Building Qt 6 from Git

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This article provides hints for checking out and building the Qt 6 repositories. This is primarily for developers who want to contribute to the Qt library or try the latest unreleased code.

If you want to build a specific release of Qt from sources to use the libraries in your project, you can download the source code from the Official Releases page or the Archive. Commercial customers can download the Source Packages via the Qt Account portal.

System Requirements

  • Git (>= 1.6.x)
  • CMake (>= 3.16, >= 3.18.4 for Ninja Multi-Config, >= 3.19 for WebEngine, >= 3.21.1 for static Qt builds in Qt 6.2+, or builds for Apple platforms in Qt 6.6+)
  • Ninja
  • C++ compiler supporting C++ 17
  • Perl (>=5.14, optional for Qt >= 6.5)
  • Python (>=2.6.x)
  • libclang: >=15, optional when QDoc should be built. Pre-built versions for each OS can be downloaded here. Alternatively, they can be installed through the clang-15, libclang-15-dev and llvm-15 packages on Linux.
  • Windows: Visual Studio 2022, Visual Studio 2019, MinGW 11.2
  • Linux: OpenGL developing library (libgl-dev, libegl-dev), libfontconfig1-dev (for fonts to be rendered correctly), libinput-dev (for the XCB platform plugin), and the XCB libraries mentioned in https://doc.qt.io/qt-6/linux-requirements.html

Note for MSVC: Visual Studio 2019/2022 comes with CMake and ninja preinstalled. StrawberryPerl is a Perl version that does not need registration and comes as both an installer and a zip archive.

System Requirements - Qt WebEngine and Qt PDF

Qt WebEngine and Qt PDF have additional build requirements

  • Python (>=3.6.x)
  • Python html5lib
  • Bison, Flex
  • GPerf
  • Node.js version 8 or later (version 12 or later is recommended)
  • Windows: Visual Studio 2019 v16.11+ (required for QtWebEngine to address an issue with defaulted noexcept operators)
  • Windows: Windows 10 SDK >= 10.0.19041.0 (version 2004) for QtWebEngine

Getting the source code

Note: If you plan to use Qt 6.7 or later, please follow the steps outlined in the Qt Documentation at Getting Qt Sources from the Git repository. For older versions, follow the steps in this section.

First, clone the top-level Qt git repository into a directory of your choice. On Linux-type operating systems, it is common to clone the Qt source code into ~/qt6. On Windows, we recommend cloning the Qt source code into a directory with a short path, for example, C:\dev\qt6 to avoid path length limitations on this platform.

In your terminal, navigate to the directory that will contain the qt6 top-level repository and use the git command line to make a clone: 

$ git clone git://code.qt.io/qt/qt5.git qt6

Alternatively, if you're behind a firewall and want to use the https protocol: 

$ git clone https://code.qt.io/qt/qt5.git qt6

Do not worry about the name mentioning qt5.git. This is also used for Qt 6.

Then check out the target branch (see Branch Guidelines). New feature development happens in the dev branch, which has the latest changes. You may also check out sources for any publicly released and tagged version, or any currently active branch. 

$ cd qt6
$ git switch dev

To build a specific release of Qt, you can switch to the desired tag: 

$ cd qt6
$ git switch 6.5.3

This will check out the 6.5.3 release. You can see all branch names in the repo overview.

For commercial-only modules and commercial-only branches of public modules, see Getting Commercial Qt Sources.

Getting the submodule source code

As described in the README.git, initialize the repository using the init-repository script, which clones the various sub-modules of Qt 6.

Relevant options for init-repository:

  • --module-subset : For example, to get modules for Qt Quick development: --module-subset=qtbase,qtshadertools,qtdeclarative. You can add or remove individual submodules later with git submodule init/deinit.
  • --codereview-username <Jira/Gerrit username> : If you plan to contribute to Qt, you may specify your codereview username (pay attention to capitalization!) so that the git remotes are properly set up. Note that it is recommended to adjust your ssh configuration instead.
$ cd qt6
$ perl init-repository

On Windows: 

> .\init-repository.bat

Configuring and Building

Qt 6 is built with CMake and can be configured by running CMake with appropriate options. Qt also has a configure script, making it easier to call CMake with the correct arguments. This configure script (configure.bat on Windows) is located in the directory you git-cloned the source code into (~/qt6 if you followed the directions above).

When configuring the Qt build, we recommend to keep the build directory separate from the source code. This is done by calling CMake or configure from a different, parallel-level directory.

On Linux:

$ mkdir qt6-build
$ cd qt6-build
$ ../qt6/configure -prefix /path/to/install
$ cmake --build . --parallel 4
$ cmake --install .

Where 4 is the number of jobs. You can try your own value or use auto value using --parallel without argument.

Where dot after "--build ." means current folder.

On Windows:

Open the correct command prompt (e.g. 'x64 Native Tools Command Prompt for VS 2022'), which properly sets up the needed environment variables. Also, make sure that Ninja can be found (by adding the path to ninja,exe to your PATH env var) 

> mkdir qt6-build
> cd qt6-build
> ..\qt6\configure.bat -prefix C:\path\to\install
> cmake --build .
> cmake --install .

Run configure -help to get an overview of available options.

You may also pass CMake options directly to configure: 

 > ../qt6/configure -- -DQT_BUILD_TESTS=ON

All options which are specified after a double-dash (--), will be passed verbatim to CMake.

See cmake/configure-cmake-mapping.md in the sources for an overview of available options and how they map to CMake options.

On macOS for iOS:

Here is an example of CMake configure arguments used to build Qt for iOS on macOS: 

-DCMAKE_BUILD_TYPE=Debug -DFEATURE_developer_build=ON -DQT_BUILD_TESTS=OFF -DQT_BUILD_EXAMPLES=ON -DQT_BUILD_EXAMPLES_BY_DEFAULT=OFF -DCMAKE_SYSTEM_NAME=iOS -DQT_HOST_PATH=~/dev/qt-dev-debug-non-fw/qtbase

Note that configuring tests as part of the build when targeting iOS is somewhat pointless, because you won't be able to run them. To run an iOS app (or test), they need to be built with the xcode generator, and building the tests in-tree means they will be built with ninja. So you need to configure each test manually in a separate build directory.

Developer Builds

The configure option -developer-build sets the install prefix to the build directory, so that no install step is necessary. It also changes defaults so that all tests (including tests using private API that is otherwise not exported) can run.

This can take quite some time though. If you do want to be able to build the tests, but only on request, configure with CMake variable QT_BUILD_TESTS_BY_DEFAULT=OFF: 

 $ ../qt6/configure -developer-build -- -DQT_BUILD_TESTS_BY_DEFAULT=OFF
 $ cmake --build . --parallel

Later on you can then build single tests, for instance : 

 $ cmake --build . --target tst_qstyle

Use ninja -t targets to see all the targets that are provided in the build.

See cmake/README.md in the sources for details on how to configure and build Qt 6 with CMake.

Running Tests

Once you've built (as long as you you did build with tests enabled), you can run the tests either directly using ninja tst_qlocale_check (for example, to run tests/auto/corelib/text/qlocale/tst_qlocale) or via ctest (see its man page for further options) like 

 $ ctest -V -R qlocale

(for the same example); the parameter to -R is a regular expression, matching test names. This includes the test output; if you omit -V that's skipped and you just get a single-line summary of the test result.

If you want to run only a particular test function, you pass it using the TESTARGS environment variable. For example: 

$ TESTARGS=emptyCtor  ctest -V -R qlocale

And if you want to run a specific test function with a specific data-tag, you provide it after a colon: 

$ TESTARGS=emptyCtor:en_GB  ctest -V -R qlocale
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