From ce5c62d04a48555267d44774024fc6f774e7e719 Mon Sep 17 00:00:00 2001
From: Sebastien Lebreton <sebastien@lebreton.fr>
Date: Tue, 2 Jun 2026 08:33:06 +0200
Subject: [PATCH] Fixes #471: CacheYieldInstructionAnalyzer threw AD0001
 (InvalidOperationException)

---
 .../CacheYieldInstructionAnalyzerTests.cs     | 25 +++++++++++++++++++
 .../CacheYieldInstructionAnalyzer.cs          |  6 ++++-
 2 files changed, 30 insertions(+), 1 deletion(-)

diff --git a/src/Microsoft.Unity.Analyzers.Tests/CacheYieldInstructionAnalyzerTests.cs b/src/Microsoft.Unity.Analyzers.Tests/CacheYieldInstructionAnalyzerTests.cs
index 5cff1c44..03671f60 100644
--- a/src/Microsoft.Unity.Analyzers.Tests/CacheYieldInstructionAnalyzerTests.cs
+++ b/src/Microsoft.Unity.Analyzers.Tests/CacheYieldInstructionAnalyzerTests.cs
@@ -226,6 +226,31 @@ IEnumerator Coroutine2()
 		await VerifyCSharpFixAsync(test, fixedTest);
 	}
 
+	[Fact]
+	public async Task NonUnityTypeWithMultipleLiteralArguments()
+	{
+		// See https://github.com/microsoft/Microsoft.Unity.Analyzers/issues/471
+		// The analyzer used to throw AD0001 (InvalidOperationException: Sequence contains more than one matching element)
+		// when a yield return expression created an object with more than one literal argument.
+		const string test = @"
+using System.Collections.Generic;
+
+public struct A
+{
+    public A(int a, int b)
+    {
+    }
+
+    public static IEnumerable<A> GetObjs()
+    {
+        yield return new A(23, 23);
+    }
+}
+";
+
+		await VerifyCSharpDiagnosticAsync(test);
+	}
+
 	[Fact]
 	public async Task WaitForSecondsAndRealtime()
 	{
diff --git a/src/Microsoft.Unity.Analyzers/CacheYieldInstructionAnalyzer.cs b/src/Microsoft.Unity.Analyzers/CacheYieldInstructionAnalyzer.cs
index b52171f2..1cdbfca6 100644
--- a/src/Microsoft.Unity.Analyzers/CacheYieldInstructionAnalyzer.cs
+++ b/src/Microsoft.Unity.Analyzers/CacheYieldInstructionAnalyzer.cs
@@ -56,7 +56,11 @@ private static void AnalyzeYieldReturn(SyntaxNodeAnalysisContext context)
 		if (yieldStatement.Expression is not ObjectCreationExpressionSyntax objectCreation)
 			return;
 
-		if (objectCreation.ArgumentList?.Arguments.SingleOrDefault(arg => arg.Expression is LiteralExpressionSyntax) == null)
+		// The code fix only supports caching when there's exactly one literal argument (see issue #471).
+		if (objectCreation.ArgumentList?.Arguments is not { Count: 1 } arguments)
+			return;
+
+		if (arguments[0].Expression is not LiteralExpressionSyntax)
 			return;
 
 		var typeSymbol = context.SemanticModel.GetTypeInfo(objectCreation).Type;