Express "Class argument may not be null" ?

[Steven Schveighoffer via Digitalmars-d-learn]

On 8/8/17 3:59 PM, Johan Engelen wrote:
> On Tuesday, 8 August 2017 at 19:38:19 UTC, Steven Schveighoffer wrote:
>>
>> Note that C++ also can do this, so I'm not sure the & is accomplishing 
>> the correct goal:
>>
>> void foo(Klass&);
>>
>> int main()
>> {
>>    Klass *k = NULL;
>>    foo(*k);
>> }
> 
> In C++, it is clear that the _caller_ is doing the dereferencing, and 
> the dereference is also explicit.

In fact it's not doing any dereferencing. It's just under the hood 
passing a pointer.

>> However, the in contract does actually enforce the requirement.
> 
> And adds null pointer checks even when clearly not needed.

Clearly not needed? I thought the point was to ensure the reference is 
not null?

-Steve