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, 6 insertions, 6 deletions

diff --git a/src/libstd/collections/hash/map.rs b/src/libstd/collections/hash/map.rs
index d3ac632617d..0f1da8c5d3a 100644
--- a/src/libstd/collections/hash/map.rs
+++ b/src/libstd/collections/hash/map.rs
@@ -18,7 +18,7 @@ use borrow::BorrowFrom;
 use clone::Clone;
 use cmp::{max, Eq, PartialEq};
 use default::Default;
-use fmt::{self, Show};
+use fmt::{self, Debug};
 use hash::{self, Hash, SipHasher};
 use iter::{self, Iterator, ExactSizeIterator, IteratorExt, FromIterator, Extend, Map};
 use marker::Sized;
@@ -270,7 +270,7 @@ fn test_resize_policy() {
 /// ```
 /// use std::collections::HashMap;
 ///
-/// #[derive(Hash, Eq, PartialEq, Show)]
+/// #[derive(Hash, Eq, PartialEq, Debug)]
 /// struct Viking {
 ///     name: String,
 ///     country: String,
@@ -1216,8 +1216,8 @@ impl<K, V, S, H> Eq for HashMap<K, V, S>
 {}
 
 #[stable]
-impl<K, V, S, H> Show for HashMap<K, V, S>
-    where K: Eq + Hash<H> + Show, V: Show,
+impl<K, V, S, H> Debug for HashMap<K, V, S>
+    where K: Eq + Hash<H> + Debug, V: Debug,
           S: HashState<Hasher=H>,
           H: hash::Hasher<Output=u64>
 {
@@ -1996,8 +1996,8 @@ mod test_map {
 
         let map_str = format!("{:?}", map);
 
-        assert!(map_str == "HashMap {1i: 2i, 3i: 4i}" ||
-                map_str == "HashMap {3i: 4i, 1i: 2i}");
+        assert!(map_str == "HashMap {1: 2, 3: 4}" ||
+                map_str == "HashMap {3: 4, 1: 2}");
         assert_eq!(format!("{:?}", empty), "HashMap {}");
     }