Cleanup and optimize `render_impls` by yotamofek · Pull Request #157540 · rust-lang/rust

yotamofek · 2026-06-06T17:48:25Z

take ownership of the Vec<&Impl> instead of copying into another alloc
reuse ImplString to do natural sort ordering
lazy formatting

Somewhat of a follow-up to #157233 and #157179 (cc @nnethercote - thanks!)
This kinda undoes f7c8bc2 but IMHO it makes more sense to be explicit about negative impl ordering, and also seems kinda wasteful to "render" the negativity into a string and rely on however ASCII decided to order characters. I can also undo this part, I think this PR is still a positive change even without it.

r? @GuillaumeGomez

LLM disclosure:
I used LLM for reviewing my changes and making sure some assumptions I was making were correct (i.e. that render_impls will not render anything IFF the list of traits passed to it is empty)

yotamofek · 2026-06-06T17:49:11Z

I doubt it'll register on perf, but I do think this should be an optimization (albeit a small one) so let's run perf anyways

@bors try @rust-timer queue

…, r=<try> Cleanup and optimize `render_impls`

yotamofek · 2026-06-06T17:57:14Z

A job failed! Check out the build log: (web) (plain enhanced) (plain)
Click to see the possible cause of the failure (guessed by this bot)

Docker error
hopefully try build will still work

rust-bors · 2026-06-06T19:59:22Z

☀️ Try build successful (CI)
Build commit: 19872c0 (19872c0f5e198bd2f48c9898b0b0e83f77aa8dbf, parent: 8954863c81df429ebf96ea38a16c76f209995833)

rust-timer · 2026-06-06T20:45:12Z

Finished benchmarking commit (19872c0): 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
@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%	[-0.5%, -0.1%]	8
Improvements ✅ (secondary)	-0.2%	[-0.3%, -0.2%]	3
All ❌✅ (primary)	-0.2%	[-0.5%, -0.1%]	8

Max RSS (memory usage)

Results (primary 0.6%, 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)	7.0%	[6.8%, 7.1%]	2
Regressions ❌ (secondary)	3.9%	[2.6%, 6.0%]	4
Improvements ✅ (primary)	-3.6%	[-5.2%, -2.6%]	3
Improvements ✅ (secondary)	-2.0%	[-2.0%, -2.0%]	1
All ❌✅ (primary)	0.6%	[-5.2%, 7.1%]	5

Cycles

Results (primary 3.4%, secondary 3.5%)

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

	mean	range	count
Regressions ❌ (primary)	3.4%	[1.5%, 6.0%]	102
Regressions ❌ (secondary)	3.5%	[2.1%, 7.0%]	90
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	3.4%	[1.5%, 6.0%]	102

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)	0.0%	[0.0%, 0.1%]	30
Regressions ❌ (secondary)	0.0%	[0.0%, 0.1%]	6
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.0%	[0.0%, 0.1%]	30

Bootstrap: 514.086s -> 513.359s (-0.14%)
Artifact size: 400.74 MiB -> 400.64 MiB (-0.03%)

rustbot · 2026-06-06T21:25:43Z

This PR was rebased onto a different main 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.

yotamofek · 2026-06-06T21:26:29Z

Perf results are a pleasant surprise! 🦆
Force pushed without any changes to trigger new CI run

GuillaumeGomez · 2026-06-06T21:32:30Z

Nice, well done! r=me once CI pass.

- take ownership of the `Vec<&Impl>` instead of copying into another alloc - reuse `ImplString` to do natural sort ordering - lazy formatting

yotamofek · 2026-06-07T08:06:33Z

The test failed because the order of the IDs changed, the displayed order actually didn't.
(and the IDs kinda make more sense now as they're ordered by display order, not by appearing-in-source order. not that it matters)

so updated the test accordingly

this is the diff of the HTML output before and after this PR:

diff --git a/struct.S.html b/struct.S.html
index 627987947fb..32dd5469c2c 100644
--- a/struct.S.html
+++ b/struct.S.html
@@ -99,27 +99,27 @@
                             </section>
                         </summary>
                         <div class="impl-items">
-                            <section id="associatedconstant.C-2" class="associatedconstant trait-impl"><a
+                            <section id="associatedconstant.C" class="associatedconstant trait-impl"><a
                                     class="src rightside"
                                     href="../src/issue_33302/const-rendering-macros-33302.rs.html#54">Source</a><a
-                                    href="#associatedconstant.C-2" class="anchor">§</a>
+                                    href="#associatedconstant.C" class="anchor">§</a>
                                 <h4 class="code-header">const <a href="trait.T.html#associatedconstant.C"
                                         class="constant">C</a>: (<a class="primitive"
                                         href="https://doc.rust-lang.org/nightly/std/primitive.i32.html">i32</a>, <a
                                         class="primitive"
                                         href="https://doc.rust-lang.org/nightly/std/primitive.i32.html">i32</a>)</h4>
                             </section>
-                            <section id="associatedconstant.D-2" class="associatedconstant trait-impl"><a
+                            <section id="associatedconstant.D" class="associatedconstant trait-impl"><a
                                     class="src rightside"
                                     href="../src/issue_33302/const-rendering-macros-33302.rs.html#54">Source</a><a
-                                    href="#associatedconstant.D-2" class="anchor">§</a>
+                                    href="#associatedconstant.D" class="anchor">§</a>
                                 <h4 class="code-header">const <a href="trait.T.html#associatedconstant.D"
                                         class="constant">D</a>: <a class="primitive"
                                         href="https://doc.rust-lang.org/nightly/std/primitive.i32.html">i32</a></h4>
                             </section>
-                            <section id="method.ignore-2" class="method trait-impl"><a class="src rightside"
+                            <section id="method.ignore" class="method trait-impl"><a class="src rightside"
                                     href="../src/issue_33302/const-rendering-macros-33302.rs.html#54">Source</a><a
-                                    href="#method.ignore-2" class="anchor">§</a>
+                                    href="#method.ignore" class="anchor">§</a>
                                 <h4 class="code-header">fn <a href="trait.T.html#method.ignore" class="fn">ignore</a>(_:
                                     <a class="primitive"
                                         href="https://doc.rust-lang.org/nightly/std/primitive.reference.html">&amp;X</a>)
@@ -180,28 +180,28 @@
                             </section>
                         </summary>
                         <div class="impl-items">
-                            <section id="associatedconstant.C" class="associatedconstant trait-impl"><a
+                            <section id="associatedconstant.C-2" class="associatedconstant trait-impl"><a
                                     class="src rightside"
                                     href="../src/issue_33302/const-rendering-macros-33302.rs.html#54">Source</a><a
-                                    href="#associatedconstant.C" class="anchor">§</a>
+                                    href="#associatedconstant.C-2" class="anchor">§</a>
                                 <h4 class="code-header">const <a href="trait.T.html#associatedconstant.C"
                                         class="constant">C</a>: [<a class="primitive"
                                         href="https://doc.rust-lang.org/nightly/std/primitive.i32.html">i32</a>; <a
                                         class="primitive"
                                         href="https://doc.rust-lang.org/nightly/std/primitive.array.html">16</a>]</h4>
                             </section>
-                            <section id="method.ignore" class="method trait-impl"><a class="src rightside"
+                            <section id="method.ignore-2" class="method trait-impl"><a class="src rightside"
                                     href="../src/issue_33302/const-rendering-macros-33302.rs.html#54">Source</a><a
-                                    href="#method.ignore" class="anchor">§</a>
+                                    href="#method.ignore-2" class="anchor">§</a>
                                 <h4 class="code-header">fn <a href="trait.T.html#method.ignore" class="fn">ignore</a>(_:
                                     <a class="primitive"
                                         href="https://doc.rust-lang.org/nightly/std/primitive.reference.html">&amp;X</a>)
                                 </h4>
                             </section>
-                            <section id="associatedconstant.D" class="associatedconstant trait-impl"><a
+                            <section id="associatedconstant.D-2" class="associatedconstant trait-impl"><a
                                     class="src rightside"
                                     href="../src/issue_33302/const-rendering-macros-33302.rs.html#54">Source</a><a
-                                    href="#associatedconstant.D" class="anchor">§</a>
+                                    href="#associatedconstant.D-2" class="anchor">§</a>
                                 <h4 class="code-header">const <a href="trait.T.html#associatedconstant.D"
                                         class="constant">D</a>: <a class="primitive"
                                         href="https://doc.rust-lang.org/nightly/std/primitive.i32.html">i32</a> = _</h4>
@@ -443,10 +443,10 @@
                         <div class="impl-items">
                             <details class="toggle" open>
                                 <summary>
-                                    <section id="associatedtype.Error-1" class="associatedtype trait-impl"><a
+                                    <section id="associatedtype.Error" class="associatedtype trait-impl"><a
                                             class="src rightside"
                                             href="https://doc.rust-lang.org/nightly/src/core/convert/mod.rs.html#831">Source</a><a
-                                            href="#associatedtype.Error-1" class="anchor">§</a>
+                                            href="#associatedtype.Error" class="anchor">§</a>
                                         <h4 class="code-header">type <a
                                                 href="https://doc.rust-lang.org/nightly/core/convert/trait.TryFrom.html#associatedtype.Error"
                                                 class="associatedtype">Error</a> = <a class="enum"
@@ -496,10 +496,10 @@
                         <div class="impl-items">
                             <details class="toggle" open>
                                 <summary>
-                                    <section id="associatedtype.Error" class="associatedtype trait-impl"><a
+                                    <section id="associatedtype.Error-1" class="associatedtype trait-impl"><a
                                             class="src rightside"
                                             href="https://doc.rust-lang.org/nightly/src/core/convert/mod.rs.html#815">Source</a><a
-                                            href="#associatedtype.Error" class="anchor">§</a>
+                                            href="#associatedtype.Error-1" class="anchor">§</a>
                                         <h4 class="code-header">type <a
                                                 href="https://doc.rust-lang.org/nightly/core/convert/trait.TryInto.html#associatedtype.Error"
                                                 class="associatedtype">Error</a> = &lt;U as <a class="trait"

yotamofek · 2026-06-07T10:25:29Z

@GuillaumeGomez just making sure you're still ok with r=you with the modification to the test

GuillaumeGomez · 2026-06-07T10:50:18Z

Yup all good, thanks again!

@bors r+ rollup=iffy

rust-bors · 2026-06-07T10:50:20Z

📌 Commit 0053d76 has been approved by GuillaumeGomez

It is now in the queue for this repository.

@nnethercote

…pls-cleanup, r=GuillaumeGomez Cleanup and optimize `render_impls` - take ownership of the `Vec<&Impl>` instead of copying into another alloc - reuse `ImplString` to do natural sort ordering - lazy formatting Somewhat of a follow-up to rust-lang#157233 and rust-lang#157179 (cc @nnethercote - thanks!) This kinda undoes rust-lang@f7c8bc2 but IMHO it makes more sense to be explicit about negative impl ordering, and also seems kinda wasteful to "render" the negativity into a string and rely on however ASCII decided to order characters. I can also undo this part, I think this PR is still a positive change even without it. r? @GuillaumeGomez LLM disclosure: I used LLM for reviewing my changes and making sure some assumptions I was making were correct (i.e. that `render_impls` will not render anything IFF the list of traits passed to it is empty)

@nnethercote

…pls-cleanup, r=GuillaumeGomez Cleanup and optimize `render_impls` - take ownership of the `Vec<&Impl>` instead of copying into another alloc - reuse `ImplString` to do natural sort ordering - lazy formatting Somewhat of a follow-up to rust-lang#157233 and rust-lang#157179 (cc @nnethercote - thanks!) This kinda undoes rust-lang@f7c8bc2 but IMHO it makes more sense to be explicit about negative impl ordering, and also seems kinda wasteful to "render" the negativity into a string and rely on however ASCII decided to order characters. I can also undo this part, I think this PR is still a positive change even without it. r? @GuillaumeGomez LLM disclosure: I used LLM for reviewing my changes and making sure some assumptions I was making were correct (i.e. that `render_impls` will not render anything IFF the list of traits passed to it is empty)

…uwer Rollup of 10 pull requests Successful merges: - #157447 (Move cross crate tests into the appropriate folder) - #145108 (Resolver: Batched Import Resolution) - #156119 (Further optimize `SliceIndex<str>` impl for `Range<usize>`) - #157289 (Add infallible primitive type lookups to template arg resolver) - #157540 (Cleanup and optimize `render_impls`) - #157543 (Reorganize `tests/ui/issues` [5/N]) - #156188 (riscv: promote d, e, and f target_features to CfgStableToggleUnstable) - #157323 (Document Repeat::last panic behavior) - #157545 (Suggest using comma to separate valid attribute list items) - #157559 (chore: Update annotate-snippets to 0.12.16)

@nnethercote

…pls-cleanup, r=GuillaumeGomez Cleanup and optimize `render_impls` - take ownership of the `Vec<&Impl>` instead of copying into another alloc - reuse `ImplString` to do natural sort ordering - lazy formatting Somewhat of a follow-up to rust-lang#157233 and rust-lang#157179 (cc @nnethercote - thanks!) This kinda undoes rust-lang@f7c8bc2 but IMHO it makes more sense to be explicit about negative impl ordering, and also seems kinda wasteful to "render" the negativity into a string and rely on however ASCII decided to order characters. I can also undo this part, I think this PR is still a positive change even without it. r? @GuillaumeGomez LLM disclosure: I used LLM for reviewing my changes and making sure some assumptions I was making were correct (i.e. that `render_impls` will not render anything IFF the list of traits passed to it is empty)

@nnethercote

…pls-cleanup, r=GuillaumeGomez Cleanup and optimize `render_impls` - take ownership of the `Vec<&Impl>` instead of copying into another alloc - reuse `ImplString` to do natural sort ordering - lazy formatting Somewhat of a follow-up to rust-lang#157233 and rust-lang#157179 (cc @nnethercote - thanks!) This kinda undoes rust-lang@f7c8bc2 but IMHO it makes more sense to be explicit about negative impl ordering, and also seems kinda wasteful to "render" the negativity into a string and rely on however ASCII decided to order characters. I can also undo this part, I think this PR is still a positive change even without it. r? @GuillaumeGomez LLM disclosure: I used LLM for reviewing my changes and making sure some assumptions I was making were correct (i.e. that `render_impls` will not render anything IFF the list of traits passed to it is empty)

Rollup of 25 pull requests Successful merges: - #157447 (Move cross crate tests into the appropriate folder) - #145108 (Resolver: Batched Import Resolution) - #156119 (Further optimize `SliceIndex<str>` impl for `Range<usize>`) - #157224 (Manually unroll loop in `str::floor_char_boundary`) - #157289 (Add infallible primitive type lookups to template arg resolver) - #157540 (Cleanup and optimize `render_impls`) - #157444 (Couple of work product cleanups) - #157543 (Reorganize `tests/ui/issues` [5/N]) - #153513 (Syntactically reject equality predicates) - #155797 (LineWriter: cap write_vectored newline scan to avoid quadratic write_all_vectored) - #156155 (macros: report unbound metavariables directly) - #156188 (riscv: promote d, e, and f target_features to CfgStableToggleUnstable) - #156666 (Clarify meaning of ranges in pointer offset docs) - #157078 (Document equivalence of `highest_one` and `ilog2` methods on integers) - #157129 (ci: update download-artifact action to v8) - #157169 (triagebot: Update messages to direct changes to appropriate repositories) - #157323 (Document Repeat::last panic behavior) - #157370 (Clarify MaybeUninit::zeroed padding docs) - #157399 (Silence llbc's output by default to prevent rustc's linker output warning) - #157500 (Improve documentation of `align_of` and `Alignment`.) - #157545 (Suggest using comma to separate valid attribute list items) - #157559 (chore: Update annotate-snippets to 0.12.16) - #157560 (In `copy_nonoverlapping`, use `mul nuw nsw` to compute the byte size) - #157580 (Importing suggestion reported twice when reporting privacy error) - #157581 (Test fixup)

@nnethercote

Rollup merge of #157540 - yotamofek:pr/rustdoc/render_all_impls-cleanup, r=GuillaumeGomez Cleanup and optimize `render_impls` - take ownership of the `Vec<&Impl>` instead of copying into another alloc - reuse `ImplString` to do natural sort ordering - lazy formatting Somewhat of a follow-up to #157233 and #157179 (cc @nnethercote - thanks!) This kinda undoes f7c8bc2 but IMHO it makes more sense to be explicit about negative impl ordering, and also seems kinda wasteful to "render" the negativity into a string and rely on however ASCII decided to order characters. I can also undo this part, I think this PR is still a positive change even without it. r? @GuillaumeGomez LLM disclosure: I used LLM for reviewing my changes and making sure some assumptions I was making were correct (i.e. that `render_impls` will not render anything IFF the list of traits passed to it is empty)

Rollup of 25 pull requests Successful merges: - rust-lang/rust#157447 (Move cross crate tests into the appropriate folder) - rust-lang/rust#145108 (Resolver: Batched Import Resolution) - rust-lang/rust#156119 (Further optimize `SliceIndex<str>` impl for `Range<usize>`) - rust-lang/rust#157224 (Manually unroll loop in `str::floor_char_boundary`) - rust-lang/rust#157289 (Add infallible primitive type lookups to template arg resolver) - rust-lang/rust#157540 (Cleanup and optimize `render_impls`) - rust-lang/rust#157444 (Couple of work product cleanups) - rust-lang/rust#157543 (Reorganize `tests/ui/issues` [5/N]) - rust-lang/rust#153513 (Syntactically reject equality predicates) - rust-lang/rust#155797 (LineWriter: cap write_vectored newline scan to avoid quadratic write_all_vectored) - rust-lang/rust#156155 (macros: report unbound metavariables directly) - rust-lang/rust#156188 (riscv: promote d, e, and f target_features to CfgStableToggleUnstable) - rust-lang/rust#156666 (Clarify meaning of ranges in pointer offset docs) - rust-lang/rust#157078 (Document equivalence of `highest_one` and `ilog2` methods on integers) - rust-lang/rust#157129 (ci: update download-artifact action to v8) - rust-lang/rust#157169 (triagebot: Update messages to direct changes to appropriate repositories) - rust-lang/rust#157323 (Document Repeat::last panic behavior) - rust-lang/rust#157370 (Clarify MaybeUninit::zeroed padding docs) - rust-lang/rust#157399 (Silence llbc's output by default to prevent rustc's linker output warning) - rust-lang/rust#157500 (Improve documentation of `align_of` and `Alignment`.) - rust-lang/rust#157545 (Suggest using comma to separate valid attribute list items) - rust-lang/rust#157559 (chore: Update annotate-snippets to 0.12.16) - rust-lang/rust#157560 (In `copy_nonoverlapping`, use `mul nuw nsw` to compute the byte size) - rust-lang/rust#157580 (Importing suggestion reported twice when reporting privacy error) - rust-lang/rust#157581 (Test fixup)

rustbot assigned GuillaumeGomez Jun 6, 2026

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Auto merge of #157540 - yotamofek:pr/rustdoc/render_all_impls-cleanup…

19872c0

…, r=<try> Cleanup and optimize `render_impls`

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rustbot removed the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Jun 6, 2026

yotamofek force-pushed the pr/rustdoc/render_all_impls-cleanup branch from 1b36eaf to 183502d Compare June 6, 2026 21:25

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Cleanup and optimize render_impls

0053d76

- take ownership of the `Vec<&Impl>` instead of copying into another alloc - reuse `ImplString` to do natural sort ordering - lazy formatting

yotamofek force-pushed the pr/rustdoc/render_all_impls-cleanup branch from 183502d to 0053d76 Compare June 7, 2026 08:06

GuillaumeGomez approved these changes Jun 7, 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 Jun 7, 2026

JonathanBrouwer mentioned this pull request Jun 7, 2026

Rollup of 11 pull requests #157569

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Rollup of 10 pull requests #157570

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Rollup of 21 pull requests #157582

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Rollup of 21 pull requests #157583

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Rollup of 25 pull requests #157586

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rust-bors Bot merged commit 5e09019 into rust-lang:main Jun 8, 2026
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Overall result: ✅ improvements - no action needed

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