#490: cabal unpack gives bad error message for unsatisfiable constraints ----------------------------------+----------------------------------------- Reporter: duncan | Owner: Type: defect | Status: new Priority: normal | Milestone: cabal-install-0.6 Component: cabal-install tool | Version: 1.6.0.1 Severity: normal | Keywords: Difficulty: very easy (<1 hour) | Ghcversion: Platform: | ----------------------------------+----------------------------------------- The simple use case works fine: {{{ $ cabal unpack HaXml Downloading HaXml-1.13.3... Unpacking HaXml-1.13.3... }}} But we also allow constraints and that does not necessarily work: {{{ $ cabal unpack HaXml-1.19.6 cabal: List.maximumBy: empty list }}} The problem is that the index does not contain `HaXml-1.19.6`. After a `cabal update` it is fine. In general this would happen for any user- supplied version constraint that turns out to be unsatisfiable. The function `resolvePackages` in `Distribution.Client.Unpack` does not consider the possibility that a dependency may be unsatisfiable. -- Ticket URL: http://hackage.haskell.org/trac/hackage/ticket/490 Hackage http://haskell.org/cabal/ Hackage: Cabal and related projects