#11600: Panic (ASSERT failed) in compiler/types/TyCoRep.hs:1939 -------------------------------------+------------------------------------- Reporter: hvr | Owner: Type: bug | Status: new Priority: highest | Milestone: 8.0.1 Component: Compiler | Version: 8.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Compile-time | Unknown/Multiple crash | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by hvr): Fyi, here's the same panic with a slightly newer snapshot of GHC HEAD (i.e. a008eadfaa4816be349b4fefde9b9b9edc1ca359), but this time bootstrapped with GHC 8.0 (and thus CallStack support): {{{ "inplace/bin/ghc-stage1" -hisuf dyn_hi -osuf dyn_o -hcsuf dyn_hc -fPIC -dynamic -O0 -H64m -Wall -fllvm-fill-undef-with-garbage -Werror -hide-all-packages -i -ighc/. -ighc/stage2/build -ighc/stage2/build/autogen -Ighc/stage2/build -Ighc/stage2/build/autogen -optP-DGHCI -optP-include -optPghc/stage2/build/autogen/cabal_macros.h -package-id array-0.5.1.0 -package-id base-4.9.0.0 -package-id bytestring-0.10.7.0 -package-id containers-0.5.7.1 -package-id deepseq-1.4.2.0 -package-id directory-1.2.5.1 -package-id filepath-1.4.1.0 -package-id ghc-8.1 -package-id ghc-boot-8.1 -package-id ghci-8.1 -package-id haskeline-0.7.2.2 -package-id process-1.4.2.0 -package-id time-1.6 -package-id transformers-0.5.2.0 -package-id unix-2.7.2.0 -Wall -fno-warn-name-shadowing -XHaskell2010 -O -dcore-lint -no-hs-main -threaded -no-user-package-db -rtsopts -Wnoncanonical-monad-instances -odir ghc/stage2/build -hidir ghc/stage2/build -stubdir ghc/stage2/build -c ghc/./GHCi/UI.hs -o ghc/stage2/build/GHCi/UI.dyn_o WARNING: file compiler/specialise/Specialise.hs, line 1173 Missed specialisation opportunity for $fMonadIOExceptT_$cliftIO [] 2 [] 1 [ALWAYS] WARNING: file compiler/specialise/Specialise.hs, line 1173 Missed specialisation opportunity for $w$c<*> [] 2 [] 1 [0] ghc-stage1: panic! (the 'impossible' happened) (GHC version 8.1.20160218 for x86_64-unknown-linux): ASSERT failed! CallStack (from HasCallStack): assertPprPanic, called at compiler/types/TyCoRep.hs:1932:56 in ghc:TyCoRep checkValidSubst, called at compiler/types/TyCoRep.hs:2076:17 in ghc:TyCoRep substCo, called at compiler/coreSyn/CoreSubst.hs:605:20 in ghc:CoreSubst in_scope InScope {fromTarget_aiKD pprTT_aj4s pp_resume_aj4J ... }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11600#comment:6 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler