Building my project all of a sudden gets this message:

error: C2589: '(' : illegal token on right side of '::' at QCustomPlot.hpp:4261:

Is this a Microsoft compiler problem. When I googled the error I got a reference to visual studio 2013 and the claim it is fixed in visual studio 2015.

While compiling class template member function 'double QCPAbstractPlottable1D<QCPGraphData>::selectTest(const QPointF &,bool,QVariant *) const'

see reference to class template instantiation 'QCPAbstractPlottable1D<QCPGraphData>' being compiled

To cause the problem I include a header for a class that is derived from QCustomPlot.