Merge "Require $key in msg() functions"

diff --combined includes/specialpage/SpecialPage.php
index e861afe,b883d33..9594952
--- 1/includes/specialpage/SpecialPage.php
--- 2/includes/specialpage/SpecialPage.php
+++ b/includes/specialpage/SpecialPage.php
@@@ -33,7 -33,7 +33,7 @@@ use MediaWiki\MediaWikiServices
   *
   * @ingroup SpecialPage
   */
- class SpecialPage {
+ class SpecialPage implements MessageLocalizer {
        // The canonical name of this special page
        // Also used for the default <h1> heading, @see getDescription()
        protected $mName;
@@@ -743,7 -743,7 +743,7 @@@
         * @return Message
         * @see wfMessage
         */
-       public function msg( /* $args */ ) {
+       public function msg( $key /* $args */ ) {
                $message = call_user_func_array(
                        [ $this->getContext(), 'msg' ],
                        func_get_args()
@@@ -783,10 -783,6 +783,10 @@@
         * @since 1.25
         */
        public function addHelpLink( $to, $overrideBaseUrl = false ) {
 +              if ( $this->including() ) {
 +                      return;
 +              }
 +
                global $wgContLang;
                $msg = $this->msg( $wgContLang->lc( $this->getName() ) . '-helppage' );