#![allow(warnings)] struct Wrap<'p> { p: &'p mut i32 } impl<'p> Drop for Wrap<'p> { fn drop(&mut self) { *self.p += 1; } } struct Foo<'p> { a: String, b: Wrap<'p> } fn main() { let mut x = 0; let wrap = Wrap { p: &mut x }; let s = String::from("str"); let foo = Foo { a: s, b: wrap }; std::mem::drop(foo.a); x = 1; //~ ERROR cannot assign to `x` because it is borrowed [E0506] }