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Date: Sat, 23 Apr 2022 20:19:00 +0200
Message-ID: <CADyq6sJnKB4+02rZ6LvZfoAnX9OrHmhQko1FqEyR5Qu6Uj7asQ@mail.gmail.com>
To: "G. P. B." <george.banyard@gmail.com>
Cc: PHP internals <internals@lists.php.net>
Content-Type: multipart/alternative; boundary="0000000000004fccc305dd566168"
Subject: Re: [PHP-DEV] Canonicalize "iterable" into "array|Traversable" and Reflection
From: ocramius@gmail.com (Marco Pivetta)

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Hey George,

How would the engine behave (with this RFC included) with an inheritance
check?

Specifically:

interface A {
    function foo(interable $param): iterable;
}
interface B {
    function foo(array|\Trabersable $param): array|\Traversable:
}

Would they be compatible with each other, if put in inheritance between
each other in any order?

On Sat, 23 Apr 2022, 14:28 G. P. B., <george.banyard@gmail.com> wrote:

> Hello internals,
>
> One area the engine currently needs to take special care is dealing with
> the typing relation between iterable, Traversable, and array.
> The change is to canonicalize "iterable" into "array|Traversable" as this
> then removes this special case.
>
> However, doing so breaks Reflection for iterable types and will now return
> a ReflectionUnionType instead of a ReflectionNamed type.
> There are a couple of options to proceed:
>  - Accept the BC break, and expect end users to already be handling union
> types for code running on 8.2 (least complexity)
>  - Only provide a BC layer for (?)iterable to return a ReflectionNamedType
> and have usages of iterable in a union type be exposed as Traversable|array
> (OK complexity)
>  - Full BC such that even in union types where iterabl was used
> Traversable|array gets converted back to iterable (high complexity)
>
> The PR for this change is https://github.com/php/php-src/pull/7309
>
> This PR is also blocking the implementation for DNF types, as it vastly
> simplifies the implementation of it.
>
> Best regards,
>
> George P. Banyard
>

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