[PATCH 3/5] gcc: quiet Wattribute for no_sanitize("address")

[Sebastian Huber]

From: rlibby <rlibby@FreeBSD.org>

This is an unfortunate instance where the __has_attribute check does
not function usefully.  Gcc does have the attribute, but for gcc it only
applies to functions, not variables, and trying to apply it to a
variable generates Wattribute.  So far we only apply the attribute to
variables.  Only enable the attribute for clang, for now.

Reviewed by:	Anton Rang <rang at acm.org>
Sponsored by:	Dell EMC Isilon
Differential Revision:	https://reviews.freebsd.org/D22875
---
 newlib/libc/include/sys/cdefs.h | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/newlib/libc/include/sys/cdefs.h b/newlib/libc/include/sys/cdefs.h
index 1f2ce063d..1be994ffd 100644
--- a/newlib/libc/include/sys/cdefs.h
+++ b/newlib/libc/include/sys/cdefs.h
@@ -709,8 +709,12 @@
 /* Function should not be analyzed. */
 #define	__no_lock_analysis	__lock_annotate(no_thread_safety_analysis)
 
-/* Function or variable should not be sanitized, ie. by AddressSanitizer */
-#if __has_attribute(no_sanitize)
+/*
+ * Function or variable should not be sanitized, i.e. by AddressSanitizer.
+ * GCC has the nosanitize attribute, but as a function attribute only, and
+ * warns on use as a variable attribute.
+ */
+#if __has_attribute(no_sanitize) && defined(__clang__)
 #define __nosanitizeaddress	__attribute__((no_sanitize("address")))
 #else
 #define __nosanitizeaddress
-- 
2.26.2