Qt-opensource-windows-x86-5.15.2.exe

New "required" properties for components and better tool support for formatting and linting QML code. LTS Stability: As a patch release, 5.15.2 specifically included 176 bug fixes

Select (for applications) or GNU GPL v3 (if you are also releasing your source code). Accept. qt-opensource-windows-x86-5.15.2.exe

You selected a 32-bit MinGW that defaults to C++98. Fix: In your .pro file, add: New "required" properties for components and better tool