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The following commit(s) were added to refs/heads/main by this push:
new 0413c017e0 fix(arrow-cast): preserve length when casting zero-width
FixedSizeListArray (#11043)
0413c017e0 is described below
commit 0413c017e093b989e61692f277ae6ea78125d97c
Author: RIchard Baah <[email protected]>
AuthorDate: Tue Sep 15 01:03:49 2026 -0400
fix(arrow-cast): preserve length when casting zero-width FixedSizeListArray
(#11043)
# Which issue does this PR close?
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- Closes None.
# Rationale for this change
`try_new` can't infer length when size == 0 (0 / 0 is ambiguous), so
route through `try_new_with_length` in that case.
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in the issue then this section is not needed.
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# What changes are included in this PR?
Branch on `size == 0 && nulls.is_none()` to pass length explicitly;
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is sometimes worth providing a summary of the individual changes in this
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# Are these changes tested?
yes, added a regression test
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# Are there any user-facing changes?
no
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---
arrow-cast/src/cast/mod.rs | 27 +++++++++++++++++++++++++--
1 file changed, 25 insertions(+), 2 deletions(-)
diff --git a/arrow-cast/src/cast/mod.rs b/arrow-cast/src/cast/mod.rs
index 03abb14d27..c0e5327c1d 100644
--- a/arrow-cast/src/cast/mod.rs
+++ b/arrow-cast/src/cast/mod.rs
@@ -870,11 +870,14 @@ pub fn cast_with_options(
}
let array = array.as_fixed_size_list();
let values = cast_with_options(array.values(),
list_to.data_type(), cast_options)?;
- Ok(Arc::new(FixedSizeListArray::try_new(
+ let nulls = array.nulls().cloned();
+ let len = array.len();
+ Ok(Arc::new(FixedSizeListArray::try_new_with_length(
list_to.clone(),
*size_from,
values,
- array.nulls().cloned(),
+ nulls,
+ len,
)?))
}
(ListView(_), ListView(to)) => cast_list_view_values::<i32>(array, to,
cast_options),
@@ -9395,6 +9398,26 @@ mod tests {
assert_eq!(946684800000, c.value(5));
}
+ #[test]
+ fn test_cast_zero_width_fsl_to_fsl() {
+ // size=0 FSL with no nulls: length cannot be inferred from the child
buffer
+ // (0 bytes / 0 = ambiguous), so the cast must preserve it explicitly.
+ let field = Arc::new(Field::new_list_field(DataType::Int32, true));
+ let input = FixedSizeListArray::try_new_with_length(
+ field,
+ 0,
+ Arc::new(Int32Array::new_null(0)),
+ None,
+ 3,
+ )
+ .unwrap();
+ let to_type =
+
DataType::FixedSizeList(Arc::new(Field::new_list_field(DataType::Int64, true)),
0);
+ let result = cast(&(Arc::new(input) as ArrayRef), &to_type).unwrap();
+ assert_eq!(result.len(), 3);
+ assert_eq!(result.data_type(), &to_type);
+ }
+
#[test]
#[cfg_attr(miri, ignore)] // Unsupported inline assembly
fn test_can_cast_fsl_to_fsl() {
