From 75f0fd4d4c21452ef8612ac9dad03e76927f6712 Mon Sep 17 00:00:00 2001
From: AlekseyTs <AlekseyTs@users.noreply.github.com>
Date: Wed, 18 Dec 2024 15:03:59 -0800
Subject: [PATCH] Add a test

---
 .../Emit/CodeGen/CodeGenAsyncIteratorTests.cs | 39 +++++++++++++++++++
 1 file changed, 39 insertions(+)

diff --git a/src/Compilers/CSharp/Test/Emit/CodeGen/CodeGenAsyncIteratorTests.cs b/src/Compilers/CSharp/Test/Emit/CodeGen/CodeGenAsyncIteratorTests.cs
index c5cb4eeb9a3eb..d53a9fe93a818 100644
--- a/src/Compilers/CSharp/Test/Emit/CodeGen/CodeGenAsyncIteratorTests.cs
+++ b/src/Compilers/CSharp/Test/Emit/CodeGen/CodeGenAsyncIteratorTests.cs
@@ -10557,5 +10557,44 @@ public static async System.Collections.Generic.IAsyncEnumerator<string> Produce(
 """;
             CompileAndVerify(src, expectedOutput: ExpectedOutput("True one False null"), verify: Verification.Skipped, targetFramework: TargetFramework.Net80).VerifyDiagnostics();
         }
+
+        [Fact]
+        public void CompilerLoweringPreserveAttribute_01()
+        {
+            string source1 = @"
+using System;
+using System.Runtime.CompilerServices;
+
+[CompilerLoweringPreserve]
+[AttributeUsage(AttributeTargets.GenericParameter)]
+public class Preserve1Attribute : Attribute { }
+
+[AttributeUsage(AttributeTargets.GenericParameter)]
+public class Preserve2Attribute : Attribute { }
+";
+
+            string source2 = @"
+using System.Collections.Generic;
+using System.Threading.Tasks;
+
+class Test1
+{
+    async IAsyncEnumerable<T> M2<[Preserve1][Preserve2]T>(T x)
+    {
+        await Task.Yield();
+        yield return x;
+    }
+}
+";
+            var comp1 = CreateCompilation([source1, source2, CompilerLoweringPreserveAttributeDefinition], targetFramework: TargetFramework.Net80);
+            CompileAndVerify(comp1, symbolValidator: validate, verify: Verification.FailsPEVerify).VerifyDiagnostics();
+
+            static void validate(ModuleSymbol m)
+            {
+                AssertEx.SequenceEqual(
+                    ["Preserve1Attribute"],
+                    m.GlobalNamespace.GetMember<NamedTypeSymbol>("Test1.<M2>d__0").TypeParameters.Single().GetAttributes().Select(a => a.ToString()));
+            }
+        }
     }
 }