Recover inner attributes in algebraic data types by JonathanBrouwer · Pull Request #162018 · rust-lang/rust

JonathanBrouwer · 2026-08-30T16:43:37Z

Previously, if you'd put an inner attribute in an empty ADT, such as a struct:

struct Test1 {
    #![inline]
}

You'd get the following errors

error: an inner attribute is not permitted in this context
 --> src/lib.rs:5:5
  |
5 |     #![cfg(false)]
  |     ^^^^^^^^^^^^^^
  |
  = note: inner attributes, like `#![no_std]`, annotate the item enclosing them, and are usually found at the beginning of source files
  = note: outer attributes, like `#[test]`, annotate the item following them

error: expected identifier, found `}`
 --> src/lib.rs:6:1
  |
4 | struct Test3 {
  |        ----- while parsing this struct
5 |     #![cfg(false)]
6 | }
  | ^ expected identifier

error: could not compile `rust-test` (lib) due to 2 previous errors

The second error is spurious. It was caused by us only recovering inner attributes just before parsing a field, meaning if we see an inner attribute and recover we expect a field next. This PR fixes that by recovering inner attributes just after the curly brace as well.

rustbot · 2026-08-30T16:43:40Z

The parser was modified, potentially altering the grammar of (stable) Rust
which would be a breaking change.

cc @fmease

rustbot · 2026-08-30T16:43:43Z

r? @wesleywiser

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JonathanBrouwer · 2026-09-08T08:53:53Z

@rustbot reroll

JonathanBrouwer · 2026-09-30T14:04:35Z

@rustbot reroll

JonathanBrouwer · 2026-10-28T11:14:21Z

@rustbot reroll

fmease · 2026-10-29T09:03:55Z

In the case of enums you're recovering from inner attributes before each variant and in the case of "records" you're recovering from inner attributes once before all fields. I would pick the same approach for both.

View changes since the review

I'm now checking before every variant and every field, and expanded the test to show this

fmease · 2026-10-29T09:07:34Z

    }

    fn parse_enum_variant(&mut self, span: Span) -> PResult<'a, Option<Variant>> {
+        if self.recover_inner_attributes()? && self.check(exp![CloseBrace]) {


Checking for CloseBrace here in parse_enum_variant is a bit ~~"assumptious"~~ abstraction breaking since strictly speaking } it doesn't belong to syntax fragment / production rule EnumVariant. Ideally that check would happen outside of this function. Of course, sometimes blurring is unavoidable.

View changes since the review

I lifted the recover_inner_attributes call out of the method to fix this

JonathanBrouwer · 2026-10-30T13:01:00Z

@rustbot ready

rustbot · 2026-10-30T13:02:02Z

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.

fmease

Thanks!

@bors rollup
@bors r+ squash

View changes since this review

* Add regression test * Recover inner attributes in algebraic data types * Try to recover after every field and variant

rust-bors · 2026-11-01T21:47:33Z

🔨 3 commits were squashed into 5dd864e.

rust-bors · 2026-11-01T21:47:35Z

📌 Commit 5dd864e has been tentatively approved by fmease

It will be put into the queue for this repository once PR CI succeeds.

… r=fmease Recover inner attributes in algebraic data types Previously, if you'd put an inner attribute in an empty ADT, such as a struct: ```rust struct Test1 { #![inline] } ``` You'd get the following errors ``` error: an inner attribute is not permitted in this context --> src/lib.rs:5:5 | 5 | #![cfg(false)] | ^^^^^^^^^^^^^^ | = note: inner attributes, like `#![no_std]`, annotate the item enclosing them, and are usually found at the beginning of source files = note: outer attributes, like `#[test]`, annotate the item following them error: expected identifier, found `}` --> src/lib.rs:6:1 | 4 | struct Test3 { | ----- while parsing this struct 5 | #![cfg(false)] 6 | } | ^ expected identifier error: could not compile `rust-test` (lib) due to 2 previous errors ``` The second error is spurious. It was caused by us only recovering inner attributes just before parsing a field, meaning if we see an inner attribute and recover we expect a field next. This PR fixes that by recovering inner attributes just after the curly brace as well.

Rollup of 9 pull requests Successful merges: - #162018 (Recover inner attributes in algebraic data types) - #162819 (Make the suggestion message of `unused_must_use` scarier.) - #163053 (Use verbose suggestion for type literal with wrong syntax) - #163245 (Fix multiple pattern comma suggestions in diagnostics) - #163369 (Don't lint unused_qualifications when the unqualified path is ambiguous) - #165282 (Improve span for unused_mut lint) - #165285 (Forward `AbiAlign` `Debug` impl to `Align`) - #165294 (unstable.rs: add missing `]` in description of `cfg_ub_checks`) - #165310 (Clarify AGENTS.md around pushing to a fork)

Rollup merge of #162018 - JonathanBrouwer:attr_empty_struct, r=fmease Recover inner attributes in algebraic data types Previously, if you'd put an inner attribute in an empty ADT, such as a struct: ```rust struct Test1 { #![inline] } ``` You'd get the following errors ``` error: an inner attribute is not permitted in this context --> src/lib.rs:5:5 | 5 | #![cfg(false)] | ^^^^^^^^^^^^^^ | = note: inner attributes, like `#![no_std]`, annotate the item enclosing them, and are usually found at the beginning of source files = note: outer attributes, like `#[test]`, annotate the item following them error: expected identifier, found `}` --> src/lib.rs:6:1 | 4 | struct Test3 { | ----- while parsing this struct 5 | #![cfg(false)] 6 | } | ^ expected identifier error: could not compile `rust-test` (lib) due to 2 previous errors ``` The second error is spurious. It was caused by us only recovering inner attributes just before parsing a field, meaning if we see an inner attribute and recover we expect a field next. This PR fixes that by recovering inner attributes just after the curly brace as well.

rustbot added 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 30, 2026

rustbot assigned wesleywiser Aug 30, 2026

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JonathanBrouwer force-pushed the attr_empty_struct branch from 1dae34b to 6990400 Compare September 8, 2026 08:52

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rustbot assigned dingxiangfei2009 and unassigned wesleywiser Sep 8, 2026

rustbot assigned JohnTitor and unassigned dingxiangfei2009 Sep 30, 2026

rustbot assigned adwinwhite and unassigned JohnTitor Oct 28, 2026

fmease reviewed Oct 29, 2026

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fmease assigned fmease and unassigned adwinwhite Oct 29, 2026

fmease 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 Oct 29, 2026

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JonathanBrouwer force-pushed the attr_empty_struct branch from 6990400 to 95c251f Compare October 30, 2026 13:01

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Recover inner attributes in algebraic data types

5dd864e

* Add regression test * Recover inner attributes in algebraic data types * Try to recover after every field and variant

rust-bors Bot force-pushed the attr_empty_struct branch from 95c251f to 5dd864e Compare November 1, 2026 21:47

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 Nov 1, 2026

This was referenced Nov 2, 2026

Rollup of 10 pull requests #165312

Closed

Rollup of 9 pull requests #165313

Merged

rust-bors Bot merged commit 27a11b4 into rust-lang:main Nov 2, 2026
14 checks passed

rustbot added this to the 1.101.0 milestone Nov 2, 2026

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