python pip package install fails , dllwrap error after 'fixing': “unable to find vcvarsall.bat”

Question

I can\'t find this in the archives. Is there something not right with mingw/msys? [I need to get vcvarsall.bat fixed, so I can install other packages.]

Failure to in

Answer 1

The question: why does dllwrap give this error within pip?

_foo.exp: file not recognized: File format not recognized

Short answer: check your PATH. MinGW\bin needs to be near the start of it.

Long answer: For a while I was using a work around. I grabbed the dllwrap command from the pip.log and executed it directly. That built the .pyd and enabled pip install to finish off the job.

I passed the --verbose flag into these two different ways of calling dllwrap. Under pip this was being done.

dlltool: Opened temporary file: dumlc.s
dlltool: run: as   -o _bcrypt.exp dumlc.s
dlltool: Generated exports file

Calling dllwrap from the command line gave this.

C:\MinGW\bin\dlltool: Opened temporary file: demmc.s
C:\MinGW\bin\dlltool: run: C:\MinGW\bin\as   -o _bcrypt.exp demmc.s
C:\MinGW\bin\dlltool: Generated exports file

My computer is running Windows 7 64-bit but with 32-bit Python 2.7. It is new but seems to have the AMD APP SDK pre-installed. That has an as.exe which defaults to 64-bit output.

My fix was to edit the PATH so that C:\MinGW\bin is ahead of C:\Program Files (x86)\AMD APP\bin\x86_64

This problem could be fixed more robustly in the Python code though I have not pinned down where in virtualenv, pip or distutils that should be done.

There are two other things needed to build extensions using MinGW which I'll repeat here briefly.

Configure distutils to use the MinGW compiler

This can be done in a variety of files or command line switches. I opted for a file in my home directory.

$ cat ~/pydistutils.cfg
[build]
compiler = mingw32

Patch distutils to eliminate the -mno-cygwin switch

As admininistrator edit Lib/distutils/cygwinccompiler.py. Delete the four -mno-cygwin options.

s/ -mno-cygwin//

-mno-cygwin has been deprecated in gcc for a while and is now an error.

See http://bugs.python.org/issue12641

Answer 2

This is likely a bug with Python. See http://bugs.python.org/issue2698

Meanwhile, you could install ActivePython and install Twisted via PyPM (no compilers needed).

Alternatively, you can use the official binary ... though I recommend the aforementioned solution as you can easily 'upgrade' to newer versions of Twisted in future.

Answer 3

On Windows, I have installed Visual Studio 2008 (vcsetup.exe) to go around this problem.

updated link: http://www.microsoft.com/en-us/download/details.aspx?id=15336

If using Python 3.3 you can use Visual Studio 2010