Fix skipped items in extend/from_iter/collect.

Fixes #365.

src/lib.rs

@@ -1520,6 +1520,7 @@ impl<T, const N: usize> SmallVec<T, N> {
                 // At this point we either consumed all capacity or the iterator is exhausted (fused)
                 if let Some(item) = iter.next() {
                     self.push(item);
+                    len += 1;
                 } else {
                     return;
                 }

src/tests.rs

@@ -1151,6 +1151,15 @@ fn collect_from_iter() {
     let _y: SmallVec<u8, 1> = SmallVec::from_iter(iter);
 }
 
+#[test]
+fn test_collect_with_spill() {
+    let input = "0123456";
+    let collected: SmallVec<char, 4> = input
+        .chars()
+        .collect();
+    assert_eq!(collected, &['0', '1', '2', '3', '4', '5', '6']);
+}
+
 #[test]
 fn test_spare_capacity_mut() {
     let mut v: SmallVec<u8, 2> = SmallVec::new();