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, 3 insertions, 4 deletions

diff --git a/src/libtest/lib.rs b/src/libtest/lib.rs
index f9fb767f77e..f2706298066 100644
--- a/src/libtest/lib.rs
+++ b/src/libtest/lib.rs
@@ -63,7 +63,6 @@ use std::any::Any;
 use std::cmp;
 use std::collections::BTreeMap;
 use std::f64;
-use std::fmt::Show;
 use std::fmt;
 use std::io::fs::PathExtensions;
 use std::io::stdio::StdWriter;
@@ -109,9 +108,9 @@ impl TestName {
         }
     }
 }
-impl fmt::String for TestName {
+impl fmt::Display for TestName {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        fmt::String::fmt(self.as_slice(), f)
+        fmt::Display::fmt(self.as_slice(), f)
     }
 }
 
@@ -172,7 +171,7 @@ impl TestFn {
     }
 }
 
-impl fmt::Show for TestFn {
+impl fmt::Debug for TestFn {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         f.write_str(match *self {
             StaticTestFn(..) => "StaticTestFn(..)",