Should I tell my doctor I smoke weed?

Always tell your doctor anything that can impact your health, they have no reason and no ability to report you for it except maybe if you're underage and it becomes a duty of care thing.

Only thing it can hurt with is if you're trying to get certain medications that can't be prescribed to people that smoke a lot of weed or drink a lot of alcohol etc. and half the time the doc will give you a warning like "I have to ask this cause if you say X then I can't do it"