Implement LWG 2221 - No formatted output operator for nullptr

[mclow.lists]

Summary

https://cplusplus.github.io/LWG/issue2221

This is straightforward; I'm putting it up for review because it will add symbols to the dylib

[dexonsmith]

LGTM.

[mclow.lists]

Landed as revision 342566

[mclow.lists]

Reverted in r342590 while I investigate additions to the dylib.

[mclow.lists]

Symbol added: _ZNSt3__113basic_ostreamIcNS_11char_traitsIcEEElsEDn

{'is_defined': True, 'type': 'FUNC', 'name': '_ZNSt3__113basic_ostreamIcNS_11char_traitsIcEEElsEDn'}

Symbol added: _ZNSt3__113basic_ostreamIwNS_11char_traitsIwEEElsEDn

{'is_defined': True, 'type': 'FUNC', 'name': '_ZNSt3__113basic_ostreamIwNS_11char_traitsIwEEElsEDn'}

Symbol added: _ZNSt3__1lsIwNS_11char_traitsIwEEEERNS_13basic_ostreamIT_T0_EES7_PKc

{'is_defined': True, 'type': 'FUNC', 'name': '_ZNSt3__1lsIwNS_11char_traitsIwEEEERNS_13basic_ostreamIT_T0_EES7_PKc'}

Symbol added: _ZNSt3124put_character_sequenceIcNS_11char_traitsIcEEEERNS_13basic_ostreamIT_T0_EES7_PKS4_m

{'is_defined': True, 'type': 'FUNC', 'name': '_ZNSt3__124__put_character_sequenceIcNS_11char_traitsIcEEEERNS_13basic_ostreamIT_T0_EES7_PKS4_m'}

[vsapsai]

Seems like revert didn't go through. I suspect it is causing build failure in http://green.lab.llvm.org/green/job/clang-stage1-configure-RA/49593/consoleText

SANITIZER_TEST_OBJECTS.sanitizer_vector_test.cc.i386.o SANITIZER_TEST_OBJECTS.gtest-all.cc.i386.o /Users/buildslave/jenkins/workspace/clang-stage1-configure-RA/clang-build/tools/clang/runtime/compiler-rt-bins/lib/sanitizer_common/tests/libRTSanitizerCommon.test.osx.a -o /Users/buildslave/jenkins/workspace/clang-stage1-configure-RA/clang-build/tools/clang/runtime/compiler-rt-bins/lib/sanitizer_common/tests/./Sanitizer-i386-Test -g --driver-mode=g++ -stdlib=libc++ -lc++ -lc++abi -fapplication-extension -mmacosx-version-min=10.9 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.13.sdk -Wl,-U,___sanitizer_free_hook -Wl,-U,___sanitizer_malloc_hook -Wl,-U,___sanitizer_report_error_summary -Wl,-U,___sanitizer_sandbox_on_notify -Wl,-U,___sanitizer_symbolize_code -Wl,-U,___sanitizer_symbolize_data -Wl,-U,___sanitizer_symbolize_demangle -Wl,-U,___sanitizer_symbolize_flush -ldl -pthread -arch i386
Undefined symbols for architecture i386:
  "std::__1::basic_ostream<char, std::__1::char_traits<char> >::operator<<(std::nullptr_t)", referenced from:
      std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > testing::PrintToString<std::nullptr_t>(std::nullptr_t const&) in SANITIZER_TEST_OBJECTS.sanitizer_quarantine_test.cc.i386.o
      std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > testing::PrintToString<std::nullptr_t>(std::nullptr_t const&) in SANITIZER_TEST_OBJECTS.sanitizer_stacktrace_printer_test.cc.i386.o
ld: symbol(s) not found for architecture i386
clang-8: error: linker command failed with exit code 1 (use -v to see invocation)

[vsapsai]

Reverted in r342599.

[davide]

This broke all the lldb bots as well, FWIW.

include/ostream

     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:

     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:

     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,

     return __os;
 }
 
-
 template<class _CharT, class _Traits>
 basic_ostream<_CharT, _Traits>&
 operator<<(basic_ostream<_CharT, _Traits>& __os, _CharT __c)

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

+//===----------------------------------------------------------------------===//
+//
+//                     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
+    }
+}