Re: [PATCH] Make !pattern in .gitattributes non-fatal

[Thomas Rast <trast@student.ethz.ch>]

Junio C Hamano <gitster@pobox.com> writes:

> Thomas Rast <trast@student.ethz.ch> writes:
>
>> Before 82dce99 (attr: more matching optimizations from .gitignore,
>> 2012-10-15), .gitattributes did not have any special treatment of a
>> leading '!'.  The docs, however, always said
>>
>>   The rules how the pattern matches paths are the same as in
>>   `.gitignore` files; see linkgit:gitignore[5].
>>
>> By those rules, leading '!' means pattern negation.  So 82dce99
>> correctly determined that this kind of line makes no sense and should
>> be disallowed.
>>
>> However, users who actually had a rule for files starting with a '!'
>> are in a bad position: before 82dce99 '!' matched that literal
>> character, so it is conceivable that users have .gitattributes with
>> such lines in them.  After 82dce99 the unescaped version was
>> disallowed in such a way that git outright refuses to run(!) most
>> commands in the presence of such a .gitattributes.  It therefore
>> becomes very hard to fix, let alone work with, such repositories.
>
> Fixing the working tree is easy, but when we read from a history
> that already records such an entry in an attribute file, it would
> become somewhat cumbersome.  I wouldn't use "very hard to fix" to
> describe such a case.

Well, I'm sorry if I hurt any feelings there, but...

  ~/tmp/badattr(master)$ git show bad:.gitattributes
  !bad text
  ~/tmp/badattr(master)$ ~/g/git-checkout bad  # a git without my patch
  fatal: Negative patterns are forbidden in git attributes
  Use '\!' for literal leading exclamation.
  ~/tmp/badattr(master)$ git status
  # On branch master
  nothing to commit (use -u to show untracked files)

Notice how it remains on master.  I suppose with enough knowledge of the
internals I could manage, but after seeing how hard it was to *build*
such broken history with a git that dies, I don't really want to try.

-- 
Thomas Rast
trast@{inf,student}.ethz.ch