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