Years greater than 9999 require a + at the beginning in NaiveDateTime::parse_from_str

[ethowitz]

Description
When calling NaiveDateTime::parse_from_str, years greater than 9999 require a + sign at the beginning. I didn't see this in the documentation for that function or in the documentation for chrono::format::strftime, though I do see that it's documented for Numeric::Year, which strftime appears to use internally. I wasn't sure if this was expected behavior, but I wanted to bring it to your attention. Thanks!

Minimal example
https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&gist=ecc55c3483a582e866c5bf5ae51d8325

use chrono::NaiveDateTime;

const FORMAT_STRING: &str = "%Y-%m-%d %H:%M:%S%.f";

fn main() {
    assert!(NaiveDateTime::parse_from_str("9999-01-01 12:34:56", FORMAT_STRING).is_ok());
    assert!(NaiveDateTime::parse_from_str("10000-01-01 12:34:56", FORMAT_STRING).is_err());
    assert!(NaiveDateTime::parse_from_str("+10000-01-01 12:34:56", FORMAT_STRING).is_ok());
}

Versions

• rustc 1.64.0-nightly
• chrono 0.4.21

[esheppa]

Thanks for the question @ethowitz - this is intended behaviour to conform with ISO8601 - essentially the standard primarily supports years 1583 through 9999, but wider ranges can be used, however five-digit and above years require either a - or + prefix. There is further detail at https://en.wikipedia.org/wiki/ISO_8601#Years

[c-git]

Thanks for the question @ethowitz - this is intended behaviour to conform with ISO8601 - essentially the standard primarily supports years 1583 through 9999, but wider ranges can be used, however five-digit and above years require either a - or + prefix. There is further detail at https://en.wikipedia.org/wiki/ISO_8601#Years

Would it be ok to just add a note to the docs for this function as well to help future users?

I can try to write a PR if this is something desirable.

[djc]

Yeah, documentation improvements for this would be great, thanks!

[c-git]

Ok submitted a PR for the docs, happy to add or remove as you see fit. Added the (+/-) for consistency with what I added to the format information. Can remove both if it is not desirable.

[c-git]

Closed the old pull request and create a new one because I needed to target 0.4.x and had originally started from main.