Dictionary unpacking not working?

[lastmjs]

We recently updated our project a couple weeks ago to the latest commit on main. The last time we had done this was in December.

This code used to work:

@update
def create_recording(
    audio: blob, name: str, user_id: Principal
) -> CreateRecordingResult:
    user = users.get(user_id)

    if user is None:
        return {"Err": {"UserDoesNotExist": user_id}}

    id = generate_id()
    recording: Recording = {
        "id": id,
        "audio": audio,
        "created_at": ic.time(),
        "name": name,
        "user_id": user_id,
    }

    recordings.insert(recording["id"], recording)

    updated_user: User = {
        **user,
        "recording_ids": [*user["recording_ids"], recording["id"]],
    }

    users.insert(updated_user["id"], updated_user)

    return {"Ok": recording}

In particular:

    updated_user: User = {
        **user,
        "recording_ids": [*user["recording_ids"], recording["id"]],
    }

updated_user was working just fine, the recording_ids property had all of the previous recording_ids and the new one. But now the recording_ids property is empty when this code is executed.

If I change it to:

    updated_user: User = {
        "id": user["id"],
        "created_at": user["created_at"],
        "username": user["username"],
        "recording_ids": [*user["recording_ids"], recording["id"]],
    }

then everything works as expected. It seems there may be a problem with the dictionary unpacking of **user.

[DimitrisJim]

can you repro this with a self-contained MRE?

[youknowone]

The basic scenario is tested here: https://github.com/RustPython/RustPython/blob/main/extra_tests/snippets/builtin_dict.py#L287-L289

We need to find what triggers the bug.

[DimitrisJim]

yup, hence why we need a good example. I can't tell what is misbehaving in Jordan's example since I can't run it.