DfaMemoryStateImpl#removeEquivalenceRelations: restore class invariant on every iteration

Invariant is required for convertQualifiers to function properly
Fixes EA-127085 - NPE: DfaMemoryStateImpl.getEqClassIndex

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

@@ -320,18 +320,16 @@ public class DfaMemoryStateImpl implements DfaMemoryState {
     if (classes != null) {
       int i = ArrayUtil.indexOf(classes, index);
       if (i != -1) {
-        classes = ArrayUtil.remove(classes, i);
-        myIdToEqClassesIndices.put(id, classes);
+        if (classes.length == 1) {
+          myIdToEqClassesIndices.remove(id);
+        } else {
+          classes = ArrayUtil.remove(classes, i);
+          myIdToEqClassesIndices.put(id, classes);
+        }
       }
     }
   }
 
-  private void removeAllFromMap(int id) {
-    if (id < 0) return;
-    id = unwrap(myFactory.getValue(id)).getID();
-    myIdToEqClassesIndices.remove(id);
-  }
-
   /**
    * Returns true if current state describes all possible concrete program states described by {@code that} state.
    *
@@ -1374,14 +1372,15 @@ public class DfaMemoryStateImpl implements DfaMemoryState {
     myCachedHash = null;
   }
 
-  void removeEquivalenceRelations(@NotNull DfaVariableValue varPlain) {
-    final int idPlain = varPlain.getID();
+  void removeEquivalenceRelations(@NotNull DfaVariableValue var) {
+    final int varID = var.getID();
 
-    int[] result = ObjectUtils.notNull(myIdToEqClassesIndices.get(idPlain), ArrayUtil.EMPTY_INT_ARRAY);
+    int[] classes = myIdToEqClassesIndices.get(varID);
+    if (classes == null) return;
 
     int interruptCount = 0;
 
-    for (int varClassIndex : result) {
+    for (int varClassIndex : classes) {
       EqClass varClass = myEqClasses.get(varClassIndex);
       if ((++interruptCount & 0xf) == 0) {
         ProgressManager.checkCanceled();
@@ -1391,7 +1390,7 @@ public class DfaMemoryStateImpl implements DfaMemoryState {
       DfaVariableValue previousCanonical = varClass.getCanonicalVariable();
       myEqClasses.set(varClassIndex, varClass);
       for (int id : varClass.toNativeArray()) {
-        if (id == idPlain || unwrap(myFactory.getValue(id)).getID() == idPlain) {
+        if (id == varID || unwrap(myFactory.getValue(id)).getID() == varID) {
           varClass.removeValue(id);
         }
       }
@@ -1425,10 +1424,10 @@ public class DfaMemoryStateImpl implements DfaMemoryState {
           assert successfullyConverted;
         }
       }
+      removeFromMap(varID, varClassIndex);
+      checkInvariants();
     }
 
-    removeAllFromMap(idPlain);
-    checkInvariants();
     myCachedNonTrivialEqClasses = null;
     myCachedHash = null;
   }

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

@@ -0,0 +1,15 @@
+class X {
+  void test(int[] arr, int[][] divisorsForAllNums) {
+    for(int i=0; i < arr.length; i++) {
+      int numInArr = arr[i];
+
+      if(i == 0 || <error descr="Operator '<' cannot be applied to 'int', 'int[]'">numInArr < arr</error><error descr="')' expected"><error descr="Unexpected token">[</error></error><error descr="Unexpected token">]</error><error descr="Unexpected token">)</error>
+
+      int divisorsCount = 0;
+      for(int y=numInArr; y > 0; y--) {
+      }
+
+      divisorsForAllNums[i] = new int[0];
+    }
+  }
+}

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

@@ -28,6 +28,8 @@ import com.intellij.testFramework.fixtures.JavaCodeInsightTestFixture;
 import com.intellij.util.containers.ContainerUtil;
 import org.jetbrains.annotations.NotNull;
 
+import java.util.Objects;
+
 /**
  * @author peter
  */
@@ -564,12 +566,12 @@ public class DataFlowInspectionTest extends DataFlowInspectionTestCase {
 
       @Override
       public boolean isImplicitlyNotNullInitialized(@NotNull PsiElement element) {
-        return element instanceof PsiField && ((PsiField)element).getName().startsWith("field");
+        return element instanceof PsiField && ((PsiField)element).getName() != null && ((PsiField)element).getName().startsWith("field");
       }
 
       @Override
       public boolean isClassWithCustomizedInitialization(@NotNull PsiElement element) {
-        return element instanceof PsiClass && ((PsiClass)element).getName().equals("Instrumented");
+        return element instanceof PsiClass && Objects.equals(((PsiClass)element).getName(), "Instrumented");
       }
     }, myFixture.getTestRootDisposable());
     doTest();
@@ -641,4 +643,6 @@ public class DataFlowInspectionTest extends DataFlowInspectionTestCase {
   public void testAssignmentFieldAliasing() { doTest(); }
   public void testNewBoxedNumberEquality() { doTest(); }
   public void testBoxingIncorrectLiteral() { doTest(); }
+
+  public void testIncompleteArrayAccessInLoop() { doTest(); }
 }