#14270: GHC HEAD's ghc-stage1 panics on Data.Typeable.Internal -------------------------------------+------------------------------------- Reporter: hvr | Owner: bgamari Type: bug | Status: new Priority: high | Milestone: 8.4.1 Component: Compiler | Version: 8.3 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Compile-time | Unknown/Multiple crash or panic | Test Case: Blocked By: | Blocking: Related Tickets: #14236 | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by bgamari): Ahh, I see what is going on here: When `Unify.unify_ty` needs to match a type `CastTy ty co` with something else, it doesn't even attempt to match `co` (on account of `Note [Matching in the presence of casts]`). Instead, it simply matches `ty` (adjusting the kind coercion accordingly). Consequently, template variables that occur only in `co` will never be matched. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14270#comment:5 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler