Function column_union

src/transform/src/typecheck.rs:509–520

Unions `other` into `typ`, returning a list of differences on failure This function returns an empty list when `typ` and `other` are a union

(
    typ: &mut ReprColumnType,
    other: &ReprColumnType,
)

///
/// This function returns an empty list when `typ` and `other` are a union
pub fn column_union(
    typ: &mut ReprColumnType,
    other: &ReprColumnType,
) -> Vec<ReprColumnTypeDifference> {
    let diffs = scalar_union(&mut typ.scalar_type, &other.scalar_type);

    if diffs.is_empty() {
        typ.nullable |= other.nullable;
    }

    diffs
}

/// Returns true when it is safe to treat a `sub` row as an `sup` row
///