Add support for C# 11 required members.

ICSharpCode.Decompiler.Tests/TestCases/Pretty/Records.cs

@@ -129,7 +129,8 @@ namespace ICSharpCode.Decompiler.Tests.TestCases.Pretty
 		}
 
 	}
-#if ROSLYN4
+
+#if CS100
 	internal class RecordStructs
 	{
 		public record struct Base(string A);
@@ -230,6 +231,9 @@ namespace ICSharpCode.Decompiler.Tests.TestCases.Pretty
 			}
 		}
 	}
+#endif
+#if CS110
+
 #endif
 }
 namespace System.Runtime.CompilerServices

ICSharpCode.Decompiler.Tests/TestCases/Pretty/Structs.cs

@@ -51,4 +51,28 @@ namespace ICSharpCode.Decompiler.Tests.TestCases.Pretty
 		}
 	}
 #endif
-}
+
+#if CS110
+	public struct StructWithRequiredMembers
+	{
+		public required string FirstName;
+		public required string LastName { get; set; }
+	}
+#endif
+}
+
+namespace System.Runtime.CompilerServices
+{
+	[AttributeUsage(AttributeTargets.All, AllowMultiple = true, Inherited = false)]
+	internal sealed class CompilerFeatureRequiredAttribute : Attribute
+	{
+		public CompilerFeatureRequiredAttribute(string featureName)
+		{
+		}
+	}
+
+	[AttributeUsage(AttributeTargets.Class | AttributeTargets.Struct | AttributeTargets.Property | AttributeTargets.Field, AllowMultiple = false, Inherited = false)]
+	internal sealed class RequiredMemberAttribute : Attribute
+	{
+	}
+}

ICSharpCode.Decompiler/CSharp/CSharpDecompiler.cs

@@ -1380,6 +1380,10 @@ namespace ICSharpCode.Decompiler.CSharp
 						}
 					}
 				}
+				if (settings.RequiredMembers)
+				{
+					RemoveAttribute(typeDecl, KnownAttribute.RequiredAttribute);
+				}
 				if (typeDecl.ClassType == ClassType.Enum)
 				{
 					switch (decompileRun.EnumValueDisplayMode)
@@ -1871,6 +1875,10 @@ namespace ICSharpCode.Decompiler.CSharp
 				typeSystemAstBuilder.UseSpecialConstants = !(field.DeclaringType.Equals(field.ReturnType) || isMathPIOrE);
 				var fieldDecl = typeSystemAstBuilder.ConvertEntity(field);
 				SetNewModifier(fieldDecl);
+				if (settings.RequiredMembers && RemoveAttribute(fieldDecl, KnownAttribute.RequiredAttribute))
+				{
+					fieldDecl.Modifiers |= Modifiers.Required;
+				}
 				if (settings.FixedBuffers && IsFixedField(field, out var elementType, out var elementCount))
 				{
 					var fixedFieldDecl = new FixedFieldDeclaration();
@@ -1983,6 +1991,10 @@ namespace ICSharpCode.Decompiler.CSharp
 					propertyDecl.Modifiers &= ~(Modifiers.New | Modifiers.Virtual);
 					propertyDecl.Modifiers |= Modifiers.Override;
 				}
+				if (settings.RequiredMembers && RemoveAttribute(propertyDecl, KnownAttribute.RequiredAttribute))
+				{
+					propertyDecl.Modifiers |= Modifiers.Required;
+				}
 				return propertyDecl;
 			}
 			catch (Exception innerException) when (!(innerException is OperationCanceledException || innerException is DecompilerException))

ICSharpCode.Decompiler/CSharp/Syntax/CSharpModifierToken.cs

@@ -67,7 +67,7 @@ namespace ICSharpCode.Decompiler.CSharp.Syntax
 			Modifiers.New,
 			Modifiers.Unsafe,
 			Modifiers.Abstract, Modifiers.Virtual, Modifiers.Sealed, Modifiers.Static, Modifiers.Override,
-			Modifiers.Readonly, Modifiers.Volatile,
+			Modifiers.Required, Modifiers.Readonly, Modifiers.Volatile,
 			Modifiers.Ref,
 			Modifiers.Extern, Modifiers.Partial, Modifiers.Const,
 			Modifiers.Async,
@@ -119,6 +119,8 @@ namespace ICSharpCode.Decompiler.CSharp.Syntax
 					return "async";
 				case Modifiers.Ref:
 					return "ref";
+				case Modifiers.Required:
+					return "required";
 				case Modifiers.Any:
 					// even though it's used for pattern matching only, 'any' needs to be in this list to be usable in the AST
 					return "any";
@@ -129,50 +131,7 @@ namespace ICSharpCode.Decompiler.CSharp.Syntax
 
 		public static int GetModifierLength(Modifiers modifier)
 		{
-			switch (modifier)
-			{
-				case Modifiers.Private:
-					return "private".Length;
-				case Modifiers.Internal:
-					return "internal".Length;
-				case Modifiers.Protected:
-					return "protected".Length;
-				case Modifiers.Public:
-					return "public".Length;
-				case Modifiers.Abstract:
-					return "abstract".Length;
-				case Modifiers.Virtual:
-					return "virtual".Length;
-				case Modifiers.Sealed:
-					return "sealed".Length;
-				case Modifiers.Static:
-					return "static".Length;
-				case Modifiers.Override:
-					return "override".Length;
-				case Modifiers.Readonly:
-					return "readonly".Length;
-				case Modifiers.Const:
-					return "const".Length;
-				case Modifiers.New:
-					return "new".Length;
-				case Modifiers.Partial:
-					return "partial".Length;
-				case Modifiers.Extern:
-					return "extern".Length;
-				case Modifiers.Volatile:
-					return "volatile".Length;
-				case Modifiers.Unsafe:
-					return "unsafe".Length;
-				case Modifiers.Async:
-					return "async".Length;
-				case Modifiers.Ref:
-					return "ref".Length;
-				case Modifiers.Any:
-					// even though it's used for pattern matching only, 'any' needs to be in this list to be usable in the AST
-					return "any".Length;
-				default:
-					throw new NotSupportedException("Invalid value for Modifiers");
-			}
+			return GetModifierName(modifier).Length;
 		}
 
 		public static Modifiers GetModifierValue(string modifier)
@@ -215,6 +174,8 @@ namespace ICSharpCode.Decompiler.CSharp.Syntax
 					return Modifiers.Async;
 				case "ref":
 					return Modifiers.Ref;
+				case "required":
+					return Modifiers.Required;
 				case "any":
 					// even though it's used for pattern matching only, 'any' needs to be in this list to be usable in the AST
 					return Modifiers.Any;

ICSharpCode.Decompiler/CSharp/Syntax/Modifiers.cs

@@ -55,6 +55,7 @@ namespace ICSharpCode.Decompiler.CSharp.Syntax
 		Unsafe = 0x8000,
 		Async = 0x10000,
 		Ref = 0x20000,
+		Required = 0x40000,
 
 		VisibilityMask = Private | Internal | Protected | Public,
 

ICSharpCode.Decompiler/DecompilerSettings.cs

@@ -151,12 +151,13 @@ namespace ICSharpCode.Decompiler
 			{
 				parameterNullCheck = false;
 				lifetimeAnnotations = false;
+				requiredMembers = false;
 			}
 		}
 
 		public CSharp.LanguageVersion GetMinimumRequiredVersion()
 		{
-			if (parameterNullCheck || lifetimeAnnotations)
+			if (parameterNullCheck || lifetimeAnnotations || requiredMembers)
 				return CSharp.LanguageVersion.CSharp11_0;
 			if (fileScopedNamespaces || recordStructs)
 				return CSharp.LanguageVersion.CSharp10_0;
@@ -356,6 +357,24 @@ namespace ICSharpCode.Decompiler
 			}
 		}
 
+		bool requiredMembers = true;
+
+		/// <summary>
+		/// Use C# 11 <c>required</c> modifier.
+		/// </summary>
+		[Category("C# 11.0 / VS 2022.4")]
+		[Description("DecompilerSettings.RequiredMembers")]
+		public bool RequiredMembers {
+			get { return requiredMembers; }
+			set {
+				if (requiredMembers != value)
+				{
+					requiredMembers = value;
+					OnPropertyChanged();
+				}
+			}
+		}
+
 		bool switchExpressions = true;
 
 		/// <summary>

ICSharpCode.Decompiler/TypeSystem/Implementation/KnownAttributes.cs

@@ -106,11 +106,14 @@ namespace ICSharpCode.Decompiler.TypeSystem
 		// C# 9 attributes:
 		NativeInteger,
 		PreserveBaseOverrides,
+
+		// C# 11 attributes:
+		RequiredAttribute,
 	}
 
 	public static class KnownAttributes
 	{
-		internal const int Count = (int)KnownAttribute.PreserveBaseOverrides + 1;
+		internal const int Count = (int)KnownAttribute.RequiredAttribute + 1;
 
 		static readonly TopLevelTypeName[] typeNames = new TopLevelTypeName[Count]{
 			default,
@@ -175,6 +178,8 @@ namespace ICSharpCode.Decompiler.TypeSystem
 			// C# 9 attributes:
 			new TopLevelTypeName("System.Runtime.CompilerServices", "NativeIntegerAttribute"),
 			new TopLevelTypeName("System.Runtime.CompilerServices", "PreserveBaseOverridesAttribute"),
+			// C# 11 attributes:
+			new TopLevelTypeName("System.Runtime.CompilerServices", "RequiredMemberAttribute"),
 		};
 
 		public static ref readonly TopLevelTypeName GetTypeName(this KnownAttribute attr)

ILSpy/Properties/Resources.Designer.cs

@@ -1226,6 +1226,15 @@ namespace ICSharpCode.ILSpy.Properties {
             }
         }
         
+        /// <summary>
+        ///   Looks up a localized string similar to Required members.
+        /// </summary>
+        public static string DecompilerSettings_RequiredMembers {
+            get {
+                return ResourceManager.GetString("DecompilerSettings.RequiredMembers", resourceCulture);
+            }
+        }
+        
         /// <summary>
         ///   Looks up a localized string similar to Separate local variable declarations and initializers (int x = 5; -&gt; int x; x = 5;), if possible.
         /// </summary>

ILSpy/Properties/Resources.resx

@@ -1054,4 +1054,7 @@ Do you want to continue?</value>
   <data name="_Window" xml:space="preserve">
     <value>_Window</value>
   </data>
+  <data name="DecompilerSettings.RequiredMembers" xml:space="preserve">
+    <value>Required members</value>
+  </data>
 </root>