Suppress some unhelpful warnings when using clang.

* configure.ac: With clang, check for and use -Wno-switch,
-Wno-tautological-constant-out-of-range-compare and -Wno-pointer-sign.

* conf_post.h(assume): Use __builtin_unreachable for clang.

* src/filelock.c (lock_file_1): Rearrange to remove compiler warning
about excess arguments to snprintf.

3 files changed, 27 insertions, 4 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index 668ebeb8537..29cd8676584 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,10 @@
+2013-09-23  Jan Djärv  <jan.h.d@swipnet.se>
+
+        * filelock.c (lock_file_1): Rearrange to remove compiler warning
+        about excess arguments to snprintf.
+
+        * conf_post.h(assume): Use __builtin_unreachable for clang.
+
 2013-09-23  Juanma Barranquero  <lekktu@gmail.com>
 
         * w32console.c (initialize_w32_display): Remove unused variable hlinfo.
diff --git a/src/conf_post.h b/src/conf_post.h
index 14af38ce70b..7d4e1f43ed7 100644
--- a/src/conf_post.h
+++ b/src/conf_post.h
@@ -248,12 +248,20 @@ extern void _DebPrint (const char *fmt, ...);
 # define FLEXIBLE_ARRAY_MEMBER 1
 #endif
 
+#ifdef __clang__
+# ifndef __has_builtin
+#  define __has_builtin(x) 0
+# endif
+#endif
+
 /* assume(cond) tells the compiler (and lint) that a certain condition
  * will always hold, and that it should optimize (or check) accordingly. */
 #if defined lint
 # define assume(cond) ((cond) ? (void) 0 : abort ())
 #elif (__GNUC__ == 4 && __GNUC_MINOR__ >= 5) || __GNUC__ > 4
 # define assume(cond) ((cond) || (__builtin_unreachable(), 0))
+#elif defined (__clang__) && __has_builtin (__builtin_unreachable)
+# define assume(cond) ((cond) || (__builtin_unreachable(), 0))
 #elif defined __MSC_VER
 # define assume(cond) __assume ((cond))
 #else
diff --git a/src/filelock.c b/src/filelock.c
index df72eff5950..2f53047f526 100644
--- a/src/filelock.c
+++ b/src/filelock.c
@@ -459,10 +459,18 @@ lock_file_1 (char *lfname, bool force)
   char lock_info_str[MAX_LFINFO + 1];
   printmax_t pid = getpid ();
 
-  if (sizeof lock_info_str
-      <= snprintf (lock_info_str, sizeof lock_info_str,
-                   boot ? "%s@%s.%"pMd":%"pMd : "%s@%s.%"pMd,
-                   user_name, host_name, pid, boot))
+  if (boot)
+    {
+      if (sizeof lock_info_str
+          <= snprintf (lock_info_str, sizeof lock_info_str,
+                       "%s@%s.%"pMd":%"pMd,
+                       user_name, host_name, pid, boot))
+        return ENAMETOOLONG;
+    }
+  else if (sizeof lock_info_str
+           <= snprintf (lock_info_str, sizeof lock_info_str,
+                        "%s@%s.%"pMd,
+                        user_name, host_name, pid))
     return ENAMETOOLONG;
 
   return create_lock_file (lfname, lock_info_str, force);