Understanding File Differences and Conflict Types

On software development teams where more than one person is working on the same project, it is common for file differences to create conflicts. Team Foundation version control lets you resolve these conflicts. Conflicts can occur during the following operations:

• Merging changes between branches

• Getting files into your workspace

• Checking in new versions of file.

Conflict Types

This topic contains information about the following conflict types:

Version Conflict

File name collision conflict

Local overwrite conflict

Version Conflict

Version conflicts can occur in Team Foundation version control with a check-in, get, or merge operation. In each case, the evolution of an item along divergent paths results in a conflict.

• Check-in   Two users check out the latest version of a file. The first user checks in changes; this creates a new version of the file. When the second user tries a check-in, there is a version conflict because the second user's changes were not made against the latest version of the file.

• Get   Two users check out the latest version of a file. The first user checks in changes; this creates a new version of the file. When the second user performs a get latest operation, there is a version conflict because the get latest operation is trying to update the checked-out file in the workspace.

• Merge   A branched file has been modified in both branches. A user tries to merge changes from one branch to the other. There is a version conflict because the file has been modified on both branches.

Resolving version conflicts involves either merging changes or selecting one set of changes over the other. For more information, see How to: Resolve Conflicts Between Two Files.

Version Conflicts

Local/Source Change	Server/Target Change	Resolve Options (Get or Checkin)	Resolve Options (Merge)
Edit Rename Undelete	Edit Rename Undelete	Merge changes for me (if there are no conflicts) Merge changes in merge tool Undo my local changes Discard server changes	Merge changes for me (if there are no conflicts) Merge changes in merge tool Keep changes in target branch Copy item from source branch This is the default selection.
	Delete	Restore file and merge changes for me (if there are no conflicts) Restore file and merge changes in merge tool Undo my local changes Restore file but keep my changes	Restore file and merge changes for me (if there are no conflicts) Restore file and merge changes in merge tool Discard changes from source branch Copy item from source branch
Delete	Edit Rename Undelete	Undo my local changes Discard server changes	Discard changes from source branch Delete item in target branch
	Delete	Undo my local changes	Discard changes from source branch
			Skip these conflicts (Indicates that conflicts of that type will not be acted upon.)

File Name Collision Conflict

File name collisions can occur in Team Foundation version control with a check-in, get, or merge operation. In all three cases, the conflict results when two or more items try to occupy the same path in the source control server.

• Check-in   Two users each add a file to the same application. Coincidentally, the two users choose the same name for the new files. One user checks in his or her file. When the second user tries a check-in, there is a file name collision.

• Get   Two users add files with identical names to an application. One user checks in the file. When the second user tries a get latest operation, there is a file name collision. This is because the first user's file cannot be retrieved where the second user has added a file.

• Merge   An application has been branched and has then been worked on in both branches. In both branches, a file that has the same name has been added. A user tries to merge changes from one branch to the other. There is a file name collision because the file added to the source branch can not be branched where a file has already been added to the target branch.

File name collision can result from any operation that adds or moves items in the server path namespace. This includes operations such as add, rename, branch, undelete, and merge.

To resolve file name collisions, you need to select which item will ultimately occupy the source control server path. For more information, see How to: Resolve Conflicts Between Two Files.

File Name Collision Conflicts

Local/Source Change	Server/Target Change	Resolve Options (Get or Checkin)	Resolve Options(Merge)
Add Branch Rename Undelete	Add Branch Rename Undelete	Undo my local changes Ignore conflict	Discard changes from source branch Ignore conflict
			Skip these conflicts (Indicates that conflicts of that type will not be acted upon.) This is the default selection.

Local overwrite conflict

Local overwrite conflicts only occur in Team Foundation version control during a get operation. These conflicts occur when a get operation tries to write over a writable file in your workspace. By default, the get operation will only replace files that are read-only. Resolving local overwrite conflicts involves either overwriting the file or checking out the file and merging changes.

Writable Files

Local/Source Change	Server/Target Change	Resolve Options (Get or Checkin)	Resolve Options(Merge)
Not applicable	Not applicable	Overwrite local file/folder Ignore conflict	Not applicable
			Skip These conflicts (Indicates that conflicts of that type will not be acted upon.) This is the default selection.

Note

You cannot use the Resolve Selected Conflicts dialog box to resolve version conflicts that require a merge tool for resolution. This dialog box does not contain the option to merge changes in a merge tool. Also, if you select Merge changes for me and you find conflicts in the internal content, you cannot invoke the merge tool. Instead, you will be presented with the Unresolved Conflicts dialog box, which explains that you must resolve some files individually. If only one file cannot be resolved, the dialog box includes the filename. If there is more than one unresolved file, the dialog box will include the number of files.

These are the compare options:

Conflict Type	Source Change	Compare Options (Get or Checkin)	Compare Options (Merge)
Version	Edit Rename Undelete	Local to Server Local to Original Server to Original	Source to Target Source to Base Target to Base
		Local to Deleted Local to Original Deleted to Original	Source to Deleted Source to Base Deleted to Base
	Delete	Original to Server	Deleted to Target
		Not applicable	Not applicable
Filename Collision	Add Branch Rename Undelete	Local to Server	Source to Target
Writable File	Not applicable	Not applicable	Not applicable

See Also

Tasks

How to: Resolve Conflicts Between Two Files

How to: Get the Source for Your Team Project

How to: Check In Pending Changes

Other Resources

Resolving Folder Differences and File Conflicts (Team Foundation Version Control)