Re: Ill-formed C++0x code or compiler bug (GCC) ?
On 28 Jan., 20:19, Dilip wrote:
On Jan 28, 5:36 am, SG wrote:
struct use_copy_ctor {};
struct prefer_clone_func : use_copy_ctor {};
template<class T>
auto clone(T const* ptr, prefer_clone_func)
-> decltype(ptr->clone())
{ return ptr->clone(); }
template<class T>
auto clone(T const* ptr, use_copy_ctor)
-> decltype(new T(*ptr))
{ return new T(*ptr); }
struct abc {
virtual ~abc() {}
virtual abc* clone() const =0;
};
struct derived : abc
{
derived* clone() const { return new derived(*this); }
};
int main()
{
derived d;
abc* p = &d;
abc* q = clone(p,prefer_clone_func());
delete q;
}
VC++ 2010 fails with a *linker* error:
error LNK2019: unresolved external symbol "public: __thiscall
abc::abc(void)" (??0abc@@QAE@XZ) referenced in function "public:
__thiscall derived::derived(void)" (??0derived@@QAE@XZ)
That's weird. Looks like VC++ forgot to emit the definition of the
"compiler-generated" default constructor of abc.
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