[libcxx] Implement http://wg21.link/p1006, constexpr in pointer_traits
Summary:
P1006 adds support for constexpr in the specialization of pointer_traits
for raw pointers. This is necessary in order to use pointer_traits in
the upcoming constexpr containers. We expect P1006 to be voted into the
working draft for C++20 at the San Diego meeting.
Reviewers: mclow.lists, EricWF
Subscribers: christof, dexonsmith, libcxx-commits
Differential Revision: https://reviews.llvm.org/D53867
llvm-svn: 346764
Cr-Mirrored-From: sso://chromium.googlesource.com/_direct/external/github.com/llvm/llvm-project
Cr-Mirrored-Commit: 727202699335fcba44e8c90ce29b6cab5e1b61fb
diff --git a/include/memory b/include/memory
index 783d94c..9fca9fe 100644
--- a/include/memory
+++ b/include/memory
@@ -43,7 +43,7 @@
template <class U> using rebind = U*;
- static pointer pointer_to(<details>) noexcept;
+ static pointer pointer_to(<details>) noexcept; // constexpr in C++20
};
template <class T> constexpr T* to_address(T* p) noexcept; // C++20
@@ -984,7 +984,7 @@
private:
struct __nat {};
public:
- _LIBCPP_INLINE_VISIBILITY
+ _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
static pointer pointer_to(typename conditional<is_void<element_type>::value,
__nat, element_type>::type& __r) _NOEXCEPT
{return _VSTD::addressof(__r);}
diff --git a/test/std/utilities/memory/pointer.traits/pointer_to.pass.cpp b/test/std/utilities/memory/pointer.traits/pointer_to.pass.cpp
index b3f3c24..756f894 100644
--- a/test/std/utilities/memory/pointer.traits/pointer_to.pass.cpp
+++ b/test/std/utilities/memory/pointer.traits/pointer_to.pass.cpp
@@ -12,15 +12,18 @@
// template <class T>
// struct pointer_traits<T*>
// {
-// static pointer pointer_to(<details>);
+// static pointer pointer_to(<details>); // constexpr in C++20
// ...
// };
#include <memory>
#include <cassert>
+#include "test_macros.h"
-int main()
-{
+#if TEST_STD_VER > 17
+constexpr
+#endif
+bool check() {
{
int i = 0;
static_assert((std::is_same<int *, decltype(std::pointer_traits<int*>::pointer_to(i))>::value), "");
@@ -30,4 +33,12 @@
{
(std::pointer_traits<void*>::element_type)0;
}
+ return true;
+}
+
+int main() {
+ check();
+#if TEST_STD_VER > 17
+ static_assert(check(), "");
+#endif
}