// Can a be converted to b?

// score 0 = exact match
// score Int.MAX_VALUE = no match
// score 1 = conversion needed (boxing/unboxing or non-primitve widening)
// score -1 = primitive widening needed

static int typeConversionScoreWithUnboxing(Class a, Class b) {
  int score = typeConversionScore(a, b);
  Class aPrim = boxedToPrimitive(a);
  if (aPrim != null)
    score = min(score, typeConversionScore(aPrim, b));
  ret score;
}