bug#43537: 26.3; "lost" diary entries - mark-diary-entries-in-calendar obsolete

[Richard Stallman <rms@gnu.org>]

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  > Yeah, I don't think this is generally possible.  The variable in
  > question was obsoleted about a decade ago, which should be sufficient
  > time for people to adjust.  Adding more code to Emacs to warn people
  > about things happening that far in the past would not be productive use
  > of our time.

The event that causes these problems to happen _now_
was the deletion of the variable, which we did recently.
Given that the problems that result are silent and mysterious,
we should look for ways to help the people affected,
not reasons to justify not doing so.

One way would be to check, after loading the init files,
whether that variable exists.  If it does, pop up buffer
to call users' attention to the problem, with advice.
We could put that in Emacs 27.2, and remove it in Emacs 29.

That is the fix that occurred to me.  It is pretty easy.
If someone finds a better fix, by all means let's use that.
But there is no reason to even considered doing nothing about this.

-- 
Dr Richard Stallman
Chief GNUisance of the GNU Project (https://gnu.org)
Founder, Free Software Foundation (https://fsf.org)
Internet Hall-of-Famer (https://internethalloffame.org)