`date -Is` is failing

[hawav]

$ date -Is
error: invalid value 's' for '--iso-8601 [<FMT>]'
  [possible values: date, hour, hours, minute, minutes, second, seconds, ns]

  tip: a similar value exists: 'second'

For more information, try '--help'.

With GNU:

2023-04-16T03:42:07+00:00

[Ideflop]

The same with :

$ uu-date -Id
error: invalid value 'd' for '--iso-8601 [<FMT>]'
  [possible values: date, hour, hours, minute, minutes, second, seconds, s, ns]

  tip: a similar value exists: 'date'

For more information, try '--help'.

$ uu-date -Ih
error: invalid value 'h' for '--iso-8601 [<FMT>]'
  [possible values: date, hour, hours, minute, minutes, second, seconds, s, ns]

  tip: a similar value exists: 'hour'

For more information, try '--help'.

$ uu-date -Im
error: invalid value 'm' for '--iso-8601 [<FMT>]'
  [possible values: date, hour, hours, minute, minutes, second, seconds, s, ns]

  tip: a similar value exists: 'minute'

For more information, try '--help'.

But it works with GNU :

$ date -Id
2023-04-16

$ date -Ih
2023-04-16T10+02:00

$ date -Im
2023-04-16T10:58+02:00

[cakebaker]

This issue probably affects all utils with args using clap's value_parser with a list of allowed values. clap only recognizes the exact values whereas GNU recognizes shortcuts as long as they are unambiguous (for example, date -Id, date -Ida, and date -Idat are all valid shortcuts for date -Idate).

[tertsdiepraam]

Maybe the best solution here is to add a valueparser to uucore that does this automatically? Then we can use that in all utils. This is also one of the issues I tried to fix with my argument parser, but work on that has stalled a bit at the moment.