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, 11 deletions

diff --git a/src/libstd/io/process.rs b/src/libstd/io/process.rs
index 43ca7b13145..7b0a86777f6 100644
--- a/src/libstd/io/process.rs
+++ b/src/libstd/io/process.rs
@@ -397,7 +397,7 @@ impl Command {
     }
 }
 
-impl fmt::String for Command {
+impl fmt::Debug for Command {
     /// Format the program and arguments of a Command for display. Any
     /// non-utf8 data is lossily converted using the utf8 replacement
     /// character.
@@ -496,7 +496,7 @@ pub enum StdioContainer {
 
 /// Describes the result of a process after it has terminated.
 /// Note that Windows have no signals, so the result is usually ExitStatus.
-#[derive(PartialEq, Eq, Clone, Copy)]
+#[derive(PartialEq, Eq, Clone, Copy, Show)]
 pub enum ProcessExit {
     /// Normal termination with an exit status.
     ExitStatus(int),
@@ -505,15 +505,8 @@ pub enum ProcessExit {
     ExitSignal(int),
 }
 
-impl fmt::Show for ProcessExit {
-    /// Format a ProcessExit enum, to nicely present the information.
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        fmt::String::fmt(self, f)
-    }
-}
-
-
-impl fmt::String for ProcessExit {
+#[stable]
+impl fmt::Display for ProcessExit {
     /// Format a ProcessExit enum, to nicely present the information.
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         match *self {