1 files changed, 78 insertions, 0 deletions
diff --git a/libcxx/test/support/test_allocator.h b/libcxx/test/support/test_allocator.h
index 551477119c1..466c7fabc66 100644
--- a/libcxx/test/support/test_allocator.h
+++ b/libcxx/test/support/test_allocator.h
@@ -228,4 +228,82 @@ public:
 
 };
 
+#if TEST_STD_VER >= 11
+
+struct Ctor_Tag {};
+
+template <typename T> class TaggingAllocator;
+
+struct Tag_X {
+  // All constructors must be passed the Tag type.
+
+  // DefaultInsertable into vector<X, TaggingAllocator<X>>,
+  Tag_X(Ctor_Tag) {}
+  // CopyInsertable into vector<X, TaggingAllocator<X>>,
+  Tag_X(Ctor_Tag, const Tag_X&) {}
+  // MoveInsertable into vector<X, TaggingAllocator<X>>, and
+  Tag_X(Ctor_Tag, Tag_X&&) {}
+
+  // EmplaceConstructible into vector<X, TaggingAllocator<X>> from args.
+  template<typename... Args>
+  Tag_X(Ctor_Tag, Args&&...) { }
+
+  // not DefaultConstructible, CopyConstructible or MoveConstructible.
+  Tag_X() = delete;
+  Tag_X(const Tag_X&) = delete;
+  Tag_X(Tag_X&&) = delete;
+
+  // CopyAssignable.
+  Tag_X& operator=(const Tag_X&) { return *this; }
+
+  // MoveAssignable.
+  Tag_X& operator=(Tag_X&&) { return *this; }
+
+private:
+  // Not Destructible.
+  ~Tag_X() { }
+
+  // Erasable from vector<X, TaggingAllocator<X>>.
+  friend class TaggingAllocator<Tag_X>;
+};
+
+
+template<typename T>
+class TaggingAllocator {
+public:
+    using value_type = T;
+    TaggingAllocator() = default;
+
+    template<typename U>
+      TaggingAllocator(const TaggingAllocator<U>&) { }
+
+    T* allocate(std::size_t n) { return std::allocator<T>{}.allocate(n); }
+
+    void deallocate(T* p, std::size_t n) { std::allocator<T>{}.deallocate(p, n); }
+
+    template<typename... Args>
+    void construct(Tag_X* p, Args&&... args)
+    { ::new((void*)p) Tag_X(Ctor_Tag{}, std::forward<Args>(args)...); }
+
+    template<typename U, typename... Args>
+    void construct(U* p, Args&&... args)
+    { ::new((void*)p) U(std::forward<Args>(args)...); }
+
+    template<typename U, typename... Args>
+    void destroy(U* p)
+    { p->~U(); }
+};
+
+template<typename T, typename U>
+bool
+operator==(const TaggingAllocator<T>&, const TaggingAllocator<U>&)
+{ return true; }
+
+template<typename T, typename U>
+bool
+operator!=(const TaggingAllocator<T>&, const TaggingAllocator<U>&)
+{ return false; }
+#endif
+
+
 #endif  // TEST_ALLOCATOR_H