diff weirdness (bug?)

git clone [email protected]:ansible/ansible.git
git revert 3616dffb68badb2b8d56

manually solve the conflict (you can look at the commit here:
https://github.com/ansible/ansible/commit/3616dffb68badb2b8d56ef34391d7aae8de79cd6
)

git diff will output:

dario@macbook ~/P/ansible (devel*+|REVERTING)> git diff

lib/ansible/constants.py +1 -5

diff --cc lib/ansible/constants.py
index c055ccf,6eac602..0000000
@@@ -84,16 -61,8 +84,12 @@@ active_user   = pwd.getpwuid(os.geteuid
 
  # Needed so the RPM can call setup.py and have modules land in the
  # correct location. See #1277 for discussion
- if getattr(sys, "real_prefix", None):
-     # in a virtualenv
-     DIST_MODULE_PATH = os.path.join(sys.prefix, 'share/ansible/')
- else:
-     DIST_MODULE_PATH = '/usr/share/ansible/'
+ DIST_MODULE_PATH = os.path.join(sys.prefix, 'share/ansible/')
 
 +# check all of these extensions when looking for yaml files for things

like
+# group variables +YAML_FILENAME_EXTENSIONS = [ "", ".yml", ".yaml" ] +

  # sections in config file
  DEFAULTS='defaults'

now, it weirdly/incorrectly says that we added the YAML-related lines

if we remove these 3 lines, we'll get this diff:

This is a combined diff, and yaml-related lines are added relative to your _other_ branch you are merging (notice these + are indented by one place). Relative to what you had at the tip of your branch before you started this operation that ended up conflicted, the half-merged result removes if/else that sets DIST_MODULE_PATH and replaces it with a single line (their +/- are on the first column, signifying that these are differences relative to the first parent, i.e. your state before you started the operation).

Quoted 1 line

if we remove these 3 lines, we'll get this diff:

With that understanding, I think the output after removing these three lines is perfectlyh understandable and correct. You are looking at the three lines that used to exist in the version you started from, that were missing from the other side. If you remoe them, it will show as removal from _your_ version (notice these - that shows what _you_ did manually are on the first column, saying that that is relative to _your_ version).

Quoted 11 lines · Junio C Hamano

This is a combined diff, and yaml-related lines are added relative to your _other_ branch you are merging (notice these + are indented by one place). Relative to what you had at the tip of your branch before you started this operation that ended up conflicted, the half-merged result removes if/else that sets DIST_MODULE_PATH and replaces it with a single line (their +/- are on the first column, signifying that these are differences relative to the first parent, i.e. your state before you started the operation).

Quoted 1 line

if we remove these 3 lines, we'll get this diff:

Quoted 8 lines

With that understanding, I think the output after removing these three lines is perfectlyh understandable and correct. You are looking at the three lines that used to exist in the version you started from, that were missing from the other side. If you remoe them, it will show as removal from _your_ version (notice these - that shows what _you_ did manually are on the first column, saying that that is relative to _your_ version).

Thank you, I was completely unaware of combined diffs. Still: I can't see how this would explain the empty diff when deleting 4 lines instead of 3.

Quoted 11 lines · Junio C Hamano

This is a combined diff, and yaml-related lines are added relative to your _other_ branch you are merging (notice these + are indented by one place). Relative to what you had at the tip of your branch before you started this operation that ended up conflicted, the half-merged result removes if/else that sets DIST_MODULE_PATH and replaces it with a single line (their +/- are on the first column, signifying that these are differences relative to the first parent, i.e. your state before you started the operation).

Quoted 1 line

if we remove these 3 lines, we'll get this diff:

Quoted 8 lines

With that understanding, I think the output after removing these three lines is perfectlyh understandable and correct. You are looking at the three lines that used to exist in the version you started from, that were missing from the other side. If you remoe them, it will show as removal from _your_ version (notice these - that shows what _you_ did manually are on the first column, saying that that is relative to _your_ version).

Thank you, I was completely unaware of combined diffs. Still: I can't see how this would explain the empty diff when deleting 4 lines instead of 3.

Also: in the diff output I get 2 hashes, but these are not the hashes of the commits, but the contents of the files apparently. One should be HEAD (but if I run sha1sum over the file the hash doesn't match), but

the other can't be the commit which I reverted: the diff is too small... or at least this is what I understand

By the way, in the man of git diff there's the briefly mentioned '-m' flag. If anyone else reading this mail in the archives is confused by the combined diff output, just use "git diff -m HEAD"... I'll probably add this in my git aliases