Compiling

$include <result.sail>

union U ('a: Type) = { U1 : 'a }

type V = U(unit)

val main : unit -> unit
function main () = let r : result(V, unit) = Err(()) in ()

with f9db302 (and so probably the just-cut 0.17 release, I'm sorry) causes sail to die an inglorious death, croaking out Fatal error: exception Not_found and leaving behind an empty output file.

Confusingly, this is a minimized version of a much larger sail program that has been accepted without complaint in the past, so I am not sure what the actual preconditions for tripping over this are. This particular input seems fatal to the 0.15 and 0.16 installations I have handy, though.

Replacing the type V definition with type V = unit seems to result in successful compilation, so it seems like it's something to do with the fact that U is parametric?