fix: fix boolean inline constant decoding

rust/lance-arrow/src/scalar.rs

@@ -141,20 +141,28 @@ pub fn decode_scalar_from_inline_value(
     data_type: &DataType,
     inline_value: &[u8],
 ) -> Result<ArrayRef> {
-    let byte_width = data_type.byte_width_opt().ok_or_else(|| {
-        ArrowError::InvalidArgumentError(format!(
-            "Inline constant is not supported for non-fixed-stride data type {:?}",
-            data_type
-        ))
-    })?;
-
-    if inline_value.len() != byte_width {
-        return Err(ArrowError::InvalidArgumentError(format!(
+    // I expect our input to be safe here, but I added some debug_assert_eq statements just in case.
+    // If they are triggered, we may need to change them to return actual errors.
+    //
+    // Boolean values are bit-packed in Arrow and therefore are not "fixed-stride" in bytes.
+    // As a result, `byte_width_opt()` returns `None` for `DataType::Boolean`, even though a
+    // length-1 scalar can be represented inline using a single byte (matching `try_inline_value`).
+    if matches!(data_type, DataType::Boolean) {
+        debug_assert_eq!(
+            inline_value.len(),
+            1,
+            "Invalid boolean inline scalar length (expected 1 byte, got {})",
+            inline_value.len()
+        );
+    } else if let Some(byte_width) = data_type.byte_width_opt() {
+        debug_assert_eq!(
+            inline_value.len(),
+            byte_width,
             "Inline constant length mismatch for {:?}: expected {} bytes but got {}",
             data_type,
             byte_width,
             inline_value.len()
-        )));
+        );
     }
 
     let data = ArrayDataBuilder::new(data_type.clone())
@@ -187,7 +195,7 @@ pub fn try_inline_value(scalar: &ArrayRef) -> Option<Vec<u8>> {
 mod tests {
     use std::sync::Arc;
 
-    use arrow_array::{cast::AsArray, FixedSizeBinaryArray, Int32Array, StringArray};
+    use arrow_array::{cast::AsArray, BooleanArray, FixedSizeBinaryArray, Int32Array, StringArray};
 
     use super::*;
 
@@ -231,6 +239,16 @@ mod tests {
         assert_eq!(decoded.as_fixed_size_binary().value(0), val.as_slice());
     }
 
+    #[test]
+    fn test_inline_value_boolean_round_trip() {
+        let scalar: ArrayRef = Arc::new(BooleanArray::from_iter([Some(true)]));
+        let inline = try_inline_value(&scalar).unwrap();
+        let decoded = decode_scalar_from_inline_value(&DataType::Boolean, &inline).unwrap();
+        assert_eq!(decoded.len(), 1);
+        assert_eq!(decoded.null_count(), 0);
+        assert!(decoded.as_boolean().value(0));
+    }
+
     #[test]
     fn test_scalar_value_buffer_rejects_nested_type() {
         let field = Arc::new(arrow_schema::Field::new("item", DataType::Int32, false));

rust/lance/src/dataset/tests/dataset_io.rs

@@ -22,8 +22,8 @@ use arrow_array::RecordBatchReader;
 use arrow_array::{
     cast::as_string_array,
     types::{Float32Type, Int32Type},
-    ArrayRef, Int32Array, Int64Array, Int8Array, Int8DictionaryArray, RecordBatchIterator,
-    StringArray,
+    ArrayRef, BooleanArray, Int32Array, Int64Array, Int8Array, Int8DictionaryArray,
+    RecordBatchIterator, StringArray,
 };
 use arrow_array::{Array, FixedSizeListArray, Int16Array, Int16DictionaryArray, StructArray};
 use arrow_ord::sort::sort_to_indices;
@@ -178,6 +178,58 @@ async fn test_create_and_fill_empty_dataset(
     assert_eq!(&expected_struct_arr, as_struct_array(sorted_arr.as_ref()));
 }
 
+#[tokio::test]
+async fn test_scan_constant_boolean_inline_value_v2_2() {
+    let test_uri = TempStrDir::default();
+    let schema = Arc::new(ArrowSchema::new(vec![ArrowField::new(
+        "flag",
+        DataType::Boolean,
+        false,
+    )]));
+
+    let rows = 1024usize;
+    let flags: ArrayRef = Arc::new(BooleanArray::from_iter(std::iter::repeat_n(true, rows)));
+    let batch = RecordBatch::try_new(schema.clone(), vec![flags]).unwrap();
+    let reader = RecordBatchIterator::new(vec![Ok(batch)].into_iter(), schema.clone());
+
+    Dataset::write(
+        reader,
+        &test_uri,
+        Some(WriteParams {
+            data_storage_version: Some(LanceFileVersion::V2_2),
+            ..Default::default()
+        }),
+    )
+    .await
+    .unwrap();
+
+    let ds = Dataset::open(&test_uri).await.unwrap();
+    let batches = ds
+        .scan()
+        .project(&["flag"])
+        .unwrap()
+        .try_into_stream()
+        .await
+        .unwrap()
+        .try_collect::<Vec<_>>()
+        .await
+        .unwrap();
+
+    let total_rows: usize = batches.iter().map(|b| b.num_rows()).sum();
+    assert_eq!(total_rows, rows);
+    for batch in batches {
+        let flags = batch
+            .column_by_name("flag")
+            .unwrap()
+            .as_any()
+            .downcast_ref::<BooleanArray>()
+            .unwrap();
+        for i in 0..flags.len() {
+            assert!(flags.value(i));
+        }
+    }
+}
+
 #[rstest]
 #[lance_test_macros::test(tokio::test)]
 async fn test_create_with_empty_iter(