Implement RFC 3631: add rustdoc doc_cfg features #138907

GuillaumeGomez · 2025-03-24T22:50:33Z

This implementation actually resulted in a lot of simplifications:

All cfg computation is now done in one place: propagate_doc_cfg.rs. Because (trait) impls are not retrieved at the same time as the other items, we cannot perform this computation in the clean process, it needs to be after.
Because there is cfg inheritance, we can keep track of them in one place (in propagate_doc_cfg.rs), meaning we don't need to copy an item's attributes to its children anymore. Only exception: impl items. For them we clone only cfg attributes.
propagate_doc_cfg.rs is also now much simpler, much less need to keep track of parents, since everything we need is handled by the new CfgInfo type.
I also suspect that Cfg::simplify_with could either be removed or at least used directly into propagate_doc_cfg.rs when we compute cfgs. Considering how big the PR already is, I'll do it in a follow-up.

I didn't remove the doc_cfg* features in this PR because some dependencies used in rustc (like stdarch) are using it, so we need to have a nightly released with this PR before I can switch to the new feature.

r? ghost

petrochenkov · 2025-03-25T09:48:06Z

What remains to be done:

I'd also want to block the stabilization on landing #138844 to avoid a stable rustdoc feature relying on externally observable hacks in rustc.
The crater run in #138844 returned mostly clean, so I expect it to land soon.

GuillaumeGomez · 2025-03-25T10:36:45Z

Noted! And that will be a nice improvement, thanks!

Just one thing left for the cfg expansion missing: #[cfg_attr(blabla, derive(Debug))]. In this case, the cfg is not kept in the generated derive items. It's been in my TODO list for a long time now. ^^'

petrochenkov · 2025-03-25T10:49:31Z

Just one thing left for the cfg expansion missing: #[cfg_attr(blabla, derive(Debug))]

Do you mean like in #138515? :)

GuillaumeGomez · 2025-03-25T10:52:03Z

You're my hero! Gonna need to handle this new attribute then. :)

bors · 2025-03-25T17:53:10Z

☔ The latest upstream changes (presumably #138923) made this pull request unmergeable. Please resolve the merge conflicts.

bors · 2025-03-27T19:41:02Z

☔ The latest upstream changes (presumably #138927) made this pull request unmergeable. Please resolve the merge conflicts.

Move doc_cfg-specific code into `cfg.rs` Follow-up of rust-lang/rust#138907. r? lolbinarycat

* give name to closure variable types to prevent future confusion * Update CHANGELOG.md * Seperate rust package from buildInputs into stableRust * Add docrs devshell with nightly Rust * nix flake update * Update devshell stableRust to 1.90.0 * Update bevy_time_runner to 0.5.2 * Change doc_auto_cfg to doc_cfg since rust-lang/rust#138907 * Update unreleased changes section in CHANGELOG.md * fix import in docs * update EguiPlugin in bevy_lookup_curve --------- Co-authored-by: Multirious <[email protected]>

See also rust-lang/rust#138907 Signed-off-by: tison <[email protected]>

See rust-lang/rust#138907, also see [#linebender > Cargo doc failures in linebender repos](https://xi.zulipchat.com/#narrow/channel/419691-linebender/topic/Cargo.20doc.20failures.20in.20linebender.20repos/with/542106544).

the `doc_auto_cfg` feature has been merged into `doc_cfg` [1], and this is breaking building vm-memory documentation on docs.rs [2]. [1]: rust-lang/rust#138907 [2]: https://docs.rs/crate/vm-memory/0.17.0/builds/2564760 Signed-off-by: Patrick Roy <[email protected]>

#4331) ## Motivation and Context   Our docrs builds started [failing](https://docs.rs/crate/aws-sdk-dynamodb/1.94.0/builds/2555063) recently with the error: ``` [INFO] [stderr] Documenting aws-sdk-dynamodb v1.94.0 (/opt/rustwide/workdir) [INFO] [stderr] error[E0557]: feature has been removed [INFO] [stderr] --> src/lib.rs:21:29 [INFO] [stderr] | [INFO] [stderr] 21 | #![cfg_attr(docsrs, feature(doc_auto_cfg))] [INFO] [stderr] | ^^^^^^^^^^^^ feature has been removed [INFO] [stderr] | [INFO] [stderr] = note: removed in CURRENT_RUSTC_VERSION; see <rust-lang/rust#138907> for more information [INFO] [stderr] = note: merged into `doc_cfg` [INFO] [stderr] [INFO] [stderr] error: Compilation failed, aborting rustdoc [INFO] [stderr] [INFO] [stderr] For more information about this error, try `rustc --explain E0557`. [INFO] [stderr] error: could not document `aws-sdk-dynamodb` ``` The [linked issue](rust-lang/rust#138907) shows that `doc_auto_cfg` has recently been merged into `doc_cfg`. docsrs builds with the latest nightly toolchain, so the change has impacted our doc builds. This PR makes that change in codegen and in all of our runtime crates. ## Checklist  - [ ] For changes to the smithy-rs codegen or runtime crates, I have created a changelog entry Markdown file in the `.changelog` directory, specifying "client," "server," or both in the `applies_to` key. - [ ] For changes to the AWS SDK, generated SDK code, or SDK runtime crates, I have created a changelog entry Markdown file in the `.changelog` directory, specifying "aws-sdk-rust" in the `applies_to` key. ---- _By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice._

Fixes Azure#3117 and fixes Azure#3118 by renaming `doc_auto_cfg` and `doc_cfg_hide` to just `doc_cfg` after rust-lang/rust#138907 was merged and released in the new nightly toolchain docs.rs uses.

[`doc_auto_cfg` was merged into `doc_cfg` and is no longer itself usable.]( rust-lang/rust#138907 ) Allows us to update our version of nightly, which this PR also does.

Fixes #3117 and fixes #3118 by renaming `doc_auto_cfg` and `doc_cfg_hide` to just `doc_cfg` after rust-lang/rust#138907 was merged and released in the new nightly toolchain docs.rs uses.

It looks like the issue with building the latest docs originated from rust-lang/rust#138907 getting into effect at docs.rs.

`doc_auto_cfg` has been removed in the latest nightly, see rust-lang/rust#138907. This feature was merged into `doc_cfg`. This fixes the rustdoc build in the latest nightly toolchain with docsrs feature enabled.

doc_auto_cfg was merged into doc_cfg in rust-lang/rust#138907

Since rust-lang/rust#138907 was merged.

`doc_auto_cfg` has been removed in the latest nightly, see rust-lang/rust#138907. This feature was merged into `doc_cfg`. This fixes the rustdoc build in the latest nightly toolchain with docsrs feature enabled.

It looks like the issue with building the latest docs originated from rust-lang/rust#138907 getting into effect at docs.rs.