#9565: T3500b exhaust simplifier ticks (loops?) on WAY=optasm -------------------------------------+------------------------------------- Reporter: slyfox | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.9 Resolution: | Keywords: Operating System: | Architecture: x86_64 (amd64) Unknown/Multiple | Difficulty: Unknown Type of failure: Compile- | Blocked By: time crash | Related Tickets: Test Case: T3500b | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Comment (by carter): could this be an instance of the known issue about recursive types interacting with the inliner? https://www.haskell.org/ghc/docs/7.8.3/html/users_guide/bugs.html see the second item there if i change the program to {{{ {-# LANGUAGE TypeFamilies, FlexibleContexts, UndecidableInstances #-} module Main where newtype Mu f = Mu (f (Mu f)) type family Id m type instance Id m = m instance Show (Id (f (Mu f))) => Show (Mu f) where show (Mu f) = show f {-# NOINLINE show #-} showMu :: Mu (Either ()) -> String showMu = show item :: Mu (Either ()) item = Mu (Right (Mu (Left ()))) main = print (showMu item) }}} that is, I mark the show instance NOINLINE, the problem goes away. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9565#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler