Use ExactSizeIterator in BooleanArray::from_trusted_len_iter

Author: tobixdev

arrow-array/src/array/boolean_array.rs

@@ -497,7 +497,8 @@ impl BooleanArray {
     /// # Safety
     ///
     /// The iterator must be [`TrustedLen`](https://doc.rust-lang.org/std/iter/trait.TrustedLen.html).
-    /// I.e. that `size_hint().1` correctly reports its length.
+    /// I.e. that `size_hint().1` correctly reports its length. Note that this is a stronger
+    /// guarantee that `ExactSizeIterator` provides which could still report a wrong length.
     ///
     /// # Panics
     ///
@@ -506,11 +507,9 @@ impl BooleanArray {
     pub unsafe fn from_trusted_len_iter<I, P>(iter: I) -> Self
     where
         P: Into<BooleanAdapter>,
-        I: IntoIterator<Item = P>,
+        I: ExactSizeIterator<Item = P>,
     {
-        let iter = iter.into_iter();
-        let (_, data_len) = iter.size_hint();
-        let data_len = data_len.expect("Iterator must be sized");
+        let data_len = iter.len();
 
         let num_bytes = bit_util::ceil(data_len, 8);
         let mut null_builder = MutableBuffer::from_len_zeroed(num_bytes);

arrow-array/src/builder/boolean_builder.rs

@@ -237,7 +237,7 @@ impl Extend<Option<bool>> for BooleanBuilder {
         let buffered = iter.into_iter().collect::<Vec<_>>();
         let array = unsafe {
             // SAFETY: buffered.into_iter() is a trusted length iterator
-            BooleanArray::from_trusted_len_iter(buffered)
+            BooleanArray::from_trusted_len_iter(buffered.into_iter())
         };
         self.append_array(&array)
     }

arrow/benches/array_from.rs

@@ -209,7 +209,7 @@ fn array_from_vec_benchmark(c: &mut Criterion) {
 fn gen_option_iter<TItem: Clone + 'static>(
     item: TItem,
     len: usize,
-) -> Box<dyn Iterator<Item = Option<TItem>>> {
+) -> Box<dyn ExactSizeIterator<Item = Option<TItem>>> {
     hint::black_box(Box::new(repeat_n(item, len).enumerate().map(
         |(idx, item)| {
             if idx % 3 == 0 {