You pass in 1st seat holding this weak hand (unfavorable vul).
LHO passes, partner opens one diamond in 3rd seat, RHO passes, and you respond one spade. LHO now overcalls two clubs, partner rebids two diamonds, and RHO bids three clubs. It’s your turn. Bidding summary:
What do you do?
You sure hate to miss a possible heart fit. But your shortness in diamonds suggests a worrisome misfit. Should you go ahead and venture a bid of three hearts? If you do partner will know that you are at least 5-4 in the majors.
You have three clubs, so inference is that partner is short in clubs. Partner has promised at least six diamonds. Holding one club and six diamonds, partner has room for six cards in the majors. With that reasonable likelihood, it’s a good idea for you to compete with three hearts.