Mark desugared range expression spans with DesugaringKind::RangeExpr #146069

camsteffen · 2025-09-01T01:20:52Z

This is a prerequisite to removing QPath::LangItem (#115178) because otherwise there would be no way to detect a range expression in the HIR.

There are some non-obvious Clippy changes so a Clippy team review would be good.

rustbot · 2025-09-01T01:20:56Z

r? @SparrowLii

rustbot has assigned @SparrowLii.
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rustbot · 2025-09-01T01:20:58Z

Some changes occurred in src/tools/clippy

cc @rust-lang/clippy

src/tools/clippy/clippy_lints/src/unnecessary_struct_initialization.rs

camsteffen · 2025-09-19T21:26:35Z

@SparrowLii are you able to review?

SparrowLii

Sorry for the late reviewing. The impl looks good to me. I'd like to run a perf test. We can merge it if there's no regression

View changes since this review

SparrowLii · 2025-09-30T06:14:30Z

@bors try @rust-timer queue

Mark desugared range expression spans with DesugaringKind::RangeExpr

rust-bors · 2025-09-30T08:27:44Z

☀️ Try build successful (CI)
Build commit: b4fcc0d (b4fcc0d45ab65abcfb6750a45343c0226167f12e, parent: c5dc558e6cca43958616b268b66c49763f2e9e9a)

rust-timer · 2025-09-30T09:37:39Z

Finished benchmarking commit (b4fcc0d): comparison URL.

Overall result: ❌ regressions - 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)	0.3%	[0.2%, 0.4%]	13
Regressions ❌ (secondary)	0.2%	[0.1%, 0.3%]	14
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.3%	[0.2%, 0.4%]	13

Max RSS (memory usage)

Results (primary 1.0%)

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

	mean	range	count
Regressions ❌ (primary)	1.0%	[0.8%, 1.2%]	2
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	1.0%	[0.8%, 1.2%]	2

Cycles

Results (primary 2.2%, secondary 6.5%)

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

	mean	range	count
Regressions ❌ (primary)	2.2%	[2.2%, 2.2%]	1
Regressions ❌ (secondary)	6.5%	[2.5%, 11.1%]	4
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	2.2%	[2.2%, 2.2%]	1

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%, 0.5%]	73
Regressions ❌ (secondary)	0.1%	[0.0%, 0.3%]	16
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.1%	[0.0%, 0.5%]	73

Bootstrap: 468.849s -> 470.946s (0.45%)
Artifact size: 387.70 MiB -> 387.73 MiB (0.01%)

camsteffen · 2025-09-30T15:08:54Z

Just a guess but let's see if that fixes it.

SparrowLii · 2025-10-09T07:11:21Z

@bors try @rust-timer queue

Mark desugared range expression spans with DesugaringKind::RangeExpr

camsteffen · 2025-10-09T14:56:02Z

Those results are worse so I took that commit back. I'm not finding anything actionable in cachegrind. I think this is a mixture of some noise and some inevitable loss with creating more span contexts.

SparrowLii · 2025-10-11T00:58:30Z

We focus on the primary cases so I think the second impl and results are a bit better. Collecting lang items in HIR is very valuable so the regression doesn't block this PR IMO. Just seeing if there are some optimiztions. Anyway I think we can merge it next week.

SparrowLii · 2025-10-20T08:52:20Z

@camsteffen Could you re-push the commit which generates the soecend perf resutlts? Then I can give a r+

The need for this arose when encountering range expressions surrounded by parenthesis, where we want the span desugaring mark to be preserved.

rustbot · 2025-10-21T15:05:46Z

This PR was rebased onto a different master 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.

camsteffen · 2025-10-21T15:08:19Z

Ok, I squashed it in. Sorry for the delay, I think I misunderstood your comment before.

SparrowLii · 2025-10-27T01:03:35Z

@bors r+ rollup=never

bors · 2025-10-27T01:03:38Z

📌 Commit 6d61dad has been approved by SparrowLii

It is now in the queue for this repository.

bors · 2025-10-27T02:50:39Z

⌛ Testing commit 6d61dad with merge 23fced0...

bors · 2025-10-27T05:57:09Z

☀️ Test successful - checks-actions
Approved by: SparrowLii
Pushing 23fced0 to master...

github-actions · 2025-10-27T06:00:15Z

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 b1b464d (parent) -> 23fced0 (this PR)

Test differences

Show 26 test diffs

26 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 23fced0fcc5e0ec260d25f04a8b78b269e5e90f0 --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

pr-check-1: 1482.8s -> 1931.4s (30.3%)
aarch64-msvc-2: 5095.3s -> 6228.7s (22.2%)
i686-gnu-nopt-1: 6862.5s -> 7962.6s (16.0%)
i686-gnu-2: 5463.9s -> 6335.6s (16.0%)
armhf-gnu: 4922.1s -> 5702.6s (15.9%)
dist-x86_64-apple: 6842.9s -> 7865.4s (14.9%)
aarch64-gnu-llvm-20-1: 3207.8s -> 3685.6s (14.9%)
aarch64-gnu-llvm-20-2: 2168.3s -> 2486.0s (14.7%)
x86_64-gnu-tools: 3360.2s -> 3772.8s (12.3%)
x86_64-gnu-gcc: 3077.2s -> 3454.3s (12.3%)

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 · 2025-10-27T08:10:34Z

Finished benchmarking commit (23fced0): comparison URL.

Overall result: ❌ regressions - 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%	[0.1%, 0.3%]	8
Regressions ❌ (secondary)	0.3%	[0.2%, 0.3%]	13
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-0.1%	[-0.1%, -0.1%]	1
All ❌✅ (primary)	0.2%	[0.1%, 0.3%]	8

Max RSS (memory usage)

Results (primary 0.5%, secondary 4.0%)

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

	mean	range	count
Regressions ❌ (primary)	1.7%	[0.8%, 3.0%]	3
Regressions ❌ (secondary)	4.0%	[4.0%, 4.0%]	1
Improvements ✅ (primary)	-3.1%	[-3.1%, -3.1%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.5%	[-3.1%, 3.0%]	4

Cycles

Results (secondary 1.6%)

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)	4.9%	[2.9%, 6.9%]	2
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-5.0%	[-5.0%, -5.0%]	1
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%, 0.5%]	74
Regressions ❌ (secondary)	0.1%	[0.0%, 0.3%]	16
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.1%	[0.0%, 0.5%]	74

Bootstrap: 474.573s -> 475.144s (0.12%)
Artifact size: 390.41 MiB -> 390.52 MiB (0.03%)

panstromek · 2025-10-27T14:41:46Z

perf triage:

Regression was deemed acceptable here: #146069 (comment)

Note that the regression mostly affects very short benchmarks (incr-unchanged and such), so this is not as bad as it might seem from the summary.

@rustbot label: +perf-regression-triaged

…rrowLii Mark desugared range expression spans with DesugaringKind::RangeExpr This is a prerequisite to removing `QPath::LangItem` (rust-lang#115178) because otherwise there would be no way to detect a range expression in the HIR. There are some non-obvious Clippy changes so a Clippy team review would be good.

rustbot assigned SparrowLii Sep 1, 2025

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-clippy Relevant to the Clippy team. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Sep 1, 2025

flip1995 reviewed Sep 1, 2025

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src/tools/clippy/clippy_lints/src/unnecessary_struct_initialization.rs Show resolved Hide resolved

camsteffen force-pushed the range-desugar-span branch 3 times, most recently from b4bfa81 to ac6978f Compare September 1, 2025 17:46

camsteffen force-pushed the range-desugar-span branch from ac6978f to 7dce8b2 Compare September 10, 2025 21:18

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SparrowLii reviewed Sep 30, 2025

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rust-bors bot added a commit that referenced this pull request Sep 30, 2025

Auto merge of #146069 - camsteffen:range-desugar-span, r=<try>

b4fcc0d

Mark desugared range expression spans with DesugaringKind::RangeExpr

rustbot added the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Sep 30, 2025

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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 Sep 30, 2025

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rust-bors bot added a commit that referenced this pull request Oct 9, 2025

Auto merge of #146069 - camsteffen:range-desugar-span, r=<try>

6557126

Mark desugared range expression spans with DesugaringKind::RangeExpr

rustbot added the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Oct 9, 2025

rustbot removed the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Oct 9, 2025

camsteffen force-pushed the range-desugar-span branch from 0cf87a7 to 7911460 Compare October 9, 2025 15:32

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camsteffen force-pushed the range-desugar-span branch 2 times, most recently from 7dce8b2 to b8af04c Compare October 9, 2025 15:54

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camsteffen added 3 commits October 21, 2025 09:59

Use inner span ctxt when lowering paren

3f4da0d

The need for this arose when encountering range expressions surrounded by parenthesis, where we want the span desugaring mark to be preserved.

Mark range expr with desugaring

3bdf45f

Reuse expr_needs_parens

6d61dad

camsteffen force-pushed the range-desugar-span branch from b8af04c to 6d61dad Compare October 21, 2025 15:05

bors 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 27, 2025

bors added the merged-by-bors This PR was explicitly merged by bors. label Oct 27, 2025

bors merged commit 23fced0 into rust-lang:master Oct 27, 2025
12 checks passed

rustbot added this to the 1.93.0 milestone Oct 27, 2025

camsteffen deleted the range-desugar-span branch October 27, 2025 13:01

rustbot added the perf-regression-triaged The performance regression has been triaged. label Oct 27, 2025

Mark desugared range expression spans with DesugaringKind::RangeExpr #146069

Mark desugared range expression spans with DesugaringKind::RangeExpr #146069

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Overall result: ❌ regressions - please read the text below

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Test differences

Job duration changes

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Overall result: ❌ regressions - please read the text below

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