Re: libstdc++.so.0.29 contains undefined reference to libiconv

[Yubin Ruan <ablacktshirt@gmail.com>]

On Thu, Apr 7, 2022 at 5:03 PM Jonathan Wakely <jwakely.gcc@gmail.com> wrote:
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> On Thu, 7 Apr 2022, 10:02 Jonathan Wakely, <jwakely.gcc@gmail.com> wrote:
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>> On Thu, 7 Apr 2022, 03:38 Yubin Ruan via Libstdc++, <libstdc++@gcc.gnu.org> wrote:
>>>
>>> Hi,
>>>
>>> I compile GCC 11.2 and get a libstdc++.so.6.0.29 (installed in
>>> "/usr/local/mygcc/lib64/") but this shared lib contains undefined
>>> reference to libiconv_*.
>>>
>>> When I compile a hello world program using gcc11.2, I get the following error:
>>>
>>> > /usr/local/mygcc/bin/g++ -Wall -std=c++17 hw.cc -o hw
>>> /usr/local/mygcc/bin/../lib/gcc/x86_64-pc-linux-gnu/11.2.0/../../../../lib64/libstdc++.so:
>>> undefined reference to `libiconv'
>>> /usr/local/mygcc/bin/../lib/gcc/x86_64-pc-linux-gnu/11.2.0/../../../../lib64/libstdc++.so:
>>> undefined reference to `libiconv_close'
>>> /usr/local/mygcc/bin/../lib/gcc/x86_64-pc-linux-gnu/11.2.0/../../../../lib64/libstdc++.so:
>>> undefined reference to `libiconv_open'
>>> collect2: error: ld returned 1 exit status
>>>
>>> Adding a "-liconv" flag will help this program compile.
>>>
>>> From ldd's output, the libstdc++.so does not has any dynamic reference
>>> to libiconv;
>>>
>>>   > ldd /usr/local/mygcc/lib64/libstdc++.so.6.0.29
>>>           linux-vdso.so.1 =>  (0x00007ffce1fea000)
>>>           libm.so.6 => /lib64/libm.so.6 (0x00007fefc74b8000)
>>>           libc.so.6 => /lib64/libc.so.6 (0x00007fefc70e9000)
>>>           /lib64/ld-linux-x86-64.so.2 (0x00007fefc7bd1000)
>>>           libgcc_s.so.1 =>
>>> /usr/local/$INSTALL_PREFX/lib64/libgcc_s.so.1 (0x00007fefc6ed1000)
>>>
>>> But from nm 's output, there are indeed undefined reference to libiconv*
>>>
>>>   > nm -D /usr/local/mygcc/lib64/libstdc++.so.6.0.29 |grep -i iconv
>>>                    U libiconv
>>>                    U libiconv_close
>>>                    U libiconv_open
>>>
>>> I already have libiconv installed under /usr/local when compiling
>>> GCC11.2, but this does not seems to help;
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>> It doesn't help because that is the cause of the problem.
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>> Glibc defines the iconv routines that libstdc++ needs, and so you should not use libiconv on Linux systems using Glibc.
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> There is an existing bug in bugzilla about this case.

Can you provide the bugzilla URL ?