Since empty arrays always evaluates to false, these checks can be simplified.
An example from Symfony\Component\Routing\Annotation\Route::setRequirements():

// current check
if (0 === count($this->methods)) {
    // ...
}

// proposed check
if (!$this->methods) {
    // ...
}

NOTE: I've found 54 exact matches for 0 === count( at 2.7 branch.