For C++ code similar to ...

#include <complex>

void fxn()
{
    std::complex<float> scf1, scf2;  // scf: standard complex float
    cfloat bcf1, bcf2;               // bcf: built-in complex float
    float f1;

    scf1 = scf2 * f1;
    // scf1.real = scf2.real * f1; scf1.imag = scf2.imag * f1;
    bcf1 = bcf2 * f1;
    // error: Cannot auto-widen "float" into "cfloat"
}

The first multiply operation works as shown in the pseudocode in the comment.  The second multiply operation gets the error diagnostic shown in the comment.

The user request is to change the meaning of the multiply operator * for the types cfloat and float so that it matches the behavior of the multiply operator * for the types std::complex<float> and float. And so on for all the other operations between float and cfloat.