proc_open inaccessible cwd behavior change in 8.3

Description

As of PHP8.3, the following code:

<?php
$descriptorspec = array();
$cwd = '/inaccessible/dir/';
$process = proc_open('/usr/bin/env php -r ""', $descriptorspec, $pipes, $cwd);
proc_close($process);

Resulted in this output:

PHP Warning:  proc_open(): posix_spawn() failed: No such file or directory in /home/hans/test/test.php on line 4
PHP Fatal error:  Uncaught TypeError: proc_close(): Argument #1 ($process) must be of type resource, false given in /home/hans/test/test.php:5
Stack trace:
#0 /home/hans/test/test.php(5): proc_close()
#1 {main}
  thrown in /home/hans/test/test.php on line 5

But in PHP<8.3, it results in no output whatsoever, and proc_open succeeds.

This behavior change breaks real code in the wild: https://github.com/chrome-php/wrench/pull/20

While I think the behavior change is good, I also think a E_DEPRECATED period is warranted, something like

Requesting an inaccessible working dir ($cwd) has been deprecated and will stop working in a future version of PHP

• Also for some unknown reason, when I test this locally, i get the posix_spawn() error, but when I test on Github CI, i don't get the posix_spawn() error (but proc_open() still fails.. silently.)

PHP Version

PHP8.3.0

Operating System

Ubuntu (both 22.04 and 24.04-beta)

Start by running the supplied proc_open() and proc_close() reproduction on Ubuntu with PHP 8.3, using the inaccessible cwd and comparing local and GitHub CI results. Trace the proc_open() behavior around the posix_spawn() failure, then define the expected deprecation or failure behavior and add coverage for the differing outcomes.