The libclamav USE flag doesn't bring in clamav as a dependency, but it should. Also, the use flag should be 'clamav' for consistency with other packages.
fixed in 3.0.14a-r3
Some clarification requested please: According to the document pointed to in the ebuild: http://www.gentoo.org/doc/en/quick-samba-howto.xml the "libclamav" USE flag means " Use the ClamAV library instead of the clamd daemon" and apparently it is the "oav" USE flag that allows one to use either clamd or libclamav (as well as other av products). Basically one can use clamd through Samba's VFS without specifying either the "clamav" or "libclamav" USE flags, but clamav would need to be installed. My confusion is that it appears that if one is planning to run the clamd daemon then compiling Samba to use libclamav is not what is needed (as Samba will use the running clamd daemon instead) and therefore the USE flag should probably not change from "libclamav" to "clamav", as the global flag may actually cause improper results.
chris: yes, the flag that needs to be changed is 'oav' -> 'clamav', not 'libclamav', which is indeed a direct way to use the libraries. The dependency request is anyway correct: both oav/clamav and libclamav require the openantivirus package. I can't fix it until tomorrow, so please be patient.
Except that "oav" can be used without ClamAV, it works to allow the use of a number of different AV products with Samba's VFS. So "oav" really needs to stay put and it shouldn't cause a ClamAV dependency. There's no simple way, that I see at the moment, to handle it. One could add a "clamd" flag, that implies "oav" yet it's quite convoluted, and if they ever switch AV products and remove the "clamd" flag, then oav will not compiled next time around. Maybe sometimes a user just has to RTFM and know what they are doing.
there are too many anti-virus USE flags in effect as it is. That's what I'm really mentioning here. There's oav, clamav, and libclamav in use. AFAICT, clamav, and libclamav do the same thing for 2 different packages.
I think I would agree with Chris -- users should read the manual. Having said that, it would be a good thing if Gentoo's Samba guide was up to date on the various anti-virus options.