Local `rustc-docs` could make use of local pages for `std` types

[rami3l]

Posting this for @blyxyas and big thanks for having spotted this issue real quick :)

Location (URL)

The same problem persists in many different pages, just to pick an example on my machine:

$RUSTUP_HOME/toolchains/nightly-aarch64-apple-darwin/share/doc/rust/html/rustc-docs/rustc_trait_selection/errors/struct.AmbiguousImpl.html

Summary

The external link for Option<> is https://doc.rust-lang.org/nightly/core/option/enum.Option.html, which is probably desirable for online usage, but considering the fact that this download is intended for offline usage, it'd be better if it can point to the std docs just next to it, i.e. $RUSTUP_HOME/toolchains/nightly-aarch64-apple-darwin/share/doc/rust/html/std/option/enum.Option.html?

A few things to be noted for this issue:

1. This issue should be resolved in a way that it doesn't break the online docs.

2. This does imply an implicit dependency between rustc-docs and rust-docs which rustup is not quite ready to handle, but since rustc-docs is mostly for in-house usage, I believe we can focus on redirecting the links for the time being.

cc @GuillaumeGomez @jieyouxu

[arferreira]

@jieyouxu / @rami3l would this be a good fit for someone still getting familiar with the codebase? If so, any pointers on where to start looking would be really helpful. This issue caught my eye since it's also in the rustdoc space.

[rami3l]

@arferreira Thanks for asking!

Frankly speaking, I have no idea, since it's a large repo and I'm also new to this part of the codebase. Sorry about that :(

However, nothing stops you from trying something out if you see opportunities out there, I started contributing with a PR that never got merged as well :)

[arferreira]

@arferreira Thanks for asking!

Frankly speaking, I have no idea, since it's a large repo and I'm also new to this part of the codebase. Sorry about that :(

However, nothing stops you from trying something out if you see opportunities out there, I started contributing with a PR that never got merged as well :)

Def!
I'm gonna take a look in depth on this!

[lolbinarycat]

--extern-html-root-url might be of some use here.

[arferreira]

@rustbot claim