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Use Vec::push_mut when adding a chunk to arenas#155161

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rust-bors[bot] merged 1 commit intorust-lang:mainfrom
saethlin:push_mut_saves
Apr 12, 2026
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Use Vec::push_mut when adding a chunk to arenas#155161
rust-bors[bot] merged 1 commit intorust-lang:mainfrom
saethlin:push_mut_saves

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@saethlin saethlin commented Apr 11, 2026

This fixes #155148, which may or may not be worth fixing on its own merits, but I think Vec::push_mut also makes the code nicer.

@rustbot rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Apr 11, 2026
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rustbot commented Apr 11, 2026

r? @nnethercote

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Kivooeo commented Apr 12, 2026

should we add a test for this?

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saethlin commented Apr 12, 2026

The arena in the compiler already has tests, the trick is that you can only get a test failure if you run the test code with Miri.

The copy+paste into proc_macro does not have any tests. I could also copy+paste the tests from the compiler into it, then also expand https://github.com/rust-lang/miri-test-libstd/ to run its new tests.

The original report is based on misuse of the API so we'd be checking that the test panics and doesn't report UB when run with Miri, but if someone just moves the panicking check around that will make the test always pass even if the UB comes back.

I'd rather not balloon the effort here.

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Kivooeo commented Apr 12, 2026

ohhhh, ok cool then

r? me @bors r+ rollup

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rust-bors Bot commented Apr 12, 2026

📌 Commit ff61915 has been approved by Kivooeo

It is now in the queue for this repository.

@rust-bors rust-bors Bot added the S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. label Apr 12, 2026
@rust-bors rust-bors Bot removed the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Apr 12, 2026
@JonathanBrouwer JonathanBrouwer mentioned this pull request Apr 12, 2026
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rust-bors Bot pushed a commit that referenced this pull request Apr 12, 2026
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Auto merge of #155199 - JonathanBrouwer:rollup-OhWpGAc, r=JonathanBro…
dab8d9d 
…uwer

Rollup of 5 pull requests

Successful merges:

 - #155197 (miri subtree update)
 - #154804 (Fix ICE when reporting host-effect errors for const Fn HRTBs in next trait solver)
 - #155014 (Hexagon: add scalar arch-version target features (v60-v79, audio))
 - #155068 (Fix ICE in `span_extend_prev_while` with multibyte characters)
 - #155161 (Use Vec::push_mut when adding a chunk to arenas)
@rust-bors rust-bors Bot merged commit bf4d385 into rust-lang:main Apr 12, 2026
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rust-timer added a commit that referenced this pull request Apr 12, 2026
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Unrolled build for #155161
0d2ba34 
Rollup merge of #155161 - saethlin:push_mut_saves, r=Kivooeo

Use Vec::push_mut when adding a chunk to arenas

This fixes #155148, which may or may not be worth fixing on its own merits, but I think `Vec::push_mut` also makes the code nicer.
@rustbot rustbot added this to the 1.97.0 milestone Apr 12, 2026
nnethercote
nnethercote reviewed Apr 13, 2026
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Yeah, this seems fine.

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@saethlin saethlin deleted the push_mut_saves branch April 13, 2026 00:59
github-actions Bot pushed a commit to rust-lang/miri that referenced this pull request Apr 19, 2026
@bors
Auto merge of #155199 - JonathanBrouwer:rollup-OhWpGAc, r=JonathanBro…
5dbcf71 
…uwer

Rollup of 5 pull requests

Successful merges:

 - rust-lang/rust#155197 (miri subtree update)
 - rust-lang/rust#154804 (Fix ICE when reporting host-effect errors for const Fn HRTBs in next trait solver)
 - rust-lang/rust#155014 (Hexagon: add scalar arch-version target features (v60-v79, audio))
 - rust-lang/rust#155068 (Fix ICE in `span_extend_prev_while` with multibyte characters)
 - rust-lang/rust#155161 (Use Vec::push_mut when adding a chunk to arenas)
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