// Demonstrate that having a lifetime param causes dropck to reject code // that might indirectly access previously dropped value. // // Compare with run-pass/issue28498-ugeh-with-lifetime-param.rs #[derive(Debug)] struct ScribbleOnDrop(String); impl Drop for ScribbleOnDrop { fn drop(&mut self) { self.0 = format!("DROPPED"); } } struct Foo<'a>(u32, &'a ScribbleOnDrop); impl<'a> Drop for Foo<'a> { fn drop(&mut self) { // Use of `may_dangle` is unsound, because destructor accesses borrowed data // in `self.1` and we must force that to strictly outlive `self`. 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); }