media-gfx/darktable builds fine but checking runtime libraries shows a plethora of errors of type: libdarktable.so => not found If the appropriate configuration is done in /etc/ld.so.conf.d, containing the path to /usr/lib*/darktable, the errors are gone.
Thank you for bringing this to our attention! That said, the "nor found" message is not really an error - all the libraries installed in subdirectories of /usr/lib64/darktable/ are loaded by Darktable at run time and thus have all the libdarktable symbols available when loaded. Of course that also means they probably do not actually have to be linked against libdarktable.so - but in the end this is a cosmetic thing. As for the location of libdarktable.so itself, I agree that it is a bit odd - but seeing as on the one hand the current set-up does allow Darktable executables to find this library, and on the other libdarktable.so is very much not instrumented as a full-fledged shared library (e.g. no SONAME), I would very much hesitate to change anything here on the Gentoo end. All in all, I would suggest reporting this upstream.