If I understand correctly, you want to disable pass-by-value semantics? I'm
not sure what you're referring to in your code example as well.
Or, are you trying to say that delegating constructors should not be
allowed to pass-by-value?

Op ma 13 mei 2024 om 16:36 schreef David wang via Std-Proposals <
std-proposals_at_[hidden]>:

> Hi everyone.
>
> In C++, we can pass an object of the same type by value to the constructor
> of the class, which results in a copy of the same type or its subtype being
> required.
>
> The sequence of constructor calls can be greatly optimized by disabling
> copying of the same type or its subtypes before constructing an object.
> I'm confused why C++ doesn't disable it.
>
> That is, when we are going to do something(constructing an object via some
> constructor), the prerequisite is that we need to do something of the same
> kind. For example, the derived(*int* i, derived that) and *template* <
> *typename* T> base(T x) in the code snippet below.
>
> *struct* base {
>
> base() {}
>
> *template* <*typename* T> base(T x) {}
>
> };
>
> *struct* derived : *public* base {
>
> derived(){}
>
> derived(*int* i, derived that): base(that) {}
>
> derived(derived& that): base(that) {}
>
> };
>
> *int* main() {
>
> derived d1;
>
> derived d2(d1);
>
> *return* 0;
>
> }
>
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>

-- 
Rhidian De Wit
Software Engineer - Barco