generics.deprecatedClassDefault

Code example

<?php declare(strict_types = 1);

/** @deprecated Use NewFormatter instead */
class OldFormatter
{
}

/**
 * @template T = OldFormatter
 */
class Pipeline
{
}

This error is reported by the phpstan-deprecation-rules extension.

Why is it reported?

A @template tag uses a deprecated class as its default type value. The @template T = DefaultClass syntax specifies a default type for a generic parameter, but when DefaultClass is deprecated, the generic class creates a dependency on a class planned for removal. Any usage of Pipeline without an explicit type argument would implicitly use the deprecated OldFormatter.

In the example above, the template parameter T defaults to OldFormatter, which is marked as @deprecated.

How to fix it

Replace the deprecated default type with the recommended replacement:

 <?php declare(strict_types = 1);

 /**
- * @template T = OldFormatter
+ * @template T = NewFormatter
  */
 class Pipeline
 {
 }

Alternatively, remove the default if there is no suitable non-deprecated replacement:

 <?php declare(strict_types = 1);

 /**
- * @template T = OldFormatter
+ * @template T
  */
 class Pipeline
 {
 }