Add String_with_vars.Var.name

Signed-off-by: Rudi Grinberg <rudi.grinberg@gmail.com>

src/string_with_vars.ml

@@ -204,6 +204,8 @@ module Var = struct
     | None -> Single name
     | Some p -> Pair (name, p)
 
+  let name { name; _ } = name
+
   let full_name t =
     match destruct t with
     | Single s -> s

src/string_with_vars.mli

@@ -53,6 +53,7 @@ module Var : sig
 
   val sexp_of_t : t -> Sexp.t
 
+  val name : t -> string
   val loc : t -> Loc.t
   val full_name : t -> string
 

src/super_context.ml

@@ -231,11 +231,7 @@ end = struct
     let static_vars = String.Table.of_list_exn static_vars
 
     let rec expand t ~syntax_version ~var =
-      let name =
-        match String_with_vars.Var.destruct var with
-        | Single v -> v
-        | Pair (v, _) -> v
-      in
+      let name = String_with_vars.Var.name var in
       Option.bind (String.Table.find t name) ~f:(function
         | Nothing v -> Some v
         | Since (v, min_version) ->