There are two ways to cast to binary as introduced in PHP 5.2.1:

• $binary = b"binary string";
• $binary = (binary) $string;

The first one is identified by PHPCS as T_BINARY_CAST, while the second is not.

By the looks of it, PHP itself incorrectly tokenizes this as T_STRING_CAST. See: https://3v4l.org/n0DJj

Ref: http://php.net/manual/en/language.types.type-juggling.php#language.types.typecasting