Source

File: wp-includes/class-wp-roles.php

protected function get_roles_data() {
		global $wp_user_roles;

		if ( ! empty( $wp_user_roles ) ) {
			return $wp_user_roles;
		}

		if ( is_multisite() && get_current_blog_id() != $this->site_id ) {
			remove_action( 'switch_blog', 'wp_switch_roles_and_user', 1 );

			$roles = get_blog_option( $this->site_id, $this->role_key, array() );

			add_action( 'switch_blog', 'wp_switch_roles_and_user', 1, 2 );

			return $roles;
		}

		return get_option( $this->role_key, array() );
	}