PVS-Studio warning V530 for TortoiseSVN

CMailMsg& CMailMsg::SetTo(string sAddress,
                          string sName)
{
   if (initIfNeeded())
   {
      // only one recipient allowed
      if (m_to.size())
         m_to.empty();

      m_to.push_back(TStrStrPair(sAddress,sName));
   }
   return *this;
}

This is what should have been written here: m_to.clear();

This suspicious code was found in TortoiseSVN project by PVS-Studio static code analyzer.
Warning message is:
V530 The return value of function 'empty' is required to be utilized. mailmsg.cpp 54

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/