AW: [std-proposals] return value lives until end of scope

See here, why break N is a bad idea.

The same applies to %%

https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2025/p3568r0.html

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Von: Frederick Virchanza Gotham via Std-Proposals <std-proposals@lists.isocpp.org>
Gesendet: Sa 23.05.2026 10:23
Betreff: Re: [std-proposals] return value lives until end of scope
An: std-proposals@lists.isocpp.org;
CC: Frederick Virchanza Gotham <cauldwell.thomas@gmail.com>;

On Saturday, May 23, 2026, Sebastian Wittmeier wrote:

You can use a single variable (container for futures) and use it as reference parameter to a function creating your async call.

I think the following:

int main()
{

for ( unsigned i = 0u; i < N; ++i )
{
%%async(Func);
}

}

would have to be implemented by the compiler something like:

int main()
{

struct Frame {
alignas(std::future<int>) char unsigned f[ sizeof(std::future<int>) ];
Frame *next;
};

Frame fr;
Frame *p = &fr;

for ( unsigned i = 0u; i < N; ++i )
{
::new(p->f) std::future<int>{ async(Func) };
p->next = alloca( sizeof *p );
p->next.next = nullptr;
p = p->next;
}

for ( p = &fr; nullptr != p; p = p->next )
{
((std::future<int>*)p->f)->~std::future<int>();
}
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