[C++-sig] Boost.Python: undefined symbols when loading a shared library

[Bin Song]

Hello Everyone,

I have been working on a code inside the MD simulation package
ESPResSo++, which calls code from another package PLUMED to perform
some calculations.  ESPResSO++ is written using Boost.Python library,
while PLUMED is mostly C++. My code works when PLUMED is statically
linked. The "undefined symbols" error arises when I uses runtime
linking. Basically some interface code are compiled with ESPResSO++,
and thereby some symbols are inside the ESPResSO++ shared library.
During the runtime, the PLUMED shared library is loaded by dlopen(),
then the code complains the symbols are undefined. I have asked the
question on stackoverflow (
https://stackoverflow.com/questions/48584427/undefined-symbols-when-loading-c-shared-lib-within-a-shared-c-lib-which-its
). Unfortunately no solution has been found yet. The point is that I
know for sure the "missing" symbols are marked as "T" in the
ESPResSO++ shared library. I tried options such as -rdynamic or
-Wl,-export-dynamic flags when creating the ESPResSO++ shared library
to make the symbols visible, based on the webpages I found. Still the
issue persists. I use the ESPResSO++ through a Python script. First
Python objects are created, and then C++ objects are created. I wonder
if the issue has to do with the fact that the ESPResSO++ shared
library is imported by Python. Maybe during the process, the symbols
related to PLUMED are hidden somehow.

If you know how to fix this, or how to diagnose the issue, please let
me know. All help are appreciated.

Best,
Bin