Keep compiler-generated code that is still referenced

ICSharpCode.Decompiler/CSharp/CSharpDecompiler.cs

@@ -1244,9 +1244,12 @@ EntityDeclaration DoDecompile(ITypeDefinition typeDef, DecompileRun decompileRun
 		{
 			Debug.Assert(decompilationContext.CurrentTypeDefinition == typeDef);
 			var watch = System.Diagnostics.Stopwatch.StartNew();
+			var entityMap = new MultiDictionary<IEntity, EntityDeclaration>();
+			var workList = new Queue<IEntity>();
+			TypeSystemAstBuilder typeSystemAstBuilder;
 			try
 			{
-				var typeSystemAstBuilder = CreateAstBuilder(decompileRun.Settings);
+				typeSystemAstBuilder = CreateAstBuilder(decompileRun.Settings);
 				var entityDecl = typeSystemAstBuilder.ConvertEntity(typeDef);
 				var typeDecl = entityDecl as TypeDeclaration;
 				if (typeDecl == null)
@@ -1289,16 +1292,6 @@ EntityDeclaration DoDecompile(ITypeDefinition typeDef, DecompileRun decompileRun
 					}
 				}
 
-				foreach (var type in typeDef.NestedTypes)
-				{
-					if (!type.MetadataToken.IsNil && !MemberIsHidden(module.PEFile, type.MetadataToken, settings))
-					{
-						var nestedType = DoDecompile(type, decompileRun, decompilationContext.WithCurrentTypeDefinition(type));
-						SetNewModifier(nestedType);
-						typeDecl.Members.Add(nestedType);
-					}
-				}
-
 				decompileRun.EnumValueDisplayMode = typeDef.Kind == TypeKind.Enum
 					? DetectBestEnumValueDisplayMode(typeDef, module.PEFile)
 					: null;
@@ -1309,60 +1302,38 @@ EntityDeclaration DoDecompile(ITypeDefinition typeDef, DecompileRun decompileRun
 
 				// For COM interop scenarios, the relative order of virtual functions/properties matters:
 				IEnumerable<IMember> allOrderedMembers = RequiresNativeOrdering(typeDef) ? GetMembersWithNativeOrdering(typeDef) :
-					fieldsAndProperties.Concat<IMember>(typeDef.Events).Concat<IMember>(typeDef.Methods);
+					fieldsAndProperties.Concat(typeDef.Events).Concat(typeDef.Methods);
+
+				var allOrderedEntities = typeDef.NestedTypes.Concat<IEntity>(allOrderedMembers);
 
-				foreach (var member in allOrderedMembers)
+				// Decompile members that are not compiler-generated.
+				foreach (var entity in allOrderedEntities)
 				{
-					if (member is IField || member is IProperty)
+					if (entity.MetadataToken.IsNil || MemberIsHidden(module.PEFile, entity.MetadataToken, settings))
 					{
-						var fieldOrProperty = member;
-						if (fieldOrProperty.MetadataToken.IsNil || MemberIsHidden(module.PEFile, fieldOrProperty.MetadataToken, settings))
-						{
-							continue;
-						}
-						if (fieldOrProperty is IField field)
-						{
-							if (typeDef.Kind == TypeKind.Enum && !field.IsConst)
-								continue;
-							var memberDecl = DoDecompile(field, decompileRun, decompilationContext.WithCurrentMember(field));
-							typeDecl.Members.Add(memberDecl);
-						}
-						else if (fieldOrProperty is IProperty property)
-						{
-							if (recordDecompiler?.PropertyIsGenerated(property) == true)
-							{
-								continue;
-							}
-							var propDecl = DoDecompile(property, decompileRun, decompilationContext.WithCurrentMember(property));
-							typeDecl.Members.Add(propDecl);
-						}
-					}
-					else if (member is IMethod method)
-					{
-						if (recordDecompiler?.MethodIsGenerated(method) == true)
-						{
-							continue;
-						}
-						if (!method.MetadataToken.IsNil && !MemberIsHidden(module.PEFile, method.MetadataToken, settings))
-						{
-							var memberDecl = DoDecompile(method, decompileRun, decompilationContext.WithCurrentMember(method));
-							typeDecl.Members.Add(memberDecl);
-							typeDecl.Members.AddRange(AddInterfaceImplHelpers(memberDecl, method, typeSystemAstBuilder));
-						}
-					}
-					else if (member is IEvent @event)
-					{
-						if ([email protected] && !MemberIsHidden(module.PEFile, @event.MetadataToken, settings))
-						{
-							var eventDecl = DoDecompile(@event, decompileRun, decompilationContext.WithCurrentMember(@event));
-							typeDecl.Members.Add(eventDecl);
-						}
+						continue;
 					}
-					else
+					DoDecompileMember(entity, recordDecompiler);
+				}
+
+				// Decompile compiler-generated members that are still needed.
+				while (workList.Count > 0)
+				{
+					var entity = workList.Dequeue();
+					if (entityMap.Contains(entity) || entity.MetadataToken.IsNil)
 					{
-						throw new ArgumentOutOfRangeException("Unexpected member type");
+						// Member is already decompiled.
+						continue;
 					}
+					DoDecompileMember(entity, recordDecompiler);
+				}
+
+				// Add all decompiled members to syntax tree in the correct order.
+				foreach (var member in allOrderedEntities)
+				{
+					typeDecl.Members.AddRange(entityMap[member]);
 				}
+
 				if (typeDecl.Members.OfType<IndexerDeclaration>().Any(idx => idx.PrivateImplementationType.IsNull))
 				{
 					// Remove the [DefaultMember] attribute if the class contains indexers
@@ -1421,6 +1392,69 @@ EntityDeclaration DoDecompile(ITypeDefinition typeDef, DecompileRun decompileRun
 				watch.Stop();
 				Instrumentation.DecompilerEventSource.Log.DoDecompileTypeDefinition(typeDef.FullName, watch.ElapsedMilliseconds);
 			}
+
+			void DoDecompileMember(IEntity entity, RecordDecompiler recordDecompiler)
+			{
+				EntityDeclaration entityDecl;
+				switch (entity)
+				{
+					case IField field:
+						if (typeDef.Kind == TypeKind.Enum && !field.IsConst)
+						{
+							return;
+						}
+						entityDecl = DoDecompile(field, decompileRun, decompilationContext.WithCurrentMember(field));
+						entityMap.Add(field, entityDecl);
+						break;
+					case IProperty property:
+						if (recordDecompiler?.PropertyIsGenerated(property) == true)
+						{
+							return;
+						}
+						entityDecl = DoDecompile(property, decompileRun, decompilationContext.WithCurrentMember(property));
+						entityMap.Add(property, entityDecl);
+						break;
+					case IMethod method:
+						if (recordDecompiler?.MethodIsGenerated(method) == true)
+						{
+							return;
+						}
+						entityDecl = DoDecompile(method, decompileRun, decompilationContext.WithCurrentMember(method));
+						entityMap.Add(method, entityDecl);
+						foreach (var helper in AddInterfaceImplHelpers(entityDecl, method, typeSystemAstBuilder))
+						{
+							entityMap.Add(method, helper);
+						}
+						break;
+					case IEvent @event:
+						entityDecl = DoDecompile(@event, decompileRun, decompilationContext.WithCurrentMember(@event));
+						entityMap.Add(@event, entityDecl);
+						break;
+					case ITypeDefinition type:
+						entityDecl = DoDecompile(type, decompileRun, decompilationContext.WithCurrentTypeDefinition(type));
+						SetNewModifier(entityDecl);
+						entityMap.Add(type, entityDecl);
+						break;
+					default:
+						throw new ArgumentOutOfRangeException("Unexpected member type");
+				}
+
+				foreach (var node in entityDecl.Descendants)
+				{
+					var rr = node.GetResolveResult();
+					if (rr is MemberResolveResult mrr
+						&& mrr.Member.DeclaringTypeDefinition == typeDef
+						&& !(mrr.Member is IMethod { IsLocalFunction: true }))
+					{
+						workList.Enqueue(mrr.Member);
+					}
+					else if (rr is TypeResolveResult trr
+						&& trr.Type.GetDefinition()?.DeclaringTypeDefinition == typeDef)
+					{
+						workList.Enqueue(trr.Type.GetDefinition());
+					}
+				}
+			}
 		}
 
 		EnumValueDisplayMode DetectBestEnumValueDisplayMode(ITypeDefinition typeDef, PEFile module)

ICSharpCode.Decompiler/CSharp/Transforms/PatternStatementTransform.cs

@@ -640,17 +640,19 @@ PropertyDeclaration TransformAutomaticProperty(PropertyDeclaration propertyDecla
 				propertyDeclaration.Modifiers &= ~Modifiers.Readonly;
 				propertyDeclaration.Getter.Modifiers &= ~Modifiers.Readonly;
 
-				// Add C# 7.3 attributes on backing field:
-				var attributes = field.GetAttributes()
-					.Where(a => !attributeTypesToRemoveFromAutoProperties.Contains(a.AttributeType.FullName))
-					.Select(context.TypeSystemAstBuilder.ConvertAttribute).ToArray();
-				if (attributes.Length > 0)
+				var fieldDecl = propertyDeclaration.Parent?.Children.OfType<FieldDeclaration>()
+					.FirstOrDefault(fd => field.Equals(fd.GetSymbol()));
+				if (fieldDecl != null)
 				{
-					var section = new AttributeSection {
-						AttributeTarget = "field"
-					};
-					section.Attributes.AddRange(attributes);
-					propertyDeclaration.Attributes.Add(section);
+					fieldDecl.Remove();
+					// Add C# 7.3 attributes on backing field:
+					CSharpDecompiler.RemoveAttribute(fieldDecl, KnownAttribute.CompilerGenerated);
+					CSharpDecompiler.RemoveAttribute(fieldDecl, KnownAttribute.DebuggerBrowsable);
+					foreach (var section in fieldDecl.Attributes)
+					{
+						section.AttributeTarget = "field";
+						propertyDeclaration.Attributes.Add(section.Detach());
+					}
 				}
 			}
 			// Since the property instance is not changed, we can continue in the visitor as usual, so return null
@@ -1010,23 +1012,17 @@ EventDeclaration TransformAutomaticEvents(CustomEventDeclaration ev)
 			ed.Variables.Add(new VariableInitializer(ev.Name));
 			ed.CopyAnnotationsFrom(ev);
 
-			if (ev.GetSymbol() is IEvent eventDef)
+			var fieldDecl = ev.Parent?.Children.OfType<FieldDeclaration>()
+				.FirstOrDefault(fd => fd.Variables.Single().Name == ev.Name);
+			if (fieldDecl != null)
 			{
-				IField field = eventDef.DeclaringType.GetFields(f => f.Name == ev.Name, GetMemberOptions.IgnoreInheritedMembers).SingleOrDefault();
-				if (field != null)
+				fieldDecl.Remove();
+				CSharpDecompiler.RemoveAttribute(fieldDecl, KnownAttribute.CompilerGenerated);
+				CSharpDecompiler.RemoveAttribute(fieldDecl, KnownAttribute.DebuggerBrowsable);
+				foreach (var section in fieldDecl.Attributes)
 				{
-					ed.AddAnnotation(field);
-					var attributes = field.GetAttributes()
-							.Where(a => !attributeTypesToRemoveFromAutoEvents.Contains(a.AttributeType.FullName))
-							.Select(context.TypeSystemAstBuilder.ConvertAttribute).ToArray();
-					if (attributes.Length > 0)
-					{
-						var section = new AttributeSection {
-							AttributeTarget = "field"
-						};
-						section.Attributes.AddRange(attributes);
-						ed.Attributes.Add(section);
-					}
+					section.AttributeTarget = "field";
+					ed.Attributes.Add(section.Detach());
 				}
 			}
 

ICSharpCode.Decompiler/TypeSystem/Implementation/KnownAttributes.cs

@@ -48,6 +48,7 @@ public enum KnownAttribute
 		SpecialName,
 		DebuggerHidden,
 		DebuggerStepThrough,
+		DebuggerBrowsable,
 
 		// Assembly attributes:
 		AssemblyVersion,
@@ -124,6 +125,7 @@ static class KnownAttributes
 			new TopLevelTypeName("System.Runtime.CompilerServices", nameof(SpecialNameAttribute)),
 			new TopLevelTypeName("System.Diagnostics", nameof(DebuggerHiddenAttribute)),
 			new TopLevelTypeName("System.Diagnostics", nameof(DebuggerStepThroughAttribute)),
+			new TopLevelTypeName("System.Diagnostics", nameof(DebuggerBrowsableAttribute)),
 			// Assembly attributes:
 			new TopLevelTypeName("System.Reflection", nameof(AssemblyVersionAttribute)),
 			new TopLevelTypeName("System.Runtime.CompilerServices", nameof(InternalsVisibleToAttribute)),

ICSharpCode.Decompiler/Util/MultiDictionary.cs

@@ -105,7 +105,7 @@ IEnumerable<TValue> ILookup<TKey, TValue>.this[TKey key] {
 			get { return this[key]; }
 		}
 
-		bool ILookup<TKey, TValue>.Contains(TKey key)
+		public bool Contains(TKey key)
 		{
 			return dict.ContainsKey(key);
 		}