Psl\Type\non_empty_string() is not marked as @psalm-pure?

[Ocramius]

In the context of following snippet:

    /**
     * @throws InvalidPackageName
     *
     * @psalm-pure
     */
    public static function fromName(string $name): self
    {
        if (preg_match('{^[a-z0-9](?:[_.-]?[a-z0-9]+)*/[a-z0-9](?:(?:[_.]?|-{0,2})[a-z0-9]+)*$}iD', $name) !== 1) {
            throw InvalidPackageName::fromInvalidName($name);
        }

        return new self(
            non_empty_string()
                ->coerce($name)
        );
    }

psalm reports:

... Cannot call an impure function from a mutation-free context (see https://psalm.dev/202)
            non_empty_string()

I wonder if all type constructors can/should be declared pure? Is this where we got stuck on conditional type purity?

[azjezz]

back to vimeo/psalm#4145 😛

the issue here is that we can't declare Type::assert/Type::coerce as "pure", because not all implementations are pure ( for example IterableType::assert iterates over an iterable, which might not be immutable ).

so i suggest you add @psalm-suppress here.

[azjezz]

Also, i attempted to improve this by having the psalm plugin report the call as pure if the argument is pure/immutable, but that is not possible via the plugin system, and it seems psalm have a special case for internal php functions ( e.g: https://github.com/vimeo/psalm/blob/bd6efd7cf2b7e6fdf01b343be0c5bbb9aacdbbbb/src/Psalm/Internal/Codebase/Functions.php#L499 )

[Ocramius]

Wow that's ugly :D

Guess we'll have to improve upstream before being able to declare it here: still like vimeo/psalm#4145 as an idea, but hard to bring it to life :-\

[azjezz]

yea, i will trying to play around with psalm to see if i can make it possible to have special "purity checkers" for function/method calls, this will allow to mark things like Type\string()->assert() pure without the need for vimeo/psalm#4145 using the plugin