[Bug libstdc++/101571] DestroyGuard used by the ranges::uninitialized family should use addressof()

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101571

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2021-07-22

--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Rather than add __addressof everywhere, we could change the constructor to take
a reference and take the address in the constructor:

--- a/libstdc++-v3/include/bits/ranges_uninitialized.h
+++ b/libstdc++-v3/include/bits/ranges_uninitialized.h
@@ -106,8 +106,8 @@ namespace ranges

       public:
        explicit
-       _DestroyGuard(const _Iter* __iter)
-         : _M_first(*__iter), _M_cur(__iter)
+       _DestroyGuard(const _Iter& __iter)
+         : _M_first(__iter), _M_cur(std::__addressof(__iter))
        { }

        void
@@ -149,7 +149,7 @@ namespace ranges
          return ranges::next(__first, __last);
        else
          {
-           auto __guard = __detail::_DestroyGuard(&__first);
+           auto __guard = __detail::_DestroyGuard(__first);
            for (; __first != __last; ++__first)
              ::new (__detail::__voidify(*__first)) _ValueType;
            __guard.release();

and so on for each use of it.

But I also have a patch to just do this everywhere:

--- a/libstdc++-v3/include/bits/ranges_uninitialized.h
+++ b/libstdc++-v3/include/bits/ranges_uninitialized.h
@@ -149,7 +149,7 @@ namespace ranges
          return ranges::next(__first, __last);
        else
          {
-           auto __guard = __detail::_DestroyGuard(&__first);
+           auto __guard = __detail::_DestroyGuard(std::__addressof(__first));
            for (; __first != __last; ++__first)
              ::new (__detail::__voidify(*__first)) _ValueType;
            __guard.release();