CMake can't find spglib on Ubuntu/Debian

[oschuett]

When building with -DCP2K_USE_SPGLIB=ON on Ubuntu 2024.04, I get the following error message:

CMake Error at CMakeLists.txt:686 (find_package):
  Could not find a package configuration file provided by "Spglib" with any
  of the following names:

    SpglibConfig.cmake
    spglib-config.cmake

  Add the installation prefix of "Spglib" to CMAKE_PREFIX_PATH or set
  "Spglib_DIR" to a directory containing one of the above files.  If "Spglib"
  provides a separate development package or SDK, be sure it has been
  installed.

It turns out that the libspglib-f08-dev package ships cmake files with somewhat different names:

/usr/lib/x86_64-linux-gnu/cmake/Spglib/SpglibTargets_fortran-none.cmake
/usr/lib/x86_64-linux-gnu/cmake/Spglib/SpglibTargets_fortran.cmake

@mtaillefumier what do you think?

[mtaillefumier]

We should not do anything at all except be sure that Spglib::fortran is added to the cp2k libraries dependencies.

https://github.com/cp2k/cp2k/blob/c5411e048c1d97964d822cc470060c619c47960d/src/CMakeLists.txt#L1560C5-L1560C49

we need to add Spglib::fortran to this line. I can do it if you want.

[mtaillefumier]

Basically, cmake will take care of this all by itself unless the devs decided otherwise. it might be a module to be searched with find_package(Spglib required fortran)

[mtaillefumier]

The error is really ubuntu specific actually. /usr/lib/x86_64-linux-gnu/cmake should be added to CMAKE_PREFIX_PATH

[oschuett]

we need to add Spglib::fortran to this line. I can do it if you want.

Yes, it would be great if you could help out with these find_package issues. Then I'll focus on migrating the remaining CI scripts.