mirror of https://github.com/rust-lang/rust
36 lines
1.0 KiB
Rust
36 lines
1.0 KiB
Rust
// Tests correct kind-checking of the reason stack closures without the :Copy
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// bound must be noncopyable. For details see
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// https://smallcultfollowing.com/babysteps/blog/2013/04/30/the-case-of-the-recurring-closure/
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struct R<'a> {
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// This struct is needed to create the
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// otherwise infinite type of a fn that
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// accepts itself as argument:
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c: Box<dyn FnMut(&mut R, bool) + 'a>
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}
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fn innocent_looking_victim() {
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let mut x = Some("hello".to_string());
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conspirator(|f, writer| {
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if writer {
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x = None;
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} else {
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match x {
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Some(ref msg) => {
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(f.c)(f, true);
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//~^ ERROR: cannot borrow `*f` as mutable more than once at a time
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println!("{}", msg);
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},
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None => panic!("oops"),
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}
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}
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})
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}
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fn conspirator<F>(mut f: F) where F: FnMut(&mut R, bool) {
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let mut r = R {c: Box::new(f)};
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f(&mut r, false) //~ ERROR borrow of moved value
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}
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fn main() { innocent_looking_victim() }
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