Attribute documentation for cfg_attr by kantnero · Pull Request #159798 · rust-lang/rust

kantnero · 2026-07-23T22:12:35Z

Documents the cfg_attr
Part of #157604

r? @GuillaumeGomez
cc @fmease @traviscross

fmease · 2026-07-25T14:26:45Z

Meta note:

Instead of trying to add docs for more and more attributes at once in one PR, I think it would be more helpful & generally better to split your efforts into several smaller PRs going forward which each contain a small set of related attributes / just one attribute instead of a large mixed bag.

That would make it a lot easier for reviewers since they wouldn't have to wade through 100 comments like in #158664 and context-switch constantly within the same PR. Consequently, it would mean your PRs can get merged a lot faster.

Re. you closing #158664 I guess that was due to git / GitHub issues? In case it wasn't though, I want to say that it makes it harder to follow the progress & discussions for specific attributes since they're now spread across several PRs (one has 100 comments as I've already mentioned), esp. since there's no link from the old to the new PR.

In any case, thanks for working on this!

kantnero · 2026-07-30T23:45:48Z

@fmease @GuillaumeGomez Change this to document just one attr cfg_attr will send subsequent pr after this is merged.

kantnero · 2026-08-03T19:29:12Z

@rustbot ready

kantnero · 2026-08-06T19:57:11Z

Hi @GuillaumeGomez @traviscross

Just checking in, this is PR ready for review. Happy to address feedbacks. Thanks

kantnero · 2026-09-30T10:48:15Z

r? @mejrs

mejrs

The cfg attribute docs have a link to cfg_attr that currently links to the reference, can you make that link point to this documentation instead?

View changes since this review

mejrs · 2026-09-30T11:12:42Z

+/// // This function is annotated with `#[test]` only on Linux platforms.
+/// #[cfg_attr(target_os = "linux", test)]
+/// fn my_function() {
+///     // ...
+/// }


I feel this example isn't very idiomatic, typically you do #[cfg(..)] #[test] fn my_function(){}.

#[cfg_attr(feature = "debug_impls", derive(Debug))] struct X;

is very common, maybe use that instead?

mejrs · 2026-09-30T11:16:51Z

+/// ```rust
+/// #[cfg_attr(
+///     all(feature = "system", feature = "disk"),
+///     doc = "For module documentation, both `system`, and `disk` need to be enabled.",


Suggested change

/// doc = "For module documentation, both `system`, and `disk` need to be enabled.",

/// doc = "These docs only show up if both `system`, and `disk` are enabled.",

rustbot · 2026-09-30T11:18:32Z

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

Signed-off-by: Emmanuel Ugwu <emmanuelugwu121@gmail.com>

mejrs

@bors r+ rollup

View changes since this review

rust-bors · 2026-09-30T15:12:18Z

📌 Commit 57be633 has been approved by mejrs

It is now in the queue for this repository.

@GuillaumeGomez

…r=mejrs Attribute documentation for cfg_attr Documents the cfg_attr Part of rust-lang#157604 r? @GuillaumeGomez cc @fmease @traviscross

…uwer Rollup of 18 pull requests Successful merges: - #163532 (rustc_codegen_cranelift subtree update) - #163534 (miri subtree update) - #163279 (const and NonZero impl for clamp_magnitude()) - #162900 (Some refactorings around metadata encoding) - #163455 (Don't use the metadata based crate_hash for rustdoc runs) - #163483 (Bump bootstrap compiler to 1.100.0 beta) - #159798 (Attribute documentation for cfg_attr) - #163368 (Don't build format string suggestions from `concat!` offsets) - #163375 (Update expect messages in library/std/src/os/unix/net/ following Rust's `expect` guidance) - #163405 (Remove some #[linkage] options) - #163470 (Miscellaneous attr error stuff) - #163489 (expose Rc::is_unique) - #163492 (x86 and x86_64: cleanup some callconv code) - #163496 (cycle handling: mirror old solver) - #163509 (Use more default field values in `Resolver`) - #163519 (Forbid `Reborrow` impls for types with destructors) - #163520 (Cast cleanups) - #163524 (Document `Result` case for the `arena_cache` query modifier) Failed merges: - #163547 ([beta] rustfmt backport)

@GuillaumeGomez

…r=mejrs Attribute documentation for cfg_attr Documents the cfg_attr Part of rust-lang#157604 r? @GuillaumeGomez cc @fmease @traviscross

…uwer Rollup of 18 pull requests Successful merges: - #163532 (rustc_codegen_cranelift subtree update) - #163534 (miri subtree update) - #163279 (const and NonZero impl for clamp_magnitude()) - #162900 (Some refactorings around metadata encoding) - #163455 (Don't use the metadata based crate_hash for rustdoc runs) - #159798 (Attribute documentation for cfg_attr) - #162921 (make mips64 `Complex` GCC-compatible) - #163368 (Don't build format string suggestions from `concat!` offsets) - #163375 (Update expect messages in library/std/src/os/unix/net/ following Rust's `expect` guidance) - #163405 (Remove some #[linkage] options) - #163470 (Miscellaneous attr error stuff) - #163489 (expose Rc::is_unique) - #163492 (x86 and x86_64: cleanup some callconv code) - #163496 (cycle handling: mirror old solver) - #163509 (Use more default field values in `Resolver`) - #163519 (Forbid `Reborrow` impls for types with destructors) - #163520 (Cast cleanups) - #163524 (Document `Result` case for the `arena_cache` query modifier)

Rollup of 20 pull requests Successful merges: - #163279 (const and NonZero impl for clamp_magnitude()) - #163081 (Provide more context on "not general enough" error) - #163455 (Don't use the metadata based crate_hash for rustdoc runs) - #159798 (Attribute documentation for cfg_attr) - #162921 (make mips64 `Complex` GCC-compatible) - #163368 (Don't build format string suggestions from `concat!` offsets) - #163375 (Update expect messages in library/std/src/os/unix/net/ following Rust's `expect` guidance) - #163470 (Miscellaneous attr error stuff) - #163489 (expose Rc::is_unique) - #163492 (x86 and x86_64: cleanup some callconv code) - #163496 (cycle handling: mirror old solver) - #163509 (Use more default field values in `Resolver`) - #163519 (Forbid `Reborrow` impls for types with destructors) - #163520 (Cast cleanups) - #163524 (Document `Result` case for the `arena_cache` query modifier) - #163546 (PassWrapper: adapt for new PassPlugin load method) - #163551 (Add libs-nominated triagebot config) - #163559 (Suggest `#[unsafe(no_mangle)]` for entry points in `no_std` binaries) - #163564 (rustc-dev-guide subtree update) - #163568 (remove dead cfg_select! arm)

@GuillaumeGomez

Rollup merge of #159798 - kantnero:attribute-documentation, r=mejrs Attribute documentation for cfg_attr Documents the cfg_attr Part of #157604 r? @GuillaumeGomez cc @fmease @traviscross

Rollup of 20 pull requests Successful merges: - rust-lang/rust#163279 (const and NonZero impl for clamp_magnitude()) - rust-lang/rust#163081 (Provide more context on "not general enough" error) - rust-lang/rust#163455 (Don't use the metadata based crate_hash for rustdoc runs) - rust-lang/rust#159798 (Attribute documentation for cfg_attr) - rust-lang/rust#162921 (make mips64 `Complex` GCC-compatible) - rust-lang/rust#163368 (Don't build format string suggestions from `concat!` offsets) - rust-lang/rust#163375 (Update expect messages in library/std/src/os/unix/net/ following Rust's `expect` guidance) - rust-lang/rust#163470 (Miscellaneous attr error stuff) - rust-lang/rust#163489 (expose Rc::is_unique) - rust-lang/rust#163492 (x86 and x86_64: cleanup some callconv code) - rust-lang/rust#163496 (cycle handling: mirror old solver) - rust-lang/rust#163509 (Use more default field values in `Resolver`) - rust-lang/rust#163519 (Forbid `Reborrow` impls for types with destructors) - rust-lang/rust#163520 (Cast cleanups) - rust-lang/rust#163524 (Document `Result` case for the `arena_cache` query modifier) - rust-lang/rust#163546 (PassWrapper: adapt for new PassPlugin load method) - rust-lang/rust#163551 (Add libs-nominated triagebot config) - rust-lang/rust#163559 (Suggest `#[unsafe(no_mangle)]` for entry points in `no_std` binaries) - rust-lang/rust#163564 (rustc-dev-guide subtree update) - rust-lang/rust#163568 (remove dead cfg_select! arm)

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-libs Relevant to the library team, which will review and decide on the PR/issue. labels Jul 23, 2026

rustbot assigned GuillaumeGomez Jul 23, 2026