On Thu, Mar 16, 2006 at 02:58:00PM +0100, Paul de Vrieze wrote: > On Wednesday 15 March 2006 16:13, Gustavo Sverzut Barbieri wrote: > > Hello, > > > > There is any provision for binary dependency on Gentoo/Portage? The > > way it works now is quite messy with things like revdep-rebuild. > > Solving this is not trivial. Basically suppose application X depends on > sys-libs/db-4.* > > This can be resolved by differently slotted libraries. We need to record > which one was actually used (not easy by itself, but more an issue of the > ebuild itself, if more than 1 candidate is available). But suppose that > we know that the application was compiled to use db-4.3.29. We must then > know that it is ok to replace the db-4.3.29 package with 4.3.30, but that > it isn't ok to replace it by 4.3.28 or 4.4.20. > > To make this things worse, the above example assumes that within a slot, > the libraries are binary compatible. There are examples of libraries that > are not. And what about a library whose interface is dependent on a third > library: B uses A, C uses B, but B exports A. So B is dependent on A, and > the binary package of C must record that B was compiled with A. > > In short, welcome to binary package hell. This is the reason that binary > distributions must use versions. Even debian. It is just very very hard > to fix these kinds of indirect dependencies.
You're forgetting we're equally screwed when upstream (*cough* openssl) goes and changes the soname while preserving abi. Old solution to it was to add another metadata key to ebuilds, "bincompat" that is compared within slotting to see if a rebuild of rdepend consumers needs to occur. fex... alsa-lib-0.90 slot=0 bincompat=0 alsa-lib-1.0 slot=0 bincompat=1 The pkg manager does it's little dance to figure out what should be installed where (and what versions can coexist), while doing it if it's going to replace a pkg and bincompat differs, pull in the subset of the state graph at that point (including vdb) that rdeps on that package/slot and force a rebuild of them. As per the norm, requires a smart resolver; for c++ would expect cycles to occur where the only solution is to pull in libstdc++ (fex) to sidestep horkage while doing the rebuilds... Also note that (like all general solutions) it's not going to be able to cover all insane stuff; if the api breaks in transitioning bincompat is going to cause a minor explossion that is only resolvable by packages specifying exact dependencies (read: version ranges). ~harring
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