Since the base package doesn't require the current version of xxhash-libs, xxhsum and libxxhash may be out of sync, e.g. xxhsum 0.7.0 uses libxxhash 0.6.5. It's not a big problem but maybe you could consider adding "Requires: %{name}-libs = %{version}-%{release}" to the base package.

When calling xxhsum without parameters, it shows the message "Wrong parameters" together with short usage information. According to this info, xxhsum should read data from stdin if no filename or "-" is provided instead of quitting.

The binaries do not link to the shared library, so there is no dependency between the packages.

$ ldd /usr/bin/xxhsum 
    linux-vdso.so.1 (0x00007ffc461f8000)
    libc.so.6 => /lib64/libc.so.6 (0x00007f49c9746000)
    /lib64/ld-linux-x86-64.so.2 (0x00007f49c9956000)

The binaries read from stdin when there is a pipe or redirection:

echo 'xxx' | xxhsum
xxhsum < filename

If stdin is a tty it considers this "Wrong parameters".

OK, thanks for the info and sorry for the noise. So, libxxhash is statically linked to xxhsum. Not sure if this should be changed. I thought, xxhsum works similar to md5sum or sha256sum which wait for input when they're called without filename.