Description
Problem
Recently standardized --check-cfg started triggering in my project. There is some common pattern in crates that want to use another nightly feature, doc_cfg, to do stuff like:
[package.metadata.docs.rs]
rustdoc-args = ["--cfg", "docs_rs"]#![cfg_attr(docs_rs, feature(doc_cfg))]
#[cfg(feature = "foo")]
#[cfg_attr(docs_rs, doc(cfg(feature = "foo")))]
pub mod p2p;The cfg attribute was used just to conditionally include the doc_cfg feature so that it is only present in docs.rs builds and not require nightly on a daily basis. When adding this I found no mention or whatever about any requirements for the name of the additional cfg flag used for this guard. It looked like docsrs is most widely used (eg. by tokio), however I opted in for docs_rs as I found it easier to read.
After standardizing of --check-cfg it turned out it's failing with the given message:
error: unexpected `cfg` condition name: `docs_rs`
--> types/src/lib.rs:16:12
|
16 | #[cfg_attr(docs_rs, doc(cfg(feature = "p2p")))]
| ^^^^^^^ help: there is a config with a similar name: `docsrs`
|
= help: consider using a Cargo feature instead or adding `println!("cargo::rustc-check-cfg=cfg(docs_rs)");` to the top of the `build.rs`
= note: see <https://doc.rust-lang.org/nightly/cargo/reference/build-scripts.html#rustc-check-cfg> for more information about checking conditional configuration
Indeed, after switching to docsrs everything is fine. I found that it's explicitely included here because that's what docs.rs uses internally, however I couldn't find it in any documentation, nor in the "well-known" names.
Steps
No response
Possible Solution(s)
No response
Notes
No response
Version
❯ cargo +nightly --version
cargo 1.80.0-nightly (05364cb2f 2024-05-03)