Fix the case that there is a complex neuron model and a simple synaps…

…e model that does not transfer any variables (#1067)

* fix template in case of no transferred variables
---------

Co-authored-by: C.A.P. Linssen <charl@turingbirds.com>

pynestml/codegeneration/resources_nest/point_neuron/common/NeuronClass.jinja2

@@ -570,7 +570,7 @@ void {{neuronName}}::pre_run_hook()
 {%-         include "directives_cpp/GSLDifferentiationFunction.jinja2" %}
 {%-     endfor %}
 
-{%-     if paired_synapse is defined %}
+{%-     if paired_synapse is defined and (purely_numeric_state_variables_moved + analytic_state_variables_moved) | length > 0 %}
 {#          for neuron-synapse co-generation: separate integrator for the emulated integrate_odes() calls below in this template #}
 {%-         set args = utils.resolve_variables_to_expressions(astnode, purely_numeric_state_variables_moved + analytic_state_variables_moved) %}
 {%-         set ast = ASTNodeFactory.create_ast_function_call("integrate_odes", args) %}

pynestml/codegeneration/resources_nest/point_neuron/common/NeuronHeader.jinja2

@@ -120,9 +120,9 @@ namespace {{names_namespace}}
 }
 
 
-{% if uses_numeric_solver %}
+{%  if uses_numeric_solver %}
 
-{%- for s in utils.create_integrate_odes_combinations(astnode) %}
+{%-     for s in utils.create_integrate_odes_combinations(astnode) %}
 /**
  * Function computing right-hand side of ODE for GSL solver.
  * @note Must be declared here so we can befriend it in class.
@@ -136,9 +136,9 @@ namespace {{names_namespace}}
  * Integrate the variables: {{ s }}
 **/
 extern "C" inline int {{neuronName}}_dynamics{% if s | length > 0 %}_{{ s }}{% endif %}( double, const double ode_state[], double f[], void* pnode );
-{%- endfor %}
+{%-     endfor %}
 
-{%-     if paired_synapse is defined %}
+{%-     if paired_synapse is defined and (purely_numeric_state_variables_moved + analytic_state_variables_moved) | length > 0 %}
 {#  for neuron-synapse co-generation: separate integrator for the emulated/dummy integrate_odes() below in NeuronClass.jinja2 #}
 {%-         set args = utils.resolve_variables_to_expressions(astnode, purely_numeric_state_variables_moved + analytic_state_variables_moved) %}
 {%-         set ast = ASTNodeFactory.create_ast_function_call("integrate_odes", args) %}

pynestml/utils/ast_utils.py

@@ -1871,10 +1871,10 @@ def _visit(self, node):
         model.integrate_odes_combinations = visitor.all_args
 
         # always ensure code is generated for an integrate_odes() call without any arguments. This is needed, for example, for gap junctions support
-        if not [] in model.integrate_odes_combinations:
-            model.integrate_odes_combinations.append([])
+        if not "" in model.integrate_odes_combinations:
+            model.integrate_odes_combinations.append("")
 
-        return visitor.all_args
+        return model.integrate_odes_combinations
 
     @classmethod
     def get_all_integrate_odes_calls_unique(cls, model: ASTModel) -> None:

tests/nest_tests/test_co_generation_static_synapse.py

@@ -0,0 +1,50 @@
+# -*- coding: utf-8 -*-
+#
+# test_co_generation_static_synapse.py
+#
+# This file is part of NEST.
+#
+# Copyright (C) 2004 The NEST Initiative
+#
+# NEST is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 2 of the License, or
+# (at your option) any later version.
+#
+# NEST is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with NEST.  If not, see <http://www.gnu.org/licenses/>.
+
+import os
+
+from pynestml.codegeneration.nest_tools import NESTTools
+from pynestml.frontend.pynestml_frontend import generate_nest_target
+
+try:
+    import matplotlib
+    matplotlib.use("Agg")
+    import matplotlib.ticker
+    import matplotlib.pyplot as plt
+    TEST_PLOTS = True
+except Exception:
+    TEST_PLOTS = False
+
+
+def test_co_generation_static_synapse():
+    r"""This tests the case that there is a complex neuron model and a simple synapse model that does not transfer any variables."""
+
+    files = [os.path.join("models", "neurons", "hill_tononi_neuron.nestml"),
+             os.path.join("models", "synapses", "static_synapse.nestml")]
+    input_path = [os.path.realpath(os.path.join(os.path.dirname(__file__), os.path.join(
+        os.pardir, os.pardir, s))) for s in files]
+    generate_nest_target(input_path=input_path,
+                         logging_level="INFO",
+                         suffix="_nestml",
+                         codegen_opts={"neuron_synapse_pairs": [{"neuron": "hill_tononi_neuron",
+                                                                 "synapse": "static_synapse"}],
+                                       "delay_variable": {"static_synapse": "d"},
+                                       "weight_variable": {"static_synapse": "w"}})