Add a warning when some exogenous are not used in the model

preprocessor/DynamicModel.cc

@@ -3585,6 +3585,19 @@ DynamicModel::findUnusedEndogenous()
   return unusedEndo;
 }
 
+set<int>
+DynamicModel::findUnusedExogenous()
+{
+  set<int> usedExo, unusedExo;
+  for (int i = 0; i < (int) equations.size(); i++)
+    equations[i]->collectVariables(eExogenous, usedExo);
+  set<int> allExo = symbol_table.getExogenous();
+  set_difference(allExo.begin(), allExo.end(),
+                 usedExo.begin(), usedExo.end(),
+                 inserter(unusedExo, unusedExo.begin()));
+  return unusedExo;
+}
+
 void
 DynamicModel::computeDerivIDs()
 {

preprocessor/DynamicModel.hh

@@ -224,6 +224,8 @@ public:
 
   //! Find endogenous variables not used in model
   set<int> findUnusedEndogenous();
+  //! Find exogenous variables not used in model
+  set<int> findUnusedExogenous();
 
   //! Copies a dynamic model (only the equations)
   /*! It assumes that the dynamic model given in argument has just been allocated */

preprocessor/ModFile.cc

@@ -286,6 +286,21 @@ ModFile::checkPass()
       cerr << ") also appear in the expressions defining the variance/covariance matrix of shocks; this is not allowed." << endl;
       exit(EXIT_FAILURE);
     }
+
+  // Check if some exogenous is not used in the model block
+  set<int> unusedExo = dynamic_model.findUnusedExogenous();
+  if (unusedExo.size() > 1)
+    {
+      warnings << "WARNING: some exogenous (";
+      for (set<int>::const_iterator it = unusedExo.begin();
+           it != unusedExo.end(); )
+        {
+          warnings << symbol_table.getName(*it);
+          if (++it != unusedExo.end())
+            warnings << ", ";
+        }
+      warnings << ") are declared but not used in the model. This may lead to crashes or unexpected behaviour." << endl;
+    }
 }
 
 void