Renaming unnamed field of internally tagged enum

[Jobarion]

The #[serde(rename)] attribute does not seem to work on unnamed fields of internally tagged enums.

#[derive(Serialize, Deserialize)]
#[serde(tag = "type")]
pub enum Test {
    A(#[serde(rename = "x")] u8),
    B(#[serde(rename = "x")] u8),
}

The struct above fails to serialize: "cannot serialize tagged newtype variant Test::A containing an integer", line: 0, column: 0, I would have expected it to serialize to {"type": "A", "x": 123}. Deserialization fails similarly.

Changing it to a struct with named fields works fine:

#[derive(Serialize, Deserialize)]
#[serde(tag = "type")]
pub enum Test {
    A{x: u8},
    B{x: u8},
}

Versions

serde: 1.0.210
serde_json: 1.0.132
rust: 1.81.0