BUG #19650: to_date()/to_timestamp() silently truncate 4+-digit day-of-year input to the first three digits

The following bug has been logged on the website:

Bug reference: 19650
Logged by: chunling qin
Email address: 303677365(at)qq(dot)com
PostgreSQL version: 18.6
Operating system: x86_64
Description:

The documentation states that DDD (day of year) accepts values 001-366 and
IDDD (ISO day of year) 001-371, and out-of-range values raise an error. That
check works for 3-digit input, but for input of 4 or more digits the parser
silently keeps only the first three digits and treats them as a valid day
number:

SELECT to_date('2024 1000', 'YYYY DDDD');
-- 2024-04-09 (parsed as day 100 — the first three digits)

SELECT to_date('2024 1234', 'YYYY DDDD');
-- 2024-05-02 (parsed as day 123)

SELECT to_date('2024 10000', 'YYYY DDDD');
-- 2024-04-09 (5-digit input, still day 100)

SELECT to_date('2024 999', 'IYYY IDDD');
-- 2026-09-25 (IDDD 999 silently accepted; an ISO year has at most 371
days)

```
hunt@(null)=# SELECT to_date('2024 1000', 'YYYY DDDD');
-- 2024-04-09 (parsed as day 100 — the first three digits)

SELECT to_date('2024 1234', 'YYYY DDDD');
-- 2024-05-02 (parsed as day 123)

SELECT to_date('2024 10000', 'YYYY DDDD');
-- 2024-04-09 (5-digit input, still day 100)

SELECT to_date('2024 999', 'IYYY IDDD');
-- 2026-09-25 (IDDD 999 silently accepted; an ISO year has at most 371
days)
to_date
------------
2024-04-09
(1 row)

to_date
------------
2024-05-02
(1 row)

to_date
------------
2024-04-09
(1 row)

to_date
------------
2026-09-25
(1 row)

hunt@(null)=# SELECT to_date('2024 367', 'YYYY DDD');
-- ERROR: date/time field value out of range: "2024 367"
ERROR: date/time field value out of range: "2024 367"
```