message: XPath: Workaround Coverity false positive
  Coverity hits a similar false positive to what clang static analyzer hit
  it assumes that since optimize() checks _right for being nullptr,
  optimize_self() might hit _right=nullptr in the ast_op_equal case which
  is impossible.
  Contributes to
diff: @@ -10922,7 +10922,7 @@ PUGI__NS_BEGIN
  // Use optimized path for @attr = 'value' or @attr = $value
  if (_type == ast_op_equal &&
  - _left && // workaround for clang static analyzer (_left is never null for ast_op_equal)
  + _left && _right && // workaround for clang static analyzer and Coverity (_left and _right are never null for ast_op_equal)
  _left->_type == ast_step && _left->_axis == axis_attribute && _left->_test == nodetest_name && !_left->_left && !_left->_right &&
  (_right->_type == ast_string_constant || (_right->_type == ast_variable && _right->_rettype == xpath_type_string)))
  {
  