[Remind-Fans] issue warnings for impossible UNTIL ranges

[Dianne Skoll]

On Wed, 2 Mar 2022 01:39:32 -0500
"Ian! D. Allen via Remind-fans" <remind-fans at lists.skoll.ca> wrote:

> Could remind be coaxed into issuing a warning for impossible constant
> date "UNTIL" and "THROUGH" ranges such as:

>     REM Mar  1 2022 *1 UNTIL Mar 30 2021 MSG test

> I recognize that some calculated dates may legitimately produce start
> dates after end dates, but no constant date strings should do this and
> I'd love to have a way for remind to tell me I made an error.

Hmm, ok.  I'll think about this.  The general case is tricky; for example,
this is impossible:

     REM Mon 2022 UNTIL Dec 31 2021 MSG oops....

but diagnosing it is not easy because Remind has no concept of "the
earliest possible trigger date".  Its algorithm only computes "the
next possible trigger date".

For the specific case of a start date followed by a *N (or
equivalently a start date followed by a THROUGH) I could probably
issue a diagnostic.

Regards,

Dianne.