This is not an official proposal. I repeat, this is not an official proposal. It’s just an idea I had and which I should propose officially one day on gentoo-dev, but as I’m not subscribed right now and I didn’t want to yet, I’ll wait for another day to do that.
I already ranted about the fact that the dependency tree of our ebuilds is vastly incomplete, as many lack dependency on zlib; trying to get this fixed was impossible, as Donnie and other insisted that as zlib was in system, we shouldn’t depend on it at all. I disagree, and I would like to know why we can’t depend on a system package, but whatever.
Anyway, as having a complete dependency tree is almost impossible because of that, I have an alternative proposal: reducing the size of the system package set.
Right now system contains stuff like ncurses, readline, zlib, autoconf, automake and m4, perl, gnuconfig, and so on. Those are packages that certainly would be part of any base Gentoo system, but are those actual part of the system set of packages? I sincerely doubt it.
The reason of the existence of the system package set is related first and foremost to breaking circular dependencies: for instance if any package that used the C compiler would depend on gcc, then the packages that gcc depends upon would create a circular dependency between gcc and itself. Also, specifying libc in almost any ebuild would be quite pointless, as well as coreutils (or freebsd-bin/ubin) for cp, mv, install, …
But why autoconf and automake? Well the easy answer is that those are often used without making sure they are depended upon explicitly… or at least this was the case till me and Martin added autotools.eclass to the tree; nowadays all the ebuilds using autotools should have proper autoconf/automake dependency already, and if they don’t they are broken anyway. So why leaving them in system? And what about m4? m4 is not part of a common Unix system, it’s just an autoconf dependency, why isn’t it just an autoconf dependency?
For what concern the three main libraries, there aren’t that many packages using zlib directly nowadays, this is especially easy to spot on a system built with --as-needed, as without that you actually do see zlib used in every other binary, for indirect dependencies. Nor there aren’t tons and tons of packages using readline, or ncurses. Actually in my own vserver’s chroot I only found four packages using readline, none of them part of system: ruby with the readline extension (uhm I wonder if I should ask for this to become an USE flag, I certainly don’t need it and I’d rather get rid of it), psql from postgresql (which maybe it’s still good to have with readline compiled in, but I could easily get rid of), bc (which is just an e2fsprogs build-dep, and I could build without readline just fine), and mysql.
A little bit different the status of ncurses, which is used by screen, gettext (only a build-dep, not needed for runtime on Linux anyway), procps, psmisc and util-linux (and I wonder why we don’t have a switch to turn it off), texinfo (wonder why we can’t remove it entirely actually) and yet again ruby. Still, I wonder why ncurses is in system rather than being properly on the dependencies list of those packages.
As for perl, that’s probably a bit more justified, there are tons of packages using perl directly or indirectly, especially in build systems. But I would like those to depend on perl properly rather than having perl in system, as there are cases where perl is not really needed at runtime at least.
And the only users of gnuconfig are the packages making use of the old and deprecated gnuconfig.eclass, or portage’s econf. Why can’t it be a dependency of portage then?
There are probably other packages that should, in my opinion, be removed from system, but these are certainly some of the most common. Unfortunately there’s a recursive problem here: to remove the packages from system without breaking stuff you’d need a proper deptree, and to get a proper deptree you need to remove the packages from system. This is what actually stops me from proposing this right away…