Is there any way of simulating a git merge between two branches, the current working branch and the master, but without making any changes?
I often have conflicts when I have to make a git merge. Is there any way of simulating the merge first?
You can use git merge --no-commit to prevent the merge from actually being committed, and if you don't like how the merge works out, just reset to the original head.
If you definitely don't want to finalize the merge, even if it's a fast-forward (and thus has no conflicts, by definition), you could add --no-ff as well.
I don't think there is a way of simulating what will happen until you try the merge. However, if you make sure that the output of git status is empty before you do the merge, it is quite safe to just go ahead and try it. If you get conflicts, you can immediately get back to the state you were at before with:
git reset --merge
Since git 1.7.4, you can also abort the merge by doing:
git merge --abort
(As the commit message that added that option explains, this was added for consistency with git rebase --abort and so on.)
If I want to compare changes on a topic branch to master, I find it easiest and safest to do the following:
git checkout master
git checkout -b trial_merge
git merge topic_branch
After completing the merge, it is easy to see the consolidated change from master
git diff master
When done, simply delete the trial_merge branch
git checkout master
git branch -D trial_merge
This way, the master branch never changes.
Here is the solution that I have found: git merge-tree does merging "in memory" and prints the diff without touching your working directory. You can even test a branch without checking it out.
Get the merge diff
First, do this to make sure your repository knows about all the remote branches:
$ git fetch --all
Now use this bash snippet to see how branch $branch would merge into $master:
$ branch='feature'
$ git merge-tree $(git merge-base $branch master) master $branch
No changes are made to your workdir or index. It's a dry-run merge.
Pick information from the output
The output is a diff.
In case the branch has been merged, it will be empty.
To find whether there are conflicts, grep it for <<<:
$ git merge-tree $(git merge-base $branch master) master $branch | fgrep '<<<'
To extract conflict diffs, use sed to extract lines between <<< and >>>:
$ git merge-tree $(git merge-base $branch master) master $branch | \
sed -ne '/^\+<<</,/^\+>>>/ p'
Features
The diff will be empty if a branch is already merged
Use grep/sed to extract conflicts information
Use origin/feature to test branches you've never worked with
Can be used to see how 2 branches have diverged
Add it to your favorites
Get the diff of the merge:
git config --global alias.mergediff '!f(){ branch="$1" ; into="$2" ; git merge-tree $(git merge-base "$branch" "$into") "$into" "$branch" ; };f '
Usage:
$ git mergediff <feature-branch> <merge-into>
$ git mergediff feature master
Get merge conflicts:
git config --global alias.mergetest '!f(){ git mergediff $# | sed -ne "/^+<<</,/^+>>>/ p" ; };f '
Usage:
$ git mergetest <feature-branch> <merge-into>
$ git mergetest feature master
Why not just create a throwaway branch (git checkout -b), and do a test merge there?
I use :
git merge --ff-only
according to documentation:
Refuse to merge and exit with a non-zero status unless the current HEAD is already up-to-date or the merge can be resolved as a fast-forward.
It's not really a simulation because there will be a fast-forward merge in case of no conflicts between the two branches. But in case of conflicts, you will be informed and nothing will happens.
I've been able to use git merge --abort, recently. However, this can only be used if there is a merge conflict. If you are sure that you will not want to commit, then use the other mentioned methods above.
I don't know exactly if it is your case, but your question remember me that sometimes I start a feature, I commit over the days and I merge the develop on it many times.
On this point I lose the control over the exact files I changed and I will only know it when my feature were closed and my code go to develop.
In this case, a good way to know what modifications you did (not other from the merges) is using Sourcetree.
You must click with the right button on the base branch and select Diff Against Current:
Then sourcetree will show you all the modifications that will be merged if you merge your branch into base branch.
Of course, it will not show you the conflicts, but it is a useful tool in merges.
I've created a changeset which contains a number of individual changes. I've realized that one of those changes might not have been a good idea, and I'd like to update my working directory to include only part of that changeset to work on, without throwing out the changeset itself.
In git terms, I want to do something similar to git checkout -p HEAD~, or the similar
git checkout -b newbranch
git reset HEAD~
git add -p
git checkout -- .
How can I do this in Mercurial?
Read carefully hg help revert, pay special attention to -r option and NAME (ordinary list of fileset).
In your case (single changeset, part of which you want to eliminate from Working Dir), you have to:
hg up to the this changeset
hg revert -r "p1(.)" set:SOME-FILESET or, instead of fileset ("set:PATTERN" part), just "... FILE FILE2 FILE3 FILEN"
As result, you'll get in one readable command modified Working Directory with only needed part of changes in it
Suppose I have a branch called test on remote server. All of the people working with this repository have this branch too. We all make some local commits to it and somehow the remote version becomes changed. Now, I want to merge remote named branch test into my local branch test having my current work saved. So if my current branch is default I do:
hg update -C test
make some changes in test branch
hg commit -m "Some changes"
hg pull
hg merge
hg commit -m "Merge"
hg push
However I recieve strange error during some of those steps: abort: branch 'test' has one head - please merge with an explicit rev
(run 'hg heads' to see all heads)
Why is that?
I have a mercurial repository in which I had created a branch 7-8 months back. And now this branch is the one in which I do most of the development and I don't have anything fruitful in default branch and other branches that I have.
I want to create a new repository that represent only this branch. i.e. I want to move this branch to a new repository with history.
I tried to use HG convert tool with following syntax:
hg convert --filemap ~filemap.txt --branchmap branchmap.txt --source-type hg --dest-type hg "E:\MyStuff\Dev\MyOldRepo" "E:\NewRepo"
File map I have defined all my file that I want to include. In branchmap file i had defined
MyOldNamedBranch default
Convert tool do rename MyOldNamedBranch to default but it also brings the changesets from other branch that I don't need.
I also tried to set the following in setting file but no results:
[convert]
hg.usebranchnames=0
hg.startrev=5262
Please suggest how I can move a branch to new repository with history and leaving other branches behind.
I have set the start revision number in command only and it worked.
hg convert --config convert.hg.startrev=5262 --branchmap branchmap.txt "E:\MyStuff\Dev\MyOldRepo" "E:\NewRepo"
And it worked like a charm.
Try this:
Clone only the branch you need:
hg clone E:\MyStuff\Dev\MyOldRepo -b MyOldNamedBranch .\NewRepo
Then inside the NewRepo, convert all the changesets to the draft phase:
hg phase -r 0 -d -f
Then update to the patent of MyOldBranch (I assume, that the parent is in the default branch)
hg update -r "parents(min(branch(MyOldBranch)))"
Then rebase MyOldBranch on the exactly the same changeset.
hg rebase -s "min(branch(MyOldBranch))" -d .
Do exactly the same with the rest of the branches.
To be honest I'm not sure if this is the best method but it worked for me.
Many times I'm making two different changes to files in my repository, I want those changes to be treated as two consecutive commits.
For example, in repository
prog.c
prog.h
README.txt
While fixing a bug prog.c and prog.h, I fixed a typo in README.txt. Now I want to commit the change to prog.c with its own commit message, and the change to README.txt afterwards.
In git, I could easily do that with the index
git add prog.c prog.h
git commit -m 'bug #1234'
git commit README.txt -m 'some typos fixed'
What's the best way to do that in Mercurial?
Clarification: I used (before the edit) a toy example where each changeset spans over a single file. But I want the general answer, what should I do when there are many files in each changeset.
hg commit -m "bug #1234" prog.c prog.h
then
hg commit -m "some typos fixed" README.txt
I LOVE the crecord mercurial extension for this purpose: it gives me file by file (and chunk by chunk, and line by line) control over what exactly I want in this commit.