Adjust doc comments

Author: Bastian Gruber

src/libstd/path.rs

@@ -1399,7 +1399,7 @@ impl<'a> From<&'a Path> for Box<Path> {
 impl From<Box<Path>> for PathBuf {
     /// Converts a `Box<Path>` into a `PathBuf`
     ///
-    /// This conversion does not allocate memory
+    /// This conversion does not allocate or copy memory.
     fn from(boxed: Box<Path>) -> PathBuf {
         boxed.into_path_buf()
     }
@@ -1409,7 +1409,8 @@ impl From<Box<Path>> for PathBuf {
 impl From<PathBuf> for Box<Path> {
     /// Converts a `PathBuf` into a `Box<Path>`
     ///
-    /// This conversion does not allocate memory
+    /// This conversion currently should not allocate memory, 
+    // but this behavior is not guaranteed on all platforms or in all future versions.
     fn from(p: PathBuf) -> Box<Path> {
         p.into_boxed_path()
     }
@@ -1434,7 +1435,7 @@ impl<'a, T: ?Sized + AsRef<OsStr>> From<&'a T> for PathBuf {
 impl From<OsString> for PathBuf {
     /// Converts a `OsString` into a `PathBuf`
     ///
-    /// This conversion does not allocate memory
+    /// This conversion does not allocate or copy memory.
     fn from(s: OsString) -> PathBuf {
         PathBuf { inner: s }
     }
@@ -1444,7 +1445,7 @@ impl From<OsString> for PathBuf {
 impl From<PathBuf> for OsString {
     /// Converts a `PathBuf` into a `OsString`
     ///
-    /// This conversion does not allocate memory
+    /// This conversion does not allocate or copy memory.
     fn from(path_buf : PathBuf) -> OsString {
         path_buf.inner
     }
@@ -1454,7 +1455,7 @@ impl From<PathBuf> for OsString {
 impl From<String> for PathBuf {
     /// Converts a `String` into a `PathBuf`
     ///
-    /// This conversion does not allocate memory
+    /// This conversion does not allocate or copy memory.
     fn from(s: String) -> PathBuf {
         PathBuf::from(OsString::from(s))
     }
@@ -1551,11 +1552,7 @@ impl<'a> From<Cow<'a, Path>> for PathBuf {
 
 #[stable(feature = "shared_from_slice2", since = "1.24.0")]
 impl From<PathBuf> for Arc<Path> {
-    /// Converts a `PathBuf` into a `Arc<Path>`
-    ///
-    /// This conversion happens in place
-    ///
-    /// This conversion does not allocate memory
+    /// Converts a Path into a Rc by copying the Path data into a new Rc buffer.
     #[inline]
     fn from(s: PathBuf) -> Arc<Path> {
         let arc: Arc<OsStr> = Arc::from(s.into_os_string());
@@ -1565,12 +1562,7 @@ impl From<PathBuf> for Arc<Path> {
 
 #[stable(feature = "shared_from_slice2", since = "1.24.0")]
 impl<'a> From<&'a Path> for Arc<Path> {
-    /// Converts a `PathBuf` into a `Arc<Path>`
-    ///
-    /// This conversion happens in place
-    ///
-    /// This conversion does not allocate memory
-    ///
+    /// Converts a Path into a Rc by copying the Path data into a new Rc buffer.
     #[inline]
     fn from(s: &Path) -> Arc<Path> {
         let arc: Arc<OsStr> = Arc::from(s.as_os_str());
@@ -1580,11 +1572,7 @@ impl<'a> From<&'a Path> for Arc<Path> {
 
 #[stable(feature = "shared_from_slice2", since = "1.24.0")]
 impl From<PathBuf> for Rc<Path> {
-    /// Converts a `PathBuf` into a `Rc<Path>`
-    ///
-    /// This conversion happens in place
-    ///
-    /// This conversion does not allocate memory
+    /// Converts a Path into a Rc by copying the Path data into a new Rc buffer.
     #[inline]
     fn from(s: PathBuf) -> Rc<Path> {
         let rc: Rc<OsStr> = Rc::from(s.into_os_string());
@@ -1594,6 +1582,7 @@ impl From<PathBuf> for Rc<Path> {
 
 #[stable(feature = "shared_from_slice2", since = "1.24.0")]
 impl<'a> From<&'a Path> for Rc<Path> {
+    /// Converts a Path into a Rc by copying the Path data into a new Rc buffer.
     #[inline]
     fn from(s: &Path) -> Rc<Path> {
         let rc: Rc<OsStr> = Rc::from(s.as_os_str());