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, 7 insertions, 1 deletions

diff --git a/src/libstd/macros.rs b/src/libstd/macros.rs
index 26e9e70dff3..4e5dd5d8818 100644
--- a/src/libstd/macros.rs
+++ b/src/libstd/macros.rs
@@ -240,6 +240,7 @@ macro_rules! unimplemented(
 /// format!("x = {}, y = {y}", 10i, y = 30i);
 /// ```
 #[macro_export]
+#[stable]
 macro_rules! format(
     ($($arg:tt)*) => (
         format_args!(::std::fmt::format, $($arg)*)
@@ -259,15 +260,18 @@ macro_rules! format(
 /// write!(&mut w, "formatted {}", "arguments");
 /// ```
 #[macro_export]
+#[stable]
 macro_rules! write(
     ($dst:expr, $($arg:tt)*) => ({
-        format_args_method!($dst, write_fmt, $($arg)*)
+        let dst = &mut *$dst;
+        format_args!(|args| { dst.write_fmt(args) }, $($arg)*)
     })
 )
 
 /// Equivalent to the `write!` macro, except that a newline is appended after
 /// the message is written.
 #[macro_export]
+#[stable]
 macro_rules! writeln(
     ($dst:expr, $fmt:expr $($arg:tt)*) => (
         write!($dst, concat!($fmt, "\n") $($arg)*)
@@ -277,6 +281,7 @@ macro_rules! writeln(
 /// Equivalent to the `println!` macro except that a newline is not printed at
 /// the end of the message.
 #[macro_export]
+#[stable]
 macro_rules! print(
     ($($arg:tt)*) => (format_args!(::std::io::stdio::print_args, $($arg)*))
 )
@@ -294,6 +299,7 @@ macro_rules! print(
 /// println!("format {} arguments", "some");
 /// ```
 #[macro_export]
+#[stable]
 macro_rules! println(
     ($($arg:tt)*) => (format_args!(::std::io::stdio::println_args, $($arg)*))
 )