What To Do About Deprecation Notices When Return Types Change in PHP?

Reference: Return Type of ... Should Be Compatible with ... or the #[ReturnTypeWillChange] Attribute Should Be Used

Background: Return Types and Covariance

Covariance rules in PHP dictate that return types in extended classes must be compatible with or more specific than those in the parent class. However, extending a class with a different or missing return type can break the covariance assumption.

Backwards Compatibility and Deprecation

Introducing return types to existing methods would break code relying on older PHP versions without them. Hence, PHP uses tentative return types with deprecation notices to allow adaptations.

The #[ReturnTypeWillChange] Attribute

The #[ReturnTypeWillChange] attribute informs PHP 8.1 to suppress the deprecation notice for a method with a planned return type change. This grants time for updates without immediate breakage.

Resolution

Determine the affected method and correct return type from the deprecation notice. Options for resolution include:

• Ignoring the Deprecation: If the library code is maintained by someone else, give them time to update it.
• Updating the Return Type: If it's safe to do so, add the correct return type to the method.
• Suppressing the Notice: Temporarily avoid the notice using the #[ReturnTypeWillChange] attribute, but plan to fix it later when PHP 9.0 enforces return types.

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