Improved disambiguation of type references.

ICSharpCode.Decompiler/Ast/Transforms/IntroduceUsingDeclarations.cs

@@ -12,14 +12,13 @@ namespace ICSharpCode.Decompiler.Ast.Transforms
 	/// <summary>
 	/// Introduces using declarations.
 	/// </summary>
-	public class IntroduceUsingDeclarations : DepthFirstAstVisitor<object, object>, IAstTransform
+	public class IntroduceUsingDeclarations : IAstTransform
 	{
 		DecompilerContext context;
 		
 		public IntroduceUsingDeclarations(DecompilerContext context)
 		{
 			this.context = context;
-			currentNamespace = context.CurrentType != null ? context.CurrentType.Namespace : string.Empty;
 		}
 		
 		public void Run(AstNode compilationUnit)
@@ -28,7 +27,7 @@ namespace ICSharpCode.Decompiler.Ast.Transforms
 				return;
 			
 			// First determine all the namespaces that need to be imported:
-			compilationUnit.AcceptVisitor(this, null);
+			compilationUnit.AcceptVisitor(new FindRequiredImports(this), null);
 			
 			importedNamespaces.Add("System"); // always import System, even when not necessary
 			
@@ -55,48 +54,60 @@ namespace ICSharpCode.Decompiler.Ast.Transforms
 			}
 			
 			// verify that the SimpleTypes refer to the correct type (no ambiguities)
-			FullyQualifyAmbiguousTypeNames(compilationUnit);
+			compilationUnit.AcceptVisitor(new FullyQualifyAmbiguousTypeNamesVisitor(this), null);
 		}
 		
 		readonly HashSet<string> declaredNamespaces = new HashSet<string>() { string.Empty };
 		readonly HashSet<string> importedNamespaces = new HashSet<string>();
 		
+		// Note that we store type names with `n suffix, so we automatically disambiguate based on number of type parameters.
 		readonly HashSet<string> availableTypeNames = new HashSet<string>();
 		readonly HashSet<string> ambiguousTypeNames = new HashSet<string>();
-		string currentNamespace;
 		
-		bool IsParentOfCurrentNamespace(string ns)
+		sealed class FindRequiredImports : DepthFirstAstVisitor<object, object>
 		{
-			if (ns.Length == 0)
+			readonly IntroduceUsingDeclarations transform;
-				return true;
+			string currentNamespace;
-			if (currentNamespace.StartsWith(ns, StringComparison.Ordinal)) {
+			
-				if (currentNamespace.Length == ns.Length)
+			public FindRequiredImports(IntroduceUsingDeclarations transform)
-					return true;
+			{
-				if (currentNamespace[ns.Length] == '.')
+				this.transform = transform;
+				this.currentNamespace = transform.context.CurrentType != null ? transform.context.CurrentType.Namespace : string.Empty;
+			}
+			
+			bool IsParentOfCurrentNamespace(string ns)
+			{
+				if (ns.Length == 0)
 					return true;
+				if (currentNamespace.StartsWith(ns, StringComparison.Ordinal)) {
+					if (currentNamespace.Length == ns.Length)
+						return true;
+					if (currentNamespace[ns.Length] == '.')
+						return true;
+				}
+				return false;
 			}
-			return false;
+			
-		}
+			public override object VisitSimpleType(SimpleType simpleType, object data)
-		
+			{
-		public override object VisitSimpleType(SimpleType simpleType, object data)
+				TypeReference tr = simpleType.Annotation<TypeReference>();
-		{
+				if (tr != null && !IsParentOfCurrentNamespace(tr.Namespace)) {
-			TypeReference tr = simpleType.Annotation<TypeReference>();
+					transform.importedNamespaces.Add(tr.Namespace);
-			if (tr != null && !IsParentOfCurrentNamespace(tr.Namespace)) {
+				}
-				importedNamespaces.Add(tr.Namespace);
+				return base.VisitSimpleType(simpleType, data); // also visit type arguments
+			}
+			
+			public override object VisitNamespaceDeclaration(NamespaceDeclaration namespaceDeclaration, object data)
+			{
+				string oldNamespace = currentNamespace;
+				foreach (Identifier ident in namespaceDeclaration.Identifiers) {
+					currentNamespace = NamespaceDeclaration.BuildQualifiedName(currentNamespace, ident.Name);
+					transform.declaredNamespaces.Add(currentNamespace);
+				}
+				base.VisitNamespaceDeclaration(namespaceDeclaration, data);
+				currentNamespace = oldNamespace;
+				return null;
 			}
-			return base.VisitSimpleType(simpleType, data); // also visit type arguments
-		}
-		
-		public override object VisitNamespaceDeclaration(NamespaceDeclaration namespaceDeclaration, object data)
-		{
-			string oldNamespace = currentNamespace;
-			foreach (Identifier ident in namespaceDeclaration.Identifiers) {
-				currentNamespace = NamespaceDeclaration.BuildQualifiedName(currentNamespace, ident.Name);
-				declaredNamespaces.Add(currentNamespace);
-			}
-			base.VisitNamespaceDeclaration(namespaceDeclaration, data);
-			currentNamespace = oldNamespace;
-			return null;
 		}
 		
 		void FindAmbiguousTypeNames(ModuleDefinition module, bool internalsVisible)
@@ -111,17 +122,176 @@ namespace ICSharpCode.Decompiler.Ast.Transforms
 			}
 		}
 		
-		void FullyQualifyAmbiguousTypeNames(AstNode compilationUnit)
+		sealed class FullyQualifyAmbiguousTypeNamesVisitor : DepthFirstAstVisitor<object, object>
 		{
-			foreach (SimpleType simpleType in compilationUnit.Descendants.OfType<SimpleType>()) {
+			readonly IntroduceUsingDeclarations transform;
+			string currentNamespace;
+			HashSet<string> currentMemberTypes;
+			Dictionary<string, MemberReference> currentMembers;
+			bool isWithinTypeReferenceExpression;
+			
+			public FullyQualifyAmbiguousTypeNamesVisitor(IntroduceUsingDeclarations transform)
+			{
+				this.transform = transform;
+				this.currentNamespace = transform.context.CurrentType != null ? transform.context.CurrentType.Namespace : string.Empty;
+			}
+			
+			public override object VisitNamespaceDeclaration(NamespaceDeclaration namespaceDeclaration, object data)
+			{
+				string oldNamespace = currentNamespace;
+				foreach (Identifier ident in namespaceDeclaration.Identifiers) {
+					currentNamespace = NamespaceDeclaration.BuildQualifiedName(currentNamespace, ident.Name);
+				}
+				base.VisitNamespaceDeclaration(namespaceDeclaration, data);
+				currentNamespace = oldNamespace;
+				return null;
+			}
+			
+			public override object VisitTypeDeclaration(TypeDeclaration typeDeclaration, object data)
+			{
+				HashSet<string> oldMemberTypes = currentMemberTypes;
+				currentMemberTypes = currentMemberTypes != null ? new HashSet<string>(currentMemberTypes) : new HashSet<string>();
+				
+				Dictionary<string, MemberReference> oldMembers = currentMembers;
+				currentMembers = new Dictionary<string, MemberReference>();
+				
+				TypeDefinition typeDef = typeDeclaration.Annotation<TypeDefinition>();
+				bool privateMembersVisible = true;
+				ModuleDefinition internalMembersVisibleInModule = typeDef.Module;
+				while (typeDef != null) {
+					foreach (GenericParameter gp in typeDef.GenericParameters) {
+						currentMemberTypes.Add(gp.Name);
+					}
+					foreach (TypeDefinition t in typeDef.NestedTypes) {
+						if (privateMembersVisible || IsVisible(t, internalMembersVisibleInModule))
+							currentMemberTypes.Add(t.Name.Substring(t.Name.LastIndexOf('+') + 1));
+					}
+					
+					foreach (MethodDefinition method in typeDef.Methods) {
+						if (privateMembersVisible || IsVisible(method, internalMembersVisibleInModule))
+							AddCurrentMember(method);
+					}
+					foreach (PropertyDefinition property in typeDef.Properties) {
+						if (privateMembersVisible || IsVisible(property.GetMethod, internalMembersVisibleInModule) || IsVisible(property.SetMethod, internalMembersVisibleInModule))
+							AddCurrentMember(property);
+					}
+					foreach (EventDefinition ev in typeDef.Events) {
+						if (privateMembersVisible || IsVisible(ev.AddMethod, internalMembersVisibleInModule) || IsVisible(ev.RemoveMethod, internalMembersVisibleInModule))
+							AddCurrentMember(ev);
+					}
+					foreach (FieldDefinition f in typeDef.Fields) {
+						if (privateMembersVisible || IsVisible(f, internalMembersVisibleInModule))
+							AddCurrentMember(f);
+					}
+					// repeat with base class:
+					if (typeDef.BaseType != null)
+						typeDef = typeDef.BaseType.Resolve();
+					else
+						typeDef = null;
+					privateMembersVisible = false;
+				}
+				
+				// Now add current members from outer classes:
+				if (oldMembers != null) {
+					foreach (var pair in oldMembers) {
+						// add members from outer classes only if the inner class doesn't define the member
+						if (!currentMembers.ContainsKey(pair.Key))
+							currentMembers.Add(pair.Key, pair.Value);
+					}
+				}
+				
+				base.VisitTypeDeclaration(typeDeclaration, data);
+				currentMembers = oldMembers;
+				return null;
+			}
+			
+			void AddCurrentMember(MemberReference m)
+			{
+				MemberReference existingMember;
+				if (currentMembers.TryGetValue(m.Name, out existingMember)) {
+					// We keep the existing member assignment if it was from another class (=from a derived class),
+					// because members in derived classes have precedence over members in base classes.
+					if (existingMember != null && existingMember.DeclaringType == m.DeclaringType) {
+						// Use null as value to signalize multiple members with the same name
+						currentMembers[m.Name] = null;
+					}
+				} else {
+					currentMembers.Add(m.Name, m);
+				}
+			}
+			
+			bool IsVisible(MethodDefinition m, ModuleDefinition internalMembersVisibleInModule)
+			{
+				if (m == null)
+					return false;
+				switch (m.Attributes & MethodAttributes.MemberAccessMask) {
+					case MethodAttributes.FamANDAssem:
+					case MethodAttributes.Assembly:
+						return m.Module == internalMembersVisibleInModule;
+					case MethodAttributes.Family:
+					case MethodAttributes.FamORAssem:
+					case MethodAttributes.Public:
+						return true;
+					default:
+						return false;
+				}
+			}
+			
+			bool IsVisible(FieldDefinition f, ModuleDefinition internalMembersVisibleInModule)
+			{
+				if (f == null)
+					return false;
+				switch (f.Attributes & FieldAttributes.FieldAccessMask) {
+					case FieldAttributes.FamANDAssem:
+					case FieldAttributes.Assembly:
+						return f.Module == internalMembersVisibleInModule;
+					case FieldAttributes.Family:
+					case FieldAttributes.FamORAssem:
+					case FieldAttributes.Public:
+						return true;
+					default:
+						return false;
+				}
+			}
+			
+			bool IsVisible(TypeDefinition t, ModuleDefinition internalMembersVisibleInModule)
+			{
+				if (t == null)
+					return false;
+				switch (t.Attributes & TypeAttributes.VisibilityMask) {
+					case TypeAttributes.NotPublic:
+					case TypeAttributes.NestedAssembly:
+					case TypeAttributes.NestedFamANDAssem:
+						return t.Module == internalMembersVisibleInModule;
+					case TypeAttributes.NestedFamily:
+					case TypeAttributes.NestedFamORAssem:
+					case TypeAttributes.NestedPublic:
+					case TypeAttributes.Public:
+						return true;
+					default:
+						return false;
+				}
+			}
+			
+			public override object VisitSimpleType(SimpleType simpleType, object data)
+			{
+				// Handle type arguments first, so that the fixed-up type arguments get moved over to the MemberType,
+				// if we're also creating one here.
+				base.VisitSimpleType(simpleType, data);
 				TypeReference tr = simpleType.Annotation<TypeReference>();
-				if (tr != null && ambiguousTypeNames.Contains(tr.Name)) {
+				// Fully qualify any ambiguous type names.
+				if (tr != null && IsAmbiguous(tr.Namespace, tr.Name)) {
 					AstType ns;
 					if (string.IsNullOrEmpty(tr.Namespace)) {
 						ns = new SimpleType("global");
 					} else {
 						string[] parts = tr.Namespace.Split('.');
-						ns = new SimpleType(parts[0]);
+						if (IsAmbiguous(string.Empty, parts[0])) {
+							// conflict between namespace and type name/member name
+							ns = new MemberType { Target = new SimpleType("global"), IsDoubleColon = true, MemberName = parts[0] };
+						} else {
+							ns = new SimpleType(parts[0]);
+						}
 						for (int i = 1; i < parts.Length; i++) {
 							ns = new MemberType { Target = ns, MemberName = parts[i] };
 						}
@@ -134,6 +304,41 @@ namespace ICSharpCode.Decompiler.Ast.Transforms
 					simpleType.TypeArguments.MoveTo(mt.TypeArguments);
 					simpleType.ReplaceWith(mt);
 				}
+				return null;
+			}
+			
+			public override object VisitTypeReferenceExpression(TypeReferenceExpression typeReferenceExpression, object data)
+			{
+				isWithinTypeReferenceExpression = true;
+				base.VisitTypeReferenceExpression(typeReferenceExpression, data);
+				isWithinTypeReferenceExpression = false;
+				return null;
+			}
+			
+			bool IsAmbiguous(string ns, string name)
+			{
+				// If the type name conflicts with an inner class/type parameter, we need to fully-qualify it:
+				if (currentMemberTypes != null && currentMemberTypes.Contains(name))
+					return true;
+				// If the type name conflicts with a field/property etc. on the current class, we need to fully-qualify it,
+				// if we're inside an expression.
+				if (isWithinTypeReferenceExpression && currentMembers != null) {
+					MemberReference mr;
+					if (currentMembers.TryGetValue(name, out mr)) {
+						// However, in the special case where the member is a field or property with the same type
+						// as is requested, then we can use the short name (if it's not otherwise ambiguous)
+						PropertyDefinition prop = mr as PropertyDefinition;
+						FieldDefinition field = mr as FieldDefinition;
+						if (!(prop != null && prop.PropertyType.Namespace == ns && prop.PropertyType.Name == name)
+						    && !(field != null && field.FieldType.Namespace == ns && field.FieldType.Name == name))
+							return true;
+					}
+				}
+				// If the type is defined in the current namespace,
+				// then we can use the short name even if we imported type with same name from another namespace.
+				if (ns == currentNamespace && !string.IsNullOrEmpty(ns))
+					return false;
+				return transform.ambiguousTypeNames.Contains(name);
 			}
 		}
 	}