Subtyping works for parameterized superclasses

idea/src/org/jetbrains/jet/lang/types/ErrorType.java

@@ -35,7 +35,7 @@ public class ErrorType extends VisitableTypeImpl implements Type {
 
     @Override
     public <R, D> R accept(TypeVisitor<R, D> visitor, D data) {
-        throw new UnsupportedOperationException("Not found: " + debugLabel); // TODO
+        return visitor.visitErrorType(this, data);
     }
 
     @Override

idea/src/org/jetbrains/jet/lang/types/JetTypeChecker.java

@@ -1,6 +1,7 @@
 package org.jetbrains.jet.lang.types;
 
 import com.intellij.psi.tree.IElementType;
+import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 import org.jetbrains.jet.JetNodeTypes;
 import org.jetbrains.jet.lang.psi.*;
@@ -63,7 +64,7 @@ public class JetTypeChecker {
     }
 
     public boolean isConvertibleTo(JetExpression expression, Type type) {
-        return false;  //To change body of created methods use File | Settings | File Templates.
+        throw new UnsupportedOperationException(); // TODO
     }
 
     public boolean isSubtypeOf(Type subtype, Type supertype) {
@@ -107,7 +108,18 @@ public class JetTypeChecker {
         return substitute(parameterValues, subject);
     }
 
+    @NotNull
     private Type substitute(Map<TypeParameterDescriptor, TypeProjection> parameterValues, Type subject) {
+        if (subject instanceof TypeVariable) {
+            TypeVariable typeVariable = (TypeVariable) subject;
+            TypeProjection value = parameterValues.get(typeVariable.getTypeParameterDescriptor());
+            if (value == null) {
+                return typeVariable;
+            }
+            Type type = value.getType();
+            assert type != null;
+            return type;
+        }
         List<TypeProjection> newArguments = new ArrayList<TypeProjection>();
         for (TypeProjection argument : subject.getArguments()) {
             newArguments.add(new TypeProjection(argument.getProjectionKind(), substitute(parameterValues, argument.getType())));
@@ -116,8 +128,13 @@ public class JetTypeChecker {
     }
 
     private Type specializeType(Type type, List<TypeProjection> newArguments) {
-        // TODO
+        return type.accept(new TypeVisitor<Type, List<TypeProjection>>() {
-        return type;
+            @Override
+            public Type visitClassType(ClassType classType, List<TypeProjection> newArguments) {
+                return new ClassType(classType.getAttributes(), classType.getClassDescriptor(), newArguments);
+            }
+
+        }, newArguments);
     }
 
     private boolean checkSubtypeForTheSameConstructor(Type subtype, Type supertype) {

idea/src/org/jetbrains/jet/lang/types/NullableType.java

@@ -0,0 +1,33 @@
+package org.jetbrains.jet.lang.types;
+
+import java.util.Collection;
+import java.util.List;
+
+/**
+ * @author abreslav
+ */
+public class NullableType extends VisitableTypeImpl {
+    public NullableType(List<Attribute> attributes) {
+        super(attributes);
+    }
+
+    @Override
+    public TypeConstructor getConstructor() {
+        throw new UnsupportedOperationException(); // TODO
+    }
+
+    @Override
+    public List<TypeProjection> getArguments() {
+        throw new UnsupportedOperationException(); // TODO
+    }
+
+    @Override
+    public Collection<MemberDescriptor> getMembers() {
+        throw new UnsupportedOperationException(); // TODO
+    }
+
+    @Override
+    public <R, D> R accept(TypeVisitor<R, D> visitor, D data) {
+        return visitor.visitNullableType(this, data);
+    }
+}

idea/src/org/jetbrains/jet/lang/types/TypeVariable.java

@@ -12,8 +12,15 @@ import java.util.List;
  */
 public class TypeVariable extends TypeImpl {
 
+    private final TypeParameterDescriptor typeParameterDescriptor;
+
     public TypeVariable(@NotNull List<Attribute> attributes, @NotNull TypeParameterDescriptor typeParameter) {
         super(attributes, typeParameter.getTypeConstructor(), Collections.<TypeProjection>emptyList());
+        this.typeParameterDescriptor = typeParameter;
+    }
+
+    public TypeParameterDescriptor getTypeParameterDescriptor() {
+        return typeParameterDescriptor;
     }
 
     @Override

idea/src/org/jetbrains/jet/lang/types/TypeVisitor.java

@@ -28,6 +28,10 @@ public class TypeVisitor<R, D> {
         return visitType(errorType, data);
     }
 
+    public R visitNullableType(NullableType nullableType, D data) {
+        return visitType(nullableType, data);
+    }
+
     public R visitType(Type type, D data) {
         throw new UnsupportedOperationException(); // TODO
     }

idea/tests/org/jetbrains/jet/types/JetTypeCheckerTest.java

@@ -158,9 +158,12 @@ public class JetTypeCheckerTest extends LightDaemonAnalyzerTestCase {
         assertNotSubtype("Base_T<in Int>", "Base_T<out Int>");
         assertNotSubtype("Base_T<*>", "Base_T<out Int>");
 
-        assertNotSubtype("Derived_T<Any>", "Base_T<Any>");
+        assertSubtype("Derived_T<Int>", "Base_T<Int>");
-        assertSubtype("Derived_outT<Any>", "Base_outT<Any>");
+        assertSubtype("Derived_outT<Int>", "Base_outT<Int>");
+        assertSubtype("Derived_inT<Int>", "Base_inT<Int>");
+
         assertNotSubtype("Derived_T<Int>", "Base_T<Any>");
+
         assertSubtype("Derived_outT<Int>", "Base_outT<Any>");
         assertSubtype("Derived_T<Int>", "Base_T<out Any>");
         assertSubtype("Derived_T<Any>", "Base_T<in Int>");