tcantenot / cooperative-visitor Goto Github PK

Hi, I've been implementing the visitor in one of my test case and found a problem when I have a visitable which derives from 2 virtual base classes. One of which is visitable base.

I found that the problem happens while storing / using the void * visitable in the InvocationInfo.

It is created using a pointer to the most derived visitable, stored in a void* ( see META_Visitable ) so it will already be offset.

It is used as a Base* directly cast from the void* then recast into the VisitableType ( see (this->*thunk)(*static_cast<Base *>(info.visitable), std::forward(args)...); ) this means it is offsetted twice. ( see VisitableType * visitable = static_cast<VisitableType *>(&b); )

I fixed the problem by completely ignoring the "visitable" member of the InvocationInfo and passing b as the parameter to this->*thunk

return (this->*thunk)(b, std::forward(args)...);

I am wondering why this member "visitable" even exists.