In small pan, mix sugar, cornstarch and salt. Stir in raspberries with syrup and lemon juice. Heat to boiling and cook for 1 minute, stirring constantly. Remove from heat. Press raspberry mixture through sieve. Discard seeds. Stir drained cherries into raspberry mixture and pour into lightly buttered 8 x 8 inch baking dish.
Cream butter and sugar in small bowl. Blend in flour and salt til crumbly. Sprinkle crumbs over fruit. Bake at 375 for 30 to 35 minutes or til lightly browned. Serve warm with ice cream. Serves 4 to 6