anchor.diff:  - v27: Added PConstant
   - v28: added many things for which the AST wasn't bumped; bumped it for
     TConstBuf which will expect will be used soon
  -- v29: added EComment
   *)
   
   (* COPY-PASTED ****************************************************************)
  
positive.code:           failwith "Cannot extract comment applied to a non-literal"
        end
  
    | MLE_App ({ expr = MLE_Name ([ "C" ], "comment_gen") }, args) ->
       failwith ("comment_gen called with wrong number of arguments: " ^ string_of_int (List.length args))
  
    | MLE_App ({ expr = MLE_Name ([ "LowStar"; "Literal" ], "buffer_of_literal") }, [ { expr = e } ]) ->
        begin match e with
  
negative.code:   | EBufCreateNoInit of lifetime * expr
    | EAbortT of string * typ
    | EComment of string * expr * string
    | EStandaloneComment of string
  
  and op =
    | Add | AddW | Sub | SubW | Div | DivW | Mult | MultW | Mod
  