Nested helper attributes in procedural macro

help
1

I have written a procedural macro that implements parsing a message specification from a byte stream for a struct by using helper attributes like so.

#[derive(MessageParsing)]
pub struct ExampleMessage {
    #[scale = 0.0001]
    field_1: u32,
    #[bit_size = 12]
    field_2: u16,
    field_3_length: u8,
    #[length_field = "field_3_length"]
    #[fieldset(Field3 {
        subfield_1: u16,
        subfield_2: u16,
    })]
    field_3: Vec<Field3>
}

This properly expands to defining the Field3 struct and the auto-generated parsing logic for both ExampleMessage and Field3. The problem I encounter is when I try to use the other helper attributes in the definition for fieldset like so

#[derive(MessageParsing)]
pub struct ExampleMessage {
    #[scale = 0.0001]
    field_1: u32,
    #[bit_size = 12]
    field_2: u16,
    field_3_length: u8,
    #[length_field = "field_3_length"]
    #[fieldset(Field3 {
        #[bit_size = 12]
        subfield_1: u16,
        #[scale = 0.01]
        subfield_2: u16,
    })]
    field_3: Vec<Field3>
}

I get the error "cannot find attribute bit_size in this scope. Is there a way to get the helper attributes recognized in the scope of the fieldset attribute. I've tried creating a second pass-through macro with the same set of helper attributes defined and putting in #[derive(Passthrough) before defining Field3 and it doesn't seem to make a difference. Is there some way of getting these attributes into the scope of the expression acting as an argument to fieldset?

2

try split the define ?

#[derive(MessageParsing)]
pub struct ExampleMessage {
    #[scale = 0.0001]
    field_1: u32,
    #[bit_size = 12]
    field_2: u16,
    field_3_length: u8,
    #[length_field = "field_3_length"]
    field_3: Vec<Field3>
}

#[derive(MessageParsing)]
pub struct Field3 {
        #[bit_size = 12]
        subfield_1: u16,
        #[scale = 0.01]
        subfield_2: u16,
}
3

Yeah, I feel silly, this was kind of staring me in the face. Thank you! I'm still kind of curious whether getting an attribute argument to compile with attributes for a macro is possible, but I'm struggling to find a use case to be honest