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Subject: Re: [ub] type punning through congruent base class?
From: Ville Voutilainen (ville.voutilainen_at_[hidden])
Date: 2014-01-16 13:45:19


On 16 January 2014 21:41, Herb Sutter <hsutter_at_[hidden]> wrote:
> Matt quoted:
>
>
>
> "The lifetime of an object of type T begins when:
>
> — storage with the proper alignment and size for type T is obtained, and
>
> — if the object has non-trivial initialization, its initialization is
> complete."
>
>
>
> Perhaps the necessary fix is to strike “if the object has non-trivial
> initialization” here. I don’t see why trivial constructors are special –
> sure, they don’t do anything, but they are notionally important.
>
>
>
> A bag of memory of alignment and size suitable for T is-not-a T object until
> its (possibly trivial) ctor is called on that memory – it seems wrong for
> that to be true for all T except trivially-constructible T’s (with implicit
> universal type-punning for all types <= sizeof(T)).

Well, as far as I understand, trivial constructors might not be called at all.


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