Re: [Mingw-users] Exporting classes to MS Visual C++

[<dan...@ya...>]

> Everything is working perfectly with C functions, but not with C++
> classes.
> There are two problems:
> 1) it is hard to decipher the name mangling of Microsoft's compiler
> (especially for overloaded functions)
> 2) I need to export the virtual table
> It seems possible to export/import the virtual table but  I'm
> wondering
> if the virtual table would be managed by the gnu compiler in way
> compatible with the MS Visual C++ compiler.
> 
> What do you think ?
> Do I have to give up ?
> 
> Marcello
> 

Hello Marcello

This is from the g++ FAQs

"Why can't I link g++-compiled programs against libraries compiled by
some other C++ compiler?" 

"Some people think that, if only the FSF and Cygnus Support folks would
stop being stubborn and mangle names the same way that, say, cfront
does, then any g++-compiled program would link successfully against any
cfront-compiled library and vice versa. Name mangling is the least of
the problems. Compilers differ as to how objects are laid out, how
multiple inheritance is implemented, how virtual function calls are
handled, and so on, so if the name mangling were made the same, your
programs would link against libraries provided from other compilers but
then crash when run. For this reason, the ARM encourages compiler
writers to make their name mangling different from that of other
compilers for the same platform. Incompatible libraries are then
detected at link time, rather than at run time. "

I believe there is a movement to standardise some of the C++ ABI issues
 and that G++ developers, particularly Jason Merrill, are involved in
this movement.  See here: 

http://reality.sgi.com/dehnert_engr/cxx/cxx-summary.html

In the future, you may be able to do what you have suggested with the
Bltz++ lib.  But not yet.

Cheers 

danny


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