maint: port --enable-gcc-warnings to clang

* configure.ac: If clang, add -Wno-format-extra-args and
-Wno-tautological-constant-out-of-range-compare.
* gl/lib/rand-isaac.c (ind):
* gl/lib/randread.c (readisaac):
* src/ls.c (dev_ino_push, dev_ino_pop):
* src/sort.c (buffer_linelim):
* src/system.h (is_nul):
* src/tail.c (tail_forever_inotify):
Rewrite to avoid casts that clang dislikes.
It's good to avoid casts anyway.
* src/expr.c (integer_overflow): Declare only if it exists.
(die): Remove; unused.
* src/ls.c (dev_ino_push): New function, replacing ...
(DEV_INO_PUSH): ... this removed macro.  All uses changed.
(decode_switches): Rewrite "str"+i to &str[i].

1 files changed, 3 insertions, 1 deletions

diff --git a/src/tail.c b/src/tail.c
index 6bbc7251f..0f1a37c07 100644
--- a/src/tail.c
+++ b/src/tail.c
@@ -1446,6 +1446,7 @@ tail_forever_inotify (int wd, struct File_spec *f, size_t n_files,
     {
       struct File_spec *fspec;
       struct inotify_event *ev;
+      void *void_ev;
 
       /* When following by name without --retry, and the last file has
          been unlinked or renamed-away, diagnose it and return.  */
@@ -1507,7 +1508,8 @@ tail_forever_inotify (int wd, struct File_spec *f, size_t n_files,
             error (EXIT_FAILURE, errno, _("error reading inotify event"));
         }
 
-      ev = (struct inotify_event *) (evbuf + evbuf_off);
+      void_ev = evbuf + evbuf_off;
+      ev = void_ev;
       evbuf_off += sizeof (*ev) + ev->len;
 
       if (ev->len) /* event on ev->name in watched directory  */