tests/rustdoc-gui/src/proc_macro_test/lib.rs

use proc_macro::TokenStream;

#[proc_macro]
pub fn make_answer(_item: TokenStream) -> TokenStream {
    "fn answer() -> u32 { 42 }".parse().unwrap()
}

#[proc_macro_derive(HelperAttr, attributes(helper))]
pub fn derive_helper_attr(_item: TokenStream) -> TokenStream {
    TokenStream::new()
}