[gcc r13-4481] libstdc++, Darwin: Fix weak attribute to use __weak__ instead of weak.

[Iain D Sandoe]

https://gcc.gnu.org/g:e76a44bf68b79278cb2c20e4ce87657a247adcfe

commit r13-4481-ge76a44bf68b79278cb2c20e4ce87657a247adcfe
Author: Iain Sandoe <iain@sandoe.co.uk>
Date:   Sat Dec 3 11:57:59 2022 +0000

    libstdc++, Darwin: Fix weak attribute to use __weak__ instead of weak.
    
    The text for _GLIBCXX_WEAK_DEFINITION has used 'weak' for the attribute name,
    since its intoduction.  Amend to use the implementation namespace '__weak__'
    version.
    
    Signed-off-by: Iain Sandoe <iain@sandoe.co.uk>
    
    libstdc++-v3/ChangeLog:
    
            * config/os/bsd/darwin/os_defines.h (_GLIBCXX_WEAK_DEFINITION): Use the
            implementation namespace for the weak attribute.

Diff:
---
 libstdc++-v3/config/os/bsd/darwin/os_defines.h | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/libstdc++-v3/config/os/bsd/darwin/os_defines.h b/libstdc++-v3/config/os/bsd/darwin/os_defines.h
index a8b6d4fa324..38fdfb5f6f0 100644
--- a/libstdc++-v3/config/os/bsd/darwin/os_defines.h
+++ b/libstdc++-v3/config/os/bsd/darwin/os_defines.h
@@ -33,11 +33,11 @@
    links to, so there's no need for weak-ness for that.  */
 #define _GLIBCXX_GTHREAD_USE_WEAK 0
 
-// On Darwin, in order to enable overriding of operator new and delete,
-// GCC makes the definition of these functions weak, relies on the
-// loader to implement weak semantics properly, and uses
-// -flat_namespace to work around the way that it doesn't.
-#define _GLIBCXX_WEAK_DEFINITION __attribute__ ((weak))
+// On Darwin, in order to enable overriding of operator new and delete, the
+// ABI library exports a weak definition. The static linker will override this
+// iff a user-provided implementation is given (providing that the user
+// implementation is not itself a weak definition).
+#define _GLIBCXX_WEAK_DEFINITION __attribute__ ((__weak__))
 
 // Static initializer macro is buggy in darwin, see libstdc++/51906
 #define _GTHREAD_USE_RECURSIVE_MUTEX_INIT_FUNC