3 // Demonstrate the use of the unguarded escape hatch with a lifetime param
4 // to assert that destructor will not access any dead data.
6 // Compare with ui/span/issue28498-reject-lifetime-param.rs
8 #![feature(dropck_eyepatch)]
11 struct ScribbleOnDrop(String);
13 impl Drop for ScribbleOnDrop {
15 self.0 = format!("DROPPED");
19 struct Foo<'a>(u32, &'a ScribbleOnDrop);
21 unsafe impl<#[may_dangle] 'a> Drop for Foo<'a> {
23 // Use of `may_dangle` is sound, because destructor never accesses `self.1`.
24 println!("Dropping Foo({}, _)", self.0);
29 let (last_dropped, foo0);
30 let (foo1, first_dropped);
32 last_dropped = ScribbleOnDrop(format!("last"));
33 first_dropped = ScribbleOnDrop(format!("first"));
34 foo0 = Foo(0, &last_dropped);
35 foo1 = Foo(1, &first_dropped);
37 println!("foo0.1: {:?} foo1.1: {:?}", foo0.1, foo1.1);