[feature request] type check match clause

[Disservin]

Description

<?php

function foo(string $str)
{
    return match ($str) {
        'foo' => 'bar',
        321 => 'x'
    };
}

The type of $str is known to be string which means 321 in the match clause can never be reached, since match uses identity checks (===).

Maybe issue a warning ?

Use case

better intellisense

Proposed solution

No response

Alternatives considered

No response

Code example

[calebdw]

this is more of a dead code diagnostic than type checking

[Disservin]

ah yeah the warning would be a dead code or unreachable warning

[calebdw]

Just FYI: phpstan already reports all these things and we surface those warnings in the diagnostics (same thing for mago)---are you using it?

[DarkGhostHunter]

On runtime it does not

[AJenbo]

Yeah this type of check is a dead code detection check. A logic check, not an error check.