g++ groks __attribute__((unused)) at least since 4.3.6.

Cannot find the exact moment from gcc release notes, but tests fine in 4.3.6.
(not fine = "warning: unused ...")

diff --git a/perl.h b/perl.h
index 193458c..8466bc7 100644 (file)
--- a/perl.h
+++ b/perl.h
@@ -309,7 +309,7 @@
 #endif
 
 #ifndef PERL_UNUSED_DECL
-#  if defined(HASATTRIBUTE_UNUSED) && !defined(__cplusplus)
+#  if defined(HASATTRIBUTE_UNUSED) && (!defined(__cplusplus) || (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 3)))
 #    define PERL_UNUSED_DECL __attribute__unused__
 #  else
 #    define PERL_UNUSED_DECL