Implement feature `integer_casts` by orlp · Pull Request #157402 · rust-lang/rust

orlp · 2026-06-03T23:13:49Z

Tracking issue: #157388

rustbot · 2026-06-03T23:13:55Z

rustbot has assigned @Mark-Simulacrum.
They will have a look at your PR within the next two weeks and either review your PR or reassign to another reviewer.

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Owners of files modified in this PR: libs
libs expanded to 8 candidates
Random selection from Mark-Simulacrum, jhpratt

jhpratt

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rustbot · 2026-06-07T02:28:39Z

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

orlp · 2026-06-07T09:49:37Z

@rustbot ready

jhpratt · 2026-06-07T18:32:21Z

That wording works for me.

@bors r+ rollup

rust-bors · 2026-06-07T18:32:24Z

📌 Commit 9d5fa40 has been approved by jhpratt

It is now in the queue for this repository.

Implement feature `integer_casts` Tracking issue: rust-lang#157388

rust-log-analyzer · 2026-06-08T02:28:43Z

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)

jieyouxu · 2026-06-08T04:40:46Z

@bors p=101
@bors retry

rust-bors · 2026-06-08T04:40:52Z

⌛ Testing commit d79b87b with merge 47e54da...

Workflow: https://github.com/rust-lang/rust/actions/runs/27116431268

Implement feature `integer_casts` Tracking issue: #157388

jhpratt · 2026-06-08T04:53:35Z

@bors treeclosed-

@bors yield

Yielding so that the rollup=nevers get a chance to run before things get busier with the start of business hours in Europe. An n=4 rollup doesn't make much sense when there's 3 nevers waiting.

rust-bors · 2026-06-08T04:53:38Z

Tree is now open for merging.

rust-bors · 2026-06-08T04:53:39Z

Auto build was cancelled. Cancelled workflows:

https://github.com/rust-lang/rust/actions/runs/27116431268

The next pull request likely to be tested is #157402.

rust-bors · 2026-06-08T04:53:42Z

⌛ Testing commit d79b87b with merge e6f8fdb...

Workflow: https://github.com/rust-lang/rust/actions/runs/27116808211

Implement feature `integer_casts` Tracking issue: #157388

jhpratt · 2026-06-08T04:53:49Z

@bors p=0

@bors yield

rust-bors · 2026-06-08T04:53:52Z

Auto build was cancelled. Cancelled workflows:

https://github.com/rust-lang/rust/actions/runs/27116808211

The next pull request likely to be tested is #155607.

…uwer Rollup of 9 pull requests Successful merges: - #157599 (`rust-analyzer` subtree update) - #157298 (Use alternate means of detecting enums in `is_udt`) - #155338 (Staticlib hide internal symbols) - #157402 (Implement feature `integer_casts`) - #157452 (Fix WASI links) - #157535 (Rename `errors.rs` file to `diagnostics.rs` (2/N)) - #157585 (Rename `errors.rs` file to `diagnostics.rs` (3/N)) - #157588 (Use `mul nuw nsw` in `intrinsics::copy`) - #157592 (Suggest comma multiple)

Rollup merge of #157402 - orlp:int-cast, r=jhpratt Implement feature `integer_casts` Tracking issue: #157388

Mark-Simulacrum · 2026-06-09T02:07:57Z

@rust-timer build d65ab4d

cc #157600 (comment)

rust-timer · 2026-06-09T03:49:25Z

Finished benchmarking commit (d65ab4d): comparison URL.

Overall result: ❌✅ regressions and improvements - please read:

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.

Next, please: If you can, justify the regressions found in this try perf run in writing along with @rustbot label: +perf-regression-triaged. If not, fix the regressions and do another perf run. Neutral or positive results will clear the label automatically.

@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)	0.6%	[0.2%, 1.6%]	16
Regressions ❌ (secondary)	1.1%	[0.3%, 1.8%]	24
Improvements ✅ (primary)	-0.3%	[-0.5%, -0.3%]	4
Improvements ✅ (secondary)	-0.4%	[-1.0%, -0.2%]	7
All ❌✅ (primary)	0.4%	[-0.5%, 1.6%]	20

Max RSS (memory usage)

Results (primary 1.3%, secondary 3.6%)

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

	mean	range	count
Regressions ❌ (primary)	1.3%	[1.0%, 1.5%]	5
Regressions ❌ (secondary)	3.6%	[3.6%, 3.6%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	1.3%	[1.0%, 1.5%]	5

Cycles

Results (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)	-	-	0
Regressions ❌ (secondary)	1.8%	[1.8%, 1.8%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-3.5%	[-6.1%, -2.3%]	7
All ❌✅ (primary)	-	-	0

Binary size

This perf run didn't have relevant results for this metric.

Bootstrap: 516.268s -> 516.499s (0.04%)
Artifact size: 400.81 MiB -> 400.82 MiB (0.00%)

JonathanBrouwer · 2026-06-09T06:21:11Z

Caused the perf regression in #157600
Is there anything we can do about this?

jhpratt · 2026-06-09T06:57:31Z

I'm unsure how it could cause such a significant change in the first place, to be honest.

orlp · 2026-06-09T08:28:26Z

@jhpratt @JonathanBrouwer I think it's fairly obvious. All the regressions are for creating docs. This PR adds ~288 trait implementations to the standard library that end up being documented/processed.

If the trait ends up being perma-unstable I can see us #[doc(hidden)] them, but if the goal is to eventually stabilize them as well (so you can write e.g. u8::checked_cast_from), I don't think there's much we can do.

JonathanBrouwer · 2026-06-09T08:30:40Z

Does adding trait impls to the stdlib also make downstream crates slower to document? I guess that makes sense to some degree but still interesting

orlp · 2026-06-09T08:52:03Z

Yes, but also not by much. Adding 288 new impls is quite a lot and only resulted in 0.3-1% slowdowns, with 1.5% being an exception on hello world. The latter crate naturally is the fastest to document in the first place, meaning any fixed overhead shows up more.

It's not my decision but I don't think further action is required at this time.

JonathanBrouwer · 2026-06-09T09:03:03Z

I agree, but I'll cc the rustdoc team so they at least know about it

Cc @rust-lang/rustdoc

rustbot assigned Mark-Simulacrum Jun 3, 2026

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-libs Relevant to the library team, which will review and decide on the PR/issue. labels Jun 3, 2026

orlp mentioned this pull request Jun 3, 2026

Tracking Issue for integer_casts #157388

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6 tasks

orlp force-pushed the int-cast branch from 7d20958 to 973b0e5 Compare June 3, 2026 23:16

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orlp force-pushed the int-cast branch from 973b0e5 to 0a6eef9 Compare June 3, 2026 23:19

jhpratt reviewed Jun 7, 2026

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Comment thread library/core/src/convert/num.rs Outdated

Comment thread library/core/src/convert/num.rs Outdated

Comment thread library/core/src/convert/num.rs Outdated

Comment thread library/core/src/num/int_macros.rs Outdated

rustbot assigned jhpratt and unassigned Mark-Simulacrum Jun 7, 2026

rustbot removed the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Jun 7, 2026

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JonathanBrouwer added a commit to JonathanBrouwer/rust that referenced this pull request Jun 7, 2026

Rollup merge of rust-lang#157402 - orlp:int-cast, r=jhpratt

494816a

Implement feature `integer_casts` Tracking issue: rust-lang#157388

jhpratt added a commit to jhpratt/rust that referenced this pull request Jun 7, 2026

Rollup merge of rust-lang#157402 - orlp:int-cast, r=jhpratt

8a28376

Implement feature `integer_casts` Tracking issue: rust-lang#157388

JonathanBrouwer mentioned this pull request Jun 7, 2026

Rollup of 21 pull requests #157582

Closed

jhpratt mentioned this pull request Jun 7, 2026

Rollup of 21 pull requests #157583

Closed

rust-bors Bot 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-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. labels Jun 7, 2026

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orlp added 2 commits June 8, 2026 00:43

Implement feature integer_casts

ac38744

Use impl(self) instead of Sealed

537b091

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 8, 2026

rust-bors Bot mentioned this pull request Jun 8, 2026

Use mul nuw nsw in intrinsics::copy #157588

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rust-bors Bot pushed a commit that referenced this pull request Jun 8, 2026

Auto merge of #157402 - orlp:int-cast, r=jhpratt

47e54da

Implement feature `integer_casts` Tracking issue: #157388

rust-bors Bot pushed a commit that referenced this pull request Jun 8, 2026

Auto merge of #157402 - orlp:int-cast, r=jhpratt

e6f8fdb

Implement feature `integer_casts` Tracking issue: #157388

JonathanBrouwer mentioned this pull request Jun 8, 2026

Rollup of 9 pull requests #157600

Merged

rust-bors Bot merged commit 150c383 into rust-lang:main Jun 8, 2026
2 of 13 checks passed

rustbot added this to the 1.98.0 milestone Jun 8, 2026

rust-timer added a commit that referenced this pull request Jun 8, 2026

Unrolled build for #157402

d65ab4d

Rollup merge of #157402 - orlp:int-cast, r=jhpratt Implement feature `integer_casts` Tracking issue: #157388

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rust-timer commented Jun 9, 2026

Overall result: ❌✅ regressions and improvements - please read:

Instruction count

Max RSS (memory usage)

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Binary size

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