On Sep 13, 1:52 pm, Ross Paterson
On Sat, Sep 11, 2010 at 12:17:27PM -0700, Jason Dagit wrote:
"To avoid this problem in the future, avoid upgrading core packages. The latest version of cabal-install has disabled the upgrade command to make it a bit harder for people to break their systems in this way."
It's not always possible. In particular, random-1.0.0.2 (shipped with GHC 6.12.*) depends on the time package, of which more recent versions have been released. That can trigger rebuilding of random-1.0.0.2, and thus haskell98-1.0.1.1.
My case was similar, old-locale had been upgraded. And currently, haskell98 would not necessarily be rebuilt automatically - it would just break. The point is that time should _not_ be upgradeable with the current system, for the same reason as "cabal upgrade" is disabled. The alternative is to allow Cabal to rebuild itself _and_ GHC (and everything) safely. BTW, I just realized that thanks to static linking, the ghc and cabal binaries should never stop working - only using those libraries for building packages could break. If you always upgrade locally, you can always remove packages from the user DB as I did.
It might help if the release of random with GHC 7.0 had a tight dependency on the version of the time package shipped with it. Maybe all the core packages need tight dependencies.
If you mean it as a hack for cabal's brokenness, it could be OK, but otherwise than that, I believe it's a bad idea. GHC itself does not depend on any specific package; it's the compiled GHC package which has a tight dependency. So I don't like the concept. Furthermore, if a GHC release (whichever it is) had a tight dependency, that would be annoying for when you want to compile that release against different libraries - if that is supposed to work. But actually, on my system I can't see ghc in cabal's DB; I can see that in the ghc-pkg database for binaries, but there all dependencies are tight, probably because they are dependencies among installed packages. Have a look: $ cabal info QuickCheck [...] Dependencies: mtl -any, base >=4 && <5, random -any, base >=3 && <4, random -any, base <3, ghc -any, extensible- exceptions -any $ ghc-pkg describe QuickCheck | grep depends depends: base-3.0.3.1 random-1.0.0.1 Best regards -- Paolo Giarrusso, PhD student http://www.informatik.uni-marburg.de/~pgiarrusso/