src/test/run-pass/hygienic-labels.rs

   1 // Copyright 2012-2014 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 // Test that labels injected by macros do not break hygiene.
  12
  13 // Issue #24278: The label/lifetime shadowing checker from #24162
  14 // conservatively ignores hygiene, and thus issues warnings that are
  15 // both true- and false-positives for this test.
  16
  17 macro_rules! loop_x {
  18     ($e: expr) => {
  19         // $e shouldn't be able to interact with this 'x
  20         'x: loop { $e }
  21     }
  22 }
  23
  24 macro_rules! run_once {
  25     ($e: expr) => {
  26         // ditto
  27         'x: for _ in 0..1 { $e }
  28     }
  29 }
  30
  31 macro_rules! while_x {
  32     ($e: expr) => {
  33         // ditto
  34         'x: while 1 + 1 == 2 { $e }
  35     }
  36 }
  37
  38 pub fn main() {
  39     'x: for _ in 0..1 {
  40         // this 'x should refer to the outer loop, lexically
  41         loop_x!(break 'x);
  42         panic!("break doesn't act hygienically inside for loop");
  43     }
  44
  45     'x: loop {
  46         // ditto
  47         loop_x!(break 'x);
  48         panic!("break doesn't act hygienically inside infinite loop");
  49     }
  50
  51     'x: while 1 + 1 == 2 {
  52         while_x!(break 'x);
  53         panic!("break doesn't act hygienically inside infinite while loop");
  54     }
  55
  56     'x: for _ in 0..1 {
  57         // ditto
  58         run_once!(continue 'x);
  59         panic!("continue doesn't act hygienically inside for loop");
  60     }
  61 }