compile warning in serialization/extended_type_info.hpp on visual studio: c4265

[David Frink <david.frink@…>]

class boost::serialization::extended_type_info generates warning ​c4265 with visual studio 2005, 2008, and 2010 because the destructor is not virtual, even though the class has virtual functions.

Looking at the class, I see that the warning was fixed only for gcc:

    // account for bogus gcc warning
    #if defined(__GNUC__)
    virtual
    #endif
    ~extended_type_info();

I believe the fix is to always declare the destructor virtual.

[Robert Ramey]

The reason this "virtual" is not necessary is that the destructor is protected so it cannot be called directly so there is no need to add a new member to the virtual function table. GCC doesn't have a convenient way to suppress bogus warnings so to avoid this warning I had to do this. This is basically the wrong thing to do but if I don't do it, I get complaints about "bugs" in the library. If you want to suggest the usaage of a praga or something for msvc - I'll put it in.

Robert Ramey