done using
@subclass-serializable.
Introducing this through behaviour a new flag allows for opt-in
behaviour, which is backwards compatible.

Fixes phpGH-8996

Co-authored-by: wazelin <contact@sergeimikhailov.com>

…sses if the appropriate methods are present

This introduces the class flag ZEND_ACC_SUBCLASS_SERIALIZABLE, which
allows classes which are not serializable / deserializable to become
that if a subclass implements the appropriate methods.
Setting this flag through the stubs can be done using
@subclass-serializable.
Introducing this through behaviour a new flag allows for opt-in
behaviour, which is backwards compatible.

Fixes phpGH-8996

Co-authored-by: wazelin <contact@sergeimikhailov.com>

…sses if the appropriate methods are present

This introduces the class flag ZEND_ACC_SUBCLASS_SERIALIZABLE, which
allows classes which are not serializable / deserializable to become
that if a subclass implements the appropriate methods.
Setting this flag through the stubs can be done using
@subclass-serializable.
Introducing this through behaviour a new flag allows for opt-in
behaviour, which is backwards compatible.

Fixes phpGH-8996

Co-authored-by: wazelin <contact@sergeimikhailov.com>

…sses if the appropriate methods are present

This introduces the class flag ZEND_ACC_SUBCLASS_SERIALIZABLE, which
allows classes which are not serializable / deserializable to become
that if a subclass implements the appropriate methods.
Setting this flag through the stubs can be done using
@subclass-serializable.
Introducing this through behaviour a new flag allows for opt-in
behaviour, which is backwards compatible.

Fixes phpGH-8996.

Co-authored-by: wazelin <contact@sergeimikhailov.com>

PHP 8.1 introduced a seemingly unintentional BC break in ca94d55 by
blocking the (un)serialization of DOM objects.
This was done because the serialization never really worked and just
resulted in an empty object, which upon unserialization just resulted in
an object that you can't use.

Users can however implement their own serialization methods, but the
commit made that impossible as the ACC flag gets passed down to the
child class. An approach was tried in php#10307 with a new ACC flag to
selectively allow serialization with subclasses if they implement the
right methods. However, that was found to be too ad hoc.

Instead, let's abuse how the __sleep and __wakeup methods work to throw
the exception instead. If the child class implements the __serialize /
__unserialize method, then the throwing methods won't be called.
Similarly, if the child class implements __sleep and __wakeup, then
they're overridden and it doesn't matter that they throw.

For the user, this PR has the exact same behaviour for (sub)classes that
don't implement the serialization methods: an exception will be thrown.
For code that previously implemented subclasses with these methods, this
approach will make that code work again. This approach should be both BC
preserving and unbreak user's code.

For the test:
Co-authored-by: wazelin <contact@sergeimikhailov.com>

* PHP-8.1:
  Fix GH-8996: DOMNode serialization on PHP ^8.1
  Fix GH-12380: JIT+private array property access inside closure accesses private property in child class

* PHP-8.2:
  Fix GH-8996: DOMNode serialization on PHP ^8.1
  Fix GH-12380: JIT+private array property access inside closure accesses private property in child class

* PHP-8.3:
  Fix GH-8996: DOMNode serialization on PHP ^8.1
  Fix GH-12380: JIT+private array property access inside closure accesses private property in child class

PHP 8.1 introduced a seemingly unintentional BC break in ca94d55 by
blocking the (un)serialization of DOM objects.
This was done because the serialization never really worked and just
resulted in an empty object, which upon unserialization just resulted in
an object that you can't use.

Users can however implement their own serialization methods, but the
commit made that impossible as the ACC flag gets passed down to the
child class. An approach was tried in php#10307 with a new ACC flag to
selectively allow serialization with subclasses if they implement the
right methods. However, that was found to be too ad hoc.

Instead, let's abuse how the __sleep and __wakeup methods work to throw
the exception instead. If the child class implements the __serialize /
__unserialize method, then the throwing methods won't be called.
Similarly, if the child class implements __sleep and __wakeup, then
they're overridden and it doesn't matter that they throw.

For the user, this PR has the exact same behaviour for (sub)classes that
don't implement the serialization methods: an exception will be thrown.
For code that previously implemented subclasses with these methods, this
approach will make that code work again. This approach should be both BC
preserving and unbreak user's code.

For the test:
Co-authored-by: wazelin <contact@sergeimikhailov.com>

php/php-src#8996