rustdoc: allow resizing the sidebar / hiding the top bar
Fixes#97306
Preview: http://notriddle.com/rustdoc-html-demo-4/sidebar-resize/std/index.html
## Summary
This feature adds:
1. A checkbox to the Settings popover to hide the persistent navigation bar (the sidebar on large viewports and the top bar on small ones).
2. On large viewports, it adds a resize handle to the persistent sidebar. Resizing it into nothing is equivalent to turning off the persistent navigation bar checkbox in Settings.
3. If the navigation bar is hidden, a toolbar button to the left of the search appears. Clicking it brings the navigation bar back.
## Motivation
While "mobile mode" is definitely a good default, it's not the only reason people have wanted to hide the sidebar:
* Some people use tiling window managers, and don't like rustdoc's current breakpoints. Changing the breakpoints might help with that, but there's no perfect solution, because there's a gap between "huge screen" and "smartphone" where reasonable people can disagree about whether it makes sense for the sidebar to be on-screen. https://github.com/rust-lang/rust/issues/97306
* Some people ask for ways to reduce on-screen clutter because it makes it easier to focus. There's not a media query for that (and if there was, privacy-conscious users would turn it off). https://github.com/rust-lang/rust/issues/59829
This feature is designed to avoid these problems. Resizing the sidebar especially helps, because it provides a way to hide the sidebar without adding a new top-level button (which would add clutter), and it provides a way to make rustdoc play nicer in complex, custom screen layouts.
## Guide and Reference-level explanation
On a desktop or laptop with a mouse, resize the sidebar by dragging its right edge.
On any browser, including mobile phones, the sticky top bar or side bar can be hidden from the Settings area (the button with the cog wheel, next to the search bar). When it's hidden, a convenient button will appear on the search bar's left.
## Drawbacks
This adds more JavaScript code to the render blocking area.
## Rationale and alternatives
The most obvious way to allow people to hide the sidebar would have been to let them "manually enter mobile mode." The upside is that it's a feature we already have. The downside is that it's actually really hard to come up with a terse description. Is it:
* A Setting that forces desktop viewers to always have the mobile-style top bar? If so, how do we label it? Should it be visible on mobile, and, if so, does it just not do anything?
* A persistent hide/show sidebar button, present on desktop, just like on mobile? That's clutter that I'd like to avoid.
## Prior art
* The new file browser in GitHub uses a similar divider with a mouse-over indicator
* mdBook and macOS Finder both allow you to resize the sidebar to nothing as a gesture to hide it
* https://www.nngroup.com/articles/drag-drop/
## Future possibilities
https://rust-lang.zulipchat.com/#narrow/stream/266220-rustdoc/topic/Table.20of.20contents proposes a new, second sidebar (a table of contents). How should it fit in with this feature? Should it be resizeable? Hideable? Can it be accessed on mobile?
This is an attempt to balance three problems, each of which would
be violated by a simpler implementation:
- A type alias should show all the `impl` blocks for the target
type, and vice versa, if they're applicable. If nothing was
done, and rustdoc continues to match them up in HIR, this
would not work.
- Copying the target type's docs into its aliases' HTML pages
directly causes far too much redundant HTML text to be generated
when a crate has large numbers of methods and large numbers
of type aliases.
- Using JavaScript exclusively for type alias impl docs would
be a functional regression, and could make some docs very hard
to find for non-JS readers.
- Making sure that only applicable docs are show in the
resulting page requires a type checkers. Do not reimplement
the type checker in JavaScript.
So, to make it work, rustdoc stashes these type-alias-inlined docs
in a JSONP "database-lite". The file is generated in `write_shared.rs`,
included in a `<script>` tag added in `print_item.rs`, and `main.js`
takes care of patching the additional docs into the DOM.
The format of `trait.impl` and `type.impl` JS files are superficially
similar. Each line, except the JSONP wrapper itself, belongs to a crate,
and they are otherwise separate (rustdoc should be idempotent). The
"meat" of the file is HTML strings, so the frontend code is very simple.
Links are relative to the doc root, though, so the frontend needs to fix
that up, and inlined docs can reuse these files.
However, there are a few differences, caused by the sophisticated
features that type aliases have. Consider this crate graph:
```text
---------------------------------
| crate A: struct Foo<T> |
| type Bar = Foo<i32> |
| impl X for Foo<i8> |
| impl Y for Foo<i32> |
---------------------------------
|
----------------------------------
| crate B: type Baz = A::Foo<i8> |
| type Xyy = A::Foo<i8> |
| impl Z for Xyy |
----------------------------------
```
The type.impl/A/struct.Foo.js JS file has a structure kinda like this:
```js
JSONP({
"A": [["impl Y for Foo<i32>", "Y", "A::Bar"]],
"B": [["impl X for Foo<i8>", "X", "B::Baz", "B::Xyy"], ["impl Z for Xyy", "Z", "B::Baz"]],
});
```
When the type.impl file is loaded, only the current crate's docs are
actually used. The main reason to bundle them together is that there's
enough duplication in them for DEFLATE to remove the redundancy.
The contents of a crate are a list of impl blocks, themselves
represented as lists. The first item in the sublist is the HTML block,
the second item is the name of the trait (which goes in the sidebar),
and all others are the names of type aliases that successfully match.
This way:
- There's no need to generate these files for types that have no aliases
in the current crate. If a dependent crate makes a type alias, it'll
take care of generating its own docs.
- There's no need to reimplement parts of the type checker in
JavaScript. The Rust backend does the checking, and includes its
results in the file.
- Docs defined directly on the type alias are dropped directly in the
HTML by `render_assoc_items`, and are accessible without JavaScript.
The JSONP file will not list impl items that are known to be part
of the main HTML file already.
[JSONP]: https://en.wikipedia.org/wiki/JSONP
Helps with #90929
This changes the search results, specifically, when there's more than
one impl with an associated item with the same name. For example,
the search queries `simd<i8> -> simd<i8>` and `simd<i64> -> simd<i64>`
don't link to the same function, but most of the functions have the
same names.
This change should probably be FCP-ed, especially since it adds a new
anchor link format for `main.js` to handle, so that URLs like
`struct.Vec.html#impl-AsMut<[T]>-for-Vec<T,+A>/method.as_mut` redirect
to `struct.Vec.html#method.as_mut-2`. It's a strange design, but there
are a few reasons for it:
* I'd like to avoid making the HTML bigger. Obviously, fixing this bug
is going to add at least a little more data to the search index, but
adding more HTML penalises viewers for the benefit of searchers.
* Breaking `struct.Vec.html#method.len` would also be a disappointment.
On the other hand:
* The path-style anchors might be less prone to link rot than the numbered
anchors. It's definitely less likely to have URLs that appear to "work",
but silently point at the wrong thing.
* This commit arranges the path-style anchor to redirect to the numbered
anchor. Nothing stops rustdoc from doing the opposite, making path-style
anchors the default and redirecting the "legacy" numbered ones.
It lints against features that are inteded to be internal to the
compiler and standard library. Implements MCP #596.
We allow `internal_features` in the standard library and compiler as those
use many features and this _is_ the standard library from the "internal to the compiler and
standard library" after all.
Marking some features as internal wasn't exactly the most scientific approach, I just marked some
mostly obvious features. While there is a categorization in the macro,
it's not very well upheld (should probably be fixed in another PR).
We always pass `-Ainternal_features` in the testsuite
About 400 UI tests and several other tests use internal features.
Instead of throwing the attribute on each one, just always allow them.
There's nothing wrong with testing internal features^^
