Disable via #if

To avoid breaking CanFindATypeForAllCsFiles test

Author: sbomer

src/tools/illink/test/ILLink.RoslynAnalyzer.Tests/DataFlowTests.cs

@@ -149,12 +149,11 @@ public Task EventDataFlow ()
 			return RunTest ();
 		}
 
-		// Disabled until we can use C# 14 in tests.
-		// [Fact]
-		// public Task ExtensionMembersDataFlow ()
-		// {
-		// 	return RunTest ();
-		// }
+		[Fact]
+		public Task ExtensionMembersDataFlow ()
+		{
+			return RunTest ();
+		}
 
 		[Fact]
 		public Task ExtensionsDataFlow ()

src/tools/illink/test/Mono.Linker.Tests.Cases/DataFlow/ExtensionMembersDataFlow.cs

@@ -18,6 +18,8 @@ public class ExtensionMembersDataFlow
 	{
 		public static void Main ()
 		{
+// This test is disabled until we can use C# 14 in tests.
+#if SUPPORTS_EXTENSION_MEMBERS
 			TestExtensionMethod ();
 			TestExtensionMethodMismatch ();
 			TestExtensionMethodRequires ();
@@ -277,6 +279,7 @@ public Type ExtensionMembersPropertyConflict {
 			// 	right.RequiresPublicMethods ();
 			// 	return ExtensionMembersDataFlow.GetWithMethods ();
 			// }
+#endif
 		}
 	}
 }

src/tools/illink/test/Mono.Linker.Tests.Cases/Mono.Linker.Tests.Cases.csproj

@@ -66,9 +66,4 @@
     <Compile Remove="TopLevelStatements/**/*" />
   </ItemGroup>
 
-  <ItemGroup>
-    <!-- This test is disabled until we can use C# 14 in tests. -->
-    <Compile Remove="DataFlow\ExtensionMembersDataFlow.cs" />
-  </ItemGroup>
-
 </Project>