#11291: DfltProb1(optasm): panic CoreToStg.myCollectArgs -------------------------------------+------------------------------------- Reporter: thomie | Owner: Type: bug | Status: new Priority: highest | Milestone: 8.0.1 Component: Compiler | Version: 7.11 (CodeGen) | Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: Compile-time | Test Case: crash | typecheck/should_compile/DfltProb1 | (optasm) Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by bgamari): * failure: None/Unknown => Compile-time crash * component: Compiler => Compiler (CodeGen) Old description:
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# }}}
New description: The program looks like this: {{{#!hs 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# }}} -- Comment: I believe this is fixed on `master`. I have a suspicion that this is due to d990354473239943d83ee90f8906f3737b53fe65. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11291#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler