On Sat, 22 Jun 2024 at 21:32, Yongwei Wu <wuyongwei_at_[hidden]> wrote:
>
> On Sat, 22 Jun 2024 at 15:41, Jens Maurer <jens.maurer_at_[hidden]> wrote:
> > > https://cplusplus.github.io/CWG/issues/2823.html
> > >
> > > According to this issue, ptr->h() is undefined.
> >
> > That's the result, yes.
>
> Consider this variant:
>
> class Obj {
> public:
> constexpr int f() { return d_; }
> constexpr int g() { return 0; }
> constexpr static int h() { return 1; }
>
> private:
> int d_{};
> };
>
> constexpr auto ptr = static_cast<Obj*>(nullptr);
> constexpr int n1 = ptr->f();
> constexpr int n2 = ptr->g();
> constexpr int n3 = ptr->h();
>
> Will the standard require all the last three lines to generate errors,
> as required by [expr.const]/5.8?
> https://eel.is/c++draft/expr.const#5.8
>
> It seems to me a burden to the compilers, though I have no idea how
> difficult it is to implement it.
>
> Currently, only the n1 line generates errors in the three main
> compilers I tested. The n3 line does not even trigger a warning.

The report was not good enough. The latest GCC and Clang compilers
report errors on the n2 line.