386db05df8
Makes labelled loops hygiene by performing renaming of the labels
defined in e.g. `'x: loop { ... }` and then used in break and continue
statements within loop body so that they act hygienically when used with
macros.
Closes #12262.
46 lines
1.2 KiB
Rust
46 lines
1.2 KiB
Rust
// Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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#[feature(macro_rules)];
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macro_rules! loop_x {
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($e: expr) => {
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// $e shouldn't be able to interact with this 'x
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'x: loop { $e }
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}
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}
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macro_rules! run_once {
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($e: expr) => {
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// ditto
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'x: for _ in range(0, 1) { $e }
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}
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}
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pub fn main() {
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'x: for _ in range(0, 1) {
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// this 'x should refer to the outer loop, lexically
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loop_x!(break 'x);
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fail!("break doesn't act hygienically inside for loop");
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}
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'x: loop {
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// ditto
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loop_x!(break 'x);
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fail!("break doesn't act hygienically inside infinite loop");
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}
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'x: for _ in range(0, 1) {
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// ditto
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run_once!(continue 'x);
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fail!("continue doesn't act hygienically inside for loop");
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}
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}
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