Subject: bug#1501: Emacs 22 loses undo buffer

From: Noam Postavsky <[email-masked]>
Date: Wed, 21 Aug 2019 21:19:32 -0400

Stefan Kangas <[email-masked]> writes:

> Noam Postavsky <[email-masked]> writes:
>
>> Stefan Kangas <[email-masked]> writes:
>>
>> > increase in the memory usage of each undo record, especially when
>> > using font-lock-mode.  I'm not sure that is a serious problem, since
>> > memory is only getting cheaper, but it might be worth investigating.
>> > On the other hand, we could just decide that this is not worth the
>> > effort and close this as wontfix.
>>
>> Hmm, it sounds like the problem might just be due to saving text
>> properties in the undo records?  If so, maybe a simple fix is to just
>> drop them (or drop only face and font-lock-face properties).
>
> Is it not worth saving also that information?

Definitely not face, since it's overwritten as soon as font-lock runs.
It's true font-lock-face can sometimes be set manually, though usually
it's computed by font-lock rules.