[mono-cecil] ArgumentNullException when calling FlowGraphFactory.CreateActionFlowGraph

[Philip_L]

Here's the stack trace:

System.ArgumentNullException: Value cannot be null.
Parameter name: then
   at
Cecil.FlowAnalysis.ActionFlow.ConditionalBranchActionBlock.SetTargets
(ActionBlock then, ActionBlock else_) in C:\Users\Phil\Desktop
\Development\cecil\flowanalysis\Cecil.FlowAnalysis\ActionFlow
\ConditionalBranchActionBlock.cs:line 74
   at
Cecil.FlowAnalysis.ActionFlow.ActionFlowGraphBuilder.ConnectActionBlocks
() in C:\Users\Phil\Desktop\Development\cecil\flowanalysis
\Cecil.FlowAnalysis\ActionFlow\ActionFlowGraphBuilder.cs:line 154
   at Cecil.FlowAnalysis.ActionFlow.ActionFlowGraphBuilder.Run() in C:
\Users\Phil\Desktop\Development\cecil\flowanalysis\Cecil.FlowAnalysis
\ActionFlow\ActionFlowGraphBuilder.cs:line 70
   at Cecil.FlowAnalysis.ActionFlow.ActionFlowGraphBuilder.BuildGraph
() in C:\Users\Phil\Desktop\Development\cecil\flowanalysis
\Cecil.FlowAnalysis\ActionFlow\ActionFlowGraphBuilder.cs:line 62
   at Cecil.FlowAnalysis.FlowGraphFactory.CreateActionFlowGraph
(ControlFlowGraph cfg) in C:\Users\Phil\Desktop\Development\cecil
\flowanalysis\Cecil.FlowAnalysis\FlowGraphFactory.cs:line 48
   at FlowAnalysis.Program.Main(String[] args) in C:\Users\Phil\Desktop
\Development\spikes\FlowAnalysis\FlowAnalysis\Program.cs:line 29


Here's the assembly that I opened using Cecil and Cecil.FlowAnalysis:


    public class Foo
    {
        public void DoSomething(bool someCondition)
        {
            if (someCondition)
            {
                Console.WriteLine("The condition is true");
            }
            else
            {
                Console.WriteLine("The condition is false");
            }
        }
    }

...and here's the client code that I used to make it crash:


    class Program
    {
        static void Main(string[] args)
        {
            var filename = typeof(Foo).Assembly.Location;
            var assembly = AssemblyFactory.GetAssembly(filename);
            var module = assembly.MainModule;
            var types = module.Types.Cast<TypeDefinition>();

            var fooType = types.Where(t => t.Name == "Foo").First();

            var methods = fooType.Methods.Cast<MethodDefinition>();
            var targetMethod = methods.First();

            try
            {
                var cfg = FlowGraphFactory.CreateControlFlowGraph
(targetMethod);

                // Cecil.FlowAnalysis crashes on the next line
                var afg = FlowGraphFactory.CreateActionFlowGraph(cfg);
            }
            catch(Exception ex)
            {

                var message = ex.ToString();
                Debug.WriteLine(message);
                throw;
            }


            return;
        }

Now is there something I'm doing wrong here and is there any way to
fix this or work around this?

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mono-cecil