Setting up Gerrit

All projects under the Qt Open Governance umbrella are hosted on our Gerrit Instance. There is an official mirror and browser of these repositories.

In order to be able to propose changes to those projects, you have to first setup your Gerrit account and get Qt's sourcecode, following the steps below:

Set up a Gerrit account
Tweak your SSH config as instructed here
Use the recommended Git settings, defined here
Get the source code of the projects you want to contribute to

Moreover, if you did not use the init-repository scripts to get the source code, you will have to manually:

Set up the git commit hooks .
Set up a Gerrit git remote.

Once all the steps above have been completed, you're ready to submit your patch to Qt!

How to get started - Gerrit registration

Before starting make sure you have a working Git installation and OpenSSH installed. ( or the bundled version of SSH that comes with recent Git packages).

Create a Qt account, if you don't have one yet.
- Note: Use an all-lowercase user name. Otherwise, Gerrit will lowercase it for you, and as it is case sensitive, you will have to use mismatched login names.
Log into https://codereview.qt-project.org with your Qt account.
Go to "Settings" -> "Profile", set your real name and register your email address, if it hasn't been automatically registered.
- You will receive a confirmation email; click on the link inside to finalize your registration.
  - If you use Outlook, manually copy the link including any trailing equal signs into the browser.
- Note: The email address you use to contribute to the Qt Project will be publicly visible in the Git history. Use an alias + a custom e-mail address if you want to stay anonymous (this is discouraged)
Review and agree to the Qt Project's contribution license agreement (CLA) in Gerrit. You need to do this only once, unless the license changes.
- If your company has a corporate contribution agreement, ask the admin of your company's Gerrit user group to add your account to this group.
- More details about the CLA can be found here.
Create a public SSH key for your PC, if you don't have one yet (see below under "Local Setup" for instructions)
Go to "Settings"-> "SSH Public Keys" and upload your public SSH Key.
If you are behind a firewall that blocks SSH access:
1. Go to "Settings" -> "HTTP Password"
2. Click "Generate Password"
3. Add the following line to your ~/.netrc (Windows: %USERPROFILE%\_netrc):
```
machine codereview.qt-project.org login <Gerrit username> password <Generated password>
```

Local Setup

Proper configuration of SSH for your Gerrit account is necessary for the URLs in the next steps.

Note: On Windows, when not using OpenSSH, the ~/ shorthand used below can be equated with C:\Users\%USERNAME%\. Make replacements in the example as necessary.

Edit ~/.ssh/config with host information for Gerrit, as shown below. Do not copy comments marked by #, as they may not be ignored by your SSH client.

Host codereview.qt-project.org
    Port 29418
    # To avoid no mutual signature algorithm errors
    PubkeyAcceptedKeyTypes +ssh-rsa
    # Use your Gerrit username, not email or your username on your own machine.
    # You can view this from Settings in gerrit when logged in.
    User yourgerritusername
    PreferredAuthentications publickey
    IdentityFile ~/.ssh/id_ed25519

Next, you will need to ensure that you have an SSH key pair, and make it known to Gerrit.

If you have no key pair on this machine yet, generate one now. On the command line, invoke the following command, replacing "john-doe-win10-home" with a comment that uniquely describes the machine you're on:
ssh-keygen -t ed25519 -C john-doe-win10-home -f ~/.ssh/id_ed25519
Note: SSH keys are intended to be unique to each machine. New keys must be created for each additional machine logging in to Gerrit with SSH.
Open the ~/.ssh/id_ed25519.pub file with a text editor and copy its entire contents into the clipboard.
Log into https://codereview.qt-project.org and navigate to Settings (the gear symbol on the top right) → SSH Keys
Paste the clipboard into the New SSH key entry, and hit the ADD NEW SSH KEY button.

You can verify that the connection works by running:
ssh codereview.qt-project.org

If the connection is functional, you should see a welcome message. End the connection by pressing Ctrl-C. If not, running ssh -v codereview.qt-project.org should give you an error message with details.

When making a connection to codereview.qt-project.org using ssh for the first time a prompt will show asking you to verify the authenticity (public key) of the host using it's fingerprint.

The authenticity of host '[codereview.qt-project.org]:29418 ([54.194.93.196]:29418)' can't be established.
ED25519 key fingerprint is SHA256:DwwqNluQyJVkOk+3bFMK6NwWYIGjMnqGP+R0k59e3CY.
This key is not known by any other names.
Are you sure you want to continue connecting (yes/no/[fingerprint])?

This prompt will only show the first time connecting to the host or when the host's public keys are changed. When prompted verify that the fingerprint for your key type is correct then accept the host's public key by typing yes, alternatively you could copy the fingerprint into the terminal for it to compare it to the provided fingerprint. Here is a list of current fingerprints for codereview.qt-project.org^[1]:

ssh_host_ecdsa_384_key
384 SHA256:yMnqjnsJU0y6kfiyQQu8pYNGPFE7av5QxbeLdjTKNmk (ECDSA)

ssh_host_ecdsa_521_key
521 SHA256:kytLsqmLdG1KXLO/s3OxOajTYqf1+n7+YqqbOUzNbtE (ECDSA)

ssh_host_ecdsa_key
256 SHA256:El3+EYlXAGylCVo/Y/WYzPg7tS4fjejkepO1JVXUkb0 (ECDSA)

ssh_host_ed25519_key
256 SHA256:DwwqNluQyJVkOk+3bFMK6NwWYIGjMnqGP+R0k59e3CY (ED25519)

ssh_host_rsa_key
4096 SHA256:EPuL0PAbNuXXoye7X93ARF7/XALxA5XNAaE3p6M/L3g (RSA)

If the fingerprint the host provides is not included in this list, you might face an attempt for a man-in-the-middle attack or the host keys might have changed, if that happens search for the project's latest keys.

Configuring Git

We are developing in a heterogeneous environment with both Unix and Windows machines. Therefore it is imperative to have all files in the repository in the canonical LF-only format. Therefore, Windows users must run

git config --global core.autocrlf true

to automatically get CRLF line endings which are suitable for the native tools, and Unix users should use

git config --global core.autocrlf input

(this is a safety measure for the case where files with CRLF line endings get into the file system- this can happen when archives are unpacked, attachments saved, etc.).

To be able to create commits which can be pushed to the server, you need to set up your committer information correctly:

git config --global user.name "Your Name"
git config --global user.email "me@example.com"

Please do not use nicknames or pseudonyms instead of the real name unless you have really good reasons. Gerrit will not accept your commits unless the committer information matches the email address(es) you registered.

To facilitate following the style guide for commit messages, it is recommended to install the Qt commit message template:

git config --global commit.template <path to qt5.git or qt.git>/.commit-template

Sometimes it is necessary to resolve the same conflicts multiple times. Git has the ability to record and replay conflict resolutions automatically, but - surprise surprise - it is not enabled by default. To fix it, run:

git config --global rerere.enabled true
git config --global rerere.autoupdate true # this saves you the git add, but you should verify the result with git diff --staged

git pull will show a nice diffstat, so you get an overview of the changes from upstream. git pull --rebase does not do that by default. But you want it:

git config --global rebase.stat true

To get nicely colored patches (from git diff, git log -p, git show, etc.), use this:

git config --global color.ui auto
git config --global core.pager "less -FRSX"

Git supports aliases which you can use to save yourself some typing. For example, these (any similarity with subversion command aliases is purely accidental ;)):

git config --global alias.di diff
git config --global alias.ci commit
git config --global alias.co checkout
git config --global alias.ann blame
git config --global alias.st status

Getting the source code

Cloning Qt5

You should clone from the official mirror and track changes from there in order to keep the load on Gerrit down.

This guide will show you how to get and build the source code.

After getting the source code, if you did not use the init-repository script to clone the source code as described in the guide, or you want to manually clone only a submodule, make sure you also manually set up the git commit hooks and set up a git remote that point to Qt's gerrit instance.

Cloning Qt Creator

git clone git://code.qt.io/qt-creator/qt-creator.git

Setting up git hooks

NOTE: This is only needed if you did NOT use the init-repository script to get the source code, that automatically configures the git hooks for you.

It's recommended to use the git hooks from the qtrepotools repo, which makes it simpler to fetch any updates to the git hooks by a git pull.

The git_post_commit_hook from the qtrepotools repository, gives you the checks of the Sanity Bot locally.

This section assumes you have a qtrepotools checkout. <qt module checkout dir> is the path to the Qt repo where you want to set up the git hooks.

On systems that support symlinks (Unix) the git hooks can be set up by creating symlinks to the scripts in <qtrepotools dir>/git-hooks/:

cd <qt module checkout dir>/.git/hooks
ln -s <path to qtrepotools dir>/git-hooks/gerrit_commit_msg_hook commit-msg 
ln -s <path to qtrepotools dir>/git-hooks/git_post_commit_hook post-commit

An alternative, that should work on all platforms:
- Create <qt module checkout dir>/.git/hooks/{commit-msg,post-commit} files and add this to them (respectively):

commit-msg:

#!/bin/sh
exec "<path to qtrepotools clone>/qtrepotools/git-hooks/gerrit_commit_msg_hook" "$@"

post-commit:

#!/bin/sh
exec "<path to qtrepotools clone>/qtrepotools/git-hooks/git_post_commit_hook" "$@"

# Make them executable:
chmod u+x "<qt module checkout dir>/.git/hooks/commit-msg"
chmod u+x "<qt module checkout dir>/.git/hooks/post-commit"

NOTE: Starting with git 1.7.8, if <qt module checkout dir>/.git is a text file that contains gitdir: ../.git/modules/<module name>, you need to put the git hooks for each sub-module in <path to git super repo>/.git/modules/<module name>/hooks instead of <qt module checkout dir>/.git/hooks.