Rollup merge of #71148 - bluss:vec-drop-raw-slice, r=RalfJung

Vec drop and truncate: drop using raw slice *mut [T]

By creating a *mut [T] directly (without going through &mut [T]), avoid
questions of validity of the contents of the slice.

Consider the following risky code:

```rust
unsafe {
    let mut v = Vec::<bool>::with_capacity(16);
    v.set_len(16);
}
```

The intention is that with this change, we avoid one of the soundness
questions about the above snippet, because Vec::drop no longer
produces a mutable slice of the vector's contents.

r? @RalfJung

0 files changed, 0 insertions, 0 deletions