Bare metal C++ with a GNU/Linux toolchain

Bare metal C++ with a GNU/Linux toolchain

[Florian Weimer]

It seems that it is fairly straightforward to eliminate dependencies on
libstdc++ if only a C++ subset is used (no exception handling, no RTTI,
no operator new, etc.).  But once you use abstract classes, you
necessarily gain a reference to __cxa_pure_virtual.

Would it be possible to document this symbol as interposable, so that
developers can bring their own definition if they want?  If yes, what
would be the appropriate place for this?

Thanks,
Florian

Re: Bare metal C++ with a GNU/Linux toolchain

[François Dumont]

On 18/05/22 13:16, Florian Weimer via Libstdc++ wrote:
> It seems that it is fairly straightforward to eliminate dependencies on
> libstdc++ if only a C++ subset is used (no exception handling, no RTTI,
> no operator new, etc.).

Those C++ features are in libsup++, not libstdc++.

You should still be able to use full C++ without libstdc++.

I used to do so when working on STLport but it was such a long time ago 
that the way we were doing it is surely outdated.


>    But once you use abstract classes, you
> necessarily gain a reference to __cxa_pure_virtual.
>
> Would it be possible to document this symbol as interposable, so that
> developers can bring their own definition if they want?  If yes, what
> would be the appropriate place for this?
>
> Thanks,
> Florian
>

Re: Bare metal C++ with a GNU/Linux toolchain

[Jonathan Wakely]

On Wed, 18 May 2022 at 18:04, François Dumont via Libstdc++
<libstdc++@gcc.gnu.org> wrote:
>
> On 18/05/22 13:16, Florian Weimer via Libstdc++ wrote:
> > It seems that it is fairly straightforward to eliminate dependencies on
> > libstdc++ if only a C++ subset is used (no exception handling, no RTTI,
> > no operator new, etc.).
>
> Those C++ features are in libsup++, not libstdc++.

Yes, but that's still part of the libstdc++ project and so documenting
this in the libstdc++ manual is probably the right place (but I'm not
sure where in the manual yet).


>
> You should still be able to use full C++ without libstdc++.
>
> I used to do so when working on STLport but it was such a long time ago
> that the way we were doing it is surely outdated.
>
>
> >    But once you use abstract classes, you
> > necessarily gain a reference to __cxa_pure_virtual.
> >
> > Would it be possible to document this symbol as interposable, so that
> > developers can bring their own definition if they want?  If yes, what
> > would be the appropriate place for this?
> >
> > Thanks,
> > Florian
> >
>