[libcxx-commits] [libcxx] [libc++][NFC] Use __copy_cv to implement __apply_cv (PR #86477)

[Nikolas Klauser via libcxx-commits]

https://github.com/philnik777 created https://github.com/llvm/llvm-project/pull/86477

None

>From 2004fe8975eb382036c9d5866d8bdcfadfca56b8 Mon Sep 17 00:00:00 2001
From: Nikolas Klauser <nikolasklauser at berlin.de>
Date: Mon, 25 Mar 2024 09:43:41 +0100
Subject: [PATCH] [libc++][NFC] Use __copy_cv to implement __apply_cv

---
 libcxx/include/__type_traits/apply_cv.h | 50 +++----------------------
 1 file changed, 5 insertions(+), 45 deletions(-)

diff --git a/libcxx/include/__type_traits/apply_cv.h b/libcxx/include/__type_traits/apply_cv.h
index 7c6aabec8344b1..723af95b8d9280 100644
--- a/libcxx/include/__type_traits/apply_cv.h
+++ b/libcxx/include/__type_traits/apply_cv.h
@@ -10,9 +10,7 @@
 #define _LIBCPP___TYPE_TRAITS_APPLY_CV_H
 
 #include <__config>
-#include <__type_traits/is_const.h>
-#include <__type_traits/is_volatile.h>
-#include <__type_traits/remove_reference.h>
+#include <__type_traits/copy_cv.h>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #  pragma GCC system_header
@@ -20,54 +18,16 @@
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-template <class _Tp,
-          bool = is_const<__libcpp_remove_reference_t<_Tp> >::value,
-          bool = is_volatile<__libcpp_remove_reference_t<_Tp> >::value>
-struct __apply_cv_impl {
-  template <class _Up>
-  using __apply _LIBCPP_NODEBUG = _Up;
-};
-
 template <class _Tp>
-struct __apply_cv_impl<_Tp, true, false> {
-  template <class _Up>
-  using __apply _LIBCPP_NODEBUG = const _Up;
-};
-
-template <class _Tp>
-struct __apply_cv_impl<_Tp, false, true> {
-  template <class _Up>
-  using __apply _LIBCPP_NODEBUG = volatile _Up;
-};
-
-template <class _Tp>
-struct __apply_cv_impl<_Tp, true, true> {
-  template <class _Up>
-  using __apply _LIBCPP_NODEBUG = const volatile _Up;
-};
-
-template <class _Tp>
-struct __apply_cv_impl<_Tp&, false, false> {
-  template <class _Up>
-  using __apply _LIBCPP_NODEBUG = _Up&;
-};
-
-template <class _Tp>
-struct __apply_cv_impl<_Tp&, true, false> {
-  template <class _Up>
-  using __apply _LIBCPP_NODEBUG = const _Up&;
-};
-
-template <class _Tp>
-struct __apply_cv_impl<_Tp&, false, true> {
+struct __apply_cv_impl {
   template <class _Up>
-  using __apply _LIBCPP_NODEBUG = volatile _Up&;
+  using __apply _LIBCPP_NODEBUG = __copy_cv_t<_Tp, _Up>;
 };
 
 template <class _Tp>
-struct __apply_cv_impl<_Tp&, true, true> {
+struct __apply_cv_impl<_Tp&> {
   template <class _Up>
-  using __apply _LIBCPP_NODEBUG = const volatile _Up&;
+  using __apply _LIBCPP_NODEBUG = __copy_cv_t<_Tp, _Up>&;
 };
 
 template <class _Tp, class _Up>