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// edition:2018
fn is_unwindsafe(_: impl std::panic::UnwindSafe) {}
fn main() {
// A normal future created by an async block takes a `&mut Context<'_>` argument.
// That should not leak through to the whole async block.
is_unwindsafe(async {
async {}.await; // this needs an inner await point
});
is_unwindsafe(async {
//~^ ERROR the type `&mut Context<'_>` may not be safely transferred across an unwind boundary
use std::ptr::null;
use std::task::{Context, RawWaker, RawWakerVTable, Waker};
let waker = unsafe {
Waker::from_raw(RawWaker::new(
null(),
&RawWakerVTable::new(|_| todo!(), |_| todo!(), |_| todo!(), |_| todo!()),
))
};
let mut cx = Context::from_waker(&waker);
let cx_ref = &mut cx;
async {}.await; // this needs an inner await point
// in this case, `&mut Context<'_>` is *truly* alive across an await point
drop(cx_ref);
});
}
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