librustc: Always parse `macro!()`/`macro![]` as expressions if not

followed by a semicolon.

This allows code like `vec![1i, 2, 3].len();` to work.

This breaks code that uses macros as statements without putting
semicolons after them, such as:

    fn main() {
        ...
        assert!(a == b)
        assert!(c == d)
        println(...);
    }

It also breaks code that uses macros as items without semicolons:

    local_data_key!(foo)

    fn main() {
        println("hello world")
    }

Add semicolons to fix this code. Those two examples can be fixed as
follows:

    fn main() {
        ...
        assert!(a == b);
        assert!(c == d);
        println(...);
    }

    local_data_key!(foo);

    fn main() {
        println("hello world")
    }

RFC #378.

Closes #18635.

[breaking-change]

1 files changed, 2 insertions, 2 deletions

diff --git a/src/libstd/time/duration.rs b/src/libstd/time/duration.rs
index f98cebd9675..8c4a5a6b8c7 100644
--- a/src/libstd/time/duration.rs
+++ b/src/libstd/time/duration.rs
@@ -40,9 +40,9 @@ const SECS_PER_DAY: i64 = 86400;
 /// The number of (non-leap) seconds in a week.
 const SECS_PER_WEEK: i64 = 604800;
 
-macro_rules! try_opt(
+macro_rules! try_opt {
     ($e:expr) => (match $e { Some(v) => v, None => return None })
-)
+}
 
 
 /// ISO 8601 time duration with nanosecond precision.