Modernize relational operators for shared_ptr and unique_ptr. This includes adding support for nullptr, and using less<T*>. Fixes http://llvm.org/bugs/show_bug.cgi?id=12056.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@151084 91177308-0d34-0410-b5e6-96231b3b80d8

test/utilities/memory/util.smartptr/util.smartptr.shared/util.smartptr.shared.cmp/cmp_nullptr.pass.cpp

@@ -0,0 +1,71 @@
+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// shared_ptr
+
+// template <class T>
+//     bool operator==(const shared_ptr<T>& x, nullptr_t) noexcept;
+// template <class T>
+//     bool operator==(nullptr_t, const shared_ptr<T>& y) noexcept;
+// template <class T>
+//     bool operator!=(const shared_ptr<T>& x, nullptr_t) noexcept;
+// template <class T>
+//     bool operator!=(nullptr_t, const shared_ptr<T>& y) noexcept;
+// template <class T>
+//     bool operator<(const shared_ptr<T>& x, nullptr_t) noexcept;
+// template <class T>
+//     bool operator<(nullptr_t, const shared_ptr<T>& y) noexcept;
+// template <class T>
+//     bool operator<=(const shared_ptr<T>& x, nullptr_t) noexcept;
+// template <class T>
+//     bool operator<=(nullptr_t, const shared_ptr<T>& y) noexcept;
+// template <class T>
+//     bool operator>(const shared_ptr<T>& x, nullptr_t) noexcept;
+// template <class T>
+//     bool operator>(nullptr_t, const shared_ptr<T>& y) noexcept;
+// template <class T>
+//     bool operator>=(const shared_ptr<T>& x, nullptr_t) noexcept;
+// template <class T>
+//     bool operator>=(nullptr_t, const shared_ptr<T>& y) noexcept;
+
+#include <memory>
+#include <cassert>
+
+void do_nothing(int*) {}
+
+int main()
+{
+    int* ptr1(new int);
+    int* ptr2(new int);
+    const std::shared_ptr<int> p1(new int(1));
+    assert(!(p1 == nullptr));
+    assert(!(nullptr == p1));
+    assert(!(p1 < nullptr));
+    assert( (nullptr < p1));
+    assert(!(p1 <= nullptr));
+    assert( (nullptr <= p1));
+    assert( (p1 > nullptr));
+    assert(!(nullptr > p1));
+    assert( (p1 >= nullptr));
+    assert(!(nullptr >= p1));
+
+    const std::shared_ptr<int> p2;
+    assert( (p2 == nullptr));
+    assert( (nullptr == p2));
+    assert(!(p2 < nullptr));
+    assert(!(nullptr < p2));
+    assert( (p2 <= nullptr));
+    assert( (nullptr <= p2));
+    assert(!(p2 > nullptr));
+    assert(!(nullptr > p2));
+    assert( (p2 >= nullptr));
+    assert( (nullptr >= p2));
+}