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use core::ptr::null;
use futures_core::task::{RawWaker, RawWakerVTable, Waker};
unsafe fn clone_panic_waker(_data: *const ()) -> RawWaker {
raw_panic_waker()
}
unsafe fn noop(_data: *const ()) {}
unsafe fn wake_panic(_data: *const ()) {
if !std::thread::panicking() {
panic!("should not be woken");
}
}
const PANIC_WAKER_VTABLE: RawWakerVTable =
RawWakerVTable::new(clone_panic_waker, wake_panic, wake_panic, noop);
const fn raw_panic_waker() -> RawWaker {
RawWaker::new(null(), &PANIC_WAKER_VTABLE)
}
pub fn panic_waker() -> Waker {
unsafe { Waker::from_raw(raw_panic_waker()) }
}
pub fn panic_waker_ref() -> &'static Waker {
struct SyncRawWaker(RawWaker);
unsafe impl Sync for SyncRawWaker {}
static PANIC_WAKER_INSTANCE: SyncRawWaker = SyncRawWaker(raw_panic_waker());
unsafe { &*(&PANIC_WAKER_INSTANCE.0 as *const RawWaker as *const Waker) }
}
#[cfg(test)]
mod tests {
#[test]
#[should_panic(expected = "should not be woken")]
fn issue_2091_cross_thread_segfault() {
let waker = std::thread::spawn(super::panic_waker_ref).join().unwrap();
waker.wake_by_ref();
}
}