diff --git a/src/doc/book/references-and-borrowing.md b/src/doc/book/references-and-borrowing.md
index 57bfbce8b84debab2f26a638ae1aed85ecc491ed..2ec3a00c0df516ab73db23926639712697c0cd50 100644
--- a/src/doc/book/references-and-borrowing.md
+++ b/src/doc/book/references-and-borrowing.md
@@ -152,7 +152,7 @@ the thing `y` points at. You’ll notice that `x` had to be marked `mut` as well
 If it wasn’t, we couldn’t take a mutable borrow to an immutable value.
 
 You'll also notice we added an asterisk (`*`) in front of `y`, making it `*y`,
-this is because `y` is a `&mut` reference. You'll need to use astrisks to
+this is because `y` is a `&mut` reference. You'll need to use asterisks to
 access the contents of a reference as well.
 
 Otherwise, `&mut` references are like references. There _is_ a large
diff --git a/src/libcore/intrinsics.rs b/src/libcore/intrinsics.rs
index 8271b85b01a3b93553403fb45f6c096256a1cf79..06b506ab014b4e77b1c09643fb17a204c486f5da 100644
--- a/src/libcore/intrinsics.rs
+++ b/src/libcore/intrinsics.rs
@@ -262,22 +262,25 @@
     /// Moves a value out of scope without running drop glue.
     pub fn forget<T>(_: T) -> ();
 
-    /// Reinterprets the bits of a value of one type as another type; both types
-    /// must have the same size. Neither the original, nor the result, may be an
-    /// [invalid value] (../../nomicon/meet-safe-and-unsafe.html).
+    /// Reinterprets the bits of a value of one type as another type.
+    ///
+    /// Both types must have the same size. Neither the original, nor the result,
+    /// may be an [invalid value](../../nomicon/meet-safe-and-unsafe.html).
     ///
     /// `transmute` is semantically equivalent to a bitwise move of one type
-    /// into another. It copies the bits from the destination type into the
-    /// source type, then forgets the original. It's equivalent to C's `memcpy`
-    /// under the hood, just like `transmute_copy`.
+    /// into another. It copies the bits from the source value into the
+    /// destination value, then forgets the original. It's equivalent to C's
+    /// `memcpy` under the hood, just like `transmute_copy`.
     ///
-    /// `transmute` is incredibly unsafe. There are a vast number of ways to
-    /// cause undefined behavior with this function. `transmute` should be
+    /// `transmute` is **incredibly** unsafe. There are a vast number of ways to
+    /// cause [undefined behavior][ub] with this function. `transmute` should be
     /// the absolute last resort.
     ///
     /// The [nomicon](../../nomicon/transmutes.html) has additional
     /// documentation.
     ///
+    /// [ub]: ../../reference.html#behavior-considered-undefined
+    ///
     /// # Examples
     ///
     /// There are a few things that `transmute` is really useful for.
@@ -292,7 +295,8 @@
     /// assert_eq!(bitpattern, 0x3F800000);
     /// ```
     ///
-    /// Turning a pointer into a function pointer:
+    /// Turning a pointer into a function pointer. This is *not* portable to
+    /// machines where function pointers and data pointers have different sizes.
     ///
     /// ```
     /// fn foo() -> i32 {
@@ -305,8 +309,8 @@
     /// assert_eq!(function(), 0);
     /// ```
     ///
-    /// Extending a lifetime, or shortening an invariant lifetime; this is
-    /// advanced, very unsafe rust:
+    /// Extending a lifetime, or shortening an invariant lifetime. This is
+    /// advanced, very unsafe Rust!
     ///
     /// ```
     /// struct R<'a>(&'a i32);
@@ -322,11 +326,9 @@
     ///
     /// # Alternatives
     ///
-    /// However, many uses of `transmute` can be achieved through other means.
-    /// `transmute` can transform any type into any other, with just the caveat
-    /// that they're the same size, and often interesting results occur. Below
-    /// are common applications of `transmute` which can be replaced with safe
-    /// applications of `as`:
+    /// Don't despair: many uses of `transmute` can be achieved through other means.
+    /// Below are common applications of `transmute` which can be replaced with safer
+    /// constructs.
     ///
     /// Turning a pointer into a `usize`:
     ///
@@ -335,6 +337,7 @@
     /// let ptr_num_transmute = unsafe {
     ///     std::mem::transmute::<&i32, usize>(ptr)
     /// };
+    ///
     /// // Use an `as` cast instead
     /// let ptr_num_cast = ptr as *const i32 as usize;
     /// ```
@@ -346,6 +349,7 @@
     /// let ref_transmuted = unsafe {
     ///     std::mem::transmute::<*mut i32, &mut i32>(ptr)
     /// };
+    ///
     /// // Use a reborrow instead
     /// let ref_casted = unsafe { &mut *ptr };
     /// ```
@@ -357,6 +361,7 @@
     /// let val_transmuted = unsafe {
     ///     std::mem::transmute::<&mut i32, &mut u32>(ptr)
     /// };
+    ///
     /// // Now, put together `as` and reborrowing - note the chaining of `as`
     /// // `as` is not transitive
     /// let val_casts = unsafe { &mut *(ptr as *mut i32 as *mut u32) };
@@ -368,9 +373,11 @@
     /// // this is not a good way to do this.
     /// let slice = unsafe { std::mem::transmute::<&str, &[u8]>("Rust") };
     /// assert_eq!(slice, &[82, 117, 115, 116]);
+    ///
     /// // You could use `str::as_bytes`
     /// let slice = "Rust".as_bytes();
     /// assert_eq!(slice, &[82, 117, 115, 116]);
+    ///
     /// // Or, just use a byte string, if you have control over the string
     /// // literal
     /// assert_eq!(b"Rust", &[82, 117, 115, 116]);
@@ -381,18 +388,21 @@
     /// ```
     /// let store = [0, 1, 2, 3];
     /// let mut v_orig = store.iter().collect::<Vec<&i32>>();
+    ///
     /// // Using transmute: this is Undefined Behavior, and a bad idea.
     /// // However, it is no-copy.
     /// let v_transmuted = unsafe {
     ///     std::mem::transmute::<Vec<&i32>, Vec<Option<&i32>>>(
     ///         v_orig.clone())
     /// };
+    ///
     /// // This is the suggested, safe way.
-    /// // It does copy the entire Vector, though, into a new array.
+    /// // It does copy the entire vector, though, into a new array.
     /// let v_collected = v_orig.clone()
     ///                         .into_iter()
     ///                         .map(|r| Some(r))
     ///                         .collect::<Vec<Option<&i32>>>();
+    ///
     /// // The no-copy, unsafe way, still using transmute, but not UB.
     /// // This is equivalent to the original, but safer, and reuses the
     /// // same Vec internals. Therefore the new inner type must have the
@@ -412,6 +422,7 @@
     ///
     /// ```
     /// use std::{slice, mem};
+    ///
     /// // There are multiple ways to do this; and there are multiple problems
     /// // with the following, transmute, way.
     /// fn split_at_mut_transmute<T>(slice: &mut [T], mid: usize)
@@ -426,6 +437,7 @@
     ///         (&mut slice[0..mid], &mut slice2[mid..len])
     ///     }
     /// }
+    ///
     /// // This gets rid of the typesafety problems; `&mut *` will *only* give
     /// // you an `&mut T` from an `&mut T` or `*mut T`.
     /// fn split_at_mut_casts<T>(slice: &mut [T], mid: usize)
@@ -439,6 +451,7 @@
     ///         (&mut slice[0..mid], &mut slice2[mid..len])
     ///     }
     /// }
+    ///
     /// // This is how the standard library does it. This is the best method, if
     /// // you need to do something like this
     /// fn split_at_stdlib<T>(slice: &mut [T], mid: usize)
diff --git a/src/libcore/mem.rs b/src/libcore/mem.rs
index 9c61f76ac8895b9e8817447030606e8b5d1da6e3..d3b8a60b79776c3f00a304e3430f006b1a4abc59 100644
--- a/src/libcore/mem.rs
+++ b/src/libcore/mem.rs
@@ -21,54 +21,39 @@
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use intrinsics::transmute;
 
-/// Leaks a value into the void, consuming ownership and never running its
-/// destructor.
+/// Leaks a value: takes ownership and "forgets" about the value **without running
+/// its destructor**.
 ///
-/// This function will take ownership of its argument, but is distinct from the
-/// `mem::drop` function in that it **does not run the destructor**, leaking the
-/// value and any resources that it owns.
+/// Any resources the value manages, such as heap memory or a file handle, will linger
+/// forever in an unreachable state.
 ///
-/// There's only a few reasons to use this function. They mainly come
-/// up in unsafe code or FFI code.
-///
-/// * You have an uninitialized value, perhaps for performance reasons, and
-///   need to prevent the destructor from running on it.
-/// * You have two copies of a value (like when writing something like
-///   [`mem::swap`][swap]), but need the destructor to only run once to
-///   prevent a double `free`.
-/// * Transferring resources across [FFI][ffi] boundaries.
-///
-/// [swap]: fn.swap.html
-/// [ffi]: ../../book/ffi.html
+/// If you want to dispose of a value properly, running its destructor, see
+/// [`mem::drop`][drop].
 ///
 /// # Safety
 ///
-/// This function is not marked as `unsafe` as Rust does not guarantee that the
-/// `Drop` implementation for a value will always run. Note, however, that
-/// leaking resources such as memory or I/O objects is likely not desired, so
-/// this function is only recommended for specialized use cases.
-///
-/// The safety of this function implies that when writing `unsafe` code
-/// yourself care must be taken when leveraging a destructor that is required to
-/// run to preserve memory safety. There are known situations where the
-/// destructor may not run (such as if ownership of the object with the
-/// destructor is returned) which must be taken into account.
+/// `forget` is not marked as `unsafe`, because Rust's safety guarantees
+/// do not include a guarantee that destructors will always run. For example,
+/// a program can create a reference cycle using [`Rc`][rc], or call
+/// [`process:exit`][exit] to exit without running destructors. Thus, allowing
+/// `mem::forget` from safe code does not fundamentally change Rust's safety
+/// guarantees.
 ///
-/// # Other forms of Leakage
+/// That said, leaking resources such as memory or I/O objects is usually undesirable,
+/// so `forget` is only recommended for specialized use cases like those shown below.
 ///
-/// It's important to point out that this function is not the only method by
-/// which a value can be leaked in safe Rust code. Other known sources of
-/// leakage are:
+/// Because forgetting a value is allowed, any `unsafe` code you write must
+/// allow for this possibility. You cannot return a value and expect that the
+/// caller will necessarily run the value's destructor.
 ///
-/// * `Rc` and `Arc` cycles
-/// * `mpsc::{Sender, Receiver}` cycles (they use `Arc` internally)
-/// * Panicking destructors are likely to leak local resources
+/// [rc]: ../../std/rc/struct.Rc.html
+/// [exit]: ../../std/process/fn.exit.html
 ///
-/// # Example
+/// # Examples
 ///
 /// Leak some heap memory by never deallocating it:
 ///
-/// ```rust
+/// ```
 /// use std::mem;
 ///
 /// let heap_memory = Box::new(3);
@@ -77,7 +62,7 @@
 ///
 /// Leak an I/O object, never closing the file:
 ///
-/// ```rust,no_run
+/// ```no_run
 /// use std::mem;
 /// use std::fs::File;
 ///
@@ -85,9 +70,43 @@
 /// mem::forget(file);
 /// ```
 ///
-/// The `mem::swap` function uses `mem::forget` to good effect:
+/// The practical use cases for `forget` are rather specialized and mainly come
+/// up in unsafe or FFI code.
+///
+/// ## Use case 1
+///
+/// You have created an uninitialized value using [`mem::uninitialized`][uninit].
+/// You must either initialize or `forget` it on every computation path before
+/// Rust drops it automatically, like at the end of a scope or after a panic.
+/// Running the destructor on an uninitialized value would be [undefined behavior][ub].
+///
+/// ```
+/// use std::mem;
+/// use std::ptr;
+///
+/// # let some_condition = false;
+/// unsafe {
+///     let mut uninit_vec: Vec<u32> = mem::uninitialized();
+///
+///     if some_condition {
+///         // Initialize the variable.
+///         ptr::write(&mut uninit_vec, Vec::new());
+///     } else {
+///         // Forget the uninitialized value so its destructor doesn't run.
+///         mem::forget(uninit_vec);
+///     }
+/// }
+/// ```
+///
+/// ## Use case 2
+///
+/// You have duplicated the bytes making up a value, without doing a proper
+/// [`Clone`][clone]. You need the value's destructor to run only once,
+/// because a double `free` is undefined behavior.
 ///
-/// ```rust
+/// An example is the definition of [`mem::swap`][swap] in this module:
+///
+/// ```
 /// use std::mem;
 /// use std::ptr;
 ///
@@ -109,6 +128,41 @@
 ///     }
 /// }
 /// ```
+///
+/// ## Use case 3
+///
+/// You are transferring ownership across a [FFI] boundary to code written in
+/// another language. You need to `forget` the value on the Rust side because Rust
+/// code is no longer responsible for it.
+///
+/// ```no_run
+/// use std::mem;
+///
+/// extern "C" {
+///     fn my_c_function(x: *const u32);
+/// }
+///
+/// let x: Box<u32> = Box::new(3);
+///
+/// // Transfer ownership into C code.
+/// unsafe {
+///     my_c_function(&*x);
+/// }
+/// mem::forget(x);
+/// ```
+///
+/// In this case, C code must call back into Rust to free the object. Calling C's `free`
+/// function on a [`Box`][box] is *not* safe! Also, `Box` provides an [`into_raw`][into_raw]
+/// method which is the preferred way to do this in practice.
+///
+/// [drop]: fn.drop.html
+/// [uninit]: fn.uninitialized.html
+/// [clone]: ../clone/trait.Clone.html
+/// [swap]: fn.swap.html
+/// [FFI]: ../../book/ffi.html
+/// [box]: ../../std/boxed/struct.Box.html
+/// [into_raw]: ../../std/boxed/struct.Box.html#method.into_raw
+/// [ub]: ../../reference.html#behavior-considered-undefined
 #[inline]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub fn forget<T>(t: T) {
@@ -133,7 +187,14 @@ pub fn size_of<T>() -> usize {
     unsafe { intrinsics::size_of::<T>() }
 }
 
-/// Returns the size of the given value in bytes.
+/// Returns the size of the pointed-to value in bytes.
+///
+/// This is usually the same as `size_of::<T>()`. However, when `T` *has* no
+/// statically known size, e.g. a slice [`[T]`][slice] or a [trait object],
+/// then `size_of_val` can be used to get the dynamically-known size.
+///
+/// [slice]: ../../std/primitive.slice.html
+/// [trait object]: ../../book/trait-objects.html
 ///
 /// # Examples
 ///
@@ -141,6 +202,10 @@ pub fn size_of<T>() -> usize {
 /// use std::mem;
 ///
 /// assert_eq!(4, mem::size_of_val(&5i32));
+///
+/// let x: [u8; 13] = [0; 13];
+/// let y: &[u8] = &x;
+/// assert_eq!(13, mem::size_of_val(y));
 /// ```
 #[inline]
 #[stable(feature = "rust1", since = "1.0.0")]
@@ -148,10 +213,14 @@ pub fn size_of_val<T: ?Sized>(val: &T) -> usize {
     unsafe { intrinsics::size_of_val(val) }
 }
 
-/// Returns the ABI-required minimum alignment of a type
+/// Returns the [ABI]-required minimum alignment of a type.
+///
+/// Every valid address of a value of the type `T` must be a multiple of this number.
 ///
 /// This is the alignment used for struct fields. It may be smaller than the preferred alignment.
 ///
+/// [ABI]: https://en.wikipedia.org/wiki/Application_binary_interface
+///
 /// # Examples
 ///
 /// ```
@@ -167,7 +236,11 @@ pub fn min_align_of<T>() -> usize {
     unsafe { intrinsics::min_align_of::<T>() }
 }
 
-/// Returns the ABI-required minimum alignment of the type of the value that `val` points to
+/// Returns the [ABI]-required minimum alignment of the type of the value that `val` points to.
+///
+/// Every valid address of a value of the type `T` must be a multiple of this number.
+///
+/// [ABI]: https://en.wikipedia.org/wiki/Application_binary_interface
 ///
 /// # Examples
 ///
@@ -184,10 +257,14 @@ pub fn min_align_of_val<T: ?Sized>(val: &T) -> usize {
     unsafe { intrinsics::min_align_of_val(val) }
 }
 
-/// Returns the alignment in memory for a type.
+/// Returns the [ABI]-required minimum alignment of a type.
+///
+/// Every valid address of a value of the type `T` must be a multiple of this number.
 ///
 /// This is the alignment used for struct fields. It may be smaller than the preferred alignment.
 ///
+/// [ABI]: https://en.wikipedia.org/wiki/Application_binary_interface
+///
 /// # Examples
 ///
 /// ```
@@ -201,7 +278,11 @@ pub fn align_of<T>() -> usize {
     unsafe { intrinsics::min_align_of::<T>() }
 }
 
-/// Returns the ABI-required minimum alignment of the type of the value that `val` points to
+/// Returns the [ABI]-required minimum alignment of the type of the value that `val` points to.
+///
+/// Every valid address of a value of the type `T` must be a multiple of this number.
+///
+/// [ABI]: https://en.wikipedia.org/wiki/Application_binary_interface
 ///
 /// # Examples
 ///
@@ -216,16 +297,23 @@ pub fn align_of_val<T: ?Sized>(val: &T) -> usize {
     unsafe { intrinsics::min_align_of_val(val) }
 }
 
-/// Creates a value initialized to zero.
+/// Creates a value whose bytes are all zero.
+///
+/// This has the same effect as allocating space with
+/// [`mem::uninitialized`][uninit] and then zeroing it out. It is useful for
+/// [FFI] sometimes, but should generally be avoided.
 ///
-/// This function is similar to allocating space for a local variable and zeroing it out (an unsafe
-/// operation).
+/// There is no guarantee that an all-zero byte-pattern represents a valid value of
+/// some type `T`. If `T` has a destructor and the value is destroyed (due to
+/// a panic or the end of a scope) before being initialized, then the destructor
+/// will run on zeroed data, likely leading to [undefined behavior][ub].
 ///
-/// Care must be taken when using this function, if the type `T` has a destructor and the value
-/// falls out of scope (due to unwinding or returning) before being initialized, then the
-/// destructor will run on zeroed data, likely leading to crashes.
+/// See also the documentation for [`mem::uninitialized`][uninit], which has
+/// many of the same caveats.
 ///
-/// This is useful for FFI functions sometimes, but should generally be avoided.
+/// [uninit]: fn.uninitialized.html
+/// [FFI]: ../../book/ffi.html
+/// [ub]: ../../reference.html#behavior-considered-undefined
 ///
 /// # Examples
 ///
@@ -233,6 +321,7 @@ pub fn align_of_val<T: ?Sized>(val: &T) -> usize {
 /// use std::mem;
 ///
 /// let x: i32 = unsafe { mem::zeroed() };
+/// assert_eq!(0, x);
 /// ```
 #[inline]
 #[stable(feature = "rust1", since = "1.0.0")]
@@ -241,32 +330,38 @@ pub unsafe fn zeroed<T>() -> T {
 }
 
 /// Bypasses Rust's normal memory-initialization checks by pretending to
-/// produce a value of type T, while doing nothing at all.
+/// produce a value of type `T`, while doing nothing at all.
 ///
 /// **This is incredibly dangerous, and should not be done lightly. Deeply
 /// consider initializing your memory with a default value instead.**
 ///
-/// This is useful for FFI functions and initializing arrays sometimes,
+/// This is useful for [FFI] functions and initializing arrays sometimes,
 /// but should generally be avoided.
 ///
-/// # Undefined Behavior
+/// [FFI]: ../../book/ffi.html
 ///
-/// It is Undefined Behavior to read uninitialized memory. Even just an
+/// # Undefined behavior
+///
+/// It is [undefined behavior][ub] to read uninitialized memory, even just an
 /// uninitialized boolean. For instance, if you branch on the value of such
-/// a boolean your program may take one, both, or neither of the branches.
+/// a boolean, your program may take one, both, or neither of the branches.
 ///
-/// Note that this often also includes *writing* to the uninitialized value.
-/// Rust believes the value is initialized, and will therefore try to Drop
-/// the uninitialized value and its fields if you try to overwrite the memory
-/// in a normal manner. The only way to safely initialize an arbitrary
-/// uninitialized value is with one of the `ptr` functions: `write`, `copy`, or
-/// `copy_nonoverlapping`. This isn't necessary if `T` is a primitive
-/// or otherwise only contains types that don't implement Drop.
+/// Writing to the uninitialized value is similarly dangerous. Rust believes the
+/// value is initialized, and will therefore try to [`Drop`][drop] the uninitialized
+/// value and its fields if you try to overwrite it in a normal manner. The only way
+/// to safely initialize an uninitialized value is with [`ptr::write`][write],
+/// [`ptr::copy`][copy], or [`ptr::copy_nonoverlapping`][copy_no].
 ///
-/// If this value *does* need some kind of Drop, it must be initialized before
+/// If the value does implement `Drop`, it must be initialized before
 /// it goes out of scope (and therefore would be dropped). Note that this
 /// includes a `panic` occurring and unwinding the stack suddenly.
 ///
+/// [ub]: ../../reference.html#behavior-considered-undefined
+/// [write]: ../ptr/fn.write.html
+/// [copy]: ../intrinsics/fn.copy.html
+/// [copy_no]: ../intrinsics/fn.copy_nonoverlapping.html
+/// [drop]: ../ops/trait.Drop.html
+///
 /// # Examples
 ///
 /// Here's how to safely initialize an array of `Vec`s.
@@ -309,8 +404,8 @@ pub unsafe fn zeroed<T>() -> T {
 /// println!("{:?}", &data[0]);
 /// ```
 ///
-/// This example emphasizes exactly how delicate and dangerous doing this is.
-/// Note that the `vec!` macro *does* let you initialize every element with a
+/// This example emphasizes exactly how delicate and dangerous using `mem::uninitialized`
+/// can be. Note that the `vec!` macro *does* let you initialize every element with a
 /// value that is only `Clone`, so the following is semantically equivalent and
 /// vastly less dangerous, as long as you can live with an extra heap
 /// allocation:
@@ -325,21 +420,20 @@ pub unsafe fn uninitialized<T>() -> T {
     intrinsics::uninit()
 }
 
-/// Swap the values at two mutable locations of the same type, without deinitializing or copying
-/// either one.
+/// Swaps the values at two mutable locations, without deinitializing either one.
 ///
 /// # Examples
 ///
 /// ```
 /// use std::mem;
 ///
-/// let x = &mut 5;
-/// let y = &mut 42;
+/// let mut x = 5;
+/// let mut y = 42;
 ///
-/// mem::swap(x, y);
+/// mem::swap(&mut x, &mut y);
 ///
-/// assert_eq!(42, *x);
-/// assert_eq!(5, *y);
+/// assert_eq!(42, x);
+/// assert_eq!(5, y);
 /// ```
 #[inline]
 #[stable(feature = "rust1", since = "1.0.0")]
@@ -361,10 +455,7 @@ pub fn swap<T>(x: &mut T, y: &mut T) {
 }
 
 /// Replaces the value at a mutable location with a new one, returning the old value, without
-/// deinitializing or copying either one.
-///
-/// This is primarily used for transferring and swapping ownership of a value in a mutable
-/// location.
+/// deinitializing either one.
 ///
 /// # Examples
 ///
@@ -373,15 +464,17 @@ pub fn swap<T>(x: &mut T, y: &mut T) {
 /// ```
 /// use std::mem;
 ///
-/// let mut v: Vec<i32> = Vec::new();
+/// let mut v: Vec<i32> = vec![1, 2];
 ///
-/// mem::replace(&mut v, Vec::new());
+/// let old_v = mem::replace(&mut v, vec![3, 4, 5]);
+/// assert_eq!(2, old_v.len());
+/// assert_eq!(3, v.len());
 /// ```
 ///
-/// This function allows consumption of one field of a struct by replacing it with another value.
-/// The normal approach doesn't always work:
+/// `replace` allows consumption of a struct field by replacing it with another value.
+/// Without `replace` you can run into issues like these:
 ///
-/// ```rust,ignore
+/// ```ignore
 /// struct Buffer<T> { buf: Vec<T> }
 ///
 /// impl<T> Buffer<T> {
@@ -401,6 +494,7 @@ pub fn swap<T>(x: &mut T, y: &mut T) {
 /// ```
 /// # #![allow(dead_code)]
 /// use std::mem;
+///
 /// # struct Buffer<T> { buf: Vec<T> }
 /// impl<T> Buffer<T> {
 ///     fn get_and_reset(&mut self) -> Vec<T> {
@@ -417,14 +511,25 @@ pub fn replace<T>(dest: &mut T, mut src: T) -> T {
 
 /// Disposes of a value.
 ///
-/// While this does call the argument's implementation of `Drop`, it will not
-/// release any borrows, as borrows are based on lexical scope.
+/// While this does call the argument's implementation of [`Drop`][drop],
+/// it will not release any borrows, as borrows are based on lexical scope.
 ///
 /// This effectively does nothing for
 /// [types which implement `Copy`](../../book/ownership.html#copy-types),
 /// e.g. integers. Such values are copied and _then_ moved into the function,
 /// so the value persists after this function call.
 ///
+/// This function is not magic; it is literally defined as
+///
+/// ```
+/// pub fn drop<T>(_x: T) { }
+/// ```
+///
+/// Because `_x` is moved into the function, it is automatically dropped before
+/// the function returns.
+///
+/// [drop]: ../ops/trait.Drop.html
+///
 /// # Examples
 ///
 /// Basic usage:
@@ -461,8 +566,8 @@ pub fn replace<T>(dest: &mut T, mut src: T) -> T {
 /// v.push(4); // no problems
 /// ```
 ///
-/// Since `RefCell` enforces the borrow rules at runtime, `drop()` can
-/// seemingly release a borrow of one:
+/// Since `RefCell` enforces the borrow rules at runtime, `drop` can
+/// release a `RefCell` borrow:
 ///
 /// ```
 /// use std::cell::RefCell;
@@ -478,7 +583,7 @@ pub fn replace<T>(dest: &mut T, mut src: T) -> T {
 /// println!("{}", *borrow);
 /// ```
 ///
-/// Integers and other types implementing `Copy` are unaffected by `drop()`
+/// Integers and other types implementing `Copy` are unaffected by `drop`.
 ///
 /// ```
 /// #[derive(Copy, Clone)]
@@ -496,19 +601,22 @@ pub fn replace<T>(dest: &mut T, mut src: T) -> T {
 #[stable(feature = "rust1", since = "1.0.0")]
 pub fn drop<T>(_x: T) { }
 
-/// Interprets `src` as `&U`, and then reads `src` without moving the contained
-/// value.
+/// Interprets `src` as having type `&U`, and then reads `src` without moving
+/// the contained value.
 ///
 /// This function will unsafely assume the pointer `src` is valid for
-/// `sizeof(U)` bytes by transmuting `&T` to `&U` and then reading the `&U`. It
-/// will also unsafely create a copy of the contained value instead of moving
-/// out of `src`.
+/// [`size_of::<U>()`][size_of] bytes by transmuting `&T` to `&U` and then reading
+/// the `&U`. It will also unsafely create a copy of the contained value instead of
+/// moving out of `src`.
 ///
 /// It is not a compile-time error if `T` and `U` have different sizes, but it
 /// is highly encouraged to only invoke this function where `T` and `U` have the
-/// same size. This function triggers undefined behavior if `U` is larger than
+/// same size. This function triggers [undefined behavior][ub] if `U` is larger than
 /// `T`.
 ///
+/// [ub]: ../../reference.html#behavior-considered-undefined
+/// [size_of]: fn.size_of.html
+///
 /// # Examples
 ///
 /// ```
diff --git a/src/librustc_const_eval/check_match.rs b/src/librustc_const_eval/check_match.rs
index da4445ef68947c7db45d627a96eff76e0b65d0b8..a1e7d0a1e34deaa8031ce33f36b39216b5bf72d2 100644
--- a/src/librustc_const_eval/check_match.rs
+++ b/src/librustc_const_eval/check_match.rs
@@ -410,10 +410,13 @@ fn check_exhaustive<'a, 'tcx>(cx: &MatchCheckCtxt<'a, 'tcx>,
                         },
                         _ => bug!(),
                     };
-                    span_err!(cx.tcx.sess, sp, E0297,
+                    let pattern_string = pat_to_string(witness);
+                    struct_span_err!(cx.tcx.sess, sp, E0297,
                         "refutable pattern in `for` loop binding: \
                                 `{}` not covered",
-                                pat_to_string(witness));
+                                pattern_string)
+                        .span_label(sp, &format!("pattern `{}` not covered", pattern_string))
+                        .emit();
                 },
                 _ => {
                     let pattern_strings: Vec<_> = witnesses.iter().map(|w| {
diff --git a/src/libstd/io/buffered.rs b/src/libstd/io/buffered.rs
index a26a932ad2de6c076f9d3d0720ce4135802aebf1..dbb45d54f38d185a57a5828d75b6d1927b25c8f0 100644
--- a/src/libstd/io/buffered.rs
+++ b/src/libstd/io/buffered.rs
@@ -468,8 +468,7 @@ fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
             self.panicked = false;
             r
         } else {
-            let amt = cmp::min(buf.len(), self.buf.capacity());
-            Write::write(&mut self.buf, &buf[..amt])
+            Write::write(&mut self.buf, buf)
         }
     }
     fn flush(&mut self) -> io::Result<()> {
diff --git a/src/libstd/primitive_docs.rs b/src/libstd/primitive_docs.rs
index 2b92da6c684a43f2e5680000520583964b7d2bff..fdc84467015f90ca970796252524e6be03b6c537 100644
--- a/src/libstd/primitive_docs.rs
+++ b/src/libstd/primitive_docs.rs
@@ -249,37 +249,58 @@ mod prim_pointer { }
 #[doc(primitive = "array")]
 //
 /// A fixed-size array, denoted `[T; N]`, for the element type, `T`, and the
-/// non-negative compile time constant size, `N`.
+/// non-negative compile-time constant size, `N`.
 ///
-/// Arrays values are created either with an explicit expression that lists
-/// each element: `[x, y, z]` or a repeat expression: `[x; N]`. The repeat
-/// expression requires that the element type is `Copy`.
+/// There are two syntactic forms for creating an array:
 ///
-/// The type `[T; N]` is `Copy` if `T: Copy`.
+/// * A list with each element, i.e. `[x, y, z]`.
+/// * A repeat expression `[x; N]`, which produces an array with `N` copies of `x`.
+///   The type of `x` must be [`Copy`][copy].
 ///
 /// Arrays of sizes from 0 to 32 (inclusive) implement the following traits if
 /// the element type allows it:
 ///
-/// - `Clone` (only if `T: Copy`)
-/// - `Debug`
-/// - `IntoIterator` (implemented for `&[T; N]` and `&mut [T; N]`)
-/// - `PartialEq`, `PartialOrd`, `Ord`, `Eq`
-/// - `Hash`
-/// - `AsRef`, `AsMut`
-/// - `Borrow`, `BorrowMut`
-/// - `Default`
-///
-/// This limitation to `N in 0..33` exists because Rust does not yet support
-/// generics over the size of an array type. `[Foo; 3]` and `[Bar; 3]` are
-/// instances of same generic type `[T; 3]`, but `[Foo; 3]` and `[Foo; 5]` are
+/// - [`Clone`][clone] (only if `T: Copy`)
+/// - [`Debug`][debug]
+/// - [`IntoIterator`][intoiterator] (implemented for `&[T; N]` and `&mut [T; N]`)
+/// - [`PartialEq`][partialeq], [`PartialOrd`][partialord], [`Eq`][eq], [`Ord`][ord]
+/// - [`Hash`][hash]
+/// - [`AsRef`][asref], [`AsMut`][asmut]
+/// - [`Borrow`][borrow], [`BorrowMut`][borrowmut]
+/// - [`Default`][default]
+///
+/// This limitation on the size `N` exists because Rust does not yet support
+/// code that is generic over the size of an array type. `[Foo; 3]` and `[Bar; 3]`
+/// are instances of same generic type `[T; 3]`, but `[Foo; 3]` and `[Foo; 5]` are
 /// entirely different types. As a stopgap, trait implementations are
-/// statically generated for `N in 0..33`.
+/// statically generated up to size 32.
 ///
-/// Arrays coerce to [slices (`[T]`)][slice], so their methods can be called on
-/// arrays. Slices are dynamic and do not coerce to arrays; consequently more
-/// methods are defined on `slice` where they support both types.
+/// Arrays of *any* size are [`Copy`][copy] if the element type is `Copy`. This
+/// works because the `Copy` trait is specially known to the compiler.
+///
+/// Arrays coerce to [slices (`[T]`)][slice], so a slice method may be called on
+/// an array. Indeed, this provides most of the API for working with arrays.
+/// Slices have a dynamic size and do not coerce to arrays.
+///
+/// There is no way to move elements out of an array. See [`mem::replace`][replace]
+/// for an alternative.
 ///
 /// [slice]: primitive.slice.html
+/// [copy]: marker/trait.Copy.html
+/// [clone]: clone/trait.Clone.html
+/// [debug]: fmt/trait.Debug.html
+/// [intoiterator]: iter/trait.IntoIterator.html
+/// [partialeq]: cmp/trait.PartialEq.html
+/// [partialord]: cmp/trait.PartialOrd.html
+/// [eq]: cmp/trait.Eq.html
+/// [ord]: cmp/trait.Ord.html
+/// [hash]: hash/trait.Hash.html
+/// [asref]: convert/trait.AsRef.html
+/// [asmut]: convert/trait.AsMut.html
+/// [borrow]: borrow/trait.Borrow.html
+/// [borrowmut]: borrow/trait.BorrowMut.html
+/// [default]: default/trait.Default.html
+/// [replace]: mem/fn.replace.html
 ///
 /// # Examples
 ///
@@ -295,7 +316,30 @@ mod prim_pointer { }
 /// for x in &array {
 ///     print!("{} ", x);
 /// }
+/// ```
+///
+/// An array itself is not iterable:
+///
+/// ```ignore
+/// let array: [i32; 3] = [0; 3];
+///
+/// for x in array { }
+/// // error: the trait bound `[i32; 3]: std::iter::Iterator` is not satisfied
+/// ```
 ///
+/// The solution is to coerce the array to a slice by calling a slice method:
+///
+/// ```
+/// # let array: [i32; 3] = [0; 3];
+/// for x in array.iter() { }
+/// ```
+///
+/// If the array has 32 or fewer elements (see above), you can also use the
+/// array reference's `IntoIterator` implementation:
+///
+/// ```
+/// # let array: [i32; 3] = [0; 3];
+/// for x in &array { }
 /// ```
 ///
 mod prim_array { }
diff --git a/src/test/compile-fail/E0297.rs b/src/test/compile-fail/E0297.rs
index 43166c1a9e83e4f4a53a2e9bde49d1b6c1ec0771..32c129b22a1668683cfc79252fbf2e8fdb9402db 100644
--- a/src/test/compile-fail/E0297.rs
+++ b/src/test/compile-fail/E0297.rs
@@ -11,5 +11,7 @@
 fn main() {
     let xs : Vec<Option<i32>> = vec!(Some(1), None);
 
-    for Some(x) in xs {} //~ ERROR E0297
+    for Some(x) in xs {}
+    //~^ ERROR E0297
+    //~| NOTE pattern `None` not covered
 }