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rust-lang / docs.rs

crates.io documentation generator
https://docs.rs
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`rustdoc-args` is ignored for proc_macro crates #2374

Open dylni opened 10 months ago

dylni commented 10 months ago

Crate name

attr_alias

Build failure link

https://docs.rs/crate/attr_alias/0.1.0/builds/1075851

Additional details

The build did not fail, but this still appeared to be the best template, as the build did not work as expected.

For proc_macro crates, docs.rs avoids passing --target for builds: https://github.com/rust-lang/docs.rs/blob/b0f6feadba64502c8aa68dedc3e20be096c5af23/src/docbuilder/rustwide_builder.rs#L830-L833

From what I can tell, for library crates, this fixes an issue of rustdoc-args being ignored when passed as build.rustdocflags to rustdoc. However, regardless of whether --target is passed, rustdoc-args is ignored for proc_macro crates.

For example, Cargo.toml for attr_alias includes:

[package.metadata.docs.rs]
rustdoc-args = ["--cfg", "attr_alias_docs_rs"]

attr_alias::attr_alias also has the attribute:

#[cfg_attr(attr_alias_docs_rs, doc(cfg(feature = "nightly")))]

Therefore, attr_alias::attr_alias should be documented to require the "nightly" feature, but the note is missing, since rustdoc-args was ignored: https://docs.rs/attr_alias/0.1.0/attr_alias/attr.attr_alias.html

Nemo157 commented 10 months ago

You can see we pass it along to cargo: https://docs.rs/crate/attr_alias/0.1.0/builds/1075851, it must be ignoring it for some reason though, probably related to the weirdness of a --target-less build; I can investigate more tomorrow.

dylni commented 10 months ago

@Nemo157 Agreed, my description could have been clearer. I updated it to make that point more obvious.

Nemo157 commented 10 months ago

This is much bigger than just the package.metadata.docs.rs.rustdoc-args being ignored, all the additional args we use like --static-root-path are ignored too :facepalm:. This must be a pretty recent cargo bug, serde_derive built 2023-11-21 isn't affected.

Nemo157 commented 10 months ago

Ah no, it's because attr_alias sets rustc-args which makes us use -Zhost-config -Ztarget-applies-to-host, which then makes build.rustdocflags not apply. This actually needs a soon-to-be-fully-implemented feature of per-target rustdocflags to properly fix https://github.com/rust-lang/cargo/pull/13197