I am well aware of the initializer_list solution, my point being that this
mistake is too easy to make. It breaks the "easy to use, hard to missuse"
principle.

// Robin

On Thu, Mar 6, 2025, 11:55 Hewill Kang <hewillk_at_[hidden]> wrote:

> You can use std::initializer_list to prevent dangling issue:
>
> ```c++
> auto [min, max] = std::minmax({a, b - a});
> ```
>
>
> Robin Savonen Söderholm via Std-Proposals <std-proposals_at_[hidden]>於
> 2025年3月6日 週四，18:27寫道：
>
>> Hi!
>>
>> I recently got burned by a piece of innocent looking code that was
>> something along the lines of this:
>> ```c++
>> auto [min, max] = std::minmax(a, b - a);
>> ```
>> The problem stems from the fact that std::minmax (not initialiser_list
>> api) returns a std::pair<T const&, T const&> regardless of what the
>> arguments are AND that the structural bindings 'auto' is just making sure
>> that the object being separated is not a reference, NOT that the objects
>> inside [...] are not references...
>> In the best of worlds I would argue that `auto [x, y] = ...` would mean
>> that `x` and `y` are pure values, but I guess such a change could cause
>> trouble due to breaking currently working code that relies on the reference
>> capture (and it would complicate the meaning of `auto& [x, y] = ...`).
>> A simpler option would be to change the API for the minmax function (and
>> perhaps other, similar looking functions) to something where if an RValue
>> is detected amongst the arguments, it would return a std::pair<T, T> only
>> (or pair<T const, T const>), while if all arguments are lvalue references
>> it could keep it's current form (for speed or for the need of testing the
>> address of an argument or something..)
>>
>> What would be the best remedy for things like this you think?
>> --
>> Std-Proposals mailing list
>> Std-Proposals_at_[hidden]
>> https://lists.isocpp.org/mailman/listinfo.cgi/std-proposals
>>
>