some C++20 string cleaning

Source/driver/Castro.H

@@ -1,6 +1,8 @@
 #ifndef CASTRO_H
 #define CASTRO_H
 
+#include <format>
+
 #include <state_indices.H>
 
 // runtime parameters
@@ -1131,7 +1133,7 @@ public:
 ///
     bool oversubscribing() {    // NOLINT(readability-convert-member-functions-to-static)
 #ifdef AMREX_USE_GPU
-        return (amrex::MultiFab::queryMemUsage("AmrLevel_Level_" + std::to_string(level)) >=
+        return (amrex::MultiFab::queryMemUsage(std::format("AmrLevel_Level_{}", level)) >=
                 static_cast<Long>(amrex::Gpu::Device::totalGlobalMem()));
 #else
         return false;

Source/driver/Castro.cpp

@@ -12,6 +12,7 @@
 #include <ctime>
 #include <memory>
 #include <numbers>
+#include <format>
 
 #include <AMReX_Utility.H>
 #include <AMReX_CONSTANTS.H>
@@ -693,7 +694,7 @@ Castro::Castro (Amr&            papa,
 {
     BL_PROFILE("Castro::Castro()");
 
-    MultiFab::RegionTag amrlevel_tag("AmrLevel_Level_" + std::to_string(lev));
+    MultiFab::RegionTag amrlevel_tag(std::format("AmrLevel_Level_{}", lev));
 
     buildMetrics();
 
@@ -3475,8 +3476,8 @@ Castro::allocOldData ()
 {
     BL_PROFILE("Castro::allocOldData");
 
-    MultiFab::RegionTag amrlevel_tag("AmrLevel_Level_" + std::to_string(level));
-    MultiFab::RegionTag statedata_tag("StateData_Level_" + std::to_string(level));
+    MultiFab::RegionTag amrlevel_tag(std::format("AmrLevel_Level_{}", level));
+    MultiFab::RegionTag statedata_tag(std::format("StateData_Level_{}", level));
     for (int k = 0; k < num_state_type; k++) {
         state[k].allocOldData();
     }
@@ -4240,8 +4241,8 @@ Castro::swap_state_time_levels(const Real dt)
 
     BL_PROFILE("Castro::swap_state_time_levels()");
 
-    MultiFab::RegionTag statedata_tag("StateData_Level_" + std::to_string(level));
-    MultiFab::RegionTag amrlevel_tag("AmrLevel_Level_" + std::to_string(level));
+    MultiFab::RegionTag statedata_tag(std::format("StateData_Level_{}", level));
+    MultiFab::RegionTag amrlevel_tag(std::format("AmrLevel_Level_{}", level));
 
     for (int k = 0; k < num_state_type; k++) {
 

Source/driver/Castro_advance.cpp

@@ -11,6 +11,7 @@
 
 #include <cmath>
 #include <climits>
+#include <format>
 
 #include <problem_initialize_state_data.H>
 
@@ -48,7 +49,7 @@ Castro::advance (Real time,
 
     wall_time_start = ParallelDescriptor::second();
 
-    MultiFab::RegionTag amrlevel_tag("AmrLevel_Level_" + std::to_string(level));
+    MultiFab::RegionTag amrlevel_tag(std::format("AmrLevel_Level_{}", level));
 
     Real dt_new = dt;
 

Source/driver/Castro_io.cpp

@@ -5,6 +5,7 @@
 
 #include <iomanip>
 #include <iostream>
+#include <format>
 #include <string>
 #include <ctime>
 
@@ -1096,7 +1097,7 @@ Castro::plotFileOutput(const std::string& dir,
             const DeriveRec* rec = derive_lst.get(name);
             if (rec->numDerive() > 1) {
                 for (int i = 0; i < rec->numDerive(); ++i) {
-                    os << rec->variableName(0) + '_' + std::to_string(i) + '\n';
+                    os << std::format("{}_{}\n", rec->variableName(0), i);
                 }
             }
             else {
@@ -1171,12 +1172,12 @@ Castro::plotFileOutput(const std::string& dir,
     // The name is relative to the directory containing the Header file.
     //
     static const std::string BaseName = "/Cell";
-    std::string Level = "Level_" + std::to_string(level);
+    std::string Level = std::format("Level_{}", level);
     //
     // Now for the full pathname of that directory.
     //
     std::string FullPath = dir;
-    if (!FullPath.empty() && FullPath[FullPath.size()-1] != '/') {
+    if (!FullPath.ends_with('/')) {
       FullPath += '/';
     }
     FullPath += Level;

Source/driver/Castro_setup.cpp

@@ -1,6 +1,7 @@
 #include <cstdio>
 
 #include <array>
+#include <format>
 
 #include <AMReX_LevelBld.H>
 #include <AMReX_ParmParse.H>
@@ -493,7 +494,7 @@ Castro::variableSetUp ()
     {
       set_scalar_bc(bc, phys_bc);
       bcs[UFA+i] = bc;
-      name[UFA+i] = "adv_" + std::to_string(i);
+      name[UFA+i] = std::format("adv_{}", i);
     }
 
 
@@ -642,7 +643,7 @@ Castro::variableSetUp ()
       }
       else if (castro::time_integration_method == SimplifiedSpectralDeferredCorrections) {
           for (int n = 0; n < sdc_iters+1; n++) {
-              burn_weight_names.emplace_back("burn_weights_iter_" + std::to_string(n+1));
+              burn_weight_names.emplace_back(std::format("burn_weights_iter_{}", n + 1));
           }
       }
   }
@@ -655,7 +656,7 @@ Castro::variableSetUp ()
           replace_inflow_bc(bc);
 
           desc_lst.setComponent(Simplified_SDC_React_Type, i,
-                                "sdc_react_source_" + std::to_string(i),
+                                std::format("sdc_react_source_{}", i),
                                 bc, genericBndryFunc);
       }
   }
@@ -682,7 +683,7 @@ Castro::variableSetUp ()
   }
   else {
       for (int i = 0; i < Radiation::nGroups; i++) {
-        rad_name = "rad" + std::to_string(i);
+        rad_name = std::format("rad{}", i);
         desc_lst
           .setComponent(Rad_Type, i, rad_name, bc,
                         genericBndryFunc);