No, that's not true.
So why don't you go to a MinGW forum and ask there?and I cannot see any solution so far how to use mingw compiler here.
As already said it is not glued to anything. It supports everything qmake or cmake support, msvc included.The easiest way to switch to msvc. I just wanted to use QtCreator ("editor" as u says) instead of Visual Studio "editor". Unfortunatelly its "glued" to mingw, so there is no other choice.
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