#643: Cabal should warn & detect when no modules are imported/used from a declared dependency -----------------------------+---------------------------------------------- Reporter: guest | Owner: Type: enhancement | Status: new Priority: low | Milestone: Component: Cabal library | Version: HEAD Severity: normal | Keywords: Difficulty: hard (< 1 day) | Ghcversion: Platform: | -----------------------------+---------------------------------------------- For context, see: http://www.haskell.org/pipermail/libraries/2010-March/013115.html http://www.haskell.org/pipermail/libraries/2010-March/013155.html http://www.haskell.org/pipermail/libraries/2010-March/013157.html Not a few Haskell packages had declared in their .cabal files that they used the 'haskell98' package; but they never imported anything from haskell98 (such as the Monad or List modules), as proven by simply removing the dependency and noting that it continued to compile. Apparently the authors were mistaken about the use, had updated the old module imports, or believed haskell98 did something it didn't. The authors never knew, because neither GHC, Cabal, nor cabal-install would ever warn about the superfluous dependency. Given that dependencies can cause failures quite easily via bit-rot or the diamond dependency problem, otiose deps are quite bad. -- Ticket URL: http://hackage.haskell.org/trac/hackage/ticket/643 Hackage http://haskell.org/cabal/ Hackage: Cabal and related projects