JET-86: Report errors for class objects

idea/src/org/jetbrains/jet/lang/descriptors/ClassDescriptorImpl.java

@@ -86,6 +86,11 @@ public class ClassDescriptorImpl extends DeclarationDescriptorImpl implements Cl
         return null;
     }
 
+    @Override
+    public boolean isClassObjectAValue() {
+        return true;
+    }
+
     @Override
     public <R, D> R accept(DeclarationDescriptorVisitor<R, D> visitor, D data) {
         return visitor.visitClassDescriptor(this, data);

idea/src/org/jetbrains/jet/lang/descriptors/ClassifierDescriptor.java

@@ -17,4 +17,6 @@ public interface ClassifierDescriptor extends DeclarationDescriptor {
 
     @Nullable
     JetType getClassObjectType();
+
+    boolean isClassObjectAValue();
 }

idea/src/org/jetbrains/jet/lang/descriptors/LazySubstitutingClassDescriptor.java

@@ -95,6 +95,11 @@ public class LazySubstitutingClassDescriptor implements ClassDescriptor {
         return original.getClassObjectType();
     }
 
+    @Override
+    public boolean isClassObjectAValue() {
+        return original.isClassObjectAValue();
+    }
+
     @Override
     public <R, D> R accept(DeclarationDescriptorVisitor<R, D> visitor, D data) {
         return visitor.visitClassDescriptor(this, data);

idea/src/org/jetbrains/jet/lang/descriptors/MutableClassDescriptor.java

@@ -209,6 +209,11 @@ public class MutableClassDescriptor extends MutableDeclarationDescriptor impleme
         return classObjectType;
     }
 
+    @Override
+    public boolean isClassObjectAValue() {
+        return true;
+    }
+
     @Override
     public <R, D> R accept(DeclarationDescriptorVisitor<R, D> visitor, D data) {
         return visitor.visitClassDescriptor(this, data);

idea/src/org/jetbrains/jet/lang/descriptors/TypeParameterDescriptor.java

@@ -140,6 +140,11 @@ public class TypeParameterDescriptor extends DeclarationDescriptorImpl implement
         return classObjectBoundsAsType;
     }
 
+    @Override
+    public boolean isClassObjectAValue() {
+        return true;
+    }
+
     public int getIndex() {
         return index;
     }

idea/src/org/jetbrains/jet/lang/resolve/java/JavaClassDescriptor.java

@@ -108,6 +108,11 @@ public class JavaClassDescriptor extends MutableDeclarationDescriptor implements
         return classObjectType;
     }
 
+    @Override
+    public boolean isClassObjectAValue() {
+        return false;
+    }
+
     @Override
     public <R, D> R accept(DeclarationDescriptorVisitor<R, D> visitor, D data) {
         return visitor.visitClassDescriptor(this, data);

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

@@ -709,7 +709,7 @@ public class JetTypeInferrer {
                         ClassifierDescriptor classifier = scope.getClassifier(referencedName);
                         if (classifier != null) {
                             JetType classObjectType = classifier.getClassObjectType();
-                            if (classObjectType != null) {
+                            if (classObjectType != null && (isNamespacePosition() || classifier.isClassObjectAValue())) {
                                 result = classObjectType;
                             }
                             else {
@@ -727,6 +727,10 @@ public class JetTypeInferrer {
             }
         }
 
+        public boolean isNamespacePosition() {
+            return false;
+        }
+
         protected boolean furtherNameLookup(@NotNull JetSimpleNameExpression expression, @NotNull String referencedName) {
             NamespaceType namespaceType = lookupNamespaceType(expression, referencedName);
             if (namespaceType != null) {
@@ -1867,6 +1871,11 @@ public class JetTypeInferrer {
             super(scope, preferBlock);
         }
 
+        @Override
+        public boolean isNamespacePosition() {
+            return true;
+        }
+
         @NotNull
         @Override
         public TypeInferrerVisitor createNew(JetScope scope, boolean preferBlock) {

idea/testData/checker/ClassObjects.jet

@@ -0,0 +1,30 @@
+namespace Jet86
+
+class A {
+  class object {
+    val x = 1
+  }
+  <error>class object { // error
+    val x = 1
+  }</error>
+}
+
+class B() {
+  val x = 12
+}
+
+object b {
+  <error>class object {
+    val x = 1
+  }</error> // error
+}
+
+val a = A.x
+val c = <error>B</error>.x
+val d = b.<error>x</error>
+
+val s = <error>System</error>  // error
+fun test() {
+  System.out?.println()
+  java.lang.System.out?.println()
+}

idea/testData/resolve/ClassObjects.jet

@@ -0,0 +1,15 @@
+namespace Jet86
+
+~A~class A {
+  class object {
+    ~A.x~val x = 1
+  }
+}
+
+~B~class B() {
+  ~B.x~val x = 12
+}
+
+val a = `A`A.`A.x`x
+val c = `B`B.`!null`x
+val d = new B().`B.x`x

idea/tests/org/jetbrains/jet/resolve/ExpectedResolveData.java

@@ -115,8 +115,8 @@ public class ExpectedResolveData {
             String name = entry.getValue();
             PsiElement element = file.findElementAt(position);
 
+            JetReferenceExpression referenceExpression = PsiTreeUtil.getParentOfType(element, JetReferenceExpression.class);
             if ("!".equals(name)) {
-                JetReferenceExpression referenceExpression = PsiTreeUtil.getParentOfType(element, JetReferenceExpression.class);
                 assertTrue(
                         "Must have been unresolved: " +
                         renderReferenceInContext(referenceExpression) +
@@ -124,6 +124,15 @@ public class ExpectedResolveData {
                         unresolvedReferences.contains(referenceExpression));
                 continue;
             }
+            else if ("!null".equals(name)) {
+                assertTrue(
+                       "Must have been resolved to null: " +
+                        renderReferenceInContext(referenceExpression) +
+                        " but was resolved to " + DescriptorRenderer.TEXT.render(bindingContext.resolveReferenceExpression(referenceExpression)),
+                        bindingContext.getExpressionType(referenceExpression) == null
+                );
+                continue;
+            }
 
             PsiElement expected = nameToDeclaration.get(name);
             if (expected == null && name.startsWith("$")) {