In file included from <path>\Qt\qt-everywhere-opensource-src-5.8.0\qtbase\src\corelib\kernel\qvariant.cpp:65:
In file included from <path>\Qt\qt-everywhere-opensource-src-5.8.0\qtbase\include\QtCore\5.8.0\QtCore\private/qvariant_p.h:1:
<path>\Qt\qt-everywhere-opensource-src-5.8.0\qtbase\include\QtCore\5.8.0\QtCore\private/../../../../../src/corelib/kernel/qvariant_p.h(433,
27):  error:
      use of overloaded operator '<<' is ambiguous (with operand types 'QDebug' and 'nullptr_t')
            dbg.nospace() << *v_cast<T>(d);
            ~~~~~~~~~~~~~ ^  ~~~~~~~~~~~~~
<path>\Qt\qt-everywhere-opensource-src-5.8.0\qtbase\include\QtCore\5.8.0\QtCore\private/../../../../../src/corelib/kernel/qvariant_p.h(454,
21):  note:
      in instantiation of member function 'QVariantDebugStream<(anonymous namespace)::CoreTypesFilter>::Filtered<nullptr_t, true>::Filtered' requested here
        Filtered<T> streamIt(m_debugStream, m_d);
                    ^
<path>\Qt\qt-everywhere-opensource-src-5.8.0\qtbase\src\corelib\kernel/qmetatypeswitcher_p.h(74,29):  note: in instantiation of function
      template specialization 'QVariantDebugStream<(anonymous namespace)::CoreTypesFilter>::delegate<nullptr_t>' requested here
    QT_FOR_EACH_STATIC_TYPE(QT_METATYPE_SWICHER_CASE)
                            ^
<path>\Qt\qt-everywhere-opensource-src-5.8.0\qtbase\src\corelib\kernel\qvariant.cpp(978,24):  note: in instantiation of function template
      specialization 'QMetaTypeSwitcher::switcher<void, QVariantDebugStream<(anonymous namespace)::CoreTypesFilter> >' requested here
    QMetaTypeSwitcher::switcher<void>(stream, d->type, 0);
                       ^
<path>\Qt\qt-everywhere-opensource-src-5.8.0\qtbase\include\QtCore/../../src/corelib/io/qdebug.h(153,20):  note: candidate function
    inline QDebug &operator<<(const char* t) { stream->ts << QString::fromUtf8(t); return maybeSpace(); }
                   ^
<path>\Qt\qt-everywhere-opensource-src-5.8.0\qtbase\include\QtCore/../../src/corelib/io/qdebug.h(158,20):  note: candidate function
    inline QDebug &operator<<(const void * t) { stream->ts << t; return maybeSpace(); }
                   ^
<path>\Qt\qt-everywhere-opensource-src-5.8.0\qtbase\include\QtCore/../../src/corelib/io/qdebug.h(162,20):  note: candidate function
    inline QDebug &operator<<(QTextStreamFunction f) {
                   ^
<path>\Qt\qt-everywhere-opensource-src-5.8.0\qtbase\include\QtCore/../../src/corelib/io/qdebug.h(137,20):  note: candidate function
    inline QDebug &operator<<(bool t) { stream->ts << (t ? "true" : "false"); return maybeSpace(); }
                   ^
<path>\Qt\qt-everywhere-opensource-src-5.8.0\qtbase\include\QtCore/../../src/corelib/io/qiodevice.h(186,22):  note: candidate function
Q_CORE_EXPORT QDebug operator<<(QDebug debug, QIODevice::OpenMode modes);
                     ^
<path>\Qt\qt-everywhere-opensource-src-5.8.0\qtbase\include\QtCore/../../src/corelib/io/qdebug.h(154,20):  note: candidate function
    inline QDebug &operator<<(const QString & t) { putString(t.constData(), uint(t.length())); return maybeSpace(); }
                   ^
<path>\Qt\qt-everywhere-opensource-src-5.8.0\qtbase\include\QtCore/../../src/corelib/io/qdebug.h(155,20):  note: candidate function
    inline QDebug &operator<<(const QStringRef & t) { putString(t.constData(), uint(t.length())); return maybeSpace(); }
                   ^
<path>\Qt\qt-everywhere-opensource-src-5.8.0\qtbase\include\QtCore/../../src/corelib/io/qdebug.h(157,20):  note: candidate function
    inline QDebug &operator<<(const QByteArray & t) { putByteArray(t.constData(), t.size(), ContainsBinary); return maybeSpace(); }
                   ^
<path>\Qt\qt-everywhere-opensource-src-5.8.0\qtbase\include\QtCore/../../src/corelib/tools/qregularexpression.h(168,22):  note: candidate
      function
Q_CORE_EXPORT QDebug operator<<(QDebug debug, QRegularExpression::PatternOptions patternOptions);
                     ^
<path>\Qt\qt-everywhere-opensource-src-5.8.0\qtbase\include\QtCore/../../src/corelib/plugin/quuid.h(229,22):  note: candidate function
Q_CORE_EXPORT QDebug operator<<(QDebug, const QUuid &);
                     ^
<path>\Qt\qt-everywhere-opensource-src-5.8.0\qtbase\src\corelib\kernel\qvariant.cpp(3615,8):  note: candidate function
QDebug operator<<(QDebug dbg, const QVariant &v)
       ^
1 error generated.