wp-includes/class-wp-http-encoding.php:231Whether decompression and compression are supported by the PHP version.
bool public static function is_available() { return ( function_exists( 'gzuncompress' ) || function_exists( 'gzdeflate' ) || function_exists( 'gzinflate' ) ); }Introduced in 2.8.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/class-wp-http-encoding.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.