[CMake] relocatable build directory: howto?

[Clinton Stimpson]

On May 5, 2012, at 5:52 AM, Dave Abrahams wrote:

> 
> on Sat May 05 2012, Michael Wild <themiwi-Re5JQEeQqe8AvxtiuMwx3w-AT-public.gmane.org> wrote:
> 
>> On 05/05/2012 07:25 AM, Dave Abrahams wrote:
>>> 
>>> I need to preserve the built-but-not-yet-installed state of some
>>> projects, and the tool I'm driving CMake with moves the result of every
>>> build step from a read-write build directory into a readonly cache.  The
>>> result is that the generated cmake_install.cmake files no longer work,
>> 
>>> because they are full of absolute paths.  I wrote a simple program to
>>> adjust the paths in the cmake_install.cmake files as a postprocessing
>>> step, replacing $CWD, where it is found, with a cmake variable.  The
>>> only problem: on my Mac, /tmp is a symlink to /private/tmp, and in some
>>> scenarios the absolute path in cmake_install.cmake is the short one
>>> wheras while $CWD is the long one.  No match :(
>>> 
>>> I started to write some code to address this problem, but it's getting
>>> complex to the point where it seems like "there must be a better way."
>>> So I ask: is there?
>>> 
>>> Thanks in advance,
>>> 
>> 
>> I'm afraid that the answer is no. There is the variable
>> CMAKE_USE_RELATIVE_PATHS, but that is broken and does not work in
>> general. Just out of curiosity: Why do you need to cache the build tree
>> in the first place? 
> 
> I'm driving CMake with a package installation system (0install) that
> doesn't allow for subpackages (it may someday, but that's not supported
> as of now).  This system installs packages into a cache.  It's
> undesirable to have to build a cmake package twice just to produce its
> -dev (on windows, includes import libraries) and -bin (includes
> DLLs/so's) incarnations.  The way we deal with that now is to make the
> preinstall (built) state a separate 0install package and let 0install
> put that in the cache, then come back later and install from that
> package.
> 
> Which reminds me; it would be awesome if there were a way to get cmake
> to clean everything but the leaves in its dependency graph.  IOW, I'd
> like to throw out all the .o files after having built libraries.  Is
> there a way?
> 
>> Would it be enough to "make install DESTDIR=/path/to/cache"?
> 
> Only if I want to build twice.
> 


In case its applicable, I just thought I'd mention that you can run "cmake -P cmake_install.cmake .... " if you want to customize the installation of the files, even putting the -dev files in one place and the -bin in another, then run you own packaging tool on those directories afterwards.

Maybe you could cache those directories instead of the build tree, or was there something else you still needed from the build tree?

Clint