Fix doctests

src/libstd/fs.rs

@@ -515,6 +515,7 @@ impl OpenOptions {
     /// # Examples
     ///
     /// ```no_run
+    /// #![feature(expand_open_options)]
     /// use std::fs::OpenOptions;
     ///
     /// let file = OpenOptions::new().write(true).create_new(true).open("foo.txt");

src/libstd/sys/unix/ext/fs.rs

@@ -114,12 +114,13 @@ pub trait OpenOptionsExt {
     ///
     /// # Examples
     ///
-    /// ```no_run
+    /// ```rust,ignore
     /// extern crate libc;
     /// use std::fs::OpenOptions;
     /// use std::os::unix::fs::OpenOptionsExt;
     ///
-    /// let options = OpenOptions::new().write(true);
+    /// let mut options = OpenOptions::new();
+    /// options.write(true);
     /// if cfg!(unix) { options.custom_flags(libc::O_NOFOLLOW); }
     /// let file = options.open("foo.txt");
     /// ```

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

@@ -77,7 +77,8 @@ pub trait OpenOptionsExt {
     /// use std::fs::OpenOptions;
     /// use std::os::windows::fs::OpenOptionsExt;
     ///
-    /// let options = OpenOptions::new().create(true).write(true);
+    /// let mut options = OpenOptions::new();
+    /// options.create(true).write(true);
     /// if cfg!(windows) { options.custom_flags(winapi::FILE_FLAG_DELETE_ON_CLOSE); }
     /// let file = options.open("foo.txt");
     /// ```