// force-host // no-prefer-dynamic #![crate_type = "proc-macro"] extern crate proc_macro; use proc_macro::TokenStream; #[proc_macro_derive(Issue39889)] pub fn f(_input: TokenStream) -> TokenStream { let rules = r#" macro_rules! id { ($($tt:tt)*) => { $($tt)* }; } "#; rules.parse().unwrap() }