[PATCH] Don't override operator new if GDB is built with -fsanitize=address

[Yao Qi <qiyaoltc@gmail.com>]

Nowadays, if we build GDB with -fsanitize=address, we can get the asan
error below,

(gdb) quit
=================================================================
==9723==ERROR: AddressSanitizer: alloc-dealloc-mismatch (malloc vs operator delete) on 0x60200003bf70
    #0 0x7f88f3837527 in operator delete(void*) (/usr/lib/x86_64-linux-gnu/libasan.so.1+0x55527)
    #1 0xac8e13 in __gnu_cxx::new_allocator<void (*)()>::deallocate(void (**)(), unsigned long) /usr/include/c++/4.9/ext/new_allocator.h:110
    #2 0xac8cc2 in __gnu_cxx::__alloc_traits<std::allocator<void (*)()> >::deallocate(std::allocator<void (*)()>&, void (**)(), unsigned long) /usr/include/c++/4.9/ext/alloc_traits.h:185
....
0x60200003bf70 is located 0 bytes inside of 8-byte region [0x60200003bf70,0x60200003bf78)
allocated by thread T0 here:
    #0 0x7f88f38367ef in __interceptor_malloc (/usr/lib/x86_64-linux-gnu/libasan.so.1+0x547ef)
    #1 0xbd2762 in operator new(unsigned long) /home/yao/SourceCode/gnu/gdb/git/gdb/common/new-op.c:42
    #2 0xac8edc in __gnu_cxx::new_allocator<void (*)()>::allocate(unsigned long, void const*) /usr/include/c++/4.9/ext/new_allocator.h:104
    #3 0xac8d81 in __gnu_cxx::__alloc_traits<std::allocator<void (*)()> >::allocate(std::allocator<void (*)()>&, unsigned long) /usr/include/c++/4.9/ext/alloc_traits.h:182

The reason for this is that we override operator new but don't override
operator delete.  This patch does the override only if the code is NOT
compiled with asan.

gdb:

2016-10-25  Yao Qi  <yao.qi@linaro.org>

	PR gdb/20716
	* common/new-op.c (__has_feature): New macro.
	Don't override operator new if asan is used.
---
 gdb/common/new-op.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/gdb/common/new-op.c b/gdb/common/new-op.c
index 5ba4d6e..f04c5cb 100644
--- a/gdb/common/new-op.c
+++ b/gdb/common/new-op.c
@@ -17,6 +17,12 @@
    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
+/* GCC does not understand __has_feature.  */
+#if !defined(__has_feature)
+# define __has_feature(x) 0
+#endif
+
+#if !__has_feature(address_sanitizer) && !defined(__SANITIZE_ADDRESS__)
 #include "common-defs.h"
 #include "host-defs.h"
 #include <new>
@@ -83,3 +89,4 @@ operator new[] (std::size_t sz, const std::nothrow_t&)
 {
   return ::operator new (sz, std::nothrow);
 }
+#endif
-- 
1.9.1