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, 16 deletions

diff --git a/src/libsyntax/abi.rs b/src/libsyntax/abi.rs
index 09235ee209c..7447e0b229e 100644
--- a/src/libsyntax/abi.rs
+++ b/src/libsyntax/abi.rs
@@ -15,7 +15,7 @@ pub use self::AbiArchitecture::*;
 
 use std::fmt;
 
-#[derive(Copy, PartialEq)]
+#[derive(Copy, PartialEq, Eq, Show)]
 pub enum Os {
     OsWindows,
     OsMacos,
@@ -26,7 +26,7 @@ pub enum Os {
     OsDragonfly,
 }
 
-#[derive(PartialEq, Eq, Hash, RustcEncodable, RustcDecodable, Clone, Copy)]
+#[derive(PartialEq, Eq, Hash, RustcEncodable, RustcDecodable, Clone, Copy, Show)]
 pub enum Abi {
     // NB: This ordering MUST match the AbiDatas array below.
     // (This is ensured by the test indices_are_correct().)
@@ -119,25 +119,13 @@ impl Abi {
     }
 }
 
-impl fmt::Show for Abi {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        fmt::String::fmt(self, f)
-    }
-}
-
-impl fmt::String for Abi {
+impl fmt::Display for Abi {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         write!(f, "\"{}\"", self.name())
     }
 }
 
-impl fmt::Show for Os {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        fmt::String::fmt(self, f)
-    }
-}
-
-impl fmt::String for Os {
+impl fmt::Display for Os {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         match *self {
             OsLinux => "linux".fmt(f),