// core::cell (in core/src/cell/lazy.rs) pub struct LazyCell<T, F = fn() -> T> { /* ... */ } impl<T, F: FnOnce() -> T> LazyCell<T, F> { pub const fn new(init: F) -> LazyCell<T, F>; pub fn force(this: &LazyCell<T, F>) -> &T; } impl<T, F: FnOnce() -> T> Deref for LazyCell<T, F> { type Target = T; } impl<T: Default> Default for LazyCell<T>; impl<T: fmt::Debug, F> fmt::Debug for LazyCell<T, F>;

// std::sync (in std/sync/lazy_lock.rs) pub struct LazyLock<T, F = fn() -> T> { /* ... */ } impl<T, F: FnOnce() -> T> LazyLock<T, F> { pub const fn new(f: F) -> LazyLock<T, F>; pub fn force(this: &LazyLock<T, F>) -> &T; } impl<T, F> Drop for LazyLock<T, F>; impl<T, F: FnOnce() -> T> Deref for LazyLock<T, F> { type Target = T; } impl<T: Default> Default for LazyLock<T>; impl<T: fmt::Debug, F> fmt::Debug for LazyLock<T, F>; // We never create a `&F` from a `&LazyLock<T, F>` so it is fine // to not impl `Sync` for `F` unsafe impl<T: Sync + Send, F: Send> Sync for LazyLock<T, F>; // auto-derived `Send` impl is OK. impl<T: RefUnwindSafe + UnwindSafe, F: UnwindSafe> RefUnwindSafe for LazyLock<T, F>; impl<T: UnwindSafe, F: UnwindSafe> UnwindSafe for LazyLock<T, F>;