review comments: modify note wording and change `println`

- Don't print the newline on its own to avoid the possibility of
  printing it out of order due to `stdout` locking.
- Modify wording of `concat!()` with non-literals to not mislead into
  believing that only `&str` literals are accepted.
- Add test for `concat!()` with non-literals.

1 files changed, 1 insertions, 8 deletions

diff --git a/src/libstd/macros.rs b/src/libstd/macros.rs
index a4a6ed73c61..7f3c8fcdd5a 100644
--- a/src/libstd/macros.rs
+++ b/src/libstd/macros.rs
@@ -155,14 +155,7 @@ macro_rules! print {
 #[stable(feature = "rust1", since = "1.0.0")]
 macro_rules! println {
     () => (print!("\n"));
-    ($fmt:expr) => ({
-        print!($fmt);
-        print!("\n");
-    });
-    ($fmt:expr, $($arg:tt)*) => ({
-        print!($fmt, $($arg)*);
-        print!("\n");
-    });
+    ($($arg:tt)*) => (print!("{}\n", format_args!($($arg)*)));
 }
 
 /// Macro for printing to the standard error.