Revert "Revert "Merge to upstream r304942.""

This reverts commit 38a0d5af7e.

Test: make checkbuild
Test: ./run_tests.py
Test: ./run_tests.py --bitness 64

test/std/utilities/smartptr/unique.ptr/unique.ptr.special/swap.pass.cpp

@@ -0,0 +1,102 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// <memory>
+
+// unique_ptr
+
+// Test swap
+
+#include <memory>
+#include <cassert>
+
+#include "test_macros.h"
+#include "deleter_types.h"
+
+struct A
+{
+    int state_;
+    static int count;
+    A() : state_(0) {++count;}
+    explicit A(int i) : state_(i) {++count;}
+    A(const A& a) : state_(a.state_) {++count;}
+    A& operator=(const A& a) {state_ = a.state_; return *this;}
+    ~A() {--count;}
+
+    friend bool operator==(const A& x, const A& y)
+        {return x.state_ == y.state_;}
+};
+
+int A::count = 0;
+
+template <class T>
+struct NonSwappableDeleter {
+  explicit NonSwappableDeleter(int) {}
+  NonSwappableDeleter& operator=(NonSwappableDeleter const&) { return *this; }
+  void operator()(T*) const {}
+private:
+  NonSwappableDeleter(NonSwappableDeleter const&);
+
+};
+
+int main()
+{
+    {
+    A* p1 = new A(1);
+    std::unique_ptr<A, Deleter<A> > s1(p1, Deleter<A>(1));
+    A* p2 = new A(2);
+    std::unique_ptr<A, Deleter<A> > s2(p2, Deleter<A>(2));
+    assert(s1.get() == p1);
+    assert(*s1 == A(1));
+    assert(s1.get_deleter().state() == 1);
+    assert(s2.get() == p2);
+    assert(*s2 == A(2));
+    assert(s2.get_deleter().state() == 2);
+    swap(s1, s2);
+    assert(s1.get() == p2);
+    assert(*s1 == A(2));
+    assert(s1.get_deleter().state() == 2);
+    assert(s2.get() == p1);
+    assert(*s2 == A(1));
+    assert(s2.get_deleter().state() == 1);
+    assert(A::count == 2);
+    }
+    assert(A::count == 0);
+    {
+    A* p1 = new A[3];
+    std::unique_ptr<A[], Deleter<A[]> > s1(p1, Deleter<A[]>(1));
+    A* p2 = new A[3];
+    std::unique_ptr<A[], Deleter<A[]> > s2(p2, Deleter<A[]>(2));
+    assert(s1.get() == p1);
+    assert(s1.get_deleter().state() == 1);
+    assert(s2.get() == p2);
+    assert(s2.get_deleter().state() == 2);
+    swap(s1, s2);
+    assert(s1.get() == p2);
+    assert(s1.get_deleter().state() == 2);
+    assert(s2.get() == p1);
+    assert(s2.get_deleter().state() == 1);
+    assert(A::count == 6);
+    }
+    assert(A::count == 0);
+#if TEST_STD_VER >= 11
+    {
+        // test that unique_ptr's specialized swap is disabled when the deleter
+        // is non-swappable. Instead we should pick up the generic swap(T, T)
+        // and perform 3 move constructions.
+        typedef NonSwappableDeleter<int> D;
+        D  d(42);
+        int x = 42;
+        int y = 43;
+        std::unique_ptr<int, D&> p(&x, d);
+        std::unique_ptr<int, D&> p2(&y, d);
+        std::swap(p, p2);
+    }
+#endif
+}