#11291: DfltProb1(optasm): panic CoreToStg.myCollectArgs -------------------------------------+------------------------------------- Reporter: thomie | Owner: Type: bug | Status: new Priority: highest | Milestone: 8.0.1 Component: Compiler | Version: 7.11 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: typecheck/should_compile/DfltProb1 | (optasm) | Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- The program looks like this: {{{ module DfltProb1 where import Control.Monad.ST import Prelude hiding (traverse) traverse :: a -> ST s [a] traverse = undefined -- WORKS with signature test :: Num a => [a] test = runST (traverse 1) main = print test }}} This is the failure: {{{ $ ghc-7.11.20151225 -O DfltProb1.hs ghc-stage2: panic! (the 'impossible' happened) (GHC version 7.11.20151224 for x86_64-unknown-linux): CoreToStg.myCollectArgs (case traverse of _ [Occ=Dead] { }) realWorld# }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11291 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler