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Error Identifier: method.templateTypeNotInParameter

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 Factory
{
	/**
	 * @template T of object
	 * @param string $class
	 * @return T
	 */
	public function create(string $class): object
	{
		return new $class();
	}
}

Why is it reported? #

A template type declared on a method is not referenced in any of its parameters. PHPStan cannot infer the concrete type for the template type T from the call site because no parameter uses it. This means the generic type information is useless – callers will always get the upper bound of the template type instead of a specific type.

In the example above, T appears in the @return tag but not in any @param tag. PHPStan has no way to determine what T should be when the method is called.

How to fix it #

Reference the template type in a parameter so PHPStan can infer it from the argument:

 <?php declare(strict_types = 1);
 
 class Factory
 {
 	/**
 	 * @template T of object
-	 * @param string $class
+	 * @param class-string<T> $class
 	 * @return T
 	 */
 	public function create(string $class): object
 	{
 		return new $class();
 	}
 }

If the template type is genuinely not needed, remove it:

 <?php declare(strict_types = 1);
 
 class Factory
 {
 	/**
-	 * @template T of object
-	 * @param string $class
-	 * @return T
+	 * @param class-string $class
+	 * @return object
 	 */
 	public function create(string $class): object
 	{
 		return new $class();
 	}
 }

How to ignore this error #

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

// @phpstan-ignore method.templateTypeNotInParameter
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.templateTypeNotInParameter

Rules that report this error #

• PHPStan\Rules\Functions\ExistingClassesInArrowFunctionTypehintsRule [1]
• PHPStan\Rules\Functions\ExistingClassesInClosureTypehintsRule [1]
• PHPStan\Rules\Functions\ExistingClassesInTypehintsRule [1]
• PHPStan\Rules\Methods\ExistingClassesInTypehintsRule [1]
• PHPStan\Rules\Properties\ExistingClassesInPropertyHookTypehintsRule [1]

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