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, 8 insertions, 3 deletions

diff --git a/src/libsyntax/ptr.rs b/src/libsyntax/ptr.rs
index 37fa8703706..01f3839b039 100644
--- a/src/libsyntax/ptr.rs
+++ b/src/libsyntax/ptr.rs
@@ -36,7 +36,7 @@
 //!   implementation changes (using a special thread-local heap, for example).
 //!   Moreover, a switch to, e.g. `P<'a, T>` would be easy and mostly automated.
 
-use std::fmt::{self, Show};
+use std::fmt::{self, Display, Debug};
 use std::hash::{Hash, Hasher};
 use std::ops::Deref;
 use std::ptr;
@@ -100,9 +100,14 @@ impl<T: PartialEq> PartialEq for P<T> {
 
 impl<T: Eq> Eq for P<T> {}
 
-impl<T: Show> Show for P<T> {
+impl<T: Debug> Debug for P<T> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        (**self).fmt(f)
+        Debug::fmt(&**self, f)
+    }
+}
+impl<T: Display> Display for P<T> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        Display::fmt(&**self, f)
     }
 }