[PHP-BUG] Bug #78337 [NEW]: Typed properties references inconsistency due to gc

From:             jascha dot php at ja-s dot de
Operating system: 
PHP version:      7.4.0beta1
Package:          PHP Language Specification
Bug Type:         Bug
Bug description:Typed properties references inconsistency due to gc

Description:
------------
I've just looked into PHP 7.4s property typing. I'm a little
disappointed, that this is currently limited to properties, and can not
be applied to any variables.

Luckily v2 supports references to properties. So I'm pretty sure
somebody is gonna provide a little library to construct typed variables
by linkin a variable to the reference set of a typed property.

But what isn't mentioned in the typed_properties_v2 RFC, is how the
garbage collector affects the typing due to reducing the reference set.
This can produce unexpected behavior.


Possible solutions:
* Forbid references:
https://wiki.php.net/rfc/typed_properties_v2#forbid_references
* Add typed variables (seems unlikely, but i'm hoping for this)
* Just document the behavior

Test script:
---------------
https://3v4l.org/ctEgn

Expected result:
----------------
string(3) "123"
string(3) "123"

Actual result:
--------------
int(123)
string(3) "123"

-- 
Edit bug report at https://bugs.php.net/bug.php?id=78337&edit=1
-- 
Try a snapshot (PHP 5.4):   https://bugs.php.net/fix.php?id=78337&r=trysnapshot54
Try a snapshot (PHP 5.5):   https://bugs.php.net/fix.php?id=78337&r=trysnapshot55
Try a snapshot (trunk):     https://bugs.php.net/fix.php?id=78337&r=trysnapshottrunk
Fixed in SVN:               https://bugs.php.net/fix.php?id=78337&r=fixed
Fixed in release:           https://bugs.php.net/fix.php?id=78337&r=alreadyfixed
Need backtrace:             https://bugs.php.net/fix.php?id=78337&r=needtrace
Need Reproduce Script:      https://bugs.php.net/fix.php?id=78337&r=needscript
Try newer version:          https://bugs.php.net/fix.php?id=78337&r=oldversion
Not developer issue:        https://bugs.php.net/fix.php?id=78337&r=support
Expected behavior:          https://bugs.php.net/fix.php?id=78337&r=notwrong
Not enough info:            https://bugs.php.net/fix.php?id=78337&r=notenoughinfo
Submitted twice:            https://bugs.php.net/fix.php?id=78337&r=submittedtwice
register_globals:           https://bugs.php.net/fix.php?id=78337&r=globals
PHP 4 support discontinued: https://bugs.php.net/fix.php?id=78337&r=php4
Daylight Savings:           https://bugs.php.net/fix.php?id=78337&r=dst
IIS Stability:              https://bugs.php.net/fix.php?id=78337&r=isapi
Install GNU Sed:            https://bugs.php.net/fix.php?id=78337&r=gnused
Floating point limitations: https://bugs.php.net/fix.php?id=78337&r=float
No Zend Extensions:         https://bugs.php.net/fix.php?id=78337&r=nozend
MySQL Configuration Error:  https://bugs.php.net/fix.php?id=78337&r=mysqlcfg