#15170: GHC HEAD panic (dischargeFmv) -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.6.1 Component: Compiler (Type | Version: 8.5 checker) | Resolution: | Keywords: TypeInType Operating System: Unknown/Multiple | Architecture: Type of failure: Compile-time | Unknown/Multiple crash or panic | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by simonpj): The patch in comment:3 makes the program in comment:1 compile fine. However, the program in the Description now fails with a Lint error: {{{ *** Core Lint errors : in result of Desugar (before optimization) *** <no location info>: warning: In the type ‘forall (x :: a_a10V[sk:0]) a (b :: a ~> *) (c :: forall (x :: a). Proxy x ~> ((b @@ x) ~> *)) (f :: forall (x :: a) (y :: b @@ x). Proxy x ~> (Proxy y ~> ((c x @@ 'Proxy) @@ y))) (g :: forall (x :: a). Proxy x ~> (b @@ x)) (x :: a). SingKind ((c x @@ 'Proxy) @@ (g x @@ 'Proxy)) => (forall (xx :: a) (yy :: b @@ xx). Sing ((f xx yy @@ 'Proxy) @@ 'Proxy)) -> Sing (g x) -> Sing a -> Demote ((c x @@ 'Proxy) @@ (g x @@ 'Proxy))’ @ a_a10V[sk:0] is out of scope }}} I believe that the cause is the same as #14880, which I would love to get nailed. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15170#comment:4 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler