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c++/3894: Template derived from virtual base cannot work with std::vector
- To: gcc-gnats at gcc dot gnu dot org
- Subject: c++/3894: Template derived from virtual base cannot work with std::vector
- From: scisim at astro dot estec dot esa dot nl
- Date: 31 Jul 2001 11:51:25 -0000
- Reply-To: scisim at astro dot estec dot esa dot nl
>Number: 3894
>Category: c++
>Synopsis: Template derived from virtual base cannot work with std::vector
>Confidential: no
>Severity: serious
>Priority: medium
>Responsible: unassigned
>State: open
>Class: sw-bug
>Submitter-Id: net
>Arrival-Date: Tue Jul 31 04:56:01 PDT 2001
>Closed-Date:
>Last-Modified:
>Originator: SciSim
>Release: gcc version 2.95.4 20010319 (Debian prerelease)
>Organization:
>Environment:
# default
>Description:
Cannot find copy constructor of derived class, if
derived class is a template and its base class it virtual.
>How-To-Repeat:
$ cat > Duck.cc
#include <iostream>
#include <vector>
class Duck {
public:
Duck()
{
std::cout<<"Constructing a duck\n";
}
Duck(const Duck& rhs)
{
std::cout << "Copy constructing a duck\n";
}
virtual ~Duck(){}
};
template<class T>
class UncleDagobert : public virtual Duck {
public:
UncleDagobert() : Duck()
{
std::cout<<"Constructing a rich duck\n";
}
UncleDagobert(const UncleDagobert<T> &rhs) : Duck(rhs)
{
std::cout<<"Copy-constructing a rich duck\n";
}
UncleDagobert<T >& operator=(const UncleDagobert<T >& rhs) {}
virtual ~UncleDagobert(){}
};
int main()
{
UncleDagobert<double> o;
UncleDagobert<double> oo(o);
std::vector<UncleDagobert<double > > v;
v.push_back(o);
v.push_back(oo);
}
$ g++ Duck.cc
/usr/lib/gcc-lib/i386-linux/2.95.4/../../../../include/g++-3/stl_vector.h: In method `void vector<UncleDagobert<double>,allocator<UncleDagobert<double> > >::_M_insert_aux(UncleDagobert<double> *, const UncleDagobert<double> &)':
/usr/lib/gcc-lib/i386-linux/2.95.4/../../../../include/g++-3/stl_vector.h:325: instantiated from here
/usr/lib/gcc-lib/i386-linux/2.95.4/../../../../include/g++-3/stl_vector.h:593: no matching function for call to `UncleDagobert<double>::UncleDagobert (const UncleDagobert<double> &)'
Duck.cc:21: candidates are: UncleDagobert<double>::UncleDagobert()
$
>Fix:
class UncleDagobert : public Duck
>Release-Note:
>Audit-Trail:
>Unformatted: