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// Demonstrate that a type param in negative position causes dropck to reject code
// that might indirectly access previously dropped value.
//
// Compare with run-pass/issue28498-ugeh-with-passed-to-fn.rs
#[derive(Debug)]
struct ScribbleOnDrop(String);
impl Drop for ScribbleOnDrop {
fn drop(&mut self) {
self.0 = format!("DROPPED");
}
}
struct Foo<T>(u32, T, Box<for <'r> fn(&'r T) -> String>);
impl<T> Drop for Foo<T> {
fn drop(&mut self) {
// Use of `may_dangle` is unsound, because we pass `T` to the callback in `self.2`
// below, and thus potentially read from borrowed data.
println!("Dropping Foo({}, {})", self.0, (self.2)(&self.1));
}
}
fn callback(s: & &ScribbleOnDrop) -> String { format!("{:?}", s) }
fn main() {
let (last_dropped, foo0);
let (foo1, first_dropped);
last_dropped = ScribbleOnDrop(format!("last"));
first_dropped = ScribbleOnDrop(format!("first"));
foo0 = Foo(0, &last_dropped, Box::new(callback)); // OK
foo1 = Foo(1, &first_dropped, Box::new(callback));
//~^ ERROR `first_dropped` does not live long enough
println!("foo0.1: {:?} foo1.1: {:?}", foo0.1, foo1.1);
}
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