How to know whether the currently processed file is proto2 or proto3 in CustomizeCallback?

[ape-casear]

I need to add custom annotations to some fields. I found out that in the output of the rs code. Specifically serde.

the value would be wrapped by Option if it is in proto2

// proto2
foo: ::std::option::Option<u32>

// proto3
foo: u32

so params in the handler fn should be determined by syntax proto 2 or 3?

How to know whether the currently processed file is proto2 or proto3 in CustomizeCallback?

[ape-casear]

got it

  fn field(&self, field: &FieldDescriptor) -> Customize {
        let msg = field.containing_message();
        let syntax = msg.file_descriptor().proto().syntax();

        println!("syntax is {}", syntax);