Re: [GHC] #15473: GHC 8.6+ loops infinitely on an UndecidableInstances error message

#15473: GHC 8.6+ loops infinitely on an UndecidableInstances error message -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: new Priority: highest | Milestone: 8.6.1 Component: Compiler (Type | Version: 8.5 checker) | Resolution: | Keywords: 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 Simon Peyton Jones ): In [changeset:"db6f1d9cfc74690798645a7cc5b25040c36bb35d/ghc" db6f1d9/ghc]: {{{ #!CommitTicketReference repository="ghc" revision="db6f1d9cfc74690798645a7cc5b25040c36bb35d" Turn infinite loop into a panic In these two functions * TcIface.toIfaceAppTyArgsX * Type.piResultTys we take a type application (f t1 .. tn) and try to find its kind. It turned out that, if (f t1 .. tn) was ill-kinded the function would go into an infinite loop. That's not good: it caused the loop in Trac #15473. This patch doesn't fix the bug in #15473, but it does turn the loop into a decent panic, which is a step forward. }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15473#comment:3 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler