Problem/Motivation
As #3355675-12: Drupal 9 uses PHP syntax that's deprecated in PHP 8.2, so exclude that from error_reporting() and DeprecationListenerTrait shows, Drupal 9.5 can work on PHP 8.2. However, drupal/core-recommended is incompatible with PHP 8.2, because it constrains to minor versions of Laminas packages whose composer.json requires "php" to be between 7.3 and 8.1. We can't upgrade core's composer.lock to higher minor versions of the Laminas packages, because those drop compatibility with PHP 7.
In #3356283: Fork laminas/laminas-diactoros, we're forking laminas/diactoros in order to have a single version that works (and doesn't have a disclosed security vulnerability) on PHP 7.3 through PHP 8.2.
That will then only leave laminas-feed, laminas-escaper, and laminas-stdlib preventing drupal/core-recommended 9.5 from being PHP 8.2 compatible.
Steps to reproduce
Proposed resolution
Option 1
Remove laminas-feed, laminas-escaper, and laminas-stdlib from drupal/core-recommended. The patch in #21 does this. The downside of this would be that sites (including sites on PHP 8.0 and 8.1) could accidentally update to newer versions of these packages than what's in Drupal core's composer.lock (and therefore, what DrupalCI tests).
Option 2
Fork these libraries similar to #3356283: Fork laminas/laminas-diactoros. While not needed for security, this would allow a single version to work for PHP 7.3 through 8.2, allowing them to remain in drupal/core-recommended, ensuring everyone using drupal/core-recommended is using the versions tested on DrupalCI. The downside would be having to maintain these forks until Drupal 9's EOL.
Remaining tasks
Decide which option to do, and then do it.