Implement `clone_from` for `BorrowckDomain` by TaKO8Ki · Pull Request #164089 · rust-lang/rust

TaKO8Ki · 2026-10-10T13:40:37Z

I've added a similar implementation for BorrowckDomain as for rustc_const_eval::check_consts::resolver::State.

rust/compiler/rustc_const_eval/src/check_consts/resolver.rs

Lines 270 to 281 in 208a58d

    
           impl Clone for State { 
        
               fn clone(&self) -> Self { 
        
                   State { qualif: self.qualif.clone(), borrow: self.borrow.clone() } 
        
               } 
        
               // Data flow engine when possible uses `clone_from` for domain values. 
        
               // Providing an implementation will avoid some intermediate memory allocations. 
        
               fn clone_from(&mut self, other: &Self) { 
        
                   self.qualif.clone_from(&other.qualif); 
        
                   self.borrow.clone_from(&other.borrow); 
        
               } 
        
           }

TaKO8Ki · 2026-10-10T13:41:40Z

@bors try @rust-timer queue

Implement `clone_from` for `BorrowckDomain`

rust-bors · 2026-10-10T14:41:25Z

☀️ Try build successful (CI)
Build commit: f776b65 (f776b65df91f16f1ee06fb6deba9f1aea2f35ee5)
Base parent: 5ec56e3 (5ec56e3902656f2460259fc3ac0f6e2255f94417)

rust-timer · 2026-10-10T19:29:11Z

Finished benchmarking commit (f776b65): comparison URL.

Overall result: ✅ improvements - no action needed

Benchmarking means the PR may be perf-sensitive. It's automatically marked not fit for rolling up. Overriding is possible but disadvised: it risks changing compiler perf.

@bors rollup=never rustc-perf
@rustbot label: -S-waiting-on-perf -perf-regression

Instruction count

Our most reliable metric. Used to determine the overall result above. However, even this metric can be noisy.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-0.2%	[-0.3%, -0.1%]	17
Improvements ✅ (secondary)	-0.2%	[-0.3%, -0.1%]	13
All ❌✅ (primary)	-0.2%	[-0.3%, -0.1%]	17

Max RSS (memory usage)

Results (primary -2.6%, 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
Regressions ❌ (secondary)	4.4%	[4.4%, 4.4%]	1
Improvements ✅ (primary)	-2.6%	[-2.6%, -2.6%]	1
Improvements ✅ (secondary)	-4.1%	[-4.1%, -4.1%]	1
All ❌✅ (primary)	-2.6%	[-2.6%, -2.6%]	1

Cycles

Results (primary 0.7%, 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)	2.6%	[2.6%, 2.6%]	2
Regressions ❌ (secondary)	4.5%	[4.5%, 4.5%]	1
Improvements ✅ (primary)	-3.2%	[-3.2%, -3.2%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.7%	[-3.2%, 2.6%]	3

Binary size

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

Bootstrap: 487.044s -> 488.946s (0.39%)
Artifact size: 406.45 MiB -> 406.61 MiB (0.04%)

rustbot · 2026-10-11T11:45:24Z

r? @mati865

rustbot has assigned @mati865.
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Owners of files modified in this PR: borrowck, compiler
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mati865

Nice!

@bors r+

View changes since this review

rust-bors · 2026-10-12T11:33:43Z

📌 Commit 208a58d has been approved by mati865

It is now in the queue for this repository.

JonathanBrouwer · 2026-10-12T19:14:23Z

@bors rollup=iffy
Adding this to a rollup of perf-sensitive PRs

…uwer Rollup of 4 perf-sensitive pull requests Successful merges: - #163425 (Treat union fields as aliasing each other in value_analysis) - #164074 (Avoid cloning impl trait AST nodes in late resolution) - #164089 (Implement `clone_from` for `BorrowckDomain`) - #164150 (Reserve more capacity for Symbol interner)

Rollup merge of #164089 - TaKO8Ki:borrowck-domain-clone-from, r=mati865 Implement `clone_from` for `BorrowckDomain` I've added a similar implementation for `BorrowckDomain` as for `rustc_const_eval::check_consts::resolver::State`. https://github.com/rust-lang/rust/blob/208a58d8c1b22a5b43c8e671077ed5ac4032abde/compiler/rustc_const_eval/src/check_consts/resolver.rs#L270-L281

rust-timer · 2026-10-13T07:57:05Z

Note

This PR was benchmarked as part of triage of its containing rollup: triage URL.

Finished benchmarking commit (078dd24): comparison URL.

Overall result: ✅ improvements - no action needed

@rustbot label: -perf-regression

Instruction count

Our most reliable metric. Used to determine the overall result above. However, even this metric can be noisy.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-0.2%	[-0.6%, -0.1%]	21
Improvements ✅ (secondary)	-0.4%	[-0.8%, -0.1%]	53
All ❌✅ (primary)	-0.2%	[-0.6%, -0.1%]	21

Max RSS (memory usage)

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

Cycles

Results (secondary 2.3%)

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)	2.3%	[2.3%, 2.3%]	1
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%, 0.2%]	82
Regressions ❌ (secondary)	0.1%	[0.0%, 0.2%]	47
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.1%	[0.0%, 0.2%]	82

Artifact size: 406.63 MiB -> 406.94 MiB (0.08%)

implement clone_from for BorrowckDomain

208a58d

rustbot added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Oct 10, 2026

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rust-bors Bot pushed a commit that referenced this pull request Oct 10, 2026

Auto merge of #164089 - TaKO8Ki:borrowck-domain-clone-from, r=<try>

f776b65

Implement `clone_from` for `BorrowckDomain`

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rustbot removed the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Oct 10, 2026

TaKO8Ki marked this pull request as ready for review October 11, 2026 11:45

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 Oct 11, 2026

rustbot assigned mati865 Oct 11, 2026

mati865 approved these changes Oct 12, 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 Oct 12, 2026

JonathanBrouwer mentioned this pull request Oct 12, 2026

Rollup of 4 perf-sensitive pull requests #164224

Merged

rust-bors Bot merged commit 645a281 into rust-lang:main Oct 12, 2026
15 checks passed

rustbot added this to the 1.101.0 milestone Oct 12, 2026

TaKO8Ki deleted the borrowck-domain-clone-from branch October 15, 2026 06:58

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Implement `clone_from` for `BorrowckDomain` - #164089

Implement `clone_from` for `BorrowckDomain`#164089
rust-bors[bot] merged 1 commit into
rust-lang:mainfrom
TaKO8Ki:borrowck-domain-clone-from

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	impl Clone for State {
	fn clone(&self) -> Self {
	State { qualif: self.qualif.clone(), borrow: self.borrow.clone() }
	}

	// Data flow engine when possible uses `clone_from` for domain values.
	// Providing an implementation will avoid some intermediate memory allocations.
	fn clone_from(&mut self, other: &Self) {
	self.qualif.clone_from(&other.qualif);
	self.borrow.clone_from(&other.borrow);
	}
	}

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Overall result: ✅ improvements - no action needed

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