Fix up stability annotations per feedback.

src/doc/unstable-book/src/SUMMARY.md

@@ -130,8 +130,6 @@
     - [derive_eq](library-features/derive-eq.md)
     - [discriminant_value](library-features/discriminant-value.md)
     - [error_type_id](library-features/error-type-id.md)
-    - [eprint](library-features/eprint.md)
-    - [eprint_internal](library-features/eprint-internal.md)
     - [exact_size_is_empty](library-features/exact-size-is-empty.md)
     - [fd](library-features/fd.md)
     - [fd_read](library-features/fd-read.md)
@@ -180,7 +178,7 @@
     - [peek](library-features/peek.md)
     - [placement_in](library-features/placement-in.md)
     - [placement_new_protocol](library-features/placement-new-protocol.md)
-    - [print](library-features/print.md)
+    - [print_internals](library-features/print-internals.md)
     - [proc_macro_internals](library-features/proc-macro-internals.md)
     - [process_try_wait](library-features/process-try-wait.md)
     - [question_mark_carrier](library-features/question-mark-carrier.md)

src/doc/unstable-book/src/library-features/eprint.md

-# `eprint`
-
-The tracking issue for this feature is: [#40528]
-
-[#40528]: https://github.com/rust-lang/rust/issues/40528
-
-------------------------
-
-This feature enables the `eprint!` and `eprintln!` global macros,
-which are just like `print!` and `println!`, respectively, except that
-they send output to the standard _error_ stream, rather than standard
-output.  (`panic!` messages have always been written to standard error.)
-

src/doc/unstable-book/src/library-features/eprint-internal.md → src/doc/unstable-book/src/library-features/print-internals.md

-# `eprint_internal`
+# `print_internals`
 
 This feature is internal to the Rust compiler and is not intended for general use.
 

src/doc/unstable-book/src/library-features/print.md

-# `print`
-
-This feature is internal to the Rust compiler and is not intended for general use.
-
-------------------------

src/libstd/io/mod.rs

@@ -287,11 +287,11 @@
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use self::util::{copy, sink, Sink, empty, Empty, repeat, Repeat};
 #[stable(feature = "rust1", since = "1.0.0")]
-pub use self::stdio::{stdin, stdout, stderr, _print, Stdin, Stdout, Stderr};
+pub use self::stdio::{stdin, stdout, stderr, Stdin, Stdout, Stderr};
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use self::stdio::{StdoutLock, StderrLock, StdinLock};
-#[unstable(feature = "eprint", issue="40528")]
-pub use self::stdio::_eprint;
+#[unstable(feature = "print_internals", issue = "0")]
+pub use self::stdio::{_print, _eprint};
 #[unstable(feature = "libstd_io_internals", issue = "0")]
 #[doc(no_inline, hidden)]
 pub use self::stdio::{set_panic, set_print};

src/libstd/io/stdio.rs

@@ -692,7 +692,7 @@ fn print_to<T>(args: fmt::Arguments,
     }
 }
 
-#[unstable(feature = "print",
+#[unstable(feature = "print_internals",
            reason = "implementation detail which may disappear or be replaced at any time",
            issue = "0")]
 #[doc(hidden)]
@@ -700,7 +700,7 @@ pub fn _print(args: fmt::Arguments) {
     print_to(args, &LOCAL_STDOUT, stdout, "stdout");
 }
 
-#[unstable(feature = "eprint_internal",
+#[unstable(feature = "print_internals",
            reason = "implementation detail which may disappear or be replaced at any time",
            issue = "0")]
 #[doc(hidden)]

src/libstd/macros.rs

@@ -143,7 +143,7 @@
 ///
 /// Panics if writing to `io::stderr` fails.
 #[macro_export]
-#[unstable(feature = "eprint", issue="40528")]
+#[stable(feature = "eprint", since="1.18.0")]
 #[allow_internal_unstable]
 macro_rules! eprint {
     ($($arg:tt)*) => ($crate::io::_eprint(format_args!($($arg)*)));
@@ -162,7 +162,7 @@
 ///
 /// Panics if writing to `io::stderr` fails.
 #[macro_export]
-#[unstable(feature = "eprint", issue="40528")]
+#[stable(feature = "eprint", since="1.18.0")]
 macro_rules! eprintln {
     () => (eprint!("\n"));
     ($fmt:expr) => (eprint!(concat!($fmt, "\n")));

src/test/run-pass/print-stdout-eprint-stderr.rs

@@ -8,8 +8,6 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-#![feature(eprint)]
-
 use std::{env, process};
 
 fn child() {