mirror of
https://github.com/rust-lang/rust
synced 2024-11-05 20:45:15 +00:00
43 lines
1.2 KiB
Rust
43 lines
1.2 KiB
Rust
#![feature(coroutines)]
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#![feature(coroutine_clone)]
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#![feature(coroutine_trait)]
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#![feature(rustc_attrs, stmt_expr_attributes)]
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use std::ops::Coroutine;
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use std::pin::Pin;
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fn copy<T: Copy>(x: T) -> T {
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x
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}
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fn main() {
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let mut g = #[coroutine]
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|| {
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// This is desuraged as 4 stages:
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// - allocate a `*mut u8` with `exchange_malloc`;
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// - create a Box that is ignored for trait computations;
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// - compute fields (and yields);
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// - assign to `t`.
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let t = #[rustc_box]
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Box::new((5, yield));
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drop(t);
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};
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// Allocate the temporary box.
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Pin::new(&mut g).resume(());
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// The temporary box is in coroutine locals.
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// As it is not taken into account for trait computation,
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// the coroutine is `Copy`.
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let mut h = copy(g);
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//~^ ERROR the trait bound `Box<(i32, ())>: Copy` is not satisfied in
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// We now have 2 boxes with the same backing allocation:
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// one inside `g` and one inside `h`.
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// Proceed and drop `t` in `g`.
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Pin::new(&mut g).resume(());
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//~^ ERROR borrow of moved value: `g`
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// Proceed and drop `t` in `h` -> double free!
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Pin::new(&mut h).resume(());
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}
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