// 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(u32, T); impl Drop for Foo { fn drop(&mut self) { // Use of `unsafe_destructor_blind_to_params` 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); }