Ability to type hint truly empty arrays

[mfn]

Feature request

I brought this previously up #2739 but it was closed without action.

I would like to bring this up once more, the necessity to have:

• something returning a "complex shape of array": array{foo:string,bar:string,baz:string,daz:string}
• and in some cases returning an empty array
• the use-case would be to improve the handling in legacy code bases, or code which can't switch to alternatives like value objects, for whatever reason

Example

/**
 * @return array{foo:string,bar:string,baz:string,daz:string}
*/
function foo()
{
  if (some error condition) {
    return [];
  }
  if (some other condition) {
    return [];
  }
  return [
    'foo' => '…',
    'bar' => '…',
    'baz' => '…',
    'daz' => '…',
  ];
}

One of the previously proposed solution was to make each key of the array optional: but this would mean it's legal to return a partial array which is not the intent here.

Another solution, as a workaround, was to declare it e.g. array{foo:string,bar:string,baz:string,daz:string} | array{dummy?:null}

But in the this begs the question: since we already have the great array shape type documentator:

can't we just make it support array{} ?

It seems it would fit it very nicely. This was suggested by @adaamz in #2739 (comment)

Thank you for reconsidering!

[ondrejmirtes]

Although myself I don't understand why do you need to typehint a function that always returns an empty array - at that point you know you can replace the call with []. Such function is of very little usefulness....

but it was easy enough to implement it so I did it: phpstan/phpdoc-parser@ea0b174 + phpstan/phpstan-src@d36852a

[mfn]

Thank you!

I don't understand why do you need to typehint a function that always returns an empty array

But it's not "always", see my example!

Basically it's a legacy / idiotic behaviour 😼 to return [] instead of e.g. null which obviously would be more idiomatic but, again, I'm talking about legacy code here.

[github-actions]

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