PVS-Studio warning V554 for Boost

static std::basic_string<wchar_t> get(char const* source = "")
{
  ....
  std::auto_ptr<wchar_t> result (new wchar_t[len+1]);
  ....
}

This suspicious code was found in Boost project by PVS-Studio static code analyzer.
Warning message is:
V554 Incorrect use of auto_ptr. The memory allocated with 'new []' will be cleaned using 'delete'. tree_to_xml.ipp 71

PVS-Studio is a static analyzer for detecting bugs in the source code of applications written in C, C++, C++11, C++/CX. Site: http://www.viva64.com/en/pvs-studio/