Optimize IntoIter::extend for the likely-empty case.

Gankra · Aug 23, 2022 · 522d47f · 522d47f
1 parent ae882f2
commit 522d47f
Showing 1 changed file with 4 additions and 1 deletion.
diff --git a/src/lib.rs b/src/lib.rs
@@ -1135,7 +1135,10 @@ impl<T> Extend<T> for ThinVec<T> {
         I: IntoIterator<Item = T>,
     {
         let iter = iter.into_iter();
-        self.reserve(iter.size_hint().0);
+        let hint = iter.size_hint().0;
+        if hint > 0 {
+            self.reserve(hint);
+        }
         for x in iter {
             self.push(x);
         }