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