qt6 (Qt GUI toolkit, version 6)

Qt6 is a complete and well-developed object-oriented framework for
developing graphical user interface (GUI) applications using C++.

The following configuration options are available for qt6:

QTWEBENGINE: Qt WebEngine is enabled by default. You can disable it
with QTWEBENGINE=OFF in the environment, then html5lib and nodejs22 will
be optional.

QT3D: Qt 3D is enabled by default. You can disable it with QT3D=OFF.

LLVM_OPT: llvm-opt is enabled by default, since LLVM >= 17 is required
for QDoc and QtTools. If you already installed llvm from extra or used
llvm in current branch, LLVM_OPT could be disabled with LLVM_OPT=OFF.

Qt6 requires 16GB of RAM to build, and a minimum of 49GB of available
disk storage.
