public void check() {
		for (RuleStartState start : atn.ruleToStartState) {
			//System.out.print("check "+start.rule.name);
			rulesVisitedPerRuleCheck.clear();
			rulesVisitedPerRuleCheck.add(start);
			//FASerializer ser = new FASerializer(atn.g, start);
			//System.out.print(":\n"+ser+"\n");

			check(g.getRule(start.ruleIndex), start, new HashSet<ATNState>());
		}
		//System.out.println("cycles="+listOfRecursiveCycles);
		if ( !listOfRecursiveCycles.isEmpty() ) {
			g.tool.errMgr.leftRecursionCycles(g.fileName, listOfRecursiveCycles);
		}
	}
Which rule start states have we visited while looking for a single
	left-recursion check?
tool/src/org/antlr/v4/analysis/LeftRecursionDetector.java