Does git mv folder and merge afterward new file from feature branch to the modified path, deletes its history?

Question

I have the below scenario:

main branch before consolidation:

│   └── dir1
│   │   └── python1
│   │   │   └── test1.py
│   └── dir2
│   │   └── python2
│   │   │   └── test2.py
│   └── dir3
│   │   └── python3
│   │   │   └── test3.py

main branch after consolidation:

│   └── dir1
│   └── dir2
│   │   └── python1
│   │   │   └── test1.py
│   │   └── python2
│   │   │   └── test2.py
│   │   └── python3
│   │   │   └── test3.py
│   └── dir3

feature branch before merge (test4.py history has 10 commits in history):

│   └── dir1
│   │   └── python1
│   │   │   └── test4.py

main branch after merge from feature branch (using git merge -s ort and resolving the conflict on non existing test4.py):

│   └── dir1
│   └── dir2
│   │   └── python1
│   │   │   └── test1.py
│   │   │   └── test4.py
│   │   └── python2
│   │   │   └── test2.py
│   │   └── python3
│   │   │   └── test3.py
│   └── dir3

The problem is that all the history of test4.py got deleted... any idea why it happens and if its avoidable?

A slight quirk of git's design is that it doesn't actually track copies or renames in any permanent way. Instead, various history commands have options to reconstruct renames when they compare commits. So, it matters what command you're using to try to see the history of test4.py — IMSoP
– IMSoP, Commented Sep 12, 2021 at 18:17
git blame / gitk / git log , and also tried via intelji GUI, but nothing show the history — arielma
– arielma, Commented Sep 12, 2021 at 18:31
The way to think of this is: Git doesn't have file history. Git has commits, and the commits are the history. git log shows the commits as found by the fact that they are the history; git log -- path selects a subset of commit-history to walk, and then shows an even smaller subset of that subset; git log --follow -- path attempts to detect file renames and modifies the way that git log -- path works by changing which path it's using to do the subset-selecting, as it goes. — torek
– torek, Commented Sep 12, 2021 at 20:01
This all works fairly well for most cases, but in complicated rename-and-rework cases, it can fail pretty hard. You seem to have one of those cases. — torek
– torek, Commented Sep 12, 2021 at 20:01
In the future, try to avoid moving/renaming a file and changing it in the same commit. If you can do one, and not the other, git is almost guaranteed to be able to follow the history of the file across renames and moves. — Lasse V. Karlsen
– Lasse V. Karlsen, Commented Sep 12, 2021 at 21:09

jthill · Accepted Answer · 2021-09-12 20:05:02Z

3

If the merge deleted dir1/python1/test4.py from your target tree, then the branch you merged deleted that file. But I see now that it just moved it. If you want to see the history of that file,

gitk --follow -- dir2/python1/test4.py

will show it to you if it hasn't also changed beyond recognition. You can try adding -M50 if it has very substantially changed, and --full-history to inspect ancestry that didn't wind up having any effect on the mainline, just in case you want to see changes that were abandoned or otherwise wound up identical to changes Git's already showing you..

git blame always runs --follow (that's so often what's wanted nobody's taught it any option not to do that yet), but you do have to hunt down a commit that has it.

If a file wasn't just moved but actually deleted, if it doesn't exist now, git log -1 --pretty=%h -- path/to/that/test4.py will find the commit that deleted it, tack a ^ on the end of that one's output and that's the last commit before it got deleted.

edited Sep 12, 2021 at 20:05

answered Sep 12, 2021 at 18:50

jthill

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5 Comments

arielma Over a year ago

So it means there is no way to get the file history for dir2/python1/test4.py?

jthill Over a year ago

I misread your question, I stopped at "non existing test4.py" and didn't see it tucked in there under dir2. If the merge didn't also change it beyond recognition gitk --follow -- dir2/python1/test4.py and so on will do just fine.

arielma Over a year ago

I clarified the question. anyway it doesn't work, I don't see the history using this command on dir2/python1/test4.py

jthill Over a year ago

If it's been moved and substantially changed you might have to broaden the search with something like -M50, see the git log docs, gitk takes all of log's selection arguments.

jthill Over a year ago

Well,I'm doing my command testing on the git history with git-legacy-stash.sh and it works perfectly, so there's something particular about your history that's tripping up the rename-tracking mechanism. Is it a public repo?

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