Spread crushed pineapple evenly into a lightly greased 13- x 9-inch baking dish. Spread cherry pie filling over pineapple.
Stir together cake mix, 1 cup water, and oil just until blended. (Batter will be lumpy.) Pour over cherry filling. Sprinkle with pecans.
Bake at 350° for 40 to 50 minutes or until cake is golden.