[gentoo-dev] when to use a function and an implementation use flag.

[Peter Hjalmarsson <xake@rymdraket.net>]

I took a look at qemu-kvm and found something I percieve as funny:
It had a gnutls use-flag, but no ssl useflag.

As I see it is I want ssl/tls support it should be sufficient to enable
USE="ssl" and let the maintainer of said ebuild decide which
implementation (if more then one) I am better off with and only care
about the USE="gnutls openssl nss" if i really think the maintainer is
wrong.

For qemu-kvm the problem is that there is only one implementation (i.e.
gnutls), and if I want to have ssl support I have to enable gnutls for
this package.

When I wrote a bug about this I got a rather short reply from maintainer
about pointing me to the policy about this.
Now I know there was a disscussion a while back about this on the
mailinglist, but google fails me to find it, looking into the Gentoo
Development Guide [1] it fails me too.

There is not a _single_ word about how to handle if there is only one
implementation, but two use flags for this (one for the function
provided - ssl - and one for the actual implementation - gnutls).

So I have a question:
Is there no policy about this?
If there is could someone please point me towards it and also it in that
case may be time to update the gentoo development guide.

[1]
http://devmanual.gentoo.org/general-concepts/use-flags/index.html#conflicting-use-flags