void test2 ( SV *sv ) {
    double d = SvIV( sv );
    double d2 = SvUV( sv );
    return;
}

IC_sort.c
IC_sort.xs(42) : warning C4244: 'initializing' : conversion from 'IV' to 'double', possible loss of data
IC_sort.xs(43) : warning C4244: 'initializing' : conversion from 'UV' to 'double', possible loss of data