1 #![crate_type = "proc-macro"]
3 extern crate proc_macro;
5 use proc_macro::TokenStream;
7 #[proc_macro_derive(A)]
8 pub fn derive(input: TokenStream) -> TokenStream {
9 let input = input.to_string();
10 assert!(input.contains("struct A;"));
11 "struct B;".parse().unwrap()