I've built Python 2.6.1 and Python 2.6.2 on x86_64-sun-solaris2.10 using
the Sun Workshop Express (200903) toolchain.  I'm building in 64 bit mode.

Most stuff builds just fine (even warnings are rare), but pyexpat fails
to link with this error:

building 'pyexpat' extension
creating
build/temp.solaris-2.10-i86pc-2.6/local/src/RPM/BUILD/Python-2.6.2/Modules/expat
cc -xtarget=native -m64 -xarch=native -KPIC -DNDEBUG -Xa -xO4 -xstrconst
-mt -xtarget=native -m64 -xarch=native -I/local/include
-I/local/gnu/include -I/local/BerkeleyDB/include
-I/local/openssl/include -DHAVE_EXPAT_CONFIG_H=1 -DUSE_PYEXPAT_CAPI
-I/local/src/RPM/BUILD/Python-2.6.2/./Modules/expat -I.
-I/local/src/RPM/BUILD/Python-2.6.2/./Include -I. -IInclude -I./Include
-I/local/include -I/local/gnu/include -I/local/BerkeleyDB/include
-I/local/openssl/include -I/usr/local/include
-I/local/src/RPM/BUILD/Python-2.6.2/Include
-I/local/src/RPM/BUILD/Python-2.6.2 -c
/local/src/RPM/BUILD/Python-2.6.2/Modules/pyexpat.c -o
build/temp.solaris-2.10-i86pc-2.6/local/src/RPM/BUILD/Python-2.6.2/Modules/pyexpat.o
"/local/src/RPM/BUILD/Python-2.6.2/Modules/pyexpat.c", line 1574:
warning: assignment type mismatch:
    pointer to void "=" pointer to function(pointer to void, pointer to
const ch
ar, int) returning void
cc -xtarget=native -m64 -xarch=native -KPIC -DNDEBUG -Xa -xO4 -xstrconst
-mt -xtarget=native -m64 -xarch=native -I/local/include
-I/local/gnu/include -I/local/BerkeleyDB/include
-I/local/openssl/include -DHAVE_EXPAT_CONFIG_H=1 -DUSE_PYEXPAT_CAPI
-I/local/src/RPM/BUILD/Python-2.6.2/./Modules/expat -I.
-I/local/src/RPM/BUILD/Python-2.6.2/./Include -I. -IInclude -I./Include
-I/local/include -I/local/gnu/include -I/local/BerkeleyDB/include
-I/local/openssl/include -I/usr/local/include
-I/local/src/RPM/BUILD/Python-2.6.2/Include
-I/local/src/RPM/BUILD/Python-2.6.2 -c
/local/src/RPM/BUILD/Python-2.6.2/Modules/expat/xmlparse.c -o
build/temp.solaris-2.10-i86pc-2.6/local/src/RPM/BUILD/Python-2.6.2/Modules/expat/xmlparse.o
cc -xtarget=native -m64 -xarch=native -KPIC -DNDEBUG -Xa -xO4 -xstrconst
-mt -xtarget=native -m64 -xarch=native -I/local/include
-I/local/gnu/include -I/local/BerkeleyDB/include
-I/local/openssl/include -DHAVE_EXPAT_CONFIG_H=1 -DUSE_PYEXPAT_CAPI
-I/local/src/RPM/BUILD/Python-2.6.2/./Modules/expat -I.
-I/local/src/RPM/BUILD/Python-2.6.2/./Include -I. -IInclude -I./Include
-I/local/include -I/local/gnu/include -I/local/BerkeleyDB/include
-I/local/openssl/include -I/usr/local/include
-I/local/src/RPM/BUILD/Python-2.6.2/Include
-I/local/src/RPM/BUILD/Python-2.6.2 -c
/local/src/RPM/BUILD/Python-2.6.2/Modules/expat/xmlrole.c -o
build/temp.solaris-2.10-i86pc-2.6/local/src/RPM/BUILD/Python-2.6.2/Modules/expat/xmlrole.o
cc -xtarget=native -m64 -xarch=native -KPIC -DNDEBUG -Xa -xO4 -xstrconst
-mt -xtarget=native -m64 -xarch=native -I/local/include
-I/local/gnu/include -I/local/BerkeleyDB/include
-I/local/openssl/include -DHAVE_EXPAT_CONFIG_H=1 -DUSE_PYEXPAT_CAPI
-I/local/src/RPM/BUILD/Python-2.6.2/./Modules/expat -I.
-I/local/src/RPM/BUILD/Python-2.6.2/./Include -I. -IInclude -I./Include
-I/local/include -I/local/
gnu/include -I/local/BerkeleyDB/include -I/local/openssl/include
-I/usr/local/include -I/local/src/RPM/BUILD/Python-2.6.2/Include
-I/local/src/RPM/BUILD/Python-2.6.2 -c
/local/src/RPM/BUILD/Python-2.6.2/Modules/expat/xmltok.c -o
build/temp.solaris-2.10-i86pc-2.6/local/src/RPM/BUILD/Python-2.6.2/Modules/expat/xmltok.o
cc -xtarget=native -m64 -xarch=native -G -L/local/lib/64
-L/local/gnu/lib/64 -L/local/BerkeleyDB/lib/64 -L/local/openssl/lib/64
-L/local/lib/64 -L/local/gnu/lib/64 -L/local/BerkeleyDB/lib/64
-L/local/openssl/lib/64 -DNDEBUG -Xa -xO4 -xstrconst -mt -xtarget=native
-m64 -xarch=native -I/local/include -I/local/gnu/include
-I/local/BerkeleyDB/include -I/local/openssl/include -I. -IInclude
-I./Include 
-I/local/include -I/local/gnu/include -I/local/BerkeleyDB/include
-I/local/openssl/include
build/temp.solaris-2.10-i86pc-2.6/local/src/RPM/BUILD/Python-2.6.2/Modules/pyexpat.o
build/temp.solaris-2.10-i86pc-2.6/local/src/RPM/BUILD/Python-2.6.2/Modules/expat/xmlparse.o
build/temp.solaris-2.10-i86pc-2.6/local/src/RPM/BUILD/Python-2.6.2/Modules/expat/xmlrole.o
build/temp.solaris-2.10-i86pc-2.6/local/src/RPM/BUILD/Python-2.6.2/Modules/expat/xmltok.o
-L/local/lib -L/local/lib/64 -L/local/gnu/lib/64
-L/local/BerkeleyDB/lib/64 -L/local/openssl/lib/64 -L/usr/local/lib -o
build/lib.solaris-2.10-i86pc-2.6/pyexpat.so
*** WARNING: renaming "pyexpat" since importing it failed: ld.so.1:
python: fatal: relocation error: file
build/lib.solaris-2.10-i86pc-2.6/pyexpat.so: symbol
XML_SetCharacterDataHandler: referenced symbol not found

I never tried any of the 2.5.x Python builds, but I can tell you that I
built several versions in the 2.4.x series, and none of those versions
had problems compiling or linking pyexpat.

I do have expat 2.0.1 (also built with the Sun compiler in 64 bit mode)
installed on the system, but from the comments in setup.py and the
compiler output, it appears clear that the expat components that ship
with Python 2.6.x are the ones that are being compiled and attempted for
use in the link.

Please let me know if I can provide any relevant information.

Thanks,

Tim (the Enchanter)

This still happens in 2.6.3 and 2.6.4 so I spent some time looking at it.

It's happening because of a combination of issues, but ultimately it's because python's build isn't making certain that it's including its private copy of expat.h and expat_external.h.

Basically, this

-DHAVE_EXPAT_CONFIG_H=1 -DUSE_PYEXPAT_CAPI -I/local/src/RPM/BUILD/Python-2.6.4/./Modules/expat

should *precede* CFLAGS, rather than coming after it.

To reproduce:

- install expat 2.0.1 under /usr/local or /opt (or any prefix other
  than just /usr)
- include -I$prefix/include in CFLAGS when configuring Python
- make

This results in the special includes for python's local copy of the expat sources being *after* the -I/usr/local/include on the command line, so the copy of expat.h and expat_external.h in /usr/local/include are found first, and that causes the link failure when generating pyexpat.so.

Note that it's not just as simple as not including -I/usr/local/include in CFLAGS, because there may be other locally-installed packages that python should be finding to build other modules.

The real fix is for Python's build machinery to make certain that the special includes for Python's private expat sources precede CFLAGS.