1 files changed, 16 insertions, 7 deletions
diff --git a/library/goptions.ml b/library/goptions.ml
index eb7bb5b4..dcbc46ab 100644
--- a/library/goptions.ml
+++ b/library/goptions.ml
@@ -161,7 +161,7 @@ module type RefConvertArg =
 sig
   type t
   val compare : t -> t -> int
-  val encode : reference -> t
+  val encode : qualid -> t
   val subst : substitution -> t -> t
   val printer : t -> Pp.t
   val key : option_name
@@ -172,7 +172,7 @@ end
 module RefConvert = functor (A : RefConvertArg) ->
 struct
   type t = A.t
-  type key = reference
+  type key = qualid
   let compare = A.compare
   let table = ref_table
   let encode = A.encode
@@ -318,26 +318,35 @@ let set_option_value ?(locality = OptDefault) check_and_cast key v =
   | Some (name, depr, (read,write,append)) ->
     write locality (check_and_cast v (read ()))
 
-let bad_type_error () = user_err Pp.(str "Bad type of value for this option.")
+let show_value_type = function
+  | BoolValue _ -> "bool"
+  | IntValue _ -> "int"
+  | StringValue _ -> "string"
+  | StringOptValue _ -> "string"
+
+let bad_type_error opt_value actual_type =
+  user_err Pp.(str "Bad type of value for this option:" ++ spc() ++
+               str "expected " ++ str (show_value_type opt_value) ++
+               str ", got " ++ str actual_type ++ str ".")
 
 let check_int_value v = function
   | IntValue _ -> IntValue v
-  | _ -> bad_type_error ()
+  | optv -> bad_type_error optv "int"
 
 let check_bool_value v = function
   | BoolValue _ -> BoolValue v
-  | _ -> bad_type_error ()
+  | optv -> bad_type_error optv "bool"
 
 let check_string_value v = function
   | StringValue _ -> StringValue v
   | StringOptValue _ -> StringOptValue (Some v)
-  | _ -> bad_type_error ()
+  | optv -> bad_type_error optv "string"
 
 let check_unset_value v = function
   | BoolValue _ -> BoolValue false
   | IntValue _ -> IntValue None
   | StringOptValue _ -> StringOptValue None
-  | _ -> bad_type_error ()
+  | optv -> bad_type_error optv "nothing"
 
 (* Nota: For compatibility reasons, some errors are treated as
    warning. This allows a script to refer to an option that doesn't