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

[Par Kurlberg]

Hi,

This is perhaps more of a feature request than a bug report, but only
luck prevented me from being bitten badly:

When upgrading from emacs24 to emacs26 I found out the hard way that
mark-diary-entries-in-calendar has been removed, and replaced by
calendar-view-diary-initially-flag . The last week I've been puzzled
about missing a few, fortunately not too important, meetings, and
thinking "what, I thought I put that in my emacs diary file?!".  When an
upcoming important meeting, that I strongly recalled putting into the
diary, was not indicated in the calender (i.e., the days are usually
marked by red) I started digging and found out about the now completely
obselete variable.

Of course, in theory I've been amply warned - the documentation states
"mark-diary-entries-in-calendar is obsolete since 23.1".  However, given
that anyone who relies on keeping track of meetings via
emacs/diary/calender easily might miss a few meetings before noticing
this, perhaps emacs26+ could warn if mark-diary-entries-in-calendar is
true whereas calendar-view-diary-initially-flag is unset?

More generally, some sort of mechanisms for "important" upgrade warnings
on obsolete variables having been removed would be very helpful, but it
is perhaps hard to figure out / agree on exactly what are "important
enough" changes.

Best,
Pär

PS: Missing unimportant meetings is perhaps a feature rather than a
bug. :-)


In GNU Emacs 26.3 (build 2, x86_64-pc-linux-gnu, GTK+ Version 3.24.14)
 of 2020-03-26, modified by Debian built on lcy01-amd64-020
Windowing system distributor 'The X.Org Foundation', version 11.0.12008000
System Description:     Ubuntu 20.04.1 LTS