[Numpy-discussion] Problem with libgfortran installed with pip install numpy

David Grote dpgrote at lbl.gov
Wed Sep 5 19:37:14 EDT 2018

Hi - I have recently come across this problem. On my mac, I build a Fortran
code, producing a shared object, that I import into Python along with
numpy. This had been working fine until recently when I started seeing sag
faults deep inside the Fortran code, usually in Fortran print statements. I
tracked this down to a gfortran version issue.

I use the brew installation of Python and gcc (using the most recent
version, 8.2.0). gcc of course installs a version of libgfortran.dylib.
Doing a lsof of a running Python, I see that it finds that copy of
libgfortran, and also a copy that was downloaded with numpy
Looking at numpy's copy of libgfortran, I see that it is version 4.9.0,
much older. Since my code is importing numpy first, the OS seems be using
numpy's version of libgfortran to link when importing my code. I know from
other experience that older versions of libgfortran are not compatible with
code compiled using a new version of gfortran and so therefore segfaults

If I download the numpy source and do python setup.py install, I don't have
this problem.

After this long description, my question is why is such an old version of
gcc used to build the distribution of numpy that gets installed from pypi?
gcc version 4.9.0 is from 2014. Can a newer version be used?
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