IPC reader fails to decode a struct array with zero fields

[kawadakk]

Describe the bug
Encoding succeeds, but decoding fails with an error InvalidArgumentError("all columns in a record batch must have the specified row count").

To Reproduce

// add to arrow-ipc/src/writer.rs
#[test]
fn ipc_struct_array_with_zero_fields() {
    let record_batch = {
        let struct_ty = DataType::Struct(Vec::<Field>::new().into());
        let structs = ArrayDataBuilder::new(struct_ty.clone())
            .len(3)
            .build()
            .unwrap();
        RecordBatch::try_new_with_options(
            Arc::new(Schema::new(vec![Field::new("field", struct_ty, false)])),
            vec![make_array(structs)],
            &RecordBatchOptions::new().with_row_count(Some(3)),
        )
        .unwrap()
    };
    let deserialized_batch = deserialize(serialize(&record_batch));

    let structs = deserialized_batch
        .column(0)
        .as_any()
        .downcast_ref::<StructArray>()
        .unwrap();

    assert_eq!(structs.len(), 3);
}

thread 'writer::tests::ipc_struct_array_with_zero_fields' panicked at 'called `Result::unwrap()` on an `Err` value: InvalidArgumentError("all columns in a record batch must have the specified row count")', arrow-ipc\src\writer.rs:1816:39
stack backtrace:
   0: rust_begin_unwind
             at /rustc/864bdf7843e1ceabc824ed86d97006acad6af643/library\std\src/panicking.rs:617:5
   1: core::panicking::panic_fmt
             at /rustc/864bdf7843e1ceabc824ed86d97006acad6af643/library\core\src/panicking.rs:67:14
   2: core::result::unwrap_failed
             at /rustc/864bdf7843e1ceabc824ed86d97006acad6af643/library\core\src/result.rs:1651:5
   3: core::result::Result<T,E>::unwrap
             at /rustc/864bdf7843e1ceabc824ed86d97006acad6af643\library\core\src/result.rs:1076:23
   4: arrow_ipc::writer::tests::deserialize
             at .\src\writer.rs:1816:9
   5: arrow_ipc::writer::tests::ipc_struct_array_with_zero_fields
             at .\src\writer.rs:1976:34
   6: arrow_ipc::writer::tests::ipc_struct_array_with_zero_fields::{{closure}}
             at .\src\writer.rs:1962:44
   7: core::ops::function::FnOnce::call_once
             at /rustc/864bdf7843e1ceabc824ed86d97006acad6af643\library\core\src\ops/function.rs:250:5
   8: core::ops::function::FnOnce::call_once
             at /rustc/864bdf7843e1ceabc824ed86d97006acad6af643/library\core\src\ops/function.rs:250:5

Expected behavior
Successful roundtrip conversion

Additional context

[jackwener]

When deserialize

fn try_new_impl(
        schema: SchemaRef,
        columns: Vec<ArrayRef>,
        options: &RecordBatchOptions,
    )

column in columns len is 0.
options.rowcount is 3

[hiltontj]

Should the expected behaviour be that it fails to encode the data in the first place? (instead of roundtrip conversion)

Or, is it possible for the reader to decode the struct array without knowledge of what fields it has?

[kawadakk]

If it can decode a struct array with a non-zero number of fields, it should be able to decode one with zero fields as well.

[kawadakk]

I opened a PR: #5918