`this A1 const &self` requires that this object must be convertible to
`A1 const &`. Apparently B1 cannot be converted to A1, due to the
private inheritance.

On Fri, 14 Aug 2026 at 21:37, sidneycogdil via Std-Discussion
<std-discussion_at_[hidden]> wrote:
>
> https://godbolt.org/z/MxacGPbGo
>
> ```cpp
> struct A1 {
> A1(int a)
> : a(a)
> {
> }
>
> auto get(this A1 const &self)
> {
> return self.a;
> }
>
> private:
> int a;
> };
>
> struct B1 : private A1 {
> using A1::get;
> };
>
> auto f(B1 &b)
> {
> auto n = b.get(); // doesn't work. bad
> (void)n;
> }
>
> struct A2 {
> A2(int a)
> : a(a)
> {
> }
>
> auto get() const
> {
> return this->a;
> }
>
> private:
> int a;
> };
>
> struct B2 : private A2 {
> using A2::get;
> };
>
> auto f(B2 &b)
> {
> auto n = b.get(); // works. good
> (void)n;
> }
>
> ```
>
> The only difference is that explicit object parameter is used in A1::get but
> not in A2::get.
>
>
>
> --
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> Std-Discussion_at_[hidden]
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-- 
Yongwei Wu
URL: http://wyw.dcweb.cn/