#15767: "StgCmmEnv: variable not found" with FunctionalDependencies and FlexibleContexts -------------------------------------+------------------------------------- Reporter: roland | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.6.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Compile-time Unknown/Multiple | crash or panic Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- {{{ {-# LANGUAGE FunctionalDependencies, FlexibleContexts #-} module Bug where class C a b | b -> a where f :: a -> b y = x where x :: (C () b, C Bool b) => b x = f () }}} {{{ $ ghc -c Bug.hs ghc: panic! (the 'impossible' happened) (GHC version 8.6.1 for x86_64-unknown-openbsd): StgCmmEnv: variable not found $dC_a1lC local binds for: f $tc'C:C $tcC $trModule $tc'C:C1_r1mz $tc'C:C2_r1n0 $krep_r1n1 $krep1_r1n2 $krep2_r1n3 $krep3_r1n4 $krep4_r1n5 $tcC1_r1n6 $tcC2_r1n7 $krep5_r1n8 $krep6_r1n9 $krep7_r1na $trModule1_r1nb $trModule2_r1nc $trModule3_r1nd $trModule4_r1ne $krep8_r1nf $krep9_r1ng Call stack: CallStack (from HasCallStack): callStackDoc, called at compiler/utils/Outputable.hs:1160:37 in ghc:Outputable pprPanic, called at compiler/codeGen/StgCmmEnv.hs:149:9 in ghc:StgCmmEnv Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15767 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler