Building Mesa for windows 7. Mesa 9.1

I went through all the steps on the compiling / installing page on Mesa's site, and read the FAQ. The final command that you send to scons for compilation throws errors within python scripts. This is my output. What am I doing wrong? Also if anyone has compiled dll's for mesa using up to date mesa and mingw, or VS2012, then please share!

Here is my output, I haven't programmed python in a long time but it appears a map/dictionary doesn't contain the key/value pair.

C:\Downloads\MesaLib-9.1.5\Mesa-9.1.5>scons platform=windows toolchain=crossming
w machine=x86_64 mesagdi libgl-gdi

scons: Reading SConscript files ...
KeyError: 'CCVERSION':
  File "C:\Downloads\MesaLib-9.1.5\Mesa-9.1.5\SConstruct", line 40:
    ENV = os.environ,
  File "C:\Python27\scons-2.3.0\SCons\Environment.py", line 1002:
    apply_tools(self, tools, toolpath)
  File "C:\Python27\scons-2.3.0\SCons\Environment.py", line 106:
    env.Tool(tool)
  File "C:\Python27\scons-2.3.0\SCons\Environment.py", line 1786:
    tool(self)
  File "C:\Python27\scons-2.3.0\SCons\Tool\__init__.py", line 183:
    self.generate(env, *args, **kw)
  File "C:\Downloads\MesaLib-9.1.5\Mesa-9.1.5\scons\gallium.py", line 313:
    ccversion = env['CCVERSION']
  File "C:\Python27\scons-2.3.0\SCons\Environment.py", line 412:
    return self._dict[key]

Common scons options:

build=release
machine=x86
platform=windows
libgl-gdi

1. Linux (Debian Wheezy), toolchain=crossmingw: Fails during linking phase because it can't find __vscprintf, among other things. Works as of Debian Jessie 8.5 & Mesa d2f42a945ec0fbcc51b59cfd329258bd62ebf0d2 via:

   scons \
   toolchain=crossmingw \
   build=release \
   machine=x86 \
   platform=windows \
   libgl-gdi
   

   DLL is installed to build/windows-x86/gallium/targets/libgl-gdi/opengl32.dll

2. Windows, toolchain=mingw: Fails with "The command line is too long." despite multiple permutations of both snippits on LongCmdLinesOnWin32.

3. Windows, VS2012 Express, MSVC_VERSION=11.0: Succeeds after removing stray C99-isms from src/glsl/ralloc.c::ralloc_size().

EDIT: More complete procedure:

1. Install Visual Studio Express 2012 for Windows Desktop:

   http://www.microsoft.com/visualstudio/eng/downloads#d-express-windows-desktop
   

2. Install MinGW:

   http://www.mingw.org/
   http://sourceforge.net/projects/mingw/files/
   http://sourceforge.net/projects/mingw/files/latest/download?source=files
   mingw-get-inst-20120426.exe
   
   Run installer:
   Download latest repo catalogs
   Install to C:\MinGW (default)
   Check:
   * C compiler
   * C++ compiler
   * MSYS basic system
   * MinGW developer toolkit (should install msys-flex and msys-bison)
   

3. Install Python 2.7:

   http://www.python.org/download/
   http://www.python.org/ftp/python/2.7.5/python-2.7.5.msi
   
   You have to use 32-bit Python because the Scons people only distribute 32-bit installers.
   
   Install for all users (default)
   Install to C:\Python27 (default)
   Use default install options/customizations
   

4. Install libxml2 for Python:

   http://www.lfd.uci.edu/~gohlke/pythonlibs/
   libxml2-python-2.9.1.win32-py2.7.‌exe
   
   Installer should find the python install automagically
   

5. Install pywin32:

   http://pywin32.sourceforge.net/
   http://sourceforge.net/projects/pywin32/files/pywin32/
   http://sourceforge.net/projects/pywin32/files/pywin32/Build%20218/
   http://sourceforge.net/projects/pywin32/files/pywin32/Build%20218/pywin32-218.win32-py2.7.exe
   
   Installer should find the Python install automagically
   

6. Install Scons:

   http://www.scons.org/
   http://prdownloads.sourceforge.net/scons/scons-2.3.0-setup.exe
   
   Installer should find the Python install automagically
   

7. Add these near the top of your PATH:

   C:\Python27\
   C:\Python27\Scripts
   

8. Download Mesa:

   ftp://ftp.freedesktop.org/pub/mesa/
   ftp://ftp.freedesktop.org/pub/mesa/9.1.5/MesaLib-9.1.5.zip
   
   Extract somewhere (C:\Mesa-9.1.5)
   

9. Start MSYS shell:

   C:\mingw\msys\1.0\msys.bat
   
   Change into mesa src directory:
   cd /c/Mesa-9.1.5/
   

10. Build Mesa:

    scons.py \
    build=release \
    machine=x86 \
    platform=windows \
    MSVC_VERSION=11.0 \
    libgl-gdi \
    

This should create an opengl32.dll in build\windows-x86\gallium\targets\libgl-gdi.

With a little bit more legwork it's possible to build llvmpipe.