Re: Extra import symbol in debug build

[i.nixman@autistici.org]

On 2023-02-17 11:26, Jonathan Wakely wrote:
> On Fri, 17 Feb 2023, 08:51 , <i.nixman@autistici.org> wrote:
> 
>> On 2023-02-16 20:08, Jonathan Wakely wrote:
>> > 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.
>> >
>> 
>> then I have two questions:
>> 
>> 1. will the problem be solved by "pushing" a debug version of 
>> libstdc++
>> on the remote machine?
>> 
> 
> You don't need a debug version, the symbol is present in all builds of
> libstdc++.

hmm..
but I can't confirm that using this cmd:
readelf -sW /lib64/libstdc++.so.6 | grep 
_ZNKSt9basic_iosIcSt11char_traitsIcEEcvbEv