------- Comment #3 from jeidsath at gmail dot com 2007-11-21 23:52 -------
(In reply to comment #2)
> I think this is the issue, nothing specific to std::auto_ptr:
>
> struct G { G() { } G(G&) { } };
>
> int main()
> {
> class A
> {
> const G g;
> };
> A a;
> A b = a;
> }
>
No, copying of const values is certainly allowed:
const int i = 5;
const int i2 = i; //SHOULD compile
Your struct G can also be created and copied:
G g;
G g2 = g;
However, the same does not work with const auto_ptr, because copying
is a non-const operation for auto_ptrs:
const auto_ptr<int> i;
const auto_ptr<int> i2 = i; //ERROR
Did you mean to make the copy constructor private? In that case, G
certainly won't work in my example, const or not, and g++ catches
this.
Now, if you're trying to make a more general example, try this:
#include <iostream>
struct H
{
H()
{ a=5; } ;
H(H& rhs)
{ rhs.a=10; };
int a;
};
int main()
{
struct B
{
const H h;
};
B b;
B b2 = b;
std::cout << b.h.a << "\n";//ERROR prints out "10",
//b.h has been changed despite constness
}
The copy constructor for H does not take a const reference because I
am modelling auto_ptr -- compare gcc's definition of the auto_ptr copy
constructor in "memory":
auto_ptr(auto_ptr& __a) throw() : _M_ptr(__a.release()) { }
Joel Eidsath
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34180
