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, 5 insertions, 5 deletions

diff --git a/src/libcore/result.rs b/src/libcore/result.rs
index 1ab810f937d..c3d49e24978 100644
--- a/src/libcore/result.rs
+++ b/src/libcore/result.rs
@@ -229,7 +229,7 @@
 use self::Result::{Ok, Err};
 
 use clone::Clone;
-use fmt::Show;
+use fmt::Display;
 use iter::{Iterator, IteratorExt, DoubleEndedIterator, FromIterator, ExactSizeIterator};
 use ops::{FnMut, FnOnce};
 use option::Option::{self, None, Some};
@@ -714,7 +714,7 @@ impl<T, E> Result<T, E> {
 }
 
 #[stable]
-impl<T, E: Show> Result<T, E> {
+impl<T, E: Display> Result<T, E> {
     /// Unwraps a result, yielding the content of an `Ok`.
     ///
     /// # Panics
@@ -739,13 +739,13 @@ impl<T, E: Show> Result<T, E> {
         match self {
             Ok(t) => t,
             Err(e) =>
-                panic!("called `Result::unwrap()` on an `Err` value: {:?}", e)
+                panic!("called `Result::unwrap()` on an `Err` value: {}", e)
         }
     }
 }
 
 #[stable]
-impl<T: Show, E> Result<T, E> {
+impl<T: Display, E> Result<T, E> {
     /// Unwraps a result, yielding the content of an `Err`.
     ///
     /// # Panics
@@ -769,7 +769,7 @@ impl<T: Show, E> Result<T, E> {
     pub fn unwrap_err(self) -> E {
         match self {
             Ok(t) =>
-                panic!("called `Result::unwrap_err()` on an `Ok` value: {:?}", t),
+                panic!("called `Result::unwrap_err()` on an `Ok` value: {}", t),
             Err(e) => e
         }
     }