Splatty Splat Splat Splat

If I call Fn with the value 1, what does it return?

struct FiveValues {
  int One;
  uint Two;
  float Three;
  int FourFive[2];
};

export int Fn(int X) {
  FiveValues V = (FiveValues)X;
  return V.One + V.Two + V.Three + V.FourFive[0] + V.FourFive[1];
}

A. 1

B. 2

C. 3

D. 4

E. 5

F. This cannot possible compile… right?

Answer!

E!

In HLSL when a scalar value is cast to any aggregate type (vectors, matrices, arrays or user defined structs), the scalar value is cast to the appropriate types and replicated into each element of the aggregate.

See it here in Compiler Explorer.