std: Rename Show/String to Debug/Display

This commit is an implementation of [RFC 565][rfc] which is a stabilization of
the `std::fmt` module and the implementations of various formatting traits.
Specifically, the following changes were performed:

[rfc]: https://github.com/rust-lang/rfcs/blob/master/text/0565-show-string-guidelines.md

* The `Show` trait is now deprecated, it was renamed to `Debug`
* The `String` trait is now deprecated, it was renamed to `Display`
* Many `Debug` and `Display` implementations were audited in accordance with the
  RFC and audited implementations now have the `#[stable]` attribute
  * Integers and floats no longer print a suffix
  * Smart pointers no longer print details that they are a smart pointer
  * Paths with `Debug` are now quoted and escape characters
* The `unwrap` methods on `Result` now require `Display` instead of `Debug`
* The `Error` trait no longer has a `detail` method and now requires that
  `Display` must be implemented. With the loss of `String`, this has moved into
  libcore.
* `impl<E: Error> FromError<E> for Box<Error>` now exists
* `derive(Show)` has been renamed to `derive(Debug)`. This is not currently
  warned about due to warnings being emitted on stage1+

While backwards compatibility is attempted to be maintained with a blanket
implementation of `Display` for the old `String` trait (and the same for
`Show`/`Debug`) this is still a breaking change due to primitives no longer
implementing `String` as well as modifications such as `unwrap` and the `Error`
trait. Most code is fairly straightforward to update with a rename or tweaks of
method calls.

[breaking-change]
Closes #21436

1 files changed, 8 insertions, 4 deletions

diff --git a/src/libstd/io/buffered.rs b/src/libstd/io/buffered.rs
index 8c38bc009cc..c1244abbfcb 100644
--- a/src/libstd/io/buffered.rs
+++ b/src/libstd/io/buffered.rs
@@ -52,7 +52,8 @@ pub struct BufferedReader<R> {
     cap: uint,
 }
 
-impl<R> fmt::Show for BufferedReader<R> where R: fmt::Show {
+#[stable]
+impl<R> fmt::Debug for BufferedReader<R> where R: fmt::Debug {
     fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
         write!(fmt, "BufferedReader {{ reader: {:?}, buffer: {}/{} }}",
                self.inner, self.cap - self.pos, self.buf.len())
@@ -150,7 +151,8 @@ pub struct BufferedWriter<W> {
     pos: uint
 }
 
-impl<W> fmt::Show for BufferedWriter<W> where W: fmt::Show {
+#[stable]
+impl<W> fmt::Debug for BufferedWriter<W> where W: fmt::Debug {
     fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
         write!(fmt, "BufferedWriter {{ writer: {:?}, buffer: {}/{} }}",
                self.inner.as_ref().unwrap(), self.pos, self.buf.len())
@@ -249,7 +251,8 @@ pub struct LineBufferedWriter<W> {
     inner: BufferedWriter<W>,
 }
 
-impl<W> fmt::Show for LineBufferedWriter<W> where W: fmt::Show {
+#[stable]
+impl<W> fmt::Debug for LineBufferedWriter<W> where W: fmt::Debug {
     fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
         write!(fmt, "LineBufferedWriter {{ writer: {:?}, buffer: {}/{} }}",
                self.inner.inner, self.inner.pos, self.inner.buf.len())
@@ -339,7 +342,8 @@ pub struct BufferedStream<S> {
     inner: BufferedReader<InternalBufferedWriter<S>>
 }
 
-impl<S> fmt::Show for BufferedStream<S> where S: fmt::Show {
+#[stable]
+impl<S> fmt::Debug for BufferedStream<S> where S: fmt::Debug {
     fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
         let reader = &self.inner;
         let writer = &self.inner.inner.0;