[12.x] revert changes to old() helper

[browner12]

this is a breaking change, as previously users could pass any type of value to $default. with this change it forces all $defaults to be string|array|null.

this is a reversion of part of #56684

for the following code:

dump(new \Illuminate\Support\Collection(['foo', 'bar']));
dd(old('tags', new \Illuminate\Support\Collection(['foo', 'bar'])))

prior to change:

after changes:

[calebdw]

It would have been nice to been tagged on this.

The phpdoc is lying, if the method truly returns mixed then the return type should be updated to mixed

[calebdw]

Additionally, passing a collection violates the allowable parameter types defined for $default

* @param  \Illuminate\Database\Eloquent\Model|string|array|null  $default

[browner12]

I tagged your PR, figured that would alert you.

I'd be okay going to a mixed return type. Just needed to get something in quick because this was a breaking change on a minor release.

Yah, it violates the docblock, but unfortunately docblocks don't mean jack squat. I think this will be the next major shift Laravel could/should go through and tighten its types. Would be a major hurdle, but think it would pay off in the long run.

[calebdw]

I tagged your PR, figured that would alert you.

Unfortunately it doesn't look like github sends any notification that way, has to be a directy CC, but thanks for trying 👍

I'd be okay going to a mixed return type. Just needed to get something in quick because this was a breaking change on a minor release.

We can probably add a @template TDefault to the function and the return so that we can more accurately determine the return type based on the provided default:

    /**
     * Retrieve an old input item.
     *
     * @template TDefault
     * @param  string|null  $key
     * @param  TDefault  $default
     * @return string|array|null|TDefault
     */
    function old($key = null, $default = null): mixed

Yah, it violates the docblock, but unfortunately docblocks don't mean jack squat. I think this will be the next major shift Laravel could/should go through and tighten its types. Would be a major hurdle, but think it would pay off in the long run.

100% agree, this is one of my biggest frustrations is that functions/methods don't return or accept what they say they should. Would be willing to help out with this for v13 if that's something that Taylor is willing to do. Rector/shift can be used to automatically add native types for users