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.Function1;
026 import kotlin.Function3;
027 import kotlin.Unit;
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.PseudocodeVariablesData.VariableInitState;
032 import org.jetbrains.kotlin.cfg.PseudocodeVariablesData.VariableUseState;
033 import org.jetbrains.kotlin.cfg.pseudocode.PseudoValue;
034 import org.jetbrains.kotlin.cfg.pseudocode.Pseudocode;
035 import org.jetbrains.kotlin.cfg.pseudocode.PseudocodePackage;
036 import org.jetbrains.kotlin.cfg.pseudocode.PseudocodeUtil;
037 import org.jetbrains.kotlin.cfg.pseudocode.instructions.Instruction;
038 import org.jetbrains.kotlin.cfg.pseudocode.instructions.InstructionVisitor;
039 import org.jetbrains.kotlin.cfg.pseudocode.instructions.JetElementInstruction;
040 import org.jetbrains.kotlin.cfg.pseudocode.instructions.eval.*;
041 import org.jetbrains.kotlin.cfg.pseudocode.instructions.jumps.*;
042 import org.jetbrains.kotlin.cfg.pseudocode.instructions.special.LocalFunctionDeclarationInstruction;
043 import org.jetbrains.kotlin.cfg.pseudocode.instructions.special.MarkInstruction;
044 import org.jetbrains.kotlin.cfg.pseudocode.instructions.special.SubroutineExitInstruction;
045 import org.jetbrains.kotlin.cfg.pseudocode.instructions.special.VariableDeclarationInstruction;
046 import org.jetbrains.kotlin.cfg.pseudocodeTraverser.Edges;
047 import org.jetbrains.kotlin.cfg.pseudocodeTraverser.PseudocodeTraverserPackage;
048 import org.jetbrains.kotlin.cfg.pseudocodeTraverser.TraversalOrder;
049 import org.jetbrains.kotlin.descriptors.*;
050 import org.jetbrains.kotlin.diagnostics.Diagnostic;
051 import org.jetbrains.kotlin.diagnostics.DiagnosticFactory;
052 import org.jetbrains.kotlin.diagnostics.Errors;
053 import org.jetbrains.kotlin.idea.MainFunctionDetector;
054 import org.jetbrains.kotlin.lexer.JetTokens;
055 import org.jetbrains.kotlin.psi.*;
056 import org.jetbrains.kotlin.resolve.*;
057 import org.jetbrains.kotlin.resolve.bindingContextUtil.BindingContextUtilPackage;
058 import org.jetbrains.kotlin.resolve.calls.callUtil.CallUtilPackage;
059 import org.jetbrains.kotlin.resolve.calls.model.ResolvedCall;
060 import org.jetbrains.kotlin.resolve.scopes.receivers.ExpressionReceiver;
061 import org.jetbrains.kotlin.resolve.scopes.receivers.ReceiverValue;
062 import org.jetbrains.kotlin.resolve.scopes.receivers.ThisReceiver;
063 import org.jetbrains.kotlin.types.JetType;
064 import org.jetbrains.kotlin.types.expressions.ExpressionTypingUtils;
065
066 import java.util.*;
067
068 import static org.jetbrains.kotlin.cfg.PseudocodeVariablesData.VariableUseState.*;
069 import static org.jetbrains.kotlin.cfg.TailRecursionKind.*;
070 import static org.jetbrains.kotlin.cfg.pseudocodeTraverser.TraversalOrder.FORWARD;
071 import static org.jetbrains.kotlin.diagnostics.Errors.*;
072 import static org.jetbrains.kotlin.resolve.BindingContext.CAPTURED_IN_CLOSURE;
073 import static org.jetbrains.kotlin.resolve.BindingContext.TAIL_RECURSION_CALL;
074 import static org.jetbrains.kotlin.resolve.calls.callUtil.CallUtilPackage.getResolvedCall;
075 import static org.jetbrains.kotlin.types.TypeUtils.NO_EXPECTED_TYPE;
076 import static org.jetbrains.kotlin.types.TypeUtils.noExpectedType;
077
078 public class JetFlowInformationProvider {
079
080 private final JetElement subroutine;
081 private final Pseudocode pseudocode;
082 private final BindingTrace trace;
083 private PseudocodeVariablesData pseudocodeVariablesData;
084
085 private JetFlowInformationProvider(
086 @NotNull JetElement declaration,
087 @NotNull BindingTrace trace,
088 @NotNull Pseudocode pseudocode
089 ) {
090 this.subroutine = declaration;
091 this.trace = trace;
092 this.pseudocode = pseudocode;
093 }
094
095 public JetFlowInformationProvider(
096 @NotNull JetElement declaration,
097 @NotNull BindingTrace trace
098 ) {
099 this(declaration, trace, new JetControlFlowProcessor(trace).generatePseudocode(declaration));
100 }
101
102 public PseudocodeVariablesData getPseudocodeVariablesData() {
103 if (pseudocodeVariablesData == null) {
104 pseudocodeVariablesData = new PseudocodeVariablesData(pseudocode, trace.getBindingContext());
105 }
106 return pseudocodeVariablesData;
107 }
108
109 public void checkForLocalClassOrObjectMode() {
110 // Local classes and objects are analyzed twice: when TopDownAnalyzer processes it and as a part of its container.
111 // Almost all checks can be done when the container is analyzed
112 // except recording initialized variables (this information is needed for DeclarationChecker).
113 recordInitializedVariables();
114 }
115
116 public void checkDeclaration() {
117
118 recordInitializedVariables();
119
120 checkLocalFunctions();
121
122 markUninitializedVariables();
123
124 markUnusedVariables();
125
126 markStatements();
127
128 markUnusedExpressions();
129
130 markWhenWithoutElse();
131 }
132
133 public void checkFunction(@Nullable JetType expectedReturnType) {
134 UnreachableCode unreachableCode = collectUnreachableCode();
135 reportUnreachableCode(unreachableCode);
136
137 if (subroutine instanceof JetFunctionLiteral) return;
138
139 checkDefiniteReturn(expectedReturnType != null ? expectedReturnType : NO_EXPECTED_TYPE, unreachableCode);
140
141 markTailCalls();
142 }
143
144 private void collectReturnExpressions(@NotNull final Collection<JetElement> returnedExpressions) {
145 final Set<Instruction> instructions = Sets.newHashSet(pseudocode.getInstructions());
146 SubroutineExitInstruction exitInstruction = pseudocode.getExitInstruction();
147 for (Instruction previousInstruction : exitInstruction.getPreviousInstructions()) {
148 previousInstruction.accept(new InstructionVisitor() {
149 @Override
150 public void visitReturnValue(@NotNull ReturnValueInstruction instruction) {
151 if (instructions.contains(instruction)) { //exclude non-local return expressions
152 returnedExpressions.add(instruction.getElement());
153 }
154 }
155
156 @Override
157 public void visitReturnNoValue(@NotNull ReturnNoValueInstruction instruction) {
158 if (instructions.contains(instruction)) {
159 returnedExpressions.add(instruction.getElement());
160 }
161 }
162
163
164 @Override
165 public void visitJump(@NotNull AbstractJumpInstruction instruction) {
166 // Nothing
167 }
168
169 @Override
170 public void visitUnconditionalJump(@NotNull UnconditionalJumpInstruction instruction) {
171 redirectToPrevInstructions(instruction);
172 }
173
174 private void redirectToPrevInstructions(Instruction instruction) {
175 for (Instruction previousInstruction : instruction.getPreviousInstructions()) {
176 previousInstruction.accept(this);
177 }
178 }
179
180 @Override
181 public void visitNondeterministicJump(@NotNull NondeterministicJumpInstruction instruction) {
182 redirectToPrevInstructions(instruction);
183 }
184
185 @Override
186 public void visitMarkInstruction(@NotNull MarkInstruction instruction) {
187 redirectToPrevInstructions(instruction);
188 }
189
190 @Override
191 public void visitInstruction(@NotNull Instruction instruction) {
192 if (instruction instanceof JetElementInstruction) {
193 JetElementInstruction elementInstruction = (JetElementInstruction) instruction;
194 returnedExpressions.add(elementInstruction.getElement());
195 }
196 else {
197 throw new IllegalStateException(instruction + " precedes the exit point");
198 }
199 }
200 });
201 }
202 }
203
204 private void checkLocalFunctions() {
205 for (LocalFunctionDeclarationInstruction localDeclarationInstruction : pseudocode.getLocalDeclarations()) {
206 JetElement element = localDeclarationInstruction.getElement();
207 if (element instanceof JetDeclarationWithBody) {
208 JetDeclarationWithBody localDeclaration = (JetDeclarationWithBody) element;
209
210 CallableDescriptor functionDescriptor =
211 (CallableDescriptor) trace.getBindingContext().get(BindingContext.DECLARATION_TO_DESCRIPTOR, localDeclaration);
212 JetType expectedType = functionDescriptor != null ? functionDescriptor.getReturnType() : null;
213
214 JetFlowInformationProvider providerForLocalDeclaration =
215 new JetFlowInformationProvider(localDeclaration, trace, localDeclarationInstruction.getBody());
216
217 providerForLocalDeclaration.checkFunction(expectedType);
218 }
219 }
220 }
221
222 public void checkDefiniteReturn(final @NotNull JetType expectedReturnType, @NotNull final UnreachableCode unreachableCode) {
223 assert subroutine instanceof JetDeclarationWithBody;
224 JetDeclarationWithBody function = (JetDeclarationWithBody) subroutine;
225
226 if (!function.hasBody()) return;
227
228 List<JetElement> returnedExpressions = Lists.newArrayList();
229 collectReturnExpressions(returnedExpressions);
230
231 final boolean blockBody = function.hasBlockBody();
232
233 final boolean[] noReturnError = new boolean[] { false };
234 for (JetElement returnedExpression : returnedExpressions) {
235 returnedExpression.accept(new JetVisitorVoid() {
236 @Override
237 public void visitReturnExpression(@NotNull JetReturnExpression expression) {
238 if (!blockBody) {
239 trace.report(RETURN_IN_FUNCTION_WITH_EXPRESSION_BODY.on(expression));
240 }
241 }
242
243 @Override
244 public void visitJetElement(@NotNull JetElement element) {
245 if (!(element instanceof JetExpression || element instanceof JetWhenCondition)) return;
246
247 if (blockBody && !noExpectedType(expectedReturnType)
248 && !KotlinBuiltIns.isUnit(expectedReturnType)
249 && !unreachableCode.getElements().contains(element)) {
250 noReturnError[0] = true;
251 }
252 }
253 });
254 }
255 if (noReturnError[0]) {
256 trace.report(NO_RETURN_IN_FUNCTION_WITH_BLOCK_BODY.on(function));
257 }
258 }
259
260 private void reportUnreachableCode(@NotNull UnreachableCode unreachableCode) {
261 for (JetElement element : unreachableCode.getElements()) {
262 trace.report(UNREACHABLE_CODE.on(element, unreachableCode.getUnreachableTextRanges(element)));
263 trace.record(BindingContext.UNREACHABLE_CODE, element, true);
264 }
265 }
266
267 @NotNull
268 private UnreachableCode collectUnreachableCode() {
269 Set<JetElement> reachableElements = Sets.newHashSet();
270 Set<JetElement> unreachableElements = Sets.newHashSet();
271 for (Instruction instruction : pseudocode.getInstructionsIncludingDeadCode()) {
272 if (!(instruction instanceof JetElementInstruction)
273 || instruction instanceof LoadUnitValueInstruction
274 || instruction instanceof MergeInstruction
275 || (instruction instanceof MagicInstruction && ((MagicInstruction) instruction).getSynthetic())) continue;
276
277 JetElement element = ((JetElementInstruction) instruction).getElement();
278
279 if (instruction instanceof JumpInstruction) {
280 boolean isJumpElement = element instanceof JetBreakExpression
281 || element instanceof JetContinueExpression
282 || element instanceof JetReturnExpression
283 || element instanceof JetThrowExpression;
284 if (!isJumpElement) continue;
285 }
286
287 if (instruction.getDead()) {
288 unreachableElements.add(element);
289 }
290 else {
291 reachableElements.add(element);
292 }
293 }
294 return new UnreachableCodeImpl(reachableElements, unreachableElements);
295 }
296
297 ////////////////////////////////////////////////////////////////////////////////
298 // Uninitialized variables analysis
299
300 public void markUninitializedVariables() {
301 final Collection<VariableDescriptor> varWithUninitializedErrorGenerated = Sets.newHashSet();
302 final Collection<VariableDescriptor> varWithValReassignErrorGenerated = Sets.newHashSet();
303 final boolean processClassOrObject = subroutine instanceof JetClassOrObject;
304
305 PseudocodeVariablesData pseudocodeVariablesData = getPseudocodeVariablesData();
306 Map<Instruction, Edges<Map<VariableDescriptor, VariableInitState>>> initializers =
307 pseudocodeVariablesData.getVariableInitializers();
308 final Set<VariableDescriptor> declaredVariables = pseudocodeVariablesData.getDeclaredVariables(pseudocode, true);
309 final LexicalScopeVariableInfo lexicalScopeVariableInfo = pseudocodeVariablesData.getLexicalScopeVariableInfo();
310
311 final Map<Instruction, DiagnosticFactory<?>> reportedDiagnosticMap = Maps.newHashMap();
312
313 PseudocodeTraverserPackage.traverse(
314 pseudocode, FORWARD, initializers,
315 new InstructionDataAnalyzeStrategy<Map<VariableDescriptor, VariableInitState>>() {
316 @Override
317 public void execute(
318 @NotNull Instruction instruction,
319 @Nullable Map<VariableDescriptor, VariableInitState> in,
320 @Nullable Map<VariableDescriptor, VariableInitState> out
321 ) {
322 assert in != null && out != null;
323 VariableInitContext ctxt =
324 new VariableInitContext(instruction, reportedDiagnosticMap, in, out, lexicalScopeVariableInfo);
325 if (ctxt.variableDescriptor == null) return;
326 if (instruction instanceof ReadValueInstruction) {
327 JetElement element = ((ReadValueInstruction) instruction).getElement();
328 boolean error = checkBackingField(ctxt, element);
329 if (!error && declaredVariables.contains(ctxt.variableDescriptor)) {
330 checkIsInitialized(ctxt, element, varWithUninitializedErrorGenerated);
331 }
332 return;
333 }
334 if (!(instruction instanceof WriteValueInstruction)) return;
335 JetElement element = ((WriteValueInstruction) instruction).getlValue();
336 boolean error = checkBackingField(ctxt, element);
337 if (!(element instanceof JetExpression)) return;
338 if (!error) {
339 error = checkValReassignment(ctxt, (JetExpression) element, varWithValReassignErrorGenerated);
340 }
341 if (!error && processClassOrObject) {
342 error = checkAssignmentBeforeDeclaration(ctxt, (JetExpression) element);
343 }
344 if (!error && processClassOrObject) {
345 checkInitializationUsingBackingField(ctxt, (JetExpression) element);
346 }
347 }
348 }
349 );
350 }
351
352 public void recordInitializedVariables() {
353 PseudocodeVariablesData pseudocodeVariablesData = getPseudocodeVariablesData();
354 Pseudocode pseudocode = pseudocodeVariablesData.getPseudocode();
355 Map<Instruction, Edges<Map<VariableDescriptor, VariableInitState>>> initializers =
356 pseudocodeVariablesData.getVariableInitializers();
357 recordInitializedVariables(pseudocode, initializers);
358 for (LocalFunctionDeclarationInstruction instruction : pseudocode.getLocalDeclarations()) {
359 recordInitializedVariables(instruction.getBody(), initializers);
360 }
361 }
362
363 private void checkIsInitialized(
364 @NotNull VariableInitContext ctxt,
365 @NotNull JetElement element,
366 @NotNull Collection<VariableDescriptor> varWithUninitializedErrorGenerated
367 ) {
368 if (!(element instanceof JetSimpleNameExpression)) return;
369
370 boolean isInitialized = ctxt.exitInitState.isInitialized;
371 VariableDescriptor variableDescriptor = ctxt.variableDescriptor;
372 if (variableDescriptor instanceof PropertyDescriptor) {
373 if (!trace.get(BindingContext.BACKING_FIELD_REQUIRED, (PropertyDescriptor) variableDescriptor)) {
374 isInitialized = true;
375 }
376 }
377 if (!isInitialized && !varWithUninitializedErrorGenerated.contains(variableDescriptor)) {
378 if (!(variableDescriptor instanceof PropertyDescriptor)) {
379 varWithUninitializedErrorGenerated.add(variableDescriptor);
380 }
381 if (variableDescriptor instanceof ValueParameterDescriptor) {
382 report(Errors.UNINITIALIZED_PARAMETER.on((JetSimpleNameExpression) element,
383 (ValueParameterDescriptor) variableDescriptor), ctxt);
384 }
385 else {
386 report(Errors.UNINITIALIZED_VARIABLE.on((JetSimpleNameExpression) element, variableDescriptor), ctxt);
387 }
388 }
389 }
390
391 private boolean checkValReassignment(
392 @NotNull VariableInitContext ctxt,
393 @NotNull JetExpression expression,
394 @NotNull Collection<VariableDescriptor> varWithValReassignErrorGenerated
395 ) {
396 VariableDescriptor variableDescriptor = ctxt.variableDescriptor;
397 if (JetPsiUtil.isBackingFieldReference(expression) && variableDescriptor instanceof PropertyDescriptor) {
398 PropertyDescriptor propertyDescriptor = (PropertyDescriptor) variableDescriptor;
399 JetPropertyAccessor accessor = PsiTreeUtil.getParentOfType(expression, JetPropertyAccessor.class);
400 if (accessor != null) {
401 DeclarationDescriptor accessorDescriptor = trace.get(BindingContext.DECLARATION_TO_DESCRIPTOR, accessor);
402 if (propertyDescriptor.getGetter() == accessorDescriptor) {
403 //val can be reassigned through backing field inside its own getter
404 return false;
405 }
406 }
407 }
408
409 boolean isInitializedNotHere = ctxt.enterInitState.isInitialized;
410 boolean hasBackingField = true;
411 if (variableDescriptor instanceof PropertyDescriptor) {
412 hasBackingField = trace.get(BindingContext.BACKING_FIELD_REQUIRED, (PropertyDescriptor) variableDescriptor);
413 }
414 if (variableDescriptor.isVar() && variableDescriptor instanceof PropertyDescriptor) {
415 DeclarationDescriptor descriptor = BindingContextUtils.getEnclosingDescriptor(trace.getBindingContext(), expression);
416 PropertySetterDescriptor setterDescriptor = ((PropertyDescriptor) variableDescriptor).getSetter();
417
418 ResolvedCall<? extends CallableDescriptor> resolvedCall = CallUtilPackage.getResolvedCall(expression, trace.getBindingContext());
419 ReceiverValue receiverValue = ReceiverValue.IRRELEVANT_RECEIVER;
420 if (resolvedCall != null) {
421 receiverValue = ExpressionTypingUtils
422 .normalizeReceiverValueForVisibility(resolvedCall.getDispatchReceiver(), trace.getBindingContext());
423
424 }
425 if (Visibilities.isVisible(receiverValue, variableDescriptor, descriptor) && setterDescriptor != null
426 && !Visibilities.isVisible(receiverValue, setterDescriptor, descriptor)) {
427 report(Errors.INVISIBLE_SETTER.on(expression, variableDescriptor, setterDescriptor.getVisibility(),
428 variableDescriptor.getContainingDeclaration()), ctxt);
429 return true;
430 }
431 }
432 if ((isInitializedNotHere || !hasBackingField) && !variableDescriptor.isVar()
433 && !varWithValReassignErrorGenerated.contains(variableDescriptor)) {
434 boolean hasReassignMethodReturningUnit = false;
435 JetSimpleNameExpression operationReference = null;
436 PsiElement parent = expression.getParent();
437 if (parent instanceof JetBinaryExpression) {
438 operationReference = ((JetBinaryExpression) parent).getOperationReference();
439 }
440 else if (parent instanceof JetUnaryExpression) {
441 operationReference = ((JetUnaryExpression) parent).getOperationReference();
442 }
443 if (operationReference != null) {
444 DeclarationDescriptor descriptor = trace.get(BindingContext.REFERENCE_TARGET, operationReference);
445 if (descriptor instanceof FunctionDescriptor) {
446 if (KotlinBuiltIns.isUnit(((FunctionDescriptor) descriptor).getReturnType())) {
447 hasReassignMethodReturningUnit = true;
448 }
449 }
450 if (descriptor == null) {
451 Collection<? extends DeclarationDescriptor> descriptors =
452 trace.get(BindingContext.AMBIGUOUS_REFERENCE_TARGET, operationReference);
453 if (descriptors != null) {
454 for (DeclarationDescriptor referenceDescriptor : descriptors) {
455 if (KotlinBuiltIns.isUnit(((FunctionDescriptor) referenceDescriptor).getReturnType())) {
456 hasReassignMethodReturningUnit = true;
457 }
458 }
459 }
460 }
461 }
462 if (!hasReassignMethodReturningUnit) {
463 varWithValReassignErrorGenerated.add(variableDescriptor);
464 report(Errors.VAL_REASSIGNMENT.on(expression, variableDescriptor), ctxt);
465 return true;
466 }
467 }
468 return false;
469 }
470
471 private boolean checkAssignmentBeforeDeclaration(@NotNull VariableInitContext ctxt, @NotNull JetExpression expression) {
472 if (!ctxt.enterInitState.isDeclared && !ctxt.exitInitState.isDeclared
473 && !ctxt.enterInitState.isInitialized && ctxt.exitInitState.isInitialized) {
474 report(Errors.INITIALIZATION_BEFORE_DECLARATION.on(expression, ctxt.variableDescriptor), ctxt);
475 return true;
476 }
477 return false;
478 }
479
480 private boolean checkInitializationUsingBackingField(@NotNull VariableInitContext ctxt, @NotNull JetExpression expression) {
481 VariableDescriptor variableDescriptor = ctxt.variableDescriptor;
482 if (variableDescriptor instanceof PropertyDescriptor && !ctxt.enterInitState.isInitialized && ctxt.exitInitState.isInitialized) {
483 if (!variableDescriptor.isVar()) return false;
484 if (!trace.get(BindingContext.BACKING_FIELD_REQUIRED, (PropertyDescriptor) variableDescriptor)) return false;
485 PsiElement property = DescriptorToSourceUtils.descriptorToDeclaration(variableDescriptor);
486 assert property instanceof JetProperty;
487 if (((PropertyDescriptor) variableDescriptor).getModality() == Modality.FINAL && ((JetProperty) property).getSetter() == null) {
488 return false;
489 }
490 JetExpression variable = expression;
491 if (expression instanceof JetDotQualifiedExpression) {
492 if (((JetDotQualifiedExpression) expression).getReceiverExpression() instanceof JetThisExpression) {
493 variable = ((JetDotQualifiedExpression) expression).getSelectorExpression();
494 }
495 }
496 if (variable instanceof JetSimpleNameExpression) {
497 JetSimpleNameExpression simpleNameExpression = (JetSimpleNameExpression) variable;
498 if (simpleNameExpression.getReferencedNameElementType() != JetTokens.FIELD_IDENTIFIER) {
499 if (((PropertyDescriptor) variableDescriptor).getModality() != Modality.FINAL) {
500 report(Errors.INITIALIZATION_USING_BACKING_FIELD_OPEN_SETTER.on(expression, variableDescriptor), ctxt);
501 }
502 else {
503 report(Errors.INITIALIZATION_USING_BACKING_FIELD_CUSTOM_SETTER.on(expression, variableDescriptor), ctxt);
504 }
505 return true;
506 }
507 }
508 }
509 return false;
510 }
511
512 private boolean checkBackingField(@NotNull VariableContext cxtx, @NotNull JetElement element) {
513 VariableDescriptor variableDescriptor = cxtx.variableDescriptor;
514 boolean[] error = new boolean[1];
515 if (!isCorrectBackingFieldReference(element, cxtx, error, true)) return false;
516 if (error[0]) return true;
517 if (!(variableDescriptor instanceof PropertyDescriptor)) {
518 report(Errors.NOT_PROPERTY_BACKING_FIELD.on(element), cxtx);
519 return true;
520 }
521 PsiElement property = DescriptorToSourceUtils.descriptorToDeclaration(variableDescriptor);
522 boolean insideSelfAccessors = PsiTreeUtil.isAncestor(property, element, false);
523 if (!trace.get(BindingContext.BACKING_FIELD_REQUIRED, (PropertyDescriptor) variableDescriptor) &&
524 // not to generate error in accessors of abstract properties, there is one: declared accessor of abstract property
525 !insideSelfAccessors) {
526
527 if (((PropertyDescriptor) variableDescriptor).getModality() == Modality.ABSTRACT) {
528 report(NO_BACKING_FIELD_ABSTRACT_PROPERTY.on(element), cxtx);
529 }
530 else {
531 report(NO_BACKING_FIELD_CUSTOM_ACCESSORS.on(element), cxtx);
532 }
533 return true;
534 }
535 if (insideSelfAccessors) return false;
536
537 DeclarationDescriptor declarationDescriptor = BindingContextUtils.getEnclosingDescriptor(trace.getBindingContext(), element);
538
539 DeclarationDescriptor containingDeclaration = variableDescriptor.getContainingDeclaration();
540 if ((containingDeclaration instanceof ClassDescriptor)
541 && DescriptorUtils.isAncestor(containingDeclaration, declarationDescriptor, false)) {
542 return false;
543 }
544 report(Errors.INACCESSIBLE_BACKING_FIELD.on(element), cxtx);
545 return true;
546 }
547
548 private boolean isCorrectBackingFieldReference(
549 @Nullable JetElement element,
550 VariableContext ctxt,
551 boolean[] error,
552 boolean reportError
553 ) {
554 error[0] = false;
555 if (JetPsiUtil.isBackingFieldReference(element)) {
556 return true;
557 }
558 if (element instanceof JetDotQualifiedExpression && isCorrectBackingFieldReference(
559 ((JetDotQualifiedExpression) element).getSelectorExpression(), ctxt, error, false)) {
560 if (((JetDotQualifiedExpression) element).getReceiverExpression() instanceof JetThisExpression) {
561 return true;
562 }
563 error[0] = true;
564 if (reportError) {
565 report(Errors.INACCESSIBLE_BACKING_FIELD.on(element), ctxt);
566 }
567 }
568 return false;
569 }
570
571 private void recordInitializedVariables(
572 @NotNull Pseudocode pseudocode,
573 @NotNull Map<Instruction, Edges<Map<VariableDescriptor, PseudocodeVariablesData.VariableInitState>>> initializersMap
574 ) {
575 Edges<Map<VariableDescriptor, VariableInitState>> initializers = initializersMap.get(pseudocode.getExitInstruction());
576 Set<VariableDescriptor> declaredVariables = getPseudocodeVariablesData().getDeclaredVariables(pseudocode, false);
577 for (VariableDescriptor variable : declaredVariables) {
578 if (variable instanceof PropertyDescriptor) {
579 PseudocodeVariablesData.VariableInitState variableInitState = initializers.getIncoming().get(variable);
580 if (variableInitState == null) return;
581 trace.record(BindingContext.IS_INITIALIZED, (PropertyDescriptor) variable, variableInitState.isInitialized);
582 }
583 }
584 }
585
586 ////////////////////////////////////////////////////////////////////////////////
587 // "Unused variable" & "unused value" analyses
588
589 public void markUnusedVariables() {
590 final PseudocodeVariablesData pseudocodeVariablesData = getPseudocodeVariablesData();
591 Map<Instruction, Edges<Map<VariableDescriptor, VariableUseState>>> variableStatusData =
592 pseudocodeVariablesData.getVariableUseStatusData();
593 final Map<Instruction, DiagnosticFactory<?>> reportedDiagnosticMap = Maps.newHashMap();
594 InstructionDataAnalyzeStrategy<Map<VariableDescriptor, VariableUseState>> variableStatusAnalyzeStrategy =
595 new InstructionDataAnalyzeStrategy<Map<VariableDescriptor, VariableUseState>>() {
596 @Override
597 public void execute(
598 @NotNull Instruction instruction,
599 @Nullable Map<VariableDescriptor, VariableUseState> in,
600 @Nullable Map<VariableDescriptor, VariableUseState> out
601 ) {
602
603 assert in != null && out != null;
604 VariableContext ctxt = new VariableUseContext(instruction, reportedDiagnosticMap, in, out);
605 Set<VariableDescriptor> declaredVariables =
606 pseudocodeVariablesData.getDeclaredVariables(instruction.getOwner(), false);
607 VariableDescriptor variableDescriptor = PseudocodeUtil.extractVariableDescriptorIfAny(
608 instruction, false, trace.getBindingContext());
609 if (variableDescriptor == null || !declaredVariables.contains(variableDescriptor)
610 || !ExpressionTypingUtils.isLocal(variableDescriptor.getContainingDeclaration(), variableDescriptor)) {
611 return;
612 }
613 PseudocodeVariablesData.VariableUseState variableUseState = in.get(variableDescriptor);
614 if (instruction instanceof WriteValueInstruction) {
615 if (trace.get(CAPTURED_IN_CLOSURE, variableDescriptor) != null) return;
616 JetElement element = ((WriteValueInstruction) instruction).getElement();
617 if (variableUseState != READ) {
618 if (element instanceof JetBinaryExpression &&
619 ((JetBinaryExpression) element).getOperationToken() == JetTokens.EQ) {
620 JetExpression right = ((JetBinaryExpression) element).getRight();
621 if (right != null) {
622 report(Errors.UNUSED_VALUE.on(right, right, variableDescriptor), ctxt);
623 }
624 }
625 else if (element instanceof JetPostfixExpression) {
626 IElementType operationToken =
627 ((JetPostfixExpression) element).getOperationReference().getReferencedNameElementType();
628 if (operationToken == JetTokens.PLUSPLUS || operationToken == JetTokens.MINUSMINUS) {
629 report(Errors.UNUSED_CHANGED_VALUE.on(element, element), ctxt);
630 }
631 }
632 }
633 }
634 else if (instruction instanceof VariableDeclarationInstruction) {
635 JetDeclaration element = ((VariableDeclarationInstruction) instruction).getVariableDeclarationElement();
636 if (!(element instanceof JetNamedDeclaration)) return;
637 PsiElement nameIdentifier = ((JetNamedDeclaration) element).getNameIdentifier();
638 if (nameIdentifier == null) return;
639 if (!VariableUseState.isUsed(variableUseState)) {
640 if (JetPsiUtil.isVariableNotParameterDeclaration(element)) {
641 report(Errors.UNUSED_VARIABLE.on((JetNamedDeclaration) element, variableDescriptor), ctxt);
642 }
643 else if (element instanceof JetParameter) {
644 PsiElement owner = element.getParent().getParent();
645 if (owner instanceof JetFunction) {
646 MainFunctionDetector mainFunctionDetector = new MainFunctionDetector(trace.getBindingContext());
647 boolean isMain = (owner instanceof JetNamedFunction) && mainFunctionDetector.isMain((JetNamedFunction) owner);
648 if (owner instanceof JetFunctionLiteral) return;
649 DeclarationDescriptor descriptor = trace.get(BindingContext.DECLARATION_TO_DESCRIPTOR, owner);
650 assert descriptor instanceof FunctionDescriptor : owner.getText();
651 FunctionDescriptor functionDescriptor = (FunctionDescriptor) descriptor;
652 if (!isMain && !functionDescriptor.getModality().isOverridable()
653 && functionDescriptor.getOverriddenDescriptors().isEmpty()) {
654 report(Errors.UNUSED_PARAMETER.on((JetParameter) element, variableDescriptor), ctxt);
655 }
656 } else if (owner instanceof JetClass) {
657 if (!((JetParameter) element).hasValOrVarNode() && !((JetClass) owner).isAnnotation()) {
658 report(Errors.UNUSED_PARAMETER.on((JetParameter) element, variableDescriptor), ctxt);
659 }
660 }
661 }
662 }
663 else if (variableUseState == ONLY_WRITTEN_NEVER_READ && JetPsiUtil.isVariableNotParameterDeclaration(element)) {
664 report(Errors.ASSIGNED_BUT_NEVER_ACCESSED_VARIABLE.on((JetNamedDeclaration) element, variableDescriptor), ctxt);
665 }
666 else if (variableUseState == WRITTEN_AFTER_READ && element instanceof JetVariableDeclaration) {
667 if (element instanceof JetProperty) {
668 JetExpression initializer = ((JetProperty) element).getInitializer();
669 if (initializer != null) {
670 report(Errors.VARIABLE_WITH_REDUNDANT_INITIALIZER.on(initializer, variableDescriptor), ctxt);
671 }
672 }
673 else if (element instanceof JetMultiDeclarationEntry) {
674 report(VARIABLE_WITH_REDUNDANT_INITIALIZER.on(element, variableDescriptor), ctxt);
675 }
676 }
677 }
678 }
679 };
680 PseudocodeTraverserPackage.traverse(pseudocode, TraversalOrder.BACKWARD, variableStatusData, variableStatusAnalyzeStrategy);
681 }
682
683 ////////////////////////////////////////////////////////////////////////////////
684 // "Unused expressions" in block
685
686 public void markUnusedExpressions() {
687 final Map<Instruction, DiagnosticFactory<?>> reportedDiagnosticMap = Maps.newHashMap();
688 PseudocodeTraverserPackage.traverse(
689 pseudocode, FORWARD, new JetFlowInformationProvider.FunctionVoid1<Instruction>() {
690 @Override
691 public void execute(@NotNull Instruction instruction) {
692 if (!(instruction instanceof JetElementInstruction)) return;
693
694 JetElement element = ((JetElementInstruction)instruction).getElement();
695 if (!(element instanceof JetExpression)) return;
696
697 if (BindingContextUtilPackage.isUsedAsStatement((JetExpression) element, trace.getBindingContext())
698 && PseudocodePackage.getSideEffectFree(instruction)) {
699 VariableContext ctxt = new VariableContext(instruction, reportedDiagnosticMap);
700 report(
701 element instanceof JetFunctionLiteralExpression
702 ? Errors.UNUSED_FUNCTION_LITERAL.on((JetFunctionLiteralExpression) element)
703 : Errors.UNUSED_EXPRESSION.on(element),
704 ctxt
705 );
706 }
707 }
708 }
709 );
710 }
711
712 ////////////////////////////////////////////////////////////////////////////////
713 // Statements
714
715 public void markStatements() {
716 PseudocodeTraverserPackage.traverse(
717 pseudocode, FORWARD, new JetFlowInformationProvider.FunctionVoid1<Instruction>() {
718 @Override
719 public void execute(@NotNull Instruction instruction) {
720 PseudoValue value = instruction instanceof InstructionWithValue
721 ? ((InstructionWithValue) instruction).getOutputValue()
722 : null;
723 Pseudocode pseudocode = instruction.getOwner();
724 boolean isUsedAsExpression = !pseudocode.getUsages(value).isEmpty();
725 for (JetElement element : pseudocode.getValueElements(value)) {
726 trace.record(BindingContext.USED_AS_EXPRESSION, element, isUsedAsExpression);
727 }
728 }
729 }
730 );
731 }
732
733 public void markWhenWithoutElse() {
734 PseudocodeTraverserPackage.traverse(
735 pseudocode, FORWARD, new JetFlowInformationProvider.FunctionVoid1<Instruction>() {
736 @Override
737 public void execute(@NotNull Instruction instruction) {
738 PseudoValue value = instruction instanceof InstructionWithValue
739 ? ((InstructionWithValue) instruction).getOutputValue()
740 : null;
741 for (JetElement element : instruction.getOwner().getValueElements(value)) {
742 if (element instanceof JetWhenExpression) {
743 JetWhenExpression whenExpression = (JetWhenExpression) element;
744 if (whenExpression.getElseExpression() == null && WhenChecker.mustHaveElse(whenExpression, trace)) {
745 trace.report(NO_ELSE_IN_WHEN.on(whenExpression));
746 }
747 }
748 }
749 }
750 }
751 );
752 }
753
754 ////////////////////////////////////////////////////////////////////////////////
755 // Tail calls
756
757 public void markTailCalls() {
758 final DeclarationDescriptor subroutineDescriptor = trace.get(BindingContext.DECLARATION_TO_DESCRIPTOR, subroutine);
759 if (!(subroutineDescriptor instanceof FunctionDescriptor)) return;
760 if (!KotlinBuiltIns.isTailRecursive(subroutineDescriptor)) return;
761
762 // finally blocks are copied which leads to multiple diagnostics reported on one instruction
763 class KindAndCall {
764 TailRecursionKind kind;
765 ResolvedCall<?> call;
766
767 KindAndCall(TailRecursionKind kind, ResolvedCall<?> call) {
768 this.kind = kind;
769 this.call = call;
770 }
771 }
772 final Map<JetElement, KindAndCall> calls = new HashMap<JetElement, KindAndCall>();
773 PseudocodeTraverserPackage.traverse(
774 pseudocode,
775 FORWARD,
776 new FunctionVoid1<Instruction>() {
777 public void execute(@NotNull Instruction instruction) {
778 if (!(instruction instanceof CallInstruction)) return;
779 CallInstruction callInstruction = (CallInstruction) instruction;
780
781 ResolvedCall<?> resolvedCall = getResolvedCall(callInstruction.getElement(), trace.getBindingContext());
782 if (resolvedCall == null) return;
783
784 // is this a recursive call?
785 CallableDescriptor functionDescriptor = resolvedCall.getResultingDescriptor();
786 if (!functionDescriptor.getOriginal().equals(subroutineDescriptor)) return;
787
788 JetElement element = callInstruction.getElement();
789 //noinspection unchecked
790 JetExpression parent = PsiTreeUtil.getParentOfType(
791 element,
792 JetTryExpression.class, JetFunction.class, JetClassInitializer.class
793 );
794
795 if (parent instanceof JetTryExpression) {
796 // We do not support tail calls Collections.singletonMap() try-catch-finally, for simplicity of the mental model
797 // very few cases there would be real tail-calls, and it's often not so easy for the user to see why
798 calls.put(element, new KindAndCall(IN_TRY, resolvedCall));
799 return;
800 }
801
802 boolean isTail = PseudocodeTraverserPackage.traverseFollowingInstructions(
803 callInstruction,
804 new HashSet<Instruction>(),
805 FORWARD,
806 new TailRecursionDetector(subroutine, callInstruction)
807 );
808
809 boolean sameDispatchReceiver = sameDispatchReceiver(resolvedCall);
810
811 TailRecursionKind kind = isTail && sameDispatchReceiver ? TAIL_CALL : NON_TAIL;
812
813 KindAndCall kindAndCall = calls.get(element);
814 calls.put(element,
815 new KindAndCall(
816 combineKinds(kind, kindAndCall == null ? null : kindAndCall.kind),
817 resolvedCall
818 )
819 );
820 }
821 }
822 );
823 boolean hasTailCalls = false;
824 for (Map.Entry<JetElement, KindAndCall> entry : calls.entrySet()) {
825 JetElement element = entry.getKey();
826 KindAndCall kindAndCall = entry.getValue();
827 switch (kindAndCall.kind) {
828 case TAIL_CALL:
829 trace.record(TAIL_RECURSION_CALL, kindAndCall.call, TailRecursionKind.TAIL_CALL);
830 hasTailCalls = true;
831 break;
832 case IN_TRY:
833 trace.report(Errors.TAIL_RECURSION_IN_TRY_IS_NOT_SUPPORTED.on(element));
834 break;
835 case NON_TAIL:
836 trace.report(Errors.NON_TAIL_RECURSIVE_CALL.on(element));
837 break;
838 }
839 }
840
841 if (!hasTailCalls) {
842 trace.report(Errors.NO_TAIL_CALLS_FOUND.on((JetNamedFunction) subroutine));
843 }
844 }
845
846 private boolean sameDispatchReceiver(ResolvedCall<?> resolvedCall) {
847 // A tail call is not allowed to change dispatch receiver
848 // class C {
849 // fun foo(other: C) {
850 // other.foo(this) // not a tail call
851 // }
852 // }
853 ReceiverParameterDescriptor dispatchReceiverParameter = resolvedCall.getResultingDescriptor().getDispatchReceiverParameter();
854 ReceiverValue dispatchReceiverValue = resolvedCall.getDispatchReceiver();
855 if (dispatchReceiverParameter == null || !dispatchReceiverValue.exists()) return true;
856
857 DeclarationDescriptor classDescriptor = null;
858 if (dispatchReceiverValue instanceof ThisReceiver) {
859 // foo() -- implicit receiver
860 classDescriptor = ((ThisReceiver) dispatchReceiverValue).getDeclarationDescriptor();
861 }
862 else if (dispatchReceiverValue instanceof ExpressionReceiver) {
863 JetExpression expression = JetPsiUtil.deparenthesize(((ExpressionReceiver) dispatchReceiverValue).getExpression());
864 if (expression instanceof JetThisExpression) {
865 // this.foo() -- explicit receiver
866 JetThisExpression thisExpression = (JetThisExpression) expression;
867 classDescriptor = trace.get(BindingContext.REFERENCE_TARGET, thisExpression.getInstanceReference());
868 }
869 }
870 return dispatchReceiverParameter.getContainingDeclaration() == classDescriptor;
871 }
872
873 private static TailRecursionKind combineKinds(TailRecursionKind kind, @Nullable TailRecursionKind existingKind) {
874 TailRecursionKind resultingKind;
875 if (existingKind == null || existingKind == kind) {
876 resultingKind = kind;
877 }
878 else {
879 if (check(kind, existingKind, IN_TRY, TAIL_CALL)) {
880 resultingKind = IN_TRY;
881 }
882 else if (check(kind, existingKind, IN_TRY, NON_TAIL)) {
883 resultingKind = IN_TRY;
884 }
885 else {
886 // TAIL_CALL, NON_TAIL
887 resultingKind = NON_TAIL;
888 }
889 }
890 return resultingKind;
891 }
892
893 private static boolean check(Object a, Object b, Object x, Object y) {
894 return (a == x && b == y) || (a == y && b == x);
895 }
896
897 ////////////////////////////////////////////////////////////////////////////////
898 // Utility classes and methods
899
900 /**
901 * The method provides reporting of the same diagnostic only once for copied instructions
902 * (depends on whether it should be reported for all or only for one of the copies)
903 */
904 private void report(
905 @NotNull Diagnostic diagnostic,
906 @NotNull VariableContext ctxt
907 ) {
908 Instruction instruction = ctxt.instruction;
909 if (instruction.getCopies().isEmpty()) {
910 trace.report(diagnostic);
911 return;
912 }
913 Map<Instruction, DiagnosticFactory<?>> previouslyReported = ctxt.reportedDiagnosticMap;
914 previouslyReported.put(instruction, diagnostic.getFactory());
915
916 boolean alreadyReported = false;
917 boolean sameErrorForAllCopies = true;
918 for (Instruction copy : instruction.getCopies()) {
919 DiagnosticFactory<?> previouslyReportedErrorFactory = previouslyReported.get(copy);
920 if (previouslyReportedErrorFactory != null) {
921 alreadyReported = true;
922 }
923
924 if (previouslyReportedErrorFactory != diagnostic.getFactory()) {
925 sameErrorForAllCopies = false;
926 }
927 }
928
929 if (mustBeReportedOnAllCopies(diagnostic.getFactory())) {
930 if (sameErrorForAllCopies) {
931 trace.report(diagnostic);
932 }
933 }
934 else {
935 //only one reporting required
936 if (!alreadyReported) {
937 trace.report(diagnostic);
938 }
939 }
940 }
941
942 private static boolean mustBeReportedOnAllCopies(@NotNull DiagnosticFactory<?> diagnosticFactory) {
943 return diagnosticFactory == UNUSED_VARIABLE
944 || diagnosticFactory == UNUSED_PARAMETER
945 || diagnosticFactory == UNUSED_CHANGED_VALUE;
946 }
947
948
949 private class VariableContext {
950 final Map<Instruction, DiagnosticFactory<?>> reportedDiagnosticMap;
951 final Instruction instruction;
952 final VariableDescriptor variableDescriptor;
953
954 private VariableContext(
955 @NotNull Instruction instruction,
956 @NotNull Map<Instruction, DiagnosticFactory<?>> map
957 ) {
958 this.instruction = instruction;
959 reportedDiagnosticMap = map;
960 variableDescriptor = PseudocodeUtil.extractVariableDescriptorIfAny(instruction, true, trace.getBindingContext());
961 }
962 }
963
964 private class VariableInitContext extends VariableContext {
965 final VariableInitState enterInitState;
966 final VariableInitState exitInitState;
967
968 private VariableInitContext(
969 @NotNull Instruction instruction,
970 @NotNull Map<Instruction, DiagnosticFactory<?>> map,
971 @NotNull Map<VariableDescriptor, VariableInitState> in,
972 @NotNull Map<VariableDescriptor, VariableInitState> out,
973 @NotNull LexicalScopeVariableInfo lexicalScopeVariableInfo
974 ) {
975 super(instruction, map);
976 enterInitState = initialize(variableDescriptor, lexicalScopeVariableInfo, in);
977 exitInitState = initialize(variableDescriptor, lexicalScopeVariableInfo, out);
978 }
979
980 private VariableInitState initialize(
981 VariableDescriptor variableDescriptor,
982 LexicalScopeVariableInfo lexicalScopeVariableInfo,
983 Map<VariableDescriptor, VariableInitState> map
984 ) {
985 if (variableDescriptor == null) return null;
986 VariableInitState state = map.get(variableDescriptor);
987 if (state != null) return state;
988 return PseudocodeVariablesData.getDefaultValueForInitializers(variableDescriptor, instruction, lexicalScopeVariableInfo);
989 }
990 }
991
992 private class VariableUseContext extends VariableContext {
993 final VariableUseState enterUseState;
994 final VariableUseState exitUseState;
995
996
997 private VariableUseContext(
998 @NotNull Instruction instruction,
999 @NotNull Map<Instruction, DiagnosticFactory<?>> map,
1000 @NotNull Map<VariableDescriptor, VariableUseState> in,
1001 @NotNull Map<VariableDescriptor, VariableUseState> out
1002 ) {
1003 super(instruction, map);
1004 enterUseState = variableDescriptor != null ? in.get(variableDescriptor) : null;
1005 exitUseState = variableDescriptor != null ? out.get(variableDescriptor) : null;
1006 }
1007 }
1008
1009 //TODO after KT-4621 rewrite to Kotlin
1010 public abstract static class InstructionDataAnalyzeStrategy<D> implements Function3<Instruction, D, D, Unit> {
1011 @Override
1012 public Unit invoke(Instruction instruction, D enterData, D exitData) {
1013 execute(instruction, enterData, exitData);
1014 return Unit.INSTANCE$;
1015 }
1016
1017 public abstract void execute(Instruction instruction, D enterData, D exitData);
1018 }
1019
1020 public abstract static class FunctionVoid1<P> implements Function1<P, Unit> {
1021 @Override
1022 public Unit invoke(P p) {
1023 execute(p);
1024 return Unit.INSTANCE$;
1025 }
1026
1027 public abstract void execute(P p);
1028 }
1029 }