Conflict Types

Some operations, like merge, revert and pull, modify the contents of your working tree. These modifications are programmatically generated, and so they may conflict with the current state of your working tree.

When conflicts are present in your working tree (as shown by bzr conflicts), you should resolve them and then inform bzr that the conflicts have been resolved.

Resolving conflicts is sometimes not obvious. Either because the user that should resolve them is not the one responsible for their occurrence, as is the case when merging other people’s work or because some conflicts are presented in a way that is not easy to understand.

Bazaar tries to avoid conflicts ; its aim is to ask you to resolve the conflict if and only if there’s an actual conceptual conflict in the source tree. Because Bazaar doesn’t understand the real meaning of the files being versioned, it can, when faced with ambiguities, fall short in either direction trying to resolve the conflict itself. Many kinds of changes can be combined programmatically, but sometimes only a human can determine the right thing to do.

When Bazaar generates a conflict, it adds information into the working tree to present the conflicting versions, and it’s up to you to find the correct resolution.

Whatever the conflict is, resolving it is roughly done in two steps:

  • modify the working tree content so that the conflicted item is now in the state you want to keep,
  • inform Bazaar that the conflict is now solved and ask to cleanup any remaining generated information (bzr resolve <item>).

For most conflict types, there are some obvious ways to modify the working tree and put it into the desired state. For some types of conflicts, Bazaar itself already made a choice, when possible.

Yet, whether Bazaar makes a choice or not, there are some other simple but different ways to resolve the conflict.

Each type of conflict is explained below, and the action which must be done to resolve the conflict is outlined.

Various actions are available depending on the kind of conflict, for some of these actions, Bazaar can provide some help. In the end you should at least inform Bazaar that you’re done with the conflict with:

``bzr resolve FILE --action=done'

Note that this is the default action when a single file is involved so you can simply use:

``bzr resolve FILE``

See bzr help resolve for more details.

Text conflicts

Typical message:

Text conflict in FILE

These are produced when a text merge cannot completely reconcile two sets of text changes. Bazaar will emit files for each version with the extensions THIS, OTHER, and BASE. THIS is the version of the file from the target tree, i.e. the tree that you are merging changes into. OTHER is the version that you are merging into the target. BASE is an older version that is used as a basis for comparison.

In the main copy of the file, Bazaar will include all the changes that it could reconcile, and any un-reconciled conflicts are surrounded by “herringbone” markers like <<<<<<<.

Say the initial text is “The project leader released it.”, and THIS modifies it to “Martin Pool released it.”, while OTHER modifies it to “The project leader released Bazaar.” A conflict would look like this:

<<<<<<< TREE
Martin Pool released it.
=======
The project leader released Bazaar.
>>>>>>> MERGE-SOURCE

The correct resolution would be “Martin Pool released Bazaar.”

You can handle text conflicts either by editing the main copy of the file, or by invoking external tools on the THIS, OTHER and BASE versions. It’s worth mentioning that resolving text conflicts rarely involves picking one set of changes over the other (but see below when you encounter these cases). More often, the two sets of changes must be intelligently combined.

If you edit the main copy, be sure to remove the herringbone markers. When you are done editing, the file should look like it never had a conflict, and be ready to commit.

When you have resolved text conflicts, just run bzr resolve --auto, and Bazaar will auto-detect which conflicts you have resolved.

When the conflict is resolved, Bazaar deletes the previously generated .BASE, .THIS and .OTHER files if they are still present in the working tree.

When you want to pick one set of changes over the other, you can use bzr resolve with one of the following actions:

  • --action=take-this will issue mv FILE.THIS FILE,
  • --action=take-other will issue mv FILE.OTHER FILE.

Note that if you have modified FILE.THIS or FILE.OTHER, these modifications will be taken into account.

Content conflicts

Typical message:

Contents conflict in FILE

This conflict happens when there are conflicting changes in the working tree and the merge source, but the conflicted items are not text files. They may be binary files, or symlinks, or directories. It can even happen with files that are deleted on one side, and modified on the other.

Like text conflicts, Bazaar will emit THIS, OTHER and BASE files. (They may be regular files, symlinks or directories). But it will not include a “main copy” of the file with herringbone conflict markers. It will appear that the “main copy” has been renamed to THIS or OTHER.

To resolve that kind of conflict, you should rebuild FILE from either version or a combination of both.

bzr resolve recognizes the following actions:

  • --action=take-this will issue bzr mv FILE.THIS FILE,
  • --action=take-other will issue bzr mv FILE.OTHER FILE,
  • --action=done will just mark the conflict as resolved.

Any action will also delete the previously generated .BASE, .THIS and .OTHER files if they are still present in the working tree.

Bazaar cannot auto-detect when conflicts of this kind have been resolved.

Tag conflicts

Typical message:

Conflicting tags:
    version-0.1

When pulling from or pushing to another branch, Bazaar informs you about tags that conflict between the two branches; that is the same tag points to two different revisions. You need not resolve these conflicts, but subsequent uses of pull or push will result in the same message.

To resolve the conflict, you must apply the correct tags to either the target branch or the source branch as appropriate. Use “bzr tags –show-ids -d SOURCE_URL” to see the tags in the source branch. If you want to make the target branch’s tags match the source branch, then in the target branch do bzr tag --force -r revid:REVISION_ID CONFLICTING_TAG for each of the CONFLICTING_TAGs, where REVISION_ID comes from the list of tags in the source branch. You need not call “bzr resolve” after doing this. To resolve in favor of the target branch, you need to similarly use tag --force in the source branch. (Note that pulling or pushing using –overwrite will overwrite all tags as well.)

Duplicate paths

Typical message:

Conflict adding file FILE.  Moved existing file to FILE.moved.

Sometimes Bazaar will attempt to create a file using a pathname that has already been used. The existing file will be renamed to “FILE.moved”.

To resolve that kind of conflict, you should rebuild FILE from either version or a combination of both.

bzr resolve recognizes the following actions:

  • --action=take-this will issue bzr rm FILE ; bzr mv FILE.moved FILE,
  • --action=take-other will issue bzr rm FILE.moved,
  • --action=done will just mark the conflict as resolved.

Note that you must get rid of FILE.moved before using --action=done.

Bazaar cannot auto-detect when conflicts of this kind have been resolved.

Unversioned parent

Typical message:

Conflict because FILE is not versioned, but has versioned children.

Sometimes Bazaar will attempt to create a file whose parent directory is not versioned. This happens when the directory has been deleted in the target, but has a new child in the source, or vice versa. In this situation, Bazaar will version the parent directory as well. Resolving this issue depends very much on the particular scenario. You may wish to rename or delete either the file or the directory. When you are satisfied, you can run “bzr resolve FILE” to mark the conflict as resolved.

Missing parent

Typical message:

Conflict adding files to FILE.  Created directory.

This happens when a directory has been deleted in the target, but has new children in the source. This is similar to the “unversioned parent” conflict, except that the parent directory does not exist, instead of just being unversioned. In this situation, Bazaar will create the missing parent. Resolving this issue depends very much on the particular scenario.

To resolve that kind of conflict, you should either remove or rename the children or the directory or a combination of both.

bzr resolve recognizes the following actions:

  • --action=take-this will issue bzr rm directory including the children,
  • --action=take-other will acknowledge Bazaar choice to keep the children and restoring the directory,
  • --action=done will just mark the conflict as resolved.

Bazaar cannot auto-detect when conflicts of this kind have been resolved.

Deleting parent

Typical message:

Conflict: can't delete DIR because it is not empty.  Not deleting.

This is the opposite of “missing parent”. A directory is deleted in the source, but has new children in the target (either because a directory deletion is merged or because the merge introduce new children). Bazaar will retain the directory. Resolving this issue depends very much on the particular scenario.

To resolve that kind of conflict, you should either remove or rename the children or the directory or a combination of both.

bzr resolve recognizes the following actions:

  • --action=take-this will acknowledge Bazaar choice to keep the directory,
  • --action=take-other will issue bzr rm directory including the children,
  • --action=done will just mark the conflict as resolved.

Note that when merging a directory deletion, if unversioned files are present, they become potential orphans has they don’t have a directory parent anymore.

Handling such orphans, before the conflict is created, is controlled by setting the bzr.transform.orphan_policy configuration option.

There are two possible values for this option:

  • conflict (the default): will leave the orphans in place and generate a conflicts,
  • move: will move the orphans to a bzr-orphans directory at the root of the working tree with names like <file>.~#~.

Bazaar cannot auto-detect when conflicts of this kind have been resolved.

Path conflict

Typical message:

Path conflict: PATH1 / PATH2

This happens when the source and target have each modified the name or parent directory of a file. Bazaar will use the path elements from the source.

To resolve that kind of conflict, you just have to decide what name should be retained for the file involved.

bzr resolve recognizes the following actions:

  • --action=take-this will revert Bazaar choice and keep PATH1 by issuing bzr mv PATH2 PATH1,
  • --action=take-other will acknowledge Bazaar choice of keeping PATH2,
  • --action=done will just mark the conflict as resolved.

Bazaar cannot auto-detect when conflicts of this kind have been resolved.

Parent loop

Typical message:

Conflict moving FILE into DIRECTORY.  Cancelled move.

This happens when the source and the target have each moved directories, so that, if the change could be applied, a directory would be contained by itself. For example:

$ bzr init
$ bzr mkdir white
$ bzr mkdir black
$ bzr commit -m "BASE"
$ bzr branch . ../other
$ bzr mv white black
$ bzr commit -m "THIS"
$ bzr mv ../other/black ../other/white
$ bzr commit ../other -m "OTHER"
$ bzr merge ../other

In this situation, Bazaar will cancel the move, and leave white in black. To resolve that kind of conflict, you just have to decide what name should be retained for the directories involved.

bzr resolve recognizes the following actions:

  • --action=take-this will acknowledge Bazaar choice of leaving white in black,

  • --action=take-other will revert Bazaar choice and move black in

    white by issuing bzr mv black/white white ; bzr mv black white,

  • --action=done will just mark the conflict as resolved.

Bazaar cannot auto-detect when conflicts of this kind have been resolved.

Non-directory parent

Typical message:

Conflict: foo.new is not a directory, but has files in it.
Created directory.

This happens when one side has added files to a directory, and the other side has changed the directory into a file or symlink. For example:

$ bzr init
$ bzr mkdir foo
$ bzr commit -m "BASE"
$ bzr branch . ../other
$ rmdir foo
$ touch foo
$ bzr commit -m "THIS"
$ bzr mkdir ../other/foo/bar
$ bzr commit ../other -m "OTHER"
$ bzr merge ../other

To resolve that kind of conflict, you have to decide what name should be retained for the file, directory or symlink involved.

bzr resolve recognizes the following actions:

  • --action=take-this will issue bzr rm --force foo.new and bzr add foo,
  • --action=take-other will issue bzr rm --force foo and bzr mv foo.new foo,
  • --action=done will just mark the conflict as resolved.

Bazaar cannot auto-detect when conflicts of this kind have been resolved.

MalformedTransform

It is possible (though very rare) for Bazaar to raise a MalformedTransform exception. This means that Bazaar encountered a filesystem conflict that it was unable to resolve. This usually indicates a bug. Please let us know if you encounter this. Our bug tracker is at https://launchpad.net/bzr/+bugs