[libc++][NFC] Replace __apply_cv with __copy_cv or __copy_cvref #90867

philnik777 · 2024-05-02T15:58:32Z

__apply_cv_t and __copy_cvref_t are very closely related. They are in fact identical except that __copy_cvref_t handles rvalue references properly. Some uses don't actually require handling of references, so they are replaced with __copy_cv_t.

llvmbot · 2024-05-10T09:23:38Z

@llvm/pr-subscribers-libcxx

Author: Nikolas Klauser (philnik777)

Changes

__apply_cv_t and __copy_cvref_t are very closely related. They are in fact idendical except that __copy_cvref_t handles rvalue reference properly. Some uses don't actually require handling of references, so they are replaced with __copy_cv_t.

Full diff: https://github.com/llvm/llvm-project/pull/90867.diff

9 Files Affected:

(modified) libcxx/include/CMakeLists.txt (-1)
(modified) libcxx/include/__tuple/make_tuple_types.h (+3-3)
(removed) libcxx/include/__type_traits/apply_cv.h (-38)
(modified) libcxx/include/__type_traits/make_signed.h (+1-2)
(modified) libcxx/include/__type_traits/make_unsigned.h (+2-2)
(modified) libcxx/include/cwchar (+2-2)
(modified) libcxx/include/module.modulemap (-5)
(modified) libcxx/include/tuple (+9-10)
(modified) libcxx/include/type_traits (-1)

diff --git a/libcxx/include/CMakeLists.txt b/libcxx/include/CMakeLists.txt
index 1296c536bc882..abc9489fc7b95 100644
--- a/libcxx/include/CMakeLists.txt
+++ b/libcxx/include/CMakeLists.txt
@@ -731,7 +731,6 @@ set(files
   __type_traits/aligned_storage.h
   __type_traits/aligned_union.h
   __type_traits/alignment_of.h
-  __type_traits/apply_cv.h
   __type_traits/can_extract_key.h
   __type_traits/common_reference.h
   __type_traits/common_type.h
diff --git a/libcxx/include/__tuple/make_tuple_types.h b/libcxx/include/__tuple/make_tuple_types.h
index 43161b17cfa3a..9e0fefae2f2f5 100644
--- a/libcxx/include/__tuple/make_tuple_types.h
+++ b/libcxx/include/__tuple/make_tuple_types.h
@@ -16,7 +16,7 @@
 #include <__tuple/tuple_indices.h>
 #include <__tuple/tuple_size.h>
 #include <__tuple/tuple_types.h>
-#include <__type_traits/apply_cv.h>
+#include <__type_traits/copy_cvref.h>
 #include <__type_traits/remove_cv.h>
 #include <__type_traits/remove_reference.h>
 #include <cstddef>
@@ -41,7 +41,7 @@ template <template <class...> class _Tuple, class... _Types, size_t... _Idx>
 struct __make_tuple_types_flat<_Tuple<_Types...>, __tuple_indices<_Idx...>> {
   // Specialization for pair, tuple, and __tuple_types
   template <class _Tp>
-  using __apply_quals _LIBCPP_NODEBUG = __tuple_types<__apply_cv_t<_Tp, __type_pack_element<_Idx, _Types...>>...>;
+  using __apply_quals _LIBCPP_NODEBUG = __tuple_types<__copy_cvref_t<_Tp, __type_pack_element<_Idx, _Types...>>...>;
 };
 
 template <class _Vt, size_t _Np, size_t... _Idx>
@@ -49,7 +49,7 @@ struct __make_tuple_types_flat<array<_Vt, _Np>, __tuple_indices<_Idx...>> {
   template <size_t>
   using __value_type = _Vt;
   template <class _Tp>
-  using __apply_quals = __tuple_types<__apply_cv_t<_Tp, __value_type<_Idx>>...>;
+  using __apply_quals = __tuple_types<__copy_cvref_t<_Tp, __value_type<_Idx>>...>;
 };
 
 template <class _Tp,
diff --git a/libcxx/include/__type_traits/apply_cv.h b/libcxx/include/__type_traits/apply_cv.h
deleted file mode 100644
index 723af95b8d928..0000000000000
--- a/libcxx/include/__type_traits/apply_cv.h
+++ /dev/null
@@ -1,38 +0,0 @@
-//===----------------------------------------------------------------------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef _LIBCPP___TYPE_TRAITS_APPLY_CV_H
-#define _LIBCPP___TYPE_TRAITS_APPLY_CV_H
-
-#include <__config>
-#include <__type_traits/copy_cv.h>
-
-#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
-#  pragma GCC system_header
-#endif
-
-_LIBCPP_BEGIN_NAMESPACE_STD
-
-template <class _Tp>
-struct __apply_cv_impl {
-  template <class _Up>
-  using __apply _LIBCPP_NODEBUG = __copy_cv_t<_Tp, _Up>;
-};
-
-template <class _Tp>
-struct __apply_cv_impl<_Tp&> {
-  template <class _Up>
-  using __apply _LIBCPP_NODEBUG = __copy_cv_t<_Tp, _Up>&;
-};
-
-template <class _Tp, class _Up>
-using __apply_cv_t _LIBCPP_NODEBUG = typename __apply_cv_impl<_Tp>::template __apply<_Up>;
-
-_LIBCPP_END_NAMESPACE_STD
-
-#endif // _LIBCPP___TYPE_TRAITS_APPLY_CV_H
diff --git a/libcxx/include/__type_traits/make_signed.h b/libcxx/include/__type_traits/make_signed.h
index 1a8a35f3859d2..c1fc009d9ba2e 100644
--- a/libcxx/include/__type_traits/make_signed.h
+++ b/libcxx/include/__type_traits/make_signed.h
@@ -10,7 +10,6 @@
 #define _LIBCPP___TYPE_TRAITS_MAKE_SIGNED_H
 
 #include <__config>
-#include <__type_traits/apply_cv.h>
 #include <__type_traits/is_enum.h>
 #include <__type_traits/is_integral.h>
 #include <__type_traits/nat.h>
@@ -70,7 +69,7 @@ template <> struct __make_signed<__uint128_t,        true> {typedef __int128_t t
 // clang-format on
 
 template <class _Tp>
-using __make_signed_t = __apply_cv_t<_Tp, typename __make_signed<__remove_cv_t<_Tp> >::type>;
+using __make_signed_t = __copy_cv_t<_Tp, typename __make_signed<__remove_cv_t<_Tp> >::type>;
 
 #endif // __has_builtin(__make_signed)
 
diff --git a/libcxx/include/__type_traits/make_unsigned.h b/libcxx/include/__type_traits/make_unsigned.h
index 98967371e7738..282cd2d911316 100644
--- a/libcxx/include/__type_traits/make_unsigned.h
+++ b/libcxx/include/__type_traits/make_unsigned.h
@@ -10,8 +10,8 @@
 #define _LIBCPP___TYPE_TRAITS_MAKE_UNSIGNED_H
 
 #include <__config>
-#include <__type_traits/apply_cv.h>
 #include <__type_traits/conditional.h>
+#include <__type_traits/copy_cv.h>
 #include <__type_traits/is_enum.h>
 #include <__type_traits/is_integral.h>
 #include <__type_traits/is_unsigned.h>
@@ -72,7 +72,7 @@ template <> struct __make_unsigned<__uint128_t,        true> {typedef __uint128_
 // clang-format on
 
 template <class _Tp>
-using __make_unsigned_t = __apply_cv_t<_Tp, typename __make_unsigned<__remove_cv_t<_Tp> >::type>;
+using __make_unsigned_t = __copy_cv_t<_Tp, typename __make_unsigned<__remove_cv_t<_Tp> >::type>;
 
 #endif // __has_builtin(__make_unsigned)
 
diff --git a/libcxx/include/cwchar b/libcxx/include/cwchar
index 4cc6f56c389bf..08cfac58c846a 100644
--- a/libcxx/include/cwchar
+++ b/libcxx/include/cwchar
@@ -103,7 +103,7 @@ size_t wcsrtombs(char* restrict dst, const wchar_t** restrict src, size_t len,
 */
 
 #include <__config>
-#include <__type_traits/apply_cv.h>
+#include <__type_traits/copy_cv.h>
 #include <__type_traits/is_constant_evaluated.h>
 #include <__type_traits/is_equality_comparable.h>
 #include <__type_traits/is_same.h>
@@ -236,7 +236,7 @@ _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _Tp* __constexpr_wmemchr(_Tp
     wchar_t __value_buffer = 0;
     __builtin_memcpy(&__value_buffer, &__value, sizeof(wchar_t));
     return reinterpret_cast<_Tp*>(
-        __builtin_wmemchr(reinterpret_cast<__apply_cv_t<_Tp, wchar_t>*>(__str), __value_buffer, __count));
+        __builtin_wmemchr(reinterpret_cast<__copy_cv_t<_Tp, wchar_t>*>(__str), __value_buffer, __count));
   }
 #  if _LIBCPP_STD_VER >= 17
   else if constexpr (is_same_v<remove_cv_t<_Tp>, wchar_t>)
diff --git a/libcxx/include/module.modulemap b/libcxx/include/module.modulemap
index 8727ab88f16c0..51d5017cedb1a 100644
--- a/libcxx/include/module.modulemap
+++ b/libcxx/include/module.modulemap
@@ -1851,11 +1851,6 @@ module std_private_type_traits_add_volatile                              [system
 module std_private_type_traits_aligned_storage                           [system] { header "__type_traits/aligned_storage.h" }
 module std_private_type_traits_aligned_union                             [system] { header "__type_traits/aligned_union.h" }
 module std_private_type_traits_alignment_of                              [system] { header "__type_traits/alignment_of.h" }
-module std_private_type_traits_apply_cv                                  [system] {
-  header "__type_traits/apply_cv.h"
-  export std_private_type_traits_is_const
-  export std_private_type_traits_is_volatile
-}
 module std_private_type_traits_can_extract_key                           [system] { header "__type_traits/can_extract_key.h" }
 module std_private_type_traits_common_reference                          [system] {
   header "__type_traits/common_reference.h"
diff --git a/libcxx/include/tuple b/libcxx/include/tuple
index c7fc5509a0f80..fecfc316c2ac8 100644
--- a/libcxx/include/tuple
+++ b/libcxx/include/tuple
@@ -222,7 +222,6 @@ template <class... Types>
 #include <__tuple/tuple_like_ext.h>
 #include <__tuple/tuple_size.h>
 #include <__tuple/tuple_types.h>
-#include <__type_traits/apply_cv.h>
 #include <__type_traits/common_reference.h>
 #include <__type_traits/common_type.h>
 #include <__type_traits/conditional.h>
@@ -1286,14 +1285,14 @@ struct __tuple_cat_return_ref_imp;
 template <class... _Types, size_t... _I0, class _Tuple0>
 struct __tuple_cat_return_ref_imp<tuple<_Types...>, __tuple_indices<_I0...>, _Tuple0> {
   typedef _LIBCPP_NODEBUG __libcpp_remove_reference_t<_Tuple0> _T0;
-  typedef tuple<_Types..., __apply_cv_t<_Tuple0, typename tuple_element<_I0, _T0>::type>&&...> type;
+  typedef tuple<_Types..., __copy_cvref_t<_Tuple0, typename tuple_element<_I0, _T0>::type>&&...> type;
 };
 
 template <class... _Types, size_t... _I0, class _Tuple0, class _Tuple1, class... _Tuples>
 struct __tuple_cat_return_ref_imp<tuple<_Types...>, __tuple_indices<_I0...>, _Tuple0, _Tuple1, _Tuples...>
     : public __tuple_cat_return_ref_imp<
           tuple<_Types...,
-                __apply_cv_t<_Tuple0, typename tuple_element<_I0, __libcpp_remove_reference_t<_Tuple0>>::type>&&...>,
+                __copy_cvref_t<_Tuple0, typename tuple_element<_I0, __libcpp_remove_reference_t<_Tuple0>>::type>&&...>,
           typename __make_tuple_indices<tuple_size<__libcpp_remove_reference_t<_Tuple1> >::value>::type,
           _Tuple1,
           _Tuples...> {};
@@ -1327,7 +1326,7 @@ struct __tuple_cat<tuple<_Types...>, __tuple_indices<_I0...>, __tuple_indices<_J
     (void)__t; // avoid unused parameter warning on GCC when _I0 is empty
     typedef _LIBCPP_NODEBUG __libcpp_remove_reference_t<_Tuple0> _T0;
     typedef _LIBCPP_NODEBUG __libcpp_remove_reference_t<_Tuple1> _T1;
-    return __tuple_cat<tuple<_Types..., __apply_cv_t<_Tuple0, typename tuple_element<_J0, _T0>::type>&&...>,
+    return __tuple_cat<tuple<_Types..., __copy_cvref_t<_Tuple0, typename tuple_element<_J0, _T0>::type>&&...>,
                        typename __make_tuple_indices<sizeof...(_Types) + tuple_size<_T0>::value>::type,
                        typename __make_tuple_indices<tuple_size<_T1>::value>::type>()(
         std::forward_as_tuple(
@@ -1375,22 +1374,22 @@ inline _LIBCPP_HIDE_FROM_ABI constexpr _Tp __make_from_tuple_impl(_Tuple&& __t,
 }
 #else
 template <class _Tp, class _Tuple, size_t... _Idx>
-inline _LIBCPP_HIDE_FROM_ABI constexpr _Tp __make_from_tuple_impl(_Tuple&& __t, __tuple_indices<_Idx...>, 
+inline _LIBCPP_HIDE_FROM_ABI constexpr _Tp __make_from_tuple_impl(_Tuple&& __t, __tuple_indices<_Idx...>,
     enable_if_t<is_constructible_v<_Tp, decltype(std::get<_Idx>(std::forward<_Tuple>(__t)))...>> * = nullptr)
     _LIBCPP_NOEXCEPT_RETURN(_Tp(std::get<_Idx>(std::forward<_Tuple>(__t))...))
 #endif // _LIBCPP_STD_VER >= 20
 
-template <class _Tp, class _Tuple, 
+template <class _Tp, class _Tuple,
           class _Seq = typename __make_tuple_indices<tuple_size_v<remove_reference_t<_Tuple>>>::type, class = void>
 inline constexpr bool __can_make_from_tuple = false;
 
 template <class _Tp, class _Tuple, size_t... _Idx>
-inline constexpr bool __can_make_from_tuple<_Tp, _Tuple, __tuple_indices<_Idx...>, 
+inline constexpr bool __can_make_from_tuple<_Tp, _Tuple, __tuple_indices<_Idx...>,
     enable_if_t<is_constructible_v<_Tp, decltype(std::get<_Idx>(std::declval<_Tuple>()))...>>> = true;
 
-// Based on LWG3528(https://wg21.link/LWG3528) and http://eel.is/c++draft/description#structure.requirements-9, 
-// the standard allows to impose requirements, we constraint std::make_from_tuple to make std::make_from_tuple 
-// SFINAE friendly and also avoid worse diagnostic messages. We still keep the constraints of std::__make_from_tuple_impl 
+// Based on LWG3528(https://wg21.link/LWG3528) and http://eel.is/c++draft/description#structure.requirements-9,
+// the standard allows to impose requirements, we constraint std::make_from_tuple to make std::make_from_tuple
+// SFINAE friendly and also avoid worse diagnostic messages. We still keep the constraints of std::__make_from_tuple_impl
 // so that std::__make_from_tuple_impl will have the same advantages when used alone.
 #if _LIBCPP_STD_VER >= 20
 template <class _Tp, class _Tuple>
diff --git a/libcxx/include/type_traits b/libcxx/include/type_traits
index 10f9b881c0e4a..aee9fcf4137f3 100644
--- a/libcxx/include/type_traits
+++ b/libcxx/include/type_traits
@@ -428,7 +428,6 @@ namespace std
 #include <__type_traits/aligned_storage.h>
 #include <__type_traits/aligned_union.h>
 #include <__type_traits/alignment_of.h>
-#include <__type_traits/apply_cv.h>
 #include <__type_traits/can_extract_key.h>
 #include <__type_traits/common_reference.h>
 #include <__type_traits/common_type.h>

[libc++][NFC] Replace __apply_cv with __copy_cv or __copy_cvref

6fddf26

philnik777 force-pushed the remove_apply_cv branch from 094bd62 to 6fddf26 Compare May 2, 2024 20:35

philnik777 marked this pull request as ready for review May 10, 2024 09:23

philnik777 requested a review from a team as a code owner May 10, 2024 09:23

llvmbot added the libc++ libc++ C++ Standard Library. Not GNU libstdc++. Not libc++abi. label May 10, 2024

ldionne approved these changes May 10, 2024

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philnik777 merged commit 05f88b1 into llvm:main May 10, 2024
3 checks passed

philnik777 deleted the remove_apply_cv branch May 10, 2024 18:06

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[libc++][NFC] Replace __apply_cv with __copy_cv or __copy_cvref #90867

[libc++][NFC] Replace __apply_cv with __copy_cv or __copy_cvref #90867

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philnik777 commented May 2, 2024 •

edited by ldionne

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[libc++][NFC] Replace __apply_cv with __copy_cv or __copy_cvref #90867

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edited by ldionne

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