rustdoc: Censor certain complex unevaluated const exprs
Fixes#97933.
This is more of a hotfix for the aforementioned issue. By that, I mean that my proposed patch is
not the best solution but one that does not change as much existing code.
It treats symptoms rather than the root cause.
This PR “censors” certain complex unevaluated constant expressions like `match`es, blocks, function calls, struct literals etc. by pretty-printing them as `_` / `{ _ }` (number and string literals, paths and `()` are still printed as one would expect).
Resorting to this placeholder is preferable to printing the full expression verbatim since
they can be quite large and verbose resulting in an unreadable mess in the generated documentation.
Further, mindlessly printing the const would leak private and `doc(hidden)` struct fields (#97933), at least in the current
stable & nightly implementations which rely on `span_to_snippet` (!) and `rustc_hir_pretty::id_to_string`.
The censoring of _verbose_ expressions is probably going to stay longer term.
However, in regards to private and `doc(hidden)` struct fields, I have a more proper fix in mind
which I have already partially implemented locally and for which I am going to open a separate PR sometime soon.
For that, I was already in contact with `@GuillaumeGomez.`
The proper fix involves rustdoc not falling back on pretty-printing unevaluated consts so easily (what this PR is concerned about)
and instead preferring to print evaluated consts which contain more information allowing it to selectively hide private and `doc(hidden)` fields, create hyperlinks etc. generally making the output more granular and precise (compared to the brutal `_` placeholder).
Unfortunately, I was a bit too late and the issue just hit stable (1.62).
Should this be backported to beta or even a potential 1.62.1?
r? `@GuillaumeGomez`
This reduces the size of the function signature index, because
it's common to have many functions that operate on the same types.
$ wc -c search-index-old.js search-index-new.js
5224374 search-index-old.js
3932314 search-index-new.js
By my math, this reduces the uncompressed size of the search index by 32%.
On compressed signatures, the wins are less drastic, a mere 8%:
$ wc -c search-index-old.js.gz search-index-new.js.gz
404532 search-index-old.js.gz
371635 search-index-new.js.gz
Now that the "All Crates" dropdown is only rendered on the search results page,
there is no need to load crates.js on most pages. Load it only on crate pages.
Also, add the `defer` attribute so it does not block page rendering.
For sidebar-items.js, move the script tag to `<head>`. Since it already has the
defer attribute it won't block loading. The defer attribute does preserve
ordering between scripts, so instead of the callback on load, it can set a
global variable on load, which is slightly simpler. Also, since it is required
to finish rendering the page, beginning its load earlier is better.
Remove generation and handling of sidebar-vars. Everything there can be computed
with information available in JS via other means.
Remove the "other" wrapper in the sidebar. It was unnecessary.
Remove excess script fields
Hack: many traits and types in std are re-exported from core or alloc. In
general, rustdoc is capable of recognizing these implementations as being
on local types. However, in at least one case, rustdoc gets confused and
labels an implementation as being on a foreign type. To make sure that
confusion doesn't pass on to the reader, consider all implementations in
std, core, and alloc to be on local types.
Remove `#[rustc_deprecated]`
This removes `#[rustc_deprecated]` and introduces diagnostics to help users to the right direction (that being `#[deprecated]`). All uses of `#[rustc_deprecated]` have been converted. CI is expected to fail initially; this requires #95958, which includes converting `stdarch`.
I plan on following up in a short while (maybe a bootstrap cycle?) removing the diagnostics, as they're only intended to be short-term.
Improve Rustdoc UI for scraped examples with multiline arguments, fix overflow in line numbers
This PR improves a few aspects of the scrape examples feature in Rustdoc.
* Only function names and not the full call expression are highlighted.
* For call-sites with multiline arguments, the minimized code viewer will scroll to the top of the call-site rather than the middle if the argument is larger than the viewer size, ensuring that the function name is visible.
* This fixes an issue where the line numbers column had a visible x-scroll bar.
r? `@GuillaumeGomez`
librustdoc: adopt let else in more places
Continuation of #89933, #91018, #91481, #93046, #93590, #94011.
I have extended my clippy lint to also recognize tuple passing and match statements. The diff caused by fixing it is way above 1 thousand lines. Thus, I split it up into multiple pull requests to make reviewing easier. This PR handles librustdoc.
Refactor sidebar printing code
This is the refactoring parts of #92660, plus the trait aliases capitalization
consistency fix. I think this will be necessary for #92658.
r? `@GuillaumeGomez`
The new code is much simpler and easier to understand. In fact, the old
code actually had a subtle bug where it excluded a few item types,
including trait aliases, from the sidebar, even though they are rendered
on the page itself! Now, all sections should show up in the sidebar.
