[libc++] Fix PR34898 - vector iterator constructors and assign method perform push_back instead of emplace_back.

Summary:
The constructors `vector(Iter, Iter, Alloc = Alloc{})` and `assign(Iter, Iter)` don't correctly perform EmplaceConstruction from the result of dereferencing the iterator. This results in them performing an additional and unneeded copy.

This patch addresses the issue by correctly using `emplace_back` in C++11 and newer.

There are also some bugs in our `insert` implementation, but those will be handled separately. 

@mclow.lists We should probably merge this into 5.1, agreed?

Reviewers: mclow.lists, dlj, EricWF

Reviewed By: mclow.lists, EricWF

Subscribers: cfe-commits, mclow.lists

Differential Revision: https://reviews.llvm.org/D38757

llvm-svn: 315994

2 files changed, 100 insertions, 2 deletions

diff --git a/libcxx/test/support/container_test_types.h b/libcxx/test/support/container_test_types.h
index 08e88f09146..b8422ec4602 100644
--- a/libcxx/test/support/container_test_types.h
+++ b/libcxx/test/support/container_test_types.h
@@ -234,6 +234,19 @@ inline ConstructController* getConstructController() {
   return &c;
 }
 
+template <class ...Args>
+struct ExpectConstructGuard {
+  ExpectConstructGuard(int N)  {
+    auto CC = getConstructController();
+    assert(!CC->unchecked());
+    CC->expect<Args...>(N);
+  }
+
+  ~ExpectConstructGuard() {
+    assert(!getConstructController()->unchecked());
+  }
+};
+
 //===----------------------------------------------------------------------===//
 //                       ContainerTestAllocator
 //===----------------------------------------------------------------------===//
@@ -417,7 +430,12 @@ namespace std {
       return arg.data;
     }
   };
-
+  template <class T, class Alloc>
+  class vector;
+  template <class T, class Alloc>
+  class deque;
+  template <class T, class Alloc>
+  class list;
   template <class _Key, class _Value, class _Less, class _Alloc>
   class map;
   template <class _Key, class _Value, class _Less, class _Alloc>
@@ -444,6 +462,13 @@ _LIBCPP_END_NAMESPACE_STD
 // TCT - Test container type
 namespace TCT {
 
+template <class T = CopyInsertable<1>>
+using vector = std::vector<T, ContainerTestAllocator<T, T> >;
+template <class T = CopyInsertable<1>>
+using deque = std::deque<T, ContainerTestAllocator<T, T> >;
+template <class T = CopyInsertable<1>>
+using list = std::list<T, ContainerTestAllocator<T, T> >;
+
 template <class Key = CopyInsertable<1>, class Value = CopyInsertable<2>,
           class ValueTp = std::pair<const Key, Value> >
 using unordered_map =
@@ -488,5 +513,4 @@ using multiset =
 
 } // end namespace TCT
 
-
 #endif // SUPPORT_CONTAINER_TEST_TYPES_H
diff --git a/libcxx/test/support/emplace_constructible.h b/libcxx/test/support/emplace_constructible.h
new file mode 100644
index 00000000000..f2bc0ec6a36
--- /dev/null
+++ b/libcxx/test/support/emplace_constructible.h
@@ -0,0 +1,74 @@
+#ifndef TEST_SUPPORT_EMPLACE_CONSTRUCTIBLE_H
+#define TEST_SUPPORT_EMPLACE_CONSTRUCTIBLE_H
+
+#include "test_macros.h"
+
+#if TEST_STD_VER >= 11
+template <class T>
+struct EmplaceConstructible {
+  T value;
+  explicit EmplaceConstructible(T value) : value(value) {}
+  EmplaceConstructible(EmplaceConstructible const&) = delete;
+};
+
+template <class T>
+struct EmplaceConstructibleAndMoveInsertable {
+  int copied = 0;
+  T value;
+  explicit EmplaceConstructibleAndMoveInsertable(T value) : value(value) {}
+
+  EmplaceConstructibleAndMoveInsertable(
+      EmplaceConstructibleAndMoveInsertable&& Other)
+      : copied(Other.copied + 1), value(std::move(Other.value)) {}
+};
+
+template <class T>
+struct EmplaceConstructibleAndMoveable {
+  int copied = 0;
+  int assigned = 0;
+  T value;
+  explicit EmplaceConstructibleAndMoveable(T value) noexcept : value(value) {}
+
+  EmplaceConstructibleAndMoveable(EmplaceConstructibleAndMoveable&& Other)
+      noexcept : copied(Other.copied + 1),
+                 value(std::move(Other.value)) {}
+
+  EmplaceConstructibleAndMoveable&
+  operator=(EmplaceConstructibleAndMoveable&& Other) noexcept {
+    copied = Other.copied;
+    assigned = Other.assigned + 1;
+    value = std::move(Other.value);
+    return *this;
+  }
+};
+
+template <class T>
+struct EmplaceConstructibleMoveableAndAssignable {
+  int copied = 0;
+  int assigned = 0;
+  T value;
+  explicit EmplaceConstructibleMoveableAndAssignable(T value) noexcept
+      : value(value) {}
+
+  EmplaceConstructibleMoveableAndAssignable(
+      EmplaceConstructibleMoveableAndAssignable&& Other) noexcept
+      : copied(Other.copied + 1),
+        value(std::move(Other.value)) {}
+
+  EmplaceConstructibleMoveableAndAssignable&
+  operator=(EmplaceConstructibleMoveableAndAssignable&& Other) noexcept {
+    copied = Other.copied;
+    assigned = Other.assigned + 1;
+    value = std::move(Other.value);
+    return *this;
+  }
+
+  EmplaceConstructibleMoveableAndAssignable& operator=(T xvalue) {
+    value = std::move(xvalue);
+    ++assigned;
+    return *this;
+  }
+};
+#endif
+
+#endif // TEST_SUPPORT_EMPLACE_CONSTRUCTIBLE_H