#![feature(proc_macro)] extern crate proc_macro; use proc_macro::TokenStream; #[proc_macro] pub fn print_a_thing(_input: TokenStream) -> TokenStream { "println!(\"Invoked from a proc macro\");".parse().unwrap() } #[cfg(test)] mod tests { #[test] fn it_works() { assert_eq!(2 + 2, 4); } }