Drop order of fields?

[Hawk777]

In standard Rust, without anything self-referential, struct fields are dropped in order of declaration:

struct Foo;
impl Drop for Foo {
	fn drop(&mut self) {
		println!("Drop Foo");
	}
}
struct Bar;
impl Drop for Bar {
	fn drop(&mut self) {
		println!("Drop Bar");
	}
}
struct Container {
	foo: Foo,
	bar: Bar,
}
fn main() {
	Container {
		foo: Foo,
		bar: Bar,
	};
}
// Prints “Drop Foo” and then “Drop Bar”

Experimentally, when Ouroboros gets involved, references are dropped before their referents, despite appearing after them in declaration order:

struct Foo;
impl Drop for Foo {
	fn drop(&mut self) {
		println!("Drop Foo");
	}
}
struct Bar<'foo>(&'foo Foo);
impl Drop for Bar<'_> {
	fn drop(&mut self) {
		println!("Drop Bar");
	}
}
#[ouroboros::self_referencing]
struct Container {
	foo: Foo,
	#[borrows(foo)]
	#[covariant]
	bar: Bar<'this>,
}
fn main() {
	ContainerBuilder {
		foo: Foo,
		bar_builder: |foo| Bar(foo)
	}.build();
}
// Prints “Drop Bar” and then “Drop Foo”

This is logical in the sense that a reference must be dropped before its referent; however, it is contrary to the usual drop order of struct fields, and it is also AFAICT not documented anywhere in the Ouroboros documentation. Is the drop order something I can rely on? Should it be documented somewhere?