Re: git-diff passes <rev>:<path> args to GIT_EXTERNAL_DIFF incorrectly?

From: Dmitry Nikulin <pastafariant@gmail.com>
Date: Aug 30, 2019, 13:23 UTC
Message-ID: <CAH53SykQWLtjt0gWVrz5KyH-9WyqaQ0GtkhmyLt09QEqcAS_dw@mail.gmail.com>
In-Reply-To: <9c280a3f-6a1a-61d1-a255-1dcf0671d39c@gmail.com>

On Fri, 30 Aug 2019 at 13:16, Phillip Wood <phillip.wood123@gmail.com> wrote:

> I'm not sure why the last argument is being split in
> your example. It is not split in the example below

I have replicated the splitting issue on my small demo repo [1]:

$ env GIT_EXTERNAL_DIFF=./print_argv.py git diff -M origin/branch1
origin/branch1-mv -- file1.txt file1-mv.txt
['./print_argv.py',
 'file1.txt',
 '/tmp/EWaCSc_file1.txt',
 '2bef330804cb3f6962e45a72a12a3071ee9b5888',
 '100644',
 '/tmp/mtEiSc_file1-mv.txt',
 'f8fd6737fbe5a45c97ba9c9de495dc46ff11eccd',
 '100644',
 'file1-mv.txt',
 'similarity index 90%\n'
 'rename from file1.txt\n'
 'rename to file1-mv.txt\n'
 'index 2bef330..f8fd673 100644\n']

This is, however, tangential to the original problem: documenting the external diff CLI interface for diffing two blobs. Here is what I am seeing:

$ env GIT_EXTERNAL_DIFF=./print_argv.py git diff
origin/branch1:file1.txt origin/branch1-mv:file1-mv.txt
['./print_argv.py',
 'file1.txt',
 '/tmp/n9USvy_file1.txt',
 '2bef330804cb3f6962e45a72a12a3071ee9b5888',
 '100644',
 '/tmp/Zst0uy_file1-mv.txt',
 'f8fd6737fbe5a45c97ba9c9de495dc46ff11eccd',
 '100644',
 'file1-mv.txt',
 'index 2bef330..f8fd673 100644\n']

The meaning and origin of the last arg remains mysterious, and the other args do not conform to the published documentation[2], which states that the args should be:

    path old-file old-hex old-mode new-file new-hex new-mode

Instead the args that are passed are:

    path old-filename old-file old-hex old-mode new-file new-hex
new-mode new-filename something

[1]: https://github.com/dniku/git-external-diff-argv [2]: https://www.git-scm.com/docs/git#Documentation/git.txt-codeGITEXTERNALDIFFcode