dfa: a variable can't be null after dereference (IDEA-122215)

java/java-tests/testData/inspection/dataFlow/fixture/ComparingToNotNullShouldNotAffectNullity.java

@@ -18,6 +18,27 @@ class Bar3 {
       if (first == getObj() || collection.size() > 0) {
         System.out.println(first.hashCode());
       }
+      if (<warning descr="Condition 'first == null' is always 'false'">first == null</warning>) {
+        System.out.println(first.hashCode());
+      }
+    }
+  }
+
+  void foo2(Collection<Object> collection) {
+    if (!collection.isEmpty()) {
+      Object first = collection.iterator().next();
+      if (first != getObj() || collection.size() > 0) {
+        first.hashCode();
+      }
+    }
+  }
+
+  void foo3(Collection<Object> collection) {
+    if (!collection.isEmpty()) {
+      Object first = collection.iterator().next();
+      if (first == getObj() || collection.size() > 2) {
+        System.out.println(first.hashCode());
+      }
       if (first == null) {
         System.out.println(<warning descr="Method invocation 'first.hashCode()' may produce 'java.lang.NullPointerException'">first.hashCode()</warning>);
       }

java/java-tests/testData/inspection/dataFlow/fixture/NotNullAfterDereference.java

@@ -0,0 +1,9 @@
+class Foo {
+
+  private void someMethod(String someArg) {
+    someArg.getClass();
+    if (<warning descr="Condition 'someArg == null' is always 'false'">someArg == null</warning>) {
+      System.err.println("Wrong argument");
+    }
+  }
+}