(emacs.info) Merging

 
 Merging Branches
 ................
 
    When you have finished the changes on a certain branch, you will
 often want to incorporate them into the file's main line of development
 (the trunk).  This is not a trivial operation, because development might
 also have proceeded on the trunk, so that you must "merge" the changes
 into a file that has already been changed otherwise.  VC allows you to
 do this (and other things) with the `vc-merge' command.
 
 `C-x v m (vc-merge)'
      Merge changes into the work file.
 
    `C-x v m' (`vc-merge') takes a set of changes and merges it into the
 current version of the work file.  It first asks you for a branch
 number or a pair of version numbers in the minibuffer.  Then it finds
 the changes from that branch, or between the two versions you
 specified, and merges them into the current version of the current file.
 
    As an example, suppose that you have finished a certain feature on
 branch 1.3.1.  In the meantime, development on the trunk has proceeded
 to version 1.5.  To merge the changes from the branch to the trunk,
 first go to the head version of the trunk, by typing `C-u C-x C-q RET'.
 Version 1.5 is now current.  If locking is used for the file, type
 `C-x C-q' to lock version 1.5 so that you can change it.  Next, type
 `C-x v m 1.3.1 RET'.  This takes the entire set of changes on branch
 1.3.1 (relative to version 1.3, where the branch started, up to the
 last version on the branch) and merges it into the current version of
 the work file.  You can now check in the changed file, thus creating
 version 1.6 containing the changes from the branch.
 
    It is possible to do further editing after merging the branch, before
 the next check-in.  But it is usually wiser to check in the merged
 version, then lock it and make the further changes.  This will keep a
 better record of the history of changes.
 
    When you merge changes into a file that has itself been modified, the
 changes might overlap.  We call this situation a "conflict", and
 reconciling the conflicting changes is called "resolving a conflict".
 
    Whenever conflicts occur during merging, VC detects them, tells you
 about them in the echo area, and asks whether you want help in merging.
 If you say yes, it starts an Ediff session ( Ediff (ediff)Top.).
 
    If you say no, the conflicting changes are both inserted into the
 file, surrounded by "conflict markers".  The example below shows how a
 conflict region looks; the file is called `name' and the current master
 file version with user B's changes in it is 1.11.
 
      <<<<<<< name
        USER A'S VERSION
      =======
        USER B'S VERSION
      >>>>>>> 1.11
 
    Then you can resolve the conflicts by editing the file manually.  Or
 you can type `M-x vc-resolve-conflicts' after visiting the file.  This
 starts an Ediff session, as described above.
Info Catalog
(emacs.info) Creating Branches
(emacs.info) Branches
(emacs.info) Multi-User Branching
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