Port EXTERNALLY_VISIBLE to Clang 3.2.

* conf_post.h (__has_attribute): New macro.
(EXTERNALLY_VISIBLE): Use it.  This ports to Clang 3.2.

2 files changed, 13 insertions, 1 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index 3fabe7579a9..79d1982cc0e 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,9 @@
+2012-12-28  Paul Eggert  <eggert@cs.ucla.edu>
+
+        Port EXTERNALLY_VISIBLE to Clang 3.2.
+        * conf_post.h (__has_attribute): New macro.
+        (EXTERNALLY_VISIBLE): Use it.  This ports to Clang 3.2.
+
 2012-12-27  Glenn Morris  <rgm@gnu.org>
 
         * cygw32.c (Fcygwin_convert_file_name_to_windows)
diff --git a/src/conf_post.h b/src/conf_post.h
index b1997e79081..37a426fc451 100644
--- a/src/conf_post.h
+++ b/src/conf_post.h
@@ -40,6 +40,10 @@ along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 #endif
 #endif
 
+#ifndef __has_attribute
+# define __has_attribute(a) 0 /* non-clang */
+#endif
+
 /* This silences a few compilation warnings on FreeBSD.  */
 #ifdef BSD_SYSTEM_AHB
 #undef BSD_SYSTEM_AHB
@@ -191,7 +195,9 @@ extern void _DebPrint (const char *fmt, ...);
 #define NO_INLINE
 #endif
 
-#if (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 1))
+#if (__clang__                                                          \
+     ? __has_attribute (externally_visible)                             \
+     : (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 1)))
 #define EXTERNALLY_VISIBLE __attribute__((externally_visible))
 #else
 #define EXTERNALLY_VISIBLE