generics.callSiteVarianceRedundant

Code example

<?php declare(strict_types = 1);

/**
 * @template-covariant T
 */
interface Collection
{
}

/**
 * @param Collection<covariant string> $collection
 */
function doFoo(Collection $collection): void
{
}

Why is it reported?

The call-site variance annotation (e.g. covariant or contravariant) on a generic type argument is redundant because the template type on the class is already declared with the same variance. In the example, Collection already declares T as @template-covariant, so writing Collection<covariant string> is unnecessary -- Collection<string> has the same meaning.

How to fix it

Remove the redundant call-site variance annotation:

 /**
- * @param Collection<covariant string> $collection
+ * @param Collection<string> $collection
  */
 function doFoo(Collection $collection): void
 {
 }