Enforce even more library clippy lints in CI - #161328

ChrisDenton · 2026-08-18T21:59:00Z

Once again, this is best reviewed commit-by-commit since each commit fixes a lint.

I've bundled together a large(ish) number of lints because I feel they shouldn't be controversial and don't touch too much code. A large chunk of them is just telling clippy that, for example, implementing is_digit by calling is_digit just isn't going to work. I have reviewed each and every fix myself but please do double or triple check my working!

rustbot · 2026-08-18T21:59:04Z

Some changes occurred to the intrinsics. Make sure the CTFE / Miri interpreter
gets adapted for the changes, if necessary.

cc @rust-lang/miri, @RalfJung, @oli-obk, @lcnr

ChrisDenton · 2026-08-18T22:00:02Z

Btw, they'll likely be platform specific fixes that CI tells me about so I'll probably be updating these in a few hours.

ChrisDenton · 2026-08-18T22:02:07Z

-            match cond {
-                crate::option::Option::Some(cond) => {
-                    if !cond(&ret) {
-                        // Emit no unwind panic in case this was a safety requirement.
-                        crate::panicking::panic_nounwind("failed ensures check");
-                    }
-                },
-                crate::option::Option::None => {},
+            if let crate::option::Option::Some(cond) = cond {
+                if !cond(&ret) {
+                    // Emit no unwind panic in case this was a safety requirement.
+                    crate::panicking::panic_nounwind("failed ensures check");
+                }


This is the intrinsic that got people pinged (sorry). If you rather I didn't change this then please say!

View changes since the review

matthiaskrgr · 2026-08-18T22:07:09Z

@bors try @rust-timer queue

Enforce even more library clippy lints in CI

ChrisDenton · 2026-08-18T22:19:14Z

                    if next_read != next_write {
                        let ptr_write = prev_ptr_write.add(1);
-                        mem::swap(&mut *ptr_read, &mut *ptr_write);
+                        ptr::swap(ptr_read, ptr_write);


This should probably be looked at closer. Clippy says these do the same thing but it's possible going via an &mut is doing something useful.

View changes since the review

mem::swap will emit noalias so it assumes the areas don't overlap (thus better opts). I would say it's fine to use swap_nonoverlapping to make clippy happy as well here fwiw

Hm, it might be better to not enforce this lint since it's so situational.

this may be a deficiency in the clippy lint? &mut implies nonoverlapping, the lint should probably account for that.

Yeah, it should.

nia-e

mostly looks good, with a couple worries:

clippy wants us to do a lot more method calls. this is fine but needs a perf run for sure, and i'm a smidge worried about binary size and/or bootstrap time, esp since it might put more pressure on the inliner
a lot of these allows should be expects with a comment... but also, i'm not gonna do that to you chris ^^ that can be a later pr

let's see what a perf run comes up with before anything.

@bors try @rust-timer queue

View changes since this review

nia-e · 2026-08-18T22:07:44Z

@@ -1,5 +1,7 @@
 //! impl char {}

+#![allow(clippy::manual_is_ascii_check)]


Is this lint worth adding, given that it seems the only change is, uh, allowing it anyway? :D

I suppose there's the point of "let's add this so it doesn't show up in the future" which is fair but I'd like to know if that is indeed your specific intent here

Yeah. A lot of these #[allow] are to stop clippy complaining about the implementation of things it's linting for so when you run x clippy library you don't get a bunch of spurious warnings. I guess it is possible clippy might one day get smarter about this but it's more an us problem rather than a clippy problem per se.

nia-e · 2026-08-18T22:15:57Z

            ret
        } else {
-            match cond {
-                crate::option::Option::Some(cond) => {


why isn't this if let $whatever && !cond? of all things I'd expect clippy to yell about this nested if :D

Clippy moves in mysterious ways. Though it is entirely possible I missed the particular lint that would complain about it.

Enforce even more library clippy lints in CI

nia-e · 2026-08-18T22:34:56Z

huh, how did the comment from matthias not show up? apologies ^^ github has been odd

rust-bors · 2026-08-18T23:23:20Z

☀️ Try build successful (CI)
Build commit: 8906bf7 (8906bf76a8be8117da1f6c656fd34abfa6ebb3a0)
Base parent: e71c0f1 (e71c0f1e3395b10a8c331317be1a5c107bdf7b2e)

clarfonthey · 2026-08-18T23:25:30Z

Just comparing to my personal clippy lint list, what I see missing is:

borrow_as_ptr
default_trait_access
doc_markdown
filter_map_next
if_not_else
ignored_unit_patterns
inconsistent_struct_constructor
manual_assert
manual_is_power_of_two
map_unwrap_or
match_same_arms
missing_docs_in_private_items (the spiciest one, imho)
`needless_continue
needless_raw_string_hashes
redundant_closure_for_method_calls
redundant_else
ref_as_ptr
semicolon_if_nothing_returned
unnecessary_semicolon

Besides missing_docs_in_private_items being almost certainly undesired at the moment (unless we want more untriaged comments), I haven't actually checked which of these are most reasonable for libstd.

rust-timer · 2026-08-19T00:06:00Z

Finished benchmarking commit (8906bf7): comparison URL.

Overall result: ❌ regressions - no action needed

Benchmarking means the PR may be perf-sensitive. Consider adding rollup=never if this change is not fit for rolling up.

@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)	0.4%	[0.4%, 0.4%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Max RSS (memory usage)

Results (primary 0.9%, secondary 0.5%)

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

	mean	range	count
Regressions ❌ (primary)	2.3%	[2.1%, 2.4%]	2
Regressions ❌ (secondary)	3.3%	[3.3%, 3.3%]	1
Improvements ✅ (primary)	-1.9%	[-1.9%, -1.9%]	1
Improvements ✅ (secondary)	-2.2%	[-2.2%, -2.2%]	1
All ❌✅ (primary)	0.9%	[-1.9%, 2.4%]	3

Cycles

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

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)	0.3%	[0.0%, 0.5%]	2
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-0.1%	[-0.2%, -0.0%]	21
Improvements ✅ (secondary)	-0.1%	[-0.1%, -0.0%]	80
All ❌✅ (primary)	-0.1%	[-0.2%, 0.5%]	23

Bootstrap: 456.919s -> 457.665s (0.16%)
Artifact size: 398.99 MiB -> 398.96 MiB (-0.01%)

ChrisDenton · 2026-08-19T12:16:05Z

a lot of these allows should be expects with a comment... but also, i'm not gonna do that to you chris ^^ that can be a later pr

I went ahead and added a bunch of expect messages.

This can affect drop order

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 Aug 18, 2026

rustbot assigned nia-e Aug 18, 2026

ChrisDenton commented Aug 18, 2026

View reviewed changes