Implement LWG 2221 - No formatted output operator for nullptr. Reviewed as https://reviews.llvm.org/D44263

llvm-svn: 342566

libcxx/include/ostream

@@ -56,6 +56,7 @@ public:
     basic_ostream& operator<<(double f);
     basic_ostream& operator<<(long double f);
     basic_ostream& operator<<(const void* p);
+    basic_ostream<charT, traits>& operator<<(nullptr_t);   // C++17
     basic_ostream& operator<<(basic_streambuf<char_type,traits>* sb);
 
     // 27.7.2.7 Unformatted output:
@@ -216,6 +217,7 @@ public:
     basic_ostream& operator<<(double __f);
     basic_ostream& operator<<(long double __f);
     basic_ostream& operator<<(const void* __p);
+    basic_ostream& operator<<(nullptr_t);
     basic_ostream& operator<<(basic_streambuf<char_type, traits_type>* __sb);
 
     // 27.7.2.7 Unformatted output:
@@ -709,6 +711,14 @@ basic_ostream<_CharT, _Traits>::operator<<(const void* __n)
     return *this;
 }
 
+template <class _CharT, class _Traits>
+basic_ostream<_CharT, _Traits>&
+basic_ostream<_CharT, _Traits>::operator<<(nullptr_t)
+{
+	return *this << "(nullptr)";
+}
+
+
 template<class _CharT, class _Traits>
 basic_ostream<_CharT, _Traits>&
 __put_character_sequence(basic_ostream<_CharT, _Traits>& __os,
@@ -742,7 +752,6 @@ __put_character_sequence(basic_ostream<_CharT, _Traits>& __os,
     return __os;
 }
 
-
 template<class _CharT, class _Traits>
 basic_ostream<_CharT, _Traits>&
 operator<<(basic_ostream<_CharT, _Traits>& __os, _CharT __c)

libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters/nullptr.pass.cpp

@@ -0,0 +1,80 @@
+//===----------------------------------------------------------------------===//
+//
+//                     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.
+//
+//===----------------------------------------------------------------------===//
+
+// <ostream>
+
+// template <class charT, class traits = char_traits<charT> >
+//   class basic_ostream;
+
+// template<class charT, class traits>
+//   basic_ostream<charT,traits>& operator<<(basic_ostream<charT,traits>& out, nullptr_t);
+//
+
+#include <ostream>
+#include <cassert>
+#include "test_macros.h"
+
+template <class CharT>
+class testbuf
+    : public std::basic_streambuf<CharT>
+{
+    typedef std::basic_streambuf<CharT> base;
+    std::basic_string<CharT> str_;
+public:
+    testbuf()
+    {
+    }
+
+    std::basic_string<CharT> str() const
+        {return std::basic_string<CharT>(base::pbase(), base::pptr());}
+
+protected:
+
+    virtual typename base::int_type
+        overflow(typename base::int_type ch = base::traits_type::eof())
+        {
+            if (ch != base::traits_type::eof())
+            {
+                int n = static_cast<int>(str_.size());
+                str_.push_back(ch);
+                str_.resize(str_.capacity());
+                base::setp(const_cast<CharT*>(str_.data()),
+                           const_cast<CharT*>(str_.data() + str_.size()));
+                base::pbump(n+1);
+            }
+            return ch;
+        }
+};
+
+int main()
+{
+    {
+        std::wostream os((std::wstreambuf*)0);
+        os << nullptr;
+        assert(os.bad());
+        assert(os.fail());
+    }
+    {
+        testbuf<char> sb;
+        std::ostream os(&sb);
+        assert(sb.str().length() == 0);
+        os << nullptr;
+        assert(sb.str().length() > 0);
+        LIBCPP_ASSERT(sb.str() == "(nullptr)");  // output is an implementation-defined NTCTS
+    }
+
+    {
+        testbuf<wchar_t> sb;
+        std::wostream os(&sb);
+        assert(sb.str().length() == 0);
+        os << nullptr;
+        assert(sb.str().length() > 0);
+        LIBCPP_ASSERT(sb.str() == L"(nullptr)");  // output is an implementation-defined NTCTS
+    }
+}

libcxx/www/cxx1z_status.html

@@ -365,7 +365,7 @@
  	<tr><td></td><td></td><td></td><td></td></tr>
 	<tr><td><a href="https://wg21.link/LWG2062">2062</a></td><td>Effect contradictions w/o no-throw guarantee of std::function swaps</td><td>Issaquah</td><td>Complete</td></tr>
 	<tr><td><a href="https://wg21.link/LWG2166">2166</a></td><td>Heap property underspecified?</td><td>Issaquah</td><td></td></tr>
-	<tr><td><a href="https://wg21.link/LWG2221">2221</a></td><td>No formatted output operator for nullptr</td><td>Issaquah</td><td></td></tr>
+	<tr><td><a href="https://wg21.link/LWG2221">2221</a></td><td>No formatted output operator for nullptr</td><td>Issaquah</td><td>Complete</td></tr>
 	<tr><td><a href="https://wg21.link/LWG2223">2223</a></td><td>shrink_to_fit effect on iterator validity</td><td>Issaquah</td><td>Complete</td></tr>
 	<tr><td><a href="https://wg21.link/LWG2261">2261</a></td><td>Are containers required to use their 'pointer' type internally?</td><td>Issaquah</td><td></td></tr>
 	<tr><td><a href="https://wg21.link/LWG2394">2394</a></td><td>locale::name specification unclear - what is implementation-defined?</td><td>Issaquah</td><td>Complete</td></tr>
@@ -504,7 +504,7 @@
 <!-- 	<tr><td></td><td></td><td></td><td></td></tr> -->
   </table>
 
-  <p>Last Updated: 3-Aug-2018</p>
+  <p>Last Updated: 19-Sep-2018</p>
 </div>
 </body>
 </html>