IDEA-209947 Constant comparison

GitOrigin-RevId: 361545bd9303b8eac1e6c86da577ed5d9aad20c7

java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/TrackingRunner.java

@@ -369,7 +369,6 @@ public class TrackingRunner extends StandardDataFlowRunner {
             Warning caused by narrowing conversion
             Warning caused by unary minus
             Warning caused by final field initializer
-            Literal is not-null
   TODO: 3. Check how it works with:
             Inliners (notably: Stream API)
             Boxed numbers
@@ -932,23 +931,25 @@ public class TrackingRunner extends StandardDataFlowRunner {
   }
 
   private static MemoryStateChange findRelationAddedChange(MemoryStateChange history, DfaVariableValue var, Relation relation) {
-    List<Relation> subRelations;
+    List<RelationType> subRelations;
     switch (relation.myRelationType) {
       case NE:
-        subRelations = Arrays.asList(relation, new Relation(RelationType.GT, relation.myCounterpart),
-                                     new Relation(RelationType.LT, relation.myCounterpart));
+        if (relation.myCounterpart instanceof DfaConstValue) {
+          return history.findRelation(var, rel -> rel.equals(relation) ||
+                                                  rel.myRelationType == RelationType.EQ && rel.myCounterpart instanceof DfaConstValue,
+                                      true);
+        }
+        subRelations = Arrays.asList(RelationType.NE, RelationType.GT, RelationType.LT);
         break;
       case LE:
-        subRelations = Arrays.asList(new Relation(RelationType.EQ, relation.myCounterpart),
-                                     new Relation(RelationType.LT, relation.myCounterpart));
+        subRelations = Arrays.asList(RelationType.EQ, RelationType.LT);
         break;
       case GE:
-        subRelations = Arrays.asList(new Relation(RelationType.EQ, relation.myCounterpart),
-                                     new Relation(RelationType.GT, relation.myCounterpart));
+        subRelations = Arrays.asList(RelationType.EQ, RelationType.GT);
         break;
       default:
-        subRelations = Collections.singletonList(relation);
+        subRelations = Collections.singletonList(relation.myRelationType);
     }
-    return history.findRelation(var, subRelations::contains, true);
+    return history.findRelation(var, rel -> rel.myCounterpart == relation.myCounterpart && subRelations.contains(rel.myRelationType), true);
   }
 }

java/java-tests/testData/inspection/dataFlow/tracker/ConstantStrings.java

@@ -0,0 +1,13 @@
+/*
+Value is always false (s == null; line#11)
+  Result of 's != null' is known from line #10 (!"foo".equals(s) && !"bar".equals(s); line#10)
+ */
+
+import java.util.List;
+
+class Test {
+  void test(String s) {
+    if (!"foo".equals(s) && !"bar".equals(s)) return;
+    if (<selection>s == null</selection>) {}
+  }
+}

java/java-tests/testData/inspection/dataFlow/tracker/ConstantStrings2.java

@@ -0,0 +1,16 @@
+/*
+Value is always false (s == null; line#14)
+  's' was assigned (=; line#13)
+    One of the following happens:
+      Expression cannot be null as it's literal ("foo"; line#13)
+      or expression cannot be null as it's literal ("bar"; line#13)
+ */
+
+import java.util.List;
+
+class Test {
+  void test(boolean b) {
+    String s = b ? "foo" : "bar";
+    if (<selection>s == null</selection>) {}
+  }
+}

java/java-tests/testData/inspection/dataFlow/tracker/ListAddContract.java

@@ -1,6 +1,6 @@
 /*
-Value is always true (list.add("foo"); line#9)
-  According to contract, method 'add' always returns 'true' value (add; line#9)
+Value is always true (list.add("foo"); line#10)
+  According to contract, method 'add' always returns 'true' value (add; line#10)
  */
 
 import java.util.List;

java/java-tests/testSrc/com/intellij/java/codeInspection/DataFlowInspectionTrackerTest.java

@@ -156,4 +156,6 @@ public class DataFlowInspectionTrackerTest extends LightCodeInsightFixtureTestCa
   public void testInstanceOfSecondCheck() { doTest(); }
   public void testNullCheckNpeNullCheck() { doTest(); }
   public void testListAddContract() { doTest(); }
+  public void testConstantStrings() { doTest(); }
+  public void testConstantStrings2() { doTest(); }
 }