1 //=- AnalysisBasedWarnings.cpp - Sema warnings based on libAnalysis -*- C++ -*-=//
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7 //===----------------------------------------------------------------------===//
9 // This file defines analysis_warnings::[Policy,Executor].
10 // Together they are used by Sema to issue warnings based on inexpensive
11 // static analysis algorithms in libAnalysis.
13 //===----------------------------------------------------------------------===//
15 #include "clang/Sema/AnalysisBasedWarnings.h"
16 #include "clang/AST/DeclCXX.h"
17 #include "clang/AST/DeclObjC.h"
18 #include "clang/AST/EvaluatedExprVisitor.h"
19 #include "clang/AST/ExprCXX.h"
20 #include "clang/AST/ExprObjC.h"
21 #include "clang/AST/ParentMap.h"
22 #include "clang/AST/RecursiveASTVisitor.h"
23 #include "clang/AST/StmtCXX.h"
24 #include "clang/AST/StmtObjC.h"
25 #include "clang/AST/StmtVisitor.h"
26 #include "clang/Analysis/Analyses/CFGReachabilityAnalysis.h"
27 #include "clang/Analysis/Analyses/Consumed.h"
28 #include "clang/Analysis/Analyses/ReachableCode.h"
29 #include "clang/Analysis/Analyses/ThreadSafety.h"
30 #include "clang/Analysis/Analyses/UninitializedValues.h"
31 #include "clang/Analysis/AnalysisDeclContext.h"
32 #include "clang/Analysis/CFG.h"
33 #include "clang/Analysis/CFGStmtMap.h"
34 #include "clang/Basic/SourceLocation.h"
35 #include "clang/Basic/SourceManager.h"
36 #include "clang/Lex/Preprocessor.h"
37 #include "clang/Sema/ScopeInfo.h"
38 #include "clang/Sema/SemaInternal.h"
39 #include "llvm/ADT/BitVector.h"
40 #include "llvm/ADT/MapVector.h"
41 #include "llvm/ADT/SmallString.h"
42 #include "llvm/ADT/SmallVector.h"
43 #include "llvm/ADT/StringRef.h"
44 #include "llvm/Support/Casting.h"
49 using namespace clang;
51 //===----------------------------------------------------------------------===//
52 // Unreachable code analysis.
53 //===----------------------------------------------------------------------===//
56 class UnreachableCodeHandler : public reachable_code::Callback {
58 SourceRange PreviousSilenceableCondVal;
61 UnreachableCodeHandler(Sema &s) : S(s) {}
63 void HandleUnreachable(reachable_code::UnreachableKind UK,
65 SourceRange SilenceableCondVal,
67 SourceRange R2) override {
68 // Avoid reporting multiple unreachable code diagnostics that are
69 // triggered by the same conditional value.
70 if (PreviousSilenceableCondVal.isValid() &&
71 SilenceableCondVal.isValid() &&
72 PreviousSilenceableCondVal == SilenceableCondVal)
74 PreviousSilenceableCondVal = SilenceableCondVal;
76 unsigned diag = diag::warn_unreachable;
78 case reachable_code::UK_Break:
79 diag = diag::warn_unreachable_break;
81 case reachable_code::UK_Return:
82 diag = diag::warn_unreachable_return;
84 case reachable_code::UK_Loop_Increment:
85 diag = diag::warn_unreachable_loop_increment;
87 case reachable_code::UK_Other:
91 S.Diag(L, diag) << R1 << R2;
93 SourceLocation Open = SilenceableCondVal.getBegin();
95 SourceLocation Close = SilenceableCondVal.getEnd();
96 Close = S.getLocForEndOfToken(Close);
97 if (Close.isValid()) {
98 S.Diag(Open, diag::note_unreachable_silence)
99 << FixItHint::CreateInsertion(Open, "/* DISABLES CODE */ (")
100 << FixItHint::CreateInsertion(Close, ")");
105 } // anonymous namespace
107 /// CheckUnreachable - Check for unreachable code.
108 static void CheckUnreachable(Sema &S, AnalysisDeclContext &AC) {
109 // As a heuristic prune all diagnostics not in the main file. Currently
110 // the majority of warnings in headers are false positives. These
111 // are largely caused by configuration state, e.g. preprocessor
112 // defined code, etc.
114 // Note that this is also a performance optimization. Analyzing
115 // headers many times can be expensive.
116 if (!S.getSourceManager().isInMainFile(AC.getDecl()->getBeginLoc()))
119 UnreachableCodeHandler UC(S);
120 reachable_code::FindUnreachableCode(AC, S.getPreprocessor(), UC);
124 /// Warn on logical operator errors in CFGBuilder
125 class LogicalErrorHandler : public CFGCallback {
129 LogicalErrorHandler(Sema &S) : CFGCallback(), S(S) {}
131 static bool HasMacroID(const Expr *E) {
132 if (E->getExprLoc().isMacroID())
135 // Recurse to children.
136 for (const Stmt *SubStmt : E->children())
137 if (const Expr *SubExpr = dyn_cast_or_null<Expr>(SubStmt))
138 if (HasMacroID(SubExpr))
144 void compareAlwaysTrue(const BinaryOperator *B, bool isAlwaysTrue) override {
148 SourceRange DiagRange = B->getSourceRange();
149 S.Diag(B->getExprLoc(), diag::warn_tautological_overlap_comparison)
150 << DiagRange << isAlwaysTrue;
153 void compareBitwiseEquality(const BinaryOperator *B,
154 bool isAlwaysTrue) override {
158 SourceRange DiagRange = B->getSourceRange();
159 S.Diag(B->getExprLoc(), diag::warn_comparison_bitwise_always)
160 << DiagRange << isAlwaysTrue;
163 } // anonymous namespace
165 //===----------------------------------------------------------------------===//
166 // Check for infinite self-recursion in functions
167 //===----------------------------------------------------------------------===//
169 // Returns true if the function is called anywhere within the CFGBlock.
170 // For member functions, the additional condition of being call from the
171 // this pointer is required.
172 static bool hasRecursiveCallInPath(const FunctionDecl *FD, CFGBlock &Block) {
173 // Process all the Stmt's in this block to find any calls to FD.
174 for (const auto &B : Block) {
175 if (B.getKind() != CFGElement::Statement)
178 const CallExpr *CE = dyn_cast<CallExpr>(B.getAs<CFGStmt>()->getStmt());
179 if (!CE || !CE->getCalleeDecl() ||
180 CE->getCalleeDecl()->getCanonicalDecl() != FD)
183 // Skip function calls which are qualified with a templated class.
184 if (const DeclRefExpr *DRE =
185 dyn_cast<DeclRefExpr>(CE->getCallee()->IgnoreParenImpCasts())) {
186 if (NestedNameSpecifier *NNS = DRE->getQualifier()) {
187 if (NNS->getKind() == NestedNameSpecifier::TypeSpec &&
188 isa<TemplateSpecializationType>(NNS->getAsType())) {
194 const CXXMemberCallExpr *MCE = dyn_cast<CXXMemberCallExpr>(CE);
195 if (!MCE || isa<CXXThisExpr>(MCE->getImplicitObjectArgument()) ||
196 !MCE->getMethodDecl()->isVirtual())
202 // Returns true if every path from the entry block passes through a call to FD.
203 static bool checkForRecursiveFunctionCall(const FunctionDecl *FD, CFG *cfg) {
204 llvm::SmallPtrSet<CFGBlock *, 16> Visited;
205 llvm::SmallVector<CFGBlock *, 16> WorkList;
206 // Keep track of whether we found at least one recursive path.
207 bool foundRecursion = false;
209 const unsigned ExitID = cfg->getExit().getBlockID();
211 // Seed the work list with the entry block.
212 WorkList.push_back(&cfg->getEntry());
214 while (!WorkList.empty()) {
215 CFGBlock *Block = WorkList.pop_back_val();
217 for (auto I = Block->succ_begin(), E = Block->succ_end(); I != E; ++I) {
218 if (CFGBlock *SuccBlock = *I) {
219 if (!Visited.insert(SuccBlock).second)
222 // Found a path to the exit node without a recursive call.
223 if (ExitID == SuccBlock->getBlockID())
226 // If the successor block contains a recursive call, end analysis there.
227 if (hasRecursiveCallInPath(FD, *SuccBlock)) {
228 foundRecursion = true;
232 WorkList.push_back(SuccBlock);
236 return foundRecursion;
239 static void checkRecursiveFunction(Sema &S, const FunctionDecl *FD,
240 const Stmt *Body, AnalysisDeclContext &AC) {
241 FD = FD->getCanonicalDecl();
243 // Only run on non-templated functions and non-templated members of
244 // templated classes.
245 if (FD->getTemplatedKind() != FunctionDecl::TK_NonTemplate &&
246 FD->getTemplatedKind() != FunctionDecl::TK_MemberSpecialization)
249 CFG *cfg = AC.getCFG();
252 // If the exit block is unreachable, skip processing the function.
253 if (cfg->getExit().pred_empty())
256 // Emit diagnostic if a recursive function call is detected for all paths.
257 if (checkForRecursiveFunctionCall(FD, cfg))
258 S.Diag(Body->getBeginLoc(), diag::warn_infinite_recursive_function);
261 //===----------------------------------------------------------------------===//
262 // Check for throw in a non-throwing function.
263 //===----------------------------------------------------------------------===//
265 /// Determine whether an exception thrown by E, unwinding from ThrowBlock,
266 /// can reach ExitBlock.
267 static bool throwEscapes(Sema &S, const CXXThrowExpr *E, CFGBlock &ThrowBlock,
269 SmallVector<CFGBlock *, 16> Stack;
270 llvm::BitVector Queued(Body->getNumBlockIDs());
272 Stack.push_back(&ThrowBlock);
273 Queued[ThrowBlock.getBlockID()] = true;
275 while (!Stack.empty()) {
276 CFGBlock &UnwindBlock = *Stack.back();
279 for (auto &Succ : UnwindBlock.succs()) {
280 if (!Succ.isReachable() || Queued[Succ->getBlockID()])
283 if (Succ->getBlockID() == Body->getExit().getBlockID())
287 dyn_cast_or_null<CXXCatchStmt>(Succ->getLabel())) {
288 QualType Caught = Catch->getCaughtType();
289 if (Caught.isNull() || // catch (...) catches everything
290 !E->getSubExpr() || // throw; is considered cuaght by any handler
291 S.handlerCanCatch(Caught, E->getSubExpr()->getType()))
292 // Exception doesn't escape via this path.
295 Stack.push_back(Succ);
296 Queued[Succ->getBlockID()] = true;
304 static void visitReachableThrows(
306 llvm::function_ref<void(const CXXThrowExpr *, CFGBlock &)> Visit) {
307 llvm::BitVector Reachable(BodyCFG->getNumBlockIDs());
308 clang::reachable_code::ScanReachableFromBlock(&BodyCFG->getEntry(), Reachable);
309 for (CFGBlock *B : *BodyCFG) {
310 if (!Reachable[B->getBlockID()])
312 for (CFGElement &E : *B) {
313 Optional<CFGStmt> S = E.getAs<CFGStmt>();
316 if (auto *Throw = dyn_cast<CXXThrowExpr>(S->getStmt()))
322 static void EmitDiagForCXXThrowInNonThrowingFunc(Sema &S, SourceLocation OpLoc,
323 const FunctionDecl *FD) {
324 if (!S.getSourceManager().isInSystemHeader(OpLoc) &&
325 FD->getTypeSourceInfo()) {
326 S.Diag(OpLoc, diag::warn_throw_in_noexcept_func) << FD;
327 if (S.getLangOpts().CPlusPlus11 &&
328 (isa<CXXDestructorDecl>(FD) ||
329 FD->getDeclName().getCXXOverloadedOperator() == OO_Delete ||
330 FD->getDeclName().getCXXOverloadedOperator() == OO_Array_Delete)) {
331 if (const auto *Ty = FD->getTypeSourceInfo()->getType()->
332 getAs<FunctionProtoType>())
333 S.Diag(FD->getLocation(), diag::note_throw_in_dtor)
334 << !isa<CXXDestructorDecl>(FD) << !Ty->hasExceptionSpec()
335 << FD->getExceptionSpecSourceRange();
337 S.Diag(FD->getLocation(), diag::note_throw_in_function)
338 << FD->getExceptionSpecSourceRange();
342 static void checkThrowInNonThrowingFunc(Sema &S, const FunctionDecl *FD,
343 AnalysisDeclContext &AC) {
344 CFG *BodyCFG = AC.getCFG();
347 if (BodyCFG->getExit().pred_empty())
349 visitReachableThrows(BodyCFG, [&](const CXXThrowExpr *Throw, CFGBlock &Block) {
350 if (throwEscapes(S, Throw, Block, BodyCFG))
351 EmitDiagForCXXThrowInNonThrowingFunc(S, Throw->getThrowLoc(), FD);
355 static bool isNoexcept(const FunctionDecl *FD) {
356 const auto *FPT = FD->getType()->castAs<FunctionProtoType>();
357 if (FPT->isNothrow() || FD->hasAttr<NoThrowAttr>())
362 //===----------------------------------------------------------------------===//
363 // Check for missing return value.
364 //===----------------------------------------------------------------------===//
366 enum ControlFlowKind {
371 NeverFallThroughOrReturn
374 /// CheckFallThrough - Check that we don't fall off the end of a
375 /// Statement that should return a value.
377 /// \returns AlwaysFallThrough iff we always fall off the end of the statement,
378 /// MaybeFallThrough iff we might or might not fall off the end,
379 /// NeverFallThroughOrReturn iff we never fall off the end of the statement or
380 /// return. We assume NeverFallThrough iff we never fall off the end of the
381 /// statement but we may return. We assume that functions not marked noreturn
383 static ControlFlowKind CheckFallThrough(AnalysisDeclContext &AC) {
384 CFG *cfg = AC.getCFG();
385 if (!cfg) return UnknownFallThrough;
387 // The CFG leaves in dead things, and we don't want the dead code paths to
388 // confuse us, so we mark all live things first.
389 llvm::BitVector live(cfg->getNumBlockIDs());
390 unsigned count = reachable_code::ScanReachableFromBlock(&cfg->getEntry(),
393 bool AddEHEdges = AC.getAddEHEdges();
394 if (!AddEHEdges && count != cfg->getNumBlockIDs())
395 // When there are things remaining dead, and we didn't add EH edges
396 // from CallExprs to the catch clauses, we have to go back and
397 // mark them as live.
398 for (const auto *B : *cfg) {
399 if (!live[B->getBlockID()]) {
400 if (B->pred_begin() == B->pred_end()) {
401 const Stmt *Term = B->getTerminatorStmt();
402 if (Term && isa<CXXTryStmt>(Term))
403 // When not adding EH edges from calls, catch clauses
404 // can otherwise seem dead. Avoid noting them as dead.
405 count += reachable_code::ScanReachableFromBlock(B, live);
411 // Now we know what is live, we check the live precessors of the exit block
412 // and look for fall through paths, being careful to ignore normal returns,
413 // and exceptional paths.
414 bool HasLiveReturn = false;
415 bool HasFakeEdge = false;
416 bool HasPlainEdge = false;
417 bool HasAbnormalEdge = false;
419 // Ignore default cases that aren't likely to be reachable because all
420 // enums in a switch(X) have explicit case statements.
421 CFGBlock::FilterOptions FO;
422 FO.IgnoreDefaultsWithCoveredEnums = 1;
424 for (CFGBlock::filtered_pred_iterator I =
425 cfg->getExit().filtered_pred_start_end(FO);
427 const CFGBlock &B = **I;
428 if (!live[B.getBlockID()])
431 // Skip blocks which contain an element marked as no-return. They don't
432 // represent actually viable edges into the exit block, so mark them as
434 if (B.hasNoReturnElement()) {
435 HasAbnormalEdge = true;
439 // Destructors can appear after the 'return' in the CFG. This is
440 // normal. We need to look pass the destructors for the return
441 // statement (if it exists).
442 CFGBlock::const_reverse_iterator ri = B.rbegin(), re = B.rend();
444 for ( ; ri != re ; ++ri)
445 if (ri->getAs<CFGStmt>())
448 // No more CFGElements in the block?
450 const Stmt *Term = B.getTerminatorStmt();
451 if (Term && isa<CXXTryStmt>(Term)) {
452 HasAbnormalEdge = true;
455 // A labeled empty statement, or the entry block...
460 CFGStmt CS = ri->castAs<CFGStmt>();
461 const Stmt *S = CS.getStmt();
462 if (isa<ReturnStmt>(S) || isa<CoreturnStmt>(S)) {
463 HasLiveReturn = true;
466 if (isa<ObjCAtThrowStmt>(S)) {
470 if (isa<CXXThrowExpr>(S)) {
474 if (isa<MSAsmStmt>(S)) {
475 // TODO: Verify this is correct.
477 HasLiveReturn = true;
480 if (isa<CXXTryStmt>(S)) {
481 HasAbnormalEdge = true;
484 if (std::find(B.succ_begin(), B.succ_end(), &cfg->getExit())
486 HasAbnormalEdge = true;
494 return NeverFallThrough;
495 return NeverFallThroughOrReturn;
497 if (HasAbnormalEdge || HasFakeEdge || HasLiveReturn)
498 return MaybeFallThrough;
499 // This says AlwaysFallThrough for calls to functions that are not marked
500 // noreturn, that don't return. If people would like this warning to be more
501 // accurate, such functions should be marked as noreturn.
502 return AlwaysFallThrough;
507 struct CheckFallThroughDiagnostics {
508 unsigned diag_MaybeFallThrough_HasNoReturn;
509 unsigned diag_MaybeFallThrough_ReturnsNonVoid;
510 unsigned diag_AlwaysFallThrough_HasNoReturn;
511 unsigned diag_AlwaysFallThrough_ReturnsNonVoid;
512 unsigned diag_NeverFallThroughOrReturn;
513 enum { Function, Block, Lambda, Coroutine } funMode;
514 SourceLocation FuncLoc;
516 static CheckFallThroughDiagnostics MakeForFunction(const Decl *Func) {
517 CheckFallThroughDiagnostics D;
518 D.FuncLoc = Func->getLocation();
519 D.diag_MaybeFallThrough_HasNoReturn =
520 diag::warn_falloff_noreturn_function;
521 D.diag_MaybeFallThrough_ReturnsNonVoid =
522 diag::warn_maybe_falloff_nonvoid_function;
523 D.diag_AlwaysFallThrough_HasNoReturn =
524 diag::warn_falloff_noreturn_function;
525 D.diag_AlwaysFallThrough_ReturnsNonVoid =
526 diag::warn_falloff_nonvoid_function;
528 // Don't suggest that virtual functions be marked "noreturn", since they
529 // might be overridden by non-noreturn functions.
530 bool isVirtualMethod = false;
531 if (const CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(Func))
532 isVirtualMethod = Method->isVirtual();
534 // Don't suggest that template instantiations be marked "noreturn"
535 bool isTemplateInstantiation = false;
536 if (const FunctionDecl *Function = dyn_cast<FunctionDecl>(Func))
537 isTemplateInstantiation = Function->isTemplateInstantiation();
539 if (!isVirtualMethod && !isTemplateInstantiation)
540 D.diag_NeverFallThroughOrReturn =
541 diag::warn_suggest_noreturn_function;
543 D.diag_NeverFallThroughOrReturn = 0;
545 D.funMode = Function;
549 static CheckFallThroughDiagnostics MakeForCoroutine(const Decl *Func) {
550 CheckFallThroughDiagnostics D;
551 D.FuncLoc = Func->getLocation();
552 D.diag_MaybeFallThrough_HasNoReturn = 0;
553 D.diag_MaybeFallThrough_ReturnsNonVoid =
554 diag::warn_maybe_falloff_nonvoid_coroutine;
555 D.diag_AlwaysFallThrough_HasNoReturn = 0;
556 D.diag_AlwaysFallThrough_ReturnsNonVoid =
557 diag::warn_falloff_nonvoid_coroutine;
558 D.funMode = Coroutine;
562 static CheckFallThroughDiagnostics MakeForBlock() {
563 CheckFallThroughDiagnostics D;
564 D.diag_MaybeFallThrough_HasNoReturn =
565 diag::err_noreturn_block_has_return_expr;
566 D.diag_MaybeFallThrough_ReturnsNonVoid =
567 diag::err_maybe_falloff_nonvoid_block;
568 D.diag_AlwaysFallThrough_HasNoReturn =
569 diag::err_noreturn_block_has_return_expr;
570 D.diag_AlwaysFallThrough_ReturnsNonVoid =
571 diag::err_falloff_nonvoid_block;
572 D.diag_NeverFallThroughOrReturn = 0;
577 static CheckFallThroughDiagnostics MakeForLambda() {
578 CheckFallThroughDiagnostics D;
579 D.diag_MaybeFallThrough_HasNoReturn =
580 diag::err_noreturn_lambda_has_return_expr;
581 D.diag_MaybeFallThrough_ReturnsNonVoid =
582 diag::warn_maybe_falloff_nonvoid_lambda;
583 D.diag_AlwaysFallThrough_HasNoReturn =
584 diag::err_noreturn_lambda_has_return_expr;
585 D.diag_AlwaysFallThrough_ReturnsNonVoid =
586 diag::warn_falloff_nonvoid_lambda;
587 D.diag_NeverFallThroughOrReturn = 0;
592 bool checkDiagnostics(DiagnosticsEngine &D, bool ReturnsVoid,
593 bool HasNoReturn) const {
594 if (funMode == Function) {
595 return (ReturnsVoid ||
596 D.isIgnored(diag::warn_maybe_falloff_nonvoid_function,
599 D.isIgnored(diag::warn_noreturn_function_has_return_expr,
602 D.isIgnored(diag::warn_suggest_noreturn_block, FuncLoc));
604 if (funMode == Coroutine) {
605 return (ReturnsVoid ||
606 D.isIgnored(diag::warn_maybe_falloff_nonvoid_function, FuncLoc) ||
607 D.isIgnored(diag::warn_maybe_falloff_nonvoid_coroutine,
611 // For blocks / lambdas.
612 return ReturnsVoid && !HasNoReturn;
616 } // anonymous namespace
618 /// CheckFallThroughForBody - Check that we don't fall off the end of a
619 /// function that should return a value. Check that we don't fall off the end
620 /// of a noreturn function. We assume that functions and blocks not marked
621 /// noreturn will return.
622 static void CheckFallThroughForBody(Sema &S, const Decl *D, const Stmt *Body,
624 const CheckFallThroughDiagnostics &CD,
625 AnalysisDeclContext &AC,
626 sema::FunctionScopeInfo *FSI) {
628 bool ReturnsVoid = false;
629 bool HasNoReturn = false;
630 bool IsCoroutine = FSI->isCoroutine();
632 if (const auto *FD = dyn_cast<FunctionDecl>(D)) {
633 if (const auto *CBody = dyn_cast<CoroutineBodyStmt>(Body))
634 ReturnsVoid = CBody->getFallthroughHandler() != nullptr;
636 ReturnsVoid = FD->getReturnType()->isVoidType();
637 HasNoReturn = FD->isNoReturn();
639 else if (const auto *MD = dyn_cast<ObjCMethodDecl>(D)) {
640 ReturnsVoid = MD->getReturnType()->isVoidType();
641 HasNoReturn = MD->hasAttr<NoReturnAttr>();
643 else if (isa<BlockDecl>(D)) {
644 if (const FunctionType *FT =
645 BlockType->getPointeeType()->getAs<FunctionType>()) {
646 if (FT->getReturnType()->isVoidType())
648 if (FT->getNoReturnAttr())
653 DiagnosticsEngine &Diags = S.getDiagnostics();
655 // Short circuit for compilation speed.
656 if (CD.checkDiagnostics(Diags, ReturnsVoid, HasNoReturn))
658 SourceLocation LBrace = Body->getBeginLoc(), RBrace = Body->getEndLoc();
659 auto EmitDiag = [&](SourceLocation Loc, unsigned DiagID) {
661 S.Diag(Loc, DiagID) << FSI->CoroutinePromise->getType();
666 // cpu_dispatch functions permit empty function bodies for ICC compatibility.
667 if (D->getAsFunction() && D->getAsFunction()->isCPUDispatchMultiVersion())
670 // Either in a function body compound statement, or a function-try-block.
671 switch (CheckFallThrough(AC)) {
672 case UnknownFallThrough:
675 case MaybeFallThrough:
677 EmitDiag(RBrace, CD.diag_MaybeFallThrough_HasNoReturn);
678 else if (!ReturnsVoid)
679 EmitDiag(RBrace, CD.diag_MaybeFallThrough_ReturnsNonVoid);
681 case AlwaysFallThrough:
683 EmitDiag(RBrace, CD.diag_AlwaysFallThrough_HasNoReturn);
684 else if (!ReturnsVoid)
685 EmitDiag(RBrace, CD.diag_AlwaysFallThrough_ReturnsNonVoid);
687 case NeverFallThroughOrReturn:
688 if (ReturnsVoid && !HasNoReturn && CD.diag_NeverFallThroughOrReturn) {
689 if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
690 S.Diag(LBrace, CD.diag_NeverFallThroughOrReturn) << 0 << FD;
691 } else if (const ObjCMethodDecl *MD = dyn_cast<ObjCMethodDecl>(D)) {
692 S.Diag(LBrace, CD.diag_NeverFallThroughOrReturn) << 1 << MD;
694 S.Diag(LBrace, CD.diag_NeverFallThroughOrReturn);
698 case NeverFallThrough:
703 //===----------------------------------------------------------------------===//
705 //===----------------------------------------------------------------------===//
708 /// ContainsReference - A visitor class to search for references to
709 /// a particular declaration (the needle) within any evaluated component of an
710 /// expression (recursively).
711 class ContainsReference : public ConstEvaluatedExprVisitor<ContainsReference> {
713 const DeclRefExpr *Needle;
716 typedef ConstEvaluatedExprVisitor<ContainsReference> Inherited;
718 ContainsReference(ASTContext &Context, const DeclRefExpr *Needle)
719 : Inherited(Context), FoundReference(false), Needle(Needle) {}
721 void VisitExpr(const Expr *E) {
722 // Stop evaluating if we already have a reference.
726 Inherited::VisitExpr(E);
729 void VisitDeclRefExpr(const DeclRefExpr *E) {
731 FoundReference = true;
733 Inherited::VisitDeclRefExpr(E);
736 bool doesContainReference() const { return FoundReference; }
738 } // anonymous namespace
740 static bool SuggestInitializationFixit(Sema &S, const VarDecl *VD) {
741 QualType VariableTy = VD->getType().getCanonicalType();
742 if (VariableTy->isBlockPointerType() &&
743 !VD->hasAttr<BlocksAttr>()) {
744 S.Diag(VD->getLocation(), diag::note_block_var_fixit_add_initialization)
746 << FixItHint::CreateInsertion(VD->getLocation(), "__block ");
750 // Don't issue a fixit if there is already an initializer.
754 // Don't suggest a fixit inside macros.
755 if (VD->getEndLoc().isMacroID())
758 SourceLocation Loc = S.getLocForEndOfToken(VD->getEndLoc());
760 // Suggest possible initialization (if any).
761 std::string Init = S.getFixItZeroInitializerForType(VariableTy, Loc);
765 S.Diag(Loc, diag::note_var_fixit_add_initialization) << VD->getDeclName()
766 << FixItHint::CreateInsertion(Loc, Init);
770 /// Create a fixit to remove an if-like statement, on the assumption that its
771 /// condition is CondVal.
772 static void CreateIfFixit(Sema &S, const Stmt *If, const Stmt *Then,
773 const Stmt *Else, bool CondVal,
774 FixItHint &Fixit1, FixItHint &Fixit2) {
776 // If condition is always true, remove all but the 'then'.
777 Fixit1 = FixItHint::CreateRemoval(
778 CharSourceRange::getCharRange(If->getBeginLoc(), Then->getBeginLoc()));
780 SourceLocation ElseKwLoc = S.getLocForEndOfToken(Then->getEndLoc());
782 FixItHint::CreateRemoval(SourceRange(ElseKwLoc, Else->getEndLoc()));
785 // If condition is always false, remove all but the 'else'.
787 Fixit1 = FixItHint::CreateRemoval(CharSourceRange::getCharRange(
788 If->getBeginLoc(), Else->getBeginLoc()));
790 Fixit1 = FixItHint::CreateRemoval(If->getSourceRange());
794 /// DiagUninitUse -- Helper function to produce a diagnostic for an
795 /// uninitialized use of a variable.
796 static void DiagUninitUse(Sema &S, const VarDecl *VD, const UninitUse &Use,
797 bool IsCapturedByBlock) {
798 bool Diagnosed = false;
800 switch (Use.getKind()) {
801 case UninitUse::Always:
802 S.Diag(Use.getUser()->getBeginLoc(), diag::warn_uninit_var)
803 << VD->getDeclName() << IsCapturedByBlock
804 << Use.getUser()->getSourceRange();
807 case UninitUse::AfterDecl:
808 case UninitUse::AfterCall:
809 S.Diag(VD->getLocation(), diag::warn_sometimes_uninit_var)
810 << VD->getDeclName() << IsCapturedByBlock
811 << (Use.getKind() == UninitUse::AfterDecl ? 4 : 5)
812 << const_cast<DeclContext*>(VD->getLexicalDeclContext())
813 << VD->getSourceRange();
814 S.Diag(Use.getUser()->getBeginLoc(), diag::note_uninit_var_use)
815 << IsCapturedByBlock << Use.getUser()->getSourceRange();
818 case UninitUse::Maybe:
819 case UninitUse::Sometimes:
820 // Carry on to report sometimes-uninitialized branches, if possible,
821 // or a 'may be used uninitialized' diagnostic otherwise.
825 // Diagnose each branch which leads to a sometimes-uninitialized use.
826 for (UninitUse::branch_iterator I = Use.branch_begin(), E = Use.branch_end();
828 assert(Use.getKind() == UninitUse::Sometimes);
830 const Expr *User = Use.getUser();
831 const Stmt *Term = I->Terminator;
833 // Information used when building the diagnostic.
838 // FixIts to suppress the diagnostic by removing the dead condition.
839 // For all binary terminators, branch 0 is taken if the condition is true,
840 // and branch 1 is taken if the condition is false.
841 int RemoveDiagKind = -1;
842 const char *FixitStr =
843 S.getLangOpts().CPlusPlus ? (I->Output ? "true" : "false")
844 : (I->Output ? "1" : "0");
845 FixItHint Fixit1, Fixit2;
847 switch (Term ? Term->getStmtClass() : Stmt::DeclStmtClass) {
849 // Don't know how to report this. Just fall back to 'may be used
850 // uninitialized'. FIXME: Can this happen?
853 // "condition is true / condition is false".
854 case Stmt::IfStmtClass: {
855 const IfStmt *IS = cast<IfStmt>(Term);
858 Range = IS->getCond()->getSourceRange();
860 CreateIfFixit(S, IS, IS->getThen(), IS->getElse(),
861 I->Output, Fixit1, Fixit2);
864 case Stmt::ConditionalOperatorClass: {
865 const ConditionalOperator *CO = cast<ConditionalOperator>(Term);
868 Range = CO->getCond()->getSourceRange();
870 CreateIfFixit(S, CO, CO->getTrueExpr(), CO->getFalseExpr(),
871 I->Output, Fixit1, Fixit2);
874 case Stmt::BinaryOperatorClass: {
875 const BinaryOperator *BO = cast<BinaryOperator>(Term);
876 if (!BO->isLogicalOp())
879 Str = BO->getOpcodeStr();
880 Range = BO->getLHS()->getSourceRange();
882 if ((BO->getOpcode() == BO_LAnd && I->Output) ||
883 (BO->getOpcode() == BO_LOr && !I->Output))
884 // true && y -> y, false || y -> y.
885 Fixit1 = FixItHint::CreateRemoval(
886 SourceRange(BO->getBeginLoc(), BO->getOperatorLoc()));
888 // false && y -> false, true || y -> true.
889 Fixit1 = FixItHint::CreateReplacement(BO->getSourceRange(), FixitStr);
893 // "loop is entered / loop is exited".
894 case Stmt::WhileStmtClass:
897 Range = cast<WhileStmt>(Term)->getCond()->getSourceRange();
899 Fixit1 = FixItHint::CreateReplacement(Range, FixitStr);
901 case Stmt::ForStmtClass:
904 Range = cast<ForStmt>(Term)->getCond()->getSourceRange();
907 Fixit1 = FixItHint::CreateRemoval(Range);
909 Fixit1 = FixItHint::CreateReplacement(Range, FixitStr);
911 case Stmt::CXXForRangeStmtClass:
912 if (I->Output == 1) {
913 // The use occurs if a range-based for loop's body never executes.
914 // That may be impossible, and there's no syntactic fix for this,
915 // so treat it as a 'may be uninitialized' case.
920 Range = cast<CXXForRangeStmt>(Term)->getRangeInit()->getSourceRange();
923 // "condition is true / loop is exited".
924 case Stmt::DoStmtClass:
927 Range = cast<DoStmt>(Term)->getCond()->getSourceRange();
929 Fixit1 = FixItHint::CreateReplacement(Range, FixitStr);
932 // "switch case is taken".
933 case Stmt::CaseStmtClass:
936 Range = cast<CaseStmt>(Term)->getLHS()->getSourceRange();
938 case Stmt::DefaultStmtClass:
941 Range = cast<DefaultStmt>(Term)->getDefaultLoc();
945 S.Diag(Range.getBegin(), diag::warn_sometimes_uninit_var)
946 << VD->getDeclName() << IsCapturedByBlock << DiagKind
947 << Str << I->Output << Range;
948 S.Diag(User->getBeginLoc(), diag::note_uninit_var_use)
949 << IsCapturedByBlock << User->getSourceRange();
950 if (RemoveDiagKind != -1)
951 S.Diag(Fixit1.RemoveRange.getBegin(), diag::note_uninit_fixit_remove_cond)
952 << RemoveDiagKind << Str << I->Output << Fixit1 << Fixit2;
958 S.Diag(Use.getUser()->getBeginLoc(), diag::warn_maybe_uninit_var)
959 << VD->getDeclName() << IsCapturedByBlock
960 << Use.getUser()->getSourceRange();
963 /// DiagnoseUninitializedUse -- Helper function for diagnosing uses of an
964 /// uninitialized variable. This manages the different forms of diagnostic
965 /// emitted for particular types of uses. Returns true if the use was diagnosed
966 /// as a warning. If a particular use is one we omit warnings for, returns
968 static bool DiagnoseUninitializedUse(Sema &S, const VarDecl *VD,
969 const UninitUse &Use,
970 bool alwaysReportSelfInit = false) {
971 if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(Use.getUser())) {
972 // Inspect the initializer of the variable declaration which is
973 // being referenced prior to its initialization. We emit
974 // specialized diagnostics for self-initialization, and we
975 // specifically avoid warning about self references which take the
980 // This is used to indicate to GCC that 'x' is intentionally left
981 // uninitialized. Proven code paths which access 'x' in
982 // an uninitialized state after this will still warn.
983 if (const Expr *Initializer = VD->getInit()) {
984 if (!alwaysReportSelfInit && DRE == Initializer->IgnoreParenImpCasts())
987 ContainsReference CR(S.Context, DRE);
988 CR.Visit(Initializer);
989 if (CR.doesContainReference()) {
990 S.Diag(DRE->getBeginLoc(), diag::warn_uninit_self_reference_in_init)
991 << VD->getDeclName() << VD->getLocation() << DRE->getSourceRange();
996 DiagUninitUse(S, VD, Use, false);
998 const BlockExpr *BE = cast<BlockExpr>(Use.getUser());
999 if (VD->getType()->isBlockPointerType() && !VD->hasAttr<BlocksAttr>())
1000 S.Diag(BE->getBeginLoc(),
1001 diag::warn_uninit_byref_blockvar_captured_by_block)
1002 << VD->getDeclName()
1003 << VD->getType().getQualifiers().hasObjCLifetime();
1005 DiagUninitUse(S, VD, Use, true);
1008 // Report where the variable was declared when the use wasn't within
1009 // the initializer of that declaration & we didn't already suggest
1010 // an initialization fixit.
1011 if (!SuggestInitializationFixit(S, VD))
1012 S.Diag(VD->getBeginLoc(), diag::note_var_declared_here)
1013 << VD->getDeclName();
1019 class FallthroughMapper : public RecursiveASTVisitor<FallthroughMapper> {
1021 FallthroughMapper(Sema &S)
1022 : FoundSwitchStatements(false),
1026 bool foundSwitchStatements() const { return FoundSwitchStatements; }
1028 void markFallthroughVisited(const AttributedStmt *Stmt) {
1029 bool Found = FallthroughStmts.erase(Stmt);
1034 typedef llvm::SmallPtrSet<const AttributedStmt*, 8> AttrStmts;
1036 const AttrStmts &getFallthroughStmts() const {
1037 return FallthroughStmts;
1040 void fillReachableBlocks(CFG *Cfg) {
1041 assert(ReachableBlocks.empty() && "ReachableBlocks already filled");
1042 std::deque<const CFGBlock *> BlockQueue;
1044 ReachableBlocks.insert(&Cfg->getEntry());
1045 BlockQueue.push_back(&Cfg->getEntry());
1046 // Mark all case blocks reachable to avoid problems with switching on
1047 // constants, covered enums, etc.
1048 // These blocks can contain fall-through annotations, and we don't want to
1049 // issue a warn_fallthrough_attr_unreachable for them.
1050 for (const auto *B : *Cfg) {
1051 const Stmt *L = B->getLabel();
1052 if (L && isa<SwitchCase>(L) && ReachableBlocks.insert(B).second)
1053 BlockQueue.push_back(B);
1056 while (!BlockQueue.empty()) {
1057 const CFGBlock *P = BlockQueue.front();
1058 BlockQueue.pop_front();
1059 for (CFGBlock::const_succ_iterator I = P->succ_begin(),
1062 if (*I && ReachableBlocks.insert(*I).second)
1063 BlockQueue.push_back(*I);
1068 bool checkFallThroughIntoBlock(const CFGBlock &B, int &AnnotatedCnt,
1069 bool IsTemplateInstantiation) {
1070 assert(!ReachableBlocks.empty() && "ReachableBlocks empty");
1072 int UnannotatedCnt = 0;
1075 std::deque<const CFGBlock*> BlockQueue(B.pred_begin(), B.pred_end());
1076 while (!BlockQueue.empty()) {
1077 const CFGBlock *P = BlockQueue.front();
1078 BlockQueue.pop_front();
1081 const Stmt *Term = P->getTerminatorStmt();
1082 if (Term && isa<SwitchStmt>(Term))
1083 continue; // Switch statement, good.
1085 const SwitchCase *SW = dyn_cast_or_null<SwitchCase>(P->getLabel());
1086 if (SW && SW->getSubStmt() == B.getLabel() && P->begin() == P->end())
1087 continue; // Previous case label has no statements, good.
1089 const LabelStmt *L = dyn_cast_or_null<LabelStmt>(P->getLabel());
1090 if (L && L->getSubStmt() == B.getLabel() && P->begin() == P->end())
1091 continue; // Case label is preceded with a normal label, good.
1093 if (!ReachableBlocks.count(P)) {
1094 for (CFGBlock::const_reverse_iterator ElemIt = P->rbegin(),
1095 ElemEnd = P->rend();
1096 ElemIt != ElemEnd; ++ElemIt) {
1097 if (Optional<CFGStmt> CS = ElemIt->getAs<CFGStmt>()) {
1098 if (const AttributedStmt *AS = asFallThroughAttr(CS->getStmt())) {
1099 // Don't issue a warning for an unreachable fallthrough
1100 // attribute in template instantiations as it may not be
1101 // unreachable in all instantiations of the template.
1102 if (!IsTemplateInstantiation)
1103 S.Diag(AS->getBeginLoc(),
1104 diag::warn_fallthrough_attr_unreachable);
1105 markFallthroughVisited(AS);
1109 // Don't care about other unreachable statements.
1112 // If there are no unreachable statements, this may be a special
1115 // A a; // A has a destructor.
1118 // // <<<< This place is represented by a 'hanging' CFG block.
1123 const Stmt *LastStmt = getLastStmt(*P);
1124 if (const AttributedStmt *AS = asFallThroughAttr(LastStmt)) {
1125 markFallthroughVisited(AS);
1127 continue; // Fallthrough annotation, good.
1130 if (!LastStmt) { // This block contains no executable statements.
1131 // Traverse its predecessors.
1132 std::copy(P->pred_begin(), P->pred_end(),
1133 std::back_inserter(BlockQueue));
1139 return !!UnannotatedCnt;
1142 // RecursiveASTVisitor setup.
1143 bool shouldWalkTypesOfTypeLocs() const { return false; }
1145 bool VisitAttributedStmt(AttributedStmt *S) {
1146 if (asFallThroughAttr(S))
1147 FallthroughStmts.insert(S);
1151 bool VisitSwitchStmt(SwitchStmt *S) {
1152 FoundSwitchStatements = true;
1156 // We don't want to traverse local type declarations. We analyze their
1157 // methods separately.
1158 bool TraverseDecl(Decl *D) { return true; }
1160 // We analyze lambda bodies separately. Skip them here.
1161 bool TraverseLambdaExpr(LambdaExpr *LE) {
1162 // Traverse the captures, but not the body.
1163 for (const auto &C : zip(LE->captures(), LE->capture_inits()))
1164 TraverseLambdaCapture(LE, &std::get<0>(C), std::get<1>(C));
1170 static const AttributedStmt *asFallThroughAttr(const Stmt *S) {
1171 if (const AttributedStmt *AS = dyn_cast_or_null<AttributedStmt>(S)) {
1172 if (hasSpecificAttr<FallThroughAttr>(AS->getAttrs()))
1178 static const Stmt *getLastStmt(const CFGBlock &B) {
1179 if (const Stmt *Term = B.getTerminatorStmt())
1181 for (CFGBlock::const_reverse_iterator ElemIt = B.rbegin(),
1183 ElemIt != ElemEnd; ++ElemIt) {
1184 if (Optional<CFGStmt> CS = ElemIt->getAs<CFGStmt>())
1185 return CS->getStmt();
1187 // Workaround to detect a statement thrown out by CFGBuilder:
1188 // case X: {} case Y:
1189 // case X: ; case Y:
1190 if (const SwitchCase *SW = dyn_cast_or_null<SwitchCase>(B.getLabel()))
1191 if (!isa<SwitchCase>(SW->getSubStmt()))
1192 return SW->getSubStmt();
1197 bool FoundSwitchStatements;
1198 AttrStmts FallthroughStmts;
1200 llvm::SmallPtrSet<const CFGBlock *, 16> ReachableBlocks;
1202 } // anonymous namespace
1204 static StringRef getFallthroughAttrSpelling(Preprocessor &PP,
1205 SourceLocation Loc) {
1206 TokenValue FallthroughTokens[] = {
1207 tok::l_square, tok::l_square,
1208 PP.getIdentifierInfo("fallthrough"),
1209 tok::r_square, tok::r_square
1212 TokenValue ClangFallthroughTokens[] = {
1213 tok::l_square, tok::l_square, PP.getIdentifierInfo("clang"),
1214 tok::coloncolon, PP.getIdentifierInfo("fallthrough"),
1215 tok::r_square, tok::r_square
1218 bool PreferClangAttr = !PP.getLangOpts().CPlusPlus17;
1220 StringRef MacroName;
1221 if (PreferClangAttr)
1222 MacroName = PP.getLastMacroWithSpelling(Loc, ClangFallthroughTokens);
1223 if (MacroName.empty())
1224 MacroName = PP.getLastMacroWithSpelling(Loc, FallthroughTokens);
1225 if (MacroName.empty() && !PreferClangAttr)
1226 MacroName = PP.getLastMacroWithSpelling(Loc, ClangFallthroughTokens);
1227 if (MacroName.empty())
1228 MacroName = PreferClangAttr ? "[[clang::fallthrough]]" : "[[fallthrough]]";
1232 static void DiagnoseSwitchLabelsFallthrough(Sema &S, AnalysisDeclContext &AC,
1234 // Only perform this analysis when using [[]] attributes. There is no good
1235 // workflow for this warning when not using C++11. There is no good way to
1236 // silence the warning (no attribute is available) unless we are using
1237 // [[]] attributes. One could use pragmas to silence the warning, but as a
1238 // general solution that is gross and not in the spirit of this warning.
1240 // NOTE: This an intermediate solution. There are on-going discussions on
1241 // how to properly support this warning outside of C++11 with an annotation.
1242 if (!AC.getASTContext().getLangOpts().DoubleSquareBracketAttributes)
1245 FallthroughMapper FM(S);
1246 FM.TraverseStmt(AC.getBody());
1248 if (!FM.foundSwitchStatements())
1251 if (PerFunction && FM.getFallthroughStmts().empty())
1254 CFG *Cfg = AC.getCFG();
1259 FM.fillReachableBlocks(Cfg);
1261 for (const CFGBlock *B : llvm::reverse(*Cfg)) {
1262 const Stmt *Label = B->getLabel();
1264 if (!Label || !isa<SwitchCase>(Label))
1269 bool IsTemplateInstantiation = false;
1270 if (const FunctionDecl *Function = dyn_cast<FunctionDecl>(AC.getDecl()))
1271 IsTemplateInstantiation = Function->isTemplateInstantiation();
1272 if (!FM.checkFallThroughIntoBlock(*B, AnnotatedCnt,
1273 IsTemplateInstantiation))
1276 S.Diag(Label->getBeginLoc(),
1277 PerFunction ? diag::warn_unannotated_fallthrough_per_function
1278 : diag::warn_unannotated_fallthrough);
1280 if (!AnnotatedCnt) {
1281 SourceLocation L = Label->getBeginLoc();
1284 if (S.getLangOpts().CPlusPlus11) {
1285 const Stmt *Term = B->getTerminatorStmt();
1286 // Skip empty cases.
1287 while (B->empty() && !Term && B->succ_size() == 1) {
1288 B = *B->succ_begin();
1289 Term = B->getTerminatorStmt();
1291 if (!(B->empty() && Term && isa<BreakStmt>(Term))) {
1292 Preprocessor &PP = S.getPreprocessor();
1293 StringRef AnnotationSpelling = getFallthroughAttrSpelling(PP, L);
1294 SmallString<64> TextToInsert(AnnotationSpelling);
1295 TextToInsert += "; ";
1296 S.Diag(L, diag::note_insert_fallthrough_fixit) <<
1297 AnnotationSpelling <<
1298 FixItHint::CreateInsertion(L, TextToInsert);
1301 S.Diag(L, diag::note_insert_break_fixit) <<
1302 FixItHint::CreateInsertion(L, "break; ");
1306 for (const auto *F : FM.getFallthroughStmts())
1307 S.Diag(F->getBeginLoc(), diag::err_fallthrough_attr_invalid_placement);
1310 static bool isInLoop(const ASTContext &Ctx, const ParentMap &PM,
1315 switch (S->getStmtClass()) {
1316 case Stmt::ForStmtClass:
1317 case Stmt::WhileStmtClass:
1318 case Stmt::CXXForRangeStmtClass:
1319 case Stmt::ObjCForCollectionStmtClass:
1321 case Stmt::DoStmtClass: {
1322 Expr::EvalResult Result;
1323 if (!cast<DoStmt>(S)->getCond()->EvaluateAsInt(Result, Ctx))
1325 return Result.Val.getInt().getBoolValue();
1330 } while ((S = PM.getParent(S)));
1335 static void diagnoseRepeatedUseOfWeak(Sema &S,
1336 const sema::FunctionScopeInfo *CurFn,
1338 const ParentMap &PM) {
1339 typedef sema::FunctionScopeInfo::WeakObjectProfileTy WeakObjectProfileTy;
1340 typedef sema::FunctionScopeInfo::WeakObjectUseMap WeakObjectUseMap;
1341 typedef sema::FunctionScopeInfo::WeakUseVector WeakUseVector;
1342 typedef std::pair<const Stmt *, WeakObjectUseMap::const_iterator>
1345 ASTContext &Ctx = S.getASTContext();
1347 const WeakObjectUseMap &WeakMap = CurFn->getWeakObjectUses();
1349 // Extract all weak objects that are referenced more than once.
1350 SmallVector<StmtUsesPair, 8> UsesByStmt;
1351 for (WeakObjectUseMap::const_iterator I = WeakMap.begin(), E = WeakMap.end();
1353 const WeakUseVector &Uses = I->second;
1355 // Find the first read of the weak object.
1356 WeakUseVector::const_iterator UI = Uses.begin(), UE = Uses.end();
1357 for ( ; UI != UE; ++UI) {
1362 // If there were only writes to this object, don't warn.
1366 // If there was only one read, followed by any number of writes, and the
1367 // read is not within a loop, don't warn. Additionally, don't warn in a
1368 // loop if the base object is a local variable -- local variables are often
1369 // changed in loops.
1370 if (UI == Uses.begin()) {
1371 WeakUseVector::const_iterator UI2 = UI;
1372 for (++UI2; UI2 != UE; ++UI2)
1373 if (UI2->isUnsafe())
1377 if (!isInLoop(Ctx, PM, UI->getUseExpr()))
1380 const WeakObjectProfileTy &Profile = I->first;
1381 if (!Profile.isExactProfile())
1384 const NamedDecl *Base = Profile.getBase();
1386 Base = Profile.getProperty();
1387 assert(Base && "A profile always has a base or property.");
1389 if (const VarDecl *BaseVar = dyn_cast<VarDecl>(Base))
1390 if (BaseVar->hasLocalStorage() && !isa<ParmVarDecl>(Base))
1395 UsesByStmt.push_back(StmtUsesPair(UI->getUseExpr(), I));
1398 if (UsesByStmt.empty())
1401 // Sort by first use so that we emit the warnings in a deterministic order.
1402 SourceManager &SM = S.getSourceManager();
1403 llvm::sort(UsesByStmt,
1404 [&SM](const StmtUsesPair &LHS, const StmtUsesPair &RHS) {
1405 return SM.isBeforeInTranslationUnit(LHS.first->getBeginLoc(),
1406 RHS.first->getBeginLoc());
1409 // Classify the current code body for better warning text.
1410 // This enum should stay in sync with the cases in
1411 // warn_arc_repeated_use_of_weak and warn_arc_possible_repeated_use_of_weak.
1412 // FIXME: Should we use a common classification enum and the same set of
1413 // possibilities all throughout Sema?
1421 if (isa<sema::BlockScopeInfo>(CurFn))
1422 FunctionKind = Block;
1423 else if (isa<sema::LambdaScopeInfo>(CurFn))
1424 FunctionKind = Lambda;
1425 else if (isa<ObjCMethodDecl>(D))
1426 FunctionKind = Method;
1428 FunctionKind = Function;
1430 // Iterate through the sorted problems and emit warnings for each.
1431 for (const auto &P : UsesByStmt) {
1432 const Stmt *FirstRead = P.first;
1433 const WeakObjectProfileTy &Key = P.second->first;
1434 const WeakUseVector &Uses = P.second->second;
1436 // For complicated expressions like 'a.b.c' and 'x.b.c', WeakObjectProfileTy
1437 // may not contain enough information to determine that these are different
1438 // properties. We can only be 100% sure of a repeated use in certain cases,
1439 // and we adjust the diagnostic kind accordingly so that the less certain
1440 // case can be turned off if it is too noisy.
1442 if (Key.isExactProfile())
1443 DiagKind = diag::warn_arc_repeated_use_of_weak;
1445 DiagKind = diag::warn_arc_possible_repeated_use_of_weak;
1447 // Classify the weak object being accessed for better warning text.
1448 // This enum should stay in sync with the cases in
1449 // warn_arc_repeated_use_of_weak and warn_arc_possible_repeated_use_of_weak.
1457 const NamedDecl *KeyProp = Key.getProperty();
1458 if (isa<VarDecl>(KeyProp))
1459 ObjectKind = Variable;
1460 else if (isa<ObjCPropertyDecl>(KeyProp))
1461 ObjectKind = Property;
1462 else if (isa<ObjCMethodDecl>(KeyProp))
1463 ObjectKind = ImplicitProperty;
1464 else if (isa<ObjCIvarDecl>(KeyProp))
1467 llvm_unreachable("Unexpected weak object kind!");
1469 // Do not warn about IBOutlet weak property receivers being set to null
1470 // since they are typically only used from the main thread.
1471 if (const ObjCPropertyDecl *Prop = dyn_cast<ObjCPropertyDecl>(KeyProp))
1472 if (Prop->hasAttr<IBOutletAttr>())
1475 // Show the first time the object was read.
1476 S.Diag(FirstRead->getBeginLoc(), DiagKind)
1477 << int(ObjectKind) << KeyProp << int(FunctionKind)
1478 << FirstRead->getSourceRange();
1480 // Print all the other accesses as notes.
1481 for (const auto &Use : Uses) {
1482 if (Use.getUseExpr() == FirstRead)
1484 S.Diag(Use.getUseExpr()->getBeginLoc(),
1485 diag::note_arc_weak_also_accessed_here)
1486 << Use.getUseExpr()->getSourceRange();
1492 class UninitValsDiagReporter : public UninitVariablesHandler {
1494 typedef SmallVector<UninitUse, 2> UsesVec;
1495 typedef llvm::PointerIntPair<UsesVec *, 1, bool> MappedType;
1496 // Prefer using MapVector to DenseMap, so that iteration order will be
1497 // the same as insertion order. This is needed to obtain a deterministic
1498 // order of diagnostics when calling flushDiagnostics().
1499 typedef llvm::MapVector<const VarDecl *, MappedType> UsesMap;
1503 UninitValsDiagReporter(Sema &S) : S(S) {}
1504 ~UninitValsDiagReporter() override { flushDiagnostics(); }
1506 MappedType &getUses(const VarDecl *vd) {
1507 MappedType &V = uses[vd];
1508 if (!V.getPointer())
1509 V.setPointer(new UsesVec());
1513 void handleUseOfUninitVariable(const VarDecl *vd,
1514 const UninitUse &use) override {
1515 getUses(vd).getPointer()->push_back(use);
1518 void handleSelfInit(const VarDecl *vd) override {
1519 getUses(vd).setInt(true);
1522 void flushDiagnostics() {
1523 for (const auto &P : uses) {
1524 const VarDecl *vd = P.first;
1525 const MappedType &V = P.second;
1527 UsesVec *vec = V.getPointer();
1528 bool hasSelfInit = V.getInt();
1530 // Specially handle the case where we have uses of an uninitialized
1531 // variable, but the root cause is an idiomatic self-init. We want
1532 // to report the diagnostic at the self-init since that is the root cause.
1533 if (!vec->empty() && hasSelfInit && hasAlwaysUninitializedUse(vec))
1534 DiagnoseUninitializedUse(S, vd,
1535 UninitUse(vd->getInit()->IgnoreParenCasts(),
1536 /* isAlwaysUninit */ true),
1537 /* alwaysReportSelfInit */ true);
1539 // Sort the uses by their SourceLocations. While not strictly
1540 // guaranteed to produce them in line/column order, this will provide
1541 // a stable ordering.
1542 llvm::sort(vec->begin(), vec->end(),
1543 [](const UninitUse &a, const UninitUse &b) {
1544 // Prefer a more confident report over a less confident one.
1545 if (a.getKind() != b.getKind())
1546 return a.getKind() > b.getKind();
1547 return a.getUser()->getBeginLoc() < b.getUser()->getBeginLoc();
1550 for (const auto &U : *vec) {
1551 // If we have self-init, downgrade all uses to 'may be uninitialized'.
1552 UninitUse Use = hasSelfInit ? UninitUse(U.getUser(), false) : U;
1554 if (DiagnoseUninitializedUse(S, vd, Use))
1555 // Skip further diagnostics for this variable. We try to warn only
1556 // on the first point at which a variable is used uninitialized.
1561 // Release the uses vector.
1569 static bool hasAlwaysUninitializedUse(const UsesVec* vec) {
1570 return std::any_of(vec->begin(), vec->end(), [](const UninitUse &U) {
1571 return U.getKind() == UninitUse::Always ||
1572 U.getKind() == UninitUse::AfterCall ||
1573 U.getKind() == UninitUse::AfterDecl;
1577 } // anonymous namespace
1581 typedef SmallVector<PartialDiagnosticAt, 1> OptionalNotes;
1582 typedef std::pair<PartialDiagnosticAt, OptionalNotes> DelayedDiag;
1583 typedef std::list<DelayedDiag> DiagList;
1585 struct SortDiagBySourceLocation {
1587 SortDiagBySourceLocation(SourceManager &SM) : SM(SM) {}
1589 bool operator()(const DelayedDiag &left, const DelayedDiag &right) {
1590 // Although this call will be slow, this is only called when outputting
1591 // multiple warnings.
1592 return SM.isBeforeInTranslationUnit(left.first.first, right.first.first);
1595 } // anonymous namespace
1596 } // namespace clang
1598 //===----------------------------------------------------------------------===//
1600 //===----------------------------------------------------------------------===//
1602 namespace threadSafety {
1604 class ThreadSafetyReporter : public clang::threadSafety::ThreadSafetyHandler {
1607 SourceLocation FunLocation, FunEndLocation;
1609 const FunctionDecl *CurrentFunction;
1612 OptionalNotes getNotes() const {
1613 if (Verbose && CurrentFunction) {
1614 PartialDiagnosticAt FNote(CurrentFunction->getBody()->getBeginLoc(),
1615 S.PDiag(diag::note_thread_warning_in_fun)
1616 << CurrentFunction);
1617 return OptionalNotes(1, FNote);
1619 return OptionalNotes();
1622 OptionalNotes getNotes(const PartialDiagnosticAt &Note) const {
1623 OptionalNotes ONS(1, Note);
1624 if (Verbose && CurrentFunction) {
1625 PartialDiagnosticAt FNote(CurrentFunction->getBody()->getBeginLoc(),
1626 S.PDiag(diag::note_thread_warning_in_fun)
1627 << CurrentFunction);
1628 ONS.push_back(std::move(FNote));
1633 OptionalNotes getNotes(const PartialDiagnosticAt &Note1,
1634 const PartialDiagnosticAt &Note2) const {
1636 ONS.push_back(Note1);
1637 ONS.push_back(Note2);
1638 if (Verbose && CurrentFunction) {
1639 PartialDiagnosticAt FNote(CurrentFunction->getBody()->getBeginLoc(),
1640 S.PDiag(diag::note_thread_warning_in_fun)
1641 << CurrentFunction);
1642 ONS.push_back(std::move(FNote));
1647 OptionalNotes makeLockedHereNote(SourceLocation LocLocked, StringRef Kind) {
1648 return LocLocked.isValid()
1649 ? getNotes(PartialDiagnosticAt(
1650 LocLocked, S.PDiag(diag::note_locked_here) << Kind))
1655 ThreadSafetyReporter(Sema &S, SourceLocation FL, SourceLocation FEL)
1656 : S(S), FunLocation(FL), FunEndLocation(FEL),
1657 CurrentFunction(nullptr), Verbose(false) {}
1659 void setVerbose(bool b) { Verbose = b; }
1661 /// Emit all buffered diagnostics in order of sourcelocation.
1662 /// We need to output diagnostics produced while iterating through
1663 /// the lockset in deterministic order, so this function orders diagnostics
1664 /// and outputs them.
1665 void emitDiagnostics() {
1666 Warnings.sort(SortDiagBySourceLocation(S.getSourceManager()));
1667 for (const auto &Diag : Warnings) {
1668 S.Diag(Diag.first.first, Diag.first.second);
1669 for (const auto &Note : Diag.second)
1670 S.Diag(Note.first, Note.second);
1674 void handleInvalidLockExp(StringRef Kind, SourceLocation Loc) override {
1675 PartialDiagnosticAt Warning(Loc, S.PDiag(diag::warn_cannot_resolve_lock)
1677 Warnings.emplace_back(std::move(Warning), getNotes());
1680 void handleUnmatchedUnlock(StringRef Kind, Name LockName,
1681 SourceLocation Loc) override {
1682 if (Loc.isInvalid())
1684 PartialDiagnosticAt Warning(Loc, S.PDiag(diag::warn_unlock_but_no_lock)
1685 << Kind << LockName);
1686 Warnings.emplace_back(std::move(Warning), getNotes());
1689 void handleIncorrectUnlockKind(StringRef Kind, Name LockName,
1690 LockKind Expected, LockKind Received,
1691 SourceLocation LocLocked,
1692 SourceLocation LocUnlock) override {
1693 if (LocUnlock.isInvalid())
1694 LocUnlock = FunLocation;
1695 PartialDiagnosticAt Warning(
1696 LocUnlock, S.PDiag(diag::warn_unlock_kind_mismatch)
1697 << Kind << LockName << Received << Expected);
1698 Warnings.emplace_back(std::move(Warning),
1699 makeLockedHereNote(LocLocked, Kind));
1702 void handleDoubleLock(StringRef Kind, Name LockName, SourceLocation LocLocked,
1703 SourceLocation LocDoubleLock) override {
1704 if (LocDoubleLock.isInvalid())
1705 LocDoubleLock = FunLocation;
1706 PartialDiagnosticAt Warning(LocDoubleLock, S.PDiag(diag::warn_double_lock)
1707 << Kind << LockName);
1708 Warnings.emplace_back(std::move(Warning),
1709 makeLockedHereNote(LocLocked, Kind));
1712 void handleMutexHeldEndOfScope(StringRef Kind, Name LockName,
1713 SourceLocation LocLocked,
1714 SourceLocation LocEndOfScope,
1715 LockErrorKind LEK) override {
1716 unsigned DiagID = 0;
1718 case LEK_LockedSomePredecessors:
1719 DiagID = diag::warn_lock_some_predecessors;
1721 case LEK_LockedSomeLoopIterations:
1722 DiagID = diag::warn_expecting_lock_held_on_loop;
1724 case LEK_LockedAtEndOfFunction:
1725 DiagID = diag::warn_no_unlock;
1727 case LEK_NotLockedAtEndOfFunction:
1728 DiagID = diag::warn_expecting_locked;
1731 if (LocEndOfScope.isInvalid())
1732 LocEndOfScope = FunEndLocation;
1734 PartialDiagnosticAt Warning(LocEndOfScope, S.PDiag(DiagID) << Kind
1736 Warnings.emplace_back(std::move(Warning),
1737 makeLockedHereNote(LocLocked, Kind));
1740 void handleExclusiveAndShared(StringRef Kind, Name LockName,
1741 SourceLocation Loc1,
1742 SourceLocation Loc2) override {
1743 PartialDiagnosticAt Warning(Loc1,
1744 S.PDiag(diag::warn_lock_exclusive_and_shared)
1745 << Kind << LockName);
1746 PartialDiagnosticAt Note(Loc2, S.PDiag(diag::note_lock_exclusive_and_shared)
1747 << Kind << LockName);
1748 Warnings.emplace_back(std::move(Warning), getNotes(Note));
1751 void handleNoMutexHeld(StringRef Kind, const NamedDecl *D,
1752 ProtectedOperationKind POK, AccessKind AK,
1753 SourceLocation Loc) override {
1754 assert((POK == POK_VarAccess || POK == POK_VarDereference) &&
1755 "Only works for variables");
1756 unsigned DiagID = POK == POK_VarAccess?
1757 diag::warn_variable_requires_any_lock:
1758 diag::warn_var_deref_requires_any_lock;
1759 PartialDiagnosticAt Warning(Loc, S.PDiag(DiagID)
1760 << D << getLockKindFromAccessKind(AK));
1761 Warnings.emplace_back(std::move(Warning), getNotes());
1764 void handleMutexNotHeld(StringRef Kind, const NamedDecl *D,
1765 ProtectedOperationKind POK, Name LockName,
1766 LockKind LK, SourceLocation Loc,
1767 Name *PossibleMatch) override {
1768 unsigned DiagID = 0;
1769 if (PossibleMatch) {
1772 DiagID = diag::warn_variable_requires_lock_precise;
1774 case POK_VarDereference:
1775 DiagID = diag::warn_var_deref_requires_lock_precise;
1777 case POK_FunctionCall:
1778 DiagID = diag::warn_fun_requires_lock_precise;
1781 DiagID = diag::warn_guarded_pass_by_reference;
1783 case POK_PtPassByRef:
1784 DiagID = diag::warn_pt_guarded_pass_by_reference;
1787 PartialDiagnosticAt Warning(Loc, S.PDiag(DiagID) << Kind
1790 PartialDiagnosticAt Note(Loc, S.PDiag(diag::note_found_mutex_near_match)
1792 if (Verbose && POK == POK_VarAccess) {
1793 PartialDiagnosticAt VNote(D->getLocation(),
1794 S.PDiag(diag::note_guarded_by_declared_here)
1795 << D->getNameAsString());
1796 Warnings.emplace_back(std::move(Warning), getNotes(Note, VNote));
1798 Warnings.emplace_back(std::move(Warning), getNotes(Note));
1802 DiagID = diag::warn_variable_requires_lock;
1804 case POK_VarDereference:
1805 DiagID = diag::warn_var_deref_requires_lock;
1807 case POK_FunctionCall:
1808 DiagID = diag::warn_fun_requires_lock;
1811 DiagID = diag::warn_guarded_pass_by_reference;
1813 case POK_PtPassByRef:
1814 DiagID = diag::warn_pt_guarded_pass_by_reference;
1817 PartialDiagnosticAt Warning(Loc, S.PDiag(DiagID) << Kind
1820 if (Verbose && POK == POK_VarAccess) {
1821 PartialDiagnosticAt Note(D->getLocation(),
1822 S.PDiag(diag::note_guarded_by_declared_here));
1823 Warnings.emplace_back(std::move(Warning), getNotes(Note));
1825 Warnings.emplace_back(std::move(Warning), getNotes());
1829 void handleNegativeNotHeld(StringRef Kind, Name LockName, Name Neg,
1830 SourceLocation Loc) override {
1831 PartialDiagnosticAt Warning(Loc,
1832 S.PDiag(diag::warn_acquire_requires_negative_cap)
1833 << Kind << LockName << Neg);
1834 Warnings.emplace_back(std::move(Warning), getNotes());
1837 void handleFunExcludesLock(StringRef Kind, Name FunName, Name LockName,
1838 SourceLocation Loc) override {
1839 PartialDiagnosticAt Warning(Loc, S.PDiag(diag::warn_fun_excludes_mutex)
1840 << Kind << FunName << LockName);
1841 Warnings.emplace_back(std::move(Warning), getNotes());
1844 void handleLockAcquiredBefore(StringRef Kind, Name L1Name, Name L2Name,
1845 SourceLocation Loc) override {
1846 PartialDiagnosticAt Warning(Loc,
1847 S.PDiag(diag::warn_acquired_before) << Kind << L1Name << L2Name);
1848 Warnings.emplace_back(std::move(Warning), getNotes());
1851 void handleBeforeAfterCycle(Name L1Name, SourceLocation Loc) override {
1852 PartialDiagnosticAt Warning(Loc,
1853 S.PDiag(diag::warn_acquired_before_after_cycle) << L1Name);
1854 Warnings.emplace_back(std::move(Warning), getNotes());
1857 void enterFunction(const FunctionDecl* FD) override {
1858 CurrentFunction = FD;
1861 void leaveFunction(const FunctionDecl* FD) override {
1862 CurrentFunction = nullptr;
1865 } // anonymous namespace
1866 } // namespace threadSafety
1867 } // namespace clang
1869 //===----------------------------------------------------------------------===//
1871 //===----------------------------------------------------------------------===//
1874 namespace consumed {
1876 class ConsumedWarningsHandler : public ConsumedWarningsHandlerBase {
1883 ConsumedWarningsHandler(Sema &S) : S(S) {}
1885 void emitDiagnostics() override {
1886 Warnings.sort(SortDiagBySourceLocation(S.getSourceManager()));
1887 for (const auto &Diag : Warnings) {
1888 S.Diag(Diag.first.first, Diag.first.second);
1889 for (const auto &Note : Diag.second)
1890 S.Diag(Note.first, Note.second);
1894 void warnLoopStateMismatch(SourceLocation Loc,
1895 StringRef VariableName) override {
1896 PartialDiagnosticAt Warning(Loc, S.PDiag(diag::warn_loop_state_mismatch) <<
1899 Warnings.emplace_back(std::move(Warning), OptionalNotes());
1902 void warnParamReturnTypestateMismatch(SourceLocation Loc,
1903 StringRef VariableName,
1904 StringRef ExpectedState,
1905 StringRef ObservedState) override {
1907 PartialDiagnosticAt Warning(Loc, S.PDiag(
1908 diag::warn_param_return_typestate_mismatch) << VariableName <<
1909 ExpectedState << ObservedState);
1911 Warnings.emplace_back(std::move(Warning), OptionalNotes());
1914 void warnParamTypestateMismatch(SourceLocation Loc, StringRef ExpectedState,
1915 StringRef ObservedState) override {
1917 PartialDiagnosticAt Warning(Loc, S.PDiag(
1918 diag::warn_param_typestate_mismatch) << ExpectedState << ObservedState);
1920 Warnings.emplace_back(std::move(Warning), OptionalNotes());
1923 void warnReturnTypestateForUnconsumableType(SourceLocation Loc,
1924 StringRef TypeName) override {
1925 PartialDiagnosticAt Warning(Loc, S.PDiag(
1926 diag::warn_return_typestate_for_unconsumable_type) << TypeName);
1928 Warnings.emplace_back(std::move(Warning), OptionalNotes());
1931 void warnReturnTypestateMismatch(SourceLocation Loc, StringRef ExpectedState,
1932 StringRef ObservedState) override {
1934 PartialDiagnosticAt Warning(Loc, S.PDiag(
1935 diag::warn_return_typestate_mismatch) << ExpectedState << ObservedState);
1937 Warnings.emplace_back(std::move(Warning), OptionalNotes());
1940 void warnUseOfTempInInvalidState(StringRef MethodName, StringRef State,
1941 SourceLocation Loc) override {
1943 PartialDiagnosticAt Warning(Loc, S.PDiag(
1944 diag::warn_use_of_temp_in_invalid_state) << MethodName << State);
1946 Warnings.emplace_back(std::move(Warning), OptionalNotes());
1949 void warnUseInInvalidState(StringRef MethodName, StringRef VariableName,
1950 StringRef State, SourceLocation Loc) override {
1952 PartialDiagnosticAt Warning(Loc, S.PDiag(diag::warn_use_in_invalid_state) <<
1953 MethodName << VariableName << State);
1955 Warnings.emplace_back(std::move(Warning), OptionalNotes());
1958 } // anonymous namespace
1959 } // namespace consumed
1960 } // namespace clang
1962 //===----------------------------------------------------------------------===//
1963 // AnalysisBasedWarnings - Worker object used by Sema to execute analysis-based
1964 // warnings on a function, method, or block.
1965 //===----------------------------------------------------------------------===//
1967 clang::sema::AnalysisBasedWarnings::Policy::Policy() {
1968 enableCheckFallThrough = 1;
1969 enableCheckUnreachable = 0;
1970 enableThreadSafetyAnalysis = 0;
1971 enableConsumedAnalysis = 0;
1974 static unsigned isEnabled(DiagnosticsEngine &D, unsigned diag) {
1975 return (unsigned)!D.isIgnored(diag, SourceLocation());
1978 clang::sema::AnalysisBasedWarnings::AnalysisBasedWarnings(Sema &s)
1980 NumFunctionsAnalyzed(0),
1981 NumFunctionsWithBadCFGs(0),
1983 MaxCFGBlocksPerFunction(0),
1984 NumUninitAnalysisFunctions(0),
1985 NumUninitAnalysisVariables(0),
1986 MaxUninitAnalysisVariablesPerFunction(0),
1987 NumUninitAnalysisBlockVisits(0),
1988 MaxUninitAnalysisBlockVisitsPerFunction(0) {
1990 using namespace diag;
1991 DiagnosticsEngine &D = S.getDiagnostics();
1993 DefaultPolicy.enableCheckUnreachable =
1994 isEnabled(D, warn_unreachable) ||
1995 isEnabled(D, warn_unreachable_break) ||
1996 isEnabled(D, warn_unreachable_return) ||
1997 isEnabled(D, warn_unreachable_loop_increment);
1999 DefaultPolicy.enableThreadSafetyAnalysis =
2000 isEnabled(D, warn_double_lock);
2002 DefaultPolicy.enableConsumedAnalysis =
2003 isEnabled(D, warn_use_in_invalid_state);
2006 static void flushDiagnostics(Sema &S, const sema::FunctionScopeInfo *fscope) {
2007 for (const auto &D : fscope->PossiblyUnreachableDiags)
2008 S.Diag(D.Loc, D.PD);
2012 AnalysisBasedWarnings::IssueWarnings(sema::AnalysisBasedWarnings::Policy P,
2013 sema::FunctionScopeInfo *fscope,
2014 const Decl *D, QualType BlockType) {
2016 // We avoid doing analysis-based warnings when there are errors for
2018 // (1) The CFGs often can't be constructed (if the body is invalid), so
2019 // don't bother trying.
2020 // (2) The code already has problems; running the analysis just takes more
2022 DiagnosticsEngine &Diags = S.getDiagnostics();
2024 // Do not do any analysis if we are going to just ignore them.
2025 if (Diags.getIgnoreAllWarnings() ||
2026 (Diags.getSuppressSystemWarnings() &&
2027 S.SourceMgr.isInSystemHeader(D->getLocation())))
2030 // For code in dependent contexts, we'll do this at instantiation time.
2031 if (cast<DeclContext>(D)->isDependentContext())
2034 if (Diags.hasUncompilableErrorOccurred()) {
2035 // Flush out any possibly unreachable diagnostics.
2036 flushDiagnostics(S, fscope);
2040 const Stmt *Body = D->getBody();
2043 // Construct the analysis context with the specified CFG build options.
2044 AnalysisDeclContext AC(/* AnalysisDeclContextManager */ nullptr, D);
2046 // Don't generate EH edges for CallExprs as we'd like to avoid the n^2
2047 // explosion for destructors that can result and the compile time hit.
2048 AC.getCFGBuildOptions().PruneTriviallyFalseEdges = true;
2049 AC.getCFGBuildOptions().AddEHEdges = false;
2050 AC.getCFGBuildOptions().AddInitializers = true;
2051 AC.getCFGBuildOptions().AddImplicitDtors = true;
2052 AC.getCFGBuildOptions().AddTemporaryDtors = true;
2053 AC.getCFGBuildOptions().AddCXXNewAllocator = false;
2054 AC.getCFGBuildOptions().AddCXXDefaultInitExprInCtors = true;
2056 // Force that certain expressions appear as CFGElements in the CFG. This
2057 // is used to speed up various analyses.
2058 // FIXME: This isn't the right factoring. This is here for initial
2059 // prototyping, but we need a way for analyses to say what expressions they
2060 // expect to always be CFGElements and then fill in the BuildOptions
2061 // appropriately. This is essentially a layering violation.
2062 if (P.enableCheckUnreachable || P.enableThreadSafetyAnalysis ||
2063 P.enableConsumedAnalysis) {
2064 // Unreachable code analysis and thread safety require a linearized CFG.
2065 AC.getCFGBuildOptions().setAllAlwaysAdd();
2068 AC.getCFGBuildOptions()
2069 .setAlwaysAdd(Stmt::BinaryOperatorClass)
2070 .setAlwaysAdd(Stmt::CompoundAssignOperatorClass)
2071 .setAlwaysAdd(Stmt::BlockExprClass)
2072 .setAlwaysAdd(Stmt::CStyleCastExprClass)
2073 .setAlwaysAdd(Stmt::DeclRefExprClass)
2074 .setAlwaysAdd(Stmt::ImplicitCastExprClass)
2075 .setAlwaysAdd(Stmt::UnaryOperatorClass)
2076 .setAlwaysAdd(Stmt::AttributedStmtClass);
2079 // Install the logical handler for -Wtautological-overlap-compare
2080 llvm::Optional<LogicalErrorHandler> LEH;
2081 if (!Diags.isIgnored(diag::warn_tautological_overlap_comparison,
2082 D->getBeginLoc())) {
2084 AC.getCFGBuildOptions().Observer = &*LEH;
2087 // Emit delayed diagnostics.
2088 if (!fscope->PossiblyUnreachableDiags.empty()) {
2089 bool analyzed = false;
2091 // Register the expressions with the CFGBuilder.
2092 for (const auto &D : fscope->PossiblyUnreachableDiags) {
2093 for (const Stmt *S : D.Stmts)
2094 AC.registerForcedBlockExpression(S);
2099 for (const auto &D : fscope->PossiblyUnreachableDiags) {
2100 bool AllReachable = true;
2101 for (const Stmt *S : D.Stmts) {
2102 const CFGBlock *block = AC.getBlockForRegisteredExpression(S);
2103 CFGReverseBlockReachabilityAnalysis *cra =
2104 AC.getCFGReachablityAnalysis();
2105 // FIXME: We should be able to assert that block is non-null, but
2106 // the CFG analysis can skip potentially-evaluated expressions in
2107 // edge cases; see test/Sema/vla-2.c.
2109 // Can this block be reached from the entrance?
2110 if (!cra->isReachable(&AC.getCFG()->getEntry(), block)) {
2111 AllReachable = false;
2115 // If we cannot map to a basic block, assume the statement is
2120 S.Diag(D.Loc, D.PD);
2125 flushDiagnostics(S, fscope);
2128 // Warning: check missing 'return'
2129 if (P.enableCheckFallThrough) {
2130 const CheckFallThroughDiagnostics &CD =
2132 ? CheckFallThroughDiagnostics::MakeForBlock()
2133 : (isa<CXXMethodDecl>(D) &&
2134 cast<CXXMethodDecl>(D)->getOverloadedOperator() == OO_Call &&
2135 cast<CXXMethodDecl>(D)->getParent()->isLambda())
2136 ? CheckFallThroughDiagnostics::MakeForLambda()
2137 : (fscope->isCoroutine()
2138 ? CheckFallThroughDiagnostics::MakeForCoroutine(D)
2139 : CheckFallThroughDiagnostics::MakeForFunction(D)));
2140 CheckFallThroughForBody(S, D, Body, BlockType, CD, AC, fscope);
2143 // Warning: check for unreachable code
2144 if (P.enableCheckUnreachable) {
2145 // Only check for unreachable code on non-template instantiations.
2146 // Different template instantiations can effectively change the control-flow
2147 // and it is very difficult to prove that a snippet of code in a template
2148 // is unreachable for all instantiations.
2149 bool isTemplateInstantiation = false;
2150 if (const FunctionDecl *Function = dyn_cast<FunctionDecl>(D))
2151 isTemplateInstantiation = Function->isTemplateInstantiation();
2152 if (!isTemplateInstantiation)
2153 CheckUnreachable(S, AC);
2156 // Check for thread safety violations
2157 if (P.enableThreadSafetyAnalysis) {
2158 SourceLocation FL = AC.getDecl()->getLocation();
2159 SourceLocation FEL = AC.getDecl()->getEndLoc();
2160 threadSafety::ThreadSafetyReporter Reporter(S, FL, FEL);
2161 if (!Diags.isIgnored(diag::warn_thread_safety_beta, D->getBeginLoc()))
2162 Reporter.setIssueBetaWarnings(true);
2163 if (!Diags.isIgnored(diag::warn_thread_safety_verbose, D->getBeginLoc()))
2164 Reporter.setVerbose(true);
2166 threadSafety::runThreadSafetyAnalysis(AC, Reporter,
2167 &S.ThreadSafetyDeclCache);
2168 Reporter.emitDiagnostics();
2171 // Check for violations of consumed properties.
2172 if (P.enableConsumedAnalysis) {
2173 consumed::ConsumedWarningsHandler WarningHandler(S);
2174 consumed::ConsumedAnalyzer Analyzer(WarningHandler);
2178 if (!Diags.isIgnored(diag::warn_uninit_var, D->getBeginLoc()) ||
2179 !Diags.isIgnored(diag::warn_sometimes_uninit_var, D->getBeginLoc()) ||
2180 !Diags.isIgnored(diag::warn_maybe_uninit_var, D->getBeginLoc())) {
2181 if (CFG *cfg = AC.getCFG()) {
2182 UninitValsDiagReporter reporter(S);
2183 UninitVariablesAnalysisStats stats;
2184 std::memset(&stats, 0, sizeof(UninitVariablesAnalysisStats));
2185 runUninitializedVariablesAnalysis(*cast<DeclContext>(D), *cfg, AC,
2188 if (S.CollectStats && stats.NumVariablesAnalyzed > 0) {
2189 ++NumUninitAnalysisFunctions;
2190 NumUninitAnalysisVariables += stats.NumVariablesAnalyzed;
2191 NumUninitAnalysisBlockVisits += stats.NumBlockVisits;
2192 MaxUninitAnalysisVariablesPerFunction =
2193 std::max(MaxUninitAnalysisVariablesPerFunction,
2194 stats.NumVariablesAnalyzed);
2195 MaxUninitAnalysisBlockVisitsPerFunction =
2196 std::max(MaxUninitAnalysisBlockVisitsPerFunction,
2197 stats.NumBlockVisits);
2202 bool FallThroughDiagFull =
2203 !Diags.isIgnored(diag::warn_unannotated_fallthrough, D->getBeginLoc());
2204 bool FallThroughDiagPerFunction = !Diags.isIgnored(
2205 diag::warn_unannotated_fallthrough_per_function, D->getBeginLoc());
2206 if (FallThroughDiagFull || FallThroughDiagPerFunction ||
2207 fscope->HasFallthroughStmt) {
2208 DiagnoseSwitchLabelsFallthrough(S, AC, !FallThroughDiagFull);
2211 if (S.getLangOpts().ObjCWeak &&
2212 !Diags.isIgnored(diag::warn_arc_repeated_use_of_weak, D->getBeginLoc()))
2213 diagnoseRepeatedUseOfWeak(S, fscope, D, AC.getParentMap());
2216 // Check for infinite self-recursion in functions
2217 if (!Diags.isIgnored(diag::warn_infinite_recursive_function,
2218 D->getBeginLoc())) {
2219 if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
2220 checkRecursiveFunction(S, FD, Body, AC);
2224 // Check for throw out of non-throwing function.
2225 if (!Diags.isIgnored(diag::warn_throw_in_noexcept_func, D->getBeginLoc()))
2226 if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D))
2227 if (S.getLangOpts().CPlusPlus && isNoexcept(FD))
2228 checkThrowInNonThrowingFunc(S, FD, AC);
2230 // If none of the previous checks caused a CFG build, trigger one here
2231 // for -Wtautological-overlap-compare
2232 if (!Diags.isIgnored(diag::warn_tautological_overlap_comparison,
2233 D->getBeginLoc())) {
2237 // Collect statistics about the CFG if it was built.
2238 if (S.CollectStats && AC.isCFGBuilt()) {
2239 ++NumFunctionsAnalyzed;
2240 if (CFG *cfg = AC.getCFG()) {
2241 // If we successfully built a CFG for this context, record some more
2242 // detail information about it.
2243 NumCFGBlocks += cfg->getNumBlockIDs();
2244 MaxCFGBlocksPerFunction = std::max(MaxCFGBlocksPerFunction,
2245 cfg->getNumBlockIDs());
2247 ++NumFunctionsWithBadCFGs;
2252 void clang::sema::AnalysisBasedWarnings::PrintStats() const {
2253 llvm::errs() << "\n*** Analysis Based Warnings Stats:\n";
2255 unsigned NumCFGsBuilt = NumFunctionsAnalyzed - NumFunctionsWithBadCFGs;
2256 unsigned AvgCFGBlocksPerFunction =
2257 !NumCFGsBuilt ? 0 : NumCFGBlocks/NumCFGsBuilt;
2258 llvm::errs() << NumFunctionsAnalyzed << " functions analyzed ("
2259 << NumFunctionsWithBadCFGs << " w/o CFGs).\n"
2260 << " " << NumCFGBlocks << " CFG blocks built.\n"
2261 << " " << AvgCFGBlocksPerFunction
2262 << " average CFG blocks per function.\n"
2263 << " " << MaxCFGBlocksPerFunction
2264 << " max CFG blocks per function.\n";
2266 unsigned AvgUninitVariablesPerFunction = !NumUninitAnalysisFunctions ? 0
2267 : NumUninitAnalysisVariables/NumUninitAnalysisFunctions;
2268 unsigned AvgUninitBlockVisitsPerFunction = !NumUninitAnalysisFunctions ? 0
2269 : NumUninitAnalysisBlockVisits/NumUninitAnalysisFunctions;
2270 llvm::errs() << NumUninitAnalysisFunctions
2271 << " functions analyzed for uninitialiazed variables\n"
2272 << " " << NumUninitAnalysisVariables << " variables analyzed.\n"
2273 << " " << AvgUninitVariablesPerFunction
2274 << " average variables per function.\n"
2275 << " " << MaxUninitAnalysisVariablesPerFunction
2276 << " max variables per function.\n"
2277 << " " << NumUninitAnalysisBlockVisits << " block visits.\n"
2278 << " " << AvgUninitBlockVisitsPerFunction
2279 << " average block visits per function.\n"
2280 << " " << MaxUninitAnalysisBlockVisitsPerFunction
2281 << " max block visits per function.\n";