How should I cover an empty space between a fence post and a garage wall?
Rip a 45 degree notch down the center of a post (4 x 4 x hgt of gate) and install into a post anchor bracket and than afix to the brick mortar joints with TapCon screws. Or TapCon a 2 x 4 to one edge of the corner and cap the edge with another 2 x 4 on the other corner edge. If you can dig a hole sink a metal or wooden post and attach a fence board to it. Pour a cement footing and build a brick pillar with those left over half bricks. Attach a dog-eared fence board to the edge of the gate. Or install 2 angle brackets, bent to 22.5 degrees, to the mortar joints of the brick wall (with TapCons) and attach fence board to the bracket. Or pour a footing and install concrete block on edge, wrap extruded metal lathing around it, and trowel on a stucco finish.