Auto merge of #111567 - Urgau:uplift_cast_ref_to_mut, r=b-naber

Uplift `clippy::cast_ref_to_mut` lint

This PR aims at uplifting the `clippy::cast_ref_to_mut` lint into rustc.

## `cast_ref_to_mut`

(deny-by-default)

The `cast_ref_to_mut` lint checks for casts of `&T` to `&mut T` without using interior mutability.

### Example

```rust,compile_fail
fn x(r: &i32) {
    unsafe {
        *(r as *const i32 as *mut i32) += 1;
    }
}
```

### Explanation

Casting `&T` to `&mut T` without interior mutability is undefined behavior, as it's a violation of Rust reference aliasing requirements.

-----

Mostly followed the instructions for uplifting a clippy lint described here: https://github.com/rust-lang/rust/pull/99696#pullrequestreview-1134072751

`@rustbot` label: +I-lang-nominated
r? compiler

-----

For Clippy:

changelog: Moves: Uplifted `clippy::cast_ref_to_mut` into rustc

2 files changed, 2 insertions, 0 deletions

diff --git a/library/core/src/ptr/const_ptr.rs b/library/core/src/ptr/const_ptr.rs
index c579c3672a7..926189a17b2 100644
--- a/library/core/src/ptr/const_ptr.rs
+++ b/library/core/src/ptr/const_ptr.rs
@@ -104,6 +104,7 @@ impl<T: ?Sized> *const T {
     /// refactored.
     #[stable(feature = "ptr_const_cast", since = "1.65.0")]
     #[rustc_const_stable(feature = "ptr_const_cast", since = "1.65.0")]
+    #[rustc_diagnostic_item = "ptr_cast_mut"]
     #[inline(always)]
     pub const fn cast_mut(self) -> *mut T {
         self as _
diff --git a/library/core/src/ptr/mod.rs b/library/core/src/ptr/mod.rs
index d0cb2f715d0..acc9ca29d41 100644
--- a/library/core/src/ptr/mod.rs
+++ b/library/core/src/ptr/mod.rs
@@ -698,6 +698,7 @@ where
 #[inline(always)]
 #[must_use]
 #[unstable(feature = "ptr_from_ref", issue = "106116")]
+#[rustc_diagnostic_item = "ptr_from_ref"]
 pub const fn from_ref<T: ?Sized>(r: &T) -> *const T {
     r
 }