PHP 8.3 introduced typed class constants, the json_validate() function, readonly property amendments in child classes, the Override attribute, and improvements to array_sum() and array_product(). These changes affect how modern WordPress plugins should be written.
Problem: A WordPress plugin is being upgraded to require PHP 8.3, and it is unclear which new language features are safe to adopt versus which deprecated patterns need to be removed to avoid warnings in production.
Solution: PHP 8.3 brings readonly class improvements, typed class constants, json_validate(), the #[\Override] attribute, and mb_str_split(). Remove deprecated dynamic property creation on classes not marked #[AllowDynamicProperties]. Run vendor/bin/phpstan analyse --php-version=80300 to detect compatibility issues before deployment.
The examples below demonstrate typed class constants for WordPress option schemas, json_validate() as a replacement for decode-and-check patterns, and the Override attribute for safer method overriding in plugin class hierarchies.
json_validate() and readonly property improvements:
product_type = $product_type; // set once in constructor — then immutable
}
}NOTE: Run vendor/bin/phpstan analyse --php-version=80300 to detect PHP 8.3 compatibility issues in your plugin before upgrading the server's PHP version. Most WordPress plugins require only minor changes — the biggest source of breakage is static analysis tools that don't yet recognise typed constants.