Error Identifier: purePropertyHook.redundantUnlessCallable

← Back to purePropertyHook.*

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);

final class Registry
{
	/** @var pure-callable(): int */
	private $stored;

	public mixed $handler {
		/**
		 * @param pure-callable(): int $value
		 * @pure-unless-callable-is-impure $value
		 */
		set {
			$this->stored = $value;
		}
	}
}

Why is it reported? #

The @pure-unless-callable-is-impure tag marks a property hook (PHP 8.4+) as pure except when the named callable parameter is impure — its purity depends on the callable passed in at each call site.

Here the parameter $value is typed as pure-callable, which guarantees it is always pure. Because the only condition that could make the hook impure can never happen, the tag has no effect: the hook is unconditionally pure. Marking it @pure-unless-callable-is-impure is misleading and hides the fact that the hook can simply be declared @phpstan-pure. This mirrors pureMethod.redundantUnlessCallable for regular methods.

How to fix it #

Replace @pure-unless-callable-is-impure with @phpstan-pure:

 	/**
 	 * @param pure-callable(): int $value
-	 * @pure-unless-callable-is-impure $value
+	 * @phpstan-pure
 	 */
 	set {

If the hook is actually meant to accept impure callables, widen the parameter type from pure-callable to callable so that the @pure-unless-callable-is-impure tag becomes meaningful again:

 	/**
-	 * @param pure-callable(): int $value
+	 * @param callable(): int $value
 	 * @pure-unless-callable-is-impure $value
 	 */
 	set {

How to ignore this error #

You can use the identifier purePropertyHook.redundantUnlessCallable to ignore this error using a comment:

// @phpstan-ignore purePropertyHook.redundantUnlessCallable
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: purePropertyHook.redundantUnlessCallable

Rules that report this error #

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