Auto merge of #84501 - JohnTitor:rollup-wxu1thu, r=JohnTitor

Rollup of 10 pull requests

Successful merges:

 - #83990 (implement `TrustedRandomAccess` for `Take` iterator adapter)
 - #84250 (bootstrap: use bash on illumos to run install scripts)
 - #84320 (Use details tag for trait implementors.)
 - #84436 (Make a few functions private)
 - #84453 (Document From implementations for Waker and RawWaker)
 - #84458 (Remove unnecessary fields and parameters in rustdoc)
 - #84485 (Add some associated type bounds tests)
 - #84489 (Mention FusedIterator case in Iterator::fuse doc)
 - #84492 (rustdoc: Remove unnecessary dummy span)
 - #84496 (Add some specialization tests)

Failed merges:

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

3 files changed, 33 insertions, 1 deletions

diff --git a/library/alloc/src/task.rs b/library/alloc/src/task.rs
index 58a9ae77244..528ee4ff154 100644
--- a/library/alloc/src/task.rs
+++ b/library/alloc/src/task.rs
@@ -87,6 +87,9 @@ pub trait Wake {
 
 #[stable(feature = "wake_trait", since = "1.51.0")]
 impl<W: Wake + Send + Sync + 'static> From<Arc<W>> for Waker {
+    /// Use a `Wake`-able type as a `Waker`.
+    ///
+    /// No heap allocations or atomic operations are used for this conversion.
     fn from(waker: Arc<W>) -> Waker {
         // SAFETY: This is safe because raw_waker safely constructs
         // a RawWaker from Arc<W>.
@@ -96,6 +99,9 @@ impl<W: Wake + Send + Sync + 'static> From<Arc<W>> for Waker {
 
 #[stable(feature = "wake_trait", since = "1.51.0")]
 impl<W: Wake + Send + Sync + 'static> From<Arc<W>> for RawWaker {
+    /// Use a `Wake`-able type as a `RawWaker`.
+    ///
+    /// No heap allocations or atomic operations are used for this conversion.
     fn from(waker: Arc<W>) -> RawWaker {
         raw_waker(waker)
     }
diff --git a/library/core/src/iter/adapters/take.rs b/library/core/src/iter/adapters/take.rs
index 9efc7a480ae..54a47f1323e 100644
--- a/library/core/src/iter/adapters/take.rs
+++ b/library/core/src/iter/adapters/take.rs
@@ -1,5 +1,8 @@
 use crate::cmp;
-use crate::iter::{adapters::SourceIter, FusedIterator, InPlaceIterable, TrustedLen};
+use crate::iter::{
+    adapters::zip::try_get_unchecked, adapters::SourceIter, FusedIterator, InPlaceIterable,
+    TrustedLen, TrustedRandomAccess,
+};
 use crate::ops::{ControlFlow, Try};
 
 /// An iterator that only iterates over the first `n` iterations of `iter`.
@@ -111,6 +114,15 @@ where
 
         self.try_fold(init, ok(fold)).unwrap()
     }
+
+    unsafe fn __iterator_get_unchecked(&mut self, idx: usize) -> <I as Iterator>::Item
+    where
+        Self: TrustedRandomAccess,
+    {
+        // SAFETY: the caller must uphold the contract for
+        // `Iterator::__iterator_get_unchecked`.
+        unsafe { try_get_unchecked(&mut self.iter, idx) }
+    }
 }
 
 #[unstable(issue = "none", feature = "inplace_iteration")]
@@ -207,3 +219,12 @@ impl<I> FusedIterator for Take<I> where I: FusedIterator {}
 
 #[unstable(feature = "trusted_len", issue = "37572")]
 unsafe impl<I: TrustedLen> TrustedLen for Take<I> {}
+
+#[doc(hidden)]
+#[unstable(feature = "trusted_random_access", issue = "none")]
+unsafe impl<I> TrustedRandomAccess for Take<I>
+where
+    I: TrustedRandomAccess,
+{
+    const MAY_HAVE_SIDE_EFFECT: bool = I::MAY_HAVE_SIDE_EFFECT;
+}
diff --git a/library/core/src/iter/traits/iterator.rs b/library/core/src/iter/traits/iterator.rs
index 9b0f9544f8e..7977d599ae7 100644
--- a/library/core/src/iter/traits/iterator.rs
+++ b/library/core/src/iter/traits/iterator.rs
@@ -1495,7 +1495,12 @@ pub trait Iterator {
     /// [`Some(T)`] again. `fuse()` adapts an iterator, ensuring that after a
     /// [`None`] is given, it will always return [`None`] forever.
     ///
+    /// Note that the [`Fuse`] wrapper is a no-op on iterators that implement
+    /// the [`FusedIterator`] trait. `fuse()` may therefore behave incorrectly
+    /// if the [`FusedIterator`] trait is improperly implemented.
+    ///
     /// [`Some(T)`]: Some
+    /// [`FusedIterator`]: crate::iter::FusedIterator
     ///
     /// # Examples
     ///