Function parse_interval_day_duration 

fn parse_interval_day_duration(
    duration_str: &str,
    precision: SupportedPrecision,
    span: Span<'_>,
) -> Result<IntervalDayToSecond, MessageParseError>

Parse the contents of an interval_day literal string - e.g. “5d”, “4d 5s”, “5d 3s 100ns”, “-5d -3s” - into an IntervalDayToSecond with the sub-second precision taken from the literal’s type ascription.