#10632: ImplicitParams: GHC does not warn about unused implicit parameters -------------------------------------+------------------------------------- Reporter: mwnx | Owner: Type: bug | Status: new Priority: lowest | Milestone: Component: Compiler | Version: 7.10.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Incorrect Unknown/Multiple | warning at compile-time Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -------------------------------------+------------------------------------- When using -XImplicitParams, and an implicit parameter is not used within a function which accepts said parameter, no warning is issued (with -Wall turned on). Example: {{{#!hs {-# LANGUAGE ImplicitParams #-} f :: (?file1 :: String) => IO () f = putStrLn $ "f2: " main :: IO () main = let ?file1 = "A" in f }}} Here, I would expect a warning about ?file1 being unused in f. As far as I can tell (but I'm quite the layman in these matters), issuing a warning here would be desirable, possible, and quite easy. Sorry for the bug report if there's a reason for the status quo. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10632 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler