Optimize code generated for diam and area.

src/neuron/cache/mechanism_range.hpp

@@ -22,7 +22,7 @@ void indices_to_cache(short type, Callable callable) {
         auto const sem = dparam_semantics[field];
         // See https://github.com/neuronsimulator/nrn/issues/2312 for discussion of possible
         // extensions to caching.
-        if ((sem > 0 && sem < 1000) || sem == -1 /* area */) {
+        if ((sem > 0 && sem < 1000) || sem == -1 /* area */ || sem == -9 /* diam */) {
             std::invoke(callable, field);
         }
     }

src/nmodl/nocpout.cpp

@@ -2496,15 +2496,15 @@ int iondef(int* p_pointercount) {
 
     if (diamdec) { /* must be last */
         Sprintf(buf,
-                "#define diam	*_ppvar[%d].get<double*>()\n",
+                "#define diam	(*(_ml->dptr_field<%d>(_iml)))\n",
                 ioncount + *p_pointercount + num_random_vars);
         q2 = lappendstr(defs_list, buf);
         q2->itemtype = VERBATIM;
     }              /* notice that ioncount is not incremented */
     if (areadec) { /* must be last, if we add any more the administrative
             procedures must be redone */
         Sprintf(buf,
-                "#define area	*_ppvar[%d].get<double*>()\n",
+                "#define area	(*(_ml->dptr_field<%d>(_iml)))\n",
                 ioncount + *p_pointercount + num_random_vars + diamdec);
         q2 = lappendstr(defs_list, buf);
         q2->itemtype = VERBATIM;

src/nrnoc/treeset.cpp

@@ -2367,7 +2367,7 @@ neuron::model_sorted_token nrn_ensure_model_data_are_sorted() {
         nrn_sort_node_data(node_token, cache);
         assert(node_data.is_sorted());
         // TODO: maybe we should separate out cache population from sorting.
-        std::size_t n{};  // eww
+        std::size_t n{};
         model.apply_to_mechanisms([&cache, &n, &mech_tokens](auto& mech_data) {
             // TODO do we need to pass `node_token` to `nrn_sort_mech_data`?
             nrn_sort_mech_data(mech_tokens[n], cache, mech_data);