I'm trying to build a very simple example from the SWIG documentation
http://www.swig.org/Doc2.0/SWIGDocumentation.html#Introduction_build_system
There is a code snippet that demonstrates how to use SWIG in a CMake
build system, but I can not get this simple example to build on a Linux
platform where the Python libraries are not built with the '-fPIC'. I've
modified the example slightly by building a C example file instead of a
C++ file and here is my version
FIND_PACKAGE(SWIG REQUIRED)
INCLUDE(${SWIG_USE_FILE})
FIND_PACKAGE(PythonLibs)
INCLUDE_DIRECTORIES(${PYTHON_INCLUDE_PATH})
INCLUDE_DIRECTORIES(${CMAKE_CURRENT_SOURCE_DIR})
SET(CMAKE_SWIG_FLAGS "")
SET_SOURCE_FILES_PROPERTIES(example.i PROPERTIES SWIG_FLAGS "-includeall")
SWIG_ADD_MODULE(example python example.i example.c)
SWIG_LINK_LIBRARIES(example ${PYTHON_LIBRARIES})
On my Linux machine with static Python libs, the build fails trying to
create _example.so, complaining about the static Python library not
built with -fPIC.
Linking C shared module _example.so
/usr/bin/ld: /usr/local/lib/libpython2.6.a(abstract.o): relocation
R_X86_64_32 against `a local symbol' can not be used when making a
shared object; recompile with -fPIC
/usr/local/lib/libpython2.6.a: could not read symbols: Bad value
collect2: ld returned 1 exit status
This example works on systems where the Python library is shared (Mac
OSX) and if I remove the SWIG_LINK_LIBRARIES line it will compile on
the Linux system, but then fails to build on the Mac. Since the
construction of these Python modules is hidden by the SWIG macros I'm
very confused about what is going on.
Has anyone run into this problem with static Python libraries and did
you find a portable solution? Testing if the Python libraries are shared
or static and then coming up with an -fPIC test seems to be the only
solution I see to this problem.
--
Lori A. Pritchett-Sheats, PhD.
CCS-2, Computational Physics and Methods
Office: 505-665-6675
Fax: 505-665-4972
Los Alamos National Laboratory
P.O. Box 1663
MS D413
Los Alamos, NM 87544
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