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Re: duplicate merge conflict

From: Daniel Walter <d2walter_at_hotmail.com>
Date: Tue, 19 Apr 2011 21:34:17 -0400

I understand what is going on now, but this seems to indicate that I will
need to look up revision numbers from tags every time I do a merge in SVN.
Is there any automated way of doing this? It seems like a huge step
backwards to go from using symbols that mean something to me to using
numbers that only mean something to my version control software.

Perhaps I should be using some other form of automated merging in SVN, but
none of the automated merge schemes listed is remotely like my merge
workflow. I have three versions.

4.1 on a branch
4.2 on a branch
4.3 on a trunk

I need to merge any bug fixes or changes that I make to the older versions
forward into the newer versions and then the trunk. Currently I make a new
tag on each branch whenever I merge changes forward.

Daniel
--------------------------------------------------
From: "Stefan Sperling" <stsp_at_elego.de>
Sent: Tuesday, April 19, 2011 6:50 PM
To: "Daniel Walter" <d2walter_at_hotmail.com>
Cc: "Bob Archer" <Bob.Archer_at_amsi.com>; <users_at_subversion.apache.org>
Subject: Re: duplicate merge conflict

> On Tue, Apr 19, 2011 at 10:56:28AM -0400, Daniel Walter wrote:
>> svn merge appears to work with revision numbers but not symbolically
>> with tags. Is this expected?
>>
>> The merge happens twice if I use tags:
>> svn merge tag1 tag2 --non-interactive
>>
>> But when I find the revisions with svn info
>> svn info tag1
>> Last Changed Rev: 457
>>
>> svn info tag2
>> Last Changed Rev: 467
>>
>> and then do the merge based on these revision numbers
>> svn merge -r 457:467 trunk --non-interactive
>>
>> the merge happens correctly
>>
>
> That is because the tags aren't directly ancestrally related,
> while if you are using the branch, the merges source and target
> are directly related.
>
> Do not use tags as merge left/right. That's what people used to do in the
> CVS world but it doesn't really translate into the Subversion world
> with merge tracking. In Subversion you should merge between directly
> related branches.
>
> The new svn merge help text in Subversion 1.7 might shed some light on
> how svn merge is supposed to be used so I am quoting it below:
>
> =====
>
> merge: Apply the differences between two sources to a working copy path.
> usage: 1. merge [-c M[,N...] | -r N:M ...] SOURCE[@REV] [TARGET_WCPATH]
> 2. merge --reintegrate SOURCE[@REV] [TARGET_WCPATH]
> 3. merge SOURCE1[@N] SOURCE2[@M] [TARGET_WCPATH]
>
> 1. The first form is called a "sync", or "cherry-pick", merge:
> svn merge [-c M[,N...] | -r N:M ...] SOURCE[@REV] [TARGET_WCPATH]
>
> A sync merge is used to merge into a branch any unmerged changes
> made on its immediate ancestor branch.
>
> A cherry-picking merge is used to merge specific revisions from
> one branch to another.
>
> SOURCE is usually a URL. The source of a cherry-picking merge can
> also be a working copy path, in which case the corresponding URL
> of the path is used.
>
> If REV is specified, it is used as the peg revision for SOURCE,
> i.e. SOURCE is looked up in the repository at revision REV.
> If REV is not specified, the HEAD revision is assumed.
>
> TARGET_WCPATH is a working copy of the branch the changes will
> be applied to.
>
> '-r N:M' specifies a revision range to be merged. The difference
> between SOURCE_at_REV as it existed at revision N, and SOURCE_at_REV at
> it existed at revision M, is merged into TARGET_WCPATH. If no
> revision range is specified, the default range of 0:REV is used.
>
> If mergeinfo within TARGET_WCPATH indicates that revisions within
> the range were already merged, changes made in those revisions
> are not merged again. If needed, the range is broken into multiple
> sub-ranges, and each sub-range is merged separately.
>
> If N is greater than M, the range is a "reverse range".
> A reverse range can be used to undo changes made to SOURCE
> between revisions N and M.
>
> '-c M' is equivalent to the range '-r <M-1>:M'.
> '-c -M' does the reverse: '-r M:<M-1>'.
>
> Multiple '-c' and/or '-r' options may be specified and mixing of
> forward and reverse ranges is allowed.
>
> - Sync Merge Example -
>
> A feature is being developed on a branch called "feature".
> The feature branch is regularly synced with trunk to keep up with
> changes made there.
>
> feature +------------------------o-----
> / ^
> / /
> / .............../
> trunk ------+------------L--------------R------
> r100 r200
>
> In the above diagram, L marks the "left" side of the merge
> (trunk_at_100), and R marks the "right" side of the merge (trunk_at_200).
> The difference between the left and right side is merged into the
> target.
>
> To perform the merge, check out a working copy of the feature
> branch and run the following command in the top-level directory
> of the working copy:
>
> svn merge ^/trunk
>
> The default revision range is -r0:HEAD, so any unmerged changes
> will be merged.
>
> - Cherry-picking Merge Example -
>
> A bug has been fixed on trunk on revision 50. This fix needs to
> be merged from the trunk into the release branch.
>
> 1.x-release +-----------------------o-----
> / ^
> / |
> / |
> trunk ------+--------------------------LR-----
> r50
>
> In the above diagram, L marks the left side of the merge (trunk_at_49)
> and R marks the right side of the merge (trunk_at_50).
> The difference between the left and right side is merged into the
> target.
>
> To perform the merge, check out a working copy of the release
> branch and run the following command in the top-level directory
> of the working copy:
>
> svn merge -c50 ^/trunk
>
> If several commits to trunk were related to the fix, multiple
> revisions can be merged:
>
> svn merge -c50,54,60 ^/trunk
>
>
> 2. The second form is called a "reintegrate merge":
> svn merge --reintegrate SOURCE[@REV] [TARGET_WCPATH]
>
> SOURCE is the URL of a branch to be merged back into (usually) its
> immediate ancestor branch. If REV is specified, it is used a
> the peg revision for SOURCE, i.e. SOURCE is looked up in the
> repository at revision REV. If REV is not specified, the HEAD
> revision is assumed.
>
> TARGET_WCPATH is a working copy of the branch the changes will
> be applied to.
>
> - Reintegrate Merge Example -
>
> A feature has been developed on a branch called "feature".
> The feature branch started as a copy of trunk_at_W. Work on the
> feature has completed and it should be merged back into the trunk.
>
> The feature branch was last synced with its immediate ancestor,
> the trunk, in revision X. So the difference between trunk_at_X and
> feature_at_HEAD contains the complete set of changes that implement
> the feature, and no other changes. These changes are applied to
> the trunk.
>
> feature +-------------------------------R
> / . \
> / .............. \
> / . v
> trunk ------+--------------------L------------------o
> rW rX
>
> In the diagram above, L marks the left side of the merge (trunk_at_X),
> and R marks the right side of the merge (feature_at_HEAD). The difference
> between the left and right side is merged into the target.
>
> To perform the merge, check out a working copy of the trunk, and run
> the following command in the top-level directory of the working copy:
>
> svn merge --reintegrate ^/feature
>
> To prevent unnecessary merge conflicts, reintegrate merges require
> that TARGET_WCPATH is not a mixed-revision working copy, has no
> local modifications, and has no switched subtrees.
>
> Reintegrate merges also require that the reintegrate source be fully
> synced with the target since their common branch point.
> In the above example this means that all of the changes made
> on trunk between revision W and revision X are fully merged to
> the feature branch before it can be reintegrated back to trunk.
>
> After the reintegrate merge, the feature branch cannot be synced
> to the trunk again without merge conflicts. If further work must
> be done on the feature branch, it should be deleted and then
> re-created.
>
>
> 3. The third form is called a "2-URL merge":
> svn merge SOURCE1[@N] SOURCE2[@M] [TARGET_WCPATH]
>
> Two source URLs are specified, together with two revisions N and M.
> The two sources to be compared at the specified revisions, and the
> difference is applied to TARGET_WCPATH, which is a path to a working
> copy of another branch.
>
> The revisions default to HEAD if omitted.
>
> If TARGET_WCPATH is omitted, a default value of '.' is assumed,
> unless the sources have identical basenames that match a file
> within '.'; In which case, the differences will be applied to
> that file.
>
> The sources can also be specified as working copy paths, in which
> case the URLs of the merge sources are derived from the working
> copies.
>
> This is the most flexible type of merge, but also the most difficult
> to use. It can be used to merge the differences between two (possibly
> ancestrally unrelated) branches into a working copy of another branch.
> This type of merge should be used very carefully because the
> probability
> of merge conflicts is quite high. In most use cases, a sync,
> cherry-pick,
> or reintegrate merge is sufficient and reduces the chances of
> mistakes.
>
> - 2-URL Merge Example -
>
> A feature has been developed on a branch called "feature".
> Development for the upcoming 3.0 release has happened in parallel on
> the "3.x-release" branch. The work on the feature branch must be
> merged to the 3.x-release branch. However, the feature branch and
> the 3.x-release branch are not directly related, so a 2-URL merge
> is needed.
> The feature branch was last synced with its immediate ancestor,
> the trunk, up to revision 500. So the difference between trunk_at_500
> and feature_at_HEAD contains the complete set of changes related to
> the feature, and no other changes. These changes are applied to
> the 3.x-release branch.
>
> 3.x-release +-----------------------------------o
> / ^
> / /
> / r500 /
> trunk ------+------+-----------------L---------> /
> \ . /
> \ ........... /
> \ . /
> feature +-----------------------------------R
>
> In the diagram above, L marks the left side of the merge (trunk_at_500),
> and R marks the right side of the merge is (feature_at_HEAD).
> The difference between the left and right side is merged into the
> target.
>
> To perform the merge, check out a working copy of the 3.x-release
> branch and run the following command in the top-level directory
> of the working copy:
>
> svn merge ^/trunk_at_500 ^/feature
>
> Before performing a 2-URL merge, it is a good idea to preview the
> changes which will be merged, because there is no guarantee that
> the merge will be free of conflicts. The preview can be done with
> the svn diff command:
>
> svn diff ^/trunk_at_500 ^/feature_at_HEAD
>
> Note that a 2-URL merge can also merge from foreign repositories.
> While SOURCE1 and SOURCE2 must both come from the same repository,
> TARGET_WCPATH may come from a different repository than the sources.
> However, there are some caveats. Most notably, copies made in the
> merge source will be transformed into plain additions in the merge
> target. Also, merge-tracking is not supported.
>
>
> The following applies to all types of merges:
>
> For each merged item a line will be printed with characters reporting
> the action taken. These characters have the following meaning:
>
> A Added
> D Deleted
> U Updated
> C Conflict
> G Merged
> E Existed
> R Replaced
>
> Characters in the first column report about the item itself.
> Characters in the second column report about properties of the item.
> A 'C' in the third column indicates a tree conflict, while a 'C' in
> the first and second columns indicate textual conflicts in files
> and in property values, respectively.
>
> NOTE: Subversion uses the svn:mergeinfo property to track merge
> history. This property is considered at the start of a merge to
> determine what to merge and it is updated at the conclusion of the
> merge to describe the merge that took place. Mergeinfo is used only
> if the two sources are on the same line of history -- if the first
> source is an ancestor of the second, or vice-versa. This is guaranteed
> to be the case when using sync merges and reintegrate merges.
> The --ignore-ancestry option prevents merge tracking and thus
> ignores mergeinfo, neither considering it nor recording it.
>
> Valid options:
> -r [--revision] ARG : ARG (some commands also take ARG1:ARG2 range)
> A revision argument can be one of:
> NUMBER revision number
> '{' DATE '}' revision at start of the date
> 'HEAD' latest in repository
> 'BASE' base rev of item's working
> copy
> 'COMMITTED' last commit at or before BASE
> 'PREV' revision just before COMMITTED
> -c [--change] ARG : the change made by revision ARG (like -r
> ARG-1:ARG)
> If ARG is negative this is like -r ARG:ARG-1
> -N [--non-recursive] : obsolete; try --depth=files
> or --depth=immediates
> --depth ARG : limit operation by depth ARG ('empty',
> 'files',
> 'immediates', or 'infinity')
> -q [--quiet] : print nothing, or only summary information
> --force : force operation to run
> --dry-run [--dry] : try operation but make no changes
> --diff3-cmd ARG : use ARG as merge command
> --record-only [--ro] : merge only mergeinfo differences
> -x [--extensions] ARG : Default: '-u'. When Subversion is invoking an
> external diff program, ARG is simply passed
> along
> to the program. But when Subversion is using
> its
> default internal diff implementation, or when
> Subversion is displaying blame annotations,
> ARG
> could be any of the following:
> -u (--unified):
> Output 3 lines of unified context.
> -b (--ignore-space-change):
> Ignore changes in the amount of white
> space.
> -w (--ignore-all-space):
> Ignore all white space.
> --ignore-eol-style:
> Ignore changes in EOL style.
> -p (--show-c-function):
> Show C function name in diff output.
> --ignore-ancestry [--ia] : ignore ancestry when calculating merges
> --accept ARG : specify automatic conflict resolution action
> ('postpone', 'base', 'mine-conflict',
> 'theirs-conflict', 'mine-full', 'theirs-full',
> 'edit', 'launch')
> --reintegrate [--ri] : merge a branch back into its parent branch
> --allow-mixed-revisions : Allow merge into mixed-revision working copy.
> Use of this option is not recommended!
> Please run 'svn update' instead.
>
> Global options:
> --username ARG : specify a username ARG
> --password ARG : specify a password ARG
> --no-auth-cache [--nac] : do not cache authentication tokens
> --non-interactive : do no interactive prompting
> --trust-server-cert : accept unknown SSL server certificates without
> prompting (but only with '--non-interactive')
> --config-dir [--cd] ARG : read user configuration files from directory
> ARG
> --config-option ARG : set user configuration option in the format:
> FILE:SECTION:OPTION=[VALUE]
> For example:
> servers:global:http-library=serf
>
>
Received on 2011-04-20 03:34:52 CEST

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