Incorrect handling when clocks are moved backward?

[breezewish]

Consider 06 November, 2011 01:59:59 AM in America/Los_Angeles:

let tz: chrono_tz::Tz = "America/Los_Angeles".parse().unwrap();
let dt = tz.ymd_opt(2011, 11, 6).and_hms_opt(1, 59, 59);
println!("{:?}", dt);

According to time zone information:

After Sunday, 06 November, 2011 01:59:59 AM:
Clocks were moved backward to become Sunday, 06 November, 2011 01:00:00 AM

So 06 November, 2011 01:59:59 is ambiguous, but the output is None.

[breezewish]

Also, when using local, the problem does not exist:

    let t = Local.ymd_opt(1988, 09, 10).and_hms_opt(23, 59, 59);
    println!("{}", t.unwrap().timestamp());

    let tz: Tz = "Asia/Shanghai".parse().unwrap();
    let t = tz.ymd_opt(1988, 09, 10).and_hms_opt(23, 59, 59);
    println!("{}", t.unwrap().timestamp());

My time zone is Asia/Shanghai and the first one will success and the second one will fail.

[breezewish]

A friendly ping

[kennytm]

This issue has nothing to do with chrono-tz, the implementation properly returns LocalResult::Ambiguous. The problem is that chrono's implementation of LocalResult::and_hms_opt discards the Ambiguous result.

Local "works" because Local never returns anything besides LocalResult::Single, even in case of non-existing time (due to the tm → time_t → tm roundtrip):

use chrono::*;

fn main() {
	let dt1 = chrono_tz::America::Los_Angeles.ymd_opt(2018, 3, 11).and_hms_opt(2, 15, 0);
	let dt2 = Local.ymd_opt(2018, 3, 11).and_hms_opt(2, 15, 0);
	println!("{:?}", dt1);
        // None 👌 
	println!("{:?}", dt2);
        // Single(2018-03-11T03:15:00-07:00) 😕 
}

[sparky8251]

This seems related to my issue, chrono #318. I found other related issues around this as well.