Native bitfield in winmd does not have rust bindings

[youyuanwu]

given winmd:

public struct QUIC_SETTINGS
{
	[StructLayout(LayoutKind.Explicit)]
	public struct _Anonymous1_e__Union
	{
		public struct _IsSet_e__Struct
		{
			[NativeBitfield("MaxBytesPerKey", 0L, 1L)]
			[NativeBitfield("HandshakeIdleTimeoutMs", 1L, 1L)]
			public ulong _bitfield;
		}

		[FieldOffset(0)]
		public ulong IsSetFlags;

		[FieldOffset(0)]
		public _IsSet_e__Struct IsSet;
	}

	public _Anonymous1_e__Union Anonymous1;

	public ulong MaxBytesPerKey;

	public ulong HandshakeIdleTimeoutMs;
}

There is no NativeBitfield support in generated Rust:

#[repr(C)]
pub struct QUIC_SETTINGS {
    pub Anonymous1: QUIC_SETTINGS_0,
    pub MaxBytesPerKey: u64,
    pub HandshakeIdleTimeoutMs: u64
}
#[repr(C)]
pub union QUIC_SETTINGS_0 {
    pub IsSetFlags: u64,
    pub IsSet: QUIC_SETTINGS_0_0,
}
#[repr(C)]
pub struct QUIC_SETTINGS_0_0 {
    pub _bitfield: u64,
}

C code is like this that is used to generate winmd:

typedef struct QUIC_SETTINGS {

    union {
        uint64_t IsSetFlags;
        struct {
            uint64_t MaxBytesPerKey                         : 1;
            uint64_t HandshakeIdleTimeoutMs                 : 1;
 
        } IsSet;
    };

} QUIC_SETTINGS;

The intended use in c:

    // config
    QUIC_SETTINGS Settings = {0};
    Settings.MaxBytesPerKey                         = 1000;
    Settings.IsSet.MaxBytesPerKey                 = TRUE;

[youyuanwu]

Seems like windows-rs has already an open issue about this:
microsoft/windows-rs#2942