Re: g++ libstdc++ linker question.
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On 30 April 2012 18:28, Jonathan Wakely <jwakely.gcc@xxxxxxxxx> wrote: > On 30 April 2012 13:39, F. Heitkamp wrote: >> People will tell me to ask on matplotlib list but I believe this a more >> generic GNU C++ question. >> I have been trying to run matplotlib that I built from source on my linux >> from scratch like box. >> >> When I try to run an example I get: >> >> bash-4.2$ python2.6 matplotlib-ex1.py >> Traceback (most recent call last): >> File "matplotlib-ex1.py", line 13, in <module> >> import matplotlib.pyplot as plt >> File "/usr/lib/python2.6/site-packages/matplotlib/pyplot.py", line 23, in >> <module> >> from matplotlib.figure import Figure, figaspect >> File "/usr/lib/python2.6/site-packages/matplotlib/figure.py", line 16, in >> <module> >> import artist >> File "/usr/lib/python2.6/site-packages/matplotlib/artist.py", line 6, in >> <module> >> from transforms import Bbox, IdentityTransform, TransformedBbox, >> TransformedPath >> File "/usr/lib/python2.6/site-packages/matplotlib/transforms.py", line 34, >> in <module> >> from matplotlib._path import affine_transform >> ImportError: /usr/lib/python2.6/site-packages/matplotlib/_path.so: undefined >> symbol: >> _ZSt16__ostream_insertIcSt11char_traitsIcEERSt13basic_ostreamIT_T0_ES6_PKS3_i >> >> I see this symbol is in 32 bits libstdc++ library, but does not seem to >> appear in 64 bits versions. > > Right, the equivalent symbol in the 64-bit lib ends in _l instead of _i > >> bash-4.2$ ldd /usr/lib/python2.6/site-packages/matplotlib/_path.so >> linux-gate.so.1 => (0xffffe000) >> libpython2.6.so.1.0 => /usr/lib/libpython2.6.so.1.0 (0xf74f7000) >> libgcc_s.so.1 => /lib/libgcc_s.so.1 (0xf74de000) >> libpthread.so.0 => /lib/libpthread.so.0 (0xf74c4000) >> libc.so.6 => /lib/libc.so.6 (0xf7367000) >> libdl.so.2 => /lib/libdl.so.2 (0xf7362000) >> libutil.so.1 => /lib/libutil.so.1 (0xf735e000) >> libm.so.6 => /lib/libm.so.6 (0xf7338000) >> /lib/ld-linux.so.2 (0xf77d1000) >> >> libstdc++ is not shown as being linked with _path.so >> >> Any thoughts? > > Is _path.so a 32-bit or 64-bit library? From the missing symbol I'm > asuming 32-bit. > > It would appear it wasn't correctly linked, so its dependency on > libstdc++.so isn't recorded in the library by a DT_NEEDED entry. P.S. you can check the DT_NEEDED tags by running: readelf -d /usr/lib/python2.6/site-packages/matplotlib/_path.so > Does it help if you tell the dynamic linker to preload libstdc++.so? > > LD_PRELOAD=/usr/lib/libstdc++.so python2.6 matplotlib-ex1.py The matplotlib I use is built with: python setupegg.py build_ext \ --rpath=/opt/gcc-4.4.3/lib64 python setupegg.py build python setupegg.py install --user The --rpath option ensures the right libstdc++.so is found at runtime (we have several installed). That build works here, and is linked to libstdc++.so. Unfortunately it builds matplotlib as a python egg, which is a very annoying package format. I'd rather not install it via egg, but have no experience doing so and can't suggest why your build was not linked to libstdc++.