#11371: Bogus in-scope set in substitutions -------------------------------------+------------------------------------- Reporter: simonpj | Owner: niteria Type: bug | Status: new Priority: high | Milestone: 8.2.1 Component: Compiler | Version: 7.10.3 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: #11360 | Differential Rev(s): phab:D1792, Wiki Page: | phab:D1801, phab:D1802 -------------------------------------+------------------------------------- Comment (by niteria): Looking at {{{ let { a_sihF :: VarEnv Var [LclId, Str=DmdType] a_sihF = case TyCoRep.$wtyCoVarsOfTypesAcc (ghc-prim-0.5.0.0:GHC.Types.: @ Type ty_a6bU args_a6bV) FV.runFV2 ((containers-0.5.7.1:Data.IntMap.Base.Nil @ Var) `cast` (Sym UniqFM.N:UniqFM[0] <Var>_N :: containers-0.5.7.1:Data.IntMap.Base.IntMap Var ~R# UniqFM.UniqFM Var)) (ghc-prim-0.5.0.0:GHC.Types.[] @ Var) ((containers-0.5.7.1:Data.IntMap.Base.Nil @ Var) `cast` (Sym UniqFM.N:UniqFM[0] <Var>_N :: containers-0.5.7.1:Data.IntMap.Base.IntMap Var ~R# UniqFM.UniqFM Var)) of _ [Occ=Dead] { (# ww4_aeZD, ww5_aeZE #) -> ww5_aeZE } } in let { a1_sihE :: InScopeSet [LclId, Str=DmdType m] a1_sihE = VarEnv.InScope a_sihF 1# } in let { empty_subst_seCG :: TCvSubst [LclId, Str=DmdType m] empty_subst_seCG = TyCoRep.TCvSubst a1_sihE ((containers-0.5.7.1:Data.IntMap.Base.Nil @ Type) `cast` (Sym UniqFM.N:UniqFM[0] <Type>_N :: containers-0.5.7.1:Data.IntMap.Base.IntMap Type ~R# UniqFM.UniqFM Type)) ((containers-0.5.7.1:Data.IntMap.Base.Nil @ Coercion) `cast` (Sym UniqFM.N:UniqFM[0] <Coercion>_N :: containers-0.5.7.1:Data.IntMap.Base.IntMap Coercion ~R# UniqFM.UniqFM Coercion)) } in }}} it produces not 1, but 3 thunks. I will try to see if reducing that to 1 helps. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11371#comment:35 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler