Add minimal example to reproduce memory leak in pushforward

test/FirstDerivative/FunctionCallsWithResults.C

@@ -1,5 +1,6 @@
 // RUN: %cladclang %s -I%S/../../include -oFunctionCallsWithResults.out 2>&1 | FileCheck %s
 // RUN: ./FunctionCallsWithResults.out | FileCheck -check-prefix=CHECK-EXEC %s
+//CHECK-NOT: {{.*error|warning|note:.*}}
 
 #include "clad/Differentiator/Differentiator.h"
 
@@ -89,6 +90,7 @@ double sum_of_squares(double u, double v) {
 // CHECK-NEXT: }
 
 double fn1(double i, double j) {
+  const int __k = 5; // random constant declaration for testing
   double res = sum_of_squares(i, j);
   res += sum_of_squares(j, i);
   return res;
@@ -97,6 +99,8 @@ double fn1(double i, double j) {
 // CHECK: double fn1_darg0(double i, double j) {
 // CHECK-NEXT:     double _d_i = 1;
 // CHECK-NEXT:     double _d_j = 0;
+// CHECK-NEXT:     const int _d_k = 0;
+// CHECK-NEXT:     const int __k0 = 5;
 // CHECK-NEXT:     clad::ValueAndPushforward<double, double> _t0 = sum_of_squares_pushforward(i, j, _d_i, _d_j);
 // CHECK-NEXT:     double _d_res = _t0.pushforward;
 // CHECK-NEXT:     double res = _t0.value;