4 #![crate_type = "proc-macro"]
6 extern crate proc_macro;
8 use proc_macro::TokenStream;
10 #[proc_macro_derive(A)]
11 pub fn foo(input: TokenStream) -> TokenStream {
15 #[proc_macro_derive(A)] //~ ERROR the name `A` is defined multiple times
16 pub fn bar(input: TokenStream) -> TokenStream {