#15496: if a variable that isn't in scope is used and main is not defined ghc freaks out ----------------------------------------+--------------------------------- Reporter: kuhnsB | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.6.1 Component: Compiler | Version: 8.4.3 Keywords: | Operating System: Linux Architecture: Unknown/Multiple | Type of failure: None/Unknown Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: ----------------------------------------+--------------------------------- --y = 5::Double f::Double ->Double f x = x+y --main = print 5 produces: ghc: panic! (the 'impossible' happened) (GHC version 8.0.2 for x86_64-unknown-linux): initTc: unsolved constraints WC {wc_insol = [W] y_axB :: t_axA[tau:1] (CHoleCan: y)} Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug un-commenting either line 1 or 4 causes ghc to identify the other problem correctly -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15496 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler