Packed encoding of enum still includes variant names for non-unit variants

[joshtriplett]

Test case:

use serde::{Deserialize, Serialize};
use std::io::Write;

#[derive(Debug, Deserialize, Serialize)]
enum Thing {
    Thing1(String),
    Thing2(u64),
    Thing3(Box<[Thing]>),
    Thing4,
}

fn main() -> anyhow::Result<()> {
    let thing = Thing::Thing3(vec![Thing::Thing2(42), Thing::Thing4].into_boxed_slice());
    let v = serde_cbor::ser::to_vec_packed(&thing)?;
    std::fs::File::create("cbor")?.write_all(&v)?;
    Ok(())
}

Hex dump of the resulting file:

00000000  a1 66 54 68 69 6e 67 33  82 a1 66 54 68 69 6e 67  |.fThing3..fThing|
00000010  32 18 2a 03                                       |2.*.|

Notice that it includes Thing3 and Thing2, but not Thing4.

From what I can tell, the serialization of unit variants pays attention to self.packed, but the serialization of non-unit variants does not.

[matix2267]

I've created a bugfix for this issue (#215) but I don't have high hopes to get it merged given that this project is effectively unmaintained (see #179).

Feel free to use the bugfix repo directly if it fits your use case.