PR libstdc++/79254 simplify exception-safety in copy assignment

	PR libstdc++/79254
	* config/abi/pre/gnu.ver: Remove recently added symbols.
	* include/bits/basic_string.h [_GLIBCXX_USE_CXX11_ABI]
	(basic_string::_M_copy_assign): Remove.
	(basic_string::operator=(const basic_string&)): Don't dispatch to
	_M_copy_assign. If source object is small just deallocate, otherwise
	perform new allocation before making any changes.
	* include/bits/basic_string.tcc [_GLIBCXX_USE_CXX11_ABI]
	(basic_string::_M_copy_assign(const basic_string&, true_type)):
	Remove.
	* testsuite/21_strings/basic_string/allocator/char/copy_assign.cc:
	Test cases where the allocators are equal or the string is small.
	* testsuite/21_strings/basic_string/allocator/wchar_t/copy_assign.cc:
	Likewise.

From-SVN: r245085

1 files changed, 0 insertions, 64 deletions

diff --git a/libstdc++-v3/include/bits/basic_string.tcc b/libstdc++-v3/include/bits/basic_string.tcc
index adc8b853137..41b7fa196b0 100644
--- a/libstdc++-v3/include/bits/basic_string.tcc
+++ b/libstdc++-v3/include/bits/basic_string.tcc
@@ -275,70 +275,6 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	}
     }
 
-#if __cplusplus >= 201103L
-  template<typename _CharT, typename _Traits, typename _Alloc>
-    void
-    basic_string<_CharT, _Traits, _Alloc>::
-    _M_copy_assign(const basic_string& __str, true_type)
-    {
-      struct _Guard // RAII type for strong exception-safety guarantee.
-      {
-	// Takes ownership of string's original state.
-	_Guard(basic_string* __self)
-	: _M_self(__self), _M_alloc(std::move(__self->_M_get_allocator())),
-	  _M_ptr(__self->_M_data()),
-	  _M_capacity(__self->_M_allocated_capacity), _M_len(__self->length())
-	{
-	  __self->_M_data(__self->_M_local_data());
-	  __self->_M_length(0);
-	}
-
-	// Restores string's original state if _M_release() was not called.
-	~_Guard()
-	{
-	  if (_M_ptr)
-	    {
-	      _M_self->_M_get_allocator() = std::move(_M_alloc);
-	      _M_self->_M_data(_M_ptr);
-	      _M_self->_M_capacity(_M_capacity);
-	      _M_self->_M_length(_M_len);
-	    }
-	}
-
-	_Guard(const _Guard&) = delete;
-	_Guard& operator=(const _Guard&) = delete;
-
-	void _M_release()
-	{
-	  // Original state can be freed now.
-	  _Alloc_traits::deallocate(_M_alloc, _M_ptr, _M_capacity + 1);
-	  _M_ptr = nullptr;
-	}
-
-	basic_string*	_M_self;
-	allocator_type	_M_alloc;
-	pointer		_M_ptr;
-	size_type	_M_capacity;
-	size_type	_M_len;
-      };
-
-      if (!_Alloc_traits::_S_always_equal() && !_M_is_local()
-	  && _M_get_allocator() != __str._M_get_allocator())
-	{
-	  // The propagating allocator cannot free existing storage.
-	  _Guard __guard(this);
-	  _M_get_allocator() = __str._M_get_allocator();
-	  this->_M_assign(__str);
-	  __guard._M_release();
-	}
-      else
-	{
-	  _M_get_allocator() = __str._M_get_allocator();
-	  this->_M_assign(__str);
-	}
-    }
-#endif
-
   template<typename _CharT, typename _Traits, typename _Alloc>
     void
     basic_string<_CharT, _Traits, _Alloc>::