Subject: bug#5312: Why is ‘show-trailing-whitespace’ considered unsafe?

From: Stefan Monnier <[email-masked]>
Date: Wed, 06 Jan 2010 09:24:03 -0500

>>> I find it inconvenient since adding it to a per-file or per-directory
>>> local variable list will (by default) ask users whether they want to
>>> apply the dreaded setting.
>> Arguably this var is more a personal user preference than a property of
>> a file, so maybe the lack of a `safe-local-variable' property is
>> actually a feature ;-0
> Yeah, I see what you mean.  OTOH the same could be said of, say,
> ‘indent-tabs-mode’, which /is/ safe.  I don’t find
> ‘show-trailing-whitespace’ any different.

You might be right.  But I do know of several file formats where TABs
are seriously problematic so you could argue that indent-tabs-mode in
those files is linked to the file's content rather than some mere
user preference.
Of course, maybe you can come up with file formats where trailing
whitespaces are seriously problematic as well.  I just can't think of
any off the top of my head.

        Stefan