Python在OS X上使用错误版本的GCC构建

Question

我正在尝试构建一个叫做pycrypto的python包。我的Mac上安装的是gcc-4.2，而不是gcc-4.0，但python还是一直试图使用gcc-4.0。我该怎么才能让它使用gcc-4.2呢？或者我应该换个方法来做这件事。

我遇到了以下错误：

bash-3.2$ 
bash-3.2$ sudo python setup.py build
running build
running build_py
running build_ext
warning: GMP library not found; Not building Crypto.PublicKey._fastmath.
building 'Crypto.Hash.MD2' extension
gcc-4.0 -fno-strict-aliasing -fno-common -dynamic -arch ppc -arch i386 -std=c99 -O3 -fomit-frame-pointer -Isrc/ -I/Library/Frameworks/Python.framework/Versions/2.6/include/python2.6 -c src/MD2.c -o build/temp.macosx-10.3-fat-2.6/src/MD2.o
unable to execute gcc-4.0: No such file or directory
error: command 'gcc-4.0' failed with exit status 1
bash-3.2$ 
bash-3.2$ 
bash-3.2$ 

我使用的是Mac OS X 10.6.7，python版本是2.6.6，并且已经安装了XCode。

补充说明：如果我加上CC=gcc-4.2，仍然会出现错误：

bash-3.2$ 
bash-3.2$ export CC=gcc-4.2
bash-3.2$ python setup.py build
running build
running build_py
running build_ext
warning: GMP library not found; Not building Crypto.PublicKey._fastmath.
building 'Crypto.Hash.MD2' extension
gcc-4.2 -fno-strict-aliasing -fno-common -dynamic -std=c99 -O3 -fomit-frame-pointer -arch i386 -arch x86_64 -Isrc/ -I/Library/Frameworks/Python.framework/Versions/2.6/include/python2.6 -c src/MD2.c -o build/temp.macosx-10.3-intel-2.6/src/MD2.o
gcc-4.0 -g -bundle -undefined dynamic_lookup -arch i386 -arch x86_64 build/temp.macosx-10.3-intel-2.6/src/MD2.o -o build/lib.macosx-10.3-intel-2.6/Crypto/Hash/MD2.so
unable to execute gcc-4.0: No such file or directory
error: command 'gcc-4.0' failed with exit status 1
bash-3.2$ 

补充说明：看起来使用sudo会有所不同。

我尝试按照Adam的建议同时使用CC和CXX，但在没有sudo的情况下，我得到了以下错误：

bash-3.2$ python setup.py build
running build
running build_py
creating build/lib.macosx-10.3-fat-2.6
creating build/lib.macosx-10.3-fat-2.6/Crypto
copying lib/Crypto/__init__.py -> build/lib.macosx-10.3-fat-2.6/Crypto
copying lib/Crypto/pct_warnings.py -> build/lib.macosx-10.3-fat-2.6/Crypto
...
warning: GMP library not found; Not building Crypto.PublicKey._fastmath.
building 'Crypto.Hash.MD2' extension
creating build/temp.macosx-10.3-fat-2.6
creating build/temp.macosx-10.3-fat-2.6/src
gcc-4.2 -fno-strict-aliasing -fno-common -dynamic -arch ppc -arch i386 -std=c99 -O3 -fomit-frame-pointer -Isrc/ -I/Library/Frameworks/Python.framework/Versions/2.6/include/python2.6 -c src/MD2.c -o build/temp.macosx-10.3-fat-2.6/src/MD2.o
/usr/libexec/gcc/powerpc-apple-darwin10/4.2.1/as: assembler (/usr/bin/../libexec/gcc/darwin/ppc/as or /usr/bin/../local/libexec/gcc/darwin/ppc/as) for architecture ppc not installed
Installed assemblers are:
/usr/bin/../libexec/gcc/darwin/x86_64/as for architecture x86_64
/usr/bin/../libexec/gcc/darwin/i386/as for architecture i386
lipo: can't open input file: /var/tmp//ccxan625.out (No such file or directory)
error: command 'gcc-4.2' failed with exit status 1

如果我使用sudo，就会出现以下错误，它试图使用4.0：

bash-3.2$ sudo python setup.py build
Password:
running build
running build_py
running build_ext
warning: GMP library not found; Not building Crypto.PublicKey._fastmath.
building 'Crypto.Hash.MD2' extension
gcc-4.0 -fno-strict-aliasing -fno-common -dynamic -arch ppc -arch i386 -std=c99 -O3 -fomit-frame-pointer -Isrc/ -I/Library/Frameworks/Python.framework/Versions/2.6/include/python2.6 -c src/MD2.c -o build/temp.macosx-10.3-fat-2.6/src/MD2.o
unable to execute gcc-4.0: No such file or directory
error: command 'gcc-4.0' failed with exit status 1
bash-3.2$ 
bash-3.2$ 

这些额外的信息是否让问题变得更清楚了？有没有人知道为什么在没有sudo的情况下会出现那个错误？

Answer 1

关注这个错误：

unable to execute gcc-4.0: No such file or directory
error: command 'gcc-4.0' failed with exit status 1

编译器已经明确告诉你问题出在哪里了。gcc-4.0（还有gcc-4.2）不在你的PATH里。提示一下：可以用which gcc-4.2来查找，比如：

% which gcc-4.2
/usr/bin/gcc-4.2

假设你的文件在同样的位置，我不太明白为什么/usr/bin不在你的PATH里，但事实就是这样！

找出你的PATH到底是什么：

% echo $PATH
/opt/local/bin:/bin:/usr/bin:/sbin:/usr/sbin:/usr/bin/X11:/sw/bin:/sw/sbin

修正你的路径，你就能走向更高的境界了。

Answer 2

顺便说一下，这是一个distutils的问题，Python本身并不会编译任何东西。

正如你发现的，你可以用CC这个环境变量来替换编译器。你也可以用CXX这个环境变量来替换链接器。我也想知道为什么distutils会这样，但事实就是如此。

Answer 3

根据你提供的路径（/Library/Frameworks/Python.framework/Versions/2.6），看起来你安装的是一个只能在32位系统上运行的Python 2.6，可能是通过python.org的安装程序安装的。当你构建一个包含C扩展模块的Python包时，这个Python版本自带的Distutils会尝试使用与这个Python版本相同的gcc版本和CPU架构。显然，你安装了新的Xcode 4，但它不再包含gcc-4.0或对ppc的支持。你正在使用的Python版本是用Mac OS X 10.6自带的Xcode 3工具构建的。你可能可以通过以下方法来解决这个问题：

export CC=gcc-4.2
python setup.py build
sudo python setup.py install

编辑：

看起来这个方法对pycrypto不太管用，因为它的构建过程太复杂。如果你不介意使用OS X 10.6自带的Apple版本的Python 2.6，这个方法应该可以用：

export ARCHFLAGS='-arch i386 -arch x86_64'
/usr/bin/python2.6 setup.py build

另一个选择是安装来自python.org的64位/32位 Python 2.7安装程序。这个版本是用gcc-4.2构建的，只支持Intel架构，所以在使用Xcode 4时应该不会出现问题。

更新：

以下是我在Xcode 3中使用的具体步骤。这些步骤在安装了Xcode 4的情况下也应该有效：

$ mkdir p
$ cd p
$ curl -O http://ftp.dlitz.net/pub/dlitz/crypto/pycrypto/pycrypto-2.3.tar.gz
$ tar xf pycrypto-2.3.tar.gz 
$ cd pycrypto-2.3/
$ export ARCHFLAGS='-arch i386 -arch x86_64'
$ /usr/bin/python2.6 setup.py build
running build
running build_py
creating build
creating build/lib.macosx-10.6-universal-2.6
creating build/lib.macosx-10.6-universal-2.6/Crypto
copying lib/Crypto/__init__.py -> build/lib.macosx-10.6-universal-2.6/Crypto
[...]
running build_ext
warning: GMP library not found; Not building Crypto.PublicKey._fastmath.
building 'Crypto.Hash.MD2' extension
creating build/temp.macosx-10.6-universal-2.6
creating build/temp.macosx-10.6-universal-2.6/src
gcc-4.2 -fno-strict-aliasing -fno-common -dynamic -fwrapv -Wall -Wstrict-prototypes -DENABLE_DTRACE -pipe -std=c99 -O3 -fomit-frame-pointer -arch i386 -arch x86_64 -Isrc/ -I/System/Library/Frameworks/Python.framework/Versions/2.6/include/python2.6 -c src/MD2.c -o build/temp.macosx-10.6-universal-2.6/src/MD2.o
gcc-4.2 -Wl,-F. -bundle -undefined dynamic_lookup -arch i386 -arch x86_64 build/temp.macosx-10.6-universal-2.6/src/MD2.o -o build/lib.macosx-10.6-universal-2.6/Crypto/Hash/MD2.so
[...]
building 'Crypto.Util._counter' extension
gcc-4.2 -fno-strict-aliasing -fno-common -dynamic -fwrapv -Wall -Wstrict-prototypes -DENABLE_DTRACE -pipe -std=c99 -O3 -fomit-frame-pointer -arch i386 -arch x86_64 -Isrc/ -I/System/Library/Frameworks/Python.framework/Versions/2.6/include/python2.6 -c src/_counter.c -o build/temp.macosx-10.6-universal-2.6/src/_counter.o
gcc-4.2 -Wl,-F. -bundle -undefined dynamic_lookup -arch i386 -arch x86_64 build/temp.macosx-10.6-universal-2.6/src/_counter.o -o build/lib.macosx-10.6-universal-2.6/Crypto/Util/_counter.so
$ /usr/bin/python2.6 setup.py install
running install
running build
running build_py
running build_ext
warning: GMP library not found; Not building Crypto.PublicKey._fastmath.
running install_lib
creating /Library/Python/2.6/site-packages/Crypto
[...]
byte-compiling /Library/Python/2.6/site-packages/Crypto/pct_warnings.py to pct_warnings.pyc
running install_egg_info
Writing /Library/Python/2.6/site-packages/pycrypto-2.3-py2.6.egg-info
$ /usr/bin/python2.6 setup.py test
running test
............................................................................................[...]
----------------------------------------------------------------------
Ran 902 tests in 42.612s

OK
$ cd 
$ /usr/bin/python2.6
Python 2.6.1 (r261:67515, Jun 24 2010, 21:47:49) 
[GCC 4.2.1 (Apple Inc. build 5646)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> from Crypto.Hash import MD5
>>> m = MD5.new()
>>> m.update('abc')
>>> m.digest()
'\x90\x01P\x98<\xd2O\xb0\xd6\x96?}(\xe1\x7fr'
>>> m.hexdigest()
'900150983cd24fb0d6963f7d28e17f72'
>>> ^D