[committed] libstdc++: Use std::addressof to avoid ADL for operator& [PR 60497]

[Jonathan Wakely via Gcc-patches]

This is another small step towards avoiding the problems described in PR
60497, by using std::addressof to avoid ADL, so that we don't require
all template arguments to be complete.

libstdc++-v3/ChangeLog:

        PR libstdc++/60497
        * include/bits/basic_ios.tcc (basic_ios::copyfmt): use
        std::addressof.
        * include/bits/basic_string.tcc (basic_string::swap)
        (basic_string::assign): Likewise.
        * include/bits/deque.tcc (deque::operator=(const deque&)):
        Likewise.
        * include/bits/stl_tree.h (_Rb_tree::operator=(const * _Rb_tree&)):
        Likewise.
        * include/bits/vector.tcc (vector::operator=(const vector&)):
        Likewise.

Tested powerpc64le-linux. Committed to trunk.


commit 47915ef8477569b2fbd8001996aa4e542284bb24
Author: Jonathan Wakely <jwak...@redhat.com>
Date:   Fri Apr 30 14:45:42 2021

    libstdc++: Use std::addressof to avoid ADL for operator& [PR 60497]
    
    This is another small step towards avoiding the problems described in PR
    60497, by using std::addressof to avoid ADL, so that we don't require
    all template arguments to be complete.
    
    libstdc++-v3/ChangeLog:
    
            PR libstdc++/60497
            * include/bits/basic_ios.tcc (basic_ios::copyfmt): use
            std::addressof.
            * include/bits/basic_string.tcc (basic_string::swap)
            (basic_string::assign): Likewise.
            * include/bits/deque.tcc (deque::operator=(const deque&)):
            Likewise.
            * include/bits/stl_tree.h (_Rb_tree::operator=(const * _Rb_tree&)):
            Likewise.
            * include/bits/vector.tcc (vector::operator=(const vector&)):
            Likewise.

diff --git a/libstdc++-v3/include/bits/basic_ios.tcc 
b/libstdc++-v3/include/bits/basic_ios.tcc
index f79aad97cf0..6285f734031 100644
--- a/libstdc++-v3/include/bits/basic_ios.tcc
+++ b/libstdc++-v3/include/bits/basic_ios.tcc
@@ -64,7 +64,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     {
       // _GLIBCXX_RESOLVE_LIB_DEFECTS
       // 292. effects of a.copyfmt (a)
-      if (this != &__rhs)
+      if (this != std::__addressof(__rhs))
        {
          // Per 27.1.1, do not call imbue, yet must trash all caches
          // associated with imbue()
diff --git a/libstdc++-v3/include/bits/basic_string.tcc 
b/libstdc++-v3/include/bits/basic_string.tcc
index 35b60865f58..0c13e744747 100644
--- a/libstdc++-v3/include/bits/basic_string.tcc
+++ b/libstdc++-v3/include/bits/basic_string.tcc
@@ -58,7 +58,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     basic_string<_CharT, _Traits, _Alloc>::
     swap(basic_string& __s) _GLIBCXX_NOEXCEPT
     {
-      if (this == &__s)
+      if (this == std::__addressof(__s))
        return;
 
       _Alloc_traits::_S_on_swap(_M_get_allocator(), __s._M_get_allocator());
@@ -254,7 +254,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     basic_string<_CharT, _Traits, _Alloc>::
     _M_assign(const basic_string& __str)
     {
-      if (this != &__str)
+      if (this != std::__addressof(__str))
        {
          const size_type __rsize = __str.length();
          const size_type __capacity = capacity();
diff --git a/libstdc++-v3/include/bits/deque.tcc 
b/libstdc++-v3/include/bits/deque.tcc
index db532e3c585..ab1f49813df 100644
--- a/libstdc++-v3/include/bits/deque.tcc
+++ b/libstdc++-v3/include/bits/deque.tcc
@@ -95,7 +95,7 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
     deque<_Tp, _Alloc>::
     operator=(const deque& __x)
     {
-      if (&__x != this)
+      if (std::__addressof(__x) != this)
        {
 #if __cplusplus >= 201103L
          if (_Alloc_traits::_S_propagate_on_copy_assign())
diff --git a/libstdc++-v3/include/bits/stl_tree.h 
b/libstdc++-v3/include/bits/stl_tree.h
index 550195a2749..96299129810 100644
--- a/libstdc++-v3/include/bits/stl_tree.h
+++ b/libstdc++-v3/include/bits/stl_tree.h
@@ -1729,7 +1729,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
     operator=(const _Rb_tree& __x)
     {
-      if (this != &__x)
+      if (this != std::__addressof(__x))
        {
          // Note that _Key may be a constant type.
 #if __cplusplus >= 201103L
diff --git a/libstdc++-v3/include/bits/vector.tcc 
b/libstdc++-v3/include/bits/vector.tcc
index 8a6a99fb537..caee5cbfc2f 100644
--- a/libstdc++-v3/include/bits/vector.tcc
+++ b/libstdc++-v3/include/bits/vector.tcc
@@ -198,7 +198,7 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
     vector<_Tp, _Alloc>::
     operator=(const vector<_Tp, _Alloc>& __x)
     {
-      if (&__x != this)
+      if (std::__addressof(__x) != this)
        {
          _GLIBCXX_ASAN_ANNOTATE_REINIT;
 #if __cplusplus >= 201103L