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RalfJung opened this issue Jan 8, 2025 · 1 comment
Open
1 of 4 tasks

Tracking Issue for nonnull_provenance #135243

RalfJung opened this issue Jan 8, 2025 · 1 comment
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C-tracking-issue Category: An issue tracking the progress of sth. like the implementation of an RFC T-libs-api Relevant to the library API team, which will review and decide on the PR/issue.

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@RalfJung
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RalfJung commented Jan 8, 2025 •
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Feature gate: #![feature(nonnull_provenance)]

This is a tracking issue for some provenance functions on NonNull that were missed in the initial strict provenance stabilization.

Public API

// core::ptr

impl<T> NonNull<T> {
    pub const fn without_provenance(addr: NonZero<usize>) -> Self;
    pub fn from_exposed_provenance(addr: NonZero<usize>) -> Self;
}
impl<T: ?Sized> NonNull<T> {
    pub fn expose_provenance(self) -> NonZero<usize>;
}

Steps / History

Unresolved Questions

  • None yet.

Footnotes

  1. https://std-dev-guide.rust-lang.org/feature-lifecycle/stabilization.html ↩
@RalfJung RalfJung added C-tracking-issue Category: An issue tracking the progress of sth. like the implementation of an RFC T-libs-api Relevant to the library API team, which will review and decide on the PR/issue. labels Jan 8, 2025
This was referenced Jan 8, 2025
Closed
Merged
matthiaskrgr added a commit to matthiaskrgr/rust that referenced this issue Jan 9, 2025
@matthiaskrgr
Rollup merge of rust-lang#135242 - RalfJung:nonnull-provenance, r=jhp…
04e8715 
…ratt

add missing provenance APIs on NonNull

This adds some provenance APIs that exist on raw pointers but have been forgotten on `NonNull`:
```rust
impl<T> NonNull<T> {
    pub const fn without_provenance(addr: NonZero<usize>) -> Self;
    pub fn from_exposed_provenance(addr: NonZero<usize>) -> Self;
}
impl<T: ?Sized> NonNull<T> {
    pub fn expose_provenance(self) -> NonZero<usize>;
}
```
rust-lang/libs-team#518 is the ACP for the two exposed provenance ones; I forgot to include `without_provenance` there but I hope that, too, is uncontroversial (and anyway this PR only adds things unstably). Cc `@rust-lang/libs-api`

Tracking issue: rust-lang#135243
jhpratt added a commit to jhpratt/rust that referenced this issue Jan 9, 2025
@jhpratt
Rollup merge of rust-lang#135242 - RalfJung:nonnull-provenance, r=jhp…
225dc79 
…ratt

add missing provenance APIs on NonNull

This adds some provenance APIs that exist on raw pointers but have been forgotten on `NonNull`:
```rust
impl<T> NonNull<T> {
    pub const fn without_provenance(addr: NonZero<usize>) -> Self;
    pub fn from_exposed_provenance(addr: NonZero<usize>) -> Self;
}
impl<T: ?Sized> NonNull<T> {
    pub fn expose_provenance(self) -> NonZero<usize>;
}
```
rust-lang/libs-team#518 is the ACP for the two exposed provenance ones; I forgot to include `without_provenance` there but I hope that, too, is uncontroversial (and anyway this PR only adds things unstably). Cc ``@rust-lang/libs-api``

Tracking issue: rust-lang#135243
rust-timer added a commit to rust-lang-ci/rust that referenced this issue Jan 9, 2025
@rust-timer
Unrolled build for rust-lang#135242
aeb332d 
Rollup merge of rust-lang#135242 - RalfJung:nonnull-provenance, r=jhpratt

add missing provenance APIs on NonNull

This adds some provenance APIs that exist on raw pointers but have been forgotten on `NonNull`:
```rust
impl<T> NonNull<T> {
    pub const fn without_provenance(addr: NonZero<usize>) -> Self;
    pub fn from_exposed_provenance(addr: NonZero<usize>) -> Self;
}
impl<T: ?Sized> NonNull<T> {
    pub fn expose_provenance(self) -> NonZero<usize>;
}
```
rust-lang/libs-team#518 is the ACP for the two exposed provenance ones; I forgot to include `without_provenance` there but I hope that, too, is uncontroversial (and anyway this PR only adds things unstably). Cc `@rust-lang/libs-api`

Tracking issue: rust-lang#135243
@scottmcm scottmcm mentioned this issue Jan 10, 2025
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@scottmcm
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This without_provenance taking NonZero is beautiful, since it means that code (in Rc) that used to be NonNull::new_unchecked(ptr::without_provenance(MAX)) can now be safe 👍

@scottmcm scottmcm mentioned this issue Jan 10, 2025
Merged
@samueltardieu samueltardieu mentioned this issue Jan 10, 2025
Merged
jhpratt added a commit to jhpratt/rust that referenced this issue Jan 11, 2025
@jhpratt
Rollup merge of rust-lang#135347 - samueltardieu:push-qvyxtxsqyxyr, r…
46222ce 
…=jhpratt

Use `NonNull::without_provenance` within the standard library

This API removes the need for several `unsafe` blocks, and leads to clearer code. It uses feature `nonnull_provenance` (rust-lang#135243).

Close rust-lang#135343
rust-timer added a commit to rust-lang-ci/rust that referenced this issue Jan 11, 2025
@rust-timer
Unrolled build for rust-lang#135347
c98ed1b 
Rollup merge of rust-lang#135347 - samueltardieu:push-qvyxtxsqyxyr, r=jhpratt

Use `NonNull::without_provenance` within the standard library

This API removes the need for several `unsafe` blocks, and leads to clearer code. It uses feature `nonnull_provenance` (rust-lang#135243).

Close rust-lang#135343
bors added a commit to rust-lang-ci/rust that referenced this issue Jan 14, 2025
@bors
Auto merge of rust-lang#135344 - scottmcm:safe-dangling, r=<try>
f97ac68 
Less unsafe in `dangling`/`without_provenance`

This PR was inspired by the new `NonNull::without_provenance` (cc rust-lang#135243 (comment)) since it made me realize that we could write `NonNull::dangling` in completely-safe code using other existing things.

Then doing that led me to a few more places that could be simplified, like now that GVN will optimize Transmute-then-PtrToPtr, we can just implement `ptr::without_provenance` by calling `ptr::without_provenance_mut` since the shipped rlib of `core` ends up with the same single statement as the implementation (thanks to GVN merging the steps) and thus there's no need to duplicate the `transmute` -- and more importantly, no need to repeat a long safety comment.

There did end up being a couple of other changes needed to avoid exploding certain bits of MIR, though -- like `<Box<[i32]>>::default()`'s MIR originally got way worse as certain things didn't inline, or had a bunch of extraneous UbChecks -- so there's a couple of other changes to solve that.
bors added a commit to rust-lang-ci/rust that referenced this issue Jan 15, 2025
@bors
Auto merge of rust-lang#135344 - scottmcm:safe-dangling, r=joboet
cfa4bd0 
Less unsafe in `dangling`/`without_provenance`

This PR was inspired by the new `NonNull::without_provenance` (cc rust-lang#135243 (comment)) since it made me realize that we could write `NonNull::dangling` in completely-safe code using other existing things.

Then doing that led me to a few more places that could be simplified, like now that GVN will optimize Transmute-then-PtrToPtr, we can just implement `ptr::without_provenance` by calling `ptr::without_provenance_mut` since the shipped rlib of `core` ends up with the same single statement as the implementation (thanks to GVN merging the steps) and thus there's no need to duplicate the `transmute` -- and more importantly, no need to repeat a long safety comment.

There did end up being a couple of other changes needed to avoid exploding certain bits of MIR, though -- like `<Box<[i32]>>::default()`'s MIR originally got way worse as certain things didn't inline, or had a bunch of extraneous UbChecks -- so there's a couple of other changes to solve that.
bors added a commit to rust-lang-ci/rust that referenced this issue Jan 16, 2025
@bors
Auto merge of rust-lang#135344 - scottmcm:safe-dangling, r=joboet
d8a6409 
Less unsafe in `dangling`/`without_provenance`

This PR was inspired by the new `NonNull::without_provenance` (cc rust-lang#135243 (comment)) since it made me realize that we could write `NonNull::dangling` in completely-safe code using other existing things.

Then doing that led me to a few more places that could be simplified, like now that GVN will optimize Transmute-then-PtrToPtr, we can just implement `ptr::without_provenance` by calling `ptr::without_provenance_mut` since the shipped rlib of `core` ends up with the same single statement as the implementation (thanks to GVN merging the steps) and thus there's no need to duplicate the `transmute` -- and more importantly, no need to repeat a long safety comment.

There did end up being a couple of other changes needed to avoid exploding certain bits of MIR, though -- like `<Box<[i32]>>::default()`'s MIR originally got way worse as certain things didn't inline, or had a bunch of extraneous UbChecks -- so there's a couple of other changes to solve that.
github-actions bot pushed a commit to tautschnig/verify-rust-std that referenced this issue Mar 11, 2025
@matthiaskrgr
Rollup merge of rust-lang#135242 - RalfJung:nonnull-provenance, r=jhp…
5d599f8 
…ratt

add missing provenance APIs on NonNull

This adds some provenance APIs that exist on raw pointers but have been forgotten on `NonNull`:
```rust
impl<T> NonNull<T> {
    pub const fn without_provenance(addr: NonZero<usize>) -> Self;
    pub fn from_exposed_provenance(addr: NonZero<usize>) -> Self;
}
impl<T: ?Sized> NonNull<T> {
    pub fn expose_provenance(self) -> NonZero<usize>;
}
```
rust-lang/libs-team#518 is the ACP for the two exposed provenance ones; I forgot to include `without_provenance` there but I hope that, too, is uncontroversial (and anyway this PR only adds things unstably). Cc `@rust-lang/libs-api`

Tracking issue: rust-lang#135243
github-actions bot pushed a commit to tautschnig/verify-rust-std that referenced this issue Mar 11, 2025
@jhpratt
Rollup merge of rust-lang#135347 - samueltardieu:push-qvyxtxsqyxyr, r…
453a0d0 
…=jhpratt

Use `NonNull::without_provenance` within the standard library

This API removes the need for several `unsafe` blocks, and leads to clearer code. It uses feature `nonnull_provenance` (rust-lang#135243).

Close rust-lang#135343
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