#15110: Exitification abstracts over shadowed variables -------------------------------------+------------------------------------- Reporter: nomeata | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.6.1 Component: Compiler | Version: 8.5 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by simonpj): Ha, quite true -- although you give me too much credit for spotting it. NB: in your explanation (which should end up in a Note, be sure to point out that Core distinguishes variables by their `Unique` so their `OccName` is irrelevant. What you write should be understood to mean that the two `x`'s are variable with the same `Unique`, rather than with the same `OccName`. It's difficult to make this happen, and the Simplifier removes such shadowing, but yes, it's valid. Easy fix: {{{ abs_vars = map zap proto_abs_vars (proto_abs_vars, _) = foldr add ([], fvs) captured add v (acc, fvs) = (acc', fvs `delVarSet` b) where acc' | v `elemVarSet` fvs = v : acc | otherwise = acc }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15110#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler