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.

Is this still a problem given that both Python and Solaris have moved on?

I just tried Python 2.7.6 on x86_64-pc-openindiana151a9.   The core issue is still present.  It's not currently causing a build failure, but only because OpenIndiana 151a9 and Python are using the exact same version of Expat, so the headers that python's build process is mistakenly including from the operating system match the code that it's compiling internally.

My comment in msg97311 on 2010-01-06 is still valid.  If Python's build process is going to use internal expat, then it better ensure that the compilation flags it needs for that (including the -I) comes before the standard CFLAGS & CPPFLAGS.

The issue applies and is reproducible for all versions 2.6 through 3.5.

This is the changeset we applied to all FreeBSD Ports to fix the issue:

https://svnweb.freebsd.org/ports?view=revision&revision=326729

One specific example (Python 3.3):

1) Use CPPFLAGS over CFLAGS (See before *and* after comments):

  https://svnweb.freebsd.org/ports/head/lang/python33/Makefile?r1=326729&r2=326728&pathrev=326729

2) Revert the absolutely crazy complexity in Makefile.pre.in by stripping out CONFIGURE_*, allowing once again
./configure to substitute the right variables based on what has been passed to it:

  https://svnweb.freebsd.org/ports/head/lang/python33/files/patch-Makefile.pre.in?r1=326729&r2=326728&pathrev=326729

This results in:

Makefile.pre.in:
  CPPFLAGS=       @CPPFLAGS@ <-- YAY!
  PY_CPPFLAGS=    $(BASECPPFLAGS) -I. -IInclude -I$(srcdir)/Include $(CPPFLAGS) <-- YAY
  
Makefile:
  CPPFLAGS=       -I/usr/local/include - YAY!
  PY_CPPFLAGS=    $(BASECPPFLAGS) -I. -IInclude -I$(srcdir)/Include $(CPPFLAGS) <-- YAY!

The root cause *requiring* the use of CPPFLAGS, is PY_CFLAGS before PY_CPPFLAGS here:

  PY_CORE_CFLAGS= $(PY_CFLAGS) $(PY_CPPFLAGS) $(CFLAGSFORSHARED) -DPy_BUILD_CORE

As per https://www.gnu.org/prep/standards/html_node/Command-Variables.html

"Put CFLAGS last in the compilation command, after other variables containing compiler options, so the user can use CFLAGS to override the others."

We must use CPPFLAGS, because CFLAGS has been broken in one way or another for a long time. The target state is *both* must just work.

This can only happen if the standard user-serviceable autoconf and Makefile variables are left alone, not extended or overridden, and behave in exactly the same way whether provided in the environment for *either* ./configure, make, or *both*.

For the most recent chapter in the C[PP|LD]FLAGS/Makefile book, see: 92a9dc668c95 from #9189 which was sound in intent, but in execution left us deeper down the rabbit-hole.

Moving forward and as a first step, what does everyone think of switching the order of
$(PY_CFLAGS) $(PY_CPPFLAGS) in PY_CORE_CFLAGS= ?

I hope (but I'm not holding my breath) that nothing relies on the current ordering.

Setting versions to correctly reflect those affected.

Adding a patch for reference only