WP_User::set_role( string $role )

617	public function set_role( $role ) {618		if ( 1 === count( $this->roles ) && current( $this->roles ) === $role ) {619			return;620		}621 622		foreach ( (array) $this->roles as $oldrole ) {623			unset( $this->caps[ $oldrole ] );624		}625 626		$old_roles = $this->roles;627 628		if ( ! empty( $role ) ) {629			$this->caps[ $role ] = true;630			$this->roles         = array( $role => true );631		} else {632			$this->roles = array();633		}634 635		update_user_meta( $this->ID, $this->cap_key, $this->caps );636		$this->get_role_caps();637		$this->update_user_level_from_caps();638 639		foreach ( $old_roles as $old_role ) {640			if ( ! $old_role || $old_role === $role ) {641				continue;642			}643 644			/** This action is documented in wp-includes/class-wp-user.php */645			do_action( 'remove_user_role', $this->ID, $old_role );646		}647 648		if ( $role && ! in_array( $role, $old_roles, true ) ) {649			/** This action is documented in wp-includes/class-wp-user.php */650			do_action( 'add_user_role', $this->ID, $role );651		}652 653		/**654		 * Fires after the user's role has changed.655		 *656		 * @since 2.9.0657		 * @since 3.6.0 Added $old_roles to include an array of the user's previous roles.658		 *659		 * @param int      $user_id   The user ID.660		 * @param string   $role      The new role.661		 * @param string[] $old_roles An array of the user's previous roles.662		 */663		do_action( 'set_user_role', $this->ID, $role, $old_roles );664	}