Rollup merge of rust-lang#76302 - jyn514:peekable-2, r=Dylan-DPC

Address review comments on `Peekable::next_if`

r? @pickfire
See rust-lang#72310 (review) for context.

library/core/src/iter/adapters/mod.rs

@@ -1772,7 +1772,7 @@ impl<I: Iterator> Peekable<I> {
  self.peeked.get_or_insert_with(|| iter.next()).as_ref()
  }
 
- /// Consume the next value of this iterator if a condition is true.
+ /// Consume and return the next value of this iterator if a condition is true.
  ///
  /// If `func` returns `true` for the next value of this iterator, consume and return it.
  /// Otherwise, return `None`.
@@ -1812,7 +1812,7 @@ impl<I: Iterator> Peekable<I> {
  }
  }
 
- /// Consume the next item if it is equal to `expected`.
+ /// Consume and return the next item if it is equal to `expected`.
  ///
  /// # Example
  /// Consume a number if it's equal to 0.
@@ -1827,10 +1827,10 @@ impl<I: Iterator> Peekable<I> {
  /// assert_eq!(iter.next(), Some(1));
  /// ```
  #[unstable(feature = "peekable_next_if", issue = "72480")]
- pub fn next_if_eq<R>(&mut self, expected: &R) -> Option<I::Item>
+ pub fn next_if_eq<T>(&mut self, expected: &T) -> Option<I::Item>
  where
- R: ?Sized,
- I::Item: PartialEq<R>,
+ T: ?Sized,
+ I::Item: PartialEq<T>,
  {
  self.next_if(|next| next == expected)
  }