When applying a patch is there any way to resolve conflicts?

Question

I am on windows.

For various reasons we have multiple git instances of different svn branches.

Many times I want to fix an issue in repository A, generate a patch, and apply it to repository B. This works fine except if there are conflicts.

When rebasing I just right click the folder and use tortioseGit and select the resolve option. This brings up a nice gui to let me work through my conflicts.

Is there any way to accomplish this with rejected patch chunks?

Here is my current approach to creating/applying the patches

git format-patch master --stdout > c:\\patch\\file.patch
git apply --reject --ignore-space-change --ignore-whitespace c:\\patch\\file.patch

Birefringence

I usually do it by hand when all patching options fail... – Squireen

If the merge fails, it is because the program can't figure out how to un-ambiguously do the merge. You should get a file with <<<<, ===, >>>> sets and you have to go in and resolve them by hand. – Percival

Yeah doing it by hand is a real pita when your talking a few 100 rej hunks. – Birefringence

That's when you'd want to use git mergetool and do a 3-way merge with the gui of your choice (i'm partial to kdiff on windows)... – Langan

Answer 1

To generate your patch do the following:

git format-patch --stdout first_commit^..last_commit > changes.patch

Now when you are ready to apply the patches:

git am -3 < changes.patch

the -3 will do a three-way merge if there are conflicts. At this point you can do a git mergetool if you want to go to a gui or just manually merge the files using vim (the standard <<<<<<, ||||||, >>>>>> conflict resolution).

Langan

I didn't know about the ... notation; it's documented in the gitrevisions(7) man page. – Eyebright

There certainly are alot of ways to get the commits you want and nothing else... That being said, what I was trying to convey is not what I actually said... Now it is fixed to really mean what I wanted... (or so I think...)... – Langan

It may be useful to add --ignore-whitespace --ignore-space-change to git am too. I had trivial merges that did not go through without it. – Inroad

git apply -3 changes.patch seems to work for me as well – Corycorybant

git -am -3 works for me. After git am -3 , I have to stage all the changes with git add patch. git am --continue. Then the patch will be applied successfully. – Milissamilissent

Even though the patch doesn't apply cleanly I still get "No files need merging" from git mergetool. Instead I had to find the base commit the original patch used, apply on top of that (luckily my repo had this) and then rebase. – Greenbrier

I'm having the same problem as @jozxyqk. Neither git am -3 nor git apply -3 will actually drop conflict markers into my files, even though I get messages like Applied patch to 'configure.ac' with conflicts. and error: patch failed: .... This is on git 2.17.1. Perhaps when some files can't be patched at all, git rolls back? – Untaught

I got the same issue as @nh2, did you ever find the problem? – Hassock

I wonder if this really works according the original question, when those commits (index SHAs in patch) are alien to the current repo? (No good test at hand, but -3 won't work with patches processed e.g. with interdiff or other advanced means. It requires to first establish the starting file state (e.g. committing a copy) of at least the conflicting files somewhere in the current repo at a suitable parent (with good similarity), and from there do apply + rebase / cherry-pick) – Shamrock

What about Mercurial users? :( – Actual

@Actual this is a git question...? no idea about mercurial unfortunately – Langan

Answer 2

If you are frequently running into the same conflict set when applying patches, rebasing or merging then you can use git rerere (reuse recorded resolution) function. This allows you to pre-define how conflicts should be resolved based on how you resolved them in the past. See http://git-scm.com/blog/2010/03/08/rerere.html for details of how this works.

Sutter

Answer 3

Just use

git apply -3 <patch_name>

it will allow you to fix conflicts

Seaver

Not always... error: repository lacks the necessary blob to perform 3-way merge. – Conwell

Answer 4

TortoiseGit has a merge feature that can open patch files.

There's a picture of it here.

Curtis

Actually the merge option might be what I'm looking for. – Birefringence

Really? I've not used tortoise in a long time, but the linked page has the text "TortoiseMerge can open Git patch file directly, you review it and patch to working copy.", so it seems like it should! – Curtis

it does open patch files... however, sometimes the patch file format breaks tortoisegitmerge. i've never been successful with diff -u, but rather diff -c output. – Trogon

You can also right drag patches on a working tree folder and select "Apply patch serial" (for patches like 0001-xxx.patch, ... 0002-xxy.patch) or "Apply single patch file". – Slattery

Answer 5

My approach is:

• Create an "Integration"-Branch where the files are identical
• Apply the patch to this Integration-Branch
• Merge or rebase it to master (don't know if rebase is useful here, because I don't know what will happen when applying further patches)

Eunuchoidism