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Why can I compile as C but not as C++ with Cython on Mac OS X

I am trying to figure out how to use C/C++ code in python using Cython. I can get the following example working as C code:
sum.h:
#ifndef MY_SUM_H_
#define MY_SUM_H_
int my_sum(int a, int b);
#endif
sum.c:
int my_sum(int a, int b){
return a + b;
}
test.pyx:
cdef extern from "my_sum.h":
cdef int my_sum(int a, int b)
cpdef sum_wrap(int a, int b):
return my_sum(a, b)
setup.py:
from distutils.core import setup
from distutils.extension import Extension
from Cython.Distutils import build_ext
ext_modules = [Extension("test", ["test.pyx", "my_sum.c"], language = "c")]
setup(cmdclass = {'build_ext': build_ext}, ext_modules = ext_modules)
However, if I try to test it as C++ code it fails. I rename sum.c to sum.cpp and change language to c++ in setup.py. After that, it looks like this:
from distutils.core import setup
from distutils.extension import Extension
from Cython.Distutils import build_ext
ext_modules = [Extension("test", ["test.pyx", "my_sum.cpp"], language = "c++")]
setup(cmdclass = {'build_ext': build_ext}, ext_modules = ext_modules)
That should be enough right? It produces the following error:
$ python setup.py build_ext --inplace
running build_ext
cythoning test.pyx to test.cpp
/Users/jensrenders/miniconda3/lib/python3.7/site-packages/Cython/Compiler/Main.py:367: FutureWarning: Cython directive 'language_level' not set, using 2 for now (Py2). This will change in a later release! File: /Users/jensrenders/Dropbox/cython_demo/test.pyx
tree = Parsing.p_module(s, pxd, full_module_name)
building 'test' extension
gcc -Wno-unused-result -Wsign-compare -Wunreachable-code -DNDEBUG -g -fwrapv -O3 -Wall -Wstrict-prototypes -I/Users/jensrenders/miniconda3/include -arch x86_64 -I/Users/jensrenders/miniconda3/include -arch x86_64 -I/Users/jensrenders/miniconda3/include/python3.7m -c test.cpp -o build/temp.macosx-10.7-x86_64-3.7/test.o
warning: include path for stdlibc++ headers not found; pass '-std=libc++' on the command line to use the libc++ standard
library instead [-Wstdlibcxx-not-found]
1 warning generated.
gcc -Wno-unused-result -Wsign-compare -Wunreachable-code -DNDEBUG -g -fwrapv -O3 -Wall -Wstrict-prototypes -I/Users/jensrenders/miniconda3/include -arch x86_64 -I/Users/jensrenders/miniconda3/include -arch x86_64 -I/Users/jensrenders/miniconda3/include/python3.7m -c my_sum.cpp -o build/temp.macosx-10.7-x86_64-3.7/my_sum.o
warning: include path for stdlibc++ headers not found; pass '-std=libc++' on the command line to use the libc++ standard
library instead [-Wstdlibcxx-not-found]
1 warning generated.
g++ -bundle -undefined dynamic_lookup -L/Users/jensrenders/miniconda3/lib -arch x86_64 -L/Users/jensrenders/miniconda3/lib -arch x86_64 -arch x86_64 build/temp.macosx-10.7-x86_64-3.7/test.o build/temp.macosx-10.7-x86_64-3.7/my_sum.o -o /Users/jensrenders/Dropbox/cython_demo/test.cpython-37m-darwin.so
clang: warning: libstdc++ is deprecated; move to libc++ with a minimum deployment target of OS X 10.9 [-Wdeprecated]
ld: library not found for -lstdc++
clang: error: linker command failed with exit code 1 (use -v to see invocation)
error: command 'g++' failed with exit status 1
I do get a test.cpp file as output but no shared object.
What causes this, and how can it be solved?
Thanks for your help!
EDIT:
As #MaximEgorushkin points out, it is strange that cython tries to compile the C++ files with gcc. I can force it to use g++ by adding
os.environ["CC"] = "g++" to setup.py, but this does not solve the problem:
$ python setup.py build_ext --inplace
running build_ext
building 'test' extension
g++ -Wno-unused-result -Wsign-compare -Wunreachable-code -DNDEBUG -g -fwrapv -O3 -Wall -Wstrict-prototypes -I/Users/jensrenders/miniconda3/include -arch x86_64 -I/Users/jensrenders/miniconda3/include -arch x86_64 -I/Users/jensrenders/miniconda3/include/python3.7m -c test.cpp -o build/temp.macosx-10.7-x86_64-3.7/test.o
warning: include path for stdlibc++ headers not found; pass '-std=libc++' on the command line to use the libc++ standard
library instead [-Wstdlibcxx-not-found]
1 warning generated.
g++ -Wno-unused-result -Wsign-compare -Wunreachable-code -DNDEBUG -g -fwrapv -O3 -Wall -Wstrict-prototypes -I/Users/jensrenders/miniconda3/include -arch x86_64 -I/Users/jensrenders/miniconda3/include -arch x86_64 -I/Users/jensrenders/miniconda3/include/python3.7m -c my_sum.cpp -o build/temp.macosx-10.7-x86_64-3.7/my_sum.o
warning: include path for stdlibc++ headers not found; pass '-std=libc++' on the command line to use the libc++ standard
library instead [-Wstdlibcxx-not-found]
1 warning generated.
g++ -bundle -undefined dynamic_lookup -L/Users/jensrenders/miniconda3/lib -arch x86_64 -L/Users/jensrenders/miniconda3/lib -arch x86_64 -arch x86_64 build/temp.macosx-10.7-x86_64-3.7/test.o build/temp.macosx-10.7-x86_64-3.7/my_sum.o -o /Users/jensrenders/Dropbox/cython_demo/test.cpython-37m-darwin.so
clang: warning: libstdc++ is deprecated; move to libc++ with a minimum deployment target of OS X 10.9 [-Wdeprecated]
ld: library not found for -lstdc++
clang: error: linker command failed with exit code 1 (use -v to see invocation)
error: command 'g++' failed with exit status 1

Here is a similar problem:
https://github.com/pandas-dev/pandas/issues/23424
As they suggest, and as indicated by the line in the output
clang: warning: libstdc++ is deprecated; move to libc++ with a minimum deployment target of OS X 10.9 [-Wdeprecated]
adding extra_link_args=["-stdlib=libc++", "-mmacosx-version-min=10.9"] solves the problem. setup.py then looks like this:
from distutils.core import setup
from distutils.extension import Extension
from Cython.Distutils import build_ext
ext_modules = [Extension("test",
sources=["test.pyx", "my_sum.cpp"],
language="c++",
extra_link_args=["-stdlib=libc++", "-mmacosx-version-min=10.9"])]
setup(cmdclass = {'build_ext': build_ext}, ext_modules = ext_modules)

Command "/usr/bin/clang++ -bundle -undefined..." failed with exit status 1

I'm trying to build a library "cmappertools" referencing to c++ "boost" in os x maverick, and hit the error below. I'm very new to both python and c++ boost, and can't even tell where to start looking: the "Missing compiler_cxx fix for UnixCCompiler" error didn't seem pointing me to anywhere. Any idea, please?
checking for exit in -lboost_thread-mt... yes
checking whether the Boost::Chrono library is available... yes
checking for exit in -lboost_chrono-mt... yes
checking whether C++ compiler accepts -fvisibility=hidden... yes
checking whether C++ compiler accepts -fno-common... yes
checking whether C++ compiler accepts -fvisibility-inlines-hidden... yes
...
building extension "cmappertools" sources
build_src: building npy-pkg config files
running build_ext
customize UnixCCompiler
customize UnixCCompiler using build_ext
customize UnixCCompiler
**#### ['/usr/bin/clang', '-fno-strict-aliasing', '-fno-common', '-dynamic', '-arch', 'i386', '-arch', 'x86_64', '-g', '-DNDEBUG', '-g', '-fwrapv', '-O3', '-Wall', '-Wstrict-prototypes'] #######
Missing compiler_cxx fix for UnixCCompiler**
customize UnixCCompiler using build_ext
building 'cmappertools' extension
compiling C++ sources
C compiler: /usr/bin/clang++ -fno-strict-aliasing -fno-common -dynamic -arch i386 -arch x86_64 -g - DNDEBUG -g -fwrapv -O3 -Wall
compile options: '-I/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site- packages/numpy/core/include -I/Library/Frameworks/Python.framework/Versions/2.7/include/python2.7 -c'
extra options: '-pthread -I/usr/local/include -fvisibility=hidden -fno-common -fvisibility-inlines- hidden -ffunction-sections -fdata-sections'
clang++: cmappertools.cpp
/usr/bin/clang++ -bundle -undefined dynamic_lookup -arch i386 -arch x86_64 -g build/temp.macosx-10.6-intel-2.7/cmappertools.o -o build/lib.macosx-10.6-intel-2.7/cmappertools.so -L/usr/local/lib - lboost_thread-mt -lboost_chrono-mt -Wl,-s
ld: warning: option -s is obsolete and being ignored
ld: warning: ignoring file /usr/local/lib/libboost_thread-mt.dylib, file was built for x86_64 which is not the architecture being linked (i386): /usr/local/lib/libboost_thread-mt.dylib
ld: warning: ignoring file /usr/local/lib/libboost_chrono-mt.dylib, file was built for x86_64 which is not the architecture being linked (i386): /usr/local/lib/libboost_chrono-mt.dylib
ld: internal error: atom not found in symbolIndex(__ZN5boost16exception_detail20copy_boost_exceptionEPNS_9exceptionEPKS1_) for architecture i386
clang: error: linker command failed with exit code 1 (use -v to see invocation)
ld: warning: option -s is obsolete and being ignored
ld: warning: ignoring file /usr/local/lib/libboost_thread-mt.dylib, file was built for x86_64 which is not the architecture being linked (i386): /usr/local/lib/libboost_thread-mt.dylib
ld: warning: ignoring file /usr/local/lib/libboost_chrono-mt.dylib, file was built for x86_64 which is not the architecture being linked (i386): /usr/local/lib/libboost_chrono-mt.dylib
ld: internal error: atom not found in symbolIndex(__ZN5boost16exception_detail20copy_boost_exceptionEPNS_9exceptionEPKS1_) for architecture i386
clang: error: linker command failed with exit code 1 (use -v to see invocation)
error: Command "/usr/bin/clang++ -bundle -undefined dynamic_lookup -arch i386 -arch x86_64 -g build/temp.macosx-10.6-intel-2.7/cmappertools.o -o build/lib.macosx-10.6-intel-2.7/cmappertools.so -L/usr/local/lib -lboost_thread-mt -lboost_chrono-mt -Wl,-s" failed with exit status 1

You need to compile boost in combined 32/64 bit - it's only compiled for 64bit mode.
If you installed boost via brew, you should have added the --universal option to the install command.
If you were manually building boost, you should have added the options:
address-model=32_64 architecture=x86
to the b2 compile line. This will cause it to be built in 32 & 64 bit, which should support your python build.

Rectangle Example, cython [duplicate]

I want to wrap a test project containing C++ and OpenMP code with Cython, and build it with distutils via a setup.py file. The content of my file looks like this:
from distutils.core import setup
from distutils.extension import Extension
from Cython.Build import cythonize
from Cython.Distutils import build_ext
modules = [Extension("Interface",
["Interface.pyx", "Parallel.cpp"],
language = "c++",
extra_compile_args=["-fopenmp"],
extra_link_args=["-fopenmp"])]
for e in modules:
e.cython_directives = {"embedsignature" : True}
setup(name="Interface",
cmdclass={"build_ext": build_ext},
ext_modules=modules)
The -fopenmp flag is used with gcc to compile and link against OpenMP. However, if I just invoke
cls ~/workspace/CythonOpenMP/src $ python3 setup.py build
this flag is not recognized, because the compiler is clang:
running build
running build_ext
skipping 'Interface.cpp' Cython extension (up-to-date)
building 'Interface' extension
cc -Wno-unused-result -fno-common -dynamic -DNDEBUG -g -O3 -Wall -Wstrict-prototypes -I/usr/local/include -I/usr/local/opt/sqlite/include -I/usr/local/Cellar/python3/3.3.0/Frameworks/Python.framework/Versions/3.3/include/python3.3m -c Interface.cpp -o build/temp.macosx-10.8-x86_64-3.3/Interface.o -fopenmp
clang: warning: argument unused during compilation: '-fopenmp'
cc -Wno-unused-result -fno-common -dynamic -DNDEBUG -g -O3 -Wall -Wstrict-prototypes -I/usr/local/include -I/usr/local/opt/sqlite/include -I/usr/local/Cellar/python3/3.3.0/Frameworks/Python.framework/Versions/3.3/include/python3.3m -c Parallel.cpp -o build/temp.macosx-10.8-x86_64-3.3/Parallel.o -fopenmp
clang: warning: argument unused during compilation: '-fopenmp'
Parallel.cpp:24:10: warning: unknown pragma ignored [-Wunknown-pragmas]
#pragma omp parallel for
^
1 warning generated.
c++ -bundle -undefined dynamic_lookup -L/usr/local/lib -L/usr/local/opt/sqlite/lib build/temp.macosx-10.8-x86_64-3.3/Interface.o build/temp.macosx-10.8-x86_64-3.3/Parallel.o -o build/lib.macosx-10.8-x86_64-3.3/Interface.so -fopenmp
ld: library not found for -lgomp
clang: error: linker command failed with exit code 1 (use -v to see invocation)
error: command 'c++' failed with exit status 1
I've unsucessfully tried to specify gcc:
cls ~/workspace/CythonOpenMP/src $ python3 setup.py build --compiler=g++-4.7
running build
running build_ext
error: don't know how to compile C/C++ code on platform 'posix' with 'g++-4.7' compiler
How can I tell distutils to use gcc?

Try setting the "CC" environment variable from inside the setup.py with os.environ.

I just took a look at the distutils source, and the --compiler option expects "unix", "msvc", "cygwin", "mingw32", "bcpp", or "emx". It checks the compiler name you want by checking the CC environment variable. Try calling build like this:
CC=gcc python setup.py build
You don't need to set CXX, it doesn't check for that.

Just in case some others are facing the same problem under Windows (where CC environment variable wouldn't have any effect) :
Create file "C:\Python27\Lib\distutils\distutils.cfg" and write this inside :
Code :
[build]
compiler = mingw32
Remove all instances of "-mno-cygwin" gcc option from file "C:\Python27\Lib\distutils\cygwinccompiler.py" :
This :
self.set_executables(compiler='gcc -mno-cygwin -O -Wall',
compiler_so='gcc -mno-cygwin -mdll -O -Wall',
compiler_cxx='g++ -mno-cygwin -O -Wall',
linker_exe='gcc -mno-cygwin',
linker_so='%s -mno-cygwin %s %s'
% (self.linker_dll, shared_option,
entry_point))
Becomes this :
self.set_executables(compiler='gcc -O -Wall',
compiler_so='gcc -mdll -O -Wall',
compiler_cxx='g++ -O -Wall',
linker_exe='gcc',
linker_so='%s %s %s'
% (self.linker_dll, shared_option,
entry_point))
The second point can be necessary in case you are using a recent version of gcc, where the deprecated option -mno-cygwin has been removed.
Hope this will help even if it is not directly related to the OP real needs (but still related to the question's title...)

According to this wiki, Python versions after 3.4 do not support MinGW anymore.
CPython 3.7 for Windows is compiled with MSC v.1916. When I try to use above-mentioned method with distutils.cfg, I then get an error from distutils: Unknown MS Compiler Version 1916. Looks like it has a hardcoded table of msvcr libraries in its cygwincompiler.py file (which is also responsible for MinGW), and last version known to that file is 1600 from VS2010 / MSVC 10.0.

Try this:
http://mail.python.org/pipermail/distutils-sig/2002-August/002944.html
In short, it appears that you should try: python setup.py build --compiler=g++ first.

On linux while using distutils.ccompiler do
os.environ('CC')='gcc' and then call distutils.sysconfig.customize_compiler(compiler)
It will do the job.

pip install PIL fails on OSX

I'm trying to install PIL on OSX 10.6.8 using pip in virtualenv, but it fails with gcc returning 1 exit status.
here's what i get:
$ pip install PIL
Downloading/unpacking PIL
Running setup.py egg_info for package PIL
WARNING: '' not a valid package name; please use only.-separated package names in setup.py
Installing collected packages: PIL
Running setup.py install for PIL
WARNING: '' not a valid package name; please use only.-separated package names in setup.py
--- using frameworks at /System/Library/Frameworks
building '_imaging' extension
gcc-4.2 -fno-strict-aliasing -fno-common -dynamic -DNDEBUG -g -fwrapv -Os -Wall -Wstrict-prototypes -DENABLE_DTRACE -arch i386 -arch ppc -arch x86_64 -pipe -DHAVE_LIBJPEG -DHAVE_LIBZ -I/System/Library/Frameworks/Tcl.framework/Headers -I/System/Library/Frameworks/Tk.framework/Headers -I/opt/local/include/freetype2 -IlibImaging -I/opt/local/include -I/Users/DataGreed/workspaces/vitrualenv/project/include -I/usr/local/include -I/usr/include -I/System/Library/Frameworks/Python.framework/Versions/2.6/include/python2.6 -c _imaging.c -o build/temp.macosx-10.6-universal-2.6/_imaging.o
_imaging.c:3017: warning: initialization from incompatible pointer type
_imaging.c:3077: warning: initialization from incompatible pointer type
/usr/libexec/gcc/powerpc-apple-darwin10/4.2.1/as: assembler (/usr/bin/../libexec/as/ppc/as or /usr/bin/../local/libexec/as/ppc/as) for architecture ppc not installed
Installed assemblers are:
/usr/bin/../libexec/as/x86_64/as for architecture x86_64
/usr/bin/../libexec/as/i386/as for architecture i386
/usr/bin/../libexec/as/arm/as for architecture arm
_imaging.c:3017: warning: initialization from incompatible pointer type
_imaging.c:3077: warning: initialization from incompatible pointer type
_imaging.c:3281: fatal error: error writing to -: Broken pipe
compilation terminated.
_imaging.c:3017: warning: initialization from incompatible pointer type
_imaging.c:3077: warning: initialization from incompatible pointer type
lipo: can't open input file: /var/folders/sO/sODPLYP7Goy5NCFskrL1dE+++TM/-Tmp-//ccds0vgZ.out (No such file or directory)
error: command 'gcc-4.2' failed with exit status 1
Complete output from command /Users/DataGreed/workspaces/vitrualenv/project/bin/python -c "import setuptools;__file__='/Users/DataGreed/workspaces/vitrualenv/project/build/PIL/setup.py';exec(compile(open(__file__).read().replace('\r\n', '\n'), __file__, 'exec'))" install --record /var/folders/sO/sODPLYP7Goy5NCFskrL1dE+++TM/-Tmp-/pip-BNAuaC-record/install-record.txt --single-version-externally-managed --install-headers /Users/DataGreed/workspaces/vitrualenv/project/bin/../include/site/python2.6:
WARNING: '' not a valid package name; please use only.-separated package names in setup.py
running install
running build
running build_py
running build_ext
--- using frameworks at /System/Library/Frameworks
building '_imaging' extension
gcc-4.2 -fno-strict-aliasing -fno-common -dynamic -DNDEBUG -g -fwrapv -Os -Wall -Wstrict-prototypes -DENABLE_DTRACE -arch i386 -arch ppc -arch x86_64 -pipe -DHAVE_LIBJPEG -DHAVE_LIBZ -I/System/Library/Frameworks/Tcl.framework/Headers -I/System/Library/Frameworks/Tk.framework/Headers -I/opt/local/include/freetype2 -IlibImaging -I/opt/local/include -I/Users/DataGreed/workspaces/vitrualenv/project/include -I/usr/local/include -I/usr/include -I/System/Library/Frameworks/Python.framework/Versions/2.6/include/python2.6 -c _imaging.c -o build/temp.macosx-10.6-universal-2.6/_imaging.o
_imaging.c:3017: warning: initialization from incompatible pointer type
_imaging.c:3077: warning: initialization from incompatible pointer type
/usr/libexec/gcc/powerpc-apple-darwin10/4.2.1/as: assembler (/usr/bin/../libexec/as/ppc/as or /usr/bin/../local/libexec/as/ppc/as) for architecture ppc not installed
Installed assemblers are:
/usr/bin/../libexec/as/x86_64/as for architecture x86_64
/usr/bin/../libexec/as/i386/as for architecture i386
/usr/bin/../libexec/as/arm/as for architecture arm
_imaging.c:3017: warning: initialization from incompatible pointer type
_imaging.c:3077: warning: initialization from incompatible pointer type
_imaging.c:3281: fatal error: error writing to -: Broken pipe
compilation terminated.
_imaging.c:3017: warning: initialization from incompatible pointer type
_imaging.c:3077: warning: initialization from incompatible pointer type
lipo: can't open input file: /var/folders/sO/sODPLYP7Goy5NCFskrL1dE+++TM/-Tmp-//ccds0vgZ.out (No such file or directory)
error: command 'gcc-4.2' failed with exit status 1
UPD: on the other computer with the same osx version it installs flawlessly :-/
UPD2: there is a more strange thing actually. I have PIL already installed via pip outside virtualenv. But I cannot install it in virtualenv only.
UPD3: i dunno if it can help, but when I load virtualenv wrapper scripts, i got this:
/Library/Python/2.6/site-packages/stevedore/extension.py:4: UserWarning: Module
pkg_resources was already imported from /System/Library/Frameworks/Python.framework/Versions/2.6/Extras/lib/python/pkg_resources.pyc, but /Library/Python/2.6/site-packages is being added to sys.path
import pkg_resources
/Library/Python/2.6/site-packages/stevedore/extension.py:4: UserWarning: Module site was already imported from /System/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site.pyc, but /Library/Python/2.6/site-packages is being added to sys.path
import pkg_resources
When I use workon, i get the same warnings.

Have you tried Pillow? (pip install pillow):
http://pypi.python.org/pypi/Pillow/
It makes life with PIL much easier. I was able to install PIL via Pillow on OSX with virtualenv and virtualenvwrapper.

Mine installs fine into a virtualenv on 10.6.8 but...
mine is being built with gcc-4.0 , while yours is being built with 4.2 ; and 4.2 should be the default.
so i don't actually know why mine is being built with gcc-4.0 , but it does work fine.
$ which gcc
/usr/bin/gcc
$ ls -alh /usr/bin/gcc
lrwxr-xr-x 1 root wheel 7B Jan 3 2012 /usr/bin/gcc -> gcc-4.2

Xcode gcc exit status 1

First of all I am very new to all this.
I recently upgraded to Snow Leopard and installed the Xcode + iPhone dev package, 3.1.2.
I went on to install the Django framework + MYSQLDB handler. During the build stage, the terminal shows me the gcc exit status 1 error. But I have the Xcode already installed?
Where am I going wrong?
Also while trying to fix things up, I installed the Xcode that came with the Snow Leopard DVD. still the same error.
Now I think I should remove the Xcode completely and do a fresh install?
Is the ver.3.1.2 specific to 32-bit? Please help me out.
Here is the complete error:
Amit-Vermas-MacBook:mysql-python-1.2.2 amitverma$ gcc-4.0
i686-apple-darwin10-gcc-4.0.1: no input files
Amit-Vermas-MacBook:mysql-python-1.2.2 amitverma$ python setup.py build
running build
running build_py
copying MySQLdb/release.py -> build/lib.macosx-10.3-i386-2.5/MySQLdb
running build_ext
building '_mysql' extension
gcc -isysroot /Developer/SDKs/MacOSX10.4u.sdk -fno-strict-aliasing -Wno-long-double -no-cpp-precomp -mno-fused-madd -fno-common -dynamic -DNDEBUG -g -O3 -Dversion_info=(1,2,2,'final',0) -D__version__=1.2.2 -I/usr/local/mysql/include -I/Library/Frameworks/Python.framework/Versions/2.5/include/python2.5 -c _mysql.c -o build/temp.macosx-10.3-i386-2.5/_mysql.o -g -Os -arch x86_64 -fno-common -D_P1003_1B_VISIBLE -DSIGNAL_WITH_VIO_CLOSE -DSIGNALS_DONT_BREAK_READ -DIGNORE_SIGHUP_SIGQUIT -DDONT_DECLARE_CXA_PURE_VIRTUAL
cc1: error: unrecognized command line option "-Wno-long-double"
error: command 'gcc' failed with exit status 1

I am not sure if you solved your problem. I got the exact same issue after I upgraded from Mac OS 10.4 to 10.6.
Following some blog posts, on a hunch, I ran setup.py pointing to an older gcc version (gcc-4.0).
CC='/usr/bin/gcc-4.0' python setup.py build
The build encountered few warnings.
running build
running build_py
copying MySQLdb/release.py -> build/lib.macosx-10.3-i386-2.5/MySQLdb
running build_ext
building '_mysql' extension
/usr/bin/gcc-4.0 -isysroot /Developer/SDKs/MacOSX10.4u.sdk -fno-strict-aliasing -Wno-long-double -no-cpp-precomp -mno-fused-madd -fno-common -dynamic -DNDEBUG -g -O3 -Dversion_info=(1,2,3,'gamma',1) -D__version__=1.2.3c1 -I/usr/local/mysql/include -I/Library/Frameworks/Python.framework/Versions/2.5/include/python2.5 -c _mysql.c -o build/temp.macosx-10.3-i386-2.5/_mysql.o -g -Os -arch i386 -fno-common -D_P1003_1B_VISIBLE -DSIGNAL_WITH_VIO_CLOSE -DSIGNALS_DONT_BREAK_READ -DIGNORE_SIGHUP_SIGQUIT -DDONT_DECLARE_CXA_PURE_VIRTUAL
In file included from _mysql.c:36:
/usr/local/mysql/include/my_config.h:1050:1: warning: "HAVE_WCSCOLL" redefined
In file included from /Library/Frameworks/Python.framework/Versions/2.5/include/python2.5/Python.h:8,
from pymemcompat.h:10,
from _mysql.c:29:
/Library/Frameworks/Python.framework/Versions/2.5/include/python2.5/pyconfig.h:724:1: warning: this is the location of the previous definition
gcc -arch i386 -arch ppc -isysroot /Developer/SDKs/MacOSX10.4u.sdk -g -bundle -undefined dynamic_lookup build/temp.macosx-10.3-i386-2.5/_mysql.o -L/usr/local/mysql/lib -lmysqlclient_r -lz -lm -lmygcc -o build/lib.macosx-10.3-i386-2.5/_mysql.so
ld: warning: in build/temp.macosx-10.3-i386-2.5/_mysql.o, file is not of required architecture
ld: warning: in /usr/local/mysql/lib/libmysqlclient_r.dylib, file is not of required architecture
ld: warning: in /usr/local/mysql/lib/libmygcc.a, file is not of required architecture
Ran the same command again.
Everything works now magically. The install also went through. The module works as expected.

It normally also shows why a compilation fails. Could you give the text preceding "gcc exited with code 1" or something like that? And perhaps the source file also.
Also look for other threads on this subject, like this one. Good search terms on google or stack overflow are leopard and MySQLdb.

If it helps any, I solved this issue with sym links, and I think it will work for you. I wrote this with my version of gcc in mind, which is 4.2:
cd /usr/bin
rm cc gcc c++ g++
ln -s gcc-4.2 cc
ln -s gcc-4.2 gcc
ln -s c++-4.2 c++
ln -s g++-4.2 g++
ln -s gcc-4.2 gcc-4.0
There ya go!