feat: treat void as null for null coalescing operator

[kesselb]

Hi 👋

WordPress often uses type definitions like array|void (e.g. https://github.com/WordPress/wordpress-develop/blob/68be569925ad2a88c97e1308b8a67a57bf17a14f/src/wp-includes/post.php#L2627).

$custom_keys = get_post_custom_keys( $post_id ) ?? [];

Shows: Expression on left side of ?? is not nullable.

[phpstan-bot]

You've opened the pull request against the latest branch 1.11.x. If your code is relevant on 1.10.x and you want it to be released sooner, please rebase your pull request and change its target to 1.10.x.

[ondrejmirtes]

Using void in a union is completely invalid and when used in a native type even crashes PHP: https://3v4l.org/7iULB

Instead of array|void instead array|null should be used.

That said, I'd accept a PR that changes array|void into array|null as a result of FuncCall/StaticCall/MethodCall. So the change needs to happen in MutatingScope::resolveType. It's not enough to change a single rule.

[kesselb]

Thanks for your prompt review 👍

I will take a look.

[herndlm]

Looks like you are aware of it already @kesselb , but just for the sake of completeness and issue linking - we discussed this also in szepeviktor/phpstan-wordpress#176, and yeah, WordPress types are wrong there IMO

Oh and phpstan/phpstan#9185 too

[ondrejmirtes]

Superseded by #2778