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]

2 files changed, 26 insertions, 21 deletions

diff --git a/src/libsyntax/diagnostics/macros.rs b/src/libsyntax/diagnostics/macros.rs
index b4bf793d4e1..3107508a96a 100644
--- a/src/libsyntax/diagnostics/macros.rs
+++ b/src/libsyntax/diagnostics/macros.rs
@@ -11,44 +11,45 @@
 #![macro_escape]
 
 #[macro_export]
-macro_rules! register_diagnostic(
-    ($code:tt, $description:tt) => (__register_diagnostic!($code, $description));
-    ($code:tt) => (__register_diagnostic!($code))
-)
+macro_rules! register_diagnostic {
+    ($code:tt, $description:tt) => (__register_diagnostic! { $code, $description });
+    ($code:tt) => (__register_diagnostic! { $code })
+}
 
 #[macro_export]
-macro_rules! span_err(
+macro_rules! span_err {
     ($session:expr, $span:expr, $code:ident, $($message:tt)*) => ({
         __diagnostic_used!($code);
         $session.span_err_with_code($span, format!($($message)*).as_slice(), stringify!($code))
     })
-)
+}
 
 #[macro_export]
-macro_rules! span_warn(
+macro_rules! span_warn {
     ($session:expr, $span:expr, $code:ident, $($message:tt)*) => ({
         __diagnostic_used!($code);
         $session.span_warn_with_code($span, format!($($message)*).as_slice(), stringify!($code))
     })
-)
+}
 
 #[macro_export]
-macro_rules! span_note(
+macro_rules! span_note {
     ($session:expr, $span:expr, $($message:tt)*) => ({
         ($session).span_note($span, format!($($message)*).as_slice())
     })
-)
+}
 
 #[macro_export]
-macro_rules! span_help(
+macro_rules! span_help {
     ($session:expr, $span:expr, $($message:tt)*) => ({
         ($session).span_help($span, format!($($message)*).as_slice())
     })
-)
+}
 
 #[macro_export]
-macro_rules! register_diagnostics(
+macro_rules! register_diagnostics {
     ($($code:tt),*) => (
-        $(register_diagnostic!($code))*
+        $(register_diagnostic! { $code })*
     )
-)
+}
+
diff --git a/src/libsyntax/diagnostics/plugin.rs b/src/libsyntax/diagnostics/plugin.rs
index cb2a1f8acd8..bcce5538314 100644
--- a/src/libsyntax/diagnostics/plugin.rs
+++ b/src/libsyntax/diagnostics/plugin.rs
@@ -18,12 +18,16 @@ use ext::build::AstBuilder;
 use parse::token;
 use ptr::P;
 
-thread_local!(static REGISTERED_DIAGNOSTICS: RefCell<HashMap<Name, Option<Name>>> = {
-    RefCell::new(HashMap::new())
-})
-thread_local!(static USED_DIAGNOSTICS: RefCell<HashMap<Name, Span>> = {
-    RefCell::new(HashMap::new())
-})
+thread_local! {
+    static REGISTERED_DIAGNOSTICS: RefCell<HashMap<Name, Option<Name>>> = {
+        RefCell::new(HashMap::new())
+    }
+}
+thread_local! {
+    static USED_DIAGNOSTICS: RefCell<HashMap<Name, Span>> = {
+        RefCell::new(HashMap::new())
+    }
+}
 
 fn with_registered_diagnostics<T, F>(f: F) -> T where
     F: FnOnce(&mut HashMap<Name, Option<Name>>) -> T,