py/objboundmeth: Support loading generic attrs from the method.

Instead of assuming that the method is a bytecode object, and only
supporting load of __name__, make the operation generic by delegating the
load to the method object itself.  Saves a bit of code size and fixes the
case of attempting to load __name__ on a native method, see issue #4028.

py/objboundmeth.c

@@ -89,10 +89,9 @@ STATIC void bound_meth_attr(mp_obj_t self_in, qstr attr, mp_obj_t *dest) {
         // not load attribute
         return;
     }
-    if (attr == MP_QSTR___name__) {
-        mp_obj_bound_meth_t *o = MP_OBJ_TO_PTR(self_in);
-        dest[0] = MP_OBJ_NEW_QSTR(mp_obj_fun_get_name(o->meth));
-    }
+    // Delegate the load to the method object
+    mp_obj_bound_meth_t *self = MP_OBJ_TO_PTR(self_in);
+    mp_load_method_maybe(self->meth, attr, dest);
 }
 #endif
 

tests/basics/fun_name.py

@@ -15,3 +15,10 @@ try:
 except AttributeError:
     print('SKIP')
     raise SystemExit
+
+# __name__ of a bound native method is not implemented in uPy
+# the test here is to make sure it doesn't crash
+try:
+    str((1).to_bytes.__name__)
+except AttributeError:
+    pass