try 2. make namedtuple types handle subclasses

py/objnamedtuple.c

@@ -31,6 +31,7 @@
 #include "py/runtime.h"
 #include "py/objstr.h"
 #include "py/objnamedtuple.h"
+#include "py/objtype.h"
 
 #include "supervisor/shared/translate.h"
 
@@ -70,6 +71,15 @@ void namedtuple_print(const mp_print_t *print, mp_obj_t o_in, mp_print_kind_t ki
     mp_obj_attrtuple_print_helper(print, fields, &o->tuple);
 }
 
+mp_obj_t namedtuple_subscr(mp_obj_t self_in, mp_obj_t index, mp_obj_t value) {
+    mp_obj_type_t *type = mp_obj_get_type(self_in);
+    // Check for subclasses of namedtuple and unpack if needed.
+    if (type->parent != &mp_type_tuple) {
+        self_in = ((mp_obj_instance_t*) self_in)->subobj[0];
+    }
+    return mp_obj_tuple_subscr(self_in, index, value);
+}
+
 void namedtuple_attr(mp_obj_t self_in, qstr attr, mp_obj_t *dest) {
     if (dest[0] == MP_OBJ_NULL) {
         // load attribute
@@ -167,7 +177,7 @@ STATIC mp_obj_t mp_obj_new_namedtuple_type(qstr name, size_t n_fields, mp_obj_t
     o->base.unary_op = mp_obj_tuple_unary_op;
     o->base.binary_op = mp_obj_tuple_binary_op;
     o->base.attr = namedtuple_attr;
-    o->base.subscr = mp_obj_tuple_subscr;
+    o->base.subscr = namedtuple_subscr;
     o->base.getiter = mp_obj_tuple_getiter;
     o->base.parent = &mp_type_tuple;
     return MP_OBJ_FROM_PTR(o);

py/objnamedtuple.h

@@ -49,6 +49,7 @@ typedef struct _mp_obj_namedtuple_t {
 
 void namedtuple_print(const mp_print_t *print, mp_obj_t o_in, mp_print_kind_t kind);
 size_t mp_obj_namedtuple_find_field(const mp_obj_namedtuple_type_t *type, qstr name);
+mp_obj_t namedtuple_subscr(mp_obj_t self_in, mp_obj_t index, mp_obj_t value);
 void namedtuple_attr(mp_obj_t self_in, qstr attr, mp_obj_t *dest);
 mp_obj_namedtuple_type_t *mp_obj_new_namedtuple_base(size_t n_fields, mp_obj_t *fields);
 mp_obj_t namedtuple_make_new(const mp_obj_type_t *type_in, size_t n_args, const mp_obj_t *args, mp_map_t *kw_args);

py/objtuple.c

@@ -179,9 +179,10 @@ mp_obj_t mp_obj_tuple_binary_op(mp_binary_op_t op, mp_obj_t lhs, mp_obj_t rhs) {
 
 #pragma GCC diagnostic ignored "-Wunused-parameter"
 mp_obj_t mp_obj_tuple_subscr(mp_obj_t self_in, mp_obj_t index, mp_obj_t value) {
+
     if (value == MP_OBJ_SENTINEL) {
         // load
-        mp_obj_tuple_t *self = mp_instance_cast_to_native_base(self_in, MP_OBJ_FROM_PTR(&mp_type_tuple));
+        mp_obj_tuple_t *self = MP_OBJ_TO_PTR(self_in);
 #if MICROPY_PY_BUILTINS_SLICE
         if (MP_OBJ_IS_TYPE(index, &mp_type_slice)) {
             mp_bound_slice_t slice;