What is the #[\Override] Attribute added in PHP 8.3, and how does it protect inheritance?

Short answer

It is placed on derived methods to confirm that they override a method that exists in the parent class or interface; the engine throws a compile-time error if the original method changes.

Explanation

In a large project, you may override a parent method, then another developer may rename or delete that method. Your derived method silently becomes a new method that is never called, creating hidden bugs. Adding #[\Override] makes the PHP engine verify that the parent method exists and throw a Compile Error immediately if it does not.

Code example

namespace App\Models;

class ParentModel
{
    public function execute(): void {}
}

class ChildModel extends ParentModel
{
    #[\Override]               // the leading backslash matters inside a namespace
    public function execute(): void {}

    // #[\Override]
    // public function exceute(): void {}   // typo → Fatal error: ChildModel::exceute() has #[\Override]
    //                                      // attribute, but no matching parent method exists
}

Common mistakes

• Placing #[\Override] on a completely new method that implements no interface method and overrides no parent method.

Follow-up questions

• What is the First-Class Callables syntax (...) in PHP 8.1, and how does it improve callbacks?

Sources

• PHP docs — Override Attribute