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Update reference safety requirements #125021

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Merged
merged 2 commits into from
May 12, 2024
Merged

Update reference safety requirements #125021

merged 2 commits into from
May 12, 2024

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joshlf
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@joshlf joshlf commented May 11, 2024

Per #116677 (comment), the language as written promises too much. This PR relaxes the language to be consistent with current semantics. If and when #117945 is implemented, we can revert to the old language.

While we're here, we also require that references be non-null.

cc @RalfJung

Per rust-lang#116677 (comment), the language as written promises too much. This PR relaxes the language to be consistent with current semantics. If and when rust-lang#117945 is implemented, we can revert to the old language.
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@rustbot rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-libs Relevant to the library team, which will review and decide on the PR/issue. labels May 11, 2024
@joshlf joshlf changed the title Relax slice safety requirements Relax reference safety requirements May 11, 2024
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This is probably good even with #117945, as it avoids having to explain what "dereferenceable for 0 bytes" means.

But maybe we should add that the reference is non-null? This is always true, and will remain so.

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joshlf commented May 11, 2024

But maybe we should add that the reference is non-null? This is always true, and will remain so.

Updated the PR.

@joshlf joshlf changed the title Relax reference safety requirements Update reference safety requirements May 11, 2024
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Cc @rust-lang/opsem @rust-lang/lang -- I think this just clarifies the existing rules

@bors r+ rollup

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bors commented May 12, 2024

📌 Commit 15df3d7 has been approved by RalfJung

It is now in the queue for this repository.

@bors bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels May 12, 2024
GuillaumeGomez added a commit to GuillaumeGomez/rust that referenced this pull request May 12, 2024
Update reference safety requirements

Per rust-lang#116677 (comment), the language as written promises too much. This PR relaxes the language to be consistent with current semantics. If and when rust-lang#117945 is implemented, we can revert to the old language.

While we're here, we also require that references be non-null.

cc `@RalfJung`
bors added a commit to rust-lang-ci/rust that referenced this pull request May 12, 2024
…llaumeGomez

Rollup of 4 pull requests

Successful merges:

 - rust-lang#124807 (Migrate `run-make/rustdoc-io-error` to `rmake.rs`)
 - rust-lang#125021 (Update reference safety requirements)
 - rust-lang#125030 (Fix some minor issues from the ui-test auto-porting)
 - rust-lang#125036 (solve: all "non-structural" logging to trace)

r? `@ghost`
`@rustbot` modify labels: rollup
bors added a commit to rust-lang-ci/rust that referenced this pull request May 12, 2024
…llaumeGomez

Rollup of 4 pull requests

Successful merges:

 - rust-lang#125021 (Update reference safety requirements)
 - rust-lang#125022 (Migrate rustdoc scrape examples ordering)
 - rust-lang#125030 (Fix some minor issues from the ui-test auto-porting)
 - rust-lang#125036 (solve: all "non-structural" logging to trace)

r? `@ghost`
`@rustbot` modify labels: rollup
@bors bors merged commit 5087947 into rust-lang:master May 12, 2024
6 checks passed
@rustbot rustbot added this to the 1.80.0 milestone May 12, 2024
rust-timer added a commit to rust-lang-ci/rust that referenced this pull request May 12, 2024
Rollup merge of rust-lang#125021 - joshlf:patch-11, r=RalfJung

Update reference safety requirements

Per rust-lang#116677 (comment), the language as written promises too much. This PR relaxes the language to be consistent with current semantics. If and when rust-lang#117945 is implemented, we can revert to the old language.

While we're here, we also require that references be non-null.

cc ``@RalfJung``
@joshlf joshlf deleted the patch-11 branch May 13, 2024 17:19
@joshlf joshlf mentioned this pull request May 13, 2024
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joshlf added a commit to google/zerocopy that referenced this pull request Sep 7, 2024
Now that [1] is completed, zero-sized accesses no longer require
provenance. Per [2], zero-sized references are no longer required to be
dereferenceable, and so may not carry provenance.

This commit updates `Ptr`'s invariants to not require provenance or a
valid allocation when its referent is zero-sized.

[1] rust-lang/rust#117945
[2] rust-lang/rust#125021
joshlf added a commit to google/zerocopy that referenced this pull request Sep 7, 2024
Now that [1] is completed, zero-sized accesses no longer require
provenance. Per [2], zero-sized references are no longer required to be
dereferenceable, and so may not carry provenance.

This commit updates `Ptr`'s invariants to not require provenance or a
valid allocation when its referent is zero-sized.

[1] rust-lang/rust#117945
[2] rust-lang/rust#125021

Closes #874
github-merge-queue bot pushed a commit to google/zerocopy that referenced this pull request Sep 7, 2024
Now that [1] is completed, zero-sized accesses no longer require
provenance. Per [2], zero-sized references are no longer required to be
dereferenceable, and so may not carry provenance.

This commit updates `Ptr`'s invariants to not require provenance or a
valid allocation when its referent is zero-sized.

[1] rust-lang/rust#117945
[2] rust-lang/rust#125021

Closes #874
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5 participants