Fix bitvector update order for bitfield and single bit updates

Fixes #1101

src/lib/type_check.ml

@@ -3842,12 +3842,14 @@ and infer_vector_update l env v n exp =
                 mk_exp ~loc:l (E_app (Id_aux (update_name, field_id_loc), [v; exp]))
             | _ -> typ_error l "Vector update could not be interpreted as a bitfield update"
           )
-          v updates
+          v (List.rev updates)
       in
       infer_exp env update_exp
   | _ ->
       let update_exp =
-        List.fold_left (fun v (n, exp, l) -> mk_exp ~loc:l (E_app (mk_id "vector_update", [v; n; exp]))) v updates
+        List.fold_left
+          (fun v (n, exp, l) -> mk_exp ~loc:l (E_app (mk_id "vector_update", [v; n; exp])))
+          v (List.rev updates)
       in
       infer_exp env update_exp
 

test/c/bv_update_order.expect

@@ -0,0 +1,3 @@
+0x6
+0x6
+0x0

test/c/bv_update_order.sail

@@ -0,0 +1,32 @@
+default Order dec
+
+$include <prelude.sail>
+
+bitfield Foo : bits(4) = {
+  A : 3 .. 0,
+  B : 3 .. 0
+}
+
+function foo() -> unit = {
+  let x = Mk_Foo(sail_zeros(4));
+  let y = [x with A = 0x5, B = 0x6];
+  print_endline(bits_str(y[A]))
+}
+
+function bar() -> unit = {
+  let x = sail_zeros(4);
+  let y = [x with 3 .. 0 = 0x5, 3 .. 0 = 0x6];
+  print_endline(bits_str(y[3 .. 0]))
+}
+
+function baz() -> unit = {
+  let x = sail_zeros(4);
+  let y = [x with 0 = bitone, 0 = bitzero];
+  print_endline(bits_str(y[3 .. 0]))
+}
+
+function main() -> unit = {
+  foo();
+  bar();
+  baz();
+}