D how to check null

original text

enum canBeNull(T) = is(typeof({
    T t; t = null;}));
static assert(canBeNull!(Object));
static assert(!canBeNull!(int));

I do , Heavy duty opAssign and opCmp.
I check static if(is(typeof(null) : T))( Can be implicitly converted to T), Or use __traits(compiles, v is null) Better .