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Subject: Re: Placement new into static storage violates strict pointer safety?
From: Andrew Tomazos (andrewtomazos_at_[hidden])
Date: 2019-08-23 23:49:01


On Fri, Aug 23, 2019 at 4:00 PM language.lawyer--- via Std-Discussion <
std-discussion_at_[hidden]> wrote:

> [basic.stc] is known to be completely broken.
>
> Consider:
>
> struct { int i; int j; } s;
> int main()
> {
> ::new(&s.j) int{};
> }
>
> The newly-created int object is a subobject of `s` ([intro.object]/2)
>

How did you conclude that this is defined behaviour? What happens to the
old int subobject s.j? How did you conclude that the newly-created int
object is a subobject of the s object?

> Since it was created using new-expression, it has dynamic storage duration
> ([basic.stc]/2).
> But [basic.stc.inherit]/1 says "The storage duration of subobjects and
> reference members is that of their complete object", so it has static
> storage duration.
> --
> Std-Discussion mailing list
> Std-Discussion_at_[hidden]
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>



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