Stir together cherries, sugar, flour, lemon juice, and salt in a bowl. Pour into crust. Sprinkle the remaining crumbly flour mixture evenly over top, squeezing to create clumps. Bake about 1 hour, until filling is bubbly and top is nicely browned. If you find it is browning too quickly, you can cover the top loosely with foil. Remove from oven and allow to cool in pan for about 20 minutes. Remove from pan and let cool completely on a wire rack, about 1 hour. Cut into 2-inch squares.