BER: automatic tagging not applied to tagged choice

[t-higuchi]

With following ASN.1 definition,

TestModuleA DEFINITIONS AUTOMATIC TAGS::= BEGIN
    --untagged choice
    C1 ::= CHOICE { a INTEGER, b BOOLEAN }

    --tagged choice. This is explicit tagging. (see ITU-T X.680 section 31.2.7 clause c)
    TC1  ::= [4] C1
    --another form of tagged choice
    TC2  ::= [4] CHOICE { a INTEGER, b BOOLEAN }
END

It is expected that:

• BER encoding of tagged choice TC1 and TC2 should be identical, and
• Alternatives in choice (a and b) are automatically tagged

But rasn produces different BER encoding for TC1 and TC2.

Code to reproduce:

    use rasn::prelude::*;

    #[doc = "untagged choice"]
    #[derive(AsnType, Debug, Clone, Decode, Encode, PartialEq, Eq, Hash)]
    #[rasn(choice, automatic_tags)]
    pub enum C1 {
        A(Integer),
        B(bool),
    }
    #[doc = "tagged choice. This is explicit tagging. (see ITU-T X.680 section 31.2.7 clause c)"]
    #[derive(AsnType, Debug, Clone, Decode, Encode, PartialEq, Eq, Hash)]
    #[rasn(delegate, tag(explicit(context, 4)))]
    pub struct TC1(pub C1);
    #[doc = "another form of tagged choice"]
    #[derive(AsnType, Debug, Clone, Decode, Encode, PartialEq, Eq, Hash)]
    #[rasn(choice, tag(explicit(context, 4)), automatic_tags)]
    pub enum TC2 {
        A(Integer),
        B(bool),
    }

    let choice = C1::A(0x55.into());
    let tc1 = TC1(choice.clone());
    let tc2 = TC2::A(0x55.into());

    let choice_enc = rasn::ber::encode(&choice).unwrap();
    let tc1_enc = rasn::ber::encode(&tc1).unwrap();
    let tc2_enc = rasn::ber::encode(&tc2).unwrap();

    println!("TaggedReferencedChoice: {:02x?}", tagged_ref_choice_ber);
    println!("TaggedChoice:           {:02x?}", tagged_choice_ber);

output is:

choice           : [80, 01, 55]
tagged choice TC1: [a4, 03, 80, 01, 55]
tagged choice TC2: [a4, 03, 02, 01, 55]
                            ^^^^^^^^^^ explicitly tagged INTEGER 0x55. 

It seems to be a bug where #[rasn(automatic_tags)] is not applied when CHOICE is tagged.