The musical, that grand old film form, had been dormant for a couple of decades when Baz Luhrmann, rather than just reviving the musical, attached it to the defibrillator of his wild imagination. In this mash-up of 42nd Street and Camille, the nightclub chanteuse played by Nicole Kidman evokes Marilyn and Madonna as she swings above the crowd warbling “Diamonds Are a Girl’s Best Friend.” Ewan McGregor, as the poor writer who falls for the courtesan, is a nouveau Gene Kelly — a hunky Joe with a radiant smile, haunting the Left Bank like An American in Paris, twirling an umbrella a la Singin’ in the Rain. A sultry chorus line coos, “Moulin Rouge-ez avec moi ce soir?” and performs a tantric cancan. An all-out tribute to India’s Bollywood musical — a kind of “Springtime for Hindu” — has enough eye candy to give the viewer diabetes. Mixing the romantic and the grotesque, the songs of MGM and MTV, and two stars at the peak of their appeal, Luhrmann created a rhapsody in red, a musical that is both retro and now-tro.