Inline warnings for version Qt 5.15

In QtCreator with version 5.15 I get these inline errors which I didn't with 5.12 and prior:

C:\Qt-development\TODD2\advancefilterworker.cpp:349: warning: C4714: function 'QString QStringView::arg<const QString&,const QString&>(const QString &,const QString &) const' marked as __forceinline not inlined

C:\Qt\5.15.0\msvc2015_64\include\QtCore\qstringview.h:231: see declaration of 'QStringView::arg'

I have the following compiler flag set:
QMAKE_CXXFLAGS_WARN_ON += -W4

If I comment out the flag, the warnings are gone. I'd like to keep the flag. 

Qt should be fixed to get rid of these warnings.

Thanks,
Dan