[gcc r12-10421] libstdc++: Protect against macros

[Matthias Kretz]

https://gcc.gnu.org/g:81830862ee431e93c4008c87da8ab352dc79770d

commit r12-10421-g81830862ee431e93c4008c87da8ab352dc79770d
Author: Matthias Kretz <m.kretz@gsi.de>
Date:   Fri Jun 2 21:21:36 2023 +0200

    libstdc++: Protect against macros
    
    Signed-off-by: Matthias Kretz <m.kretz@gsi.de>
    
    libstdc++-v3/ChangeLog:
    
            * include/experimental/bits/simd.h (__bit_cast): Use
            __gnu__::__vector_size__ instead of gnu::vector_size.
    
    (cherry picked from commit ce2188e4320cbb46d6246bd3f478ba20440c62f3)

Diff:
---
 libstdc++-v3/include/experimental/bits/simd.h | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/libstdc++-v3/include/experimental/bits/simd.h b/libstdc++-v3/include/experimental/bits/simd.h
index b18ce9d34a27..6f7418a840ea 100644
--- a/libstdc++-v3/include/experimental/bits/simd.h
+++ b/libstdc++-v3/include/experimental/bits/simd.h
@@ -1743,18 +1743,18 @@ template <typename _To, typename _From>
       return reinterpret_cast<_To>(__x);
     else if constexpr (__is_vector_type_v<_To> && __from_is_vectorizable)
       {
-	using _FV [[gnu::vector_size(sizeof(_From))]] = _From;
+	using _FV [[__gnu__::__vector_size__(sizeof(_From))]] = _From;
 	return reinterpret_cast<_To>(_FV{__x});
       }
     else if constexpr (__to_is_vectorizable && __from_is_vectorizable)
       {
-	using _TV [[gnu::vector_size(sizeof(_To))]] = _To;
-	using _FV [[gnu::vector_size(sizeof(_From))]] = _From;
+	using _TV [[__gnu__::__vector_size__(sizeof(_To))]] = _To;
+	using _FV [[__gnu__::__vector_size__(sizeof(_From))]] = _From;
 	return reinterpret_cast<_TV>(_FV{__x})[0];
       }
     else if constexpr (__to_is_vectorizable && __is_vector_type_v<_From>)
       {
-	using _TV [[gnu::vector_size(sizeof(_To))]] = _To;
+	using _TV [[__gnu__::__vector_size__(sizeof(_To))]] = _To;
 	return reinterpret_cast<_TV>(__x)[0];
       }
     else