pre-intern single-letter `sym::[a-zA-Z]` by GrigorenkoPV · Pull Request #152948 · rust-lang/rust

GrigorenkoPV · 2026-02-21T20:56:30Z

Needs a perf run I guess.

rustbot · 2026-02-21T20:56:35Z

rustbot has assigned @jdonszelmann.
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compiler expanded to 68 candidates
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GrigorenkoPV · 2026-02-21T20:57:55Z

compiler/rustc_span/src/symbol.rs

    #[doc(inline)]
    pub use super::sym_generated::*;

+    // use quite a lot in relation to C ABI


Eh, typo. Will fix later.

GrigorenkoPV · 2026-02-21T20:59:41Z

Not sure if I have enough rights, but let's try the magic spell

@bors try @rust-timer queue

rust-bors · 2026-02-21T20:59:43Z

@GrigorenkoPV: 🔑 Insufficient privileges: not in try users

JonathanBrouwer · 2026-02-21T21:09:44Z

@bors try @rust-timer queue

pre-intern single-letter `sym::[a-zA-Z]`

rust-bors · 2026-02-21T23:21:14Z

☀️ Try build successful (CI)
Build commit: 09623a8 (09623a861acf5ebfb89c93a6a60a1c931156ddb3, parent: 99246f40931ce1d1d29517b61bd70dd9ed4fbe5d)

rust-timer · 2026-02-22T00:01:36Z

Finished benchmarking commit (09623a8): comparison URL.

Overall result: ❌✅ regressions and improvements - no action needed

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.

@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
Regressions ❌ (secondary)	0.3%	[0.3%, 0.3%]	1
Improvements ✅ (primary)	-0.3%	[-0.3%, -0.3%]	1
Improvements ✅ (secondary)	-0.1%	[-0.1%, -0.1%]	2
All ❌✅ (primary)	-0.3%	[-0.3%, -0.3%]	1

Max RSS (memory usage)

Results (primary 2.0%, secondary -2.8%)

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

	mean	range	count
Regressions ❌ (primary)	2.0%	[2.0%, 2.0%]	1
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-2.8%	[-4.9%, -1.0%]	3
All ❌✅ (primary)	2.0%	[2.0%, 2.0%]	1

Cycles

Results (secondary 2.0%)

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)	2.0%	[2.0%, 2.0%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Binary size

Results (primary -0.1%, 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)	-0.1%	[-0.1%, -0.0%]	16
Improvements ✅ (secondary)	-0.0%	[-0.0%, -0.0%]	10
All ❌✅ (primary)	-0.1%	[-0.1%, -0.0%]	16

Bootstrap: 482.582s -> 480.846s (-0.36%)
Artifact size: 397.92 MiB -> 397.93 MiB (0.00%)

JonathanBrouwer · 2026-02-22T11:33:54Z

The perf regression is most likely noise, so perf looks good
@rustbot author, ci is failing

rustbot · 2026-02-22T11:33:58Z

Reminder, once the PR becomes ready for a review, use @rustbot ready.

GrigorenkoPV · 2026-02-22T14:14:19Z

I simply blessed the tests. IDK if these changes are acceptable or should warrant more investigation.

@rustbot ready

JonathanBrouwer · 2026-02-22T16:00:36Z

I would like to at least understand why the stderrs changed, I don't see an obvious explanation for this

Kivooeo · 2026-02-23T17:30:46Z

I don't see an obvious explanation for this

this is more correct now, well, more consistent maybe is the better word, it seems like the suggestion broke ties between equally-similar candidates by picking the lowest symbol index, and c was suggested because it had a lower assign index than a or b which wasn't in symbols! table at all

JonathanBrouwer

@bors r+ rollup=never
Rollup=never for performance

View changes since this review

rust-bors · 2026-02-23T20:04:40Z

📌 Commit a5e6ccc has been approved by JonathanBrouwer

It is now in the queue for this repository.

nnethercote · 2026-02-24T04:23:11Z

compiler/rustc_span/src/symbol.rs

+        }))
+    }
+
+    pub fn character(c: char) -> Symbol {


I'm sad the name is character when everything else in this commit uses "letter".

i can do follow up with rename ;)

I'm sad the name is character when everything else in this commit uses "letter".

I was going to name it letter at first, but then I though it would be strange to not include digits here too, and it has a fallback for other characters anyway, hence character. After all, it works on any character, but has a special fast path for ascii letters and digits.

There's ascii_letter_digit just above, which does exactly what it says it does, has no fallback for other characters, and thus can be made const.

JonathanBrouwer · 2026-02-28T07:20:18Z

@bors p=6
Scheduling this before the rollup

rust-bors · 2026-02-28T12:22:45Z

☀️ Test successful - CI
Approved by: JonathanBrouwer
Duration: 3h 44m 26s
Pushing 1d113d2 to main...

github-actions · 2026-02-28T12:25:55Z

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 846cb1e (parent) -> 1d113d2 (this PR)

Test differences

Show 2 test diffs

2 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 1d113d2f3068f6cadf0fe799307d7a06d771d866 --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

dist-aarch64-llvm-mingw: 1h 32m -> 1h 49m (+19.2%)
pr-check-1: 27m 52s -> 33m 13s (+19.2%)
x86_64-gnu-llvm-20-3: 1h 39m -> 1h 55m (+16.3%)
i686-gnu-2: 1h 29m -> 1h 41m (+14.0%)
x86_64-rust-for-linux: 47m 20s -> 53m 47s (+13.6%)
tidy: 2m 49s -> 2m 26s (-13.6%)
x86_64-gnu-tools: 55m 51s -> 1h 3m (+13.3%)
x86_64-mingw-1: 2h 31m -> 2h 51m (+12.8%)
armhf-gnu: 1h 22m -> 1h 32m (+12.2%)
dist-x86_64-apple: 2h 7m -> 2h 22m (+12.2%)

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 · 2026-02-28T13:04:17Z

Finished benchmarking commit (1d113d2): comparison URL.

Overall result: ❌✅ regressions and 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)	0.3%	[0.3%, 0.3%]	3
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-0.2%	[-0.2%, -0.1%]	3
All ❌✅ (primary)	-	-	0

Max RSS (memory usage)

Results (primary -2.2%, secondary -1.1%)

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)	-	-	0
Improvements ✅ (primary)	-2.2%	[-2.2%, -2.2%]	1
Improvements ✅ (secondary)	-1.1%	[-1.1%, -1.0%]	3
All ❌✅ (primary)	-2.2%	[-2.2%, -2.2%]	1

Cycles

Results (secondary -4.4%)

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
Improvements ✅ (secondary)	-4.4%	[-4.4%, -4.3%]	2
All ❌✅ (primary)	-	-	0

Binary size

Results (primary -0.1%, 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)	-0.1%	[-0.1%, -0.0%]	16
Improvements ✅ (secondary)	-0.0%	[-0.0%, -0.0%]	10
All ❌✅ (primary)	-0.1%	[-0.1%, -0.0%]	16

Bootstrap: 481.235s -> 508.307s (5.63%)
Artifact size: 397.57 MiB -> 397.57 MiB (0.00%)

rustbot assigned jdonszelmann Feb 21, 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. T-rustdoc Relevant to the rustdoc team, which will review and decide on the PR/issue. labels Feb 21, 2026

GrigorenkoPV commented Feb 21, 2026

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rust-bors bot pushed a commit that referenced this pull request Feb 21, 2026

Auto merge of #152948 - GrigorenkoPV:sym-ascii, r=<try>

09623a8

pre-intern single-letter `sym::[a-zA-Z]`

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rustbot added the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Feb 21, 2026

JonathanBrouwer assigned JonathanBrouwer and unassigned jdonszelmann Feb 21, 2026

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pre-intern single-letter sym::[a-zA-Z]

abcdef0

GrigorenkoPV force-pushed the sym-ascii branch from abcdef0 to abcdef0 Compare February 21, 2026 22:01

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rustbot removed the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Feb 22, 2026

rustbot 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 Feb 22, 2026

bless tests

a5e6ccc

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 Feb 22, 2026

JonathanBrouwer approved these changes Feb 23, 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 Feb 23, 2026

nnethercote reviewed Feb 24, 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 Feb 28, 2026

rust-bors bot merged commit 1d113d2 into rust-lang:main Feb 28, 2026
12 checks passed

rustbot added this to the 1.96.0 milestone Feb 28, 2026

GrigorenkoPV deleted the sym-ascii branch February 28, 2026 12:27

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rust-timer commented Feb 22, 2026

Overall result: ❌✅ regressions and improvements - no action needed

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Test differences

Job duration changes

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Overall result: ❌✅ regressions and improvements - no action needed

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