union.zig

donp@jewel 1off $ cat main.zig
pub const Command = struct {
  id: u16,
  payload: union {
    a: u16,
    b: u16
  }
};

pub fn main() void {
  const myCommand = Command{.id = 1,
                            .payload = @typeOf(@field(Command, "payload")){.a = 1}};
}
donp@jewel 1off $ zig build-exe main.zig
/home/donp/code/tootdeck/zig/1off/main.zig:11:48: error: container 'Command' has no member called 'payload'
                            .payload = @typeOf(@field(Command, "payload")){.a = 1}};
                                               ^