--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/testsuite/g++.dg/lto/pr68811_1.C	Fri Oct 27 22:46:09 2017 +0900
@@ -0,0 +1,94 @@
+// { dg-options "-O2 -flto -w" }
+template <typename> class allocator;
+template <typename _CharT, typename = _CharT, typename = allocator<_CharT>>
+class Trans_NS___cxx11_basic_string;
+struct __false_type {};
+template <typename> using __void_t = void;
+template <typename, typename, template <typename...> class, typename...>
+struct __detector {
+  using type = int;
+};
+template <typename _Default, template <typename...> class _Op,
+          typename... _Args>
+struct __detector<_Default, __void_t<_Op<_Args...>>, _Op, _Args...> {
+  using type = _Op<_Args...>;
+};
+template <typename _Default, template <typename...> class _Op,
+          typename... _Args>
+using __detected_or = __detector<_Default, void, _Op, _Args...>;
+template <typename _Default, template <typename...> class _Op,
+          typename... _Args>
+using __detected_or_t = typename __detected_or<_Default, _Op, _Args...>::type;
+template <template <typename...> class _Default,
+          template <typename...> class _Op, typename... _Args>
+using __detected_or_t_ = __detected_or_t<_Default<_Args...>, _Op, _Args...>;
+struct random_access_iterator_tag {};
+class __undefined;
+template <typename, typename> using __replace_first_arg_t = __undefined;
+template <typename> class allocator {
+public:
+  template <typename> struct rebind { typedef allocator other; };
+};
+struct __allocator_traits_base {
+  template <typename _Alloc, typename _Up>
+  using __rebind = typename _Alloc::template rebind<_Up>::other;
+  template <typename _Tp> using __pointer = typename _Tp::pointer;
+  template <typename _Tp> using __size_type = typename _Tp::size_type;
+};
+template <typename _Alloc, typename _Up>
+using __alloc_rebind =
+    __detected_or_t_<__replace_first_arg_t, __allocator_traits_base::__rebind,
+                     _Alloc, _Up>;
+struct allocator_traits : __allocator_traits_base {
+  using pointer = __detected_or_t<char, __pointer, allocator<char>>;
+  using size_type = __detected_or_t<int, __size_type, allocator<char>>;
+  template <typename _Tp>
+  using rebind_alloc = __alloc_rebind<allocator<char>, _Tp>;
+};
+struct __alloc_traits : allocator_traits {
+  struct rebind {
+    typedef rebind_alloc<int> other;
+  };
+};
+template <typename, typename, typename> class Trans_NS___cxx11_basic_string {
+public:
+  struct _Alloc_hider : __alloc_traits::rebind::other {
+    _Alloc_hider(__alloc_traits::pointer, allocator);
+  } _M_dataplus;
+  __alloc_traits::pointer _M_local_data();
+  template <typename _InIterator>
+  void _M_construct_aux(_InIterator __beg, _InIterator __end, __false_type) {
+    _M_construct(__beg, __end, random_access_iterator_tag());
+  }
+  template <typename _InIterator>
+  void _M_construct(_InIterator __beg, _InIterator __end) {
+    _M_construct_aux(__beg, __end, __false_type());
+  }
+  template <typename _FwdIterator>
+  void _M_construct(_FwdIterator, _FwdIterator, random_access_iterator_tag);
+  char _S_copy___s2;
+  void _S_copy(char *, __alloc_traits::size_type __n) {
+    __builtin_memcpy(0, &_S_copy___s2, __n);
+  }
+  template <class _Iterator>
+  void _S_copy_chars(char *__p, _Iterator __k1, _Iterator __k2) {
+    _S_copy(__p, __k2 - __k1);
+  }
+  Trans_NS___cxx11_basic_string(char *__s,
+                                allocator<char> __a = allocator<char>())
+      : _M_dataplus(_M_local_data(), __a) {
+    _M_construct(__s, __s);
+  }
+};
+template <typename _CharT, typename _Traits, typename _Alloc>
+template <typename _InIterator>
+void Trans_NS___cxx11_basic_string<_CharT, _Traits, _Alloc>::_M_construct(
+    _InIterator __beg, _InIterator __end, random_access_iterator_tag) {
+  _S_copy_chars(0, __beg, __end);
+}
+class Decimal {
+  Trans_NS___cxx11_basic_string<char> toString() const;
+};
+Trans_NS___cxx11_basic_string<char> Decimal::toString() const {
+  return "Infinity";
+}