I'll not mark this change as not functional, but please note that elk is strict about the supported libxc version, and it may not support multiple libxc versions https://sourceforge.net/p/elk/discussion/897822/thread/1c1e07d855/

I see libxc tests fail during the build https://koji.fedoraproject.org/koji/search?terms=elk-9.2.12-4.fc42&type=build&match=exact but this does not fail the build. This behavior (some tests fail, but the build is marked as successful) is expected in all packages I maintain. The reason is that often some tests fail, and failing the build on failed tests would probably never allow to release a package. Therefore, a manual inspection of the build.log from a koji scratch build is needed, and direct pushes to the rawhide branch are not that good.

cd tests-libxc; ../tests/test-mpi.sh
Running test in directory test_001...
 Failed! See test.log and output files
+---------------------------------+
| Elk code version 9.2.12 started |
+---------------------------------+
Number of MPI processes :      2
Number of OpenMP threads per MPI process :    2
Total number of threads (MPI x OpenMP) :      4
Maximum OpenMP nesting level :    4
Number of OpenMP threads at first nesting level :    2
Number of MKL threads :    2
RAM disk enabled
+-----------------------+
| Current task :      0 |
+-----------------------+
Error(libxcifc): incompatible Libxc version : 07.000.000
Error(libxcifc): incompatible Libxc version : 07.000.000
...

ELK depending on libxc 6 has nothing to do with Libxc itself. Libxc 7 is fully API compatible with libxc 6.

I did notice the hard version check in the elk source code(!!!!!!) which I thought I had amended to also allow libxc version 7. Elk patch amended.

Looks like the side tag is no longer accessible to run the elk rebuild; I guess one must wait for these builds to hit rawhide to run the elk rebuild. It is should enough to relax the explicit version check.

I would contribute the patch upstream myself if they had an online repository...

thanks @marcindulak for pointing out the incomplete patch!

The issue was fixed in elk-9.2.12-5.fc42

cd tests-libxc; ../tests/test-mpi.sh
Running test in directory test_001...
 Passed
Running test in directory test_002...
 Passed
Running test in directory test_003...
 Passed
Running test in directory test_004...
 Passed
Running test in directory test_005...
 Passed
Running test in directory test_006...
 Passed
1040.69user 5.89system 8:59.87elapsed 193%CPU (0avgtext+0avgdata 237660maxresident)k
16inputs+269152outputs (0major+427642minor)pagefaults 0swaps

Here is a request to elk to support e.g. last two major libxc versions https://sourceforge.net/p/elk/discussion/897822/thread/765df893ad/, and to support fortran 2003 interface https://sourceforge.net/p/elk/discussion/897822/thread/9fe1485f0d/