xdisp.c (draw_glyphs):

Mark variables that gcc -Wuninitialized cannot deduce are never
used uninitialized.

src/ChangeLog

@@ -5,8 +5,8 @@
 	(Fcurrent_bidi_paragraph_direction): Simplify slightly; this
 	avoids a gcc -Wuninitialized diagnostic.
 	(display_line, BUILD_COMPOSITE_GLYPH_STRING, draw_glyphs):
-	Mark variables that gcc -Wuninitialized cannot deduce are never
-	used uninitialized.
+	(note_mouse_highlight): Mark variables that gcc -Wuninitialized
+	does not deduce are never used uninitialized.
 	* lisp.h (IF_LINT): New macro, copied from ../lib-src/emacsclient.c
 	which in turn is copied from coreutils.

src/xdisp.c

@@ -25457,7 +25457,8 @@ note_mouse_highlight (struct frame *f, int x, int y)
 	    {
 	      /* The mouse-highlighting, if any, comes from an overlay
 		 or text property in the buffer.  */
-	      Lisp_Object buffer, cover_string;
+	      Lisp_Object buffer IF_LINT (= Qnil);
+	      Lisp_Object cover_string IF_LINT (= Qnil);
 	      if (STRINGP (object))
 		{