lib: or2: define in GCC-specific way.

* lib.h (or2): Define simply using the ?: operator from
GNU C, eliminating the explicit temporary variable.
(uses_or2): For GNU C, we make this a dummy, harmless
declaration. If memory serves me, one of the few good ways
to do that it without eliciting unused warnings is to
declare an enum.

1 files changed, 5 insertions, 1 deletions

diff --git a/lib.h b/lib.h
index 34f00c09..a161133c 100644
--- a/lib.h
+++ b/lib.h
@@ -1442,9 +1442,13 @@ INLINE int null_or_missing_p(val v) { return (nilp(v) || missingp(v)); }
 
 #define if3(a, b, c) ((a) ? (b) : (c))
 
+#ifdef __GNUC__
+#define uses_or2 enum { f_o_o_ ## __LINE__ }
+#define or2(a, b) ((a) ?: (b))
+#else
 #define uses_or2 val or2_temp
-
 #define or2(a, b) ((or2_temp = (a)) ? or2_temp : (b))
+#endif
 
 #define or3(a, b, c) or2(a, or2(b, c))