The preg_match always return with option array key when condition is === 1

[kayw-geek]

Hi @shish, Thank you for adding more features to Safe.

Currently, I found an issue where the return value of the \Safe\preg_match() method must be assigned to a variable for PHPStan to correctly infer it; otherwise, it assumes that the array key might not exist.

$result = \Safe\preg_match($pattern, $string, $matches);
if ($result === 1){
    \PHPStan\Testing\assertType($type, $matches);
}

if(\Safe\preg_match($pattern, $string, $matches) === 1) {
    \PHPStan\Testing\assertType($type, $matches); // line 24
}

 ------ ------------------------------------------------------------------------------------------------------------------------------------ 
  24     Expected type array{0: string, 1: non-empty-string, 2: 'o', 3?: 'World'}, actual: array{0?: string, 1?: non-empty-string, 2?: 'o',  
         3?: 'World'}                                                                                                                        
 ------ ------------------------------------------------------------------------------------------------------------------------------------ 


                                                                                                                        
 [ERROR] Found 1 error                                                                                                  
                       

[shish]

cc @staabm who has some idea how this part works, I am even more confused by this than the last thread along these lines 😅

[staabm]

@shish this looks very similar. Was the other fix released already?

@kayw-geek which version of the safe/* packages do you use?

[shish]

@shish this looks very similar. Was the other fix released already?

Yup, checked that a testcase fails with the current phpstan-safe-rule master branch + Safe 3.0.2 (and verified that vendor/thecodingmachine/safe/generated/8.4/pcre.php has the @returns 0|1 annotation just in case) :S

[staabm]

Ok thanks. Will have a look tomorrow :-)

[kayw-geek]

@staabm The thecodingmachine/safe version is v3.0.2, and the preg_match function has the @return 0|1 phpdoc in pcre.php

[staabm]

I have tested with this reproducer (as the origin report does not provide a full runnable example):

<?php declare(strict_types = 1);

function doFoo(string $string) {
	$pattern = '/\s/';


	$result = preg_match($pattern, $string, $matches);
	if ($result === 1){
		\PHPStan\dumpType($matches);
	}
	
	if (preg_match($pattern, $string, $matches) === 1) {
		\PHPStan\dumpType( $matches); // line 24
	}
}

this case works with \preg_match() because PHPStan has a built-in hack for it in
https://github.com/phpstan/phpstan-src/blob/de3720dc4e473505002301c247e77a939845be94/src/Analyser/TypeSpecifier.php#L2185-L2198

I have a open todo on phpstan-src which I guess will fix this problem.
I will make sure to test this case after the phpstan-src fix landed. until then there is nothing we can do here.

In case this is a high priority issue for you, please consider sponsoring my open source work.
otherwise I have other priorities atm