Implement the first part of N4258 - allocator_traits<X>::is_always_equal. Also fixes PR#23723
llvm-svn: 238848
Cr-Mirrored-From: sso://chromium.googlesource.com/_direct/external/github.com/llvm/llvm-project
Cr-Mirrored-Commit: 31a473137096b979e5cd297848d46ce72bd924be
diff --git a/include/memory b/include/memory
index 4e3a6f8..dc5902d 100644
--- a/include/memory
+++ b/include/memory
@@ -75,6 +75,8 @@
| false_type propagate_on_container_move_assignment;
typedef Alloc::propagate_on_container_swap
| false_type propagate_on_container_swap;
+ typedef Alloc::is_always_equal
+ | is_empty is_always_equal;
template <class T> using rebind_alloc = Alloc::rebind<U>::other | Alloc<T, Args...>;
template <class T> using rebind_traits = allocator_traits<rebind_alloc<T>>;
@@ -1144,6 +1146,29 @@
typedef typename _Alloc::propagate_on_container_swap type;
};
+template <class _Tp>
+struct __has_is_always_equal
+{
+private:
+ struct __two {char __lx; char __lxx;};
+ template <class _Up> static __two __test(...);
+ template <class _Up> static char __test(typename _Up::is_always_equal* = 0);
+public:
+ static const bool value = sizeof(__test<_Tp>(0)) == 1;
+};
+
+template <class _Alloc, bool = __has_is_always_equal<_Alloc>::value>
+struct __is_always_equal
+{
+ typedef typename _VSTD::is_empty<_Alloc>::type type;
+};
+
+template <class _Alloc>
+struct __is_always_equal<_Alloc, true>
+{
+ typedef typename _Alloc::is_always_equal type;
+};
+
template <class _Tp, class _Up, bool = __has_rebind<_Tp, _Up>::value>
struct __has_rebind_other
{
@@ -1423,6 +1448,8 @@
propagate_on_container_move_assignment;
typedef typename __propagate_on_container_swap<allocator_type>::type
propagate_on_container_swap;
+ typedef typename __is_always_equal<allocator_type>::type
+ is_always_equal;
#ifndef _LIBCPP_HAS_NO_TEMPLATE_ALIASES
template <class _Tp> using rebind_alloc =
@@ -1667,6 +1694,7 @@
typedef _Tp value_type;
typedef true_type propagate_on_container_move_assignment;
+ typedef true_type is_always_equal;
template <class _Up> struct rebind {typedef allocator<_Up> other;};