libstdc++: Use RAII in std::vector::_M_realloc_insert

Replace the try-block with RAII types for deallocating storage and
destroying elements.

libstdc++-v3/ChangeLog:

	* include/bits/vector.tcc (_M_realloc_insert): Replace try-block
	with RAII types.

diff --git a/libstdc++-v3/include/bits/vector.tcc b/libstdc++-v3/include/bits/vector.tcc
index acd11e2dc68e73b29a8b8672647aaae8c24fe007..cda52fbbc4a1bf2dd63f5d00d7268ce933f31f0c 100644 (file)
--- a/libstdc++-v3/include/bits/vector.tcc
+++ b/libstdc++-v3/include/bits/vector.tcc
@@ -458,73 +458,109 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
     _M_realloc_insert(iterator __position, const _Tp& __x)
 #endif
     {
-      const size_type __len =
-       _M_check_len(size_type(1), "vector::_M_realloc_insert");
+      const size_type __len = _M_check_len(1u, "vector::_M_realloc_insert");
       pointer __old_start = this->_M_impl._M_start;
       pointer __old_finish = this->_M_impl._M_finish;
       const size_type __elems_before = __position - begin();
       pointer __new_start(this->_M_allocate(__len));
       pointer __new_finish(__new_start);
-      __try
+
+      // RAII guard for allocated storage.
+      struct _Guard
+      {
+       pointer _M_storage;         // Storage to deallocate
+       size_type _M_len;
+       _Tp_alloc_type& _M_alloc;
+
+       _GLIBCXX20_CONSTEXPR
+       _Guard(pointer __s, size_type __l, _Tp_alloc_type& __a)
+       : _M_storage(__s), _M_len(__l), _M_alloc(__a)
+       { }
+
+       _GLIBCXX20_CONSTEXPR
+       ~_Guard()
        {
-         // The order of the three operations is dictated by the C++11
-         // case, where the moves could alter a new element belonging
-         // to the existing vector.  This is an issue only for callers
-         // taking the element by lvalue ref (see last bullet of C++11
-         // [res.on.arguments]).
-         _Alloc_traits::construct(this->_M_impl,
-                                  __new_start + __elems_before,
+         if (_M_storage)
+           __gnu_cxx::__alloc_traits<_Tp_alloc_type>::
+             deallocate(_M_alloc, _M_storage, _M_len);
+       }
+
+      private:
+       _Guard(const _Guard&);
+      };
+      _Guard __guard(__new_start, __len, _M_impl);
+
+      // The order of the three operations is dictated by the C++11
+      // case, where the moves could alter a new element belonging
+      // to the existing vector.  This is an issue only for callers
+      // taking the element by lvalue ref (see last bullet of C++11
+      // [res.on.arguments]).
+
+      // If this throws, the existing elements are unchanged.
 #if __cplusplus >= 201103L
-                                  std::forward<_Args>(__args)...);
+      _Alloc_traits::construct(this->_M_impl,
+                              std::__to_address(__new_start + __elems_before),
+                              std::forward<_Args>(__args)...);
 #else
-                                  __x);
+      _Alloc_traits::construct(this->_M_impl,
+                              __new_start + __elems_before,
+                              __x);
 #endif
-         __new_finish = pointer();
 
 #if __cplusplus >= 201103L
-         if _GLIBCXX17_CONSTEXPR (_S_use_relocate())
-           {
-             __new_finish = _S_relocate(__old_start, __position.base(),
-                                        __new_start, _M_get_Tp_allocator());
+      if _GLIBCXX17_CONSTEXPR (_S_use_relocate())
+       {
+         // Relocation cannot throw.
+         __new_finish = _S_relocate(__old_start, __position.base(),
+                                    __new_start, _M_get_Tp_allocator());
+         ++__new_finish;
+         __new_finish = _S_relocate(__position.base(), __old_finish,
+                                    __new_finish, _M_get_Tp_allocator());
+       }
+      else
+#endif
+       {
+         // RAII type to destroy initialized elements.
+         struct _Guard_elts
+         {
+           pointer _M_first, _M_last;  // Elements to destroy
+           _Tp_alloc_type& _M_alloc;
 
-             ++__new_finish;
+           _GLIBCXX20_CONSTEXPR
+           _Guard_elts(pointer __elt, _Tp_alloc_type& __a)
+           : _M_first(__elt), _M_last(__elt + 1), _M_alloc(__a)
+           { }
 
-             __new_finish = _S_relocate(__position.base(), __old_finish,
-                                        __new_finish, _M_get_Tp_allocator());
-           }
-         else
-#endif
-           {
-             __new_finish
-               = std::__uninitialized_move_if_noexcept_a
-               (__old_start, __position.base(),
-                __new_start, _M_get_Tp_allocator());
+           _GLIBCXX20_CONSTEXPR
+           ~_Guard_elts()
+           { std::_Destroy(_M_first, _M_last, _M_alloc); }
 
-             ++__new_finish;
+         private:
+           _Guard_elts(const _Guard_elts&);
+         };
 
-             __new_finish
-               = std::__uninitialized_move_if_noexcept_a
-               (__position.base(), __old_finish,
-                __new_finish, _M_get_Tp_allocator());
-           }
-       }
-      __catch(...)
-       {
-         if (!__new_finish)
-           _Alloc_traits::destroy(this->_M_impl,
-                                  __new_start + __elems_before);
-         else
-           std::_Destroy(__new_start, __new_finish, _M_get_Tp_allocator());
-         _M_deallocate(__new_start, __len);
-         __throw_exception_again;
+         // Guard the new element so it will be destroyed if anything throws.
+         _Guard_elts __guard_elts(__new_start + __elems_before, _M_impl);
+
+         __new_finish = std::__uninitialized_move_if_noexcept_a(
+                          __old_start, __position.base(),
+                          __new_start, _M_get_Tp_allocator());
+
+         ++__new_finish;
+         // Guard everything before the new element too.
+         __guard_elts._M_first = __new_start;
+
+         __new_finish = std::__uninitialized_move_if_noexcept_a(
+                           __position.base(), __old_finish,
+                           __new_finish, _M_get_Tp_allocator());
+
+         // New storage has been fully initialized, destroy the old elements.
+         __guard_elts._M_first = __old_start;
+         __guard_elts._M_last = __old_finish;
        }
-#if __cplusplus >= 201103L
-      if _GLIBCXX17_CONSTEXPR (!_S_use_relocate())
-#endif
-       std::_Destroy(__old_start, __old_finish, _M_get_Tp_allocator());
-      _GLIBCXX_ASAN_ANNOTATE_REINIT;
-      _M_deallocate(__old_start,
-                   this->_M_impl._M_end_of_storage - __old_start);
+      __guard._M_storage = __old_start;
+      __guard._M_len = this->_M_impl._M_end_of_storage - __old_start;
+
       this->_M_impl._M_start = __new_start;
       this->_M_impl._M_finish = __new_finish;
       this->_M_impl._M_end_of_storage = __new_start + __len;