string <-> null/bool implicit conversion

[Timon Gehr via Digitalmars-d]

On 08/21/2015 01:34 PM, "Marc =?UTF-8?B?U2Now7x0eiI=?= 
<schuetzm at gmx.net>" wrote:
> On Thursday, 20 August 2015 at 19:41:44 UTC, Jonathan M Davis wrote:
>> On Thursday, 20 August 2015 at 17:50:11 UTC, Steven Schveighoffer wrote:
>>> if(arr != null)
>>
>> Definitely don't do that. IMHO, "== null and "!= null" should be
>> illegal. If you really want to check for null, then you need to use
>> "is null" or "!is null", whereas if you want to check that an array is
>> empty, check its length or call empty. By using "== null" or "!=
>> null", you tend to give the false impression that you're checking
>> whether the object or array is null - which is not what you're
>> actually doing.
>
> I disagree. `is null` is the one that should be illegal. `is` is
> supposed to do a bitwise comparison,

If 'is null' is disallowed, what's the point of allowing '== null'?

> but `null` is usually just a
> pointer/reference,  while a slice consists of both a reference and a
> length.

There's a 'null slice'. Both pointer and length are null. It's what the 
implicit conversion from 'typeof(null)' yields.

> Which of those are compared?

Both. You explained it above.