I have several branches in mercurial all indicating there are multiple heads. When I attempt to execute hg merge -r $x -r $y in an attempt to merge two of the revisions I receive and error indicating that there are outstanding uncommitted merges.
It probably happens because you started a merge before but did not commit it. You can undo the previous merge in your working directory by running hg update -C.
Related
I'm trying to grasp the Mercurial basics so please bear with me. :) My current workflow is as follows:
do some work until I'm ready to commit or need the others' changes
pull
at this point I'd like to merge my work with the latest changesets and commit, however Mercurial insists on me committing before merging
so it goes like "commit, merge, commit" and I'm basically committing everything twice, writing the same notes in both changesets and pushing two changesets at a time
Is it intended to be so? Is it possible to have just one changeset coming from me with every merge? Is it indeed desirable?
I've read a lot of online manuals but still feel I do not have solid understanding of the process. All comments are welcome. Thanks!
EDIT: Turns out I didn't know that update could merge incoming changes with uncommitted edits.
Merging always creates a separate changeset in Mercurial.
Plus, merging is not possible as long as you have uncommitted stuff in your local repository.
So the solution is to commit first, and pull and merge afterwards.
This will always result in two changesets, not one.
(...because merging always creates a separate changeset)
But you don't commit the same stuff twice, and especially you shouldn't write the same commit message twice:
The first commit is what you actually changed ("fixed a bug in the foo bar").
The second commit is just the merge (TortoiseHG actually pre-populates the commit message with "Merge", 99% of the time I just leave it like that).
This workflow will prevent a merge in the history, but you still do a merge as noted below:
Do some work until you are ready to commit or need another's changes.
hg pull
hg update (Note: hg pull -u does this and the previous in one step.
During hg update, your uncommitted changes will be merged with the new tip of your current branch. You will still have to resolve any conflicts.
hg commit when ready.
I still recommend if you have extensive changes to commit first before pulling/merging because it is easier to start over by updating to that changeset if the merge goes badly.
Keeping the hg pull and hg update separate allows you to look at the incoming changesets and predict how the merge will go.
The reason is feels strange is that you delay your commit until you want to integrate with the others.
A big feature of distributed version control is that commits are local. Because they're local you should commit often — commit every time you have a small consistent chunk of work done. Your commits are not inflicted on others immediately so you wont interrupt them by making many small commits.
If you begin making more commits you'll see that your workflow becomes:
$ hg commit -m "Refactoring for Issue123"
$ hg commit -m "Basic functionality for Issue123"
$ hg commit -m "Fixed off-by-one error (Issue123)"
$ hg commit -m "Finished implementing Issue123"
$ hg commit -m "Added more tests for Issue123"
$ hg commit -m "Begin use new function from Issue123"
$ hg pull
$ hg merge
$ hg commit -m "Merge"
Here the ratio of merge commits to "real" commits is much more sensible.
Many people (myself included) like to use the rebase extension to avoid the merge completely. That extension linearizes the commits by faking the history so that it looks like you did your four commits after the changesets you pulled down with hg pull. The only change in workflow is that you hg rebase instead of hg merge above and then skip the final commit.
I'm transitioning to Mercurial from Subversion, where I'm used to using svnmerge.py to track changes that have already been merged, or which have been blocked from being merged:
# Mark change 123 as having already been merged; it will not be merged again, even if a range
# that contains it is subsequently specified.
svnmerge.py merge -M -r123
#
# Block change 326 from being considered for merges.
svnmerge.py merge -X -r326
#
# Show changes that are available for merging from the source branch.
svnmerge.py avail
#
# Do a catchall merge of the remaining changes. Neither change 123 nor change 326 will be
# considered for merging.
svnmerge.py merge
I want to be able to do something similar for hg pull/push/merge/graft, so that if I know that I never want to merge a given change, I can just block it from consideration, making subsequent cherry-picking, merging, etc., into a more fire-and-forget affair. I have done a lot of googling, but have not found a way to do this.
There also appears to be no way to view a list of as-yet-ungrafted changes.
As I'm often tidying up after other developers and helping them with their merges, it's immensely helpful to be able to do these kinds of things, which one might well consider "inverse cherry-picking;" i.e., marking changes that you do NOT want to merge, and then doing a bulk merge of the remainder.
DAG-based systems like Mercurial ans Git are all or nothing: when you merge two branches, you do a three-way merge of the common ancestor and the two branches.
The three-way merge is only concerned with the final stage of each branch. For instance, it doesn't matter if you make your changes in 10 it 1000 steps — the merge result will be the same.
This implies that the only way to ignore a changeset is to back it out before the merge:
$ hg backout BAD
That will cancel the changeset on the branch, making it appear that it was never made from the perspective of the three-way merge.
If you have a whole branch that you want to merge, but ignore, then you can do a dummy merge:
$ hg merge --tool internal:local --non-interactive
$ hg revert --all --rev .
That goes through the merge, but reverts back to the old state before committing.
The best advice I can give you is to structure your workflow so that the above backouts aren't necessary. This means committing a bugfix on the oldest applicative branch. If a bug is found while creating feature X, then use hg bisect to figure out when the bug was introduced. Now updated back to the oldest branch where you still want to fix the bug:
$ hg update 2.0
# fix bug
$ hg commit -m "Fixed issue-123"
then merge the bugfix into all later branches:
$ hg update 2.1
$ hg merge 2.0
$ hg commit -m "Merge with 2.0 to get bugfix for issue-123"
$ hg update 2.2
$ hg merge 2.1
$ hg commit -m "Merge with 2.1 to get bugfix for issue-123"
If the bugfix no longer applies, then you should still merge, but throw away the unrelated changes:
$ hg update 3.0
$ hg merge 2.2 --tool internal:local --non-interactive
$ hg revert --all --rev .
$ hg commit -m "Dummy merge with 2.2"
That ensures that you can always use
$ hg log -r "::2.2 - ::3.0"
to see changesets on the 2.2 branch that haven't been merged into 3.0 yet.
I accidentally merged a branch into a workspace with applied patches.
How do I clean up this mess? Do I have to clean the merge (hg up -C) or is there some way to save my merge?
Mercurial 1.9.1, TortoiseHg 2.1.2
I reproduced the basis of the situation with these commands on a fresh repo:
echo first > file.txt
hg add
hg ci -m first
hg branch test
echo test1 >> file.txt
hg ci -m test1
hg up 0
echo patch >> file.txt
hg qnew -f patch.diff
Then I performed hg merge test and resolved conflicts, and tried some different things:
Committing is denied due to the involvement of patches:
abort: cannot commit over an applied mq patch
I could not shelve the merge in TortoiseHg.
I could not qnew:
abort: cannot manage merge changesets
The only thing I found I could do to keep the merge was to finish the patches and commit the merge changeset. With the givens, I think keeping the patches and keeping the merge are mutually exclusive.
I know that pbranch allows merging with patches, and there's probably some way to import your MQ patches into it. I don't think it's supported in TortoiseHg, though.
For Mercurial, right now there is default branch and newfeature branch... is it true that if I am on
the newfeature branch, and do an hg pull and hg update, it will always ask me to merge? (if there are changesets that I pulled)
Also, it seems that I cannot just do hg merge? I need to use hg heads and then look at what the newfeature branch's head is (say it is revision 6880),
then I need to hg merge -r 6880? Because otherwise, will Mercurial merge the newfeature branch with the default branch automatically? I cannot do hg merge -b newfeature, it seems, as there is no -b option for hg merge.
Is there an easier way other than using hg heads to look for the revision to merge? Isn't there a more automatic way?
You've got two questions there, let me take them one at a time (with a little paraphrasing):
Q. When I hg pull and get a new head Mercurial suggest I hg merge. Do I have to?
A. No. Mercurial is just warning you you have more heads than than you did, and that if you don't like that arrangement you can merge to stop it. Named branches are heads, so you'll see that warning if pulling gets you a new head
Q. If I want to merge one named branch into another do I have to provide the revision number?
A. No. It's true that hg merge will only automatically select heads on the same named branch, but you can do hg merge -r newfeature and that merges in the changeset from the point of divergence up to the head on newfeature (6880 in your example) exactly the same as hg update -r 6880 would.
In either case, after committing that merge you'll have no heads on newfeature (the new, resulting head is on default because that was the branch name of your parent before you started the merge. However, just doing this after the merge:
hg update newfeature
...code....
hg commit
will create a new head on the newfeature branch, and you're right back as you were before the merge, except all of the changes that were on new feature are also available in default now.
If you pull a changeset or changesets from one branch into another branch that share the same root changeset. Mercurial will have multiple heads as you have so noticed. It will only suggest that you merge when you do an hg update on one of the branches.
You shouldn't have to specify which revision to merge to, assuming that you want to merge the tips of each of the branches. hg merge should suffice.
Your command structure should look as follow
hg pull -b 'branchYouWantToPullFrom`
hg update
hg merge
hg commit
hg merge works in your working copy, which is always connected to a specific branch.
You have to specify a branch name only if you want to merge your current branch with another branch: hg merge branch_name.
hg pull updates your repository with all remote changes. Then you have to update your working copy, that is connected to a specific branch. So, when you type hg update command, you update your working copy with all changes in your current branch.
If you want to switch to another branch you have to type hg update branch_name. You can type hg branch to know your current branch.
The only reason to merge with a specific revision is when you have three or more heads, a strange situation probably caused by some hg push -f (extremely bad practice). If you are in this situation, the right way to know which revisions you have to merge is hg heads. In a normal situation hg heads returns one head per branch, so you don't have to merge two heads of different branches if you don't want.
If you're working on a branch and someone has committed and pushed some changes on the same branch, you have to pull and merge before your push, simply with hg merge, no revision or branch.
I hope this will help you.
I have two heads, let's call them "A" (the good head) and "B" (the bad head). I want to merge them by taking everything from A and nothing from B. Basically, my merge of A and B is A.
When I try hg merge, it starts asking me about this file and that, and inevitably I get into trouble. I don't want any of that! How can I tell it to merge them and end up with A, preferably without any intermediate steps?
From the Mercurial tips at section 22. Keep "My" or "Their" files when doing a merge.
https://www.mercurial-scm.org/wiki/TipsAndTricks
Occasionally you want to merge two heads, but you want to throw away all changes from one of the heads, a so-called dummy merge. You can override the merge by using the ui.merge configuration entry:
$ hg --config ui.merge=internal:local merge #keep my files
$ hg --config ui.merge=internal:other merge #keep their files
Here local means parent of working directory, other is the head you want to merge with. This will leave out updates from the other head.
To merge X into the current revision without letting any of the changes from X come through, do:
hg --config ui.merge=internal:fail merge X
hg revert --all --rev .
The other approach is mentioned in : https://www.mercurial-scm.org/wiki/PruningDeadBranches
$ hg update -C tip # jump to one head
$ hg merge otherhead # merge in the other head
$ hg revert -a -r tip # undo all the changes from the merge
$ hg commit -m "eliminate other head" # create new tip identical to the old
One thing I came across and started using recently on some personal repos was just using the close-branch switch with commit. e.g.
$ hg update B
$ hg commit --close-branch -m "Abandoning branch"
In my reasoning, if you're blowing away one branch in favor of the other entirely, it's simply not a merge and it's silly to call it that. I'm relatively new to hg myself, and I seem to recall that --close-branch has not been around since the beginning and maybe that's why it doesn't have as much traction as the merging gyrations I usually see.