1 files changed, 39 insertions, 0 deletions
diff --git a/libstdc++-v3/include/bits/stl_list.h b/libstdc++-v3/include/bits/stl_list.h
index f8bfff18b19..3401e5b4d25 100644
--- a/libstdc++-v3/include/bits/stl_list.h
+++ b/libstdc++-v3/include/bits/stl_list.h
@@ -1868,6 +1868,45 @@ _GLIBCXX_END_NAMESPACE_CXX11
     { __x.swap(__y); }
 
 _GLIBCXX_END_NAMESPACE_CONTAINER
+
+#if _GLIBCXX_USE_CXX11_ABI
+_GLIBCXX_BEGIN_NAMESPACE_VERSION
+
+  // Detect when distance is used to compute the size of the whole list.
+  template<typename _Tp>
+    inline ptrdiff_t
+    __distance(_GLIBCXX_STD_C::_List_iterator<_Tp> __first,
+	       _GLIBCXX_STD_C::_List_iterator<_Tp> __last,
+	       input_iterator_tag __tag)
+    {
+      typedef _GLIBCXX_STD_C::_List_const_iterator<_Tp> _CIter;
+      return std::__distance(_CIter(__first), _CIter(__last), __tag);
+    }
+
+  template<typename _Tp>
+    inline ptrdiff_t
+    __distance(_GLIBCXX_STD_C::_List_const_iterator<_Tp> __first,
+	       _GLIBCXX_STD_C::_List_const_iterator<_Tp> __last,
+	       input_iterator_tag)
+    {
+      typedef _GLIBCXX_STD_C::_List_node<size_t> _Sentinel;
+      _GLIBCXX_STD_C::_List_const_iterator<_Tp> __beyond = __last;
+      ++__beyond;
+      bool __whole = __first == __beyond;
+      if (__builtin_constant_p (__whole) && __whole)
+	return static_cast<const _Sentinel*>(__last._M_node)->_M_data;
+
+      ptrdiff_t __n = 0;
+      while (__first != __last)
+	{
+	  ++__first;
+	  ++__n;
+	}
+      return __n;
+    }
+
+_GLIBCXX_END_NAMESPACE_VERSION
+#endif
 } // namespace std
 
 #endif /* _STL_LIST_H */