On Thu, 16 Feb 2023, 18:39 , <i.nixman@autistici.org> wrote:

> On 2023-02-16 15:29, Jonathan Wakely wrote:
> > On Thu, 16 Feb 2023 at 15:25, i.nixman--- via Gcc-help
> > <gcc-help@gcc.gnu.org> wrote:
> >>
> >> hello,
> >>
> >>
> >> I can successfully build the same C++ code using GCC-8.3.1 for Debug
> >> (-g
> >> -O0) and Release (-g -O2) build.
> >> I can successfully debug the Release-executable on a remote host, but
> >> I
> >> can't debug the Debug-executable on a remote host, because the
> >> Debug-executable imports an extra symbol
> >> _ZNKSt9basic_iosIcSt11char_traitsIcEEcvbEv from libstdc++ which
> >> doesn't
> >> exist.
> >
> > It should exist, it has been there since GCC
>
> hmm...
>
> I just checked the two binaries using this cmd:
>
> > readelf -sW executable | grep
> > _ZNKSt9basic_iosIcSt11char_traitsIcEEcvbEv
>
> it shows nothing for release build, and shows this for debug build:
>
> >     54: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND
> > _ZNKSt9basic_iosIcSt11char_traitsIcEEcvbEv
> > 199898: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND
> > _ZNKSt9basic_iosIcSt11char_traitsIcEEcvbEv
>


This only shows that the function is inlined in the optimized build, and
not in the debug build, so the debug one has an unresolved reference to a
symbol defined in the libstdc++ dynamic library. This is completely normal.


>
> what should I do next to understand the reason?
>

Check which libstdc++.so.6 is being used by the executable when you're
debugging it and make sure it's the one from the GCC build you're compiling
with.

https://gcc.gnu.org/onlinedocs/libstdc++/manual/using_dynamic_or_shared.html#manual.intro.using.linkage.dynamic

Since the problem happens when debugging on a remote host, you need to make
sure you have the right libstdc++.so.6 when doing that debugging.


moreover, im unsure I understand the reason correctly...
>
>
>
> best!
>
>
> >
> >>
> >> but I don't want to debug libstdc++, so I think I shouldn't install
> >> additional debug version of libstdc++.
> >>
> >> it looks like a bug, or am I wrong?
> >>
> >> another my question is, what should I do to get rid of that extra
> >> symbol
> >> in Debug build?
> >>
> >>
> >>
> >>
> >> best!
> >>
> >> ps
> >> I can't update GCC nor libstdc++.
>