[libc++] [C++2b] [P1682] Add to_underlying.
* https://wg21.link/P1682
Reviewed By: ldionne, Mordante, #libc
Differential Revision: https://reviews.llvm.org/D97365
GitOrigin-RevId: 43e421417378bab378eccdf88a66a0a46304fa13
diff --git a/include/utility b/include/utility
index 6f27af7..ca3d3fe 100644
--- a/include/utility
+++ b/include/utility
@@ -191,6 +191,10 @@
template <size_t I>
inline constexpr in_place_index_t<I> in_place_index{};
+// [utility.underlying], to_underlying
+template <class T>
+ constexpr underlying_type_t<T> to_underlying( T value ) noexcept; // C++2b
+
} // std
*/
@@ -1622,8 +1626,21 @@
using __enable_hash_helper _LIBCPP_NODEBUG_TYPE = _Type;
#endif
+template <class _Tp>
+_LIBCPP_INLINE_VISIBILITY constexpr typename underlying_type<_Tp>::type
+__to_underlying(_Tp __val) noexcept {
+ return static_cast<typename underlying_type<_Tp>::type>(__val);
+}
#endif // !_LIBCPP_CXX03_LANG
+#if _LIBCPP_STD_VER > 20
+template <class _Tp>
+_LIBCPP_INLINE_VISIBILITY constexpr underlying_type_t<_Tp>
+to_underlying(_Tp __val) noexcept {
+ return _VSTD::__to_underlying(__val);
+}
+#endif
+
_LIBCPP_END_NAMESPACE_STD
#endif // _LIBCPP_UTILITY
diff --git a/include/version b/include/version
index 49648a0..becbfa5 100644
--- a/include/version
+++ b/include/version
@@ -150,6 +150,7 @@
__cpp_lib_to_address 201711L <memory>
__cpp_lib_to_array 201907L <array>
__cpp_lib_to_chars 201611L <utility>
+__cpp_lib_to_underlying 202102L <utility>
__cpp_lib_transformation_trait_aliases 201304L <type_traits>
__cpp_lib_transparent_operators 201510L <functional> <memory>
201210L // C++14
@@ -365,6 +366,7 @@
// # define __cpp_lib_stacktrace 202011L
// # define __cpp_lib_stdatomic_h 202011L
# define __cpp_lib_string_contains 202011L
+# define __cpp_lib_to_underlying 202102L
#endif
// clang-format on