IDEA-218089 Find cause may duplicate reason for && operator

GitOrigin-RevId: 4f742038e13a70f086e5065acff060ed72340822

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

@@ -163,12 +163,15 @@ public class TrackingRunner extends StandardDataFlowRunner {
             Cause for "modifying an immutable collection"
             Cause for "Collection is always empty" (separate inspection now)
   TODO: 2. Describe causes in more cases:
-            Warning caused by contract
+            Warning caused by complex contracts
             Warning caused by CustomMethodHandler
             Warning caused by polyadic math
             Warning caused by unary minus
+            Warning caused by string concatenation
+            Warning caused by java.lang.Void nullability
+            Warning caused by getClass() equality
+            Warning caused by inliners
   TODO: 3. Check how it works with:
-            Inliners (notably: Stream API)
             Boxed numbers
    */
   @Nullable
@@ -356,9 +359,22 @@ public class TrackingRunner extends StandardDataFlowRunner {
       if (children.isEmpty()) {
         ((PossibleExecutionDfaProblemType)mergePoint.myProblem).myComplete = false;
       }
+      List<CauseItem> mergeChildren = mergePoint.myChildren;
       for (CauseItem child : children) {
-        if (!mergePoint.myChildren.contains(child)) {
-          mergePoint.myChildren.add(child);
+        if (!mergeChildren.contains(child)) {
+          boolean merged = false;
+          for (int i = 0; i < mergeChildren.size(); i++) {
+            CauseItem mergeChild = mergeChildren.get(i);
+            CauseItem result = mergeChild.merge(child);
+            if (result != null) {
+              mergeChildren.set(i, result);
+              merged = true;
+              break;
+            }
+          }
+          if (!merged) {
+            mergeChildren.add(child);
+          }
         }
       }
       return true;

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

@@ -0,0 +1,36 @@
+/*
+Value is always false (bar.equals("Asdasdd") && asdsa.length() == 12; line#32)
+  One of the following happens:
+    Operand #1 of &&-chain is false (bar.equals("Asdasdd"); line#32)
+      According to hard-coded contract, method 'equals' returns 'false' value when this != parameter (equals; line#32)
+        One of the following happens:
+          'bar' was assigned (=; line#25)
+            Values cannot be equal because "asdbar".length != "Asdasdd".length
+              Left operand is 6 (foo + "bar"; line#25)
+              and right operand is 7 ("Asdasdd"; line#32)
+          or 'bar' was assigned (=; line#27)
+            Values cannot be equal because "asdbaz".length != "Asdasdd".length
+              Left operand is 6 (foo + "baz"; line#27)
+              and right operand is 7 ("Asdasdd"; line#32)
+    or operand #2 of &&-chain is false (asdsa.length() == 12; line#32)
+      Left operand is in {0..3} (asdsa.length(); line#32)
+        Range is known from line #32 (bar.equals("Asdasdd"); line#32)
+ */
+class A
+  public A(String asdsa) {
+    String foo = "asd";
+    String bar;
+
+    if (asdsa.length() > 4) {
+      bar = foo + "bar";
+    } else if (asdsa.length() >3) {
+      bar = foo + "baz";
+    } else {
+      bar = "Asdasdd";
+    }
+
+    if (<selection>bar.equals("Asdasdd") && asdsa.length() == 12</selection>) {
+      System.out.println("asd");
+    }
+  }
+}

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

@@ -179,4 +179,5 @@ public class DataFlowInspectionTrackerTest extends LightJavaCodeInsightFixtureTe
   public void testFinalFieldInitializedCtor() { doTest(); }
   public void testEqualsNull() { doTest(); }
   public void testEnumCompare() { doTest(); }
+  public void testMergeOnAnd() { doTest(); }
 }