std: Stabilize std::fmt

This commit applies the stabilization of std::fmt as outlined in [RFC 380][rfc].
There are a number of breaking changes as a part of this commit which will need
to be handled to migrated old code:

* A number of formatting traits have been removed: String, Bool, Char, Unsigned,
  Signed, and Float. It is recommended to instead use Show wherever possible or
  to use adaptor structs to implement other methods of formatting.

* The format specifier for Boolean has changed from `t` to `b`.

* The enum `FormatError` has been renamed to `Error` as well as becoming a unit
  struct instead of an enum. The `WriteError` variant no longer exists.

* The `format_args_method!` macro has been removed with no replacement. Alter
  code to use the `format_args!` macro instead.

* The public fields of a `Formatter` have become read-only with no replacement.
  Use a new formatting string to alter the formatting flags in combination with
  the `write!` macro. The fields can be accessed through accessor methods on the
  `Formatter` structure.

Other than these breaking changes, the contents of std::fmt should now also all
contain stability markers. Most of them are still #[unstable] or #[experimental]

[rfc]: https://github.com/rust-lang/rfcs/blob/master/text/0380-stabilize-std-fmt.md
[breaking-change]

Closes #18904

1 files changed, 5 insertions, 7 deletions

diff --git a/src/libstd/io/mod.rs b/src/libstd/io/mod.rs
index 82bfa3c4e80..681400e9db5 100644
--- a/src/libstd/io/mod.rs
+++ b/src/libstd/io/mod.rs
@@ -1034,7 +1034,7 @@ pub trait Writer {
                     Ok(()) => Ok(()),
                     Err(e) => {
                         self.error = Err(e);
-                        Err(fmt::WriteError)
+                        Err(fmt::Error)
                     }
                 }
             }
@@ -1081,13 +1081,13 @@ pub trait Writer {
     /// Write the result of passing n through `int::to_str_bytes`.
     #[inline]
     fn write_int(&mut self, n: int) -> IoResult<()> {
-        write!(self, "{:d}", n)
+        write!(self, "{}", n)
     }
 
     /// Write the result of passing n through `uint::to_str_bytes`.
     #[inline]
     fn write_uint(&mut self, n: uint) -> IoResult<()> {
-        write!(self, "{:u}", n)
+        write!(self, "{}", n)
     }
 
     /// Write a little-endian uint (number of bytes depends on system).
@@ -1896,10 +1896,8 @@ impl Default for FilePermission {
 }
 
 impl fmt::Show for FilePermission {
-    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
-        formatter.fill = '0';
-        formatter.width = Some(4);
-        (&self.bits as &fmt::Octal).fmt(formatter)
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "{:04o}", self.bits)
     }
 }