Re: [PATCH 0/1] fix rustdoc build detection

[Mauro Carvalho Chehab <mchehab+huawei@kernel.org>]

Em Mon, 24 Nov 2025 02:51:40 +0100
Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> escreveu:

> On Fri, Nov 21, 2025 at 10:41 AM Mauro Carvalho Chehab
> <mchehab+huawei@kernel.org> wrote:
> >
> > I'm not talking about stop using rustdoc. I'm talking about using
> > it to output on a format that Sphinx can understand, and let Sphinx
> > do the final output, solving cross-references.  
> 
> By stop using `rustdoc` I meant its "normal" (HTML) output, i.e. the
> webpage with all its features and so on.

I see.

> The JSON support is unstable so far:
> 
>     https://github.com/rust-lang/rust/issues/76578

From the issue timestamps, it seems that it doesn't have a high
priority.

> And even then, I imagine it will always still require a kernel config,
> so that isn't an advantage either.

This doesn't seem to be an issue itself, as a new kernel config is easy 
to add.

> Thus trying to mimic what `rustdoc` does is probably going to be a lot
> of work to maintain, to likely get a worse result than what `rustdoc`
> already does.

Perhaps one solution would be to write a new output plugin to make
rustdoc produce a better output format that could be easily mapped
by a Sphinx plugin (like producing an output on an enriched text
format like Markdown or ReST).

I can't evaluate how easy/hard would be to do that, as I'm not
familiar with Rust toolset.

> Something that would work without a config could be way more
> interesting for us to integrate into Sphinx.

At Sphinx side, it won't be hard to pick references from rustdoc.

At kernel_include extension:

	https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/sphinx/kernel_include.py

I added a logic there to detect unsolved cross-references.

Currently, it just warns about unsolved references, but it won't 
be hard to modify a similar logic to solve it, pointing to a
rustdoc reference (if those are stable enough).

Doing the reverse can be trickier, though: internally, Sphinx
maps them via a C domain. The output plugin (html, pdf, ...)
is what converts such reference into an html (or pdf) tag.
Such mapping is version dependent.

There was a major rewrite at eh C domain on Sphinx 3.0 which
changed such mapping, but other versions may have changed it as well.

Also, there is an open issue that will likely change it once
fixed:

	https://github.com/sphinx-doc/sphinx/issues/7819
	https://github.com/sphinx-doc/sphinx/issues/8241

(last one closed as duplicate of #7819)

So, creating cross-references from rustdoc to Sphinx could
be tricky and hard to maintain, as it may require some checks
at rust/rustdoc side to verify Sphinx version.

Thanks,
Mauro