1//=- AnalysisBasedWarnings.cpp - Sema warnings based on libAnalysis -*- C++ -*-=//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This file defines analysis_warnings::[Policy,Executor].
11// Together they are used by Sema to issue warnings based on inexpensive
12// static analysis algorithms in libAnalysis.
13//
14//===----------------------------------------------------------------------===//
15
16#include "clang/Sema/AnalysisBasedWarnings.h"
17#include "clang/AST/DeclCXX.h"
18#include "clang/AST/DeclObjC.h"
19#include "clang/AST/EvaluatedExprVisitor.h"
20#include "clang/AST/ExprCXX.h"
21#include "clang/AST/ExprObjC.h"
22#include "clang/AST/ParentMap.h"
23#include "clang/AST/RecursiveASTVisitor.h"
24#include "clang/AST/StmtCXX.h"
25#include "clang/AST/StmtObjC.h"
26#include "clang/AST/StmtVisitor.h"
27#include "clang/Analysis/Analyses/CFGReachabilityAnalysis.h"
28#include "clang/Analysis/Analyses/Consumed.h"
29#include "clang/Analysis/Analyses/ReachableCode.h"
30#include "clang/Analysis/Analyses/ThreadSafety.h"
31#include "clang/Analysis/Analyses/UninitializedValues.h"
32#include "clang/Analysis/AnalysisContext.h"
33#include "clang/Analysis/CFG.h"
34#include "clang/Analysis/CFGStmtMap.h"
35#include "clang/Basic/SourceLocation.h"
36#include "clang/Basic/SourceManager.h"
37#include "clang/Lex/Preprocessor.h"
38#include "clang/Sema/ScopeInfo.h"
39#include "clang/Sema/SemaInternal.h"
40#include "llvm/ADT/ArrayRef.h"
41#include "llvm/ADT/BitVector.h"
42#include "llvm/ADT/FoldingSet.h"
43#include "llvm/ADT/ImmutableMap.h"
44#include "llvm/ADT/MapVector.h"
45#include "llvm/ADT/PostOrderIterator.h"
46#include "llvm/ADT/SmallString.h"
47#include "llvm/ADT/SmallVector.h"
48#include "llvm/ADT/StringRef.h"
49#include "llvm/Support/Casting.h"
50#include <algorithm>
51#include <deque>
52#include <iterator>
53#include <vector>
54
55using namespace clang;
56
57//===----------------------------------------------------------------------===//
58// Unreachable code analysis.
59//===----------------------------------------------------------------------===//
60
61namespace {
62  class UnreachableCodeHandler : public reachable_code::Callback {
63    Sema &S;
64  public:
65    UnreachableCodeHandler(Sema &s) : S(s) {}
66
67    void HandleUnreachable(reachable_code::UnreachableKind UK,
68                           SourceLocation L,
69                           SourceRange SilenceableCondVal,
70                           SourceRange R1,
71                           SourceRange R2) override {
72      unsigned diag = diag::warn_unreachable;
73      switch (UK) {
74        case reachable_code::UK_Break:
75          diag = diag::warn_unreachable_break;
76          break;
77        case reachable_code::UK_Return:
78          diag = diag::warn_unreachable_return;
79          break;
80        case reachable_code::UK_Loop_Increment:
81          diag = diag::warn_unreachable_loop_increment;
82          break;
83        case reachable_code::UK_Other:
84          break;
85      }
86
87      S.Diag(L, diag) << R1 << R2;
88
89      SourceLocation Open = SilenceableCondVal.getBegin();
90      if (Open.isValid()) {
91        SourceLocation Close = SilenceableCondVal.getEnd();
92        Close = S.getLocForEndOfToken(Close);
93        if (Close.isValid()) {
94          S.Diag(Open, diag::note_unreachable_silence)
95            << FixItHint::CreateInsertion(Open, "/* DISABLES CODE */ (")
96            << FixItHint::CreateInsertion(Close, ")");
97        }
98      }
99    }
100  };
101} // anonymous namespace
102
103/// CheckUnreachable - Check for unreachable code.
104static void CheckUnreachable(Sema &S, AnalysisDeclContext &AC) {
105  // As a heuristic prune all diagnostics not in the main file.  Currently
106  // the majority of warnings in headers are false positives.  These
107  // are largely caused by configuration state, e.g. preprocessor
108  // defined code, etc.
109  //
110  // Note that this is also a performance optimization.  Analyzing
111  // headers many times can be expensive.
112  if (!S.getSourceManager().isInMainFile(AC.getDecl()->getLocStart()))
113    return;
114
115  UnreachableCodeHandler UC(S);
116  reachable_code::FindUnreachableCode(AC, S.getPreprocessor(), UC);
117}
118
119namespace {
120/// \brief Warn on logical operator errors in CFGBuilder
121class LogicalErrorHandler : public CFGCallback {
122  Sema &S;
123
124public:
125  LogicalErrorHandler(Sema &S) : CFGCallback(), S(S) {}
126
127  static bool HasMacroID(const Expr *E) {
128    if (E->getExprLoc().isMacroID())
129      return true;
130
131    // Recurse to children.
132    for (const Stmt *SubStmt : E->children())
133      if (const Expr *SubExpr = dyn_cast_or_null<Expr>(SubStmt))
134        if (HasMacroID(SubExpr))
135          return true;
136
137    return false;
138  }
139
140  void compareAlwaysTrue(const BinaryOperator *B, bool isAlwaysTrue) override {
141    if (HasMacroID(B))
142      return;
143
144    SourceRange DiagRange = B->getSourceRange();
145    S.Diag(B->getExprLoc(), diag::warn_tautological_overlap_comparison)
146        << DiagRange << isAlwaysTrue;
147  }
148
149  void compareBitwiseEquality(const BinaryOperator *B,
150                              bool isAlwaysTrue) override {
151    if (HasMacroID(B))
152      return;
153
154    SourceRange DiagRange = B->getSourceRange();
155    S.Diag(B->getExprLoc(), diag::warn_comparison_bitwise_always)
156        << DiagRange << isAlwaysTrue;
157  }
158};
159} // anonymous namespace
160
161//===----------------------------------------------------------------------===//
162// Check for infinite self-recursion in functions
163//===----------------------------------------------------------------------===//
164
165// Returns true if the function is called anywhere within the CFGBlock.
166// For member functions, the additional condition of being call from the
167// this pointer is required.
168static bool hasRecursiveCallInPath(const FunctionDecl *FD, CFGBlock &Block) {
169  // Process all the Stmt's in this block to find any calls to FD.
170  for (const auto &B : Block) {
171    if (B.getKind() != CFGElement::Statement)
172      continue;
173
174    const CallExpr *CE = dyn_cast<CallExpr>(B.getAs<CFGStmt>()->getStmt());
175    if (!CE || !CE->getCalleeDecl() ||
176        CE->getCalleeDecl()->getCanonicalDecl() != FD)
177      continue;
178
179    // Skip function calls which are qualified with a templated class.
180    if (const DeclRefExpr *DRE =
181            dyn_cast<DeclRefExpr>(CE->getCallee()->IgnoreParenImpCasts())) {
182      if (NestedNameSpecifier *NNS = DRE->getQualifier()) {
183        if (NNS->getKind() == NestedNameSpecifier::TypeSpec &&
184            isa<TemplateSpecializationType>(NNS->getAsType())) {
185          continue;
186        }
187      }
188    }
189
190    const CXXMemberCallExpr *MCE = dyn_cast<CXXMemberCallExpr>(CE);
191    if (!MCE || isa<CXXThisExpr>(MCE->getImplicitObjectArgument()) ||
192        !MCE->getMethodDecl()->isVirtual())
193      return true;
194  }
195  return false;
196}
197
198// All blocks are in one of three states.  States are ordered so that blocks
199// can only move to higher states.
200enum RecursiveState {
201  FoundNoPath,
202  FoundPath,
203  FoundPathWithNoRecursiveCall
204};
205
206// Returns true if there exists a path to the exit block and every path
207// to the exit block passes through a call to FD.
208static bool checkForRecursiveFunctionCall(const FunctionDecl *FD, CFG *cfg) {
209
210  const unsigned ExitID = cfg->getExit().getBlockID();
211
212  // Mark all nodes as FoundNoPath, then set the status of the entry block.
213  SmallVector<RecursiveState, 16> States(cfg->getNumBlockIDs(), FoundNoPath);
214  States[cfg->getEntry().getBlockID()] = FoundPathWithNoRecursiveCall;
215
216  // Make the processing stack and seed it with the entry block.
217  SmallVector<CFGBlock *, 16> Stack;
218  Stack.push_back(&cfg->getEntry());
219
220  while (!Stack.empty()) {
221    CFGBlock *CurBlock = Stack.back();
222    Stack.pop_back();
223
224    unsigned ID = CurBlock->getBlockID();
225    RecursiveState CurState = States[ID];
226
227    if (CurState == FoundPathWithNoRecursiveCall) {
228      // Found a path to the exit node without a recursive call.
229      if (ExitID == ID)
230        return false;
231
232      // Only change state if the block has a recursive call.
233      if (hasRecursiveCallInPath(FD, *CurBlock))
234        CurState = FoundPath;
235    }
236
237    // Loop over successor blocks and add them to the Stack if their state
238    // changes.
239    for (auto I = CurBlock->succ_begin(), E = CurBlock->succ_end(); I != E; ++I)
240      if (*I) {
241        unsigned next_ID = (*I)->getBlockID();
242        if (States[next_ID] < CurState) {
243          States[next_ID] = CurState;
244          Stack.push_back(*I);
245        }
246      }
247  }
248
249  // Return true if the exit node is reachable, and only reachable through
250  // a recursive call.
251  return States[ExitID] == FoundPath;
252}
253
254static void checkRecursiveFunction(Sema &S, const FunctionDecl *FD,
255                                   const Stmt *Body, AnalysisDeclContext &AC) {
256  FD = FD->getCanonicalDecl();
257
258  // Only run on non-templated functions and non-templated members of
259  // templated classes.
260  if (FD->getTemplatedKind() != FunctionDecl::TK_NonTemplate &&
261      FD->getTemplatedKind() != FunctionDecl::TK_MemberSpecialization)
262    return;
263
264  CFG *cfg = AC.getCFG();
265  if (!cfg) return;
266
267  // If the exit block is unreachable, skip processing the function.
268  if (cfg->getExit().pred_empty())
269    return;
270
271  // Emit diagnostic if a recursive function call is detected for all paths.
272  if (checkForRecursiveFunctionCall(FD, cfg))
273    S.Diag(Body->getLocStart(), diag::warn_infinite_recursive_function);
274}
275
276//===----------------------------------------------------------------------===//
277// Check for missing return value.
278//===----------------------------------------------------------------------===//
279
280enum ControlFlowKind {
281  UnknownFallThrough,
282  NeverFallThrough,
283  MaybeFallThrough,
284  AlwaysFallThrough,
285  NeverFallThroughOrReturn
286};
287
288/// CheckFallThrough - Check that we don't fall off the end of a
289/// Statement that should return a value.
290///
291/// \returns AlwaysFallThrough iff we always fall off the end of the statement,
292/// MaybeFallThrough iff we might or might not fall off the end,
293/// NeverFallThroughOrReturn iff we never fall off the end of the statement or
294/// return.  We assume NeverFallThrough iff we never fall off the end of the
295/// statement but we may return.  We assume that functions not marked noreturn
296/// will return.
297static ControlFlowKind CheckFallThrough(AnalysisDeclContext &AC) {
298  CFG *cfg = AC.getCFG();
299  if (!cfg) return UnknownFallThrough;
300
301  // The CFG leaves in dead things, and we don't want the dead code paths to
302  // confuse us, so we mark all live things first.
303  llvm::BitVector live(cfg->getNumBlockIDs());
304  unsigned count = reachable_code::ScanReachableFromBlock(&cfg->getEntry(),
305                                                          live);
306
307  bool AddEHEdges = AC.getAddEHEdges();
308  if (!AddEHEdges && count != cfg->getNumBlockIDs())
309    // When there are things remaining dead, and we didn't add EH edges
310    // from CallExprs to the catch clauses, we have to go back and
311    // mark them as live.
312    for (const auto *B : *cfg) {
313      if (!live[B->getBlockID()]) {
314        if (B->pred_begin() == B->pred_end()) {
315          if (B->getTerminator() && isa<CXXTryStmt>(B->getTerminator()))
316            // When not adding EH edges from calls, catch clauses
317            // can otherwise seem dead.  Avoid noting them as dead.
318            count += reachable_code::ScanReachableFromBlock(B, live);
319          continue;
320        }
321      }
322    }
323
324  // Now we know what is live, we check the live precessors of the exit block
325  // and look for fall through paths, being careful to ignore normal returns,
326  // and exceptional paths.
327  bool HasLiveReturn = false;
328  bool HasFakeEdge = false;
329  bool HasPlainEdge = false;
330  bool HasAbnormalEdge = false;
331
332  // Ignore default cases that aren't likely to be reachable because all
333  // enums in a switch(X) have explicit case statements.
334  CFGBlock::FilterOptions FO;
335  FO.IgnoreDefaultsWithCoveredEnums = 1;
336
337  for (CFGBlock::filtered_pred_iterator
338	 I = cfg->getExit().filtered_pred_start_end(FO); I.hasMore(); ++I) {
339    const CFGBlock& B = **I;
340    if (!live[B.getBlockID()])
341      continue;
342
343    // Skip blocks which contain an element marked as no-return. They don't
344    // represent actually viable edges into the exit block, so mark them as
345    // abnormal.
346    if (B.hasNoReturnElement()) {
347      HasAbnormalEdge = true;
348      continue;
349    }
350
351    // Destructors can appear after the 'return' in the CFG.  This is
352    // normal.  We need to look pass the destructors for the return
353    // statement (if it exists).
354    CFGBlock::const_reverse_iterator ri = B.rbegin(), re = B.rend();
355
356    for ( ; ri != re ; ++ri)
357      if (ri->getAs<CFGStmt>())
358        break;
359
360    // No more CFGElements in the block?
361    if (ri == re) {
362      if (B.getTerminator() && isa<CXXTryStmt>(B.getTerminator())) {
363        HasAbnormalEdge = true;
364        continue;
365      }
366      // A labeled empty statement, or the entry block...
367      HasPlainEdge = true;
368      continue;
369    }
370
371    CFGStmt CS = ri->castAs<CFGStmt>();
372    const Stmt *S = CS.getStmt();
373    if (isa<ReturnStmt>(S)) {
374      HasLiveReturn = true;
375      continue;
376    }
377    if (isa<ObjCAtThrowStmt>(S)) {
378      HasFakeEdge = true;
379      continue;
380    }
381    if (isa<CXXThrowExpr>(S)) {
382      HasFakeEdge = true;
383      continue;
384    }
385    if (isa<MSAsmStmt>(S)) {
386      // TODO: Verify this is correct.
387      HasFakeEdge = true;
388      HasLiveReturn = true;
389      continue;
390    }
391    if (isa<CXXTryStmt>(S)) {
392      HasAbnormalEdge = true;
393      continue;
394    }
395    if (std::find(B.succ_begin(), B.succ_end(), &cfg->getExit())
396        == B.succ_end()) {
397      HasAbnormalEdge = true;
398      continue;
399    }
400
401    HasPlainEdge = true;
402  }
403  if (!HasPlainEdge) {
404    if (HasLiveReturn)
405      return NeverFallThrough;
406    return NeverFallThroughOrReturn;
407  }
408  if (HasAbnormalEdge || HasFakeEdge || HasLiveReturn)
409    return MaybeFallThrough;
410  // This says AlwaysFallThrough for calls to functions that are not marked
411  // noreturn, that don't return.  If people would like this warning to be more
412  // accurate, such functions should be marked as noreturn.
413  return AlwaysFallThrough;
414}
415
416namespace {
417
418struct CheckFallThroughDiagnostics {
419  unsigned diag_MaybeFallThrough_HasNoReturn;
420  unsigned diag_MaybeFallThrough_ReturnsNonVoid;
421  unsigned diag_AlwaysFallThrough_HasNoReturn;
422  unsigned diag_AlwaysFallThrough_ReturnsNonVoid;
423  unsigned diag_NeverFallThroughOrReturn;
424  enum { Function, Block, Lambda } funMode;
425  SourceLocation FuncLoc;
426
427  static CheckFallThroughDiagnostics MakeForFunction(const Decl *Func) {
428    CheckFallThroughDiagnostics D;
429    D.FuncLoc = Func->getLocation();
430    D.diag_MaybeFallThrough_HasNoReturn =
431      diag::warn_falloff_noreturn_function;
432    D.diag_MaybeFallThrough_ReturnsNonVoid =
433      diag::warn_maybe_falloff_nonvoid_function;
434    D.diag_AlwaysFallThrough_HasNoReturn =
435      diag::warn_falloff_noreturn_function;
436    D.diag_AlwaysFallThrough_ReturnsNonVoid =
437      diag::warn_falloff_nonvoid_function;
438
439    // Don't suggest that virtual functions be marked "noreturn", since they
440    // might be overridden by non-noreturn functions.
441    bool isVirtualMethod = false;
442    if (const CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(Func))
443      isVirtualMethod = Method->isVirtual();
444
445    // Don't suggest that template instantiations be marked "noreturn"
446    bool isTemplateInstantiation = false;
447    if (const FunctionDecl *Function = dyn_cast<FunctionDecl>(Func))
448      isTemplateInstantiation = Function->isTemplateInstantiation();
449
450    if (!isVirtualMethod && !isTemplateInstantiation)
451      D.diag_NeverFallThroughOrReturn =
452        diag::warn_suggest_noreturn_function;
453    else
454      D.diag_NeverFallThroughOrReturn = 0;
455
456    D.funMode = Function;
457    return D;
458  }
459
460  static CheckFallThroughDiagnostics MakeForBlock() {
461    CheckFallThroughDiagnostics D;
462    D.diag_MaybeFallThrough_HasNoReturn =
463      diag::err_noreturn_block_has_return_expr;
464    D.diag_MaybeFallThrough_ReturnsNonVoid =
465      diag::err_maybe_falloff_nonvoid_block;
466    D.diag_AlwaysFallThrough_HasNoReturn =
467      diag::err_noreturn_block_has_return_expr;
468    D.diag_AlwaysFallThrough_ReturnsNonVoid =
469      diag::err_falloff_nonvoid_block;
470    D.diag_NeverFallThroughOrReturn = 0;
471    D.funMode = Block;
472    return D;
473  }
474
475  static CheckFallThroughDiagnostics MakeForLambda() {
476    CheckFallThroughDiagnostics D;
477    D.diag_MaybeFallThrough_HasNoReturn =
478      diag::err_noreturn_lambda_has_return_expr;
479    D.diag_MaybeFallThrough_ReturnsNonVoid =
480      diag::warn_maybe_falloff_nonvoid_lambda;
481    D.diag_AlwaysFallThrough_HasNoReturn =
482      diag::err_noreturn_lambda_has_return_expr;
483    D.diag_AlwaysFallThrough_ReturnsNonVoid =
484      diag::warn_falloff_nonvoid_lambda;
485    D.diag_NeverFallThroughOrReturn = 0;
486    D.funMode = Lambda;
487    return D;
488  }
489
490  bool checkDiagnostics(DiagnosticsEngine &D, bool ReturnsVoid,
491                        bool HasNoReturn) const {
492    if (funMode == Function) {
493      return (ReturnsVoid ||
494              D.isIgnored(diag::warn_maybe_falloff_nonvoid_function,
495                          FuncLoc)) &&
496             (!HasNoReturn ||
497              D.isIgnored(diag::warn_noreturn_function_has_return_expr,
498                          FuncLoc)) &&
499             (!ReturnsVoid ||
500              D.isIgnored(diag::warn_suggest_noreturn_block, FuncLoc));
501    }
502
503    // For blocks / lambdas.
504    return ReturnsVoid && !HasNoReturn;
505  }
506};
507
508} // anonymous namespace
509
510/// CheckFallThroughForFunctionDef - Check that we don't fall off the end of a
511/// function that should return a value.  Check that we don't fall off the end
512/// of a noreturn function.  We assume that functions and blocks not marked
513/// noreturn will return.
514static void CheckFallThroughForBody(Sema &S, const Decl *D, const Stmt *Body,
515                                    const BlockExpr *blkExpr,
516                                    const CheckFallThroughDiagnostics& CD,
517                                    AnalysisDeclContext &AC) {
518
519  bool ReturnsVoid = false;
520  bool HasNoReturn = false;
521
522  if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
523    ReturnsVoid = FD->getReturnType()->isVoidType();
524    HasNoReturn = FD->isNoReturn();
525  }
526  else if (const ObjCMethodDecl *MD = dyn_cast<ObjCMethodDecl>(D)) {
527    ReturnsVoid = MD->getReturnType()->isVoidType();
528    HasNoReturn = MD->hasAttr<NoReturnAttr>();
529  }
530  else if (isa<BlockDecl>(D)) {
531    QualType BlockTy = blkExpr->getType();
532    if (const FunctionType *FT =
533          BlockTy->getPointeeType()->getAs<FunctionType>()) {
534      if (FT->getReturnType()->isVoidType())
535        ReturnsVoid = true;
536      if (FT->getNoReturnAttr())
537        HasNoReturn = true;
538    }
539  }
540
541  DiagnosticsEngine &Diags = S.getDiagnostics();
542
543  // Short circuit for compilation speed.
544  if (CD.checkDiagnostics(Diags, ReturnsVoid, HasNoReturn))
545      return;
546
547  SourceLocation LBrace = Body->getLocStart(), RBrace = Body->getLocEnd();
548  // Either in a function body compound statement, or a function-try-block.
549  switch (CheckFallThrough(AC)) {
550    case UnknownFallThrough:
551      break;
552
553    case MaybeFallThrough:
554      if (HasNoReturn)
555        S.Diag(RBrace, CD.diag_MaybeFallThrough_HasNoReturn);
556      else if (!ReturnsVoid)
557        S.Diag(RBrace, CD.diag_MaybeFallThrough_ReturnsNonVoid);
558      break;
559    case AlwaysFallThrough:
560      if (HasNoReturn)
561        S.Diag(RBrace, CD.diag_AlwaysFallThrough_HasNoReturn);
562      else if (!ReturnsVoid)
563        S.Diag(RBrace, CD.diag_AlwaysFallThrough_ReturnsNonVoid);
564      break;
565    case NeverFallThroughOrReturn:
566      if (ReturnsVoid && !HasNoReturn && CD.diag_NeverFallThroughOrReturn) {
567        if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
568          S.Diag(LBrace, CD.diag_NeverFallThroughOrReturn) << 0 << FD;
569        } else if (const ObjCMethodDecl *MD = dyn_cast<ObjCMethodDecl>(D)) {
570          S.Diag(LBrace, CD.diag_NeverFallThroughOrReturn) << 1 << MD;
571        } else {
572          S.Diag(LBrace, CD.diag_NeverFallThroughOrReturn);
573        }
574      }
575      break;
576    case NeverFallThrough:
577      break;
578  }
579}
580
581//===----------------------------------------------------------------------===//
582// -Wuninitialized
583//===----------------------------------------------------------------------===//
584
585namespace {
586/// ContainsReference - A visitor class to search for references to
587/// a particular declaration (the needle) within any evaluated component of an
588/// expression (recursively).
589class ContainsReference : public ConstEvaluatedExprVisitor<ContainsReference> {
590  bool FoundReference;
591  const DeclRefExpr *Needle;
592
593public:
594  typedef ConstEvaluatedExprVisitor<ContainsReference> Inherited;
595
596  ContainsReference(ASTContext &Context, const DeclRefExpr *Needle)
597    : Inherited(Context), FoundReference(false), Needle(Needle) {}
598
599  void VisitExpr(const Expr *E) {
600    // Stop evaluating if we already have a reference.
601    if (FoundReference)
602      return;
603
604    Inherited::VisitExpr(E);
605  }
606
607  void VisitDeclRefExpr(const DeclRefExpr *E) {
608    if (E == Needle)
609      FoundReference = true;
610    else
611      Inherited::VisitDeclRefExpr(E);
612  }
613
614  bool doesContainReference() const { return FoundReference; }
615};
616} // anonymous namespace
617
618static bool SuggestInitializationFixit(Sema &S, const VarDecl *VD) {
619  QualType VariableTy = VD->getType().getCanonicalType();
620  if (VariableTy->isBlockPointerType() &&
621      !VD->hasAttr<BlocksAttr>()) {
622    S.Diag(VD->getLocation(), diag::note_block_var_fixit_add_initialization)
623        << VD->getDeclName()
624        << FixItHint::CreateInsertion(VD->getLocation(), "__block ");
625    return true;
626  }
627
628  // Don't issue a fixit if there is already an initializer.
629  if (VD->getInit())
630    return false;
631
632  // Don't suggest a fixit inside macros.
633  if (VD->getLocEnd().isMacroID())
634    return false;
635
636  SourceLocation Loc = S.getLocForEndOfToken(VD->getLocEnd());
637
638  // Suggest possible initialization (if any).
639  std::string Init = S.getFixItZeroInitializerForType(VariableTy, Loc);
640  if (Init.empty())
641    return false;
642
643  S.Diag(Loc, diag::note_var_fixit_add_initialization) << VD->getDeclName()
644    << FixItHint::CreateInsertion(Loc, Init);
645  return true;
646}
647
648/// Create a fixit to remove an if-like statement, on the assumption that its
649/// condition is CondVal.
650static void CreateIfFixit(Sema &S, const Stmt *If, const Stmt *Then,
651                          const Stmt *Else, bool CondVal,
652                          FixItHint &Fixit1, FixItHint &Fixit2) {
653  if (CondVal) {
654    // If condition is always true, remove all but the 'then'.
655    Fixit1 = FixItHint::CreateRemoval(
656        CharSourceRange::getCharRange(If->getLocStart(),
657                                      Then->getLocStart()));
658    if (Else) {
659      SourceLocation ElseKwLoc = S.getLocForEndOfToken(Then->getLocEnd());
660      Fixit2 = FixItHint::CreateRemoval(
661          SourceRange(ElseKwLoc, Else->getLocEnd()));
662    }
663  } else {
664    // If condition is always false, remove all but the 'else'.
665    if (Else)
666      Fixit1 = FixItHint::CreateRemoval(
667          CharSourceRange::getCharRange(If->getLocStart(),
668                                        Else->getLocStart()));
669    else
670      Fixit1 = FixItHint::CreateRemoval(If->getSourceRange());
671  }
672}
673
674/// DiagUninitUse -- Helper function to produce a diagnostic for an
675/// uninitialized use of a variable.
676static void DiagUninitUse(Sema &S, const VarDecl *VD, const UninitUse &Use,
677                          bool IsCapturedByBlock) {
678  bool Diagnosed = false;
679
680  switch (Use.getKind()) {
681  case UninitUse::Always:
682    S.Diag(Use.getUser()->getLocStart(), diag::warn_uninit_var)
683        << VD->getDeclName() << IsCapturedByBlock
684        << Use.getUser()->getSourceRange();
685    return;
686
687  case UninitUse::AfterDecl:
688  case UninitUse::AfterCall:
689    S.Diag(VD->getLocation(), diag::warn_sometimes_uninit_var)
690      << VD->getDeclName() << IsCapturedByBlock
691      << (Use.getKind() == UninitUse::AfterDecl ? 4 : 5)
692      << const_cast<DeclContext*>(VD->getLexicalDeclContext())
693      << VD->getSourceRange();
694    S.Diag(Use.getUser()->getLocStart(), diag::note_uninit_var_use)
695      << IsCapturedByBlock << Use.getUser()->getSourceRange();
696    return;
697
698  case UninitUse::Maybe:
699  case UninitUse::Sometimes:
700    // Carry on to report sometimes-uninitialized branches, if possible,
701    // or a 'may be used uninitialized' diagnostic otherwise.
702    break;
703  }
704
705  // Diagnose each branch which leads to a sometimes-uninitialized use.
706  for (UninitUse::branch_iterator I = Use.branch_begin(), E = Use.branch_end();
707       I != E; ++I) {
708    assert(Use.getKind() == UninitUse::Sometimes);
709
710    const Expr *User = Use.getUser();
711    const Stmt *Term = I->Terminator;
712
713    // Information used when building the diagnostic.
714    unsigned DiagKind;
715    StringRef Str;
716    SourceRange Range;
717
718    // FixIts to suppress the diagnostic by removing the dead condition.
719    // For all binary terminators, branch 0 is taken if the condition is true,
720    // and branch 1 is taken if the condition is false.
721    int RemoveDiagKind = -1;
722    const char *FixitStr =
723        S.getLangOpts().CPlusPlus ? (I->Output ? "true" : "false")
724                                  : (I->Output ? "1" : "0");
725    FixItHint Fixit1, Fixit2;
726
727    switch (Term ? Term->getStmtClass() : Stmt::DeclStmtClass) {
728    default:
729      // Don't know how to report this. Just fall back to 'may be used
730      // uninitialized'. FIXME: Can this happen?
731      continue;
732
733    // "condition is true / condition is false".
734    case Stmt::IfStmtClass: {
735      const IfStmt *IS = cast<IfStmt>(Term);
736      DiagKind = 0;
737      Str = "if";
738      Range = IS->getCond()->getSourceRange();
739      RemoveDiagKind = 0;
740      CreateIfFixit(S, IS, IS->getThen(), IS->getElse(),
741                    I->Output, Fixit1, Fixit2);
742      break;
743    }
744    case Stmt::ConditionalOperatorClass: {
745      const ConditionalOperator *CO = cast<ConditionalOperator>(Term);
746      DiagKind = 0;
747      Str = "?:";
748      Range = CO->getCond()->getSourceRange();
749      RemoveDiagKind = 0;
750      CreateIfFixit(S, CO, CO->getTrueExpr(), CO->getFalseExpr(),
751                    I->Output, Fixit1, Fixit2);
752      break;
753    }
754    case Stmt::BinaryOperatorClass: {
755      const BinaryOperator *BO = cast<BinaryOperator>(Term);
756      if (!BO->isLogicalOp())
757        continue;
758      DiagKind = 0;
759      Str = BO->getOpcodeStr();
760      Range = BO->getLHS()->getSourceRange();
761      RemoveDiagKind = 0;
762      if ((BO->getOpcode() == BO_LAnd && I->Output) ||
763          (BO->getOpcode() == BO_LOr && !I->Output))
764        // true && y -> y, false || y -> y.
765        Fixit1 = FixItHint::CreateRemoval(SourceRange(BO->getLocStart(),
766                                                      BO->getOperatorLoc()));
767      else
768        // false && y -> false, true || y -> true.
769        Fixit1 = FixItHint::CreateReplacement(BO->getSourceRange(), FixitStr);
770      break;
771    }
772
773    // "loop is entered / loop is exited".
774    case Stmt::WhileStmtClass:
775      DiagKind = 1;
776      Str = "while";
777      Range = cast<WhileStmt>(Term)->getCond()->getSourceRange();
778      RemoveDiagKind = 1;
779      Fixit1 = FixItHint::CreateReplacement(Range, FixitStr);
780      break;
781    case Stmt::ForStmtClass:
782      DiagKind = 1;
783      Str = "for";
784      Range = cast<ForStmt>(Term)->getCond()->getSourceRange();
785      RemoveDiagKind = 1;
786      if (I->Output)
787        Fixit1 = FixItHint::CreateRemoval(Range);
788      else
789        Fixit1 = FixItHint::CreateReplacement(Range, FixitStr);
790      break;
791    case Stmt::CXXForRangeStmtClass:
792      if (I->Output == 1) {
793        // The use occurs if a range-based for loop's body never executes.
794        // That may be impossible, and there's no syntactic fix for this,
795        // so treat it as a 'may be uninitialized' case.
796        continue;
797      }
798      DiagKind = 1;
799      Str = "for";
800      Range = cast<CXXForRangeStmt>(Term)->getRangeInit()->getSourceRange();
801      break;
802
803    // "condition is true / loop is exited".
804    case Stmt::DoStmtClass:
805      DiagKind = 2;
806      Str = "do";
807      Range = cast<DoStmt>(Term)->getCond()->getSourceRange();
808      RemoveDiagKind = 1;
809      Fixit1 = FixItHint::CreateReplacement(Range, FixitStr);
810      break;
811
812    // "switch case is taken".
813    case Stmt::CaseStmtClass:
814      DiagKind = 3;
815      Str = "case";
816      Range = cast<CaseStmt>(Term)->getLHS()->getSourceRange();
817      break;
818    case Stmt::DefaultStmtClass:
819      DiagKind = 3;
820      Str = "default";
821      Range = cast<DefaultStmt>(Term)->getDefaultLoc();
822      break;
823    }
824
825    S.Diag(Range.getBegin(), diag::warn_sometimes_uninit_var)
826      << VD->getDeclName() << IsCapturedByBlock << DiagKind
827      << Str << I->Output << Range;
828    S.Diag(User->getLocStart(), diag::note_uninit_var_use)
829      << IsCapturedByBlock << User->getSourceRange();
830    if (RemoveDiagKind != -1)
831      S.Diag(Fixit1.RemoveRange.getBegin(), diag::note_uninit_fixit_remove_cond)
832        << RemoveDiagKind << Str << I->Output << Fixit1 << Fixit2;
833
834    Diagnosed = true;
835  }
836
837  if (!Diagnosed)
838    S.Diag(Use.getUser()->getLocStart(), diag::warn_maybe_uninit_var)
839        << VD->getDeclName() << IsCapturedByBlock
840        << Use.getUser()->getSourceRange();
841}
842
843/// DiagnoseUninitializedUse -- Helper function for diagnosing uses of an
844/// uninitialized variable. This manages the different forms of diagnostic
845/// emitted for particular types of uses. Returns true if the use was diagnosed
846/// as a warning. If a particular use is one we omit warnings for, returns
847/// false.
848static bool DiagnoseUninitializedUse(Sema &S, const VarDecl *VD,
849                                     const UninitUse &Use,
850                                     bool alwaysReportSelfInit = false) {
851  if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(Use.getUser())) {
852    // Inspect the initializer of the variable declaration which is
853    // being referenced prior to its initialization. We emit
854    // specialized diagnostics for self-initialization, and we
855    // specifically avoid warning about self references which take the
856    // form of:
857    //
858    //   int x = x;
859    //
860    // This is used to indicate to GCC that 'x' is intentionally left
861    // uninitialized. Proven code paths which access 'x' in
862    // an uninitialized state after this will still warn.
863    if (const Expr *Initializer = VD->getInit()) {
864      if (!alwaysReportSelfInit && DRE == Initializer->IgnoreParenImpCasts())
865        return false;
866
867      ContainsReference CR(S.Context, DRE);
868      CR.Visit(Initializer);
869      if (CR.doesContainReference()) {
870        S.Diag(DRE->getLocStart(),
871               diag::warn_uninit_self_reference_in_init)
872          << VD->getDeclName() << VD->getLocation() << DRE->getSourceRange();
873        return true;
874      }
875    }
876
877    DiagUninitUse(S, VD, Use, false);
878  } else {
879    const BlockExpr *BE = cast<BlockExpr>(Use.getUser());
880    if (VD->getType()->isBlockPointerType() && !VD->hasAttr<BlocksAttr>())
881      S.Diag(BE->getLocStart(),
882             diag::warn_uninit_byref_blockvar_captured_by_block)
883        << VD->getDeclName();
884    else
885      DiagUninitUse(S, VD, Use, true);
886  }
887
888  // Report where the variable was declared when the use wasn't within
889  // the initializer of that declaration & we didn't already suggest
890  // an initialization fixit.
891  if (!SuggestInitializationFixit(S, VD))
892    S.Diag(VD->getLocStart(), diag::note_var_declared_here)
893      << VD->getDeclName();
894
895  return true;
896}
897
898namespace {
899  class FallthroughMapper : public RecursiveASTVisitor<FallthroughMapper> {
900  public:
901    FallthroughMapper(Sema &S)
902      : FoundSwitchStatements(false),
903        S(S) {
904    }
905
906    bool foundSwitchStatements() const { return FoundSwitchStatements; }
907
908    void markFallthroughVisited(const AttributedStmt *Stmt) {
909      bool Found = FallthroughStmts.erase(Stmt);
910      assert(Found);
911      (void)Found;
912    }
913
914    typedef llvm::SmallPtrSet<const AttributedStmt*, 8> AttrStmts;
915
916    const AttrStmts &getFallthroughStmts() const {
917      return FallthroughStmts;
918    }
919
920    void fillReachableBlocks(CFG *Cfg) {
921      assert(ReachableBlocks.empty() && "ReachableBlocks already filled");
922      std::deque<const CFGBlock *> BlockQueue;
923
924      ReachableBlocks.insert(&Cfg->getEntry());
925      BlockQueue.push_back(&Cfg->getEntry());
926      // Mark all case blocks reachable to avoid problems with switching on
927      // constants, covered enums, etc.
928      // These blocks can contain fall-through annotations, and we don't want to
929      // issue a warn_fallthrough_attr_unreachable for them.
930      for (const auto *B : *Cfg) {
931        const Stmt *L = B->getLabel();
932        if (L && isa<SwitchCase>(L) && ReachableBlocks.insert(B).second)
933          BlockQueue.push_back(B);
934      }
935
936      while (!BlockQueue.empty()) {
937        const CFGBlock *P = BlockQueue.front();
938        BlockQueue.pop_front();
939        for (CFGBlock::const_succ_iterator I = P->succ_begin(),
940                                           E = P->succ_end();
941             I != E; ++I) {
942          if (*I && ReachableBlocks.insert(*I).second)
943            BlockQueue.push_back(*I);
944        }
945      }
946    }
947
948    bool checkFallThroughIntoBlock(const CFGBlock &B, int &AnnotatedCnt) {
949      assert(!ReachableBlocks.empty() && "ReachableBlocks empty");
950
951      int UnannotatedCnt = 0;
952      AnnotatedCnt = 0;
953
954      std::deque<const CFGBlock*> BlockQueue(B.pred_begin(), B.pred_end());
955      while (!BlockQueue.empty()) {
956        const CFGBlock *P = BlockQueue.front();
957        BlockQueue.pop_front();
958        if (!P) continue;
959
960        const Stmt *Term = P->getTerminator();
961        if (Term && isa<SwitchStmt>(Term))
962          continue; // Switch statement, good.
963
964        const SwitchCase *SW = dyn_cast_or_null<SwitchCase>(P->getLabel());
965        if (SW && SW->getSubStmt() == B.getLabel() && P->begin() == P->end())
966          continue; // Previous case label has no statements, good.
967
968        const LabelStmt *L = dyn_cast_or_null<LabelStmt>(P->getLabel());
969        if (L && L->getSubStmt() == B.getLabel() && P->begin() == P->end())
970          continue; // Case label is preceded with a normal label, good.
971
972        if (!ReachableBlocks.count(P)) {
973          for (CFGBlock::const_reverse_iterator ElemIt = P->rbegin(),
974                                                ElemEnd = P->rend();
975               ElemIt != ElemEnd; ++ElemIt) {
976            if (Optional<CFGStmt> CS = ElemIt->getAs<CFGStmt>()) {
977              if (const AttributedStmt *AS = asFallThroughAttr(CS->getStmt())) {
978                S.Diag(AS->getLocStart(),
979                       diag::warn_fallthrough_attr_unreachable);
980                markFallthroughVisited(AS);
981                ++AnnotatedCnt;
982                break;
983              }
984              // Don't care about other unreachable statements.
985            }
986          }
987          // If there are no unreachable statements, this may be a special
988          // case in CFG:
989          // case X: {
990          //    A a;  // A has a destructor.
991          //    break;
992          // }
993          // // <<<< This place is represented by a 'hanging' CFG block.
994          // case Y:
995          continue;
996        }
997
998        const Stmt *LastStmt = getLastStmt(*P);
999        if (const AttributedStmt *AS = asFallThroughAttr(LastStmt)) {
1000          markFallthroughVisited(AS);
1001          ++AnnotatedCnt;
1002          continue; // Fallthrough annotation, good.
1003        }
1004
1005        if (!LastStmt) { // This block contains no executable statements.
1006          // Traverse its predecessors.
1007          std::copy(P->pred_begin(), P->pred_end(),
1008                    std::back_inserter(BlockQueue));
1009          continue;
1010        }
1011
1012        ++UnannotatedCnt;
1013      }
1014      return !!UnannotatedCnt;
1015    }
1016
1017    // RecursiveASTVisitor setup.
1018    bool shouldWalkTypesOfTypeLocs() const { return false; }
1019
1020    bool VisitAttributedStmt(AttributedStmt *S) {
1021      if (asFallThroughAttr(S))
1022        FallthroughStmts.insert(S);
1023      return true;
1024    }
1025
1026    bool VisitSwitchStmt(SwitchStmt *S) {
1027      FoundSwitchStatements = true;
1028      return true;
1029    }
1030
1031    // We don't want to traverse local type declarations. We analyze their
1032    // methods separately.
1033    bool TraverseDecl(Decl *D) { return true; }
1034
1035    // We analyze lambda bodies separately. Skip them here.
1036    bool TraverseLambdaBody(LambdaExpr *LE) { return true; }
1037
1038  private:
1039
1040    static const AttributedStmt *asFallThroughAttr(const Stmt *S) {
1041      if (const AttributedStmt *AS = dyn_cast_or_null<AttributedStmt>(S)) {
1042        if (hasSpecificAttr<FallThroughAttr>(AS->getAttrs()))
1043          return AS;
1044      }
1045      return nullptr;
1046    }
1047
1048    static const Stmt *getLastStmt(const CFGBlock &B) {
1049      if (const Stmt *Term = B.getTerminator())
1050        return Term;
1051      for (CFGBlock::const_reverse_iterator ElemIt = B.rbegin(),
1052                                            ElemEnd = B.rend();
1053                                            ElemIt != ElemEnd; ++ElemIt) {
1054        if (Optional<CFGStmt> CS = ElemIt->getAs<CFGStmt>())
1055          return CS->getStmt();
1056      }
1057      // Workaround to detect a statement thrown out by CFGBuilder:
1058      //   case X: {} case Y:
1059      //   case X: ; case Y:
1060      if (const SwitchCase *SW = dyn_cast_or_null<SwitchCase>(B.getLabel()))
1061        if (!isa<SwitchCase>(SW->getSubStmt()))
1062          return SW->getSubStmt();
1063
1064      return nullptr;
1065    }
1066
1067    bool FoundSwitchStatements;
1068    AttrStmts FallthroughStmts;
1069    Sema &S;
1070    llvm::SmallPtrSet<const CFGBlock *, 16> ReachableBlocks;
1071  };
1072} // anonymous namespace
1073
1074static StringRef getFallthroughAttrSpelling(Preprocessor &PP,
1075                                            SourceLocation Loc) {
1076  TokenValue FallthroughTokens[] = {
1077    tok::l_square, tok::l_square,
1078    PP.getIdentifierInfo("fallthrough"),
1079    tok::r_square, tok::r_square
1080  };
1081
1082  TokenValue ClangFallthroughTokens[] = {
1083    tok::l_square, tok::l_square, PP.getIdentifierInfo("clang"),
1084    tok::coloncolon, PP.getIdentifierInfo("fallthrough"),
1085    tok::r_square, tok::r_square
1086  };
1087
1088  bool PreferClangAttr = !PP.getLangOpts().CPlusPlus1z;
1089
1090  StringRef MacroName;
1091  if (PreferClangAttr)
1092    MacroName = PP.getLastMacroWithSpelling(Loc, ClangFallthroughTokens);
1093  if (MacroName.empty())
1094    MacroName = PP.getLastMacroWithSpelling(Loc, FallthroughTokens);
1095  if (MacroName.empty() && !PreferClangAttr)
1096    MacroName = PP.getLastMacroWithSpelling(Loc, ClangFallthroughTokens);
1097  if (MacroName.empty())
1098    MacroName = PreferClangAttr ? "[[clang::fallthrough]]" : "[[fallthrough]]";
1099  return MacroName;
1100}
1101
1102static void DiagnoseSwitchLabelsFallthrough(Sema &S, AnalysisDeclContext &AC,
1103                                            bool PerFunction) {
1104  // Only perform this analysis when using C++11.  There is no good workflow
1105  // for this warning when not using C++11.  There is no good way to silence
1106  // the warning (no attribute is available) unless we are using C++11's support
1107  // for generalized attributes.  Once could use pragmas to silence the warning,
1108  // but as a general solution that is gross and not in the spirit of this
1109  // warning.
1110  //
1111  // NOTE: This an intermediate solution.  There are on-going discussions on
1112  // how to properly support this warning outside of C++11 with an annotation.
1113  if (!AC.getASTContext().getLangOpts().CPlusPlus11)
1114    return;
1115
1116  FallthroughMapper FM(S);
1117  FM.TraverseStmt(AC.getBody());
1118
1119  if (!FM.foundSwitchStatements())
1120    return;
1121
1122  if (PerFunction && FM.getFallthroughStmts().empty())
1123    return;
1124
1125  CFG *Cfg = AC.getCFG();
1126
1127  if (!Cfg)
1128    return;
1129
1130  FM.fillReachableBlocks(Cfg);
1131
1132  for (const CFGBlock *B : llvm::reverse(*Cfg)) {
1133    const Stmt *Label = B->getLabel();
1134
1135    if (!Label || !isa<SwitchCase>(Label))
1136      continue;
1137
1138    int AnnotatedCnt;
1139
1140    if (!FM.checkFallThroughIntoBlock(*B, AnnotatedCnt))
1141      continue;
1142
1143    S.Diag(Label->getLocStart(),
1144        PerFunction ? diag::warn_unannotated_fallthrough_per_function
1145                    : diag::warn_unannotated_fallthrough);
1146
1147    if (!AnnotatedCnt) {
1148      SourceLocation L = Label->getLocStart();
1149      if (L.isMacroID())
1150        continue;
1151      if (S.getLangOpts().CPlusPlus11) {
1152        const Stmt *Term = B->getTerminator();
1153        // Skip empty cases.
1154        while (B->empty() && !Term && B->succ_size() == 1) {
1155          B = *B->succ_begin();
1156          Term = B->getTerminator();
1157        }
1158        if (!(B->empty() && Term && isa<BreakStmt>(Term))) {
1159          Preprocessor &PP = S.getPreprocessor();
1160          StringRef AnnotationSpelling = getFallthroughAttrSpelling(PP, L);
1161          SmallString<64> TextToInsert(AnnotationSpelling);
1162          TextToInsert += "; ";
1163          S.Diag(L, diag::note_insert_fallthrough_fixit) <<
1164              AnnotationSpelling <<
1165              FixItHint::CreateInsertion(L, TextToInsert);
1166        }
1167      }
1168      S.Diag(L, diag::note_insert_break_fixit) <<
1169        FixItHint::CreateInsertion(L, "break; ");
1170    }
1171  }
1172
1173  for (const auto *F : FM.getFallthroughStmts())
1174    S.Diag(F->getLocStart(), diag::err_fallthrough_attr_invalid_placement);
1175}
1176
1177static bool isInLoop(const ASTContext &Ctx, const ParentMap &PM,
1178                     const Stmt *S) {
1179  assert(S);
1180
1181  do {
1182    switch (S->getStmtClass()) {
1183    case Stmt::ForStmtClass:
1184    case Stmt::WhileStmtClass:
1185    case Stmt::CXXForRangeStmtClass:
1186    case Stmt::ObjCForCollectionStmtClass:
1187      return true;
1188    case Stmt::DoStmtClass: {
1189      const Expr *Cond = cast<DoStmt>(S)->getCond();
1190      llvm::APSInt Val;
1191      if (!Cond->EvaluateAsInt(Val, Ctx))
1192        return true;
1193      return Val.getBoolValue();
1194    }
1195    default:
1196      break;
1197    }
1198  } while ((S = PM.getParent(S)));
1199
1200  return false;
1201}
1202
1203static void diagnoseRepeatedUseOfWeak(Sema &S,
1204                                      const sema::FunctionScopeInfo *CurFn,
1205                                      const Decl *D,
1206                                      const ParentMap &PM) {
1207  typedef sema::FunctionScopeInfo::WeakObjectProfileTy WeakObjectProfileTy;
1208  typedef sema::FunctionScopeInfo::WeakObjectUseMap WeakObjectUseMap;
1209  typedef sema::FunctionScopeInfo::WeakUseVector WeakUseVector;
1210  typedef std::pair<const Stmt *, WeakObjectUseMap::const_iterator>
1211  StmtUsesPair;
1212
1213  ASTContext &Ctx = S.getASTContext();
1214
1215  const WeakObjectUseMap &WeakMap = CurFn->getWeakObjectUses();
1216
1217  // Extract all weak objects that are referenced more than once.
1218  SmallVector<StmtUsesPair, 8> UsesByStmt;
1219  for (WeakObjectUseMap::const_iterator I = WeakMap.begin(), E = WeakMap.end();
1220       I != E; ++I) {
1221    const WeakUseVector &Uses = I->second;
1222
1223    // Find the first read of the weak object.
1224    WeakUseVector::const_iterator UI = Uses.begin(), UE = Uses.end();
1225    for ( ; UI != UE; ++UI) {
1226      if (UI->isUnsafe())
1227        break;
1228    }
1229
1230    // If there were only writes to this object, don't warn.
1231    if (UI == UE)
1232      continue;
1233
1234    // If there was only one read, followed by any number of writes, and the
1235    // read is not within a loop, don't warn. Additionally, don't warn in a
1236    // loop if the base object is a local variable -- local variables are often
1237    // changed in loops.
1238    if (UI == Uses.begin()) {
1239      WeakUseVector::const_iterator UI2 = UI;
1240      for (++UI2; UI2 != UE; ++UI2)
1241        if (UI2->isUnsafe())
1242          break;
1243
1244      if (UI2 == UE) {
1245        if (!isInLoop(Ctx, PM, UI->getUseExpr()))
1246          continue;
1247
1248        const WeakObjectProfileTy &Profile = I->first;
1249        if (!Profile.isExactProfile())
1250          continue;
1251
1252        const NamedDecl *Base = Profile.getBase();
1253        if (!Base)
1254          Base = Profile.getProperty();
1255        assert(Base && "A profile always has a base or property.");
1256
1257        if (const VarDecl *BaseVar = dyn_cast<VarDecl>(Base))
1258          if (BaseVar->hasLocalStorage() && !isa<ParmVarDecl>(Base))
1259            continue;
1260      }
1261    }
1262
1263    UsesByStmt.push_back(StmtUsesPair(UI->getUseExpr(), I));
1264  }
1265
1266  if (UsesByStmt.empty())
1267    return;
1268
1269  // Sort by first use so that we emit the warnings in a deterministic order.
1270  SourceManager &SM = S.getSourceManager();
1271  std::sort(UsesByStmt.begin(), UsesByStmt.end(),
1272            [&SM](const StmtUsesPair &LHS, const StmtUsesPair &RHS) {
1273    return SM.isBeforeInTranslationUnit(LHS.first->getLocStart(),
1274                                        RHS.first->getLocStart());
1275  });
1276
1277  // Classify the current code body for better warning text.
1278  // This enum should stay in sync with the cases in
1279  // warn_arc_repeated_use_of_weak and warn_arc_possible_repeated_use_of_weak.
1280  // FIXME: Should we use a common classification enum and the same set of
1281  // possibilities all throughout Sema?
1282  enum {
1283    Function,
1284    Method,
1285    Block,
1286    Lambda
1287  } FunctionKind;
1288
1289  if (isa<sema::BlockScopeInfo>(CurFn))
1290    FunctionKind = Block;
1291  else if (isa<sema::LambdaScopeInfo>(CurFn))
1292    FunctionKind = Lambda;
1293  else if (isa<ObjCMethodDecl>(D))
1294    FunctionKind = Method;
1295  else
1296    FunctionKind = Function;
1297
1298  // Iterate through the sorted problems and emit warnings for each.
1299  for (const auto &P : UsesByStmt) {
1300    const Stmt *FirstRead = P.first;
1301    const WeakObjectProfileTy &Key = P.second->first;
1302    const WeakUseVector &Uses = P.second->second;
1303
1304    // For complicated expressions like 'a.b.c' and 'x.b.c', WeakObjectProfileTy
1305    // may not contain enough information to determine that these are different
1306    // properties. We can only be 100% sure of a repeated use in certain cases,
1307    // and we adjust the diagnostic kind accordingly so that the less certain
1308    // case can be turned off if it is too noisy.
1309    unsigned DiagKind;
1310    if (Key.isExactProfile())
1311      DiagKind = diag::warn_arc_repeated_use_of_weak;
1312    else
1313      DiagKind = diag::warn_arc_possible_repeated_use_of_weak;
1314
1315    // Classify the weak object being accessed for better warning text.
1316    // This enum should stay in sync with the cases in
1317    // warn_arc_repeated_use_of_weak and warn_arc_possible_repeated_use_of_weak.
1318    enum {
1319      Variable,
1320      Property,
1321      ImplicitProperty,
1322      Ivar
1323    } ObjectKind;
1324
1325    const NamedDecl *KeyProp = Key.getProperty();
1326    if (isa<VarDecl>(KeyProp))
1327      ObjectKind = Variable;
1328    else if (isa<ObjCPropertyDecl>(KeyProp))
1329      ObjectKind = Property;
1330    else if (isa<ObjCMethodDecl>(KeyProp))
1331      ObjectKind = ImplicitProperty;
1332    else if (isa<ObjCIvarDecl>(KeyProp))
1333      ObjectKind = Ivar;
1334    else
1335      llvm_unreachable("Unexpected weak object kind!");
1336
1337    // Do not warn about IBOutlet weak property receivers being set to null
1338    // since they are typically only used from the main thread.
1339    if (const ObjCPropertyDecl *Prop = dyn_cast<ObjCPropertyDecl>(KeyProp))
1340      if (Prop->hasAttr<IBOutletAttr>())
1341        continue;
1342
1343    // Show the first time the object was read.
1344    S.Diag(FirstRead->getLocStart(), DiagKind)
1345      << int(ObjectKind) << KeyProp << int(FunctionKind)
1346      << FirstRead->getSourceRange();
1347
1348    // Print all the other accesses as notes.
1349    for (const auto &Use : Uses) {
1350      if (Use.getUseExpr() == FirstRead)
1351        continue;
1352      S.Diag(Use.getUseExpr()->getLocStart(),
1353             diag::note_arc_weak_also_accessed_here)
1354          << Use.getUseExpr()->getSourceRange();
1355    }
1356  }
1357}
1358
1359namespace {
1360class UninitValsDiagReporter : public UninitVariablesHandler {
1361  Sema &S;
1362  typedef SmallVector<UninitUse, 2> UsesVec;
1363  typedef llvm::PointerIntPair<UsesVec *, 1, bool> MappedType;
1364  // Prefer using MapVector to DenseMap, so that iteration order will be
1365  // the same as insertion order. This is needed to obtain a deterministic
1366  // order of diagnostics when calling flushDiagnostics().
1367  typedef llvm::MapVector<const VarDecl *, MappedType> UsesMap;
1368  UsesMap uses;
1369
1370public:
1371  UninitValsDiagReporter(Sema &S) : S(S) {}
1372  ~UninitValsDiagReporter() override { flushDiagnostics(); }
1373
1374  MappedType &getUses(const VarDecl *vd) {
1375    MappedType &V = uses[vd];
1376    if (!V.getPointer())
1377      V.setPointer(new UsesVec());
1378    return V;
1379  }
1380
1381  void handleUseOfUninitVariable(const VarDecl *vd,
1382                                 const UninitUse &use) override {
1383    getUses(vd).getPointer()->push_back(use);
1384  }
1385
1386  void handleSelfInit(const VarDecl *vd) override {
1387    getUses(vd).setInt(true);
1388  }
1389
1390  void flushDiagnostics() {
1391    for (const auto &P : uses) {
1392      const VarDecl *vd = P.first;
1393      const MappedType &V = P.second;
1394
1395      UsesVec *vec = V.getPointer();
1396      bool hasSelfInit = V.getInt();
1397
1398      // Specially handle the case where we have uses of an uninitialized
1399      // variable, but the root cause is an idiomatic self-init.  We want
1400      // to report the diagnostic at the self-init since that is the root cause.
1401      if (!vec->empty() && hasSelfInit && hasAlwaysUninitializedUse(vec))
1402        DiagnoseUninitializedUse(S, vd,
1403                                 UninitUse(vd->getInit()->IgnoreParenCasts(),
1404                                           /* isAlwaysUninit */ true),
1405                                 /* alwaysReportSelfInit */ true);
1406      else {
1407        // Sort the uses by their SourceLocations.  While not strictly
1408        // guaranteed to produce them in line/column order, this will provide
1409        // a stable ordering.
1410        std::sort(vec->begin(), vec->end(),
1411                  [](const UninitUse &a, const UninitUse &b) {
1412          // Prefer a more confident report over a less confident one.
1413          if (a.getKind() != b.getKind())
1414            return a.getKind() > b.getKind();
1415          return a.getUser()->getLocStart() < b.getUser()->getLocStart();
1416        });
1417
1418        for (const auto &U : *vec) {
1419          // If we have self-init, downgrade all uses to 'may be uninitialized'.
1420          UninitUse Use = hasSelfInit ? UninitUse(U.getUser(), false) : U;
1421
1422          if (DiagnoseUninitializedUse(S, vd, Use))
1423            // Skip further diagnostics for this variable. We try to warn only
1424            // on the first point at which a variable is used uninitialized.
1425            break;
1426        }
1427      }
1428
1429      // Release the uses vector.
1430      delete vec;
1431    }
1432
1433    uses.clear();
1434  }
1435
1436private:
1437  static bool hasAlwaysUninitializedUse(const UsesVec* vec) {
1438    return std::any_of(vec->begin(), vec->end(), [](const UninitUse &U) {
1439      return U.getKind() == UninitUse::Always ||
1440             U.getKind() == UninitUse::AfterCall ||
1441             U.getKind() == UninitUse::AfterDecl;
1442    });
1443  }
1444};
1445} // anonymous namespace
1446
1447namespace clang {
1448namespace {
1449typedef SmallVector<PartialDiagnosticAt, 1> OptionalNotes;
1450typedef std::pair<PartialDiagnosticAt, OptionalNotes> DelayedDiag;
1451typedef std::list<DelayedDiag> DiagList;
1452
1453struct SortDiagBySourceLocation {
1454  SourceManager &SM;
1455  SortDiagBySourceLocation(SourceManager &SM) : SM(SM) {}
1456
1457  bool operator()(const DelayedDiag &left, const DelayedDiag &right) {
1458    // Although this call will be slow, this is only called when outputting
1459    // multiple warnings.
1460    return SM.isBeforeInTranslationUnit(left.first.first, right.first.first);
1461  }
1462};
1463} // anonymous namespace
1464} // namespace clang
1465
1466//===----------------------------------------------------------------------===//
1467// -Wthread-safety
1468//===----------------------------------------------------------------------===//
1469namespace clang {
1470namespace threadSafety {
1471namespace {
1472class ThreadSafetyReporter : public clang::threadSafety::ThreadSafetyHandler {
1473  Sema &S;
1474  DiagList Warnings;
1475  SourceLocation FunLocation, FunEndLocation;
1476
1477  const FunctionDecl *CurrentFunction;
1478  bool Verbose;
1479
1480  OptionalNotes getNotes() const {
1481    if (Verbose && CurrentFunction) {
1482      PartialDiagnosticAt FNote(CurrentFunction->getBody()->getLocStart(),
1483                                S.PDiag(diag::note_thread_warning_in_fun)
1484                                    << CurrentFunction->getNameAsString());
1485      return OptionalNotes(1, FNote);
1486    }
1487    return OptionalNotes();
1488  }
1489
1490  OptionalNotes getNotes(const PartialDiagnosticAt &Note) const {
1491    OptionalNotes ONS(1, Note);
1492    if (Verbose && CurrentFunction) {
1493      PartialDiagnosticAt FNote(CurrentFunction->getBody()->getLocStart(),
1494                                S.PDiag(diag::note_thread_warning_in_fun)
1495                                    << CurrentFunction->getNameAsString());
1496      ONS.push_back(std::move(FNote));
1497    }
1498    return ONS;
1499  }
1500
1501  OptionalNotes getNotes(const PartialDiagnosticAt &Note1,
1502                         const PartialDiagnosticAt &Note2) const {
1503    OptionalNotes ONS;
1504    ONS.push_back(Note1);
1505    ONS.push_back(Note2);
1506    if (Verbose && CurrentFunction) {
1507      PartialDiagnosticAt FNote(CurrentFunction->getBody()->getLocStart(),
1508                                S.PDiag(diag::note_thread_warning_in_fun)
1509                                    << CurrentFunction->getNameAsString());
1510      ONS.push_back(std::move(FNote));
1511    }
1512    return ONS;
1513  }
1514
1515  // Helper functions
1516  void warnLockMismatch(unsigned DiagID, StringRef Kind, Name LockName,
1517                        SourceLocation Loc) {
1518    // Gracefully handle rare cases when the analysis can't get a more
1519    // precise source location.
1520    if (!Loc.isValid())
1521      Loc = FunLocation;
1522    PartialDiagnosticAt Warning(Loc, S.PDiag(DiagID) << Kind << LockName);
1523    Warnings.emplace_back(std::move(Warning), getNotes());
1524  }
1525
1526 public:
1527  ThreadSafetyReporter(Sema &S, SourceLocation FL, SourceLocation FEL)
1528    : S(S), FunLocation(FL), FunEndLocation(FEL),
1529      CurrentFunction(nullptr), Verbose(false) {}
1530
1531  void setVerbose(bool b) { Verbose = b; }
1532
1533  /// \brief Emit all buffered diagnostics in order of sourcelocation.
1534  /// We need to output diagnostics produced while iterating through
1535  /// the lockset in deterministic order, so this function orders diagnostics
1536  /// and outputs them.
1537  void emitDiagnostics() {
1538    Warnings.sort(SortDiagBySourceLocation(S.getSourceManager()));
1539    for (const auto &Diag : Warnings) {
1540      S.Diag(Diag.first.first, Diag.first.second);
1541      for (const auto &Note : Diag.second)
1542        S.Diag(Note.first, Note.second);
1543    }
1544  }
1545
1546  void handleInvalidLockExp(StringRef Kind, SourceLocation Loc) override {
1547    PartialDiagnosticAt Warning(Loc, S.PDiag(diag::warn_cannot_resolve_lock)
1548                                         << Loc);
1549    Warnings.emplace_back(std::move(Warning), getNotes());
1550  }
1551
1552  void handleUnmatchedUnlock(StringRef Kind, Name LockName,
1553                             SourceLocation Loc) override {
1554    warnLockMismatch(diag::warn_unlock_but_no_lock, Kind, LockName, Loc);
1555  }
1556
1557  void handleIncorrectUnlockKind(StringRef Kind, Name LockName,
1558                                 LockKind Expected, LockKind Received,
1559                                 SourceLocation Loc) override {
1560    if (Loc.isInvalid())
1561      Loc = FunLocation;
1562    PartialDiagnosticAt Warning(Loc, S.PDiag(diag::warn_unlock_kind_mismatch)
1563                                         << Kind << LockName << Received
1564                                         << Expected);
1565    Warnings.emplace_back(std::move(Warning), getNotes());
1566  }
1567
1568  void handleDoubleLock(StringRef Kind, Name LockName, SourceLocation Loc) override {
1569    warnLockMismatch(diag::warn_double_lock, Kind, LockName, Loc);
1570  }
1571
1572  void handleMutexHeldEndOfScope(StringRef Kind, Name LockName,
1573                                 SourceLocation LocLocked,
1574                                 SourceLocation LocEndOfScope,
1575                                 LockErrorKind LEK) override {
1576    unsigned DiagID = 0;
1577    switch (LEK) {
1578      case LEK_LockedSomePredecessors:
1579        DiagID = diag::warn_lock_some_predecessors;
1580        break;
1581      case LEK_LockedSomeLoopIterations:
1582        DiagID = diag::warn_expecting_lock_held_on_loop;
1583        break;
1584      case LEK_LockedAtEndOfFunction:
1585        DiagID = diag::warn_no_unlock;
1586        break;
1587      case LEK_NotLockedAtEndOfFunction:
1588        DiagID = diag::warn_expecting_locked;
1589        break;
1590    }
1591    if (LocEndOfScope.isInvalid())
1592      LocEndOfScope = FunEndLocation;
1593
1594    PartialDiagnosticAt Warning(LocEndOfScope, S.PDiag(DiagID) << Kind
1595                                                               << LockName);
1596    if (LocLocked.isValid()) {
1597      PartialDiagnosticAt Note(LocLocked, S.PDiag(diag::note_locked_here)
1598                                              << Kind);
1599      Warnings.emplace_back(std::move(Warning), getNotes(Note));
1600      return;
1601    }
1602    Warnings.emplace_back(std::move(Warning), getNotes());
1603  }
1604
1605  void handleExclusiveAndShared(StringRef Kind, Name LockName,
1606                                SourceLocation Loc1,
1607                                SourceLocation Loc2) override {
1608    PartialDiagnosticAt Warning(Loc1,
1609                                S.PDiag(diag::warn_lock_exclusive_and_shared)
1610                                    << Kind << LockName);
1611    PartialDiagnosticAt Note(Loc2, S.PDiag(diag::note_lock_exclusive_and_shared)
1612                                       << Kind << LockName);
1613    Warnings.emplace_back(std::move(Warning), getNotes(Note));
1614  }
1615
1616  void handleNoMutexHeld(StringRef Kind, const NamedDecl *D,
1617                         ProtectedOperationKind POK, AccessKind AK,
1618                         SourceLocation Loc) override {
1619    assert((POK == POK_VarAccess || POK == POK_VarDereference) &&
1620           "Only works for variables");
1621    unsigned DiagID = POK == POK_VarAccess?
1622                        diag::warn_variable_requires_any_lock:
1623                        diag::warn_var_deref_requires_any_lock;
1624    PartialDiagnosticAt Warning(Loc, S.PDiag(DiagID)
1625      << D->getNameAsString() << getLockKindFromAccessKind(AK));
1626    Warnings.emplace_back(std::move(Warning), getNotes());
1627  }
1628
1629  void handleMutexNotHeld(StringRef Kind, const NamedDecl *D,
1630                          ProtectedOperationKind POK, Name LockName,
1631                          LockKind LK, SourceLocation Loc,
1632                          Name *PossibleMatch) override {
1633    unsigned DiagID = 0;
1634    if (PossibleMatch) {
1635      switch (POK) {
1636        case POK_VarAccess:
1637          DiagID = diag::warn_variable_requires_lock_precise;
1638          break;
1639        case POK_VarDereference:
1640          DiagID = diag::warn_var_deref_requires_lock_precise;
1641          break;
1642        case POK_FunctionCall:
1643          DiagID = diag::warn_fun_requires_lock_precise;
1644          break;
1645        case POK_PassByRef:
1646          DiagID = diag::warn_guarded_pass_by_reference;
1647          break;
1648        case POK_PtPassByRef:
1649          DiagID = diag::warn_pt_guarded_pass_by_reference;
1650          break;
1651      }
1652      PartialDiagnosticAt Warning(Loc, S.PDiag(DiagID) << Kind
1653                                                       << D->getNameAsString()
1654                                                       << LockName << LK);
1655      PartialDiagnosticAt Note(Loc, S.PDiag(diag::note_found_mutex_near_match)
1656                                        << *PossibleMatch);
1657      if (Verbose && POK == POK_VarAccess) {
1658        PartialDiagnosticAt VNote(D->getLocation(),
1659                                 S.PDiag(diag::note_guarded_by_declared_here)
1660                                     << D->getNameAsString());
1661        Warnings.emplace_back(std::move(Warning), getNotes(Note, VNote));
1662      } else
1663        Warnings.emplace_back(std::move(Warning), getNotes(Note));
1664    } else {
1665      switch (POK) {
1666        case POK_VarAccess:
1667          DiagID = diag::warn_variable_requires_lock;
1668          break;
1669        case POK_VarDereference:
1670          DiagID = diag::warn_var_deref_requires_lock;
1671          break;
1672        case POK_FunctionCall:
1673          DiagID = diag::warn_fun_requires_lock;
1674          break;
1675        case POK_PassByRef:
1676          DiagID = diag::warn_guarded_pass_by_reference;
1677          break;
1678        case POK_PtPassByRef:
1679          DiagID = diag::warn_pt_guarded_pass_by_reference;
1680          break;
1681      }
1682      PartialDiagnosticAt Warning(Loc, S.PDiag(DiagID) << Kind
1683                                                       << D->getNameAsString()
1684                                                       << LockName << LK);
1685      if (Verbose && POK == POK_VarAccess) {
1686        PartialDiagnosticAt Note(D->getLocation(),
1687                                 S.PDiag(diag::note_guarded_by_declared_here)
1688                                     << D->getNameAsString());
1689        Warnings.emplace_back(std::move(Warning), getNotes(Note));
1690      } else
1691        Warnings.emplace_back(std::move(Warning), getNotes());
1692    }
1693  }
1694
1695  void handleNegativeNotHeld(StringRef Kind, Name LockName, Name Neg,
1696                             SourceLocation Loc) override {
1697    PartialDiagnosticAt Warning(Loc,
1698        S.PDiag(diag::warn_acquire_requires_negative_cap)
1699        << Kind << LockName << Neg);
1700    Warnings.emplace_back(std::move(Warning), getNotes());
1701  }
1702
1703  void handleFunExcludesLock(StringRef Kind, Name FunName, Name LockName,
1704                             SourceLocation Loc) override {
1705    PartialDiagnosticAt Warning(Loc, S.PDiag(diag::warn_fun_excludes_mutex)
1706                                         << Kind << FunName << LockName);
1707    Warnings.emplace_back(std::move(Warning), getNotes());
1708  }
1709
1710  void handleLockAcquiredBefore(StringRef Kind, Name L1Name, Name L2Name,
1711                                SourceLocation Loc) override {
1712    PartialDiagnosticAt Warning(Loc,
1713      S.PDiag(diag::warn_acquired_before) << Kind << L1Name << L2Name);
1714    Warnings.emplace_back(std::move(Warning), getNotes());
1715  }
1716
1717  void handleBeforeAfterCycle(Name L1Name, SourceLocation Loc) override {
1718    PartialDiagnosticAt Warning(Loc,
1719      S.PDiag(diag::warn_acquired_before_after_cycle) << L1Name);
1720    Warnings.emplace_back(std::move(Warning), getNotes());
1721  }
1722
1723  void enterFunction(const FunctionDecl* FD) override {
1724    CurrentFunction = FD;
1725  }
1726
1727  void leaveFunction(const FunctionDecl* FD) override {
1728    CurrentFunction = nullptr;
1729  }
1730};
1731} // anonymous namespace
1732} // namespace threadSafety
1733} // namespace clang
1734
1735//===----------------------------------------------------------------------===//
1736// -Wconsumed
1737//===----------------------------------------------------------------------===//
1738
1739namespace clang {
1740namespace consumed {
1741namespace {
1742class ConsumedWarningsHandler : public ConsumedWarningsHandlerBase {
1743
1744  Sema &S;
1745  DiagList Warnings;
1746
1747public:
1748
1749  ConsumedWarningsHandler(Sema &S) : S(S) {}
1750
1751  void emitDiagnostics() override {
1752    Warnings.sort(SortDiagBySourceLocation(S.getSourceManager()));
1753    for (const auto &Diag : Warnings) {
1754      S.Diag(Diag.first.first, Diag.first.second);
1755      for (const auto &Note : Diag.second)
1756        S.Diag(Note.first, Note.second);
1757    }
1758  }
1759
1760  void warnLoopStateMismatch(SourceLocation Loc,
1761                             StringRef VariableName) override {
1762    PartialDiagnosticAt Warning(Loc, S.PDiag(diag::warn_loop_state_mismatch) <<
1763      VariableName);
1764
1765    Warnings.emplace_back(std::move(Warning), OptionalNotes());
1766  }
1767
1768  void warnParamReturnTypestateMismatch(SourceLocation Loc,
1769                                        StringRef VariableName,
1770                                        StringRef ExpectedState,
1771                                        StringRef ObservedState) override {
1772
1773    PartialDiagnosticAt Warning(Loc, S.PDiag(
1774      diag::warn_param_return_typestate_mismatch) << VariableName <<
1775        ExpectedState << ObservedState);
1776
1777    Warnings.emplace_back(std::move(Warning), OptionalNotes());
1778  }
1779
1780  void warnParamTypestateMismatch(SourceLocation Loc, StringRef ExpectedState,
1781                                  StringRef ObservedState) override {
1782
1783    PartialDiagnosticAt Warning(Loc, S.PDiag(
1784      diag::warn_param_typestate_mismatch) << ExpectedState << ObservedState);
1785
1786    Warnings.emplace_back(std::move(Warning), OptionalNotes());
1787  }
1788
1789  void warnReturnTypestateForUnconsumableType(SourceLocation Loc,
1790                                              StringRef TypeName) override {
1791    PartialDiagnosticAt Warning(Loc, S.PDiag(
1792      diag::warn_return_typestate_for_unconsumable_type) << TypeName);
1793
1794    Warnings.emplace_back(std::move(Warning), OptionalNotes());
1795  }
1796
1797  void warnReturnTypestateMismatch(SourceLocation Loc, StringRef ExpectedState,
1798                                   StringRef ObservedState) override {
1799
1800    PartialDiagnosticAt Warning(Loc, S.PDiag(
1801      diag::warn_return_typestate_mismatch) << ExpectedState << ObservedState);
1802
1803    Warnings.emplace_back(std::move(Warning), OptionalNotes());
1804  }
1805
1806  void warnUseOfTempInInvalidState(StringRef MethodName, StringRef State,
1807                                   SourceLocation Loc) override {
1808
1809    PartialDiagnosticAt Warning(Loc, S.PDiag(
1810      diag::warn_use_of_temp_in_invalid_state) << MethodName << State);
1811
1812    Warnings.emplace_back(std::move(Warning), OptionalNotes());
1813  }
1814
1815  void warnUseInInvalidState(StringRef MethodName, StringRef VariableName,
1816                             StringRef State, SourceLocation Loc) override {
1817
1818    PartialDiagnosticAt Warning(Loc, S.PDiag(diag::warn_use_in_invalid_state) <<
1819                                MethodName << VariableName << State);
1820
1821    Warnings.emplace_back(std::move(Warning), OptionalNotes());
1822  }
1823};
1824} // anonymous namespace
1825} // namespace consumed
1826} // namespace clang
1827
1828//===----------------------------------------------------------------------===//
1829// AnalysisBasedWarnings - Worker object used by Sema to execute analysis-based
1830//  warnings on a function, method, or block.
1831//===----------------------------------------------------------------------===//
1832
1833clang::sema::AnalysisBasedWarnings::Policy::Policy() {
1834  enableCheckFallThrough = 1;
1835  enableCheckUnreachable = 0;
1836  enableThreadSafetyAnalysis = 0;
1837  enableConsumedAnalysis = 0;
1838}
1839
1840static unsigned isEnabled(DiagnosticsEngine &D, unsigned diag) {
1841  return (unsigned)!D.isIgnored(diag, SourceLocation());
1842}
1843
1844clang::sema::AnalysisBasedWarnings::AnalysisBasedWarnings(Sema &s)
1845  : S(s),
1846    NumFunctionsAnalyzed(0),
1847    NumFunctionsWithBadCFGs(0),
1848    NumCFGBlocks(0),
1849    MaxCFGBlocksPerFunction(0),
1850    NumUninitAnalysisFunctions(0),
1851    NumUninitAnalysisVariables(0),
1852    MaxUninitAnalysisVariablesPerFunction(0),
1853    NumUninitAnalysisBlockVisits(0),
1854    MaxUninitAnalysisBlockVisitsPerFunction(0) {
1855
1856  using namespace diag;
1857  DiagnosticsEngine &D = S.getDiagnostics();
1858
1859  DefaultPolicy.enableCheckUnreachable =
1860    isEnabled(D, warn_unreachable) ||
1861    isEnabled(D, warn_unreachable_break) ||
1862    isEnabled(D, warn_unreachable_return) ||
1863    isEnabled(D, warn_unreachable_loop_increment);
1864
1865  DefaultPolicy.enableThreadSafetyAnalysis =
1866    isEnabled(D, warn_double_lock);
1867
1868  DefaultPolicy.enableConsumedAnalysis =
1869    isEnabled(D, warn_use_in_invalid_state);
1870}
1871
1872static void flushDiagnostics(Sema &S, const sema::FunctionScopeInfo *fscope) {
1873  for (const auto &D : fscope->PossiblyUnreachableDiags)
1874    S.Diag(D.Loc, D.PD);
1875}
1876
1877void clang::sema::
1878AnalysisBasedWarnings::IssueWarnings(sema::AnalysisBasedWarnings::Policy P,
1879                                     sema::FunctionScopeInfo *fscope,
1880                                     const Decl *D, const BlockExpr *blkExpr) {
1881
1882  // We avoid doing analysis-based warnings when there are errors for
1883  // two reasons:
1884  // (1) The CFGs often can't be constructed (if the body is invalid), so
1885  //     don't bother trying.
1886  // (2) The code already has problems; running the analysis just takes more
1887  //     time.
1888  DiagnosticsEngine &Diags = S.getDiagnostics();
1889
1890  // Do not do any analysis for declarations in system headers if we are
1891  // going to just ignore them.
1892  if (Diags.getSuppressSystemWarnings() &&
1893      S.SourceMgr.isInSystemHeader(D->getLocation()))
1894    return;
1895
1896  // For code in dependent contexts, we'll do this at instantiation time.
1897  if (cast<DeclContext>(D)->isDependentContext())
1898    return;
1899
1900  if (Diags.hasUncompilableErrorOccurred()) {
1901    // Flush out any possibly unreachable diagnostics.
1902    flushDiagnostics(S, fscope);
1903    return;
1904  }
1905
1906  const Stmt *Body = D->getBody();
1907  assert(Body);
1908
1909  // Construct the analysis context with the specified CFG build options.
1910  AnalysisDeclContext AC(/* AnalysisDeclContextManager */ nullptr, D);
1911
1912  // Don't generate EH edges for CallExprs as we'd like to avoid the n^2
1913  // explosion for destructors that can result and the compile time hit.
1914  AC.getCFGBuildOptions().PruneTriviallyFalseEdges = true;
1915  AC.getCFGBuildOptions().AddEHEdges = false;
1916  AC.getCFGBuildOptions().AddInitializers = true;
1917  AC.getCFGBuildOptions().AddImplicitDtors = true;
1918  AC.getCFGBuildOptions().AddTemporaryDtors = true;
1919  AC.getCFGBuildOptions().AddCXXNewAllocator = false;
1920  AC.getCFGBuildOptions().AddCXXDefaultInitExprInCtors = true;
1921
1922  // Force that certain expressions appear as CFGElements in the CFG.  This
1923  // is used to speed up various analyses.
1924  // FIXME: This isn't the right factoring.  This is here for initial
1925  // prototyping, but we need a way for analyses to say what expressions they
1926  // expect to always be CFGElements and then fill in the BuildOptions
1927  // appropriately.  This is essentially a layering violation.
1928  if (P.enableCheckUnreachable || P.enableThreadSafetyAnalysis ||
1929      P.enableConsumedAnalysis) {
1930    // Unreachable code analysis and thread safety require a linearized CFG.
1931    AC.getCFGBuildOptions().setAllAlwaysAdd();
1932  }
1933  else {
1934    AC.getCFGBuildOptions()
1935      .setAlwaysAdd(Stmt::BinaryOperatorClass)
1936      .setAlwaysAdd(Stmt::CompoundAssignOperatorClass)
1937      .setAlwaysAdd(Stmt::BlockExprClass)
1938      .setAlwaysAdd(Stmt::CStyleCastExprClass)
1939      .setAlwaysAdd(Stmt::DeclRefExprClass)
1940      .setAlwaysAdd(Stmt::ImplicitCastExprClass)
1941      .setAlwaysAdd(Stmt::UnaryOperatorClass)
1942      .setAlwaysAdd(Stmt::AttributedStmtClass);
1943  }
1944
1945  // Install the logical handler for -Wtautological-overlap-compare
1946  std::unique_ptr<LogicalErrorHandler> LEH;
1947  if (!Diags.isIgnored(diag::warn_tautological_overlap_comparison,
1948                       D->getLocStart())) {
1949    LEH.reset(new LogicalErrorHandler(S));
1950    AC.getCFGBuildOptions().Observer = LEH.get();
1951  }
1952
1953  // Emit delayed diagnostics.
1954  if (!fscope->PossiblyUnreachableDiags.empty()) {
1955    bool analyzed = false;
1956
1957    // Register the expressions with the CFGBuilder.
1958    for (const auto &D : fscope->PossiblyUnreachableDiags) {
1959      if (D.stmt)
1960        AC.registerForcedBlockExpression(D.stmt);
1961    }
1962
1963    if (AC.getCFG()) {
1964      analyzed = true;
1965      for (const auto &D : fscope->PossiblyUnreachableDiags) {
1966        bool processed = false;
1967        if (D.stmt) {
1968          const CFGBlock *block = AC.getBlockForRegisteredExpression(D.stmt);
1969          CFGReverseBlockReachabilityAnalysis *cra =
1970              AC.getCFGReachablityAnalysis();
1971          // FIXME: We should be able to assert that block is non-null, but
1972          // the CFG analysis can skip potentially-evaluated expressions in
1973          // edge cases; see test/Sema/vla-2.c.
1974          if (block && cra) {
1975            // Can this block be reached from the entrance?
1976            if (cra->isReachable(&AC.getCFG()->getEntry(), block))
1977              S.Diag(D.Loc, D.PD);
1978            processed = true;
1979          }
1980        }
1981        if (!processed) {
1982          // Emit the warning anyway if we cannot map to a basic block.
1983          S.Diag(D.Loc, D.PD);
1984        }
1985      }
1986    }
1987
1988    if (!analyzed)
1989      flushDiagnostics(S, fscope);
1990  }
1991
1992  // Warning: check missing 'return'
1993  if (P.enableCheckFallThrough) {
1994    const CheckFallThroughDiagnostics &CD =
1995      (isa<BlockDecl>(D) ? CheckFallThroughDiagnostics::MakeForBlock()
1996       : (isa<CXXMethodDecl>(D) &&
1997          cast<CXXMethodDecl>(D)->getOverloadedOperator() == OO_Call &&
1998          cast<CXXMethodDecl>(D)->getParent()->isLambda())
1999            ? CheckFallThroughDiagnostics::MakeForLambda()
2000            : CheckFallThroughDiagnostics::MakeForFunction(D));
2001    CheckFallThroughForBody(S, D, Body, blkExpr, CD, AC);
2002  }
2003
2004  // Warning: check for unreachable code
2005  if (P.enableCheckUnreachable) {
2006    // Only check for unreachable code on non-template instantiations.
2007    // Different template instantiations can effectively change the control-flow
2008    // and it is very difficult to prove that a snippet of code in a template
2009    // is unreachable for all instantiations.
2010    bool isTemplateInstantiation = false;
2011    if (const FunctionDecl *Function = dyn_cast<FunctionDecl>(D))
2012      isTemplateInstantiation = Function->isTemplateInstantiation();
2013    if (!isTemplateInstantiation)
2014      CheckUnreachable(S, AC);
2015  }
2016
2017  // Check for thread safety violations
2018  if (P.enableThreadSafetyAnalysis) {
2019    SourceLocation FL = AC.getDecl()->getLocation();
2020    SourceLocation FEL = AC.getDecl()->getLocEnd();
2021    threadSafety::ThreadSafetyReporter Reporter(S, FL, FEL);
2022    if (!Diags.isIgnored(diag::warn_thread_safety_beta, D->getLocStart()))
2023      Reporter.setIssueBetaWarnings(true);
2024    if (!Diags.isIgnored(diag::warn_thread_safety_verbose, D->getLocStart()))
2025      Reporter.setVerbose(true);
2026
2027    threadSafety::runThreadSafetyAnalysis(AC, Reporter,
2028                                          &S.ThreadSafetyDeclCache);
2029    Reporter.emitDiagnostics();
2030  }
2031
2032  // Check for violations of consumed properties.
2033  if (P.enableConsumedAnalysis) {
2034    consumed::ConsumedWarningsHandler WarningHandler(S);
2035    consumed::ConsumedAnalyzer Analyzer(WarningHandler);
2036    Analyzer.run(AC);
2037  }
2038
2039  if (!Diags.isIgnored(diag::warn_uninit_var, D->getLocStart()) ||
2040      !Diags.isIgnored(diag::warn_sometimes_uninit_var, D->getLocStart()) ||
2041      !Diags.isIgnored(diag::warn_maybe_uninit_var, D->getLocStart())) {
2042    if (CFG *cfg = AC.getCFG()) {
2043      UninitValsDiagReporter reporter(S);
2044      UninitVariablesAnalysisStats stats;
2045      std::memset(&stats, 0, sizeof(UninitVariablesAnalysisStats));
2046      runUninitializedVariablesAnalysis(*cast<DeclContext>(D), *cfg, AC,
2047                                        reporter, stats);
2048
2049      if (S.CollectStats && stats.NumVariablesAnalyzed > 0) {
2050        ++NumUninitAnalysisFunctions;
2051        NumUninitAnalysisVariables += stats.NumVariablesAnalyzed;
2052        NumUninitAnalysisBlockVisits += stats.NumBlockVisits;
2053        MaxUninitAnalysisVariablesPerFunction =
2054            std::max(MaxUninitAnalysisVariablesPerFunction,
2055                     stats.NumVariablesAnalyzed);
2056        MaxUninitAnalysisBlockVisitsPerFunction =
2057            std::max(MaxUninitAnalysisBlockVisitsPerFunction,
2058                     stats.NumBlockVisits);
2059      }
2060    }
2061  }
2062
2063  bool FallThroughDiagFull =
2064      !Diags.isIgnored(diag::warn_unannotated_fallthrough, D->getLocStart());
2065  bool FallThroughDiagPerFunction = !Diags.isIgnored(
2066      diag::warn_unannotated_fallthrough_per_function, D->getLocStart());
2067  if (FallThroughDiagFull || FallThroughDiagPerFunction ||
2068      fscope->HasFallthroughStmt) {
2069    DiagnoseSwitchLabelsFallthrough(S, AC, !FallThroughDiagFull);
2070  }
2071
2072  if (S.getLangOpts().ObjCWeak &&
2073      !Diags.isIgnored(diag::warn_arc_repeated_use_of_weak, D->getLocStart()))
2074    diagnoseRepeatedUseOfWeak(S, fscope, D, AC.getParentMap());
2075
2076
2077  // Check for infinite self-recursion in functions
2078  if (!Diags.isIgnored(diag::warn_infinite_recursive_function,
2079                       D->getLocStart())) {
2080    if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
2081      checkRecursiveFunction(S, FD, Body, AC);
2082    }
2083  }
2084
2085  // If none of the previous checks caused a CFG build, trigger one here
2086  // for -Wtautological-overlap-compare
2087  if (!Diags.isIgnored(diag::warn_tautological_overlap_comparison,
2088                               D->getLocStart())) {
2089    AC.getCFG();
2090  }
2091
2092  // Collect statistics about the CFG if it was built.
2093  if (S.CollectStats && AC.isCFGBuilt()) {
2094    ++NumFunctionsAnalyzed;
2095    if (CFG *cfg = AC.getCFG()) {
2096      // If we successfully built a CFG for this context, record some more
2097      // detail information about it.
2098      NumCFGBlocks += cfg->getNumBlockIDs();
2099      MaxCFGBlocksPerFunction = std::max(MaxCFGBlocksPerFunction,
2100                                         cfg->getNumBlockIDs());
2101    } else {
2102      ++NumFunctionsWithBadCFGs;
2103    }
2104  }
2105}
2106
2107void clang::sema::AnalysisBasedWarnings::PrintStats() const {
2108  llvm::errs() << "\n*** Analysis Based Warnings Stats:\n";
2109
2110  unsigned NumCFGsBuilt = NumFunctionsAnalyzed - NumFunctionsWithBadCFGs;
2111  unsigned AvgCFGBlocksPerFunction =
2112      !NumCFGsBuilt ? 0 : NumCFGBlocks/NumCFGsBuilt;
2113  llvm::errs() << NumFunctionsAnalyzed << " functions analyzed ("
2114               << NumFunctionsWithBadCFGs << " w/o CFGs).\n"
2115               << "  " << NumCFGBlocks << " CFG blocks built.\n"
2116               << "  " << AvgCFGBlocksPerFunction
2117               << " average CFG blocks per function.\n"
2118               << "  " << MaxCFGBlocksPerFunction
2119               << " max CFG blocks per function.\n";
2120
2121  unsigned AvgUninitVariablesPerFunction = !NumUninitAnalysisFunctions ? 0
2122      : NumUninitAnalysisVariables/NumUninitAnalysisFunctions;
2123  unsigned AvgUninitBlockVisitsPerFunction = !NumUninitAnalysisFunctions ? 0
2124      : NumUninitAnalysisBlockVisits/NumUninitAnalysisFunctions;
2125  llvm::errs() << NumUninitAnalysisFunctions
2126               << " functions analyzed for uninitialiazed variables\n"
2127               << "  " << NumUninitAnalysisVariables << " variables analyzed.\n"
2128               << "  " << AvgUninitVariablesPerFunction
2129               << " average variables per function.\n"
2130               << "  " << MaxUninitAnalysisVariablesPerFunction
2131               << " max variables per function.\n"
2132               << "  " << NumUninitAnalysisBlockVisits << " block visits.\n"
2133               << "  " << AvgUninitBlockVisitsPerFunction
2134               << " average block visits per function.\n"
2135               << "  " << MaxUninitAnalysisBlockVisitsPerFunction
2136               << " max block visits per function.\n";
2137}
2138