Error Identifier: method.unusedParameter

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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);

class Foo
{
	private function doFoo(int $value, string $unused): void
	{
		echo $value;
	}
}

Why is it reported? #

The private method declares the parameter $unused but never reads it in its body. A parameter that no code path uses is dead — it either signals a leftover from refactoring or a mistake where the parameter was meant to be used.

Only private methods are reported. A public or protected method’s signature may be dictated by an interface, a parent class, or an override, so its parameters cannot always be removed. A private method has no callers outside the class, so its signature is not a contract. Magic methods (whose names start with __) are excluded because the engine dictates their signature, and the constructor has its own constructor.unusedParameter rule. Parameters referenced by a @phpstan-assert tag or a conditional return type are also not reported.

This rule is part of PHPStan’s dead code analysis. It is reported at rule level 4 and above, and is currently part of Bleeding Edge.

How to fix it #

Remove the unused parameter:

-	private function doFoo(int $value, string $unused): void
+	private function doFoo(int $value): void
 	{
 		echo $value;
 	}

Or use the parameter in the method body if it was intended to be read:

 	private function doFoo(int $value, string $unused): void
 	{
 		echo $value;
+		echo $unused;
 	}

How to ignore this error #

You can use the identifier method.unusedParameter to ignore this error using a comment:

// @phpstan-ignore method.unusedParameter
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: method.unusedParameter

Rules that report this error #

• PHPStan\Rules\Classes\UnusedConstructorParametersRule [1]
• PHPStan\Rules\Functions\UnusedFunctionParametersRule [1]
• PHPStan\Rules\Methods\UnusedMethodParametersRule [1]