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/num/f64.rs b/src/libstd/num/f64.rs
index 29ccfe512b9..4b31e33236d 100644
--- a/src/libstd/num/f64.rs
+++ b/src/libstd/num/f64.rs
@@ -673,8 +673,8 @@ mod tests {
         let inf: f64 = Float::infinity();
         let neg_inf: f64 = Float::neg_infinity();
         let nan: f64 = Float::nan();
-        assert_eq!(match inf.frexp() { (x, _) => x }, inf)
-        assert_eq!(match neg_inf.frexp() { (x, _) => x }, neg_inf)
+        assert_eq!(match inf.frexp() { (x, _) => x }, inf);
+        assert_eq!(match neg_inf.frexp() { (x, _) => x }, neg_inf);
         assert!(match nan.frexp() { (x, _) => x.is_nan() })
     }