Enable single Location to issue multiple borrows by aapoalas · Pull Request #159449 · rust-lang/rust

aapoalas · 2026-07-17T14:25:32Z

In the Reborrow work, a single MIR assignment statement can produce multiple borrows. To support that the GatherBorrows contents need to change a little. Aside from the get_index_of function which is used in three places, none of the changes affect code outside the borrow_set.rs file.

I also changed the one Vec there was into a SmallVec<[1]> as that is the most likely case (I believe), and similarly used SmallVec<[1]> for the Location->BorrowIndex[] listing.

r? compiler

Kobzol · 2026-07-17T14:29:19Z

@bors try @rust-timer queue

…ion, r=<try> Enable single Location to issue multiple borrows

rust-bors · 2026-07-17T16:37:20Z

☀️ Try build successful (CI)
Build commit: 544be1c (544be1c5fc24cbe33b4e5fb71220310270f6cda8)
Base parent: 4a9d536 (4a9d5368df6450bbd2fc8dde4508c3e5d83bb19d)

rust-timer · 2026-07-17T19:16:18Z

Finished benchmarking commit (544be1c): comparison URL.

Overall result: no relevant changes - no action needed

Benchmarking means the PR may be perf-sensitive. Consider adding rollup=never if this change is not fit for rolling up.

@rustbot label: -S-waiting-on-perf -perf-regression

Instruction count

This perf run didn't have relevant results for this metric.

Max RSS (memory usage)

Results (primary 7.3%, secondary 6.1%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	7.3%	[2.0%, 12.5%]	2
Regressions ❌ (secondary)	6.1%	[6.1%, 6.1%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	7.3%	[2.0%, 12.5%]	2

Cycles

Results (secondary 4.5%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	4.5%	[2.2%, 6.8%]	2
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Binary size

Results (primary 0.1%, secondary 0.1%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	0.1%	[0.0%, 0.1%]	56
Regressions ❌ (secondary)	0.1%	[0.0%, 0.1%]	23
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.1%	[0.0%, 0.1%]	56

Bootstrap: 491.028s -> 495.454s (0.90%)
Artifact size: 389.42 MiB -> 389.56 MiB (0.04%)

jieyouxu · 2026-07-18T05:51:39Z

@rustbot reroll

aapoalas · 2026-07-18T14:39:08Z

I believe the failure is CI being flaky... maybe?

mati865 · 2026-07-18T15:22:02Z

I'm occupied with other issues that we are facing right now. @rustbot reroll

aapoalas · 2026-07-18T19:42:27Z

Checked that none of the public functions I removed are relied on by rust-analyzer. One removed function (exposing the location_map) was relied on by Aquascope but their usage would've broke anyway; they were using it to iterate through all BorrowData<'tcx> so I added the fn iter() to enable that.

nnethercote

Can you squash the commits? Not sure if it should end up being a single commit, or maybe two, but we don't need separate "fix" commits.

View changes since this review

rustbot · 2026-07-20T09:39:15Z

This PR was rebased onto a different main commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.

aapoalas · 2026-07-20T09:39:36Z

Can you squash the commits? Not sure if it should end up being a single commit, or maybe two, but we don't need separate "fix" commits.

Done.

nnethercote · 2026-07-20T10:43:03Z

@bors r+

rust-bors · 2026-07-20T10:43:06Z

📌 Commit 69e55f3 has been approved by nnethercote

It is now in the queue for this repository.

…-from-location, r=nnethercote Enable single Location to issue multiple borrows In the Reborrow work, a single MIR assignment statement can produce multiple borrows. To support that the GatherBorrows contents need to change a little. Aside from the `get_index_of` function which is used in three places, none of the changes affect code outside the `borrow_set.rs` file. I also changed the one `Vec` there was into a `SmallVec<[1]>` as that is the most likely case (I believe), and similarly used `SmallVec<[1]>` for the `Location->BorrowIndex[]` listing. r? compiler

…uwer Rollup of 10 pull requests Successful merges: - #159600 (`rust-analyzer` subtree update) - #158046 (proc_macro: preserve file module spans for inner attrs) - #159000 (Small cleanups to the incr comp session code) - #159449 (Enable single Location to issue multiple borrows) - #159587 (Improve `AttrItem::span`) - #159460 (Do not mark unnormalized const aliases as rigid when normalizing param env) - #159529 (Add regression test for nested replacement ranges in `collect_tokens`) - #159585 (Minor `TokenStream` improvements) - #159586 (Separate `InterpCx` usage by `ConstAnalysis` phases) - #159603 (Clarify `push_stream`/`push_tree`) Failed merges: - #159590 (Remove some dead code)

…uwer Rollup of 18 pull requests Successful merges: - #159600 (`rust-analyzer` subtree update) - #158046 (proc_macro: preserve file module spans for inner attrs) - #159000 (Small cleanups to the incr comp session code) - #159189 (Account for type alias projections in E0308 "expected/found" shortening logic) - #159449 (Enable single Location to issue multiple borrows) - #159544 (Suggest valid command-line crate names) - #159587 (Improve `AttrItem::span`) - #159594 (feat(rustc_hir_typeck): suggest `impl Fn` return for capturing closures) - #159597 (std: use `arc4random_buf` from libc) - #159599 (Resolver: Record at least 1 ambiguous trait if main decl is not a trait.) - #158061 (Make `pin!()` more foolproof.) - #159460 (Do not mark unnormalized const aliases as rigid when normalizing param env) - #159529 (Add regression test for nested replacement ranges in `collect_tokens`) - #159571 (Remove unused bundled library lookup for the local crate) - #159585 (Minor `TokenStream` improvements) - #159586 (Separate `InterpCx` usage by `ConstAnalysis` phases) - #159602 (Remove `ItemLike`) - #159603 (Clarify `push_stream`/`push_tree`) Failed merges: - #159590 (Remove some dead code)

Rollup merge of #159449 - aapoalas:borrowck/multiple-borrows-from-location, r=nnethercote Enable single Location to issue multiple borrows In the Reborrow work, a single MIR assignment statement can produce multiple borrows. To support that the GatherBorrows contents need to change a little. Aside from the `get_index_of` function which is used in three places, none of the changes affect code outside the `borrow_set.rs` file. I also changed the one `Vec` there was into a `SmallVec<[1]>` as that is the most likely case (I believe), and similarly used `SmallVec<[1]>` for the `Location->BorrowIndex[]` listing. r? compiler

rustbot assigned jieyouxu Jul 17, 2026

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 Jul 17, 2026

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rust-bors Bot pushed a commit that referenced this pull request Jul 17, 2026

Auto merge of #159449 - aapoalas:borrowck/multiple-borrows-from-locat…

544be1c

…ion, r=<try> Enable single Location to issue multiple borrows

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rustbot removed the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Jul 17, 2026

aapoalas commented Jul 17, 2026

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Comment thread compiler/rustc_borrowck/src/borrow_set.rs Outdated

rustbot assigned mati865 and unassigned jieyouxu Jul 18, 2026

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rustbot assigned nnethercote and unassigned mati865 Jul 18, 2026

nnethercote reviewed Jul 20, 2026

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Comment thread compiler/rustc_borrowck/src/borrow_set.rs Outdated

nnethercote added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Jul 20, 2026

Enable single Location to issue multiple borrows

69e55f3

aapoalas force-pushed the borrowck/multiple-borrows-from-location branch from 58bb0be to 69e55f3 Compare July 20, 2026 09:39

aapoalas requested a review from nnethercote July 20, 2026 09:48

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Jul 20, 2026

nnethercote approved these changes Jul 20, 2026

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rust-bors Bot 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 Jul 20, 2026

JonathanBrouwer mentioned this pull request Jul 20, 2026

Rollup of 10 pull requests #159604

Closed

JonathanBrouwer mentioned this pull request Jul 20, 2026

Rollup of 18 pull requests #159610

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rust-bors Bot merged commit 69f40f0 into rust-lang:main Jul 20, 2026
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rustbot added this to the 1.99.0 milestone Jul 20, 2026

aapoalas deleted the borrowck/multiple-borrows-from-location branch July 23, 2026 12:00

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rust-timer commented Jul 17, 2026

Overall result: no relevant changes - no action needed

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