Fix crash when changing automation mode for MIDI track control automation.

Also some work towards tolerating automation controls with no automation list,
towards actually doing something for these cases, though not required just to
fix this crash (MidiTrack::set_parameter_automation_state() avoids those
paths).

libs/ardour/ardour/midi_track.h

@@ -93,6 +93,8 @@ public:
 		MidiTrack* _route;
 	};
 
+	virtual void set_parameter_automation_state (Evoral::Parameter param, AutoState);
+
 	NoteMode note_mode() const { return _note_mode; }
 	void set_note_mode (NoteMode m);
 

libs/ardour/automatable.cc

@@ -137,16 +137,20 @@ Automatable::add_control(boost::shared_ptr<Evoral::Control> ac)
 	Evoral::Parameter param = ac->parameter();
 
 	boost::shared_ptr<AutomationList> al = boost::dynamic_pointer_cast<AutomationList> (ac->list ());
-	assert (al);
 
-	al->automation_state_changed.connect_same_thread (
-		_list_connections, boost::bind (&Automatable::automation_list_automation_state_changed, this, ac->parameter(), _1)
-		);
+	if (al) {
+		al->automation_state_changed.connect_same_thread (
+			_list_connections,
+			boost::bind (&Automatable::automation_list_automation_state_changed,
+			             this, ac->parameter(), _1));
+	}
 
 	ControlSet::add_control (ac);
 	_can_automate_list.insert (param);
 
-	automation_list_automation_state_changed (param, al->automation_state ()); // sync everything up
+	if (al) {
+		automation_list_automation_state_changed (param, al->automation_state ()); // sync everything up
+	}
 }
 
 string
@@ -394,6 +398,7 @@ Automatable::control_factory(const Evoral::Parameter& param)
 		MidiTrack* mt = dynamic_cast<MidiTrack*>(this);
 		if (mt) {
 			control = new MidiTrack::MidiControl(mt, param);
+			list.reset();  // No list, this is region "automation"
 		} else {
 			warning << "MidiCCAutomation for non-MidiTrack" << endl;
 		}

libs/ardour/automation_control.cc

@@ -85,7 +85,7 @@ AutomationControl::set_list (boost::shared_ptr<Evoral::ControlList> list)
 void
 AutomationControl::set_automation_state (AutoState as)
 {
-	if (as != alist()->automation_state()) {
+	if (_list && as != alist()->automation_state()) {
 
 		alist()->set_automation_state (as);
 

libs/ardour/midi_track.cc

@@ -622,6 +622,24 @@ MidiTrack::write_immediate_event(size_t size, const uint8_t* buf)
 	return (_immediate_events.write(0, type, size, buf) == size);
 }
 
+void
+MidiTrack::set_parameter_automation_state (Evoral::Parameter param, AutoState state)
+{
+	switch (param.type()) {
+	case MidiCCAutomation:
+	case MidiPgmChangeAutomation:
+	case MidiPitchBenderAutomation:
+	case MidiChannelPressureAutomation:
+	case MidiSystemExclusiveAutomation:
+		/* The track control for MIDI parameters is for immediate events to act
+		   as a control surface, write/touch for them is not currently
+		   supported. */
+		return;
+	default:
+		Automatable::set_parameter_automation_state(param, state);
+	}
+}
+
 void
 MidiTrack::MidiControl::set_value(double val)
 {

libs/evoral/src/ControlSet.cpp

@@ -45,9 +45,12 @@ ControlSet::add_control(boost::shared_ptr<Control> ac)
 
 	ac->ListMarkedDirty.connect_same_thread (_control_connections, boost::bind (&ControlSet::control_list_marked_dirty, this));
 
-	ac->list()->InterpolationChanged.connect_same_thread (
-		_list_connections, boost::bind (&ControlSet::control_list_interpolation_changed, this, ac->parameter(), _1)
-	                                                      );
+	if (ac->list()) {
+		ac->list()->InterpolationChanged.connect_same_thread (
+			_list_connections,
+			boost::bind (&ControlSet::control_list_interpolation_changed,
+			             this, ac->parameter(), _1));
+	}
 }
 
 void
@@ -95,6 +98,9 @@ ControlSet::find_next_event (double now, double end, ControlEvent& next_event) c
 		ControlList::const_iterator i;
 		boost::shared_ptr<const ControlList> alist (li->second->list());
 		ControlEvent cp (now, 0.0f);
+		if (!alist) {
+			continue;
+		}
 
 		for (i = lower_bound (alist->begin(), alist->end(), &cp, ControlList::time_comparator);
 		     i != alist->end() && (*i)->when < end; ++i) {
@@ -121,8 +127,11 @@ ControlSet::clear_controls ()
 	_control_connections.drop_connections ();
 	_list_connections.drop_connections ();
 
-	for (Controls::iterator li = _controls.begin(); li != _controls.end(); ++li)
-		li->second->list()->clear();
+	for (Controls::iterator li = _controls.begin(); li != _controls.end(); ++li) {
+		if (li->second->list()) {
+			li->second->list()->clear();
+		}
+	}
 }
 
 } // namespace Evoral