#9102: Assertion failure in CoreUtils.lhs ------------------------------------+------------------------------------- Reporter: tmcdonell | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.2 Keywords: | Operating System: Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: None/Unknown Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ------------------------------------+------------------------------------- I happened to be using a debug build of ghc-7.8.2, and got this assertion failure compiling [http://hackage.haskell.org/package/fclabels-2.0.1 fclabels]. {{{ [ 7 of 10] Compiling Data.Label.Total ( src/Data/Label/Total.hs, dist/build/Data/Label/Total.o ) <no location info>: ghc: panic! (the 'impossible' happened) (GHC version 7.8.2.20140429 for x86_64-unknown-linux): ASSERT failed! file compiler/coreSyn/CoreUtils.lhs line 194 coercion Nth:0 dt{v d7gF} [lid] passed to mkCast base:Control.Category.id{v rkl} [gid[ClassOp]] @ ghc- prim:GHC.Prim.*{(w) tc 34d} @ fclabels-2.0.1:Data.Label.Point.Total{tc r1Pm} (base:Control.Arrow.$p1Arrow{v r1s} [gid[ClassOp]] @ fclabels-2.0.1:Data.Label.Point.Total{tc r1Pm} (base:Control.Arrow.$p1ArrowApply{v rp} [gid[ClassOp]] @ fclabels-2.0.1:Data.Label.Point.Total{tc r1Pm} $dArrowApply{v a72o} [lid])) @ f{tv a8m6} [tv] f{v a8hw} [lid] has wrong role nominal }}} Problem does not appear with `-O0`. I couldn't test with HEAD because fclabels isn't compatible with the changes to Template Haskell yet. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9102 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler