Tracking Issue for `box_uninit_write` #129397

workingjubilee · 2024-08-22T05:42:04Z

Feature gate: #![feature(box_uninit_write)]

Split-out from #63291 as a result of stabilizing most of its API! It's a way to write to the MaybeUninit on the Box and thus initialize it!

Public API

impl<T, A> Box<MaybeUninit<T>, A> {
    pub fn write(mut boxed: Self, value: T) -> Box<T, A>;
}

Steps / History

Implementation: #...
- honestly have no idea
- related API was added in Tracking issue for uninitialized constructors for Box, Rc, Arc #63291
Final comment period (FCP)¹
Stabilization PR

Unresolved Questions

idk lol

https://std-dev-guide.rust-lang.org/feature-lifecycle/stabilization.html ↩

The text was updated successfully, but these errors were encountered:

…n-of-stabilization, r=<try> Partially stabilize `feature(new_uninit)` Finished comment period: rust-lang#63291 (comment) The following API has been stabilized from rust-lang#63291 ```rust impl<T> Box<T> { pub fn new_uninit() -> Box<MaybeUninit<T>> {…} } impl<T> Rc<T> { pub fn new_uninit() -> Rc<MaybeUninit<T>> {…} } impl<T> Arc<T> { pub fn new_uninit() -> Arc<MaybeUninit<T>> {…} } impl<T> Box<[T]> { pub fn new_uninit_slice(len: usize) -> Box<[MaybeUninit<T>]> {…} } impl<T> Rc<[T]> { pub fn new_uninit_slice(len: usize) -> Rc<[MaybeUninit<T>]> {…} } impl<T> Arc<[T]> { pub fn new_uninit_slice(len: usize) -> Arc<[MaybeUninit<T>]> {…} } impl<T> Box<MaybeUninit<T>> { pub unsafe fn assume_init(self) -> Box<T> {…} } impl<T> Box<[MaybeUninit<T>]> { pub unsafe fn assume_init(self) -> Box<[T]> {…} } impl<T> Rc<MaybeUninit<T>> { pub unsafe fn assume_init(self) -> Rc<T> {…} } impl<T> Rc<[MaybeUninit<T>]> { pub unsafe fn assume_init(self) -> Rc<[T]> {…} } impl<T> Arc<MaybeUninit<T>> { pub unsafe fn assume_init(self) -> Arc<T> {…} } impl<T> Arc<[MaybeUninit<T>]> { pub unsafe fn assume_init(self) -> Arc<[T]> {…} } ``` The remaining API is split between new issues - `new_zeroed_alloc`: rust-lang#129396 - `box_uninit_write`: rust-lang#129397 All relevant code is thus either stabilized or split out of that issue, so this closes rust-lang#63291 as, with the FCP concluded, that issue has served its purpose. try-job: x86_64-rust-for-linux

Upstream Rust's libs-api team has consensus for stabilizing some of `feature(new_uninit)`, but not for `Box<MaybeUninit<T>>::write`. Instead, we can use `MaybeUninit<T>::write`, so Rust for Linux can drop the feature after stabilization. That will happen after merging, as the FCP has completed [1]. This is required before stabilization because remaining-unstable API will be divided into new features. This code doesn't know about those yet. It can't: they haven't landed, as the relevant PR is blocked on rustc's CI testing Rust-for-Linux without this patch. [ The PR has landed [2], so we could conditionally enable the new unstable feature (`box_uninit_write` [3]) instead, but just for a single `unsafe` block it is probably not worth it. For the time being, I added it to the "nice to have" section of our unstable features list. - Miguel ] Link: rust-lang/rust#63291 (comment) [1] Link: rust-lang/rust#129416 [2] Link: rust-lang/rust#129397 [3] Signed-off-by: Jubilee Young <workingjubilee@gmail.com> Reviewed-by: Alice Ryhl <aliceryhl@google.com> Reviewed-by: Trevor Gross <tmgross@umich.edu> [ Reworded slightly. - Miguel ] Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

Upstream Rust's libs-api team has consensus for stabilizing some of `feature(new_uninit)`, but not for `Box<MaybeUninit<T>>::write`. Instead, we can use `MaybeUninit<T>::write`, so Rust for Linux can drop the feature after stabilization. That will happen after merging, as the FCP has completed [1]. This is required before stabilization because remaining-unstable API will be divided into new features. This code doesn't know about those yet. It can't: they haven't landed, as the relevant PR is blocked on rustc's CI testing Rust-for-Linux without this patch. [ The PR has landed [2] and will be released in Rust 1.82.0 (expected on 2024-10-17), so we could conditionally enable the new unstable feature (`box_uninit_write` [3]) instead, but just for a single `unsafe` block it is probably not worth it. For the time being, I added it to the "nice to have" section of our unstable features list. - Miguel ] Link: rust-lang/rust#63291 (comment) [1] Link: rust-lang/rust#129416 [2] Link: rust-lang/rust#129397 [3] Signed-off-by: Jubilee Young <workingjubilee@gmail.com> Reviewed-by: Alice Ryhl <aliceryhl@google.com> Reviewed-by: Trevor Gross <tmgross@umich.edu> [ Reworded slightly. - Miguel ] Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

…ion-of-stabilization, r=dtolnay Partially stabilize `feature(new_uninit)` Finished comment period: rust-lang#63291 (comment) The following API has been stabilized from rust-lang#63291 ```rust impl<T> Box<T> { pub fn new_uninit() -> Box<MaybeUninit<T>> {…} } impl<T> Rc<T> { pub fn new_uninit() -> Rc<MaybeUninit<T>> {…} } impl<T> Arc<T> { pub fn new_uninit() -> Arc<MaybeUninit<T>> {…} } impl<T> Box<[T]> { pub fn new_uninit_slice(len: usize) -> Box<[MaybeUninit<T>]> {…} } impl<T> Rc<[T]> { pub fn new_uninit_slice(len: usize) -> Rc<[MaybeUninit<T>]> {…} } impl<T> Arc<[T]> { pub fn new_uninit_slice(len: usize) -> Arc<[MaybeUninit<T>]> {…} } impl<T> Box<MaybeUninit<T>> { pub unsafe fn assume_init(self) -> Box<T> {…} } impl<T> Box<[MaybeUninit<T>]> { pub unsafe fn assume_init(self) -> Box<[T]> {…} } impl<T> Rc<MaybeUninit<T>> { pub unsafe fn assume_init(self) -> Rc<T> {…} } impl<T> Rc<[MaybeUninit<T>]> { pub unsafe fn assume_init(self) -> Rc<[T]> {…} } impl<T> Arc<MaybeUninit<T>> { pub unsafe fn assume_init(self) -> Arc<T> {…} } impl<T> Arc<[MaybeUninit<T>]> { pub unsafe fn assume_init(self) -> Arc<[T]> {…} } ``` The remaining API is split between new issues - `new_zeroed_alloc`: rust-lang#129396 - `box_uninit_write`: rust-lang#129397 All relevant code is thus either stabilized or split out of that issue, so this closes rust-lang#63291 as, with the FCP concluded, that issue has served its purpose. try-job: x86_64-rust-for-linux

…ion-of-stabilization, r=dtolnay,joboet Partially stabilize `feature(new_uninit)` Finished comment period: rust-lang#63291 (comment) The following API has been stabilized from rust-lang#63291 ```rust impl<T> Box<T> { pub fn new_uninit() -> Box<MaybeUninit<T>> {…} } impl<T> Rc<T> { pub fn new_uninit() -> Rc<MaybeUninit<T>> {…} } impl<T> Arc<T> { pub fn new_uninit() -> Arc<MaybeUninit<T>> {…} } impl<T> Box<[T]> { pub fn new_uninit_slice(len: usize) -> Box<[MaybeUninit<T>]> {…} } impl<T> Rc<[T]> { pub fn new_uninit_slice(len: usize) -> Rc<[MaybeUninit<T>]> {…} } impl<T> Arc<[T]> { pub fn new_uninit_slice(len: usize) -> Arc<[MaybeUninit<T>]> {…} } impl<T> Box<MaybeUninit<T>> { pub unsafe fn assume_init(self) -> Box<T> {…} } impl<T> Box<[MaybeUninit<T>]> { pub unsafe fn assume_init(self) -> Box<[T]> {…} } impl<T> Rc<MaybeUninit<T>> { pub unsafe fn assume_init(self) -> Rc<T> {…} } impl<T> Rc<[MaybeUninit<T>]> { pub unsafe fn assume_init(self) -> Rc<[T]> {…} } impl<T> Arc<MaybeUninit<T>> { pub unsafe fn assume_init(self) -> Arc<T> {…} } impl<T> Arc<[MaybeUninit<T>]> { pub unsafe fn assume_init(self) -> Arc<[T]> {…} } ``` The remaining API is split between new issues - `new_zeroed_alloc`: rust-lang#129396 - `box_uninit_write`: rust-lang#129397 All relevant code is thus either stabilized or split out of that issue, so this closes rust-lang#63291 as, with the FCP concluded, that issue has served its purpose. try-job: x86_64-rust-for-linux

Rollup merge of rust-lang#129401 - workingjubilee:partial-initialization-of-stabilization, r=dtolnay,joboet Partially stabilize `feature(new_uninit)` Finished comment period: rust-lang#63291 (comment) The following API has been stabilized from rust-lang#63291 ```rust impl<T> Box<T> { pub fn new_uninit() -> Box<MaybeUninit<T>> {…} } impl<T> Rc<T> { pub fn new_uninit() -> Rc<MaybeUninit<T>> {…} } impl<T> Arc<T> { pub fn new_uninit() -> Arc<MaybeUninit<T>> {…} } impl<T> Box<[T]> { pub fn new_uninit_slice(len: usize) -> Box<[MaybeUninit<T>]> {…} } impl<T> Rc<[T]> { pub fn new_uninit_slice(len: usize) -> Rc<[MaybeUninit<T>]> {…} } impl<T> Arc<[T]> { pub fn new_uninit_slice(len: usize) -> Arc<[MaybeUninit<T>]> {…} } impl<T> Box<MaybeUninit<T>> { pub unsafe fn assume_init(self) -> Box<T> {…} } impl<T> Box<[MaybeUninit<T>]> { pub unsafe fn assume_init(self) -> Box<[T]> {…} } impl<T> Rc<MaybeUninit<T>> { pub unsafe fn assume_init(self) -> Rc<T> {…} } impl<T> Rc<[MaybeUninit<T>]> { pub unsafe fn assume_init(self) -> Rc<[T]> {…} } impl<T> Arc<MaybeUninit<T>> { pub unsafe fn assume_init(self) -> Arc<T> {…} } impl<T> Arc<[MaybeUninit<T>]> { pub unsafe fn assume_init(self) -> Arc<[T]> {…} } ``` The remaining API is split between new issues - `new_zeroed_alloc`: rust-lang#129396 - `box_uninit_write`: rust-lang#129397 All relevant code is thus either stabilized or split out of that issue, so this closes rust-lang#63291 as, with the FCP concluded, that issue has served its purpose. try-job: x86_64-rust-for-linux

…abilization, r=dtolnay,joboet Partially stabilize `feature(new_uninit)` Finished comment period: rust-lang/rust#63291 (comment) The following API has been stabilized from rust-lang/rust#63291 ```rust impl<T> Box<T> { pub fn new_uninit() -> Box<MaybeUninit<T>> {…} } impl<T> Rc<T> { pub fn new_uninit() -> Rc<MaybeUninit<T>> {…} } impl<T> Arc<T> { pub fn new_uninit() -> Arc<MaybeUninit<T>> {…} } impl<T> Box<[T]> { pub fn new_uninit_slice(len: usize) -> Box<[MaybeUninit<T>]> {…} } impl<T> Rc<[T]> { pub fn new_uninit_slice(len: usize) -> Rc<[MaybeUninit<T>]> {…} } impl<T> Arc<[T]> { pub fn new_uninit_slice(len: usize) -> Arc<[MaybeUninit<T>]> {…} } impl<T> Box<MaybeUninit<T>> { pub unsafe fn assume_init(self) -> Box<T> {…} } impl<T> Box<[MaybeUninit<T>]> { pub unsafe fn assume_init(self) -> Box<[T]> {…} } impl<T> Rc<MaybeUninit<T>> { pub unsafe fn assume_init(self) -> Rc<T> {…} } impl<T> Rc<[MaybeUninit<T>]> { pub unsafe fn assume_init(self) -> Rc<[T]> {…} } impl<T> Arc<MaybeUninit<T>> { pub unsafe fn assume_init(self) -> Arc<T> {…} } impl<T> Arc<[MaybeUninit<T>]> { pub unsafe fn assume_init(self) -> Arc<[T]> {…} } ``` The remaining API is split between new issues - `new_zeroed_alloc`: rust-lang/rust#129396 - `box_uninit_write`: rust-lang/rust#129397 All relevant code is thus either stabilized or split out of that issue, so this closes #63291 as, with the FCP concluded, that issue has served its purpose. try-job: x86_64-rust-for-linux

Like commit 0903b9e ("rust: alloc: eschew `Box<MaybeUninit<T>>::write`"), but for the new `rbtree` code. That is, `feature(new_uninit)` [1] got partially stabilized [2] for Rust 1.82.0 (expected to be released on 2024-10-17), but it did not include `Box<MaybeUninit<T>>::write`, which got split into `feature(box_uninit_write)` [3]. To avoid relying on a new unstable feature, rewrite the `write` + `assume_init` pair manually. Link: rust-lang/rust#63291 [1] Link: rust-lang/rust#129401 [2] Link: rust-lang/rust#129397 [3] Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

Like commit 0903b9e ("rust: alloc: eschew `Box<MaybeUninit<T>>::write`"), but for the new `rbtree` and `alloc` code. That is, `feature(new_uninit)` [1] got partially stabilized [2] for Rust 1.82.0 (expected to be released on 2024-10-17), but it did not include `Box<MaybeUninit<T>>::write`, which got split into `feature(box_uninit_write)` [3]. To avoid relying on a new unstable feature, rewrite the `write` + `assume_init` pair manually. Link: rust-lang/rust#63291 [1] Link: rust-lang/rust#129401 [2] Link: rust-lang/rust#129397 [3] Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

Like commit 0903b9e ("rust: alloc: eschew `Box<MaybeUninit<T>>::write`"), but for the new `rbtree` and `alloc` code. That is, `feature(new_uninit)` [1] got partially stabilized [2] for Rust 1.82.0 (expected to be released on 2024-10-17), but it did not include `Box<MaybeUninit<T>>::write`, which got split into `feature(box_uninit_write)` [3]. To avoid relying on a new unstable feature, rewrite the `write` + `assume_init` pair manually. Link: rust-lang/rust#63291 [1] Link: rust-lang/rust#129401 [2] Link: rust-lang/rust#129397 [3] Reviewed-by: Alice Ryhl <aliceryhl@google.com> Reviewed-by: Matt Gilbride <mattgilbride@google.com> Link: https://lore.kernel.org/r/20240904144229.18592-1-ojeda@kernel.org Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

workingjubilee added T-libs-api Relevant to the library API team, which will review and decide on the PR/issue. C-tracking-issue Category: A tracking issue for an RFC or an unstable feature. labels Aug 22, 2024

This was referenced Aug 22, 2024

Partially stabilize feature(new_uninit) #129401

Merged

library: Move unstable API of new_uninit to new features #129416

Merged

ojeda mentioned this issue Aug 24, 2024

Rust unstable features needed for the kernel Rust-for-Linux/linux#2

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lolbinarycat added the F-box_uninit_write label Sep 3, 2024

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Tracking Issue for `box_uninit_write` #129397

Tracking Issue for `box_uninit_write` #129397

workingjubilee commented Aug 22, 2024 •

edited

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Tracking Issue for box_uninit_write #129397

Tracking Issue for box_uninit_write #129397

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workingjubilee commented Aug 22, 2024 • edited Loading

Public API

Steps / History

Unresolved Questions

Footnotes

Tracking Issue for `box_uninit_write` #129397

Tracking Issue for `box_uninit_write` #129397

workingjubilee commented Aug 22, 2024 •

edited

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