Show appropriate feature flags in docs

Author: steveklabnik

src/doc/trpl/choosing-your-guarantees.md

@@ -127,7 +127,8 @@ If a field is wrapped in `Cell`, it's a nice indicator that the chunk of data is
 stay the same between the time you first read it and when you intend to use it.
 
 ```rust
-# use std::cell::Cell;
+use std::cell::Cell;
+
 let x = Cell::new(1);
 let y = &x;
 let z = &x;
@@ -185,7 +186,8 @@ any other borrows active when a mutable borrow is active. If the programmer atte
 borrow, the thread will panic.
 
 ```rust
-# use std::cell::RefCell;
+use std::cell::RefCell;
+
 let x = RefCell::new(vec![1,2,3,4]);
 {
     println!("{:?}", *x.borrow())

src/doc/trpl/intrinsics.md

@@ -11,7 +11,7 @@ perform efficient pointer arithmetic, one would import those functions
 via a declaration like
 
 ```rust
-# #![feature(intrinsics)]
+#![feature(intrinsics)]
 # fn main() {}
 
 extern "rust-intrinsic" {

src/liballoc/arc.rs

@@ -200,7 +200,8 @@ impl<T: ?Sized> Arc<T> {
     /// # Examples
     ///
     /// ```
-    /// # #![feature(arc_weak)]
+    /// #![feature(arc_weak)]
+    ///
     /// use std::sync::Arc;
     ///
     /// let five = Arc::new(5);
@@ -337,7 +338,8 @@ impl<T: Clone> Arc<T> {
     /// # Examples
     ///
     /// ```
-    /// # #![feature(arc_unique)]
+    /// #![feature(arc_unique)]
+    ///
     /// use std::sync::Arc;
     ///
     /// let mut five = Arc::new(5);
@@ -408,7 +410,8 @@ impl<T: ?Sized> Arc<T> {
     /// # Examples
     ///
     /// ```
-    /// # #![feature(arc_unique, alloc)]
+    /// #![feature(arc_unique, alloc)]
+    ///
     /// extern crate alloc;
     /// # fn main() {
     /// use alloc::arc::Arc;
@@ -555,7 +558,8 @@ impl<T: ?Sized> Weak<T> {
     /// # Examples
     ///
     /// ```
-    /// # #![feature(arc_weak)]
+    /// #![feature(arc_weak)]
+    ///
     /// use std::sync::Arc;
     ///
     /// let five = Arc::new(5);
@@ -599,7 +603,8 @@ impl<T: ?Sized> Clone for Weak<T> {
     /// # Examples
     ///
     /// ```
-    /// # #![feature(arc_weak)]
+    /// #![feature(arc_weak)]
+    ///
     /// use std::sync::Arc;
     ///
     /// let weak_five = Arc::new(5).downgrade();
@@ -626,7 +631,8 @@ impl<T: ?Sized> Drop for Weak<T> {
     /// # Examples
     ///
     /// ```
-    /// # #![feature(arc_weak)]
+    /// #![feature(arc_weak)]
+    ///
     /// use std::sync::Arc;
     ///
     /// {

src/liballoc/boxed.rs

@@ -74,7 +74,8 @@ use core::raw::{TraitObject};
 /// The following two examples are equivalent:
 ///
 /// ```
-/// # #![feature(box_heap)]
+/// #![feature(box_heap)]
+///
 /// #![feature(box_syntax, placement_in_syntax)]
 /// use std::boxed::HEAP;
 ///
@@ -237,7 +238,8 @@ impl<T : ?Sized> Box<T> {
     ///
     /// # Examples
     /// ```
-    /// # #![feature(box_raw)]
+    /// #![feature(box_raw)]
+    ///
     /// let seventeen = Box::new(17u32);
     /// let raw = Box::into_raw(seventeen);
     /// let boxed_again = unsafe { Box::from_raw(raw) };
@@ -260,7 +262,8 @@ impl<T : ?Sized> Box<T> {
 ///
 /// # Examples
 /// ```
-/// # #![feature(box_raw)]
+/// #![feature(box_raw)]
+///
 /// use std::boxed;
 ///
 /// let seventeen = Box::new(17u32);
@@ -303,7 +306,8 @@ impl<T: Clone> Clone for Box<T> {
     /// # Examples
     ///
     /// ```
-    /// # #![feature(box_raw)]
+    /// #![feature(box_raw)]
+    ///
     /// let x = Box::new(5);
     /// let mut y = Box::new(10);
     ///

src/liballoc/rc.rs

@@ -91,7 +91,8 @@
 //! documentation for more details on interior mutability.
 //!
 //! ```rust
-//! # #![feature(rc_weak)]
+//! #![feature(rc_weak)]
+//!
 //! use std::rc::Rc;
 //! use std::rc::Weak;
 //! use std::cell::RefCell;
@@ -227,7 +228,8 @@ impl<T> Rc<T> {
     /// # Examples
     ///
     /// ```
-    /// # #![feature(rc_unique)]
+    /// #![feature(rc_unique)]
+    ///
     /// use std::rc::Rc;
     ///
     /// let x = Rc::new(3);
@@ -262,7 +264,8 @@ impl<T: ?Sized> Rc<T> {
     /// # Examples
     ///
     /// ```
-    /// # #![feature(rc_weak)]
+    /// #![feature(rc_weak)]
+    ///
     /// use std::rc::Rc;
     ///
     /// let five = Rc::new(5);
@@ -292,7 +295,8 @@ impl<T: ?Sized> Rc<T> {
     /// # Examples
     ///
     /// ```
-    /// # #![feature(rc_unique)]
+    /// #![feature(rc_unique)]
+    ///
     /// use std::rc::Rc;
     ///
     /// let five = Rc::new(5);
@@ -313,7 +317,8 @@ impl<T: ?Sized> Rc<T> {
     /// # Examples
     ///
     /// ```
-    /// # #![feature(rc_unique)]
+    /// #![feature(rc_unique)]
+    ///
     /// use std::rc::Rc;
     ///
     /// let mut x = Rc::new(3);
@@ -353,7 +358,8 @@ pub fn strong_count<T: ?Sized>(this: &Rc<T>) -> usize { Rc::strong_count(this) }
 /// # Examples
 ///
 /// ```
-/// # #![feature(rc_unique)]
+/// #![feature(rc_unique)]
+///
 /// use std::rc;
 /// use std::rc::Rc;
 ///
@@ -373,7 +379,8 @@ pub fn is_unique<T>(rc: &Rc<T>) -> bool { Rc::is_unique(rc) }
 /// # Examples
 ///
 /// ```
-/// # #![feature(rc_unique)]
+/// #![feature(rc_unique)]
+///
 /// use std::rc::{self, Rc};
 ///
 /// let x = Rc::new(3);
@@ -395,7 +402,8 @@ pub fn try_unwrap<T>(rc: Rc<T>) -> Result<T, Rc<T>> { Rc::try_unwrap(rc) }
 /// # Examples
 ///
 /// ```
-/// # #![feature(rc_unique)]
+/// #![feature(rc_unique)]
+///
 /// use std::rc::{self, Rc};
 ///
 /// let mut x = Rc::new(3);
@@ -419,7 +427,8 @@ impl<T: Clone> Rc<T> {
     /// # Examples
     ///
     /// ```
-    /// # #![feature(rc_unique)]
+    /// #![feature(rc_unique)]
+    ///
     /// use std::rc::Rc;
     ///
     /// let mut five = Rc::new(5);
@@ -750,7 +759,8 @@ impl<T: ?Sized> Weak<T> {
     /// # Examples
     ///
     /// ```
-    /// # #![feature(rc_weak)]
+    /// #![feature(rc_weak)]
+    ///
     /// use std::rc::Rc;
     ///
     /// let five = Rc::new(5);
@@ -778,7 +788,8 @@ impl<T: ?Sized> Drop for Weak<T> {
     /// # Examples
     ///
     /// ```
-    /// # #![feature(rc_weak)]
+    /// #![feature(rc_weak)]
+    ///
     /// use std::rc::Rc;
     ///
     /// {
@@ -825,7 +836,8 @@ impl<T: ?Sized> Clone for Weak<T> {
     /// # Examples
     ///
     /// ```
-    /// # #![feature(rc_weak)]
+    /// #![feature(rc_weak)]
+    ///
     /// use std::rc::Rc;
     ///
     /// let weak_five = Rc::new(5).downgrade();

src/libcollections/binary_heap.rs

@@ -216,7 +216,8 @@ impl<T: Ord> BinaryHeap<T> {
     /// # Examples
     ///
     /// ```
-    /// # #![feature(collections)]
+    /// #![feature(collections)]
+    ///
     /// use std::collections::BinaryHeap;
     /// let heap = BinaryHeap::from_vec(vec![9, 1, 2, 7, 3, 2]);
     /// ```
@@ -236,7 +237,8 @@ impl<T: Ord> BinaryHeap<T> {
     /// # Examples
     ///
     /// ```
-    /// # #![feature(collections)]
+    /// #![feature(collections)]
+    ///
     /// use std::collections::BinaryHeap;
     /// let heap = BinaryHeap::from_vec(vec![1, 2, 3, 4]);
     ///
@@ -341,7 +343,8 @@ impl<T: Ord> BinaryHeap<T> {
     /// # Examples
     ///
     /// ```
-    /// # #![feature(collections)]
+    /// #![feature(collections)]
+    ///
     /// use std::collections::BinaryHeap;
     /// let mut heap = BinaryHeap::from_vec(vec![1, 3]);
     ///
@@ -387,7 +390,8 @@ impl<T: Ord> BinaryHeap<T> {
     /// # Examples
     ///
     /// ```
-    /// # #![feature(collections)]
+    /// #![feature(collections)]
+    ///
     /// use std::collections::BinaryHeap;
     /// let mut heap = BinaryHeap::new();
     /// heap.push(1);
@@ -419,7 +423,8 @@ impl<T: Ord> BinaryHeap<T> {
     /// # Examples
     ///
     /// ```
-    /// # #![feature(collections)]
+    /// #![feature(collections)]
+    ///
     /// use std::collections::BinaryHeap;
     /// let mut heap = BinaryHeap::new();
     ///
@@ -445,7 +450,8 @@ impl<T: Ord> BinaryHeap<T> {
     /// # Examples
     ///
     /// ```
-    /// # #![feature(collections)]
+    /// #![feature(collections)]
+    ///
     /// use std::collections::BinaryHeap;
     /// let heap = BinaryHeap::from_vec(vec![1, 2, 3, 4, 5, 6, 7]);
     /// let vec = heap.into_vec();
@@ -463,7 +469,8 @@ impl<T: Ord> BinaryHeap<T> {
     /// # Examples
     ///
     /// ```
-    /// # #![feature(collections)]
+    /// #![feature(collections)]
+    ///
     /// use std::collections::BinaryHeap;
     ///
     /// let mut heap = BinaryHeap::from_vec(vec![1, 2, 4, 5, 7]);
@@ -724,7 +731,8 @@ impl<T: Ord> IntoIterator for BinaryHeap<T> {
     /// # Examples
     ///
     /// ```
-    /// # #![feature(collections)]
+    /// #![feature(collections)]
+    ///
     /// use std::collections::BinaryHeap;
     /// let heap = BinaryHeap::from_vec(vec![1, 2, 3, 4]);
     ///