Replace check_attr_crate_level with check_target for #[doc] by evavh · Pull Request #161521 · rust-lang/rust

evavh · 2026-08-22T12:50:29Z

A small change as part of the target checking refactor for #[doc] attribute parsing.

rustbot · 2026-08-22T12:50:32Z

Some changes occurred in compiler/rustc_attr_parsing

mejrs · 2026-08-22T13:38:33Z

-                    return;
-                }
+                cx.check_target(
+                    &sym::no_crate_inject.to_string(),


Suggested change

&sym::no_crate_inject.to_string(),

sym::no_crate_inject.as_str()

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mejrs · 2026-08-22T13:39:56Z

-                    return;
-                }
+                cx.check_target(
+                    &s.to_string(),


Suggested change

&s.to_string(),

s.as_str(),

View changes since the review

JonathanBrouwer · 2026-08-22T16:26:17Z

-                    return;
-                }
+                cx.check_target(
+                concat!("(", stringify!($ident), ")"),


Could you make tests for these cases if they don't already exist? I'd expect some stderr changes in this PR

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rustbot · 2026-08-22T16:26:25Z

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

evavh · 2026-08-28T12:38:01Z

I tried to add tests for the crate-level attribute checks, but I'm running into an interesting problem: there seems to be no way for the target check to fail. The possible ways for a crate-level attribute to be applied to a non-crate target (that I can think of) are:

A #[doc(CRATE_LEVEL_ONLY)] attribute applied to an item: this outputs the error crate-level attribute should be an inner attribute: add an exclamation mark
A #![doc(CRATE_LEVEL_ONLY)] attribute applied to an item (ie not at the top of the file): the error is an inner attribute is not permitted in this context

In both cases the compiler throws an error before we even reach the target checking code in doc.rs. The same applies to doc attribute arguments that shouldn't be used crate-level, like fake_variadic. It seems the distinction between inner (#!) and outer (#) attributes is enough to guard against wrong crate/non-crate targets.

The test I wrote covers all doc attribute arguments that check whether they are applied at crate level, and they all throw errors in earlier parsing steps. What do we do with the target checking code that does nothing?

JonathanBrouwer · 2026-08-30T15:44:46Z

@evavh I took a random crate-level doc attribute, and applied it to a function:

#[doc(html_no_source)]
fn test1() { }
fn test2() {
    #![doc(html_no_source)]
}

In both cases this produces "this attribute can only be applied at the crate level"
This diagnostic is produced in target checking, so if you hit it you are doing target checking somewhere:

rust/compiler/rustc_attr_parsing/src/target_checking.rs

Line 215 in ff619e2

    
           pub(crate) fn check_crate_level(cx: &mut AcceptContext<'_, 'sess>, warn: bool) {

The diagnostic "an inner attribute is not permitted in this context" is produced when you apply inner attributes to an item that doesn't support inner attributes, such as a struct, and is indeed produced in the parser

struct Test {
    #![doc(html_no_source)]
}

@rustbot author

rustbot · 2026-08-31T14:31:20Z

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 · 2026-08-31T23:05:16Z

These are breaking changes, so they will need a crater run. Alternatively, you could refactor this in a way that doesn't change behavior.

evavh · 2026-09-01T12:19:06Z

Turns out I was very confused by the "new" diagnostic emitted by check_crate_level called by AttributeParser::check_target. The target checking is still happening correctly with this refactor, though I do think the diagnostic has become worse.

I tried changing the diagnostic in check_crate_level, but that broke all kinds of unrelated tests.

As for breaking changes, using a crate-level doc attribute on the wrong target now emits an ERROR instead of a WARN.

@rustbot ready

JonathanBrouwer · 2026-09-01T12:41:04Z

-                }
+                cx.check_target(
+                    sym::no_crate_inject.as_str(),
+                    &AllowedTargets::AllowList(&[Allow(Target::Crate)]),


If you use AllowListWarnRest instead of AllowList it will warn instead of erroring.
Then to generate the right lint INVALID_DOC_ATTRIBUTES instead of the default UNUSED_ATTRIBUTES we should add a special case here

rust/compiler/rustc_attr_parsing/src/target_checking.rs

Line 173 in ff619e2

} else if is_diagnostic_attr {

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JonathanBrouwer · 2026-09-01T12:42:03Z

 //! This is not an official rust crate

-#[doc(rust_logo)]
-//~^ WARN this attribute can only be applied at the crate level


Is there a reason you removed this from the test?
This is here to show that this doc attribute, incorrectly, is not feature gated

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rust-log-analyzer · 2026-09-01T12:58:31Z

The job aarch64-gnu-llvm-21-2 failed! Check out the build log: (web) (plain enhanced) (plain)

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




This error was generated by the lint-docs tool.
This tool extracts documentation for lints from the source code and places
them in the rustc book. See the declare_lint! documentation
https://doc.rust-lang.org/nightly/nightly-rustc/rustc_lint_defs/macro.declare_lint.html
for an example of the format of documentation this tool expects.

To re-run these tests, run: ./x.py test --keep-stage=0 src/tools/lint-docs
The --keep-stage flag should be used if you have already built the compiler
and are only modifying the doc comments to avoid rebuilding the compiler.

Bootstrap failed while executing `--stage 2 test --skip tidy --skip intrinsic-test --skip src/tools/rust-analyzer --skip tests --skip library --skip tidyselftest`
Currently active steps:
test::LintDocs { build_compiler: Compiler { stage: 1, host: aarch64-unknown-linux-gnu, forced_compiler: false }, target: aarch64-unknown-linux-gnu } at src/bootstrap/src/core/build_steps/test.rs:4173
doc::RustcBook { build_compiler: Compiler { stage: 1, host: aarch64-unknown-linux-gnu, forced_compiler: false }, target: aarch64-unknown-linux-gnu, validate: true } at src/bootstrap/src/core/build_steps/test.rs:4186
Command `/checkout/obj/build/aarch64-unknown-linux-gnu/stage1-tools-bin/lint-docs --build-rustc-stage 1 --src /checkout/compiler --out /checkout/obj/build/aarch64-unknown-linux-gnu/md-doc/rustc/src/lints --rustc /checkout/obj/build/aarch64-unknown-linux-gnu/stage1/bin/rustc --rustc-target aarch64-unknown-linux-gnu --validate` failed with exit code 1
Created at: src/bootstrap/src/core/build_steps/tool.rs:1627:23
Executed at: src/bootstrap/src/core/build_steps/doc.rs:1465:13

Command has failed. Rerun with -v to see more details.
Build completed unsuccessfully in 0:39:24
  local time: Tue Sep  1 12:58:18 UTC 2026
  network time: Tue, 01 Sep 2026 12:58:18 GMT
##[error]Process completed with exit code 1.
##[group]Run echo "disk usage:"

rustbot added A-attributes Area: Attributes (`#[…]`, `#![…]`) S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Aug 22, 2026

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JonathanBrouwer added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Aug 30, 2026

rustbot 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-review Status: Awaiting review from the assignee but also interested parties. labels Aug 30, 2026

evavh added 3 commits August 31, 2026 16:29

Replace check_attr_crate_level with check_target

9d0b363

Fix string casting

6a28006

Add test for doc attr crate-level target checks

7a056e3

evavh force-pushed the doc-crate-level-check branch from 6c2968e to 7a056e3 Compare August 31, 2026 14:31

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mejrs added needs-fcp This change is insta-stable, or significant enough to need a team FCP to proceed. needs-crater This change needs a crater run to check for possible breakage in the ecosystem. labels Aug 31, 2026

evavh marked this pull request as draft September 1, 2026 11:56

Minimize doc-crate-level test for clarity

fc4c9ef

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Sep 1, 2026

JonathanBrouwer reviewed Sep 1, 2026

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	&sym::no_crate_inject.to_string(),
	sym::no_crate_inject.as_str()

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