[CMake] Out-of-source builds

[Bill Hoffman]

Phil Smith wrote:
> It seems that an out-of-source build must be part of the same
directory structure (this is Windows).
> 
> To whit:
> 
> - Source is under c:\svn\Toolkit\IBMport\vtk-core - If I'm in
> c:\svn\Toolkit\IBMport\, I can cmake just fine - If I'm in c:\temp\,
> cmake with fully qualified toolchain and path
(c:\svn\Toolkit\IBMport\) works, but then make fails because some of the
targets have "c:" prefixed and that irritates make
> - If I'm in c:\temp\, cmake withOUT fully qualified toolchain and/or
path fails, trying to (for some reason) append svn\Toolkit\IBMport\ as a
relative path onto c:\temp\, even though the toolchain/path passed has a
leading backslash.
> 
> Is this a bug? Or necessary/deliberate behavior? The last case at
least seems wrong offhand.
> 
> I tinkered with /cygdrive/c/etc. but couldn't get that to work
> either. --

If you want /cygdrive, then use the native cygwin cmake.  If you want 
mixed dos style paths, you have to use the patched gmake.   Cygwin 
removed support for c: in paths.  Next version of gmake will put the 
support back.

You can find a patched make here:

http://www.cmake.org/files/cygwin/make.exe

-Bill