Hi, Am Mittwoch, den 24.08.2011, 12:44 +0200 schrieb Matthias Klose: > > The question that has to be answered first is: Assume the libraries do > > not depend on libffi themselves, and only ghc does. Now you update > > libffi and ghc gets rebuilds, what will happen: > > > > A) The haskell ABIs stay the same, the existing library packages can > > still be used. Great. > > > > B) The haskell ABIs change. We’ll have to binNMU all Haskell libraries, > > but oh well, not bad thanks to BD-Uninstallable-support in wanna-build > > and autosigning. > > > > C) The haskell ABIs do not change, but the old library builds are > > broken nevertheless. Big mess. Hard to recover from, because builds are > > not ordered automatically any more. Needs lots of NMUes and Dep-Waits. > > sorry, I don't get the `C' case. why should these be broken by a libffi or > libgmp change? Maybe it’s an unrealistic example, but I could imagine that ghc some data type (size) defined by libffi is used when generating code for a haskell library under the assumption that it has the same structure/size in the run time system and/or other used haskell libraries. But instead of making blind guesses, maybe GHC upstream can enlighten us: Is it safe to build ghc and a Haskell library, then upgrade libffi to a new version (with soname bump), rebuild ghc, but use the previous library build? > > Removing the libffi dependencies from the haskell libraries makes C > > possible and only helps with A. So until someone investigates this, I’d > > rather err on the safe side, leave the dependencies in, and fix the > > issue by rebuilding all haskell libraries when you upload the new ffi > > soname to unstable. > > well, with binNMU orgies like this you'll pull in any new or tightened > dependencies for shared libraries. Not depending on these unused libraries > does avoid this. True. I agree that it would be nice and worthwhile to remove the libffi dependency from the libraries, but only if it is actually safe and scenario C is guaranteed not to happen. Greetings, Joachim -- Joachim "nomeata" Breitner Debian Developer nomeata@debian.org | ICQ# 74513189 | GPG-Keyid: 4743206C JID: nomeata@joachim-breitner.de | http://people.debian.org/~nomeata
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