Analyzers throw exceptions when an orchestrator uses C# 8 local functions

[juunas11]

Description

Installing version 2.2.1 (or 2.2.0) of Microsoft.Azure.WebJobs.Extensions.DurableTask and by extension 0.2.1 of the Microsoft.Azure.WebJobs.Extensions.DurableTask.Analyzers caused our build to crash as we got warnings that the analyzer had ran into an exception (and we treat warnings as errors).
I made a small repro, and it seems to be due to us using C# 8 local functions in orchestrators.

Expected behavior

Analyzer gives warnings and errors that it is able to give.

Actual behavior

Warning when building the project:

Warning
AD0001
'Microsoft.Azure.WebJobs.Extensions.DurableTask.Analyzers.OrchestratorAnalyzer' threw an exception of type 'System.InvalidCastException' with message 'Unable to cast object of type 'Microsoft.CodeAnalysis.CSharp.Syntax.LocalFunctionStatementSyntax' to type 'Microsoft.CodeAnalysis.CSharp.Syntax.MethodDeclarationSyntax'.'.

Version 0.2.1 and 0.2.2 of the analyzers throw the same exception.

Relevant source code snippets

Modifying the "Hello world" orchestrator like this is enough to trigger the warning:

[FunctionName("TestOrchestrator")]
public static async Task<List<string>> RunOrchestrator(
    [OrchestrationTrigger] IDurableOrchestrationContext context)
{
    var outputs = new List<string>();

    async Task<string> CallAsync(string name)
    {
        return await context.CallActivityAsync<string>("TestOrchestrator_Hello", name);
    }

    outputs.Add(await CallAsync("Tokyo"));
    outputs.Add(await CallAsync("Seattle"));
    outputs.Add(await CallAsync("London"));

    return outputs;
}

Known workarounds

Downgraded the DurableTask extension to 2.1.1 and removed the analyzer.

App Details

• Durable Functions extension version (e.g. v1.8.3): 2.2.1
• Azure Functions runtime version (1.0 or 2.0): 3.0
• Programming language used: C#

[amdeel]

Hey @juunas11, thanks for letting me know about this issue. This will be fixed in the next analyzer release.

[amdeel]

Hey @juunas11, I just wanted to let you know that this fix is in the 0.2.3 analyzer release, which is available now if you reference this directly. It will also be added by default with the durable extension starting with the (upcoming) Durable 2.2.2 release.