Error Identifier: impure.require

← Back to impure.*

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 loadConfig(string $path): mixed
{
	return require $path;
}

Why is it reported? #

A function marked as @phpstan-pure must not have side effects and must depend only on its parameters. Using require or require_once inside a pure function is a side effect because it reads a file from disk and executes its contents, which can produce different results depending on external state.

How to fix it #

Remove the @phpstan-pure annotation if the function needs to use require:

 <?php declare(strict_types = 1);
 
-/** @phpstan-pure */
 function loadConfig(string $path): mixed
 {
 	return require $path;
 }

Alternatively, restructure the code so that the file loading happens outside the pure function, and pass the data as a parameter.

How to ignore this error #

You can use the identifier impure.require to ignore this error using a comment:

// @phpstan-ignore impure.require
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: impure.require

Rules that report this error #

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