Narrow type in Collection::filter() #697
Description
It would be great if Collection::filter() would also be able to narrow types.
class Group extends Node
/**
* @var Collection<int, Node>
*/
#[ORM\OneToMany(targetEntity: Node::class, mappedBy: 'parent')]
private Collection $children;
/**
* @return Collection<int, Group>
*/
public function getGroups(): Collection
{
return $this->children
->filter(static fn (Node $node): bool => $node instanceof Group)
;
}
}
Yields:
Method App\Entity\Group::getGroups() should return Doctrine\Common\Collections\Collection<int, App\Entity\Group>
but returns Doctrine\Common\Collections\Collection<int, App\Entity\Node>.
A workaround is to convert to an array.
/**
* @return array<int, Group>
*/
public function getGroups(): array
{
return array_filter(
$this->children->toArray(),
static fn (Node $node): bool => $node instanceof Group
);
}