[gcc r12-5311] libstdc++: Use hidden friends for vector<bool>::reference swap overloads

[Jonathan Wakely <redi@gcc.gnu.org>]

https://gcc.gnu.org/g:59434931fb658f0a180ce3f3305cb3987ed2b56d

commit r12-5311-g59434931fb658f0a180ce3f3305cb3987ed2b56d
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Thu Nov 11 20:51:15 2021 +0000

    libstdc++: Use hidden friends for vector<bool>::reference swap overloads
    
    These swap overloads are non-standard, but are needed to make swap work
    for vector<bool>::reference rvalues. They don't need to be called
    explicitly, only via ADL, so hide them from normal lookup. This is what
    I've proposed as the resolution to LWG 3638.
    
    libstdc++-v3/ChangeLog:
    
            * include/bits/stl_bvector.h (swap(_Bit_reference, _Bit_reference))
            (swap(_Bit_reference, bool&), swap(bool&, _Bit_reference)):
            Define as hidden friends of _Bit_reference.

Diff:
---
 libstdc++-v3/include/bits/stl_bvector.h | 50 ++++++++++++++++-----------------
 1 file changed, 25 insertions(+), 25 deletions(-)

diff --git a/libstdc++-v3/include/bits/stl_bvector.h b/libstdc++-v3/include/bits/stl_bvector.h
index 381c47b6132..68070685baf 100644
--- a/libstdc++-v3/include/bits/stl_bvector.h
+++ b/libstdc++-v3/include/bits/stl_bvector.h
@@ -125,36 +125,36 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
     void
     flip() _GLIBCXX_NOEXCEPT
     { *_M_p ^= _M_mask; }
-  };
 
 #if __cplusplus >= 201103L
-  _GLIBCXX20_CONSTEXPR
-  inline void
-  swap(_Bit_reference __x, _Bit_reference __y) noexcept
-  {
-    bool __tmp = __x;
-    __x = __y;
-    __y = __tmp;
-  }
+    _GLIBCXX20_CONSTEXPR
+    friend void
+    swap(_Bit_reference __x, _Bit_reference __y) noexcept
+    {
+      bool __tmp = __x;
+      __x = __y;
+      __y = __tmp;
+    }
 
-  _GLIBCXX20_CONSTEXPR
-  inline void
-  swap(_Bit_reference __x, bool& __y) noexcept
-  {
-    bool __tmp = __x;
-    __x = __y;
-    __y = __tmp;
-  }
+    _GLIBCXX20_CONSTEXPR
+    friend void
+    swap(_Bit_reference __x, bool& __y) noexcept
+    {
+      bool __tmp = __x;
+      __x = __y;
+      __y = __tmp;
+    }
 
-  _GLIBCXX20_CONSTEXPR
-  inline void
-  swap(bool& __x, _Bit_reference __y) noexcept
-  {
-    bool __tmp = __x;
-    __x = __y;
-    __y = __tmp;
-  }
+    _GLIBCXX20_CONSTEXPR
+    friend void
+    swap(bool& __x, _Bit_reference __y) noexcept
+    {
+      bool __tmp = __x;
+      __x = __y;
+      __y = __tmp;
+    }
 #endif
+  };
 
   struct _Bit_iterator_base
   : public std::iterator<std::random_access_iterator_tag, bool>