C Macro deeper meaning?

[Kagamin via Digitalmars-d-learn]

On Sunday, 31 January 2016 at 02:58:28 UTC, Andrew Edwards wrote:
>     void notUsed(T)(T v) { return cast(void)0; };
>
> since it always returns cast(void)0 regardless of the input.
>
> But it cannot be that simple, so what am I missing?

Now notUsed has an unused parameter v.