Add PHP 8 Support / WIP

[ichiriac]

Prepare the parser to PHP 8 :

• https://wiki.php.net/rfc/union_types_v2

Work In Progress as RFC are not yet closed

[Selion05]

https://wiki.php.net/rfc/nullsafe_operator

What is the status about php 8 support?

[Wulfheart]

What’s new in PHP8?

• Named arguments
• Attributes
• Constructor property promotion
• Union types
• Match expression
• Nullsafe operator

I’d suggest creating an separate issue for each if these features.

Compiled from https://www.php.net/releases/8.0/en.php

[cseufert]

There are now patches available for:

• named arguments feat(php8): named arguments #673
• property promotion c1 feat(php8): promoted params v2 #697
• union types PHP8: Union types support #656 (merged in php8 staging branch)
• match expression feat(php8): match expression #686
• nullsafe operator add php8 nullsafe operator #662 (merged in php8 staging branch)

so really the work just needs to focus on attributes, however I am not sure the right way to update the lexer to support Attributes.

[czosel]

Hi @cseufert
Awesome work! #662 has been merged in a temporary php8 branch because I don't know the codebase well enough to just merge stuff into master before @ichiriac took a look as well. If you like, you can point your PRs to the php8 branch as well, and I'll try to find some time for a first review :)

[cseufert]

I have changed the following PR's to merge to the php8 branch:

• feat(php8): match expression #686 Match expression
• feat(php8): promoted params v2 #697 Promoted properties v2

I am going to have a go at getting this stuff working in prettier at some point, and am looking foward to having someone who know the codebase have a review of the code. I feel it could benefit a lot from being ported to typescript, but I guess thats a totally different problem.