[PATCH] Adjust tr1::_Hashtable to work with std::allocator in C++20

[Jonathan Wakely]

In C++20 std::allocator will no longer define construct and destroy
member functions, so using them needs to go via allocator_traits.
   
       * include/tr1/hashtable.h (tr1::_Hashtable::_M_allocate_node): Use
       __gnu_cxx::__alloc_traits for allocator construct function.
       (tr1::_Hashtable::_M_deallocate_node): Likewise for destroy function.
I forgot to include the necessary header, so there was another patch
to fix that:

       * include/tr1/hashtable.h: Add header for __gnu_cxx::__alloc_traits.

Tested x86_64-linux, committed to trunk.


commit 614abedbab087928017033aa7962e6c2dd3ec5d3
Author: redi <redi@138bc75d-0d04-0410-961f-82ee72b054a4>
Date:   Fri Oct 4 13:17:54 2019 +0000

    Add missing header required by previous change
    
            * include/tr1/hashtable.h: Add header for __gnu_cxx::__alloc_traits.
    
    git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@276576 138bc75d-0d04-0410-961f-82ee72b054a4

diff --git a/libstdc++-v3/include/tr1/hashtable.h b/libstdc++-v3/include/tr1/hashtable.h
index 85fec6a6a14..354d7b814eb 100644
--- a/libstdc++-v3/include/tr1/hashtable.h
+++ b/libstdc++-v3/include/tr1/hashtable.h
@@ -34,6 +34,7 @@
 #pragma GCC system_header
 
 #include <tr1/hashtable_policy.h>
+#include <ext/alloc_traits.h>
 
 namespace std _GLIBCXX_VISIBILITY(default)
 {

commit 5bf86f5e0fc6567f69eb299eb1c9d4a74f105bb7
Author: redi <redi@138bc75d-0d04-0410-961f-82ee72b054a4>
Date:   Fri Oct 4 12:17:01 2019 +0000

    Adjust tr1::_Hashtable to work with std::allocator in C++20
    
    In C++20 std::allocator will no longer define construct and destroy
    member functions, so using them needs to go via allocator_traits.
    
            * include/tr1/hashtable.h (tr1::_Hashtable::_M_allocate_node): Use
            __gnu_cxx::__alloc_traits for allocator construct function.
            (tr1::_Hashtable::_M_deallocate_node): Likewise for destroy function.
    
    git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@276575 138bc75d-0d04-0410-961f-82ee72b054a4

diff --git a/libstdc++-v3/include/tr1/hashtable.h b/libstdc++-v3/include/tr1/hashtable.h
index c1b5c9e8fda..85fec6a6a14 100644
--- a/libstdc++-v3/include/tr1/hashtable.h
+++ b/libstdc++-v3/include/tr1/hashtable.h
@@ -429,7 +429,9 @@ namespace tr1
       _Node* __n = _M_node_allocator.allocate(1);
       __try
 	{
-	  _M_get_Value_allocator().construct(&__n->_M_v, __v);
+	  _Value_allocator_type __a = _M_get_Value_allocator();
+	  typedef __gnu_cxx::__alloc_traits<_Value_allocator_type> _Traits;
+	  _Traits::construct(__a, &__n->_M_v, __v);
 	  __n->_M_next = 0;
 	  return __n;
 	}
@@ -449,7 +451,9 @@ namespace tr1
 	       _H1, _H2, _Hash, _RehashPolicy, __chc, __cit, __uk>::
     _M_deallocate_node(_Node* __n)
     {
-      _M_get_Value_allocator().destroy(&__n->_M_v);
+      _Value_allocator_type __a = _M_get_Value_allocator();
+      typedef __gnu_cxx::__alloc_traits<_Value_allocator_type> _Traits;
+      _Traits::destroy(__a, &__n->_M_v);
       _M_node_allocator.deallocate(__n, 1);
     }