The code currently ignores the actual delimiter on the RHS and fakes up
a `NoDelim`/`DelimSpan::dummy()` one. This commit changes it to use the
actual delimiter.

The commit also reorders the fields for the `Delimited` variant to match
the `Sequence` variant.

…trochenkov

make `fn() -> _ { .. }` suggestion MachineApplicable

This might not be valid, but it would be nice to promote this to `MachineApplicable` so people can use rustfix here.

Also de65fcf009d07019689cfad7f327667e390a325d is to [restore the suggestion for `issue-77179.rs`](rust-lang@de65fcf#diff-12e43fb5d6d12ec7cb5c6b48204a18d113cf5de0e12eb71a358b639bd9aadaf0R8). (though in this case, the code in that issue still doesn't compile, so it's not marked with rustfix).

Make EncodeWide implement FusedIterator

[`EncodeUtf16`](https://doc.rust-lang.org/std/str/struct.EncodeUtf16.html) and [`EncodeWide`](https://doc.rust-lang.org/std/os/windows/ffi/struct.EncodeWide.html) currently serve similar purposes: They convert from UTF-8 to UTF-16 and WTF-8 to WTF-16, respectively. `EncodeUtf16` wraps a &str, whereas `EncodeWide` wraps an &OsStr.

When Iteration has concluded, these iterators wrap an empty slice, which will forever yield `None` values. Hence, `EncodeUtf16` rightfully implements `FusedIterator`. However, `EncodeWide` in contrast does not, even though it serves an almost identical purpose.

This PR attempts to fix that issue. I consider this change minor and non-controversial, hence why I have not added a RFC/FCP. Please let me know if the stability attribute is wrong or contains a wrong version number. Thanks in advance.

Fixes rust-lang#96368

…enkov

Less `NoDelim`

Currently there are several places where `NoDelim` (which really means "implicit delimiter" or "invisible delimiter") is used to mean "no delimiter". The name `NoDelim` is a bit misleading, and may be a cause.

This PR changes these places, e.g. by changing a `DelimToken` to `Option<DelimToken>` and then using `None` to mean "no delimiter". As a result, the *only* place where `NoDelim` values are now produced is within:
- `Delimiter::to_internal()`, when converting from `Delimiter::None`.
- `FlattenNonterminals::process_token()`, when converting `TokenKind::Interpolated`.

r? ````@petrochenkov````

not need `Option` for `dbg_scope`

This PR fixes a few FIXME about not using `Option` in `dbg_scope` field of `DebugScope`, during `create_function_debug_context` func in codegen parts.
Added a `BitSet<SourceScope>` parameter to `make_mir_scope` to indicate whether the `DebugScope` has been instantiated.
cc ````@eddyb````

…, r=davidtwco

Better error messages when collecting into `[T; n]`

Fixes rust-lang#96461

…, r=lcnr

replace let else with `?`

r? `@oli-obk`

…etrochenkov

Add missing `target_feature` to the list of well known cfg names

This PR adds the missing `target_feature` cfg name to the list of well known cfg names.

It was notice missing in rust-lang#96472 thanks to `@bjorn3,` the reason being that `--check-cfg=names()` automatically inherit the names passed by `--cfg` (or internal to `rustc`) and is seems that the vast majority of targets have at least one target feature leading to `target_feature` being a well known name in most target but it should always be a well known name so this PR add it unconditionally to list.

r? `@petrochenkov`