fixes bugs in TypeInfo

idea/src/org/jetbrains/jet/codegen/ExpressionCodegen.java

@@ -1740,7 +1740,22 @@ public class ExpressionCodegen extends JetVisitor<StackValue, StackValue> {
                 v.dup();
             }
             Type type = typeMapper.boxType(typeMapper.mapType(jetType, OwnerKind.INTERFACE));
-            v.instanceOf(type);
+            if(jetType.isNullable()) {
+                Label nope = new Label();
+                Label end = new Label();
+
+                v.dup();
+                v.ifnull(nope);
+                v.instanceOf(type);
+                v.goTo(end);
+                v.mark(nope);
+                v.pop();
+                v.aconst(1);
+                v.mark(end);
+            }
+            else {
+                v.instanceOf(type);
+            }
         }
     }
 

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

@@ -11,6 +11,7 @@ import com.intellij.psi.tree.TokenSet;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 import org.jetbrains.jet.JetNodeTypes;
+import org.jetbrains.jet.lang.ErrorHandler;
 import org.jetbrains.jet.lang.JetSemanticServices;
 import org.jetbrains.jet.lang.cfg.JetFlowInformationProvider;
 import org.jetbrains.jet.lang.descriptors.*;
@@ -1708,7 +1709,7 @@ public class JetTypeInferrer {
                         return;
                     }
                     if (TypeUtils.intersect(semanticServices.getTypeChecker(), Sets.newHashSet(type, subjectType)) == null) {
-                        context.trace.getErrorHandler().genericError(reportErrorOn.getNode(), "Incompatible types: " + type + " and " + subjectType); // TODO : message
+                        context.trace.getErrorHandler().genericError(reportErrorOn.getNode(), "Incompatible types: " + type + " and " + subjectType + " " + ErrorHandler.atLocation(reportErrorOn));
                     }
                 }
 

idea/testData/codegen/regressions/kt259.jet

@@ -1,20 +1,66 @@
 class A() {}
-class B<T>() {}
+class B<T>() {
+    fun isT (a : Any?) : Boolean {
+        return a is T
+    }
+}
 
-fun box() : String {
+fun t1() : Boolean {
     val a = A()
-    System.out?.println(a is A)   //true
-    System.out?.println(a is A?)  //true
+    if(a !is A)   return false
+    if(a !is A?)   return false
+    if(null !is A?)   return false
+    return true
+}
 
+fun t2 () : Boolean {
     val b = B<String>()
-    System.out?.println(b is B<String>)   //true
-    System.out?.println(b is B<String>?)  //false !!!
+    if(b !is B<String>)   return false
+    if(b !is B<String>?)  return false
+    if(null !is B<String>?)  return false
 
     val v = b as B<String>   //ok
     val u = b as B<String>?  //TypeCastException
 
     val w : B<String>? = b as B<String>   //ok
     val x = w as B<String>?  //TypeCastException
+    return true
+}
 
+fun t3 () : Boolean {
+    val b = B<String>()
+    if(!b.isT("aaa")) return false
+
+    if(b.isT(10))     return false
+    if(b.isT(null))   return false
+
+    val d = B<String?>()
+    if(!d.isT("aaa")) return false
+    if(d.isT(10))     return false
+    if(!d.isT(null))  return false
+
+    val c = B<Int>()
+    if(c.isT("aaa")) return false
+    if(!c.isT(10))   return false
+    if(c.isT(null)) return false
+
+    val e = B<Int?>()
+    if(e.isT("aaa")) return false
+    if(!e.isT(10))   return false
+    if(!e.isT(null)) return false
+
+    return true
+}
+
+fun box() : String {
+    if(!t1()) {
+        return "t1 failed"
+    }
+    if(!t2()) {
+        return "t2 failed"
+    }
+    if(!t3()) {
+        return "t3 failed"
+    }
     return "OK"
 }

stdlib/src/jet/typeinfo/TypeInfo.java

@@ -40,25 +40,28 @@ public class TypeInfo<T> implements JetObject {
 
     public boolean isInstance(Object obj) {
         if (obj instanceof JetObject) {
-            return isSubtypeOf(((JetObject) obj).getTypeInfo());
+            return ((JetObject) obj).getTypeInfo().isSubtypeOf(this);
         }
-        throw new UnsupportedOperationException(); // TODO
+        if(obj == null)
+            return nullable;
+
+        return theClass.isAssignableFrom(obj.getClass());  // TODO
     }
 
-    public boolean isSubtypeOf(TypeInfo<?> other) {
-        if (!theClass.isAssignableFrom(other.theClass)) {
+    public boolean isSubtypeOf(TypeInfo<?> superType) {
+        if (!superType.theClass.isAssignableFrom(theClass)) {
             return false;
         }
-        if (!nullable && other.nullable) {
+        if (nullable && !superType.nullable) {
             return false;
         }
         if (typeParameters != null) {
-            if (other.typeParameters == null || other.typeParameters.length != typeParameters.length) {
+            if (superType.typeParameters == null || superType.typeParameters.length != typeParameters.length) {
                 throw new IllegalArgumentException("inconsistent type infos for the same class");
             }
             for (int i = 0; i < typeParameters.length; i++) {
                 // TODO handle variance here
-                if (!typeParameters [i].equals(other.typeParameters [i])) {
+                if (!typeParameters [i].equals(superType.typeParameters [i])) {
                     return false;
                 }
             }
@@ -95,9 +98,22 @@ public class TypeInfo<T> implements JetObject {
 
     @Override
     public int hashCode() {
-        int result = theClass.hashCode();
-        result = 31 * result + (typeParameters != null ? Arrays.hashCode(typeParameters) : 0);
-        return result;
+        return 31 * theClass.hashCode() + (typeParameters != null ? Arrays.hashCode(typeParameters) : 0);
+    }
+
+    @Override
+    public String toString() {
+        StringBuilder sb = new StringBuilder().append(theClass.getName());
+        if(typeParameters != null && typeParameters.length != 0) {
+            sb.append("<");
+            for(int i = 0; i != typeParameters.length-1; ++i) {
+                sb.append(typeParameters[i].toString()).append(",");
+            }
+            sb.append(typeParameters[typeParameters.length - 1].toString()).append(">");
+        }
+        if(nullable)
+            sb.append("?");
+        return sb.toString();
     }
 
     public static final TypeInfo<Byte> BYTE_TYPE_INFO = new TypeInfo<Byte>(Byte.class, false);