On Tue, 30 Aug 2022, 19:46 Anton Wöllert, <a.woellert@gmail.com> wrote:

> Thanks for your comments,
>
> sorry for posting on the wrong mailing list.  I'll just restate my
> initial question here on gcc-help again:
>
>    I was trying to build a cross-compilation toolchain for a specific
>    target using a newer GCC version, than the one that the binaries
>    were build on the target.
>
>    The C part seems to work well, but the C++ part doesn't.  It seems
>    that the G++ ships it's own libstdc++ include headers.  If this
>    libstdc++ is newer than the one one the target, I get undefined
>    references (because there are some newer implementation details and
>    things like that).  Is it possible to tell G++/GCC to use the
>    libstdc++.so from the target and also to use the C++ headers (like
>    iostream) from the target?
>    If not, is there any reason this is hard-coded?
>
>    With clang it looks like you can specify "any" libstdc++ version you
>    want, although I haven't tested it yet.
>
> On Tue, 2022-08-30 at 18:21 +0100, Jonathan Wakely wrote:
> > This doesn't belong on this mailing list though, please use the gcc-
> > help list instead.
> >
> > This list is for discussion of GCC development, not help using it.
> >
> >
> > > > C++ in general
> > > > tries to be very good in backward compatibility.
> > > > This essentially means that you can't use newer compilers with
> > > > more
> > > > features/bugfixes to compile software for older targets.
> > >
> > >
> > > No it doesn't. Using new compilers on older machines works fine.
> > > You just need to do it right.
> > >
>
> So what is the right way to compile software with a newer version of
> gcc for a target, that has an older version of gcc?  I can't find any
> hints about that in documentation.  Should I ship the newer
> libstdc++.so with the application to the target and set
> LD_LIBRARY_PATH?


As the documentation says, there are other ways that might be better than
LD_LIBRARY_PATH, but they all require shipping the new libstdc++.so.6 with
the application. Static linking is another option, which avoids needing the
new libstdc++.so.6 at runtime.



  Then I probably also have to add other libraries,
> right?
>

No, you shouldn't need to.


>
> Kind regards,
> Anton
>
>
>