How to determine the last Mercurial commit that changed file X? - mercurial

Given a checkout of a Mercurial repository and a filename. How does one determine the last commit that changed that file? Unlike git, care must be taken with branches. The intended semantic here is to follow the history of the branch. Where branches fork from other branches, follow parent branches.
Non-solutions:
shows commits from unmerged branches
hg log -l 1 filename
empty output if the file remains unchanged after branch creation
hg log -l 1 -b . filename
Arguably, this question highlights misuse of branches and bookmarks should be used instead. However that may be, existing history necessiates taking branches into account.

The -f flag tells hg log to follow history of the current or selected changeset, so this should find the first change of a file without looking at changesets that aren't direct ancestors:
hg log -f -l 1 filename

Related

What is the name for the commit/head that corresponds to the local checked-out state?

There is a commit in my hg repository with hash 123abc. This is the last commit I made in the repo. When I run hg diff --from 123abc, I see no output. When I run hg log --graph, I see an # next to 123abc.
In Git this commit would be called "HEAD". I'm not sure what it's called in Mercurial. It is not the "tip", because I pulled other changes after the last time I committed (and hg log -r tip shows commit 456def).
What is this commit/head called?
Mercurial calls this the "parent" or the "parent revision of the working directory", and you can see it by running hg parent, hg id, or hg summary.
You can refer to it as . with the hg log command:
hg log -r . # show the commit message for the parent
If 123abc has no children, then it is a "head".
A head is a changeset with no child changesets. The tip is the most
recently changed head. Other heads are recent pulls into a repository
that have not yet been merged.
(https://www.mercurial-scm.org/wiki/Head)
Regardless whether the current working directory derives from a head or a non-head, I would refer to the commit that precedes it as the "working directory parent" changeset or commit. (That may just be the term my team uses - not sure it is "official".)
The parent may be visible in a GUI tool (like Tortoise) or you can get it using hg parent.
Based on the statements about 456def I'm a little confused whether it has no children, or not? (Maybe update the question to clarify / add more detail)

Edit Mercurial Earlier Commit Message - TortoiseHg

Is there a way to edit a commit message in Mercurial on a commit after other commits have occured using TortoiseHg? I've read these posts:
How to edit incorrect commit message in Mercurial?
Mercurial: how to amend the last commit?
and have been able to update a "regular" commit message when it is the latest commit on a branch (using TortoiseHg). However, I haven't been able to figure out how to edit a commit message when other commits have occurred after the one I want to edit. It always edits the last commit.
Based on Ed Cottrell's comment, I did a test where I made two commits without pushing to the central repo, and I still have the same issue - only the last commit message can be edited.
EDIT: I should clarify that I am looking to update a changeset that has been pushed.
Histedit extension (bundled with TortoiseHG now) has a mess command for changing the commit message of historical changesets.
Unfortunately, this command is not supported by the TortoiseHG GUI so you need to run the command from command line.
As long as the change in question is local and hasn't been pushed anywhere, it is possible.
The commit message is used to compute the globally unique hash id that is used for all repositories to determine whether or not they already have a changeset. If you change the commit message, you change the unique hash id and every repo will see it as a "new" changeset. All other repositories that had the old changeset will try to get the new one and ask that you merge it with itself.... This is not a good thing, so the short answer to your question is "don't do it".
If you could definitively purge that change from all other repos, so that only the local copy is left you could essentially get to the "draft" state. Note that if any repo has the "old" changeset, it will be pushed to the central repo someday and cause the mess that we are trying to avoid.
If the changeset is still local (e.g. in draft status), you can use hg commit --amend if it is the parent of the working directory.
If there are changes after it, I would use mq and hg qimport all the changes down to and including the one where you want to edit the commit message. hg qpop -a and then hg qpush to get to the patch that represents the changeset you want to edit. Then hg qrefresh -e and make your changes. Then just hg qfin -a and you should be good to go.
The advice from Edward is good — if you've pushed your changes to another repository, you should consider them set in stone and not update the commit message or any other aspect of them.
However, we're working on changing this in Mercurial. There is an experimental extension that will allow you to do more extensive history editing and push those edits to other repositories. It is called the Evolve Extension and it enables some behavior that is partly in the core of Mercurial and partly outside core.
When using evolve, you can edit the second-to-last commit message like this
$ hg update .^
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg commit --amend -m 'new commit message'
1 new unstable changesets
$ hg stabilize
more:[5] old tip changeset
atop:[6] new commit message
The extension allows you to do this as long as the changesets are in the draft phase. To keep them in the draft phase after pushing them somewhere, the repository you push to need to be configured as a non-publishing repository. You can read more about this in the Changeset Evolution Documentation.

Add a parent to the original changeset in Mercurial

I have a project with 24 months of source control history in a Mercurial repository.
I've recently found some old tarballs of the project that predate source control, and i think they would be useful to import into the repository as "pre-historic" changesets.
Can i somehow add a parent to my initial commit?
Alternatively, is it possible to re-play my entire repository history on top of the tarballs, preserving all metadata (timestamps etc)?
Is it possible to have the new parent commits use the timestamps of these old tarballs?
You can use the convert extension to build a new repository where the tarballs are imported as revisions before your current root revision.
First, you import the tarballs based on the null revision:
$ hg update null
$ tar -xvzf backup-2010.tar.gz
$ hg addremove
$ hg commit -m 'Version from 2010'
$ rm -r *
$ tar -xvzf backup-2011.tar.gz
$ hg addremove
$ hg commit -m 'Version from 2011'
I'm using addremove above to give Mercurial a chance to detect renames between each tarball (look at the --similarity flag to fine-tune this and use hg rename --after by hand to help Mercurial further). Also, I remove all the files in the working copy before importing a new tarball: that way the next commit will contain exactly the snapshot present in the tarball you unpack.
After you've imported all the tarballs like above, you have a parallel history in your repository:
[c1] --- [c2] --- [c3] ... [cN]
[t1] --- [t2] --- [tM]
Your old commits are c1 to cN and the commits from the tarballs are t1 to tM. At the moment they share no history — it's as if you used hg pull -f to pull an unrelated repository into the current one.
The convert extension can now be used to do a Mercurial to Mercurial conversion where you rewrite the parent revision of c1 to be tM. Use the --splicemap flag for this. It needs a file with
<full changeset hash for c1> <full changeset hash for tM>
Use hg log --template '{node} ' -r c1 -r tM > splicemap to generate such a file. Then run
$ hg convert --splicemap splicemap . spliced
to generate a new repository spliced with the combined history. The repository is new, so you need to get everybody to re-clone it.
This technique is similar to using hg rebase as suggested by Kindread. The difference is that convert wont try to merge anything: it simply rewrites the parent pointer in c1 to be tM. Since there is no merging involved, this cannot fails with weird merge conflicts.
You should look at using rebase. This can allow you to make the changes the 2nd changeset on your repo ( you have to rebase from the 1st ).
https://www.mercurial-scm.org/wiki/RebaseExtension
However, note that if there are other clones of this repo existing ( such as for fellow developers, or on a repo server ), you will have issues with them pulling the revised repo. You will probably have to co-ordinate with the owners of those clone's to get all work into a single clone, rebase that clone, and then have everyone re-clone from the revised clone. You will also have to change the phase the of the changesets.
https://www.mercurial-scm.org/wiki/Phases
Honestly though, I would just add them to your 'modern-day' repo, I don't think making them pre-historic would give you any notable advantage over adding them to the top.

Mercurial (hg) equivalent of git reset (--mixed or --soft)

what would be an equivalent mercurial command (or workflow) for
git reset --mixed HEAD^
or
git reset --soft HEAD^
i.e. I want leave the working tree intact but get the repository back into the state it was before the last commit. Surprisingly I did not find anything useful on stackoverflow or with google.
Note that I cannot use
hg rollback
as I've done some history rewriting using HistEdit after the last commit.
Added to clarify:
After some rebasing and history editing I had ended up with A<--B<--C. Then I used HistEdit to squash B and C together, obtaining A<--C'. Now I want to split up the commit C' (I committed the wrong files in B). I figured the easiest way to do this was to get the repository back to state A (which technically never existed in the repository because of all the rebasing and history editing before hand) and the working tree to the state of C' and then doing two commits.
The right way to replicate git reset --soft HEAD^ (undo the current commit but keep changes in the working copy) is:
hg strip --keep -r .
-1 will only work if the commit you want to strip is the very last commit that entered the repository. . refers to the currently checked out commit, which is the closest equivalent Mercurial has to Git's HEAD.
Note that if . has descendants, those will get stripped away too. If you'd like to keep the commit around, then once you have the commit ID, you can instead:
hg update .^
hg revert --all -r <commit id>
This will update to the commit's parent and then replace the files in the working copy with the versions at that commit.
I believe the more modern and simpler way to do this now is hg uncommit. Note this leaves behind an empty commit which can be useful if you want to reuse the commit message later. If you don't, use hg uncommit --no-keep to not leave the empty commit.
hg uncommit [OPTION]... [FILE]...
uncommit part or all of a local changeset
This command undoes the effect of a local commit, returning the affected
files to their uncommitted state. This means that files modified or
deleted in the changeset will be left unchanged, and so will remain
modified in the working directory.
If no files are specified, the commit will be left empty, unless --no-keep

Mercurial: How to compact/combine specified old revisions into one?

I've got a repository. In the middle of its life-cycle I deleted a lot of unnecessary files from it (I decided to keep them unversioned).
hg remove
hg commit
The repo grows bigger and bigger.
And I decided to get rid of old revisions the from initial one to the revision where lot of files were removed (let's name it X).
Other words I want combine these revisions (from the initial to the X) into one initial revision.
But same time to keep the history of the following revisions (X+1, etc..) as they are.
I googled for the solution, but failed.
And found nothing clever than do this:
hg init newrepo
cd oldrepo
hg archive -r X newrepo
hg export -r X+1: -o "~/patches/%R-%h.diff"
cd newrepo
hg commit -A -m 'initial release (after archiving)'
hg import ~/patches/*.diff
And damn it, after few successfully applied patches
I receive:
Hunk #1 FAILED at xxx
Hunk #2 FAILED at xxx
2 out of 2 hunks FAILED -- saving rejects to file xxx.rej
abort: patch failed to apply
What I do wrong?
I've got 1 repo without branches (to be more exact to the revision X all branches were merged).
The second solution was
* hg convert to svn
* hg convert to mercurial from revisiob X+1
Failed with python backtrace (probably it was caused by our repo has about 3K files).
To filter out files from repository, you want to use hg convert (Mercurial to Mercurial) with --filemap argument (see documentation for more details). Keep in mind the affected changeset IDs (and those of all their descendants) will change.
Take a look at the Collapse extension which seems to do what you want.
You can fold changesets with MQ, or use histedit extension