Strict comparison using === between 0 and int<1, max> will always evaluate to false.

[lukepass]

Bug report

Hello, phpstan is reporting a false positive here:

/** @var User */
$user = $this->getUser();
$em   = $this->getDoctrine()->getManager();

/** @var null|UserProduct */
$userProduct = $em->getRepository(UserProduct::class)->findOneByUserAndProduct($user, $product);

if (!$userProduct || $userProduct->getCount() < 1) {
    throw new BadRequestHttpException();
}

// decreases the products
$userProduct->setCount($userProduct->getCount() - 1); // <--- here I am decreasing!
if (0 === $userProduct->getCount()) {
    $em->remove($userProduct);
}

The error is this:

Strict comparison using === between 0 and int<1, max> will always evaluate to false.

And the check is if (0 === $userProduct->getCount()). It's correct because I am decreasing the value.

Code snippet that reproduces the problem

Expected output

[mergeable]

This bug report is missing a link to reproduction on phpstan.org.
It will most likely be closed after manual review.

[ondrejmirtes]

Funny enough, if you make your UserProduct::setCount() method return void, it will work :) In that case PHPStan knows it's calling a method with a side-effect, so it will reset memorized value from getCount().

Otherwise you can work around it using local variables:

/** @var User */
$user = $this->getUser();
$em   = $this->getDoctrine()->getManager();

/** @var null|UserProduct */
$userProduct = $em->getRepository(UserProduct::class)->findOneByUserAndProduct($user, $product);

if (!$userProduct) {
    throw new BadRequestHttpException();
}

$count = $userProduct->getCount();
if ($count < 1) {
    throw new BadRequestHttpException();
}

// decreases the products
$userProduct->setCount($userProduct->getCount() - 1); // <--- here I am decreasing!
if (0 === $userProduct->getCount()) {
    $em->remove($userProduct);
}

[ossinkine]

@ondrejmirtes Why is this issue closed? You suggest a workaround but the issue still exists. Why the PHPStan memorizes the method result?

[ondrejmirtes]

It memorizes it so it could detect:

assert($userProduct->getCount() === 0);
assert($userProduct->getCount() === 0); // always true

I'm aware of this issue, it's definitely a duplicate but I didn't spend the time looking for the issue ID.

[ossinkine]

It depends on getCount method implementation. For example, the following implementation returns difeerent values:

function getCount(): int
{
    static $count;
    return ++$count;
}

There is no rules which declare the some methods must be idempotent, right?

[ondrejmirtes]

Currently not. All methods are memorized, except for void methods. Void methods also invalidate previously memorized calls.

[ossinkine]

So is there the way to disable this behavior? BTW void method does not invalidate the memorized calls: https://phpstan.org/r/51fd580d-ac38-4e82-ad22-a65c407da902

[ossinkine]

#1157 is this related issue?

[ondrejmirtes]

All of these issues are related:

phpstan/phpstan-phpunit#25

#1157

#1745

#2209

#2349

#2403

#2288

[dktapps]

This is something of a pest to be honest, I've run into this multiple times in various forms. The assumption that a method with a return value is pure is unreliable in many cases.

[lock]

This thread has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.