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cell-refcell-rc

 1 year ago
source link: https://gist.github.com/jonhoo/7cfdfe581e5108b79c2a4e9fbde38de8
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cell-refcell-rc · GitHub

Hi, Jon, Great great tutorial! love it.

One question:

// TODO: #[may_dangle]
impl<T> Drop for Rc<T> {
    fn drop(&mut self) {
        let inner = unsafe { self.inner.as_ref() };
        let c = inner.refcount.get();
        if c == 1 {
            drop(inner);
            // SAFETY: we are the _only_ Rc left, and we are being dropped.
            // therefore, after us, there will be no Rc's, and no references to T.
            let _ = unsafe { Box::from_raw(self.inner.as_ptr()) };
        } else {
            // there are other Rcs, so don't drop the Box!
            inner.refcount.set(c - 1);
        }
    }
}

why this one have a may_dangle issue?


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