#12648: Stack overflow when using monad-unlift -------------------------------------+------------------------------------- Reporter: nh2 | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Compile-time Unknown/Multiple | crash Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- I found that with the following simple program I could make runghc/ghci crash with `*** Exception: stack overflow`: {{{ #!/usr/bin/env stack -- stack --resolver lts-7.1 --install-ghc runghc --package monad- unlift-0.2.0 {-# LANGUAGE FlexibleContexts #-} import Control.Monad.Trans.Unlift f :: (MonadBaseUnlift m IO) => m a f = do _ <- askUnliftBase return () }}} I'm not super sure if that's OK. Probably not; even if it does trigger an undecideable case, shouldn't ghc tell me about it instead of just crashing? The `monad-unlift` code used is here: https://github.com/fpco/monad- unlift/blob/adb7869adccc66247cbb1a6175277802e9c098e1/monad- unlift/Control/Monad/Trans/Unlift.hs -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12648 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler