I read that there is a problem with PHP 7.2 and if you want to use ARGON2 you need to compile php using –with-password-argon2
In my case I'm using PHP 7.3.6
php -v
PHP 7.3.6 (cli) (built: Jun 22 2019 11:43:32) ( NTS ) Copyright (c) 1997-2018 The PHP Group Zend Engine v3.3.6, Copyright (c) 1998-2018 Zend Technologies with Zend OPcache v7.3.6, Copyright (c) 1999-2018, by Zend Technologies with Xdebug v2.7.2, Copyright (c) 2002-2019, by Derick Rethans
If I try:
var_dump(password_hash('password', PASSWORD_ARGON2I));
it returns:
PHP Warning: Use of undefined constant PASSWORD_ARGON2I - assumed 'PASSWORD_ARGON2I' (this will throw an Error in a future version of PHP)
More info: MacOS Sierra