fix analyzer exception 'Syntax node is not within syntax tree' (#307)

During orchestration method analysis, since the syntax tree of the callee method might be different from the caller method, we need to get the correct semantic model when they differ.

src/Analyzers/Orchestration/OrchestrationAnalyzer.cs

@@ -316,7 +316,12 @@ void FindInvokedMethods(
             IEnumerable<MethodDeclarationSyntax> calleeSyntaxes = calleeMethodSymbol.GetSyntaxNodes();
             foreach (MethodDeclarationSyntax calleeSyntax in calleeSyntaxes)
             {
-                this.FindInvokedMethods(semanticModel, calleeSyntax, calleeMethodSymbol, rootOrchestration, reportDiagnostic);
+                // Since the syntax tree of the callee method might be different from the caller method, we need to get the correct semantic model,
+                // avoiding the exception 'Syntax node is not within syntax tree'.
+                SemanticModel sm = semanticModel.SyntaxTree == calleeSyntax.SyntaxTree ?
+                    semanticModel : semanticModel.Compilation.GetSemanticModel(calleeSyntax.SyntaxTree);
+
+                this.FindInvokedMethods(sm, calleeSyntax, calleeMethodSymbol, rootOrchestration, reportDiagnostic);
             }
         }
     }

test/Analyzers.Tests/Orchestration/DateTimeOrchestrationAnalyzerTests.cs

@@ -222,6 +222,32 @@ public class MyOrchestrator : ITaskOrchestrator
         await VerifyCS.VerifyDurableTaskAnalyzerAsync(code, expected);
     }
 
+    [Fact]
+    public async Task TaskOrchestratorUsingDifferentSyntaxTreesHasDiag()
+    {
+        string mainCode = Wrapper.WrapTaskOrchestrator(@"
+public class MyOrchestrator : TaskOrchestrator<string, DateTime>
+{
+    public override Task<DateTime> RunAsync(TaskOrchestrationContext context, string input)
+    {
+        var dependency = new Dependency();
+        return Task.FromResult(dependency.Method());
+    }
+}
+");
+        string codeInAnotherSyntaxTree = Wrapper.WrapTaskOrchestrator(@"
+public class Dependency{
+    public DateTime Method() => {|#0:DateTime.Now|};
+}
+");
+
+        void configureTest(VerifyCS.Test test) => test.TestState.Sources.Add(codeInAnotherSyntaxTree);
+
+        DiagnosticResult expected = BuildDiagnostic().WithLocation(0).WithArguments("Method", "System.DateTime.Now", "MyOrchestrator");
+
+        await VerifyCS.VerifyDurableTaskAnalyzerAsync(mainCode, configureTest, expected);
+    }
+
 
     [Fact]
     public async Task FuncOrchestratorWithLambdaHasDiag()

test/Analyzers.Tests/Verifiers/CSharpAnalyzerVerifier.Durable.cs

@@ -12,6 +12,11 @@ public static partial class CSharpAnalyzerVerifier<TAnalyzer>
 {
     /// <inheritdoc cref="AnalyzerVerifier{TAnalyzer, TTest, TVerifier}.VerifyAnalyzerAsync(string, DiagnosticResult[])"/>
     public static async Task VerifyDurableTaskAnalyzerAsync(string source, params DiagnosticResult[] expected)
+    {
+        await VerifyDurableTaskAnalyzerAsync(source, null, expected);
+    }
+
+    public static async Task VerifyDurableTaskAnalyzerAsync(string source, Action<Test>? configureTest = null, params DiagnosticResult[] expected)
     {
         Test test = new()
         {
@@ -24,6 +29,8 @@ public static async Task VerifyDurableTaskAnalyzerAsync(string source, params Di
 
         test.ExpectedDiagnostics.AddRange(expected);
 
+        configureTest?.Invoke(test);
+
         await test.RunAsync(CancellationToken.None);
     }
 }