By Echo Wang July 21 (Reuters) - The Nasdaq edged higher on Thursday boosted by gains in electric automaker Tesla on its better-than-expected quarterly results, which helped offset a slide in telecom and energy shares. Tesla TSLA.O surged 10.1%, while AT&T Inc T.N tumbled to bring down telecom shares after the wireless carrier cut its cash flow forecast saying some subscribers were delaying bill payments. Rising inflation also led the European Central Bank to belatedly join global peers in a rate-hike cycle with an aggressive 50-basis point increase.