DIP1000

[Ola Fosheim Grøstad]

On Wednesday, 29 June 2022 at 05:51:26 UTC, bauss wrote:
> Not necessarily, especially if the fields aren't value types. 
> You can have stack allocated "objects" with pointers to heap 
> allocated memory (heap allocated "objects".)

Those are not fields, those are separate objects… The compiler 
knows which is a field (part of the object).

> You can't, or rather you shouldn't have stack allocated fields 
> within heap allocated "objects" however; as that will almost be 
> guaranteed to lead to problems.

That is perfectly ok if you use RAII and manage life times.

> Ex. from your example then even if the "node struct" you pass 
> was allocated on the stack, then the memory the "next" pointer 
> points to might not be allocated same place.
>
> Unless I'm misunderstanding what you're trying to say.

You did :). If you look at the post I made in general about 
DIP1000 and flow typing you see that I annotate scope with a 
number to indicate life time ordering.

If you have `connect(int* a,int* b){a.next = b}` then the 
compiler can deduce that the signature with formal parameters 
should be `connect(scope!N(int*) a, scope_or_earlier!N(int*) b)`. 
The compiler then checks that the actual parameters at the call 
site are subtypes (same type or proper subtype).