Method ~EnvVarGuard

cpp/src/arrow/testing/gtest_util.cc:686–692

}

EnvVarGuard::~EnvVarGuard() {
  if (old_value_.has_value()) {
    ARROW_CHECK_OK(arrow::internal::SetEnvVar(name_, *old_value_));
  } else {
    ARROW_CHECK_OK(arrow::internal::DelEnvVar(name_));
  }
}

struct SignalHandlerGuard::Impl {
  int signum_;