parsing timezone should support Unicode "MINUS SIGN" (U+2212)

[jtmoon79]

According to Wikipedia

To represent a negative offset, ISO 8601 specifies using a minus sign, (−). If the interchange character set is limited and does not have a minus sign character, then the hyphen-minus should be used, (-). ASCII does not have a minus sign, so its hyphen-minus character (code is 45 decimal or 2D hexadecimal) would be used. If the character set has a minus sign, then that character should be used. Unicode has a minus sign, and its character code is U+2212 (2212 hexadecimal); the HTML character entity invocation is −.

Problem

chrono parse_from_str fails to parse a Unicode "minus sign" character − (U+2212).

rust playground

extern crate chrono;
use chrono::DateTime;

fn main() {
    let dt_pattern = r"%Y %b %d %H%M%S %:z";

    // use ASCII "hyphen-minus"
    let data = r"2019 Aug 30 125959 -07:00";
    let dt = DateTime::parse_from_str(data, dt_pattern);
    dbg!(&dt);

    // use Unicode "minus" character
    let data = r"2019 Aug 30 125959 −07:00";
    let dt = DateTime::parse_from_str(data, dt_pattern);
    dbg!(&dt);
}

results in output

[src/main.rs:10] &dt = Ok(
    2019-08-30T12:59:59-07:00,
)
[src/main.rs:15] &dt = Err(
    ParseError(
        Invalid,
    ),
)

(using chrono version 0.4.22).

In some circumstances, chrono users must manually transform a found "minus sign" character − to "hyphen-minus" character -.

Solution

To more fully support the ISO 8601 standard, chrono should parse Unicode "minus sign" character − (U+2212) in numeric timezone offsets, e.g. −07:00.

[djc]

I'm open to adding support for this, want to submit a PR?

I am curious, which components are dumping obscure Unicode characters in your syslog? 😄

[pitdicker]

Fixed in #1087.