Php storm flags unwrap method as unreachble statement

[JeremyM1985]

The @psalm-return never-return annotation for the unwrap() in class None, flags any proceeding code as unreachable when using Option as a reutrn type.

public function getMemberById(MemberId $memberId): Option
{
    if ($this->hasMemberWithId($memberId)) {
        return new some($this->members[$memberId->toString()]);
    }

    return new None();
}

//

$optional = $this->getMemberById($memberId);

if ($optional->isSome()) {
    $this->member= $optional->unwrap();


    // any further code here is marked as unreachable statement

}

Using the native php never return type (from 8.1) instead of the annotation seems to solve my issue.

Maybe you have an idea? or perhaps i should return union type Some|None instead?

[prewk]

Yeah I can see why that would happen.. I don't know what's kosher here, to me it seems it should say that it returns T as its interface tells us, but throw at runtime anyway.

@Lctrs can you shed some light here?

I'm out of the loop with PHP, haven't been in the ecosystem since 2018 basically, but happy to help in any way I can.

[Lctrs]

Arguably, I would say that PHPStorm is not wrong to tell you this code is unreachable as it might be at this point given the types it knows at this point for the $optional variable - which, from its point of view, is still Some|None at this point as we never tell that is Option::isSome() returns true, it is a Some instance.

Given that Option is not a core PHP's concept (ie. not integrated in the language itself), I would say that mimicking Rust's API to the fullest was an error, and you should not use Option::isSome() or Option::isNone() methods but rather instanceof Some and instanceof None to check if it has a value or not to have IDEs fully understand the types of the variable at play here.

[prewk]

Wouldn't letting None say it's returning T work as well?

[Lctrs]

Yeah, I was talking about the current state of the lib.

[prewk]

Yeah as you implied, PHP can't infer stuff. I guess Psalm would be able to if it was advanced enough. What I don't understand is how phpStorm finds the None class and gets the types from it? It must be pretty confused. Shouldn't it just use the Option interface?

The Rust impl looks like this:

    pub const fn unwrap(self) -> T {
        match self {
            Some(val) => val,
            None => panic("called `Option::unwrap()` on a `None` value"),
        }
    }

If phpStorm indeed does read the types in Some and None, and not just in Option, I assume the correct thing would be to have identical types in all three?