test/unit/pipelined_compilation/my_macro.rs - third_party/github.com/bazelbuild/rules_rust - Git at Google

 use proc_macro::TokenStream;

 #[proc_macro_attribute]
 pub fn noop(_attr: TokenStream, item: TokenStream) -> TokenStream {
     item
 }
	use proc_macro::TokenStream;

	#[proc_macro_attribute]
	pub fn noop(_attr: TokenStream, item: TokenStream) -> TokenStream {
	item
	}