Building qt 5 from git

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Building Qt 5 from Git

Introduction

This article provides hints for checking out and building the modularized Qt 5 from Git, on desktop platforms. Please feel free to update this article as things change during development. Raise issues related to the article via: http://forum.qt.io/viewthread/7018

If you also want to compile Qt Creator, see Building Qt Creator from Git [qt.io].

System Requirements

All desktop platforms

• Git (>= 1.6.x)
• Perl (>=5.14)
• Python (>=2.6.x)
• A working compiler

For more detailed information, see Building Qt Sources [qt.io]

SSL (optional)

See Enabling and Disabling SSL Support [qt.io]

WebKit (optional)

• bison
• flex
• gperf
• Ruby [ruby-lang.org]
• ICU [site.icu-project.org]

For Windows, bison, flex and gperf are provided with the source code at <qt>\gnuwin32\bin. Get Ruby from http://rubyinstaller.org/. You can download the precompiled ICU packages from icu-project.org (MSVC 2010 only), or compile your own [qt.io]

Linux/X11

apt-get build-dep

Ubuntu/Debian based systems have a convenient way of installing build-depends for any package:

sudo apt-get build-dep qt5-default

RPM-based distros with yum offer a similar tool called yum-builddep.

Convenience packages (Ubuntu 11.10 — 12.10 only)

For Ubuntu/Debian, Gabor Loki has provided a custom PPA with the sedkit-env-webkit [launchpad.net] meta package that installs all required dependencies for building Qt/Qt WebKit. You can add the PPA by calling:

For other distros, get the separate components below.

Libxcb

Libxcb [xcb.freedesktop.org] is now the default window-system backend for platforms based on X11/Xorg, and you should therefore install libxcb and its accompanying packages. Qt5 should build with whatever libxcb version is available in your distro’s packages (but you may optionally wish to use v1.8 or higher to have threaded rendering support). src/plugins/platforms/xcb/README [qt.gitorious.org] lists the required packages.

ArchLinux:

On Chakra Linux, other than packages mentioned for ArchLinux, you need to install package xcb-util-keysyms separately. It’s available from CCR.

Centos 5/6

Install missing Qt build dependencies:

Install Red Hat DevTools 1.1 for CentOS-5/6 ×86_64, they are required due to outdated GCC shipped with default CentOS

You also need to initialise your newly installed dev tools:

For more info on preparing the environment on CentOS, see this thread [qt.io].

OpenGL support

For Qt Quick 2 a graphics driver with native OpenGL 2.0 support is highly recommended.

Accessibility

It is recommended to build with accessibility enabled, install libatspi 2 and libdbus-1 development packages.

Qt WebEngine

Fedora:

Please note that these libraries need to be installed on other distributions as well, though the package names and the set of libraries that are preinstalled may differ depending on the distribution used.

Qt Multimedia

You’ll need at least alsa-lib (>= 1.0.15) and gstreamer (>=0.10.24, but <1.0 for now [lists.qt.io]) with the base-plugins package.

OS X

Install the latest Xcode from the App Store. Verify that your Xcode install is properly set up for command line use:

This should give you eg:

You can verify that the right Xcode is being used by running:

If this points to /Developer you’re probably using an older Xcode version. Switch to the latest one by running:

Windows

Windows Graphics Drivers

QML2 requires OpenGL 2.1 or higher or Open GL ES 2.0 to work.

In Windows, two options are available:

1. Use the ANGLE-library [code.google.com] to translate OpenGL calls into DirectX (default)
2. Use the native OpenGL driver for your graphics card

A copy of ANGLE is bundled in Qt 5. To use Option 1, you need to install the DirectX SDK [msdn.microsoft.com] (Note: Starting from Windows Kit 8, this is included in the Windows SDK).

To use Option 2, you need to ensure that your graphics card driver supports OpenGL 2.1 or higher (Note: The stock Windows driver only supports OpenGL 1.1, which is insufficient), and pass `-opengl desktop’ to configure.exe.

Supported Compilers on Windows

• Visual Studio 2013
• Visual Studio 2012
• Visual Studio 2010 or Windows SDK v7.0A (upgradable to Windows SDK v7.1)
• Visual Studio 2008 or Windows SDK v6.0A (upgradable to Windows SDK v6.1)
• MinGW-w64 based compiler with g++ version 4.7 or higher (e.g. MinGW-builds [sourceforge.net], see also MinGW 64 bit).

Notes:

• Windows SDK v6.0A/v7.0A contains the same compiler as Visual Studio 2008/2010.
• Windows SDK 8.0 and later do not include a compiler.
• As of 16.3.2012, if you wish to install both Visual Studio 2010 and the standalone SDK, you need to follow this order (see readme.html provided with the service pack):
  1. Install Visual Studio 2010
  2. Install Windows SDK 7.1. See also Cannot_Install_Windows_SDK page.
  3. Install Visual Studio 2010 SP1
  4. Install Visual C++ 2010 SP1 Compiler Update for the Windows SDK 7.1

Windows Build environment

We recommend creating a command prompt that provides the build environment (see the Qt Creator README [qt.gitorious.org] ). In this environment, Python (e.g. Active Python 2.7 later) and Perl (e.g. Active State Perl 5.12 or later) should be in the PATH.
Get Perl from: http://www.activestate.com/activeperl/downloads [activestate.com]
Get Python from: http://www.python.org/download/releases/ [python.org]
Get Ruby from: http://www.rubyinstaller.org/downloads/ [rubyinstaller.org]

Hint: Make sure that Perl is added to the path in front of git since that ships an outdated version (Perl 5.8), which will cause the scripts to fail.

Multicore building: To speed up building when using nmake, the compiler can be instructed to use all available CPU cores in one of the following ways:

• Pass the option -MP to Qt’s configure
• Set the environment variable CL (specifying Visual Studio compiler options) to /MP (On the command line:

  set CL=/MP
  

  )
• Use the tool jom instead of nmake.

ICU on Windows

Qt 5 can make use of the ICU [site.icu-project.org] library for UNICODE and Globalization support. This is required for building Qt WebKit. You can use precompiled versions of ICU with a Visual Studio 2010 dependency from the website, or compile ICU on your own .

At compile time, the absolute paths of include and lib folders of the ICU installation must be appended to INCLUDE and LIB environment variables after calling the setup script of the Windows SDK.

At run-time, the ICU DLLs need to be found. This can be achieved by copying the DLLs to the application folder or adding the bin folder of the ICU installation to the PATH environment variable.

Getting the source code

First clone the top-level Qt 5 git repository:

or (if you’re behind a firewall and want to use the https protocol):

Then check out the target branch (see Branch Guidelines):

Following the README.git [qt.gitorious.org] – file we initialize the repository using the script init-repository which clones the various sub-modules of Qt 5. Relevant options:

• --no-webkit
  

   : Consider skipping qtwebkit by passing this option. This module is quite big, takes a long time to compile and is often a source of compile errors, so it is recommend to only download it if you intend to use it. You can always re-run init-repository later on to add it.

• --codereview-username <Jira/Gerrit username>
  

   : If you plan to contribute to Qt, you should specify your codereview username so that the git remotes are properly set up.

Configuring and building

The Qt5 build system should be fairly resilient against any “outside distractions” – it shouldn’t matter whether you have other Qt versions in PATH, and QTDIR is entirely ignored. However, make sure that you have no qmake-specific environment variables like QMAKEPATH or QMAKEFEATURES set, and the qmake -query output does not refer to any other Qt versions ($HOME/.config/Trolltech/QMake.conf should be empty).

Configure the build (from top level dir). Disabling tests and examples will greatly speed up compilation:

For Linux / OS X:

For Windows:

The

-developer-build

options export more symbols than in a traditional Qt build in order to allow more classes and functions to be unit tested. It also defaults to a ‘debug’ build, and installs the binaries in the current directory, avoiding the need for ‘make install’. ‘-opensource’ sets the license to be LGPL 2.1. The

-nomake examples

and

-nomake tests

parameters make sure examples and tests aren’t compiled by default. You can always decide to compile them later by hand.

• Hint1: On Linux, you should also pass

  -no-gtkstyle
  

  . This is because on a number of systems (at least SUSE and Gentoo)

  pkg-config —cflags gtk+-2.0
  

  actually returns paths that include the system Qt 4.x include directories.

• Hint2: You can add

  -confirm-license
  

  to get rid of the question whether you agree to the license.

• Hint3: On Windows, you might not be able to build if

  sh.exe
  

  is in your PATH (for example due to a git or msys installation). Such an error is indicated by

  qt5-srcqtbasebinqmake.exe: command not found
  

  and alike. In this case, make sure that

  sh.exe
  

  is not in your path. You will have to re-configure if your installation is already configured.

Now trigger the build by running:

For Linux / OS X:

If you are making an out-of-source developer build and that also includes building the QtWebKit module, the above command will return an error while building QtWebKit. This can be fixed by omitting the all and simply running:

For Windows (MSVC), choose one of the following, depending on your setup/environment:

Or only build a specific module, e.g. declarative, and modules it depends on:

Building Qt WebKit

Windows

WebKit.org [trac.webkit.org] has instructions for building WebKit on Windows. ICU [site.icu-project.org] is required for building.

The tools bison, flex and gperf which are required for building are provided for convenience in the folder gnuwin32\bin. If you are using shadow builds, you must add this directory to your

<span class="caps">PATH</span>

, else no special actions need to be done manually in order to use them.

Installing (Linux / OS X)

• Note: Installation is only needed if you haven’t used the configure options

  -developer-build
  

  or

  -prefix “<span class="caps">PWD</span>/qtbase”
  

  . Otherwise you can just use Qt from the build directory.

To install, run

Cleaning

To get a really clean tree use:

since make confclean no longer works from the top-level of the repo.

Getting updates

To update both the qt5.git repo as well as the submodules to the list of revisions that are known to work, run

In addition, you should pass the same parameters to init-repository as you did in “Getting the source code”.

Unlike a “normal” git submodule update, this ensures that any changes to the module structure are automatically pulled as well.

If you are planning to do nightly builds, consider using the script qt5_tool that lives in qtrepotools/bin. It provides options for updating the repository, cleaning and building. For example,

qt5_tool -u -c -b

can be used to clean, update and build.

qt5_tool -p -c – b

would be used to pull all modules to the head of their master branches.

Depending upon what changed in the source since it was last updated you might have to run configure again. To be really sure everything gets built, you can run clean first, then configure and make.

• Hint1: The submodule update does a checkout in submodules, potentially hiding any local commits you’ve done. If the latter happened to you (and you haven’t been working with branches anyhow),

  git reflog
  

  is your friend.
• Hint2: When creating scripts for updates on Windows, note that

  git clean
  

  often fails if some process locks a file or folder.

Using latest branches in the submodules

By default the checkout will not contain the latest stable/dev branches of each individual submodule repository, but a combination of versions that are known to work together. If you want to get the absolute latest stuff you can do so on a per-module basis, e.g.

or use qt5_tool to update all repositories:

However, there’s a good chance that compilation will fail due to incompatible versions of submodules. You might want to ask other persons actively working on a module how to resolve these incompatibilities.

Some advanced shell tricks can be useful when you are making or reviewing changes in multiple modules.

Issues

Linux

configure fails with “No QPA platform plugin enabled!” (Linux)

You should install the libxcb and it’s accompanying packages, see ‘System Requirements’.

configure fails with errors like “cannot stat file …”

Your perl version is too old, Qt 5 beta1 needs at least 5.14.

qmlscene segfaults “Cannot create platform GL context, none of GLX, EGL, DRI2 is enabled” (Linux)

Try installing the libx11-xcb-dev package:

afterwards you have to re-run configure and force qtbase/src/plugins/platforms/xcb to recompile.

WebKit doesn’t compile, missing ICU

Currently there is no configure time check for ICU, so install it through the package manager through

on Fedora:

• You can also compile Qt without Qt WebKit by deleting / renaming the qtwebkit, qtwebkit-examples-and-demos directories.
• The —no-webkit option of configure added, see QTBUG-20577 [bugreports.qt.io] issue.

Qt D-Bus fails to build due to “inconsistent user-defined literal suffixes”

This occours when you attempt to build Qt 5 with GCC 4.7 while D-Bus < 1.4.20 is present on your system. (For example, the default Fedora 17 installation is prone to this error.) The error message is this:

Note: The error is in the header files of D-Bus itself, and it has been fixed upstream, see https://bugs.freedesktop.org/show_bug.cgi?id=46147
Solution: either upgrade to a newer version of D-Bus or edit that one line of the header file manually.

[…]::isNull is not defined (from qvariant_p.h)

C++11 support is detected while your GCC doesn’t properly support it
Fixed by passing
to the configure options

cc1: fatal error: .pch/release-shared/QtGui: No such file or directory

Currently unresolved bug with the build of assembly files, see discussion at http://comments.gmane.org/gmane.comp.lib.qt.devel/5933
Fixed by passing
to the configure options

ld: hidden symbol `void QQmlThread::postMethodToThread<QQmlDataBlob*, QQmlDataBlob*, QQmlDataLoaderThread>(void (QQmlDataLoaderThread::)(QQmlDataBlob), QQmlDataBlob* const&)’ isn’t defined

Bug with GCC versions < 4.4.x, see bug report at https://bugzilla.redhat.com/show_bug.cgi?id=493929
Fixed by adding
in qtdeclarative/src/qml/qml.pro

Touchscreen (or Wacom tablet) doesn’t work

Qt depends on having libxi (including development headers), supporting XInput protocol 2.2 or higher, available at build time in order to have multi-touch support. Otherwise configure will fall back to XInput 2.0 which does not support touchscreens. To prove that is the problem, try this:

export QT_XCB_DEBUG_XINPUT_DEVICES=1

and try your Qt application again. At startup, Qt will enumerate the input devices available, like this

If it does not say Qt supports 2.2 or greater, it means the headers weren’t available when Qt was built, so the support for touch was not included. If you do have 2.2 or greater but it doesn’t say it’s a touchscreen at the end, there may be some other problem such that the touchscreen is not recognized, and you may want to write up a bug, after verifying that touch works in other X11 applications.

Windows

Debugging OpenGL issues (Windows)

Set the environment variable

QT_QPA_VERBOSE=gl:1

and run the application with DebugView [technet.microsoft.com] installed. The log will show the requested vs obtained OpenGL version. If the log tells you that it only has OpenGL 1.1, QML2 will not work. Note that qmlscene will not report errors about unsupported OpenGL versions.

Questions & Comments

Please raise questions & comments about this article in the forum: http://forum.qt.io/viewthread/7018

Categories:

• Developing_with_Qt
  • Qt 5
• HowTo