Port --enable-gcc-warnings to GCC 8

Backport from master.
* lib-src/emacsclient.c (fail):
Do not dereference a null pointer.
* src/frame.c (delete_frame):
Add a decl with UNINIT to work around GCC bug 85563.
* src/menu.h (finish_menu_items):
Do not use attribute const.
* src/regex.c (analyze_first): Use FALLTHROUGH, not a comment.

3 files changed, 3 insertions, 3 deletions

diff --git a/src/frame.c b/src/frame.c
index cee775c6fa9..0a6ca26f5d7 100644
--- a/src/frame.c
+++ b/src/frame.c
@@ -1933,6 +1933,7 @@ delete_frame (Lisp_Object frame, Lisp_Object force)
   if (f == sf)
     {
       Lisp_Object tail;
+      Lisp_Object frame1 UNINIT;  /* This line works around GCC bug 85563.  */
       eassume (CONSP (Vframe_list));
 
       /* Look for another visible frame on the same terminal.
diff --git a/src/menu.h b/src/menu.h
index 4c4ac83424f..1aa53f74544 100644
--- a/src/menu.h
+++ b/src/menu.h
@@ -30,7 +30,7 @@ enum {
 };
 
 extern void init_menu_items (void);
-extern void finish_menu_items (void) ATTRIBUTE_CONST;
+extern void finish_menu_items (void);
 extern void discard_menu_items (void);
 extern void save_menu_items (void);
 extern bool parse_single_submenu (Lisp_Object, Lisp_Object, Lisp_Object);
diff --git a/src/regex.c b/src/regex.c
index e8b99f6f023..4f9df68a9fe 100644
--- a/src/regex.c
+++ b/src/regex.c
@@ -4038,8 +4038,7 @@ analyze_first (const_re_char *p, const_re_char *pend, char *fastmap,
             };
           /* Keep `p1' to allow the `on_failure_jump' we are jumping to
              to jump back to "just after here".  */
-          /* Fallthrough */
-
+          FALLTHROUGH;
         case on_failure_jump:
         case on_failure_keep_string_jump:
         case on_failure_jump_nastyloop: