如何让 phpstan 推断我的 Laravel 收集管道的类型？

Question

鉴于我的 class

<?php
declare(strict_types=1);

use Illuminate\Support\Collection;
use stdClass;

class PhpstanIssue
{
    /**
     * @param Collection<Collection<stdClass>> $collection
     *
     * @return Collection<Foo>
     */
    public function whyDoesThisFail(Collection $collection): Collection
    {
        return $collection
            ->flatten() // Collection<stdClass>
            ->map(static function (\stdClass $std): ?Foo {
                return Foo::get($std);
            }) // should now be Collection<?Foo>
            ->filter(); // should now be Collection<Foo>
    }
}

我非常困惑为什么 phpstan (0.12.64) 会失败：

18: [ERROR] Method PhpstanIssue::whyDoesThisFail() should return
Illuminate\Support\Collection&iterable<Foo> but returns 
Illuminate\Support\Collection&iterable<Illuminate\Support\Collection&iterable<stdClass>>. (phpstan)

为什么 phpstan 不能推断出该管道的正确结果类型？我怎样才能让 phpstan 理解管道？

我可以验证我的代码在 phpunit 测试用例中是否有效：

class MyCodeWorks extends TestCase
{
    public function testPipeline()
    {
        $result = (new PhpstanIssue())->whyDoesThisFail(
            new Collection(
                [
                    new Collection([new \stdClass(), new \stdClass()]),
                    new Collection([new \stdClass()]),
                ]
            )
        );

        self::assertCount(3, $result);
        foreach ($result as $item) {
            self::assertInstanceOf(Foo::class, $item);
        }
    }
}

会过去的。

为了这个问题，我的Foo只是一个虚拟的class。唯一相关的是它采用 stdClass 实例并将其转换为 ?Foo 实例。

class Foo
{
    public static function get(\stdClass $std): ?Foo
    {
        // @phpstan-ignore-next-line
        return (bool) $std ? new static() : null;
    }
}

Answer 1

Illuminate\Support\Collection class 本身不是通用的。所以写 Collection<Foo> 是错误的。这会导致错误消息，如 Illuminate\Support\Collection&iterable<Illuminate\Support\Collection&iterable<stdClass>>

您有两个选择：

安装 Larastan. It's a PHPStan extension for Laravel. And it has stub files 使 Illuminate\Support\Collection class 通用。
或者，如果您只是使用 illuminate/collections 独立包而没有完整的 Laravel 应用程序，您可以编写自己的存根文件。来自 PHPStan docs:

... you can write a stub file with the right PHPDoc. It’s like source code, but PHPStan only reads PHPDocs from it. So the namespace and class/interface/trait/method/function names must match with the original source you’re describing. But method bodies can stay empty, PHPStan is only interested in the PHPDocs.

对于您的示例，以下存根文件应该足够了：

<?php

namespace Illuminate\Support;

/**
 * @template TKey
 * @template TValue
 * @implements \ArrayAccess<TKey, TValue>
 * @implements Enumerable<TKey, TValue>
 */
class Collection implements \ArrayAccess, Enumerable
{
    /**
     * @template TReturn
     * @param callable(TValue, TKey): TReturn $callable
     * @return static<TKey, TReturn>
     */
    public function map($callable) {}
}

如何让 phpstan 推断我的 Laravel 收集管道的类型？

How to get phpstan to infer the type for my Laravel Collection pipeline?

php

laravel

illuminate-container

phpstan