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Error Identifier: empty.notAllowed

Every error reported by PHPStan has an error identifier. Here’s a list of all error identifiers. In PHPStan Pro you can see the error identifier next to each error and filter errors by their identifiers.

Code example #

<?php declare(strict_types = 1);

function isValid(string $name): bool
{
	return !empty($name);
}

This rule is provided by the package phpstan/phpstan-strict-rules.

Why is it reported? #

The empty() language construct is disallowed by strict rules because it combines two checks into one – it checks if a variable is set and if its value is falsy. This makes its behaviour unpredictable with different types: empty('0') returns true, empty(0) returns true, and empty([]) returns true. These implicit coercions can hide bugs.

Using explicit comparisons makes the code’s intent clearer and avoids surprising results from PHP’s loose type juggling.

How to fix it #

Replace empty() with an explicit comparison appropriate for the expected type:

 <?php declare(strict_types = 1);
 
 function isValid(string $name): bool
 {
-	return !empty($name);
+	return $name !== '';
 }

For arrays, compare against an empty array or use count():

 <?php declare(strict_types = 1);
 
 /** @param list<string> $items */
 function hasItems(array $items): bool
 {
-	return !empty($items);
+	return count($items) > 0;
 }

How to ignore this error #

You can use the identifier empty.notAllowed to ignore this error using a comment:

// @phpstan-ignore empty.notAllowed
codeThatProducesTheError();

You can also use only the identifier key to ignore all errors of the same type in your configuration file in the ignoreErrors parameter:

parameters:
	ignoreErrors:
		-
			identifier: empty.notAllowed

Rules that report this error #

• PHPStan\Rules\DisallowedConstructs\DisallowedEmptyRule [1] phpstan/phpstan-strict-rules

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