private void reportNullableReturns(
      DataFlowInstructionVisitor visitor,
      ProblemsHolder holder,
      Set<PsiElement> reportedAnchors,
      @NotNull PsiElement block) {
    final PsiMethod method = getScopeMethod(block);
    if (method == null || NullableStuffInspectionBase.isNullableNotInferred(method, true)) return;

    boolean notNullRequired = NullableNotNullManager.isNotNull(method);
    if (!notNullRequired && !SUGGEST_NULLABLE_ANNOTATIONS) return;

    PsiType returnType = method.getReturnType();
    // no warnings in void lambdas, where the expression is not returned anyway
    if (block instanceof PsiExpression
        && block.getParent() instanceof PsiLambdaExpression
        && returnType == PsiType.VOID) return;

    // no warnings for Void methods, where only null can be possibly returned
    if (returnType == null || returnType.equalsToText(CommonClassNames.JAVA_LANG_VOID)) return;

    for (PsiElement statement : visitor.getProblems(NullabilityProblem.nullableReturn)) {
      assert statement instanceof PsiExpression;
      final PsiExpression expr = (PsiExpression) statement;
      if (!reportedAnchors.add(expr)) continue;

      if (notNullRequired) {
        final String text =
            isNullLiteralExpression(expr)
                ? InspectionsBundle.message("dataflow.message.return.null.from.notnull")
                : InspectionsBundle.message("dataflow.message.return.nullable.from.notnull");
        holder.registerProblem(expr, text);
      } else if (AnnotationUtil.isAnnotatingApplicable(statement)) {
        final NullableNotNullManager manager =
            NullableNotNullManager.getInstance(expr.getProject());
        final String defaultNullable = manager.getDefaultNullable();
        final String presentableNullable = StringUtil.getShortName(defaultNullable);
        final String text =
            isNullLiteralExpression(expr)
                ? InspectionsBundle.message(
                    "dataflow.message.return.null.from.notnullable", presentableNullable)
                : InspectionsBundle.message(
                    "dataflow.message.return.nullable.from.notnullable", presentableNullable);
        final LocalQuickFix[] fixes =
            PsiTreeUtil.getParentOfType(expr, PsiMethod.class, PsiLambdaExpression.class)
                    instanceof PsiLambdaExpression
                ? LocalQuickFix.EMPTY_ARRAY
                : new LocalQuickFix[] {
                  new AnnotateMethodFix(
                      defaultNullable, ArrayUtil.toStringArray(manager.getNotNulls())) {
                    @Override
                    public int shouldAnnotateBaseMethod(
                        PsiMethod method, PsiMethod superMethod, Project project) {
                      return 1;
                    }
                  }
                };
        holder.registerProblem(expr, text, fixes);
      }
    }
  }
 private void handleBranchingInstruction(
     ProblemsHolder holder,
     StandardInstructionVisitor visitor,
     Set<Instruction> trueSet,
     Set<Instruction> falseSet,
     HashSet<PsiElement> reportedAnchors,
     BranchingInstruction instruction,
     final boolean onTheFly) {
   PsiElement psiAnchor = instruction.getPsiAnchor();
   boolean underBinary = isAtRHSOfBooleanAnd(psiAnchor);
   if (instruction instanceof InstanceofInstruction
       && visitor.isInstanceofRedundant((InstanceofInstruction) instruction)) {
     if (visitor.canBeNull((BinopInstruction) instruction)) {
       holder.registerProblem(
           psiAnchor,
           InspectionsBundle.message("dataflow.message.redundant.instanceof"),
           new RedundantInstanceofFix());
     } else {
       final LocalQuickFix localQuickFix = createSimplifyBooleanExpressionFix(psiAnchor, true);
       holder.registerProblem(
           psiAnchor,
           InspectionsBundle.message(
               underBinary
                   ? "dataflow.message.constant.condition.when.reached"
                   : "dataflow.message.constant.condition",
               Boolean.toString(true)),
           localQuickFix == null ? null : new LocalQuickFix[] {localQuickFix});
     }
   } else if (psiAnchor instanceof PsiSwitchLabelStatement) {
     if (falseSet.contains(instruction)) {
       holder.registerProblem(
           psiAnchor, InspectionsBundle.message("dataflow.message.unreachable.switch.label"));
     }
   } else if (psiAnchor != null
       && !reportedAnchors.contains(psiAnchor)
       && !isFlagCheck(psiAnchor)) {
     boolean evaluatesToTrue = trueSet.contains(instruction);
     final PsiElement parent = psiAnchor.getParent();
     if (parent instanceof PsiAssignmentExpression
         && ((PsiAssignmentExpression) parent).getLExpression() == psiAnchor) {
       holder.registerProblem(
           psiAnchor,
           InspectionsBundle.message(
               "dataflow.message.pointless.assignment.expression",
               Boolean.toString(evaluatesToTrue)),
           createConditionalAssignmentFixes(
               evaluatesToTrue, (PsiAssignmentExpression) parent, onTheFly));
     } else if (!skipReportingConstantCondition(visitor, psiAnchor, evaluatesToTrue)) {
       final LocalQuickFix fix = createSimplifyBooleanExpressionFix(psiAnchor, evaluatesToTrue);
       String message =
           InspectionsBundle.message(
               underBinary
                   ? "dataflow.message.constant.condition.when.reached"
                   : "dataflow.message.constant.condition",
               Boolean.toString(evaluatesToTrue));
       holder.registerProblem(psiAnchor, message, fix == null ? null : new LocalQuickFix[] {fix});
     }
     reportedAnchors.add(psiAnchor);
   }
 }
  private static void reportOptionalOfNullableImprovements(
      ProblemsHolder holder, Set<PsiElement> reportedAnchors, Instruction[] instructions) {
    for (Instruction instruction : instructions) {
      if (instruction instanceof MethodCallInstruction) {
        final PsiExpression[] args = ((MethodCallInstruction) instruction).getArgs();
        if (args.length != 1) continue;

        final PsiExpression expr = args[0];

        if (((MethodCallInstruction) instruction).isOptionalAlwaysNullProblem()) {
          if (!reportedAnchors.add(expr)) continue;
          holder.registerProblem(
              expr,
              "Passing <code>null</code> argument to <code>Optional</code>",
              DfaOptionalSupport.createReplaceOptionalOfNullableWithEmptyFix(expr));
        } else if (((MethodCallInstruction) instruction).isOptionalAlwaysNotNullProblem()) {
          if (!reportedAnchors.add(expr)) continue;
          holder.registerProblem(
              expr,
              "Passing a non-null argument to <code>Optional</code>",
              DfaOptionalSupport.createReplaceOptionalOfNullableWithOfFix());
        }
      }
    }
  }
  private void reportNullableArguments(
      DataFlowInstructionVisitor visitor, ProblemsHolder holder, Set<PsiElement> reportedAnchors) {
    for (PsiElement expr :
        visitor.getProblems(NullabilityProblem.passingNullableToNotNullParameter)) {
      if (!reportedAnchors.add(expr)) continue;

      final String text =
          isNullLiteralExpression(expr)
              ? InspectionsBundle.message("dataflow.message.passing.null.argument")
              : InspectionsBundle.message("dataflow.message.passing.nullable.argument");
      LocalQuickFix[] fixes =
          createNPEFixes((PsiExpression) expr, (PsiExpression) expr, holder.isOnTheFly());
      holder.registerProblem(expr, text, fixes);
    }
  }
 private void reportFieldAccessMayProduceNpe(
     ProblemsHolder holder, PsiElement elementToAssert, PsiExpression expression) {
   if (expression instanceof PsiArrayAccessExpression) {
     LocalQuickFix[] fix =
         createNPEFixes((PsiExpression) elementToAssert, expression, holder.isOnTheFly());
     holder.registerProblem(
         expression, InspectionsBundle.message("dataflow.message.npe.array.access"), fix);
   } else {
     LocalQuickFix[] fix =
         createNPEFixes((PsiExpression) elementToAssert, expression, holder.isOnTheFly());
     assert elementToAssert != null;
     holder.registerProblem(
         elementToAssert, InspectionsBundle.message("dataflow.message.npe.field.access"), fix);
   }
 }
 private static void reportUnboxedNullables(
     DataFlowInstructionVisitor visitor, ProblemsHolder holder, Set<PsiElement> reportedAnchors) {
   for (PsiElement expr : visitor.getProblems(NullabilityProblem.unboxingNullable)) {
     if (!reportedAnchors.add(expr)) continue;
     holder.registerProblem(expr, InspectionsBundle.message("dataflow.message.unboxing"));
   }
 }
  private void analyzeDfaWithNestedClosures(
      PsiElement scope,
      ProblemsHolder holder,
      StandardDataFlowRunner dfaRunner,
      Collection<DfaMemoryState> initialStates) {
    final DataFlowInstructionVisitor visitor = new DataFlowInstructionVisitor(dfaRunner);
    final RunnerResult rc =
        dfaRunner.analyzeMethod(scope, visitor, IGNORE_ASSERT_STATEMENTS, initialStates);
    if (rc == RunnerResult.OK) {
      createDescription(dfaRunner, holder, visitor);

      MultiMap<PsiElement, DfaMemoryState> nestedClosures = dfaRunner.getNestedClosures();
      for (PsiElement closure : nestedClosures.keySet()) {
        analyzeDfaWithNestedClosures(closure, holder, dfaRunner, nestedClosures.get(closure));
      }
    } else if (rc == RunnerResult.TOO_COMPLEX) {
      if (scope.getParent() instanceof PsiMethod) {
        PsiMethod method = (PsiMethod) scope.getParent();
        final PsiIdentifier name = method.getNameIdentifier();
        if (name != null) { // Might be null for synthetic methods like JSP page.
          holder.registerProblem(
              name,
              InspectionsBundle.message("dataflow.too.complex"),
              ProblemHighlightType.WEAK_WARNING);
        }
      }
    }
  }
 private static void reportCastMayFail(ProblemsHolder holder, TypeCastInstruction instruction) {
   PsiTypeCastExpression typeCast = instruction.getCastExpression();
   PsiExpression operand = typeCast.getOperand();
   PsiTypeElement castType = typeCast.getCastType();
   assert castType != null;
   assert operand != null;
   holder.registerProblem(
       castType, InspectionsBundle.message("dataflow.message.cce", operand.getText()));
 }
  private void reportCallMayProduceNpe(
      ProblemsHolder holder, PsiMethodCallExpression callExpression, boolean onTheFly) {
    LocalQuickFix[] fix =
        createNPEFixes(
            callExpression.getMethodExpression().getQualifierExpression(),
            callExpression,
            onTheFly);

    holder.registerProblem(
        callExpression, InspectionsBundle.message("dataflow.message.npe.method.invocation"), fix);
  }
  private static void reportNullableAssignments(
      DataFlowInstructionVisitor visitor, ProblemsHolder holder, Set<PsiElement> reportedAnchors) {
    for (PsiElement expr : visitor.getProblems(NullabilityProblem.assigningToNotNull)) {
      if (!reportedAnchors.add(expr)) continue;

      final String text =
          isNullLiteralExpression(expr)
              ? InspectionsBundle.message("dataflow.message.assigning.null")
              : InspectionsBundle.message("dataflow.message.assigning.nullable");
      holder.registerProblem(expr, text);
    }
  }
  private static void reportNullableReturns(
      StandardDataFlowRunner runner,
      DataFlowInstructionVisitor visitor,
      ProblemsHolder holder,
      Set<PsiElement> reportedAnchors) {
    for (PsiElement statement : visitor.getProblems(NullabilityProblem.nullableReturn)) {
      assert statement instanceof PsiExpression;
      final PsiExpression expr = (PsiExpression) statement;
      if (!reportedAnchors.add(expr)) continue;

      if (runner.isInNotNullMethod()) {
        final String text =
            isNullLiteralExpression(expr)
                ? InspectionsBundle.message("dataflow.message.return.null.from.notnull")
                : InspectionsBundle.message("dataflow.message.return.nullable.from.notnull");
        holder.registerProblem(expr, text);
      } else if (AnnotationUtil.isAnnotatingApplicable(statement)) {
        final NullableNotNullManager manager =
            NullableNotNullManager.getInstance(expr.getProject());
        final String defaultNullable = manager.getDefaultNullable();
        final String presentableNullable = StringUtil.getShortName(defaultNullable);
        final String text =
            isNullLiteralExpression(expr)
                ? InspectionsBundle.message(
                    "dataflow.message.return.null.from.notnullable", presentableNullable)
                : InspectionsBundle.message(
                    "dataflow.message.return.nullable.from.notnullable", presentableNullable);
        holder.registerProblem(
            expr,
            text,
            new AnnotateMethodFix(defaultNullable, ArrayUtil.toStringArray(manager.getNotNulls())) {
              @Override
              public int shouldAnnotateBaseMethod(
                  PsiMethod method, PsiMethod superMethod, Project project) {
                return 1;
              }
            });
      }
    }
  }
  private void reportNullableArgumentsPassedToNonAnnotated(
      DataFlowInstructionVisitor visitor, ProblemsHolder holder, Set<PsiElement> reportedAnchors) {
    for (PsiElement expr :
        visitor.getProblems(NullabilityProblem.passingNullableArgumentToNonAnnotatedParameter)) {
      if (reportedAnchors.contains(expr)) continue;

      final String text =
          isNullLiteralExpression(expr)
              ? "Passing <code>null</code> argument to non annotated parameter"
              : "Argument <code>#ref</code> #loc might be null but passed to non annotated parameter";
      LocalQuickFix[] fixes =
          createNPEFixes((PsiExpression) expr, (PsiExpression) expr, holder.isOnTheFly());
      final PsiElement parent = expr.getParent();
      if (parent instanceof PsiExpressionList) {
        final int idx = ArrayUtilRt.find(((PsiExpressionList) parent).getExpressions(), expr);
        if (idx > -1) {
          final PsiElement gParent = parent.getParent();
          if (gParent instanceof PsiCallExpression) {
            final PsiMethod psiMethod = ((PsiCallExpression) gParent).resolveMethod();
            if (psiMethod != null
                && psiMethod.getManager().isInProject(psiMethod)
                && AnnotationUtil.isAnnotatingApplicable(psiMethod)) {
              final PsiParameter[] parameters = psiMethod.getParameterList().getParameters();
              if (idx < parameters.length) {
                final AddNullableAnnotationFix addNullableAnnotationFix =
                    new AddNullableAnnotationFix(parameters[idx]);
                fixes =
                    fixes == null
                        ? new LocalQuickFix[] {addNullableAnnotationFix}
                        : ArrayUtil.append(fixes, addNullableAnnotationFix);
                holder.registerProblem(expr, text, fixes);
                reportedAnchors.add(expr);
              }
            }
          }
        }
      }
    }
  }
  private static void reportConstantReferenceValues(
      ProblemsHolder holder, StandardInstructionVisitor visitor, Set<PsiElement> reportedAnchors) {
    for (Pair<PsiReferenceExpression, DfaConstValue> pair : visitor.getConstantReferenceValues()) {
      PsiReferenceExpression ref = pair.first;
      if (!reportedAnchors.add(ref)) {
        continue;
      }

      final Object value = pair.second.getValue();
      PsiVariable constant = pair.second.getConstant();
      final String presentableName = constant != null ? constant.getName() : String.valueOf(value);
      final String exprText = getConstantValueText(value, constant);
      if (presentableName == null || exprText == null) {
        continue;
      }

      holder.registerProblem(
          ref,
          "Value <code>#ref</code> #loc is always '" + presentableName + "'",
          new LocalQuickFix() {
            @NotNull
            @Override
            public String getName() {
              return "Replace with '" + presentableName + "'";
            }

            @NotNull
            @Override
            public String getFamilyName() {
              return "Replace with constant value";
            }

            @Override
            public void applyFix(@NotNull Project project, @NotNull ProblemDescriptor descriptor) {
              if (!FileModificationService.getInstance()
                  .preparePsiElementsForWrite(descriptor.getPsiElement())) {
                return;
              }

              JavaPsiFacade facade = JavaPsiFacade.getInstance(project);
              PsiElement newElement =
                  descriptor
                      .getPsiElement()
                      .replace(facade.getElementFactory().createExpressionFromText(exprText, null));
              newElement =
                  JavaCodeStyleManager.getInstance(project).shortenClassReferences(newElement);
              if (newElement instanceof PsiJavaCodeReferenceElement) {
                PsiJavaCodeReferenceElement ref = (PsiJavaCodeReferenceElement) newElement;
                PsiElement target = ref.resolve();
                String shortName = ref.getReferenceName();
                if (target != null
                    && shortName != null
                    && ref.isQualified()
                    && facade.getResolveHelper().resolveReferencedVariable(shortName, newElement)
                        == target) {
                  newElement.replace(
                      facade.getElementFactory().createExpressionFromText(shortName, null));
                }
              }
            }
          });
    }
  }
  private void createDescription(
      StandardDataFlowRunner runner, ProblemsHolder holder, DataFlowInstructionVisitor visitor) {
    Pair<Set<Instruction>, Set<Instruction>> constConditions =
        runner.getConstConditionalExpressions();
    Set<Instruction> trueSet = constConditions.getFirst();
    Set<Instruction> falseSet = constConditions.getSecond();

    ArrayList<Instruction> allProblems = new ArrayList<Instruction>();
    allProblems.addAll(trueSet);
    allProblems.addAll(falseSet);
    allProblems.addAll(runner.getCCEInstructions());
    allProblems.addAll(StandardDataFlowRunner.getRedundantInstanceofs(runner, visitor));

    HashSet<PsiElement> reportedAnchors = new HashSet<PsiElement>();
    for (PsiElement element : visitor.getProblems(NullabilityProblem.callNPE)) {
      if (reportedAnchors.add(element)) {
        reportCallMayProduceNpe(holder, (PsiMethodCallExpression) element, holder.isOnTheFly());
      }
    }
    for (PsiElement element : visitor.getProblems(NullabilityProblem.fieldAccessNPE)) {
      if (reportedAnchors.add(element)) {
        PsiElement parent = element.getParent();
        PsiElement fieldAccess =
            parent instanceof PsiArrayAccessExpression || parent instanceof PsiReferenceExpression
                ? parent
                : element;
        reportFieldAccessMayProduceNpe(holder, element, (PsiExpression) fieldAccess);
      }
    }

    for (Instruction instruction : allProblems) {
      if (instruction instanceof TypeCastInstruction
          && reportedAnchors.add(
              ((TypeCastInstruction) instruction).getCastExpression().getCastType())) {
        reportCastMayFail(holder, (TypeCastInstruction) instruction);
      } else if (instruction instanceof BranchingInstruction) {
        handleBranchingInstruction(
            holder,
            visitor,
            trueSet,
            falseSet,
            reportedAnchors,
            (BranchingInstruction) instruction);
      }
    }

    reportNullableArguments(visitor, holder, reportedAnchors);
    reportNullableAssignments(visitor, holder, reportedAnchors);
    reportUnboxedNullables(visitor, holder, reportedAnchors);
    if (!runner.isInNullableMethod()
        && runner.isInMethod()
        && (runner.isInNotNullMethod() || SUGGEST_NULLABLE_ANNOTATIONS)) {
      reportNullableReturns(runner, visitor, holder, reportedAnchors);
    }
    if (SUGGEST_NULLABLE_ANNOTATIONS) {
      reportNullableArgumentsPassedToNonAnnotated(visitor, holder, reportedAnchors);
    }

    if (REPORT_CONSTANT_REFERENCE_VALUES) {
      reportConstantReferenceValues(holder, visitor, reportedAnchors);
    }
  }
  private static void reportConstantReferenceValues(
      ProblemsHolder holder, StandardInstructionVisitor visitor, Set<PsiElement> reportedAnchors) {
    for (Pair<PsiReferenceExpression, DfaConstValue> pair : visitor.getConstantReferenceValues()) {
      PsiReferenceExpression ref = pair.first;
      if (ref.getParent() instanceof PsiReferenceExpression || !reportedAnchors.add(ref)) {
        continue;
      }

      final Object value = pair.second.getValue();
      PsiVariable constant = pair.second.getConstant();
      final String presentableName = constant != null ? constant.getName() : String.valueOf(value);
      final String exprText = String.valueOf(value);
      if (presentableName == null || exprText == null) {
        continue;
      }

      holder.registerProblem(
          ref,
          "Value <code>#ref</code> #loc is always '" + presentableName + "'",
          new LocalQuickFix() {
            @NotNull
            @Override
            public String getName() {
              return "Replace with '" + presentableName + "'";
            }

            @NotNull
            @Override
            public String getFamilyName() {
              return "Replace with constant value";
            }

            @Override
            public void applyFix(@NotNull Project project, @NotNull ProblemDescriptor descriptor) {
              if (!FileModificationService.getInstance()
                  .preparePsiElementsForWrite(descriptor.getPsiElement())) {
                return;
              }

              PsiElement problemElement = descriptor.getPsiElement();
              if (problemElement == null) return;

              PsiMethodCallExpression call =
                  problemElement.getParent() instanceof PsiExpressionList
                          && problemElement.getParent().getParent()
                              instanceof PsiMethodCallExpression
                      ? (PsiMethodCallExpression) problemElement.getParent().getParent()
                      : null;
              PsiMethod targetMethod = call == null ? null : call.resolveMethod();

              JavaPsiFacade facade = JavaPsiFacade.getInstance(project);
              problemElement.replace(
                  facade.getElementFactory().createExpressionFromText(exprText, null));

              if (targetMethod != null) {
                ExtractMethodUtil.addCastsToEnsureResolveTarget(targetMethod, call);
              }
            }
          });
    }
  }