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From Stefan Sperling <s...@elego.de>
Subject Re: What branching patterns work with Subversion reintegrate merge?
Date Sat, 19 Mar 2016 11:10:34 GMT
On Fri, Mar 18, 2016 at 08:22:06PM +0000, Bob Berger wrote:
> Subversion requires you to do a sync merge from your trunk to a branch,
> before you can do a reintegrate merge from the branch back to the trunk. But
> the sync merge seems incompatible with a branching pattern where the trunk
> contains ongoing development and branches contain releases

Use cherry-picking merges.
'svn help merge' (output qouted below) contains all you need to know.

The Subversion project itself uses the branching pattern you describe,
so I'm quite sure it works and is fully supported ;-)
If you want to read about our workflow, see here:
http://subversion.apache.org/docs/community-guide/releasing.html#release-stabilization

merge: Merge changes into a working copy.
usage: 1. merge SOURCE[@REV] [TARGET_WCPATH]
          (the 'complete' merge)
       2. merge [-c M[,N...] | -r N:M ...] SOURCE[@REV] [TARGET_WCPATH]
          (the 'cherry-pick' merge)
       3. merge SOURCE1[@REV1] SOURCE2[@REV2] [TARGET_WCPATH]
          (the '2-URL' merge)

  1. This form, with one source path and no revision range, is called
     a 'complete' merge:

       svn merge SOURCE[@REV] [TARGET_WCPATH]

     The complete merge is used for the 'sync' and 'reintegrate' merges
     in the 'feature branch' pattern described below. It finds all the
     changes on the source branch that have not already been merged to the
     target branch, and merges them into the working copy. Merge tracking
     is used to know which changes have already been merged.

     SOURCE specifies the branch from where the changes will be pulled, and
     TARGET_WCPATH specifies a working copy of the target branch to which
     the changes will be applied. Normally SOURCE and TARGET_WCPATH should
     each correspond to the root of a branch. (If you want to merge only a
     subtree, then the subtree path must be included in both SOURCE and
     TARGET_WCPATH; this is discouraged, to avoid subtree mergeinfo.)

     SOURCE is usually a URL. The optional '@REV' specifies both the peg
     revision of the URL and the latest revision that will be considered
     for merging; if REV is not specified, the HEAD revision is assumed. If
     SOURCE is a working copy path, the corresponding URL of the path is
     used, and the default value of 'REV' is the base revision (usually the
     revision last updated to).

     TARGET_WCPATH is a working copy path; if omitted, '.' is generally
     assumed. There are some special cases:

       - If SOURCE is a URL:

           - If the basename of the URL and the basename of '.' are the
             same, then the differences are applied to '.'. Otherwise,
             if a file with the same basename as that of the URL is found
             within '.', then the differences are applied to that file.
             In all other cases, the target defaults to '.'.

       - If SOURCE is a working copy path:

           - If the source is a file, then differences are applied to that
             file (useful for reverse-merging earlier changes). Otherwise,
             if the source is a directory, then the target defaults to '.'.

     In normal usage the working copy should be up to date, at a single
     revision, with no local modifications and no switched subtrees.

       - The 'Feature Branch' Merging Pattern -

     In this commonly used work flow, known also as the 'development
     branch' pattern, a developer creates a branch and commits a series of
     changes that implement a new feature. The developer periodically
     merges all the latest changes from the parent branch so as to keep the
     development branch up to date with those changes. When the feature is
     complete, the developer performs a merge from the feature branch to
     the parent branch to re-integrate the changes.

         parent --+----------o------o-o-------------o--
                   \            \           \      /
                    \          merge      merge  merge
                     \            \           \  /
         feature      +--o-o-------o----o-o----o-------

     A merge from the parent branch to the feature branch is called a
     'sync' or 'catch-up' merge, and a merge from the feature branch to the
     parent branch is called a 'reintegrate' merge.

       - Sync Merge Example -
                                 ............
                                .            .
         trunk  --+------------L--------------R------
                   \                           \
                    \                          |
                     \                         v
         feature      +------------------------o-----
                             r100            r200

     Subversion will locate all the changes on 'trunk' that have not yet
     been merged into the 'feature' branch. In this case that is a single
     range, r100:200. In the diagram above, L marks the left side (trunk@100)
     and R marks the right side (trunk@200) of the merge source. The
     difference between L and R will be applied to the target working copy
     path. In this case, the working copy is a clean checkout of the entire
     'feature' branch.

     To perform this sync merge, have a clean working copy of the feature
     branch and run the following command in its top-level directory:

         svn merge ^/trunk

     Note that the merge is now only in your local working copy and still
     needs to be committed to the repository so that it can be seen by
     others. You can review the changes and you may have to resolve
     conflicts before you commit the merge.

       - Reintegrate Merge Example -

     The feature branch was last synced with trunk up to revision X. So the
     difference between trunk@X and feature@HEAD contains the complete set
     of changes that implement the feature, and no other changes. These
     changes are applied to trunk.

                    rW                   rX
         trunk ------+--------------------L------------------o
                      \                    .                 ^
                       \                    .............   /
                        \                                . /
         feature         +--------------------------------R

     In the diagram above, L marks the left side (trunk@X) and R marks the
     right side (feature@HEAD) of the merge. The difference between the
     left and right side is merged into trunk, the target.

     To perform the merge, have a clean working copy of trunk and run the
     following command in its top-level directory:

         svn merge ^/feature

     To prevent unnecessary merge conflicts, a reintegrate merge requires
     that TARGET_WCPATH is not a mixed-revision working copy, has no local
     modifications, and has no switched subtrees.

     A reintegrate merge also requires that the source branch is coherently
     synced with the target -- in the above example, this means that all
     revisions between the branch point W and the last merged revision X
     are merged to the feature branch, so that there are no unmerged
     revisions in-between.


  2. This form is called a 'cherry-pick' merge:

       svn merge [-c M[,N...] | -r N:M ...] SOURCE[@REV] [TARGET_WCPATH]

     A cherry-pick merge is used to merge specific revisions (or revision
     ranges) from one branch to another. By default, this uses merge
     tracking to automatically skip any revisions that have already been
     merged to the target; you can use the --ignore-ancestry option to
     disable such skipping.

     SOURCE is usually a URL. The optional '@REV' specifies only the peg
     revision of the URL and does not affect the merge range; if REV is not
     specified, the HEAD revision is assumed. If SOURCE is a working copy
     path, the corresponding URL of the path is used, and the default value
     of 'REV' is the base revision (usually the revision last updated to).

     TARGET_WCPATH is a working copy path; if omitted, '.' is generally
     assumed. The special cases noted above in the 'complete' merge form
     also apply here.

     The revision ranges to be merged are specified by the '-r' and/or '-c'
     options. '-r N:M' refers to the difference in the history of the
     source branch between revisions N and M. You can use '-c M' to merge
     single revisions: '-c M' is equivalent to '-r <M-1>:M'. Each such
     difference is applied to TARGET_WCPATH.

     If the mergeinfo in 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.

     A 'reverse range' can be used to undo changes. For example, when
     source and target refer to the same branch, a previously committed
     revision can be 'undone'. In a reverse range, N is greater than M in
     '-r N:M', or the '-c' option is used with a negative number: '-c -M'
     is equivalent to '-r M:<M-1>'. Undoing changes like this is also known
     as performing a 'reverse merge'.

     Multiple '-c' and/or '-r' options may be specified and mixing of
     forward and reverse ranges is allowed.

       - Cherry-pick Merge Example -

     A bug has been fixed on trunk in revision 50. This fix needs to
     be merged from trunk onto the release branch.

            1.x-release  +-----------------------o-----
                        /                        ^
                       /                         |
                      /                          |
         trunk ------+--------------------------LR-----
                                                r50

     In the above diagram, L marks the left side (trunk@49) and R marks the
     right side (trunk@50) of the merge. The difference between the left
     and right side is applied to the target working copy path.

     Note that the difference between revision 49 and 50 is exactly those
     changes that were committed in revision 50, not including changes
     committed in revision 49.

     To perform the merge, have a clean working copy of the release branch
     and run the following command in its top-level directory; remember
     that the default target is '.':

         svn merge -c50 ^/trunk

     You can also cherry-pick several revisions and/or revision ranges:

         svn merge -c50,54,60 -r65:68 ^/trunk


  3. This form is called a '2-URL merge':

       svn merge SOURCE1[@REV1] SOURCE2[@REV2] [TARGET_WCPATH]

     You should use this merge variant only if the other variants do not
     apply to your situation, as this variant can be quite complex to
     master.

     Two source URLs are specified, identifying two trees on the same
     branch or on different branches. The trees are compared and the
     difference from SOURCE1@REV1 to SOURCE2@REV2 is applied to the
     working copy of the target branch at TARGET_WCPATH. The target
     branch may be the same as one or both sources, or different again.
     The three branches involved can be completely unrelated.

     TARGET_WCPATH is a working copy path; if omitted, '.' is generally
     assumed. The special cases noted above in the 'complete' merge form
     also apply here.

     SOURCE1 and/or SOURCE2 can also be specified as a working copy path,
     in which case the merge source URL is derived from the working copy.

       - 2-URL Merge Example -

     Two features have been developed on separate branches called 'foo' and
     'bar'. It has since become clear that 'bar' should be combined with
     the 'foo' branch for further development before reintegration.

     Although both feature branches originate from trunk, they are not
     directly related -- one is not a direct copy of the other. A 2-URL
     merge is necessary.

     The 'bar' branch has been synced with trunk up to revision 500.
     (If this revision number is not known, it can be located using the
     'svn log' and/or 'svn mergeinfo' commands.)
     The difference between trunk@500 and bar@HEAD contains the complete
     set of changes related to feature 'bar', and no other changes. These
     changes are applied to the 'foo' branch.

                           foo  +-----------------------------------o
                               /                                    ^
                              /                                    /
                             /              r500                  /
         trunk ------+------+-----------------L--------->        /
                      \                        .                /
                       \                        ............   /
                        \                                   . /
                    bar  +-----------------------------------R

     In the diagram above, L marks the left side (trunk@500) and R marks
     the right side (bar@HEAD) of the merge. The difference between the
     left and right side is applied to the target working copy path, in
     this case a working copy of the 'foo' branch.

     To perform the merge, have a clean working copy of the 'foo' branch
     and run the following command in its top-level directory:

         svn merge ^/trunk@500 ^/bar

     The exact changes applied by a 2-URL merge can be previewed with svn's
     diff command, which is a good idea to verify if you do not have the
     luxury of a clean working copy to merge to. In this case:

         svn diff ^/trunk@500 ^/bar@HEAD


  The following applies to all types of merges:

  To prevent unnecessary merge conflicts, svn merge requires that
  TARGET_WCPATH is not a mixed-revision working copy. Running 'svn update'
  before starting a merge ensures that all items in the working copy are
  based on the same revision.

  If possible, you should have no local modifications in the merge's target
  working copy prior to the merge, to keep things simpler. It will be
  easier to revert the merge and to understand the branch's history.

  Switched sub-paths should also be avoided during merging, as they may
  cause incomplete merges and create subtree mergeinfo.

  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.

    - Merge Tracking -

  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 (i.e. if one has originally been created by copying the
  other). This is verified and enforced when using sync merges and
  reintegrate merges.

  The --ignore-ancestry option prevents merge tracking and thus ignores
  mergeinfo, neither considering it nor recording it.

    - Merging from foreign repositories -

  Subversion does support merging from foreign repositories.
  While all merge source URLs must point to the same repository, the merge
  target working copy may come from a different repository than the source.
  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 for merges from foreign
  repositories.

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
                             If ARG is of the form ARG1-ARG2 then this is like
                             ARG1:ARG2, where ARG1 is inclusive
  -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 deletions even if deleted contents don't match
  --dry-run                : try operation but make no changes
  --diff3-cmd ARG          : use ARG as merge command
  --record-only            : merge only mergeinfo differences
  -x [--extensions] ARG    : Specify differencing options for external diff or
                             internal diff or blame. Default: '-u'. Options are
                             separated by spaces. Internal diff and blame take:
                               -u, --unified: Show 3 lines of unified context
                               -b, --ignore-space-change: Ignore changes in
                                 amount of white space
                               -w, --ignore-all-space: Ignore all white space
                               --ignore-eol-style: Ignore changes in EOL style
                               -U ARG, --context ARG: Show ARG lines of context
                               -p, --show-c-function: Show C function name
  --ignore-ancestry        : disable merge tracking; diff nodes as if related
  --accept ARG             : specify automatic conflict resolution action
                             ('postpone', 'working', 'base', 'mine-conflict',
                             'theirs-conflict', 'mine-full', 'theirs-full',
                             'edit', 'launch')
                             (shorthand: 'p', 'mc', 'tc', 'mf', 'tf', 'e', 'l')
  --reintegrate            : deprecated
  --allow-mixed-revisions  : Allow operation on mixed-revision working copy.
                             Use of this option is not recommended!
                             Please run 'svn update' instead.
  -v [--verbose]           : print extra information

Global options:
  --username ARG           : specify a username ARG
  --password ARG           : specify a password ARG (caution: on many operating
                             systems, other users will be able to see this)
  --no-auth-cache          : do not cache authentication tokens
  --non-interactive        : do no interactive prompting (default is to prompt
                             only if standard input is a terminal device)
  --force-interactive      : do interactive prompting even if standard input
                             is not a terminal device
  --trust-server-cert      : deprecated; same as
                             --trust-server-cert-failures=unknown-ca
  --trust-server-cert-failures ARG : with --non-interactive, accept SSL server
                             certificates with failures; ARG is comma-separated
                             list of 'unknown-ca' (Unknown Authority),
                             'cn-mismatch' (Hostname mismatch), 'expired'
                             (Expired certificate), 'not-yet-valid' (Not yet
                             valid certificate) and 'other' (all other not
                             separately classified certificate errors).
  --config-dir 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


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