#13741: Newtype unwrapping causes GHC panic -------------------------------------+------------------------------------- Reporter: vaibhavsagar | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.2 Keywords: newtype ghci | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Some combination of newtypes and infix operators is causing GHCi to panic. Steps to reproduce: 1. Open a fresh GHCi session. 2. Define `Cont`: `newtype Cont a r = Cont {(>>-) :: (a -> r) -> r}` 3. Define a `Functor` instance for `Cont`: `instance Functor (Cont r) where fmap f c = Cont $ \k -> c >>>- f . k` 4. Observe the following: {{{ ghc: panic! (the 'impossible' happened) (GHC version 8.0.2 for x86_64-unknown-linux): get_op >>>- Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13741 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler