[libc++] Use GCC type traits builtins for remove_cv and remove_cvref #81386
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@llvm/pr-subscribers-libcxx Author: Nikolas Klauser (philnik777) ChangesFull diff: https://github.com/llvm/llvm-project/pull/81386.diff 2 Files Affected:
diff --git a/libcxx/include/__type_traits/remove_cv.h b/libcxx/include/__type_traits/remove_cv.h
index c4bf612794bd55..4940a667b8c168 100644
--- a/libcxx/include/__type_traits/remove_cv.h
+++ b/libcxx/include/__type_traits/remove_cv.h
@@ -19,22 +19,17 @@
_LIBCPP_BEGIN_NAMESPACE_STD
-#if __has_builtin(__remove_cv) && !defined(_LIBCPP_COMPILER_GCC)
template <class _Tp>
struct remove_cv {
using type _LIBCPP_NODEBUG = __remove_cv(_Tp);
};
+#if defined(_LIBCPP_COMPILER_GCC)
template <class _Tp>
using __remove_cv_t = __remove_cv(_Tp);
#else
template <class _Tp>
-struct _LIBCPP_TEMPLATE_VIS remove_cv {
- typedef __remove_volatile_t<__remove_const_t<_Tp> > type;
-};
-
-template <class _Tp>
-using __remove_cv_t = __remove_volatile_t<__remove_const_t<_Tp> >;
+using __remove_cv_t = remove_cv<_Tp>::type;
#endif // __has_builtin(__remove_cv)
#if _LIBCPP_STD_VER >= 14
diff --git a/libcxx/include/__type_traits/remove_cvref.h b/libcxx/include/__type_traits/remove_cvref.h
index e8e8745ab09609..a536fb789fcb4e 100644
--- a/libcxx/include/__type_traits/remove_cvref.h
+++ b/libcxx/include/__type_traits/remove_cvref.h
@@ -20,21 +20,26 @@
_LIBCPP_BEGIN_NAMESPACE_STD
-#if __has_builtin(__remove_cvref) && !defined(_LIBCPP_COMPILER_GCC)
+#if defined(_LIBCPP_COMPILER_GCC)
template <class _Tp>
-using __remove_cvref_t _LIBCPP_NODEBUG = __remove_cvref(_Tp);
+struct __remove_cvref_gcc {
+ using type = __remove_cvref(_Tp);
+};
+
+template <class _Tp>
+using __remove_cvref_t _LIBCPP_NODEBUG = __remove_cvref_gcc<_Tp>::type;
#else
template <class _Tp>
-using __remove_cvref_t _LIBCPP_NODEBUG = __remove_cv_t<__libcpp_remove_reference_t<_Tp> >;
+using __remove_cvref_t _LIBCPP_NODEBUG = __remove_cvref(_Tp);
#endif // __has_builtin(__remove_cvref)
template <class _Tp, class _Up>
-struct __is_same_uncvref : _IsSame<__remove_cvref_t<_Tp>, __remove_cvref_t<_Up> > {};
+using __is_same_uncvref = _IsSame<__remove_cvref_t<_Tp>, __remove_cvref_t<_Up> >;
#if _LIBCPP_STD_VER >= 20
template <class _Tp>
struct remove_cvref {
- using type _LIBCPP_NODEBUG = __remove_cvref_t<_Tp>;
+ using type _LIBCPP_NODEBUG = __remove_cvref(_Tp);
};
template <class _Tp>
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Feb 29, 2024
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…e_cvref (llvm#81386)" This reverts commit 5535716. This is only being reverted from the LLVM 19 branch as a convenience to avoid breaking some IDEs which were not ready for that change. Fixes llvm#99464
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…e_cvref (llvm#81386)" This reverts commit 5535716. This is only being reverted from the LLVM 19 branch as a convenience to avoid breaking some IDEs which were not ready for that change. Fixes llvm#99464
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GCC 15 has added builtins for various C++ type traits that Clang already had. Since __has_builtin(...) now finds these, the #if branches previously only used for Clang are now used for GCC 15. However, GCC 15 requires that these builtins only be used in type aliases, not in template aliases. These changes follow the model of llvm#81386 where a previous GCC version added builtins for __remove_cv and __remove_cvref. Fixed: llvm#137704 Fixed: llvm#117319
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They have been added recently to GCC without support for mangling. This patch uses them in structs and adds aliases to these structs instead of the builtins directly.