1 files changed, 6 insertions, 0 deletions
diff --git a/compiler/rustc_index/src/bit_set.rs b/compiler/rustc_index/src/bit_set.rs
index 5aa213cb701..cf86c450a5b 100644
--- a/compiler/rustc_index/src/bit_set.rs
+++ b/compiler/rustc_index/src/bit_set.rs
@@ -938,6 +938,12 @@ pub struct GrowableBitSet<T: Idx> {
     bit_set: BitSet<T>,
 }
 
+impl<T: Idx> Default for GrowableBitSet<T> {
+    fn default() -> Self {
+        GrowableBitSet::new_empty()
+    }
+}
+
 impl<T: Idx> GrowableBitSet<T> {
     /// Ensure that the set can hold at least `min_domain_size` elements.
     pub fn ensure(&mut self, min_domain_size: usize) {