*programmer

вт, 28 окт. 2025 г. в 21:13, Nikl Kelbon <kelbonage_at_[hidden]>:

> I dont see this as counter example. Its example of type, where move
> constructor does not guarantee... Any guarantees. So, its just correct
> behavior, where
>
> 1. variant not changed (still A)
> 2. B tried to construct and throws exception
>
> I think compiler who writes such beaty code must expect exactly such
> behavior
>
> вт, 28 окт. 2025 г. в 20:58, Jonathan Wakely via Std-Proposals <
> std-proposals_at_[hidden]>:
>
>>
>>
>> On Tue, 28 Oct 2025 at 15:04, Pavel Vazharov via Std-Proposals <
>> std-proposals_at_[hidden]> wrote:
>>
>>> On Tue, Oct 28, 2025 at 4:46 PM Nikl Kelbon via Std-Proposals <
>>> std-proposals_at_[hidden]> wrote:
>>> >
>>> > Thanks for the links, but I don't see any discussion of this
>>> particular idea there. Instead, they're discussing allocating the value on
>>> the heap or doubling the buffer.0308
>>> The first sentence in the https://wg21.link/P0308 says
>>> This paper argues in section III that when variant's contained types
>>> have noexcept move constructors, variant *shall* *never* be valueless,
>>> that is, the specification should *statically* guarantee that
>>> valueless_by_exception() will *never* return true.
>>>
>>>
>> Ah yes, but you see that paper didn't discuss the possibility of "just
>> make it work for all types by using magic" ;-)
>>
>>
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>