[gcc r16-2109] libstdc++: Fix _GLIBCXX_DEBUG std::forward_list build regression

[Francois Dumont]

https://gcc.gnu.org/g:1f3bf202355f16d6ec0a9b37cb6a71be5f76b77f

commit r16-2109-g1f3bf202355f16d6ec0a9b37cb6a71be5f76b77f
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Tue Jul 8 19:20:13 2025 +0200

    libstdc++: Fix _GLIBCXX_DEBUG std::forward_list build regression
    
    Commit 2fd6f42c17a8040dbd3460ca34d93695dacf8575 broke _GLIBCXX_DEBUG
    std::forward_list implementation.
    
    libstdc++-v3/ChangeLog:
    
            * include/debug/forward_list (_Safe_forward_list<>::_M_swap):
            Adapt to _M_this() signature change.

Diff:
---
 libstdc++-v3/include/debug/forward_list | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/libstdc++-v3/include/debug/forward_list b/libstdc++-v3/include/debug/forward_list
index 4e1511da4e82..9da7dda45034 100644
--- a/libstdc++-v3/include/debug/forward_list
+++ b/libstdc++-v3/include/debug/forward_list
@@ -144,13 +144,13 @@ namespace __gnu_debug
       //std::swap(_M_this()->_M_version, __other._M_version);
       _Safe_iterator_base* __this_its = _M_this()->_M_iterators;
       _S_swap_aux(__other, __other._M_iterators,
-		  _M_this(), _M_this()->_M_iterators);
+		  *_M_this(), _M_this()->_M_iterators);
       _Safe_iterator_base* __this_const_its = _M_this()->_M_const_iterators;
       _S_swap_aux(__other, __other._M_const_iterators,
-		  _M_this(), _M_this()->_M_const_iterators);
-      _S_swap_aux(_M_this(), __this_its,
+		  *_M_this(), _M_this()->_M_const_iterators);
+      _S_swap_aux(*_M_this(), __this_its,
 		  __other, __other._M_iterators);
-      _S_swap_aux(_M_this(), __this_const_its,
+      _S_swap_aux(*_M_this(), __this_const_its,
 		  __other, __other._M_const_iterators);
     }