Auto merge of rust-lang#147745 - matthiaskrgr:rollup-b4kftk9, r=matthiaskrgr

Rollup of 11 pull requests

Successful merges:

 - rust-lang#143191 (Stabilize `rwlock_downgrade` library feature)
 - rust-lang#147444 (Allow printing a fully-qualified path in `def_path_str`)
 - rust-lang#147527 (Update t-compiler beta nomination Zulip msg)
 - rust-lang#147670 (some `ErrorGuaranteed` cleanups)
 - rust-lang#147676 (Return spans out of `is_doc_comment` to reduce reliance on `.span()` on attributes)
 - rust-lang#147708 (const `mem::drop`)
 - rust-lang#147710 (Fix ICE when using contracts on async functions)
 - rust-lang#147716 (Fix some comments)
 - rust-lang#147718 (miri: use allocator_shim_contents codegen helper)
 - rust-lang#147729 (ignore boring locals when explaining why a borrow contains a point due to drop of a live local under polonius)
 - rust-lang#147742 (Revert unintentional whitespace changes to rustfmt-excluded file)

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

Author: bors

core/src/mem/mod.rs

@@ -6,7 +6,7 @@
 #![stable(feature = "rust1", since = "1.0.0")]
 
 use crate::alloc::Layout;
-use crate::marker::DiscriminantKind;
+use crate::marker::{Destruct, DiscriminantKind};
 use crate::panic::const_assert;
 use crate::{clone, cmp, fmt, hash, intrinsics, ptr};
 
@@ -958,8 +958,13 @@ pub const fn replace<T>(dest: &mut T, src: T) -> T {
 /// [`RefCell`]: crate::cell::RefCell
 #[inline]
 #[stable(feature = "rust1", since = "1.0.0")]
+#[rustc_const_unstable(feature = "const_destruct", issue = "133214")]
 #[rustc_diagnostic_item = "mem_drop"]
-pub fn drop<T>(_x: T) {}
+pub const fn drop<T>(_x: T)
+where
+    T: [const] Destruct,
+{
+}
 
 /// Bitwise-copies a value.
 ///

std/src/sync/nonpoison/rwlock.rs

@@ -700,7 +700,6 @@ impl<'rwlock, T: ?Sized> RwLockWriteGuard<'rwlock, T> {
     ///
     /// ```
     /// #![feature(nonpoison_rwlock)]
-    /// #![feature(rwlock_downgrade)]
     ///
     /// use std::sync::nonpoison::{RwLock, RwLockWriteGuard};
     ///
@@ -719,7 +718,6 @@ impl<'rwlock, T: ?Sized> RwLockWriteGuard<'rwlock, T> {
     ///
     /// ```
     /// #![feature(nonpoison_rwlock)]
-    /// #![feature(rwlock_downgrade)]
     ///
     /// use std::sync::Arc;
     /// use std::sync::nonpoison::{RwLock, RwLockWriteGuard};
@@ -752,8 +750,7 @@ impl<'rwlock, T: ?Sized> RwLockWriteGuard<'rwlock, T> {
     /// # let final_check = rw.read();
     /// # assert_eq!(*final_check, 3);
     /// ```
-    #[unstable(feature = "rwlock_downgrade", issue = "128203")]
-    // #[unstable(feature = "nonpoison_rwlock", issue = "134645")]
+    #[unstable(feature = "nonpoison_rwlock", issue = "134645")]
     pub fn downgrade(s: Self) -> RwLockReadGuard<'rwlock, T> {
         let lock = s.lock;
 

std/src/sync/poison/rwlock.rs

@@ -813,8 +813,6 @@ impl<'rwlock, T: ?Sized> RwLockWriteGuard<'rwlock, T> {
     /// `downgrade` takes ownership of the `RwLockWriteGuard` and returns a [`RwLockReadGuard`].
     ///
     /// ```
-    /// #![feature(rwlock_downgrade)]
-    ///
     /// use std::sync::{RwLock, RwLockWriteGuard};
     ///
     /// let rw = RwLock::new(0);
@@ -831,8 +829,6 @@ impl<'rwlock, T: ?Sized> RwLockWriteGuard<'rwlock, T> {
     /// thread calling `downgrade` and any reads it performs after downgrading.
     ///
     /// ```
-    /// #![feature(rwlock_downgrade)]
-    ///
     /// use std::sync::{Arc, RwLock, RwLockWriteGuard};
     ///
     /// let rw = Arc::new(RwLock::new(1));
@@ -863,7 +859,7 @@ impl<'rwlock, T: ?Sized> RwLockWriteGuard<'rwlock, T> {
     /// # let final_check = rw.read().unwrap();
     /// # assert_eq!(*final_check, 3);
     /// ```
-    #[unstable(feature = "rwlock_downgrade", issue = "128203")]
+    #[stable(feature = "rwlock_downgrade", since = "CURRENT_RUSTC_VERSION")]
     pub fn downgrade(s: Self) -> RwLockReadGuard<'rwlock, T> {
         let lock = s.lock;
 

std/tests/sync/lib.rs

@@ -4,7 +4,6 @@
 #![feature(once_cell_try)]
 #![feature(lock_value_accessors)]
 #![feature(reentrant_lock)]
-#![feature(rwlock_downgrade)]
 #![feature(std_internals)]
 #![feature(sync_nonpoison)]
 #![feature(nonpoison_condvar)]