Merge branch 'master' into master

2 files changed, 26 insertions, 9 deletions

diff --git a/absl/memory/memory.h b/absl/memory/memory.h
index c6799608..15cd85f4 100644
--- a/absl/memory/memory.h
+++ b/absl/memory/memory.h
@@ -38,8 +38,8 @@ namespace absl {
 // Function Template: WrapUnique()
 // -----------------------------------------------------------------------------
 //
-// Transfers ownership of a raw pointer to a `std::unique_ptr`. The returned
-// value is a `std::unique_ptr` of deduced type.
+//  Adopts ownership from a raw pointer and transfers it to the returned
+//  `std::unique_ptr`, whose type is deduced.
 //
 // Example:
 //   X* NewX(int, int);
@@ -81,6 +81,9 @@ struct MakeUniqueResult<T[N]> {
 
 }  // namespace memory_internal
 
+#if __cplusplus >= 201402L || defined(_MSC_VER)
+using std::make_unique;
+#else
 // -----------------------------------------------------------------------------
 // Function Template: make_unique<T>()
 // -----------------------------------------------------------------------------
@@ -164,13 +167,14 @@ typename memory_internal::MakeUniqueResult<T>::array make_unique(size_t n) {
 template <typename T, typename... Args>
 typename memory_internal::MakeUniqueResult<T>::invalid make_unique(
     Args&&... /* args */) = delete;
+#endif
 
 // -----------------------------------------------------------------------------
 // Function Template: RawPtr()
 // -----------------------------------------------------------------------------
 //
-// Extracts the raw pointer from a pointer-like 'ptr'. `absl::RawPtr` is useful
-// within templates that need to handle a complement of raw pointers,
+// Extracts the raw pointer from a pointer-like value `ptr`. `absl::RawPtr` is
+// useful within templates that need to handle a complement of raw pointers,
 // `std::nullptr_t`, and smart pointers.
 template <typename T>
 auto RawPtr(T&& ptr) -> decltype(&*ptr) {
@@ -183,9 +187,9 @@ inline std::nullptr_t RawPtr(std::nullptr_t) { return nullptr; }
 // Function Template: ShareUniquePtr()
 // -----------------------------------------------------------------------------
 //
-// Transforms a `std::unique_ptr` rvalue into a `std::shared_ptr`. The returned
-// value is a `std::shared_ptr` of deduced type and ownership is transferred to
-// the shared pointer.
+// Adopts a `std::unique_ptr` rvalue and returns a `std::shared_ptr` of deduced
+// type. Ownership (if any) of the held value is transferred to the returned
+// shared pointer.
 //
 // Example:
 //
@@ -194,8 +198,11 @@ inline std::nullptr_t RawPtr(std::nullptr_t) { return nullptr; }
 //     CHECK_EQ(*sp, 10);
 //     CHECK(up == nullptr);
 //
-// Note that this conversion is correct even when T is an array type, although
-// the resulting shared pointer may not be very useful.
+// Note that this conversion is correct even when T is an array type, and more
+// generally it works for *any* deleter of the `unique_ptr` (single-object
+// deleter, array deleter, or any custom deleter), since the deleter is adopted
+// by the shared pointer as well. The deleter is copied (unless it is a
+// reference).
 //
 // Implements the resolution of [LWG 2415](http://wg21.link/lwg2415), by which a
 // null shared pointer does not attempt to call the deleter.
diff --git a/absl/memory/memory_test.cc b/absl/memory/memory_test.cc
index 8a5f5522..7d047ca0 100644
--- a/absl/memory/memory_test.cc
+++ b/absl/memory/memory_test.cc
@@ -138,6 +138,16 @@ TEST(Make_UniqueTest, Array) {
   EXPECT_THAT(ArrayWatch::allocs(), ElementsAre(5 * sizeof(ArrayWatch)));
 }
 
+TEST(Make_UniqueTest, NotAmbiguousWithStdMakeUnique) {
+  // Ensure that absl::make_unique is not ambiguous with std::make_unique.
+  // In C++14 mode, the below call to make_unique has both types as candidates.
+  struct TakesStdType {
+    explicit TakesStdType(const std::vector<int> &vec) {}
+  };
+  using absl::make_unique;
+  make_unique<TakesStdType>(std::vector<int>());
+}
+
 #if 0
 // TODO(billydonahue): Make a proper NC test.
 // These tests shouldn't compile.