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@ -104,6 +104,47 @@ mem::forget us in the middle of the iteration, all that does is *leak even more*
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Since we've accepted that mem::forget is safe, this is definitely safe. We call
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Since we've accepted that mem::forget is safe, this is definitely safe. We call
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leaks causing more leaks a *leak amplification*.
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leaks causing more leaks a *leak amplification*.
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Expanding the above example shows that elements remaining in the vector after
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dropping the `drainer` are leaked:
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<!-- ignore: simplified code -->
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```rust
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use std::mem;
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struct Frob {
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v: i32,
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}
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impl Drop for Frob {
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fn drop(&mut self) {
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println!("Frob {{ v: {} }} dropped", self.v)
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}
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}
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fn main() {
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let mut vec = (1..5).map(|v| Frob { v }).collect::<Vec<_>>();
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{
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let mut drainer = vec.drain(..);
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drainer.next();
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drainer.next();
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mem::forget(drainer);
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}
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println!("Goodbye");
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}
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```
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Output:
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```text
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Frob { v: 1 } dropped
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Frob { v: 2 } dropped
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Goodbye
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```
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## Rc
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## Rc
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Rc is an interesting case because at first glance it doesn't appear to be a
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Rc is an interesting case because at first glance it doesn't appear to be a
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