Quantum PHP Framework v3.0 (planned for release around end of November) will raise the minimum supported PHP version to 7.4, while maintaining compatibility with PHP 8.0+.

This issue tracks the required upgrades using Rector to refactor and modernize the codebase accordingly.

🎯 Goals:

• Enforce PHP 7.4 as the new minimum requirement
• Ensure forward compatibility with PHP 8.0 and higher
• Apply automated Rector refactoring rules where applicable
• Prepare CI environment to test against multiple PHP versions (7.4, 8.0, 8.1, etc.)

🔧 Tasks:

• Update composer.json to set php: ^7.4
• Add Rector as a dev dependency:

composer require rector/rector --dev

• Create rector.php config with these main rule sets:

LevelSetList::UP_TO_PHP_74
LevelSetList::UP_TO_PHP_80
SetList::CODE_QUALITY
SetList::TYPE_DECLARATION

• Run Rector and review changes:

• vendor/bin/rector process src --dry-run

• Manually fix/refactor edge cases that Rector cannot handle

Update CI pipeline to test on:

• PHP 7.4

• PHP 8.0

• PHP 8.1 (optional)

• Add changelog entry about PHP 7.4+ requirement for v3.0

📌 Notes:

This upgrade must be completed before releasing v3.0
Ensure backward compatibility is not broken unnecessarily

Avoid usage of PHP 8.x-only features (union types, attributes, etc.) in core unless conditionally handled