src/test/run-pass-fulldeps/proc-macro/auxiliary/hygiene_example_codegen.rs

   1 // Copyright 2017 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 // no-prefer-dynamic
  12
  13 #![feature(proc_macro_quote, proc_macro_hygiene)]
  14 #![crate_type = "proc-macro"]
  15
  16 extern crate proc_macro as proc_macro_renamed; // This does not break `quote!`
  17
  18 use proc_macro_renamed::{TokenStream, quote};
  19
  20 #[proc_macro]
  21 pub fn hello(input: TokenStream) -> TokenStream {
  22     quote!(hello_helper!($input))
  23     //^ `hello_helper!` always resolves to the following proc macro,
  24     //| no matter where `hello!` is used.
  25 }
  26
  27 #[proc_macro]
  28 pub fn hello_helper(input: TokenStream) -> TokenStream {
  29     quote! {
  30         extern crate hygiene_example; // This is never a conflict error
  31         let string = format!("hello {}", $input);
  32         //^ `format!` always resolves to the prelude macro,
  33         //| even if a different `format!` is in scope where `hello!` is used.
  34         hygiene_example::print(&string)
  35     }
  36 }