The `cargo asm` tool pattern matches on such labels to figure out where functions end: normal functions generated by LLVM always do have such a label. We don't guarantee that naked functions emit such a label, but having `cargo asm` work is convenient

Improve doc of some methods that take ranges

Some methods that were taking some range in parameter were a bit inconsistent / unclear in the panic documentation.

Here is the recap:
- Replaced "start/end point" by "start/end bound" to be coherent with [`RangeBounds`](https://doc.rust-lang.org/stable/std/ops/trait.RangeBounds.html) naming (it's also easier to understand I think)
- Previously, it was written "_[...] or if the end point is greater than the length of [...]_", but this is not entirely true! Actually, you can have a start bound that is greater than the length, with an end bound that is unbounded and it will also panic. Therefore I think that "_[...] one of the range bound is bounded and greater than the length of [...]_" is better!
- `String` methods weren't mentionning that the method panics if `start_bound > end_bound` but it actually does! It uses `slice::range` which panics when `start > end`.  (https://doc.rust-lang.org/stable/src/alloc/string.rs.html#1932-1934, https://doc.rust-lang.org/stable/src/core/slice/index.rs.html#835-837).
You can also test it with:
```rs
struct MyRange;
impl std::ops::RangeBounds<usize> for MyRange {
    fn start_bound(&self) -> std::ops::Bound<&usize> {
        std::ops::Bound::Included(&3usize)
    }
    fn end_bound(&self) -> std::ops::Bound<&usize> {
        std::ops::Bound::Included(&1usize)
    }
}

fn main() {
    let mut s = String::from("I love Rust!");
    s.drain(MyRange); // panics!
}
```

…r=Mark-Simulacrum

Stabilize `new_zeroed_alloc`

The corresponding `new_uninit` and `new_uninit_slice` functions were stabilized in rust-lang#129401, but the zeroed counterparts were left for later out of a [desire](rust-lang#63291 (comment)) to stabilize only the minimal set. These functions are straightforward mirrors of the uninit functions and well-established. Since no blockers or design questions have surfaced in the past year, I think it's time to stabilize them.

Tracking issue: rust-lang#129396

…k-Simulacrum

Stabilize `std::panic::Location::file_as_c_str`

Closes: rust-lang#141727

Nominating this for T-lang as per `@traviscross`  rust-lang#141727 (comment)

…=cjgillot

Deref related cleanups in ref_prop

Cherry picked from rust-lang#146710

r? cjgillot

…manieu

naked_asm: emit a label starting with `func_end`

The `cargo asm` tool (`cargo install cargo-show-asm`) pattern matches on such labels to figure out where functions end: normal functions generated by LLVM always do have such a label. We don't guarantee that naked functions emit such a label, but having `cargo asm` work is convenient.

https://github.com/pacak/cargo-show-asm/blob/be45f67454ad8b634246a7fc69b3c6a963ee93f1/src/asm/statements.rs#L897-L901

To make the label name unique it's suffixed with the name of the current symbol.

r? `@Amanieu`

Fix old typo in lang_start_internal comment

Noticed this when reading the rt cleanup code; the typo was introduced during a mass port of libstd to std in comments.