date: --date=month and --date=year return wrong date and time

[cakebaker]

With GNU date:

$ date
Mon May  1 10:36:23 AM CEST 2023
$ date --date=month
Thu Jun  1 10:36:49 AM CEST 2023
$ date --date=year
Wed May  1 10:36:56 AM CEST 2024

With uutils date:

$ cargo run date
Mon May  1 10:37:59 2023
$ cargo run date --date=month
Wed May 31 08:38:06 2023
$ cargo run date --date=year
Tue Apr 30 08:38:12 2024

The time is also incorrect when using --date=week, --date=day, --date=hour, etc.

[sylvestre]

Maybe because we hardcode
month = 30 days
https://github.com/uutils/humantime_to_duration/blob/main/src/lib.rs#LL119C1-L119C1
?

[cakebaker]

Yes, plus the year is also hardcoded as 365 days and next year is a leap year.

[wanderinglethe]

I guess, this is already a problem for minutes (leap seconds)?
Could we use something like chronoutil::RelativeDuration? Not directly, because it only supports months and not weeks, days, minutes, etc.

[jfinkels]

This is fixed after updating to parse_datetime v0.8.0:

$ TZ=UTC0 ../gnu/src/date --date=month
Fri Mar 21 11:01:46 PM UTC 2025
$ TZ=UTC0 ./target/debug/date --date=month
Fri Mar 21 23:01:54 UTC 2025
$ TZ=UTC0 ../gnu/src/date --date=year
Sat Feb 21 11:02:05 PM UTC 2026
$ TZ=UTC0 ./target/debug/date --date=year
Sat Feb 21 23:02:10 UTC 2026

(The formatting is wrong, but the date and time are correct.)