Revise the eprint(ln)! feature.

 * Factor out the nigh-identical bodies of `_print` and `_eprint` to a helper
   function `print_to` (I was sorely tempted to call it `_doprnt`).
 * Update the issue number for the unstable `eprint` feature.
 * Add entries to the "unstable book" for `eprint` and `eprint_internal`.
 * Style corrections to the documentation.

1 files changed, 7 insertions, 7 deletions

diff --git a/src/libstd/macros.rs b/src/libstd/macros.rs
index d1c304ec46e..98c635d127f 100644
--- a/src/libstd/macros.rs
+++ b/src/libstd/macros.rs
@@ -113,7 +113,7 @@ macro_rules! print {
 ///
 /// # Panics
 ///
-/// Panics if writing to `io::stdout()` fails.
+/// Panics if writing to `io::stdout` fails.
 ///
 /// # Examples
 ///
@@ -133,7 +133,7 @@ macro_rules! println {
 /// Macro for printing to the standard error.
 ///
 /// Equivalent to the `print!` macro, except that output goes to
-/// `io::stderr()` instead of `io::stdout()`.  See `print!` for
+/// `io::stderr` instead of `io::stdout`.  See `print!` for
 /// example usage.
 ///
 /// Use `eprint!` only for error and progress messages.  Use `print!`
@@ -141,9 +141,9 @@ macro_rules! println {
 ///
 /// # Panics
 ///
-/// Panics if writing to `io::stderr()` fails.
+/// Panics if writing to `io::stderr` fails.
 #[macro_export]
-#[unstable(feature = "eprint", issue="39228")]
+#[unstable(feature = "eprint", issue="40528")]
 #[allow_internal_unstable]
 macro_rules! eprint {
     ($($arg:tt)*) => ($crate::io::_eprint(format_args!($($arg)*)));
@@ -152,7 +152,7 @@ macro_rules! eprint {
 /// Macro for printing to the standard error, with a newline.
 ///
 /// Equivalent to the `println!` macro, except that output goes to
-/// `io::stderr()` instead of `io::stdout()`.  See `println!` for
+/// `io::stderr` instead of `io::stdout`.  See `println!` for
 /// example usage.
 ///
 /// Use `eprintln!` only for error and progress messages.  Use `println!`
@@ -160,9 +160,9 @@ macro_rules! eprint {
 ///
 /// # Panics
 ///
-/// Panics if writing to `io::stderr()` fails.
+/// Panics if writing to `io::stderr` fails.
 #[macro_export]
-#[unstable(feature = "eprint", issue="39228")]
+#[unstable(feature = "eprint", issue="40528")]
 macro_rules! eprintln {
     () => (eprint!("\n"));
     ($fmt:expr) => (eprint!(concat!($fmt, "\n")));