Jump to definition broken on file with simple typing error

[ddickstein]

module type S = sig
  val foo : unit -> ('a -> 'a -> bool) -> unit
end

module F (M : S) = struct
  let z () = M.foo () compare
end

Trying to jump to foo gives "Not in environment 'M.foo'". Fixing the type of the function foo takes to return int instead of bool makes jumping to definition work properly.

Tested on 945e5e1