py/vm: Simplify handling of MP_OBJ_STOP_ITERATION in yield-from opcode.

Signed-off-by: Damien George <damien@micropython.org>

1 files changed, 3 insertions, 3 deletions

diff --git a/py/runtime.c b/py/runtime.c
index 261670d4f..b53711bbe 100644
--- a/py/runtime.c
+++ b/py/runtime.c
@@ -1272,7 +1272,6 @@ mp_obj_t mp_iternext(mp_obj_t o_in) {
     }
 }
 
-// TODO: Unclear what to do with StopIterarion exception here.
 mp_vm_return_kind_t mp_resume(mp_obj_t self_in, mp_obj_t send_value, mp_obj_t throw_value, mp_obj_t *ret_val) {
     assert((send_value != MP_OBJ_NULL) ^ (throw_value != MP_OBJ_NULL));
     const mp_obj_type_t *type = mp_obj_get_type(self_in);
@@ -1287,8 +1286,9 @@ mp_vm_return_kind_t mp_resume(mp_obj_t self_in, mp_obj_t send_value, mp_obj_t th
         if (ret != MP_OBJ_STOP_ITERATION) {
             return MP_VM_RETURN_YIELD;
         } else {
-            // Emulate raise StopIteration()
-            // Special case, handled in vm.c
+            // The generator is finished.
+            // This is an optimised "raise StopIteration(None)".
+            *ret_val = mp_const_none;
             return MP_VM_RETURN_NORMAL;
         }
     }