// force-host // no-prefer-dynamic #![feature(proc_macro_quote)] #![crate_type = "proc-macro"] 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 }) }