(Imported from Trac #594, reported by chevalier on 2009-09-29)
I was checking whether cabal-install would install my "extcore" package, and got:
$ sudo cabal install extcore --enable-library-profiling --reinstall
Preprocessing library extcore-0.3...
Could not find module `Data.Generics':
it was found in multiple packages: base-18.104.22.168 syb
cabal: Error: some packages failed to install:
extcore-0.3 failed during the building phase. The exception was:
exit: ExitFailure 1
cabal-install 0.6.2, library version 22.214.171.124.
(Imported comment by @dcoutts on 2009-09-29)
There's very little we can do about this until Cabal does the dependency tracking itself rather than leaving it to ghc --make.
In the mean time it might be possible to get ghc to report a more helpful error message. Against my better judgement, ghc recently added a flag to distinguish whether it is being called by cabal or by the end user so that it can target error messages better.
Closing as there's been no activity in years.
We're cleaning up the bug tracker to make it useful again and are thus closing bugs that haven't seen any activity in a long time. Please re-open (or file a new bug) if the problem reappears.