[libcxx] Implement std::to_address for C++20
Summary: Now implements P0653R2 - Utility to convert to raw pointer.
Reviewers: mclow.lists, EricWF
Reviewed By: EricWF
Subscribers: cfe-commits
Differential Revision: https://reviews.llvm.org/D35470
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@318865 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/memory b/include/memory
index 888ce69..913bc85 100644
--- a/include/memory
+++ b/include/memory
@@ -46,6 +46,9 @@
static pointer pointer_to(<details>) noexcept;
};
+template <class T> constexpr T* to_address(T* p) noexcept; // C++20
+template <class Ptr> auto to_address(const Ptr& p) noexcept; // C++20
+
template <class Alloc>
struct allocator_traits
{
@@ -1090,13 +1093,14 @@
};
template <class _Tp>
-inline _LIBCPP_INLINE_VISIBILITY
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
_Tp*
__to_raw_pointer(_Tp* __p) _NOEXCEPT
{
return __p;
}
+#if _LIBCPP_STD_VER <= 17
template <class _Pointer>
inline _LIBCPP_INLINE_VISIBILITY
typename pointer_traits<_Pointer>::element_type*
@@ -1104,6 +1108,41 @@
{
return _VSTD::__to_raw_pointer(__p.operator->());
}
+#else
+template <class _Pointer>
+inline _LIBCPP_INLINE_VISIBILITY
+auto
+__to_raw_pointer(const _Pointer& __p) _NOEXCEPT
+-> decltype(pointer_traits<_Pointer>::to_address(__p))
+{
+ return pointer_traits<_Pointer>::to_address(__p);
+}
+
+template <class _Pointer, class... _None>
+inline _LIBCPP_INLINE_VISIBILITY
+auto
+__to_raw_pointer(const _Pointer& __p, _None...) _NOEXCEPT
+{
+ return _VSTD::__to_raw_pointer(__p.operator->());
+}
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY constexpr
+_Tp*
+to_address(_Tp* __p) _NOEXCEPT
+{
+ static_assert(!is_function_v<_Tp>, "_Tp is a function type");
+ return __p;
+}
+
+template <class _Pointer>
+inline _LIBCPP_INLINE_VISIBILITY
+auto
+to_address(const _Pointer& __p) _NOEXCEPT
+{
+ return _VSTD::__to_raw_pointer(__p);
+}
+#endif
template <class _Tp, class = void>
struct __has_size_type : false_type {};
diff --git a/test/std/utilities/memory/pointer.conversion/to_address.pass.cpp b/test/std/utilities/memory/pointer.conversion/to_address.pass.cpp
new file mode 100644
index 0000000..64a5c73
--- /dev/null
+++ b/test/std/utilities/memory/pointer.conversion/to_address.pass.cpp
@@ -0,0 +1,120 @@
+//===----------------------------------------------------------------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// <memory>
+
+// UNSUPPORTED: c++98, c++03, c++11, c++14, c++17
+
+// template <class T> constexpr T* to_address(T* p) noexcept;
+// template <class Ptr> auto to_address(const Ptr& p) noexcept;
+
+#include <memory>
+#include <cassert>
+#include "test_macros.h"
+
+class P1
+{
+public:
+ using element_type = int;
+
+ explicit P1(int* p)
+ : p_(p) { }
+
+ int* operator->() const noexcept
+ { return p_; }
+
+private:
+ int* p_;
+};
+
+class P2
+{
+public:
+ using element_type = int;
+
+ explicit P2(int* p)
+ : p_(p) { }
+
+ P1 operator->() const noexcept
+ { return p_; }
+
+private:
+ P1 p_;
+};
+
+class P3
+{
+public:
+ explicit P3(int* p)
+ : p_(p) { }
+
+ int* get() const noexcept
+ { return p_; }
+
+private:
+ int* p_;
+};
+
+namespace std
+{
+template<>
+struct pointer_traits<::P3>
+{
+ static int* to_address(const ::P3& p) noexcept
+ { return p.get(); }
+};
+}
+
+class P4
+{
+public:
+ explicit P4(int* p)
+ : p_(p) { }
+
+ int* operator->() const noexcept
+ { return nullptr; }
+
+ int* get() const noexcept
+ { return p_; }
+
+private:
+ int* p_;
+};
+
+namespace std
+{
+template<>
+struct pointer_traits<::P4>
+{
+ static int* to_address(const ::P4& p) noexcept
+ { return p.get(); }
+};
+}
+
+int n = 0;
+static_assert(std::to_address(&n) == &n);
+
+int main()
+{
+ int i = 0;
+ ASSERT_NOEXCEPT(std::to_address(&i));
+ assert(std::to_address(&i) == &i);
+ P1 p1(&i);
+ ASSERT_NOEXCEPT(std::to_address(p1));
+ assert(std::to_address(p1) == &i);
+ P2 p2(&i);
+ ASSERT_NOEXCEPT(std::to_address(p2));
+ assert(std::to_address(p2) == &i);
+ P3 p3(&i);
+ ASSERT_NOEXCEPT(std::to_address(p3));
+ assert(std::to_address(p3) == &i);
+ P4 p4(&i);
+ ASSERT_NOEXCEPT(std::to_address(p4));
+ assert(std::to_address(p4) == &i);
+}
