possiblyImpure.include

Code example

<?php declare(strict_types = 1);

class Config
{

	/** @phpstan-pure */
	public function load(string $file): array
	{
		return include $file;
	}

}

Why is it reported?

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

The function or method is marked as pure (via @phpstan-pure), but it uses include or require inside its body. Including or requiring files is a side effect because it executes arbitrary code from the filesystem, which may modify global state, define functions or classes, or produce output. This makes the function possibly impure.

A pure function must have no side effects and must depend only on its arguments.

How to fix it

Remove the include/require statement and pass the data as a parameter instead:

 <?php declare(strict_types = 1);

 class Config
 {

-	/** @phpstan-pure */
-	public function load(string $file): array
+	/** @phpstan-pure */
+	public function load(array $data): array
 	{
-		return include $file;
+		return $data;
 	}

 }

Alternatively, if the function genuinely needs to include files, remove the @phpstan-pure annotation:

 <?php declare(strict_types = 1);

 class Config
 {

-	/** @phpstan-pure */
 	public function load(string $file): array
 	{
 		return include $file;
 	}

 }