| #![feature(proc_macro_quote)] | |
| extern crate proc_macro; | |
| use proc_macro::*; | |
| // Outputs another copy of the struct. Useful for testing the tokens | |
| // seen by the proc_macro. | |
| #[proc_macro_derive(Double)] | |
| pub fn derive(input: TokenStream) -> TokenStream { | |
| quote!(mod foo { $input }) | |
| } |