[PATCH] libstdc++: Define std::nothrow as inline variable

[Jonathan Wakely]

This makes it possible to use `new(std::nothrow) X` without linking to
libsupc++ or libstdc++.

To ensure we still export the symbol from the library we need to
suppress the inline variable in libsupc++/new_handler.cc which is done
by defining a macro.

libstdc++-v3/ChangeLog:

	* libsupc++/new (nothrow): Define as inline variable.
	* libsupc++/new_handler.cc (_GLIBCXX_DEFINE_NOTHROW_OBJ):
	Define.
---

Tested powerpc64le-linux.

 libstdc++-v3/libsupc++/new            | 4 ++++
 libstdc++-v3/libsupc++/new_handler.cc | 2 ++
 2 files changed, 6 insertions(+)

diff --git a/libstdc++-v3/libsupc++/new b/libstdc++-v3/libsupc++/new
index fb36dae25a6d..85d28ff40769 100644
--- a/libstdc++-v3/libsupc++/new
+++ b/libstdc++-v3/libsupc++/new
@@ -125,7 +125,11 @@ namespace std
 #endif
   };
 
+#if defined __cpp_inline_variables && ! defined _GLIBCXX_DEFINE_NOTHROW_OBJ
+  inline constexpr nothrow_t nothrow{};
+#else
   extern const nothrow_t nothrow;
+#endif
 
   /** If you write your own error handler to be called by @c new, it must
    *  be of this type.  */
diff --git a/libstdc++-v3/libsupc++/new_handler.cc b/libstdc++-v3/libsupc++/new_handler.cc
index 7cd3e5a69fde..96dfb796c64a 100644
--- a/libstdc++-v3/libsupc++/new_handler.cc
+++ b/libstdc++-v3/libsupc++/new_handler.cc
@@ -23,6 +23,8 @@
 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
 // <http://www.gnu.org/licenses/>.
 
+#define _GLIBCXX_DEFINE_NOTHROW_OBJ 1
+
 #include "new"
 #include <bits/atomic_lockfree_defines.h>
 
-- 
2.50.1