src/test/run-pass/hygiene/wrap_unhygienic_example.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 // run-pass
  12 // ignore-pretty pretty-printing is unhygienic
  13
  14 // aux-build:my_crate.rs
  15 // aux-build:unhygienic_example.rs
  16
  17 #![feature(decl_macro)]
  18
  19 extern crate unhygienic_example;
  20 extern crate my_crate; // (b)
  21
  22 // Hygienic version of `unhygienic_macro`.
  23 pub macro hygienic_macro() {
  24     fn g() {} // (c)
  25     ::unhygienic_example::unhygienic_macro!();
  26     // ^ Even though we invoke an unhygienic macro, `hygienic_macro` remains hygienic.
  27     // In the above expansion:
  28     // (1) `my_crate` always resolves to (b) regardless of invocation site.
  29     // (2) The defined function `f` is only usable inside this macro definition.
  30     // (3) `g` always resolves to (c) regardless of invocation site.
  31     // (4) `$crate::g` remains hygienic and continues to resolve to (a).
  32
  33     f();
  34 }
  35
  36 #[allow(unused)]
  37 fn test_hygienic_macro() {
  38     hygienic_macro!();
  39
  40     fn f() {} // (d) no conflict
  41     f(); // resolves to (d)
  42 }
  43
  44 fn main() {}