Add #[must_use] to conversions that move self

library/std/src/path.rs

@@ -532,6 +532,7 @@ impl<'a> Component<'a> {
     /// let components: Vec<_> = path.components().map(|comp| comp.as_os_str()).collect();
     /// assert_eq!(&components, &[".", "tmp", "foo", "bar.txt"]);
     /// ```
+    #[must_use = "`self` will be dropped if the result is not used"]
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn as_os_str(self) -> &'a OsStr {
         match self {
@@ -1428,6 +1429,7 @@ impl PathBuf {
     /// let os_str = p.into_os_string();
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[must_use = "`self` will be dropped if the result is not used"]
     #[inline]
     pub fn into_os_string(self) -> OsString {
         self.inner
@@ -1435,6 +1437,7 @@ impl PathBuf {
 
     /// Converts this `PathBuf` into a [boxed](Box) [`Path`].
     #[stable(feature = "into_boxed_path", since = "1.20.0")]
+    #[must_use = "`self` will be dropped if the result is not used"]
     #[inline]
     pub fn into_boxed_path(self) -> Box<Path> {
         let rw = Box::into_raw(self.inner.into_boxed_os_str()) as *mut Path;