Francisco Casas (@fcasas) commented about tests/uav.shader_test:
float4 main() : sv_target { /* All four components must be written in a single statement. */ u[uint2(0, 0)].xy = float4(1, 2);
It is not a fault of this patch but, since you are editing this file, `float4(1, 2)` and `float(3, 4)` are not valid.