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, 4 insertions, 4 deletions

diff --git a/src/libcore/any.rs b/src/libcore/any.rs
index 20ed2253861..6e9d2f349bf 100644
--- a/src/libcore/any.rs
+++ b/src/libcore/any.rs
@@ -34,11 +34,11 @@
 //! use runtime reflection instead.
 //!
 //! ```rust
-//! use std::fmt::Show;
+//! use std::fmt::Debug;
 //! use std::any::Any;
 //!
-//! // Logger function for any type that implements Show.
-//! fn log<T: Any+Show>(value: &T) {
+//! // Logger function for any type that implements Debug.
+//! fn log<T: Any + Debug>(value: &T) {
 //!     let value_any = value as &Any;
 //!
 //!     // try to convert our value to a String.  If successful, we want to
@@ -55,7 +55,7 @@
 //! }
 //!
 //! // This function wants to log its parameter out prior to doing work with it.
-//! fn do_work<T: Show+'static>(value: &T) {
+//! fn do_work<T: Debug + 'static>(value: &T) {
 //!     log(value);
 //!     // ...do some other work
 //! }