Greatly improve rustdoc rendering speed issues
Fixes#55900.
So a few improvements here:
* we're switching to `DOMTokenList` API when available providing a replacement if it isn't (should only happen on safari and IE I think...)
* hide doc sections by default to allow the whole HTML generation to happen in the background to avoid triggering DOM redraw all the times (which killed the performances)
r? @QuietMisdreavus
Remove unneeded extra chars to reduce search-index size
Before:
```
2013782 Dec 11 10:16 build/x86_64-unknown-linux-gnu/doc/search-index.js
```
After:
```
1736597 Dec 11 10:50 build/x86_64-unknown-linux-gnu/doc/search-index.js
```
No changes in the output of the search.
r? @QuietMisdreavus
This commit replaces many usages of `File::open` and reading or writing
with `fs::read_to_string`, `fs::read` and `fs::write`. This reduces code
complexity, and will improve performance for most reads, since the
functions allocate the buffer to be the size of the file.
I believe that this commit will not impact behavior in any way, so some
matches will check the error kind in case the file was not valid UTF-8.
Some of these cases may not actually care about the error.
Replace usages of `..i + 1` ranges with `..=i`.
Before this change we were using old computer code techniques. After this change we use the new and improved computer code techniques.
emit error when doc generation fails
Fixes#41813.
The diagnostic looks something like this:
```
error: couldn't generate documentation: No space left on device (os error 28)
|
= note: failed to create or modify "/path/to/crate/target/doc/src/lazycell"
```
rustdoc: refactor: centralize all command-line argument parsing
This is something i've wanted to do for a while, since we keep having to add new arguments to places like `rust_input` or `core::run_core` whenever we add a new CLI flag or the like. Those functions have inflated up to 11-19, and in some cases hiding away the locations where some CLI flags were being parsed, obscuring their use. Now, we have a central place where all command-line configuration occurs, including argument validation.
One note about the design: i grouped together all the arguments that `html::render::run` needed, so that i could pass them on from compilation in one lump instead of trying to thread through individual items or clone the entire blob ahead of time.
One other thing this adds is that rustdoc also now recognizes all the `-Z` options that rustc does, since we were manually grabbing a few previously. Now we parse a full `DebuggingOptions` struct and hand it directly to rustc when scraping docs.
Add index page argument
@Mark-Simulacrum: I might need some help from you: in bootstrap, I want to add an argument (a new flag added into `rustdoc`) in order to generate the current index directly when `rustdoc` is documenting the `std` lib. However, my change in `bootstrap` didn't do it and I assume it must be moved inside the `Std` struct. But there, I don't see how to pass it to `rustdoc` through `cargo`. Did I miss anything?
r? @QuietMisdreavus
