compiler: upgrade to hashbrown 0.16.1 #151076

cuviper · 2026-01-13T19:30:43Z

See also #135634, #149159, and rust-lang/hashbrown#662.

This includes an in-tree upgrade of indexmap as well, which uses the
new HashTable buckets API internally, hopefully impacting performance
for the better.

And finally, we can remove #[rustc_unsafe_specialization_marker] on Copy!

cc @joboet
r? @Amanieu

See also rust-lang#135634, rust-lang#149159, and rust-lang/hashbrown#662. This includes an in-tree upgrade of `indexmap` as well, which uses the new `HashTable` buckets API internally, hopefully impacting performance for the better!

rustbot · 2026-01-13T19:30:50Z

⚠️ Warning ⚠️

There are issue links (such as #123) in the commit messages of the following commits.
Please move them to the PR description, to avoid spamming the issues with references to the commit, and so this bot can automatically canonicalize them to avoid issues with subtree.
- 348bfe3

cuviper · 2026-01-13T19:31:00Z

@bors try
@rust-timer queue

compiler: upgrade to hashbrown 0.16.1

cuviper · 2026-01-13T19:33:51Z

src/bootstrap/src/utils/proc_macro_deps.rs

    "fluent-langneg",
    "fluent-syntax",
    "fnv",
+    "foldhash",


I believe this is a false positive due to hashbrown's nightly = ["foldhash?/nightly"], rust-lang/cargo#10801, but I can't add a comment here since this is an auto-generated/blessed source file. I did add a similar comment in PERMITTED_STDLIB_DEPENDENCIES in #149159.

rust-bors · 2026-01-13T21:50:12Z

☀️ Try build successful (CI)
Build commit: b09b198 (b09b19850a9395d3b0f4f45c44d8a95bde6add0c, parent: 9b81629631b382fd49ee3a20ac47797b1467e52d)

rust-timer · 2026-01-13T22:30:57Z

Finished benchmarking commit (b09b198): comparison URL.

Overall result: ❌✅ regressions and improvements - please read the text below

Benchmarking this pull request means it may be perf-sensitive – we'll automatically label it not fit for rolling up. You can override this, but we strongly advise not to, due to possible changes in compiler perf.

Next Steps: If you can justify the regressions found in this try perf run, please do so in sufficient writing along with @rustbot label: +perf-regression-triaged. If not, please fix the regressions and do another perf run. If its results are neutral or positive, the label will be automatically removed.

@bors rollup=never
@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)	0.2%	[0.1%, 0.2%]	4
Regressions ❌ (secondary)	0.6%	[0.1%, 1.2%]	11
Improvements ✅ (primary)	-0.6%	[-0.8%, -0.4%]	3
Improvements ✅ (secondary)	-0.2%	[-0.5%, -0.1%]	14
All ❌✅ (primary)	-0.2%	[-0.8%, 0.2%]	7

Max RSS (memory usage)

Results (primary 1.6%, secondary -1.7%)

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

	mean	range	count
Regressions ❌ (primary)	2.7%	[2.4%, 2.9%]	2
Regressions ❌ (secondary)	1.9%	[1.2%, 2.6%]	4
Improvements ✅ (primary)	-0.6%	[-0.6%, -0.6%]	1
Improvements ✅ (secondary)	-4.1%	[-7.7%, -1.6%]	6
All ❌✅ (primary)	1.6%	[-0.6%, 2.9%]	3

Cycles

Results (primary -2.7%, secondary -3.8%)

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)	-	-	0
Improvements ✅ (primary)	-2.7%	[-2.7%, -2.7%]	1
Improvements ✅ (secondary)	-3.8%	[-5.5%, -2.2%]	8
All ❌✅ (primary)	-2.7%	[-2.7%, -2.7%]	1

Binary size

This benchmark run did not return any relevant results for this metric.

Bootstrap: 476.337s -> 473.121s (-0.68%)
Artifact size: 383.08 MiB -> 383.14 MiB (0.02%)

cuviper · 2026-01-13T23:26:08Z

Perf results look like a wash to me, which I guess is not bad news.

I forgot that I'd published indexmap v2.13.0 since I started testing this though, so let's try with that too, if only to keep up with the latest.

@bors try
@rust-timer queue

compiler: upgrade to hashbrown 0.16.1

rust-bors · 2026-01-14T01:42:27Z

☀️ Try build successful (CI)
Build commit: 2e3ca0d (2e3ca0db58753f952e04a911d18f1cb94a286216, parent: 2850ca8295bc253186b291314ddc239632755475)

rust-timer · 2026-01-14T03:00:26Z

Finished benchmarking commit (2e3ca0d): comparison URL.

Overall result: ❌✅ regressions and improvements - please read the text below

Benchmarking this pull request means it may be perf-sensitive – we'll automatically label it not fit for rolling up. You can override this, but we strongly advise not to, due to possible changes in compiler perf.

Next Steps: If you can justify the regressions found in this try perf run, please do so in sufficient writing along with @rustbot label: +perf-regression-triaged. If not, please fix the regressions and do another perf run. If its results are neutral or positive, the label will be automatically removed.

@bors rollup=never
@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)	0.2%	[0.1%, 0.2%]	6
Regressions ❌ (secondary)	0.7%	[0.1%, 1.2%]	9
Improvements ✅ (primary)	-0.7%	[-0.8%, -0.4%]	3
Improvements ✅ (secondary)	-0.2%	[-0.5%, -0.1%]	12
All ❌✅ (primary)	-0.1%	[-0.8%, 0.2%]	9

Max RSS (memory usage)

Results (primary 1.1%, secondary -2.7%)

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

	mean	range	count
Regressions ❌ (primary)	2.8%	[2.8%, 2.8%]	1
Regressions ❌ (secondary)	2.0%	[1.6%, 2.4%]	2
Improvements ✅ (primary)	-0.6%	[-0.6%, -0.6%]	1
Improvements ✅ (secondary)	-3.9%	[-8.3%, -1.8%]	8
All ❌✅ (primary)	1.1%	[-0.6%, 2.8%]	2

Cycles

Results (secondary -3.3%)

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)	2.1%	[2.1%, 2.1%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-4.1%	[-5.6%, -2.2%]	7
All ❌✅ (primary)	-	-	0

Binary size

Results (primary -0.0%, secondary -0.0%)

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)	-	-	0
Improvements ✅ (primary)	-0.0%	[-0.0%, -0.0%]	4
Improvements ✅ (secondary)	-0.0%	[-0.0%, -0.0%]	1
All ❌✅ (primary)	-0.0%	[-0.0%, -0.0%]	4

Bootstrap: 474.424s -> 473.528s (-0.19%)
Artifact size: 383.16 MiB -> 383.12 MiB (-0.01%)

Amanieu · 2026-01-19T12:03:46Z

@bors r+ rollup=never

rust-bors · 2026-01-19T12:03:49Z

📌 Commit 03cc50f has been approved by Amanieu

It is now in the queue for this repository.

rust-bors · 2026-01-20T09:00:47Z

☀️ Test successful - CI
Approved by: Amanieu
Duration: 3h 16m 26s
Pushing 7981818 to main...

github-actions · 2026-01-20T09:03:59Z

What is this?

This is an experimental post-merge analysis report that shows differences in test outcomes between the merged PR and its parent PR.

Comparing 058a763 (parent) -> 7981818 (this PR)

Test differences

Show 39 test diffs

39 doctest diffs were found. These are ignored, as they are noisy.

Test dashboard

Run

cargo run --manifest-path src/ci/citool/Cargo.toml -- \
    test-dashboard 79818181387879de7a521366d9bea23624728462 --output-dir test-dashboard

And then open test-dashboard/index.html in your browser to see an overview of all executed tests.

Job duration changes

aarch64-apple: 8384.7s -> 10965.0s (+30.8%)
tidy: 171.1s -> 197.3s (+15.3%)
x86_64-msvc-2: 10422.6s -> 8984.1s (-13.8%)
dist-apple-various: 3808.7s -> 4323.3s (+13.5%)
aarch64-gnu-llvm-20-2: 2739.4s -> 3038.4s (+10.9%)
dist-x86_64-apple: 8715.1s -> 7778.9s (-10.7%)
dist-powerpc64-linux: 5504.2s -> 5016.8s (-8.9%)
x86_64-msvc-ext3: 6011.5s -> 6499.3s (+8.1%)
aarch64-gnu-llvm-20-1: 3580.5s -> 3868.8s (+8.1%)
pr-check-2: 2403.8s -> 2596.4s (+8.0%)

How to interpret the job duration changes?

Job durations can vary a lot, based on the actual runner instance
that executed the job, system noise, invalidated caches, etc. The table above is provided
mostly for t-infra members, for simpler debugging of potential CI slow-downs.

rust-timer · 2026-01-20T11:03:56Z

Finished benchmarking commit (7981818): comparison URL.

Overall result: ❌✅ regressions and improvements - please read the text below

Our benchmarks found a performance regression caused by this PR.
This might be an actual regression, but it can also be just noise.

Next Steps:

If the regression was expected or you think it can be justified,
please write a comment with sufficient written justification, and add
@rustbot label: +perf-regression-triaged to it, to mark the regression as triaged.
If you think that you know of a way to resolve the regression, try to create
a new PR with a fix for the regression.
If you do not understand the regression or you think that it is just noise,
you can ask the @rust-lang/wg-compiler-performance working group for help (members of this group
were already notified of this PR).

@rustbot label: +perf-regression
cc @rust-lang/wg-compiler-performance

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)	0.2%	[0.2%, 0.2%]	3
Regressions ❌ (secondary)	0.6%	[0.1%, 1.2%]	8
Improvements ✅ (primary)	-0.8%	[-0.8%, -0.7%]	2
Improvements ✅ (secondary)	-0.3%	[-1.4%, -0.1%]	12
All ❌✅ (primary)	-0.2%	[-0.8%, 0.2%]	5

Max RSS (memory usage)

Results (primary 0.8%, secondary -3.8%)

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

	mean	range	count
Regressions ❌ (primary)	0.8%	[0.7%, 1.0%]	2
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-3.8%	[-7.0%, -1.9%]	8
All ❌✅ (primary)	0.8%	[0.7%, 1.0%]	2

Cycles

Results (primary 2.1%, secondary -3.3%)

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

	mean	range	count
Regressions ❌ (primary)	2.1%	[1.0%, 2.9%]	3
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-3.3%	[-3.8%, -2.3%]	3
All ❌✅ (primary)	2.1%	[1.0%, 2.9%]	3

Binary size

This benchmark run did not return any relevant results for this metric.

Bootstrap: 472.185s -> 473.092s (0.19%)
Artifact size: 383.28 MiB -> 383.30 MiB (0.01%)

cuviper added 2 commits January 13, 2026 11:18

compiler: upgrade to hashbrown 0.16.1

348bfe3

See also rust-lang#135634, rust-lang#149159, and rust-lang/hashbrown#662. This includes an in-tree upgrade of `indexmap` as well, which uses the new `HashTable` buckets API internally, hopefully impacting performance for the better!

library: finish unspecializing Copy

afa2260

rustbot assigned Amanieu Jan 13, 2026

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rust-bors bot pushed a commit that referenced this pull request Jan 13, 2026

Auto merge of #151076 - cuviper:compiler-hashbrown-0.16.1, r=<try>

b09b198

compiler: upgrade to hashbrown 0.16.1

rustbot added the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Jan 13, 2026

cuviper commented Jan 13, 2026

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rustbot added perf-regression Performance regression. and removed S-waiting-on-perf Status: Waiting on a perf run to be completed. labels Jan 13, 2026

update to indexmap v2.13.0

03cc50f

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rust-bors bot pushed a commit that referenced this pull request Jan 13, 2026

Auto merge of #151076 - cuviper:compiler-hashbrown-0.16.1, r=<try>

2e3ca0d

compiler: upgrade to hashbrown 0.16.1

rustbot added the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Jan 13, 2026

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rustbot removed the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Jan 14, 2026

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 Jan 19, 2026

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rust-bors bot added merged-by-bors This PR was explicitly merged by bors. and removed S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. labels Jan 20, 2026

rust-bors bot merged commit 7981818 into rust-lang:main Jan 20, 2026
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rustbot added this to the 1.95.0 milestone Jan 20, 2026

rust-bors bot mentioned this pull request Jan 20, 2026

Weekly cargo update #145516

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cuviper deleted the compiler-hashbrown-0.16.1 branch January 20, 2026 18:19

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Overall result: ❌✅ regressions and improvements - please read the text below

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Overall result: ❌✅ regressions and improvements - please read the text below

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Test differences

Job duration changes

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Overall result: ❌✅ regressions and improvements - please read the text below

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