[proc_macros]: _ as ident doesn't work

[driftluo]

use jsonrpsee_proc_macros::rpc;
use bytes::Bytes;

#[rpc(server)]
pub trait ARpc {

    #[method(name = "a")]
    async fn a(&self, _: Bytes);
}

will report:

error: custom attribute panicked
   |
14 | #[rpc(server)]
   | ^^^^^^^^^^^^^^
   |
   = help: message: Identifier in signature must be an ident

[niklasad1]

Indeed, _: Bytes as identifier doesn't work but _a: Bytes or __: Bytes works.

//cc @maciejhirsz

[dvdplm]

@driftluo Thank you for the report. We landed on not supporting _ as method argument name but improved the error handling to explain to users what happened a bit better.

[niklasad1]

FYI, because the servers currently support both the params to be passed as array or JSON object these identifiers are used to generate named fields in the JSON objects.