A union with void should error because it leads to a fatal error

[herndlm]

Bug report

https://www.php.net/manual/en/language.types.void.php states

void is a return-only type declaration indicating the function does not return a value, but the function may still terminate. Therefore, it cannot be part of a union type declaration

See https://3v4l.org/iRfF2

This was raised by @IanDelMar via szepeviktor/phpstan-wordpress#176

#6720 might be the same or is very related.

Note: Apparently WordPress uses union types of void with a scalar which annoyed me already, because I can't cast the return to a scalar without errors. E.g. https://developer.wordpress.org/reference%2Fclasses%2Fwpdb%2Fprepare%2F/

Code snippet that reproduces the problem

https://phpstan.org/r/23820230-f5a3-4533-9543-79b453cd5bd8

Expected output

There should be 2 errors IMO. The one about the invalid return type (union with void) is missing.

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[ondrejmirtes]

Implemented: phpstan/phpstan-src#2763

[herndlm]

great! but, @szepeviktor I wonder what this means for the wordpress void union types 🙈

[ondrejmirtes]

@herndlm It's a fatal error in PHP so it shouldn't mean anything.

[herndlm]

they use such phpdoc types (so no fatal error) heavily, but the rule doesn't cover them I guess. there's #6720 for that I suppose :)

[szepeviktor]

It's a fatal error in PHP

Please see https://3v4l.org/jTGHE

[github-actions]

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