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svntree-conflict

Why does this Subversion merge lead to a tree conflict instead of a merge conflict?

Question

I would have expected a merge conflict in file a.txt because its line 2 was changed on trunk and branch/featurex simultaneously.

  1. Why am I getting a tree conflict instead of a merge conflict?
  2. How do I display the conflict? svn diff?
  3. How do I resolve this conflict?

Example to reproduce the situation

To reproduce the tree conflict, you can make a change on trunk and branches/featurex and try to merge trunk to branches/featurex.

Create a branch:

PS C:\> mkdir demo
PS C:\> cd demo
PS C:\demo> svnadmin create svnrepo
PS C:\demo> cd workspace
PS C:\demo\workspace> mkdir trunk
PS C:\demo\workspace> mkdir branches
PS C:\demo\workspace> mkdir tags
PS C:\demo\workspace> svn add trunk
PS C:\demo\workspace> svn add branches
PS C:\demo\workspace> svn add tags
PS C:\demo\workspace> svn ci -m "Create SVN default folders"
PS C:\demo\workspace> cd trunk
PS C:\demo\workspace\trunk> echo "trunk: line1" > a.txt
PS C:\demo\workspace\trunk> svn add .\a.txt
PS C:\demo\workspace\trunk> svn ci -m "1st commit on trunk"
PS C:\demo\workspace\trunk> svn copy . ..\branches\featurex
PS C:\demo\workspace\trunk> cd ..
PS C:\demo\workspace> cd .\branches
PS C:\demo\workspace\branches> svn ci -m "Create branch for feature x"
Adding         featurex
Adding  (bin)  featurex\a.txt

Commit a change on trunk:

PS C:\demo\workspace\trunk> echo "trunk: line2" >> .\a.txt
PS C:\demo\workspace\trunk> svn ci -m "2nd commit on trunk"

Commit a change on branch (on the same line to create a merge conflict):

PS C:\demo\workspace\branches\featurex> svn up
PS C:\demo\workspace\branches\featurex> echo "branch: line2" >> .\a.txt
PS C:\demo\workspace\branches\featurex> svn ci -m "1st commit on branch"

Merge trunk to branch:

PS C:\demo\workspace\branches\featurex> svn up
PS C:\demo\workspace\branches\featurex> svn merge file:///c:/demo/svnrepo/trunk
--- Merging r2 through r5 into '.':
   C a.txt
--- Recording mergeinfo for merge of r2 through r5 into '.':
 U   .
Summary of conflicts:
  Tree conflicts: 1
PS C:\demo\workspace\branches\featurex>

And there it is: the unexpected tree conflict.

The content of a.txt doesn't show any merges with merge conflicts, it just shows the "branch version" with this content:

trunk: line1
branch: line2

Version

Subversion version 1.7.8 (r1419691) compiled Dec 12 2012, 21:11:09

Solution 
  • PS C:\demo\workspace\trunk> svn copy . ..\branches\featurex
PS C:\demo\workspace\trunk> cd ..
PS C:\demo\workspace> cd .\branches
PS C:\demo\workspace\branches> svn ci -m "Create branch for feature x"

    is not correct way to create a branch as evidenced by the fact that 

    Adding         featurex
Adding  (bin)  featurex\a.txt

    does not mention they are copies. To make them copies, the source must be a repository URL (and the target should be as well). Try creating the branch using:

    PS C:\demo\workspace\trunk> svn copy -m "Create branch for feature x" "^/trunk" "^/branches/featurex"

    (the ^ is alias for repository root when you are inside working copy) Followed by svn update. Or much rather svn switch — you are not supposed to check out more than one branch except to create the initial structure in one commit instead of three!