How to correctly use a 2bit enum in a struct?

[DidingasLushis]

Hello! First time asking questions here so I hope that this is the right place.

I am trying to do this:

use deku::prelude::*;
use super::Id;

#[derive(DekuRead, DekuWrite, Debug, PartialEq)]
pub struct Header {
    pub version: u8,
    pub port_num: u16,
    #[deku(bits = "2")]
    pub direction: Direction,
    pub id: Id,
}

#[derive(DekuRead, DekuWrite, Debug, PartialEq)]
#[deku(id_type = "u8")]
pub enum Direction {
    #[deku(id = "0")]
    Inbound,
    #[deku(id = "1")]
    Outbound,
    #[deku(id = "2")]
    Bidirectional,
    #[deku(id = "2")]
    Reserved,
}

However, I get this error:

$ cargo check
    Checking my_crate v0.1.0 (/path/to/project)
error[E0308]: mismatched types
  --> src/frame/header.rs:4:10
   |
4  | #[derive(DekuRead, DekuWrite, Debug, PartialEq)]
   |          ^^^^^^^^
   |          |
   |          expected `()`, found `BitSize`
   |          arguments to this function are incorrect
   |
note: associated function defined here
  --> <cargo-registry>/deku-0.19.1/src/lib.rs:423:8
   |
423|     fn from_reader_with_ctx<R: no_std_io::Read + no_std_io::Seek>(
   |        ^^^^^^^^^^^^^^^^^^^^
   = note: this error originates in the derive macro `DekuRead` (in Nightly builds, run with -Z macro-backtrace for more info)

error[E0308]: mismatched types
  --> src/frame/header.rs:4:20
   |
4  | #[derive(DekuRead, DekuWrite, Debug, PartialEq)]
   |                    ^^^^^^^^^
   |                    |
   |                    expected `()`, found `BitSize`
   |                    arguments to this function are incorrect
   |
note: method defined here
  --> <cargo-registry>/deku-0.19.1/src/lib.rs:489:8
   |
489|     fn to_writer<W: no_std_io::Write + no_std_io::Seek>(
   |        ^^^^^^^^^
   = note: this error originates in the derive macro `DekuWrite` (in Nightly builds, run with -Z macro-backtrace for more info)

For more information about this error, try `rustc --explain E0308`.
error: could not compile `my_crate` (lib) due to 2 previous errors

I have tried a few different re-writes and none seem to work, am I forced to do this?

#[derive(DekuRead, DekuWrite, Debug, PartialEq)]
#[deku(id_type = "u8", bits = "2")]
pub enum Direction {
    #[deku(id = "0")]
    Inbound,
    #[deku(id = "1")]
    Outbound,
    #[deku(id = "2")]
    Bidirectional,
    #[deku(id = "2")]
    Reserved,
}

[amboar]

The trick is to define a context attribute on the enum. Elsewhere I've done:

// MI v2.0, 5.1.1, Figure 77, SFREQ
#[derive(Debug, Clone, Copy, DekuRead, DekuWrite, Eq, PartialEq, PartialOrd)]
#[deku(
    bits = "bits.0",
    id_type = "u8",
    ctx = "endian: Endian, bits: BitSize",
    endian = "endian"
)]
#[repr(u8)]
enum SmbusFrequency {
    Reserved = 0x00,
    Freq100Khz = 0x01,
    Freq400Khz = 0x02,
    Freq1Mhz = 0x03,
}

// MI v2.0, 5.1.1, Figure 77
#[derive(Debug, DekuWrite, PartialEq)]
#[deku(endian = "little")]
struct GetSmbusI2cFrequencyResponse {
    status: ResponseStatus,
    #[deku(bits = "4", pad_bits_before = "4", pad_bytes_after = "2")]
    sfreq: SmbusFrequency,
}

So you could try:

use deku::prelude::*;
use super::Id;

#[derive(DekuRead, DekuWrite, Debug, PartialEq)]
pub struct Header {
    pub version: u8,
    pub port_num: u16,
    #[deku(bits = "2")]
    pub direction: Direction,
    pub id: Id,
}

#[derive(DekuRead, DekuWrite, Debug, PartialEq)]
#[deku(bits = "bits.0", ctx = "bits: BitSize", id_type = "u8")]
#[deku(id_type = "u8")]
pub enum Direction {
    #[deku(id = "0")]
    Inbound,
    #[deku(id = "1")]
    Outbound,
    #[deku(id = "2")]
    Bidirectional,
    #[deku(id = "2")]
    Reserved,
}

[DidingasLushis]

Great! Wow that was fast.

Note for readers:

// Don't forget to 
use deku::ctx::BitSize;