std::map as a default arg to a member function/constructor

[szymonwlodarski]

I have encountered a bug (I think). When I compile this (g++ 4.2.3):



  #include <map>

  struct A
  {
    std::map< int, int > m;

    A( std::map< int, int > m1 = std::map< int, int >())
    : m( m1 )
    {
    }
  };



  int

  main()

  {

  }



I get:

../main.cpp:14: error: expected ‘,’ or ‘...’ before ‘>’ token
../main.cpp:14: error: wrong number of template arguments (1, should
be 4)
/usr/include/c++/4.2/bits/stl_map.h:93: error: provided for
‘template<class _Key, class _Tp, class _Compare, class _Alloc> class
std::map’
../main.cpp:14: error: default argument missing for parameter 2 of
‘B::B(std::map<int, int, std::less<int>,
std::allocator<std::pair<const int, int> > >, int)’



It works with VC++, Comeau Online does not complain either.

If I change A to:

  struct A
  {
    typedef std::map< int, int > T;
    T m;

    A( T m1 = T())
    : m( m1 )
    {
    }
  };
Now it works fine.

There is no problem with non-member functions.

  void
  fun( std::map< int, int > m1 = std::map< int, int >())
  {
  }

OK.

--
Szymon