Port diagnostic attributes by mejrs · Pull Request #151558 · rust-lang/rust

mejrs · 2026-01-23T23:46:13Z

Ports all the diagnostic attributes: on_const, on_unimplemented and rustc_on_unimplemented.

I thought about migrating them one by one but that would leave a lot of code duplicated. So this PR looks big but it's mostly a lot of moving code around with slight modifications.

r? @JonathanBrouwer

cc @jdonszelmann feel free to review if you want, not sure which of you wants it.

JonathanBrouwer · 2026-01-23T23:54:41Z

@bors try @rust-timer queue

Port diagnosttic::unimplemented

rust-bors · 2026-01-24T02:12:50Z

☀️ Try build successful (CI)
Build commit: e5e5a65 (e5e5a6588240040eb81cfb52d8b9c3281547ef47, parent: d222ddc4d90743dfc1e53b610be8fc9d95893d2c)

rust-timer · 2026-01-24T02:54:28Z

Finished benchmarking commit (e5e5a65): comparison URL.

Overall result: ❌ regressions - no action needed

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.

@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%	[0.3%, 0.3%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Max RSS (memory usage)

Results (primary -1.7%, 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
Regressions ❌ (secondary)	3.9%	[3.9%, 3.9%]	1
Improvements ✅ (primary)	-1.7%	[-1.7%, -1.7%]	1
Improvements ✅ (secondary)	-4.2%	[-4.2%, -4.2%]	1
All ❌✅ (primary)	-1.7%	[-1.7%, -1.7%]	1

Cycles

Results (secondary -4.3%)

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
Improvements ✅ (secondary)	-4.3%	[-4.9%, -3.0%]	3
All ❌✅ (primary)	-	-	0

Binary size

This benchmark run did not return any relevant results for this metric.

Bootstrap: 470.684s -> 471.14s (0.10%)
Artifact size: 383.48 MiB -> 383.64 MiB (0.04%)

rustbot · 2026-02-18T23:30:37Z

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.

mejrs · 2026-02-19T01:08:02Z

I think that's everything,

@rustbot ready

jdonszelmann · 2026-02-19T16:24:24Z

@mejrs I think the only thing left here now is the templates right?

mejrs · 2026-02-19T21:01:41Z

@mejrs I think the only thing left here now is the templates right?

Oops. Pushed now.

JonathanBrouwer · 2026-02-20T09:08:35Z

@jdonszelmann r=me,you if you also approve the PR

jdonszelmann · 2026-02-20T09:09:57Z

@bors r=jdonszelmann,jonathanbrouwer rollup

rust-bors · 2026-02-20T09:10:00Z

📌 Commit 1556755 has been approved by jdonszelmann,jonathanbrouwer

It is now in the queue for this repository.

jdonszelmann · 2026-02-20T09:27:30Z

@bors r- #152759 first

jdonszelmann · 2026-02-20T19:43:02Z

@mejrs r=me after rebase

rust-bors · 2026-02-20T19:48:32Z

☔ The latest upstream changes (presumably #152904) made this pull request unmergeable. Please resolve the merge conflicts.

weiznich · 2026-02-22T14:20:20Z

compiler/rustc_hir/src/attrs/encode_cross_crate.rs

            NoMangle(..) => Yes, // Needed for rustdoc
            NoStd(..) => No,
            NonExhaustive(..) => Yes, // Needed for rustdoc
+            OnConst { .. } => Yes,


That's just a drive by comment, but I'm not 100% sure if that's really correct. In the past there was a bug were an unstable diagnostic attribute generated a warning in the parent crate, but had also generated the unstable custom error message if triggered by code in a child crate.

For that reason I changed the cross crate encoding for such attributes at some point to be depended on the feature gate for such unstable attributes.

That written: I'm do know nothing about diagnostic::on_const and the design of this PR, so this might not even apply. If that's the case feel free to just dismiss this comment.

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 Jan 23, 2026