upgrade to php 8.1

[steamboatid]

dear all,

i manage to upgrade sabberworm/PHP-CSS-Parser to php 8.1
you may find my repo at steamboatid/PHP-CSS-Parser

i did 4 phase modifications :

phase 1 :

• create dedicated lxc with php 7.4.30.
• fresh clone main repo, install all packages needed, do phpunit test.
• create phpstan baseline
• run phpunit test again, to make sure all test passed
• do simple refactor using rector, just to insert arguments type at functions.
• exec phpstan and fix all of phpstan reports
• exec composer fix:php
• exec phpunit test until all test passed

phase 2 :

• upgrade phpunit to phpunit 7.1.5
• exec phpstan and fix all of phpstan reports
• exec composer fix:php
• exec phpunit test until all test passed

phase 3 :

• create lxc with php 8.1.7 from sury.org
• exec phpstan and fix all of phpstan reports
• exec composer fix:php
• exec phpunit test until all test passed

phase 4 :

• upgrade phpunit to 8.5.27
• exec phpunit test until all test passed

precautions :

• it may not compatible with php below 8.1
• i only test with with phpunit and not yet tested with real applications

[oliverklee]

Hi @steamboatid, thanks for digging into this!

Concerning the minimum supported PHP version this library needs to support, we had a discussion about this roughly one year ago: #251

Basically, it boils down to "we need to support the lowest PHP version that still has at least 5% usage share with WordPress" (because this library is used by WordPress).

As of today, PHP 5.6 still has a share of 5.97%, and is (very) slowly going down. As PHP 7.0 and 7.1 both have a very low share, we can bump the minimum PHP version to 7.2 hopefully sometime soon.

[oliverklee]

We have now raised the PHP requirement to >= 7.2 and support PHP up to 8.3 (as covered by tests). Closing.