From 878315aa95dd1425ea20d98716be16ff51854a7b Mon Sep 17 00:00:00 2001
From: Rick Poyner <rick.poyner@tri.global>
Date: Mon, 4 Apr 2016 19:41:57 -0400
Subject: [PATCH] Simulation.h: fix type-matching and const errors in
 templates.

 * simulate(5-arg): don't modify the passed options struct.
   * restore const to options arg, to get sim(4) a fighting chance.
 * simulate(4-arg): fix a typo that defeats template resolution.
---
 drake/systems/Simulation.h | 17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/drake/systems/Simulation.h b/drake/systems/Simulation.h
index f199faab94a1..38ff15941292 100644
--- a/drake/systems/Simulation.h
+++ b/drake/systems/Simulation.h
@@ -103,8 +103,9 @@ inline bool handle_realtime_factor(const TimePoint& wall_clock_start_time,
 template <typename System>
 void simulate(const System& sys, double ti, double tf,
               const typename System::template StateVector<double>& xi,
-              SimulationOptions& options) {
-  if (options.realtime_factor < 0.0) options.realtime_factor = 0.0;
+              const SimulationOptions& options) {
+  SimulationOptions my_options = options;
+  if (my_options.realtime_factor < 0.0) my_options.realtime_factor = 0.0;
 
   TimePoint start = TimeClock::now();
   typename System::template StateVector<double> x(xi), x1est, xdot0, xdot1;
@@ -117,15 +118,15 @@ void simulate(const System& sys, double ti, double tf,
   // Take steps from ti to tf.
   double t = ti;
   while (t < tf) {
-    if (!handle_realtime_factor(start, t, options.realtime_factor,
-                                options.timeout_seconds)) {
+    if (!handle_realtime_factor(start, t, my_options.realtime_factor,
+                                my_options.timeout_seconds)) {
       std::stringstream error_msg;
       error_msg
           << "The simulation is not keeping up with desired real-time factor. "
-          << "It is behind by more than " << options.timeout_seconds
+          << "It is behind by more than " << my_options.timeout_seconds
           << " (scaled) second at simulation time " << t;
 
-      if (options.warn_real_time_violation) {
+      if (my_options.warn_real_time_violation) {
         if (!rt_warning_printed) {
           std::cerr << "WARNING: " << error_msg.str() << std::endl;
           rt_warning_printed = true;  // Suppress future warnings.
@@ -134,7 +135,7 @@ void simulate(const System& sys, double ti, double tf,
         throw std::runtime_error(error_msg.str());
       }
     }
-    const double dt = (std::min)(options.initial_step_size, tf - t);
+    const double dt = (std::min)(my_options.initial_step_size, tf - t);
 
     // Output is at t0, x0, u0.
     y = sys.output(t, x, u);
@@ -162,7 +163,7 @@ void simulate(const System& sys, double ti, double tf,
  */
 template <typename System>
 void simulate(const System& sys, double t0, double tf,
-              const typename System::template StateVectorType<double>& x0) {
+              const typename System::template StateVector<double>& x0) {
   simulate(sys, t0, tf, x0, default_simulation_options);
 }