This issue is created to coordinate efforts and have one space to reference to all of the PR's aiming to use PHP7.4 syntax in Sylius

Hello, folks! 👋

I've decided to open this issue, to be transparent with our efforts to finally use PHP 7.4 syntax on all Sylius' supported repositories. Let's face the truth - it's a little bit late 💃 But, on the other hand, better late than never 🐎

I already started the work, with this PR on SyliusResourceBundle. The path I chose is to use rectorphp, as it's working spectacularly with the code syntax upgrade. There are some things needed to be done additionally (probably upgrading PHPStan or other coding-standard relate libraries), but it should not be a big problem.

Feel free to participate, if you like to 🎉 I'm also sure, that we can do better (and faster) when we decide to bump the minimal PHP version to 8.0 (active support of PHP 7.4 ends at the end of November ⚠️) 💪

To-do:

• https://github.com/Sylius/SyliusResourceBundle/ - Use PHP 7.4 syntax SyliusResourceBundle#328
• https://github.com/Sylius/SyliusGridBundle/ - Use PHP 7.4 syntax SyliusGridBundle#171
• https://github.com/Sylius/SyliusMailerBundle/ (bump to PHP 7.4 needed as well) - Bump PHP version and use PHP 7.4 syntax SyliusMailerBundle#99
• https://github.com/Sylius/SyliusThemeBundle - Use PHP 7.4 syntax SyliusThemeBundle#110
• https://github.com/Sylius/SyliusFixturesBundle (bump to PHP 7.4 needed as well) - Bump PHP to 7.4 and use its syntax SyliusFixturesBundle#66
• https://github.com/Sylius/Sylius/ - Use PHP 7.4 syntax in Sylius components #13012, PHP 7.4 syntax in Sylius bundles vol.1 #13038, PHP 7.4 syntax in bundles vol.2 #13039, PHP 7.4 syntax in bundles vol.3 #13040, PHP 7.4 syntax in Behat #13116
• https://github.com/Sylius/SyliusDemo/ - Use PHP7.4 syntax SyliusDemo#210
• https://github.com/Sylius/PayPalPlugin/ (bump to PHP 7.4 needed as well) - Bump PHP to 7.4 and use its syntax PayPalPlugin#211
• https://github.com/Sylius/RefundPlugin/ - Use PHP 7.4 syntax RefundPlugin#330
• https://github.com/Sylius/InvoicingPlugin/ - Use PHP 7.4 syntax InvoicingPlugin#249

Live long and prosper, Sylius Community 🖖 🚀