Auto merge of #31416 - steveklabnik:rollup, r=steveklabnik

- Successful merges: #31007, #31396, #31401, #31411, #31412, #31413, #31415
- Failed merges:

2 files changed, 24 insertions, 3 deletions

diff --git a/src/libstd/ascii.rs b/src/libstd/ascii.rs
index b6123264ea8..38f79079b29 100644
--- a/src/libstd/ascii.rs
+++ b/src/libstd/ascii.rs
@@ -18,6 +18,27 @@ use mem;
 use ops::Range;
 
 /// Extension methods for ASCII-subset only operations on string slices.
+///
+/// Be aware that operations on seemingly non-ASCII characters can sometimes
+/// have unexpected results. Consider this example:
+///
+/// ```
+/// use std::ascii::AsciiExt;
+///
+/// assert_eq!("café".to_ascii_uppercase(), "CAFÉ");
+/// assert_eq!("café".to_ascii_uppercase(), "CAFé");
+/// ```
+///
+/// In the first example, the lowercased string is represented `"cafe\u{301}"`
+/// (the last character is an acute accent [combining character]). Unlike the
+/// other characters in the string, the combining character will not get mapped
+/// to an uppercase variant, resulting in `"CAFE\u{301}"`. In the second
+/// example, the lowercased string is represented `"caf\u{e9}"` (the last
+/// character is a single Unicode character representing an 'e' with an acute
+/// accent). Since the last character is defined outside the scope of ASCII,
+/// it will not get mapped to an uppercase variant, resulting in `"CAF\u{e9}"`.
+///
+/// [combining character]: https://en.wikipedia.org/wiki/Combining_character
 #[stable(feature = "rust1", since = "1.0.0")]
 pub trait AsciiExt {
     /// Container type for copied ASCII characters.
diff --git a/src/libstd/collections/hash/map.rs b/src/libstd/collections/hash/map.rs
index 7ce4aa07b50..f8efada9f6c 100644
--- a/src/libstd/collections/hash/map.rs
+++ b/src/libstd/collections/hash/map.rs
@@ -282,9 +282,9 @@ fn test_resize_policy() {
 /// let mut player_stats = HashMap::new();
 ///
 /// fn random_stat_buff() -> u8 {
-///   // could actually return some random value here - let's just return
-///   // some fixed value for now
-///   42
+///     // could actually return some random value here - let's just return
+///     // some fixed value for now
+///     42
 /// }
 ///
 /// // insert a key only if it doesn't already exist