Question

I need some help here, how is such a type mismatch even possible?
When I substitute everything in, it is exactly the same type including
constness.

cgVertex3D.cpp:33: error: no matching function for call to 
std::vector<Polygon3D*, std::allocator<Polygon3D*> >::push_back(const Polygon3D*&)

/usr/include/c++/4.4/bits/stl_vector.h:733:
note: candidates are: 

void std::vector<_Tp, _Alloc>::push_back(const _Tp&) 
[with _Tp = Polygon3D*, _Alloc = std::allocator<Polygon3D*>]
<near match>       

Answer 1

It’s _Tp that is const, and in this case _Tp is a pointer. So the substitution for const _Tp will actually result in Polygon3D *const, not const Polygon3D *, hence the mismatch.