Fixed LateInit example stack overflow

src/lib.rs

@@ -206,6 +206,8 @@
 //!
 //!
 //! ```
+//! use std::fmt;
+//!
 //! use once_cell::sync::OnceCell;
 //!
 //! #[derive(Debug)]
@@ -228,16 +230,28 @@
 //!     }
 //! }
 //!
-//! #[derive(Default, Debug)]
+//! #[derive(Default)]
 //! struct A<'a> {
 //!     b: LateInit<&'a B<'a>>,
 //! }
 //!
-//! #[derive(Default, Debug)]
+//! #[derive(Default)]
 //! struct B<'a> {
 //!     a: LateInit<&'a A<'a>>
 //! }
 //!
+//! impl fmt::Debug for A<'_> {
+//!     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+//!         write!(f, "A")
+//!     }
+//! }
+//!
+//! impl fmt::Debug for B<'_> {
+//!     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+//!         write!(f, "B")
+//!     }
+//! }
+//!
 //! fn build_cycle() {
 //!     let a = A::default();
 //!     let b = B::default();
@@ -314,9 +328,9 @@
 //! **Does this crate support async?**
 //!
 //! No, but you can use [`async_once_cell`](https://crates.io/crates/async_once_cell) instead.
-//! 
+//!
 //! **Can I bring my own mutex?**
-//! 
+//!
 //! There is [generic_once_cell](https://crates.io/crates/generic_once_cell) to allow just that.
 //!
 //! # Related crates