int fn();

void whatever()
{
    (void) fn();
}

Is there any reason for casting an unused return value to void, or am I right in thinking it's a complete waste of time?

Follow up:

Well that seems pretty comprehensive. I suppose it's better than commenting an unused return value since self documenting code is better than comments. Personally, I'll turn these warnings off since it's unnecessary noise.

I'll eat my words if a bug escapes because of it...