doc comments

Author: tnuha

library/std/src/ffi/os_str.rs

@@ -566,6 +566,9 @@ impl OsString {
         self.inner.truncate(len);
     }
 
+    /// More well behaving alternative to allowing outer types
+    /// full mutable access to the core `Vec`.
+    /// Provides plumbing to core `Vec::extend_from_slice`.
     #[inline]
     pub(crate) fn extend_from_slice(&mut self, other: &[u8]) {
         self.inner.extend_from_slice(other);

library/std/src/sys/os_str/bytes.rs

@@ -216,6 +216,9 @@ impl Buf {
         self.inner.truncate(len);
     }
 
+    /// More well behaving alternative to allowing outer types
+    /// full mutable access to the core `Vec`.
+    /// Provides plumbing to core `Vec::extend_from_slice`.
     #[inline]
     pub(crate) fn extend_from_slice(&mut self, other: &[u8]) {
         self.inner.extend_from_slice(other);