DIP1000: Scoped Pointers (Discussion)

[John Colvin via Digitalmars-d]

On Thursday, 11 August 2016 at 08:53:22 UTC, John Colvin wrote:
> On Thursday, 11 August 2016 at 08:45:38 UTC, Walter Bright 
> wrote:
>> On 8/11/2016 1:29 AM, John Colvin wrote:
>>> Can someone talk me through the lifetime algebra for the 
>>> following?
>>>
>>> void foo()
>>> {
>>>     int a;
>>>     int** c;
>>>     void bar()
>>>     {
>>>         int* b = &a;  <= ok, b has a smaller lifetime than a
>>>         c = &b;    <= error, c has a larger lifetime than b
>>>     }
>>>     bar();
>>>     *c; //undefined behaviour
>>> }
>
> but according to this rule:
>
> "For an unrestricted pointer, visibility is dictated by the 
> usual lexical scope rules. Lifetime, however is dictated by the 
> lifetime of the data to which the pointer points to."
>
> b should have the same lifetime as a, no?

ping on this? I want to understand what's going on here and be 
another set of eyes checking for mistakes, but I'm stuck on this 
bit of the spec.