bug#27066: 25.1; dired unsafe variables

["Francesco Potortì" <pot@gnu.org>]

>> Date: Thu, 25 May 2017 17:54:50 +0200
>> From: Francesco Potortì <pot@gnu.org>
>> Cc: 27066@debbugs.gnu.org
>> 
>> >I'm not sure why this is deemed a bug: you have a .dir-locals.el file
>> >in that directory, which specifies directory-local variables.  What
>> >exactly is the problem with the prompt?
>> 
>> I have not created that file myself (downloaded the source code from
>> Github), and before reading your answer I did not know about the
>> existence of .dir-locals.el files which get loaded automatically. I
>> can't find the "dir-local" string anywhere either in the Emacs or Elisp
>> manuals.
>
>How did you search?  Typing "i directory-local RET" lands me on the
>right place, as does "C-s dir-local" followed by C-s enough times.

Hm.  It turns out that Debian, for some reason, did not update my dir
info file after installing emacs25 side-by-side with emacs22, so I was
reading emacs22 docs.  Sorry for the inaccurate info.

>> Moreover the warning message does not mention .dir-locals.el
>> anywhere. 
>> 
>> So first, there is a documentation problem about the .dir-locals.el
>> files.
>
>Please suggest how to improve the existing docs.

The warning message should not say that risky variables are present in the
directory: that makes sense only if you know where to look.  When
reading that message, I thought about some bug somewhere.

The warning message should name the file where the offending variables
were found, instead.

>> Second, probably dired should prompt *before* ever loading that file and
>> parse it only if the user agrees.  Am I too conservative?
>
>I think you are too conservative.  We treat directory-local variables
>like we treat file-local variables: as soon as you visit the
>file/directory, the variables are interpreted.
>
>Perhaps we should offer an option to ask the question you mentioned,
>but I think in general it will annoy too much.

I don't know.  It's a relatively recent innovation, and I bet very few
users have ever stumbled into it.  In my opinion, dired should warn the
user and ask for permission to go on whenever it wants to read a
.dir-locals.el file.  Probably a customisation variable could avoid this
prompt.  And maybe in the future the current behaviour could become the
default, but not now.