iterable: Behavior difference based on array vs iterable

[jarstelfox]

https://psalm.dev/r/584b550264

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/584b550264

<?php


abstract class Base {
   /**
    * @return iterable<int, stdClass>
    */
   abstract function returnsIterable(): iterable;
}

class PsalmCatchesIssue extends Base { 
   function returnsIterable(): iterable {
       return [1, 2];
   }
}

class PsalmFailsToCatchIssue extends Base {
   function returnsIterable(): array { // only diff is array
       return [3, 4];
   }
}

class PsalmCatchesReturnTypeMismatch extends Base {
   /** @return array<int, int> */
   function returnsIterable(): array {
       return [5, 6];
   }
}

Psalm output (using commit a9b5291):

ERROR: InvalidReturnStatement - 13:15 - The inferred type 'list{1, 2}' does not match the declared return type 'iterable<int, stdClass>' for PsalmCatchesIssue::returnsIterable

ERROR: InvalidReturnType - 12:32 - The declared return type 'iterable<int, stdClass>' for PsalmCatchesIssue::returnsIterable is incorrect, got 'list{1, 2}'

ERROR: ImplementedReturnTypeMismatch - 24:16 - The inherited return type 'iterable<int, stdClass>' for Base::returnsIterable is different to the implemented return type for PsalmCatchesReturnTypeMismatch::returnsiterable 'array<int, int>'