On QtCreator, Options, C++, Code Model, General I see the following option
Ignore precompiled headers
And there is a tooltip on mouse hover.
I read about PCH on https://doc.qt.io/qt-5/qmake-precompiledheaders.html, but I would like to know the implications of this checkbox? It says
parsing for code completition
and semantic highlighting
will process the precompiled header before processing any file