1 files changed, 10 insertions, 4 deletions
diff --git a/library/alloc/src/string.rs b/library/alloc/src/string.rs
index f11fa92766f..85ee7ea9438 100644
--- a/library/alloc/src/string.rs
+++ b/library/alloc/src/string.rs
@@ -803,6 +803,7 @@ impl String {
     /// assert_eq!("foo", s.as_str());
     /// ```
     #[inline]
+    #[must_use]
     #[stable(feature = "string_as_str", since = "1.7.0")]
     pub fn as_str(&self) -> &str {
         self
@@ -823,6 +824,7 @@ impl String {
     /// assert_eq!("FOOBAR", s_mut_str);
     /// ```
     #[inline]
+    #[must_use]
     #[stable(feature = "string_as_str", since = "1.7.0")]
     pub fn as_mut_str(&mut self) -> &mut str {
         self
@@ -1163,6 +1165,7 @@ impl String {
     /// assert_eq!(&[104, 101, 108, 108, 111], s.as_bytes());
     /// ```
     #[inline]
+    #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn as_bytes(&self) -> &[u8] {
         &self.vec
@@ -1497,10 +1500,11 @@ impl String {
     ///
     /// # Safety
     ///
-    /// This function is unsafe because it does not check that the bytes passed
-    /// to it are valid UTF-8. If this constraint is violated, it may cause
-    /// memory unsafety issues with future users of the `String`, as the rest of
-    /// the standard library assumes that `String`s are valid UTF-8.
+    /// This function is unsafe because the returned `&mut Vec` allows writing
+    /// bytes which are not valid UTF-8. If this constraint is violated, using
+    /// the original `String` after dropping the `&mut Vec` may violate memory
+    /// safety, as the rest of the standard library assumes that `String`s are
+    /// valid UTF-8.
     ///
     /// # Examples
     ///
@@ -1766,6 +1770,7 @@ impl FromUtf8Error {
     ///
     /// assert_eq!(&[0, 159], value.unwrap_err().as_bytes());
     /// ```
+    #[must_use]
     #[stable(feature = "from_utf8_error_as_bytes", since = "1.26.0")]
     pub fn as_bytes(&self) -> &[u8] {
         &self.bytes[..]
@@ -2782,6 +2787,7 @@ impl<'a> Drain<'a> {
     /// let _ = drain.next().unwrap();
     /// assert_eq!(drain.as_str(), "bc");
     /// ```
+    #[must_use]
     #[stable(feature = "string_drain_as_str", since = "1.55.0")]
     pub fn as_str(&self) -> &str {
         self.iter.as_str()