[php-src] Issue #8312: Add boolean assignment operators

Issue: https://github.com/php/php-src/issues/8312 Comment Author: KapitanOczywisty > I don't see a clear benefit to have these operators (and apparently, most other languages > which have the logical operators and combined assignment operators do not either) @cmb69 Beside shorter syntax, there are 2 more "benefits" from using a ||= b instead of a = a || b: 1. Setter is only called when not short-circuiting, this is similar to a || (a = b): ```php new class { private array $data = ['foo' => true, 'bar' => false,]; function __construct() { $this->foo ||= true; assert($this->data['foo'] === true); $this->bar ||= false; assert($this->data['bar'] === false); } function __get(string $name): bool { echo "Getter called for {$name}\n"; return $this->data[$name]; } function __set(string $name, bool $value): void { echo "Setter called for {$name}\n"; $this->data[$name] = $value; } }; ``` should be expected: ``` Getter called for foo Getter called for bar Setter called for bar ``` https://3v4l.org/LJp09 2. it's easier to use with incrementing keys: ```php $array = [false, false, false]; $key = 0; $array[$key++] ||= true; $array[++$key] ||= true; assert($array === [true, false, true]); ``` https://3v4l.org/FGBjj