[Bug c++/113308] New: derived class doesn't currently allow inherited explicit object member function post increment operator

[cooky.ykooc922 at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113308

            Bug ID: 113308
           Summary: derived class doesn't currently allow inherited
                    explicit object member function post increment
                    operator
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: cooky.ykooc922 at gmail dot com
  Target Milestone: ---

With the recent support of explicit object parameter functions, inheriting
explicit object member functions from base class seems to work except for post
increment operator 'operator++(int)'.

struct add_fn
{
    template <typename Self>
    Self operator++(this Self&& self, int)
    {
      auto temp = self;
      ++self;
      return temp;
    }
};

struct A : add_fn 
{
    int n;
    A(int n) : n(n) {}

    A& operator++() 
    {
      ++n;
      return *this;
    }

    // this doesn't work either:
    // A& operator++(this A& self)
    // {
    //   ++self.n;
    //   return self;
    // }
};

int main()
{
    A a { 5 };
    ++a; // ok
    a++; // error: no 'operator++(int)' declared for postfix '++'
}

godbolt link: https://godbolt.org/z/1h57Thvds