How to merge to get rid of head with Mercurial com

My question is this:

If I have two heads (branches with changes) in my Mercurial repository, and I'd like to get rid of one of them, but discard all the changes from that branch instead of merging them into the other, and I can't strip out those changesets so I have to merge, how can I do that with the command line client?

If I have two heads in my Mercurial repository, and use TortoiseHg as my client, the repository might look like this:

Then I can get rid of the test2 head by doing a merge and discarding. First I would update to the head I'd like to keep (test3 in this case, which in the image above is already the current parent of my working folder). Then I would right-click and select "Merge with...":

and in the dialog that pops up I would choose to discard the changes from the merge target (ie. the branch I'd like to discard all the changes from):

After this merge has gone through, all the changes in the test2 head has been discarded, and I can commit. The head has now disappeared, but the changeset is still part of history.

My question is this: How can I do the same thing using only the command line client? I can't find any matching options to the hg merge command:

hg merge [-P] [-f] [[-r] REV]

merge working directory with another revision

... snipped text

options:

 -f --force       force a merge with outstanding changes
 -t --tool VALUE  specify merge tool
 -r --rev REV     revision to merge
 -P --preview     review revisions to merge (no merge is performed)
    --mq          operate on patch repository

use "hg -v help merge" to show global options

Edit: debugsetparents worked nicely:

hg debugsetparents . 1
hg commit -m "merged to get rid of changeset #1"

Edit: Attempt to use the --tool internal:local according to one of the answers:

@echo off setlocal if exist repo rd /s /q repo hg init repo cd repo rem revision 0 echo >test1.txt hg commit -m "test1" --addremove rem revision 1 echo >test2.txt hg commit -m "test2" --addremove rem revision 2 hg update 0 echo >test3.txt hg commit -m "test3" --addremove rem now let's get rid of change in revision 1 with merge hg merge --tool internal:local -r 1 hg commit -m "merged" dir

output of execution:

[C:\Temp] :test adding test1.txt adding test2.txt 0 files updated, 0 files merged, 1 files removed, 0 files unresolved adding test3.txt created new head 1 files updated, 0 files merged, 0 files removed, 0 files unresolved (branch merge, don't forget to commit) Volume in drive C is unlabeled Serial number is 0e17:6aba Directory of C:\Temp\repo\* 16.11.2010 20:05 . 16.11.2010 20:05 .. 16.11.2010 20:05 .hg 16.11.2010 20:05 13 test1.txt 16.11.2010 20:05 13 test2.txt 16.11.2010 20:05 13 test3.txt 39 bytes in 3 files and 3 dirs 12 288 bytes allocated 66 600 316 928 bytes free

~~Here the changes introduced in the 2nd changeset (the one with revision number 1), is now present in the merged changeset. This is not what i wanted.~~

回答1:

According to TortoiseHG's source, when you check Discard all changes from merge target (other) revision, it uses the hg debugsetparents command:

hg debugsetparents REV1 [REV2]

manually set the parents of the current working directory

    This is useful for writing repository conversion tools, but should be used with care.

    Returns 0 on success.

use "hg -v help debugsetparents" to show global options

To use:

    hg up <revision-to-keep>
    hg debugsetparents <revision-to-keep> <revision-to-throw-away>
    hg commit -m "Merge to discard ..."

回答2:

If you don't want to use debugsetparents, you can manually revert to the changeset you want to keep before committing:

hg merge --tool internal:local -r HEAD_YOU_WANT_TO_DISCARD
hg revert -r 'tip^'
hg commit

Note, however, that this technique is not necessarily the best approach. You may be better off just closing the head:

hg up HEAD_YOU_WANT_TO_DISCARD
hg commit --close-branch

The documentation here is a little misleading; this only closes the specific head, not the entire branch.