#14933: DeriveAnyClass can cause "No skolem info" GHC panic -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: patch Priority: normal | Milestone: Component: Compiler (Type | Version: 8.2.2 checker) | Resolution: | Keywords: deriving Operating System: Unknown/Multiple | Architecture: Type of failure: Compile-time | Unknown/Multiple crash or panic | Test Case: Blocked By: | Blocking: Related Tickets: #14932 | Differential Rev(s): Phab:D4507 Wiki Page: | -------------------------------------+------------------------------------- Changes (by RyanGlScott): * status: new => patch * differential: => Phab:D4507 * related: => #14932 Comment: Ack, it turns out that we are re-using the same unification variables across multiple iterations of `simplifyDeriv`, which results in utter disaster. (Honestly, I'm not sure how anything was working before.) Phab:D4507 fixes this issue (and #14932) by generating new unification variables across //each// iteration of `simplifyDeriv`. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14933#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler