Add return type extension for array_column()

[jlherren]

Note that when the iterable value type of the given array is a ConstantArrayType with optional keys, then it will not attempt to produce a precise result. I think it's not worth supporting this and would either produce useless types, or unnecessarily complex types.

[ondrejmirtes]

There's some noise in the CI pipeline which I need to look into, but here are some real issues found with your extension: https://github.com/phpstan/phpstan-src/runs/4977783162?check_suite_focus=true

[jlherren]

Mmh, yes I see the problem:

/**
 * @return VarTagValueNode[]
 */
public function getVarTagValues(string $tagName = '@var'): array
{
    return array_column(
        array_filter($this->getTagsByName($tagName), static function (PhpDocTagNode $tag): bool {
            return $tag->value instanceof VarTagValueNode;
        }),
        'value'
    );
}

Reported error:

Error: Method PhpDocNode::getVarTagValues() should return array<VarTagValueNode> but returns array<int, PhpDocTagValueNode>.

This code is obviously correct, but teaching PHPStan to correctly recognize this is obviously not possible at the moment. The previously inferred return type was array. I'm not sure what to do here (short of rewriting this code as a foreach).

[ondrejmirtes]

What if we first ran array_column to extract the value of nodes, and only after that we ran array_filter? That could preserve the type.

[ondrejmirtes]

What's the current behaviour with an empty array? If the code doesn't crash then this is a BC break.

[jlherren]

min([]) and max([]) cause fatal errors on PHP >= 8. On PHP < 8 it causes a warning and returns false, which gets coerced to 0 when given to create(). See https://3v4l.org/RS767

[jlherren]

What if we first ran array_column to extract the value of nodes, and only after that we ran array_filter? That could preserve the type.

This would indeed work! I didn't even know PHPStan recognizes array_filter() with instanceof in the callback.

[ondrejmirtes]

Can you please send a PR to phpdoc-parser that switches those calls around? :) Thanks.

[ondrejmirtes]

Thank you!

[BitScout]

Hi, 21 days ago, so right after the release of v1.4.4 (22 days ago) the daily build on ekino/phpstan-banned-code for PHP 7.4 broke. Could it be possible that this is due to this pull request?

phpstan analyze complains:

Line 16: Property Example::$myData (array) does not accept
array<array<string, string>|int|string|null, array<string, array<string, string>|string|null>>.

which in a simplified version means that phpstan thinks that array_column will return an
array<array|int|string|null, array>, in other words an array that can have arrays as its keys.

Here is an example file to reproduce the (potential) problem:

<?php

class Example
{
    /**
     * @var array<mixed>
     */
    protected $myData = [];

    /**
     * @param array<int, array<string, string|array<string,string>|null>> $data
     */
    public function __construct(array $data)
    {
        $x = array_column($data, null, 'type');
        $this->myData = $x;
    }
}

$inputData = [
    [
        'type' => 'one',
        'foo' => null,
    ],
    [
        'type' => 'two',
        'foo' => 'bar',
    ],
    [
        'type' => 'three',
        'foo' => [
            'alpha' => 'bravo',
            'charlie' => 'delta',
        ],
    ],
];

$example = new Example($inputData);

and this is the phpstan.neon.dist used:

parameters:
	level: 8
	paths:
		- src
		- tests

	checkGenericClassInNonGenericObjectType: false

includes:
	- extension.neon
	- vendor/phpstan/phpstan-phpunit/extension.neon
	- vendor/phpstan/phpstan-phpunit/rules.neon

Is something wrong about the example code? Did I misunderstand something?

[ondrejmirtes]

@BitScout Please open a new issue (Bug report).