Get Involved/development/More: Difference between revisions

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This page is the continuation with more advanced topics of the page [[Get_Involved/development]].
This page is the continuation with more advanced topics of the page [[Get_Involved/development]].


This paged is not meant for people that are starting to program for KDE.
== kde-builder is an alternative to kdesrc-build ==
 
kdesrc-build and kde-builder are two KDE build frameworks. They are used at the command line and have identical command line syntax, just replace the string "kdesrc-build" with "kde-builder". They use the same configuration file, named <code>kdesrc-buildrc</code>.
 
kde-builder is newer and regularly gets new features and is written in Python.
 
kdesrc-build is in maintenance mode and feature frozen and written in Perl.
 
The "how to install kde-builder" procedure is here https://invent.kde.org/sdk/kde-builder/-/blob/master/README.md .


== Develop in a Linux container ==
== Develop in a Linux container ==


When you start programming for KDE, it is recommended that you [[Get_Involved/development|use kdesrc-build in your main operating system or in a virtual machine]] running on a rolling-release Linux distribution (Arch, openSUSE Tumbleweed, KDE neon) or running on e.g. the latest version of Fedora KDE Spin or Kubuntu.
When you start programming for KDE, it is recommended that you [[Get_Involved/development|use kdesrc-build in your main operating system or in a virtual machine]] running on a [[Get_Involved/development#Operating_system|Linux operating system that is better supported by kdesrc-build]].


As an alternative, you can run kdesrc-build in a Linux container (docker, podman, toolbx, distrobox).
As an alternative, you can run kdesrc-build in a Linux container (docker, podman, toolbx, distrobox).
Line 15: Line 23:
=== Option 2. distrobox ===
=== Option 2. distrobox ===


Or, you can just create a long lived (pet not cattle) container using distrobox and podman (or docker). See https://www.youtube.com/watch?v=9JEALbcmcCg and https://github.com/89luca89/distrobox to learn more about distrobox and how to use it in general.
It is possible to start developing KDE software using container images that are able to see inside your home folder. This can be done using distrobox and podman.


First, install distrobox and podman from your distribution repositories. Then run:
This solution is particularly useful for users on immutable distributions like Fedora Kinoite, openSUSE Kalpa or the Steam Deck's SteamOS.


{{Input|
To learn how to build KDE software with distrobox, see: https://develop.kde.org/docs/getting-started/building/containers-distrobox/
distrobox enter
}}


This should create a container based on your current system and enter it. It is preferable to use one of the Linux distributions that is better suited for kdesrc-build, as mentioned [https://community.kde.org/Get_Involved/development#Linux in this wiki page], so if your distribution does not provide very up-to-date packages, you can download and use a different container image for your distrobox from [https://hub.docker.com/search?type=image Dockerhub]. For example, with openSUSE Tumbleweed:
== Other operating systems ==


{{Input|
=== Kubuntu >= 23.10 ===
podman pull opensuse/tumbleweed
distrobox create --image opensuse/tumbleweed --name tumbleweed
distrobox enter tumbleweed
}}


Then it's a matter of downloading and running kdesrc-build as detailed in [https://community.kde.org/Get_Involved/development#Set_up_kdesrc-build Set up kdesrc-build]:
The default configuration of kdesrc-build requires Qt version 6.6. Kubuntu 23.10 and 24.04 have Qt version 6.4.2. It is recommended that you use a [[Get_Involved/development#Operating_system|Linux OS that is better supported by kdesrc-build]].


{{Input|<nowiki>
If you are a more seasoned developer you might be able to use Kubuntu for kdesrc-build by [[Get_Involved/development/More#Qt_6_installed_using_the_Qt_online_installer|installing Qt6 using the Qt online installer]] or by [[Get_Involved/development/More#Build_Qt_using_kdesrc-build|building Qt6 using kdesrc-build]].
mkdir -p ~/kde/src
cd ~/kde/src
git clone https://invent.kde.org/sdk/kdesrc-build.git
./kdesrc-build --initial-setup
source ~/.bashrc
</nowiki>}}


From this point on, one important thing to bear in mind is that a distrobox container is transparent in its user space and containerized in its root space: when you are inside a distrobox container, you can see the content of system's home folder, but not your system's root folders, only the container's root folders. This means that you can install packages inside the container using root privileges and access those packages to compile your programs stored in your home, without ever installing those packages in your actual system!
=== Alpine Linux ===


You can take advantage of this by installing, for instance, Qt development packages used for kdesrc-build from inside the container. This way, it is not necessary to compile Qt with kdesrc-build. This is particularly convenient if you want to compile KDE software with Qt6 quickly.
<pre>
apk add git perl doas-sudo-shim
</pre>


Likewise, you should [https://community.kde.org/Get_Involved/development/Install_the_dependencies install the required dependencies] from inside the distrobox rather than from your system's repositories. Then you can start compiling as usual.
=== FreeBSD ===


After compiling your program with kdesrc-build from inside the distrobox, you can run it with <code>kdesrc-build run</code>, and despite it originating from inside a container and using the libraries from the container, it will run just fine as a GUI application on your system!
Install the latest release of FreeBSD with KDE Plasma Desktop on your hardware computer or in a virtual machine.


The only few gotchas to using this method are:
Your user should be member of the "wheel" user group (e.g. this can be configured in the FreeBSD installer, when creating your user you can select additional user groups for your user). Your user should be able to use sudo:


* You cannot use a [https://community.kde.org/Get_Involved/development#Plasma_Desktop full Plasma Desktop session] made from git.
<pre>
* You will need qqc2-desktop-style and Breeze to show the correct theme for your applications.
pkg install sudo
* You will need the QtWayland library and its respective development package to run your applications natively on a Wayland session.
visudo
# Uncomment the line: %wheel ALL=(ALL:ALL) ALL
</pre>


== Other operating systems ==
Then set up kdesrc-build using the same procedure as when installing kdesrc-build on a Linux operating system. FreeBSD is currently supported by kdesrc-build. See https://www.youtube.com/watch?v=8MqBnb3Y9JU


=== FreeBSD ===
=== OpenBSD >= 7.5 ===


Install the latest release of FreeBSD with KDE Plasma Desktop on your hardware computer or in a virtual machine. Then set up kdesrc-build using the same procedure as when installing kdesrc-build on a Linux operating system. FreeBSD is currently supported by kdesrc-build. See https://www.youtube.com/watch?v=v2wq0eTnUuc https://www.youtube.com/watch?v=MT-AN4J-hn8
Install OpenBSD version greater than or equal to 7.5. In the installer keep the defaults, the user created by the installer is named "administrator" in this example.
<pre>
# Enable doas
su -
cp /etc/examples/doas.conf /etc/doas.conf
exit
# kdesrc-build needs sudo.
mkdir -p ~/.local/bin ; ln -s /usr/bin/doas ~/.local/bin/sudo
echo "export PATH=~/.local/bin:\$PATH" >> ~/.bashrc


=== Microsoft Windows ===
# Test doas.
doas su
# kde-builder needs bash.
pkg_add bash
chsh -s /usr/local/bin/bash
exit


You can build and develop KDE projects using the [[Get_Involved/development/Windows|Microsoft Windows]] operating system.
# As user administrator
chsh -s /usr/local/bin/bash


=== Apple macOS ===
# As per https://rsadowski.de/posts/2024-01-09-openbsd-kde/ , https://openports.pl/path/meta/kde,-plasma
doas su
pkg_add kde-plasma kate


You can build and develop KDE projects using the [[Get_Involved/development/Mac|Apple macOS]] operating system.
# I recommend that you use tigervnc. https://nmariusp.github.io/install-os.html#openbsd--75
</pre>


== What to do if CMake configure fails because a build dependency is missing ==
After you install kdesrc-build:
<pre>
# Edit the kdesrc-buildrc file e.g.:
cmake-options -DCMAKE_BUILD_TYPE=RelWithDebInfo -DKF_IGNORE_PLATFORM_CHECK=ON


If you run kdesrc-build in order to build a KDE git repository. And if building fails with a CMake error. Then, that is most often caused by the fact that you do not have installed some binary packages from your Linux OS.
# Also set environment variable:
export CMAKE_PREFIX_PATH=/usr/local/lib/qt6/cmake
# Or
export CMAKE_PREFIX_PATH=/usr/local/lib/qt5/cmake
</pre>


See below for some ideas about how to find out what Linux packages you need to install.
=== Microsoft Windows ===


=== Debian/Kubuntu/KDE neon ===
You can build and develop KDE projects using the [[Get_Involved/development/Windows|Microsoft Windows]] operating system.


E.g. I am on Kubuntu 22.10, <code>kdesrc-build frameworks</code> fails, module <code>kcoreaddons</code> has CMake (configure) error <code>Could NOT find Qt6LinguistTools (missing: Qt6LinguistTools_DIR)</code>.
=== Apple macOS ===


Option 1:
You can build and develop KDE projects using the [[Get_Involved/development/Mac|Apple macOS]] operating system.


Search on the internet for <code>ubuntu packages Qt6LinguistTools</code> it returns https://packages.ubuntu.com/kinetic/amd64/qt6-tools-dev Expand "amd64 [list of files]": <code>/usr/lib/x86_64-linux-gnu/cmake/Qt6LinguistTools/Qt6LinguistToolsConfig.cmake</code>
== What to do if CMake configure fails because a build dependency is missing ==


{{Input|1=<nowiki>
See https://community.kde.org/Get_Involved/development/Install_the_dependencies .
sudo apt install qt6-tools-dev
</nowiki>}}


Option 2:
== Project Documentation ==
{{Input|1=<nowiki>
sudo apt install apt-file
sudo apt-file update
apt-file find Qt6LinguistToolsConfig.cmake
# qt6-tools-dev: /usr/lib/x86_64-linux-gnu/cmake/Qt6LinguistTools/Qt6LinguistToolsConfig.cmake
sudo apt install qt6-tools-dev
</nowiki>}}


If the error is:
* [https://docs.kde.org/trunk5/en/kdesrc-build/kdesrc-build/ Handbook]
{{Input|1=<nowiki>
* [https://invent.kde.org/sdk/kdesrc-build/-/blob/master/README.md Readme #1]
The imported target "Qt6::qtwaylandscanner" references the file
* [https://invent.kde.org/sdk/kdesrc-build/-/blob/master/doc/README.md Readme #2]
    "/usr/lib/qt6/libexec/qtwaylandscanner"
but this file does not exist.
</nowiki>}}


Then:
Developer's documentation can be found in the {{ic|doc/source-reference}} in the project repo.
{{Input|1=<nowiki>
apt-file find /usr/lib/qt6/libexec/qtwaylandscanner
# qt6-wayland-dev-tools: /usr/lib/qt6/libexec/qtwaylandscanner
sudo apt install qt6-wayland-dev-tools
</nowiki>}}


Option 3:
== kf6-qt6 vs. kf5-qt5 ==
{{Input|1=<nowiki>
apt search linguist | grep qt6
# linguist-qt6/kinetic 6.3.1-2 amd64
sudo apt install linguist-qt6
</nowiki>}}


More examples:
Many KDE git repositories can build correctly and run correctly using "kdesrc-build kf6-qt6".  
{{Input|1=<nowiki>
# Error "Could not find OsmTools (missing: OSMCONVERT_EXECUTABLE
apt-file search -i OSMCONVERT
# Returns "osmctools: /usr/bin/osmconvert".
sudo apt install osmctools
</nowiki>}}


=== Fedora ===
The KDE git repositories that can build correctly and run correctly using "kdesrc-build kf6-qt6" have two long lived git branches:


<code>sudo dnf provides "NameOrPathOfFileThatIsMissing"</code>
* A long lived git branch that does not contain the deprecated symbols from kf5-qt5, named e.g. "master".
* And another long lived git branch for qt5-kf5, where the deprecated symbols still exist.


See https://invent.kde.org/redstrate/cmake-package-installer/-/blob/master/src/main.rs
What is "kf6-qt6"? You just set up kdesrc-build following the procedure. The resulting kdesrc-build installation will be of type kf6-qt6. In kdesrc-buildrc in the "global" section you will have "branch-group kf6-qt6". The git repositories that have only one long lived git branch e.g. named "master" will use that. The git repositories that have a second long lived git branch, will use the git branch where the deprecated symbols do not exist e.g. named "master".


== Advanced kdesrc-build ==
What is "kf5-qt5"? Follow the chapter "kdesrc-build Qt5". The resulting kdesrc-build installation will be of type kf5-qt5. In kdesrc-buildrc in the "global" section you will have "branch-group kf5-qt5". The git repositories that have only one long lived git branch e.g. named "master" will use that. The git repositories that have a second long lived git branch where the deprecated symbols still exist e.g. named "kf5" will use that.


After you have edited a git repository and you want to build it, <code>--no-src</code> will make sure that <code>kdesrc-build</code> does not overwrite your changes with the latest source code from the official git repository (remote "origin" / https://invent/kde.org).
== Build Qt using kdesrc-build ==


<code>--no-include-dependencies</code> only builds the git repository that you give as parameter to <code>kdesrc-build</code>.
=== Qt6 ===
If you cannot build the KDE frameworks using {{ic|kdesrc-build}} and the Qt provided by your Linux distribution is outdated, you might want to build the Qt framework using {{ic|kdesrc-build}}.


<code>--debug</code> shows verbose output.
In your configuration file use the {{ic|qt-install-dir}} option (in the ''global'' section) with non-empty value, for example:


<code>--refresh-build</code> forces a rebuild (not an incremental build) and a full reinstall.
{{bc|
global
  qt-install-dir ~/kde/usr
  branch-group kf6-qt6
end global
}}


E.g. you have edited kcalc. You run:
It is recommended that if you build Qt6 using kdesrc-build, you also build qtwebengine. Edit the file {{ic|~/.local/state/sysadmin-repo-metadata/module-definitions/qt6.ksb}}. Follow the instructions found in the file: if you want qtwebengine, add it to use-modules after "qtwebchannel" and comment out the line "ignore-modules qtwebengine".
<pre>
kdesrc-build kcalc --no-src --no-include-dependencies --refresh-build --debug |& tee ~/a.txt
</pre>


For details, see:
<pre>
<pre>
kdesrc-build --help
kdesrc-build qtbase --refresh-build --debug
</pre>
</pre>
Press Ctrl+C after the CMake configure summary for qtbase. Make sure that you have the needed dependencies. Should find libb2-dev, libproxy-dev, libmd4c-dev, libmd4c-html0-dev, libxcb-xinput-dev, libatspi2.0-dev, libsqlite3-dev, unixodbc-dev, libmysqlclient-dev, postgresql-client, libecpg-dev, libpq-dev. Optional dependencies libsctp-dev, libts-dev.


Note: the resources below might not be up to date.
See the [https://docs.kde.org/trunk5/en/kdesrc-build/kdesrc-build/ kdesrc-build manual], [https://invent.kde.org/sdk/kdesrc-build/-/blob/master/README.md Readme #1], [https://invent.kde.org/sdk/kdesrc-build/-/blob/master/doc/README.md Readme #2], [https://invent.kde.org/sdk/kdesrc-build/-/blob/master/doc/source-reference/index.adoc Document #3] for more kdesrc-build information and options.
== Build Qt using kdesrc-build ==
Set up kdesrc-build from scratch as usual.
Open the configuration file <code>~/.config/kdesrc-buildrc</code> and confirm that <code>qtdir</code> and the lines <code>include...qt5-build-include</code> and <code>include...custom-qt5-libs-build-include</code> are not commented out (i.e. there should not be a <code>#</code> in front of the lines). E.g. (replace "username" with your Linux user's name):
{{Input|1=<nowiki>
qtdir ~/kde/usr # Where to make install Qt5
include /home/username/kde/src/kdesrc-build/qt5-build-include
include /home/username/kde/src/kdesrc-build/custom-qt5-libs-build-include
</nowiki>}}
Run in a terminal:
{{Input|1=<nowiki>
kdesrc-build Qt5
kdesrc-build frameworks
</nowiki>}}
== kf5-qt5 vs. kf5-qt6 vs. kf6-qt6 ==
For now, the KDE git repositories from https://invent.kde.org/frameworks and https://invent.kde.org/plasma/ can build correctly and run correctly using "kdesrc-build kf6-qt6".
The KDE git repositories that can build correctly and run correctly using "kdesrc-build kf6-qt6" have two long lived git branches:
* A long lived git branch that does not contain the deprecated symbols from kf5-qt5, named e.g. "master".
* And another long lived git branch for qt5-kf5 and qt6-kf5, where the deprecated symbols still exist.
What is "kf5-qt5"? You just set up kdesrc-build following the procedure. The resulting kdesrc-build installation will be of type kf5-qt5. In kdesrc-buildrc in the "global" section you will have "branch-group kf5-qt5". The git repositories that have only one long lived git branch e.g. named "master" will use that. The git repositories that have a second long lived git branch where the deprecated symbols still exist e.g. named "kf5" will use that.
What is "kf5-qt6"? You just set up kdesrc-build following the procedure. The resulting kdesrc-build installation will be of type kf5-qt5. In kdesrc-buildrc in the "global" section you will have "branch-group kf5-qt5", you keep this unchanged. You edit kdesrc-buildrc to make kdesrc-build use Qt6 instead of Qt5. The git repositories that have only one long lived git branch e.g. named "master" will use that. The git repositories that have a second long lived git branch where the deprecated symbols still exist e.g. named "kf5" will use that.
What is "kf6-qt6"? You just set up kdesrc-build following the procedure. The resulting kdesrc-build installation will be of type kf5-qt5. In kdesrc-buildrc in the "global" section you will have "branch-group kf5-qt5", you replace that with "branch-group kf6-qt6". You edit kdesrc-buildrc to make kdesrc-build use Qt6 instead of Qt5. The git repositories that have only one long lived git branch e.g. named "master" will use that. The git repositories that have a second long lived git branch, will use the git branch where the deprecated symbols do not exist e.g. named "master".
=== Why kdesrc-build kf6-qt6 cannot build and run neochat correctly? ===
neochat does not have a second long lived git branch where the deprecated symbols do not exist.
<code>kdesrc-build neochat</code> for kf6-qt6 succeeds, but then <code>kdesrc-run neochat</code> for kf6-qt6 fails because
<pre>
<pre>
qrc:/RoomListContextMenu.qml:200:27: Invalid property assignment: unsupported type "QQuickIcon"
kdesrc-build qtwebengine
Segmentation fault (core dumped)
</pre>
</pre>
This will build the Qt6 modules from qtbase up to qtwebengine. qtwebengine will probably be built incorrectly because some needed dependencies are missing.


<pre>
<pre>
# The file ~/kde/src/neochat/src/qml/Menu/RoomListContextMenu.qml at line 200 says:
kdesrc-build qtwebengine --refresh-build --debug
Kirigami.BasicListItem {
    text: i18n("Mark as Read")
    icon: "checkmark"
</pre>
</pre>
Press Ctrl+C after the CMake configure summary for qtwebengine. Make sure that you have the needed dependencies. Should find node.js >= 14, libdbus-1-dev, libxcomposite-dev, libxshmfence-dev, libxdamage-dev, libharfbuzz-dev, libvpx-dev, libpci-dev, libevent-dev, libre2-dev, libsnappy-dev, libcups2-dev, libxkbfile-dev.


The symbol <code>Kirigami.BasicListItem.icon</code> of type string is deprecated and exists in kf5-qt5. In kf6-qt6 we use the symbol of type string <code>Kirigami.BasicListItem.icon.name</code>.
Then build Qt6: {{bc|kdesrc-build qt6-set}}


== kdesrc-build, Qt6 and KDE Frameworks 6 ==
To compile Qt6 with Qt X11 Extras (which is a necessary library to compile [https://api.kde.org/frameworks/kwindowsystem/html/ KWindowSystem]), you should enable XCB feature during compilation


=== Using kdesrc-buildrc-kf6-sample ===
{{bc|1=kdesrc-build qt6-set --cmake-options="-DQT_FEATURE_xcb=ON"}}
KDE projects are currently transitioning to use Qt6. You can build the in-development Qt6 versions using kdesrc-build by adjusting the .config/kdesrc-buildrc file. You can find a sample kdesrc-buildrc file [https://invent.kde.org/sdk/kdesrc-build/-/blob/master/kdesrc-buildrc-kf6-sample here].


The important differences to Qt5 are:
=== Qt5 ===
If you want the same for Qt5, change {{ic|branch-group}} option and use {{ic|qt5-set}} instead of {{ic|qt6-set}}.


<code>branch-group kf6-qt6</code>: This will check out the correct git branches.
== Qt 6 installed using the Qt online installer ==


<code>prefix ~/kde6/usr</code>: It is recommended to use a different prefix for Qt6-based builds than for the Qt5-based builds
A screen recording version is available https://www.youtube.com/watch?v=3BIbYN2vIZw


Save the file e.g. as <code>/home/user/kde6/kdesrc-buildrc</code>.
The homepage of the Qt Framework is https://www.qt.io . Go to this web page, create an online account. https://www.qt.io/download-open-source > "Download the Qt Online Installer" > Linux > "Qt Online Installer for Linux (64-bit)" > download a file named e.g. qt-unified-linux-x64-4.6.1-online.run into the directory e.g. "~/Downloads".


Then you can use <code>kdesrc-build --rc-file=/home/user/kde6/kdesrc-buildrc ...</code> to build things against Qt6
<pre>
ls -la ~/Downloads # The downloaded file needs to have the "executable" chmod bit set.
chmod u+x ~/Downloads/qt-unified-linux-x64-4.6.1-online.run
~/Downloads/qt-unified-linux-x64-4.6.1-online.run
</pre>


=== Editing ~/.config/kdesrc-buildrc ===
A graphical user interface (GUI) installer wizard starts. Login using your Qt online account. Next > check the checkbox "I have read and agree to the terms and conditions of using OpenSource Qt", check the checkbox "I'm an individual and do not use Qt for any company" > Next > Next > enable "Help us improve" > Next > Custom installation, notice that the install directory is "~/Qt" > Next. Install the latest version of Qt6 and the latest version of the Qt Creator integrated development environment (IDE). There are some Qt6 components that are not used by KDE and can be left out when installing Qt6 e.g. Qt Design Studio, WebAssembly, Android, Sources, Qt Quick 3D, Qt 3D, Qt Quick 3D Physics, "Qt Debug Information Files". Next > enable "I have read and agree" > Next > Install.


Set up kdesrc-build following the "Set up kdesrc-build" procedure. The resulting kdesrc-build installation will be of type kf5-qt5. In kdesrc-buildrc in the "global" section you will have "branch-group kf5-qt5".
In the KDE Plasma app launcher (start menu) you now have the application "Qt Maintenance Tool".


Edit the file <code>~/.config/kdesrc-buildrc</code>
Set up kdesrc-build from scratch as usual.
* Replace all "5" with "6".
* Replace:
<pre>cmake-options -DCMAKE_BUILD_TYPE=RelWithDebInfo</pre>
with:
<pre>cmake-options -DCMAKE_BUILD_TYPE=Debug -DQT_MAJOR_VERSION=6 -DBUILD_WITH_QT6=ON</pre>


=== Installing the Qt6 Development Packages ===
Edit the file kdesrc-buildrc to look like:
* Ubuntu: <code>sudo apt install qt6-tools-dev qt6-declarative-dev libqt6core5compat6-dev qt6-wayland-dev qt6-wayland-dev-tools qt6-base-private-dev libqt6svg6-dev libqt6opengl6-dev libqt6shadertools6-dev</code>
* openSUSE Tumbleweed: <code>sudo zypper in patterns-kde-devel_qt6 qt6-wayland-private-devel</code>
* Arch Linux: <code>sudo pacman -S poppler-qt6 qca-qt6 qt6-5compat qt6-base qt6-charts qt6-declarative qt6-multimedia qt6-multimedia-ffmpeg qt6-positioning qt6-tools qt6-translations qt6-wayland qt6-webchannel qt6-webengine qt6-websockets qt6-webview qtkeychain-qt6 qcoro-qt6 qt6-svg qt6-shadertools</code>
* Fedora: <code>sudo dnf install qt6-*</code>


== Build Qt6 using kdesrc-build ==
<pre>
 
global
A screen recording version is available https://www.youtube.com/watch?v=TDzX0376QyA
...
 
    qt-install-dir  ~/Qt/6.7.0/gcc_64 # Where to install Qt6 if kdesrc-build supplies it
Note: If you cannot build the KDE frameworks using kdesrc-build and using the Qt6 provided by your OS (Linux distribution). Because the Qt6 is not complete. You might want to build Qt6 using kdesrc-build.
    libname lib
 
...
Note: Building Qt6 using kdesrc-build is an advanced topic.
end global
</pre>


Set up kdesrc-build clean from scratch following the same procedure as when using "Qt5 and KDE Frameworks 5".
== Two independent kdesrc-build configurations: kf6-qt6 and kf5-qt5 ==


{{Input|1=<nowiki>
You can switch between configurations with {{ic|--rc-file}} command line option. Generate another config, make the changes for the {{ic|source-dir}}, {{ic|build-dir}}, {{ic|install-dir}},
Edit two files:
and other changes you want. Make sure you use different value for {{ic|persistent-data-file}} option, to not mix things up.


cat ~/.config/kdesrc-buildrc
As an alternative, you can utilize custom variable to make switch from a single config:
# This file controls options to apply when configuring/building modules, and
# controls which modules are built in the first place.
# List of all options: https://docs.kde.org/trunk5/en/kdesrc-build/kdesrc-build/conf-options-table.html


{{bc-hl|shell|
global
global
     branch-group kf6-qt6
     _ver 5  # <-- Change this to switch
 
     source-dir ~/kde${_ver}/src
    # Finds and includes *KDE*-based dependencies into the build.  This makes
     build-dir ~/kde${_ver}/build
    # it easier to ensure that you have all the modules needed, but the
     install-dir ~/kde${_ver}/usr
    # dependencies are not very fine-grained so this can result in quite a few
     persistent-data-file ~/kde${_ver}/persistent-options.json
    # modules being installed that you didn't need.
    include-dependencies true
 
    # Install directory for KDE software
    kdedir ~/kde/usr
 
    # Directory for downloaded source code
     source-dir ~/kde/src
 
    # Directory to build KDE into before installing
    # relative to source-dir by default
     build-dir ~/kde/build
 
     qtdir  ~/kde/usr # Where to install Qt5 if kdesrc-build supplies it
 
    cmake-options -DCMAKE_BUILD_TYPE=Debug -DQT_MAJOR_VERSION=6 -DBUILD_WITH_QT6=ON
 
    # kdesrc-build sets 2 options which is used in options like make-options or set-env
    # to help manage the number of compile jobs that happen during a build:
    #
    # 1. num-cores, which is just the number of detected CPU cores, and can be passed
    #    to tools like make (needed for parallel build) or ninja (completely optional).
    #
    # 2. num-cores-low-mem, which is set to largest value that appears safe for
    #    particularly heavyweight modules based on total memory, intended for
     #    modules like qtwebengine
    num-cores 16
    num-cores-low-mem 12
 
    # kdesrc-build can install a sample .xsession file for "Custom"
    # (or "XSession") logins,
    install-session-driver false
 
    # or add a environment variable-setting script to
    # ~/.config/kde-env-master.sh
    install-environment-driver true
 
    # Stop the build process on the first failure
    stop-on-failure true
 
    # Use a flat folder layout under ~/kde/src and ~/kde/build
    # rather than nested directories
    directory-layout flat
 
    # Build with LSP support for everything that supports it
    compile-commands-linking true
    compile-commands-export true
 
    git-repository-base qt6-copy https://invent.kde.org/qt/qt/
end global
end global


# With base options set, the remainder of the file is used to define modules to build, in the
include ~/.local/share/kdesrc-build/data/build-include/kf${_ver}-qt${_ver}.ksb
# desired order, and set any module-specific options.
}}
#
# Modules may be grouped into sets, and this is the normal practice.
#
# You can include other files inline using the "include" command. We do this here
# to include files which are updated with kdesrc-build.
 
# Common options that should be set for some KDE modules no matter how
# kdesrc-build finds them. Do not comment these out unless you know
# what you are doing.
include /home/username/kde/src/kdesrc-build/kf6-common-options-build-include
 
# Qt and some Qt-using middleware libraries. Uncomment if your distribution's Qt
# tools are too old but be warned that Qt take a long time to build!
include /home/username/kde/src/kdesrc-build/qt6-build-include
include /home/username/kde/src/kdesrc-build/custom-qt6-libs-build-include
 
# KF5 and Plasma :)
#include /home/username/kde/src/kdesrc-build/kf6-qt6-build-include
 
# To change options for modules that have already been defined, use an
# 'options' block. See kf6-common-options-build-include for an example
 
cat ~/kde/src/kdesrc-build/qt6-build-include
# Downloads and installs Qt6 from the KDE mirror, using Qt6's CMake support
# exclusively.  Consider this an unofficial build that won't be supported by Qt
# upstream since we don't go through the init-repository script.
# It is probably better to install from your local distribution devel packages
# if possible!
module-set qt6-set
    override-build-system qt6 # technically optional for now
 
    repository qt6-copy # as defined in kdesrc-buildrc-kf6-sample
    branch    6.4
 
    # Controls where Qt6 is installed
    prefix ${qtdir}
 
    # These have been manually placed in dependency order based on the
    # .gitmodules file in https://code.qt.io/cgit/qt/qt5.git/tree/.gitmodules
    # in "essential" or "addons" categories with some additions
    # qtdoc should be last to give it best opportunity to make needed docs
    use-modules qtbase qttools qtshadertools qtdeclarative qtsvg  \
        qtimageformats qtmultimedia qtwayland                    \
        qtwebsockets qtwebchannel qtwebengine qtwebview qtsensors            \
        qtnetworkauth qt5compat qtdoc qtpositioning              \
        qtvirtualkeyboard
 
    # if you want qtwebengine, add it to use-modules after "qtwebchannel" and
    # comment this out. Note qtwebengine has significant and different build
    # requirements of its own.
    #ignore-modules qtwebengine
 
    # Archiving API requires zstd support which may not be present in your CMake
    cmake-options -DQT_BUILD_TESTS=FALSE -DCMAKE_BUILD_TYPE=RelWithDebInfo \
                  -DQT_AVOID_CMAKE_ARCHIVING_API=TRUE
 
    cmake-generator Ninja # comment out if you want the default CMake generator
end module-set
 
options qtwebengine
    # qtwebengine build system is weird, involving make as the top-level driver
    # and then calling ninja for the bulk of the build.  qtwebengine is a bulky
    # module and having ninja use all cores at once may run out of memory if
    # not careful, so we use make to pass less aggressive Ninja flags.
    # num-cores-low-mem needs to be defined in your kdesrc-buildrc.
    make-options NINJAFLAGS=-j${num-cores-low-mem}
end options
 
# vim: set ft=kdesrc-buildrc:
 
</nowiki>}}
 
== Portable installation of kdesrc-build ==
 
The current directory (pwd) is important when running kdesrc-build. If there exists a file kdesrc-buildrc in the the current directory (pwd), kdesrc-build will prefer that file over ~/.config/kdesrc-buildrc.
 
If you are interested in or need separate builds of KDE software, like when building with Qt5 or Qt6, you can create a self-contained, portable installation of kdesrc-build in its own folder. This way, you can manage your kdesrc-build configuration files each in their own environment without mixing configurations or having to rebuild the universe every time you want to test a different one.
 
{{Input|1=<nowiki>
# To not lose your previous build, make a backup:
mv ~/.config/kdesrc-buildrc ~/.config/kdesrc-buildrc~bak && mv ~/kde ~/kde~bak
# Edit ~/.bashrc file and remove the kdesrc-build block.
# Set up kdesrc-build by following just the chapter https://community.kde.org/Get_Involved/development#Set_up_kdesrc-build
# Make sure to answer "No" when it asks if you want to add the kdesrc-build block to ~/.bashrc.
# Do not source ~/.bashrc.
# Edit ~/.bashrc file and remove the kdesrc-build block.
# Reboot the computer or relogin such that the $PATH environment variable
# does not contain the string "~/kde" or sub directories of "~/kde".
# You should not have built anything using kdesrc-build yet.
# Then move the generated kdesrc-buildrc to inside the new ~/kde folder:
mv ~/.config/kdesrc-buildrc ~/kde
# This will make kdesrc-build use this file even if ~/.config/kdesrc-buildrc exists.
# Then link kdesrc-build and kdesrc-run to the root of the ~/kde folder:
cd ~/kde
ln -s src/kdesrc-build/kdesrc-build .
ln -s src/kdesrc-build/kdesrc-run .
# Edit the file paths in ~/kde/kdesrc-buildrc
cd ~/kde
# Calling ~/kde/kdesrc-build will then only use the current folder's kdesrc-buildrc:
./kdesrc-build frameworks
mv ~/kde ~/kde.5 # Or to any other directory.
# Edit the file paths in the file ~/kde.5/kdesrc-buildrc
cd ~/kde.5
./kdesrc-build frameworks --refresh-build # Because binary files contain file full paths starting with "~/kde".
</nowiki>}}
 
== Two independent kdesrc-build installations on the same machine: kf6-qt6 and kf5-qt5 ==
 
Make a backup of your existing kdesrc-build setup.
<code>mv ~/.config/kdesrc-buildrc ~/.config/kdesrc-buildrc~bak && mv ~/kde ~/kde~bak</code>
 
Set up a portable kdesrc-build from scratch in the directory <code>~/kde</code>. See the chapter [[#Portable installation of kdesrc-build]] for details. But do not run kdesrc-build to build anything.
 
In the directory <code>~/kde</code> there will be a new kdesrc-build installation of type <code>kf5-qt5</code>.
 
At the end of this procedure there will be two independent and portable kdesrc-build installations:
* <code>~/kde5</code> - <code>kf5-qt5</code>
* <code>~/kde6</code> - <code>kf6-qt6</code>
 
{{Input|1=<nowiki>
# kf5-qt5 kdesrc-build installation.
cp ~/kde ~/kde5 # Or to any other directory.
# Edit the file paths in the file ~/kde5/kdesrc-buildrc to point to "~/kde5" instead of "~/kde".
cd ~/kde5
./kdesrc-build frameworks --refresh-build # Because binary files contain file full paths starting with "~/kde".
# Now you have a kdesrc-build kf5-qt5 installation in ~/kde5
 
# kf6-qt6 kdesrc-build installation.
mv ~/kde ~/kde6 # Or to any other directory.
# Edit the file ~/kde6/kdesrc-buildrc such that the kdesrc-build installation becomes one of type kf6-qt6.
# See this wiki page for examples on how to convert a kf5-qt5 kdesrc-build installation to a kf6-qt6 kdesrc-build installation.
# Edit the file paths in the file ~/kde6/kdesrc-buildrc to point to "~/kde6" instead of "~/kde".
cd ~/kde6
./kdesrc-build frameworks --refresh-build # Because binary files contain file full paths starting with "~/kde".
# Now you have a kdesrc-build kf6-qt6 installation in ~/kde6
</nowiki>}}
 
Usage:
 
{{Input|1=<nowiki>
# Use different terminal windows or tabs (e.g. different Konsole tabs) for
# kf5-qt5 and kf6-qt6
 
# Go to the terminal window or tab for kf5-qt5.
cd ~/kde5
./kdesrc-build kcalc
./kdesrc-run kcalc
 
# Go to the terminal window or tab for kf6-qt6.
cd ~/kde6
./kdesrc-build plasma-systemmonitor
./kdesrc-run plasma-systemmonitor
</nowiki>}}
 
== What is the command line of the processes started by kdesrc-build ==
 
E.g. what are the command lines that are run by kdesrc-build in order to run the CMake configure step for the kconfig KDE git repository?
 
{{Input|1=<nowiki>
kdesrc-build kconfig --no-src --no-include-dependencies --debug --refresh-build |& tee ~/a.txt
kate ~/a.txt &
</nowiki>}}
 
Returns:
 
{{Input|1=<nowiki>
Building kconfig (build system KDE CMake) from frameworks (1/1)
Queueing PKG_CONFIG_PATH to be set to /home/username/kde/usr/lib/pkgconfig
Queueing LD_LIBRARY_PATH to be set to /home/username/kde/usr/lib
Queueing PATH to be set to /home/username/kde/usr/bin:/home/username/kde/src/kdesrc-build:/home/username/.local/bin:/home/username/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin
Not prepending /home/username/kde/usr/lib/pkgconfig to PKG_CONFIG_PATH as it appears to already be defined in PKG_CONFIG_PATH.
Queueing PKG_CONFIG_PATH to be set to /home/username/kde/usr/lib/pkgconfig
Not prepending /home/username/kde/usr/lib to LD_LIBRARY_PATH as it appears to already be defined in LD_LIBRARY_PATH.
Queueing LD_LIBRARY_PATH to be set to /home/username/kde/usr/lib
Not prepending /home/username/kde/usr/bin to PATH as it appears to already be defined in PATH.
Queueing PATH to be set to /home/username/kde/usr/bin:/home/username/kde/src/kdesrc-build:/home/username/.local/bin:/home/username/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin
Queueing CMAKE_PREFIX_PATH to be set to /home/username/kde/usr
Queueing CMAKE_MODULE_PATH to be set to /home/username/kde/usr/lib64/cmake:/home/username/kde/usr/lib/cmake
Queueing XDG_DATA_DIRS to be set to /home/username/kde/usr/share:/usr/share/plasma:/home/username/.local/share/flatpak/exports/share:/var/lib/flatpak/exports/share:/usr/local/share:/usr/share:/var/lib/snapd/desktop
Source update complete for kconfig: Skipped
cd /home/username/kde/build
 
Preparing build system for kconfig.
Removing files in build directory for kconfig
Old build system cleaned, starting new build system.
cd /home/username/kde/build/kconfig
 
Running cmake targeting Unix Makefiles...
run_logged_p(): Module kconfig, Command: {'cmake', '-B', '.', '-S', '/home/username/kde/src/kconfig', '-G', 'Unix Makefiles', '-DCMAKE_EXPORT_COMPILE_COMMANDS:BOOL=ON', '-DCMAKE_BUILD_TYPE=Debug', '-DQT_MAJOR_VERSION=6', '-DBUILD_WITH_QT6=ON', '-DBUILD_TESTING=TRUE', '-DBUILD_WITH_QT6=ON', '-DEXCLUDE_DEPRECATED_BEFORE_AND_AT=5.99.0', '-DCMAKE_CXX_FLAGS:STRING=-pipe', '-DCMAKE_INSTALL_PREFIX=/home/username/kde/usr'} from /home/username/kde/build/kconfig
cd /home/username/kde/build/kconfig
 
log_command(): Module kconfig, Command: cmake -B . -S /home/username/kde/src/kconfig -G Unix Makefiles -DCMAKE_EXPORT_COMPILE_COMMANDS:BOOL=ON -DCMAKE_BUILD_TYPE=Debug -DQT_MAJOR_VERSION=6 -DBUILD_WITH_QT6=ON -DBUILD_TESTING=TRUE -DBUILD_WITH_QT6=ON -DEXCLUDE_DEPRECATED_BEFORE_AND_AT=5.99.0 -DCMAKE_CXX_FLAGS:STRING=-pipe -DCMAKE_INSTALL_PREFIX=/home/username/kde/usr
run_logged_p(): kconfig cmake complete: 0
</nowiki>}}
 
Therefore, kdesrc-build has run the following commands:
 
{{Input|1=<nowiki>
# Preparing build system for kconfig. Removing files in build directory for kconfig. Old build system cleaned, starting new build system.
rm -rf /home/username/kde/build/kconfig
mkdir -p /home/username/kde/build/kconfig
 
# Queueing X to be set to ...
PKG_CONFIG_PATH=/home/username/kde/usr/lib/pkgconfig
LD_LIBRARY_PATH=/home/username/kde/usr/lib
PATH=/home/username/kde/usr/bin:/home/username/kde/src/kdesrc-build:/home/username/.local/bin:/home/username/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin
CMAKE_PREFIX_PATH=/home/username/kde/usr
CMAKE_MODULE_PATH=/home/username/kde/usr/lib64/cmake:/home/username/kde/usr/lib/cmake
XDG_DATA_DIRS=/home/username/kde/usr/share:/usr/share/plasma:/home/username/.local/share/flatpak/exports/share:/var/lib/flatpak/exports/share:/usr/local/share:/usr/share:/var/lib/snapd/desktop
 
cd /home/username/kde/build/kconfig
 
cmake -B . -S /home/username/kde/src/kconfig -G Unix\ Makefiles -DCMAKE_EXPORT_COMPILE_COMMANDS:BOOL=ON -DCMAKE_BUILD_TYPE=Debug -DQT_MAJOR_VERSION=6 -DBUILD_WITH_QT6=ON -DBUILD_TESTING=TRUE -DBUILD_WITH_QT6=ON -DEXCLUDE_DEPRECATED_BEFORE_AND_AT=5.99.0 -DCMAKE_CXX_FLAGS:STRING=-pipe -DCMAKE_INSTALL_PREFIX=/home/username/kde/usr
</nowiki>}}


== Other CPU architectures than x86_64/amd64 and x86 ==
== Other CPU architectures than x86_64/amd64 and x86 ==
Line 538: Line 224:
== kdesrc-build issues ==
== kdesrc-build issues ==


=== "kdesrc-build kfilemetadata" fails because of appimage ===
See https://community.kde.org/Get_Involved/development/Install_the_dependencies
 
This happens on KDE neon.
 
Solution:
<pre>
sudo apt remove libappimage-dev
</pre>
 
=== wayland-protocols is too old, e.g. "kdesrc-build kidletime" fails ===
 
<pre>
mkdir -p ~/kde/misc && cd ~/kde/misc
wget https://gitlab.freedesktop.org/wayland/wayland-protocols/-/releases/1.31/downloads/wayland-protocols-1.31.tar.xz
tar -xJvf wayland-protocols-*.tar.xz && mv wayland-protocols-*/ wayland-protocols
cd wayland-protocols
meson setup builddir --prefix $HOME/kde/usr
meson compile -C builddir
meson install -C builddir
</pre>


=== "kdesrc-build kpat" fails because of black-hole-solitaire ===
=== "kdesrc-build kpat" fails because of black-hole-solitaire ===
Line 570: Line 237:
</pre>
</pre>


=== "kdesrc-build frameworks" fails because of qtwebkit ===
=== libdisplay-info is not available ===


Some Linux OSes do not have a package for qtwebkit anymore. E.g. the Arch Linux family.
If your Linux OS does not have a package for libdisplay-info.
 
Append at the end of the file <code>kdesrc-buildrc</code>:
When you want to build all of the KDE Frameworks 5, use the kdesrc-build command line from https://community.kde.org/Get_Involved/development#KDE_Frameworks .
<pre>
module libdisplay-info
  repository https://gitlab.freedesktop.org/emersion/libdisplay-info.git
end module
</pre>

Revision as of 05:04, 16 August 2024

This page is the continuation with more advanced topics of the page Get_Involved/development.

kde-builder is an alternative to kdesrc-build

kdesrc-build and kde-builder are two KDE build frameworks. They are used at the command line and have identical command line syntax, just replace the string "kdesrc-build" with "kde-builder". They use the same configuration file, named kdesrc-buildrc.

kde-builder is newer and regularly gets new features and is written in Python.

kdesrc-build is in maintenance mode and feature frozen and written in Perl.

The "how to install kde-builder" procedure is here https://invent.kde.org/sdk/kde-builder/-/blob/master/README.md .

Develop in a Linux container

When you start programming for KDE, it is recommended that you use kdesrc-build in your main operating system or in a virtual machine running on a Linux operating system that is better supported by kdesrc-build.

As an alternative, you can run kdesrc-build in a Linux container (docker, podman, toolbx, distrobox).

Option 1. The KDE PIM Docker image

You can install Docker and the KDE PIM Docker image. It provides a development environment that is isolated from your day-to-day system. It is based on KDE Neon Unstable.

Option 2. distrobox

It is possible to start developing KDE software using container images that are able to see inside your home folder. This can be done using distrobox and podman.

This solution is particularly useful for users on immutable distributions like Fedora Kinoite, openSUSE Kalpa or the Steam Deck's SteamOS.

To learn how to build KDE software with distrobox, see: https://develop.kde.org/docs/getting-started/building/containers-distrobox/

Other operating systems

Kubuntu >= 23.10

The default configuration of kdesrc-build requires Qt version 6.6. Kubuntu 23.10 and 24.04 have Qt version 6.4.2. It is recommended that you use a Linux OS that is better supported by kdesrc-build.

If you are a more seasoned developer you might be able to use Kubuntu for kdesrc-build by installing Qt6 using the Qt online installer or by building Qt6 using kdesrc-build.

Alpine Linux

apk add git perl doas-sudo-shim

FreeBSD

Install the latest release of FreeBSD with KDE Plasma Desktop on your hardware computer or in a virtual machine.

Your user should be member of the "wheel" user group (e.g. this can be configured in the FreeBSD installer, when creating your user you can select additional user groups for your user). Your user should be able to use sudo: 

pkg install sudo
visudo
# Uncomment the line: %wheel ALL=(ALL:ALL) ALL

Then set up kdesrc-build using the same procedure as when installing kdesrc-build on a Linux operating system. FreeBSD is currently supported by kdesrc-build. See https://www.youtube.com/watch?v=8MqBnb3Y9JU

OpenBSD >= 7.5

Install OpenBSD version greater than or equal to 7.5. In the installer keep the defaults, the user created by the installer is named "administrator" in this example. 

# Enable doas
su -
cp /etc/examples/doas.conf /etc/doas.conf
exit
# kdesrc-build needs sudo.
mkdir -p ~/.local/bin ; ln -s /usr/bin/doas ~/.local/bin/sudo
echo "export PATH=~/.local/bin:\$PATH" >> ~/.bashrc

# Test doas.
doas su
# kde-builder needs bash.
pkg_add bash
chsh -s /usr/local/bin/bash
exit

# As user administrator
chsh -s /usr/local/bin/bash

# As per https://rsadowski.de/posts/2024-01-09-openbsd-kde/ , https://openports.pl/path/meta/kde,-plasma
doas su
pkg_add kde-plasma kate

# I recommend that you use tigervnc. https://nmariusp.github.io/install-os.html#openbsd--75

After you install kdesrc-build: 

# Edit the kdesrc-buildrc file e.g.:
cmake-options -DCMAKE_BUILD_TYPE=RelWithDebInfo -DKF_IGNORE_PLATFORM_CHECK=ON

# Also set environment variable:
export CMAKE_PREFIX_PATH=/usr/local/lib/qt6/cmake
# Or
export CMAKE_PREFIX_PATH=/usr/local/lib/qt5/cmake

Microsoft Windows

You can build and develop KDE projects using the Microsoft Windows operating system.

Apple macOS

You can build and develop KDE projects using the Apple macOS operating system.

What to do if CMake configure fails because a build dependency is missing

See https://community.kde.org/Get_Involved/development/Install_the_dependencies .

Project Documentation

Developer's documentation can be found in the doc/source-reference in the project repo.

kf6-qt6 vs. kf5-qt5

Many KDE git repositories can build correctly and run correctly using "kdesrc-build kf6-qt6".

The KDE git repositories that can build correctly and run correctly using "kdesrc-build kf6-qt6" have two long lived git branches:

  • A long lived git branch that does not contain the deprecated symbols from kf5-qt5, named e.g. "master".
  • And another long lived git branch for qt5-kf5, where the deprecated symbols still exist.

What is "kf6-qt6"? You just set up kdesrc-build following the procedure. The resulting kdesrc-build installation will be of type kf6-qt6. In kdesrc-buildrc in the "global" section you will have "branch-group kf6-qt6". The git repositories that have only one long lived git branch e.g. named "master" will use that. The git repositories that have a second long lived git branch, will use the git branch where the deprecated symbols do not exist e.g. named "master".

What is "kf5-qt5"? Follow the chapter "kdesrc-build Qt5". The resulting kdesrc-build installation will be of type kf5-qt5. In kdesrc-buildrc in the "global" section you will have "branch-group kf5-qt5". The git repositories that have only one long lived git branch e.g. named "master" will use that. The git repositories that have a second long lived git branch where the deprecated symbols still exist e.g. named "kf5" will use that.

Build Qt using kdesrc-build

Qt6

If you cannot build the KDE frameworks using kdesrc-build and the Qt provided by your Linux distribution is outdated, you might want to build the Qt framework using kdesrc-build.

In your configuration file use the qt-install-dir option (in the global section) with non-empty value, for example: 

global
  qt-install-dir ~/kde/usr
  branch-group kf6-qt6
end global

It is recommended that if you build Qt6 using kdesrc-build, you also build qtwebengine. Edit the file ~/.local/state/sysadmin-repo-metadata/module-definitions/qt6.ksb. Follow the instructions found in the file: if you want qtwebengine, add it to use-modules after "qtwebchannel" and comment out the line "ignore-modules qtwebengine". 

kdesrc-build qtbase --refresh-build --debug

Press Ctrl+C after the CMake configure summary for qtbase. Make sure that you have the needed dependencies. Should find libb2-dev, libproxy-dev, libmd4c-dev, libmd4c-html0-dev, libxcb-xinput-dev, libatspi2.0-dev, libsqlite3-dev, unixodbc-dev, libmysqlclient-dev, postgresql-client, libecpg-dev, libpq-dev. Optional dependencies libsctp-dev, libts-dev. 

kdesrc-build qtwebengine

This will build the Qt6 modules from qtbase up to qtwebengine. qtwebengine will probably be built incorrectly because some needed dependencies are missing. 

kdesrc-build qtwebengine --refresh-build --debug

Press Ctrl+C after the CMake configure summary for qtwebengine. Make sure that you have the needed dependencies. Should find node.js >= 14, libdbus-1-dev, libxcomposite-dev, libxshmfence-dev, libxdamage-dev, libharfbuzz-dev, libvpx-dev, libpci-dev, libevent-dev, libre2-dev, libsnappy-dev, libcups2-dev, libxkbfile-dev.

Then build Qt6: 

kdesrc-build qt6-set

To compile Qt6 with Qt X11 Extras (which is a necessary library to compile KWindowSystem), you should enable XCB feature during compilation 

kdesrc-build qt6-set --cmake-options="-DQT_FEATURE_xcb=ON"

Qt5

If you want the same for Qt5, change branch-group option and use qt5-set instead of qt6-set.

Qt 6 installed using the Qt online installer

A screen recording version is available https://www.youtube.com/watch?v=3BIbYN2vIZw

The homepage of the Qt Framework is https://www.qt.io . Go to this web page, create an online account. https://www.qt.io/download-open-source > "Download the Qt Online Installer" > Linux > "Qt Online Installer for Linux (64-bit)" > download a file named e.g. qt-unified-linux-x64-4.6.1-online.run into the directory e.g. "~/Downloads". 

ls -la ~/Downloads # The downloaded file needs to have the "executable" chmod bit set.
chmod u+x ~/Downloads/qt-unified-linux-x64-4.6.1-online.run
~/Downloads/qt-unified-linux-x64-4.6.1-online.run

A graphical user interface (GUI) installer wizard starts. Login using your Qt online account. Next > check the checkbox "I have read and agree to the terms and conditions of using OpenSource Qt", check the checkbox "I'm an individual and do not use Qt for any company" > Next > Next > enable "Help us improve" > Next > Custom installation, notice that the install directory is "~/Qt" > Next. Install the latest version of Qt6 and the latest version of the Qt Creator integrated development environment (IDE). There are some Qt6 components that are not used by KDE and can be left out when installing Qt6 e.g. Qt Design Studio, WebAssembly, Android, Sources, Qt Quick 3D, Qt 3D, Qt Quick 3D Physics, "Qt Debug Information Files". Next > enable "I have read and agree" > Next > Install.

In the KDE Plasma app launcher (start menu) you now have the application "Qt Maintenance Tool".

Set up kdesrc-build from scratch as usual.

Edit the file kdesrc-buildrc to look like: 

global
...
    qt-install-dir  ~/Qt/6.7.0/gcc_64 # Where to install Qt6 if kdesrc-build supplies it
    libname lib
...
end global

Two independent kdesrc-build configurations: kf6-qt6 and kf5-qt5

You can switch between configurations with --rc-file command line option. Generate another config, make the changes for the source-dir, build-dir, install-dir, and other changes you want. Make sure you use different value for persistent-data-file option, to not mix things up.

As an alternative, you can utilize custom variable to make switch from a single config: 

global
    _ver 5  # <-- Change this to switch
    source-dir ~/kde${_ver}/src
    build-dir ~/kde${_ver}/build
    install-dir ~/kde${_ver}/usr
    persistent-data-file ~/kde${_ver}/persistent-options.json
end global

include ~/.local/share/kdesrc-build/data/build-include/kf${_ver}-qt${_ver}.ksb

Other CPU architectures than x86_64/amd64 and x86

You can build and develop KDE projects using a Linux OS installed on an ARM architecture CPU.

kdesrc-build issues

See https://community.kde.org/Get_Involved/development/Install_the_dependencies

"kdesrc-build kpat" fails because of black-hole-solitaire

This happens on Debian/Ubuntu/Kubuntu. Because there is no Linux distribution binary package for https://github.com/shlomif/black-hole-solitaire.

Solution: append at the end of kdesrc-buildrc file: 

options kpat
    cmake-options -DWITH_BH_SOLVER=OFF
end options

libdisplay-info is not available

If your Linux OS does not have a package for libdisplay-info. Append at the end of the file kdesrc-buildrc: 

module libdisplay-info
  repository https://gitlab.freedesktop.org/emersion/libdisplay-info.git
end module
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