#![allow(unused_variables)]
#![allow(unused_must_use)]

use syn::{parse_str, parenthesized, Lit};
use syn::parse::{Parse, ParseStream, Result};

#[derive(Debug)] struct A {}

impl Parse for A {
    fn parse(input: ParseStream) -> Result<A> {
        let content;
        parenthesized!(content in input);
        content.parse::<Lit>()?;
        Ok(A {})
    }
}

fn main() {
    let x = parse_str::<A>("(1)");
    dbg!(x);
}