method.variance

Code example

<?php declare(strict_types = 1);

class C
{
	/**
	 * @template-covariant U
	 * @return void
	 */
	public function doFoo(): void
	{
	}
}

Why is it reported?

Variance annotations (@template-covariant and @template-contravariant) are only allowed for type parameters of classes and interfaces, not for methods or functions. A method-level template type cannot be declared covariant or contravariant because variance only has meaning in the context of a class's type parameters -- it describes how the class relates to its subtypes.

How to fix it

Remove the variance annotation from the method-level template type. Use a plain @template instead:

 class C
 {
 	/**
-	 * @template-covariant U
+	 * @template U
 	 * @return void
 	 */
 	public function doFoo(): void
 	{
 	}
 }

If variance is needed, move the template type to the class level:

+/**
+ * @template-covariant U
+ */
 class C
 {
-	/**
-	 * @template-covariant U
-	 * @return void
-	 */
 	public function doFoo(): void
 	{
 	}
 }