Remove `Span` from segments of `AttrPath` #149790

JonathanBrouwer · 2025-12-08T22:10:53Z

r? jdonszelmann

JonathanBrouwer · 2025-12-08T22:10:58Z

[PERF] How much does lowering the spans in `AttrPath` matter?

rust-bors · 2025-12-09T00:32:25Z

☀️ Try build successful (CI)
Build commit: d9eae17 (d9eae17767db0f7c6391226cad0d92eee5466f69, parent: 5bc345055b06dc096b01bc6d1e0cbe92d3cc630e)

rust-timer · 2025-12-09T01:36:37Z

Finished benchmarking commit (d9eae17): 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)	0.3%	[0.2%, 0.5%]	2
Regressions ❌ (secondary)	1.9%	[1.9%, 1.9%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-0.2%	[-0.2%, -0.2%]	3
All ❌✅ (primary)	0.3%	[0.2%, 0.5%]	2

Max RSS (memory usage)

Results (primary -1.5%, secondary 3.1%)

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)	3.1%	[3.1%, 3.1%]	1
Improvements ✅ (primary)	-1.5%	[-1.5%, -1.5%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-1.5%	[-1.5%, -1.5%]	1

Cycles

Results (primary -2.6%, 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)	-2.6%	[-2.6%, -2.6%]	1
Improvements ✅ (secondary)	-3.8%	[-3.8%, -3.8%]	1
All ❌✅ (primary)	-2.6%	[-2.6%, -2.6%]	1

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)	0.0%	[0.0%, 0.0%]	4
Improvements ✅ (primary)	-0.0%	[-0.0%, -0.0%]	6
Improvements ✅ (secondary)	-0.1%	[-0.1%, -0.1%]	4
All ❌✅ (primary)	-0.0%	[-0.0%, -0.0%]	6

Bootstrap: 473.701s -> 471.996s (-0.36%)
Artifact size: 389.02 MiB -> 389.02 MiB (-0.00%)

JonathanBrouwer · 2025-12-09T08:51:34Z

@bors try @rust-timer queue

[PERF] How much does lowering the spans in `AttrPath` matter?

JonathanBrouwer · 2025-12-09T09:08:59Z

@bors try cancel

rust-bors · 2025-12-09T09:09:03Z

Try build cancelled. Cancelled workflows:

https://github.com/rust-lang/rust/actions/runs/20057460189

JonathanBrouwer · 2025-12-09T09:44:50Z

@bors try

[PERF] How much does lowering the spans in `AttrPath` matter?

rust-bors · 2025-12-09T12:01:55Z

☀️ Try build successful (CI)
Build commit: f3efcc9 (f3efcc98a6728b73780875235e1a77ae38c2c3ba, parent: 018d26972e523b8d28f9579056185a1713949dfd)

rust-timer · 2025-12-09T12:59:22Z

Finished benchmarking commit (f3efcc9): 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
Regressions ❌ (secondary)	0.3%	[0.1%, 0.5%]	2
Improvements ✅ (primary)	-0.2%	[-0.3%, -0.1%]	7
Improvements ✅ (secondary)	-0.2%	[-0.5%, -0.1%]	24
All ❌✅ (primary)	-0.2%	[-0.3%, -0.1%]	7

Max RSS (memory usage)

Results (primary -2.3%, secondary -1.2%)

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)	-2.3%	[-3.5%, -0.6%]	3
Improvements ✅ (secondary)	-1.2%	[-1.2%, -1.2%]	1
All ❌✅ (primary)	-2.3%	[-3.5%, -0.6%]	3

Cycles

Results (primary 2.1%)

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

	mean	range	count
Regressions ❌ (primary)	2.1%	[2.1%, 2.1%]	1
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	2.1%	[2.1%, 2.1%]	1

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%	[-0.2%, -0.0%]	32
Improvements ✅ (secondary)	-0.0%	[-0.1%, -0.0%]	15
All ❌✅ (primary)	-0.1%	[-0.2%, -0.0%]	32

Bootstrap: 472.223s -> 472.69s (0.10%)
Artifact size: 389.03 MiB -> 389.01 MiB (-0.01%)

bors · 2025-12-12T01:47:44Z

☔ The latest upstream changes (presumably #149645) made this pull request unmergeable. Please resolve the merge conflicts.

bors · 2025-12-14T08:59:11Z

☔ The latest upstream changes (presumably #146348) made this pull request unmergeable. Please resolve the merge conflicts.

JonathanBrouwer · 2025-12-22T15:27:10Z

src/tools/clippy/tests/ui/renamed_builtin_attr.stderr

+  --> tests/ui/renamed_builtin_attr.rs:3:3
   |
 LL | #[clippy::cyclomatic_complexity = "1"]
-   |           ^^^^^^^^^^^^^^^^^^^^^ help: consider using: `cognitive_complexity`


This error message is the only place in the entire repo where these spans were used. I think the new message is just as nice as the old one

JonathanBrouwer · 2025-12-22T15:27:21Z

@bors try @rust-timer queue

rust-timer · 2025-12-22T15:27:24Z

Awaiting bors try build completion.

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

rust-bors · 2025-12-22T15:27:26Z

⌛ Trying commit 7afba29 with merge 59abdd0…

To cancel the try build, run the command @bors try cancel.

Workflow: https://github.com/rust-lang/rust/actions/runs/20436305984

[PERF] How much does lowering the spans in `AttrPath` matter?

JonathanBrouwer · 2025-12-22T15:29:16Z

compiler/rustc_hir/src/hir.rs

 #[derive(Clone, Debug, HashStable_Generic, Encodable, Decodable)]
 pub struct AttrPath {
-    pub segments: Box<[Ident]>,
+    pub segments: Box<[Symbol]>,


This is the core change, everything else is processing the consequences of this line

rustbot · 2025-12-22T15:29:37Z

Some changes occurred in src/tools/clippy

cc @rust-lang/clippy

Some changes occurred in src/tools/rustfmt

cc @rust-lang/rustfmt

Some changes occurred in compiler/rustc_passes/src/check_attr.rs

cc @jdonszelmann

Some changes occurred in compiler/rustc_attr_parsing

cc @jdonszelmann

rustbot added A-attributes Area: Attributes (`#[…]`, `#![…]`) 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 Dec 8, 2025