Fix psalm annotation on Enum::from

[kamazee]

• @return static is accurate enough, so it doesn't need a clarification for psalm. static<T> triggers false-positive alerts from static analyzers and seems to be just a mistake;
• enum entry's template type T is more precise as a parameter than mixed: it might help catch more errors when using Enum::from.

[mnapoli]

Thanks!

[kamazee]

This was a bit bold: the fix of return type was correct but I shouldn't have changed the param. Ironically, phpstan picks it up correctly (despite it's psalm- prefixed) but psalm itself doesn't, likely because of vimeo/psalm#2571 .

Will send another PR in a moment. Sorry about that :(

[Ocramius]

triggers false-positive alerts from static analyzers and seems to be just a mistake;

FYI, no mistake there: TheActualEnum<string|int> was intentional.

I did not finish up my work in #143 though, sorry

[kamazee]

@Ocramius I'll double check tomorrow but it didn't work for me (either psalm or phpstan complained). So, I thought it would be enough to set return type to TheActualEnum which already stated that it extended Enum<int|string>.

I'll follow up when I recheck it.

[kamazee]

On the following code:

<?php

/**
 * @psalm-immutable
 * @psalm-template T
 * @psalm-consistent-constructor
 */
class Enum {
    /**
     * Cache of instances of the Enum class
     *
     * @var array
     * @psalm-var array<class-string, array<string, static>>
     */
    protected static $instances = [];

    /**
     * @param mixed $value
     * @return static
     * @psalm-return static<T>
     */
    public static function from($value): self
    {
        throw new RuntimeException();
    }
}

/**
 * @method static self RED()
 * @psalm-immutable
 * @template-extends Enum<string>
 */
class Colours extends Enum {
    protected const RED = '#f00';
}

function foo(Colours $entry): void {
    var_export($entry);
}

foo(Colours::from('red'));

phpstan chokes on static<T> and is okay with just static that extends Enum<string>:
https://phpstan.org/r/7b434d16-9edc-4d44-8304-14f152cb15eb

Psalm detects no issues in such code but shows type of the from result as Colours<empty> which doesn't look right to me:
https://psalm.dev/r/5e1d95b337 (hover a pointer over the last line of the snippet)