Visualization - misuse of enumeration in Prs3d_DatumAspect

When OCCT is built with GCC 7.1 compiler (MinGw-64), it reports warning "enum constant in boolean context" [-Wint-in-bool-context] in Prs3d_DatumAspect.

The code looks as follows:

void Prs3d_DatumAspect::SetDrawFirstAndSecondAxis (Standard_Boolean theToDraw)
{
  if (theToDraw)
  {
    myAxes = Prs3d_DatumAxes(myAxes | Prs3d_DA_XAxis | Prs3d_DA_YAxis);
  }
  else
  {
    myAxes = Prs3d_DatumAxes(myAxes & !Prs3d_DA_XAxis & !Prs3d_DA_YAxis);
  }
}

The expressions in parentheses yield integers. It is not correct to cast integer to enum, as it is not guaranteed to yield a valid value for that enum.

Here Prs3d_DatumAxes is enum with defined single bit values for X=1, Y=2, Z=4, and bit combinations XY, XZ, YZ, XYZ. The second assignment will yield zero if myAxes in the beginning equal to e.g. Prs3d_DA_XAxis. However, zero is not valid value for Prs3d_DatumAxes enum.