From 1d4cd9b0aa290ef624d1689f47f2710d15e68dcc Mon Sep 17 00:00:00 2001
From: John Tramm <john.tramm@gmail.com>
Date: Tue, 28 Nov 2023 15:20:54 -0600
Subject: [PATCH] F90_NONE Removal (MGMC tallying optimization) (#2785)

---
 include/openmc/constants.h     | 1 -
 include/openmc/particle_data.h | 8 ++++----
 src/tallies/filter_energy.cpp  | 4 ++--
 3 files changed, 6 insertions(+), 7 deletions(-)

diff --git a/include/openmc/constants.h b/include/openmc/constants.h
index 2b9eaca2989..ba558b04089 100644
--- a/include/openmc/constants.h
+++ b/include/openmc/constants.h
@@ -317,7 +317,6 @@ enum class GlobalTally { K_COLLISION, K_ABSORPTION, K_TRACKLENGTH, LEAKAGE };
 
 // Miscellaneous
 constexpr int C_NONE {-1};
-constexpr int F90_NONE {0}; // TODO: replace usage of this with C_NONE
 
 // Interpolation rules
 enum class Interpolation {
diff --git a/include/openmc/particle_data.h b/include/openmc/particle_data.h
index ee34c305207..37eb05bdb04 100644
--- a/include/openmc/particle_data.h
+++ b/include/openmc/particle_data.h
@@ -257,10 +257,10 @@ class ParticleData {
   vector<int> cell_last_; //!< coordinates for all levels
 
   // Energy data
-  double E_;      //!< post-collision energy in eV
-  double E_last_; //!< pre-collision energy in eV
-  int g_ {0};     //!< post-collision energy group (MG only)
-  int g_last_;    //!< pre-collision energy group (MG only)
+  double E_;       //!< post-collision energy in eV
+  double E_last_;  //!< pre-collision energy in eV
+  int g_ {C_NONE}; //!< post-collision energy group (MG only)
+  int g_last_;     //!< pre-collision energy group (MG only)
 
   // Other physical data
   double wgt_ {1.0};       //!< particle weight
diff --git a/src/tallies/filter_energy.cpp b/src/tallies/filter_energy.cpp
index 48448cb1f05..825dd2ee571 100644
--- a/src/tallies/filter_energy.cpp
+++ b/src/tallies/filter_energy.cpp
@@ -59,7 +59,7 @@ void EnergyFilter::set_bins(gsl::span<const double> bins)
 void EnergyFilter::get_all_bins(
   const Particle& p, TallyEstimator estimator, FilterMatch& match) const
 {
-  if (p.g() != F90_NONE && matches_transport_groups_) {
+  if (p.g() != C_NONE && matches_transport_groups_) {
     if (estimator == TallyEstimator::TRACKLENGTH) {
       match.bins_.push_back(data::mg.num_energy_groups_ - p.g() - 1);
     } else {
@@ -98,7 +98,7 @@ std::string EnergyFilter::text_label(int bin) const
 void EnergyoutFilter::get_all_bins(
   const Particle& p, TallyEstimator estimator, FilterMatch& match) const
 {
-  if (p.g() != F90_NONE && matches_transport_groups_) {
+  if (p.g() != C_NONE && matches_transport_groups_) {
     match.bins_.push_back(data::mg.num_energy_groups_ - p.g() - 1);
     match.weights_.push_back(1.0);