[php-src] Issue #8420: Cutting off an empty body of a function

Issue: https://github.com/php/php-src/issues/8420 Author: roxblnfk ### Description ## Introduction Since PHP 8.0 we have the [Constructor Property Promotion](https://wiki.php.net/rfc/constructor_promotion) feature. Often, using this feature, we get a constructor with an empty body: ```php class Point { public function __construct( public float $x = 0.0, public float $y = 0.0, public float $z = 0.0, ) { } } ``` ## Proposal Add the ability to replace an empty function body with a semicolon: ```php class Point { public function __construct( public float $x = 0.0, public float $y = 0.0, public float $z = 0.0, ); } ``` In the first iteration it might be limited to a constructor and methods with the void returning type. ## Future scope In the case of the proposed feature and [this RFC (Add true type)](https://wiki.php.net/rfc/true-type) implementation, we can talk about the possibility of such a syntax sugar: ```php interface User { function isAdmin(): bool; function getFoo(): ?Foo; } class Admin implemets User { function isAdmin(): true { return true; } /** @link https://wiki.php.net/rfc/null-false-standalone-types Allow null and false as stand-alone types **/ function getFoo(): null { return null; } } // can be replaced with class Admin extends User { function isAdmin(): true; function getFoo(): null; } ``` ## Implementation Sorry, i can not create a PR with the feature i but can help with test cases