A little question about the args to construct call graph

[cshezhang]

Description

I want to use CHA to construct the call graph, but the following args throw an exception.

Main.main(
        "-pp",
        "-cp", "target/test-classes/",
        "--input-classes", main,
        "-a", ThrowAnalysis.ID + "=exception:explicit",
        "-a", CFGBuilder.ID + "=exception:explicit;dump:true",
        "-a", "cg=algorithm:cha"
);

However, if cg=algorithm:cha is replaced with cg, Taie can work properly.

The main exception trace:

cfg finishes, elapsed time: 0.01s
cg starts ...
Exception in thread "main" java.lang.NullPointerException
	at java.base/java.util.ArrayDeque.addLast(ArrayDeque.java:303)
	at java.base/java.util.ArrayDeque.add(ArrayDeque.java:494)
	at pascal.taie.analysis.graph.callgraph.CHABuilder.buildCallGraph(CHABuilder.java:70)
	at pascal.taie.analysis.graph.callgraph.CHABuilder.build(CHABuilder.java:61)
	at pascal.taie.analysis.graph.callgraph.CallGraphBuilder.analyze(CallGraphBuilder.java:64)
	at pascal.taie.analysis.graph.callgraph.CallGraphBuilder.analyze(CallGraphBuilder.java:37)
	at pascal.taie.analysis.AnalysisManager.runProgramAnalysis(AnalysisManager.java:148)
	at pascal.taie.analysis.AnalysisManager.runAnalysis(AnalysisManager.java:135)
	at pascal.taie.analysis.AnalysisManager.lambda$execute$0(AnalysisManager.java:104)
	at pascal.taie.util.Timer.runAndCount(Timer.java:93)
	at pascal.taie.analysis.AnalysisManager.lambda$execute$1(AnalysisManager.java:103)
	at java.base/java.util.ArrayList.forEach(ArrayList.java:1511)
	at pascal.taie.analysis.AnalysisManager.execute(AnalysisManager.java:102)
	at pascal.taie.Main.executePlan(Main.java:152)
	at pascal.taie.Main.lambda$main$0(Main.java:60)
	at pascal.taie.util.Timer.lambda$runAndCount$0(Timer.java:112)
	at pascal.taie.util.Timer.runAndCount(Timer.java:93)
	at pascal.taie.util.Timer.runAndCount(Timer.java:111)
	at pascal.taie.util.Timer.runAndCount(Timer.java:107)
	at pascal.taie.Main.main(Main.java:51)

Could you please kindly spot the potential usage issue? Thank you!

[silverbullettt]

The problem is that you did not specify a main method.

When CHA builds a call graph, it needs to start with a main method (a.k.a. entry method), which can be specified by option -m. You can change --input-classes main to -m main (--input-classes only tells Tai-e the classes needed to loaded into the world, but not the main method).