Closes rust-lang#82423

Pass callee expr to `confirm_builtin_call`. This removes a partial
pattern match in `confirm_builtin_call` and the `panic` in the `else`
branch. The diff is large because of indentation changes caused by
removing the if-let.

This ownership kind is only constructed in the case of path attributes like `#[path = ".."]` without a file name segment, which always represent some kind of directories and will produce and error on attempt to parse them as a module file.

…data

Also don't push the paths on the stack directly in `fn parse_external_mod`, return them instead.

…n span

…-line modules

…ing speculative

…acros`

This logic is applicable to two specific macros and not to the expansion infrastructure in general.

This is simpler and mirrors what invocation collector does

…_eval`

Fixes some punctuation and formatting; also makes some small wording changes.

As discussed in the issue tracker for the wg-allocators working group[1], updating this implementation for allocator support was most likely just forgotten in the original PR.

[1]: rust-lang/wg-allocators#86

bypass auto_da_alloc for metadata files

This saves about 0.7% when rerunning the UI test suite. I.e. when the metadata files exist and will be overwritten. No improvements expected for a clean build. So it might show up in incr-patched perf results.
```
regular rename:

Benchmark rust-lang#1: touch src/tools/compiletest/src/main.rs ; RUSTC_WRAPPER="" schedtool -B -e ./x.py test src/test/ui
  Time (mean ± σ):     47.305 s ±  0.170 s    [User: 1631.540 s, System: 412.648 s]
  Range (min … max):   47.125 s … 47.856 s    20 runs

non-durable rename:

Benchmark rust-lang#1: touch src/tools/compiletest/src/main.rs ; RUSTC_WRAPPER="" schedtool -B -e ./x.py test src/test/ui
  Time (mean ± σ):     46.930 s ±  0.064 s    [User: 1634.344 s, System: 396.038 s]
  Range (min … max):   46.759 s … 47.043 s    20 runs
```

There are more places that trigger auto_da_alloc behavior by overwriting existing files with O_TRUNC, but those are much harder to locate because `O_TRUNC` is set on `open()` but the writeback is triggered on `close()`. The latter is the part which shows up in profiles.

expand: Refactor module loading

This is an accompanying PR to rust-lang#82399, but they can be landed independently.
See individual commits for more details.

Anyone should be able to review this equally well because all people actually familiar with this code left the project.

Add natvis for Result, NonNull, CString, CStr, and Cow

This adds natvis support (used for Windows debugging) to the following types: `Result`, `NonNull`, `CString`, `CStr`, and `Cow`.

Remove Item::kind, use tagged enum. Rename variants to match

Fixes rust-lang#82299, by making the ItemEnum tagged. Doesn't remove ItemKind as it's still used in other places.

r? `````@jyn514`````
`````@rustbot````` label: +A-rustdoc-json +T-rustdoc

Fix jemalloc usage on OSX

Closes rust-lang#82423

Implement built-in attribute macro `#[cfg_eval]` + some refactoring

This PR implements a built-in attribute macro `#[cfg_eval]` as it was suggested in rust-lang#79078 to avoid `#[derive()]` without arguments being abused as a way to configure input for other attributes.

The macro is used for eagerly expanding all `#[cfg]` and `#[cfg_attr]` attributes in its input ("fully configuring" the input).
The effect is identical to effect of `#[derive(Foo, Bar)]` which also fully configures its input before passing it to macros `Foo` and `Bar`, but unlike `#[derive]` `#[cfg_eval]` can be applied to any syntax nodes supporting macro attributes, not only certain items.

`cfg_eval` was the first name suggested in rust-lang#79078, but other alternatives are also possible, e.g. `cfg_expand`.

```rust
#[cfg_eval]
#[my_attr] // Receives `struct S {}` as input, the field is configured away by `#[cfg_eval]`
struct S {
    #[cfg(FALSE)]
    field: u8,
}
```

Tracking issue: rust-lang#82679

Disable destination propagation on all mir-opt-levels

The new `// compile-flags: -Zunsound-mir-opts` are inserted without an extra newline to avoid introducing a large mir-opt diff.

… r=petrochenkov

Refactor confirm_builtin_call, remove partial if

Pass callee expr to `confirm_builtin_call`. This removes a partial
pattern match in `confirm_builtin_call` and the `panic` in the `else`
branch. The diff is large because of indentation changes caused by
removing the if-let.

…ylan-DPC

Edit ructc_ast_lowering docs

Fixes some punctuation and formatting; also makes some small wording changes.

…r=TimDiekmann

Generalize Write impl for Vec<u8> to Vec<u8, A>

As discussed in the [issue tracker for the wg-allocators working group][1], updating this impl for allocator support was most likely just forgotten previously. This PR fixes this.

r? `````@TimDiekmann`````

[1]: rust-lang/wg-allocators#86