oops should be writeln(typeof(__traits(getMember, vulkan_input, m)).stringof); that compiles but still prints nothing
trypragma(msg, typeof(__traits(getMember, vulkan_input, m)).stringof);
because at compile time the code generated for writeln() is not executed.
Also take care with the getMember trait, it will only work if the member is public. (or not public but located in the module where the __traits() code resides).