I’ve found myself visiting the documentation for `std::env::vars`
every few months, and every time I do, it is because I want to quickly
get a snippet to print out all environment variables :-)

So I think it could be nice to simplify the examples a little to make
them self-contained. It is of course a style question if one should
import a module a not, but I personally don’t import modules used just
once in a code snippet.

Co-authored-by: Jonas Böttiger <jonasboettiger@icloud.com>

There are some comments describing multiple subsequent `use` items. When
the big `use` reformatting happens some of these `use` items will be
reordered, possibly moving them away from the comment. With this
additional level of formatting it's not really feasible to have comments
of this type. This commit removes them in various ways:

- merging separate `use` items when appropriate;

- inserting blank lines between the comment and the first `use` item;

- outright deletion (for comments that are relatively low-value);

- adding a separate "top-level" comment.

We also entirely skip formatting for four library files that contain
nothing but `pub use` re-exports, where reordering would be painful.

When we do the big `use` reformatting there are a tiny number of cases
where rustfmt moves a comment from one `use` item to another in an
undesirable way. This commit pre-emptively rearranges things to prevent
this from happening.

This also adds an additional `unsafe` block to address compiler errors.

Co-authored-by: Clar Fon <15850505+clarfonthey@users.noreply.github.com>

…jhpratt,tgross35

Simplify environment variable examples

I’ve found myself visiting the documentation for `std::env::vars` every few months, and every time I do, it is because I want to quickly get a snippet to print out all environment variables :-)

So I think it could be nice to simplify the examples a little to make them self-contained. It is of course a style question if one should import a module a not, but I personally don’t import modules used just once in a code snippet.

…'s-test, r=jieyouxu

Migrate `compiler-lookup-paths`, `dump-mono-stats` and `prune-link-args` `run-make` tests to `rmake` or `ui` format

Part of rust-lang#121876 and the associated [Google Summer of Code project](https://blog.rust-lang.org/2024/05/01/gsoc-2024-selected-projects.html).

try-job: x86_64-msvc
try-job: aarch64-apple
try-job: dist-x86_64-linux
try-job: armhf-gnu

… r=tgross35

Skip fast path for dec2flt when optimize_for_size

Tracking issue: rust-lang#125612

Skip the fast algorithm when optimizing for size.
When compiling for https://github.com/quartiq/stabilizer I get these numbers:

Before
```
   text    data     bss     dec     hex filename
 192192       8   49424  241624   3afd8 dual-iir
```

After
```
   text    data     bss     dec     hex filename
 191632       8   49424  241064   3ada8 dual-iir
```

This saves 560 bytes.

…ps-2, r=cuviper

Clean up more comments near use declarations

rust-lang#125443 will reformat all use declarations in the repository. There are a few edge cases involving comments on use declarations that require care. This PR fixes them up so rust-lang#125443 can go ahead with a simple `x fmt --all`. A follow-up to rust-lang#126717.

r? `@cuviper`

`impl Send + Sync` and override `count` for the `CStr::bytes` iterator

cc tracking issue rust-lang#112115

…warfier, r=joboet

std: Use `read_unaligned` for reads from DWARF

There's a lot of... *stuff* going on here. Meanwhile, `read_unaligned` has been available since 1.17.0, so let's just use that.

Use futex.rs for Windows thread parking

If I'm not overlooking anything then the Windows 10+ thread parking implementation is practically the same as the futex.rs implementation. So we may as well use the same implementation for both. The old version is still kept around for Windows 7 support.

r? ```@joboet``` if you wouldn't mind double checking I've not missed something

Rename `tcx` to `cx` in `rustc_type_ir`

Self-explanatory. Forgot that we had to do this in type_ir too, and not just the new solver crate lol.

r? lcnr

Update method name to reflect changes to its internals

forgot to do this in rust-lang#127431

…kingjubilee

zkvm: add `#[forbid(unsafe_op_in_unsafe_fn)]` in `stdlib`

This also adds an additional `unsafe` block to address compiler errors.
This PR is intended to address rust-lang#127747 for the zkvm target.

…n-xous-uefi, r=tgross35

std: Forbid unwrapped unsafe ops in xous and uefi modules