Python 3.1.1 with --enable-shared : will not build any extensions

Question

Summary: Building Python 3.1 on RHEL 5.3 64 bit with --enable-shared fails to compile all extensions. Building "normal" works fine without any problems.

Please note that this question may seem to blur the line between programming and system administration. However, I believe that because it has to deal directly with getting language support in place, and it very much has to do with supporting the process of programming, that I would cross-post it here. Also at: http://serverfault.com/questions/73196/python-3-1-1-with-enable-shared-will-not-build-any-extensions. Thank you!

Problem:

Building Python 3.1 on RHEL 5.3 64 bit with --enable-shared fails to compile all extensions. Building "normal" works fine without any problems.

I can build python 3.1 just fine, but when built as a shared library, it emits many warnings (see below), and refuses to build any of the c based modules. Despite this failure, I can still build mod_wsgi 3.0c5 against it, and run it under apache. Needless to say, the functionality of Python is greatly reduced...

Interesting to note that Python 3.2a0 (from svn) compiles fine with --enable-shared, and mod_wsgi compiles fine against it. But when starting apache, I get:

Cannot load /etc/httpd/modules/mod_wsgi.so into server: /etc/httpd/modules/mod_wsgi.so: undefined symbol: PyCObject_FromVoidPtr

The project that this is for is a long-term project, so I'm okay with alpha quality software if needed. Here are some more details on the problem.

Host:

• Dell PowerEdge
• Intel Xenon
• RHEL 5.3 64bit
• Nothing "special"

Build:

• Python 3.1.1 source distribution
• Works fine with ./configure
• Does not work fine with ./configure --enable-shared

(export CFLAGS="-fPIC" has been done)

make output

---

gcc -pthread -fno-strict-aliasing -DNDEBUG -g -fwrapv -O3 -Wall -Wstrict-prototypes -I. -IInclude -I./Include -fPIC -DPy_BUILD_CORE -c ./Modules/_weakref.c -o Modules/_weakref.o

---

building 'bz2' extension gcc -pthread -fPIC -fno-strict-aliasing -DNDEBUG -g -fwrapv -O3 -Wall -Wstrict-prototypes -I. -I./Include -I/usr/local/include -IInclude -I/home/build/RPMBUILD/BUILD/Python-3.1.1 -c /home/build/RPMBUILD/BUILD/Python-3.1.1/Modules/bz2module.c -o build/temp.linux-x86_64-3.1/home/build/RPMBUILD/BUILD/Python-3.1.1/Modules/bz2module.o gcc -pthread -shared -fno-strict-aliasing -DNDEBUG -g -fwrapv -O3 -Wall -Wstrict-prototypes build/temp.linux-x86_64-3.1/home/build/RPMBUILD/BUILD/Python-3.1.1/Modules/bz2module.o -L/usr/local/lib -L. -lbz2 -lpython3.1 -o build/lib.linux-x86_64-3.1/bz2.so /usr/bin/ld: /usr/local/lib/libpython3.1.a(abstract.o): relocation R_X86_64_32 against 'a local symbol' can not be used when making a shared object; recompile with -fPIC

---

Failed to build these modules:
_bisect            _codecs_cn         _codecs_hk
_codecs_iso2022    _codecs_jp         _codecs_kr
_codecs_tw         _collections       _csv
_ctypes            _ctypes_test       _curses
_curses_panel      _dbm               _elementtree
_gdbm              _hashlib           _heapq
_json              _lsprof            _multibytecodec
_multiprocessing   _pickle            _random
_socket            _sqlite3           _ssl
_struct            _testcapi          array
atexit             audioop            binascii
bz2                cmath              crypt
datetime           fcntl              grp
itertools          math               mmap
nis                operator           ossaudiodev
parser             pyexpat            readline
resource           select             spwd
syslog             termios            time
unicodedata        zlib

Answer 1

Something is wrong with your build environment. It is picking up a libpython3.1.a from /usr/local/lib; this confuses the error messages. It tries linking with that library, which fails - however, it shouldn't have tried that in the first place, since it should have used the libpython that it just built. I recommend taking the Python 3.1 installation in /usr/local out of the way.

You don't show in your output whether a libpython3.1.so.1.0 was created in the build tree; it would be important to find out whether it exists, how it was linked, and what symbols it has exported.

Answer 2

/usr/local/lib has been added to the library include path at compile time:

-L/usr/local/lib -L.

Its common for compile time to look in multiple 'common' paths for libraries (/usr/lib, /usr/local/lib, ./, etc) but also, it's possibly picking up /usr/local/lib from the environment variable LD_LIBRARY_PATH and tacking it on to the build command.