[gcc r16-6271] libstdc++: Use std::add_lvalue_reference in src/c++11/mutex.cc

[Jonathan Wakely]

https://gcc.gnu.org/g:116e0ce7fd5dc2ee352578d98d23158d9e180d90

commit r16-6271-g116e0ce7fd5dc2ee352578d98d23158d9e180d90
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Fri Dec 19 09:12:40 2025 +0000

    libstdc++: Use std::add_lvalue_reference in src/c++11/mutex.cc
    
    Adjust the return type to be consistent with how it's declared in
    <mutex>.
    
    libstdc++-v3/ChangeLog:
    
            * src/c++11/mutex.cc [_GLIBCXX_NO_EXTERN_THREAD_LOCAL]
            (__get_once_call): Use std::add_lvalue_reference.

Diff:
---
 libstdc++-v3/src/c++11/mutex.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libstdc++-v3/src/c++11/mutex.cc b/libstdc++-v3/src/c++11/mutex.cc
index 82f0afa4cb4e..91968ab47bd5 100644
--- a/libstdc++-v3/src/c++11/mutex.cc
+++ b/libstdc++-v3/src/c++11/mutex.cc
@@ -42,7 +42,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
   __get_once_callable() noexcept
   { return __once_callable; }
 
-  __typeof__(void (*)())&
+  std::add_lvalue_reference<void (*)()>::type
   __get_once_call() noexcept
   { return __once_call; }