PHP 7.4 closures with array_filter breaks sniffs

[raalderink]

There is an issue with the NullableTypeForNullDefaultValueSniff fixer, used on a closure with an array_filter. It is unable to properly transform this closure into an arrow function.

File to use when reproducing:

<?php
array_map(
    static function (array $value): array {
        return array_filter($value);
    },
    []
);

When running this fixer on the above code, it will iterate 3 times over it. The first two times through the T_CLOSURE, where the second time would be the culprit. The second iteration results in the following code, which breaks the third iteration, throwing Undefined index: parenthesis_opener

<?php
array_map(
    static fn (array $value):  => array_filter[$value],
    []
);

This clearly breaks the array_filter function, because somehow it converts it to an array. The following would be correct:

array_map(
    fn(array $value): array => array_filter($value),
    []
);

In addition to that, the StaticClosureSniff will fail with Undefined index: scope_opener on the above code, which would be correct.

[kukulich]

@raalderink Do you really mean NullableTypeForNullDefaultValueSniff ?

[raalderink]

@kukulich Yes, the fixer throws this on that code:

Stack trace:
#0 /.../vendor/slevomat/coding-standard/SlevomatCodingStandard/Sniffs/TypeHints/NullableTypeForNullDefaultValueSniff.php(40): PHP_CodeSniffer\Runner->handleErrors(8, 'Undefined index...', '/...', 40, Array)
#1 /.../vendor/squizlabs/php_codesniffer/src/Files/File.php(496): SlevomatCodingStandard\Sniffs\TypeHints\NullableTypeForNullDefaultValueSniff->process(Object(PHP_CodeSniffer\Files\LocalFile), 7)
#2 /.../vendor/squizlabs/php_codesniffer/src/Files/LocalFile.php(91): PHP_CodeSniffer\Files\File->process()
#3 / in /.../vendor/squizlabs/php_codesniffer/src/Runner.php on line 606

Fatal error: Uncaught PHP_CodeSniffer\Exceptions\RuntimeException: Undefined index: parenthesis_opener in /.../vendor/slevomat/coding-standard/SlevomatCodingStandard/Sniffs/TypeHints/NullableTypeForNullDefaultValueSniff.php on line 40 in /.../vendor/squizlabs/php_codesniffer/src/Runner.php on line 606

PHP_CodeSniffer\Exceptions\RuntimeException: Undefined index: parenthesis_opener in /.../vendor/slevomat/coding-standard/SlevomatCodingStandard/Sniffs/TypeHints/NullableTypeForNullDefaultValueSniff.php on line 40 in /.../vendor/squizlabs/php_codesniffer/src/Runner.php on line 606

Call Stack:
    0.0017     401280   1. {main}() /.../vendor/squizlabs/php_codesniffer/bin/phpcbf:0
    0.0487    1731048   2. PHP_CodeSniffer\Runner->runPHPCBF() /.../vendor/squizlabs/php_codesniffer/bin/phpcbf:18
    0.3532    7546232   3. PHP_CodeSniffer\Runner->run() /.../vendor/squizlabs/php_codesniffer/src/Runner.php:200
    0.3632    8086296   4. PHP_CodeSniffer\Runner->processFile() /.../vendor/squizlabs/php_codesniffer/src/Runner.php:434
    0.3920    9037944   5. PHP_CodeSniffer\Reporter->cacheFileReport() /.../vendor/squizlabs/php_codesniffer/src/Runner.php:656
    0.3921    9056624   6. PHP_CodeSniffer\Reports\Cbf->generateFileReport() /.../vendor/squizlabs/php_codesniffer/src/Reporter.php:285
    0.3921    9056624   7. PHP_CodeSniffer\Fixer->fixFile() /.../vendor/squizlabs/php_codesniffer/src/Reports/Cbf.php:49
    0.3991    9155432   8. PHP_CodeSniffer\Files\LocalFile->process() /.../vendor/squizlabs/php_codesniffer/src/Fixer.php:174
    0.3991    9155432   9. PHP_CodeSniffer\Files\LocalFile->process() /.../vendor/squizlabs/php_codesniffer/src/Files/LocalFile.php:91
    0.4003    9148152  10. SlevomatCodingStandard\Sniffs\TypeHints\NullableTypeForNullDefaultValueSniff->process() /.../vendor/squizlabs/php_codesniffer/src/Files/File.php:496
    0.4006    9151216  11. PHP_CodeSniffer\Runner->handleErrors() /.../vendor/slevomat/coding-standard/SlevomatCodingStandard/Sniffs/TypeHints/NullableTypeForNullDefaultValueSniff.php:40

[leongersen]

This issue isn't limited to array_filter, it also occurs with, for example, array_merge. Here is another reproducer:

array_reduce(
    [],
    static function (array $values): array {
        return array_merge($values, []);
    },
    []
);

Edit: And another:

static function (\InvalidArgumentException $exception): string {
    return $exception->getMessage();
}

[kukulich]

Thank you for your report.

It looks it's a bug in PHPCS itself but I've found a workaround for this sniff: d69ad4a

[leongersen]

Is there an open issue for phpcs for this issue?

[kukulich]

@leongersen Yes, squizlabs/PHP_CodeSniffer#2828 :D

[github-actions]

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