001    /*
002     * Copyright 2010-2015 JetBrains s.r.o.
003     *
004     * Licensed under the Apache License, Version 2.0 (the "License");
005     * you may not use this file except in compliance with the License.
006     * You may obtain a copy of the License at
007     *
008     * http://www.apache.org/licenses/LICENSE-2.0
009     *
010     * Unless required by applicable law or agreed to in writing, software
011     * distributed under the License is distributed on an "AS IS" BASIS,
012     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013     * See the License for the specific language governing permissions and
014     * limitations under the License.
015     */
016    
017    package org.jetbrains.kotlin.cfg;
018    
019    import com.google.common.collect.Lists;
020    import com.google.common.collect.Maps;
021    import com.google.common.collect.Sets;
022    import com.intellij.psi.PsiElement;
023    import com.intellij.psi.tree.IElementType;
024    import com.intellij.psi.util.PsiTreeUtil;
025    import kotlin.Unit;
026    import kotlin.jvm.functions.Function1;
027    import kotlin.jvm.functions.Function3;
028    import org.jetbrains.annotations.NotNull;
029    import org.jetbrains.annotations.Nullable;
030    import org.jetbrains.kotlin.builtins.KotlinBuiltIns;
031    import org.jetbrains.kotlin.cfg.pseudocode.PseudoValue;
032    import org.jetbrains.kotlin.cfg.pseudocode.Pseudocode;
033    import org.jetbrains.kotlin.cfg.pseudocode.PseudocodeUtil;
034    import org.jetbrains.kotlin.cfg.pseudocode.PseudocodeUtilsKt;
035    import org.jetbrains.kotlin.cfg.pseudocode.instructions.Instruction;
036    import org.jetbrains.kotlin.cfg.pseudocode.instructions.InstructionVisitor;
037    import org.jetbrains.kotlin.cfg.pseudocode.instructions.KtElementInstruction;
038    import org.jetbrains.kotlin.cfg.pseudocode.instructions.eval.*;
039    import org.jetbrains.kotlin.cfg.pseudocode.instructions.jumps.*;
040    import org.jetbrains.kotlin.cfg.pseudocode.instructions.special.LocalFunctionDeclarationInstruction;
041    import org.jetbrains.kotlin.cfg.pseudocode.instructions.special.MarkInstruction;
042    import org.jetbrains.kotlin.cfg.pseudocode.instructions.special.SubroutineExitInstruction;
043    import org.jetbrains.kotlin.cfg.pseudocode.instructions.special.VariableDeclarationInstruction;
044    import org.jetbrains.kotlin.cfg.pseudocodeTraverser.Edges;
045    import org.jetbrains.kotlin.cfg.pseudocodeTraverser.PseudocodeTraverserKt;
046    import org.jetbrains.kotlin.cfg.pseudocodeTraverser.TraversalOrder;
047    import org.jetbrains.kotlin.descriptors.*;
048    import org.jetbrains.kotlin.descriptors.impl.SyntheticFieldDescriptorKt;
049    import org.jetbrains.kotlin.diagnostics.Diagnostic;
050    import org.jetbrains.kotlin.diagnostics.DiagnosticFactory;
051    import org.jetbrains.kotlin.diagnostics.Errors;
052    import org.jetbrains.kotlin.idea.MainFunctionDetector;
053    import org.jetbrains.kotlin.lexer.KtTokens;
054    import org.jetbrains.kotlin.psi.*;
055    import org.jetbrains.kotlin.resolve.*;
056    import org.jetbrains.kotlin.resolve.bindingContextUtil.BindingContextUtilsKt;
057    import org.jetbrains.kotlin.resolve.calls.callUtil.CallUtilKt;
058    import org.jetbrains.kotlin.resolve.calls.model.ResolvedCall;
059    import org.jetbrains.kotlin.resolve.calls.resolvedCallUtil.ResolvedCallUtilKt;
060    import org.jetbrains.kotlin.resolve.scopes.receivers.ReceiverValue;
061    import org.jetbrains.kotlin.types.KotlinType;
062    import org.jetbrains.kotlin.types.expressions.ExpressionTypingUtils;
063    
064    import java.util.*;
065    
066    import static org.jetbrains.kotlin.cfg.TailRecursionKind.*;
067    import static org.jetbrains.kotlin.cfg.VariableUseState.*;
068    import static org.jetbrains.kotlin.diagnostics.Errors.*;
069    import static org.jetbrains.kotlin.diagnostics.Errors.UNREACHABLE_CODE;
070    import static org.jetbrains.kotlin.resolve.BindingContext.*;
071    import static org.jetbrains.kotlin.types.TypeUtils.*;
072    
073    public class ControlFlowInformationProvider {
074    
075        private final KtElement subroutine;
076        private final Pseudocode pseudocode;
077        private final BindingTrace trace;
078        private PseudocodeVariablesData pseudocodeVariablesData;
079    
080        private ControlFlowInformationProvider(
081                @NotNull KtElement declaration,
082                @NotNull BindingTrace trace,
083                @NotNull Pseudocode pseudocode
084        ) {
085            this.subroutine = declaration;
086            this.trace = trace;
087            this.pseudocode = pseudocode;
088        }
089    
090        public ControlFlowInformationProvider(
091                @NotNull KtElement declaration,
092                @NotNull BindingTrace trace
093        ) {
094            this(declaration, trace, new ControlFlowProcessor(trace).generatePseudocode(declaration));
095        }
096    
097        public PseudocodeVariablesData getPseudocodeVariablesData() {
098            if (pseudocodeVariablesData == null) {
099                pseudocodeVariablesData = new PseudocodeVariablesData(pseudocode, trace.getBindingContext());
100            }
101            return pseudocodeVariablesData;
102        }
103    
104        public void checkForLocalClassOrObjectMode() {
105            // Local classes and objects are analyzed twice: when TopDownAnalyzer processes it and as a part of its container.
106            // Almost all checks can be done when the container is analyzed
107            // except recording initialized variables (this information is needed for DeclarationChecker).
108            recordInitializedVariables();
109        }
110    
111        public void checkDeclaration() {
112    
113            recordInitializedVariables();
114    
115            checkLocalFunctions();
116    
117            markUninitializedVariables();
118    
119            markUnusedVariables();
120    
121            markStatements();
122    
123            markUnusedExpressions();
124    
125            checkIfExpressions();
126    
127            checkWhenExpressions();
128        }
129    
130        public void checkFunction(@Nullable KotlinType expectedReturnType) {
131            UnreachableCode unreachableCode = collectUnreachableCode();
132            reportUnreachableCode(unreachableCode);
133    
134            if (subroutine instanceof KtFunctionLiteral) return;
135    
136            checkDefiniteReturn(expectedReturnType != null ? expectedReturnType : NO_EXPECTED_TYPE, unreachableCode);
137    
138            markTailCalls();
139        }
140    
141        private void collectReturnExpressions(@NotNull final Collection<KtElement> returnedExpressions) {
142            final Set<Instruction> instructions = Sets.newHashSet(pseudocode.getInstructions());
143            SubroutineExitInstruction exitInstruction = pseudocode.getExitInstruction();
144            for (Instruction previousInstruction : exitInstruction.getPreviousInstructions()) {
145                previousInstruction.accept(new InstructionVisitor() {
146                    @Override
147                    public void visitReturnValue(@NotNull ReturnValueInstruction instruction) {
148                        if (instructions.contains(instruction)) { //exclude non-local return expressions
149                            returnedExpressions.add(instruction.getElement());
150                        }
151                    }
152    
153                    @Override
154                    public void visitReturnNoValue(@NotNull ReturnNoValueInstruction instruction) {
155                        if (instructions.contains(instruction)) {
156                            returnedExpressions.add(instruction.getElement());
157                        }
158                    }
159    
160    
161                    @Override
162                    public void visitJump(@NotNull AbstractJumpInstruction instruction) {
163                        // Nothing
164                    }
165    
166                    @Override
167                    public void visitUnconditionalJump(@NotNull UnconditionalJumpInstruction instruction) {
168                        redirectToPrevInstructions(instruction);
169                    }
170    
171                    private void redirectToPrevInstructions(Instruction instruction) {
172                        for (Instruction previousInstruction : instruction.getPreviousInstructions()) {
173                            previousInstruction.accept(this);
174                        }
175                    }
176    
177                    @Override
178                    public void visitNondeterministicJump(@NotNull NondeterministicJumpInstruction instruction) {
179                        redirectToPrevInstructions(instruction);
180                    }
181    
182                    @Override
183                    public void visitMarkInstruction(@NotNull MarkInstruction instruction) {
184                        redirectToPrevInstructions(instruction);
185                    }
186    
187                    @Override
188                    public void visitInstruction(@NotNull Instruction instruction) {
189                        if (instruction instanceof KtElementInstruction) {
190                            KtElementInstruction elementInstruction = (KtElementInstruction) instruction;
191                            returnedExpressions.add(elementInstruction.getElement());
192                        }
193                        else {
194                            throw new IllegalStateException(instruction + " precedes the exit point");
195                        }
196                    }
197                });
198            }
199        }
200    
201        private void checkLocalFunctions() {
202            for (LocalFunctionDeclarationInstruction localDeclarationInstruction : pseudocode.getLocalDeclarations()) {
203                KtElement element = localDeclarationInstruction.getElement();
204                if (element instanceof KtDeclarationWithBody) {
205                    KtDeclarationWithBody localDeclaration = (KtDeclarationWithBody) element;
206    
207                    CallableDescriptor functionDescriptor =
208                            (CallableDescriptor) trace.getBindingContext().get(BindingContext.DECLARATION_TO_DESCRIPTOR, localDeclaration);
209                    KotlinType expectedType = functionDescriptor != null ? functionDescriptor.getReturnType() : null;
210    
211                    ControlFlowInformationProvider providerForLocalDeclaration =
212                            new ControlFlowInformationProvider(localDeclaration, trace, localDeclarationInstruction.getBody());
213    
214                    providerForLocalDeclaration.checkFunction(expectedType);
215                }
216            }
217        }
218    
219        public void checkDefiniteReturn(final @NotNull KotlinType expectedReturnType, @NotNull final UnreachableCode unreachableCode) {
220            assert subroutine instanceof KtDeclarationWithBody;
221            KtDeclarationWithBody function = (KtDeclarationWithBody) subroutine;
222    
223            if (!function.hasBody()) return;
224    
225            List<KtElement> returnedExpressions = Lists.newArrayList();
226            collectReturnExpressions(returnedExpressions);
227    
228            final boolean blockBody = function.hasBlockBody();
229    
230            final boolean[] noReturnError = new boolean[] { false };
231            for (KtElement returnedExpression : returnedExpressions) {
232                returnedExpression.accept(new KtVisitorVoid() {
233                    @Override
234                    public void visitReturnExpression(@NotNull KtReturnExpression expression) {
235                        if (!blockBody) {
236                            trace.report(RETURN_IN_FUNCTION_WITH_EXPRESSION_BODY.on(expression));
237                        }
238                    }
239    
240                    @Override
241                    public void visitKtElement(@NotNull KtElement element) {
242                        if (!(element instanceof KtExpression || element instanceof KtWhenCondition)) return;
243    
244                        if (blockBody && !noExpectedType(expectedReturnType)
245                                && !KotlinBuiltIns.isUnit(expectedReturnType)
246                                && !unreachableCode.getElements().contains(element)) {
247                            noReturnError[0] = true;
248                        }
249                    }
250                });
251            }
252            if (noReturnError[0]) {
253                trace.report(NO_RETURN_IN_FUNCTION_WITH_BLOCK_BODY.on(function));
254            }
255        }
256    
257        private void reportUnreachableCode(@NotNull UnreachableCode unreachableCode) {
258            for (KtElement element : unreachableCode.getElements()) {
259                trace.report(UNREACHABLE_CODE.on(element, unreachableCode.getUnreachableTextRanges(element)));
260                trace.record(BindingContext.UNREACHABLE_CODE, element, true);
261            }
262        }
263    
264        @NotNull
265        private UnreachableCode collectUnreachableCode() {
266            Set<KtElement> reachableElements = Sets.newHashSet();
267            Set<KtElement> unreachableElements = Sets.newHashSet();
268            for (Instruction instruction : pseudocode.getInstructionsIncludingDeadCode()) {
269                if (!(instruction instanceof KtElementInstruction)
270                        || instruction instanceof LoadUnitValueInstruction
271                        || instruction instanceof MergeInstruction
272                        || (instruction instanceof MagicInstruction && ((MagicInstruction) instruction).getSynthetic())) continue;
273    
274                KtElement element = ((KtElementInstruction) instruction).getElement();
275    
276                if (instruction instanceof JumpInstruction) {
277                    boolean isJumpElement = element instanceof KtBreakExpression
278                                            || element instanceof KtContinueExpression
279                                            || element instanceof KtReturnExpression
280                                            || element instanceof KtThrowExpression;
281                    if (!isJumpElement) continue;
282                }
283    
284                if (instruction.getDead()) {
285                    unreachableElements.add(element);
286                }
287                else {
288                    reachableElements.add(element);
289                }
290            }
291            return new UnreachableCodeImpl(reachableElements, unreachableElements);
292        }
293    
294    ////////////////////////////////////////////////////////////////////////////////
295    //  Uninitialized variables analysis
296    
297        public void markUninitializedVariables() {
298            final Collection<VariableDescriptor> varWithUninitializedErrorGenerated = Sets.newHashSet();
299            final Collection<VariableDescriptor> varWithValReassignErrorGenerated = Sets.newHashSet();
300            final boolean processClassOrObject = subroutine instanceof KtClassOrObject;
301    
302            PseudocodeVariablesData pseudocodeVariablesData = getPseudocodeVariablesData();
303            Map<Instruction, Edges<InitControlFlowInfo>> initializers =
304                    pseudocodeVariablesData.getVariableInitializers();
305            final Set<VariableDescriptor> declaredVariables = pseudocodeVariablesData.getDeclaredVariables(pseudocode, true);
306            final LexicalScopeVariableInfo lexicalScopeVariableInfo = pseudocodeVariablesData.getLexicalScopeVariableInfo();
307    
308            final Map<Instruction, DiagnosticFactory<?>> reportedDiagnosticMap = Maps.newHashMap();
309    
310            PseudocodeTraverserKt.traverse(
311                    pseudocode, TraversalOrder.FORWARD, initializers,
312                    new InstructionDataAnalyzeStrategy<Map<VariableDescriptor, VariableControlFlowState>>() {
313                        @Override
314                        public void execute(
315                                @NotNull Instruction instruction,
316                                @Nullable Map<VariableDescriptor, VariableControlFlowState> in,
317                                @Nullable Map<VariableDescriptor, VariableControlFlowState> out
318                        ) {
319                            assert in != null && out != null;
320                            VariableInitContext ctxt =
321                                    new VariableInitContext(instruction, reportedDiagnosticMap, in, out, lexicalScopeVariableInfo);
322                            if (ctxt.variableDescriptor == null) return;
323                            if (instruction instanceof ReadValueInstruction) {
324                                ReadValueInstruction readValueInstruction = (ReadValueInstruction) instruction;
325                                KtElement element = readValueInstruction.getElement();
326                                if (PseudocodeUtil.isThisOrNoDispatchReceiver(readValueInstruction, trace.getBindingContext()) &&
327                                    declaredVariables.contains(ctxt.variableDescriptor)) {
328                                    checkIsInitialized(ctxt, element, varWithUninitializedErrorGenerated);
329                                }
330                                return;
331                            }
332                            if (!(instruction instanceof WriteValueInstruction)) return;
333                            WriteValueInstruction writeValueInstruction = (WriteValueInstruction) instruction;
334                            KtElement element = writeValueInstruction.getLValue();
335                            if (!(element instanceof KtExpression)) return;
336                            boolean error = checkValReassignment(ctxt, (KtExpression) element, writeValueInstruction,
337                                                                 varWithValReassignErrorGenerated);
338                            if (!error && processClassOrObject) {
339                                error = checkAssignmentBeforeDeclaration(ctxt, (KtExpression) element);
340                            }
341                            if (!error && processClassOrObject) {
342                                checkInitializationForCustomSetter(ctxt, (KtExpression) element);
343                            }
344                        }
345                    }
346            );
347        }
348    
349        public void recordInitializedVariables() {
350            PseudocodeVariablesData pseudocodeVariablesData = getPseudocodeVariablesData();
351            Pseudocode pseudocode = pseudocodeVariablesData.getPseudocode();
352            Map<Instruction, Edges<InitControlFlowInfo>> initializers = pseudocodeVariablesData.getVariableInitializers();
353            recordInitializedVariables(pseudocode, initializers);
354            for (LocalFunctionDeclarationInstruction instruction : pseudocode.getLocalDeclarations()) {
355                recordInitializedVariables(instruction.getBody(), initializers);
356            }
357        }
358    
359        private boolean isDefinitelyInitialized(@NotNull PropertyDescriptor propertyDescriptor) {
360            if (propertyDescriptor.isLateInit()) return true;
361            if (trace.get(BACKING_FIELD_REQUIRED, propertyDescriptor) == Boolean.TRUE) return false;
362            PsiElement property = DescriptorToSourceUtils.descriptorToDeclaration(propertyDescriptor);
363            if (property instanceof KtProperty && ((KtProperty) property).hasDelegate()) return false;
364            return true;
365        }
366    
367        private void checkIsInitialized(
368                @NotNull VariableInitContext ctxt,
369                @NotNull KtElement element,
370                @NotNull Collection<VariableDescriptor> varWithUninitializedErrorGenerated
371        ) {
372            if (!(element instanceof KtSimpleNameExpression)) return;
373    
374    
375            boolean isDefinitelyInitialized = ctxt.exitInitState.definitelyInitialized();
376            VariableDescriptor variableDescriptor = ctxt.variableDescriptor;
377            if (!isDefinitelyInitialized && variableDescriptor instanceof PropertyDescriptor) {
378                isDefinitelyInitialized = isDefinitelyInitialized((PropertyDescriptor) variableDescriptor);
379            }
380            if (!isDefinitelyInitialized && !varWithUninitializedErrorGenerated.contains(variableDescriptor)) {
381                if (!(variableDescriptor instanceof PropertyDescriptor)) {
382                    varWithUninitializedErrorGenerated.add(variableDescriptor);
383                }
384                if (variableDescriptor instanceof ValueParameterDescriptor) {
385                    report(Errors.UNINITIALIZED_PARAMETER.on((KtSimpleNameExpression) element,
386                                                             (ValueParameterDescriptor) variableDescriptor), ctxt);
387                }
388                else {
389                    report(Errors.UNINITIALIZED_VARIABLE.on((KtSimpleNameExpression) element, variableDescriptor), ctxt);
390                }
391            }
392        }
393    
394        private boolean checkValReassignment(
395                @NotNull VariableInitContext ctxt,
396                @NotNull KtExpression expression,
397                @NotNull WriteValueInstruction writeValueInstruction,
398                @NotNull Collection<VariableDescriptor> varWithValReassignErrorGenerated
399        ) {
400            VariableDescriptor variableDescriptor = ctxt.variableDescriptor;
401            PropertyDescriptor propertyDescriptor = SyntheticFieldDescriptorKt.getReferencedProperty(variableDescriptor);
402            if (KtPsiUtil.isBackingFieldReference(variableDescriptor) && propertyDescriptor != null) {
403                KtPropertyAccessor accessor = PsiTreeUtil.getParentOfType(expression, KtPropertyAccessor.class);
404                if (accessor != null) {
405                    DeclarationDescriptor accessorDescriptor = trace.get(BindingContext.DECLARATION_TO_DESCRIPTOR, accessor);
406                    if (propertyDescriptor.getGetter() == accessorDescriptor) {
407                        //val can be reassigned through backing field inside its own getter
408                        return false;
409                    }
410                }
411            }
412    
413            boolean mayBeInitializedNotHere = ctxt.enterInitState.mayBeInitialized();
414            boolean hasBackingField = true;
415            if (variableDescriptor instanceof PropertyDescriptor) {
416                hasBackingField = trace.get(BindingContext.BACKING_FIELD_REQUIRED, (PropertyDescriptor) variableDescriptor);
417            }
418            if (variableDescriptor.isVar() && variableDescriptor instanceof PropertyDescriptor) {
419                DeclarationDescriptor descriptor = BindingContextUtils.getEnclosingDescriptor(trace.getBindingContext(), expression);
420                PropertySetterDescriptor setterDescriptor = ((PropertyDescriptor) variableDescriptor).getSetter();
421    
422                ResolvedCall<? extends CallableDescriptor> resolvedCall = CallUtilKt.getResolvedCall(expression, trace.getBindingContext());
423                ReceiverValue receiverValue = null;
424                if (resolvedCall != null) {
425                    receiverValue = resolvedCall.getDispatchReceiver();
426                }
427    
428                if (Visibilities.isVisible(receiverValue, variableDescriptor, descriptor) && setterDescriptor != null
429                        && !Visibilities.isVisible(receiverValue, setterDescriptor, descriptor)) {
430                    report(Errors.INVISIBLE_SETTER.on(expression, variableDescriptor, setterDescriptor.getVisibility(),
431                                                      setterDescriptor), ctxt);
432                    return true;
433                }
434            }
435            boolean isThisOrNoDispatchReceiver =
436                    PseudocodeUtil.isThisOrNoDispatchReceiver(writeValueInstruction, trace.getBindingContext());
437            if ((mayBeInitializedNotHere || !hasBackingField || !isThisOrNoDispatchReceiver) && !variableDescriptor.isVar()) {
438                boolean hasReassignMethodReturningUnit = false;
439                KtSimpleNameExpression operationReference = null;
440                PsiElement parent = expression.getParent();
441                if (parent instanceof KtBinaryExpression) {
442                    operationReference = ((KtBinaryExpression) parent).getOperationReference();
443                }
444                else if (parent instanceof KtUnaryExpression) {
445                    operationReference = ((KtUnaryExpression) parent).getOperationReference();
446                }
447                if (operationReference != null) {
448                    DeclarationDescriptor descriptor = trace.get(BindingContext.REFERENCE_TARGET, operationReference);
449                    if (descriptor instanceof FunctionDescriptor) {
450                        if (KotlinBuiltIns.isUnit(((FunctionDescriptor) descriptor).getReturnType())) {
451                            hasReassignMethodReturningUnit = true;
452                        }
453                    }
454                    if (descriptor == null) {
455                        Collection<? extends DeclarationDescriptor> descriptors =
456                                trace.get(BindingContext.AMBIGUOUS_REFERENCE_TARGET, operationReference);
457                        if (descriptors != null) {
458                            for (DeclarationDescriptor referenceDescriptor : descriptors) {
459                                if (KotlinBuiltIns.isUnit(((FunctionDescriptor) referenceDescriptor).getReturnType())) {
460                                    hasReassignMethodReturningUnit = true;
461                                }
462                            }
463                        }
464                    }
465                }
466                if (!hasReassignMethodReturningUnit) {
467                    if (!isThisOrNoDispatchReceiver || !varWithValReassignErrorGenerated.contains(variableDescriptor)) {
468                        report(Errors.VAL_REASSIGNMENT.on(expression, variableDescriptor), ctxt);
469                    }
470                    if (isThisOrNoDispatchReceiver) {
471                        // try to get rid of repeating VAL_REASSIGNMENT diagnostic only for vars with no receiver
472                        // or when receiver is this
473                        varWithValReassignErrorGenerated.add(variableDescriptor);
474                    }
475                    return true;
476                }
477            }
478            return false;
479        }
480    
481        private boolean checkAssignmentBeforeDeclaration(@NotNull VariableInitContext ctxt, @NotNull KtExpression expression) {
482            if (!ctxt.enterInitState.isDeclared() && !ctxt.exitInitState.isDeclared()
483                && !ctxt.enterInitState.mayBeInitialized() && ctxt.exitInitState.mayBeInitialized()) {
484                report(Errors.INITIALIZATION_BEFORE_DECLARATION.on(expression, ctxt.variableDescriptor), ctxt);
485                return true;
486            }
487            return false;
488        }
489    
490        private boolean checkInitializationForCustomSetter(@NotNull VariableInitContext ctxt, @NotNull KtExpression expression) {
491            VariableDescriptor variableDescriptor = ctxt.variableDescriptor;
492            if (!(variableDescriptor instanceof PropertyDescriptor)
493                || ctxt.enterInitState.mayBeInitialized()
494                || !ctxt.exitInitState.mayBeInitialized()
495                || !variableDescriptor.isVar()
496                || !trace.get(BindingContext.BACKING_FIELD_REQUIRED, (PropertyDescriptor) variableDescriptor)
497            ) {
498                return false;
499            }
500    
501            PsiElement property = DescriptorToSourceUtils.descriptorToDeclaration(variableDescriptor);
502            assert property instanceof KtProperty;
503            KtPropertyAccessor setter = ((KtProperty) property).getSetter();
504            if (((PropertyDescriptor) variableDescriptor).getModality() == Modality.FINAL && (setter == null || !setter.hasBody())) {
505                return false;
506            }
507    
508            KtExpression variable = expression;
509            if (expression instanceof KtDotQualifiedExpression) {
510                if (((KtDotQualifiedExpression) expression).getReceiverExpression() instanceof KtThisExpression) {
511                    variable = ((KtDotQualifiedExpression) expression).getSelectorExpression();
512                }
513            }
514            if (variable instanceof KtSimpleNameExpression) {
515                trace.record(IS_UNINITIALIZED, (PropertyDescriptor) variableDescriptor);
516                return true;
517            }
518            return false;
519        }
520    
521        private void recordInitializedVariables(
522                @NotNull Pseudocode pseudocode,
523                @NotNull Map<Instruction, Edges<InitControlFlowInfo>> initializersMap
524        ) {
525            Edges<InitControlFlowInfo> initializers = initializersMap.get(pseudocode.getExitInstruction());
526            if (initializers == null) return;
527            Set<VariableDescriptor> declaredVariables = getPseudocodeVariablesData().getDeclaredVariables(pseudocode, false);
528            for (VariableDescriptor variable : declaredVariables) {
529                if (variable instanceof PropertyDescriptor) {
530                    VariableControlFlowState variableControlFlowState = initializers.getIncoming().get(variable);
531                    if (variableControlFlowState != null && variableControlFlowState.definitelyInitialized()) continue;
532                    trace.record(BindingContext.IS_UNINITIALIZED, (PropertyDescriptor) variable);
533                }
534            }
535        }
536    
537    ////////////////////////////////////////////////////////////////////////////////
538    //  "Unused variable" & "unused value" analyses
539    
540        public void markUnusedVariables() {
541            final PseudocodeVariablesData pseudocodeVariablesData = getPseudocodeVariablesData();
542            Map<Instruction, Edges<UseControlFlowInfo>> variableStatusData = pseudocodeVariablesData.getVariableUseStatusData();
543            final Map<Instruction, DiagnosticFactory<?>> reportedDiagnosticMap = Maps.newHashMap();
544            InstructionDataAnalyzeStrategy<Map<VariableDescriptor, VariableUseState>> variableStatusAnalyzeStrategy =
545                    new InstructionDataAnalyzeStrategy<Map<VariableDescriptor, VariableUseState>>() {
546                        @Override
547                        public void execute(
548                                @NotNull Instruction instruction,
549                                @Nullable Map<VariableDescriptor, VariableUseState> in,
550                                @Nullable Map<VariableDescriptor, VariableUseState> out
551                        ) {
552    
553                            assert in != null && out != null;
554                            VariableContext ctxt = new VariableUseContext(instruction, reportedDiagnosticMap, in, out);
555                            Set<VariableDescriptor> declaredVariables =
556                                    pseudocodeVariablesData.getDeclaredVariables(instruction.getOwner(), false);
557                            VariableDescriptor variableDescriptor = PseudocodeUtil.extractVariableDescriptorIfAny(
558                                    instruction, false, trace.getBindingContext());
559                            if (variableDescriptor == null || !declaredVariables.contains(variableDescriptor)
560                                    || !ExpressionTypingUtils.isLocal(variableDescriptor.getContainingDeclaration(), variableDescriptor)) {
561                                return;
562                            }
563                            VariableUseState variableUseState = in.get(variableDescriptor);
564                            if (instruction instanceof WriteValueInstruction) {
565                                if (trace.get(CAPTURED_IN_CLOSURE, variableDescriptor) != null) return;
566                                KtElement element = ((WriteValueInstruction) instruction).getElement();
567                                if (variableUseState != READ) {
568                                    if (element instanceof KtBinaryExpression &&
569                                        ((KtBinaryExpression) element).getOperationToken() == KtTokens.EQ) {
570                                        KtExpression right = ((KtBinaryExpression) element).getRight();
571                                        if (right != null) {
572                                            report(Errors.UNUSED_VALUE.on((KtBinaryExpression) element, right, variableDescriptor), ctxt);
573                                        }
574                                    }
575                                    else if (element instanceof KtPostfixExpression) {
576                                        IElementType operationToken =
577                                                ((KtPostfixExpression) element).getOperationReference().getReferencedNameElementType();
578                                        if (operationToken == KtTokens.PLUSPLUS || operationToken == KtTokens.MINUSMINUS) {
579                                            report(Errors.UNUSED_CHANGED_VALUE.on(element, element), ctxt);
580                                        }
581                                    }
582                                }
583                            }
584                            else if (instruction instanceof VariableDeclarationInstruction) {
585                                KtDeclaration element = ((VariableDeclarationInstruction) instruction).getVariableDeclarationElement();
586                                if (!(element instanceof KtNamedDeclaration)) return;
587                                PsiElement nameIdentifier = ((KtNamedDeclaration) element).getNameIdentifier();
588                                if (nameIdentifier == null) return;
589                                if (!VariableUseState.isUsed(variableUseState)) {
590                                    if (KtPsiUtil.isVariableNotParameterDeclaration(element)) {
591                                        report(Errors.UNUSED_VARIABLE.on((KtNamedDeclaration) element, variableDescriptor), ctxt);
592                                    }
593                                    else if (element instanceof KtParameter) {
594                                        PsiElement owner = element.getParent().getParent();
595                                        if (owner instanceof KtPrimaryConstructor) {
596                                            if (!((KtParameter) element).hasValOrVar()) {
597                                                KtClassOrObject containingClass = ((KtPrimaryConstructor) owner).getContainingClassOrObject();
598                                                DeclarationDescriptor containingClassDescriptor = trace.get(
599                                                        BindingContext.DECLARATION_TO_DESCRIPTOR, containingClass
600                                                );
601                                                if (!DescriptorUtils.isAnnotationClass(containingClassDescriptor)) {
602                                                    report(Errors.UNUSED_PARAMETER.on((KtParameter) element, variableDescriptor), ctxt);
603                                                }
604                                            }
605                                        }
606                                        else if (owner instanceof KtFunction) {
607                                            MainFunctionDetector mainFunctionDetector = new MainFunctionDetector(trace.getBindingContext());
608                                            boolean isMain = (owner instanceof KtNamedFunction) && mainFunctionDetector.isMain((KtNamedFunction) owner);
609                                            if (owner instanceof KtFunctionLiteral) return;
610                                            DeclarationDescriptor descriptor = trace.get(BindingContext.DECLARATION_TO_DESCRIPTOR, owner);
611                                            assert descriptor instanceof FunctionDescriptor : owner.getText();
612                                            FunctionDescriptor functionDescriptor = (FunctionDescriptor) descriptor;
613                                            String functionName = functionDescriptor.getName().asString();
614                                            KtFunction function = (KtFunction) owner;
615                                            if (isMain
616                                                || ModalityKt.isOverridableOrOverrides(functionDescriptor)
617                                                || function.hasModifier(KtTokens.OVERRIDE_KEYWORD)
618                                                || "getValue".equals(functionName) || "setValue".equals(functionName)
619                                                || "propertyDelegated".equals(functionName)
620                                                    ) {
621                                                return;
622                                            }
623                                            report(Errors.UNUSED_PARAMETER.on((KtParameter) element, variableDescriptor), ctxt);
624                                        }
625                                    }
626                                }
627                                else if (variableUseState == ONLY_WRITTEN_NEVER_READ && KtPsiUtil.isVariableNotParameterDeclaration(element)) {
628                                    report(Errors.ASSIGNED_BUT_NEVER_ACCESSED_VARIABLE.on((KtNamedDeclaration) element, variableDescriptor), ctxt);
629                                }
630                                else if (variableUseState == WRITTEN_AFTER_READ && element instanceof KtVariableDeclaration) {
631                                    if (element instanceof KtProperty) {
632                                        KtExpression initializer = ((KtProperty) element).getInitializer();
633                                        if (initializer != null) {
634                                            report(Errors.VARIABLE_WITH_REDUNDANT_INITIALIZER.on(initializer, variableDescriptor), ctxt);
635                                        }
636                                    }
637                                    else if (element instanceof KtDestructuringDeclarationEntry) {
638                                        report(VARIABLE_WITH_REDUNDANT_INITIALIZER.on(element, variableDescriptor), ctxt);
639                                    }
640                                }
641                            }
642                        }
643                    };
644            PseudocodeTraverserKt.traverse(pseudocode, TraversalOrder.BACKWARD, variableStatusData, variableStatusAnalyzeStrategy);
645        }
646    
647    ////////////////////////////////////////////////////////////////////////////////
648    //  "Unused expressions" in block
649    
650        public void markUnusedExpressions() {
651            final Map<Instruction, DiagnosticFactory<?>> reportedDiagnosticMap = Maps.newHashMap();
652            PseudocodeTraverserKt.traverse(
653                    pseudocode, TraversalOrder.FORWARD, new ControlFlowInformationProvider.FunctionVoid1<Instruction>() {
654                        @Override
655                        public void execute(@NotNull Instruction instruction) {
656                            if (!(instruction instanceof KtElementInstruction)) return;
657    
658                            KtElement element = ((KtElementInstruction)instruction).getElement();
659                            if (!(element instanceof KtExpression)) return;
660    
661                            if (BindingContextUtilsKt.isUsedAsStatement((KtExpression) element, trace.getBindingContext())
662                                && PseudocodeUtilsKt.getSideEffectFree(instruction)) {
663                                VariableContext ctxt = new VariableContext(instruction, reportedDiagnosticMap);
664                                report(
665                                        element instanceof KtLambdaExpression
666                                            ? Errors.UNUSED_LAMBDA_EXPRESSION.on((KtLambdaExpression) element)
667                                            : Errors.UNUSED_EXPRESSION.on(element),
668                                        ctxt
669                                );
670                            }
671                        }
672                    }
673            );
674        }
675    
676    ////////////////////////////////////////////////////////////////////////////////
677    // Statements
678    
679        public void markStatements() {
680            PseudocodeTraverserKt.traverse(
681                    pseudocode, TraversalOrder.FORWARD, new ControlFlowInformationProvider.FunctionVoid1<Instruction>() {
682                        @Override
683                        public void execute(@NotNull Instruction instruction) {
684                            PseudoValue value = instruction instanceof InstructionWithValue
685                                                ? ((InstructionWithValue) instruction).getOutputValue()
686                                                : null;
687                            Pseudocode pseudocode = instruction.getOwner();
688                            List<Instruction> usages = pseudocode.getUsages(value);
689                            boolean isUsedAsExpression = !usages.isEmpty();
690                            boolean isUsedAsResultOfLambda = isUsedAsResultOfLambda(usages);
691                            for (KtElement element : pseudocode.getValueElements(value)) {
692                                trace.record(BindingContext.USED_AS_EXPRESSION, element, isUsedAsExpression);
693                                trace.record(BindingContext.USED_AS_RESULT_OF_LAMBDA, element, isUsedAsResultOfLambda);
694                            }
695                        }
696                    }
697            );
698        }
699    
700        private static boolean isUsedAsResultOfLambda(List<Instruction> usages) {
701            for (Instruction usage : usages) {
702                if (usage instanceof ReturnValueInstruction) {
703                    KtElement returnElement = ((ReturnValueInstruction) usage).getElement();
704                    PsiElement parentElement = returnElement.getParent();
705                    if (!(returnElement instanceof KtReturnExpression ||
706                          parentElement instanceof KtDeclaration && !(parentElement instanceof KtFunctionLiteral))) {
707                        return true;
708                    }
709                }
710            }
711            return false;
712        }
713    
714        public void checkIfExpressions() {
715            PseudocodeTraverserKt.traverse(
716                    pseudocode, TraversalOrder.FORWARD, new ControlFlowInformationProvider.FunctionVoid1<Instruction>() {
717                        @Override
718                        public void execute(@NotNull Instruction instruction) {
719                            PseudoValue value = instruction instanceof InstructionWithValue
720                                                ? ((InstructionWithValue) instruction).getOutputValue()
721                                                : null;
722                            for (KtElement element : instruction.getOwner().getValueElements(value)) {
723                                if (!(element instanceof KtIfExpression)) continue;
724                                KtIfExpression ifExpression = (KtIfExpression) element;
725    
726                                if (BindingContextUtilsKt.isUsedAsExpression(ifExpression, trace.getBindingContext())) {
727                                    KtExpression thenExpression = ifExpression.getThen();
728                                    KtExpression elseExpression = ifExpression.getElse();
729    
730                                    if (thenExpression == null || elseExpression == null) {
731                                        trace.report(INVALID_IF_AS_EXPRESSION.on(ifExpression));
732                                    }
733                                    else {
734                                        checkImplicitCastOnConditionalExpression(ifExpression);
735                                    }
736                                }
737                            }
738                        }
739                    }
740            );
741        }
742    
743        private static List<KtExpression> collectResultingExpressionsOfConditionalExpression(KtExpression expression) {
744            List<KtExpression> leafBranches = new ArrayList<KtExpression>();
745            collectResultingExpressionsOfConditionalExpressionRec(expression, leafBranches);
746            return leafBranches;
747        }
748    
749        private static void collectResultingExpressionsOfConditionalExpressionRec(
750                @Nullable KtExpression expression,
751                @NotNull List<KtExpression> resultingExpressions
752        ) {
753            if (expression instanceof KtIfExpression) {
754                KtIfExpression ifExpression = (KtIfExpression) expression;
755                collectResultingExpressionsOfConditionalExpressionRec(ifExpression.getThen(), resultingExpressions);
756                collectResultingExpressionsOfConditionalExpressionRec(ifExpression.getElse(), resultingExpressions);
757            }
758            else if (expression instanceof KtWhenExpression) {
759                KtWhenExpression whenExpression = (KtWhenExpression) expression;
760                for (KtWhenEntry whenEntry : whenExpression.getEntries()) {
761                    collectResultingExpressionsOfConditionalExpressionRec(whenEntry.getExpression(), resultingExpressions);
762                }
763            }
764            else if (expression != null){
765                KtExpression resultingExpression = getResultingExpression(expression);
766                if (resultingExpression instanceof KtIfExpression || resultingExpression instanceof KtWhenExpression) {
767                    collectResultingExpressionsOfConditionalExpressionRec(resultingExpression, resultingExpressions);
768                }
769                else {
770                    resultingExpressions.add(resultingExpression);
771                }
772            }
773        }
774    
775        private void checkImplicitCastOnConditionalExpression(@NotNull KtExpression expression) {
776            Collection<KtExpression> branchExpressions = collectResultingExpressionsOfConditionalExpression(expression);
777    
778            KotlinType expectedExpressionType = trace.get(EXPECTED_EXPRESSION_TYPE, expression);
779            if (expectedExpressionType != null && expectedExpressionType != DONT_CARE) return;
780    
781            KotlinType expressionType = trace.getType(expression);
782            if (expressionType == null) {
783                return;
784            }
785            if (KotlinBuiltIns.isAnyOrNullableAny(expressionType)) {
786                boolean isUsedAsResultOfLambda = BindingContextUtilsKt.isUsedAsResultOfLambda(expression, trace.getBindingContext());
787                for (KtExpression branchExpression : branchExpressions) {
788                    if (branchExpression == null) continue;
789                    KotlinType branchType = trace.getType(branchExpression);
790                    if (branchType == null
791                        || KotlinBuiltIns.isAnyOrNullableAny(branchType)
792                        || (isUsedAsResultOfLambda && KotlinBuiltIns.isUnitOrNullableUnit(branchType))) {
793                        return;
794                    }
795                }
796                for (KtExpression branchExpression : branchExpressions) {
797                    if (branchExpression == null) continue;
798                    KotlinType branchType = trace.getType(branchExpression);
799                    if (branchType == null) continue;
800                    if (KotlinBuiltIns.isNothing(branchType)) continue;
801                    trace.report(IMPLICIT_CAST_TO_ANY.on(getResultingExpression(branchExpression), branchType, expressionType));
802                }
803            }
804        }
805    
806        private static @NotNull KtExpression getResultingExpression(@NotNull KtExpression expression) {
807            KtExpression finger = expression;
808            while (true) {
809                KtExpression deparenthesized = KtPsiUtil.deparenthesize(finger);
810                deparenthesized = KtPsiUtil.getExpressionOrLastStatementInBlock(deparenthesized);
811                if (deparenthesized == null || deparenthesized == finger) break;
812                finger = deparenthesized;
813            }
814            return finger;
815        }
816    
817        public void checkWhenExpressions() {
818            final Map<Instruction, Edges<InitControlFlowInfo>> initializers = pseudocodeVariablesData.getVariableInitializers();
819            PseudocodeTraverserKt.traverse(
820                    pseudocode, TraversalOrder.FORWARD, new ControlFlowInformationProvider.FunctionVoid1<Instruction>() {
821                        @Override
822                        public void execute(@NotNull Instruction instruction) {
823                            if (instruction instanceof MagicInstruction) {
824                                MagicInstruction magicInstruction = (MagicInstruction) instruction;
825                                if (magicInstruction.getKind() == MagicKind.EXHAUSTIVE_WHEN_ELSE) {
826                                    Instruction next = magicInstruction.getNext();
827                                    if (next instanceof MergeInstruction) {
828                                        MergeInstruction mergeInstruction = (MergeInstruction) next;
829                                        if (initializers.containsKey(mergeInstruction) && initializers.containsKey(magicInstruction)) {
830                                            InitControlFlowInfo mergeInfo = initializers.get(mergeInstruction).getIncoming();
831                                            InitControlFlowInfo magicInfo = initializers.get(magicInstruction).getOutgoing();
832                                            if (mergeInstruction.getElement() instanceof KtWhenExpression &&
833                                                magicInfo.checkDefiniteInitializationInWhen(mergeInfo)) {
834                                                trace.record(IMPLICIT_EXHAUSTIVE_WHEN, (KtWhenExpression) mergeInstruction.getElement());
835                                            }
836                                        }
837                                    }
838                                }
839                            }
840                            PseudoValue value = instruction instanceof InstructionWithValue
841                                                ? ((InstructionWithValue) instruction).getOutputValue()
842                                                : null;
843                            for (KtElement element : instruction.getOwner().getValueElements(value)) {
844                                if (!(element instanceof KtWhenExpression)) continue;
845                                KtWhenExpression whenExpression = (KtWhenExpression) element;
846    
847                                if (BindingContextUtilsKt.isUsedAsExpression(whenExpression, trace.getBindingContext())) {
848                                    checkImplicitCastOnConditionalExpression(whenExpression);
849                                }
850    
851                                if (whenExpression.getElseExpression() != null) continue;
852    
853                                BindingContext context = trace.getBindingContext();
854                                List<WhenMissingCase> necessaryCases = WhenChecker.getNecessaryCases(whenExpression, context);
855                                if (!necessaryCases.isEmpty()) {
856                                    trace.report(NO_ELSE_IN_WHEN.on(whenExpression, necessaryCases));
857                                }
858                                else if (whenExpression.getSubjectExpression() != null) {
859                                    ClassDescriptor enumClassDescriptor = WhenChecker.getClassDescriptorOfTypeIfEnum(
860                                            trace.getType(whenExpression.getSubjectExpression()));
861                                    if (enumClassDescriptor != null) {
862                                        List<WhenMissingCase> missingCases = WhenChecker.getEnumMissingCases(
863                                                whenExpression, context, enumClassDescriptor
864                                        );
865                                        if (!missingCases.isEmpty()) {
866                                            trace.report(NON_EXHAUSTIVE_WHEN.on(whenExpression, missingCases));
867                                        }
868                                    }
869                                }
870                            }
871                        }
872                    }
873            );
874        }
875    
876    ////////////////////////////////////////////////////////////////////////////////
877    // Tail calls
878    
879        public void markTailCalls() {
880            final DeclarationDescriptor subroutineDescriptor = trace.get(BindingContext.DECLARATION_TO_DESCRIPTOR, subroutine);
881            if (!(subroutineDescriptor instanceof FunctionDescriptor)) return;
882            if (!((FunctionDescriptor) subroutineDescriptor).isTailrec()) return;
883    
884            // finally blocks are copied which leads to multiple diagnostics reported on one instruction
885            class KindAndCall {
886                TailRecursionKind kind;
887                ResolvedCall<?> call;
888    
889                KindAndCall(TailRecursionKind kind, ResolvedCall<?> call) {
890                    this.kind = kind;
891                    this.call = call;
892                }
893            }
894            final Map<KtElement, KindAndCall> calls = new HashMap<KtElement, KindAndCall>();
895            PseudocodeTraverserKt.traverse(
896                    pseudocode,
897                    TraversalOrder.FORWARD,
898                    new FunctionVoid1<Instruction>() {
899                        public void execute(@NotNull Instruction instruction) {
900                            if (!(instruction instanceof CallInstruction)) return;
901                            CallInstruction callInstruction = (CallInstruction) instruction;
902    
903                            ResolvedCall<?> resolvedCall = CallUtilKt.getResolvedCall(callInstruction.getElement(), trace.getBindingContext());
904                            if (resolvedCall == null) return;
905    
906                            // is this a recursive call?
907                            CallableDescriptor functionDescriptor = resolvedCall.getResultingDescriptor();
908                            if (!functionDescriptor.getOriginal().equals(subroutineDescriptor)) return;
909    
910                            KtElement element = callInstruction.getElement();
911                            //noinspection unchecked
912                            KtExpression parent = PsiTreeUtil.getParentOfType(
913                                    element,
914                                    KtTryExpression.class, KtFunction.class, KtAnonymousInitializer.class
915                            );
916    
917                            if (parent instanceof KtTryExpression) {
918                                // We do not support tail calls Collections.singletonMap() try-catch-finally, for simplicity of the mental model
919                                // very few cases there would be real tail-calls, and it's often not so easy for the user to see why
920                                calls.put(element, new KindAndCall(IN_TRY, resolvedCall));
921                                return;
922                            }
923    
924                            boolean isTail = PseudocodeTraverserKt.traverseFollowingInstructions(
925                                    callInstruction,
926                                    new HashSet<Instruction>(),
927                                    TraversalOrder.FORWARD,
928                                    new TailRecursionDetector(subroutine, callInstruction)
929                            );
930    
931                            // A tail call is not allowed to change dispatch receiver
932                            //   class C {
933                            //       fun foo(other: C) {
934                            //           other.foo(this) // not a tail call
935                            //       }
936                            //   }
937                            boolean sameDispatchReceiver =
938                                    ResolvedCallUtilKt.hasThisOrNoDispatchReceiver(resolvedCall, trace.getBindingContext());
939    
940                            TailRecursionKind kind = isTail && sameDispatchReceiver ? TAIL_CALL : NON_TAIL;
941    
942                            KindAndCall kindAndCall = calls.get(element);
943                            calls.put(element,
944                                      new KindAndCall(
945                                              combineKinds(kind, kindAndCall == null ? null : kindAndCall.kind),
946                                              resolvedCall
947                                      )
948                            );
949                        }
950                    }
951            );
952            boolean hasTailCalls = false;
953            for (Map.Entry<KtElement, KindAndCall> entry : calls.entrySet()) {
954                KtElement element = entry.getKey();
955                KindAndCall kindAndCall = entry.getValue();
956                switch (kindAndCall.kind) {
957                    case TAIL_CALL:
958                        trace.record(TAIL_RECURSION_CALL, kindAndCall.call, TailRecursionKind.TAIL_CALL);
959                        hasTailCalls = true;
960                        break;
961                    case IN_TRY:
962                        trace.report(Errors.TAIL_RECURSION_IN_TRY_IS_NOT_SUPPORTED.on(element));
963                        break;
964                    case NON_TAIL:
965                        trace.report(Errors.NON_TAIL_RECURSIVE_CALL.on(element));
966                        break;
967                }
968            }
969    
970            if (!hasTailCalls) {
971                trace.report(Errors.NO_TAIL_CALLS_FOUND.on((KtNamedFunction) subroutine));
972            }
973        }
974    
975        private static TailRecursionKind combineKinds(TailRecursionKind kind, @Nullable TailRecursionKind existingKind) {
976            TailRecursionKind resultingKind;
977            if (existingKind == null || existingKind == kind) {
978                resultingKind = kind;
979            }
980            else {
981                if (check(kind, existingKind, IN_TRY, TAIL_CALL)) {
982                    resultingKind = IN_TRY;
983                }
984                else if (check(kind, existingKind, IN_TRY, NON_TAIL)) {
985                    resultingKind = IN_TRY;
986                }
987                else {
988                    // TAIL_CALL, NON_TAIL
989                    resultingKind = NON_TAIL;
990                }
991            }
992            return resultingKind;
993        }
994    
995        private static boolean check(Object a, Object b, Object x, Object y) {
996            return (a == x && b == y) || (a == y && b == x);
997        }
998    
999    ////////////////////////////////////////////////////////////////////////////////
1000    // Utility classes and methods
1001    
1002        /**
1003         * The method provides reporting of the same diagnostic only once for copied instructions
1004         * (depends on whether it should be reported for all or only for one of the copies)
1005         */
1006        private void report(
1007                @NotNull Diagnostic diagnostic,
1008                @NotNull VariableContext ctxt
1009        ) {
1010            Instruction instruction = ctxt.instruction;
1011            if (instruction.getCopies().isEmpty()) {
1012                trace.report(diagnostic);
1013                return;
1014            }
1015            Map<Instruction, DiagnosticFactory<?>> previouslyReported = ctxt.reportedDiagnosticMap;
1016            previouslyReported.put(instruction, diagnostic.getFactory());
1017    
1018            boolean alreadyReported = false;
1019            boolean sameErrorForAllCopies = true;
1020            for (Instruction copy : instruction.getCopies()) {
1021                DiagnosticFactory<?> previouslyReportedErrorFactory = previouslyReported.get(copy);
1022                if (previouslyReportedErrorFactory != null) {
1023                    alreadyReported = true;
1024                }
1025    
1026                if (previouslyReportedErrorFactory != diagnostic.getFactory()) {
1027                    sameErrorForAllCopies = false;
1028                }
1029            }
1030    
1031            if (mustBeReportedOnAllCopies(diagnostic.getFactory())) {
1032                if (sameErrorForAllCopies) {
1033                    trace.report(diagnostic);
1034                }
1035            }
1036            else {
1037                //only one reporting required
1038                if (!alreadyReported) {
1039                    trace.report(diagnostic);
1040                }
1041            }
1042        }
1043    
1044        private static boolean mustBeReportedOnAllCopies(@NotNull DiagnosticFactory<?> diagnosticFactory) {
1045            return diagnosticFactory == UNUSED_VARIABLE
1046                   || diagnosticFactory == UNUSED_PARAMETER
1047                   || diagnosticFactory == UNUSED_CHANGED_VALUE;
1048        }
1049    
1050    
1051        private class VariableContext {
1052            final Map<Instruction, DiagnosticFactory<?>> reportedDiagnosticMap;
1053            final Instruction instruction;
1054            final VariableDescriptor variableDescriptor;
1055    
1056            private VariableContext(
1057                    @NotNull Instruction instruction,
1058                    @NotNull Map<Instruction, DiagnosticFactory<?>> map
1059            ) {
1060                this.instruction = instruction;
1061                reportedDiagnosticMap = map;
1062                variableDescriptor = PseudocodeUtil.extractVariableDescriptorIfAny(instruction, true, trace.getBindingContext());
1063            }
1064        }
1065    
1066        private class VariableInitContext extends VariableContext {
1067            final VariableControlFlowState enterInitState;
1068            final VariableControlFlowState exitInitState;
1069    
1070            private VariableInitContext(
1071                    @NotNull Instruction instruction,
1072                    @NotNull Map<Instruction, DiagnosticFactory<?>> map,
1073                    @NotNull Map<VariableDescriptor, VariableControlFlowState> in,
1074                    @NotNull Map<VariableDescriptor, VariableControlFlowState> out,
1075                    @NotNull LexicalScopeVariableInfo lexicalScopeVariableInfo
1076            ) {
1077                super(instruction, map);
1078                enterInitState = initialize(variableDescriptor, lexicalScopeVariableInfo, in);
1079                exitInitState = initialize(variableDescriptor, lexicalScopeVariableInfo, out);
1080            }
1081    
1082            private VariableControlFlowState initialize(
1083                    VariableDescriptor variableDescriptor,
1084                    LexicalScopeVariableInfo lexicalScopeVariableInfo,
1085                    Map<VariableDescriptor, VariableControlFlowState> map
1086            ) {
1087                if (variableDescriptor == null) return null;
1088                VariableControlFlowState state = map.get(variableDescriptor);
1089                if (state != null) return state;
1090                return PseudocodeVariablesData.getDefaultValueForInitializers(variableDescriptor, instruction, lexicalScopeVariableInfo);
1091            }
1092        }
1093    
1094        private class VariableUseContext extends VariableContext {
1095            final VariableUseState enterUseState;
1096            final VariableUseState exitUseState;
1097    
1098    
1099            private VariableUseContext(
1100                    @NotNull Instruction instruction,
1101                    @NotNull Map<Instruction, DiagnosticFactory<?>> map,
1102                    @NotNull Map<VariableDescriptor, VariableUseState> in,
1103                    @NotNull Map<VariableDescriptor, VariableUseState> out
1104            ) {
1105                super(instruction, map);
1106                enterUseState = variableDescriptor != null ? in.get(variableDescriptor) : null;
1107                exitUseState = variableDescriptor != null ? out.get(variableDescriptor) : null;
1108            }
1109        }
1110    
1111        //TODO after KT-4621 rewrite to Kotlin
1112        public abstract static class InstructionDataAnalyzeStrategy<D> implements Function3<Instruction, D, D, Unit> {
1113            @Override
1114            public Unit invoke(Instruction instruction, D enterData, D exitData) {
1115                execute(instruction, enterData, exitData);
1116                return Unit.INSTANCE;
1117            }
1118    
1119            public abstract void execute(Instruction instruction, D enterData, D exitData);
1120        }
1121    
1122        public abstract static class FunctionVoid1<P> implements Function1<P, Unit> {
1123            @Override
1124            public Unit invoke(P p) {
1125                execute(p);
1126                return Unit.INSTANCE;
1127            }
1128    
1129            public abstract void execute(P p);
1130        }
1131    }