PR libstdc++/89090 avoid C++17 features in C++11/C++14 code

Although GCC and Clang both allow these features pre-C++17 in system
headers, Clang does issue warnings with -Wsystem-headers. It can also
complicate bisection and/or testcase reduction if # line markers are
stripped, because the code won't be known to come from system headers.

	PR libstdc++/89090
	* include/bits/stl_uninitialized.h (__relocate_a_1): Make unused
	parameter unnamed. Add message to static assertion.
	* include/bits/vector.tcc (vector::reserve, vector::_M_realloc_insert)
	(vector::_M_default_append): Use _GLIBCXX17_CONSTEXPR for if constexpr
	in C++11 code.

From-SVN: r268536

diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index a3c0002..ff847f8 100644 (file)
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,3 +1,12 @@
+2019-02-05  Jonathan Wakely  <jwakely@redhat.com>
+
+       PR libstdc++/89090
+       * include/bits/stl_uninitialized.h (__relocate_a_1): Make unused
+       parameter unnamed. Add message to static assertion.
+       * include/bits/vector.tcc (vector::reserve, vector::_M_realloc_insert)
+       (vector::_M_default_append): Use _GLIBCXX17_CONSTEXPR for if constexpr
+       in C++11 code.
+
 2019-02-05  Marc Glisse  <marc.glisse@inria.fr>
 
        PR libstdc++/87106

diff --git a/libstdc++-v3/include/bits/stl_uninitialized.h b/libstdc++-v3/include/bits/stl_uninitialized.h
index 03ed16b..0d42b25 100644 (file)
--- a/libstdc++-v3/include/bits/stl_uninitialized.h
+++ b/libstdc++-v3/include/bits/stl_uninitialized.h
@@ -904,7 +904,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
   template <typename _Tp, typename _Up>
     inline __enable_if_t<std::__is_bitwise_relocatable<_Tp>::value, _Tp*>
     __relocate_a_1(_Tp* __first, _Tp* __last,
-                  _Tp* __result, allocator<_Up>& __alloc) noexcept
+                  _Tp* __result, allocator<_Up>&) noexcept
     {
       ptrdiff_t __count = __last - __first;
       if (__count > 0)
@@ -925,7 +925,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
        _ValueType;
       typedef typename iterator_traits<_ForwardIterator>::value_type
        _ValueType2;
-      static_assert(std::is_same<_ValueType, _ValueType2>::value);
+      static_assert(std::is_same<_ValueType, _ValueType2>::value,
+         "relocation is only possible for values of the same type");
       _ForwardIterator __cur = __result;
       for (; __first != __last; ++__first, (void)++__cur)
        std::__relocate_object_a(std::__addressof(*__cur),

diff --git a/libstdc++-v3/include/bits/vector.tcc b/libstdc++-v3/include/bits/vector.tcc
index 4cf0e80..54c0977 100644 (file)
--- a/libstdc++-v3/include/bits/vector.tcc
+++ b/libstdc++-v3/include/bits/vector.tcc
@@ -73,7 +73,7 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
          const size_type __old_size = size();
          pointer __tmp;
 #if __cplusplus >= 201103L
-         if constexpr (_S_use_relocate())
+         if _GLIBCXX17_CONSTEXPR (_S_use_relocate())
            {
              __tmp = this->_M_allocate(__n);
              std::__relocate_a(this->_M_impl._M_start,
@@ -457,7 +457,7 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
          __new_finish = pointer();
 
 #if __cplusplus >= 201103L
-         if constexpr (_S_use_relocate())
+         if _GLIBCXX17_CONSTEXPR (_S_use_relocate())
            {
              __new_finish
                = std::__relocate_a
@@ -498,7 +498,7 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
          __throw_exception_again;
        }
 #if __cplusplus >= 201103L
-      if constexpr (!_S_use_relocate())
+      if _GLIBCXX17_CONSTEXPR (!_S_use_relocate())
 #endif
        std::_Destroy(__old_start, __old_finish, _M_get_Tp_allocator());
       _GLIBCXX_ASAN_ANNOTATE_REINIT;
@@ -638,8 +638,7 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
              const size_type __len =
                _M_check_len(__n, "vector::_M_default_append");
              pointer __new_start(this->_M_allocate(__len));
-#if __cplusplus >= 201103L
-             if constexpr (_S_use_relocate())
+             if _GLIBCXX17_CONSTEXPR (_S_use_relocate())
                {
                  __try
                    {
@@ -656,7 +655,6 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
                                    __new_start, _M_get_Tp_allocator());
                }
              else
-#endif
                {
                  pointer __destroy_from = pointer();
                  __try