test/shader_io/vertex_input_builtins.wgsl

[[stage(vertex)]]
fn main(
  [[builtin(vertex_index)]] vertex_index : u32,
  [[builtin(instance_index)]] instance_index : u32,
) -> [[builtin(position)]] vec4<f32> {
  let foo : u32 = vertex_index + instance_index;
  return vec4<f32>();
}