Avoid looking for inner classes when resolving a class constraint.

ICSharpCode.NRefactory.CSharp/Resolver/ResolveVisitor.cs

@@ -3257,13 +3257,16 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 			AstType outermostType = type;
 			while (outermostType.Parent is AstType)
 				outermostType = (AstType)outermostType.Parent;
-			NameLookupMode lookupMode = NameLookupMode.Type;
+			
 			if (outermostType.Parent is UsingDeclaration || outermostType.Parent is UsingAliasDeclaration) {
-				lookupMode = NameLookupMode.TypeInUsingDeclaration;
-			} else if (outermostType.Parent is TypeDeclaration && outermostType.Role == Roles.BaseType) {
-				lookupMode = NameLookupMode.BaseTypeReference;
-			}
-			return lookupMode;
+				return NameLookupMode.TypeInUsingDeclaration;
+			} else if (outermostType.Role == Roles.BaseType) {
+				// Use BaseTypeReference for a type's base type, and for a constraint on a type.
+				// Do not use it for a constraint on a method.
+				if (outermostType.Parent is TypeDeclaration || (outermostType.Parent is Constraint && outermostType.Parent.Parent is TypeDeclaration))
+					return NameLookupMode.BaseTypeReference;
+			}
+			return NameLookupMode.Type;
 		}
 		
 		ResolveResult IAstVisitor<ResolveResult>.VisitMemberType(MemberType memberType)

ICSharpCode.NRefactory.CSharp/TypeSystem/TypeSystemConvertVisitor.cs

@@ -515,7 +515,8 @@ namespace ICSharpCode.NRefactory.CSharp.TypeSystem
 									continue;
 								}
 							}
-							tp.Constraints.Add(type.ToTypeReference());
+							var lookupMode = (ownerType == EntityType.TypeDefinition) ? NameLookupMode.BaseTypeReference : NameLookupMode.Type;
+							tp.Constraints.Add(type.ToTypeReference(lookupMode));
 						}
 						break;
 					}

ICSharpCode.NRefactory.Tests/CSharp/Resolver/NameLookupTests.cs

@@ -1015,5 +1015,55 @@ namespace foo {
 			Assert.AreEqual("foo.Foo", result.Type.FullName);
 
 		}
+		
+		[Test]
+		public void BaseTypeReference_refers_to_outer_type()
+		{
+			string program = @"class B {}
+    class A : $B$ {
+        class B {}
+    }";
+			var result = Resolve<TypeResolveResult>(program);
+			Assert.IsFalse(result.IsError);
+			Assert.AreEqual("B", result.Type.FullName);
+			
+			// also check if the reference in the type system is correct
+			var a = ((ITypeDefinition)result.Type).Compilation.RootNamespace.GetTypeDefinition("A", 0);
+			Assert.AreEqual("B", a.DirectBaseTypes.Single().FullName);
+		}
+		
+		[Test]
+		public void Class_constraint_refers_to_outer_type()
+		{
+			string program = @"class B {}
+    class A<T> where T : $B$ {
+        class B {}
+    }";
+			var result = Resolve<TypeResolveResult>(program);
+			Assert.IsFalse(result.IsError);
+			Assert.AreEqual("B", result.Type.FullName);
+			
+			// also check if the reference in the type system is correct
+			var a = ((ITypeDefinition)result.Type).Compilation.RootNamespace.GetTypeDefinition("A", 1);
+			Assert.AreEqual("B", a.TypeParameters.Single().DirectBaseTypes.Single().FullName);
+		}
+		
+		[Test]
+		public void Method_constraint_refers_to_inner_type()
+		{
+			string program = @"class B {}
+    class A {
+    	void M<T>() where T : $B$ {}
+        class B {}
+    }";
+			var result = Resolve<TypeResolveResult>(program);
+			Assert.IsFalse(result.IsError);
+			Assert.AreEqual("A.B", result.Type.FullName);
+			
+			// also check if the reference in the type system is correct
+			var a = ((ITypeDefinition)result.Type).Compilation.RootNamespace.GetTypeDefinition("A", 0);
+			var method = a.Methods.Single(m => m.Name == "M");
+			Assert.AreEqual("A.B", method.TypeParameters.Single().DirectBaseTypes.Single().FullName);
+		}
 	}
 }

ICSharpCode.NRefactory/TypeSystem/Implementation/BaseTypeCollector.cs

@@ -55,8 +55,6 @@ namespace ICSharpCode.NRefactory.TypeSystem.Implementation
 			// (e.g. C implements I1 and I2, and both interfaces derive from Object)
 			if (!this.Contains(type)) {
 				foreach (IType baseType in type.DirectBaseTypes) {
-					if (type.Kind != TypeKind.TypeParameter && baseType.Kind == TypeKind.TypeParameter)
-						continue;
 					if (SkipImplementedInterfaces && def != null && def.Kind != TypeKind.Interface && def.Kind != TypeKind.TypeParameter) {
 						if (baseType.Kind == TypeKind.Interface) {
 							// skip the interface