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.

Now that rust nightly has merged doc_auto_cfg into doc_cfg, and completed rust-lang/rust#138907, it is no longer necessary. Closes #1514.

# Which issue does this PR close? None. # Rationale for this change Removed in rust-lang/rust#138907, included in `doc_cfg` # What changes are included in this PR? Use `doc_cfg` instead of removed `doc_auto_cfg`. # Are these changes tested? Test locally with: `cargo +nightly docs-rs` # Are there any user-facing changes? No

As of <rust-lang/rust#138907>, the former feature has been removed and the latter feature has the same effect.

- [ ] Added a `CHANGELOG.md` entry # Summary Replace the removed `doc_auto_cfg` feature with the `doc_cfg` feature. # Motivation Avoid compilation errors when building documentation. # Details `doc_auto_cfg` was merged into `doc_cfg` in rust-lang/rust#138907. When `docsrs` is enabled, the old `doc_auto_cfg` results in the following errors on the latest nightlies: ``` error[E0557]: feature has been removed --> src/lib.rs:56:29 | 56 | #![cfg_attr(docsrs, feature(doc_auto_cfg))] | ^^^^^^^^^^^^ feature has been removed | = note: removed in CURRENT_RUSTC_VERSION; see <rust-lang/rust#138907> for more information = note: merged into `doc_cfg` ``` ``` error[E0557]: feature has been removed --> rand_core/src/lib.rs:36:29 | 36 | #![cfg_attr(docsrs, feature(doc_auto_cfg))] | ^^^^^^^^^^^^ feature has been removed | = note: removed in CURRENT_RUSTC_VERSION; see <rust-lang/rust#138907> for more information = note: merged into `doc_cfg` ``` The new `doc_cfg` retains the automatic `cfg` generation that `doc_auto_cfg` used to provide.

`doc_auto_cfg` has been merged into `doc_cfg` in rust-lang/rust#138907. Signed-off-by: Julian Schindel <[email protected]>

`doc_auto_cfg` has been merged into `doc_cfg` in rust-lang/rust#138907. Also bumps the Rust nightly version to actually capture the `doc_cfg` change. Fixes: [DEV-1000](https://linear.app/veecle/issue/DEV-1000) --------- Signed-off-by: Julian Schindel <[email protected]>

https://docs.rs/crate/oxc_resolver/11.8.4/builds/2542617 ``` [INFO] [stderr] error[E0557]: feature has been removed [INFO] [stderr] --> src/lib.rs:42:29 [INFO] [stderr] | [INFO] [stderr] 42 | #![cfg_attr(docsrs, feature(doc_auto_cfg))] [INFO] [stderr] | ^^^^^^^^^^^^ feature has been removed [INFO] [stderr] | [INFO] [stderr] = note: removed in 1.58.0; see <rust-lang/rust#138907> for more information [INFO] [stderr] = note: merged into `doc_cfg` [INFO] [stderr] [INFO] [stderr] error: Compilation failed, aborting rustdoc ```

Code changes are: - Use the `doc_cfg` feature instead of `doc_auto_cfg`: rust-lang/rust#138907 - Fix a few unused macro imports in the same file that defines the macro. UI test changes are: - Message for variadic args being unsupported has been updated. - Inference error location has changed slightly. Assembly test changes are: - None.

rust-lang/rust#138907

doc_auto_cfg has been merged into doc_cfg in rust-lang/rust#138907