Use the PHP 8.3 to 8.5 functions through the Symfony polyfills, and configure Rector accordingly #299

Description

The bundle supports PHP >=8.2, but the Rector configuration is inconsistent with it:

->withPhpVersion(PhpVersion::PHP_85)
->withPhpSets(php82: true)
->withSets([LevelSetList::UP_TO_PHP_82, /* ... */])

withPhpVersion(PHP_85) lets Rector use PHP 8.5 features. This is how array_any() (PHP 8.4) was introduced in ProcessConfiguration by #185, without requiring its polyfill: it only worked because symfony/monolog-bundle installed symfony/polyfill-php84, and it broke the lowest CI job of #269 once this package became optional (replaced by a loop in #296).

The goal is to use the functions of the latest PHP versions (8.3 to 8.5) safely, through the Symfony polyfills, while keeping PHP 8.2 as the minimum version for the syntax.

Proposed fix

• composer.json: require symfony/polyfill-php83, symfony/polyfill-php84 and symfony/polyfill-php85 (^1.33). They are empty on the PHP versions that have the functions natively. They give for instance json_validate(), mb_str_pad(), str_increment() (8.3), array_find(), array_find_key(), array_any(), array_all(), mb_trim(), mb_ucfirst() (8.4), array_first(), array_last(), get_error_handler() (8.5).
• rector.php:
  • withPhpVersion(PhpVersion::PHP_82), the minimum supported version, so that no syntax above PHP 8.2 is used (readonly classes are fine; no typed class constants, property hooks, pipe operator...);
  • withPhpSets() without explicit version (read from composer.json). With withPhpSets(), Rector adds its PHP_POLYFILLS set: the rules using a function of a newer version are applied when composer.json requires the matching symfony/polyfill-phpXX package. An explicit php82: true would be a ceiling and skip them;
  • remove LevelSetList::UP_TO_PHP_82, redundant with withPhpSets().
• Apply Rector. Checked on main (Rector 2.7) with this configuration: only ForeachToArrayAnyRector applies, on the loop of ProcessConfiguration::getDependencyGroups() (back to array_any(), now with its polyfill). The PHP 8.5 rule ArrayFirstLastRector (e.g. $array[array_key_first($array)] → array_first($array)) is not polyfill-aware in Rector yet, so the PHP 8.5 functions can only be used manually for now.
• CI: the lowest job (PHP 8.2) checks that the polyfills are installed.
• Then the same change in the bridge bundles (archive, cache, doctrine, flysystem, rest, soap, ui), one ticket each.

Requirements

• Documentation updates
  • Reference
  • Cookbooks
  • Changelog
• Unit tests

Breaking changes

None: three new small dependencies (polyfills), no change of the minimum PHP version.