Function is_date_minus_date

datafusion/physical-expr/src/expressions/binary.rs:173–178

Returns true if both operands are Date types (Date32 or Date64) Used to detect Date - Date operations which should return Int64 (days difference)

(lhs: &DataType, rhs: &DataType)

/// Returns true if both operands are Date types (Date32 or Date64)
/// Used to detect Date - Date operations which should return Int64 (days difference)
fn is_date_minus_date(lhs: &DataType, rhs: &DataType) -> bool {
    matches!(
        (lhs, rhs),
        (DataType::Date32, DataType::Date32) | (DataType::Date64, DataType::Date64)
    )
}

/// Computes the difference between two dates and returns the result as Int64 (days)
/// This aligns with PostgreSQL, DuckDB, and MySQL behavior where date - date returns an integer