Emplace vs closures

[Steven Schveighoffer via Digitalmars-d]

On 9/19/16 10:26 AM, Lodovico Giaretta wrote:
> On Monday, 19 September 2016 at 14:22:16 UTC, Steven Schveighoffer wrote:
>> On 9/19/16 7:27 AM, Lodovico Giaretta wrote:
>>
>>> What I'd like to know: is this usage widespread? Should we forbid it for
>>> the sake of security?
>>
>> No. There is no security concern here. You are dereferencing a null
>> pointer, which is perfectly safe.
>>
> Ok, wrong wording. I meant "should we forbid it to avoid long hours of
> debugging and unexpected behaviours? One uses emplace expecting that it
> Just Works(TM), which is not true for nested things."

Maybe we can disable the emplace that will certainly cause a Null 
pointer segfault when used, and allow the copying version. But there may 
still be code that uses the struct without needing the context pointer, 
that would then be broken.

My opinion is just not to worry about it. We don't get much traffic here 
complaining of this issue, you may be the one hardest hit by it (and you 
likely won't have it happen any more).

For instance, we have way way more complaints of people using classes 
without allocating them, and that is a similar problem.

However, a sufficient warning in the docs is certainly in order, at 
least as long as we aren't going to forbid it.

-Steve