DMD can implicitly convert class pointer to the bool. Is it bug or terrible feature?

[ilya-stromberg]

On Sunday, 24 November 2013 at 23:31:38 UTC, Andrei Alexandrescu 
wrote:
> On 11/24/13 11:17 AM, bearophile wrote:
>> Walter Bright:
>>
>>> Shadowing globals is definitely a bad idea. Shadowing 
>>> members, it's
>>> debatable.
>>
>> So are you saying D here should give an error for the 
>> shadowing of the
>> module-level x?
>
> I think he meant "shadowing locals". As I wrote in TDPL, it's a 
> bad idea to add a global somewhere and break a bunch of code 
> that has nothing to do with it.

Yes, but D allows to use it. And in few cases global variable can 
be useful.
For example, we can have thread-local variable for database 
connection that used almost everywhere.