[src/trunk]: src/sys/sys Add Clang/LLVM specific feature/extension detection ...

[kamil <kamil%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/83dcc0fac87b
branches:  trunk
changeset: 454373:83dcc0fac87b
user:      kamil <kamil%NetBSD.org@localhost>
date:      Sun Sep 15 14:30:26 2019 +0000

description:
Add Clang/LLVM specific feature/extension detection macros in sys/cdefs.h

These macros are not supported (as of now) with GCC and there is need to
maintain a fallback that evaluates to 0.

diffstat:

 sys/sys/cdefs.h |  20 +++++++++++++++++++-
 1 files changed, 19 insertions(+), 1 deletions(-)

diffs (34 lines):

diff -r de7869029e00 -r 83dcc0fac87b sys/sys/cdefs.h
--- a/sys/sys/cdefs.h   Sun Sep 15 13:40:46 2019 +0000
+++ b/sys/sys/cdefs.h   Sun Sep 15 14:30:26 2019 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: cdefs.h,v 1.141 2019/02/21 21:34:05 christos Exp $     */
+/*     $NetBSD: cdefs.h,v 1.142 2019/09/15 14:30:26 kamil Exp $        */
 
 /* * Copyright (c) 1991, 1993
  *     The Regents of the University of California.  All rights reserved.
@@ -60,6 +60,24 @@
 #define        __GNUC_PREREQ__(x, y)   0
 #endif
 
+/*
+ * Macros to test Clang/LLVM features.
+ * Usage:
+ *
+ *     #if __has_feature(safe_stack)
+ *     ...SafeStack specific code...
+ *     #else
+ *     ..regular code...
+ *     #endif
+ */
+#ifndef __has_feature
+#define __has_feature(x)       0
+#endif
+
+#ifndef __has_extension
+#define __has_extension                __has_feature /* Compat with pre-3.0 Clang */
+#endif
+
 #include <machine/cdefs.h>
 #ifdef __ELF__
 #include <sys/cdefs_elf.h>