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].

2 files changed, 23 insertions, 11 deletions

diff --git a/gl/lib/rand-isaac.c b/gl/lib/rand-isaac.c
index defd21778..04af2e782 100644
--- a/gl/lib/rand-isaac.c
+++ b/gl/lib/rand-isaac.c
@@ -58,16 +58,26 @@ just (isaac_word a)
   return a & desired_bits;
 }
 
-/* The index operation.  On typical machines whose words are exactly
-   the right size, this is optimized to a mask, an addition, and an
-   indirect load.  Atypical machines need more work.  */
+/* The index operation.  */
 static inline isaac_word
 ind (isaac_word const *m, isaac_word x)
 {
-  return (sizeof *m * CHAR_BIT == ISAAC_BITS
-          ? (* (isaac_word *) ((char *) m
-                               + (x & ((ISAAC_WORDS - 1) * sizeof *m))))
-          : m[(x / (ISAAC_BITS / CHAR_BIT)) & (ISAAC_WORDS - 1)]);
+  if (sizeof *m * CHAR_BIT == ISAAC_BITS)
+    {
+      /* The typical case, where words are exactly the right size.
+         Optimize this to a mask, an addition, and an indirect
+         load.  */
+      void const *void_m = m;
+      char const *base_p = void_m;
+      void const *word_p = base_p + (x & ((ISAAC_WORDS - 1) * sizeof *m));
+      isaac_word const *p = word_p;
+      return *p;
+    }
+  else
+    {
+      /* Atypical machines need more work.  */
+      return m[(x / (ISAAC_BITS / CHAR_BIT)) & (ISAAC_WORDS - 1)];
+    }
 }
 
 /* Use and update *S to generate random data to fill RESULT.  */
diff --git a/gl/lib/randread.c b/gl/lib/randread.c
index dfba61182..8ee384751 100644
--- a/gl/lib/randread.c
+++ b/gl/lib/randread.c
@@ -275,12 +275,14 @@ readsource (struct randread_source *s, unsigned char *p, size_t size)
    the buffered ISAAC generator in ISAAC.  */
 
 static void
-readisaac (struct isaac *isaac, unsigned char *p, size_t size)
+readisaac (struct isaac *isaac, void *p, size_t size)
 {
   size_t inbytes = isaac->buffered;
 
   while (true)
     {
+      char *char_p = p;
+
       if (size <= inbytes)
         {
           memcpy (p, isaac->data.b + ISAAC_BYTES - inbytes, size);
@@ -289,14 +291,14 @@ readisaac (struct isaac *isaac, unsigned char *p, size_t size)
         }
 
       memcpy (p, isaac->data.b + ISAAC_BYTES - inbytes, inbytes);
-      p += inbytes;
+      p = char_p + inbytes;
       size -= inbytes;
 
       /* If P is aligned, write to *P directly to avoid the overhead
          of copying from the buffer.  */
       if (ALIGNED_POINTER (p, isaac_word))
         {
-          isaac_word *wp = (isaac_word *) p;
+          isaac_word *wp = p;
           while (ISAAC_BYTES <= size)
             {
               isaac_refill (&isaac->state, wp);
@@ -308,7 +310,7 @@ readisaac (struct isaac *isaac, unsigned char *p, size_t size)
                   return;
                 }
             }
-          p = (unsigned char *) wp;
+          p = wp;
         }
 
       isaac_refill (&isaac->state, isaac->data.w);