pointer escaping return scope bug?

[ShadoLight]

On Friday, 25 November 2022 at 14:07:28 UTC, ShadoLight wrote:
>> On Saturday, 19 November 2022 at 14:07:59 UTC, Nick Treleaven
>>> ```d
>>> @safe:
>>>
>>> struct LockedFile
>>> {
>>>     private int* fps;
>>>
>>>     auto fp() return scope => fps;
>>> }
>>>
>>> void main()
>>> {
>>>     int* p;
>>>     {
>>>         auto lf = LockedFile(new int);
>>>         p = lf.fp;
>>>     }
>>>     assert(p != null); // address escaped
>>> }
>>> ```
[snip]
>
> I don't grok how `lf` can survive the local scope. Or am I 
> missing something?

Perhaps because the local scope is not pushed as a separate 
(anonymous) function on the stack... if true then, yes, then `lf` 
will indeed have the same physical lifetime as main (and `p`)...?

On the other hand, if you add a destructor to `LockedFile`, it 
will be invoked at the end of the local scope, not the end of 
main.

I find it a bit confusing what the term "lifetime" should pertain 
to in the case of variables declared inside a local scope inside 
a function - destructor invocation or physical existence of the 
variable on the stack?

But this has no bearing on the heap allocation and the lifetime 
of `p` in the example.