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// Demonstrate that having a trait bound causes dropck to reject code
// that might indirectly access previously dropped value.
//
// Compare with run-pass/issue28498-ugeh-with-trait-bound.rs
use std::fmt;
#[derive(Debug)]
struct ScribbleOnDrop(String);
impl Drop for ScribbleOnDrop {
fn drop(&mut self) {
self.0 = format!("DROPPED");
}
}
struct Foo<T: fmt::Debug>(u32, T);
impl<T: fmt::Debug> Drop for Foo<T> {
fn drop(&mut self) {
// Use of `may_dangle` is unsound, because we access `T` fmt method when we pass
// `self.1` below, and thus potentially read from borrowed data.
println!("Dropping Foo({}, {:?})", self.0, self.1);
}
}
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); // OK
foo1 = Foo(1, &first_dropped);
//~^ ERROR `first_dropped` does not live long enough
println!("foo0.1: {:?} foo1.1: {:?}", foo0.1, foo1.1);
}
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