[cosmwasm-schema] unknown serde variant attribute `untagged`

[Amit Prasad]

When trying to add serde attributes, I get the "unknown serde variant attribute" error. Sample code:

#[cw_serde]
pub enum Parent {
    Foo { x: u128 },
    Bar { y: String },
    #[serde(untagged)]
    Baz(Child),
}

#[cw_serde]
pub enum Child {
    A { x: u128 },
    B { y: String },
}

And the compiler error:

error: unknown serde variant attribute `untagged`
   |
56 |     #[serde(untagged)]
   |             ^^^^^^^^

[Amit Prasad]

Just to elaborate, this would be used to effectively "embed" or "inherit" another ExecuteMsg, for example, to implement a standard interface. If there's a better way to do this ergonomically I'm all ears, but I found this error preventing me from the most idiomatic solution.

[Amit Prasad]

Seems like this happens when JsonSchema is derived on the enum: GREsau/schemars#222

Maybe there could be an option such as #[cw_serde(schema=false)]

[Christoph Otter]

You have two options here:

• Don't use #[cw_serde]: It's just an alias for a bunch of attributes, so you can just add them yourself, omitting JsonSchema. See here for the attributes.
• Put the #[serde(untagged)] on the enum itself and wrap your messages in another enum. Then your example would look like this:

#[cw_serde]
#[serde(untagged)]
pub enum Parent {
    MyMsgs(MyMsgs),
    Baz(Child),
}

#[cw_serde]
pub enum MyMsgs {
    Foo { x: u128 },
    Bar { y: String },
}

#[cw_serde]
pub enum Child {
    A { x: u128 },
    B { y: String },
}

One thing to note here is that in the past, #[serde(untagged)] produced float operations, so the contract will be limited to 1.5+ chains.