…ng in index

Updates to mdbook 0.4.44.
Changelog: https://github.com/rust-lang/mdBook/blob/master/CHANGELOG.md#mdbook-0444

```
error[E0596]: cannot borrow `*self.s` as mutable, as it is behind a `&` reference
  --> $DIR/issue-38147-1.rs:17:9
   |
LL |         self.s.push('x');
   |         ^^^^^^ `self` is a `&` reference, so the data it refers to cannot be borrowed as mutable
   |
help: consider changing this to be a mutable reference
   |
LL |     fn f(&mut self) {
   |           +++
```

Note the suggestion to add `mut` instead of replacing the entire `&self` with `&mut self`.

Suggest considering casting fn item as fn pointer in more cases

Fixes rust-lang#132648

[rustdoc] Add sans-serif font setting

Fixes rust-lang#52449.

This PR adds a new setting introducing the possibility to switch to a sans-serif font (`Fira Sans`) for the text.

Can be tested [here](https://rustdoc.crud.net/imperio/sans-serif/std/index.html).

cc `@rust-lang/rustdoc-frontend`
r? `@notriddle`

Test pipes also when not running on Windows and Linux simultaneously

Fixes rust-lang#135635 (review).

Based on top of rust-lang#135635 to avoid merge conflicts.

…=Kobzol

ci: use windows 2025 for i686-mingw

try-job: i686-mingw

Remove duplicated code in RISC-V asm bad-reg test

I added this test in rust-lang#132516, but I accidentally repeated the same check twice.

https://github.com/rust-lang/rust/blob/aa6f5ab18e67cb815f73e0d53d217bc54b0da924/tests/ui/asm/riscv/bad-reg.rs#L39-L42

…jieyouxu

Fix a couple Emscripten tests

This fixes a couple Emscripten tests where the correct fix is more or less obvious. A couple UI tests are still broken with this PR:

- `tests/ui/abi/numbers-arithmetic/return-float.rs` (rust-lang#136197)
- `tests/ui/no_std/no-std-unwind-binary.rs` (haven't debugged yet)
- `tests/ui/test-attrs/test-passed.rs` (haven't debugged this either)

`@rustbot` label +T-compiler +O-emscripten

Properly check that array length is valid type during built-in unsizing in index

This results in duplicated errors, but this class of errors is not new; in general, we aren't really equipped to detect cases where a WF error due to a field type would be shadowed by the parent struct of that field also not being WF.

This also adds a note for these types of mismatches to make it clear that this is due to an array type.

Fixes rust-lang#134352

r? boxyuwu

Update mdbook to 0.4.44

Updates to mdbook 0.4.44.
Changelog: https://github.com/rust-lang/mdBook/blob/master/CHANGELOG.md#mdbook-0444

Tweak `&mut self` suggestion span

```
error[E0596]: cannot borrow `*self.s` as mutable, as it is behind a `&` reference
  --> $DIR/issue-38147-1.rs:17:9
   |
LL |         self.s.push('x');
   |         ^^^^^^ `self` is a `&` reference, so the data it refers to cannot be borrowed as mutable
   |
help: consider changing this to be a mutable reference
   |
LL |     fn f(&mut self) {
   |           +++
```

Note the suggestion to add `mut` instead of replacing the entire `&self` with `&mut self`.