Resolve UB in Arc/Weak interaction (2)#72533

Diggsey · 2020-05-24T12:15:33Z

Use raw pointers to avoid making any assertions about the data field.

Follow up from #72479, see that PR for more detail on the motivation.

@RalfJung I was able to avoid a lot of the changes to Weak, by making a helper type (WeakInner) - because of auto-deref and because the fields have the same name, the rest of the code continues to compile.

rust-highfive · 2020-05-24T12:15:36Z

r? @dtolnay

(rust_highfive has picked a reviewer for you, use r? to override)

src/liballoc/sync.rs

RalfJung · 2020-05-24T19:46:12Z

I was able to avoid a lot of the changes to Weak, by making a helper type (WeakInner) - because of auto-deref and because the fields have the same name, the rest of the code continues to compile.

That's a very clever trick, I like it. :)

src/liballoc/sync.rs

Use raw pointers to avoid making any assertions about the data field.

RalfJung

LGTM!

I'd prefer if someone else would also review this --the more eyes, the better.

dtolnay

Looks good to me as well. Thanks for the helpful round of review.

dtolnay · 2020-05-26T03:49:51Z

@bors r+

bors · 2020-05-26T03:49:52Z

📌 Commit ee6e705 has been approved by dtolnay

@RalfJung

Resolve UB in Arc/Weak interaction (2) Use raw pointers to avoid making any assertions about the data field. Follow up from rust-lang#72479, see that PR for more detail on the motivation. @RalfJung I was able to avoid a lot of the changes to `Weak`, by making a helper type (`WeakInner`) - because of auto-deref and because the fields have the same name, the rest of the code continues to compile.

@RalfJung

Resolve UB in Arc/Weak interaction (2) Use raw pointers to avoid making any assertions about the data field. Follow up from rust-lang#72479, see that PR for more detail on the motivation. @RalfJung I was able to avoid a lot of the changes to `Weak`, by making a helper type (`WeakInner`) - because of auto-deref and because the fields have the same name, the rest of the code continues to compile.

@ghost

Rollup of 6 pull requests Successful merges: - rust-lang#72348 (Fix confusing error message for comma typo in multiline statement) - rust-lang#72533 (Resolve UB in Arc/Weak interaction (2)) - rust-lang#72548 (Add test for old compiler ICE when using `Borrow`) - rust-lang#72606 (Small cell example update) - rust-lang#72610 (Remove font-display settings) - rust-lang#72626 (Add remark regarding DoubleEndedIterator) Failed merges: r? @ghost

rust-highfive assigned dtolnay May 24, 2020

rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label May 24, 2020

Diggsey changed the title ~~Fix UB in Arc~~ Resolve UB in Arc/Weak interaction May 24, 2020

Diggsey changed the title ~~Resolve UB in Arc/Weak interaction~~ Resolve UB in Arc/Weak interaction (2) May 24, 2020

Diggsey mentioned this pull request May 24, 2020

Resolve UB in Arc/Weak interaction #72479

Closed

RalfJung reviewed May 24, 2020

View reviewed changes