ISO8601 strings starting with + or - can't be parsed

[l0drex]

Describe the bug A clear and concise description of what the bug is. ISO8601 strings can start with a + or - for dates after or before the year 0. Passing such strings to DateTime.fromISO() results in an invalid date.

To Reproduce Please share a minimal code example that triggers the problem:

DateTime.fromISO("+1923-01-25T18:51:29Z")

Actual vs Expected behavior A clear and concise description of what you expected to happen. With a +, dates should be parsed exactly as without one. Starting with a -, the date object should correspond to a time after year 0.

Desktop (please complete the following information):

• OS: [e.g. iOS] Linux
• Browser [e.g. Chrome 84, safari 14.0] Firefox
• Luxon version [e.g. 1.25.0] 3.3.1
• Your timezone [e.g. "America/New_York"] Europe/Berlin

Additional context Add any other context about the problem here.

https://en.wikipedia.org/wiki/ISO_8601

Happens with the Javascript Date constructor as well:

new Date("+1923-01-25T18:51:29Z")

[diesieben07]

ISO 8601 does not directly permit the use of a sign for the year, "only by prior agreement between the sender and the receiver". As such this should be an option for fromISO at most, defaulting to false.

[icambron]

I think you're both misreading it a little. The important part is the number of extra year digits:

An expanded year representation [±YYYYY] must have an agreed-upon number of extra year digits beyond the four-digit minimum, and it must be prefixed with a + or − sign[21] instead of the more common AD/BC (or CE/BCE) notation; by convention 1 BC is labelled +0000, 2 BC is labeled −0001, and so on.

Luxon supports plus and minus with 6 digits, so you can say +001923 or -000234, etc

[l0drex]

Oh ok, I see. I am currently working with gedcomx dates, which are very similar to the ISO standard and got confused.