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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 intorust-lang:masterfrom
RalfJung:raw_eq

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@RalfJung RalfJung 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.

@rustbot rustbot 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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rustbot commented Jul 20, 2022

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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rust-highfive commented Jul 20, 2022

r? @joshtriplett

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@rust-highfive rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Jul 20, 2022
mcol
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fix typo
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Co-authored-by: Marco Colombo <mar.colombo13@gmail.com>
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RalfJung commented Aug 3, 2022

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

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Co-authored-by: Nicholas Nethercote <n.nethercote@gmail.com>
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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

@bors r+ rollup

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bors commented Aug 11, 2022

📌 Commit 338d7c2 has been approved by wesleywiser

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 Aug 11, 2022
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RalfJung commented Aug 11, 2022

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.

@matthiaskrgr matthiaskrgr 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
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Auto merge of rust-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 (Fix rust-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:master Aug 12, 2022
@rustbot rustbot 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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