#10689: compiling singletons-1.1.2.1 as -O1 -fspec-constr fails as 'Template variable unbound in rewrite rule' -------------------------------------+------------------------------------- Reporter: slyfox | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.2-rc2 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -------------------------------------+------------------------------------- First observed on singletons-1.1.2.1 package ghc-7.10.2. I've tried to distill it down to a single file. The file manages to crash both GHC and GHCi. GHCi: {{{ $ inplace/bin/ghc-stage2 -hide-all-packages -package=base --interactive List.hs GHCi, version 7.11.20150723: http://www.haskell.org/ghc/ :? for help [1 of 1] Compiling List ( List.hs, interpreted ) ghc-stage2: panic! (the 'impossible' happened) (GHC version 7.11.20150723 for x86_64-unknown-linux): floatExpr tick break<2>() Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} GHC: {{{ $ inplace/bin/ghc-stage2 -hide-all-packages -package=base --make List.hs -dsuppress-all -dsuppress-uniques [1 of 1] Compiling List ( List.hs, List.o ) ghc-stage2: panic! (the 'impossible' happened) (GHC version 7.11.20150723 for x86_64-unknown-linux): Template variable unbound in rewrite rule m [a_afdP, x, m, ipv, ipv, sc, sc, sc, sg] [a_afdP, x, m, ipv, ipv, sc, sc, sc, sg] [TYPE a_afdP, TYPE x, TYPE Let1627448493XsSym4 x m ipv ipv, sc, (SCons @~ ... sc sc) `cast` ...] [TYPE a_afdP, TYPE x, TYPE Let1627448493XsSym4 x ipv ipv ipv, sc, (SCons @~ ... ipv ipv) `cast` ...] Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} The "minimal" single-file sample is attached. If you need original selfcontained reproducer (79 modules, template haskell code) this is the version i've started with: http://code.haskell.org/~slyfox/unbound-template-var.tar.gz Adjusting path to GHC in '''./trigger-a-bug.bash''' should be enough. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10689 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler