jonasdedden opened a new issue, #51613:
URL: https://github.com/apache/arrow/issues/51613
### Describe the bug, including details regarding any error messages,
version, and platform.
`ListArray::FromListView` (and `LargeListArray::FromListView`) returns the
wrong validity for a sliced list-view array with nulls.
```cpp
auto views = arrow::json::ArrayFromJSONString(
arrow::list_view(arrow::int32()),
"[[1], [2], [3], [4], [5], [6], [7], [8], null, [10],
[11]]")
.ValueOrDie();
auto sliced =
std::static_pointer_cast<arrow::ListViewArray>(views->Slice(1));
auto lists =
arrow::ListArray::FromListView(*sliced,
arrow::default_memory_pool()).ValueOrDie();
// is null (list view): 0 0 0 0 0 0 0 1 0 0
// is null (list): 0 0 1 1 1 1 1 1 1 1
```
Expected: the same nulls as the input.
In `ListFromListViewImpl` (`cpp/src/arrow/array/array_nested.cc`), the
validity bitmap is read with `list_view_data->GetValues<uint8_t>(0)`, which
already advances the pointer by `offset` *bytes*. It is then passed to
`bit_util::GetBit(in_validity_bitmap, list_view_data->offset + i)`, which
applies the offset again, in bits. `FlattenListViewArray` in the same file does
this correctly with `GetValues<uint8_t>(0, 0)`.
Found while trying to use `FromListView` in a compute kernel (GH-33295).
Related: GH-51612, where the `list_view` to `list` cast could use
`FromListView`. Reproduced on current `main`, Linux x86_64.
### Component(s)
C++
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