impure.die

Code example

<?php declare(strict_types = 1);

class Foo
{
	/** @phpstan-pure */
	public function doFoo(): string
	{
		die('fatal error');
	}
}

Why is it reported?

The die language construct is used inside a function or method marked as @phpstan-pure. Pure functions must not have side effects -- they should only compute and return a value based on their inputs. Calling die terminates the entire PHP process, which is a significant side effect.

How to fix it

Remove die from the pure function by throwing an exception instead, or remove the @phpstan-pure annotation if the function genuinely needs to terminate the process:

 <?php declare(strict_types = 1);

 class Foo
 {
 	/** @phpstan-pure */
 	public function doFoo(): string
 	{
-		die('fatal error');
+		throw new \RuntimeException('fatal error');
 	}
 }

Or remove the purity annotation:

 <?php declare(strict_types = 1);

 class Foo
 {
-	/** @phpstan-pure */
 	public function doFoo(): string
 	{
 		die('fatal error');
 	}
 }