title: QT Creator warnings on empty project
body: <p>I'm using Qt Creator 4.12.0 with Qt 5.14.2 and GCC 5.3.1 and when I create a new project and build it without making any changes the there are about 32 warnings related to qvariant and qstyleoptions. if I include QVariant in the main file only one warning will be shown.</p>
  
  <p>the warning after compiling with #include :    </p>
  
  <pre><code>/opt/Qt/5.9.9/gcc_64/include/QtCore/qvariant.h:265: warning: implicitly-declared 
  ‘QVariant::Private&amp; QVariant::Private::operator=(const QVariant::Private&amp;)’ is deprecated [- 
  Wdeprecated-copy]
    265 |     { other.d = Private(); }
        |                         ^
  </code></pre>
  
  <p>why is this happening? I'm fairly new so I cannot figure out on my own.</p>