Fix #737 (pruning in fallback stages with a connect stage) (#742)

* Add unit test for #737
* Consider pruning property in Connect stage
   Even if pruning was disabled, pruning could sneak in via the Connect stage.
* Shift definition of pruning property's default
   Previously, it was explicitly disabled in Task's constructor.
   Child containers inherited the setting from their parent, i.e. ultimately the task.
   However, this meant that the property remained undefined for standalone containers.
   Now, the default value is declared in each container.
   Additionally, the property is still inherited from the parent.
* Reenable state before passing it to Fallbacks child - fixing the pruning problem

Author: rhaschke

core/src/container.cpp

@@ -327,7 +327,7 @@ void ContainerBasePrivate::liftSolution(const SolutionBasePtr& solution, const I
 
 ContainerBase::ContainerBase(ContainerBasePrivate* impl) : Stage(impl) {
 	auto& p = properties();
-	p.declare<bool>("pruning", std::string("enable pruning?")).configureInitFrom(Stage::PARENT, "pruning");
+	p.declare<bool>("pruning", false, std::string("enable pruning?")).configureInitFrom(Stage::PARENT, "pruning");
 }
 
 size_t ContainerBase::numChildren() const {
@@ -1029,6 +1029,11 @@ bool FallbacksPrivatePropagator::nextJob() {
 	}
 
 	// When arriving here, we have a valid job_ and a current_ child to feed it. Let's do that.
+	if (dir_ == Interface::FORWARD)
+		setStatus<Interface::BACKWARD>(nullptr, nullptr, &*job_, InterfaceState::Status::ENABLED);
+	else
+		setStatus<Interface::FORWARD>(nullptr, nullptr, &*job_, InterfaceState::Status::ENABLED);
+
 	copyState(dir_, job_, (*current_)->pimpl()->pullInterface(dir_), Interface::UpdateFlags());
 	return true;
 }

core/src/stage.cpp

@@ -820,7 +820,7 @@ void ConnectingPrivate::newState(Interface::iterator it, Interface::UpdateFlags
 		for (Interface::iterator oit : oit_to_enable)
 			parent_pimpl->setStatus<opposite<dir>()>(me(), &*it, &*oit, InterfaceState::Status::ENABLED);
 
-		if (!have_enabled_opposites)  // prune new state and associated branch if necessary
+		if (!have_enabled_opposites && parent()->pruning())  // prune new state and associated branch if necessary
 			// pass creator=nullptr to skip hasPendingOpposites() check as we did this here already
 			parent_pimpl->setStatus<dir>(nullptr, nullptr, &*it, InterfaceState::Status::ARMED);
 	}

core/src/task.cpp

@@ -94,7 +94,6 @@ const ContainerBase* TaskPrivate::stages() const {
 
 Task::Task(const std::string& ns, bool introspection, ContainerBase::pointer&& container)
   : WrapperBase(new TaskPrivate(this, ns), std::move(container)) {
-	setPruning(false);
 	setTimeout(std::numeric_limits<double>::max());
 
 	// monitor state on commandline

core/test/test_fallback.cpp

@@ -195,3 +195,19 @@ TEST_F(FallbacksFixtureConnect, connectStageInsideFallbacks) {
 	EXPECT_TRUE(t.plan());
 	EXPECT_COSTS(t.solutions(), testing::ElementsAre(11, 12, 22, 121));
 }
+
+TEST_F(FallbacksFixtureConnect, connectInsideSerialInsideFallbacks) {
+	t.add(std::make_unique<GeneratorMockup>(PredefinedCosts({ 0.0 })));
+	auto fallbacks = std::make_unique<Fallbacks>("Fallbacks");
+	auto serial = std::make_unique<SerialContainer>("Serial1");
+	serial->add(std::make_unique<ForwardMockup>(PredefinedCosts::constant(0.0)));
+	serial->add(std::make_unique<ConnectMockup>(PredefinedCosts::constant(1.0)));
+	serial->add(std::make_unique<BackwardMockup>(PredefinedCosts::constant(INF)));
+	serial->add(std::make_unique<GeneratorMockup>(PredefinedCosts::single(2.0)));
+	fallbacks->add(std::move(serial));
+	fallbacks->add(std::make_unique<ForwardMockup>(PredefinedCosts::constant(4.0)));
+
+	t.add(std::move(fallbacks));
+	EXPECT_TRUE(t.plan());
+	EXPECT_COSTS(t.solutions(), testing::ElementsAre(4.0));
+}