Support flexible types in DataFlowValues

compiler/frontend/src/org/jetbrains/jet/lang/resolve/calls/smartcasts/DataFlowValueFactory.java

@@ -80,7 +80,7 @@ public class DataFlowValueFactory {
 
     @NotNull
     private static Nullability getImmanentNullability(@NotNull JetType type) {
-        return type.isNullable() || TypeUtils.hasNullableSuperType(type) ? Nullability.UNKNOWN : Nullability.NOT_NULL;
+        return TypeUtils.isNullableType(type) ? Nullability.UNKNOWN : Nullability.NOT_NULL;
     }
 
     private static class IdentifierInfo {

compiler/testData/diagnostics/tests/platformTypes/dereference.kt

@@ -0,0 +1,28 @@
+// FILE: p/J.java
+
+package p;
+
+public class J {
+    public J j() {return null;}
+
+    public <T> T foo() {return null;}
+    public <T extends J> T foo1() {return null;}
+}
+
+// FILE: k.kt
+
+import p.*
+
+fun test(j: J) {
+    j.j() : J
+    j.j().j()
+    j.j()!!.j()
+
+    val ann = j.foo<String>()
+    ann!!.length
+    ann.length
+
+    val a = j.foo<J>()
+    a!!.j()
+    a.j()
+}

compiler/tests/org/jetbrains/jet/checkers/JetDiagnosticsTestGenerated.java

@@ -7695,6 +7695,11 @@ public class JetDiagnosticsTestGenerated extends AbstractJetDiagnosticsTest {
                 JetTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("compiler/testData/diagnostics/tests/platformTypes"), Pattern.compile("^(.+)\\.kt$"), true);
             }
             
+            @TestMetadata("dereference.kt")
+            public void testDereference() throws Exception {
+                doTest("compiler/testData/diagnostics/tests/platformTypes/dereference.kt");
+            }
+            
             @TestMetadata("compiler/testData/diagnostics/tests/platformTypes/methodCall")
             @TestDataPath("$PROJECT_ROOT")
             @RunWith(org.jetbrains.jet.JUnit3RunnerWithInners.class)

core/descriptors/src/org/jetbrains/jet/lang/types/flexibleTypes.kt

@@ -21,6 +21,8 @@ public trait FlexibleType : JetType {
     val upperBound: JetType
 }
 
+public fun JetType.isFlexible(): Boolean = this is FlexibleType
+
 public open class DelegatingFlexibleType(
         override val lowerBound: JetType,
         override val upperBound: JetType