ignore-value: clarify some comments

* lib/ignore-value.h: Add Eric Blake as an author since
he rewrote the macros.
(ignore_value): Specify exactly when the GCC warn_unused_result
feature became available.
(ignore_ptr): Mention that ignore_value supports aggregates.

diff --git a/ChangeLog b/ChangeLog
index c3856f1..1afdc08 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2011-01-07  Pádraig Brady <P@draigBrady.com>
+
+       ignore-value: fixup comments, and add Eric Blake
+       as an author since he rewrote the macros.
+       * lib/ignore-value.h (ignore_value):  State that
+       we now support aggregates.  Also specify exactly
+       when the GCC warn_unused_result feature was added.
+
 2011-01-06  Eric Blake  <eblake@redhat.com>
 
        ignore-value: support aggregate types

diff --git a/lib/ignore-value.h b/lib/ignore-value.h
index 52804dc..7fd4772 100644 (file)
--- a/lib/ignore-value.h
+++ b/lib/ignore-value.h
@@ -15,7 +15,7 @@
    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
-/* Written by Jim Meyering and Pádraig Brady.  */
+/* Written by Jim Meyering, Eric Blake and Pádraig Brady.  */
 
 /* Use "ignore_value" to avoid a warning when using a function declared with
    gcc's warn_unused_result attribute, but for which you really do want to
@@ -47,13 +47,17 @@
 #  endif
 # endif
 
-# if __GNUC__ < 3 || (__GNUC__ == 3 && __GNUC_MINOR__ < 1)
+/* The __attribute__((__warn_unused_result__)) feature
+   is available in gcc versions 3.4 and newer,
+   while the typeof feature has been available since 2.7 at least.  */
+# if __GNUC__ < 3 || (__GNUC__ == 3 && __GNUC_MINOR__ < 4)
 #  define ignore_value(x) ((void) (x))
 # else
 #  define ignore_value(x) (({ __typeof__ (x) __x = (x); (void) __x; }))
 # endif
 
-/* ignore_value works for both scalars and pointers; deprecate ignore_ptr.  */
+/* ignore_value works for scalars, pointers and aggregates;
+   deprecate ignore_ptr.  */
 static inline void ATTRIBUTE_DEPRECATED
 ignore_ptr (void *p) { (void) p; } /* deprecated: use ignore_value */