#14639: "unresolved constraints" when import and main missing -------------------------------------+------------------------------------- Reporter: bainewedlock | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: GHCi | Version: 8.0.2 Keywords: | Operating System: Windows Architecture: | Type of failure: Compile-time Unknown/Multiple | crash or panic Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- I gut a weird error because I forgot an import and the main method. (the commented lines in the code below) GHCi told me to post a bug about this, so... :-) == Steps to reproduce: {{{

ghci GHCi, version 8.0.2: http://www.haskell.org/ghc/ :? for help Prelude> :l bug.hs [1 of 1] Compiling Main ( bug.hs, interpreted ) ghc.exe: panic! (the 'impossible' happened) (GHC version 8.0.2 for x86_64-unknown-mingw32): initTc: unsolved constraints WC {wc_insol = [W] printf_a2MG :: t_a2MF[tau:1] (CHoleCan: printf)}

Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} == File bug.hs: {{{#!hs module Main where import Test.Hspec import Test.QuickCheck -- import Text.Printf testMovie :: Int -> Int -> Double -> Int -> Spec testMovie card ticket perc s = it (printf "should return Movie for card: %d, ticket: %d perc %s " card ticket (show perc)) $ movie card ticket perc `shouldBe` s movie :: Int -> Int -> Double -> Int movie card ticket perc = 4 -- main :: IO () -- main = undefined }}} == Expected behavior: Useful error message. == Actual behavior: "panic" error message. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14639 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler