commit f0324bcaa1ff97aabb6ba57d58d603af294d6476
author Marshall Clow <mclow.lists@gmail.com> Tue Jun 02 16:34:03 2015 +0000
committer Marshall Clow <mclow.lists@gmail.com> Tue Jun 02 16:34:03 2015 +0000
tree 3bc1dc3ca147bc670f18bae749f682754f586e73
parent 8731c5da466a217e9b1b3840625cdd5d52cbc6d5

Implement the first part of N4258 - allocator_traits<X>::is_always_equal. Also fixes PR#23723

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@238848 91177308-0d34-0410-b5e6-96231b3b80d8

include/memory

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;};
 

include/scoped_allocator

diff --git a/include/scoped_allocator b/include/scoped_allocator
index aa8bece..5864689 100644
--- a/include/scoped_allocator
+++ b/include/scoped_allocator
@@ -38,6 +38,7 @@
     typedef see below propagate_on_container_copy_assignment;
     typedef see below propagate_on_container_move_assignment;
     typedef see below propagate_on_container_swap;
+    typedef see below is_always_equal;
 
     template <class Tp>
         struct rebind
@@ -170,6 +171,14 @@
         __get_poc_swap<_Allocs...>::value;
 };
 
+template <class _A0, class ..._Allocs>
+struct __get_poc_always_equal<_A0, _Allocs...>
+{
+    static const bool value =
+        allocator_traits<_A0>::is_always_equal::value ||
+        __get_poc_always_equal<_Allocs...>::value;
+};
+
 template <class ..._Allocs>
 class __scoped_allocator_storage;
 
@@ -397,6 +406,11 @@
                 bool,
                 __get_poc_swap<outer_allocator_type, _InnerAllocs...>::value
             > propagate_on_container_swap;
+    typedef integral_constant
+            <
+                bool,
+                __get_poc_always_equal<outer_allocator_type, _InnerAllocs...>::value
+            > is_always_equal;
 
     template <class _Tp>
     struct rebind