#15712: GHC panic with -XDerivingVia -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.6.1 Resolution: | Keywords: DerivingVia Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by simonpj): With HEAD, and GHC 8.6, for the code in comment:2 I get {{{ T15712.hs:20:16: error: • Expecting one more argument to ‘GEndo’ Expected kind ‘* -> *’, but ‘GEndo’ has kind ‘(* -> *) -> * -> *’ • In the first argument of ‘Codensity’, namely ‘GEndo’ In the newtype declaration for ‘LogicT’ | 20 | (Codensity GEndo) | ^^^^^ }}} Can others confirm? If so, could someone add a regression test and close? Thanks! -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15712#comment:3 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler