"Shawn O. Pearce" <spearce@xxxxxxxxxxx> writes:
> Yes. But...
>
>> git-gui/git-gui.sh | 4 ++--
>> 1 files changed, 2 insertions(+), 2 deletions(-)
>
> That's the wrong path. Clearly you made this patch in git.git and
> not the git-gui.git repository itself. Fortunately for me I added
> -3 to git-am out of habit:
>
> $ git am -3 -s gg
> Applying 'git-gui: Call changes "Staged" and "Unstaged" in file list titles.'
>
> error: git-gui/git-gui.sh: does not exist in index
> Using index info to reconstruct a base tree...
> Falling back to patching base and 3-way merge...
> Renamed git-gui/git-gui.sh => git-gui.sh
> Wrote tree 8e034a94d9533af707279766e174b78ddf3874cc
> Committed: a1a4975824e8f9f88a8c96ae908c488a2c6047c5
>
> Yay Git! Go go gadget rename detection! ;-)
>
> I didn't even realize the git-gui/ prefix on the path in the patch
> until after I saw the rename detection message.
Yeah, -3 is a magic, isn't it?
For the benefit of people who are unfamiliar with the internal,
here is how it works.
- The patch Hannes gave Shawn had a change to
git-gui/git-gui.sh, like this:
git-gui/git-gui.sh | 4 ++--
1 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/git-gui/git-gui.sh b/git-gui/git-gui.sh
index 60e79ca..45d251e 100755
--- a/git-gui/git-gui.sh
+++ b/git-gui/git-gui.sh
@@ -5494,7 +5494,7 @@ pack .vpane -anchor n -side top -fill both -expand 1
- Shawn had a tree that looked like this:
GIT-VERSION-GEN
Makefile
git-gui.sh
lib/blame.tcl
lib/branch.tcl
...
- The patch obviously does not apply, as Shawn does not have
git-gui/git-gui.sh. However, Shawn instructed "git am" to
fall back on 3-way merge, which prepared two "fake" trees.
Fake tree 1 (the ancestor) is prepared by reading the index
line to figure out what blob the patch applies to. The
answer is 60e79ca, which Shawn has in his repository. The
resulting tree looks like this:
040000 tree 0df2c7b... git-gui
100755 blob 60e79ca... git-gui/git-gui.sh
Fake tree 2 (update) is prepared by applying the patch to the
ancestor fake tree.
040000 tree 950e50d... git-gui
100755 blob 45d251e... git-gui/git-gui.sh
- Then, it falls back to the 3-way merge, using the fake tree 1
as the common ancestor, Shawn's repository as "our" tree, and
fake tree 2 as the update being merged into "our" tree.
To this merge, most of the paths in "our" tree appear as if
Shawn added them since the common ancestor, except that
git-gui.sh at the toplevel in "our" tree was moved up by
Shawn from git-gui subdirectory (and then possibly further
modified), while git-gui/git-gui.sh was modified by Hannes.
At the path level, this is the classic case of "one side
(Shawn) modifies, while the other side (Hannes) kept it at
the place it was before", 3-way merge at the path level takes
Shawn's change (which is to "move the file up one level").
At the same time, at the contents level, this is just a
normal "common ancestor 60e79ca was modified to Shawn's
git-gui.sh on one side while Hannes's side modified it to
45d251e", and the contents are merged using the file level
3-way merge. The result is left in git-gui.sh.
All the other paths look as if Shawn added them to the common
ancestor that did not have any of them while Hannes did not
do any such change, so the merge algorithm takes Shawn's
"additions".
So in the end, Shawn ends up with most of his paths intact,
except that Hannes's patch which were meant to apply to
git-gui/git-gui.sh gets applied to his git-gui.sh.
-
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