Roslyn Analyzer to detect calls to non-existent functions fails, when Activity function defined in other assembly than orchestrator

[piotrczerwinski-insert]

The Roslyn analyzer introduced in version 1.12.1 incorrectly reports warning DURABLE2003 when an activity function is defined in a separate assembly from the orchestrator, even though the function is correctly defined and works at runtime.

Package Version
• Working version: Microsoft.Azure.Functions.Worker.Extensions.DurableTask 1.12.0
• Affected version: Microsoft.Azure.Functions.Worker.Extensions.DurableTask 1.12.1

Expected Behavior

No warning should be raised when an activity function is correctly defined in a referenced assembly. The analyzer should be able to detect activity functions across assembly boundaries.

Actual Behavior

The analyzer emits the following warning:

DurableOrchestrator\Function1.cs(23,27,23,88): warning DURABLE2003: The activity function 'SayHello' was not found in the current compilation. Ensure the activity is defined and the name matches exactly.

Steps to Reproduce

1. Create a new Azure Function project from the standard template with Orchestrator function
2. Create a separate class library project (e.g., ActivityFunctions)
3. Move the SayHello activity function to the separate assembly
4. Add a project reference from the orchestrator project to the ActivityFunctions project
5. Update Microsoft.Azure.Functions.Worker.Extensions.DurableTask to version 1.12.1

[YunchuWang]

thanks for reporting the issue! #584
This diagnostic was downgraded to Info because Durable Functions allow activity/orchestrator declarations to exist in external assemblies. Since static analyzers cannot reliably resolve cross-assembly bindings, cases where a function is intentionally defined in another project may trigger this diagnostic. It can be safely ignored in such cases (this will be indicated in diagnostic message)