|  | //@ compile-flags:--test | 
|  |  | 
|  | // comments, both doc comments and regular ones, used to trick rustdoc's doctest parser into | 
|  | // thinking that everything after it was part of the regular program. combined with the librustc_ast | 
|  | // parser loop failing to detect the manual main function, it would wrap everything in `fn main`, | 
|  | // which would cause the doctest to fail as the "extern crate" declaration was no longer valid. | 
|  | // oddly enough, it would pass in 2018 if a crate was in the extern prelude. see | 
|  | // https://github.com/rust-lang/rust/issues/56727 | 
|  |  | 
|  | //! ``` | 
|  | //! // crate: proc-macro-test | 
|  | //! //! this is a test | 
|  | //! | 
|  | //! // used to pull in proc-macro specific items | 
|  | //! extern crate proc_macro; | 
|  | //! | 
|  | //! use proc_macro::TokenStream; | 
|  | //! | 
|  | //! # fn main() {} | 
|  | //! ``` |