BackedEnum::from() and BackedEnum::tryFrom() incorrect param typing

[jack-worman]

Description

The following code (https://3v4l.org/o5uHL#v8.3.0):

<?php

declare(strict_types=1);

enum IntBacked: int {
    case One = 1;
}

var_export(IntBacked::tryFrom('bogus'));

Resulted in this output:

Fatal error: Uncaught TypeError: IntBacked::tryFrom(): Argument #1 ($value) must be of type int, string given in /in/XN86X:9
Stack trace:
#0 /in/XN86X(9): IntBacked::tryFrom('bogus')
#1 {main}
  thrown in /in/XN86X on line 9

Process exited with code 255.

But I expected this output instead:

NULL

Explanation:

The typing for BackedEnum is declared as:

interface BackedEnum extends UnitEnum
{
    public static function from(int|string $value): static;

    public static function tryFrom(int|string $value): ?static;
}

but this is clearly wrong because int backed enums only allow int $value's and string backed enums only allow string $value's.

I think the real typing should match BackedEnum exactly. I don't see the downside in doing this.

Example expected behavior:

<?php

declare(strict_types=1);

enum IntBacked: int {
    case One = 1;
}

var_export(IntBacked::from(1)); // IntBacked::One
var_export(IntBacked::from('1')); // Fatal error: Uncaught ValueError: "1" is not a valid backing value for enum "IntBacked"
var_export(IntBacked::from('bogus')); // Fatal error: Uncaught ValueError: "bogus" is not a valid backing value for enum "IntBacked"

var_export(IntBacked::tryFrom(1)); // IntBacked::One
var_export(IntBacked::tryFrom('1')); // NULL
var_export(IntBacked::tryFrom('bogus')); // NULL

PHP Version

= 8.1.0

Operating System

No response

[damianwadley]

The design of BackedEnums specifically included that passing the wrong type to those methods would be considered a typing error:

https://wiki.php.net/rfc/enumerations#backed_enums

The from() and tryFrom() methods follow standard weak/strong typing rules. In weak typing mode, passing an integer or string is acceptable and the system will coerce the value accordingly. Passing a float will also work and be coerced. In strict typing mode, passing an integer to from() on a string-backed enum (or vice versa) will result in a TypeError, as will a float in all circumstances. All other parameter types will throw a TypeError in both modes.

If you'd like to change this behavior then check out the RFC process, which begins with raising the subject for discussion on the internals mailing list.

[ondrejmirtes]

Related #12865

[github-actions]

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