bug#74848: [PATCH] calendar: check for presuppositions in `calendar-date-is-valid-p'

[Eli Zaretskii]

> From: Richard Lawrence <rwl@recursewithless.net>
> Date: Fri, 13 Dec 2024 13:02:36 +0100
> 
> Here is a patch to make calendar-date-is-valid-p return nil, instead of
> signaling an error, when it is passed a value that isn't a list of the
> form (MONTH DAY YEAR).
> 
> This (a) makes the function a proper predicate, as its name suggests,
> which (b) is necessary in some of the new iCalendar code I've been
> working on (to be posted soon).

Thanks.

> This is my first time submitting a patch with submit-emacs-patch, so
> please let me know if I did anything wrong.

The commit log message should include the file and the function(s)
where the changes are done, as well as a short description of the
changes.  See CONTRIBUTE for more details, and see "git log" for the
examples of how we format commit log messages.  Please don't forget to
mention the bug number in the commit log message.

P.S. I presume you've run the relevant parts of the test suite and
verified that they still succeed.  If not, please do.