Right side of && is always true

[haringsrob]

Hi,

So before I go to create an issue, I have a few reports like this in our codebase (we just started setting up).

Given the example below:

$rand = mt_rand(0, 100);

$varA = in_array(1, [$rand]);
$varB = false;

if ($varA) {
    $varB = true;
}

if ($varA && $varB) { // Here occurs "Right side of && is always true"
    echo 'ok';
}

The last check shows the error "Right side of && is always true". But to me $varB is not always true and can be false as well?

This is just a reproducing example, actual code is not like this ;).

Maybe I am missing something, please tell me!

[ondrejmirtes]

I think you're hitting the "dependent variables" feature that was added in 0.12.64: https://github.com/phpstan/phpstan/releases/tag/0.12.64

In your example, $varB will only ever be true when $varA is true. So if you check for truthiness of $varA, it means that you don't have to check for $varB because it can only ever be true too.

So having if ($varA) is sufficient. See: https://phpstan.org/r/cd4aa27a-7bf4-4f97-adc6-2f60246da018

[haringsrob]

Oh heck! That explains it very well. Thanks a lot for explaining!