hashtable_policy.h (_Hash_code_base): Restore default constructor protected.

2013-02-13  François Dumont  <fdumont@gcc.gnu.org>

	* include/bits/hashtable_policy.h (_Hash_code_base): Restore
	default constructor protected.
	* include/bits/hashtable.h: static assert that _Hash_code_base has
	a default constructor available through inheritance.

From-SVN: r196030

libstdc++-v3/ChangeLog

+2013-02-13  François Dumont  <fdumont@gcc.gnu.org>
+
+	* include/bits/hashtable_policy.h (_Hash_code_base): Restore
+	default constructor protected.
+	* include/bits/hashtable.h: static assert that _Hash_code_base has
+	a default constructor available through inheritance.
+
 2013-02-12  Paolo Carlini  <paolo.carlini@oracle.com>
 
 	* include/c_std/cstdlib (at_quick_exit, quick_exit): Provide in

libstdc++-v3/include/bits/hashtable.h

@@ -266,7 +266,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       // __hash_code_base above to compute node bucket index so it has to be
       // default constructible.
       static_assert(__if_hash_not_cached<
-		      is_default_constructible<__hash_code_base>>::value,
+		    is_default_constructible<
+		      // We use _Hashtable_ebo_helper to access the protected
+		      // default constructor.
+		      __detail::_Hashtable_ebo_helper<0, __hash_code_base>>>::value,
 		    "Cache the hash code or make functors involved in hash code"
 		    " and bucket index computation default constructible");
 

libstdc++-v3/include/bits/hashtable_policy.h

@@ -918,15 +918,13 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       using __ebo_extract_key = _Hashtable_ebo_helper<0, _ExtractKey>;
       using __ebo_hash = _Hashtable_ebo_helper<1, _Hash>;
 
-    public:
-      // We need the default constructor for the local iterators.
-      _Hash_code_base() = default;
-
     protected:
       typedef void* 					__hash_code;
       typedef _Hash_node<_Value, false>			__node_type;
 
-    protected:
+      // We need the default constructor for the local iterators.
+      _Hash_code_base() = default;
+
       _Hash_code_base(const _ExtractKey& __ex, const _H1&, const _H2&,
 		      const _Hash& __h)
       : __ebo_extract_key(__ex), __ebo_hash(__h) { }
@@ -1004,13 +1002,13 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       hash_function() const
       { return _M_h1(); }
 
-      // We need the default constructor for the local iterators.
-      _Hash_code_base() = default;
-
     protected:
       typedef std::size_t 				__hash_code;
       typedef _Hash_node<_Value, false>			__node_type;
 
+      // We need the default constructor for the local iterators.
+      _Hash_code_base() = default;
+
       _Hash_code_base(const _ExtractKey& __ex,
 		      const _H1& __h1, const _H2& __h2,
 		      const _Default_ranged_hash&)