[libcxx-commits] [libcxx] 2274c66 - [libc++] Use _If for conditional_t (#96193)

[via libcxx-commits]

Author: Nikolas Klauser
Date: 2024-06-25T16:53:17+02:00
New Revision: 2274c66e6faaaf29ad693b1ae3e5a7b0228a1950

URL: https://github.com/llvm/llvm-project/commit/2274c66e6faaaf29ad693b1ae3e5a7b0228a1950
DIFF: https://github.com/llvm/llvm-project/commit/2274c66e6faaaf29ad693b1ae3e5a7b0228a1950.diff

LOG: [libc++] Use _If for conditional_t (#96193)

This avoids different instantiations when the if and else types are
different, resulting in reduced memory use by the compiler.

Added: 
    

Modified: 
    libcxx/include/__type_traits/conditional.h

Removed: 
    


################################################################################
diff  --git a/libcxx/include/__type_traits/conditional.h b/libcxx/include/__type_traits/conditional.h
index 5b5445a837427..7d5849ee824e3 100644
--- a/libcxx/include/__type_traits/conditional.h
+++ b/libcxx/include/__type_traits/conditional.h
@@ -44,15 +44,14 @@ struct _LIBCPP_TEMPLATE_VIS conditional<false, _If, _Then> {
   using type _LIBCPP_NODEBUG = _Then;
 };
 
+template <bool _Bp, class _IfRes, class _ElseRes>
+using __conditional_t _LIBCPP_NODEBUG = _If<_Bp, _IfRes, _ElseRes>;
+
 #if _LIBCPP_STD_VER >= 14
 template <bool _Bp, class _IfRes, class _ElseRes>
-using conditional_t _LIBCPP_NODEBUG = typename conditional<_Bp, _IfRes, _ElseRes>::type;
+using conditional_t _LIBCPP_NODEBUG = __conditional_t<_Bp, _IfRes, _ElseRes>;
 #endif
 
-// Helper so we can use "conditional_t" in all language versions.
-template <bool _Bp, class _If, class _Then>
-using __conditional_t _LIBCPP_NODEBUG = typename conditional<_Bp, _If, _Then>::type;
-
 _LIBCPP_END_NAMESPACE_STD
 
 #endif // _LIBCPP___TYPE_TRAITS_CONDITIONAL_H