[Bug libstdc++/123758] New: warning: base class ‘class std::polyfunc::_Mo_base’ should be explicitly initialized in the copy constructor [-Wextra]

[redi at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=123758

            Bug ID: 123758
           Summary: warning: base class ‘class std::polyfunc::_Mo_base’
                    should be explicitly initialized in the copy
                    constructor [-Wextra]
           Product: gcc
           Version: 16.0
            Status: UNCONFIRMED
          Keywords: diagnostic
          Severity: normal
          Priority: P3
         Component: libstdc++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: redi at gcc dot gnu.org
                CC: tkaminsk at gcc dot gnu.org
  Target Milestone: ---

#include <functional>

int main()
{
  std::copyable_function<void()> f;
}

g++ -std=c++26 func.cc -Wextra -Wsystem-headers


In file included from /home/jwakely/gcc/16/include/c++/16.0.1/functional:93,
                 from func.cc:1:
/home/jwakely/gcc/16/include/c++/16.0.1/bits/funcwrap.h: In copy constructor
'std::__polyfunc::_Cpy_base::_Cpy_base(const std::__polyfunc::_Cpy_base&)':
/home/jwakely/gcc/16/include/c++/16.0.1/bits/funcwrap.h:497:7: warning: base
class 'class std::__polyfunc::_Mo_base' should be explicitly initialized in the
copy constructor [-Wextra]
  497 |       _Cpy_base(_Cpy_base const& __x)
      |       ^~~~~~~~~


I think this should have `: _Mo_base()` on the copy constructor to avoid the
warning.