Re: CMAKE_LIBRARY_PATH & co.

["Lluís Batlle i Rossell" <viric@viric.name>]

On Mon, Oct 14, 2013 at 09:15:25AM +0200, Ludovic Courtès wrote:
> Andreas Enge <andreas@enge.fr> skribis:
> 
> > commit e78fd4ca636a19bc286747f8d91bda22cd8f08fd
> > Author: Andreas Enge <andreas@enge.fr>
> > Date:   Sun Oct 13 18:02:49 2013 +0200
> >
> >     guix: Make cmake build system aware of usual paths.
> >     
> >     *  guix/build/cmake-build-system.scm (configure): Set CMAKE_LIBRARY_PATH to
> >          LIBRARY_PATH and CMAKE_INCLUDE_PATH to CPATH.
> 
> I think this was discussed on IRC yesterday, but I’m not sure I got it:
> are these needed because CMake explicitly looks for files in these
> directories instead of just running the compiler?
> 
> That would be a serious flaw of CMake.

Right; for what I understand, FIND_LIBRARY, and FIND_PATH, look for files in
specific directories. Then cmake takes a decision based in what it finds. A
shared object, a static lib, ...

For header files, you can do:
FIND_PATH(HEADERS file.h)  # Finds the directory having that file
INCLUDE_DIRECTORIES(${HEADERS})  # Adds the respective -I flag in compilation

It may be related to cmake being able to tune very narrowly the -I/-L flags per
project target.

I'm not that anti-cmake; I find the approach of "look for files" quite easy to
understand. :)