252d17a07c
It's unclear to me why these currently aren't allowed, and my best guess is that a long time ago we didn't strip the ast of cfg nodes before syntax expansion. Now that this is done, I'm not certain that we should continue to prohibit this functionality. This is a step in the right direction towards #5605, because now we can add an empty `std::macros` module to the documentation with a bunch of empty macros explaining how they're supposed to be used.
23 lines
630 B
Rust
23 lines
630 B
Rust
// Copyright 2013 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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#[cfg(foo)]
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macro_rules! foo( () => (1) )
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#[cfg(not(foo))]
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macro_rules! foo( () => (2) )
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pub fn main() {
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assert_eq!(foo!(), 2);
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}
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