Children of nullable Struct may have null values propagated to zone maps #9205

use vortex::VortexSessionDefault;
use vortex::array::IntoArray;
use vortex::array::arrays::BoolArray;
use vortex::array::arrays::StructArray;
use vortex::array::expr::get_item;
use vortex::array::expr::is_null;
use vortex::array::expr::root;
use vortex::array::stream::ArrayStreamExt;
use vortex::array::validity::Validity;
use vortex::buffer::ByteBufferMut;
use vortex::buffer::buffer;
use vortex::dtype::FieldNames;
use vortex::error::VortexResult;
use vortex::file::OpenOptionsSessionExt;
use vortex::file::WriteOptionsSessionExt;
use vortex::session::VortexSession;

#[tokio::main]
async fn main() -> VortexResult<()> {
    let session = VortexSession::default();

    let nullable_struct = StructArray::try_new(
        FieldNames::from(["a"]),
        vec![buffer![1i32, 2].into_array()],
        2,
        Validity::Array(BoolArray::from_iter([true, false]).into_array()),
    )?;
    let st = StructArray::try_new(
        FieldNames::from(["s"]),
        vec![nullable_struct.into_array()],
        2,
        Validity::NonNullable,
    )?
    .into_array();

    let expr = is_null(get_item("a", get_item("s", root())));
    println!(
        "in-memory is_null(s.a): {}",
        st.clone().apply(&expr)?.display_values()
    );

    let mut buf = ByteBufferMut::empty();
    session
        .write_options()
        .write(&mut buf, st.to_array_stream())
        .await?;
    let file = session.open_options().open_buffer(buf)?;

    let projected = file
        .scan()?
        .with_projection(get_item("a", get_item("s", root())))
        .into_array_stream()?
        .read_all()
        .await?;
    println!("file scan, projected s.a: {}", projected.display_values());

    let filtered = file
        .scan()?
        .with_filter(expr)
        .into_array_stream()?
        .read_all()
        .await?;
    println!(
        "file scan, filter is_null(s.a): {} rows (expected 1)",
        filtered.len()
    );

    Ok(())
}