Using Version Control Systems

Version control systems supported by Qt Creator are:

Version Control System	Address	Notes
Git	http://git-scm.com/
Subversion	http://subversion.tigris.org/
Perforce	http://www.perforce.com	Server version 2006.1 and later
CVS	http://www.cvshome.org
Mercurial	http://mercurial.selenic.com/	Qt Creator 2.0 and later

Setting Up Version Control Systems

Qt Creator uses the version control system's command line clients to access your repositories. To allow access, make sure that the command line clients can be located using the PATH environment variable or specify the path to the command line client executables in Tools > Options... > Version Control.

After you set up the version control system, use the command line to check that everything works (for example, use the status command). If no issues arise, you should be ready to use the system also from Qt Creator.

Using msysGit on Windows

If you configure Git for use with git bash, only, and use SSH authorization, Git looks for the SSH keys in the directory where the HOME environment points to. The variable is always set by git bash.

However, the variable is typically not set in a Windows command prompt. When you run Git from a Windows command prompt, it looks for the SSH keys in its installation directory, and therefore, the authorization fails.

You can set the HOME environment variable from Qt Creator. Select Tools > Options... > Version Control > Git. Select the Environment Variables and the Set "HOME" environment variable check boxes. HOME is set to %HOMEDRIVE%%HOMEPATH% when the Git executable is run and authorization works as it would with git bash.

Setting Up Common Options

Select Tools > Options... > Version Control > Common to specify settings for submit messages:

• Submit message check script is a script or program that can be used to perform checks on the submit message before submitting. The submit message is passed in as the script's first parameter. If there is an error, the script should output a message on standard error and return a non-zero exit code.
• User/alias configuration file takes a file in mailmap format that lists user names and aliases. For example:

   Jon Doe <Jon.Doe@company.com>
   Hans Mustermann <Hans.Mustermann@company.com> hm <info@company.com>

  Note: The second line above specifies the alias hm and the corresponding email address for Hans Mustermann. If the user/alias configuration file is present, the submit editor displays a context menu with Insert name... that pops up a dialog letting the user select a name.

• User fields configuration file is a simple text file consisting of lines specifying submit message fields that take user names, for example:

   Reviewed-by:
   Signed-off-by:

The fields above appear below the submit message. They provide completion for the aliases/public user names specified in the User/alias configuration file as well as a button that opens the aforementioned user name dialog.

Creating VCS Repositories for New Projects

Qt Creator allows for creating VCS repositories for version control systems that support local repository creation, such as Git or Mercurial. When creating a new project by selecting File > New File or Project..., you can choose a version control system in the final wizard page.

Using Version Control Systems

The Tools menu contains a submenu for each supported version control system.

The Version Control output pane displays the commands that are executed, a timestamp, and the relevant output. Select Window > Output Panes > Version Control to open the pane.

Adding Files

When you create a new file or a new project, the wizard displays a page asking whether the files should be added to a version control system. This happens when the parent directory or the project is already under version control and the system supports the concept of adding files, for example, Perforce and Subversion. Alternatively, you can add files later by using the version control tool menus.

With Git, there is no concept of adding files. Instead, all modified files must be staged for a commit.

Viewing Diff Output

All version control systems provide menu options to diff the current file or project: to compare it with the latest version stored in the repository and to display the differences. In Qt Creator, a diff is displayed in a read-only editor. If the file is accessible, you can double-click on a selected diff chunk and Qt Creator opens an editor displaying the file, scrolled to the line in question.

Viewing Versioning History and Change Details

Display the versioning history of a file by selecting Log (for Git and Mercurial) or Filelog (for CVS, Perforce, and Subversion). Typically, the log output contains the date, the commit message, and a change or revision identifier. Click on the identifier to display a description of the change including the diff. Right-clicking on an identifier brings up a context menu that lets you show annotation views of previous versions (see Annotating Files).

Annotating Files

Annotation views are obtained by selecting Annotate or Blame. Selecting Annotate or Blame displays the lines of the file prepended by the change identifier they originate from. Clicking on the change identifier shows a detailed description of the change.

To show the annotation of a previous version, right-click on the version identifier at the beginning of a line and choose one of the revisions shown at the bottom of the context menu. This allows you to navigate through the history of the file and obtain previous versions of it. It also works for Git and Mercurial using SHA's.

The same context menu is available when right-clicking on a version identifier in the file log view of a single file.

Committing Changes

Once you have finished making changes, submit them to the version control system by choosing Commit or Submit. Qt Creator displays a commit page containing a text editor where you can enter your commit message and a checkable list of modified files to be included.

When you have finished filling out the commit page information, click on Commit to start committing.

The Diff Selected Files button brings up a diff view of the files selected in the file list. Since the commit page is just another editor, you can go back to it by closing the diff view. You can also check a diff view from the editor combo box showing the Opened files.

Reverting Changes

All supported version control system support reverting your project to known states. This functionality is generally called reverting.

The changes discarded depend on the version control system.

A version control system can replace the Revert menu option with other options.

Reverting Changes Using Git

The Git version control system has an index that is used to stage changes. The index is commited on the next commit. Git allows you to revert back to the state of the last commit as well as to the state staged in the index.

• Undo Unstaged Changes reverts all changes and resets the working directory to the state of the index.
• Undo Uncommitted Changes reverts all changes, discarding the index. This returns your working copy to the state it was in right after the last commit.

Using Additional Git Functions

Git is a fast decentralized version control system. Git is available for Windows, Linux and Mac.

The Git submenu contains the following additional items:

Patch > Apply from Editor/Apply from File...	Patches are rewriting instructions that can be applied to a set of files. You can either apply a patch file that is open in Qt Creator or select the patch file to apply from the file system.
Pull	Pull changes from the remote repository. If there are locally modified files, you are prompted to stash those changes. Select Tools > Options... > Version Control > Git and select the Pull with rebase check box to perform a rebase operation while pulling.
Clean.../Clean Project...	All files that are not under version control (with the exception of patches and project files) are displayed in the Clean Repository dialog. Select the files to delete and click Delete. This allows you to clean a build completely.
Branches...	Display the Branch dialog that shows the local branches at the top and remote branches at the bottom. To switch to a local branch, double-click it. Double-clicking on a remote branch first creates a local branch with the same name that tracks the remote branch, and then switches to it.
Stage File for Commit	Mark new or modified files for committing to the repository. To undo this function, select Unstage File from Commit.
Show Commit...	Select a commit to view. Enter the SHA of the commit in the Change field.

Using Stashes

With Git, you can put your current set of changes onto a virtual shelf called a stash. Stashes are useful, for example, to put aside a set of changes to work on higher priority tasks or to pull in new chages from another repository.

Qt Creator exposes this functionality in the Tools > Git > Stash menu.

Stashes...	Display a dialog that shows all known stashes with options to restore, display or delete them.
Stash	Stash all local changes. The working copy is then reset to the state it had right after the last commit.
Stash Snapshot...	Save a snapshot of your current work under a name for later reference. The working copy is unchanged. For example, if you want to try something and find out later that it does not work, you can discard it and return to the state of the snapshot.
Stash Pop	Remove a single stashed state from the stash list and apply it on top of the current working tree state.

Using Additional Mercurial Functionality

The Mercurial submenu contains the following additional items:

Import	Apply changes from a patch file.
Incoming	Monitor the status of a remote repository by listing the changes that will be pulled.
Outgoing	Monitor the status of a remote repository by listing the changes that will be pushed.
Pull	Pull changes from the remote repository.
Update	Look at an earlier version of the code.

Using Additional Perforce Functions

When you start Qt Creator, it looks for the executable specified in the P4 command field in Tools > Options... > Version Control > Perforce. If the file is not found, the following error message is displayed in the Version Control output pane: Perforce: Unable to determine the repository: "p4.exe" terminated with exit code 1. If you use Perforce, check that the path to the executable is specified correctly in the P4 command field.

If you do not use Perforce, you can disable the Perforce plugin to get rid of the error message. Choose Help > About Plugins and deselect the Load check box for the Perforce plugin in the Version Control group.

The Perforce submenu contains the following additional items:

Describe...	View information about changelists and the files in them.
Edit File	Open a file for editing.
Opened	List files that are open for editing.
Pending Changes...	Group files for commit.
Update All/Update Current Project	Fetch the current version of the current project or all projects from the repository.

Using Additional Subversion Functions

The Subversion submenu contains the following additional items:

Describe...	Display commit log messages for a revision.
Update Project/Update Repository	Update your working copy.