Rollup merge of rust-lang#85730 - Smittyvb:iter-min-max-floats, r=m-ou-se

Mention workaround for floats in Iterator::{min, max}

`Iterator::{min, max}` can't be used with iterators of floats due to NaN issues. This suggests a workaround in the documentation of those functions.

Author: GuillaumeGomez

library/core/src/iter/traits/iterator.rs

@@ -2568,6 +2568,18 @@ pub trait Iterator {
     /// If several elements are equally maximum, the last element is
     /// returned. If the iterator is empty, [`None`] is returned.
     ///
+    /// Note that [`f32`]/[`f64`] doesn't implement [`Ord`] due to NaN being
+    /// incomparable. You can work around this by using [`Iterator::reduce`]:
+    /// ```
+    /// assert_eq!(
+    ///     vec![2.4, f32::NAN, 1.3]
+    ///         .into_iter()
+    ///         .reduce(f32::max)
+    ///         .unwrap(),
+    ///     2.4
+    /// );
+    /// ```
+    ///
     /// # Examples
     ///
     /// Basic usage:
@@ -2591,8 +2603,20 @@ pub trait Iterator {
 
     /// Returns the minimum element of an iterator.
     ///
-    /// If several elements are equally minimum, the first element is
-    /// returned. If the iterator is empty, [`None`] is returned.
+    /// If several elements are equally minimum, the first element is returned.
+    /// If the iterator is empty, [`None`] is returned.
+    ///
+    /// Note that [`f32`]/[`f64`] doesn't implement [`Ord`] due to NaN being
+    /// incomparable. You can work around this by using [`Iterator::reduce`]:
+    /// ```
+    /// assert_eq!(
+    ///     vec![2.4, f32::NAN, 1.3]
+    ///         .into_iter()
+    ///         .reduce(f32::min)
+    ///         .unwrap(),
+    ///     1.3
+    /// );
+    /// ```
     ///
     /// # Examples
     ///