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Error Identifier: possiblyImpure.exit

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);

/**
 * @phpstan-pure
 */
function getValue(int $input): int
{
	$closure = function () {
		exit();
	};

	$closure();

	return $input * 2;
}

Why is it reported? #

The function or method is marked as @phpstan-pure but may call exit or die. These constructs terminate the entire PHP process, which is a side effect. Pure functions must not have side effects; they should only compute and return a value based on their inputs.

How to fix it #

Remove the exit/die call from the pure function, or remove the @phpstan-pure annotation if process termination is intentional:

 /**
- * @phpstan-pure
+ * @phpstan-impure
  */
 function getValue(int $input): int
 {
 	$closure = function () {
 		exit();
 	};

 	$closure();

 	return $input * 2;
 }

How to ignore this error #

You can use the identifier possiblyImpure.exit to ignore this error using a comment:

// @phpstan-ignore possiblyImpure.exit
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: possiblyImpure.exit

Rules that report this error #

• PHPStan\Rules\Pure\PureFunctionRule [1]
• PHPStan\Rules\Pure\PureMethodRule [1]

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