possiblyImpure.exit

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?

This identifier is not reported in practice because exit is always considered definitely impure, not just possibly impure. PHPStan reports impure.exit instead.

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;
 }