Generated code produces warnings `CS0419` and `VSTHRD105` breaking builds with `TreatWarningsAsErrors`

[leandrodeopereira]

Description:

Summary

The DurableTaskSourceGenerator generates code in GeneratedDurableTaskExtensions.cs that produces compiler warnings CS0419 and VSTHRD105, which breaks builds when TreatWarningsAsErrors is enabled.

Environment

• Package: Microsoft.DurableTask.Generators v1.0.0-preview.1
• Target Framework: net10.0
• Azure Functions: v4
• Project Configuration: <TreatWarningsAsErrors>True</TreatWarningsAsErrors>
• Analyzers:
  • Microsoft.Extensions.StaticAnalysis v10.2.0
  • Standard Roslyn analyzers (C# compiler)

Reproduction

Full reproducible example available at: https://github.com/leandrodeopereira/azure-function-test

The project uses standard [DurableTask] attributes on orchestrators and activities , which triggers the source generator. Support class-based durable function invocations

Generated Code Issues

1. VSTHRD105 - Missing TaskScheduler parameter

// Generated in GeneratedDurableTaskExtensions.cs
return singletonSayHelloOrchestrator.RunAsync(context, context.GetInput<string>())
    .ContinueWith(t => (List<string>)(t.Result ?? default(List<string>)!), 
                  TaskContinuationOptions.ExecuteSynchronously);
    // ❌ Missing TaskScheduler parameter - assumes TaskScheduler.Current

Error:

VSTHRD105: Avoid method overloads that assume TaskScheduler.Current. 
Use an overload that accepts a TaskScheduler and specify TaskScheduler.Default explicitly.
https://microsoft.github.io/vs-threading/analyzers/VSTHRD105.html

2. CS0419 - Ambiguous cref in XML documentation

/// <inheritdoc cref="TaskOrchestrationContext.CallSubOrchestratorAsync"/>
public static Task<List<string>> CallSayHelloOrchestratorAsync(...)
// ❌ Ambiguous - multiple overloads match

Error:

CS0419: Ambiguous reference in cref attribute: 'TaskOrchestrationContext.CallSubOrchestratorAsync'. 
Assuming 'TaskOrchestrationContext.CallSubOrchestratorAsync(TaskName, TaskOptions)', 
but could have also matched other overloads.

Impact

Blocks usage of the generator in projects with TreatWarningsAsErrors enabled (standard for production code).

Current workarounds all compromise code quality:

• <NoWarn>CS0419;VSTHRD105</NoWarn> - Disables warnings

Expected Behavior

Generated code should compile cleanly with strict compiler settings and standard analyzers.

[YunchuWang]

thanks for reporting this issue! we are releasing a new version of source gen pkg this week which addresses the cref issue mentioned. as for VSTHRD105 issue,
Durable orchestrators run on a special task scheduler that handles replay correctly. Using TaskScheduler.Default forces the continuation to run on a different thread the thread pool, which can potentially:
Break replay semantics
Cause non-deterministic behavior
Lead to race conditions during replay
Add unnecessary context switch cost

i would suggest you disabling/ignore the taskscheduler rule