Rollup merge of #23010 - alexcrichton:deprecate-some-old-io, r=aturon

 The new `io` module has had some time to bake and this commit stabilizes some of
the utilities associated with it. This commit also deprecates a number of
`std::old_io::util` functions and structures.

These items are now `#[stable]`

* `Cursor`
* `Cursor::{new, into_inner, get_ref, get_mut, position, set_position}`
* Implementations of I/O traits for `Cursor<T>`
* Delegating implementations of I/O traits for references and `Box` pointers
* Implementations of I/O traits for primitives like slices and `Vec<T>`
* `ReadExt::bytes`
* `Bytes` (and impls)
* `ReadExt::chain`
* `Chain` (and impls)
* `ReadExt::take` (and impls)
* `BufReadExt::lines`
* `Lines` (and impls)
* `io::copy`
* `io::{empty, Empty}` (and impls)
* `io::{sink, Sink}` (and impls)
* `io::{repeat, Repeat}` (and impls)

These items remain `#[unstable]`

* Core I/O traits. These may want a little bit more time to bake along with the
  commonly used methods like `read_to_end`.
* `BufReadExt::split` - this function may be renamed to not conflict with
  `SliceExt::split`.
* `Error` - there are a number of questions about its representation,
  `ErrorKind`, and usability.

These items are now `#[deprecated]` in `old_io`

* `LimitReader` - use `take` instead
* `NullWriter` - use `io::sink` instead
* `ZeroReader` - use `io::repeat` instead
* `NullReader` - use `io::empty` instead
* `MultiWriter` - use `broadcast` instead
* `ChainedReader` - use `chain` instead
* `TeeReader` - use `tee` instead
* `copy` - use `io::copy` instead

[breaking-change]

1 files changed, 18 insertions, 2 deletions

diff --git a/src/libstd/io/cursor.rs b/src/libstd/io/cursor.rs
index 8a841742de4..2445f5a7a40 100644
--- a/src/libstd/io/cursor.rs
+++ b/src/libstd/io/cursor.rs
@@ -8,8 +8,6 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-#![allow(missing_copy_implementations)]
-
 use prelude::v1::*;
 use io::prelude::*;
 
@@ -32,6 +30,7 @@ use slice;
 /// Implementations of the I/O traits for `Cursor<T>` are not currently generic
 /// over `T` itself. Instead, specific implementations are provided for various
 /// in-memory buffer types like `Vec<u8>` and `&[u8]`.
+#[stable(feature = "rust1", since = "1.0.0")]
 pub struct Cursor<T> {
     inner: T,
     pos: u64,
@@ -39,26 +38,32 @@ pub struct Cursor<T> {
 
 impl<T> Cursor<T> {
     /// Create a new cursor wrapping the provided underlying I/O object.
+    #[stable(feature = "rust1", since = "1.0.0")]
     pub fn new(inner: T) -> Cursor<T> {
         Cursor { pos: 0, inner: inner }
     }
 
     /// Consume this cursor, returning the underlying value.
+    #[stable(feature = "rust1", since = "1.0.0")]
     pub fn into_inner(self) -> T { self.inner }
 
     /// Get a reference to the underlying value in this cursor.
+    #[stable(feature = "rust1", since = "1.0.0")]
     pub fn get_ref(&self) -> &T { &self.inner }
 
     /// Get a mutable reference to the underlying value in this cursor.
     ///
     /// Care should be taken to avoid modifying the internal I/O state of the
     /// underlying value as it may corrupt this cursor's position.
+    #[stable(feature = "rust1", since = "1.0.0")]
     pub fn get_mut(&mut self) -> &mut T { &mut self.inner }
 
     /// Returns the current value of this cursor
+    #[stable(feature = "rust1", since = "1.0.0")]
     pub fn position(&self) -> u64 { self.pos }
 
     /// Sets the value of this cursor
+    #[stable(feature = "rust1", since = "1.0.0")]
     pub fn set_position(&mut self, pos: u64) { self.pos = pos; }
 }
 
@@ -83,8 +88,11 @@ macro_rules! seek {
     }
 }
 
+#[stable(feature = "rust1", since = "1.0.0")]
 impl<'a> io::Seek for Cursor<&'a [u8]> { seek!(); }
+#[stable(feature = "rust1", since = "1.0.0")]
 impl<'a> io::Seek for Cursor<&'a mut [u8]> { seek!(); }
+#[stable(feature = "rust1", since = "1.0.0")]
 impl io::Seek for Cursor<Vec<u8>> { seek!(); }
 
 macro_rules! read {
@@ -97,8 +105,11 @@ macro_rules! read {
     }
 }
 
+#[stable(feature = "rust1", since = "1.0.0")]
 impl<'a> Read for Cursor<&'a [u8]> { read!(); }
+#[stable(feature = "rust1", since = "1.0.0")]
 impl<'a> Read for Cursor<&'a mut [u8]> { read!(); }
+#[stable(feature = "rust1", since = "1.0.0")]
 impl Read for Cursor<Vec<u8>> { read!(); }
 
 macro_rules! buffer {
@@ -111,10 +122,14 @@ macro_rules! buffer {
     }
 }
 
+#[stable(feature = "rust1", since = "1.0.0")]
 impl<'a> BufRead for Cursor<&'a [u8]> { buffer!(); }
+#[stable(feature = "rust1", since = "1.0.0")]
 impl<'a> BufRead for Cursor<&'a mut [u8]> { buffer!(); }
+#[stable(feature = "rust1", since = "1.0.0")]
 impl<'a> BufRead for Cursor<Vec<u8>> { buffer!(); }
 
+#[stable(feature = "rust1", since = "1.0.0")]
 impl<'a> Write for Cursor<&'a mut [u8]> {
     fn write(&mut self, data: &[u8]) -> io::Result<usize> {
         let pos = cmp::min(self.pos, self.inner.len() as u64);
@@ -125,6 +140,7 @@ impl<'a> Write for Cursor<&'a mut [u8]> {
     fn flush(&mut self) -> io::Result<()> { Ok(()) }
 }
 
+#[stable(feature = "rust1", since = "1.0.0")]
 impl Write for Cursor<Vec<u8>> {
     fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
         // Make sure the internal buffer is as least as big as where we