Bug#784767: libeigen3-dev: Transition to cmake 3.2

[Felix Geyer]

Package: libeigen3-dev
Version: 3.2.4-2
User: cmake at packages.debian.org
Usertags: cmake-3.2

Dear maintainer(s),

I plan to upload cmake 3.2 to unstable soon.

Your package provides a find module in /usr/share/cmake-3.0.
cmake 3.2 will not look for modules in that path anymore.

Find modules work by guessing the location of libraries and include
files.
Libraries shouldn't ship find modules at all since they know where
the library has been installed to.

There are a couple of solutions:

1) Ship a config-file package instead. [1]
   cmake looks for these packages in an unversioned path:
   <prefix>/(lib/<arch>|lib|share)/cmake/<name>*/
   and a couple of others [2]

2) Push the find module upstream. [4]
   Upstream is usually very responsive.
   Once it has been accepted upstream I can cherry-pick it in the
   cmake package.

3) cmake supports reading pkg-config files. [3]
   This needs changes in the reverse-dependencies though.

As a short term solution you can provide the find module in
/usr/share/cmake-3.2 as well as /usr/share/cmake-3.0.
This is only a temporary workaround though.

Cheers,
Felix

[1] http://www.cmake.org/cmake/help/v3.2/manual/cmake-packages.7.html#config-file-packages
[2] http://www.cmake.org/cmake/help/v3.2/command/find_package.html
[3] http://www.cmake.org/cmake/help/v3.2/module/FindPkgConfig.html
[4] http://www.cmake.org/Bug/