How much sugar in bacardi gold and diet coke?

There is essentially no sugar in either of those. The fermentation process turns sugar into ethanol, so even though rum is made from sugar cane there's little residual sugar in it (exception: some flavored rums - especially the fruity ones - add sugar back in), and Diet Coke has no sugar (it uses artificial sweeteners instead).

Rum is not calorie-free ... it's got on average about 60 calories per fluid ounce ... but that's mostly because ethanol itself has calories, not from sugar.