must_use function

[zonuexe]

Feature request

Rust refers to functions that should not discard their return values when used on a separate line as #[must_use], regardless of whether they have side effects. Similarly, PhpStorm marks such functions with #[Pure(true)].

ob_get_contents() is clearly an impure function with state, but it doesn't make sense to write ob_get_contents(); on a separate line. #[Pure(true)] means that.

refs phpstan/phpstan-src#3867 (comment)
refs #11101

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[claudepache]

There will likely be #[NoDiscard] for that purpose in PHP 8.next, see: https://wiki.php.net/rfc/marking_return_value_as_important

Besides, #[Pure(true)] is a strange choice for marking an impure function. Please, don’t implement annotations with a flat contradiction in their name.

[zonuexe]

@claudepache
#[NoDiscard] is a good idea. The RFC votes are favorable, so it's likely to be implemented in the next PHP version.

Besides, #[Pure(true)] is a strange choice for marking an impure function. Please, don’t implement annotations with a flat contradiction in their name.

Very strange, but it's JetBrains/PhpStorm that provides them. More details can be found in the linked comments and PR.

[ondrejmirtes]

Yeah, let's wait for the PHP RFC to pass. Meanwhile, you can use #[MustUseResult] with https://github.com/DaveLiddament/phpstan-php-language-extensions