python 2.7.x on MacOSX: failed dlopen() on .so's

[Paul Smith]

Hi all.  I need to build my own version of Python on a MacOSX system,
and I can't seem to do it successfully.  I need to build it with a
particular location, etc. and so I can't use Homebrew or whatever: I
need to compile it myself from the source tarball.  I did look through
the Homebrew recipe and I don't see anything that seems like it would
help with my problem.

I'm using MacOSX 10.7.5 with xcode 4.1, containing gcc 4.2.1 / clang 2.1
(configure seems to choose gcc).

I've tried this with both Python 2.7.5 and 2.7.6.  I get the tarball,
unpack it, then:

  $ configure --prefix=/Users/build/python
  $ make
  $ make install
  $ export PATH=/Users/build/python/bin:$PATH
  $ export PYTHONHOME=/Users/build/python
  $ python2.7 --version
  Python 2.7.6

Simple scripts seem to work fine.  But then I need to install various
packages; for example pycrypto.  When I try to build that it fails to
build:

  $ cd src/pycrypto-2.6 && python2.7 setup.py build
  Traceback (most recent call last):
    File "setup.py", line 45, in <module>
      import struct
    File "/Users/build/python/lib/python2.7/struct.py", line 1, in <module>
      from _struct import *
  ImportError: dlopen(/Users/build/python/lib/python2.7/lib-dynload/_struct.so, 2): Symbol not found: _PyObject_Free
    Referenced from: /Users/build/python/lib/python2.7/lib-dynload/_struct.so
    Expected in: dynamic lookup

This happens with every module that is not pure-Python: boto, paramiko,
etc.

Looking at the various python2.7/lib-dynload/*.so files with nm I see
that actually a number of them refer to an unresolved ("U") symbol
_PyObject_Free (and other _PyObject_* symbols).  I can't find any shared
library being built by the python build (.dylib or .so or whatever);
there's just a libpython2.7.a file (I tried forcing --enable-shared on
the configure line and it didn't change anything).


I should say that I've used this same configuration and set of steps,
etc. on my GNU/Linux system and it worked perfectly.