Improve workings of attribute suggestions by nnethercote · Pull Request #159633 · rust-lang/rust

nnethercote · 2026-07-21T03:35:39Z

AttrItem span tracking improved in #159587, which lets us slightly simplify the workings of attribute suggestions.

r? @JonathanBrouwer

rustbot · 2026-07-21T03:35:43Z

Some changes occurred in compiler/rustc_attr_parsing

cc @jdonszelmann, @JonathanBrouwer

rustbot · 2026-07-21T03:35:45Z

JonathanBrouwer is currently at their maximum review capacity.
They may take a while to respond.

JonathanBrouwer · 2026-07-24T12:05:29Z

-                AttrSuggestionStyle::EmbeddedAttribute
-            }
-            ParsedDescription::Attribute => AttrSuggestionStyle::Attribute(self.attr_style),
+            ParsedDescription::Attribute => AttrSuggestionStyle::EmbeddedAttribute,


Hmmm this file has two functions

template_suggestions: https://github.com/nnethercote/rust/blob/ae3bbe78ec2a9bb57a03f10ad6ee0388e12bcefb/compiler/rustc_attr_parsing/src/context.rs#L946
suggestions:
https://github.com/nnethercote/rust/blob/ae3bbe78ec2a9bb57a03f10ad6ee0388e12bcefb/compiler/rustc_attr_parsing/src/context.rs#L1141

This PR changes template_suggestions, but not suggestions. These methods seem identical to me so the fact that there are two is probably a mistake?
suggestions is the last usage of AttrSuggestionStyle::Attribute, so would be nice to also change that

View changes since the review

It's not a mistake and as initially written the difference was necessary. But I have now added some additional commits that adjust some more error messages, such that the difference is no longer necessary, and I have merged the two methods and done some other related cleanups.

rustbot · 2026-07-24T12:05:37Z

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

Attribute templated mismatch suggestions come in two forms: - for a normal attribute, something like `#[inline(always)]`; - for an attribute embedded in `cfg_attr`, something like `inline(always)`. This commit replaces the former with the latter, and removes the need for the fragile span-based test for detecting embedded attributes in `template_suggestions`, and also `AttributeParseError::attr_span`. It takes advantage of the newly added (and accurate) `AttrItem::span` field. This change has a minor effect on error messages: when there are multiple suggestions their order can change because the `#[`/`]` are no longer included. This actually improves things, because e.g. if you write the invalid `#[inline(please)]`, the simpler `#[inline]` will be suggested ahead of the longer `#[inline(always)]` and `#[inline(never)`] alternatives.

The notable thing about this is the inconsistency. In the normal case we get this output: ``` warning: valid forms for the attribute are `#[macro_export(local_inner_macros)]` and `#[macro_export]` --> $DIR/invalid_macro_export_argument.rs:7:1 | LL | #[macro_export(hello, world)] | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ``` In the `cfg_attr` case we get this output: ``` warning: valid forms for the attribute are `macro_export` and `macro_export(local_inner_macros)` --> $DIR/invalid_macro_export_argument.rs:14:18 | LL | #[cfg_attr(true, macro_export(hello, world))] | ^^^^^^^^^^^^^^^^^^^^^^^^^^ ``` The difference being the presence/absence of the `#[`/`]` delimiters in both the "warning" line and the carets. This is exactly the kind of inconsistency that rust-lang#159755 started eliminating. The next commit will do so for this case.

rustbot · 2026-07-26T11:08:01Z

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.

rustbot · 2026-07-26T11:08:02Z

⚠️ Warning ⚠️

There are issue links (such as #123) in the commit messages of the following commits.
Please move them to the PR description, to avoid spamming the issues with references to the commit, and so this bot can automatically canonicalize them to avoid issues with subtree.
- d506f47

nnethercote · 2026-07-26T11:10:39Z

@rustbot ready

JonathanBrouwer

@bors r+ rollup
Thanks a lot!

View changes since this review

rust-bors · 2026-07-26T12:14:15Z

📌 Commit 656151a has been approved by JonathanBrouwer

It is now in the queue for this repository.

🌲 The tree is currently closed for pull requests below priority 100. This pull request will be tested once the tree is reopened.

Reason for tree closure: spurious failures

JonathanBrouwer · 2026-07-26T12:14:46Z

@bors r-
Actually CI seems sad, even tho there was no rust-log-analyzer message for it (yet?)
r=me after blessing tests
@rustbot author

rust-bors · 2026-07-26T12:14:51Z

This pull request was unapproved.

View changes since this unapproval

Similar to the commit before the last.

It's identical to `AttributeDiagnosticContext::suggestions`.

It's no longer used. Also remove the `start` and `end` local variables in `AttributeTemplate::suggestions`, because they're now always empty.

It's identical to `ParsedDescription`, modulo the `Attribute` vs `EmbeddedAttribute` naming, but thanks to the previous changes the `Embedded` prefix is no longer relevant.

nnethercote · 2026-07-26T12:28:58Z

I fixed the rustdoc-ui failure.

@bors r=JonathanBrouwer

rust-bors · 2026-07-26T12:29:00Z

📌 Commit 4981cac has been approved by JonathanBrouwer

It is now in the queue for this repository.

🌲 The tree is currently closed for pull requests below priority 100. This pull request will be tested once the tree is reopened.

Reason for tree closure: spurious failures

@JonathanBrouwer

…nathanBrouwer Improve workings of attribute suggestions `AttrItem` span tracking improved in rust-lang#159587, which lets us slightly simplify the workings of attribute suggestions. r? @JonathanBrouwer

…uwer Rollup of 28 pull requests Successful merges: - #159638 (bootstrap: Split the `Step` trait into multiple traits) - #159774 (rustc_trait_selection: fix trait solver hang caused by degenerate obligations) - #159837 (line-tables-only test: check that the line number matches the function name) - #159946 (Update Enzyme submodule to imporve llvm-cov) - #159962 (miri subtree update) - #156570 (tests: extend remap-path-prefix-std to all stdlib rlibs) - #159617 (Fix up `#[linkage]` target checking) - #159633 (Improve workings of attribute suggestions) - #159733 (std: Switch implementations of `thread_local!` for WASI) - #159783 (Check unsafe impls on safe EIIs) - #159810 (Add tuple never coercion collection regression test) - #159826 (Remove redundant `#[rustc_paren_sugar]` feature gate) - #159846 (Implement `str::copy_from_str`) - #159849 (rustc_parse: Stop returning `Option` from statement parsing) - #159853 (Updated expect messages for `CString` struct and method documentation) - #159875 (More cleanup in `rustc_attr_parsing`) - #159882 (Update expect messages in library/alloc/boxed.rs and library/alloc/string.rs to follow the style guide) - #159891 (Split multiline derives into std/rustc macros) - #159893 (Fix `find_attr` hygiene and `rustc_hir` cleanups) - #159895 (rustc-dev-guide subtree update) - #159902 (Clarify that the expected runtime symbols signature is for the current target only) - #159914 (Fix error in diagnostic on_unmatched_args) - #159917 (spare capacity mut constification) - #159918 (rename abort_unwind → abort_on_unwind) - #159927 (Remove sve2 from the ImpliedFeatures of AArch64 v9a.) - #159936 (Minor `rustc_ast::ast` doc cleanups) - #159945 (Update expect messages in library/core/src/ptr/non_null.rs) - #159950 (Add CFI tests for return types and never type)

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 Jul 21, 2026

rustbot assigned JonathanBrouwer Jul 21, 2026

nnethercote changed the title ~~Attr suggestions~~ Improve workings of attribute suggestions Jul 21, 2026

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nnethercote force-pushed the attr-suggestions branch from 0f09f33 to 6f28338 Compare July 21, 2026 06:06

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nnethercote force-pushed the attr-suggestions branch from 6f28338 to 3f77289 Compare July 21, 2026 07:55

JonathanBrouwer requested changes Jul 24, 2026

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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 Jul 24, 2026

nnethercote added 2 commits July 26, 2026 18:18

nnethercote force-pushed the attr-suggestions branch from 3f77289 to 656151a Compare July 26, 2026 11:07

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 Jul 26, 2026

JonathanBrouwer approved these changes Jul 26, 2026

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rust-bors Bot added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Jul 26, 2026

rust-bors Bot 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-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. labels Jul 26, 2026

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nnethercote added 4 commits July 26, 2026 22:25

Make attribute suggestions work at the level of attr items

00fb385

Similar to the commit before the last.

Remove AttributeDiagnosticContext::template_suggestions

0fe5073

It's identical to `AttributeDiagnosticContext::suggestions`.

Remove AttrSuggestionStyle::Attribute

42b6f4f

It's no longer used. Also remove the `start` and `end` local variables in `AttributeTemplate::suggestions`, because they're now always empty.

Remove AttrSuggestionStyle

4981cac

It's identical to `ParsedDescription`, modulo the `Attribute` vs `EmbeddedAttribute` naming, but thanks to the previous changes the `Embedded` prefix is no longer relevant.

nnethercote force-pushed the attr-suggestions branch from 656151a to 4981cac Compare July 26, 2026 12:28

rust-bors Bot added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Jul 26, 2026

JonathanBrouwer mentioned this pull request Jul 26, 2026

Rollup of 28 pull requests #159966

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