Permit {This} in diagnostic attribute format literals

[mejrs]

My motivation was that yesterday I wanted to write something like this and reference $name in the string literal.

pub mod sym {
   // stuff here
}

macro_rules! my_macro {
    ($name:ident $(,)?) => {{
        #[diagnostic::on_unknown(
            message = "this is not present in symbol table",
            note = "you must add it to rustc_span::symbol::symbol!"
        )]
        use sym::$name as name;
        // ...
    }}
}

That is (as far as I can tell) impossible or at least very unergonomic. This adds the ability to just reference the name of the item the attribute is on. I imagine that's useful for use inside macros generally, so it's also added for some other attributes.

The affected attributes are all unstable, it is not implemented for diagnostic::on_unimplemented (will do in its own PR).

Note that {This} is already usable in #[rustc_on_unimplemented], so this does not implement it but just enables some more.

This PR also migrates one lint away from AttributeLintKind, and improves the messages for that lint.

[rustbot]

Some changes occurred in compiler/rustc_attr_parsing

cc @jdonszelmann, @JonathanBrouwer

[rustbot]

r? @petrochenkov

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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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Why was this reviewer chosen?

The reviewer was selected based on:

• Owners of files modified in this PR: compiler
• compiler expanded to 72 candidates
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[rustbot]

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

cc @jdonszelmann, @JonathanBrouwer

[petrochenkov]

@bors r+

[rust-bors]

📌 Commit ae94821 has been approved by petrochenkov

It is now in the queue for this repository.

[rustbot]

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]

@bors r=petrochenkov

[rust-bors]

📌 Commit c2916be has been approved by petrochenkov

It is now in the queue for this repository.

[rust-bors]

☀️ Test successful - CI
Approved by: petrochenkov
Duration: 3h 25m 47s
Pushing 80729d7 to main...

[github-actions]

What is this?

This is an experimental post-merge analysis report that shows differences in test outcomes between the merged PR and its parent PR.

Comparing 7c61a35 (parent) -> 80729d7 (this PR)

Test differences

Show 16 test diffs

Stage 1

• [ui] tests/ui/diagnostic_namespace/on_unknown/this_format_argument.rs: [missing] -> pass (J0)

Stage 2

• [ui] tests/ui/diagnostic_namespace/on_unknown/this_format_argument.rs: [missing] -> pass (J1)

Additionally, 14 doctest diffs were found. These are ignored, as they are noisy.

Job group index

• J0: x86_64-gnu-llvm-21-3, x86_64-gnu-llvm-22-3
• J1: aarch64-apple, aarch64-gnu, aarch64-gnu-llvm-21-1, aarch64-msvc-1, arm-android, armhf-gnu, dist-i586-gnu-i586-i686-musl, i686-gnu-1, i686-gnu-nopt-1, i686-msvc-1, optional-x86_64-gnu-parallel-frontend, test-various, x86_64-gnu, x86_64-gnu-debug, x86_64-gnu-gcc, x86_64-gnu-llvm-21, x86_64-gnu-llvm-21-2, x86_64-gnu-llvm-22-2, x86_64-gnu-nopt, x86_64-gnu-stable, x86_64-mingw-1, x86_64-msvc-1

Test dashboard

Run

cargo run --manifest-path src/ci/citool/Cargo.toml -- \
    test-dashboard 80729d7ce0ec05aef7a33d9892484cfd5cf34675 --output-dir test-dashboard

And then open test-dashboard/index.html in your browser to see an overview of all executed tests.

Job duration changes

1. pr-check-2: 35m 40s -> 45m 3s (+26.3%)
2. x86_64-mingw-2: 2h 11m -> 2h 43m (+24.3%)
3. i686-gnu-nopt-1: 2h 24m -> 1h 49m (-24.1%)
4. x86_64-gnu-llvm-21-3: 1h 33m -> 1h 50m (+19.2%)
5. arm-android: 1h 44m -> 1h 28m (-15.0%)
6. dist-ohos-aarch64: 1h 2m -> 1h 12m (+14.6%)
7. dist-ohos-x86_64: 1h 14m -> 1h 4m (-13.8%)
8. dist-sparcv9-solaris: 1h 32m -> 1h 20m (-13.5%)
9. pr-check-1: 33m 50s -> 29m 23s (-13.2%)
10. x86_64-mingw-1: 2h 25m -> 2h 43m (+12.5%)

How to interpret the job duration changes?

Job durations can vary a lot, based on the actual runner instance
that executed the job, system noise, invalidated caches, etc. The table above is provided
mostly for t-infra members, for simpler debugging of potential CI slow-downs.

[rust-timer]

Finished benchmarking commit (80729d7): comparison URL.

Overall result: ✅ improvements - no action needed

@rustbot label: -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
Improvements ✅ (secondary)	-0.2%	[-0.3%, -0.2%]	13
All ❌✅ (primary)	-	-	0

Max RSS (memory usage)

Results (secondary -1.9%)

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%	[1.1%, 2.2%]	3
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-5.6%	[-7.7%, -1.6%]	3
All ❌✅ (primary)	-	-	0

Cycles

Results (secondary -8.5%)

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)	-8.5%	[-19.4%, -2.4%]	3
All ❌✅ (primary)	-	-	0

Binary size

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

Bootstrap: 491.842s -> 492.349s (0.10%)
Artifact size: 394.33 MiB -> 394.32 MiB (-0.00%)