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

Author: alexcrichton

src/compiletest/common.rs

@@ -13,7 +13,7 @@ use std::fmt;
 use std::str::FromStr;
 use regex::Regex;
 
-#[derive(Clone, PartialEq)]
+#[derive(Clone, PartialEq, Debug)]
 pub enum Mode {
     CompileFail,
     RunFail,
@@ -43,9 +43,9 @@ impl FromStr for Mode {
     }
 }
 
-impl fmt::String for Mode {
+impl fmt::Display for Mode {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        fmt::String::fmt(match *self {
+        fmt::Display::fmt(match *self {
             CompileFail => "compile-fail",
             RunFail => "run-fail",
             RunPass => "run-pass",
@@ -58,12 +58,6 @@ impl fmt::String for Mode {
     }
 }
 
-impl fmt::Show for Mode {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        fmt::String::fmt(self, f)
-    }
-}
-
 #[derive(Clone)]
 pub struct Config {
     // The library paths required for running the compiler

src/compiletest/runtest.rs

@@ -547,7 +547,7 @@ fn run_debuginfo_gdb_test(config: &Config, props: &TestProps, testfile: &Path) {
 
             // Add line breakpoints
             for line in breakpoint_lines.iter() {
-                script_str.push_str(&format!("break '{:?}':{}\n",
+                script_str.push_str(&format!("break '{}':{}\n",
                                              testfile.filename_display(),
                                              *line)[]);
             }
@@ -750,7 +750,7 @@ fn run_debuginfo_lldb_test(config: &Config, props: &TestProps, testfile: &Path)
             status: status,
             stdout: out,
             stderr: err,
-            cmdline: format!("{}", cmd)
+            cmdline: format!("{:?}", cmd)
         };
     }
 }
@@ -953,7 +953,7 @@ fn check_expected_errors(expected_errors: Vec<errors::ExpectedError> ,
     }
 
     let prefixes = expected_errors.iter().map(|ee| {
-        format!("{:?}:{}:", testfile.display(), ee.line)
+        format!("{}:{}:", testfile.display(), ee.line)
     }).collect::<Vec<String> >();
 
     #[cfg(windows)]

src/liballoc/arc.rs

@@ -72,7 +72,7 @@ use core::prelude::*;
 use core::atomic;
 use core::atomic::Ordering::{Relaxed, Release, Acquire, SeqCst};
 use core::borrow::BorrowFrom;
-use core::fmt::{self, Show};
+use core::fmt;
 use core::cmp::{Ordering};
 use core::default::Default;
 use core::mem::{min_align_of, size_of};
@@ -578,16 +578,17 @@ impl<T: Ord> Ord for Arc<T> {
 #[stable]
 impl<T: Eq> Eq for Arc<T> {}
 
-impl<T: fmt::Show> fmt::Show for Arc<T> {
+#[stable]
+impl<T: fmt::Display> fmt::Display for Arc<T> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        write!(f, "Arc({:?})", (**self))
+        fmt::Display::fmt(&**self, f)
     }
 }
 
 #[stable]
-impl<T: fmt::String> fmt::String for Arc<T> {
+impl<T: fmt::Debug> fmt::Debug for Arc<T> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        fmt::String::fmt(&**self, f)
+        fmt::Debug::fmt(&**self, f)
     }
 }
 
@@ -806,7 +807,7 @@ mod tests {
     #[test]
     fn show_arc() {
         let a = Arc::new(5u32);
-        assert!(format!("{:?}", a) == "Arc(5u32)")
+        assert_eq!(format!("{:?}", a), "5");
     }
 
     // Make sure deriving works with Arc<T>

src/liballoc/boxed.rs

@@ -16,16 +16,17 @@ use core::any::Any;
 use core::clone::Clone;
 use core::cmp::{PartialEq, PartialOrd, Eq, Ord, Ordering};
 use core::default::Default;
+use core::error::{Error, FromError};
 use core::fmt;
 use core::hash::{self, Hash};
 use core::marker::Sized;
 use core::mem;
+use core::ops::{Deref, DerefMut};
 use core::option::Option;
 use core::ptr::Unique;
 use core::raw::TraitObject;
-use core::result::Result;
 use core::result::Result::{Ok, Err};
-use core::ops::{Deref, DerefMut};
+use core::result::Result;
 
 /// A value that represents the global exchange heap. This is the default
 /// place that the `box` keyword allocates into when no place is supplied.
@@ -156,20 +157,22 @@ impl BoxAny for Box<Any> {
     }
 }
 
-impl<T: ?Sized + fmt::Show> fmt::Show for Box<T> {
+#[stable]
+impl<T: fmt::Display + ?Sized> fmt::Display for Box<T> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        write!(f, "Box({:?})", &**self)
+        fmt::Display::fmt(&**self, f)
     }
 }
 
 #[stable]
-impl<T: ?Sized + fmt::String> fmt::String for Box<T> {
+impl<T: fmt::Debug + ?Sized> fmt::Debug for Box<T> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        fmt::String::fmt(&**self, f)
+        fmt::Debug::fmt(&**self, f)
     }
 }
 
-impl fmt::Show for Box<Any> {
+#[stable]
+impl fmt::Debug for Box<Any> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         f.pad("Box<Any>")
     }
@@ -187,6 +190,12 @@ impl<T: ?Sized> DerefMut for Box<T> {
     fn deref_mut(&mut self) -> &mut T { &mut **self }
 }
 
+impl<'a, E: Error + 'a> FromError<E> for Box<Error + 'a> {
+    fn from_error(err: E) -> Box<Error + 'a> {
+        Box::new(err)
+    }
+}
+
 #[cfg(test)]
 mod test {
     #[test]

src/liballoc/rc.rs

@@ -693,17 +693,17 @@ impl<S: hash::Hasher, T: Hash<S>> Hash<S> for Rc<T> {
     }
 }
 
-#[unstable = "Show is experimental."]
-impl<T: fmt::Show> fmt::Show for Rc<T> {
+#[stable]
+impl<T: fmt::Display> fmt::Display for Rc<T> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        write!(f, "Rc({:?})", **self)
+        fmt::Display::fmt(&**self, f)
     }
 }
 
 #[stable]
-impl<T: fmt::String> fmt::String for Rc<T> {
+impl<T: fmt::Debug> fmt::Debug for Rc<T> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        fmt::String::fmt(&**self, f)
+        fmt::Debug::fmt(&**self, f)
     }
 }
 
@@ -890,8 +890,8 @@ impl<T> Clone for Weak<T> {
     }
 }
 
-#[unstable = "Show is experimental."]
-impl<T: fmt::Show> fmt::Show for Weak<T> {
+#[stable]
+impl<T: fmt::Debug> fmt::Debug for Weak<T> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         write!(f, "(Weak)")
     }
@@ -1134,7 +1134,7 @@ mod tests {
     #[test]
     fn test_show() {
         let foo = Rc::new(75u);
-        assert!(format!("{:?}", foo) == "Rc(75u)")
+        assert_eq!(format!("{:?}", foo), "75");
     }
 
 }

src/libcollections/bit.rs

@@ -972,7 +972,7 @@ impl Ord for Bitv {
 }
 
 #[stable]
-impl fmt::Show for Bitv {
+impl fmt::Debug for Bitv {
     fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
         for bit in self.iter() {
             try!(write!(fmt, "{}", if bit { 1u32 } else { 0u32 }));
@@ -1727,7 +1727,7 @@ impl BitvSet {
     }
 }
 
-impl fmt::Show for BitvSet {
+impl fmt::Debug for BitvSet {
     fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
         try!(write!(fmt, "BitvSet {{"));
         let mut first = true;
@@ -2622,7 +2622,7 @@ mod bitv_set_test {
         s.insert(10);
         s.insert(50);
         s.insert(2);
-        assert_eq!("BitvSet {1u, 2u, 10u, 50u}", format!("{:?}", s));
+        assert_eq!("BitvSet {1, 2, 10, 50}", format!("{:?}", s));
     }
 
     #[test]

src/libcollections/btree/map.rs

@@ -22,7 +22,7 @@ use core::prelude::*;
 use core::borrow::BorrowFrom;
 use core::cmp::Ordering;
 use core::default::Default;
-use core::fmt::Show;
+use core::fmt::Debug;
 use core::hash::{Hash, Hasher};
 use core::iter::{Map, FromIterator};
 use core::ops::{Index, IndexMut};
@@ -871,7 +871,7 @@ impl<K: Ord, V: Ord> Ord for BTreeMap<K, V> {
 }
 
 #[stable]
-impl<K: Show, V: Show> Show for BTreeMap<K, V> {
+impl<K: Debug, V: Debug> Debug for BTreeMap<K, V> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         try!(write!(f, "BTreeMap {{"));
 

src/libcollections/btree/set.rs

@@ -16,7 +16,7 @@ use core::prelude::*;
 use core::borrow::BorrowFrom;
 use core::cmp::Ordering::{self, Less, Greater, Equal};
 use core::default::Default;
-use core::fmt::Show;
+use core::fmt::Debug;
 use core::fmt;
 // NOTE(stage0) remove import after a snapshot
 #[cfg(stage0)]
@@ -592,7 +592,7 @@ impl<'a, 'b, T: Ord + Clone> BitOr<&'b BTreeSet<T>> for &'a BTreeSet<T> {
 }
 
 #[stable]
-impl<T: Show> Show for BTreeSet<T> {
+impl<T: Debug> Debug for BTreeSet<T> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         try!(write!(f, "BTreeSet {{"));
 
@@ -892,7 +892,7 @@ mod test {
 
         let set_str = format!("{:?}", set);
 
-        assert_eq!(set_str, "BTreeSet {1i, 2i}");
+        assert_eq!(set_str, "BTreeSet {1, 2}");
         assert_eq!(format!("{:?}", empty), "BTreeSet {}");
     }
 }

src/libcollections/dlist.rs

@@ -874,7 +874,7 @@ impl<A: Clone> Clone for DList<A> {
 }
 
 #[stable]
-impl<A: fmt::Show> fmt::Show for DList<A> {
+impl<A: fmt::Debug> fmt::Debug for DList<A> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         try!(write!(f, "DList ["));
 
@@ -1333,7 +1333,7 @@ mod tests {
     #[test]
     fn test_show() {
         let list: DList<int> = range(0i, 10).collect();
-        assert_eq!(format!("{:?}", list), "DList [0i, 1i, 2i, 3i, 4i, 5i, 6i, 7i, 8i, 9i]");
+        assert_eq!(format!("{:?}", list), "DList [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]");
 
         let list: DList<&str> = vec!["just", "one", "test", "more"].iter()
                                                                    .map(|&s| s)

src/libcollections/enum_set.rs

@@ -31,7 +31,7 @@ pub struct EnumSet<E> {
 
 impl<E> Copy for EnumSet<E> {}
 
-impl<E:CLike+fmt::Show> fmt::Show for EnumSet<E> {
+impl<E:CLike + fmt::Debug> fmt::Debug for EnumSet<E> {
     fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
         try!(write!(fmt, "EnumSet {{"));
         let mut first = true;