Re: [boost] AllocatorAwareContainers

Subject: Re: [boost] AllocatorAwareContainers
From: Joaquin M López Muñoz (joaquinlopezmunoz_at_[hidden])
Date: 2017-06-15 08:46:23

El 15/06/2017 a las 10:17, Gavin Lambert via Boost escribió:
> [...]
>
> Granted it's easy enough to make this safe once you're aware of it, 
> but it seems like a way-too-easy trap to fall into.  eg. this would be 
> a "safe" node:
>
>     struct node
>     {
>         explicit node(node* n = nullptr) : next(n) {}
>
>         node* next;
>         T& value() { return reinterpret_cast<T&>(storage); }
>
>     private:
>         std::aligned_storage_t<sizeof(T), alignof(T)> storage;
>     };
>
> But of course now it's not a POD.

It's not a POD, but it has a trvial default ctor. My reading of 3.8 
Object lifetime [basic.life]
implies that you can omit construction and begin using a just-allocated 
object when
its default ctor is trivial. Maybe some language lawyer can shed some 
light here.

Joaquín M López Muñoz