Subject: bug#49631: 28.0.50; dired-hide-details-mode Probably introduced at or before Emacs version 24.4

From: Richard Stallman <[email-masked]>
Date: Tue, 20 Jul 2021 20:52:12 -0400

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  > The feature works by searching the etc/NEWS* files, and finding a
  > symbol there doesn't necessarily mean the Emacs release in which it's
  > mentioned is the actual release where the symbol was introduced.

I think we can implement an efficient, accurate, automatic way to
determine which release each function appeared in.

We could run a script on each Emacs release to find all the function
definitions in it, then make a sorted list of their names.  By
comparing these, we can find for each function the first release it
was defined in.

We only need to scan each release once, all in the same way.  We would
scan the old releases at the start, and scan each new release when it
is made, adding new functions to the records.

There could be a few functions for which that does not give correct
results, as they were defined in weird ways.  We could add those
functions manually to the records.  Since they won't be many, we could
afford to do that by hand.

Scanning a new release will never alter the information about
functions in previous releases, so once we have fixed an exception, it
will stay fixed.

We don't have to include these records in the release.  It's enough to
compare them with the results of checking the NEWS files.  Then
generate a file listing the exceptions: functions whose first release
differs from the result obtained by checking NEWS files.  It should be
short.

help-fns--first-release could check that file of exceptions first.

Then it could state its results as exact, not an approximation.

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