Assertions on approximation of platform types to non-null types

- for most expressions (ExpressionCodegen.genQualified)

compiler/testData/codegen/notNullAssertions/A.java

@@ -32,4 +32,14 @@ public class A {
     public Object get(Object o) {
         return null;
     }
+
+    public A a() { return this; }
+
+    public static class B {
+        public static B b() { return null; }
+    }
+
+    public static class C {
+        public static C c() { return null; }
+    }
 }

compiler/testData/codegen/notNullAssertions/AssertionChecker.kt

@@ -1,5 +1,5 @@
 class AssertionChecker(val illegalStateExpected: Boolean) {
-    fun invoke(name: String, f: () -> Unit) {
+    fun invoke(name: String, f: () -> Any) {
         try {
             f()
         } catch (e: IllegalStateException) {
@@ -44,15 +44,32 @@ fun checkAssertions(illegalStateExpected: Boolean) {
     // binary expression
     check("plus") { A() + A() }
     
-    // postfix expression
-    check("inc") { var a = A(); a++ }
-    
-    // prefix expression
-    check("inc") { var a = A(); ++a }
-    
     // field
-    check("NULL") { val a = A().NULL }
+    check("NULL") { A().NULL }
     
     // static field
-    check("STATIC_NULL") { val a = A.STATIC_NULL }
+    check("STATIC_NULL") { A.STATIC_NULL }
+
+    // postfix expression
+    // TODO:
+//    check("inc") { var a = A().a(); a++ }
+
+    // prefix expression
+    check("inc-b") { var a = A.B.b(); a++ }
+
+    // prefix expression
+    check("inc-c") { var a = A.C.c(); a++ }
+
+    // prefix expression
+    check("inc") { var a = A().a(); ++a }
+
+    // prefix expression
+    check("inc-b") { var a = A.B.b(); ++a }
+
+    // prefix expression
+    // TODO:
+//    check("inc-c") { var a = A.C.c(); ++a }
 }
+
+fun A.C.inc(): A.C = A.C()
+fun <T> T.inc(): T = null as T

compiler/testData/codegen/notNullAssertions/arrayListGet.kt

@@ -1,8 +1,8 @@
 import java.util.ArrayList
 
-fun foo() {
+fun foo(): Any {
     val a = ArrayList<String>()
-    a.get(0)
+    return a.get(0)
 }
 
 fun bar(a: ArrayList<String>) {