qHash woes

Since Qt 6 I'm running into this compiler warning ( here gcc 10.2.1 ) with a qHash implementation for a custom type:

warning: ISO C++ says that these are ambiguous, even though the worst conversion for the first is better than the worst conversion for the second.

The corresponding code looks like this:

class AxisId
{
  public:
    AxisId( int position, int index = 0 );
    ...
};

inline uint qHash( const AxisId& axisId, uint seed = 0 ) noexcept
{
    ...
}

Now when calling qHash for an int it seems to be unclear for gcc wether it should call qHash( int, ... ) or qHash( AxisId, ... ). I didn't check what gcc is actually doing, but from the warning my guess would be, that it takes the wrong one for AxisId.

Guess this is a general problem of the implementation in Qt6. It is not possible to define a qHash operation for a type that has a constructor from a type where a qHash implementation exists.

The complete code can be found here: https://sourceforge.net/p/qwt/code/HEAD/tree/branches/qwt-6.1-multiaxes/src/qwt_axis_id.h