C++ - Qt 5.11.2 - Problem with complex numbers and later Qt version [solved]

Hello,

Qt about:-
Qt Creator 4.7.1
Based on Qt 5.11.2 (MSVC 2015, 32 bit)

Compiler
C:\Qt\Tools\mingw530_32\bin\g++.exe

I'm getting these errors when loading an old project into Qt Creator.
It did compile with an earlier version of Qt.
Can somebody enlighten me?

Regards

Code:

---

no member named 'real' in 'std::complex<double>'
no member named 'imag' in 'std::complex<double>'

---

Code:

---

QPointF divide::findLineEndPoint( double startX, double startY,
                                  double length, double angle ) //radians
{
    auto endPoint = ( std::complex<double> ( startX, startY )
                      + std::polar<double> ( length, angle ) );
 
    return ( QPointF ( endPoint.real(), endPoint.imag() ) );
}

---

It was a problem with the 'kits' being mixed up.