Fix latest version parsing for crates with hyphens in their name

[rrbutani]

Crates with hyphens have their version extracted from the DOM (when viewing the latest version of a crate and adding it to the extension's index) incorrectly.

For example, adding the latest embedded-hal release to the extension's index results in this:

This in turn causes the extension to produce invalid docs.rs links.

---

This snippet (which itself addressed fallout from rustdoc changing its version output) is the problematic bit:

rust-search-extension/extension/script/add-search-index.js

Lines 12 to 15 in 599b1c9

	if (crateVersion === 'latest') {
	let versionText = document.querySelector('.nav-container a.crate-name>.title').textContent;
	crateVersion = versionText.split('-')[1];
	}

Updating this to take the last element after splitting on - instead of the second fixes this case but I think this leaves other edge cases unhandled.

For example, cargo and friends allow for pre-release versions which are allowed to have hyphens (i.e. 0.0.1-my-extremely-unstable-release). While it's unlikely that the docs.rs "latest" link for a crate will redirect to one of these, it is still possible – docsrs will search stable, unyanked releases first but will fall back to pre-releases.

The wasi crate is one such example of this (no "stable" releases as of this writing, pre-release version has a hyphen in it: 0.11.0+wasi-snapshot-preview1).

---

Reverting to the previous method (grabbing the version from the sidebar) and changing the query to 'nav.sidebar .version' is general enough to support pages generated before and after the rustdoc version change without being too general (and potentially picking up things in user-added HTML snippets) I think. This is the change I have implemented.

The downside to this approach is that it doesn't work on rustdoc output that predates the addition of the version in the sidebar; since docs.rs doesn't rebuild docs for older releases this can be a real concern for older stable crates that haven't had a release in a while.

---

Another approach is to snoop through some of the relative links on the page and to extract the version from the relative URLs there. There doesn't seem to be an obvious thing in the DOM to go after and we're definitely still susceptible to changes in rustdoc this way; I'm not sure if this is worth doing.

Yet another option is to pick an approach based on the rustdoc version in rustdoc-vars (i.e. document.querySelector("#rustdoc-vars").getAttribute("data-rustdoc-version")). This could help a little but it's worth noting that it itself is a relatively recent addition to the rustdoc HTML output, I think.

If either of the above or some other approach are preferable, please let me know; I'm happy to update this PR.

[Folyd]

Hi, @rrbutani. Thanks for the PR. ❤️

The main purpose why commit 4e84385 changed the CSS selector is because nav.sidebar .version only works in the root HTML page. For example, you can't get the crate version on this page: https://docs.rs/embedded-hal/latest/embedded_hal/trait.Capture.html. However, the user can click the Add to Rust Search Extension button on any page of that crate. The .nav-container a.crate-name>.title is a crate-wide selector, hence I picked it.

We have to say the librustdoc changes rapidly and frequently, it's hard to keep pace with it. The messy condition checks in add-search-index.js are the proof. According to my experience, we should follow those steadiness things as possible. The .nav-container is just a header of docs.rs, which I believe is changed infrequently than librustdoc. Therefore, I still prefer the current way.

Undoubtedly, the versionText.split('-')[1] is a stupid bug. 😅 Would you mind fixing this?

[rrbutani]

The main purpose why commit 4e84385 changed the CSS selector is because nav.sidebar .version only works in the root HTML page.

Oh, I see; thanks for the context!

The .nav-container is just a header of docs.rs, which I believe is changed infrequently than librustdoc. Therefore, I still prefer the current way.

I agree; I think this also has the added benefit of being the same across all documentation output, regardless of it's generation date.

Undoubtedly, the versionText.split('-')[1] is a stupid bug. 😅 Would you mind fixing this?

I think a regex that picks out -[0-9]+.[0-9]+.[0-9]+.* would do the trick (crate names can end with numbers but can't have dots) and handle all the cases identified but I'd still rather avoid this if possible.

---

@Folyd How about going after the crate title (space separated crate name and version) in the menu?

document.querySelector(".nav-container #crate-title").textContent.trim().split(" ")[1] gets this, I think; is that acceptable?

[rrbutani]

@Folyd I've updated the PR to match ^

[Folyd]

I think there is another file that needs fixing:

rust-search-extension/extension/script/docs-rs.js

Lines 91 to 94 in 599b1c9

	if (crateVersion === 'latest') {
	let versionText = document.querySelector('.nav-container a.crate-name>.title').textContent;
	crateVersion = versionText.split('-')[1];
	}