PVS-Studio warning V524 for TPP

CharIndexedVectorIterator operator++(int)
{  // postincrement
  CharIndexedVectorIterator _Tmp = *this;
  ++m_itr;
  return (_Tmp);
}

CharIndexedVectorIterator& operator--()
{  // predecrement
  ++m_itr;
  return (*this);
}

This suspicious code was found in TPP project by PVS-Studio static code analyzer.
Warning message is:
V524 It is odd that the body of '--' function is fully equivalent to the body of '++' function. charindexedvector.hpp 81

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/