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make raw_eq precondition more restrictive - #99511

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RalfJung:raw_eq
Aug 12, 2022
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make raw_eq precondition more restrictive#99511
bors merged 4 commits into
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RalfJung:raw_eq

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@RalfJung

@RalfJungRalfJung commented Jul 20, 2022•
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Specifically, don't allow comparing pointers that way. Comparing pointers is subtle because you have to talk about what happens to the provenance.

This matches what Miri already implements, and all existing users are fine with this.

If raw_eq on pointers is ever desired, we can adjust the intrinsic spec and Miri implementation as needed, but for now that seems just unnecessary. Also, this is a const intrinsic, and in const, comparing pointers this way is not possible -- so if we allow the intrinsic to compare pointers in general, we need to impose an extra restrictions saying that in const-context, pointers are not okay.

@rustbotrustbot added the T-libs Relevant to the library team, which will review and decide on the PR/issue. label Jul 20, 2022
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Hey! It looks like you've submitted a new PR for the library teams!

If this PR contains changes to any rust-lang/rust public library APIs then please comment with @rustbot label +T-libs-api -T-libs to tag it appropriately. If this PR contains changes to any unstable APIs please edit the PR description to add a link to the relevant API Change Proposal or create one if you haven't already. If you're unsure where your change falls no worries, just leave it as is and the reviewer will take a look and make a decision to forward on if necessary.

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  • Changing public documentation in ways that create new stability guarantees
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r? @joshtriplett

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@rust-highfiverust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Jul 20, 2022
mcol
mcol reviewed Jul 20, 2022
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Comment threadlibrary/core/src/array/equality.rs Outdated
@RalfJung@mcol
fix typo
2d1c683
Co-authored-by: Marco Colombo <mar.colombo13@gmail.com>
@RalfJung

RalfJung commented Aug 3, 2022

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14 days without review, let's re-roll the dice...
r? compiler
(since it's just an intrinsic)

steffahn
steffahn reviewed Aug 10, 2022
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Comment threadlibrary/core/src/intrinsics.rs Outdated
@RalfJung@steffahn
grammar
d1cace5
Co-authored-by: Frank Steffahn <fdsteffahn@gmail.com>
nnethercote
nnethercote reviewed Aug 11, 2022
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Comment threadlibrary/core/src/array/equality.rs Outdated
@RalfJung@nnethercote
more typos
338d7c2
Co-authored-by: Nicholas Nethercote <n.nethercote@gmail.com>
wesleywiser
wesleywiser approved these changes Aug 11, 2022
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Is there anything we should do to advertise that the safety invariant (at least, as documented) on this intrinsic has been updated?

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wesleywiser commented Aug 11, 2022

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@bors r+ rollup

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bors commented Aug 11, 2022

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📌 Commit 338d7c2 has been approved by wesleywiser

It is now in the queue for this repository.

@borsbors 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 Aug 11, 2022
@RalfJung

RalfJung commented Aug 11, 2022

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Is there anything we should do to advertise that the safety invariant (at least, as documented) on this intrinsic has been updated?

I don't think so. It's an intrinsic, and a relatively obscure one.

@matthiaskrgrmatthiaskrgr mentioned this pull request Aug 11, 2022
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bors added a commit to rust-lang-ci/rust that referenced this pull request Aug 11, 2022
@bors
Auto merge ofrust-lang#100426- matthiaskrgr:rollup-0ks4dou, r=matth…
2ed0f29
…iaskrgr
Rollup of 13 pull requests
Successful merges:
- rust-lang#93896 (rustdoc: make item-infos dimmer on dark theme)
- rust-lang#99337 (rustdoc: simplify highlight.rs)
- rust-lang#99421 (add crt-static for android)
- rust-lang#99500 (Fix flags when using clang as linker for Fuchsia)
- rust-lang#99511 (make raw_eq precondition more restrictive)
- rust-lang#99992 (Add `x.sh` and `x.ps1` shell scripts)
- rust-lang#100112 (Fix test: chunks_mut_are_send_and_sync)
- rust-lang#100203 (provide correct size hint for unsupported platform `CommandArgs`)
- rust-lang#100307 (Fixrust-lang#96847)
- rust-lang#100350 (Stringify non-shorthand visibility correctly)
- rust-lang#100374 (Improve crate selection on rustdoc search results page)
- rust-lang#100392 (Simplify visitors)
- rust-lang#100418 (Add stability attributes to BacktraceStatus variants)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
@bors
bors merged commit 37efd55 into rust-lang:masterAug 12, 2022
@rustbotrustbot added this to the 1.65.0 milestone Aug 12, 2022
@RalfJung
RalfJung deleted the raw_eq branch August 13, 2022 12:05
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