+ signal_bubble_rebuild.emit();
+}
+
+void Target::prepare()
+{
+ if(state>PREPARING)
+ return;
+ if(state==PREPARING)
+ {
+ builder.get_logger().log("problems", format("Dependency cycle detected at %s", name));
+ problems.push_back("Dependency cycle detected");
+ state = BROKEN;
+ return;
+ }
+
+ state = PREPARING;
+ if(tool)
+ tool->prepare();
+
+ find_dependencies();
+ bool broken = !problems.empty();
+
+ if(tool)
+ {
+ if(FileTarget *tool_exe = tool->get_executable())
+ add_dependency(*tool_exe);
+ broken |= !tool->get_problems().empty();
+
+ // Only check package and component problems for buildable targets
+ // XXX How to propagate nested package problems?
+ broken |= (package && !package->get_problems().empty());
+ broken |= (component && !component->get_problems().empty());
+ }
+
+ for(Target *d: depends)
+ {
+ d->prepare();
+ broken |= d->is_broken();
+ }
+ for(Target *d: trans_depends)
+ d->prepare();
+
+ check_rebuild();
+ if(broken)
+ state = BROKEN;
+ else if(state==PREPARING)
+ state = UPTODATE;
+
+ for(Target *d: depends)
+ d->signal_bubble_rebuild.connect(sigc::mem_fun(this, &Target::check_rebuild));
+}
+
+Task *Target::build()