[libcxx-commits] [libcxx] Revert "[libc++] Use _If for conditional_t" (PR #96843)

[James Y Knight via libcxx-commits]

https://github.com/jyknight created https://github.com/llvm/llvm-project/pull/96843

Reverts llvm/llvm-project#96193

>From 379cd1193a8453850f0c2e12c005160d7535b373 Mon Sep 17 00:00:00 2001
From: James Y Knight <foom at fuhm.net>
Date: Wed, 26 Jun 2024 23:57:04 -0400
Subject: [PATCH] Revert "[libc++] Use _If for conditional_t (#96193)"

This reverts commit 2274c66e6faaaf29ad693b1ae3e5a7b0228a1950.
---
 libcxx/include/__type_traits/conditional.h | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/libcxx/include/__type_traits/conditional.h b/libcxx/include/__type_traits/conditional.h
index 7d5849ee824e3..5b5445a837427 100644
--- a/libcxx/include/__type_traits/conditional.h
+++ b/libcxx/include/__type_traits/conditional.h
@@ -44,14 +44,15 @@ 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 = __conditional_t<_Bp, _IfRes, _ElseRes>;
+using conditional_t _LIBCPP_NODEBUG = typename conditional<_Bp, _IfRes, _ElseRes>::type;
 #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