Tracking Issue for smart pointer (try_)map

Feature gate: #![feature(smart_pointer_try_map)]

This is a tracking issue for map and try_map functions for various smart pointer types, as per rust-lang/libs-team#364

Public API

// Taking T by value
impl Box<T> {
    fn map<U>(this: Self, f: impl FnOnce(T) -> U) -> Box<U>;
    fn try_map<R>(this: Self, f: impl FnOnce(T) -> R) -> ChangeOutputType<R, Box<R::Output>>
    where
        R: Try,
        R::Residual: Residual<Box<R::Output, A>>;
}
impl UniqueRc<T> {
    fn map<U>(this: Self, f: impl FnOnce(T) -> U) -> UniqueRc<U>;
    fn try_map<R>(this: Self, f: impl FnOnce(T) -> R) -> ChangeOutputType<R, UniqueRc<R::Output>>
    where
        R: Try,
        R::Residual: Residual<UniqueRc<R::Output, A>>;
}
impl UniqueArc<T> {
    fn map<U>(this: Self, f: impl FnOnce(T) -> U) -> UniqueArc<U>;
    fn try_map<R>(this: Self, f: impl FnOnce(T) -> R) -> ChangeOutputType<R, UniqueArc<R::Output>>
    where
        R: Try,
        R::Residual: Residual<UniqueArc<R::Output, A>>;
}

// Taking T by reference
impl Rc<T> {
    fn map<U>(this: Self, f: impl FnOnce(&T) -> U) -> Rc<U>;
    fn try_map<R>(this: Self, f: impl FnOnce(&T) -> R) -> ChangeOutputType<R, Rc<R::Output>>
    where
        R: Try,
        R::Residual: Residual<Rc<R::Output, A>>;
}
impl Arc<T> {
    fn map<U>(this: Self, f: impl FnOnce(&T) -> U) -> Arc<<U>;
    fn try_map<R>(this: Self, f: impl FnOnce(&T) -> R) -> ChangeOutputType<R, Arc<<R::Output>>
    where
        R: Try,
        R::Residual: Residual<Arc<R::Output, A>>;
}

Steps / History

(Remember to update the S-tracking-* label when checking boxes.)

• Implementation: #144420
• Final comment period (FCP)^1
• Stabilization PR

Unresolved Questions

• https://github.com/rust-lang/libs-team/issues/364#issuecomment-2807698663

Start with the public API listed in this issue and implementation PR #144420, then review the unresolved question linked from the issue. The remaining work is the final comment period and stabilization PR; done means the API has completed that stabilization process.