[CMake] cmake 32/64 bit

[Brad King]

On Mon, Apr 23, 2012 at 4:45 AM, Jörg F. Unger
<joergfunger at googlemail.com> wrote:
> Hi everyone,
> I'm using windows 7 (64). I'm trying to determine the python installation
> using cmake.
> The problem is that cmake only exists as a 32 bit application. As a
> consequence, it has only access to the 32 bit registry entries (WOW64). I
> have installed python as a 64 bit application, which is not listed in the 32
> bit registry.
>
> By accessing
> HKEY_LOCAL_MACHINE\\SOFTWARE\\Python\\PythonCore\\${_CURRENT_VERSION}\\InstallPath
>
> in the FinPythonLibs.cmake as the path, the 32 bit cmake does not find a
> python installation. Unfortunately, there is also no possibility to set the
> variables (PYTHON_LIBRARY PYTHON_INCUDE_DIR) manually. If I manually add in
> the 32 bit registry the 64 bit application (python), everything works,
> though this is just something I did to locate the problem, not a permanent
> solution.
>
> Any ideas how to circumvent these problems? Or is there a way to build a 64
> bit cmake?

At the point when you call find_package(PythonLibs) make sure you have
at least one language enabled.  That way CMake knows the address size
of the toolchain's target format.  That is important when searching so
CMake knows which registry view to use:

  http://cmake.org/gitweb?p=cmake.git;a=blob;f=Source/cmFindCommon.cxx;hb=v2.8.8#l381

Note that the PlatformIs64Bit test is here:

  http://cmake.org/gitweb?p=cmake.git;a=blob;f=Source/cmMakefile.cxx;hb=v2.8.8#l2195

-Brad