clang/lib/Sema/AnalysisBasedWarnings.cpp

   1 //=- AnalysisBasedWarnings.cpp - Sema warnings based on libAnalysis -*- C++ -*-=//
   2 //
   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
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   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.
  12 //
  13 //===----------------------------------------------------------------------===//
  14
  15 #include "clang/Sema/AnalysisBasedWarnings.h"
  16 #include "clang/AST/Decl.h"
  17 #include "clang/AST/DeclCXX.h"
  18 #include "clang/AST/DeclObjC.h"
  19 #include "clang/AST/EvaluatedExprVisitor.h"
  20 #include "clang/AST/Expr.h"
  21 #include "clang/AST/ExprCXX.h"
  22 #include "clang/AST/ExprObjC.h"
  23 #include "clang/AST/OperationKinds.h"
  24 #include "clang/AST/ParentMap.h"
  25 #include "clang/AST/RecursiveASTVisitor.h"
  26 #include "clang/AST/StmtCXX.h"
  27 #include "clang/AST/StmtObjC.h"
  28 #include "clang/AST/StmtVisitor.h"
  29 #include "clang/AST/RecursiveASTVisitor.h"
  30 #include "clang/AST/Type.h"
  31 #include "clang/Analysis/Analyses/CFGReachabilityAnalysis.h"
  32 #include "clang/Analysis/Analyses/CalledOnceCheck.h"
  33 #include "clang/Analysis/Analyses/Consumed.h"
  34 #include "clang/Analysis/Analyses/ReachableCode.h"
  35 #include "clang/Analysis/Analyses/ThreadSafety.h"
  36 #include "clang/Analysis/Analyses/UninitializedValues.h"
  37 #include "clang/Analysis/Analyses/UnsafeBufferUsage.h"
  38 #include "clang/Analysis/AnalysisDeclContext.h"
  39 #include "clang/Analysis/CFG.h"
  40 #include "clang/Analysis/CFGStmtMap.h"
  41 #include "clang/Basic/Diagnostic.h"
  42 #include "clang/Basic/SourceLocation.h"
  43 #include "clang/Basic/SourceManager.h"
  44 #include "clang/Lex/Preprocessor.h"
  45 #include "clang/Sema/ScopeInfo.h"
  46 #include "clang/Sema/SemaInternal.h"
  47 #include "llvm/ADT/ArrayRef.h"
  48 #include "llvm/ADT/BitVector.h"
  49 #include "llvm/ADT/MapVector.h"
  50 #include "llvm/ADT/STLFunctionalExtras.h"
  51 #include "llvm/ADT/SmallString.h"
  52 #include "llvm/ADT/SmallVector.h"
  53 #include "llvm/ADT/StringRef.h"
  54 #include "llvm/Support/Casting.h"
  55 #include <algorithm>
  56 #include <deque>
  57 #include <iterator>
  58 #include <optional>
  59
  60 using namespace clang;
  61
  62 //===----------------------------------------------------------------------===//
  63 // Unreachable code analysis.
  64 //===----------------------------------------------------------------------===//
  65
  66 namespace {
  67   class UnreachableCodeHandler : public reachable_code::Callback {
  68     Sema &S;
  69     SourceRange PreviousSilenceableCondVal;
  70
  71   public:
  72     UnreachableCodeHandler(Sema &s) : S(s) {}
  73
  74     void HandleUnreachable(reachable_code::UnreachableKind UK, SourceLocation L,
  75                            SourceRange SilenceableCondVal, SourceRange R1,
  76                            SourceRange R2, bool HasFallThroughAttr) override {
  77       // If the diagnosed code is `[[fallthrough]];` and
  78       // `-Wunreachable-code-fallthrough` is  enabled, suppress `code will never
  79       // be executed` warning to avoid generating diagnostic twice
  80       if (HasFallThroughAttr &&
  81           !S.getDiagnostics().isIgnored(diag::warn_unreachable_fallthrough_attr,
  82                                         SourceLocation()))
  83         return;
  84
  85       // Avoid reporting multiple unreachable code diagnostics that are
  86       // triggered by the same conditional value.
  87       if (PreviousSilenceableCondVal.isValid() &&
  88           SilenceableCondVal.isValid() &&
  89           PreviousSilenceableCondVal == SilenceableCondVal)
  90         return;
  91       PreviousSilenceableCondVal = SilenceableCondVal;
  92
  93       unsigned diag = diag::warn_unreachable;
  94       switch (UK) {
  95         case reachable_code::UK_Break:
  96           diag = diag::warn_unreachable_break;
  97           break;
  98         case reachable_code::UK_Return:
  99           diag = diag::warn_unreachable_return;
 100           break;
 101         case reachable_code::UK_Loop_Increment:
 102           diag = diag::warn_unreachable_loop_increment;
 103           break;
 104         case reachable_code::UK_Other:
 105           break;
 106       }
 107
 108       S.Diag(L, diag) << R1 << R2;
 109
 110       SourceLocation Open = SilenceableCondVal.getBegin();
 111       if (Open.isValid()) {
 112         SourceLocation Close = SilenceableCondVal.getEnd();
 113         Close = S.getLocForEndOfToken(Close);
 114         if (Close.isValid()) {
 115           S.Diag(Open, diag::note_unreachable_silence)
 116             << FixItHint::CreateInsertion(Open, "/* DISABLES CODE */ (")
 117             << FixItHint::CreateInsertion(Close, ")");
 118         }
 119       }
 120     }
 121   };
 122 } // anonymous namespace
 123
 124 /// CheckUnreachable - Check for unreachable code.
 125 static void CheckUnreachable(Sema &S, AnalysisDeclContext &AC) {
 126   // As a heuristic prune all diagnostics not in the main file.  Currently
 127   // the majority of warnings in headers are false positives.  These
 128   // are largely caused by configuration state, e.g. preprocessor
 129   // defined code, etc.
 130   //
 131   // Note that this is also a performance optimization.  Analyzing
 132   // headers many times can be expensive.
 133   if (!S.getSourceManager().isInMainFile(AC.getDecl()->getBeginLoc()))
 134     return;
 135
 136   UnreachableCodeHandler UC(S);
 137   reachable_code::FindUnreachableCode(AC, S.getPreprocessor(), UC);
 138 }
 139
 140 namespace {
 141 /// Warn on logical operator errors in CFGBuilder
 142 class LogicalErrorHandler : public CFGCallback {
 143   Sema &S;
 144
 145 public:
 146   LogicalErrorHandler(Sema &S) : S(S) {}
 147
 148   static bool HasMacroID(const Expr *E) {
 149     if (E->getExprLoc().isMacroID())
 150       return true;
 151
 152     // Recurse to children.
 153     for (const Stmt *SubStmt : E->children())
 154       if (const Expr *SubExpr = dyn_cast_or_null<Expr>(SubStmt))
 155         if (HasMacroID(SubExpr))
 156           return true;
 157
 158     return false;
 159   }
 160
 161   void logicAlwaysTrue(const BinaryOperator *B, bool isAlwaysTrue) override {
 162     if (HasMacroID(B))
 163       return;
 164
 165     unsigned DiagID = isAlwaysTrue
 166                           ? diag::warn_tautological_negation_or_compare
 167                           : diag::warn_tautological_negation_and_compare;
 168     SourceRange DiagRange = B->getSourceRange();
 169     S.Diag(B->getExprLoc(), DiagID) << DiagRange;
 170   }
 171
 172   void compareAlwaysTrue(const BinaryOperator *B, bool isAlwaysTrue) override {
 173     if (HasMacroID(B))
 174       return;
 175
 176     SourceRange DiagRange = B->getSourceRange();
 177     S.Diag(B->getExprLoc(), diag::warn_tautological_overlap_comparison)
 178         << DiagRange << isAlwaysTrue;
 179   }
 180
 181   void compareBitwiseEquality(const BinaryOperator *B,
 182                               bool isAlwaysTrue) override {
 183     if (HasMacroID(B))
 184       return;
 185
 186     SourceRange DiagRange = B->getSourceRange();
 187     S.Diag(B->getExprLoc(), diag::warn_comparison_bitwise_always)
 188         << DiagRange << isAlwaysTrue;
 189   }
 190
 191   void compareBitwiseOr(const BinaryOperator *B) override {
 192     if (HasMacroID(B))
 193       return;
 194
 195     SourceRange DiagRange = B->getSourceRange();
 196     S.Diag(B->getExprLoc(), diag::warn_comparison_bitwise_or) << DiagRange;
 197   }
 198
 199   static bool hasActiveDiagnostics(DiagnosticsEngine &Diags,
 200                                    SourceLocation Loc) {
 201     return !Diags.isIgnored(diag::warn_tautological_overlap_comparison, Loc) ||
 202            !Diags.isIgnored(diag::warn_comparison_bitwise_or, Loc) ||
 203            !Diags.isIgnored(diag::warn_tautological_negation_and_compare, Loc);
 204   }
 205 };
 206 } // anonymous namespace
 207
 208 //===----------------------------------------------------------------------===//
 209 // Check for infinite self-recursion in functions
 210 //===----------------------------------------------------------------------===//
 211
 212 // Returns true if the function is called anywhere within the CFGBlock.
 213 // For member functions, the additional condition of being call from the
 214 // this pointer is required.
 215 static bool hasRecursiveCallInPath(const FunctionDecl *FD, CFGBlock &Block) {
 216   // Process all the Stmt's in this block to find any calls to FD.
 217   for (const auto &B : Block) {
 218     if (B.getKind() != CFGElement::Statement)
 219       continue;
 220
 221     const CallExpr *CE = dyn_cast<CallExpr>(B.getAs<CFGStmt>()->getStmt());
 222     if (!CE || !CE->getCalleeDecl() ||
 223         CE->getCalleeDecl()->getCanonicalDecl() != FD)
 224       continue;
 225
 226     // Skip function calls which are qualified with a templated class.
 227     if (const DeclRefExpr *DRE =
 228             dyn_cast<DeclRefExpr>(CE->getCallee()->IgnoreParenImpCasts())) {
 229       if (NestedNameSpecifier *NNS = DRE->getQualifier()) {
 230         if (NNS->getKind() == NestedNameSpecifier::TypeSpec &&
 231             isa<TemplateSpecializationType>(NNS->getAsType())) {
 232           continue;
 233         }
 234       }
 235     }
 236
 237     const CXXMemberCallExpr *MCE = dyn_cast<CXXMemberCallExpr>(CE);
 238     if (!MCE || isa<CXXThisExpr>(MCE->getImplicitObjectArgument()) ||
 239         !MCE->getMethodDecl()->isVirtual())
 240       return true;
 241   }
 242   return false;
 243 }
 244
 245 // Returns true if every path from the entry block passes through a call to FD.
 246 static bool checkForRecursiveFunctionCall(const FunctionDecl *FD, CFG *cfg) {
 247   llvm::SmallPtrSet<CFGBlock *, 16> Visited;
 248   llvm::SmallVector<CFGBlock *, 16> WorkList;
 249   // Keep track of whether we found at least one recursive path.
 250   bool foundRecursion = false;
 251
 252   const unsigned ExitID = cfg->getExit().getBlockID();
 253
 254   // Seed the work list with the entry block.
 255   WorkList.push_back(&cfg->getEntry());
 256
 257   while (!WorkList.empty()) {
 258     CFGBlock *Block = WorkList.pop_back_val();
 259
 260     for (auto I = Block->succ_begin(), E = Block->succ_end(); I != E; ++I) {
 261       if (CFGBlock *SuccBlock = *I) {
 262         if (!Visited.insert(SuccBlock).second)
 263           continue;
 264
 265         // Found a path to the exit node without a recursive call.
 266         if (ExitID == SuccBlock->getBlockID())
 267           return false;
 268
 269         // If the successor block contains a recursive call, end analysis there.
 270         if (hasRecursiveCallInPath(FD, *SuccBlock)) {
 271           foundRecursion = true;
 272           continue;
 273         }
 274
 275         WorkList.push_back(SuccBlock);
 276       }
 277     }
 278   }
 279   return foundRecursion;
 280 }
 281
 282 static void checkRecursiveFunction(Sema &S, const FunctionDecl *FD,
 283                                    const Stmt *Body, AnalysisDeclContext &AC) {
 284   FD = FD->getCanonicalDecl();
 285
 286   // Only run on non-templated functions and non-templated members of
 287   // templated classes.
 288   if (FD->getTemplatedKind() != FunctionDecl::TK_NonTemplate &&
 289       FD->getTemplatedKind() != FunctionDecl::TK_MemberSpecialization)
 290     return;
 291
 292   CFG *cfg = AC.getCFG();
 293   if (!cfg) return;
 294
 295   // If the exit block is unreachable, skip processing the function.
 296   if (cfg->getExit().pred_empty())
 297     return;
 298
 299   // Emit diagnostic if a recursive function call is detected for all paths.
 300   if (checkForRecursiveFunctionCall(FD, cfg))
 301     S.Diag(Body->getBeginLoc(), diag::warn_infinite_recursive_function);
 302 }
 303
 304 //===----------------------------------------------------------------------===//
 305 // Check for throw in a non-throwing function.
 306 //===----------------------------------------------------------------------===//
 307
 308 /// Determine whether an exception thrown by E, unwinding from ThrowBlock,
 309 /// can reach ExitBlock.
 310 static bool throwEscapes(Sema &S, const CXXThrowExpr *E, CFGBlock &ThrowBlock,
 311                          CFG *Body) {
 312   SmallVector<CFGBlock *, 16> Stack;
 313   llvm::BitVector Queued(Body->getNumBlockIDs());
 314
 315   Stack.push_back(&ThrowBlock);
 316   Queued[ThrowBlock.getBlockID()] = true;
 317
 318   while (!Stack.empty()) {
 319     CFGBlock &UnwindBlock = *Stack.back();
 320     Stack.pop_back();
 321
 322     for (auto &Succ : UnwindBlock.succs()) {
 323       if (!Succ.isReachable() || Queued[Succ->getBlockID()])
 324         continue;
 325
 326       if (Succ->getBlockID() == Body->getExit().getBlockID())
 327         return true;
 328
 329       if (auto *Catch =
 330               dyn_cast_or_null<CXXCatchStmt>(Succ->getLabel())) {
 331         QualType Caught = Catch->getCaughtType();
 332         if (Caught.isNull() || // catch (...) catches everything
 333             !E->getSubExpr() || // throw; is considered cuaght by any handler
 334             S.handlerCanCatch(Caught, E->getSubExpr()->getType()))
 335           // Exception doesn't escape via this path.
 336           break;
 337       } else {
 338         Stack.push_back(Succ);
 339         Queued[Succ->getBlockID()] = true;
 340       }
 341     }
 342   }
 343
 344   return false;
 345 }
 346
 347 static void visitReachableThrows(
 348     CFG *BodyCFG,
 349     llvm::function_ref<void(const CXXThrowExpr *, CFGBlock &)> Visit) {
 350   llvm::BitVector Reachable(BodyCFG->getNumBlockIDs());
 351   clang::reachable_code::ScanReachableFromBlock(&BodyCFG->getEntry(), Reachable);
 352   for (CFGBlock *B : *BodyCFG) {
 353     if (!Reachable[B->getBlockID()])
 354       continue;
 355     for (CFGElement &E : *B) {
 356       std::optional<CFGStmt> S = E.getAs<CFGStmt>();
 357       if (!S)
 358         continue;
 359       if (auto *Throw = dyn_cast<CXXThrowExpr>(S->getStmt()))
 360         Visit(Throw, *B);
 361     }
 362   }
 363 }
 364
 365 static void EmitDiagForCXXThrowInNonThrowingFunc(Sema &S, SourceLocation OpLoc,
 366                                                  const FunctionDecl *FD) {
 367   if (!S.getSourceManager().isInSystemHeader(OpLoc) &&
 368       FD->getTypeSourceInfo()) {
 369     S.Diag(OpLoc, diag::warn_throw_in_noexcept_func) << FD;
 370     if (S.getLangOpts().CPlusPlus11 &&
 371         (isa<CXXDestructorDecl>(FD) ||
 372          FD->getDeclName().getCXXOverloadedOperator() == OO_Delete ||
 373          FD->getDeclName().getCXXOverloadedOperator() == OO_Array_Delete)) {
 374       if (const auto *Ty = FD->getTypeSourceInfo()->getType()->
 375                                          getAs<FunctionProtoType>())
 376         S.Diag(FD->getLocation(), diag::note_throw_in_dtor)
 377             << !isa<CXXDestructorDecl>(FD) << !Ty->hasExceptionSpec()
 378             << FD->getExceptionSpecSourceRange();
 379     } else
 380       S.Diag(FD->getLocation(), diag::note_throw_in_function)
 381           << FD->getExceptionSpecSourceRange();
 382   }
 383 }
 384
 385 static void checkThrowInNonThrowingFunc(Sema &S, const FunctionDecl *FD,
 386                                         AnalysisDeclContext &AC) {
 387   CFG *BodyCFG = AC.getCFG();
 388   if (!BodyCFG)
 389     return;
 390   if (BodyCFG->getExit().pred_empty())
 391     return;
 392   visitReachableThrows(BodyCFG, [&](const CXXThrowExpr *Throw, CFGBlock &Block) {
 393     if (throwEscapes(S, Throw, Block, BodyCFG))
 394       EmitDiagForCXXThrowInNonThrowingFunc(S, Throw->getThrowLoc(), FD);
 395   });
 396 }
 397
 398 static bool isNoexcept(const FunctionDecl *FD) {
 399   const auto *FPT = FD->getType()->castAs<FunctionProtoType>();
 400   if (FPT->isNothrow() || FD->hasAttr<NoThrowAttr>())
 401     return true;
 402   return false;
 403 }
 404
 405 //===----------------------------------------------------------------------===//
 406 // Check for missing return value.
 407 //===----------------------------------------------------------------------===//
 408
 409 enum ControlFlowKind {
 410   UnknownFallThrough,
 411   NeverFallThrough,
 412   MaybeFallThrough,
 413   AlwaysFallThrough,
 414   NeverFallThroughOrReturn
 415 };
 416
 417 /// CheckFallThrough - Check that we don't fall off the end of a
 418 /// Statement that should return a value.
 419 ///
 420 /// \returns AlwaysFallThrough iff we always fall off the end of the statement,
 421 /// MaybeFallThrough iff we might or might not fall off the end,
 422 /// NeverFallThroughOrReturn iff we never fall off the end of the statement or
 423 /// return.  We assume NeverFallThrough iff we never fall off the end of the
 424 /// statement but we may return.  We assume that functions not marked noreturn
 425 /// will return.
 426 static ControlFlowKind CheckFallThrough(AnalysisDeclContext &AC) {
 427   CFG *cfg = AC.getCFG();
 428   if (!cfg) return UnknownFallThrough;
 429
 430   // The CFG leaves in dead things, and we don't want the dead code paths to
 431   // confuse us, so we mark all live things first.
 432   llvm::BitVector live(cfg->getNumBlockIDs());
 433   unsigned count = reachable_code::ScanReachableFromBlock(&cfg->getEntry(),
 434                                                           live);
 435
 436   bool AddEHEdges = AC.getAddEHEdges();
 437   if (!AddEHEdges && count != cfg->getNumBlockIDs())
 438     // When there are things remaining dead, and we didn't add EH edges
 439     // from CallExprs to the catch clauses, we have to go back and
 440     // mark them as live.
 441     for (const auto *B : *cfg) {
 442       if (!live[B->getBlockID()]) {
 443         if (B->pred_begin() == B->pred_end()) {
 444           const Stmt *Term = B->getTerminatorStmt();
 445           if (Term && isa<CXXTryStmt>(Term))
 446             // When not adding EH edges from calls, catch clauses
 447             // can otherwise seem dead.  Avoid noting them as dead.
 448             count += reachable_code::ScanReachableFromBlock(B, live);
 449           continue;
 450         }
 451       }
 452     }
 453
 454   // Now we know what is live, we check the live precessors of the exit block
 455   // and look for fall through paths, being careful to ignore normal returns,
 456   // and exceptional paths.
 457   bool HasLiveReturn = false;
 458   bool HasFakeEdge = false;
 459   bool HasPlainEdge = false;
 460   bool HasAbnormalEdge = false;
 461
 462   // Ignore default cases that aren't likely to be reachable because all
 463   // enums in a switch(X) have explicit case statements.
 464   CFGBlock::FilterOptions FO;
 465   FO.IgnoreDefaultsWithCoveredEnums = 1;
 466
 467   for (CFGBlock::filtered_pred_iterator I =
 468            cfg->getExit().filtered_pred_start_end(FO);
 469        I.hasMore(); ++I) {
 470     const CFGBlock &B = **I;
 471     if (!live[B.getBlockID()])
 472       continue;
 473
 474     // Skip blocks which contain an element marked as no-return. They don't
 475     // represent actually viable edges into the exit block, so mark them as
 476     // abnormal.
 477     if (B.hasNoReturnElement()) {
 478       HasAbnormalEdge = true;
 479       continue;
 480     }
 481
 482     // Destructors can appear after the 'return' in the CFG.  This is
 483     // normal.  We need to look pass the destructors for the return
 484     // statement (if it exists).
 485     CFGBlock::const_reverse_iterator ri = B.rbegin(), re = B.rend();
 486
 487     for ( ; ri != re ; ++ri)
 488       if (ri->getAs<CFGStmt>())
 489         break;
 490
 491     // No more CFGElements in the block?
 492     if (ri == re) {
 493       const Stmt *Term = B.getTerminatorStmt();
 494       if (Term && (isa<CXXTryStmt>(Term) || isa<ObjCAtTryStmt>(Term))) {
 495         HasAbnormalEdge = true;
 496         continue;
 497       }
 498       // A labeled empty statement, or the entry block...
 499       HasPlainEdge = true;
 500       continue;
 501     }
 502
 503     CFGStmt CS = ri->castAs<CFGStmt>();
 504     const Stmt *S = CS.getStmt();
 505     if (isa<ReturnStmt>(S) || isa<CoreturnStmt>(S)) {
 506       HasLiveReturn = true;
 507       continue;
 508     }
 509     if (isa<ObjCAtThrowStmt>(S)) {
 510       HasFakeEdge = true;
 511       continue;
 512     }
 513     if (isa<CXXThrowExpr>(S)) {
 514       HasFakeEdge = true;
 515       continue;
 516     }
 517     if (isa<MSAsmStmt>(S)) {
 518       // TODO: Verify this is correct.
 519       HasFakeEdge = true;
 520       HasLiveReturn = true;
 521       continue;
 522     }
 523     if (isa<CXXTryStmt>(S)) {
 524       HasAbnormalEdge = true;
 525       continue;
 526     }
 527     if (!llvm::is_contained(B.succs(), &cfg->getExit())) {
 528       HasAbnormalEdge = true;
 529       continue;
 530     }
 531
 532     HasPlainEdge = true;
 533   }
 534   if (!HasPlainEdge) {
 535     if (HasLiveReturn)
 536       return NeverFallThrough;
 537     return NeverFallThroughOrReturn;
 538   }
 539   if (HasAbnormalEdge || HasFakeEdge || HasLiveReturn)
 540     return MaybeFallThrough;
 541   // This says AlwaysFallThrough for calls to functions that are not marked
 542   // noreturn, that don't return.  If people would like this warning to be more
 543   // accurate, such functions should be marked as noreturn.
 544   return AlwaysFallThrough;
 545 }
 546
 547 namespace {
 548
 549 struct CheckFallThroughDiagnostics {
 550   unsigned diag_MaybeFallThrough_HasNoReturn;
 551   unsigned diag_MaybeFallThrough_ReturnsNonVoid;
 552   unsigned diag_AlwaysFallThrough_HasNoReturn;
 553   unsigned diag_AlwaysFallThrough_ReturnsNonVoid;
 554   unsigned diag_NeverFallThroughOrReturn;
 555   enum { Function, Block, Lambda, Coroutine } funMode;
 556   SourceLocation FuncLoc;
 557
 558   static CheckFallThroughDiagnostics MakeForFunction(const Decl *Func) {
 559     CheckFallThroughDiagnostics D;
 560     D.FuncLoc = Func->getLocation();
 561     D.diag_MaybeFallThrough_HasNoReturn =
 562       diag::warn_falloff_noreturn_function;
 563     D.diag_MaybeFallThrough_ReturnsNonVoid =
 564       diag::warn_maybe_falloff_nonvoid_function;
 565     D.diag_AlwaysFallThrough_HasNoReturn =
 566       diag::warn_falloff_noreturn_function;
 567     D.diag_AlwaysFallThrough_ReturnsNonVoid =
 568       diag::warn_falloff_nonvoid_function;
 569
 570     // Don't suggest that virtual functions be marked "noreturn", since they
 571     // might be overridden by non-noreturn functions.
 572     bool isVirtualMethod = false;
 573     if (const CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(Func))
 574       isVirtualMethod = Method->isVirtual();
 575
 576     // Don't suggest that template instantiations be marked "noreturn"
 577     bool isTemplateInstantiation = false;
 578     if (const FunctionDecl *Function = dyn_cast<FunctionDecl>(Func))
 579       isTemplateInstantiation = Function->isTemplateInstantiation();
 580
 581     if (!isVirtualMethod && !isTemplateInstantiation)
 582       D.diag_NeverFallThroughOrReturn =
 583         diag::warn_suggest_noreturn_function;
 584     else
 585       D.diag_NeverFallThroughOrReturn = 0;
 586
 587     D.funMode = Function;
 588     return D;
 589   }
 590
 591   static CheckFallThroughDiagnostics MakeForCoroutine(const Decl *Func) {
 592     CheckFallThroughDiagnostics D;
 593     D.FuncLoc = Func->getLocation();
 594     D.diag_MaybeFallThrough_HasNoReturn = 0;
 595     D.diag_MaybeFallThrough_ReturnsNonVoid =
 596         diag::warn_maybe_falloff_nonvoid_coroutine;
 597     D.diag_AlwaysFallThrough_HasNoReturn = 0;
 598     D.diag_AlwaysFallThrough_ReturnsNonVoid =
 599         diag::warn_falloff_nonvoid_coroutine;
 600     D.diag_NeverFallThroughOrReturn = 0;
 601     D.funMode = Coroutine;
 602     return D;
 603   }
 604
 605   static CheckFallThroughDiagnostics MakeForBlock() {
 606     CheckFallThroughDiagnostics D;
 607     D.diag_MaybeFallThrough_HasNoReturn =
 608       diag::err_noreturn_block_has_return_expr;
 609     D.diag_MaybeFallThrough_ReturnsNonVoid =
 610       diag::err_maybe_falloff_nonvoid_block;
 611     D.diag_AlwaysFallThrough_HasNoReturn =
 612       diag::err_noreturn_block_has_return_expr;
 613     D.diag_AlwaysFallThrough_ReturnsNonVoid =
 614       diag::err_falloff_nonvoid_block;
 615     D.diag_NeverFallThroughOrReturn = 0;
 616     D.funMode = Block;
 617     return D;
 618   }
 619
 620   static CheckFallThroughDiagnostics MakeForLambda() {
 621     CheckFallThroughDiagnostics D;
 622     D.diag_MaybeFallThrough_HasNoReturn =
 623       diag::err_noreturn_lambda_has_return_expr;
 624     D.diag_MaybeFallThrough_ReturnsNonVoid =
 625       diag::warn_maybe_falloff_nonvoid_lambda;
 626     D.diag_AlwaysFallThrough_HasNoReturn =
 627       diag::err_noreturn_lambda_has_return_expr;
 628     D.diag_AlwaysFallThrough_ReturnsNonVoid =
 629       diag::warn_falloff_nonvoid_lambda;
 630     D.diag_NeverFallThroughOrReturn = 0;
 631     D.funMode = Lambda;
 632     return D;
 633   }
 634
 635   bool checkDiagnostics(DiagnosticsEngine &D, bool ReturnsVoid,
 636                         bool HasNoReturn) const {
 637     if (funMode == Function) {
 638       return (ReturnsVoid ||
 639               D.isIgnored(diag::warn_maybe_falloff_nonvoid_function,
 640                           FuncLoc)) &&
 641              (!HasNoReturn ||
 642               D.isIgnored(diag::warn_noreturn_function_has_return_expr,
 643                           FuncLoc)) &&
 644              (!ReturnsVoid ||
 645               D.isIgnored(diag::warn_suggest_noreturn_block, FuncLoc));
 646     }
 647     if (funMode == Coroutine) {
 648       return (ReturnsVoid ||
 649               D.isIgnored(diag::warn_maybe_falloff_nonvoid_function, FuncLoc) ||
 650               D.isIgnored(diag::warn_maybe_falloff_nonvoid_coroutine,
 651                           FuncLoc)) &&
 652              (!HasNoReturn);
 653     }
 654     // For blocks / lambdas.
 655     return ReturnsVoid && !HasNoReturn;
 656   }
 657 };
 658
 659 } // anonymous namespace
 660
 661 /// CheckFallThroughForBody - Check that we don't fall off the end of a
 662 /// function that should return a value.  Check that we don't fall off the end
 663 /// of a noreturn function.  We assume that functions and blocks not marked
 664 /// noreturn will return.
 665 static void CheckFallThroughForBody(Sema &S, const Decl *D, const Stmt *Body,
 666                                     QualType BlockType,
 667                                     const CheckFallThroughDiagnostics &CD,
 668                                     AnalysisDeclContext &AC,
 669                                     sema::FunctionScopeInfo *FSI) {
 670
 671   bool ReturnsVoid = false;
 672   bool HasNoReturn = false;
 673   bool IsCoroutine = FSI->isCoroutine();
 674
 675   if (const auto *FD = dyn_cast<FunctionDecl>(D)) {
 676     if (const auto *CBody = dyn_cast<CoroutineBodyStmt>(Body))
 677       ReturnsVoid = CBody->getFallthroughHandler() != nullptr;
 678     else
 679       ReturnsVoid = FD->getReturnType()->isVoidType();
 680     HasNoReturn = FD->isNoReturn();
 681   }
 682   else if (const auto *MD = dyn_cast<ObjCMethodDecl>(D)) {
 683     ReturnsVoid = MD->getReturnType()->isVoidType();
 684     HasNoReturn = MD->hasAttr<NoReturnAttr>();
 685   }
 686   else if (isa<BlockDecl>(D)) {
 687     if (const FunctionType *FT =
 688           BlockType->getPointeeType()->getAs<FunctionType>()) {
 689       if (FT->getReturnType()->isVoidType())
 690         ReturnsVoid = true;
 691       if (FT->getNoReturnAttr())
 692         HasNoReturn = true;
 693     }
 694   }
 695
 696   DiagnosticsEngine &Diags = S.getDiagnostics();
 697
 698   // Short circuit for compilation speed.
 699   if (CD.checkDiagnostics(Diags, ReturnsVoid, HasNoReturn))
 700       return;
 701   SourceLocation LBrace = Body->getBeginLoc(), RBrace = Body->getEndLoc();
 702   auto EmitDiag = [&](SourceLocation Loc, unsigned DiagID) {
 703     if (IsCoroutine)
 704       S.Diag(Loc, DiagID) << FSI->CoroutinePromise->getType();
 705     else
 706       S.Diag(Loc, DiagID);
 707   };
 708
 709   // cpu_dispatch functions permit empty function bodies for ICC compatibility.
 710   if (D->getAsFunction() && D->getAsFunction()->isCPUDispatchMultiVersion())
 711     return;
 712
 713   // Either in a function body compound statement, or a function-try-block.
 714   switch (CheckFallThrough(AC)) {
 715     case UnknownFallThrough:
 716       break;
 717
 718     case MaybeFallThrough:
 719       if (HasNoReturn)
 720         EmitDiag(RBrace, CD.diag_MaybeFallThrough_HasNoReturn);
 721       else if (!ReturnsVoid)
 722         EmitDiag(RBrace, CD.diag_MaybeFallThrough_ReturnsNonVoid);
 723       break;
 724     case AlwaysFallThrough:
 725       if (HasNoReturn)
 726         EmitDiag(RBrace, CD.diag_AlwaysFallThrough_HasNoReturn);
 727       else if (!ReturnsVoid)
 728         EmitDiag(RBrace, CD.diag_AlwaysFallThrough_ReturnsNonVoid);
 729       break;
 730     case NeverFallThroughOrReturn:
 731       if (ReturnsVoid && !HasNoReturn && CD.diag_NeverFallThroughOrReturn) {
 732         if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
 733           S.Diag(LBrace, CD.diag_NeverFallThroughOrReturn) << 0 << FD;
 734         } else if (const ObjCMethodDecl *MD = dyn_cast<ObjCMethodDecl>(D)) {
 735           S.Diag(LBrace, CD.diag_NeverFallThroughOrReturn) << 1 << MD;
 736         } else {
 737           S.Diag(LBrace, CD.diag_NeverFallThroughOrReturn);
 738         }
 739       }
 740       break;
 741     case NeverFallThrough:
 742       break;
 743   }
 744 }
 745
 746 //===----------------------------------------------------------------------===//
 747 // -Wuninitialized
 748 //===----------------------------------------------------------------------===//
 749
 750 namespace {
 751 /// ContainsReference - A visitor class to search for references to
 752 /// a particular declaration (the needle) within any evaluated component of an
 753 /// expression (recursively).
 754 class ContainsReference : public ConstEvaluatedExprVisitor<ContainsReference> {
 755   bool FoundReference;
 756   const DeclRefExpr *Needle;
 757
 758 public:
 759   typedef ConstEvaluatedExprVisitor<ContainsReference> Inherited;
 760
 761   ContainsReference(ASTContext &Context, const DeclRefExpr *Needle)
 762     : Inherited(Context), FoundReference(false), Needle(Needle) {}
 763
 764   void VisitExpr(const Expr *E) {
 765     // Stop evaluating if we already have a reference.
 766     if (FoundReference)
 767       return;
 768
 769     Inherited::VisitExpr(E);
 770   }
 771
 772   void VisitDeclRefExpr(const DeclRefExpr *E) {
 773     if (E == Needle)
 774       FoundReference = true;
 775     else
 776       Inherited::VisitDeclRefExpr(E);
 777   }
 778
 779   bool doesContainReference() const { return FoundReference; }
 780 };
 781 } // anonymous namespace
 782
 783 static bool SuggestInitializationFixit(Sema &S, const VarDecl *VD) {
 784   QualType VariableTy = VD->getType().getCanonicalType();
 785   if (VariableTy->isBlockPointerType() &&
 786       !VD->hasAttr<BlocksAttr>()) {
 787     S.Diag(VD->getLocation(), diag::note_block_var_fixit_add_initialization)
 788         << VD->getDeclName()
 789         << FixItHint::CreateInsertion(VD->getLocation(), "__block ");
 790     return true;
 791   }
 792
 793   // Don't issue a fixit if there is already an initializer.
 794   if (VD->getInit())
 795     return false;
 796
 797   // Don't suggest a fixit inside macros.
 798   if (VD->getEndLoc().isMacroID())
 799     return false;
 800
 801   SourceLocation Loc = S.getLocForEndOfToken(VD->getEndLoc());
 802
 803   // Suggest possible initialization (if any).
 804   std::string Init = S.getFixItZeroInitializerForType(VariableTy, Loc);
 805   if (Init.empty())
 806     return false;
 807
 808   S.Diag(Loc, diag::note_var_fixit_add_initialization) << VD->getDeclName()
 809     << FixItHint::CreateInsertion(Loc, Init);
 810   return true;
 811 }
 812
 813 /// Create a fixit to remove an if-like statement, on the assumption that its
 814 /// condition is CondVal.
 815 static void CreateIfFixit(Sema &S, const Stmt *If, const Stmt *Then,
 816                           const Stmt *Else, bool CondVal,
 817                           FixItHint &Fixit1, FixItHint &Fixit2) {
 818   if (CondVal) {
 819     // If condition is always true, remove all but the 'then'.
 820     Fixit1 = FixItHint::CreateRemoval(
 821         CharSourceRange::getCharRange(If->getBeginLoc(), Then->getBeginLoc()));
 822     if (Else) {
 823       SourceLocation ElseKwLoc = S.getLocForEndOfToken(Then->getEndLoc());
 824       Fixit2 =
 825           FixItHint::CreateRemoval(SourceRange(ElseKwLoc, Else->getEndLoc()));
 826     }
 827   } else {
 828     // If condition is always false, remove all but the 'else'.
 829     if (Else)
 830       Fixit1 = FixItHint::CreateRemoval(CharSourceRange::getCharRange(
 831           If->getBeginLoc(), Else->getBeginLoc()));
 832     else
 833       Fixit1 = FixItHint::CreateRemoval(If->getSourceRange());
 834   }
 835 }
 836
 837 /// DiagUninitUse -- Helper function to produce a diagnostic for an
 838 /// uninitialized use of a variable.
 839 static void DiagUninitUse(Sema &S, const VarDecl *VD, const UninitUse &Use,
 840                           bool IsCapturedByBlock) {
 841   bool Diagnosed = false;
 842
 843   switch (Use.getKind()) {
 844   case UninitUse::Always:
 845     S.Diag(Use.getUser()->getBeginLoc(), diag::warn_uninit_var)
 846         << VD->getDeclName() << IsCapturedByBlock
 847         << Use.getUser()->getSourceRange();
 848     return;
 849
 850   case UninitUse::AfterDecl:
 851   case UninitUse::AfterCall:
 852     S.Diag(VD->getLocation(), diag::warn_sometimes_uninit_var)
 853       << VD->getDeclName() << IsCapturedByBlock
 854       << (Use.getKind() == UninitUse::AfterDecl ? 4 : 5)
 855       << const_cast<DeclContext*>(VD->getLexicalDeclContext())
 856       << VD->getSourceRange();
 857     S.Diag(Use.getUser()->getBeginLoc(), diag::note_uninit_var_use)
 858         << IsCapturedByBlock << Use.getUser()->getSourceRange();
 859     return;
 860
 861   case UninitUse::Maybe:
 862   case UninitUse::Sometimes:
 863     // Carry on to report sometimes-uninitialized branches, if possible,
 864     // or a 'may be used uninitialized' diagnostic otherwise.
 865     break;
 866   }
 867
 868   // Diagnose each branch which leads to a sometimes-uninitialized use.
 869   for (UninitUse::branch_iterator I = Use.branch_begin(), E = Use.branch_end();
 870        I != E; ++I) {
 871     assert(Use.getKind() == UninitUse::Sometimes);
 872
 873     const Expr *User = Use.getUser();
 874     const Stmt *Term = I->Terminator;
 875
 876     // Information used when building the diagnostic.
 877     unsigned DiagKind;
 878     StringRef Str;
 879     SourceRange Range;
 880
 881     // FixIts to suppress the diagnostic by removing the dead condition.
 882     // For all binary terminators, branch 0 is taken if the condition is true,
 883     // and branch 1 is taken if the condition is false.
 884     int RemoveDiagKind = -1;
 885     const char *FixitStr =
 886         S.getLangOpts().CPlusPlus ? (I->Output ? "true" : "false")
 887                                   : (I->Output ? "1" : "0");
 888     FixItHint Fixit1, Fixit2;
 889
 890     switch (Term ? Term->getStmtClass() : Stmt::DeclStmtClass) {
 891     default:
 892       // Don't know how to report this. Just fall back to 'may be used
 893       // uninitialized'. FIXME: Can this happen?
 894       continue;
 895
 896     // "condition is true / condition is false".
 897     case Stmt::IfStmtClass: {
 898       const IfStmt *IS = cast<IfStmt>(Term);
 899       DiagKind = 0;
 900       Str = "if";
 901       Range = IS->getCond()->getSourceRange();
 902       RemoveDiagKind = 0;
 903       CreateIfFixit(S, IS, IS->getThen(), IS->getElse(),
 904                     I->Output, Fixit1, Fixit2);
 905       break;
 906     }
 907     case Stmt::ConditionalOperatorClass: {
 908       const ConditionalOperator *CO = cast<ConditionalOperator>(Term);
 909       DiagKind = 0;
 910       Str = "?:";
 911       Range = CO->getCond()->getSourceRange();
 912       RemoveDiagKind = 0;
 913       CreateIfFixit(S, CO, CO->getTrueExpr(), CO->getFalseExpr(),
 914                     I->Output, Fixit1, Fixit2);
 915       break;
 916     }
 917     case Stmt::BinaryOperatorClass: {
 918       const BinaryOperator *BO = cast<BinaryOperator>(Term);
 919       if (!BO->isLogicalOp())
 920         continue;
 921       DiagKind = 0;
 922       Str = BO->getOpcodeStr();
 923       Range = BO->getLHS()->getSourceRange();
 924       RemoveDiagKind = 0;
 925       if ((BO->getOpcode() == BO_LAnd && I->Output) ||
 926           (BO->getOpcode() == BO_LOr && !I->Output))
 927         // true && y -> y, false || y -> y.
 928         Fixit1 = FixItHint::CreateRemoval(
 929             SourceRange(BO->getBeginLoc(), BO->getOperatorLoc()));
 930       else
 931         // false && y -> false, true || y -> true.
 932         Fixit1 = FixItHint::CreateReplacement(BO->getSourceRange(), FixitStr);
 933       break;
 934     }
 935
 936     // "loop is entered / loop is exited".
 937     case Stmt::WhileStmtClass:
 938       DiagKind = 1;
 939       Str = "while";
 940       Range = cast<WhileStmt>(Term)->getCond()->getSourceRange();
 941       RemoveDiagKind = 1;
 942       Fixit1 = FixItHint::CreateReplacement(Range, FixitStr);
 943       break;
 944     case Stmt::ForStmtClass:
 945       DiagKind = 1;
 946       Str = "for";
 947       Range = cast<ForStmt>(Term)->getCond()->getSourceRange();
 948       RemoveDiagKind = 1;
 949       if (I->Output)
 950         Fixit1 = FixItHint::CreateRemoval(Range);
 951       else
 952         Fixit1 = FixItHint::CreateReplacement(Range, FixitStr);
 953       break;
 954     case Stmt::CXXForRangeStmtClass:
 955       if (I->Output == 1) {
 956         // The use occurs if a range-based for loop's body never executes.
 957         // That may be impossible, and there's no syntactic fix for this,
 958         // so treat it as a 'may be uninitialized' case.
 959         continue;
 960       }
 961       DiagKind = 1;
 962       Str = "for";
 963       Range = cast<CXXForRangeStmt>(Term)->getRangeInit()->getSourceRange();
 964       break;
 965
 966     // "condition is true / loop is exited".
 967     case Stmt::DoStmtClass:
 968       DiagKind = 2;
 969       Str = "do";
 970       Range = cast<DoStmt>(Term)->getCond()->getSourceRange();
 971       RemoveDiagKind = 1;
 972       Fixit1 = FixItHint::CreateReplacement(Range, FixitStr);
 973       break;
 974
 975     // "switch case is taken".
 976     case Stmt::CaseStmtClass:
 977       DiagKind = 3;
 978       Str = "case";
 979       Range = cast<CaseStmt>(Term)->getLHS()->getSourceRange();
 980       break;
 981     case Stmt::DefaultStmtClass:
 982       DiagKind = 3;
 983       Str = "default";
 984       Range = cast<DefaultStmt>(Term)->getDefaultLoc();
 985       break;
 986     }
 987
 988     S.Diag(Range.getBegin(), diag::warn_sometimes_uninit_var)
 989       << VD->getDeclName() << IsCapturedByBlock << DiagKind
 990       << Str << I->Output << Range;
 991     S.Diag(User->getBeginLoc(), diag::note_uninit_var_use)
 992         << IsCapturedByBlock << User->getSourceRange();
 993     if (RemoveDiagKind != -1)
 994       S.Diag(Fixit1.RemoveRange.getBegin(), diag::note_uninit_fixit_remove_cond)
 995         << RemoveDiagKind << Str << I->Output << Fixit1 << Fixit2;
 996
 997     Diagnosed = true;
 998   }
 999
1000   if (!Diagnosed)
1001     S.Diag(Use.getUser()->getBeginLoc(), diag::warn_maybe_uninit_var)
1002         << VD->getDeclName() << IsCapturedByBlock
1003         << Use.getUser()->getSourceRange();
1004 }
1005
1006 /// Diagnose uninitialized const reference usages.
1007 static bool DiagnoseUninitializedConstRefUse(Sema &S, const VarDecl *VD,
1008                                              const UninitUse &Use) {
1009   S.Diag(Use.getUser()->getBeginLoc(), diag::warn_uninit_const_reference)
1010       << VD->getDeclName() << Use.getUser()->getSourceRange();
1011   return true;
1012 }
1013
1014 /// DiagnoseUninitializedUse -- Helper function for diagnosing uses of an
1015 /// uninitialized variable. This manages the different forms of diagnostic
1016 /// emitted for particular types of uses. Returns true if the use was diagnosed
1017 /// as a warning. If a particular use is one we omit warnings for, returns
1018 /// false.
1019 static bool DiagnoseUninitializedUse(Sema &S, const VarDecl *VD,
1020                                      const UninitUse &Use,
1021                                      bool alwaysReportSelfInit = false) {
1022   if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(Use.getUser())) {
1023     // Inspect the initializer of the variable declaration which is
1024     // being referenced prior to its initialization. We emit
1025     // specialized diagnostics for self-initialization, and we
1026     // specifically avoid warning about self references which take the
1027     // form of:
1028     //
1029     //   int x = x;
1030     //
1031     // This is used to indicate to GCC that 'x' is intentionally left
1032     // uninitialized. Proven code paths which access 'x' in
1033     // an uninitialized state after this will still warn.
1034     if (const Expr *Initializer = VD->getInit()) {
1035       if (!alwaysReportSelfInit && DRE == Initializer->IgnoreParenImpCasts())
1036         return false;
1037
1038       ContainsReference CR(S.Context, DRE);
1039       CR.Visit(Initializer);
1040       if (CR.doesContainReference()) {
1041         S.Diag(DRE->getBeginLoc(), diag::warn_uninit_self_reference_in_init)
1042             << VD->getDeclName() << VD->getLocation() << DRE->getSourceRange();
1043         return true;
1044       }
1045     }
1046
1047     DiagUninitUse(S, VD, Use, false);
1048   } else {
1049     const BlockExpr *BE = cast<BlockExpr>(Use.getUser());
1050     if (VD->getType()->isBlockPointerType() && !VD->hasAttr<BlocksAttr>())
1051       S.Diag(BE->getBeginLoc(),
1052              diag::warn_uninit_byref_blockvar_captured_by_block)
1053           << VD->getDeclName()
1054           << VD->getType().getQualifiers().hasObjCLifetime();
1055     else
1056       DiagUninitUse(S, VD, Use, true);
1057   }
1058
1059   // Report where the variable was declared when the use wasn't within
1060   // the initializer of that declaration & we didn't already suggest
1061   // an initialization fixit.
1062   if (!SuggestInitializationFixit(S, VD))
1063     S.Diag(VD->getBeginLoc(), diag::note_var_declared_here)
1064         << VD->getDeclName();
1065
1066   return true;
1067 }
1068
1069 namespace {
1070   class FallthroughMapper : public RecursiveASTVisitor<FallthroughMapper> {
1071   public:
1072     FallthroughMapper(Sema &S)
1073       : FoundSwitchStatements(false),
1074         S(S) {
1075     }
1076
1077     bool foundSwitchStatements() const { return FoundSwitchStatements; }
1078
1079     void markFallthroughVisited(const AttributedStmt *Stmt) {
1080       bool Found = FallthroughStmts.erase(Stmt);
1081       assert(Found);
1082       (void)Found;
1083     }
1084
1085     typedef llvm::SmallPtrSet<const AttributedStmt*, 8> AttrStmts;
1086
1087     const AttrStmts &getFallthroughStmts() const {
1088       return FallthroughStmts;
1089     }
1090
1091     void fillReachableBlocks(CFG *Cfg) {
1092       assert(ReachableBlocks.empty() && "ReachableBlocks already filled");
1093       std::deque<const CFGBlock *> BlockQueue;
1094
1095       ReachableBlocks.insert(&Cfg->getEntry());
1096       BlockQueue.push_back(&Cfg->getEntry());
1097       // Mark all case blocks reachable to avoid problems with switching on
1098       // constants, covered enums, etc.
1099       // These blocks can contain fall-through annotations, and we don't want to
1100       // issue a warn_fallthrough_attr_unreachable for them.
1101       for (const auto *B : *Cfg) {
1102         const Stmt *L = B->getLabel();
1103         if (L && isa<SwitchCase>(L) && ReachableBlocks.insert(B).second)
1104           BlockQueue.push_back(B);
1105       }
1106
1107       while (!BlockQueue.empty()) {
1108         const CFGBlock *P = BlockQueue.front();
1109         BlockQueue.pop_front();
1110         for (const CFGBlock *B : P->succs()) {
1111           if (B && ReachableBlocks.insert(B).second)
1112             BlockQueue.push_back(B);
1113         }
1114       }
1115     }
1116
1117     bool checkFallThroughIntoBlock(const CFGBlock &B, int &AnnotatedCnt,
1118                                    bool IsTemplateInstantiation) {
1119       assert(!ReachableBlocks.empty() && "ReachableBlocks empty");
1120
1121       int UnannotatedCnt = 0;
1122       AnnotatedCnt = 0;
1123
1124       std::deque<const CFGBlock*> BlockQueue(B.pred_begin(), B.pred_end());
1125       while (!BlockQueue.empty()) {
1126         const CFGBlock *P = BlockQueue.front();
1127         BlockQueue.pop_front();
1128         if (!P) continue;
1129
1130         const Stmt *Term = P->getTerminatorStmt();
1131         if (Term && isa<SwitchStmt>(Term))
1132           continue; // Switch statement, good.
1133
1134         const SwitchCase *SW = dyn_cast_or_null<SwitchCase>(P->getLabel());
1135         if (SW && SW->getSubStmt() == B.getLabel() && P->begin() == P->end())
1136           continue; // Previous case label has no statements, good.
1137
1138         const LabelStmt *L = dyn_cast_or_null<LabelStmt>(P->getLabel());
1139         if (L && L->getSubStmt() == B.getLabel() && P->begin() == P->end())
1140           continue; // Case label is preceded with a normal label, good.
1141
1142         if (!ReachableBlocks.count(P)) {
1143           for (const CFGElement &Elem : llvm::reverse(*P)) {
1144             if (std::optional<CFGStmt> CS = Elem.getAs<CFGStmt>()) {
1145             if (const AttributedStmt *AS = asFallThroughAttr(CS->getStmt())) {
1146               // Don't issue a warning for an unreachable fallthrough
1147               // attribute in template instantiations as it may not be
1148               // unreachable in all instantiations of the template.
1149               if (!IsTemplateInstantiation)
1150                 S.Diag(AS->getBeginLoc(),
1151                        diag::warn_unreachable_fallthrough_attr);
1152               markFallthroughVisited(AS);
1153               ++AnnotatedCnt;
1154               break;
1155             }
1156             // Don't care about other unreachable statements.
1157             }
1158           }
1159           // If there are no unreachable statements, this may be a special
1160           // case in CFG:
1161           // case X: {
1162           //    A a;  // A has a destructor.
1163           //    break;
1164           // }
1165           // // <<<< This place is represented by a 'hanging' CFG block.
1166           // case Y:
1167           continue;
1168         }
1169
1170         const Stmt *LastStmt = getLastStmt(*P);
1171         if (const AttributedStmt *AS = asFallThroughAttr(LastStmt)) {
1172           markFallthroughVisited(AS);
1173           ++AnnotatedCnt;
1174           continue; // Fallthrough annotation, good.
1175         }
1176
1177         if (!LastStmt) { // This block contains no executable statements.
1178           // Traverse its predecessors.
1179           std::copy(P->pred_begin(), P->pred_end(),
1180                     std::back_inserter(BlockQueue));
1181           continue;
1182         }
1183
1184         ++UnannotatedCnt;
1185       }
1186       return !!UnannotatedCnt;
1187     }
1188
1189     // RecursiveASTVisitor setup.
1190     bool shouldWalkTypesOfTypeLocs() const { return false; }
1191
1192     bool VisitAttributedStmt(AttributedStmt *S) {
1193       if (asFallThroughAttr(S))
1194         FallthroughStmts.insert(S);
1195       return true;
1196     }
1197
1198     bool VisitSwitchStmt(SwitchStmt *S) {
1199       FoundSwitchStatements = true;
1200       return true;
1201     }
1202
1203     // We don't want to traverse local type declarations. We analyze their
1204     // methods separately.
1205     bool TraverseDecl(Decl *D) { return true; }
1206
1207     // We analyze lambda bodies separately. Skip them here.
1208     bool TraverseLambdaExpr(LambdaExpr *LE) {
1209       // Traverse the captures, but not the body.
1210       for (const auto C : zip(LE->captures(), LE->capture_inits()))
1211         TraverseLambdaCapture(LE, &std::get<0>(C), std::get<1>(C));
1212       return true;
1213     }
1214
1215   private:
1216
1217     static const AttributedStmt *asFallThroughAttr(const Stmt *S) {
1218       if (const AttributedStmt *AS = dyn_cast_or_null<AttributedStmt>(S)) {
1219         if (hasSpecificAttr<FallThroughAttr>(AS->getAttrs()))
1220           return AS;
1221       }
1222       return nullptr;
1223     }
1224
1225     static const Stmt *getLastStmt(const CFGBlock &B) {
1226       if (const Stmt *Term = B.getTerminatorStmt())
1227         return Term;
1228       for (const CFGElement &Elem : llvm::reverse(B))
1229         if (std::optional<CFGStmt> CS = Elem.getAs<CFGStmt>())
1230           return CS->getStmt();
1231       // Workaround to detect a statement thrown out by CFGBuilder:
1232       //   case X: {} case Y:
1233       //   case X: ; case Y:
1234       if (const SwitchCase *SW = dyn_cast_or_null<SwitchCase>(B.getLabel()))
1235         if (!isa<SwitchCase>(SW->getSubStmt()))
1236           return SW->getSubStmt();
1237
1238       return nullptr;
1239     }
1240
1241     bool FoundSwitchStatements;
1242     AttrStmts FallthroughStmts;
1243     Sema &S;
1244     llvm::SmallPtrSet<const CFGBlock *, 16> ReachableBlocks;
1245   };
1246 } // anonymous namespace
1247
1248 static StringRef getFallthroughAttrSpelling(Preprocessor &PP,
1249                                             SourceLocation Loc) {
1250   TokenValue FallthroughTokens[] = {
1251     tok::l_square, tok::l_square,
1252     PP.getIdentifierInfo("fallthrough"),
1253     tok::r_square, tok::r_square
1254   };
1255
1256   TokenValue ClangFallthroughTokens[] = {
1257     tok::l_square, tok::l_square, PP.getIdentifierInfo("clang"),
1258     tok::coloncolon, PP.getIdentifierInfo("fallthrough"),
1259     tok::r_square, tok::r_square
1260   };
1261
1262   bool PreferClangAttr = !PP.getLangOpts().CPlusPlus17 && !PP.getLangOpts().C23;
1263
1264   StringRef MacroName;
1265   if (PreferClangAttr)
1266     MacroName = PP.getLastMacroWithSpelling(Loc, ClangFallthroughTokens);
1267   if (MacroName.empty())
1268     MacroName = PP.getLastMacroWithSpelling(Loc, FallthroughTokens);
1269   if (MacroName.empty() && !PreferClangAttr)
1270     MacroName = PP.getLastMacroWithSpelling(Loc, ClangFallthroughTokens);
1271   if (MacroName.empty()) {
1272     if (!PreferClangAttr)
1273       MacroName = "[[fallthrough]]";
1274     else if (PP.getLangOpts().CPlusPlus)
1275       MacroName = "[[clang::fallthrough]]";
1276     else
1277       MacroName = "__attribute__((fallthrough))";
1278   }
1279   return MacroName;
1280 }
1281
1282 static void DiagnoseSwitchLabelsFallthrough(Sema &S, AnalysisDeclContext &AC,
1283                                             bool PerFunction) {
1284   FallthroughMapper FM(S);
1285   FM.TraverseStmt(AC.getBody());
1286
1287   if (!FM.foundSwitchStatements())
1288     return;
1289
1290   if (PerFunction && FM.getFallthroughStmts().empty())
1291     return;
1292
1293   CFG *Cfg = AC.getCFG();
1294
1295   if (!Cfg)
1296     return;
1297
1298   FM.fillReachableBlocks(Cfg);
1299
1300   for (const CFGBlock *B : llvm::reverse(*Cfg)) {
1301     const Stmt *Label = B->getLabel();
1302
1303     if (!isa_and_nonnull<SwitchCase>(Label))
1304       continue;
1305
1306     int AnnotatedCnt;
1307
1308     bool IsTemplateInstantiation = false;
1309     if (const FunctionDecl *Function = dyn_cast<FunctionDecl>(AC.getDecl()))
1310       IsTemplateInstantiation = Function->isTemplateInstantiation();
1311     if (!FM.checkFallThroughIntoBlock(*B, AnnotatedCnt,
1312                                       IsTemplateInstantiation))
1313       continue;
1314
1315     S.Diag(Label->getBeginLoc(),
1316            PerFunction ? diag::warn_unannotated_fallthrough_per_function
1317                        : diag::warn_unannotated_fallthrough);
1318
1319     if (!AnnotatedCnt) {
1320       SourceLocation L = Label->getBeginLoc();
1321       if (L.isMacroID())
1322         continue;
1323
1324       const Stmt *Term = B->getTerminatorStmt();
1325       // Skip empty cases.
1326       while (B->empty() && !Term && B->succ_size() == 1) {
1327         B = *B->succ_begin();
1328         Term = B->getTerminatorStmt();
1329       }
1330       if (!(B->empty() && Term && isa<BreakStmt>(Term))) {
1331         Preprocessor &PP = S.getPreprocessor();
1332         StringRef AnnotationSpelling = getFallthroughAttrSpelling(PP, L);
1333         SmallString<64> TextToInsert(AnnotationSpelling);
1334         TextToInsert += "; ";
1335         S.Diag(L, diag::note_insert_fallthrough_fixit)
1336             << AnnotationSpelling
1337             << FixItHint::CreateInsertion(L, TextToInsert);
1338       }
1339       S.Diag(L, diag::note_insert_break_fixit)
1340           << FixItHint::CreateInsertion(L, "break; ");
1341     }
1342   }
1343
1344   for (const auto *F : FM.getFallthroughStmts())
1345     S.Diag(F->getBeginLoc(), diag::err_fallthrough_attr_invalid_placement);
1346 }
1347
1348 static bool isInLoop(const ASTContext &Ctx, const ParentMap &PM,
1349                      const Stmt *S) {
1350   assert(S);
1351
1352   do {
1353     switch (S->getStmtClass()) {
1354     case Stmt::ForStmtClass:
1355     case Stmt::WhileStmtClass:
1356     case Stmt::CXXForRangeStmtClass:
1357     case Stmt::ObjCForCollectionStmtClass:
1358       return true;
1359     case Stmt::DoStmtClass: {
1360       Expr::EvalResult Result;
1361       if (!cast<DoStmt>(S)->getCond()->EvaluateAsInt(Result, Ctx))
1362         return true;
1363       return Result.Val.getInt().getBoolValue();
1364     }
1365     default:
1366       break;
1367     }
1368   } while ((S = PM.getParent(S)));
1369
1370   return false;
1371 }
1372
1373 static void diagnoseRepeatedUseOfWeak(Sema &S,
1374                                       const sema::FunctionScopeInfo *CurFn,
1375                                       const Decl *D,
1376                                       const ParentMap &PM) {
1377   typedef sema::FunctionScopeInfo::WeakObjectProfileTy WeakObjectProfileTy;
1378   typedef sema::FunctionScopeInfo::WeakObjectUseMap WeakObjectUseMap;
1379   typedef sema::FunctionScopeInfo::WeakUseVector WeakUseVector;
1380   typedef std::pair<const Stmt *, WeakObjectUseMap::const_iterator>
1381   StmtUsesPair;
1382
1383   ASTContext &Ctx = S.getASTContext();
1384
1385   const WeakObjectUseMap &WeakMap = CurFn->getWeakObjectUses();
1386
1387   // Extract all weak objects that are referenced more than once.
1388   SmallVector<StmtUsesPair, 8> UsesByStmt;
1389   for (WeakObjectUseMap::const_iterator I = WeakMap.begin(), E = WeakMap.end();
1390        I != E; ++I) {
1391     const WeakUseVector &Uses = I->second;
1392
1393     // Find the first read of the weak object.
1394     WeakUseVector::const_iterator UI = Uses.begin(), UE = Uses.end();
1395     for ( ; UI != UE; ++UI) {
1396       if (UI->isUnsafe())
1397         break;
1398     }
1399
1400     // If there were only writes to this object, don't warn.
1401     if (UI == UE)
1402       continue;
1403
1404     // If there was only one read, followed by any number of writes, and the
1405     // read is not within a loop, don't warn. Additionally, don't warn in a
1406     // loop if the base object is a local variable -- local variables are often
1407     // changed in loops.
1408     if (UI == Uses.begin()) {
1409       WeakUseVector::const_iterator UI2 = UI;
1410       for (++UI2; UI2 != UE; ++UI2)
1411         if (UI2->isUnsafe())
1412           break;
1413
1414       if (UI2 == UE) {
1415         if (!isInLoop(Ctx, PM, UI->getUseExpr()))
1416           continue;
1417
1418         const WeakObjectProfileTy &Profile = I->first;
1419         if (!Profile.isExactProfile())
1420           continue;
1421
1422         const NamedDecl *Base = Profile.getBase();
1423         if (!Base)
1424           Base = Profile.getProperty();
1425         assert(Base && "A profile always has a base or property.");
1426
1427         if (const VarDecl *BaseVar = dyn_cast<VarDecl>(Base))
1428           if (BaseVar->hasLocalStorage() && !isa<ParmVarDecl>(Base))
1429             continue;
1430       }
1431     }
1432
1433     UsesByStmt.push_back(StmtUsesPair(UI->getUseExpr(), I));
1434   }
1435
1436   if (UsesByStmt.empty())
1437     return;
1438
1439   // Sort by first use so that we emit the warnings in a deterministic order.
1440   SourceManager &SM = S.getSourceManager();
1441   llvm::sort(UsesByStmt,
1442              [&SM](const StmtUsesPair &LHS, const StmtUsesPair &RHS) {
1443                return SM.isBeforeInTranslationUnit(LHS.first->getBeginLoc(),
1444                                                    RHS.first->getBeginLoc());
1445              });
1446
1447   // Classify the current code body 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.
1450   // FIXME: Should we use a common classification enum and the same set of
1451   // possibilities all throughout Sema?
1452   enum {
1453     Function,
1454     Method,
1455     Block,
1456     Lambda
1457   } FunctionKind;
1458
1459   if (isa<sema::BlockScopeInfo>(CurFn))
1460     FunctionKind = Block;
1461   else if (isa<sema::LambdaScopeInfo>(CurFn))
1462     FunctionKind = Lambda;
1463   else if (isa<ObjCMethodDecl>(D))
1464     FunctionKind = Method;
1465   else
1466     FunctionKind = Function;
1467
1468   // Iterate through the sorted problems and emit warnings for each.
1469   for (const auto &P : UsesByStmt) {
1470     const Stmt *FirstRead = P.first;
1471     const WeakObjectProfileTy &Key = P.second->first;
1472     const WeakUseVector &Uses = P.second->second;
1473
1474     // For complicated expressions like 'a.b.c' and 'x.b.c', WeakObjectProfileTy
1475     // may not contain enough information to determine that these are different
1476     // properties. We can only be 100% sure of a repeated use in certain cases,
1477     // and we adjust the diagnostic kind accordingly so that the less certain
1478     // case can be turned off if it is too noisy.
1479     unsigned DiagKind;
1480     if (Key.isExactProfile())
1481       DiagKind = diag::warn_arc_repeated_use_of_weak;
1482     else
1483       DiagKind = diag::warn_arc_possible_repeated_use_of_weak;
1484
1485     // Classify the weak object being accessed for better warning text.
1486     // This enum should stay in sync with the cases in
1487     // warn_arc_repeated_use_of_weak and warn_arc_possible_repeated_use_of_weak.
1488     enum {
1489       Variable,
1490       Property,
1491       ImplicitProperty,
1492       Ivar
1493     } ObjectKind;
1494
1495     const NamedDecl *KeyProp = Key.getProperty();
1496     if (isa<VarDecl>(KeyProp))
1497       ObjectKind = Variable;
1498     else if (isa<ObjCPropertyDecl>(KeyProp))
1499       ObjectKind = Property;
1500     else if (isa<ObjCMethodDecl>(KeyProp))
1501       ObjectKind = ImplicitProperty;
1502     else if (isa<ObjCIvarDecl>(KeyProp))
1503       ObjectKind = Ivar;
1504     else
1505       llvm_unreachable("Unexpected weak object kind!");
1506
1507     // Do not warn about IBOutlet weak property receivers being set to null
1508     // since they are typically only used from the main thread.
1509     if (const ObjCPropertyDecl *Prop = dyn_cast<ObjCPropertyDecl>(KeyProp))
1510       if (Prop->hasAttr<IBOutletAttr>())
1511         continue;
1512
1513     // Show the first time the object was read.
1514     S.Diag(FirstRead->getBeginLoc(), DiagKind)
1515         << int(ObjectKind) << KeyProp << int(FunctionKind)
1516         << FirstRead->getSourceRange();
1517
1518     // Print all the other accesses as notes.
1519     for (const auto &Use : Uses) {
1520       if (Use.getUseExpr() == FirstRead)
1521         continue;
1522       S.Diag(Use.getUseExpr()->getBeginLoc(),
1523              diag::note_arc_weak_also_accessed_here)
1524           << Use.getUseExpr()->getSourceRange();
1525     }
1526   }
1527 }
1528
1529 namespace clang {
1530 namespace {
1531 typedef SmallVector<PartialDiagnosticAt, 1> OptionalNotes;
1532 typedef std::pair<PartialDiagnosticAt, OptionalNotes> DelayedDiag;
1533 typedef std::list<DelayedDiag> DiagList;
1534
1535 struct SortDiagBySourceLocation {
1536   SourceManager &SM;
1537   SortDiagBySourceLocation(SourceManager &SM) : SM(SM) {}
1538
1539   bool operator()(const DelayedDiag &left, const DelayedDiag &right) {
1540     // Although this call will be slow, this is only called when outputting
1541     // multiple warnings.
1542     return SM.isBeforeInTranslationUnit(left.first.first, right.first.first);
1543   }
1544 };
1545 } // anonymous namespace
1546 } // namespace clang
1547
1548 namespace {
1549 class UninitValsDiagReporter : public UninitVariablesHandler {
1550   Sema &S;
1551   typedef SmallVector<UninitUse, 2> UsesVec;
1552   typedef llvm::PointerIntPair<UsesVec *, 1, bool> MappedType;
1553   // Prefer using MapVector to DenseMap, so that iteration order will be
1554   // the same as insertion order. This is needed to obtain a deterministic
1555   // order of diagnostics when calling flushDiagnostics().
1556   typedef llvm::MapVector<const VarDecl *, MappedType> UsesMap;
1557   UsesMap uses;
1558   UsesMap constRefUses;
1559
1560 public:
1561   UninitValsDiagReporter(Sema &S) : S(S) {}
1562   ~UninitValsDiagReporter() override { flushDiagnostics(); }
1563
1564   MappedType &getUses(UsesMap &um, const VarDecl *vd) {
1565     MappedType &V = um[vd];
1566     if (!V.getPointer())
1567       V.setPointer(new UsesVec());
1568     return V;
1569   }
1570
1571   void handleUseOfUninitVariable(const VarDecl *vd,
1572                                  const UninitUse &use) override {
1573     getUses(uses, vd).getPointer()->push_back(use);
1574   }
1575
1576   void handleConstRefUseOfUninitVariable(const VarDecl *vd,
1577                                          const UninitUse &use) override {
1578     getUses(constRefUses, vd).getPointer()->push_back(use);
1579   }
1580
1581   void handleSelfInit(const VarDecl *vd) override {
1582     getUses(uses, vd).setInt(true);
1583     getUses(constRefUses, vd).setInt(true);
1584   }
1585
1586   void flushDiagnostics() {
1587     for (const auto &P : uses) {
1588       const VarDecl *vd = P.first;
1589       const MappedType &V = P.second;
1590
1591       UsesVec *vec = V.getPointer();
1592       bool hasSelfInit = V.getInt();
1593
1594       // Specially handle the case where we have uses of an uninitialized
1595       // variable, but the root cause is an idiomatic self-init.  We want
1596       // to report the diagnostic at the self-init since that is the root cause.
1597       if (!vec->empty() && hasSelfInit && hasAlwaysUninitializedUse(vec))
1598         DiagnoseUninitializedUse(S, vd,
1599                                  UninitUse(vd->getInit()->IgnoreParenCasts(),
1600                                            /* isAlwaysUninit */ true),
1601                                  /* alwaysReportSelfInit */ true);
1602       else {
1603         // Sort the uses by their SourceLocations.  While not strictly
1604         // guaranteed to produce them in line/column order, this will provide
1605         // a stable ordering.
1606         llvm::sort(*vec, [](const UninitUse &a, const UninitUse &b) {
1607           // Prefer a more confident report over a less confident one.
1608           if (a.getKind() != b.getKind())
1609             return a.getKind() > b.getKind();
1610           return a.getUser()->getBeginLoc() < b.getUser()->getBeginLoc();
1611         });
1612
1613         for (const auto &U : *vec) {
1614           // If we have self-init, downgrade all uses to 'may be uninitialized'.
1615           UninitUse Use = hasSelfInit ? UninitUse(U.getUser(), false) : U;
1616
1617           if (DiagnoseUninitializedUse(S, vd, Use))
1618             // Skip further diagnostics for this variable. We try to warn only
1619             // on the first point at which a variable is used uninitialized.
1620             break;
1621         }
1622       }
1623
1624       // Release the uses vector.
1625       delete vec;
1626     }
1627
1628     uses.clear();
1629
1630     // Flush all const reference uses diags.
1631     for (const auto &P : constRefUses) {
1632       const VarDecl *vd = P.first;
1633       const MappedType &V = P.second;
1634
1635       UsesVec *vec = V.getPointer();
1636       bool hasSelfInit = V.getInt();
1637
1638       if (!vec->empty() && hasSelfInit && hasAlwaysUninitializedUse(vec))
1639         DiagnoseUninitializedUse(S, vd,
1640                                  UninitUse(vd->getInit()->IgnoreParenCasts(),
1641                                            /* isAlwaysUninit */ true),
1642                                  /* alwaysReportSelfInit */ true);
1643       else {
1644         for (const auto &U : *vec) {
1645           if (DiagnoseUninitializedConstRefUse(S, vd, U))
1646             break;
1647         }
1648       }
1649
1650       // Release the uses vector.
1651       delete vec;
1652     }
1653
1654     constRefUses.clear();
1655   }
1656
1657 private:
1658   static bool hasAlwaysUninitializedUse(const UsesVec* vec) {
1659     return llvm::any_of(*vec, [](const UninitUse &U) {
1660       return U.getKind() == UninitUse::Always ||
1661              U.getKind() == UninitUse::AfterCall ||
1662              U.getKind() == UninitUse::AfterDecl;
1663     });
1664   }
1665 };
1666
1667 /// Inter-procedural data for the called-once checker.
1668 class CalledOnceInterProceduralData {
1669 public:
1670   // Add the delayed warning for the given block.
1671   void addDelayedWarning(const BlockDecl *Block,
1672                          PartialDiagnosticAt &&Warning) {
1673     DelayedBlockWarnings[Block].emplace_back(std::move(Warning));
1674   }
1675   // Report all of the warnings we've gathered for the given block.
1676   void flushWarnings(const BlockDecl *Block, Sema &S) {
1677     for (const PartialDiagnosticAt &Delayed : DelayedBlockWarnings[Block])
1678       S.Diag(Delayed.first, Delayed.second);
1679
1680     discardWarnings(Block);
1681   }
1682   // Discard all of the warnings we've gathered for the given block.
1683   void discardWarnings(const BlockDecl *Block) {
1684     DelayedBlockWarnings.erase(Block);
1685   }
1686
1687 private:
1688   using DelayedDiagnostics = SmallVector<PartialDiagnosticAt, 2>;
1689   llvm::DenseMap<const BlockDecl *, DelayedDiagnostics> DelayedBlockWarnings;
1690 };
1691
1692 class CalledOnceCheckReporter : public CalledOnceCheckHandler {
1693 public:
1694   CalledOnceCheckReporter(Sema &S, CalledOnceInterProceduralData &Data)
1695       : S(S), Data(Data) {}
1696   void handleDoubleCall(const ParmVarDecl *Parameter, const Expr *Call,
1697                         const Expr *PrevCall, bool IsCompletionHandler,
1698                         bool Poised) override {
1699     auto DiagToReport = IsCompletionHandler
1700                             ? diag::warn_completion_handler_called_twice
1701                             : diag::warn_called_once_gets_called_twice;
1702     S.Diag(Call->getBeginLoc(), DiagToReport) << Parameter;
1703     S.Diag(PrevCall->getBeginLoc(), diag::note_called_once_gets_called_twice)
1704         << Poised;
1705   }
1706
1707   void handleNeverCalled(const ParmVarDecl *Parameter,
1708                          bool IsCompletionHandler) override {
1709     auto DiagToReport = IsCompletionHandler
1710                             ? diag::warn_completion_handler_never_called
1711                             : diag::warn_called_once_never_called;
1712     S.Diag(Parameter->getBeginLoc(), DiagToReport)
1713         << Parameter << /* Captured */ false;
1714   }
1715
1716   void handleNeverCalled(const ParmVarDecl *Parameter, const Decl *Function,
1717                          const Stmt *Where, NeverCalledReason Reason,
1718                          bool IsCalledDirectly,
1719                          bool IsCompletionHandler) override {
1720     auto DiagToReport = IsCompletionHandler
1721                             ? diag::warn_completion_handler_never_called_when
1722                             : diag::warn_called_once_never_called_when;
1723     PartialDiagnosticAt Warning(Where->getBeginLoc(), S.PDiag(DiagToReport)
1724                                                           << Parameter
1725                                                           << IsCalledDirectly
1726                                                           << (unsigned)Reason);
1727
1728     if (const auto *Block = dyn_cast<BlockDecl>(Function)) {
1729       // We shouldn't report these warnings on blocks immediately
1730       Data.addDelayedWarning(Block, std::move(Warning));
1731     } else {
1732       S.Diag(Warning.first, Warning.second);
1733     }
1734   }
1735
1736   void handleCapturedNeverCalled(const ParmVarDecl *Parameter,
1737                                  const Decl *Where,
1738                                  bool IsCompletionHandler) override {
1739     auto DiagToReport = IsCompletionHandler
1740                             ? diag::warn_completion_handler_never_called
1741                             : diag::warn_called_once_never_called;
1742     S.Diag(Where->getBeginLoc(), DiagToReport)
1743         << Parameter << /* Captured */ true;
1744   }
1745
1746   void
1747   handleBlockThatIsGuaranteedToBeCalledOnce(const BlockDecl *Block) override {
1748     Data.flushWarnings(Block, S);
1749   }
1750
1751   void handleBlockWithNoGuarantees(const BlockDecl *Block) override {
1752     Data.discardWarnings(Block);
1753   }
1754
1755 private:
1756   Sema &S;
1757   CalledOnceInterProceduralData &Data;
1758 };
1759
1760 constexpr unsigned CalledOnceWarnings[] = {
1761     diag::warn_called_once_never_called,
1762     diag::warn_called_once_never_called_when,
1763     diag::warn_called_once_gets_called_twice};
1764
1765 constexpr unsigned CompletionHandlerWarnings[]{
1766     diag::warn_completion_handler_never_called,
1767     diag::warn_completion_handler_never_called_when,
1768     diag::warn_completion_handler_called_twice};
1769
1770 bool shouldAnalyzeCalledOnceImpl(llvm::ArrayRef<unsigned> DiagIDs,
1771                                  const DiagnosticsEngine &Diags,
1772                                  SourceLocation At) {
1773   return llvm::any_of(DiagIDs, [&Diags, At](unsigned DiagID) {
1774     return !Diags.isIgnored(DiagID, At);
1775   });
1776 }
1777
1778 bool shouldAnalyzeCalledOnceConventions(const DiagnosticsEngine &Diags,
1779                                         SourceLocation At) {
1780   return shouldAnalyzeCalledOnceImpl(CompletionHandlerWarnings, Diags, At);
1781 }
1782
1783 bool shouldAnalyzeCalledOnceParameters(const DiagnosticsEngine &Diags,
1784                                        SourceLocation At) {
1785   return shouldAnalyzeCalledOnceImpl(CalledOnceWarnings, Diags, At) ||
1786          shouldAnalyzeCalledOnceConventions(Diags, At);
1787 }
1788 } // anonymous namespace
1789
1790 //===----------------------------------------------------------------------===//
1791 // -Wthread-safety
1792 //===----------------------------------------------------------------------===//
1793 namespace clang {
1794 namespace threadSafety {
1795 namespace {
1796 class ThreadSafetyReporter : public clang::threadSafety::ThreadSafetyHandler {
1797   Sema &S;
1798   DiagList Warnings;
1799   SourceLocation FunLocation, FunEndLocation;
1800
1801   const FunctionDecl *CurrentFunction;
1802   bool Verbose;
1803
1804   OptionalNotes getNotes() const {
1805     if (Verbose && CurrentFunction) {
1806       PartialDiagnosticAt FNote(CurrentFunction->getBody()->getBeginLoc(),
1807                                 S.PDiag(diag::note_thread_warning_in_fun)
1808                                     << CurrentFunction);
1809       return OptionalNotes(1, FNote);
1810     }
1811     return OptionalNotes();
1812   }
1813
1814   OptionalNotes getNotes(const PartialDiagnosticAt &Note) const {
1815     OptionalNotes ONS(1, Note);
1816     if (Verbose && CurrentFunction) {
1817       PartialDiagnosticAt FNote(CurrentFunction->getBody()->getBeginLoc(),
1818                                 S.PDiag(diag::note_thread_warning_in_fun)
1819                                     << CurrentFunction);
1820       ONS.push_back(std::move(FNote));
1821     }
1822     return ONS;
1823   }
1824
1825   OptionalNotes getNotes(const PartialDiagnosticAt &Note1,
1826                          const PartialDiagnosticAt &Note2) const {
1827     OptionalNotes ONS;
1828     ONS.push_back(Note1);
1829     ONS.push_back(Note2);
1830     if (Verbose && CurrentFunction) {
1831       PartialDiagnosticAt FNote(CurrentFunction->getBody()->getBeginLoc(),
1832                                 S.PDiag(diag::note_thread_warning_in_fun)
1833                                     << CurrentFunction);
1834       ONS.push_back(std::move(FNote));
1835     }
1836     return ONS;
1837   }
1838
1839   OptionalNotes makeLockedHereNote(SourceLocation LocLocked, StringRef Kind) {
1840     return LocLocked.isValid()
1841                ? getNotes(PartialDiagnosticAt(
1842                      LocLocked, S.PDiag(diag::note_locked_here) << Kind))
1843                : getNotes();
1844   }
1845
1846   OptionalNotes makeUnlockedHereNote(SourceLocation LocUnlocked,
1847                                      StringRef Kind) {
1848     return LocUnlocked.isValid()
1849                ? getNotes(PartialDiagnosticAt(
1850                      LocUnlocked, S.PDiag(diag::note_unlocked_here) << Kind))
1851                : getNotes();
1852   }
1853
1854  public:
1855   ThreadSafetyReporter(Sema &S, SourceLocation FL, SourceLocation FEL)
1856     : S(S), FunLocation(FL), FunEndLocation(FEL),
1857       CurrentFunction(nullptr), Verbose(false) {}
1858
1859   void setVerbose(bool b) { Verbose = b; }
1860
1861   /// Emit all buffered diagnostics in order of sourcelocation.
1862   /// We need to output diagnostics produced while iterating through
1863   /// the lockset in deterministic order, so this function orders diagnostics
1864   /// and outputs them.
1865   void emitDiagnostics() {
1866     Warnings.sort(SortDiagBySourceLocation(S.getSourceManager()));
1867     for (const auto &Diag : Warnings) {
1868       S.Diag(Diag.first.first, Diag.first.second);
1869       for (const auto &Note : Diag.second)
1870         S.Diag(Note.first, Note.second);
1871     }
1872   }
1873
1874   void handleInvalidLockExp(SourceLocation Loc) override {
1875     PartialDiagnosticAt Warning(Loc, S.PDiag(diag::warn_cannot_resolve_lock)
1876                                          << Loc);
1877     Warnings.emplace_back(std::move(Warning), getNotes());
1878   }
1879
1880   void handleUnmatchedUnlock(StringRef Kind, Name LockName, SourceLocation Loc,
1881                              SourceLocation LocPreviousUnlock) override {
1882     if (Loc.isInvalid())
1883       Loc = FunLocation;
1884     PartialDiagnosticAt Warning(Loc, S.PDiag(diag::warn_unlock_but_no_lock)
1885                                          << Kind << LockName);
1886     Warnings.emplace_back(std::move(Warning),
1887                           makeUnlockedHereNote(LocPreviousUnlock, Kind));
1888   }
1889
1890   void handleIncorrectUnlockKind(StringRef Kind, Name LockName,
1891                                  LockKind Expected, LockKind Received,
1892                                  SourceLocation LocLocked,
1893                                  SourceLocation LocUnlock) override {
1894     if (LocUnlock.isInvalid())
1895       LocUnlock = FunLocation;
1896     PartialDiagnosticAt Warning(
1897         LocUnlock, S.PDiag(diag::warn_unlock_kind_mismatch)
1898                        << Kind << LockName << Received << Expected);
1899     Warnings.emplace_back(std::move(Warning),
1900                           makeLockedHereNote(LocLocked, Kind));
1901   }
1902
1903   void handleDoubleLock(StringRef Kind, Name LockName, SourceLocation LocLocked,
1904                         SourceLocation LocDoubleLock) override {
1905     if (LocDoubleLock.isInvalid())
1906       LocDoubleLock = FunLocation;
1907     PartialDiagnosticAt Warning(LocDoubleLock, S.PDiag(diag::warn_double_lock)
1908                                                    << Kind << LockName);
1909     Warnings.emplace_back(std::move(Warning),
1910                           makeLockedHereNote(LocLocked, Kind));
1911   }
1912
1913   void handleMutexHeldEndOfScope(StringRef Kind, Name LockName,
1914                                  SourceLocation LocLocked,
1915                                  SourceLocation LocEndOfScope,
1916                                  LockErrorKind LEK) override {
1917     unsigned DiagID = 0;
1918     switch (LEK) {
1919       case LEK_LockedSomePredecessors:
1920         DiagID = diag::warn_lock_some_predecessors;
1921         break;
1922       case LEK_LockedSomeLoopIterations:
1923         DiagID = diag::warn_expecting_lock_held_on_loop;
1924         break;
1925       case LEK_LockedAtEndOfFunction:
1926         DiagID = diag::warn_no_unlock;
1927         break;
1928       case LEK_NotLockedAtEndOfFunction:
1929         DiagID = diag::warn_expecting_locked;
1930         break;
1931     }
1932     if (LocEndOfScope.isInvalid())
1933       LocEndOfScope = FunEndLocation;
1934
1935     PartialDiagnosticAt Warning(LocEndOfScope, S.PDiag(DiagID) << Kind
1936                                                                << LockName);
1937     Warnings.emplace_back(std::move(Warning),
1938                           makeLockedHereNote(LocLocked, Kind));
1939   }
1940
1941   void handleExclusiveAndShared(StringRef Kind, Name LockName,
1942                                 SourceLocation Loc1,
1943                                 SourceLocation Loc2) override {
1944     PartialDiagnosticAt Warning(Loc1,
1945                                 S.PDiag(diag::warn_lock_exclusive_and_shared)
1946                                     << Kind << LockName);
1947     PartialDiagnosticAt Note(Loc2, S.PDiag(diag::note_lock_exclusive_and_shared)
1948                                        << Kind << LockName);
1949     Warnings.emplace_back(std::move(Warning), getNotes(Note));
1950   }
1951
1952   void handleNoMutexHeld(const NamedDecl *D, ProtectedOperationKind POK,
1953                          AccessKind AK, SourceLocation Loc) override {
1954     assert((POK == POK_VarAccess || POK == POK_VarDereference) &&
1955            "Only works for variables");
1956     unsigned DiagID = POK == POK_VarAccess?
1957                         diag::warn_variable_requires_any_lock:
1958                         diag::warn_var_deref_requires_any_lock;
1959     PartialDiagnosticAt Warning(Loc, S.PDiag(DiagID)
1960       << D << getLockKindFromAccessKind(AK));
1961     Warnings.emplace_back(std::move(Warning), getNotes());
1962   }
1963
1964   void handleMutexNotHeld(StringRef Kind, const NamedDecl *D,
1965                           ProtectedOperationKind POK, Name LockName,
1966                           LockKind LK, SourceLocation Loc,
1967                           Name *PossibleMatch) override {
1968     unsigned DiagID = 0;
1969     if (PossibleMatch) {
1970       switch (POK) {
1971         case POK_VarAccess:
1972           DiagID = diag::warn_variable_requires_lock_precise;
1973           break;
1974         case POK_VarDereference:
1975           DiagID = diag::warn_var_deref_requires_lock_precise;
1976           break;
1977         case POK_FunctionCall:
1978           DiagID = diag::warn_fun_requires_lock_precise;
1979           break;
1980         case POK_PassByRef:
1981           DiagID = diag::warn_guarded_pass_by_reference;
1982           break;
1983         case POK_PtPassByRef:
1984           DiagID = diag::warn_pt_guarded_pass_by_reference;
1985           break;
1986         case POK_ReturnByRef:
1987           DiagID = diag::warn_guarded_return_by_reference;
1988           break;
1989         case POK_PtReturnByRef:
1990           DiagID = diag::warn_pt_guarded_return_by_reference;
1991           break;
1992       }
1993       PartialDiagnosticAt Warning(Loc, S.PDiag(DiagID) << Kind
1994                                                        << D
1995                                                        << LockName << LK);
1996       PartialDiagnosticAt Note(Loc, S.PDiag(diag::note_found_mutex_near_match)
1997                                         << *PossibleMatch);
1998       if (Verbose && POK == POK_VarAccess) {
1999         PartialDiagnosticAt VNote(D->getLocation(),
2000                                   S.PDiag(diag::note_guarded_by_declared_here)
2001                                       << D->getDeclName());
2002         Warnings.emplace_back(std::move(Warning), getNotes(Note, VNote));
2003       } else
2004         Warnings.emplace_back(std::move(Warning), getNotes(Note));
2005     } else {
2006       switch (POK) {
2007         case POK_VarAccess:
2008           DiagID = diag::warn_variable_requires_lock;
2009           break;
2010         case POK_VarDereference:
2011           DiagID = diag::warn_var_deref_requires_lock;
2012           break;
2013         case POK_FunctionCall:
2014           DiagID = diag::warn_fun_requires_lock;
2015           break;
2016         case POK_PassByRef:
2017           DiagID = diag::warn_guarded_pass_by_reference;
2018           break;
2019         case POK_PtPassByRef:
2020           DiagID = diag::warn_pt_guarded_pass_by_reference;
2021           break;
2022         case POK_ReturnByRef:
2023           DiagID = diag::warn_guarded_return_by_reference;
2024           break;
2025         case POK_PtReturnByRef:
2026           DiagID = diag::warn_pt_guarded_return_by_reference;
2027           break;
2028       }
2029       PartialDiagnosticAt Warning(Loc, S.PDiag(DiagID) << Kind
2030                                                        << D
2031                                                        << LockName << LK);
2032       if (Verbose && POK == POK_VarAccess) {
2033         PartialDiagnosticAt Note(D->getLocation(),
2034                                  S.PDiag(diag::note_guarded_by_declared_here));
2035         Warnings.emplace_back(std::move(Warning), getNotes(Note));
2036       } else
2037         Warnings.emplace_back(std::move(Warning), getNotes());
2038     }
2039   }
2040
2041   void handleNegativeNotHeld(StringRef Kind, Name LockName, Name Neg,
2042                              SourceLocation Loc) override {
2043     PartialDiagnosticAt Warning(Loc,
2044         S.PDiag(diag::warn_acquire_requires_negative_cap)
2045         << Kind << LockName << Neg);
2046     Warnings.emplace_back(std::move(Warning), getNotes());
2047   }
2048
2049   void handleNegativeNotHeld(const NamedDecl *D, Name LockName,
2050                              SourceLocation Loc) override {
2051     PartialDiagnosticAt Warning(
2052         Loc, S.PDiag(diag::warn_fun_requires_negative_cap) << D << LockName);
2053     Warnings.emplace_back(std::move(Warning), getNotes());
2054   }
2055
2056   void handleFunExcludesLock(StringRef Kind, Name FunName, Name LockName,
2057                              SourceLocation Loc) override {
2058     PartialDiagnosticAt Warning(Loc, S.PDiag(diag::warn_fun_excludes_mutex)
2059                                          << Kind << FunName << LockName);
2060     Warnings.emplace_back(std::move(Warning), getNotes());
2061   }
2062
2063   void handleLockAcquiredBefore(StringRef Kind, Name L1Name, Name L2Name,
2064                                 SourceLocation Loc) override {
2065     PartialDiagnosticAt Warning(Loc,
2066       S.PDiag(diag::warn_acquired_before) << Kind << L1Name << L2Name);
2067     Warnings.emplace_back(std::move(Warning), getNotes());
2068   }
2069
2070   void handleBeforeAfterCycle(Name L1Name, SourceLocation Loc) override {
2071     PartialDiagnosticAt Warning(Loc,
2072       S.PDiag(diag::warn_acquired_before_after_cycle) << L1Name);
2073     Warnings.emplace_back(std::move(Warning), getNotes());
2074   }
2075
2076   void enterFunction(const FunctionDecl* FD) override {
2077     CurrentFunction = FD;
2078   }
2079
2080   void leaveFunction(const FunctionDecl* FD) override {
2081     CurrentFunction = nullptr;
2082   }
2083 };
2084 } // anonymous namespace
2085 } // namespace threadSafety
2086 } // namespace clang
2087
2088 //===----------------------------------------------------------------------===//
2089 // -Wconsumed
2090 //===----------------------------------------------------------------------===//
2091
2092 namespace clang {
2093 namespace consumed {
2094 namespace {
2095 class ConsumedWarningsHandler : public ConsumedWarningsHandlerBase {
2096
2097   Sema &S;
2098   DiagList Warnings;
2099
2100 public:
2101
2102   ConsumedWarningsHandler(Sema &S) : S(S) {}
2103
2104   void emitDiagnostics() override {
2105     Warnings.sort(SortDiagBySourceLocation(S.getSourceManager()));
2106     for (const auto &Diag : Warnings) {
2107       S.Diag(Diag.first.first, Diag.first.second);
2108       for (const auto &Note : Diag.second)
2109         S.Diag(Note.first, Note.second);
2110     }
2111   }
2112
2113   void warnLoopStateMismatch(SourceLocation Loc,
2114                              StringRef VariableName) override {
2115     PartialDiagnosticAt Warning(Loc, S.PDiag(diag::warn_loop_state_mismatch) <<
2116       VariableName);
2117
2118     Warnings.emplace_back(std::move(Warning), OptionalNotes());
2119   }
2120
2121   void warnParamReturnTypestateMismatch(SourceLocation Loc,
2122                                         StringRef VariableName,
2123                                         StringRef ExpectedState,
2124                                         StringRef ObservedState) override {
2125
2126     PartialDiagnosticAt Warning(Loc, S.PDiag(
2127       diag::warn_param_return_typestate_mismatch) << VariableName <<
2128         ExpectedState << ObservedState);
2129
2130     Warnings.emplace_back(std::move(Warning), OptionalNotes());
2131   }
2132
2133   void warnParamTypestateMismatch(SourceLocation Loc, StringRef ExpectedState,
2134                                   StringRef ObservedState) override {
2135
2136     PartialDiagnosticAt Warning(Loc, S.PDiag(
2137       diag::warn_param_typestate_mismatch) << ExpectedState << ObservedState);
2138
2139     Warnings.emplace_back(std::move(Warning), OptionalNotes());
2140   }
2141
2142   void warnReturnTypestateForUnconsumableType(SourceLocation Loc,
2143                                               StringRef TypeName) override {
2144     PartialDiagnosticAt Warning(Loc, S.PDiag(
2145       diag::warn_return_typestate_for_unconsumable_type) << TypeName);
2146
2147     Warnings.emplace_back(std::move(Warning), OptionalNotes());
2148   }
2149
2150   void warnReturnTypestateMismatch(SourceLocation Loc, StringRef ExpectedState,
2151                                    StringRef ObservedState) override {
2152
2153     PartialDiagnosticAt Warning(Loc, S.PDiag(
2154       diag::warn_return_typestate_mismatch) << ExpectedState << ObservedState);
2155
2156     Warnings.emplace_back(std::move(Warning), OptionalNotes());
2157   }
2158
2159   void warnUseOfTempInInvalidState(StringRef MethodName, StringRef State,
2160                                    SourceLocation Loc) override {
2161
2162     PartialDiagnosticAt Warning(Loc, S.PDiag(
2163       diag::warn_use_of_temp_in_invalid_state) << MethodName << State);
2164
2165     Warnings.emplace_back(std::move(Warning), OptionalNotes());
2166   }
2167
2168   void warnUseInInvalidState(StringRef MethodName, StringRef VariableName,
2169                              StringRef State, SourceLocation Loc) override {
2170
2171     PartialDiagnosticAt Warning(Loc, S.PDiag(diag::warn_use_in_invalid_state) <<
2172                                 MethodName << VariableName << State);
2173
2174     Warnings.emplace_back(std::move(Warning), OptionalNotes());
2175   }
2176 };
2177 } // anonymous namespace
2178 } // namespace consumed
2179 } // namespace clang
2180
2181 //===----------------------------------------------------------------------===//
2182 // Unsafe buffer usage analysis.
2183 //===----------------------------------------------------------------------===//
2184
2185 namespace {
2186 class UnsafeBufferUsageReporter : public UnsafeBufferUsageHandler {
2187   Sema &S;
2188   bool SuggestSuggestions;  // Recommend -fsafe-buffer-usage-suggestions?
2189
2190   // Lists as a string the names of variables in `VarGroupForVD` except for `VD`
2191   // itself:
2192   std::string listVariableGroupAsString(
2193       const VarDecl *VD, const ArrayRef<const VarDecl *> &VarGroupForVD) const {
2194     if (VarGroupForVD.size() <= 1)
2195       return "";
2196
2197     std::vector<StringRef> VarNames;
2198     auto PutInQuotes = [](StringRef S) -> std::string {
2199       return "'" + S.str() + "'";
2200     };
2201
2202     for (auto *V : VarGroupForVD) {
2203       if (V == VD)
2204         continue;
2205       VarNames.push_back(V->getName());
2206     }
2207     if (VarNames.size() == 1) {
2208       return PutInQuotes(VarNames[0]);
2209     }
2210     if (VarNames.size() == 2) {
2211       return PutInQuotes(VarNames[0]) + " and " + PutInQuotes(VarNames[1]);
2212     }
2213     assert(VarGroupForVD.size() > 3);
2214     const unsigned N = VarNames.size() -
2215                        2; // need to print the last two names as "..., X, and Y"
2216     std::string AllVars = "";
2217
2218     for (unsigned I = 0; I < N; ++I)
2219       AllVars.append(PutInQuotes(VarNames[I]) + ", ");
2220     AllVars.append(PutInQuotes(VarNames[N]) + ", and " +
2221                    PutInQuotes(VarNames[N + 1]));
2222     return AllVars;
2223   }
2224
2225 public:
2226   UnsafeBufferUsageReporter(Sema &S, bool SuggestSuggestions)
2227     : S(S), SuggestSuggestions(SuggestSuggestions) {}
2228
2229   void handleUnsafeOperation(const Stmt *Operation,
2230                              bool IsRelatedToDecl) override {
2231     SourceLocation Loc;
2232     SourceRange Range;
2233     unsigned MsgParam = 0;
2234     if (const auto *ASE = dyn_cast<ArraySubscriptExpr>(Operation)) {
2235       Loc = ASE->getBase()->getExprLoc();
2236       Range = ASE->getBase()->getSourceRange();
2237       MsgParam = 2;
2238     } else if (const auto *BO = dyn_cast<BinaryOperator>(Operation)) {
2239       BinaryOperator::Opcode Op = BO->getOpcode();
2240       if (Op == BO_Add || Op == BO_AddAssign || Op == BO_Sub ||
2241           Op == BO_SubAssign) {
2242         if (BO->getRHS()->getType()->isIntegerType()) {
2243           Loc = BO->getLHS()->getExprLoc();
2244           Range = BO->getLHS()->getSourceRange();
2245         } else {
2246           Loc = BO->getRHS()->getExprLoc();
2247           Range = BO->getRHS()->getSourceRange();
2248         }
2249         MsgParam = 1;
2250       }
2251     } else if (const auto *UO = dyn_cast<UnaryOperator>(Operation)) {
2252       UnaryOperator::Opcode Op = UO->getOpcode();
2253       if (Op == UO_PreInc || Op == UO_PreDec || Op == UO_PostInc ||
2254           Op == UO_PostDec) {
2255         Loc = UO->getSubExpr()->getExprLoc();
2256         Range = UO->getSubExpr()->getSourceRange();
2257         MsgParam = 1;
2258       }
2259     } else {
2260       if (isa<CallExpr>(Operation)) {
2261         // note_unsafe_buffer_operation doesn't have this mode yet.
2262         assert(!IsRelatedToDecl && "Not implemented yet!");
2263         MsgParam = 3;
2264       }
2265       Loc = Operation->getBeginLoc();
2266       Range = Operation->getSourceRange();
2267     }
2268     if (IsRelatedToDecl) {
2269       assert(!SuggestSuggestions &&
2270              "Variables blamed for unsafe buffer usage without suggestions!");
2271       S.Diag(Loc, diag::note_unsafe_buffer_operation) << MsgParam << Range;
2272     } else {
2273       S.Diag(Loc, diag::warn_unsafe_buffer_operation) << MsgParam << Range;
2274       if (SuggestSuggestions) {
2275         S.Diag(Loc, diag::note_safe_buffer_usage_suggestions_disabled);
2276       }
2277     }
2278   }
2279
2280   void handleUnsafeVariableGroup(const VarDecl *Variable,
2281                                  const VariableGroupsManager &VarGrpMgr,
2282                                  FixItList &&Fixes, const Decl *D) override {
2283     assert(!SuggestSuggestions &&
2284            "Unsafe buffer usage fixits displayed without suggestions!");
2285     S.Diag(Variable->getLocation(), diag::warn_unsafe_buffer_variable)
2286         << Variable << (Variable->getType()->isPointerType() ? 0 : 1)
2287         << Variable->getSourceRange();
2288     if (!Fixes.empty()) {
2289       assert(isa<NamedDecl>(D) &&
2290              "Fix-its are generated only for `NamedDecl`s");
2291       const NamedDecl *ND = cast<NamedDecl>(D);
2292       bool BriefMsg = false;
2293       // If the variable group involves parameters, the diagnostic message will
2294       // NOT explain how the variables are grouped as the reason is non-trivial
2295       // and irrelavant to users' experience:
2296       const auto VarGroupForVD = VarGrpMgr.getGroupOfVar(Variable, &BriefMsg);
2297       unsigned FixItStrategy = 0; // For now we only have 'std::span' strategy
2298       const auto &FD =
2299           S.Diag(Variable->getLocation(),
2300                  BriefMsg ? diag::note_unsafe_buffer_variable_fixit_together
2301                           : diag::note_unsafe_buffer_variable_fixit_group);
2302
2303       FD << Variable << FixItStrategy;
2304       FD << listVariableGroupAsString(Variable, VarGroupForVD)
2305          << (VarGroupForVD.size() > 1) << ND;
2306       for (const auto &F : Fixes) {
2307         FD << F;
2308       }
2309     }
2310
2311 #ifndef NDEBUG
2312     if (areDebugNotesRequested())
2313       for (const DebugNote &Note: DebugNotesByVar[Variable])
2314         S.Diag(Note.first, diag::note_safe_buffer_debug_mode) << Note.second;
2315 #endif
2316   }
2317
2318   bool isSafeBufferOptOut(const SourceLocation &Loc) const override {
2319     return S.PP.isSafeBufferOptOut(S.getSourceManager(), Loc);
2320   }
2321
2322   // Returns the text representation of clang::unsafe_buffer_usage attribute.
2323   // `WSSuffix` holds customized "white-space"s, e.g., newline or whilespace
2324   // characters.
2325   std::string
2326   getUnsafeBufferUsageAttributeTextAt(SourceLocation Loc,
2327                                       StringRef WSSuffix = "") const override {
2328     Preprocessor &PP = S.getPreprocessor();
2329     TokenValue ClangUnsafeBufferUsageTokens[] = {
2330         tok::l_square,
2331         tok::l_square,
2332         PP.getIdentifierInfo("clang"),
2333         tok::coloncolon,
2334         PP.getIdentifierInfo("unsafe_buffer_usage"),
2335         tok::r_square,
2336         tok::r_square};
2337
2338     StringRef MacroName;
2339
2340     // The returned macro (it returns) is guaranteed not to be function-like:
2341     MacroName = PP.getLastMacroWithSpelling(Loc, ClangUnsafeBufferUsageTokens);
2342     if (MacroName.empty())
2343       MacroName = "[[clang::unsafe_buffer_usage]]";
2344     return MacroName.str() + WSSuffix.str();
2345   }
2346 };
2347 } // namespace
2348
2349 //===----------------------------------------------------------------------===//
2350 // AnalysisBasedWarnings - Worker object used by Sema to execute analysis-based
2351 //  warnings on a function, method, or block.
2352 //===----------------------------------------------------------------------===//
2353
2354 sema::AnalysisBasedWarnings::Policy::Policy() {
2355   enableCheckFallThrough = 1;
2356   enableCheckUnreachable = 0;
2357   enableThreadSafetyAnalysis = 0;
2358   enableConsumedAnalysis = 0;
2359 }
2360
2361 /// InterProceduralData aims to be a storage of whatever data should be passed
2362 /// between analyses of different functions.
2363 ///
2364 /// At the moment, its primary goal is to make the information gathered during
2365 /// the analysis of the blocks available during the analysis of the enclosing
2366 /// function.  This is important due to the fact that blocks are analyzed before
2367 /// the enclosed function is even parsed fully, so it is not viable to access
2368 /// anything in the outer scope while analyzing the block.  On the other hand,
2369 /// re-building CFG for blocks and re-analyzing them when we do have all the
2370 /// information (i.e. during the analysis of the enclosing function) seems to be
2371 /// ill-designed.
2372 class sema::AnalysisBasedWarnings::InterProceduralData {
2373 public:
2374   // It is important to analyze blocks within functions because it's a very
2375   // common pattern to capture completion handler parameters by blocks.
2376   CalledOnceInterProceduralData CalledOnceData;
2377 };
2378
2379 static unsigned isEnabled(DiagnosticsEngine &D, unsigned diag) {
2380   return (unsigned)!D.isIgnored(diag, SourceLocation());
2381 }
2382
2383 sema::AnalysisBasedWarnings::AnalysisBasedWarnings(Sema &s)
2384     : S(s), IPData(std::make_unique<InterProceduralData>()),
2385       NumFunctionsAnalyzed(0), NumFunctionsWithBadCFGs(0), NumCFGBlocks(0),
2386       MaxCFGBlocksPerFunction(0), NumUninitAnalysisFunctions(0),
2387       NumUninitAnalysisVariables(0), MaxUninitAnalysisVariablesPerFunction(0),
2388       NumUninitAnalysisBlockVisits(0),
2389       MaxUninitAnalysisBlockVisitsPerFunction(0) {
2390
2391   using namespace diag;
2392   DiagnosticsEngine &D = S.getDiagnostics();
2393
2394   DefaultPolicy.enableCheckUnreachable =
2395       isEnabled(D, warn_unreachable) || isEnabled(D, warn_unreachable_break) ||
2396       isEnabled(D, warn_unreachable_return) ||
2397       isEnabled(D, warn_unreachable_loop_increment);
2398
2399   DefaultPolicy.enableThreadSafetyAnalysis = isEnabled(D, warn_double_lock);
2400
2401   DefaultPolicy.enableConsumedAnalysis =
2402       isEnabled(D, warn_use_in_invalid_state);
2403 }
2404
2405 // We need this here for unique_ptr with forward declared class.
2406 sema::AnalysisBasedWarnings::~AnalysisBasedWarnings() = default;
2407
2408 static void flushDiagnostics(Sema &S, const sema::FunctionScopeInfo *fscope) {
2409   for (const auto &D : fscope->PossiblyUnreachableDiags)
2410     S.Diag(D.Loc, D.PD);
2411 }
2412
2413 // An AST Visitor that calls a callback function on each callable DEFINITION
2414 // that is NOT in a dependent context:
2415 class CallableVisitor : public RecursiveASTVisitor<CallableVisitor> {
2416 private:
2417   llvm::function_ref<void(const Decl *)> Callback;
2418
2419 public:
2420   CallableVisitor(llvm::function_ref<void(const Decl *)> Callback)
2421       : Callback(Callback) {}
2422
2423   bool VisitFunctionDecl(FunctionDecl *Node) {
2424     if (cast<DeclContext>(Node)->isDependentContext())
2425       return true; // Not to analyze dependent decl
2426     // `FunctionDecl->hasBody()` returns true if the function has a body
2427     // somewhere defined.  But we want to know if this `Node` has a body
2428     // child.  So we use `doesThisDeclarationHaveABody`:
2429     if (Node->doesThisDeclarationHaveABody())
2430       Callback(Node);
2431     return true;
2432   }
2433
2434   bool VisitBlockDecl(BlockDecl *Node) {
2435     if (cast<DeclContext>(Node)->isDependentContext())
2436       return true; // Not to analyze dependent decl
2437     Callback(Node);
2438     return true;
2439   }
2440
2441   bool VisitObjCMethodDecl(ObjCMethodDecl *Node) {
2442     if (cast<DeclContext>(Node)->isDependentContext())
2443       return true; // Not to analyze dependent decl
2444     if (Node->hasBody())
2445       Callback(Node);
2446     return true;
2447   }
2448
2449   bool VisitLambdaExpr(LambdaExpr *Node) {
2450     return VisitFunctionDecl(Node->getCallOperator());
2451   }
2452
2453   bool shouldVisitTemplateInstantiations() const { return true; }
2454   bool shouldVisitImplicitCode() const { return false; }
2455 };
2456
2457 void clang::sema::AnalysisBasedWarnings::IssueWarnings(
2458      TranslationUnitDecl *TU) {
2459   if (!TU)
2460     return; // This is unexpected, give up quietly.
2461
2462   DiagnosticsEngine &Diags = S.getDiagnostics();
2463
2464   if (S.hasUncompilableErrorOccurred() || Diags.getIgnoreAllWarnings())
2465     // exit if having uncompilable errors or ignoring all warnings:
2466     return;
2467
2468   DiagnosticOptions &DiagOpts = Diags.getDiagnosticOptions();
2469
2470   // UnsafeBufferUsage analysis settings.
2471   bool UnsafeBufferUsageCanEmitSuggestions = S.getLangOpts().CPlusPlus20;
2472   bool UnsafeBufferUsageShouldEmitSuggestions =  // Should != Can.
2473       UnsafeBufferUsageCanEmitSuggestions &&
2474       DiagOpts.ShowSafeBufferUsageSuggestions;
2475   bool UnsafeBufferUsageShouldSuggestSuggestions =
2476       UnsafeBufferUsageCanEmitSuggestions &&
2477       !DiagOpts.ShowSafeBufferUsageSuggestions;
2478   UnsafeBufferUsageReporter R(S, UnsafeBufferUsageShouldSuggestSuggestions);
2479
2480   // The Callback function that performs analyses:
2481   auto CallAnalyzers = [&](const Decl *Node) -> void {
2482     // Perform unsafe buffer usage analysis:
2483     if (!Diags.isIgnored(diag::warn_unsafe_buffer_operation,
2484                          Node->getBeginLoc()) ||
2485         !Diags.isIgnored(diag::warn_unsafe_buffer_variable,
2486                          Node->getBeginLoc())) {
2487       clang::checkUnsafeBufferUsage(Node, R,
2488                                     UnsafeBufferUsageShouldEmitSuggestions);
2489     }
2490
2491     // More analysis ...
2492   };
2493   // Emit per-function analysis-based warnings that require the whole-TU
2494   // reasoning. Check if any of them is enabled at all before scanning the AST:
2495   if (!Diags.isIgnored(diag::warn_unsafe_buffer_operation, SourceLocation()) ||
2496       !Diags.isIgnored(diag::warn_unsafe_buffer_variable, SourceLocation())) {
2497     CallableVisitor(CallAnalyzers).TraverseTranslationUnitDecl(TU);
2498   }
2499 }
2500
2501 void clang::sema::AnalysisBasedWarnings::IssueWarnings(
2502     sema::AnalysisBasedWarnings::Policy P, sema::FunctionScopeInfo *fscope,
2503     const Decl *D, QualType BlockType) {
2504
2505   // We avoid doing analysis-based warnings when there are errors for
2506   // two reasons:
2507   // (1) The CFGs often can't be constructed (if the body is invalid), so
2508   //     don't bother trying.
2509   // (2) The code already has problems; running the analysis just takes more
2510   //     time.
2511   DiagnosticsEngine &Diags = S.getDiagnostics();
2512
2513   // Do not do any analysis if we are going to just ignore them.
2514   if (Diags.getIgnoreAllWarnings() ||
2515       (Diags.getSuppressSystemWarnings() &&
2516        S.SourceMgr.isInSystemHeader(D->getLocation())))
2517     return;
2518
2519   // For code in dependent contexts, we'll do this at instantiation time.
2520   if (cast<DeclContext>(D)->isDependentContext())
2521     return;
2522
2523   if (S.hasUncompilableErrorOccurred()) {
2524     // Flush out any possibly unreachable diagnostics.
2525     flushDiagnostics(S, fscope);
2526     return;
2527   }
2528
2529   const Stmt *Body = D->getBody();
2530   assert(Body);
2531
2532   // Construct the analysis context with the specified CFG build options.
2533   AnalysisDeclContext AC(/* AnalysisDeclContextManager */ nullptr, D);
2534
2535   // Don't generate EH edges for CallExprs as we'd like to avoid the n^2
2536   // explosion for destructors that can result and the compile time hit.
2537   AC.getCFGBuildOptions().PruneTriviallyFalseEdges = true;
2538   AC.getCFGBuildOptions().AddEHEdges = false;
2539   AC.getCFGBuildOptions().AddInitializers = true;
2540   AC.getCFGBuildOptions().AddImplicitDtors = true;
2541   AC.getCFGBuildOptions().AddTemporaryDtors = true;
2542   AC.getCFGBuildOptions().AddCXXNewAllocator = false;
2543   AC.getCFGBuildOptions().AddCXXDefaultInitExprInCtors = true;
2544
2545   // Force that certain expressions appear as CFGElements in the CFG.  This
2546   // is used to speed up various analyses.
2547   // FIXME: This isn't the right factoring.  This is here for initial
2548   // prototyping, but we need a way for analyses to say what expressions they
2549   // expect to always be CFGElements and then fill in the BuildOptions
2550   // appropriately.  This is essentially a layering violation.
2551   if (P.enableCheckUnreachable || P.enableThreadSafetyAnalysis ||
2552       P.enableConsumedAnalysis) {
2553     // Unreachable code analysis and thread safety require a linearized CFG.
2554     AC.getCFGBuildOptions().setAllAlwaysAdd();
2555   }
2556   else {
2557     AC.getCFGBuildOptions()
2558       .setAlwaysAdd(Stmt::BinaryOperatorClass)
2559       .setAlwaysAdd(Stmt::CompoundAssignOperatorClass)
2560       .setAlwaysAdd(Stmt::BlockExprClass)
2561       .setAlwaysAdd(Stmt::CStyleCastExprClass)
2562       .setAlwaysAdd(Stmt::DeclRefExprClass)
2563       .setAlwaysAdd(Stmt::ImplicitCastExprClass)
2564       .setAlwaysAdd(Stmt::UnaryOperatorClass);
2565   }
2566
2567   // Install the logical handler.
2568   std::optional<LogicalErrorHandler> LEH;
2569   if (LogicalErrorHandler::hasActiveDiagnostics(Diags, D->getBeginLoc())) {
2570     LEH.emplace(S);
2571     AC.getCFGBuildOptions().Observer = &*LEH;
2572   }
2573
2574   // Emit delayed diagnostics.
2575   if (!fscope->PossiblyUnreachableDiags.empty()) {
2576     bool analyzed = false;
2577
2578     // Register the expressions with the CFGBuilder.
2579     for (const auto &D : fscope->PossiblyUnreachableDiags) {
2580       for (const Stmt *S : D.Stmts)
2581         AC.registerForcedBlockExpression(S);
2582     }
2583
2584     if (AC.getCFG()) {
2585       analyzed = true;
2586       for (const auto &D : fscope->PossiblyUnreachableDiags) {
2587         bool AllReachable = true;
2588         for (const Stmt *S : D.Stmts) {
2589           const CFGBlock *block = AC.getBlockForRegisteredExpression(S);
2590           CFGReverseBlockReachabilityAnalysis *cra =
2591               AC.getCFGReachablityAnalysis();
2592           // FIXME: We should be able to assert that block is non-null, but
2593           // the CFG analysis can skip potentially-evaluated expressions in
2594           // edge cases; see test/Sema/vla-2.c.
2595           if (block && cra) {
2596             // Can this block be reached from the entrance?
2597             if (!cra->isReachable(&AC.getCFG()->getEntry(), block)) {
2598               AllReachable = false;
2599               break;
2600             }
2601           }
2602           // If we cannot map to a basic block, assume the statement is
2603           // reachable.
2604         }
2605
2606         if (AllReachable)
2607           S.Diag(D.Loc, D.PD);
2608       }
2609     }
2610
2611     if (!analyzed)
2612       flushDiagnostics(S, fscope);
2613   }
2614
2615   // Warning: check missing 'return'
2616   if (P.enableCheckFallThrough) {
2617     const CheckFallThroughDiagnostics &CD =
2618         (isa<BlockDecl>(D)
2619              ? CheckFallThroughDiagnostics::MakeForBlock()
2620              : (isa<CXXMethodDecl>(D) &&
2621                 cast<CXXMethodDecl>(D)->getOverloadedOperator() == OO_Call &&
2622                 cast<CXXMethodDecl>(D)->getParent()->isLambda())
2623                    ? CheckFallThroughDiagnostics::MakeForLambda()
2624                    : (fscope->isCoroutine()
2625                           ? CheckFallThroughDiagnostics::MakeForCoroutine(D)
2626                           : CheckFallThroughDiagnostics::MakeForFunction(D)));
2627     CheckFallThroughForBody(S, D, Body, BlockType, CD, AC, fscope);
2628   }
2629
2630   // Warning: check for unreachable code
2631   if (P.enableCheckUnreachable) {
2632     // Only check for unreachable code on non-template instantiations.
2633     // Different template instantiations can effectively change the control-flow
2634     // and it is very difficult to prove that a snippet of code in a template
2635     // is unreachable for all instantiations.
2636     bool isTemplateInstantiation = false;
2637     if (const FunctionDecl *Function = dyn_cast<FunctionDecl>(D))
2638       isTemplateInstantiation = Function->isTemplateInstantiation();
2639     if (!isTemplateInstantiation)
2640       CheckUnreachable(S, AC);
2641   }
2642
2643   // Check for thread safety violations
2644   if (P.enableThreadSafetyAnalysis) {
2645     SourceLocation FL = AC.getDecl()->getLocation();
2646     SourceLocation FEL = AC.getDecl()->getEndLoc();
2647     threadSafety::ThreadSafetyReporter Reporter(S, FL, FEL);
2648     if (!Diags.isIgnored(diag::warn_thread_safety_beta, D->getBeginLoc()))
2649       Reporter.setIssueBetaWarnings(true);
2650     if (!Diags.isIgnored(diag::warn_thread_safety_verbose, D->getBeginLoc()))
2651       Reporter.setVerbose(true);
2652
2653     threadSafety::runThreadSafetyAnalysis(AC, Reporter,
2654                                           &S.ThreadSafetyDeclCache);
2655     Reporter.emitDiagnostics();
2656   }
2657
2658   // Check for violations of consumed properties.
2659   if (P.enableConsumedAnalysis) {
2660     consumed::ConsumedWarningsHandler WarningHandler(S);
2661     consumed::ConsumedAnalyzer Analyzer(WarningHandler);
2662     Analyzer.run(AC);
2663   }
2664
2665   if (!Diags.isIgnored(diag::warn_uninit_var, D->getBeginLoc()) ||
2666       !Diags.isIgnored(diag::warn_sometimes_uninit_var, D->getBeginLoc()) ||
2667       !Diags.isIgnored(diag::warn_maybe_uninit_var, D->getBeginLoc()) ||
2668       !Diags.isIgnored(diag::warn_uninit_const_reference, D->getBeginLoc())) {
2669     if (CFG *cfg = AC.getCFG()) {
2670       UninitValsDiagReporter reporter(S);
2671       UninitVariablesAnalysisStats stats;
2672       std::memset(&stats, 0, sizeof(UninitVariablesAnalysisStats));
2673       runUninitializedVariablesAnalysis(*cast<DeclContext>(D), *cfg, AC,
2674                                         reporter, stats);
2675
2676       if (S.CollectStats && stats.NumVariablesAnalyzed > 0) {
2677         ++NumUninitAnalysisFunctions;
2678         NumUninitAnalysisVariables += stats.NumVariablesAnalyzed;
2679         NumUninitAnalysisBlockVisits += stats.NumBlockVisits;
2680         MaxUninitAnalysisVariablesPerFunction =
2681             std::max(MaxUninitAnalysisVariablesPerFunction,
2682                      stats.NumVariablesAnalyzed);
2683         MaxUninitAnalysisBlockVisitsPerFunction =
2684             std::max(MaxUninitAnalysisBlockVisitsPerFunction,
2685                      stats.NumBlockVisits);
2686       }
2687     }
2688   }
2689
2690   // Check for violations of "called once" parameter properties.
2691   if (S.getLangOpts().ObjC && !S.getLangOpts().CPlusPlus &&
2692       shouldAnalyzeCalledOnceParameters(Diags, D->getBeginLoc())) {
2693     if (AC.getCFG()) {
2694       CalledOnceCheckReporter Reporter(S, IPData->CalledOnceData);
2695       checkCalledOnceParameters(
2696           AC, Reporter,
2697           shouldAnalyzeCalledOnceConventions(Diags, D->getBeginLoc()));
2698     }
2699   }
2700
2701   bool FallThroughDiagFull =
2702       !Diags.isIgnored(diag::warn_unannotated_fallthrough, D->getBeginLoc());
2703   bool FallThroughDiagPerFunction = !Diags.isIgnored(
2704       diag::warn_unannotated_fallthrough_per_function, D->getBeginLoc());
2705   if (FallThroughDiagFull || FallThroughDiagPerFunction ||
2706       fscope->HasFallthroughStmt) {
2707     DiagnoseSwitchLabelsFallthrough(S, AC, !FallThroughDiagFull);
2708   }
2709
2710   if (S.getLangOpts().ObjCWeak &&
2711       !Diags.isIgnored(diag::warn_arc_repeated_use_of_weak, D->getBeginLoc()))
2712     diagnoseRepeatedUseOfWeak(S, fscope, D, AC.getParentMap());
2713
2714
2715   // Check for infinite self-recursion in functions
2716   if (!Diags.isIgnored(diag::warn_infinite_recursive_function,
2717                        D->getBeginLoc())) {
2718     if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
2719       checkRecursiveFunction(S, FD, Body, AC);
2720     }
2721   }
2722
2723   // Check for throw out of non-throwing function.
2724   if (!Diags.isIgnored(diag::warn_throw_in_noexcept_func, D->getBeginLoc()))
2725     if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D))
2726       if (S.getLangOpts().CPlusPlus && !fscope->isCoroutine() && isNoexcept(FD))
2727         checkThrowInNonThrowingFunc(S, FD, AC);
2728
2729   // If none of the previous checks caused a CFG build, trigger one here
2730   // for the logical error handler.
2731   if (LogicalErrorHandler::hasActiveDiagnostics(Diags, D->getBeginLoc())) {
2732     AC.getCFG();
2733   }
2734
2735   // Collect statistics about the CFG if it was built.
2736   if (S.CollectStats && AC.isCFGBuilt()) {
2737     ++NumFunctionsAnalyzed;
2738     if (CFG *cfg = AC.getCFG()) {
2739       // If we successfully built a CFG for this context, record some more
2740       // detail information about it.
2741       NumCFGBlocks += cfg->getNumBlockIDs();
2742       MaxCFGBlocksPerFunction = std::max(MaxCFGBlocksPerFunction,
2743                                          cfg->getNumBlockIDs());
2744     } else {
2745       ++NumFunctionsWithBadCFGs;
2746     }
2747   }
2748 }
2749
2750 void clang::sema::AnalysisBasedWarnings::PrintStats() const {
2751   llvm::errs() << "\n*** Analysis Based Warnings Stats:\n";
2752
2753   unsigned NumCFGsBuilt = NumFunctionsAnalyzed - NumFunctionsWithBadCFGs;
2754   unsigned AvgCFGBlocksPerFunction =
2755       !NumCFGsBuilt ? 0 : NumCFGBlocks/NumCFGsBuilt;
2756   llvm::errs() << NumFunctionsAnalyzed << " functions analyzed ("
2757                << NumFunctionsWithBadCFGs << " w/o CFGs).\n"
2758                << "  " << NumCFGBlocks << " CFG blocks built.\n"
2759                << "  " << AvgCFGBlocksPerFunction
2760                << " average CFG blocks per function.\n"
2761                << "  " << MaxCFGBlocksPerFunction
2762                << " max CFG blocks per function.\n";
2763
2764   unsigned AvgUninitVariablesPerFunction = !NumUninitAnalysisFunctions ? 0
2765       : NumUninitAnalysisVariables/NumUninitAnalysisFunctions;
2766   unsigned AvgUninitBlockVisitsPerFunction = !NumUninitAnalysisFunctions ? 0
2767       : NumUninitAnalysisBlockVisits/NumUninitAnalysisFunctions;
2768   llvm::errs() << NumUninitAnalysisFunctions
2769                << " functions analyzed for uninitialiazed variables\n"
2770                << "  " << NumUninitAnalysisVariables << " variables analyzed.\n"
2771                << "  " << AvgUninitVariablesPerFunction
2772                << " average variables per function.\n"
2773                << "  " << MaxUninitAnalysisVariablesPerFunction
2774                << " max variables per function.\n"
2775                << "  " << NumUninitAnalysisBlockVisits << " block visits.\n"
2776                << "  " << AvgUninitBlockVisitsPerFunction
2777                << " average block visits per function.\n"
2778                << "  " << MaxUninitAnalysisBlockVisitsPerFunction
2779                << " max block visits per function.\n";
2780 }