Re: [BUG] gitattribute macro expansion oddity

[Michael Haggerty <mhagger@alum.mit.edu>]

On 01/10/2012 08:03 AM, Jeff King wrote:
> I'm seeing some very odd behavior with git's attribute expansion for
> diffs. You can see it with this repository:
> 
>   git clone git://github.com/libgit2/libgit2sharp.git
> 
> Try a diff of a non-binary file: [...]

The problem has nothing with diffing; simply interrogating the attribute
values gives different results depending on the order of the files:

$ git check-attr --all Lib/NativeBinaries/x86/git2.dll
LibGit2Sharp/Configuration.cs
Lib/NativeBinaries/x86/git2.dll: binary: set
Lib/NativeBinaries/x86/git2.dll: diff: unset
Lib/NativeBinaries/x86/git2.dll: text: unset
LibGit2Sharp/Configuration.cs: binary: set
LibGit2Sharp/Configuration.cs: diff: unset
LibGit2Sharp/Configuration.cs: text: unset
LibGit2Sharp/Configuration.cs: crlf: set
$ git check-attr --all LibGit2Sharp/Configuration.cs
Lib/NativeBinaries/x86/git2.dll
LibGit2Sharp/Configuration.cs: diff: csharp
LibGit2Sharp/Configuration.cs: crlf: set
Lib/NativeBinaries/x86/git2.dll: binary: set
Lib/NativeBinaries/x86/git2.dll: diff: unset
Lib/NativeBinaries/x86/git2.dll: text: unset

It also doesn't depend on the fact that Lib/.gitattributes uses CRLF as
its EOL, nor does it depend on the use of the "binary" macro.  However,
it does depend on the fact that the directory name "Lib" matches the
first part of the directory name "LibGit2Sharp".  Here is a simplified
demonstration of the problem:

a=LibA/a.txt
b=Lib/b.bin
rm -rf foo
git init foo
cd foo
mkdir $(dirname $a) $(dirname $b)
touch $a $b
echo '*.txt foo' >.gitattributes
echo '* bar' >$(dirname $b)/.gitattributes
git add .
git commit -am 'Demonstrate problem'
echo '================================================='
git check-attr --all $b $a
echo '================================================='
git check-attr --all $a $b
echo '================================================='

The attributes of $a are different depending on what order $a and $b
appear in the "git check-attr" command line.

Changing the example to "a=foo/a.txt" makes the problem go away.

Michael

-- 
Michael Haggerty
mhagger@alum.mit.edu
http://softwareswirl.blogspot.com/