Re: Honoring a checked out gitattributes file

Kristian Amlie venit, vidit, dixit 28.01.2009 16:25:

Hi!

We currently use msysGit in our company test farm to checkout the latest
development branch and do autotests. However, we have one problem:
Certain files require UNIX line endings, even though this is a Windows
system. For this we use .gitattributes.

However, if the .gitattributes file is also checked in to the branch, it
will not always be honored. I browsed the code a bit, and it seems to
happen whenever there is an existing .gitattributes file, but the
checkout adds new files to it. These new files will not get the correct
line endings (although I'm not sure if it happens *every* time, it could
depend on the order they are checked out).

I think this should be fairly straightforward to fix, by ensuring that
if there is a file called .gitattributes in the index of the current
directory, check it out first, before all the other files that may be
affected by it. I can produce a patch and testcase for it, but I wanted
to hear the opinions of some developers in case there is an obvious flaw
in my solution.

What do you think?

I think there's a general time ordering problem. Say you do the
following commits:

A: add a.txt
B: add a .gitattributes file covering *.txt (say with crlf or any filter)
C: add c.txt

Now, with an empty dir, you do either

1) checkout A, B, C sequentially
2) checkout C

The contents of the checkout will be different in cases 1) and 2):
1) a.txt is checked out out as is, c.txt according to the attributes
2) with current git: probably like 1), with your suggestion: both a.txt
and c.txt filtered according to the attributes.

If you add a file and .gitattributes covering it in the same commit
there is an ordering ambiguity which can be solved (patched away)
easily, but I think the difference between 1) and 2) is still
problematic, and would need to be dealt with.

The main problem seems to be that changing a file like gitattributes can
potentially change (by changing filters) the contents which should be
stored for a different file even if the checkout of that file doesn't
change.

Cheers,
Michael