Refactor array access type checking to ensure index is either an integer type or an enum, improving clarity and consistency in type validation.

Author: congwang-mk

src/type_checker.ml

@@ -715,13 +715,6 @@ and type_check_function_pointer_call ctx typed_callee typed_args arg_types pos =
 and type_check_array_access ctx arr idx pos =
   let typed_idx = type_check_expression ctx idx in
 
-  (* Index must be integer type, enum *)
-  let resolved_idx_type = resolve_user_type ctx typed_idx.texpr_type in
-  (match resolved_idx_type with
-   | U8 | U16 | U32 | U64 | I8 | I16 | I32 | I64 -> ()
-   | Enum _ -> ()  (* Enums are compatible with integers for array indexing *)
-   | _ -> type_error "Array index must be integer type" pos);
-  
   (* Check if this is map access first *)
   (match arr.expr_desc with
    | Identifier map_name when Hashtbl.mem ctx.maps map_name ->
@@ -738,7 +731,13 @@ and type_check_array_access ctx arr idx pos =
             { texpr_desc = TArrayAccess (typed_arr, typed_idx); texpr_type = map_decl.value_type; texpr_pos = pos }
         | None -> type_error ("Map key type mismatch") pos)
    | _ ->
-       (* Regular array access *)
+       (* Regular array access - index must be integer type or enum *)
+       let resolved_idx_type = resolve_user_type ctx typed_idx.texpr_type in
+       (match resolved_idx_type with
+        | U8 | U16 | U32 | U64 | I8 | I16 | I32 | I64 -> ()
+        | Enum _ -> ()  (* Enums are compatible with integers for array indexing *)
+        | _ -> type_error "Array index must be integer type" pos);
+       
        let typed_arr = type_check_expression ctx arr in
        (match typed_arr.texpr_type with
         | Array (element_type, _) ->