syntax4.c

this is a gcc file, you can download it and learn its usetility, for further detail please look at t

// Build don't link:

// Copyright (C) 2000 Free Software Foundation, Inc.
// Contributed by Nathan Sidwell 22 June 2000 <[e-mail]>

// Origin GNATS bug report 262 from Jeremy Sanders <[e-mail]>
// and several others. With templates, it's very easy to say something
// erroneous like
//    template class X::X<whatever>
// The culprit
//    ... class X::X ...
// caused us to ICE as we got confused about pushing and popping scopes.

class X {
  X ();
};

class Y {
  public:
  typedef ::X W;
  class Z;
};

class Y::Z {};
class Y::W  () {}  // ERROR - parse error
Y::W::X () {}