I didn't touch the Qt build system for some time and learned the hard way, that my former scripts for Qt 5.6 are not longer working.

Particular problem: Building Qt Designer from sources along the Qt source libraries for Windows:
System: Win 10, VS 2017, qt-everywhere-src-5.12.1.zip

My build went supposedly error-free with the following configure options:
Qt Code:
  1. -opensource ^
  2. -confirm-license ^
  3. -opengl desktop ^
  4. -platform %VCPLATFORM% ^
  5. -nomake examples ^
  6. -nomake tests ^
  7. -make-tool jom ^
  8. -skip qtwebengine ^
  9. -prefix %INSTALL_DIR%
To copy to clipboard, switch view to plain text mode 

(the batch variables are probably self-explanatory). Afterwards, no designer.exe could be found and after fiddling without luck with qmake pro files, I discovered the new build system based on 'configure.json' files:

Qt Code:
  1. src\qt-everywhere-src-5.12.1\qttools\configure.json
To copy to clipboard, switch view to plain text mode 

containing a single subconfig "src/qdoc". This is, what I was seeing after my build - some attempt to build qdoc and nothing else from qttools (it has of course his own share of problems, because it requires now libclang - but this is a different story). Also, designer doesn't have a json-based subconfig.

What I am supposed to do, in order to build these things? In particular if I prefer my source tree untouched. Is there some mechanism in overriding the provided configure.json from outside (command line etc.) and what exactly are the incarnations, required for building Qt designer (or better, for some sort of "Qt with all tools")?

I wasn't able to find any meaningful documentation, answering these questions (except an incomplete intro at https://wiki.qt.io/Qt_Configuration_System