From: Ian Turner <vectro@vectro.org>
Date: Mon, 23 Sep 2024 16:29:06 GMT
Subject: Bug report: Undocumented interaction of --exit-code and --ignore-space-change for file move
Message-ID: <d8512f2b-400f-4daa-a59f-5d10d4fc3840@vectro.org>

Hi all,

I noticed that there an undocumented interaction of the --exit-code and 
--ignore-space-change flags to git diff, when the diff only contains 
file moves. Specifically, --ignore-space-change will cause git diff to 
return a zero exit code in this situation.

I am not sure if the problem is with the command behavior, or with the 
documentation.

STEPS TO REPRODUCE:

git init
echo foo > a.txt
git add a.txt
git commit -m "A"
git mv a.txt b.txt
git commit -m "B"
git diff --exit-code HEAD~1..HEAD # returns exit code 1
git diff --exit-code --ignore-space-change HEAD~1..HEAD # returns exit 
status 0

EXPECTED BEHAVIOR:

Both of the last two commands above should return nonzero exit status.

WORKAROUND:

As one might expect --no-renames undoes this behavior, although it also 
changes the diff output if not using --quiet:

git diff --exit-code --ignore-space-change --no-renames HEAD~1..HEAD # 
returns exit status 1

OTHER INFO:

Tested this on git 2.39.2 and git 2.41.0, both on Linux.

Regards,

Ian Turner