Fix: return module items in file order

This affects their UIDs, and the order in which they later get traversed.

In particular, it was affecting the struct names renaming.

compiler/shared_ast/program.ml

@@ -122,6 +122,10 @@ let rename_ids
   let module PathMap = Map.Make (Uid.Path) in
   let pctxmap = PathMap.singleton [] ctx in
   let pctxmap, structs_map, fields_map, ctx_structs =
+    (* Warning: the folding order matters here, if a module contains e.g. two
+       fields with the same name. This fold relies on UIDs, and is thus
+       dependent on the definition order. Another possibility would be to fold
+       lexicographically, but the result would be "less intuitive" *)
     StructName.Map.fold
       (fun name fields (pctxmap, structs_map, fields_map, ctx_structs) ->
         let path = StructName.path name in

compiler/surface/parser_driver.ml

@@ -476,7 +476,8 @@ let get_interface program =
       (* Non-metadata blocks are ignored *)
       req, acc
   in
-  List.fold_left filter ([], []) program.Ast.program_items
+  let req, acc = List.fold_left filter ([], []) program.Ast.program_items in
+  List.rev req, List.rev acc
 
 (** {1 API} *)