//moc_customplot.cpp a section
...
const QMetaObject QCP::staticMetaObject = { {
nullptr,
qt_meta_stringdata_QCP.offsetsAndSize,
qt_meta_data_QCP,
nullptr,
nullptr,
qt_incomplete_metaTypeArray<qt_meta_stringdata_QCP_t
, QtPrivate::TypeAndForceComplete<QCP, std::true_type> // *** in this line QCP is a namespace.. so I know //that...
//is illegal. so why is this happening

//customplot.h section
#ifndef Q_MOC_RUN
namespace QCP {
#else
class QCP { // when in moc-run, make it look like a class, so we get Q_GADGET, Q_ENUMS/Q_FLAGS features in //namespace

>,
nullptr
} };

This error seems the fault of the library to me. I understand I might be missing something... though... ... ...

So am I doing something wrong ?

Please help!