#12234: 'deriving Eq' on recursive datatype makes ghc eat a lot of CPU and RAM -------------------------------------+------------------------------------- Reporter: slyfox | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Resolution: | Keywords: deriving-perf Operating System: Unknown/Multiple | Architecture: Type of failure: Compile-time | Unknown/Multiple performance bug | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by niteria): Shot in the dark: does solving coercibility for recursive newtypes involve finding fixpoints? I've run into one place in the code generator once where not returning the elements of a set in the Unique order would make it never find a fixpoint, because the insertion order would oscillate between 2 values. Otherwise, maybe using Unique order for SCC had some nice properties in this case. But under normal circumstances, I wouldn't expect my commit to cause that. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12234#comment:9 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler