message: Qualify calls to isnan
  The C++ standard library is allowed to only put these into std:: and not in the
  global namespace. Some versions of GCC seem to be doing that, breaking the
  build. Just use the Eigen numext version consistenly.
diff: @@ -49,26 +49,28 @@ static ::testing::AssertionResult EqualFailure(const T& x, const T& y) {
  }
  static ::testing::AssertionResult IsEqual(float x, float y) {
  // We consider NaNs equal for testing.
  - if ((isnan(x) && isnan(y)) ||
  + if ((Eigen::numext::isnan(x) && Eigen::numext::isnan(y)) ||
  ::testing::internal::CmpHelperFloatingPointEQ<float>("", "", x, y))
  return ::testing::AssertionSuccess();
  return EqualFailure(x, y);
  }
  static ::testing::AssertionResult IsEqual(double x, double y) {
  // We consider NaNs equal for testing.
  - if ((isnan(x) && isnan(y)) ||
  + if ((Eigen::numext::isnan(x) && Eigen::numext::isnan(y)) ||
  ::testing::internal::CmpHelperFloatingPointEQ<double>("", "", x, y))
  return ::testing::AssertionSuccess();
  return EqualFailure(x, y);
  }
  static ::testing::AssertionResult IsEqual(Eigen::half x, Eigen::half y) {
  // We consider NaNs equal for testing.
  - if (isnan(x) && isnan(y)) return ::testing::AssertionSuccess();
  + if (Eigen::numext::isnan(x) && Eigen::numext::isnan(y))
  + return ::testing::AssertionSuccess();
  // Below is a reimplementation of CmpHelperFloatingPointEQ<Eigen::half>, which
  // we cannot use because Eigen::half is not default-constructible.
  - if (isnan(x) || isnan(y)) return EqualFailure(x, y);
  + if (Eigen::numext::isnan(x) || Eigen::numext::isnan(y))
  + return EqualFailure(x, y);
  auto sign_and_magnitude_to_biased = [](uint16_t sam) {
  const uint16_t kSignBitMask = 0x8000;
  @@ -115,7 +117,8 @@ template <typename T>
  static ::testing::AssertionResult IsClose(const T& x, const T& y, const T& atol,
  const T& rtol) {
  // We consider NaNs equal for testing.
  - if (isnan(x) && isnan(y)) return ::testing::AssertionSuccess();
  + if (Eigen::numext::isnan(x) && Eigen::numext::isnan(y))
  + return ::testing::AssertionSuccess();
  if (x == y) return ::testing::AssertionSuccess(); // Handle infinity.
  auto tolerance = atol + rtol * Eigen::numext::abs(x);
  if (Eigen::numext::abs(x - y) <= tolerance)
  