Auto merge of #97522 - xfix:stabilize-slice-from-raw-parts, r=dtolnay

Partially stabilize const_slice_from_raw_parts

This doesn't stabilize methods working on mutable pointers.

This pull request continues from #94946.

Pinging `@rust-lang/wg-const-eval` this because I use `rustc_allow_const_fn_unstable`. I believe this is justifiable as it's already possible to use `slice::from_raw_parts` in stable by abusing `transmute`. The stable alternative to this would be to provide a stable const implementation of `std::ptr::from_raw_parts` (as it can already be implemented in stable).

```rust
use std::mem;

#[repr(C)]
struct Slice<T> {
    data: *const T,
    len: usize,
}

fn main() {
    let data: *const i32 = [1, 2, 3, 4].as_ptr();
    let len = 4;
    println!("{:?}", unsafe {
        mem::transmute::<Slice<i32>, &[i32]>(Slice { data, len })
    });
}
```

`@rustbot` modify labels: +T-libs-api

1 files changed, 0 insertions, 1 deletions

diff --git a/compiler/rustc_codegen_cranelift/example/issue-91827-extern-types.rs b/compiler/rustc_codegen_cranelift/example/issue-91827-extern-types.rs
index cf8fada5320..2ecc8b8238b 100644
--- a/compiler/rustc_codegen_cranelift/example/issue-91827-extern-types.rs
+++ b/compiler/rustc_codegen_cranelift/example/issue-91827-extern-types.rs
@@ -6,7 +6,6 @@
 // Regression test for issue #91827.
 
 #![feature(const_ptr_offset_from)]
-#![feature(const_slice_from_raw_parts)]
 #![feature(extern_types)]
 
 use std::ptr::addr_of;