C# 11 is no longer in preview.

ICSharpCode.Decompiler.Tests/Helpers/Tester.cs

@@ -365,10 +365,7 @@ namespace ICSharpCode.Decompiler.Tests.Helpers
 				{
 					preprocessorSymbols.Add("ROSLYN4");
 					preprocessorSymbols.Add("CS100");
-					if (flags.HasFlag(CompilerOptions.Preview))
-					{
-						preprocessorSymbols.Add("CS110");
-					}
+					preprocessorSymbols.Add("CS110");
 				}
 			}
 			else if ((flags & CompilerOptions.UseMcsMask) != 0)
@@ -582,7 +579,7 @@ namespace ICSharpCode.Decompiler.Tests.Helpers
 					CompilerOptions.UseRoslyn1_3_2 => CSharp.LanguageVersion.CSharp6,
 					CompilerOptions.UseRoslyn2_10_0 => CSharp.LanguageVersion.CSharp7_3,
 					CompilerOptions.UseRoslyn3_11_0 => CSharp.LanguageVersion.CSharp9_0,
-					_ => cscOptions.HasFlag(CompilerOptions.Preview) ? CSharp.LanguageVersion.Latest : CSharp.LanguageVersion.CSharp10_0,
+					_ => cscOptions.HasFlag(CompilerOptions.Preview) ? CSharp.LanguageVersion.Latest : CSharp.LanguageVersion.CSharp11_0,
 				};
 				DecompilerSettings settings = new(langVersion) {
 					// Never use file-scoped namespaces

ICSharpCode.Decompiler.Tests/PrettyTestRunner.cs

@@ -267,7 +267,7 @@ namespace ICSharpCode.Decompiler.Tests
 		[Test]
 		public async Task DelegateConstruction([ValueSource(nameof(defaultOptionsWithMcs))] CompilerOptions cscOptions)
 		{
-			await RunForLibrary(cscOptions: cscOptions | CompilerOptions.Preview);
+			await RunForLibrary(cscOptions: cscOptions);
 		}
 
 		[Test]
@@ -332,7 +332,7 @@ namespace ICSharpCode.Decompiler.Tests
 		[Test]
 		public async Task LocalFunctions([ValueSource(nameof(roslyn2OrNewerOptions))] CompilerOptions cscOptions)
 		{
-			await RunForLibrary(cscOptions: cscOptions | CompilerOptions.Preview);
+			await RunForLibrary(cscOptions: cscOptions);
 		}
 
 		[Test]
@@ -488,7 +488,7 @@ namespace ICSharpCode.Decompiler.Tests
 		[Test]
 		public async Task NativeInts([ValueSource(nameof(roslyn3OrNewerOptions))] CompilerOptions cscOptions)
 		{
-			await RunForLibrary(cscOptions: cscOptions | CompilerOptions.Preview);
+			await RunForLibrary(cscOptions: cscOptions);
 		}
 
 		[Test]
@@ -506,7 +506,7 @@ namespace ICSharpCode.Decompiler.Tests
 		[Test]
 		public async Task FunctionPointers([ValueSource(nameof(roslyn3OrNewerOptions))] CompilerOptions cscOptions)
 		{
-			await RunForLibrary(cscOptions: cscOptions | CompilerOptions.Preview);
+			await RunForLibrary(cscOptions: cscOptions);
 		}
 
 		[Test]
@@ -578,7 +578,7 @@ namespace ICSharpCode.Decompiler.Tests
 		[Test]
 		public async Task OptionalArguments([ValueSource(nameof(defaultOptions))] CompilerOptions cscOptions)
 		{
-			await RunForLibrary(cscOptions: cscOptions | CompilerOptions.Preview);
+			await RunForLibrary(cscOptions: cscOptions);
 		}
 
 		[Test]
@@ -602,11 +602,6 @@ namespace ICSharpCode.Decompiler.Tests
 		[Test]
 		public async Task CustomAttributes([ValueSource(nameof(defaultOptions))] CompilerOptions cscOptions)
 		{
-			if (cscOptions.HasFlag(CompilerOptions.UseRoslynLatest))
-			{
-				// Test C# 11 generic attributes
-				cscOptions |= CompilerOptions.Preview;
-			}
 			await RunForLibrary(cscOptions: cscOptions);
 		}
 
@@ -661,7 +656,7 @@ namespace ICSharpCode.Decompiler.Tests
 		[Test]
 		public async Task YieldReturn([ValueSource(nameof(defaultOptionsWithMcs))] CompilerOptions cscOptions)
 		{
-			await RunForLibrary(cscOptions: cscOptions | CompilerOptions.Preview);
+			await RunForLibrary(cscOptions: cscOptions);
 		}
 
 		[Test]
@@ -697,7 +692,7 @@ namespace ICSharpCode.Decompiler.Tests
 		[Test]
 		public async Task StaticAbstractInterfaceMembers([ValueSource(nameof(roslyn4OrNewerOptions))] CompilerOptions cscOptions)
 		{
-			await RunForLibrary(cscOptions: cscOptions | CompilerOptions.Preview);
+			await RunForLibrary(cscOptions: cscOptions);
 		}
 
 		[Test]