How do I check if a type is assignable to null at compile time?

[Jack]

On Saturday, 27 February 2021 at 01:23:06 UTC, H. S. Teoh wrote:
> On Sat, Feb 27, 2021 at 01:03:56AM +0000, Jack via 
> Digitalmars-d-learn wrote:
>> On Friday, 26 February 2021 at 23:37:18 UTC, Murilo wrote:
>> > On Friday, 26 February 2021 at 05:25:14 UTC, Jack wrote:
>> > > I started with:
>> > > 
>> > > enum isAssignableNull(T) = is(T : Object) || isPointer(T);
>> > > 
>> > > but how do I cover all cases?
>> > 
>> > You can check if it's null with this `variable is null` and 
>> > you can test it with assert as in `assert(variable is null);`
>> 
>> I mean a give type T not variablee
>
> Why not just:
>
> 	enum isAssignableNull(T) = is(typeof((T t){ t = null; }));
>
> ?
>
>
> T

works too, thanks but I ended up using Nathan S. solution which 
is quite fine too:
  enum bool isAssignableNull(T) = is(typeof(null) : T);