Port doc attributes to new attribute API

[GuillaumeGomez]

Part of #131229.

This PR ports the doc attributes to the new attribute API. However, there are things that will need to be fixed in a follow-up:

• Some part of cfg_old.rs are likely unused now, so they should be removed.
• Not all error/lints are emitted at the same time anymore, making them kinda less useful considering that you need to run and fix rustc/rustdoc multiple times to get through all of them.
• For coherency with the other attribute errors, I didn't modify the default output too much, meaning that we have some new messages now. I'll likely come back to that to check if the previous ones were better in a case-by-case approach.
• doc(test(attr(...))) is handled in a horrifying manner currently. Until we can handle it correctly with the Attribute system, it'll remain that thing we're all very ashamed of. 😈
• A type in rustdoc got its size increased, I'll check the impact on performance. But in any case, I plan to improve it in a follow-up so should be "ok".
• Because of error reporting, some fields of Doc are suboptimal, like inline which instead of being an Option is a ThinVec because we report the error later on. Part of the things I'm not super happy about but can be postponed to future me.

And finally, once this PR is merged, I plan to finally stabilize doc_cfg feature. :)

cc @jdonszelmann
r? @JonathanBrouwer

[rustbot]

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

cc @jdonszelmann

Some changes occurred in compiler/rustc_attr_parsing

cc @jdonszelmann

These commits modify the Cargo.lock file. Unintentional changes to Cargo.lock can be introduced when switching branches and rebasing PRs.

If this was unintentional then you should revert the changes before this PR is merged.
Otherwise, you can ignore this comment.

Some changes occurred in compiler/rustc_hir/src/attrs

cc @jdonszelmann

[GuillaumeGomez]

Just to be safe:

@bors try @rust-timer queue

[GuillaumeGomez]

Ah right, forgot about clippy. Updating it as well.

[rustbot]

Some changes occurred in src/tools/clippy

cc @rust-lang/clippy

[rust-bors]

☀️ Try build successful (CI)
Build commit: 4f24013 (4f240130369441697d5ccde454291d18ea71990c, parent: 5372fc9cb790c112ce707991b1fcc025cec8fdbe)

[rust-timer]

Finished benchmarking commit (4f24013): comparison URL.

Overall result: ❌✅ regressions and improvements - please read the text below

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.

Next Steps: If you can justify the regressions found in this try perf run, please do so in sufficient writing along with @rustbot label: +perf-regression-triaged. If not, please fix the regressions and do another perf run. If its results are neutral or positive, the label will be automatically removed.

@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)	1.0%	[0.2%, 3.1%]	30
Improvements ✅ (primary)	-0.5%	[-1.3%, -0.1%]	39
Improvements ✅ (secondary)	-0.6%	[-1.1%, -0.1%]	30
All ❌✅ (primary)	-0.5%	[-1.3%, -0.1%]	39

Max RSS (memory usage)

Results (primary -0.2%, secondary 1.5%)

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

	mean	range	count
Regressions ❌ (primary)	1.3%	[0.8%, 1.5%]	3
Regressions ❌ (secondary)	3.6%	[1.4%, 6.4%]	11
Improvements ✅ (primary)	-1.0%	[-2.3%, -0.5%]	6
Improvements ✅ (secondary)	-1.4%	[-2.5%, -0.6%]	8
All ❌✅ (primary)	-0.2%	[-2.3%, 1.5%]	9

Cycles

Results (secondary 2.0%)

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)	4.1%	[2.2%, 9.8%]	8
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-3.8%	[-5.5%, -2.2%]	3
All ❌✅ (primary)	-	-	0

Binary size

Results (primary -0.5%, 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)	0.1%	[0.0%, 0.3%]	23
Regressions ❌ (secondary)	0.0%	[0.0%, 0.0%]	9
Improvements ✅ (primary)	-0.9%	[-3.1%, -0.0%]	28
Improvements ✅ (secondary)	-0.2%	[-0.3%, -0.0%]	15
All ❌✅ (primary)	-0.5%	[-3.1%, 0.3%]	51

Bootstrap: 468.725s -> 473.041s (0.92%)
Artifact size: 386.77 MiB -> 389.06 MiB (0.59%)

[GuillaumeGomez]

Strange, one doc test has a regression but all others are faster.

[bors]

☔ The latest upstream changes (presumably #149646) made this pull request unmergeable. Please resolve the merge conflicts.

[JonathanBrouwer]

I'd say since perf looks very good on primary benchmarks and is mixed on secondary benchmarks, I'm happy with perf as-is. I am wondering what caused the regression on include-blob though, it doesn't even use any doc attributes
@rustbot label: +perf-regression-triaged

[bors]

☔ The latest upstream changes (presumably #149701) made this pull request unmergeable. Please resolve the merge conflicts.

[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.

[rust-log-analyzer]

The job aarch64-gnu-llvm-20-2 failed! Check out the build log: (web) (plain enhanced) (plain)

Click to see the possible cause of the failure (guessed by this bot)

fmt check
fmt: checked 6591 files
tidy check
tidy [rustdoc_json (src)]: `rustdoc-json-types` modified, checking format version
tidy [fluent_used (compiler)]: /checkout/compiler/rustc_attr_parsing/messages.ftl: message `attr_parsing_empty_attribute` is not used
tidy [fluent_used (compiler)]: FAIL
tidy: Skipping binary file check, read-only filesystem
tidy: The following check failed: fluent_used (compiler)
Command `/checkout/obj/build/aarch64-unknown-linux-gnu/stage1-tools-bin/rust-tidy /checkout /checkout/obj/build/aarch64-unknown-linux-gnu/stage0/bin/cargo /checkout/obj/build 4 yarn` failed with exit code 1
Created at: src/bootstrap/src/core/build_steps/tool.rs:1612:23
Executed at: src/bootstrap/src/core/build_steps/test.rs:1314:29

Command has failed. Rerun with -v to see more details.
Bootstrap failed while executing `--stage 2 test --skip tests --skip coverage-map --skip coverage-run --skip library --skip tidyselftest`
Build completed unsuccessfully in 0:00:47
  local time: Sat Dec  6 21:39:33 UTC 2025
  network time: Sat, 06 Dec 2025 21:39:33 GMT
##[error]Process completed with exit code 1.