#9739: GHC 7.8 chokes on recursive classes -------------------------------------+------------------------------------- Reporter: bitonic | Owner: Type: bug | Status: new Priority: normal | Milestone: 7.10.1 Component: Compiler | Version: 7.9 (Type checker) | Keywords: Resolution: | Architecture: Unknown/Multiple Operating System: | Difficulty: Unknown Unknown/Multiple | Blocked By: Type of failure: Compile- | Related Tickets: time crash | Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Comment (by dfeuer): This is interesting: the definition of `Class1` is actually ''illegal'' in Haskell 98, because `class3` constrains the type variable `a`. This sort of thing is only supposed to be allowed with `-XConstrainedClassMethods`. In fact, if you enable that flag, suddenly the compiler realizes there's a loop! So it looks likely that someone made the flag enable the extra loop checking required by such methods, but accidentally failed to make it control whether such things are allowed at all! -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9739#comment:7 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler