Jeremy,

*If the motivation is reusing the name, consider what rust has done with
shadowing:*
*let x = foo();*
*let x = x.transform(); // new x shadows old x, can be a new type*
*There is precedent for this mechanism in C++ now with P2169.*

Thank you!


On Wed, Dec 10, 2025 at 11:02 AM Jeremy Rifkin via Std-Proposals <
std-proposals_at_[hidden]> wrote:

> Hi,
> It is extremely unlikely something like this would ever be added to C++.
> Such a change would require a lot of motivation, and this paper doesn't
> currently provide much motivation.
>
> If the motivation is reusing the name, consider what rust has done with
> shadowing:
> let x = foo();
> let x = x.transform(); // new x shadows old x, can be a new type
> There is precedent for this mechanism in C++ now with P2169.
>
> If the motivation is compiler optimization, this is a micro-optimization
> and would be harmful as a language feature. Compilers can very easily
> identify when objects in a function are dead and reclaim storage and
> registers.
>
> If the motivation is ending an object's lifetime as far as the C++
> abstract machine is concerned and calling destructors, just use
> std::optional:
> std::optional<T> thing;
> ...
> thing.reset(); // destroy the object, call the destructor
> This is much more simple and straightforward to reason about than the
> language feature you're proposing. If you are concerned about the overhead
> from the flag std::optional stores to indicate if a value is contained or
> not, this is something compilers should be able to optimize with relative
> ease, though the overhead would be completely negligible in almost all
> cases even if it didn't.
>
> Cheers,
> Jeremy
>
>
>
> On Tue, Dec 9, 2025 at 8:23 PM wjf via Std-Proposals <
> std-proposals_at_[hidden]> wrote:
>
>> see attachment
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