Document diagnostic_namespace feature

[mejrs]

This adds it to the rust unstable book.

FWIW: I couldn't find a way to serve the book locally (please send help), so I can't check that this renders correctly.

cc @weiznich

[rustbot]

r? @ehuss

(rustbot has picked a reviewer for you, use r? to override)

[fmease]

Did you try mdbook serve while you were in the directory of the book?

[mejrs]

Did you try mdbook serve while you were in the directory of the book?

That was the first thing i tried, but it gave

2023-10-10 21:18:08 [ERROR] (mdbook::utils): Error: Couldn't open SUMMARY.md in "C:\\Users\\bruno\\Rust\\rust\\src\\doc\\unstable-book\\src" directory
2023-10-10 21:18:08 [ERROR] (mdbook::utils):    Caused By: The system cannot find the file specified. (os error 2)

[fmease]

Hmm, I guess boostrap generates the SUMMARY.md. I should probably leave this question to someone else to answer, however you could try to use ./x b <path/to/book> or a variation thereof.

[ehuss]

To build the documentation, you need to run ./x.py doc src/doc/unstable-book --open. We don't have support for automatically rebuilding the book.

There's a little bit of documentation on this at https://rustc-dev-guide.rust-lang.org/contributing.html#writing-documentation, but that isn't very discoverable. We should probably add something somewhere to point that out.

Thanks for adding this!

@bors r+ rollup

[bors]

📌 Commit 521cd0b has been approved by ehuss

It is now in the queue for this repository.

[ehuss]

Oops, forgot the example needs to compile.

@bors r-

I think the code block needs something like rust,compile_fail,E0277

You can test it with ./x.py test src/doc/unstable-book

[mejrs]

@rustbot ready

[ehuss]

Thanks!

@bors r+ rollup

[bors]

📌 Commit ba02a99 has been approved by ehuss

It is now in the queue for this repository.