Update documention in windows::ffi

src/libstd/sys/windows/ext/ffi.rs

@@ -26,8 +26,22 @@ pub trait OsStringExt {
     /// Creates an `OsString` from a potentially ill-formed UTF-16 slice of
     /// 16-bit code units.
     ///
-    /// This is lossless: calling `.encode_wide()` on the resulting string
+    /// This is lossless: calling [`encode_wide()`] on the resulting string
     /// will always return the original code units.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::ffi::OsString;
+    /// use std::os::windows::prelude::*;
+    ///
+    /// // UTF-16 encoding for "Unicode".
+    /// let source = [0x0055, 0x006E, 0x0069, 0x0063, 0x006F, 0x0064, 0x0065];
+    ///
+    /// let string = OsString::from_wide(&source[..]);
+    /// ```
+    ///
+    /// [`encode_wide()`]: ./trait.OsStrExt.html#tymethod.encode_wide
     #[stable(feature = "rust1", since = "1.0.0")]
     fn from_wide(wide: &[u16]) -> Self;
 }
@@ -42,11 +56,29 @@ impl OsStringExt for OsString {
 /// Windows-specific extensions to `OsStr`.
 #[stable(feature = "rust1", since = "1.0.0")]
 pub trait OsStrExt {
-    /// Re-encodes an `OsStr` as a wide character sequence,
-    /// i.e. potentially ill-formed UTF-16.
+    /// Re-encodes an `OsStr` as a wide character sequence, i.e. potentially
+    /// ill-formed UTF-16.
     ///
-    /// This is lossless. Note that the encoding does not include a final
-    /// null.
+    /// This is lossless: calling [`OsString::from_wide()`] and then
+    /// `encode_wide()` on the result will yield the original code units.
+    /// Note that the encoding does not add a final null terminator.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::ffi::OsString;
+    /// use std::os::windows::prelude::*;
+    ///
+    /// // UTF-16 encoding for "Unicode".
+    /// let source = [0x0055, 0x006E, 0x0069, 0x0063, 0x006F, 0x0064, 0x0065];
+    ///
+    /// let string = OsString::from_wide(&source[..]);
+    ///
+    /// let result: Vec<u16> = string.encode_wide().collect();
+    /// assert_eq!(&source[..], &result[..]);
+    /// ```
+    ///
+    /// [`OsString::from_wide()`]: ./trait.OsStringExt.html#tymethod.from_wide
     #[stable(feature = "rust1", since = "1.0.0")]
     fn encode_wide(&self) -> EncodeWide;
 }

src/libstd/sys/windows/ext/mod.rs

@@ -8,11 +8,13 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-//! Experimental extensions to `std` for Windows.
+//! Platform-specific extensions to `std` for Windows.
 //!
-//! For now, this module is limited to extracting handles, file
-//! descriptors, and sockets, but its functionality will grow over
-//! time.
+//! Provides access to platform-level information for Windows, and exposes
+//! Windows-specific idioms that would otherwise be inappropriate as part
+//! the core `std` library. These extensions allow developers to use
+//! `std` types and idioms with Windows in a way that the noraml
+//! platform-agnostic idioms would not normally support.
 
 #![stable(feature = "rust1", since = "1.0.0")]
 

src/libstd/sys_common/wtf8.rs

@@ -750,6 +750,7 @@ impl<'a> Iterator for Wtf8CodePoints<'a> {
     }
 }
 
+/// Generates a wide character sequence for potentially ill-formed UTF-16.
 #[stable(feature = "rust1", since = "1.0.0")]
 #[derive(Clone)]
 pub struct EncodeWide<'a> {