Always display first line of impl blocks even when collapsed

[GuillaumeGomez]

Fixes #130612.

It the line is too long, only the beginning will be visible:

Otherwise, it looks like this:

Can be tested here.

r? @notriddle

[rustbot]

Some changes occurred in HTML/CSS/JS.

cc @GuillaumeGomez, @jsha

[jieyouxu]

This looks cool 💚

[notriddle]

This should have a comment explaining what it does. Also, it should probably be a method on the Markdown struct? It's basically a different version of to_string.

/// Convert markdown to (summary, remaining) HTML.
///
/// - The summary is the first top-level Markdown element (usually a paragraph, but potentially any block).
/// - The remaining docs contain everything after the summary.

[GuillaumeGomez]

Good idea for the docs. I don't have an opinion on whether or not it should be a method so I'll just make a method since you seem to favor it. 👍

[GuillaumeGomez]

Applied suggestions.

[notriddle]

@rfcbot fcp cancel

@rfcbot fcp merge

[rfcbot]

@notriddle proposal cancelled.

[rfcbot]

Team member @notriddle has proposed to merge this. The next step is review by the rest of the tagged team members:

• @GuillaumeGomez
• @camelid
• @jsha
• @notriddle

Concerns:

• gradient-looks-weird resolved by Always display first line of impl blocks even when collapsed #132155 (comment)

Once a majority of reviewers approve (and at most 2 approvals are outstanding), this will enter its final comment period. If you spot a major issue that hasn't been raised at any point in this process, please speak up!

See this document for info about what commands tagged team members can give me.

[camelid]

I don't love the look of this. It looks a bit out of place compared to the generally clean style of rustdoc. In the case of tables and other things, it seems reasonable to just not show them rather than do a paywall-style blur of everything below the first row.

[notriddle]

@rfcbot concern gradient-looks-weird

I see what you mean there. To avoid this, I think you'd want to only have a summary if the first element is a paragraph or header, and then use white-space: nowrap; overflow: hidden; text-overflow: ellipsis;?

[camelid]

Exactly, that sounds good.

[GuillaumeGomez]

I liked the blur effect but text ellipsis is fine too. 😆

[GuillaumeGomez]

Problem with this approach is that the ellipsis only appears if the current sentence is cut:

expanded:

I'll try to check if we can still get the "..." in any case...

[GuillaumeGomez]

I can't figure a way to have an ellipsis which matches these conditions:

• Appears whatever the width of the first line.
• Appears only if there is hidden content.

With the blur I didn't have these issues, hence why I went for this solution. 😆

If you have an idea, I'd love to hear it!

[GuillaumeGomez]

A few things I thought about: the problem with short sentences is that they don't overflow, and therefore don't generate the ellipsis. However if there is more content, users won't until expanded. So instead I tried to cheat a bit and added a ::after element:

details.toggle:not([open]) > summary .docblock > :first-child {
	max-width: calc(100% - 1em);
	overflow: hidden;
	width: fit-content;
	white-space: nowrap;
	position: relative;
	text-overflow: clip;
	padding-right: 1em;
}
details.toggle:not([open]) > summary .docblock > :first-child::after {
	content: "…";
	position: absolute;
	right: 0;
	top: 0;
	background-color: var(--main-background-color);
}

However, it never gets displayed correctly on big text as it goes over it or is always stuck to the right side. I was hoping to kinda go around this issue by using padding and was able to. It gives this result:

If you are ok with this result, I can go with it.

[notriddle]

@rfcbot concern gradient-looks-weird

#132155 (comment)

[GuillaumeGomez]

I pushed the change with the text ellipsis. I find this solution less good but if majority prefers it, let's go with it. :)

[GuillaumeGomez]

Half+1 members approved the PR. Should we move forward with it?

[bors]

☔ The latest upstream changes (presumably #133006) made this pull request unmergeable. Please resolve the merge conflicts.

[GuillaumeGomez]

Fixed merge conflicts.

[notriddle]

@rfcbot resolve gradient-looks-weird

[rfcbot]

🔔 This is now entering its final comment period, as per the review above. 🔔

[bors]

☔ The latest upstream changes (presumably #133047) made this pull request unmergeable. Please resolve the merge conflicts.