Expand nested items within a backtrace.

Fixes a regression from #4913 which causes items to be exanded with spans lacking expn_info from the context's current backtrace.

1 files changed, 8 insertions, 0 deletions

diff --git a/src/libsyntax/util/small_vector.rs b/src/libsyntax/util/small_vector.rs
index 9eb9871bb21..f15b7dd5563 100644
--- a/src/libsyntax/util/small_vector.rs
+++ b/src/libsyntax/util/small_vector.rs
@@ -39,6 +39,14 @@ impl<T> FromIterator<T> for SmallVector<T> {
     }
 }
 
+impl<T> Extendable<T> for SmallVector<T> {
+    fn extend<I: Iterator<T>>(&mut self, iter: &mut I) {
+        for val in *iter {
+            self.push(val);
+        }
+    }
+}
+
 impl<T> SmallVector<T> {
     pub fn zero() -> SmallVector<T> {
         Zero