[cmake-developers] General Config.cmake file issue on ArchLinux

[Andrea Scarpino]

On Saturday 17 November 2012 20:24:42 you wrote:
> Hi,
> 
> maybe I am missing something, but here we go:
> 
> on 64bit ArchLinux installations, /lib64/ is a symlink to /usr/lib/.
> /bin/ and /usr/bin/ are normal directories, no symlinks.

Hi Alexander,
that's true, anyway we'll symlink /bin to /usr/bin in the next year.

> Now if a Config.cmake files is installed into /usr/lib/foo/, and references
> other files of its installations using relative paths from its own location
> to e.g. /usr/bin/ (../../bin/ ), there is breakage.

Note, that this only applies when $PATH contains a different order than the 
default one we ship; which is
PATH="/usr/local/bin:/usr/bin:/bin:/usr/local/sbin:/usr/sbin:/sbin".

In detail, when /bin is before /usr/bin cmake looks for the binary in /bin.

> CMake finds FooConfig.cmake in /lib64/foo/FooConfig.cmake (which it seems to
> search before /usr/lib). Then it goes ../../bin/, but doesn't end up in
> /usr/bin/, where e.g. some executable is located, but instead it goes to
> /lib64/foo/../../bin/, which is /bin/, but the expected executable is not
> there, and so the FooConfig.cmake file fails.

I'm not familiar with the cmake code, but I guess that the different PATH order 
I said above cause cmake to take the FooConfig.cmake file from /lib64 rather 
than /usr/lib.

> If so, maybe the best thing to do is to tell the ArchLinux developers to set
> up their symlinks in a different way ?
> Having e.g. /usr/lib64/ point to /usr/lib/ would make it work I think.
> Or if /lib64/ points to /usr/lib/, then maybe /bin/ should also point to
> /usr/bin/.

We are going to move everything to /usr. As I said above /bin will be 
symlinked to /usr/bin in the next year.

-- 
Andrea
Arch Linux Developer