Fixed some issues with GetBaseTypes/GetAllBaseTypes.

ICSharpCode.NRefactory.Tests/TypeSystem/GetAllBaseTypesTest.cs

@@ -70,7 +70,6 @@ namespace ICSharpCode.NRefactory.TypeSystem
 			Assert.AreEqual(new [] { c }, c.GetAllBaseTypes(context).ToArray());
 		}
 		
-		
 		[Test]
 		public void ClassDerivingFromTwoInstanciationsOfIEnumerable()
 		{
@@ -78,14 +77,33 @@ namespace ICSharpCode.NRefactory.TypeSystem
 			DefaultTypeDefinition c = new DefaultTypeDefinition(mscorlib, string.Empty, "C");
 			c.BaseTypes.Add(typeof(IEnumerable<int>).ToTypeReference());
 			c.BaseTypes.Add(typeof(IEnumerable<uint>).ToTypeReference());
-			Assert.AreEqual(new [] {
+			IType[] expected = {
 				c,
 				c.BaseTypes[0].Resolve(context),
 				c.BaseTypes[1].Resolve(context),
 				mscorlib.GetClass(typeof(IEnumerable)),
 				mscorlib.GetClass(typeof(object))
-			                },
+			};
+			Assert.AreEqual(expected,
 			                c.GetAllBaseTypes(context).OrderBy(t => t.DotNetName).ToArray());
 		}
+		
+		[Test]
+		public void StructImplementingIEquatable()
+		{
+			// struct S : IEquatable<S> {}
+			// don't use a Cecil-loaded struct for this test; we're testing the implicit addition of System.ValueType
+			DefaultTypeDefinition s = new DefaultTypeDefinition(mscorlib, string.Empty, "S");
+			s.ClassType = ClassType.Struct;
+			s.BaseTypes.Add(new ParameterizedType(mscorlib.GetClass(typeof(IEquatable<>)), new[] { s }));
+			IType[] expected = {
+				s,
+				s.BaseTypes[0].Resolve(context),
+				mscorlib.GetClass(typeof(object)),
+				mscorlib.GetClass(typeof(ValueType))
+			};
+			Assert.AreEqual(expected,
+			                s.GetAllBaseTypes(context).OrderBy(t => t.DotNetName).ToArray());
+		}
 	}
 }

ICSharpCode.NRefactory/TypeSystem/ExtensionMethods.cs

@@ -43,12 +43,12 @@ namespace ICSharpCode.NRefactory.TypeSystem
 			}
 			// Avoid outputting a type more than once - necessary for "diamond" multiple inheritance
 			// (e.g. C implements I1 and I2, and both interfaces derive from Object)
-			if (output.Contains(type))
-				return;
+			if (!output.Contains(type)) {
 				output.Add(type);
 				foreach (IType baseType in type.GetBaseTypes(context)) {
 					CollectAllBaseTypes(baseType, context, activeTypeDefinitions, output);
 				}
+			}
 			if (def != null)
 				activeTypeDefinitions.Pop();
 		}

ICSharpCode.NRefactory/TypeSystem/Implementation/DefaultTypeDefinition.cs

@@ -318,30 +318,36 @@ namespace ICSharpCode.NRefactory.TypeSystem.Implementation
 		
 		public IEnumerable<IType> GetBaseTypes(ITypeResolveContext context)
 		{
-			if (baseTypes == null || baseTypes.Count == 0) {
-				if (this.FullName == "System.Object")
-					return EmptyList<IType>.Instance;
+			bool hasNonInterface = false;
+			if (baseTypes != null) {
+				foreach (ITypeReference baseTypeRef in baseTypes) {
+					IType baseType = baseTypeRef.Resolve(context);
+					ITypeDefinition baseTypeDef = baseType.GetDefinition();
+					if (baseTypeDef == null || baseTypeDef.ClassType != ClassType.Interface)
+						hasNonInterface = true;
+					yield return baseType;
+				}
+			}
+			if (!hasNonInterface && !(this.Name == "Object" && this.Namespace == "System" && this.TypeParameterCount == 0)) {
+				Type primitiveBaseType;
 				switch (classType) {
 					case ClassType.Enum:
-						return GetPrimitiveBaseType(typeof(Enum), context);
+						primitiveBaseType = typeof(Enum);
+						break;
 					case ClassType.Struct:
-						return GetPrimitiveBaseType(typeof(ValueType), context);
+						primitiveBaseType = typeof(ValueType);
+						break;
 					case ClassType.Delegate:
-						return GetPrimitiveBaseType(typeof(Delegate), context);
+						primitiveBaseType = typeof(Delegate);
+						break;
 					default:
-						return GetPrimitiveBaseType(typeof(object), context);
-				}
+						primitiveBaseType = typeof(object);
+						break;
 				}
-			return baseTypes.Select(t => t.Resolve(context)).Where(t => t != SharedTypes.UnknownType);
-		}
-		
-		static IEnumerable<IType> GetPrimitiveBaseType(Type type, ITypeResolveContext context)
-		{
-			IType t = context.GetClass(type);
+				IType t = context.GetClass(primitiveBaseType);
 				if (t != null)
-				return new [] { t };
-			else
-				return EmptyList<IType>.Instance;
+					yield return t;
+			}
 		}
 		
 		public virtual ITypeDefinition GetCompoundClass()