Hg Merge specific commit from another branch - mercurial

I have two branches Dev and Feature1. I was working on Feature1, creating said feature, and committed it. I then wrote the code for Feature2 but committed it under Feature1 branch instead of a new branch (Feature2). So now i have two features in Feature1 branch as two separate commits, but I only want to include the second feature back into Dev.
What is the mercurial way to do this?

Use hg graft
This command uses Mercurial's merge logic to copy individual changes from other branches without merging branches in the history graph. This is sometimes known as 'backporting' or 'cherry-picking'.
Documentation: https://www.mercurial-scm.org/repo/hg/help/graft

Supposed you have not yet published your commits:
If you want to merge the commit Feature2 independent of commit Feature1, you should
move it on its own branch.
If already published:
Use the transplant extension to "duplicate" the Feature2 commit and put it on
its own branch. Then backout Feature2 commit on the Feature1 branch. Now you
merge Feature2 independent of Feature1 too.
In any case, instead of putting Feature2 on its own branch, you could also put it
directly onto your Dev branch if this is your actual intention.

include the second feature back into Dev.
Include to Dev and leave in Feature1 - translpant, as mentioned by #oben-sonne
Move completely from Feature1 - rebase
In case you want rebase into Feature2 you'll have to create this branch (Feature1) before rebase

Related

Splitting out multiple intermediate changes in Mercurial

We have a very unfortunate situation where a new feature branch was made from a second, unrelated feature branch that had been put on hold rather than from default. There's multiple changesets within both feature branches and while most changed files are unrelated several high level project files that have edits on both branches. Default has also had several updates and merges during this time too. Thankfully the intermediate feature hasn't been updated concurrently with the new feature. I've looked into various commands and options available and lost how to best fix this situation. The tree currently looks roughly like:
Default -- Various edits and merges -- tip
\
\-- Named Branch 1 (15 changes) -- Named Branch 2 (30 edits)
I want to get to a point where default has the changes from Named Branch 2 but none from Named Branch 1. I also want a branch that has the changes from Named Branch 1 available for when we return to this feature.
I suspect there's no nice easy way to do this, and there's going to be some messy parts in the history, however I am at a loss at how to start going about this task.
hg graft can cherry-pick changesets from one branch to another. Update to the destination branch, then graft the revisions you want to copy by running, for example:
hg graft 8 9 10
Conflicts will be handled using the normal merge process.
If you use TortoiseHg, select the changesets to graft to the current selected changeset, then right-click and select Graft Selected to local...:
Result:
Since you want to move the entire branch 2, you could consider using rebase. Make a clone of the repository and try this:
hg rebase --source <first branch2 rev> --dest <new parent in default> --keepbranches
This will in principle transform the history to what it should have been. However:
You may have to resolve conflicts arising when <first branch2 ver> gets moved to a new parent.
Since rebase rewrites history, you'll have to get everyone to cooperate in synchronizing their repositories. Whether that's feasible or worth the trouble in your case I can't say, but it's not that difficult: Assuming everyone has pushed any changes in branch 2, they can pull the new history and then get rid of the obsolete version of branch 2 with hg strip:
hg strip <first branch2 rev>

In Mercurial what's the difference between hg graft and hg rebase

I know Rebase is a (bundled) extension, while Graft is a core feature (that replaced the Transplant (bundled) extension).
graft is documented as:
copy changes from other branches onto the current branch
This command uses Mercurial's merge logic to copy individual changes from other branches without merging branches in the history graph. This is sometimes known as 'backporting' or 'cherry-picking'.
rebase is documented as:
Rebase allows moving commits around in Mercurial's history (using a series of internal merges). This has many uses:
moving changesets between branches
"linearizing" history
reordering changesets
collapsing multiple changes into one changeset
Both seem to use merging to move or copy changesets between branches.
Graft copies. Rebase moves. But rebase --keep copies.
So often it seems I can accomplish my goal of copying a changeset either way.
Does it matter which one I use? When should I prefer one over the other?
E.g. should graft only be used when copying to a different named branch? Or only when there's just a single changeset?
Edit: Could it be that rebase is a potentially unsafe superset of graft, but can only be used with draft changesets during development for editing local history, while graft is a safe subset of rebase that can be used with public changesets during maintenance for backporting?
hg graft allows "cherry-picking," as you noted in your question. For example, you can run hg graft -D "2085::2093 and not 2091" to copy only some changes from another revision. By comparison, hg rebase (with or without --keep) will grab whatever changeset you specify and all of its decendant changes.
Also, rebase allows you to collapse changesets (with --collapse). As far as I can tell, graft does not.
One more difference I have noticed: hg graft --edit 123 lets you graft revision 123 to the working directory and edit the commit message. I can't find an hg rebase equivalent. I should point out, though, that hg histedit also allows for editing the commit message while rebasing.
There are probably other differences that I am not thinking of. SO community: feel free to point those out in the comments, and I will happily revise this answer to make it more complete.
See the graft documentation and the Rebase Extension documentation for more details.

hg: Commit some changes to another branch

I was working in branch-a when I found an unrelated bug that should be fixed in the default branch. So, I'd like commit some of my changes to default, then merge default into the current branch, and keep working.
As far as I know, Mercurial doesn't allow committing directly into another branch, so I would have to switch to the default branch first. The problem is, I can't simply checkout the default branch, because the other changes would cause conflicts. One workflow I can think of is to shelve, checkout default, unshelve only the files that relate to the fix, commit, checkout branch-a, merge default, and finally, unshelve the rest of the files. Is there an easier way to accomplish this?
Commit only subset of files, related to branch-a changes (use additionally power of Record Extension, if bugfix's and branch-a's changes happens in some file(s) - commit only needed hunks of file) as changeset A
If you haven't MQ Extension:
Commit the rest of changes into branch-a as changeset B (child of A)
Rebase B (with Rebase Extension) changeset into default branch with --keep option in oder to have B in original location also
If you have MQ extension
Create new patch with working-dir changes
Unapply MQ-patch
Update to default
Apply patch
Test, test...
Finish patch (convert to permanent changeset)
Graft this changeset only into branch-a branch

Mercurial: How can I create an unplanned branch

My use case is this:
I am working on a new feature and I have several commits on that feature.
Since it was a minor feature, I didn't even consider doing the feature in a feature branch.
However. Now my boss comes along and tells me to fix a bug on the same branch that I am working on (default).
To fix that I'd like to create a feature branch for my feature, push all my existing (unpushed) commits into that branch.
So I'd like to create a branch just before my first commit and then somehow move all my commits to that branch.
How can I do this?
There’s two ways to approach this, depending on your preference:
In a new repository.
Make a new clone of your repository, and do the bug fix you need to make there. Then push it to the main repository when you’re done, and continue where you left off in the original repository. Pull and merge to get the new changes as usual.
In the existing repository.
Update to the changeset before your local changes, and just start fixing and committing there. This creates a new anonymous branch. When you’re done, push using push -r ., this will only push the changes that are included in the working copy. After this, merge with your original branch (hg merge) and continue where you left off.
Note that you can bookmark the feature branch with hg bookmark if you do not feel comfortable with leaving your changes unlabeled. Also you can easily find back any heads you left behind using hg heads.
Personally I prefer to work in a new clean clone, as you don’t need to worry about branching and where to leave uncommitted changes. However if your project setup is complicated it may be more convenient to reuse the existing repo.
For this situation you can fix it by rebasing (which may need enabling in your configuration).
On your branch, update to the revision before the change-sets you want to move:
hg up -r<revison>
This assumes contiguous revisions need moving.
Create a new branch:
hg branch "TempWork"
Put a dummy commit onto it in order to get a new revision:
hg commit -m"New Branch"
Then perform the rebase from the first of the change-sets you want to move (it moves descendants automatically) and specify the new branch revision as the destination:
hg rebase -s<base revision> -d<new branch revision>
Then update back onto your main-line branch.
Fourth method: Using mq-patches
You have to have mq extension enabled and initiated for repo
On hotfix moment you
convert feature-commits into set of mq-patches (hg qimport)
Unapply all patches in set (hg qpop -a)
Code hotfix, commit
...
Finish and test hotfix on clean codebase
Apply all patches in set (hg qpush -a), fix possible conflicts
Convert patches back to changeset (hg qfinish)

Rename a committed to branch in Mercurial

Mercurial - What are the steps involved to accomplish the rename of a branch after it has been created and committed to (both locally and in the central repo).
For example, I've created a branch called Zelda and then committed and pushed to a central repository. I now want to change the name of the branch to Triforce.
Is there an extension that accomplishes this? What might be the long way in addition to any extension solution?
The short answer is no.
The long answer is, Mercurial branches are names attached to changesets. If you have several changesets committed to the branch zelda and given away (i.e., pushed to the central repo), there's no way you can rename that branch without re-creating these changesets, which means rewriting history.
Even if you strip those changesets both in you repo and in the central repo, then re-create them as belonging to the branch triforce, and push the “renamed” branch again, all of your collaborators will end up having two copies of the changesets, one set on branch zelda, another on branch triforce.
So yes, what you should do is described in https://stackoverflow.com/a/7245187/67988. To quote from there, adjusted to your branch names, i.e. zelda is the old branch to be closed and triforce is the new branch to be created.
hg update zelda
hg commit --close-branch -m "mgmt: Close branch zelda"
hg branch triforce
hg commit -m "mgmt: Create branch triforce"
hg push --new-branch
P.S. If no one else pulled from the central repo yet, you can try stripping zelda from there. Or, if you have access to all other devs' PCs (assuming a controlled environment), and really want to go one very dangerous road, you can strip this branch from all the repos. This is definitely not considered good practice, and can only be used as a last resort measure.
The mutable-branches extension can give the illusion of having renamed a branch.