Auto merge of rust-lang#126736 - matthiaskrgr:rollup-rb20oe3, r=matthiaskrgr

Rollup of 7 pull requests

Successful merges:

 - rust-lang#126380 (Add std Xtensa targets support)
 - rust-lang#126636 (Resolve Clippy `f16` and `f128` `unimplemented!`/`FIXME`s )
 - rust-lang#126659 (More status-quo tests for the `#[coverage(..)]` attribute)
 - rust-lang#126711 (Make Option::as_[mut_]slice const)
 - rust-lang#126717 (Clean up some comments near `use` declarations)
 - rust-lang#126719 (Fix assertion failure for some `Expect` diagnostics.)
 - rust-lang#126730 (Add opaque type corner case test)

r? `@ghost`
`@rustbot` modify labels: rollup

Author: bors

alloc/src/boxed/thin.rs

@@ -1,6 +1,7 @@
-// Based on
-// https://github.com/matthieu-m/rfc2580/blob/b58d1d3cba0d4b5e859d3617ea2d0943aaa31329/examples/thin.rs
-// by matthieu-m
+//! Based on
+//! <https://github.com/matthieu-m/rfc2580/blob/b58d1d3cba0d4b5e859d3617ea2d0943aaa31329/examples/thin.rs>
+//! by matthieu-m
+
 use crate::alloc::{self, Layout, LayoutError};
 use core::error::Error;
 use core::fmt::{self, Debug, Display, Formatter};

alloc/src/vec/in_place_collect.rs

@@ -154,6 +154,7 @@
 //! }
 //! vec.truncate(write_idx);
 //! ```
+
 use crate::alloc::{handle_alloc_error, Global};
 use core::alloc::Allocator;
 use core::alloc::Layout;

core/src/option.rs

@@ -797,7 +797,8 @@ impl<T> Option<T> {
     #[inline]
     #[must_use]
     #[stable(feature = "option_as_slice", since = "1.75.0")]
-    pub fn as_slice(&self) -> &[T] {
+    #[rustc_const_unstable(feature = "const_option_ext", issue = "91930")]
+    pub const fn as_slice(&self) -> &[T] {
         // SAFETY: When the `Option` is `Some`, we're using the actual pointer
         // to the payload, with a length of 1, so this is equivalent to
         // `slice::from_ref`, and thus is safe.
@@ -811,7 +812,7 @@ impl<T> Option<T> {
         unsafe {
             slice::from_raw_parts(
                 (self as *const Self).byte_add(core::mem::offset_of!(Self, Some.0)).cast(),
-                usize::from(self.is_some()),
+                self.is_some() as usize,
             )
         }
     }
@@ -851,7 +852,8 @@ impl<T> Option<T> {
     #[inline]
     #[must_use]
     #[stable(feature = "option_as_slice", since = "1.75.0")]
-    pub fn as_mut_slice(&mut self) -> &mut [T] {
+    #[rustc_const_unstable(feature = "const_option_ext", issue = "91930")]
+    pub const fn as_mut_slice(&mut self) -> &mut [T] {
         // SAFETY: When the `Option` is `Some`, we're using the actual pointer
         // to the payload, with a length of 1, so this is equivalent to
         // `slice::from_mut`, and thus is safe.
@@ -867,7 +869,7 @@ impl<T> Option<T> {
         unsafe {
             slice::from_raw_parts_mut(
                 (self as *mut Self).byte_add(core::mem::offset_of!(Self, Some.0)).cast(),
-                usize::from(self.is_some()),
+                self.is_some() as usize,
             )
         }
     }

core/src/str/count.rs

@@ -17,6 +17,7 @@
 //! Note: Because the term "leading byte" can sometimes be ambiguous (for
 //! example, it could also refer to the first byte of a slice), we'll often use
 //! the term "non-continuation byte" to refer to these bytes in the code.
+
 use core::intrinsics::unlikely;
 
 const USIZE_SIZE: usize = core::mem::size_of::<usize>();

core/tests/iter/adapters/map_windows.rs

@@ -3,6 +3,7 @@ use std::sync::atomic::{AtomicUsize, Ordering::SeqCst};
 #[cfg(not(panic = "abort"))]
 mod drop_checks {
     //! These tests mainly make sure the elements are correctly dropped.
+
     use std::sync::atomic::{AtomicBool, AtomicUsize, Ordering::SeqCst};
 
     #[derive(Debug)]

core/tests/net/parser.rs

@@ -1,4 +1,5 @@
 // FIXME: These tests are all excellent candidates for AFL fuzz testing
+
 use core::net::{IpAddr, Ipv4Addr, Ipv6Addr, SocketAddr, SocketAddrV4, SocketAddrV6};
 use core::str::FromStr;
 

core/tests/num/ieee754.rs

@@ -27,6 +27,7 @@
 //! standard. That is why they accept wildly diverse inputs or may seem to duplicate other tests.
 //! Please consider this carefully when adding, removing, or reorganizing these tests. They are
 //! here so that it is clear what tests are required by the standard and what can be changed.
+
 use ::core::str::FromStr;
 
 // IEEE 754 for many tests is applied to specific bit patterns.

core/tests/option.rs

@@ -574,4 +574,13 @@ fn as_slice() {
     assert_eq!(Some(43).as_mut_slice(), &[43]);
     assert_eq!(None::<i32>.as_slice(), &[]);
     assert_eq!(None::<i32>.as_mut_slice(), &[]);
+
+    const A: &[u32] = Some(44).as_slice();
+    const B: &[u32] = None.as_slice();
+    const _: () = {
+        let [45] = Some(45).as_mut_slice() else { panic!() };
+        let []: &[u32] = None.as_mut_slice() else { panic!() };
+    };
+    assert_eq!(A, &[44]);
+    assert_eq!(B, &[]);
 }

core/tests/pin_macro.rs

@@ -1,4 +1,5 @@
 // edition:2021
+
 use core::{
     marker::PhantomPinned,
     mem::{drop as stuff, transmute},

panic_unwind/src/miri.rs

@@ -1,4 +1,5 @@
 //! Unwinding panics for Miri.
+
 use alloc::boxed::Box;
 use core::any::Any;