1//===--- SemaStmt.cpp - Semantic Analysis for Statements ------------------===//
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 implements semantic analysis for statements.
11//
12//===----------------------------------------------------------------------===//
13
14#include "clang/Sema/SemaInternal.h"
15#include "clang/AST/ASTContext.h"
16#include "clang/AST/ASTDiagnostic.h"
17#include "clang/AST/CharUnits.h"
18#include "clang/AST/CXXInheritance.h"
19#include "clang/AST/DeclObjC.h"
20#include "clang/AST/EvaluatedExprVisitor.h"
21#include "clang/AST/ExprCXX.h"
22#include "clang/AST/ExprObjC.h"
23#include "clang/AST/RecursiveASTVisitor.h"
24#include "clang/AST/StmtCXX.h"
25#include "clang/AST/StmtObjC.h"
26#include "clang/AST/TypeLoc.h"
27#include "clang/AST/TypeOrdering.h"
28#include "clang/Basic/TargetInfo.h"
29#include "clang/Lex/Preprocessor.h"
30#include "clang/Sema/Initialization.h"
31#include "clang/Sema/Lookup.h"
32#include "clang/Sema/Scope.h"
33#include "clang/Sema/ScopeInfo.h"
34#include "llvm/ADT/ArrayRef.h"
35#include "llvm/ADT/DenseMap.h"
36#include "llvm/ADT/STLExtras.h"
37#include "llvm/ADT/SmallPtrSet.h"
38#include "llvm/ADT/SmallString.h"
39#include "llvm/ADT/SmallVector.h"
40
41using namespace clang;
42using namespace sema;
43
44StmtResult Sema::ActOnExprStmt(ExprResult FE) {
45  if (FE.isInvalid())
46    return StmtError();
47
48  FE = ActOnFinishFullExpr(FE.get(), FE.get()->getExprLoc(),
49                           /*DiscardedValue*/ true);
50  if (FE.isInvalid())
51    return StmtError();
52
53  // C99 6.8.3p2: The expression in an expression statement is evaluated as a
54  // void expression for its side effects.  Conversion to void allows any
55  // operand, even incomplete types.
56
57  // Same thing in for stmt first clause (when expr) and third clause.
58  return StmtResult(FE.getAs<Stmt>());
59}
60
61
62StmtResult Sema::ActOnExprStmtError() {
63  DiscardCleanupsInEvaluationContext();
64  return StmtError();
65}
66
67StmtResult Sema::ActOnNullStmt(SourceLocation SemiLoc,
68                               bool HasLeadingEmptyMacro) {
69  return new (Context) NullStmt(SemiLoc, HasLeadingEmptyMacro);
70}
71
72StmtResult Sema::ActOnDeclStmt(DeclGroupPtrTy dg, SourceLocation StartLoc,
73                               SourceLocation EndLoc) {
74  DeclGroupRef DG = dg.get();
75
76  // If we have an invalid decl, just return an error.
77  if (DG.isNull()) return StmtError();
78
79  return new (Context) DeclStmt(DG, StartLoc, EndLoc);
80}
81
82void Sema::ActOnForEachDeclStmt(DeclGroupPtrTy dg) {
83  DeclGroupRef DG = dg.get();
84
85  // If we don't have a declaration, or we have an invalid declaration,
86  // just return.
87  if (DG.isNull() || !DG.isSingleDecl())
88    return;
89
90  Decl *decl = DG.getSingleDecl();
91  if (!decl || decl->isInvalidDecl())
92    return;
93
94  // Only variable declarations are permitted.
95  VarDecl *var = dyn_cast<VarDecl>(decl);
96  if (!var) {
97    Diag(decl->getLocation(), diag::err_non_variable_decl_in_for);
98    decl->setInvalidDecl();
99    return;
100  }
101
102  // foreach variables are never actually initialized in the way that
103  // the parser came up with.
104  var->setInit(nullptr);
105
106  // In ARC, we don't need to retain the iteration variable of a fast
107  // enumeration loop.  Rather than actually trying to catch that
108  // during declaration processing, we remove the consequences here.
109  if (getLangOpts().ObjCAutoRefCount) {
110    QualType type = var->getType();
111
112    // Only do this if we inferred the lifetime.  Inferred lifetime
113    // will show up as a local qualifier because explicit lifetime
114    // should have shown up as an AttributedType instead.
115    if (type.getLocalQualifiers().getObjCLifetime() == Qualifiers::OCL_Strong) {
116      // Add 'const' and mark the variable as pseudo-strong.
117      var->setType(type.withConst());
118      var->setARCPseudoStrong(true);
119    }
120  }
121}
122
123/// \brief Diagnose unused comparisons, both builtin and overloaded operators.
124/// For '==' and '!=', suggest fixits for '=' or '|='.
125///
126/// Adding a cast to void (or other expression wrappers) will prevent the
127/// warning from firing.
128static bool DiagnoseUnusedComparison(Sema &S, const Expr *E) {
129  SourceLocation Loc;
130  bool IsNotEqual, CanAssign, IsRelational;
131
132  if (const BinaryOperator *Op = dyn_cast<BinaryOperator>(E)) {
133    if (!Op->isComparisonOp())
134      return false;
135
136    IsRelational = Op->isRelationalOp();
137    Loc = Op->getOperatorLoc();
138    IsNotEqual = Op->getOpcode() == BO_NE;
139    CanAssign = Op->getLHS()->IgnoreParenImpCasts()->isLValue();
140  } else if (const CXXOperatorCallExpr *Op = dyn_cast<CXXOperatorCallExpr>(E)) {
141    switch (Op->getOperator()) {
142    default:
143      return false;
144    case OO_EqualEqual:
145    case OO_ExclaimEqual:
146      IsRelational = false;
147      break;
148    case OO_Less:
149    case OO_Greater:
150    case OO_GreaterEqual:
151    case OO_LessEqual:
152      IsRelational = true;
153      break;
154    }
155
156    Loc = Op->getOperatorLoc();
157    IsNotEqual = Op->getOperator() == OO_ExclaimEqual;
158    CanAssign = Op->getArg(0)->IgnoreParenImpCasts()->isLValue();
159  } else {
160    // Not a typo-prone comparison.
161    return false;
162  }
163
164  // Suppress warnings when the operator, suspicious as it may be, comes from
165  // a macro expansion.
166  if (S.SourceMgr.isMacroBodyExpansion(Loc))
167    return false;
168
169  S.Diag(Loc, diag::warn_unused_comparison)
170    << (unsigned)IsRelational << (unsigned)IsNotEqual << E->getSourceRange();
171
172  // If the LHS is a plausible entity to assign to, provide a fixit hint to
173  // correct common typos.
174  if (!IsRelational && CanAssign) {
175    if (IsNotEqual)
176      S.Diag(Loc, diag::note_inequality_comparison_to_or_assign)
177        << FixItHint::CreateReplacement(Loc, "|=");
178    else
179      S.Diag(Loc, diag::note_equality_comparison_to_assign)
180        << FixItHint::CreateReplacement(Loc, "=");
181  }
182
183  return true;
184}
185
186void Sema::DiagnoseUnusedExprResult(const Stmt *S) {
187  if (const LabelStmt *Label = dyn_cast_or_null<LabelStmt>(S))
188    return DiagnoseUnusedExprResult(Label->getSubStmt());
189
190  const Expr *E = dyn_cast_or_null<Expr>(S);
191  if (!E)
192    return;
193
194  // If we are in an unevaluated expression context, then there can be no unused
195  // results because the results aren't expected to be used in the first place.
196  if (isUnevaluatedContext())
197    return;
198
199  SourceLocation ExprLoc = E->IgnoreParenImpCasts()->getExprLoc();
200  // In most cases, we don't want to warn if the expression is written in a
201  // macro body, or if the macro comes from a system header. If the offending
202  // expression is a call to a function with the warn_unused_result attribute,
203  // we warn no matter the location. Because of the order in which the various
204  // checks need to happen, we factor out the macro-related test here.
205  bool ShouldSuppress =
206      SourceMgr.isMacroBodyExpansion(ExprLoc) ||
207      SourceMgr.isInSystemMacro(ExprLoc);
208
209  const Expr *WarnExpr;
210  SourceLocation Loc;
211  SourceRange R1, R2;
212  if (!E->isUnusedResultAWarning(WarnExpr, Loc, R1, R2, Context))
213    return;
214
215  // If this is a GNU statement expression expanded from a macro, it is probably
216  // unused because it is a function-like macro that can be used as either an
217  // expression or statement.  Don't warn, because it is almost certainly a
218  // false positive.
219  if (isa<StmtExpr>(E) && Loc.isMacroID())
220    return;
221
222  // Check if this is the UNREFERENCED_PARAMETER from the Microsoft headers.
223  // That macro is frequently used to suppress "unused parameter" warnings,
224  // but its implementation makes clang's -Wunused-value fire.  Prevent this.
225  if (isa<ParenExpr>(E->IgnoreImpCasts()) && Loc.isMacroID()) {
226    SourceLocation SpellLoc = Loc;
227    if (findMacroSpelling(SpellLoc, "UNREFERENCED_PARAMETER"))
228      return;
229  }
230
231  // Okay, we have an unused result.  Depending on what the base expression is,
232  // we might want to make a more specific diagnostic.  Check for one of these
233  // cases now.
234  unsigned DiagID = diag::warn_unused_expr;
235  if (const ExprWithCleanups *Temps = dyn_cast<ExprWithCleanups>(E))
236    E = Temps->getSubExpr();
237  if (const CXXBindTemporaryExpr *TempExpr = dyn_cast<CXXBindTemporaryExpr>(E))
238    E = TempExpr->getSubExpr();
239
240  if (DiagnoseUnusedComparison(*this, E))
241    return;
242
243  E = WarnExpr;
244  if (const CallExpr *CE = dyn_cast<CallExpr>(E)) {
245    if (E->getType()->isVoidType())
246      return;
247
248    // If the callee has attribute pure, const, or warn_unused_result, warn with
249    // a more specific message to make it clear what is happening. If the call
250    // is written in a macro body, only warn if it has the warn_unused_result
251    // attribute.
252    if (const Decl *FD = CE->getCalleeDecl()) {
253      if (const Attr *A = isa<FunctionDecl>(FD)
254                              ? cast<FunctionDecl>(FD)->getUnusedResultAttr()
255                              : FD->getAttr<WarnUnusedResultAttr>()) {
256        Diag(Loc, diag::warn_unused_result) << A << R1 << R2;
257        return;
258      }
259      if (ShouldSuppress)
260        return;
261      if (FD->hasAttr<PureAttr>()) {
262        Diag(Loc, diag::warn_unused_call) << R1 << R2 << "pure";
263        return;
264      }
265      if (FD->hasAttr<ConstAttr>()) {
266        Diag(Loc, diag::warn_unused_call) << R1 << R2 << "const";
267        return;
268      }
269    }
270  } else if (ShouldSuppress)
271    return;
272
273  if (const ObjCMessageExpr *ME = dyn_cast<ObjCMessageExpr>(E)) {
274    if (getLangOpts().ObjCAutoRefCount && ME->isDelegateInitCall()) {
275      Diag(Loc, diag::err_arc_unused_init_message) << R1;
276      return;
277    }
278    const ObjCMethodDecl *MD = ME->getMethodDecl();
279    if (MD) {
280      if (const auto *A = MD->getAttr<WarnUnusedResultAttr>()) {
281        Diag(Loc, diag::warn_unused_result) << A << R1 << R2;
282        return;
283      }
284    }
285  } else if (const PseudoObjectExpr *POE = dyn_cast<PseudoObjectExpr>(E)) {
286    const Expr *Source = POE->getSyntacticForm();
287    if (isa<ObjCSubscriptRefExpr>(Source))
288      DiagID = diag::warn_unused_container_subscript_expr;
289    else
290      DiagID = diag::warn_unused_property_expr;
291  } else if (const CXXFunctionalCastExpr *FC
292                                       = dyn_cast<CXXFunctionalCastExpr>(E)) {
293    if (isa<CXXConstructExpr>(FC->getSubExpr()) ||
294        isa<CXXTemporaryObjectExpr>(FC->getSubExpr()))
295      return;
296  }
297  // Diagnose "(void*) blah" as a typo for "(void) blah".
298  else if (const CStyleCastExpr *CE = dyn_cast<CStyleCastExpr>(E)) {
299    TypeSourceInfo *TI = CE->getTypeInfoAsWritten();
300    QualType T = TI->getType();
301
302    // We really do want to use the non-canonical type here.
303    if (T == Context.VoidPtrTy) {
304      PointerTypeLoc TL = TI->getTypeLoc().castAs<PointerTypeLoc>();
305
306      Diag(Loc, diag::warn_unused_voidptr)
307        << FixItHint::CreateRemoval(TL.getStarLoc());
308      return;
309    }
310  }
311
312  if (E->isGLValue() && E->getType().isVolatileQualified()) {
313    Diag(Loc, diag::warn_unused_volatile) << R1 << R2;
314    return;
315  }
316
317  DiagRuntimeBehavior(Loc, nullptr, PDiag(DiagID) << R1 << R2);
318}
319
320void Sema::ActOnStartOfCompoundStmt() {
321  PushCompoundScope();
322}
323
324void Sema::ActOnFinishOfCompoundStmt() {
325  PopCompoundScope();
326}
327
328sema::CompoundScopeInfo &Sema::getCurCompoundScope() const {
329  return getCurFunction()->CompoundScopes.back();
330}
331
332StmtResult Sema::ActOnCompoundStmt(SourceLocation L, SourceLocation R,
333                                   ArrayRef<Stmt *> Elts, bool isStmtExpr) {
334  const unsigned NumElts = Elts.size();
335
336  // If we're in C89 mode, check that we don't have any decls after stmts.  If
337  // so, emit an extension diagnostic.
338  if (!getLangOpts().C99 && !getLangOpts().CPlusPlus) {
339    // Note that __extension__ can be around a decl.
340    unsigned i = 0;
341    // Skip over all declarations.
342    for (; i != NumElts && isa<DeclStmt>(Elts[i]); ++i)
343      /*empty*/;
344
345    // We found the end of the list or a statement.  Scan for another declstmt.
346    for (; i != NumElts && !isa<DeclStmt>(Elts[i]); ++i)
347      /*empty*/;
348
349    if (i != NumElts) {
350      Decl *D = *cast<DeclStmt>(Elts[i])->decl_begin();
351      Diag(D->getLocation(), diag::ext_mixed_decls_code);
352    }
353  }
354  // Warn about unused expressions in statements.
355  for (unsigned i = 0; i != NumElts; ++i) {
356    // Ignore statements that are last in a statement expression.
357    if (isStmtExpr && i == NumElts - 1)
358      continue;
359
360    DiagnoseUnusedExprResult(Elts[i]);
361  }
362
363  // Check for suspicious empty body (null statement) in `for' and `while'
364  // statements.  Don't do anything for template instantiations, this just adds
365  // noise.
366  if (NumElts != 0 && !CurrentInstantiationScope &&
367      getCurCompoundScope().HasEmptyLoopBodies) {
368    for (unsigned i = 0; i != NumElts - 1; ++i)
369      DiagnoseEmptyLoopBody(Elts[i], Elts[i + 1]);
370  }
371
372  return new (Context) CompoundStmt(Context, Elts, L, R);
373}
374
375StmtResult
376Sema::ActOnCaseStmt(SourceLocation CaseLoc, Expr *LHSVal,
377                    SourceLocation DotDotDotLoc, Expr *RHSVal,
378                    SourceLocation ColonLoc) {
379  assert(LHSVal && "missing expression in case statement");
380
381  if (getCurFunction()->SwitchStack.empty()) {
382    Diag(CaseLoc, diag::err_case_not_in_switch);
383    return StmtError();
384  }
385
386  ExprResult LHS =
387      CorrectDelayedTyposInExpr(LHSVal, [this](class Expr *E) {
388        if (!getLangOpts().CPlusPlus11)
389          return VerifyIntegerConstantExpression(E);
390        if (Expr *CondExpr =
391                getCurFunction()->SwitchStack.back()->getCond()) {
392          QualType CondType = CondExpr->getType();
393          llvm::APSInt TempVal;
394          return CheckConvertedConstantExpression(E, CondType, TempVal,
395                                                        CCEK_CaseValue);
396        }
397        return ExprError();
398      });
399  if (LHS.isInvalid())
400    return StmtError();
401  LHSVal = LHS.get();
402
403  if (!getLangOpts().CPlusPlus11) {
404    // C99 6.8.4.2p3: The expression shall be an integer constant.
405    // However, GCC allows any evaluatable integer expression.
406    if (!LHSVal->isTypeDependent() && !LHSVal->isValueDependent()) {
407      LHSVal = VerifyIntegerConstantExpression(LHSVal).get();
408      if (!LHSVal)
409        return StmtError();
410    }
411
412    // GCC extension: The expression shall be an integer constant.
413
414    if (RHSVal && !RHSVal->isTypeDependent() && !RHSVal->isValueDependent()) {
415      RHSVal = VerifyIntegerConstantExpression(RHSVal).get();
416      // Recover from an error by just forgetting about it.
417    }
418  }
419
420  LHS = ActOnFinishFullExpr(LHSVal, LHSVal->getExprLoc(), false,
421                                 getLangOpts().CPlusPlus11);
422  if (LHS.isInvalid())
423    return StmtError();
424
425  auto RHS = RHSVal ? ActOnFinishFullExpr(RHSVal, RHSVal->getExprLoc(), false,
426                                          getLangOpts().CPlusPlus11)
427                    : ExprResult();
428  if (RHS.isInvalid())
429    return StmtError();
430
431  CaseStmt *CS = new (Context)
432      CaseStmt(LHS.get(), RHS.get(), CaseLoc, DotDotDotLoc, ColonLoc);
433  getCurFunction()->SwitchStack.back()->addSwitchCase(CS);
434  return CS;
435}
436
437/// ActOnCaseStmtBody - This installs a statement as the body of a case.
438void Sema::ActOnCaseStmtBody(Stmt *caseStmt, Stmt *SubStmt) {
439  DiagnoseUnusedExprResult(SubStmt);
440
441  CaseStmt *CS = static_cast<CaseStmt*>(caseStmt);
442  CS->setSubStmt(SubStmt);
443}
444
445StmtResult
446Sema::ActOnDefaultStmt(SourceLocation DefaultLoc, SourceLocation ColonLoc,
447                       Stmt *SubStmt, Scope *CurScope) {
448  DiagnoseUnusedExprResult(SubStmt);
449
450  if (getCurFunction()->SwitchStack.empty()) {
451    Diag(DefaultLoc, diag::err_default_not_in_switch);
452    return SubStmt;
453  }
454
455  DefaultStmt *DS = new (Context) DefaultStmt(DefaultLoc, ColonLoc, SubStmt);
456  getCurFunction()->SwitchStack.back()->addSwitchCase(DS);
457  return DS;
458}
459
460StmtResult
461Sema::ActOnLabelStmt(SourceLocation IdentLoc, LabelDecl *TheDecl,
462                     SourceLocation ColonLoc, Stmt *SubStmt) {
463  // If the label was multiply defined, reject it now.
464  if (TheDecl->getStmt()) {
465    Diag(IdentLoc, diag::err_redefinition_of_label) << TheDecl->getDeclName();
466    Diag(TheDecl->getLocation(), diag::note_previous_definition);
467    return SubStmt;
468  }
469
470  // Otherwise, things are good.  Fill in the declaration and return it.
471  LabelStmt *LS = new (Context) LabelStmt(IdentLoc, TheDecl, SubStmt);
472  TheDecl->setStmt(LS);
473  if (!TheDecl->isGnuLocal()) {
474    TheDecl->setLocStart(IdentLoc);
475    if (!TheDecl->isMSAsmLabel()) {
476      // Don't update the location of MS ASM labels.  These will result in
477      // a diagnostic, and changing the location here will mess that up.
478      TheDecl->setLocation(IdentLoc);
479    }
480  }
481  return LS;
482}
483
484StmtResult Sema::ActOnAttributedStmt(SourceLocation AttrLoc,
485                                     ArrayRef<const Attr*> Attrs,
486                                     Stmt *SubStmt) {
487  // Fill in the declaration and return it.
488  AttributedStmt *LS = AttributedStmt::Create(Context, AttrLoc, Attrs, SubStmt);
489  return LS;
490}
491
492namespace {
493class CommaVisitor : public EvaluatedExprVisitor<CommaVisitor> {
494  typedef EvaluatedExprVisitor<CommaVisitor> Inherited;
495  Sema &SemaRef;
496public:
497  CommaVisitor(Sema &SemaRef) : Inherited(SemaRef.Context), SemaRef(SemaRef) {}
498  void VisitBinaryOperator(BinaryOperator *E) {
499    if (E->getOpcode() == BO_Comma)
500      SemaRef.DiagnoseCommaOperator(E->getLHS(), E->getExprLoc());
501    EvaluatedExprVisitor<CommaVisitor>::VisitBinaryOperator(E);
502  }
503};
504}
505
506StmtResult
507Sema::ActOnIfStmt(SourceLocation IfLoc, bool IsConstexpr, Stmt *InitStmt,
508                  ConditionResult Cond,
509                  Stmt *thenStmt, SourceLocation ElseLoc,
510                  Stmt *elseStmt) {
511  if (Cond.isInvalid())
512    Cond = ConditionResult(
513        *this, nullptr,
514        MakeFullExpr(new (Context) OpaqueValueExpr(SourceLocation(),
515                                                   Context.BoolTy, VK_RValue),
516                     IfLoc),
517        false);
518
519  Expr *CondExpr = Cond.get().second;
520  if (!Diags.isIgnored(diag::warn_comma_operator,
521                       CondExpr->getExprLoc()))
522    CommaVisitor(*this).Visit(CondExpr);
523
524  if (!elseStmt)
525    DiagnoseEmptyStmtBody(CondExpr->getLocEnd(), thenStmt,
526                          diag::warn_empty_if_body);
527
528  return BuildIfStmt(IfLoc, IsConstexpr, InitStmt, Cond, thenStmt, ElseLoc,
529                     elseStmt);
530}
531
532StmtResult Sema::BuildIfStmt(SourceLocation IfLoc, bool IsConstexpr,
533                             Stmt *InitStmt, ConditionResult Cond,
534                             Stmt *thenStmt, SourceLocation ElseLoc,
535                             Stmt *elseStmt) {
536  if (Cond.isInvalid())
537    return StmtError();
538
539  if (IsConstexpr)
540    getCurFunction()->setHasBranchProtectedScope();
541
542  DiagnoseUnusedExprResult(thenStmt);
543  DiagnoseUnusedExprResult(elseStmt);
544
545  return new (Context)
546      IfStmt(Context, IfLoc, IsConstexpr, InitStmt, Cond.get().first,
547             Cond.get().second, thenStmt, ElseLoc, elseStmt);
548}
549
550namespace {
551  struct CaseCompareFunctor {
552    bool operator()(const std::pair<llvm::APSInt, CaseStmt*> &LHS,
553                    const llvm::APSInt &RHS) {
554      return LHS.first < RHS;
555    }
556    bool operator()(const std::pair<llvm::APSInt, CaseStmt*> &LHS,
557                    const std::pair<llvm::APSInt, CaseStmt*> &RHS) {
558      return LHS.first < RHS.first;
559    }
560    bool operator()(const llvm::APSInt &LHS,
561                    const std::pair<llvm::APSInt, CaseStmt*> &RHS) {
562      return LHS < RHS.first;
563    }
564  };
565}
566
567/// CmpCaseVals - Comparison predicate for sorting case values.
568///
569static bool CmpCaseVals(const std::pair<llvm::APSInt, CaseStmt*>& lhs,
570                        const std::pair<llvm::APSInt, CaseStmt*>& rhs) {
571  if (lhs.first < rhs.first)
572    return true;
573
574  if (lhs.first == rhs.first &&
575      lhs.second->getCaseLoc().getRawEncoding()
576       < rhs.second->getCaseLoc().getRawEncoding())
577    return true;
578  return false;
579}
580
581/// CmpEnumVals - Comparison predicate for sorting enumeration values.
582///
583static bool CmpEnumVals(const std::pair<llvm::APSInt, EnumConstantDecl*>& lhs,
584                        const std::pair<llvm::APSInt, EnumConstantDecl*>& rhs)
585{
586  return lhs.first < rhs.first;
587}
588
589/// EqEnumVals - Comparison preficate for uniqing enumeration values.
590///
591static bool EqEnumVals(const std::pair<llvm::APSInt, EnumConstantDecl*>& lhs,
592                       const std::pair<llvm::APSInt, EnumConstantDecl*>& rhs)
593{
594  return lhs.first == rhs.first;
595}
596
597/// GetTypeBeforeIntegralPromotion - Returns the pre-promotion type of
598/// potentially integral-promoted expression @p expr.
599static QualType GetTypeBeforeIntegralPromotion(Expr *&expr) {
600  if (ExprWithCleanups *cleanups = dyn_cast<ExprWithCleanups>(expr))
601    expr = cleanups->getSubExpr();
602  while (ImplicitCastExpr *impcast = dyn_cast<ImplicitCastExpr>(expr)) {
603    if (impcast->getCastKind() != CK_IntegralCast) break;
604    expr = impcast->getSubExpr();
605  }
606  return expr->getType();
607}
608
609ExprResult Sema::CheckSwitchCondition(SourceLocation SwitchLoc, Expr *Cond) {
610  class SwitchConvertDiagnoser : public ICEConvertDiagnoser {
611    Expr *Cond;
612
613  public:
614    SwitchConvertDiagnoser(Expr *Cond)
615        : ICEConvertDiagnoser(/*AllowScopedEnumerations*/true, false, true),
616          Cond(Cond) {}
617
618    SemaDiagnosticBuilder diagnoseNotInt(Sema &S, SourceLocation Loc,
619                                         QualType T) override {
620      return S.Diag(Loc, diag::err_typecheck_statement_requires_integer) << T;
621    }
622
623    SemaDiagnosticBuilder diagnoseIncomplete(
624        Sema &S, SourceLocation Loc, QualType T) override {
625      return S.Diag(Loc, diag::err_switch_incomplete_class_type)
626               << T << Cond->getSourceRange();
627    }
628
629    SemaDiagnosticBuilder diagnoseExplicitConv(
630        Sema &S, SourceLocation Loc, QualType T, QualType ConvTy) override {
631      return S.Diag(Loc, diag::err_switch_explicit_conversion) << T << ConvTy;
632    }
633
634    SemaDiagnosticBuilder noteExplicitConv(
635        Sema &S, CXXConversionDecl *Conv, QualType ConvTy) override {
636      return S.Diag(Conv->getLocation(), diag::note_switch_conversion)
637        << ConvTy->isEnumeralType() << ConvTy;
638    }
639
640    SemaDiagnosticBuilder diagnoseAmbiguous(Sema &S, SourceLocation Loc,
641                                            QualType T) override {
642      return S.Diag(Loc, diag::err_switch_multiple_conversions) << T;
643    }
644
645    SemaDiagnosticBuilder noteAmbiguous(
646        Sema &S, CXXConversionDecl *Conv, QualType ConvTy) override {
647      return S.Diag(Conv->getLocation(), diag::note_switch_conversion)
648      << ConvTy->isEnumeralType() << ConvTy;
649    }
650
651    SemaDiagnosticBuilder diagnoseConversion(
652        Sema &S, SourceLocation Loc, QualType T, QualType ConvTy) override {
653      llvm_unreachable("conversion functions are permitted");
654    }
655  } SwitchDiagnoser(Cond);
656
657  ExprResult CondResult =
658      PerformContextualImplicitConversion(SwitchLoc, Cond, SwitchDiagnoser);
659  if (CondResult.isInvalid())
660    return ExprError();
661
662  // C99 6.8.4.2p5 - Integer promotions are performed on the controlling expr.
663  return UsualUnaryConversions(CondResult.get());
664}
665
666StmtResult Sema::ActOnStartOfSwitchStmt(SourceLocation SwitchLoc,
667                                        Stmt *InitStmt, ConditionResult Cond) {
668  if (Cond.isInvalid())
669    return StmtError();
670
671  getCurFunction()->setHasBranchIntoScope();
672
673  SwitchStmt *SS = new (Context)
674      SwitchStmt(Context, InitStmt, Cond.get().first, Cond.get().second);
675  getCurFunction()->SwitchStack.push_back(SS);
676  return SS;
677}
678
679static void AdjustAPSInt(llvm::APSInt &Val, unsigned BitWidth, bool IsSigned) {
680  Val = Val.extOrTrunc(BitWidth);
681  Val.setIsSigned(IsSigned);
682}
683
684/// Check the specified case value is in range for the given unpromoted switch
685/// type.
686static void checkCaseValue(Sema &S, SourceLocation Loc, const llvm::APSInt &Val,
687                           unsigned UnpromotedWidth, bool UnpromotedSign) {
688  // If the case value was signed and negative and the switch expression is
689  // unsigned, don't bother to warn: this is implementation-defined behavior.
690  // FIXME: Introduce a second, default-ignored warning for this case?
691  if (UnpromotedWidth < Val.getBitWidth()) {
692    llvm::APSInt ConvVal(Val);
693    AdjustAPSInt(ConvVal, UnpromotedWidth, UnpromotedSign);
694    AdjustAPSInt(ConvVal, Val.getBitWidth(), Val.isSigned());
695    // FIXME: Use different diagnostics for overflow  in conversion to promoted
696    // type versus "switch expression cannot have this value". Use proper
697    // IntRange checking rather than just looking at the unpromoted type here.
698    if (ConvVal != Val)
699      S.Diag(Loc, diag::warn_case_value_overflow) << Val.toString(10)
700                                                  << ConvVal.toString(10);
701  }
702}
703
704typedef SmallVector<std::pair<llvm::APSInt, EnumConstantDecl*>, 64> EnumValsTy;
705
706/// Returns true if we should emit a diagnostic about this case expression not
707/// being a part of the enum used in the switch controlling expression.
708static bool ShouldDiagnoseSwitchCaseNotInEnum(const Sema &S,
709                                              const EnumDecl *ED,
710                                              const Expr *CaseExpr,
711                                              EnumValsTy::iterator &EI,
712                                              EnumValsTy::iterator &EIEnd,
713                                              const llvm::APSInt &Val) {
714  if (const DeclRefExpr *DRE =
715          dyn_cast<DeclRefExpr>(CaseExpr->IgnoreParenImpCasts())) {
716    if (const VarDecl *VD = dyn_cast<VarDecl>(DRE->getDecl())) {
717      QualType VarType = VD->getType();
718      QualType EnumType = S.Context.getTypeDeclType(ED);
719      if (VD->hasGlobalStorage() && VarType.isConstQualified() &&
720          S.Context.hasSameUnqualifiedType(EnumType, VarType))
721        return false;
722    }
723  }
724
725  if (ED->hasAttr<FlagEnumAttr>()) {
726    return !S.IsValueInFlagEnum(ED, Val, false);
727  } else {
728    while (EI != EIEnd && EI->first < Val)
729      EI++;
730
731    if (EI != EIEnd && EI->first == Val)
732      return false;
733  }
734
735  return true;
736}
737
738StmtResult
739Sema::ActOnFinishSwitchStmt(SourceLocation SwitchLoc, Stmt *Switch,
740                            Stmt *BodyStmt) {
741  SwitchStmt *SS = cast<SwitchStmt>(Switch);
742  assert(SS == getCurFunction()->SwitchStack.back() &&
743         "switch stack missing push/pop!");
744
745  getCurFunction()->SwitchStack.pop_back();
746
747  if (!BodyStmt) return StmtError();
748  SS->setBody(BodyStmt, SwitchLoc);
749
750  Expr *CondExpr = SS->getCond();
751  if (!CondExpr) return StmtError();
752
753  QualType CondType = CondExpr->getType();
754
755  Expr *CondExprBeforePromotion = CondExpr;
756  QualType CondTypeBeforePromotion =
757      GetTypeBeforeIntegralPromotion(CondExprBeforePromotion);
758
759  // C++ 6.4.2.p2:
760  // Integral promotions are performed (on the switch condition).
761  //
762  // A case value unrepresentable by the original switch condition
763  // type (before the promotion) doesn't make sense, even when it can
764  // be represented by the promoted type.  Therefore we need to find
765  // the pre-promotion type of the switch condition.
766  if (!CondExpr->isTypeDependent()) {
767    // We have already converted the expression to an integral or enumeration
768    // type, when we started the switch statement. If we don't have an
769    // appropriate type now, just return an error.
770    if (!CondType->isIntegralOrEnumerationType())
771      return StmtError();
772
773    if (CondExpr->isKnownToHaveBooleanValue()) {
774      // switch(bool_expr) {...} is often a programmer error, e.g.
775      //   switch(n && mask) { ... }  // Doh - should be "n & mask".
776      // One can always use an if statement instead of switch(bool_expr).
777      Diag(SwitchLoc, diag::warn_bool_switch_condition)
778          << CondExpr->getSourceRange();
779    }
780  }
781
782  // Get the bitwidth of the switched-on value after promotions. We must
783  // convert the integer case values to this width before comparison.
784  bool HasDependentValue
785    = CondExpr->isTypeDependent() || CondExpr->isValueDependent();
786  unsigned CondWidth = HasDependentValue ? 0 : Context.getIntWidth(CondType);
787  bool CondIsSigned = CondType->isSignedIntegerOrEnumerationType();
788
789  // Get the width and signedness that the condition might actually have, for
790  // warning purposes.
791  // FIXME: Grab an IntRange for the condition rather than using the unpromoted
792  // type.
793  unsigned CondWidthBeforePromotion
794    = HasDependentValue ? 0 : Context.getIntWidth(CondTypeBeforePromotion);
795  bool CondIsSignedBeforePromotion
796    = CondTypeBeforePromotion->isSignedIntegerOrEnumerationType();
797
798  // Accumulate all of the case values in a vector so that we can sort them
799  // and detect duplicates.  This vector contains the APInt for the case after
800  // it has been converted to the condition type.
801  typedef SmallVector<std::pair<llvm::APSInt, CaseStmt*>, 64> CaseValsTy;
802  CaseValsTy CaseVals;
803
804  // Keep track of any GNU case ranges we see.  The APSInt is the low value.
805  typedef std::vector<std::pair<llvm::APSInt, CaseStmt*> > CaseRangesTy;
806  CaseRangesTy CaseRanges;
807
808  DefaultStmt *TheDefaultStmt = nullptr;
809
810  bool CaseListIsErroneous = false;
811
812  for (SwitchCase *SC = SS->getSwitchCaseList(); SC && !HasDependentValue;
813       SC = SC->getNextSwitchCase()) {
814
815    if (DefaultStmt *DS = dyn_cast<DefaultStmt>(SC)) {
816      if (TheDefaultStmt) {
817        Diag(DS->getDefaultLoc(), diag::err_multiple_default_labels_defined);
818        Diag(TheDefaultStmt->getDefaultLoc(), diag::note_duplicate_case_prev);
819
820        // FIXME: Remove the default statement from the switch block so that
821        // we'll return a valid AST.  This requires recursing down the AST and
822        // finding it, not something we are set up to do right now.  For now,
823        // just lop the entire switch stmt out of the AST.
824        CaseListIsErroneous = true;
825      }
826      TheDefaultStmt = DS;
827
828    } else {
829      CaseStmt *CS = cast<CaseStmt>(SC);
830
831      Expr *Lo = CS->getLHS();
832
833      if (Lo->isTypeDependent() || Lo->isValueDependent()) {
834        HasDependentValue = true;
835        break;
836      }
837
838      llvm::APSInt LoVal;
839
840      if (getLangOpts().CPlusPlus11) {
841        // C++11 [stmt.switch]p2: the constant-expression shall be a converted
842        // constant expression of the promoted type of the switch condition.
843        ExprResult ConvLo =
844          CheckConvertedConstantExpression(Lo, CondType, LoVal, CCEK_CaseValue);
845        if (ConvLo.isInvalid()) {
846          CaseListIsErroneous = true;
847          continue;
848        }
849        Lo = ConvLo.get();
850      } else {
851        // We already verified that the expression has a i-c-e value (C99
852        // 6.8.4.2p3) - get that value now.
853        LoVal = Lo->EvaluateKnownConstInt(Context);
854
855        // If the LHS is not the same type as the condition, insert an implicit
856        // cast.
857        Lo = DefaultLvalueConversion(Lo).get();
858        Lo = ImpCastExprToType(Lo, CondType, CK_IntegralCast).get();
859      }
860
861      // Check the unconverted value is within the range of possible values of
862      // the switch expression.
863      checkCaseValue(*this, Lo->getLocStart(), LoVal,
864                     CondWidthBeforePromotion, CondIsSignedBeforePromotion);
865
866      // Convert the value to the same width/sign as the condition.
867      AdjustAPSInt(LoVal, CondWidth, CondIsSigned);
868
869      CS->setLHS(Lo);
870
871      // If this is a case range, remember it in CaseRanges, otherwise CaseVals.
872      if (CS->getRHS()) {
873        if (CS->getRHS()->isTypeDependent() ||
874            CS->getRHS()->isValueDependent()) {
875          HasDependentValue = true;
876          break;
877        }
878        CaseRanges.push_back(std::make_pair(LoVal, CS));
879      } else
880        CaseVals.push_back(std::make_pair(LoVal, CS));
881    }
882  }
883
884  if (!HasDependentValue) {
885    // If we don't have a default statement, check whether the
886    // condition is constant.
887    llvm::APSInt ConstantCondValue;
888    bool HasConstantCond = false;
889    if (!HasDependentValue && !TheDefaultStmt) {
890      HasConstantCond = CondExpr->EvaluateAsInt(ConstantCondValue, Context,
891                                                Expr::SE_AllowSideEffects);
892      assert(!HasConstantCond ||
893             (ConstantCondValue.getBitWidth() == CondWidth &&
894              ConstantCondValue.isSigned() == CondIsSigned));
895    }
896    bool ShouldCheckConstantCond = HasConstantCond;
897
898    // Sort all the scalar case values so we can easily detect duplicates.
899    std::stable_sort(CaseVals.begin(), CaseVals.end(), CmpCaseVals);
900
901    if (!CaseVals.empty()) {
902      for (unsigned i = 0, e = CaseVals.size(); i != e; ++i) {
903        if (ShouldCheckConstantCond &&
904            CaseVals[i].first == ConstantCondValue)
905          ShouldCheckConstantCond = false;
906
907        if (i != 0 && CaseVals[i].first == CaseVals[i-1].first) {
908          // If we have a duplicate, report it.
909          // First, determine if either case value has a name
910          StringRef PrevString, CurrString;
911          Expr *PrevCase = CaseVals[i-1].second->getLHS()->IgnoreParenCasts();
912          Expr *CurrCase = CaseVals[i].second->getLHS()->IgnoreParenCasts();
913          if (DeclRefExpr *DeclRef = dyn_cast<DeclRefExpr>(PrevCase)) {
914            PrevString = DeclRef->getDecl()->getName();
915          }
916          if (DeclRefExpr *DeclRef = dyn_cast<DeclRefExpr>(CurrCase)) {
917            CurrString = DeclRef->getDecl()->getName();
918          }
919          SmallString<16> CaseValStr;
920          CaseVals[i-1].first.toString(CaseValStr);
921
922          if (PrevString == CurrString)
923            Diag(CaseVals[i].second->getLHS()->getLocStart(),
924                 diag::err_duplicate_case) <<
925                 (PrevString.empty() ? StringRef(CaseValStr) : PrevString);
926          else
927            Diag(CaseVals[i].second->getLHS()->getLocStart(),
928                 diag::err_duplicate_case_differing_expr) <<
929                 (PrevString.empty() ? StringRef(CaseValStr) : PrevString) <<
930                 (CurrString.empty() ? StringRef(CaseValStr) : CurrString) <<
931                 CaseValStr;
932
933          Diag(CaseVals[i-1].second->getLHS()->getLocStart(),
934               diag::note_duplicate_case_prev);
935          // FIXME: We really want to remove the bogus case stmt from the
936          // substmt, but we have no way to do this right now.
937          CaseListIsErroneous = true;
938        }
939      }
940    }
941
942    // Detect duplicate case ranges, which usually don't exist at all in
943    // the first place.
944    if (!CaseRanges.empty()) {
945      // Sort all the case ranges by their low value so we can easily detect
946      // overlaps between ranges.
947      std::stable_sort(CaseRanges.begin(), CaseRanges.end());
948
949      // Scan the ranges, computing the high values and removing empty ranges.
950      std::vector<llvm::APSInt> HiVals;
951      for (unsigned i = 0, e = CaseRanges.size(); i != e; ++i) {
952        llvm::APSInt &LoVal = CaseRanges[i].first;
953        CaseStmt *CR = CaseRanges[i].second;
954        Expr *Hi = CR->getRHS();
955        llvm::APSInt HiVal;
956
957        if (getLangOpts().CPlusPlus11) {
958          // C++11 [stmt.switch]p2: the constant-expression shall be a converted
959          // constant expression of the promoted type of the switch condition.
960          ExprResult ConvHi =
961            CheckConvertedConstantExpression(Hi, CondType, HiVal,
962                                             CCEK_CaseValue);
963          if (ConvHi.isInvalid()) {
964            CaseListIsErroneous = true;
965            continue;
966          }
967          Hi = ConvHi.get();
968        } else {
969          HiVal = Hi->EvaluateKnownConstInt(Context);
970
971          // If the RHS is not the same type as the condition, insert an
972          // implicit cast.
973          Hi = DefaultLvalueConversion(Hi).get();
974          Hi = ImpCastExprToType(Hi, CondType, CK_IntegralCast).get();
975        }
976
977        // Check the unconverted value is within the range of possible values of
978        // the switch expression.
979        checkCaseValue(*this, Hi->getLocStart(), HiVal,
980                       CondWidthBeforePromotion, CondIsSignedBeforePromotion);
981
982        // Convert the value to the same width/sign as the condition.
983        AdjustAPSInt(HiVal, CondWidth, CondIsSigned);
984
985        CR->setRHS(Hi);
986
987        // If the low value is bigger than the high value, the case is empty.
988        if (LoVal > HiVal) {
989          Diag(CR->getLHS()->getLocStart(), diag::warn_case_empty_range)
990            << SourceRange(CR->getLHS()->getLocStart(),
991                           Hi->getLocEnd());
992          CaseRanges.erase(CaseRanges.begin()+i);
993          --i;
994          --e;
995          continue;
996        }
997
998        if (ShouldCheckConstantCond &&
999            LoVal <= ConstantCondValue &&
1000            ConstantCondValue <= HiVal)
1001          ShouldCheckConstantCond = false;
1002
1003        HiVals.push_back(HiVal);
1004      }
1005
1006      // Rescan the ranges, looking for overlap with singleton values and other
1007      // ranges.  Since the range list is sorted, we only need to compare case
1008      // ranges with their neighbors.
1009      for (unsigned i = 0, e = CaseRanges.size(); i != e; ++i) {
1010        llvm::APSInt &CRLo = CaseRanges[i].first;
1011        llvm::APSInt &CRHi = HiVals[i];
1012        CaseStmt *CR = CaseRanges[i].second;
1013
1014        // Check to see whether the case range overlaps with any
1015        // singleton cases.
1016        CaseStmt *OverlapStmt = nullptr;
1017        llvm::APSInt OverlapVal(32);
1018
1019        // Find the smallest value >= the lower bound.  If I is in the
1020        // case range, then we have overlap.
1021        CaseValsTy::iterator I = std::lower_bound(CaseVals.begin(),
1022                                                  CaseVals.end(), CRLo,
1023                                                  CaseCompareFunctor());
1024        if (I != CaseVals.end() && I->first < CRHi) {
1025          OverlapVal  = I->first;   // Found overlap with scalar.
1026          OverlapStmt = I->second;
1027        }
1028
1029        // Find the smallest value bigger than the upper bound.
1030        I = std::upper_bound(I, CaseVals.end(), CRHi, CaseCompareFunctor());
1031        if (I != CaseVals.begin() && (I-1)->first >= CRLo) {
1032          OverlapVal  = (I-1)->first;      // Found overlap with scalar.
1033          OverlapStmt = (I-1)->second;
1034        }
1035
1036        // Check to see if this case stmt overlaps with the subsequent
1037        // case range.
1038        if (i && CRLo <= HiVals[i-1]) {
1039          OverlapVal  = HiVals[i-1];       // Found overlap with range.
1040          OverlapStmt = CaseRanges[i-1].second;
1041        }
1042
1043        if (OverlapStmt) {
1044          // If we have a duplicate, report it.
1045          Diag(CR->getLHS()->getLocStart(), diag::err_duplicate_case)
1046            << OverlapVal.toString(10);
1047          Diag(OverlapStmt->getLHS()->getLocStart(),
1048               diag::note_duplicate_case_prev);
1049          // FIXME: We really want to remove the bogus case stmt from the
1050          // substmt, but we have no way to do this right now.
1051          CaseListIsErroneous = true;
1052        }
1053      }
1054    }
1055
1056    // Complain if we have a constant condition and we didn't find a match.
1057    if (!CaseListIsErroneous && ShouldCheckConstantCond) {
1058      // TODO: it would be nice if we printed enums as enums, chars as
1059      // chars, etc.
1060      Diag(CondExpr->getExprLoc(), diag::warn_missing_case_for_condition)
1061        << ConstantCondValue.toString(10)
1062        << CondExpr->getSourceRange();
1063    }
1064
1065    // Check to see if switch is over an Enum and handles all of its
1066    // values.  We only issue a warning if there is not 'default:', but
1067    // we still do the analysis to preserve this information in the AST
1068    // (which can be used by flow-based analyes).
1069    //
1070    const EnumType *ET = CondTypeBeforePromotion->getAs<EnumType>();
1071
1072    // If switch has default case, then ignore it.
1073    if (!CaseListIsErroneous  && !HasConstantCond && ET) {
1074      const EnumDecl *ED = ET->getDecl();
1075      EnumValsTy EnumVals;
1076
1077      // Gather all enum values, set their type and sort them,
1078      // allowing easier comparison with CaseVals.
1079      for (auto *EDI : ED->enumerators()) {
1080        llvm::APSInt Val = EDI->getInitVal();
1081        AdjustAPSInt(Val, CondWidth, CondIsSigned);
1082        EnumVals.push_back(std::make_pair(Val, EDI));
1083      }
1084      std::stable_sort(EnumVals.begin(), EnumVals.end(), CmpEnumVals);
1085      auto EI = EnumVals.begin(), EIEnd =
1086        std::unique(EnumVals.begin(), EnumVals.end(), EqEnumVals);
1087
1088      // See which case values aren't in enum.
1089      for (CaseValsTy::const_iterator CI = CaseVals.begin();
1090          CI != CaseVals.end(); CI++) {
1091        Expr *CaseExpr = CI->second->getLHS();
1092        if (ShouldDiagnoseSwitchCaseNotInEnum(*this, ED, CaseExpr, EI, EIEnd,
1093                                              CI->first))
1094          Diag(CaseExpr->getExprLoc(), diag::warn_not_in_enum)
1095            << CondTypeBeforePromotion;
1096      }
1097
1098      // See which of case ranges aren't in enum
1099      EI = EnumVals.begin();
1100      for (CaseRangesTy::const_iterator RI = CaseRanges.begin();
1101          RI != CaseRanges.end(); RI++) {
1102        Expr *CaseExpr = RI->second->getLHS();
1103        if (ShouldDiagnoseSwitchCaseNotInEnum(*this, ED, CaseExpr, EI, EIEnd,
1104                                              RI->first))
1105          Diag(CaseExpr->getExprLoc(), diag::warn_not_in_enum)
1106            << CondTypeBeforePromotion;
1107
1108        llvm::APSInt Hi =
1109          RI->second->getRHS()->EvaluateKnownConstInt(Context);
1110        AdjustAPSInt(Hi, CondWidth, CondIsSigned);
1111
1112        CaseExpr = RI->second->getRHS();
1113        if (ShouldDiagnoseSwitchCaseNotInEnum(*this, ED, CaseExpr, EI, EIEnd,
1114                                              Hi))
1115          Diag(CaseExpr->getExprLoc(), diag::warn_not_in_enum)
1116            << CondTypeBeforePromotion;
1117      }
1118
1119      // Check which enum vals aren't in switch
1120      auto CI = CaseVals.begin();
1121      auto RI = CaseRanges.begin();
1122      bool hasCasesNotInSwitch = false;
1123
1124      SmallVector<DeclarationName,8> UnhandledNames;
1125
1126      for (EI = EnumVals.begin(); EI != EIEnd; EI++){
1127        // Drop unneeded case values
1128        while (CI != CaseVals.end() && CI->first < EI->first)
1129          CI++;
1130
1131        if (CI != CaseVals.end() && CI->first == EI->first)
1132          continue;
1133
1134        // Drop unneeded case ranges
1135        for (; RI != CaseRanges.end(); RI++) {
1136          llvm::APSInt Hi =
1137            RI->second->getRHS()->EvaluateKnownConstInt(Context);
1138          AdjustAPSInt(Hi, CondWidth, CondIsSigned);
1139          if (EI->first <= Hi)
1140            break;
1141        }
1142
1143        if (RI == CaseRanges.end() || EI->first < RI->first) {
1144          hasCasesNotInSwitch = true;
1145          UnhandledNames.push_back(EI->second->getDeclName());
1146        }
1147      }
1148
1149      if (TheDefaultStmt && UnhandledNames.empty())
1150        Diag(TheDefaultStmt->getDefaultLoc(), diag::warn_unreachable_default);
1151
1152      // Produce a nice diagnostic if multiple values aren't handled.
1153      if (!UnhandledNames.empty()) {
1154        DiagnosticBuilder DB = Diag(CondExpr->getExprLoc(),
1155                                    TheDefaultStmt ? diag::warn_def_missing_case
1156                                                   : diag::warn_missing_case)
1157                               << (int)UnhandledNames.size();
1158
1159        for (size_t I = 0, E = std::min(UnhandledNames.size(), (size_t)3);
1160             I != E; ++I)
1161          DB << UnhandledNames[I];
1162      }
1163
1164      if (!hasCasesNotInSwitch)
1165        SS->setAllEnumCasesCovered();
1166    }
1167  }
1168
1169  if (BodyStmt)
1170    DiagnoseEmptyStmtBody(CondExpr->getLocEnd(), BodyStmt,
1171                          diag::warn_empty_switch_body);
1172
1173  // FIXME: If the case list was broken is some way, we don't have a good system
1174  // to patch it up.  Instead, just return the whole substmt as broken.
1175  if (CaseListIsErroneous)
1176    return StmtError();
1177
1178  return SS;
1179}
1180
1181void
1182Sema::DiagnoseAssignmentEnum(QualType DstType, QualType SrcType,
1183                             Expr *SrcExpr) {
1184  if (Diags.isIgnored(diag::warn_not_in_enum_assignment, SrcExpr->getExprLoc()))
1185    return;
1186
1187  if (const EnumType *ET = DstType->getAs<EnumType>())
1188    if (!Context.hasSameUnqualifiedType(SrcType, DstType) &&
1189        SrcType->isIntegerType()) {
1190      if (!SrcExpr->isTypeDependent() && !SrcExpr->isValueDependent() &&
1191          SrcExpr->isIntegerConstantExpr(Context)) {
1192        // Get the bitwidth of the enum value before promotions.
1193        unsigned DstWidth = Context.getIntWidth(DstType);
1194        bool DstIsSigned = DstType->isSignedIntegerOrEnumerationType();
1195
1196        llvm::APSInt RhsVal = SrcExpr->EvaluateKnownConstInt(Context);
1197        AdjustAPSInt(RhsVal, DstWidth, DstIsSigned);
1198        const EnumDecl *ED = ET->getDecl();
1199
1200        if (ED->hasAttr<FlagEnumAttr>()) {
1201          if (!IsValueInFlagEnum(ED, RhsVal, true))
1202            Diag(SrcExpr->getExprLoc(), diag::warn_not_in_enum_assignment)
1203              << DstType.getUnqualifiedType();
1204        } else {
1205          typedef SmallVector<std::pair<llvm::APSInt, EnumConstantDecl *>, 64>
1206              EnumValsTy;
1207          EnumValsTy EnumVals;
1208
1209          // Gather all enum values, set their type and sort them,
1210          // allowing easier comparison with rhs constant.
1211          for (auto *EDI : ED->enumerators()) {
1212            llvm::APSInt Val = EDI->getInitVal();
1213            AdjustAPSInt(Val, DstWidth, DstIsSigned);
1214            EnumVals.push_back(std::make_pair(Val, EDI));
1215          }
1216          if (EnumVals.empty())
1217            return;
1218          std::stable_sort(EnumVals.begin(), EnumVals.end(), CmpEnumVals);
1219          EnumValsTy::iterator EIend =
1220              std::unique(EnumVals.begin(), EnumVals.end(), EqEnumVals);
1221
1222          // See which values aren't in the enum.
1223          EnumValsTy::const_iterator EI = EnumVals.begin();
1224          while (EI != EIend && EI->first < RhsVal)
1225            EI++;
1226          if (EI == EIend || EI->first != RhsVal) {
1227            Diag(SrcExpr->getExprLoc(), diag::warn_not_in_enum_assignment)
1228                << DstType.getUnqualifiedType();
1229          }
1230        }
1231      }
1232    }
1233}
1234
1235StmtResult Sema::ActOnWhileStmt(SourceLocation WhileLoc, ConditionResult Cond,
1236                                Stmt *Body) {
1237  if (Cond.isInvalid())
1238    return StmtError();
1239
1240  auto CondVal = Cond.get();
1241  CheckBreakContinueBinding(CondVal.second);
1242
1243  if (CondVal.second &&
1244      !Diags.isIgnored(diag::warn_comma_operator, CondVal.second->getExprLoc()))
1245    CommaVisitor(*this).Visit(CondVal.second);
1246
1247  DiagnoseUnusedExprResult(Body);
1248
1249  if (isa<NullStmt>(Body))
1250    getCurCompoundScope().setHasEmptyLoopBodies();
1251
1252  return new (Context)
1253      WhileStmt(Context, CondVal.first, CondVal.second, Body, WhileLoc);
1254}
1255
1256StmtResult
1257Sema::ActOnDoStmt(SourceLocation DoLoc, Stmt *Body,
1258                  SourceLocation WhileLoc, SourceLocation CondLParen,
1259                  Expr *Cond, SourceLocation CondRParen) {
1260  assert(Cond && "ActOnDoStmt(): missing expression");
1261
1262  CheckBreakContinueBinding(Cond);
1263  ExprResult CondResult = CheckBooleanCondition(DoLoc, Cond);
1264  if (CondResult.isInvalid())
1265    return StmtError();
1266  Cond = CondResult.get();
1267
1268  CondResult = ActOnFinishFullExpr(Cond, DoLoc);
1269  if (CondResult.isInvalid())
1270    return StmtError();
1271  Cond = CondResult.get();
1272
1273  DiagnoseUnusedExprResult(Body);
1274
1275  return new (Context) DoStmt(Body, Cond, DoLoc, WhileLoc, CondRParen);
1276}
1277
1278namespace {
1279  // This visitor will traverse a conditional statement and store all
1280  // the evaluated decls into a vector.  Simple is set to true if none
1281  // of the excluded constructs are used.
1282  class DeclExtractor : public EvaluatedExprVisitor<DeclExtractor> {
1283    llvm::SmallPtrSetImpl<VarDecl*> &Decls;
1284    SmallVectorImpl<SourceRange> &Ranges;
1285    bool Simple;
1286  public:
1287    typedef EvaluatedExprVisitor<DeclExtractor> Inherited;
1288
1289    DeclExtractor(Sema &S, llvm::SmallPtrSetImpl<VarDecl*> &Decls,
1290                  SmallVectorImpl<SourceRange> &Ranges) :
1291        Inherited(S.Context),
1292        Decls(Decls),
1293        Ranges(Ranges),
1294        Simple(true) {}
1295
1296    bool isSimple() { return Simple; }
1297
1298    // Replaces the method in EvaluatedExprVisitor.
1299    void VisitMemberExpr(MemberExpr* E) {
1300      Simple = false;
1301    }
1302
1303    // Any Stmt not whitelisted will cause the condition to be marked complex.
1304    void VisitStmt(Stmt *S) {
1305      Simple = false;
1306    }
1307
1308    void VisitBinaryOperator(BinaryOperator *E) {
1309      Visit(E->getLHS());
1310      Visit(E->getRHS());
1311    }
1312
1313    void VisitCastExpr(CastExpr *E) {
1314      Visit(E->getSubExpr());
1315    }
1316
1317    void VisitUnaryOperator(UnaryOperator *E) {
1318      // Skip checking conditionals with derefernces.
1319      if (E->getOpcode() == UO_Deref)
1320        Simple = false;
1321      else
1322        Visit(E->getSubExpr());
1323    }
1324
1325    void VisitConditionalOperator(ConditionalOperator *E) {
1326      Visit(E->getCond());
1327      Visit(E->getTrueExpr());
1328      Visit(E->getFalseExpr());
1329    }
1330
1331    void VisitParenExpr(ParenExpr *E) {
1332      Visit(E->getSubExpr());
1333    }
1334
1335    void VisitBinaryConditionalOperator(BinaryConditionalOperator *E) {
1336      Visit(E->getOpaqueValue()->getSourceExpr());
1337      Visit(E->getFalseExpr());
1338    }
1339
1340    void VisitIntegerLiteral(IntegerLiteral *E) { }
1341    void VisitFloatingLiteral(FloatingLiteral *E) { }
1342    void VisitCXXBoolLiteralExpr(CXXBoolLiteralExpr *E) { }
1343    void VisitCharacterLiteral(CharacterLiteral *E) { }
1344    void VisitGNUNullExpr(GNUNullExpr *E) { }
1345    void VisitImaginaryLiteral(ImaginaryLiteral *E) { }
1346
1347    void VisitDeclRefExpr(DeclRefExpr *E) {
1348      VarDecl *VD = dyn_cast<VarDecl>(E->getDecl());
1349      if (!VD) return;
1350
1351      Ranges.push_back(E->getSourceRange());
1352
1353      Decls.insert(VD);
1354    }
1355
1356  }; // end class DeclExtractor
1357
1358  // DeclMatcher checks to see if the decls are used in a non-evaluated
1359  // context.
1360  class DeclMatcher : public EvaluatedExprVisitor<DeclMatcher> {
1361    llvm::SmallPtrSetImpl<VarDecl*> &Decls;
1362    bool FoundDecl;
1363
1364  public:
1365    typedef EvaluatedExprVisitor<DeclMatcher> Inherited;
1366
1367    DeclMatcher(Sema &S, llvm::SmallPtrSetImpl<VarDecl*> &Decls,
1368                Stmt *Statement) :
1369        Inherited(S.Context), Decls(Decls), FoundDecl(false) {
1370      if (!Statement) return;
1371
1372      Visit(Statement);
1373    }
1374
1375    void VisitReturnStmt(ReturnStmt *S) {
1376      FoundDecl = true;
1377    }
1378
1379    void VisitBreakStmt(BreakStmt *S) {
1380      FoundDecl = true;
1381    }
1382
1383    void VisitGotoStmt(GotoStmt *S) {
1384      FoundDecl = true;
1385    }
1386
1387    void VisitCastExpr(CastExpr *E) {
1388      if (E->getCastKind() == CK_LValueToRValue)
1389        CheckLValueToRValueCast(E->getSubExpr());
1390      else
1391        Visit(E->getSubExpr());
1392    }
1393
1394    void CheckLValueToRValueCast(Expr *E) {
1395      E = E->IgnoreParenImpCasts();
1396
1397      if (isa<DeclRefExpr>(E)) {
1398        return;
1399      }
1400
1401      if (ConditionalOperator *CO = dyn_cast<ConditionalOperator>(E)) {
1402        Visit(CO->getCond());
1403        CheckLValueToRValueCast(CO->getTrueExpr());
1404        CheckLValueToRValueCast(CO->getFalseExpr());
1405        return;
1406      }
1407
1408      if (BinaryConditionalOperator *BCO =
1409              dyn_cast<BinaryConditionalOperator>(E)) {
1410        CheckLValueToRValueCast(BCO->getOpaqueValue()->getSourceExpr());
1411        CheckLValueToRValueCast(BCO->getFalseExpr());
1412        return;
1413      }
1414
1415      Visit(E);
1416    }
1417
1418    void VisitDeclRefExpr(DeclRefExpr *E) {
1419      if (VarDecl *VD = dyn_cast<VarDecl>(E->getDecl()))
1420        if (Decls.count(VD))
1421          FoundDecl = true;
1422    }
1423
1424    void VisitPseudoObjectExpr(PseudoObjectExpr *POE) {
1425      // Only need to visit the semantics for POE.
1426      // SyntaticForm doesn't really use the Decal.
1427      for (auto *S : POE->semantics()) {
1428        if (auto *OVE = dyn_cast<OpaqueValueExpr>(S))
1429          // Look past the OVE into the expression it binds.
1430          Visit(OVE->getSourceExpr());
1431        else
1432          Visit(S);
1433      }
1434    }
1435
1436    bool FoundDeclInUse() { return FoundDecl; }
1437
1438  };  // end class DeclMatcher
1439
1440  void CheckForLoopConditionalStatement(Sema &S, Expr *Second,
1441                                        Expr *Third, Stmt *Body) {
1442    // Condition is empty
1443    if (!Second) return;
1444
1445    if (S.Diags.isIgnored(diag::warn_variables_not_in_loop_body,
1446                          Second->getLocStart()))
1447      return;
1448
1449    PartialDiagnostic PDiag = S.PDiag(diag::warn_variables_not_in_loop_body);
1450    llvm::SmallPtrSet<VarDecl*, 8> Decls;
1451    SmallVector<SourceRange, 10> Ranges;
1452    DeclExtractor DE(S, Decls, Ranges);
1453    DE.Visit(Second);
1454
1455    // Don't analyze complex conditionals.
1456    if (!DE.isSimple()) return;
1457
1458    // No decls found.
1459    if (Decls.size() == 0) return;
1460
1461    // Don't warn on volatile, static, or global variables.
1462    for (llvm::SmallPtrSetImpl<VarDecl*>::iterator I = Decls.begin(),
1463                                                   E = Decls.end();
1464         I != E; ++I)
1465      if ((*I)->getType().isVolatileQualified() ||
1466          (*I)->hasGlobalStorage()) return;
1467
1468    if (DeclMatcher(S, Decls, Second).FoundDeclInUse() ||
1469        DeclMatcher(S, Decls, Third).FoundDeclInUse() ||
1470        DeclMatcher(S, Decls, Body).FoundDeclInUse())
1471      return;
1472
1473    // Load decl names into diagnostic.
1474    if (Decls.size() > 4)
1475      PDiag << 0;
1476    else {
1477      PDiag << Decls.size();
1478      for (llvm::SmallPtrSetImpl<VarDecl*>::iterator I = Decls.begin(),
1479                                                     E = Decls.end();
1480           I != E; ++I)
1481        PDiag << (*I)->getDeclName();
1482    }
1483
1484    // Load SourceRanges into diagnostic if there is room.
1485    // Otherwise, load the SourceRange of the conditional expression.
1486    if (Ranges.size() <= PartialDiagnostic::MaxArguments)
1487      for (SmallVectorImpl<SourceRange>::iterator I = Ranges.begin(),
1488                                                  E = Ranges.end();
1489           I != E; ++I)
1490        PDiag << *I;
1491    else
1492      PDiag << Second->getSourceRange();
1493
1494    S.Diag(Ranges.begin()->getBegin(), PDiag);
1495  }
1496
1497  // If Statement is an incemement or decrement, return true and sets the
1498  // variables Increment and DRE.
1499  bool ProcessIterationStmt(Sema &S, Stmt* Statement, bool &Increment,
1500                            DeclRefExpr *&DRE) {
1501    if (auto Cleanups = dyn_cast<ExprWithCleanups>(Statement))
1502      if (!Cleanups->cleanupsHaveSideEffects())
1503        Statement = Cleanups->getSubExpr();
1504
1505    if (UnaryOperator *UO = dyn_cast<UnaryOperator>(Statement)) {
1506      switch (UO->getOpcode()) {
1507        default: return false;
1508        case UO_PostInc:
1509        case UO_PreInc:
1510          Increment = true;
1511          break;
1512        case UO_PostDec:
1513        case UO_PreDec:
1514          Increment = false;
1515          break;
1516      }
1517      DRE = dyn_cast<DeclRefExpr>(UO->getSubExpr());
1518      return DRE;
1519    }
1520
1521    if (CXXOperatorCallExpr *Call = dyn_cast<CXXOperatorCallExpr>(Statement)) {
1522      FunctionDecl *FD = Call->getDirectCallee();
1523      if (!FD || !FD->isOverloadedOperator()) return false;
1524      switch (FD->getOverloadedOperator()) {
1525        default: return false;
1526        case OO_PlusPlus:
1527          Increment = true;
1528          break;
1529        case OO_MinusMinus:
1530          Increment = false;
1531          break;
1532      }
1533      DRE = dyn_cast<DeclRefExpr>(Call->getArg(0));
1534      return DRE;
1535    }
1536
1537    return false;
1538  }
1539
1540  // A visitor to determine if a continue or break statement is a
1541  // subexpression.
1542  class BreakContinueFinder : public EvaluatedExprVisitor<BreakContinueFinder> {
1543    SourceLocation BreakLoc;
1544    SourceLocation ContinueLoc;
1545  public:
1546    BreakContinueFinder(Sema &S, Stmt* Body) :
1547        Inherited(S.Context) {
1548      Visit(Body);
1549    }
1550
1551    typedef EvaluatedExprVisitor<BreakContinueFinder> Inherited;
1552
1553    void VisitContinueStmt(ContinueStmt* E) {
1554      ContinueLoc = E->getContinueLoc();
1555    }
1556
1557    void VisitBreakStmt(BreakStmt* E) {
1558      BreakLoc = E->getBreakLoc();
1559    }
1560
1561    bool ContinueFound() { return ContinueLoc.isValid(); }
1562    bool BreakFound() { return BreakLoc.isValid(); }
1563    SourceLocation GetContinueLoc() { return ContinueLoc; }
1564    SourceLocation GetBreakLoc() { return BreakLoc; }
1565
1566  };  // end class BreakContinueFinder
1567
1568  // Emit a warning when a loop increment/decrement appears twice per loop
1569  // iteration.  The conditions which trigger this warning are:
1570  // 1) The last statement in the loop body and the third expression in the
1571  //    for loop are both increment or both decrement of the same variable
1572  // 2) No continue statements in the loop body.
1573  void CheckForRedundantIteration(Sema &S, Expr *Third, Stmt *Body) {
1574    // Return when there is nothing to check.
1575    if (!Body || !Third) return;
1576
1577    if (S.Diags.isIgnored(diag::warn_redundant_loop_iteration,
1578                          Third->getLocStart()))
1579      return;
1580
1581    // Get the last statement from the loop body.
1582    CompoundStmt *CS = dyn_cast<CompoundStmt>(Body);
1583    if (!CS || CS->body_empty()) return;
1584    Stmt *LastStmt = CS->body_back();
1585    if (!LastStmt) return;
1586
1587    bool LoopIncrement, LastIncrement;
1588    DeclRefExpr *LoopDRE, *LastDRE;
1589
1590    if (!ProcessIterationStmt(S, Third, LoopIncrement, LoopDRE)) return;
1591    if (!ProcessIterationStmt(S, LastStmt, LastIncrement, LastDRE)) return;
1592
1593    // Check that the two statements are both increments or both decrements
1594    // on the same variable.
1595    if (LoopIncrement != LastIncrement ||
1596        LoopDRE->getDecl() != LastDRE->getDecl()) return;
1597
1598    if (BreakContinueFinder(S, Body).ContinueFound()) return;
1599
1600    S.Diag(LastDRE->getLocation(), diag::warn_redundant_loop_iteration)
1601         << LastDRE->getDecl() << LastIncrement;
1602    S.Diag(LoopDRE->getLocation(), diag::note_loop_iteration_here)
1603         << LoopIncrement;
1604  }
1605
1606} // end namespace
1607
1608
1609void Sema::CheckBreakContinueBinding(Expr *E) {
1610  if (!E || getLangOpts().CPlusPlus)
1611    return;
1612  BreakContinueFinder BCFinder(*this, E);
1613  Scope *BreakParent = CurScope->getBreakParent();
1614  if (BCFinder.BreakFound() && BreakParent) {
1615    if (BreakParent->getFlags() & Scope::SwitchScope) {
1616      Diag(BCFinder.GetBreakLoc(), diag::warn_break_binds_to_switch);
1617    } else {
1618      Diag(BCFinder.GetBreakLoc(), diag::warn_loop_ctrl_binds_to_inner)
1619          << "break";
1620    }
1621  } else if (BCFinder.ContinueFound() && CurScope->getContinueParent()) {
1622    Diag(BCFinder.GetContinueLoc(), diag::warn_loop_ctrl_binds_to_inner)
1623        << "continue";
1624  }
1625}
1626
1627StmtResult Sema::ActOnForStmt(SourceLocation ForLoc, SourceLocation LParenLoc,
1628                              Stmt *First, ConditionResult Second,
1629                              FullExprArg third, SourceLocation RParenLoc,
1630                              Stmt *Body) {
1631  if (Second.isInvalid())
1632    return StmtError();
1633
1634  if (!getLangOpts().CPlusPlus) {
1635    if (DeclStmt *DS = dyn_cast_or_null<DeclStmt>(First)) {
1636      // C99 6.8.5p3: The declaration part of a 'for' statement shall only
1637      // declare identifiers for objects having storage class 'auto' or
1638      // 'register'.
1639      for (auto *DI : DS->decls()) {
1640        VarDecl *VD = dyn_cast<VarDecl>(DI);
1641        if (VD && VD->isLocalVarDecl() && !VD->hasLocalStorage())
1642          VD = nullptr;
1643        if (!VD) {
1644          Diag(DI->getLocation(), diag::err_non_local_variable_decl_in_for);
1645          DI->setInvalidDecl();
1646        }
1647      }
1648    }
1649  }
1650
1651  CheckBreakContinueBinding(Second.get().second);
1652  CheckBreakContinueBinding(third.get());
1653
1654  if (!Second.get().first)
1655    CheckForLoopConditionalStatement(*this, Second.get().second, third.get(),
1656                                     Body);
1657  CheckForRedundantIteration(*this, third.get(), Body);
1658
1659  if (Second.get().second &&
1660      !Diags.isIgnored(diag::warn_comma_operator,
1661                       Second.get().second->getExprLoc()))
1662    CommaVisitor(*this).Visit(Second.get().second);
1663
1664  Expr *Third  = third.release().getAs<Expr>();
1665
1666  DiagnoseUnusedExprResult(First);
1667  DiagnoseUnusedExprResult(Third);
1668  DiagnoseUnusedExprResult(Body);
1669
1670  if (isa<NullStmt>(Body))
1671    getCurCompoundScope().setHasEmptyLoopBodies();
1672
1673  return new (Context)
1674      ForStmt(Context, First, Second.get().second, Second.get().first, Third,
1675              Body, ForLoc, LParenLoc, RParenLoc);
1676}
1677
1678/// In an Objective C collection iteration statement:
1679///   for (x in y)
1680/// x can be an arbitrary l-value expression.  Bind it up as a
1681/// full-expression.
1682StmtResult Sema::ActOnForEachLValueExpr(Expr *E) {
1683  // Reduce placeholder expressions here.  Note that this rejects the
1684  // use of pseudo-object l-values in this position.
1685  ExprResult result = CheckPlaceholderExpr(E);
1686  if (result.isInvalid()) return StmtError();
1687  E = result.get();
1688
1689  ExprResult FullExpr = ActOnFinishFullExpr(E);
1690  if (FullExpr.isInvalid())
1691    return StmtError();
1692  return StmtResult(static_cast<Stmt*>(FullExpr.get()));
1693}
1694
1695ExprResult
1696Sema::CheckObjCForCollectionOperand(SourceLocation forLoc, Expr *collection) {
1697  if (!collection)
1698    return ExprError();
1699
1700  ExprResult result = CorrectDelayedTyposInExpr(collection);
1701  if (!result.isUsable())
1702    return ExprError();
1703  collection = result.get();
1704
1705  // Bail out early if we've got a type-dependent expression.
1706  if (collection->isTypeDependent()) return collection;
1707
1708  // Perform normal l-value conversion.
1709  result = DefaultFunctionArrayLvalueConversion(collection);
1710  if (result.isInvalid())
1711    return ExprError();
1712  collection = result.get();
1713
1714  // The operand needs to have object-pointer type.
1715  // TODO: should we do a contextual conversion?
1716  const ObjCObjectPointerType *pointerType =
1717    collection->getType()->getAs<ObjCObjectPointerType>();
1718  if (!pointerType)
1719    return Diag(forLoc, diag::err_collection_expr_type)
1720             << collection->getType() << collection->getSourceRange();
1721
1722  // Check that the operand provides
1723  //   - countByEnumeratingWithState:objects:count:
1724  const ObjCObjectType *objectType = pointerType->getObjectType();
1725  ObjCInterfaceDecl *iface = objectType->getInterface();
1726
1727  // If we have a forward-declared type, we can't do this check.
1728  // Under ARC, it is an error not to have a forward-declared class.
1729  if (iface &&
1730      (getLangOpts().ObjCAutoRefCount
1731           ? RequireCompleteType(forLoc, QualType(objectType, 0),
1732                                 diag::err_arc_collection_forward, collection)
1733           : !isCompleteType(forLoc, QualType(objectType, 0)))) {
1734    // Otherwise, if we have any useful type information, check that
1735    // the type declares the appropriate method.
1736  } else if (iface || !objectType->qual_empty()) {
1737    IdentifierInfo *selectorIdents[] = {
1738      &Context.Idents.get("countByEnumeratingWithState"),
1739      &Context.Idents.get("objects"),
1740      &Context.Idents.get("count")
1741    };
1742    Selector selector = Context.Selectors.getSelector(3, &selectorIdents[0]);
1743
1744    ObjCMethodDecl *method = nullptr;
1745
1746    // If there's an interface, look in both the public and private APIs.
1747    if (iface) {
1748      method = iface->lookupInstanceMethod(selector);
1749      if (!method) method = iface->lookupPrivateMethod(selector);
1750    }
1751
1752    // Also check protocol qualifiers.
1753    if (!method)
1754      method = LookupMethodInQualifiedType(selector, pointerType,
1755                                           /*instance*/ true);
1756
1757    // If we didn't find it anywhere, give up.
1758    if (!method) {
1759      Diag(forLoc, diag::warn_collection_expr_type)
1760        << collection->getType() << selector << collection->getSourceRange();
1761    }
1762
1763    // TODO: check for an incompatible signature?
1764  }
1765
1766  // Wrap up any cleanups in the expression.
1767  return collection;
1768}
1769
1770StmtResult
1771Sema::ActOnObjCForCollectionStmt(SourceLocation ForLoc,
1772                                 Stmt *First, Expr *collection,
1773                                 SourceLocation RParenLoc) {
1774
1775  ExprResult CollectionExprResult =
1776    CheckObjCForCollectionOperand(ForLoc, collection);
1777
1778  if (First) {
1779    QualType FirstType;
1780    if (DeclStmt *DS = dyn_cast<DeclStmt>(First)) {
1781      if (!DS->isSingleDecl())
1782        return StmtError(Diag((*DS->decl_begin())->getLocation(),
1783                         diag::err_toomany_element_decls));
1784
1785      VarDecl *D = dyn_cast<VarDecl>(DS->getSingleDecl());
1786      if (!D || D->isInvalidDecl())
1787        return StmtError();
1788
1789      FirstType = D->getType();
1790      // C99 6.8.5p3: The declaration part of a 'for' statement shall only
1791      // declare identifiers for objects having storage class 'auto' or
1792      // 'register'.
1793      if (!D->hasLocalStorage())
1794        return StmtError(Diag(D->getLocation(),
1795                              diag::err_non_local_variable_decl_in_for));
1796
1797      // If the type contained 'auto', deduce the 'auto' to 'id'.
1798      if (FirstType->getContainedAutoType()) {
1799        OpaqueValueExpr OpaqueId(D->getLocation(), Context.getObjCIdType(),
1800                                 VK_RValue);
1801        Expr *DeducedInit = &OpaqueId;
1802        if (DeduceAutoType(D->getTypeSourceInfo(), DeducedInit, FirstType) ==
1803                DAR_Failed)
1804          DiagnoseAutoDeductionFailure(D, DeducedInit);
1805        if (FirstType.isNull()) {
1806          D->setInvalidDecl();
1807          return StmtError();
1808        }
1809
1810        D->setType(FirstType);
1811
1812        if (ActiveTemplateInstantiations.empty()) {
1813          SourceLocation Loc =
1814              D->getTypeSourceInfo()->getTypeLoc().getBeginLoc();
1815          Diag(Loc, diag::warn_auto_var_is_id)
1816            << D->getDeclName();
1817        }
1818      }
1819
1820    } else {
1821      Expr *FirstE = cast<Expr>(First);
1822      if (!FirstE->isTypeDependent() && !FirstE->isLValue())
1823        return StmtError(Diag(First->getLocStart(),
1824                   diag::err_selector_element_not_lvalue)
1825          << First->getSourceRange());
1826
1827      FirstType = static_cast<Expr*>(First)->getType();
1828      if (FirstType.isConstQualified())
1829        Diag(ForLoc, diag::err_selector_element_const_type)
1830          << FirstType << First->getSourceRange();
1831    }
1832    if (!FirstType->isDependentType() &&
1833        !FirstType->isObjCObjectPointerType() &&
1834        !FirstType->isBlockPointerType())
1835        return StmtError(Diag(ForLoc, diag::err_selector_element_type)
1836                           << FirstType << First->getSourceRange());
1837  }
1838
1839  if (CollectionExprResult.isInvalid())
1840    return StmtError();
1841
1842  CollectionExprResult = ActOnFinishFullExpr(CollectionExprResult.get());
1843  if (CollectionExprResult.isInvalid())
1844    return StmtError();
1845
1846  return new (Context) ObjCForCollectionStmt(First, CollectionExprResult.get(),
1847                                             nullptr, ForLoc, RParenLoc);
1848}
1849
1850/// Finish building a variable declaration for a for-range statement.
1851/// \return true if an error occurs.
1852static bool FinishForRangeVarDecl(Sema &SemaRef, VarDecl *Decl, Expr *Init,
1853                                  SourceLocation Loc, int DiagID) {
1854  if (Decl->getType()->isUndeducedType()) {
1855    ExprResult Res = SemaRef.CorrectDelayedTyposInExpr(Init);
1856    if (!Res.isUsable()) {
1857      Decl->setInvalidDecl();
1858      return true;
1859    }
1860    Init = Res.get();
1861  }
1862
1863  // Deduce the type for the iterator variable now rather than leaving it to
1864  // AddInitializerToDecl, so we can produce a more suitable diagnostic.
1865  QualType InitType;
1866  if ((!isa<InitListExpr>(Init) && Init->getType()->isVoidType()) ||
1867      SemaRef.DeduceAutoType(Decl->getTypeSourceInfo(), Init, InitType) ==
1868          Sema::DAR_Failed)
1869    SemaRef.Diag(Loc, DiagID) << Init->getType();
1870  if (InitType.isNull()) {
1871    Decl->setInvalidDecl();
1872    return true;
1873  }
1874  Decl->setType(InitType);
1875
1876  // In ARC, infer lifetime.
1877  // FIXME: ARC may want to turn this into 'const __unsafe_unretained' if
1878  // we're doing the equivalent of fast iteration.
1879  if (SemaRef.getLangOpts().ObjCAutoRefCount &&
1880      SemaRef.inferObjCARCLifetime(Decl))
1881    Decl->setInvalidDecl();
1882
1883  SemaRef.AddInitializerToDecl(Decl, Init, /*DirectInit=*/false,
1884                               /*TypeMayContainAuto=*/false);
1885  SemaRef.FinalizeDeclaration(Decl);
1886  SemaRef.CurContext->addHiddenDecl(Decl);
1887  return false;
1888}
1889
1890namespace {
1891// An enum to represent whether something is dealing with a call to begin()
1892// or a call to end() in a range-based for loop.
1893enum BeginEndFunction {
1894  BEF_begin,
1895  BEF_end
1896};
1897
1898/// Produce a note indicating which begin/end function was implicitly called
1899/// by a C++11 for-range statement. This is often not obvious from the code,
1900/// nor from the diagnostics produced when analysing the implicit expressions
1901/// required in a for-range statement.
1902void NoteForRangeBeginEndFunction(Sema &SemaRef, Expr *E,
1903                                  BeginEndFunction BEF) {
1904  CallExpr *CE = dyn_cast<CallExpr>(E);
1905  if (!CE)
1906    return;
1907  FunctionDecl *D = dyn_cast<FunctionDecl>(CE->getCalleeDecl());
1908  if (!D)
1909    return;
1910  SourceLocation Loc = D->getLocation();
1911
1912  std::string Description;
1913  bool IsTemplate = false;
1914  if (FunctionTemplateDecl *FunTmpl = D->getPrimaryTemplate()) {
1915    Description = SemaRef.getTemplateArgumentBindingsText(
1916      FunTmpl->getTemplateParameters(), *D->getTemplateSpecializationArgs());
1917    IsTemplate = true;
1918  }
1919
1920  SemaRef.Diag(Loc, diag::note_for_range_begin_end)
1921    << BEF << IsTemplate << Description << E->getType();
1922}
1923
1924/// Build a variable declaration for a for-range statement.
1925VarDecl *BuildForRangeVarDecl(Sema &SemaRef, SourceLocation Loc,
1926                              QualType Type, const char *Name) {
1927  DeclContext *DC = SemaRef.CurContext;
1928  IdentifierInfo *II = &SemaRef.PP.getIdentifierTable().get(Name);
1929  TypeSourceInfo *TInfo = SemaRef.Context.getTrivialTypeSourceInfo(Type, Loc);
1930  VarDecl *Decl = VarDecl::Create(SemaRef.Context, DC, Loc, Loc, II, Type,
1931                                  TInfo, SC_None);
1932  Decl->setImplicit();
1933  return Decl;
1934}
1935
1936}
1937
1938static bool ObjCEnumerationCollection(Expr *Collection) {
1939  return !Collection->isTypeDependent()
1940          && Collection->getType()->getAs<ObjCObjectPointerType>() != nullptr;
1941}
1942
1943/// ActOnCXXForRangeStmt - Check and build a C++11 for-range statement.
1944///
1945/// C++11 [stmt.ranged]:
1946///   A range-based for statement is equivalent to
1947///
1948///   {
1949///     auto && __range = range-init;
1950///     for ( auto __begin = begin-expr,
1951///           __end = end-expr;
1952///           __begin != __end;
1953///           ++__begin ) {
1954///       for-range-declaration = *__begin;
1955///       statement
1956///     }
1957///   }
1958///
1959/// The body of the loop is not available yet, since it cannot be analysed until
1960/// we have determined the type of the for-range-declaration.
1961StmtResult Sema::ActOnCXXForRangeStmt(Scope *S, SourceLocation ForLoc,
1962                                      SourceLocation CoawaitLoc, Stmt *First,
1963                                      SourceLocation ColonLoc, Expr *Range,
1964                                      SourceLocation RParenLoc,
1965                                      BuildForRangeKind Kind) {
1966  if (!First)
1967    return StmtError();
1968
1969  if (Range && ObjCEnumerationCollection(Range))
1970    return ActOnObjCForCollectionStmt(ForLoc, First, Range, RParenLoc);
1971
1972  DeclStmt *DS = dyn_cast<DeclStmt>(First);
1973  assert(DS && "first part of for range not a decl stmt");
1974
1975  if (!DS->isSingleDecl()) {
1976    Diag(DS->getStartLoc(), diag::err_type_defined_in_for_range);
1977    return StmtError();
1978  }
1979
1980  Decl *LoopVar = DS->getSingleDecl();
1981  if (LoopVar->isInvalidDecl() || !Range ||
1982      DiagnoseUnexpandedParameterPack(Range, UPPC_Expression)) {
1983    LoopVar->setInvalidDecl();
1984    return StmtError();
1985  }
1986
1987  // Coroutines: 'for co_await' implicitly co_awaits its range.
1988  if (CoawaitLoc.isValid()) {
1989    ExprResult Coawait = ActOnCoawaitExpr(S, CoawaitLoc, Range);
1990    if (Coawait.isInvalid()) return StmtError();
1991    Range = Coawait.get();
1992  }
1993
1994  // Build  auto && __range = range-init
1995  SourceLocation RangeLoc = Range->getLocStart();
1996  VarDecl *RangeVar = BuildForRangeVarDecl(*this, RangeLoc,
1997                                           Context.getAutoRRefDeductType(),
1998                                           "__range");
1999  if (FinishForRangeVarDecl(*this, RangeVar, Range, RangeLoc,
2000                            diag::err_for_range_deduction_failure)) {
2001    LoopVar->setInvalidDecl();
2002    return StmtError();
2003  }
2004
2005  // Claim the type doesn't contain auto: we've already done the checking.
2006  DeclGroupPtrTy RangeGroup =
2007      BuildDeclaratorGroup(MutableArrayRef<Decl *>((Decl **)&RangeVar, 1),
2008                           /*TypeMayContainAuto=*/ false);
2009  StmtResult RangeDecl = ActOnDeclStmt(RangeGroup, RangeLoc, RangeLoc);
2010  if (RangeDecl.isInvalid()) {
2011    LoopVar->setInvalidDecl();
2012    return StmtError();
2013  }
2014
2015  return BuildCXXForRangeStmt(ForLoc, CoawaitLoc, ColonLoc, RangeDecl.get(),
2016                              /*BeginStmt=*/nullptr, /*EndStmt=*/nullptr,
2017                              /*Cond=*/nullptr, /*Inc=*/nullptr,
2018                              DS, RParenLoc, Kind);
2019}
2020
2021/// \brief Create the initialization, compare, and increment steps for
2022/// the range-based for loop expression.
2023/// This function does not handle array-based for loops,
2024/// which are created in Sema::BuildCXXForRangeStmt.
2025///
2026/// \returns a ForRangeStatus indicating success or what kind of error occurred.
2027/// BeginExpr and EndExpr are set and FRS_Success is returned on success;
2028/// CandidateSet and BEF are set and some non-success value is returned on
2029/// failure.
2030static Sema::ForRangeStatus BuildNonArrayForRange(Sema &SemaRef,
2031                                            Expr *BeginRange, Expr *EndRange,
2032                                            QualType RangeType,
2033                                            VarDecl *BeginVar,
2034                                            VarDecl *EndVar,
2035                                            SourceLocation ColonLoc,
2036                                            OverloadCandidateSet *CandidateSet,
2037                                            ExprResult *BeginExpr,
2038                                            ExprResult *EndExpr,
2039                                            BeginEndFunction *BEF) {
2040  DeclarationNameInfo BeginNameInfo(
2041      &SemaRef.PP.getIdentifierTable().get("begin"), ColonLoc);
2042  DeclarationNameInfo EndNameInfo(&SemaRef.PP.getIdentifierTable().get("end"),
2043                                  ColonLoc);
2044
2045  LookupResult BeginMemberLookup(SemaRef, BeginNameInfo,
2046                                 Sema::LookupMemberName);
2047  LookupResult EndMemberLookup(SemaRef, EndNameInfo, Sema::LookupMemberName);
2048
2049  if (CXXRecordDecl *D = RangeType->getAsCXXRecordDecl()) {
2050    // - if _RangeT is a class type, the unqualified-ids begin and end are
2051    //   looked up in the scope of class _RangeT as if by class member access
2052    //   lookup (3.4.5), and if either (or both) finds at least one
2053    //   declaration, begin-expr and end-expr are __range.begin() and
2054    //   __range.end(), respectively;
2055    SemaRef.LookupQualifiedName(BeginMemberLookup, D);
2056    SemaRef.LookupQualifiedName(EndMemberLookup, D);
2057
2058    if (BeginMemberLookup.empty() != EndMemberLookup.empty()) {
2059      SourceLocation RangeLoc = BeginVar->getLocation();
2060      *BEF = BeginMemberLookup.empty() ? BEF_end : BEF_begin;
2061
2062      SemaRef.Diag(RangeLoc, diag::err_for_range_member_begin_end_mismatch)
2063          << RangeLoc << BeginRange->getType() << *BEF;
2064      return Sema::FRS_DiagnosticIssued;
2065    }
2066  } else {
2067    // - otherwise, begin-expr and end-expr are begin(__range) and
2068    //   end(__range), respectively, where begin and end are looked up with
2069    //   argument-dependent lookup (3.4.2). For the purposes of this name
2070    //   lookup, namespace std is an associated namespace.
2071
2072  }
2073
2074  *BEF = BEF_begin;
2075  Sema::ForRangeStatus RangeStatus =
2076      SemaRef.BuildForRangeBeginEndCall(ColonLoc, ColonLoc, BeginNameInfo,
2077                                        BeginMemberLookup, CandidateSet,
2078                                        BeginRange, BeginExpr);
2079
2080  if (RangeStatus != Sema::FRS_Success) {
2081    if (RangeStatus == Sema::FRS_DiagnosticIssued)
2082      SemaRef.Diag(BeginRange->getLocStart(), diag::note_in_for_range)
2083          << ColonLoc << BEF_begin << BeginRange->getType();
2084    return RangeStatus;
2085  }
2086  if (FinishForRangeVarDecl(SemaRef, BeginVar, BeginExpr->get(), ColonLoc,
2087                            diag::err_for_range_iter_deduction_failure)) {
2088    NoteForRangeBeginEndFunction(SemaRef, BeginExpr->get(), *BEF);
2089    return Sema::FRS_DiagnosticIssued;
2090  }
2091
2092  *BEF = BEF_end;
2093  RangeStatus =
2094      SemaRef.BuildForRangeBeginEndCall(ColonLoc, ColonLoc, EndNameInfo,
2095                                        EndMemberLookup, CandidateSet,
2096                                        EndRange, EndExpr);
2097  if (RangeStatus != Sema::FRS_Success) {
2098    if (RangeStatus == Sema::FRS_DiagnosticIssued)
2099      SemaRef.Diag(EndRange->getLocStart(), diag::note_in_for_range)
2100          << ColonLoc << BEF_end << EndRange->getType();
2101    return RangeStatus;
2102  }
2103  if (FinishForRangeVarDecl(SemaRef, EndVar, EndExpr->get(), ColonLoc,
2104                            diag::err_for_range_iter_deduction_failure)) {
2105    NoteForRangeBeginEndFunction(SemaRef, EndExpr->get(), *BEF);
2106    return Sema::FRS_DiagnosticIssued;
2107  }
2108  return Sema::FRS_Success;
2109}
2110
2111/// Speculatively attempt to dereference an invalid range expression.
2112/// If the attempt fails, this function will return a valid, null StmtResult
2113/// and emit no diagnostics.
2114static StmtResult RebuildForRangeWithDereference(Sema &SemaRef, Scope *S,
2115                                                 SourceLocation ForLoc,
2116                                                 SourceLocation CoawaitLoc,
2117                                                 Stmt *LoopVarDecl,
2118                                                 SourceLocation ColonLoc,
2119                                                 Expr *Range,
2120                                                 SourceLocation RangeLoc,
2121                                                 SourceLocation RParenLoc) {
2122  // Determine whether we can rebuild the for-range statement with a
2123  // dereferenced range expression.
2124  ExprResult AdjustedRange;
2125  {
2126    Sema::SFINAETrap Trap(SemaRef);
2127
2128    AdjustedRange = SemaRef.BuildUnaryOp(S, RangeLoc, UO_Deref, Range);
2129    if (AdjustedRange.isInvalid())
2130      return StmtResult();
2131
2132    StmtResult SR = SemaRef.ActOnCXXForRangeStmt(
2133        S, ForLoc, CoawaitLoc, LoopVarDecl, ColonLoc, AdjustedRange.get(),
2134        RParenLoc, Sema::BFRK_Check);
2135    if (SR.isInvalid())
2136      return StmtResult();
2137  }
2138
2139  // The attempt to dereference worked well enough that it could produce a valid
2140  // loop. Produce a fixit, and rebuild the loop with diagnostics enabled, in
2141  // case there are any other (non-fatal) problems with it.
2142  SemaRef.Diag(RangeLoc, diag::err_for_range_dereference)
2143    << Range->getType() << FixItHint::CreateInsertion(RangeLoc, "*");
2144  return SemaRef.ActOnCXXForRangeStmt(S, ForLoc, CoawaitLoc, LoopVarDecl,
2145                                      ColonLoc, AdjustedRange.get(), RParenLoc,
2146                                      Sema::BFRK_Rebuild);
2147}
2148
2149namespace {
2150/// RAII object to automatically invalidate a declaration if an error occurs.
2151struct InvalidateOnErrorScope {
2152  InvalidateOnErrorScope(Sema &SemaRef, Decl *D, bool Enabled)
2153      : Trap(SemaRef.Diags), D(D), Enabled(Enabled) {}
2154  ~InvalidateOnErrorScope() {
2155    if (Enabled && Trap.hasErrorOccurred())
2156      D->setInvalidDecl();
2157  }
2158
2159  DiagnosticErrorTrap Trap;
2160  Decl *D;
2161  bool Enabled;
2162};
2163}
2164
2165/// BuildCXXForRangeStmt - Build or instantiate a C++11 for-range statement.
2166StmtResult
2167Sema::BuildCXXForRangeStmt(SourceLocation ForLoc, SourceLocation CoawaitLoc,
2168                           SourceLocation ColonLoc, Stmt *RangeDecl,
2169                           Stmt *Begin, Stmt *End, Expr *Cond,
2170                           Expr *Inc, Stmt *LoopVarDecl,
2171                           SourceLocation RParenLoc, BuildForRangeKind Kind) {
2172  // FIXME: This should not be used during template instantiation. We should
2173  // pick up the set of unqualified lookup results for the != and + operators
2174  // in the initial parse.
2175  //
2176  // Testcase (accepts-invalid):
2177  //   template<typename T> void f() { for (auto x : T()) {} }
2178  //   namespace N { struct X { X begin(); X end(); int operator*(); }; }
2179  //   bool operator!=(N::X, N::X); void operator++(N::X);
2180  //   void g() { f<N::X>(); }
2181  Scope *S = getCurScope();
2182
2183  DeclStmt *RangeDS = cast<DeclStmt>(RangeDecl);
2184  VarDecl *RangeVar = cast<VarDecl>(RangeDS->getSingleDecl());
2185  QualType RangeVarType = RangeVar->getType();
2186
2187  DeclStmt *LoopVarDS = cast<DeclStmt>(LoopVarDecl);
2188  VarDecl *LoopVar = cast<VarDecl>(LoopVarDS->getSingleDecl());
2189
2190  // If we hit any errors, mark the loop variable as invalid if its type
2191  // contains 'auto'.
2192  InvalidateOnErrorScope Invalidate(*this, LoopVar,
2193                                    LoopVar->getType()->isUndeducedType());
2194
2195  StmtResult BeginDeclStmt = Begin;
2196  StmtResult EndDeclStmt = End;
2197  ExprResult NotEqExpr = Cond, IncrExpr = Inc;
2198
2199  if (RangeVarType->isDependentType()) {
2200    // The range is implicitly used as a placeholder when it is dependent.
2201    RangeVar->markUsed(Context);
2202
2203    // Deduce any 'auto's in the loop variable as 'DependentTy'. We'll fill
2204    // them in properly when we instantiate the loop.
2205    if (!LoopVar->isInvalidDecl() && Kind != BFRK_Check)
2206      LoopVar->setType(SubstAutoType(LoopVar->getType(), Context.DependentTy));
2207  } else if (!BeginDeclStmt.get()) {
2208    SourceLocation RangeLoc = RangeVar->getLocation();
2209
2210    const QualType RangeVarNonRefType = RangeVarType.getNonReferenceType();
2211
2212    ExprResult BeginRangeRef = BuildDeclRefExpr(RangeVar, RangeVarNonRefType,
2213                                                VK_LValue, ColonLoc);
2214    if (BeginRangeRef.isInvalid())
2215      return StmtError();
2216
2217    ExprResult EndRangeRef = BuildDeclRefExpr(RangeVar, RangeVarNonRefType,
2218                                              VK_LValue, ColonLoc);
2219    if (EndRangeRef.isInvalid())
2220      return StmtError();
2221
2222    QualType AutoType = Context.getAutoDeductType();
2223    Expr *Range = RangeVar->getInit();
2224    if (!Range)
2225      return StmtError();
2226    QualType RangeType = Range->getType();
2227
2228    if (RequireCompleteType(RangeLoc, RangeType,
2229                            diag::err_for_range_incomplete_type))
2230      return StmtError();
2231
2232    // Build auto __begin = begin-expr, __end = end-expr.
2233    VarDecl *BeginVar = BuildForRangeVarDecl(*this, ColonLoc, AutoType,
2234                                             "__begin");
2235    VarDecl *EndVar = BuildForRangeVarDecl(*this, ColonLoc, AutoType,
2236                                           "__end");
2237
2238    // Build begin-expr and end-expr and attach to __begin and __end variables.
2239    ExprResult BeginExpr, EndExpr;
2240    if (const ArrayType *UnqAT = RangeType->getAsArrayTypeUnsafe()) {
2241      // - if _RangeT is an array type, begin-expr and end-expr are __range and
2242      //   __range + __bound, respectively, where __bound is the array bound. If
2243      //   _RangeT is an array of unknown size or an array of incomplete type,
2244      //   the program is ill-formed;
2245
2246      // begin-expr is __range.
2247      BeginExpr = BeginRangeRef;
2248      if (FinishForRangeVarDecl(*this, BeginVar, BeginRangeRef.get(), ColonLoc,
2249                                diag::err_for_range_iter_deduction_failure)) {
2250        NoteForRangeBeginEndFunction(*this, BeginExpr.get(), BEF_begin);
2251        return StmtError();
2252      }
2253
2254      // Find the array bound.
2255      ExprResult BoundExpr;
2256      if (const ConstantArrayType *CAT = dyn_cast<ConstantArrayType>(UnqAT))
2257        BoundExpr = IntegerLiteral::Create(
2258            Context, CAT->getSize(), Context.getPointerDiffType(), RangeLoc);
2259      else if (const VariableArrayType *VAT =
2260               dyn_cast<VariableArrayType>(UnqAT))
2261        BoundExpr = VAT->getSizeExpr();
2262      else {
2263        // Can't be a DependentSizedArrayType or an IncompleteArrayType since
2264        // UnqAT is not incomplete and Range is not type-dependent.
2265        llvm_unreachable("Unexpected array type in for-range");
2266      }
2267
2268      // end-expr is __range + __bound.
2269      EndExpr = ActOnBinOp(S, ColonLoc, tok::plus, EndRangeRef.get(),
2270                           BoundExpr.get());
2271      if (EndExpr.isInvalid())
2272        return StmtError();
2273      if (FinishForRangeVarDecl(*this, EndVar, EndExpr.get(), ColonLoc,
2274                                diag::err_for_range_iter_deduction_failure)) {
2275        NoteForRangeBeginEndFunction(*this, EndExpr.get(), BEF_end);
2276        return StmtError();
2277      }
2278    } else {
2279      OverloadCandidateSet CandidateSet(RangeLoc,
2280                                        OverloadCandidateSet::CSK_Normal);
2281      BeginEndFunction BEFFailure;
2282      ForRangeStatus RangeStatus =
2283          BuildNonArrayForRange(*this, BeginRangeRef.get(),
2284                                EndRangeRef.get(), RangeType,
2285                                BeginVar, EndVar, ColonLoc, &CandidateSet,
2286                                &BeginExpr, &EndExpr, &BEFFailure);
2287
2288      if (Kind == BFRK_Build && RangeStatus == FRS_NoViableFunction &&
2289          BEFFailure == BEF_begin) {
2290        // If the range is being built from an array parameter, emit a
2291        // a diagnostic that it is being treated as a pointer.
2292        if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(Range)) {
2293          if (ParmVarDecl *PVD = dyn_cast<ParmVarDecl>(DRE->getDecl())) {
2294            QualType ArrayTy = PVD->getOriginalType();
2295            QualType PointerTy = PVD->getType();
2296            if (PointerTy->isPointerType() && ArrayTy->isArrayType()) {
2297              Diag(Range->getLocStart(), diag::err_range_on_array_parameter)
2298                << RangeLoc << PVD << ArrayTy << PointerTy;
2299              Diag(PVD->getLocation(), diag::note_declared_at);
2300              return StmtError();
2301            }
2302          }
2303        }
2304
2305        // If building the range failed, try dereferencing the range expression
2306        // unless a diagnostic was issued or the end function is problematic.
2307        StmtResult SR = RebuildForRangeWithDereference(*this, S, ForLoc,
2308                                                       CoawaitLoc,
2309                                                       LoopVarDecl, ColonLoc,
2310                                                       Range, RangeLoc,
2311                                                       RParenLoc);
2312        if (SR.isInvalid() || SR.isUsable())
2313          return SR;
2314      }
2315
2316      // Otherwise, emit diagnostics if we haven't already.
2317      if (RangeStatus == FRS_NoViableFunction) {
2318        Expr *Range = BEFFailure ? EndRangeRef.get() : BeginRangeRef.get();
2319        Diag(Range->getLocStart(), diag::err_for_range_invalid)
2320            << RangeLoc << Range->getType() << BEFFailure;
2321        CandidateSet.NoteCandidates(*this, OCD_AllCandidates, Range);
2322      }
2323      // Return an error if no fix was discovered.
2324      if (RangeStatus != FRS_Success)
2325        return StmtError();
2326    }
2327
2328    assert(!BeginExpr.isInvalid() && !EndExpr.isInvalid() &&
2329           "invalid range expression in for loop");
2330
2331    // C++11 [dcl.spec.auto]p7: BeginType and EndType must be the same.
2332    // C++1z removes this restriction.
2333    QualType BeginType = BeginVar->getType(), EndType = EndVar->getType();
2334    if (!Context.hasSameType(BeginType, EndType)) {
2335      Diag(RangeLoc, getLangOpts().CPlusPlus1z
2336                         ? diag::warn_for_range_begin_end_types_differ
2337                         : diag::ext_for_range_begin_end_types_differ)
2338          << BeginType << EndType;
2339      NoteForRangeBeginEndFunction(*this, BeginExpr.get(), BEF_begin);
2340      NoteForRangeBeginEndFunction(*this, EndExpr.get(), BEF_end);
2341    }
2342
2343    BeginDeclStmt =
2344        ActOnDeclStmt(ConvertDeclToDeclGroup(BeginVar), ColonLoc, ColonLoc);
2345    EndDeclStmt =
2346        ActOnDeclStmt(ConvertDeclToDeclGroup(EndVar), ColonLoc, ColonLoc);
2347
2348    const QualType BeginRefNonRefType = BeginType.getNonReferenceType();
2349    ExprResult BeginRef = BuildDeclRefExpr(BeginVar, BeginRefNonRefType,
2350                                           VK_LValue, ColonLoc);
2351    if (BeginRef.isInvalid())
2352      return StmtError();
2353
2354    ExprResult EndRef = BuildDeclRefExpr(EndVar, EndType.getNonReferenceType(),
2355                                         VK_LValue, ColonLoc);
2356    if (EndRef.isInvalid())
2357      return StmtError();
2358
2359    // Build and check __begin != __end expression.
2360    NotEqExpr = ActOnBinOp(S, ColonLoc, tok::exclaimequal,
2361                           BeginRef.get(), EndRef.get());
2362    if (!NotEqExpr.isInvalid())
2363      NotEqExpr = CheckBooleanCondition(ColonLoc, NotEqExpr.get());
2364    if (!NotEqExpr.isInvalid())
2365      NotEqExpr = ActOnFinishFullExpr(NotEqExpr.get());
2366    if (NotEqExpr.isInvalid()) {
2367      Diag(RangeLoc, diag::note_for_range_invalid_iterator)
2368        << RangeLoc << 0 << BeginRangeRef.get()->getType();
2369      NoteForRangeBeginEndFunction(*this, BeginExpr.get(), BEF_begin);
2370      if (!Context.hasSameType(BeginType, EndType))
2371        NoteForRangeBeginEndFunction(*this, EndExpr.get(), BEF_end);
2372      return StmtError();
2373    }
2374
2375    // Build and check ++__begin expression.
2376    BeginRef = BuildDeclRefExpr(BeginVar, BeginRefNonRefType,
2377                                VK_LValue, ColonLoc);
2378    if (BeginRef.isInvalid())
2379      return StmtError();
2380
2381    IncrExpr = ActOnUnaryOp(S, ColonLoc, tok::plusplus, BeginRef.get());
2382    if (!IncrExpr.isInvalid() && CoawaitLoc.isValid())
2383      IncrExpr = ActOnCoawaitExpr(S, CoawaitLoc, IncrExpr.get());
2384    if (!IncrExpr.isInvalid())
2385      IncrExpr = ActOnFinishFullExpr(IncrExpr.get());
2386    if (IncrExpr.isInvalid()) {
2387      Diag(RangeLoc, diag::note_for_range_invalid_iterator)
2388        << RangeLoc << 2 << BeginRangeRef.get()->getType() ;
2389      NoteForRangeBeginEndFunction(*this, BeginExpr.get(), BEF_begin);
2390      return StmtError();
2391    }
2392
2393    // Build and check *__begin  expression.
2394    BeginRef = BuildDeclRefExpr(BeginVar, BeginRefNonRefType,
2395                                VK_LValue, ColonLoc);
2396    if (BeginRef.isInvalid())
2397      return StmtError();
2398
2399    ExprResult DerefExpr = ActOnUnaryOp(S, ColonLoc, tok::star, BeginRef.get());
2400    if (DerefExpr.isInvalid()) {
2401      Diag(RangeLoc, diag::note_for_range_invalid_iterator)
2402        << RangeLoc << 1 << BeginRangeRef.get()->getType();
2403      NoteForRangeBeginEndFunction(*this, BeginExpr.get(), BEF_begin);
2404      return StmtError();
2405    }
2406
2407    // Attach  *__begin  as initializer for VD. Don't touch it if we're just
2408    // trying to determine whether this would be a valid range.
2409    if (!LoopVar->isInvalidDecl() && Kind != BFRK_Check) {
2410      AddInitializerToDecl(LoopVar, DerefExpr.get(), /*DirectInit=*/false,
2411                           /*TypeMayContainAuto=*/true);
2412      if (LoopVar->isInvalidDecl())
2413        NoteForRangeBeginEndFunction(*this, BeginExpr.get(), BEF_begin);
2414    }
2415  }
2416
2417  // Don't bother to actually allocate the result if we're just trying to
2418  // determine whether it would be valid.
2419  if (Kind == BFRK_Check)
2420    return StmtResult();
2421
2422  return new (Context) CXXForRangeStmt(
2423      RangeDS, cast_or_null<DeclStmt>(BeginDeclStmt.get()),
2424      cast_or_null<DeclStmt>(EndDeclStmt.get()), NotEqExpr.get(),
2425      IncrExpr.get(), LoopVarDS, /*Body=*/nullptr, ForLoc, CoawaitLoc,
2426      ColonLoc, RParenLoc);
2427}
2428
2429/// FinishObjCForCollectionStmt - Attach the body to a objective-C foreach
2430/// statement.
2431StmtResult Sema::FinishObjCForCollectionStmt(Stmt *S, Stmt *B) {
2432  if (!S || !B)
2433    return StmtError();
2434  ObjCForCollectionStmt * ForStmt = cast<ObjCForCollectionStmt>(S);
2435
2436  ForStmt->setBody(B);
2437  return S;
2438}
2439
2440// Warn when the loop variable is a const reference that creates a copy.
2441// Suggest using the non-reference type for copies.  If a copy can be prevented
2442// suggest the const reference type that would do so.
2443// For instance, given "for (const &Foo : Range)", suggest
2444// "for (const Foo : Range)" to denote a copy is made for the loop.  If
2445// possible, also suggest "for (const &Bar : Range)" if this type prevents
2446// the copy altogether.
2447static void DiagnoseForRangeReferenceVariableCopies(Sema &SemaRef,
2448                                                    const VarDecl *VD,
2449                                                    QualType RangeInitType) {
2450  const Expr *InitExpr = VD->getInit();
2451  if (!InitExpr)
2452    return;
2453
2454  QualType VariableType = VD->getType();
2455
2456  if (auto Cleanups = dyn_cast<ExprWithCleanups>(InitExpr))
2457    if (!Cleanups->cleanupsHaveSideEffects())
2458      InitExpr = Cleanups->getSubExpr();
2459
2460  const MaterializeTemporaryExpr *MTE =
2461      dyn_cast<MaterializeTemporaryExpr>(InitExpr);
2462
2463  // No copy made.
2464  if (!MTE)
2465    return;
2466
2467  const Expr *E = MTE->GetTemporaryExpr()->IgnoreImpCasts();
2468
2469  // Searching for either UnaryOperator for dereference of a pointer or
2470  // CXXOperatorCallExpr for handling iterators.
2471  while (!isa<CXXOperatorCallExpr>(E) && !isa<UnaryOperator>(E)) {
2472    if (const CXXConstructExpr *CCE = dyn_cast<CXXConstructExpr>(E)) {
2473      E = CCE->getArg(0);
2474    } else if (const CXXMemberCallExpr *Call = dyn_cast<CXXMemberCallExpr>(E)) {
2475      const MemberExpr *ME = cast<MemberExpr>(Call->getCallee());
2476      E = ME->getBase();
2477    } else {
2478      const MaterializeTemporaryExpr *MTE = cast<MaterializeTemporaryExpr>(E);
2479      E = MTE->GetTemporaryExpr();
2480    }
2481    E = E->IgnoreImpCasts();
2482  }
2483
2484  bool ReturnsReference = false;
2485  if (isa<UnaryOperator>(E)) {
2486    ReturnsReference = true;
2487  } else {
2488    const CXXOperatorCallExpr *Call = cast<CXXOperatorCallExpr>(E);
2489    const FunctionDecl *FD = Call->getDirectCallee();
2490    QualType ReturnType = FD->getReturnType();
2491    ReturnsReference = ReturnType->isReferenceType();
2492  }
2493
2494  if (ReturnsReference) {
2495    // Loop variable creates a temporary.  Suggest either to go with
2496    // non-reference loop variable to indiciate a copy is made, or
2497    // the correct time to bind a const reference.
2498    SemaRef.Diag(VD->getLocation(), diag::warn_for_range_const_reference_copy)
2499        << VD << VariableType << E->getType();
2500    QualType NonReferenceType = VariableType.getNonReferenceType();
2501    NonReferenceType.removeLocalConst();
2502    QualType NewReferenceType =
2503        SemaRef.Context.getLValueReferenceType(E->getType().withConst());
2504    SemaRef.Diag(VD->getLocStart(), diag::note_use_type_or_non_reference)
2505        << NonReferenceType << NewReferenceType << VD->getSourceRange();
2506  } else {
2507    // The range always returns a copy, so a temporary is always created.
2508    // Suggest removing the reference from the loop variable.
2509    SemaRef.Diag(VD->getLocation(), diag::warn_for_range_variable_always_copy)
2510        << VD << RangeInitType;
2511    QualType NonReferenceType = VariableType.getNonReferenceType();
2512    NonReferenceType.removeLocalConst();
2513    SemaRef.Diag(VD->getLocStart(), diag::note_use_non_reference_type)
2514        << NonReferenceType << VD->getSourceRange();
2515  }
2516}
2517
2518// Warns when the loop variable can be changed to a reference type to
2519// prevent a copy.  For instance, if given "for (const Foo x : Range)" suggest
2520// "for (const Foo &x : Range)" if this form does not make a copy.
2521static void DiagnoseForRangeConstVariableCopies(Sema &SemaRef,
2522                                                const VarDecl *VD) {
2523  const Expr *InitExpr = VD->getInit();
2524  if (!InitExpr)
2525    return;
2526
2527  QualType VariableType = VD->getType();
2528
2529  if (const CXXConstructExpr *CE = dyn_cast<CXXConstructExpr>(InitExpr)) {
2530    if (!CE->getConstructor()->isCopyConstructor())
2531      return;
2532  } else if (const CastExpr *CE = dyn_cast<CastExpr>(InitExpr)) {
2533    if (CE->getCastKind() != CK_LValueToRValue)
2534      return;
2535  } else {
2536    return;
2537  }
2538
2539  // TODO: Determine a maximum size that a POD type can be before a diagnostic
2540  // should be emitted.  Also, only ignore POD types with trivial copy
2541  // constructors.
2542  if (VariableType.isPODType(SemaRef.Context))
2543    return;
2544
2545  // Suggest changing from a const variable to a const reference variable
2546  // if doing so will prevent a copy.
2547  SemaRef.Diag(VD->getLocation(), diag::warn_for_range_copy)
2548      << VD << VariableType << InitExpr->getType();
2549  SemaRef.Diag(VD->getLocStart(), diag::note_use_reference_type)
2550      << SemaRef.Context.getLValueReferenceType(VariableType)
2551      << VD->getSourceRange();
2552}
2553
2554/// DiagnoseForRangeVariableCopies - Diagnose three cases and fixes for them.
2555/// 1) for (const foo &x : foos) where foos only returns a copy.  Suggest
2556///    using "const foo x" to show that a copy is made
2557/// 2) for (const bar &x : foos) where bar is a temporary intialized by bar.
2558///    Suggest either "const bar x" to keep the copying or "const foo& x" to
2559///    prevent the copy.
2560/// 3) for (const foo x : foos) where x is constructed from a reference foo.
2561///    Suggest "const foo &x" to prevent the copy.
2562static void DiagnoseForRangeVariableCopies(Sema &SemaRef,
2563                                           const CXXForRangeStmt *ForStmt) {
2564  if (SemaRef.Diags.isIgnored(diag::warn_for_range_const_reference_copy,
2565                              ForStmt->getLocStart()) &&
2566      SemaRef.Diags.isIgnored(diag::warn_for_range_variable_always_copy,
2567                              ForStmt->getLocStart()) &&
2568      SemaRef.Diags.isIgnored(diag::warn_for_range_copy,
2569                              ForStmt->getLocStart())) {
2570    return;
2571  }
2572
2573  const VarDecl *VD = ForStmt->getLoopVariable();
2574  if (!VD)
2575    return;
2576
2577  QualType VariableType = VD->getType();
2578
2579  if (VariableType->isIncompleteType())
2580    return;
2581
2582  const Expr *InitExpr = VD->getInit();
2583  if (!InitExpr)
2584    return;
2585
2586  if (VariableType->isReferenceType()) {
2587    DiagnoseForRangeReferenceVariableCopies(SemaRef, VD,
2588                                            ForStmt->getRangeInit()->getType());
2589  } else if (VariableType.isConstQualified()) {
2590    DiagnoseForRangeConstVariableCopies(SemaRef, VD);
2591  }
2592}
2593
2594/// FinishCXXForRangeStmt - Attach the body to a C++0x for-range statement.
2595/// This is a separate step from ActOnCXXForRangeStmt because analysis of the
2596/// body cannot be performed until after the type of the range variable is
2597/// determined.
2598StmtResult Sema::FinishCXXForRangeStmt(Stmt *S, Stmt *B) {
2599  if (!S || !B)
2600    return StmtError();
2601
2602  if (isa<ObjCForCollectionStmt>(S))
2603    return FinishObjCForCollectionStmt(S, B);
2604
2605  CXXForRangeStmt *ForStmt = cast<CXXForRangeStmt>(S);
2606  ForStmt->setBody(B);
2607
2608  DiagnoseEmptyStmtBody(ForStmt->getRParenLoc(), B,
2609                        diag::warn_empty_range_based_for_body);
2610
2611  DiagnoseForRangeVariableCopies(*this, ForStmt);
2612
2613  return S;
2614}
2615
2616StmtResult Sema::ActOnGotoStmt(SourceLocation GotoLoc,
2617                               SourceLocation LabelLoc,
2618                               LabelDecl *TheDecl) {
2619  getCurFunction()->setHasBranchIntoScope();
2620  TheDecl->markUsed(Context);
2621  return new (Context) GotoStmt(TheDecl, GotoLoc, LabelLoc);
2622}
2623
2624StmtResult
2625Sema::ActOnIndirectGotoStmt(SourceLocation GotoLoc, SourceLocation StarLoc,
2626                            Expr *E) {
2627  // Convert operand to void*
2628  if (!E->isTypeDependent()) {
2629    QualType ETy = E->getType();
2630    QualType DestTy = Context.getPointerType(Context.VoidTy.withConst());
2631    ExprResult ExprRes = E;
2632    AssignConvertType ConvTy =
2633      CheckSingleAssignmentConstraints(DestTy, ExprRes);
2634    if (ExprRes.isInvalid())
2635      return StmtError();
2636    E = ExprRes.get();
2637    if (DiagnoseAssignmentResult(ConvTy, StarLoc, DestTy, ETy, E, AA_Passing))
2638      return StmtError();
2639  }
2640
2641  ExprResult ExprRes = ActOnFinishFullExpr(E);
2642  if (ExprRes.isInvalid())
2643    return StmtError();
2644  E = ExprRes.get();
2645
2646  getCurFunction()->setHasIndirectGoto();
2647
2648  return new (Context) IndirectGotoStmt(GotoLoc, StarLoc, E);
2649}
2650
2651static void CheckJumpOutOfSEHFinally(Sema &S, SourceLocation Loc,
2652                                     const Scope &DestScope) {
2653  if (!S.CurrentSEHFinally.empty() &&
2654      DestScope.Contains(*S.CurrentSEHFinally.back())) {
2655    S.Diag(Loc, diag::warn_jump_out_of_seh_finally);
2656  }
2657}
2658
2659StmtResult
2660Sema::ActOnContinueStmt(SourceLocation ContinueLoc, Scope *CurScope) {
2661  Scope *S = CurScope->getContinueParent();
2662  if (!S) {
2663    // C99 6.8.6.2p1: A break shall appear only in or as a loop body.
2664    return StmtError(Diag(ContinueLoc, diag::err_continue_not_in_loop));
2665  }
2666  CheckJumpOutOfSEHFinally(*this, ContinueLoc, *S);
2667
2668  return new (Context) ContinueStmt(ContinueLoc);
2669}
2670
2671StmtResult
2672Sema::ActOnBreakStmt(SourceLocation BreakLoc, Scope *CurScope) {
2673  Scope *S = CurScope->getBreakParent();
2674  if (!S) {
2675    // C99 6.8.6.3p1: A break shall appear only in or as a switch/loop body.
2676    return StmtError(Diag(BreakLoc, diag::err_break_not_in_loop_or_switch));
2677  }
2678  if (S->isOpenMPLoopScope())
2679    return StmtError(Diag(BreakLoc, diag::err_omp_loop_cannot_use_stmt)
2680                     << "break");
2681  CheckJumpOutOfSEHFinally(*this, BreakLoc, *S);
2682
2683  return new (Context) BreakStmt(BreakLoc);
2684}
2685
2686/// \brief Determine whether the given expression is a candidate for
2687/// copy elision in either a return statement or a throw expression.
2688///
2689/// \param ReturnType If we're determining the copy elision candidate for
2690/// a return statement, this is the return type of the function. If we're
2691/// determining the copy elision candidate for a throw expression, this will
2692/// be a NULL type.
2693///
2694/// \param E The expression being returned from the function or block, or
2695/// being thrown.
2696///
2697/// \param AllowParamOrMoveConstructible Whether we allow function parameters or
2698/// id-expressions that could be moved out of the function to be considered NRVO
2699/// candidates. C++ prohibits these for NRVO itself, but we re-use this logic to
2700/// determine whether we should try to move as part of a return or throw (which
2701/// does allow function parameters).
2702///
2703/// \returns The NRVO candidate variable, if the return statement may use the
2704/// NRVO, or NULL if there is no such candidate.
2705VarDecl *Sema::getCopyElisionCandidate(QualType ReturnType, Expr *E,
2706                                       bool AllowParamOrMoveConstructible) {
2707  if (!getLangOpts().CPlusPlus)
2708    return nullptr;
2709
2710  // - in a return statement in a function [where] ...
2711  // ... the expression is the name of a non-volatile automatic object ...
2712  DeclRefExpr *DR = dyn_cast<DeclRefExpr>(E->IgnoreParens());
2713  if (!DR || DR->refersToEnclosingVariableOrCapture())
2714    return nullptr;
2715  VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl());
2716  if (!VD)
2717    return nullptr;
2718
2719  if (isCopyElisionCandidate(ReturnType, VD, AllowParamOrMoveConstructible))
2720    return VD;
2721  return nullptr;
2722}
2723
2724bool Sema::isCopyElisionCandidate(QualType ReturnType, const VarDecl *VD,
2725                                  bool AllowParamOrMoveConstructible) {
2726  QualType VDType = VD->getType();
2727  // - in a return statement in a function with ...
2728  // ... a class return type ...
2729  if (!ReturnType.isNull() && !ReturnType->isDependentType()) {
2730    if (!ReturnType->isRecordType())
2731      return false;
2732    // ... the same cv-unqualified type as the function return type ...
2733    // When considering moving this expression out, allow dissimilar types.
2734    if (!AllowParamOrMoveConstructible && !VDType->isDependentType() &&
2735        !Context.hasSameUnqualifiedType(ReturnType, VDType))
2736      return false;
2737  }
2738
2739  // ...object (other than a function or catch-clause parameter)...
2740  if (VD->getKind() != Decl::Var &&
2741      !(AllowParamOrMoveConstructible && VD->getKind() == Decl::ParmVar))
2742    return false;
2743  if (VD->isExceptionVariable()) return false;
2744
2745  // ...automatic...
2746  if (!VD->hasLocalStorage()) return false;
2747
2748  if (AllowParamOrMoveConstructible)
2749    return true;
2750
2751  // ...non-volatile...
2752  if (VD->getType().isVolatileQualified()) return false;
2753
2754  // __block variables can't be allocated in a way that permits NRVO.
2755  if (VD->hasAttr<BlocksAttr>()) return false;
2756
2757  // Variables with higher required alignment than their type's ABI
2758  // alignment cannot use NRVO.
2759  if (!VD->getType()->isDependentType() && VD->hasAttr<AlignedAttr>() &&
2760      Context.getDeclAlign(VD) > Context.getTypeAlignInChars(VD->getType()))
2761    return false;
2762
2763  return true;
2764}
2765
2766/// \brief Perform the initialization of a potentially-movable value, which
2767/// is the result of return value.
2768///
2769/// This routine implements C++14 [class.copy]p32, which attempts to treat
2770/// returned lvalues as rvalues in certain cases (to prefer move construction),
2771/// then falls back to treating them as lvalues if that failed.
2772ExprResult
2773Sema::PerformMoveOrCopyInitialization(const InitializedEntity &Entity,
2774                                      const VarDecl *NRVOCandidate,
2775                                      QualType ResultType,
2776                                      Expr *Value,
2777                                      bool AllowNRVO) {
2778  // C++14 [class.copy]p32:
2779  // When the criteria for elision of a copy/move operation are met, but not for
2780  // an exception-declaration, and the object to be copied is designated by an
2781  // lvalue, or when the expression in a return statement is a (possibly
2782  // parenthesized) id-expression that names an object with automatic storage
2783  // duration declared in the body or parameter-declaration-clause of the
2784  // innermost enclosing function or lambda-expression, overload resolution to
2785  // select the constructor for the copy is first performed as if the object
2786  // were designated by an rvalue.
2787  ExprResult Res = ExprError();
2788
2789  if (AllowNRVO && !NRVOCandidate)
2790    NRVOCandidate = getCopyElisionCandidate(ResultType, Value, true);
2791
2792  if (AllowNRVO && NRVOCandidate) {
2793    ImplicitCastExpr AsRvalue(ImplicitCastExpr::OnStack, Value->getType(),
2794                              CK_NoOp, Value, VK_XValue);
2795
2796    Expr *InitExpr = &AsRvalue;
2797
2798    InitializationKind Kind = InitializationKind::CreateCopy(
2799        Value->getLocStart(), Value->getLocStart());
2800
2801    InitializationSequence Seq(*this, Entity, Kind, InitExpr);
2802    if (Seq) {
2803      for (const InitializationSequence::Step &Step : Seq.steps()) {
2804        if (!(Step.Kind ==
2805                  InitializationSequence::SK_ConstructorInitialization ||
2806              (Step.Kind == InitializationSequence::SK_UserConversion &&
2807               isa<CXXConstructorDecl>(Step.Function.Function))))
2808          continue;
2809
2810        CXXConstructorDecl *Constructor =
2811            cast<CXXConstructorDecl>(Step.Function.Function);
2812
2813        const RValueReferenceType *RRefType
2814          = Constructor->getParamDecl(0)->getType()
2815                                                 ->getAs<RValueReferenceType>();
2816
2817        // [...] If the first overload resolution fails or was not performed, or
2818        // if the type of the first parameter of the selected constructor is not
2819        // an rvalue reference to the object’s type (possibly cv-qualified),
2820        // overload resolution is performed again, considering the object as an
2821        // lvalue.
2822        if (!RRefType ||
2823            !Context.hasSameUnqualifiedType(RRefType->getPointeeType(),
2824                                            NRVOCandidate->getType()))
2825          break;
2826
2827        // Promote "AsRvalue" to the heap, since we now need this
2828        // expression node to persist.
2829        Value = ImplicitCastExpr::Create(Context, Value->getType(), CK_NoOp,
2830                                         Value, nullptr, VK_XValue);
2831
2832        // Complete type-checking the initialization of the return type
2833        // using the constructor we found.
2834        Res = Seq.Perform(*this, Entity, Kind, Value);
2835      }
2836    }
2837  }
2838
2839  // Either we didn't meet the criteria for treating an lvalue as an rvalue,
2840  // above, or overload resolution failed. Either way, we need to try
2841  // (again) now with the return value expression as written.
2842  if (Res.isInvalid())
2843    Res = PerformCopyInitialization(Entity, SourceLocation(), Value);
2844
2845  return Res;
2846}
2847
2848/// \brief Determine whether the declared return type of the specified function
2849/// contains 'auto'.
2850static bool hasDeducedReturnType(FunctionDecl *FD) {
2851  const FunctionProtoType *FPT =
2852      FD->getTypeSourceInfo()->getType()->castAs<FunctionProtoType>();
2853  return FPT->getReturnType()->isUndeducedType();
2854}
2855
2856/// ActOnCapScopeReturnStmt - Utility routine to type-check return statements
2857/// for capturing scopes.
2858///
2859StmtResult
2860Sema::ActOnCapScopeReturnStmt(SourceLocation ReturnLoc, Expr *RetValExp) {
2861  // If this is the first return we've seen, infer the return type.
2862  // [expr.prim.lambda]p4 in C++11; block literals follow the same rules.
2863  CapturingScopeInfo *CurCap = cast<CapturingScopeInfo>(getCurFunction());
2864  QualType FnRetType = CurCap->ReturnType;
2865  LambdaScopeInfo *CurLambda = dyn_cast<LambdaScopeInfo>(CurCap);
2866  bool HasDeducedReturnType =
2867      CurLambda && hasDeducedReturnType(CurLambda->CallOperator);
2868
2869  if (ExprEvalContexts.back().Context == DiscardedStatement &&
2870      (HasDeducedReturnType || CurCap->HasImplicitReturnType)) {
2871    if (RetValExp) {
2872      ExprResult ER = ActOnFinishFullExpr(RetValExp, ReturnLoc);
2873      if (ER.isInvalid())
2874        return StmtError();
2875      RetValExp = ER.get();
2876    }
2877    return new (Context) ReturnStmt(ReturnLoc, RetValExp, nullptr);
2878  }
2879
2880  if (HasDeducedReturnType) {
2881    // In C++1y, the return type may involve 'auto'.
2882    // FIXME: Blocks might have a return type of 'auto' explicitly specified.
2883    FunctionDecl *FD = CurLambda->CallOperator;
2884    if (CurCap->ReturnType.isNull())
2885      CurCap->ReturnType = FD->getReturnType();
2886
2887    AutoType *AT = CurCap->ReturnType->getContainedAutoType();
2888    assert(AT && "lost auto type from lambda return type");
2889    if (DeduceFunctionTypeFromReturnExpr(FD, ReturnLoc, RetValExp, AT)) {
2890      FD->setInvalidDecl();
2891      return StmtError();
2892    }
2893    CurCap->ReturnType = FnRetType = FD->getReturnType();
2894  } else if (CurCap->HasImplicitReturnType) {
2895    // For blocks/lambdas with implicit return types, we check each return
2896    // statement individually, and deduce the common return type when the block
2897    // or lambda is completed.
2898    // FIXME: Fold this into the 'auto' codepath above.
2899    if (RetValExp && !isa<InitListExpr>(RetValExp)) {
2900      ExprResult Result = DefaultFunctionArrayLvalueConversion(RetValExp);
2901      if (Result.isInvalid())
2902        return StmtError();
2903      RetValExp = Result.get();
2904
2905      // DR1048: even prior to C++14, we should use the 'auto' deduction rules
2906      // when deducing a return type for a lambda-expression (or by extension
2907      // for a block). These rules differ from the stated C++11 rules only in
2908      // that they remove top-level cv-qualifiers.
2909      if (!CurContext->isDependentContext())
2910        FnRetType = RetValExp->getType().getUnqualifiedType();
2911      else
2912        FnRetType = CurCap->ReturnType = Context.DependentTy;
2913    } else {
2914      if (RetValExp) {
2915        // C++11 [expr.lambda.prim]p4 bans inferring the result from an
2916        // initializer list, because it is not an expression (even
2917        // though we represent it as one). We still deduce 'void'.
2918        Diag(ReturnLoc, diag::err_lambda_return_init_list)
2919          << RetValExp->getSourceRange();
2920      }
2921
2922      FnRetType = Context.VoidTy;
2923    }
2924
2925    // Although we'll properly infer the type of the block once it's completed,
2926    // make sure we provide a return type now for better error recovery.
2927    if (CurCap->ReturnType.isNull())
2928      CurCap->ReturnType = FnRetType;
2929  }
2930  assert(!FnRetType.isNull());
2931
2932  if (BlockScopeInfo *CurBlock = dyn_cast<BlockScopeInfo>(CurCap)) {
2933    if (CurBlock->FunctionType->getAs<FunctionType>()->getNoReturnAttr()) {
2934      Diag(ReturnLoc, diag::err_noreturn_block_has_return_expr);
2935      return StmtError();
2936    }
2937  } else if (CapturedRegionScopeInfo *CurRegion =
2938                 dyn_cast<CapturedRegionScopeInfo>(CurCap)) {
2939    Diag(ReturnLoc, diag::err_return_in_captured_stmt) << CurRegion->getRegionName();
2940    return StmtError();
2941  } else {
2942    assert(CurLambda && "unknown kind of captured scope");
2943    if (CurLambda->CallOperator->getType()->getAs<FunctionType>()
2944            ->getNoReturnAttr()) {
2945      Diag(ReturnLoc, diag::err_noreturn_lambda_has_return_expr);
2946      return StmtError();
2947    }
2948  }
2949
2950  // Otherwise, verify that this result type matches the previous one.  We are
2951  // pickier with blocks than for normal functions because we don't have GCC
2952  // compatibility to worry about here.
2953  const VarDecl *NRVOCandidate = nullptr;
2954  if (FnRetType->isDependentType()) {
2955    // Delay processing for now.  TODO: there are lots of dependent
2956    // types we can conclusively prove aren't void.
2957  } else if (FnRetType->isVoidType()) {
2958    if (RetValExp && !isa<InitListExpr>(RetValExp) &&
2959        !(getLangOpts().CPlusPlus &&
2960          (RetValExp->isTypeDependent() ||
2961           RetValExp->getType()->isVoidType()))) {
2962      if (!getLangOpts().CPlusPlus &&
2963          RetValExp->getType()->isVoidType())
2964        Diag(ReturnLoc, diag::ext_return_has_void_expr) << "literal" << 2;
2965      else {
2966        Diag(ReturnLoc, diag::err_return_block_has_expr);
2967        RetValExp = nullptr;
2968      }
2969    }
2970  } else if (!RetValExp) {
2971    return StmtError(Diag(ReturnLoc, diag::err_block_return_missing_expr));
2972  } else if (!RetValExp->isTypeDependent()) {
2973    // we have a non-void block with an expression, continue checking
2974
2975    // C99 6.8.6.4p3(136): The return statement is not an assignment. The
2976    // overlap restriction of subclause 6.5.16.1 does not apply to the case of
2977    // function return.
2978
2979    // In C++ the return statement is handled via a copy initialization.
2980    // the C version of which boils down to CheckSingleAssignmentConstraints.
2981    NRVOCandidate = getCopyElisionCandidate(FnRetType, RetValExp, false);
2982    InitializedEntity Entity = InitializedEntity::InitializeResult(ReturnLoc,
2983                                                                   FnRetType,
2984                                                      NRVOCandidate != nullptr);
2985    ExprResult Res = PerformMoveOrCopyInitialization(Entity, NRVOCandidate,
2986                                                     FnRetType, RetValExp);
2987    if (Res.isInvalid()) {
2988      // FIXME: Cleanup temporaries here, anyway?
2989      return StmtError();
2990    }
2991    RetValExp = Res.get();
2992    CheckReturnValExpr(RetValExp, FnRetType, ReturnLoc);
2993  } else {
2994    NRVOCandidate = getCopyElisionCandidate(FnRetType, RetValExp, false);
2995  }
2996
2997  if (RetValExp) {
2998    ExprResult ER = ActOnFinishFullExpr(RetValExp, ReturnLoc);
2999    if (ER.isInvalid())
3000      return StmtError();
3001    RetValExp = ER.get();
3002  }
3003  ReturnStmt *Result = new (Context) ReturnStmt(ReturnLoc, RetValExp,
3004                                                NRVOCandidate);
3005
3006  // If we need to check for the named return value optimization,
3007  // or if we need to infer the return type,
3008  // save the return statement in our scope for later processing.
3009  if (CurCap->HasImplicitReturnType || NRVOCandidate)
3010    FunctionScopes.back()->Returns.push_back(Result);
3011
3012  if (FunctionScopes.back()->FirstReturnLoc.isInvalid())
3013    FunctionScopes.back()->FirstReturnLoc = ReturnLoc;
3014
3015  return Result;
3016}
3017
3018namespace {
3019/// \brief Marks all typedefs in all local classes in a type referenced.
3020///
3021/// In a function like
3022/// auto f() {
3023///   struct S { typedef int a; };
3024///   return S();
3025/// }
3026///
3027/// the local type escapes and could be referenced in some TUs but not in
3028/// others. Pretend that all local typedefs are always referenced, to not warn
3029/// on this. This isn't necessary if f has internal linkage, or the typedef
3030/// is private.
3031class LocalTypedefNameReferencer
3032    : public RecursiveASTVisitor<LocalTypedefNameReferencer> {
3033public:
3034  LocalTypedefNameReferencer(Sema &S) : S(S) {}
3035  bool VisitRecordType(const RecordType *RT);
3036private:
3037  Sema &S;
3038};
3039bool LocalTypedefNameReferencer::VisitRecordType(const RecordType *RT) {
3040  auto *R = dyn_cast<CXXRecordDecl>(RT->getDecl());
3041  if (!R || !R->isLocalClass() || !R->isLocalClass()->isExternallyVisible() ||
3042      R->isDependentType())
3043    return true;
3044  for (auto *TmpD : R->decls())
3045    if (auto *T = dyn_cast<TypedefNameDecl>(TmpD))
3046      if (T->getAccess() != AS_private || R->hasFriends())
3047        S.MarkAnyDeclReferenced(T->getLocation(), T, /*OdrUse=*/false);
3048  return true;
3049}
3050}
3051
3052TypeLoc Sema::getReturnTypeLoc(FunctionDecl *FD) const {
3053  TypeLoc TL = FD->getTypeSourceInfo()->getTypeLoc().IgnoreParens();
3054  while (auto ATL = TL.getAs<AttributedTypeLoc>())
3055    TL = ATL.getModifiedLoc().IgnoreParens();
3056  return TL.castAs<FunctionProtoTypeLoc>().getReturnLoc();
3057}
3058
3059/// Deduce the return type for a function from a returned expression, per
3060/// C++1y [dcl.spec.auto]p6.
3061bool Sema::DeduceFunctionTypeFromReturnExpr(FunctionDecl *FD,
3062                                            SourceLocation ReturnLoc,
3063                                            Expr *&RetExpr,
3064                                            AutoType *AT) {
3065  TypeLoc OrigResultType = getReturnTypeLoc(FD);
3066  QualType Deduced;
3067
3068  if (RetExpr && isa<InitListExpr>(RetExpr)) {
3069    //  If the deduction is for a return statement and the initializer is
3070    //  a braced-init-list, the program is ill-formed.
3071    Diag(RetExpr->getExprLoc(),
3072         getCurLambda() ? diag::err_lambda_return_init_list
3073                        : diag::err_auto_fn_return_init_list)
3074        << RetExpr->getSourceRange();
3075    return true;
3076  }
3077
3078  if (FD->isDependentContext()) {
3079    // C++1y [dcl.spec.auto]p12:
3080    //   Return type deduction [...] occurs when the definition is
3081    //   instantiated even if the function body contains a return
3082    //   statement with a non-type-dependent operand.
3083    assert(AT->isDeduced() && "should have deduced to dependent type");
3084    return false;
3085  }
3086
3087  if (RetExpr) {
3088    //  Otherwise, [...] deduce a value for U using the rules of template
3089    //  argument deduction.
3090    DeduceAutoResult DAR = DeduceAutoType(OrigResultType, RetExpr, Deduced);
3091
3092    if (DAR == DAR_Failed && !FD->isInvalidDecl())
3093      Diag(RetExpr->getExprLoc(), diag::err_auto_fn_deduction_failure)
3094        << OrigResultType.getType() << RetExpr->getType();
3095
3096    if (DAR != DAR_Succeeded)
3097      return true;
3098
3099    // If a local type is part of the returned type, mark its fields as
3100    // referenced.
3101    LocalTypedefNameReferencer Referencer(*this);
3102    Referencer.TraverseType(RetExpr->getType());
3103  } else {
3104    //  In the case of a return with no operand, the initializer is considered
3105    //  to be void().
3106    //
3107    // Deduction here can only succeed if the return type is exactly 'cv auto'
3108    // or 'decltype(auto)', so just check for that case directly.
3109    if (!OrigResultType.getType()->getAs<AutoType>()) {
3110      Diag(ReturnLoc, diag::err_auto_fn_return_void_but_not_auto)
3111        << OrigResultType.getType();
3112      return true;
3113    }
3114    // We always deduce U = void in this case.
3115    Deduced = SubstAutoType(OrigResultType.getType(), Context.VoidTy);
3116    if (Deduced.isNull())
3117      return true;
3118  }
3119
3120  //  If a function with a declared return type that contains a placeholder type
3121  //  has multiple return statements, the return type is deduced for each return
3122  //  statement. [...] if the type deduced is not the same in each deduction,
3123  //  the program is ill-formed.
3124  QualType DeducedT = AT->getDeducedType();
3125  if (!DeducedT.isNull() && !FD->isInvalidDecl()) {
3126    AutoType *NewAT = Deduced->getContainedAutoType();
3127    // It is possible that NewAT->getDeducedType() is null. When that happens,
3128    // we should not crash, instead we ignore this deduction.
3129    if (NewAT->getDeducedType().isNull())
3130      return false;
3131
3132    CanQualType OldDeducedType = Context.getCanonicalFunctionResultType(
3133                                   DeducedT);
3134    CanQualType NewDeducedType = Context.getCanonicalFunctionResultType(
3135                                   NewAT->getDeducedType());
3136    if (!FD->isDependentContext() && OldDeducedType != NewDeducedType) {
3137      const LambdaScopeInfo *LambdaSI = getCurLambda();
3138      if (LambdaSI && LambdaSI->HasImplicitReturnType) {
3139        Diag(ReturnLoc, diag::err_typecheck_missing_return_type_incompatible)
3140          << NewAT->getDeducedType() << DeducedT
3141          << true /*IsLambda*/;
3142      } else {
3143        Diag(ReturnLoc, diag::err_auto_fn_different_deductions)
3144          << (AT->isDecltypeAuto() ? 1 : 0)
3145          << NewAT->getDeducedType() << DeducedT;
3146      }
3147      return true;
3148    }
3149  } else if (!FD->isInvalidDecl()) {
3150    // Update all declarations of the function to have the deduced return type.
3151    Context.adjustDeducedFunctionResultType(FD, Deduced);
3152  }
3153
3154  return false;
3155}
3156
3157StmtResult
3158Sema::ActOnReturnStmt(SourceLocation ReturnLoc, Expr *RetValExp,
3159                      Scope *CurScope) {
3160  StmtResult R = BuildReturnStmt(ReturnLoc, RetValExp);
3161  if (R.isInvalid() || ExprEvalContexts.back().Context == DiscardedStatement)
3162    return R;
3163
3164  if (VarDecl *VD =
3165      const_cast<VarDecl*>(cast<ReturnStmt>(R.get())->getNRVOCandidate())) {
3166    CurScope->addNRVOCandidate(VD);
3167  } else {
3168    CurScope->setNoNRVO();
3169  }
3170
3171  CheckJumpOutOfSEHFinally(*this, ReturnLoc, *CurScope->getFnParent());
3172
3173  return R;
3174}
3175
3176StmtResult Sema::BuildReturnStmt(SourceLocation ReturnLoc, Expr *RetValExp) {
3177  // Check for unexpanded parameter packs.
3178  if (RetValExp && DiagnoseUnexpandedParameterPack(RetValExp))
3179    return StmtError();
3180
3181  if (isa<CapturingScopeInfo>(getCurFunction()))
3182    return ActOnCapScopeReturnStmt(ReturnLoc, RetValExp);
3183
3184  QualType FnRetType;
3185  QualType RelatedRetType;
3186  const AttrVec *Attrs = nullptr;
3187  bool isObjCMethod = false;
3188
3189  if (const FunctionDecl *FD = getCurFunctionDecl()) {
3190    FnRetType = FD->getReturnType();
3191    if (FD->hasAttrs())
3192      Attrs = &FD->getAttrs();
3193    if (FD->isNoReturn())
3194      Diag(ReturnLoc, diag::warn_noreturn_function_has_return_expr)
3195        << FD->getDeclName();
3196  } else if (ObjCMethodDecl *MD = getCurMethodDecl()) {
3197    FnRetType = MD->getReturnType();
3198    isObjCMethod = true;
3199    if (MD->hasAttrs())
3200      Attrs = &MD->getAttrs();
3201    if (MD->hasRelatedResultType() && MD->getClassInterface()) {
3202      // In the implementation of a method with a related return type, the
3203      // type used to type-check the validity of return statements within the
3204      // method body is a pointer to the type of the class being implemented.
3205      RelatedRetType = Context.getObjCInterfaceType(MD->getClassInterface());
3206      RelatedRetType = Context.getObjCObjectPointerType(RelatedRetType);
3207    }
3208  } else // If we don't have a function/method context, bail.
3209    return StmtError();
3210
3211  // C++1z: discarded return statements are not considered when deducing a
3212  // return type.
3213  if (ExprEvalContexts.back().Context == DiscardedStatement &&
3214      FnRetType->getContainedAutoType()) {
3215    if (RetValExp) {
3216      ExprResult ER = ActOnFinishFullExpr(RetValExp, ReturnLoc);
3217      if (ER.isInvalid())
3218        return StmtError();
3219      RetValExp = ER.get();
3220    }
3221    return new (Context) ReturnStmt(ReturnLoc, RetValExp, nullptr);
3222  }
3223
3224  // FIXME: Add a flag to the ScopeInfo to indicate whether we're performing
3225  // deduction.
3226  if (getLangOpts().CPlusPlus14) {
3227    if (AutoType *AT = FnRetType->getContainedAutoType()) {
3228      FunctionDecl *FD = cast<FunctionDecl>(CurContext);
3229      if (DeduceFunctionTypeFromReturnExpr(FD, ReturnLoc, RetValExp, AT)) {
3230        FD->setInvalidDecl();
3231        return StmtError();
3232      } else {
3233        FnRetType = FD->getReturnType();
3234      }
3235    }
3236  }
3237
3238  bool HasDependentReturnType = FnRetType->isDependentType();
3239
3240  ReturnStmt *Result = nullptr;
3241  if (FnRetType->isVoidType()) {
3242    if (RetValExp) {
3243      if (isa<InitListExpr>(RetValExp)) {
3244        // We simply never allow init lists as the return value of void
3245        // functions. This is compatible because this was never allowed before,
3246        // so there's no legacy code to deal with.
3247        NamedDecl *CurDecl = getCurFunctionOrMethodDecl();
3248        int FunctionKind = 0;
3249        if (isa<ObjCMethodDecl>(CurDecl))
3250          FunctionKind = 1;
3251        else if (isa<CXXConstructorDecl>(CurDecl))
3252          FunctionKind = 2;
3253        else if (isa<CXXDestructorDecl>(CurDecl))
3254          FunctionKind = 3;
3255
3256        Diag(ReturnLoc, diag::err_return_init_list)
3257          << CurDecl->getDeclName() << FunctionKind
3258          << RetValExp->getSourceRange();
3259
3260        // Drop the expression.
3261        RetValExp = nullptr;
3262      } else if (!RetValExp->isTypeDependent()) {
3263        // C99 6.8.6.4p1 (ext_ since GCC warns)
3264        unsigned D = diag::ext_return_has_expr;
3265        if (RetValExp->getType()->isVoidType()) {
3266          NamedDecl *CurDecl = getCurFunctionOrMethodDecl();
3267          if (isa<CXXConstructorDecl>(CurDecl) ||
3268              isa<CXXDestructorDecl>(CurDecl))
3269            D = diag::err_ctor_dtor_returns_void;
3270          else
3271            D = diag::ext_return_has_void_expr;
3272        }
3273        else {
3274          ExprResult Result = RetValExp;
3275          Result = IgnoredValueConversions(Result.get());
3276          if (Result.isInvalid())
3277            return StmtError();
3278          RetValExp = Result.get();
3279          RetValExp = ImpCastExprToType(RetValExp,
3280                                        Context.VoidTy, CK_ToVoid).get();
3281        }
3282        // return of void in constructor/destructor is illegal in C++.
3283        if (D == diag::err_ctor_dtor_returns_void) {
3284          NamedDecl *CurDecl = getCurFunctionOrMethodDecl();
3285          Diag(ReturnLoc, D)
3286            << CurDecl->getDeclName() << isa<CXXDestructorDecl>(CurDecl)
3287            << RetValExp->getSourceRange();
3288        }
3289        // return (some void expression); is legal in C++.
3290        else if (D != diag::ext_return_has_void_expr ||
3291                 !getLangOpts().CPlusPlus) {
3292          NamedDecl *CurDecl = getCurFunctionOrMethodDecl();
3293
3294          int FunctionKind = 0;
3295          if (isa<ObjCMethodDecl>(CurDecl))
3296            FunctionKind = 1;
3297          else if (isa<CXXConstructorDecl>(CurDecl))
3298            FunctionKind = 2;
3299          else if (isa<CXXDestructorDecl>(CurDecl))
3300            FunctionKind = 3;
3301
3302          Diag(ReturnLoc, D)
3303            << CurDecl->getDeclName() << FunctionKind
3304            << RetValExp->getSourceRange();
3305        }
3306      }
3307
3308      if (RetValExp) {
3309        ExprResult ER = ActOnFinishFullExpr(RetValExp, ReturnLoc);
3310        if (ER.isInvalid())
3311          return StmtError();
3312        RetValExp = ER.get();
3313      }
3314    }
3315
3316    Result = new (Context) ReturnStmt(ReturnLoc, RetValExp, nullptr);
3317  } else if (!RetValExp && !HasDependentReturnType) {
3318    FunctionDecl *FD = getCurFunctionDecl();
3319
3320    unsigned DiagID;
3321    if (getLangOpts().CPlusPlus11 && FD && FD->isConstexpr()) {
3322      // C++11 [stmt.return]p2
3323      DiagID = diag::err_constexpr_return_missing_expr;
3324      FD->setInvalidDecl();
3325    } else if (getLangOpts().C99) {
3326      // C99 6.8.6.4p1 (ext_ since GCC warns)
3327      DiagID = diag::ext_return_missing_expr;
3328    } else {
3329      // C90 6.6.6.4p4
3330      DiagID = diag::warn_return_missing_expr;
3331    }
3332
3333    if (FD)
3334      Diag(ReturnLoc, DiagID) << FD->getIdentifier() << 0/*fn*/;
3335    else
3336      Diag(ReturnLoc, DiagID) << getCurMethodDecl()->getDeclName() << 1/*meth*/;
3337
3338    Result = new (Context) ReturnStmt(ReturnLoc);
3339  } else {
3340    assert(RetValExp || HasDependentReturnType);
3341    const VarDecl *NRVOCandidate = nullptr;
3342
3343    QualType RetType = RelatedRetType.isNull() ? FnRetType : RelatedRetType;
3344
3345    // C99 6.8.6.4p3(136): The return statement is not an assignment. The
3346    // overlap restriction of subclause 6.5.16.1 does not apply to the case of
3347    // function return.
3348
3349    // In C++ the return statement is handled via a copy initialization,
3350    // the C version of which boils down to CheckSingleAssignmentConstraints.
3351    if (RetValExp)
3352      NRVOCandidate = getCopyElisionCandidate(FnRetType, RetValExp, false);
3353    if (!HasDependentReturnType && !RetValExp->isTypeDependent()) {
3354      // we have a non-void function with an expression, continue checking
3355      InitializedEntity Entity = InitializedEntity::InitializeResult(ReturnLoc,
3356                                                                     RetType,
3357                                                      NRVOCandidate != nullptr);
3358      ExprResult Res = PerformMoveOrCopyInitialization(Entity, NRVOCandidate,
3359                                                       RetType, RetValExp);
3360      if (Res.isInvalid()) {
3361        // FIXME: Clean up temporaries here anyway?
3362        return StmtError();
3363      }
3364      RetValExp = Res.getAs<Expr>();
3365
3366      // If we have a related result type, we need to implicitly
3367      // convert back to the formal result type.  We can't pretend to
3368      // initialize the result again --- we might end double-retaining
3369      // --- so instead we initialize a notional temporary.
3370      if (!RelatedRetType.isNull()) {
3371        Entity = InitializedEntity::InitializeRelatedResult(getCurMethodDecl(),
3372                                                            FnRetType);
3373        Res = PerformCopyInitialization(Entity, ReturnLoc, RetValExp);
3374        if (Res.isInvalid()) {
3375          // FIXME: Clean up temporaries here anyway?
3376          return StmtError();
3377        }
3378        RetValExp = Res.getAs<Expr>();
3379      }
3380
3381      CheckReturnValExpr(RetValExp, FnRetType, ReturnLoc, isObjCMethod, Attrs,
3382                         getCurFunctionDecl());
3383    }
3384
3385    if (RetValExp) {
3386      ExprResult ER = ActOnFinishFullExpr(RetValExp, ReturnLoc);
3387      if (ER.isInvalid())
3388        return StmtError();
3389      RetValExp = ER.get();
3390    }
3391    Result = new (Context) ReturnStmt(ReturnLoc, RetValExp, NRVOCandidate);
3392  }
3393
3394  // If we need to check for the named return value optimization, save the
3395  // return statement in our scope for later processing.
3396  if (Result->getNRVOCandidate())
3397    FunctionScopes.back()->Returns.push_back(Result);
3398
3399  if (FunctionScopes.back()->FirstReturnLoc.isInvalid())
3400    FunctionScopes.back()->FirstReturnLoc = ReturnLoc;
3401
3402  return Result;
3403}
3404
3405StmtResult
3406Sema::ActOnObjCAtCatchStmt(SourceLocation AtLoc,
3407                           SourceLocation RParen, Decl *Parm,
3408                           Stmt *Body) {
3409  VarDecl *Var = cast_or_null<VarDecl>(Parm);
3410  if (Var && Var->isInvalidDecl())
3411    return StmtError();
3412
3413  return new (Context) ObjCAtCatchStmt(AtLoc, RParen, Var, Body);
3414}
3415
3416StmtResult
3417Sema::ActOnObjCAtFinallyStmt(SourceLocation AtLoc, Stmt *Body) {
3418  return new (Context) ObjCAtFinallyStmt(AtLoc, Body);
3419}
3420
3421StmtResult
3422Sema::ActOnObjCAtTryStmt(SourceLocation AtLoc, Stmt *Try,
3423                         MultiStmtArg CatchStmts, Stmt *Finally) {
3424  if (!getLangOpts().ObjCExceptions)
3425    Diag(AtLoc, diag::err_objc_exceptions_disabled) << "@try";
3426
3427  getCurFunction()->setHasBranchProtectedScope();
3428  unsigned NumCatchStmts = CatchStmts.size();
3429  return ObjCAtTryStmt::Create(Context, AtLoc, Try, CatchStmts.data(),
3430                               NumCatchStmts, Finally);
3431}
3432
3433StmtResult Sema::BuildObjCAtThrowStmt(SourceLocation AtLoc, Expr *Throw) {
3434  if (Throw) {
3435    ExprResult Result = DefaultLvalueConversion(Throw);
3436    if (Result.isInvalid())
3437      return StmtError();
3438
3439    Result = ActOnFinishFullExpr(Result.get());
3440    if (Result.isInvalid())
3441      return StmtError();
3442    Throw = Result.get();
3443
3444    QualType ThrowType = Throw->getType();
3445    // Make sure the expression type is an ObjC pointer or "void *".
3446    if (!ThrowType->isDependentType() &&
3447        !ThrowType->isObjCObjectPointerType()) {
3448      const PointerType *PT = ThrowType->getAs<PointerType>();
3449      if (!PT || !PT->getPointeeType()->isVoidType())
3450        return StmtError(Diag(AtLoc, diag::error_objc_throw_expects_object)
3451                         << Throw->getType() << Throw->getSourceRange());
3452    }
3453  }
3454
3455  return new (Context) ObjCAtThrowStmt(AtLoc, Throw);
3456}
3457
3458StmtResult
3459Sema::ActOnObjCAtThrowStmt(SourceLocation AtLoc, Expr *Throw,
3460                           Scope *CurScope) {
3461  if (!getLangOpts().ObjCExceptions)
3462    Diag(AtLoc, diag::err_objc_exceptions_disabled) << "@throw";
3463
3464  if (!Throw) {
3465    // @throw without an expression designates a rethrow (which must occur
3466    // in the context of an @catch clause).
3467    Scope *AtCatchParent = CurScope;
3468    while (AtCatchParent && !AtCatchParent->isAtCatchScope())
3469      AtCatchParent = AtCatchParent->getParent();
3470    if (!AtCatchParent)
3471      return StmtError(Diag(AtLoc, diag::error_rethrow_used_outside_catch));
3472  }
3473  return BuildObjCAtThrowStmt(AtLoc, Throw);
3474}
3475
3476ExprResult
3477Sema::ActOnObjCAtSynchronizedOperand(SourceLocation atLoc, Expr *operand) {
3478  ExprResult result = DefaultLvalueConversion(operand);
3479  if (result.isInvalid())
3480    return ExprError();
3481  operand = result.get();
3482
3483  // Make sure the expression type is an ObjC pointer or "void *".
3484  QualType type = operand->getType();
3485  if (!type->isDependentType() &&
3486      !type->isObjCObjectPointerType()) {
3487    const PointerType *pointerType = type->getAs<PointerType>();
3488    if (!pointerType || !pointerType->getPointeeType()->isVoidType()) {
3489      if (getLangOpts().CPlusPlus) {
3490        if (RequireCompleteType(atLoc, type,
3491                                diag::err_incomplete_receiver_type))
3492          return Diag(atLoc, diag::error_objc_synchronized_expects_object)
3493                   << type << operand->getSourceRange();
3494
3495        ExprResult result = PerformContextuallyConvertToObjCPointer(operand);
3496        if (!result.isUsable())
3497          return Diag(atLoc, diag::error_objc_synchronized_expects_object)
3498                   << type << operand->getSourceRange();
3499
3500        operand = result.get();
3501      } else {
3502          return Diag(atLoc, diag::error_objc_synchronized_expects_object)
3503                   << type << operand->getSourceRange();
3504      }
3505    }
3506  }
3507
3508  // The operand to @synchronized is a full-expression.
3509  return ActOnFinishFullExpr(operand);
3510}
3511
3512StmtResult
3513Sema::ActOnObjCAtSynchronizedStmt(SourceLocation AtLoc, Expr *SyncExpr,
3514                                  Stmt *SyncBody) {
3515  // We can't jump into or indirect-jump out of a @synchronized block.
3516  getCurFunction()->setHasBranchProtectedScope();
3517  return new (Context) ObjCAtSynchronizedStmt(AtLoc, SyncExpr, SyncBody);
3518}
3519
3520/// ActOnCXXCatchBlock - Takes an exception declaration and a handler block
3521/// and creates a proper catch handler from them.
3522StmtResult
3523Sema::ActOnCXXCatchBlock(SourceLocation CatchLoc, Decl *ExDecl,
3524                         Stmt *HandlerBlock) {
3525  // There's nothing to test that ActOnExceptionDecl didn't already test.
3526  return new (Context)
3527      CXXCatchStmt(CatchLoc, cast_or_null<VarDecl>(ExDecl), HandlerBlock);
3528}
3529
3530StmtResult
3531Sema::ActOnObjCAutoreleasePoolStmt(SourceLocation AtLoc, Stmt *Body) {
3532  getCurFunction()->setHasBranchProtectedScope();
3533  return new (Context) ObjCAutoreleasePoolStmt(AtLoc, Body);
3534}
3535
3536namespace {
3537class CatchHandlerType {
3538  QualType QT;
3539  unsigned IsPointer : 1;
3540
3541  // This is a special constructor to be used only with DenseMapInfo's
3542  // getEmptyKey() and getTombstoneKey() functions.
3543  friend struct llvm::DenseMapInfo<CatchHandlerType>;
3544  enum Unique { ForDenseMap };
3545  CatchHandlerType(QualType QT, Unique) : QT(QT), IsPointer(false) {}
3546
3547public:
3548  /// Used when creating a CatchHandlerType from a handler type; will determine
3549  /// whether the type is a pointer or reference and will strip off the top
3550  /// level pointer and cv-qualifiers.
3551  CatchHandlerType(QualType Q) : QT(Q), IsPointer(false) {
3552    if (QT->isPointerType())
3553      IsPointer = true;
3554
3555    if (IsPointer || QT->isReferenceType())
3556      QT = QT->getPointeeType();
3557    QT = QT.getUnqualifiedType();
3558  }
3559
3560  /// Used when creating a CatchHandlerType from a base class type; pretends the
3561  /// type passed in had the pointer qualifier, does not need to get an
3562  /// unqualified type.
3563  CatchHandlerType(QualType QT, bool IsPointer)
3564      : QT(QT), IsPointer(IsPointer) {}
3565
3566  QualType underlying() const { return QT; }
3567  bool isPointer() const { return IsPointer; }
3568
3569  friend bool operator==(const CatchHandlerType &LHS,
3570                         const CatchHandlerType &RHS) {
3571    // If the pointer qualification does not match, we can return early.
3572    if (LHS.IsPointer != RHS.IsPointer)
3573      return false;
3574    // Otherwise, check the underlying type without cv-qualifiers.
3575    return LHS.QT == RHS.QT;
3576  }
3577};
3578} // namespace
3579
3580namespace llvm {
3581template <> struct DenseMapInfo<CatchHandlerType> {
3582  static CatchHandlerType getEmptyKey() {
3583    return CatchHandlerType(DenseMapInfo<QualType>::getEmptyKey(),
3584                       CatchHandlerType::ForDenseMap);
3585  }
3586
3587  static CatchHandlerType getTombstoneKey() {
3588    return CatchHandlerType(DenseMapInfo<QualType>::getTombstoneKey(),
3589                       CatchHandlerType::ForDenseMap);
3590  }
3591
3592  static unsigned getHashValue(const CatchHandlerType &Base) {
3593    return DenseMapInfo<QualType>::getHashValue(Base.underlying());
3594  }
3595
3596  static bool isEqual(const CatchHandlerType &LHS,
3597                      const CatchHandlerType &RHS) {
3598    return LHS == RHS;
3599  }
3600};
3601}
3602
3603namespace {
3604class CatchTypePublicBases {
3605  ASTContext &Ctx;
3606  const llvm::DenseMap<CatchHandlerType, CXXCatchStmt *> &TypesToCheck;
3607  const bool CheckAgainstPointer;
3608
3609  CXXCatchStmt *FoundHandler;
3610  CanQualType FoundHandlerType;
3611
3612public:
3613  CatchTypePublicBases(
3614      ASTContext &Ctx,
3615      const llvm::DenseMap<CatchHandlerType, CXXCatchStmt *> &T, bool C)
3616      : Ctx(Ctx), TypesToCheck(T), CheckAgainstPointer(C),
3617        FoundHandler(nullptr) {}
3618
3619  CXXCatchStmt *getFoundHandler() const { return FoundHandler; }
3620  CanQualType getFoundHandlerType() const { return FoundHandlerType; }
3621
3622  bool operator()(const CXXBaseSpecifier *S, CXXBasePath &) {
3623    if (S->getAccessSpecifier() == AccessSpecifier::AS_public) {
3624      CatchHandlerType Check(S->getType(), CheckAgainstPointer);
3625      const auto &M = TypesToCheck;
3626      auto I = M.find(Check);
3627      if (I != M.end()) {
3628        FoundHandler = I->second;
3629        FoundHandlerType = Ctx.getCanonicalType(S->getType());
3630        return true;
3631      }
3632    }
3633    return false;
3634  }
3635};
3636}
3637
3638/// ActOnCXXTryBlock - Takes a try compound-statement and a number of
3639/// handlers and creates a try statement from them.
3640StmtResult Sema::ActOnCXXTryBlock(SourceLocation TryLoc, Stmt *TryBlock,
3641                                  ArrayRef<Stmt *> Handlers) {
3642  // Don't report an error if 'try' is used in system headers.
3643  if (!getLangOpts().CXXExceptions &&
3644      !getSourceManager().isInSystemHeader(TryLoc))
3645    Diag(TryLoc, diag::err_exceptions_disabled) << "try";
3646
3647  if (getCurScope() && getCurScope()->isOpenMPSimdDirectiveScope())
3648    Diag(TryLoc, diag::err_omp_simd_region_cannot_use_stmt) << "try";
3649
3650  sema::FunctionScopeInfo *FSI = getCurFunction();
3651
3652  // C++ try is incompatible with SEH __try.
3653  if (!getLangOpts().Borland && FSI->FirstSEHTryLoc.isValid()) {
3654    Diag(TryLoc, diag::err_mixing_cxx_try_seh_try);
3655    Diag(FSI->FirstSEHTryLoc, diag::note_conflicting_try_here) << "'__try'";
3656  }
3657
3658  const unsigned NumHandlers = Handlers.size();
3659  assert(!Handlers.empty() &&
3660         "The parser shouldn't call this if there are no handlers.");
3661
3662  llvm::DenseMap<CatchHandlerType, CXXCatchStmt *> HandledTypes;
3663  for (unsigned i = 0; i < NumHandlers; ++i) {
3664    CXXCatchStmt *H = cast<CXXCatchStmt>(Handlers[i]);
3665
3666    // Diagnose when the handler is a catch-all handler, but it isn't the last
3667    // handler for the try block. [except.handle]p5. Also, skip exception
3668    // declarations that are invalid, since we can't usefully report on them.
3669    if (!H->getExceptionDecl()) {
3670      if (i < NumHandlers - 1)
3671        return StmtError(Diag(H->getLocStart(), diag::err_early_catch_all));
3672      continue;
3673    } else if (H->getExceptionDecl()->isInvalidDecl())
3674      continue;
3675
3676    // Walk the type hierarchy to diagnose when this type has already been
3677    // handled (duplication), or cannot be handled (derivation inversion). We
3678    // ignore top-level cv-qualifiers, per [except.handle]p3
3679    CatchHandlerType HandlerCHT =
3680        (QualType)Context.getCanonicalType(H->getCaughtType());
3681
3682    // We can ignore whether the type is a reference or a pointer; we need the
3683    // underlying declaration type in order to get at the underlying record
3684    // decl, if there is one.
3685    QualType Underlying = HandlerCHT.underlying();
3686    if (auto *RD = Underlying->getAsCXXRecordDecl()) {
3687      if (!RD->hasDefinition())
3688        continue;
3689      // Check that none of the public, unambiguous base classes are in the
3690      // map ([except.handle]p1). Give the base classes the same pointer
3691      // qualification as the original type we are basing off of. This allows
3692      // comparison against the handler type using the same top-level pointer
3693      // as the original type.
3694      CXXBasePaths Paths;
3695      Paths.setOrigin(RD);
3696      CatchTypePublicBases CTPB(Context, HandledTypes, HandlerCHT.isPointer());
3697      if (RD->lookupInBases(CTPB, Paths)) {
3698        const CXXCatchStmt *Problem = CTPB.getFoundHandler();
3699        if (!Paths.isAmbiguous(CTPB.getFoundHandlerType())) {
3700          Diag(H->getExceptionDecl()->getTypeSpecStartLoc(),
3701               diag::warn_exception_caught_by_earlier_handler)
3702              << H->getCaughtType();
3703          Diag(Problem->getExceptionDecl()->getTypeSpecStartLoc(),
3704                diag::note_previous_exception_handler)
3705              << Problem->getCaughtType();
3706        }
3707      }
3708    }
3709
3710    // Add the type the list of ones we have handled; diagnose if we've already
3711    // handled it.
3712    auto R = HandledTypes.insert(std::make_pair(H->getCaughtType(), H));
3713    if (!R.second) {
3714      const CXXCatchStmt *Problem = R.first->second;
3715      Diag(H->getExceptionDecl()->getTypeSpecStartLoc(),
3716           diag::warn_exception_caught_by_earlier_handler)
3717          << H->getCaughtType();
3718      Diag(Problem->getExceptionDecl()->getTypeSpecStartLoc(),
3719           diag::note_previous_exception_handler)
3720          << Problem->getCaughtType();
3721    }
3722  }
3723
3724  FSI->setHasCXXTry(TryLoc);
3725
3726  return CXXTryStmt::Create(Context, TryLoc, TryBlock, Handlers);
3727}
3728
3729StmtResult Sema::ActOnSEHTryBlock(bool IsCXXTry, SourceLocation TryLoc,
3730                                  Stmt *TryBlock, Stmt *Handler) {
3731  assert(TryBlock && Handler);
3732
3733  sema::FunctionScopeInfo *FSI = getCurFunction();
3734
3735  // SEH __try is incompatible with C++ try. Borland appears to support this,
3736  // however.
3737  if (!getLangOpts().Borland) {
3738    if (FSI->FirstCXXTryLoc.isValid()) {
3739      Diag(TryLoc, diag::err_mixing_cxx_try_seh_try);
3740      Diag(FSI->FirstCXXTryLoc, diag::note_conflicting_try_here) << "'try'";
3741    }
3742  }
3743
3744  FSI->setHasSEHTry(TryLoc);
3745
3746  // Reject __try in Obj-C methods, blocks, and captured decls, since we don't
3747  // track if they use SEH.
3748  DeclContext *DC = CurContext;
3749  while (DC && !DC->isFunctionOrMethod())
3750    DC = DC->getParent();
3751  FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(DC);
3752  if (FD)
3753    FD->setUsesSEHTry(true);
3754  else
3755    Diag(TryLoc, diag::err_seh_try_outside_functions);
3756
3757  // Reject __try on unsupported targets.
3758  if (!Context.getTargetInfo().isSEHTrySupported())
3759    Diag(TryLoc, diag::err_seh_try_unsupported);
3760
3761  return SEHTryStmt::Create(Context, IsCXXTry, TryLoc, TryBlock, Handler);
3762}
3763
3764StmtResult
3765Sema::ActOnSEHExceptBlock(SourceLocation Loc,
3766                          Expr *FilterExpr,
3767                          Stmt *Block) {
3768  assert(FilterExpr && Block);
3769
3770  if(!FilterExpr->getType()->isIntegerType()) {
3771    return StmtError(Diag(FilterExpr->getExprLoc(),
3772                     diag::err_filter_expression_integral)
3773                     << FilterExpr->getType());
3774  }
3775
3776  return SEHExceptStmt::Create(Context,Loc,FilterExpr,Block);
3777}
3778
3779void Sema::ActOnStartSEHFinallyBlock() {
3780  CurrentSEHFinally.push_back(CurScope);
3781}
3782
3783void Sema::ActOnAbortSEHFinallyBlock() {
3784  CurrentSEHFinally.pop_back();
3785}
3786
3787StmtResult Sema::ActOnFinishSEHFinallyBlock(SourceLocation Loc, Stmt *Block) {
3788  assert(Block);
3789  CurrentSEHFinally.pop_back();
3790  return SEHFinallyStmt::Create(Context, Loc, Block);
3791}
3792
3793StmtResult
3794Sema::ActOnSEHLeaveStmt(SourceLocation Loc, Scope *CurScope) {
3795  Scope *SEHTryParent = CurScope;
3796  while (SEHTryParent && !SEHTryParent->isSEHTryScope())
3797    SEHTryParent = SEHTryParent->getParent();
3798  if (!SEHTryParent)
3799    return StmtError(Diag(Loc, diag::err_ms___leave_not_in___try));
3800  CheckJumpOutOfSEHFinally(*this, Loc, *SEHTryParent);
3801
3802  return new (Context) SEHLeaveStmt(Loc);
3803}
3804
3805StmtResult Sema::BuildMSDependentExistsStmt(SourceLocation KeywordLoc,
3806                                            bool IsIfExists,
3807                                            NestedNameSpecifierLoc QualifierLoc,
3808                                            DeclarationNameInfo NameInfo,
3809                                            Stmt *Nested)
3810{
3811  return new (Context) MSDependentExistsStmt(KeywordLoc, IsIfExists,
3812                                             QualifierLoc, NameInfo,
3813                                             cast<CompoundStmt>(Nested));
3814}
3815
3816
3817StmtResult Sema::ActOnMSDependentExistsStmt(SourceLocation KeywordLoc,
3818                                            bool IsIfExists,
3819                                            CXXScopeSpec &SS,
3820                                            UnqualifiedId &Name,
3821                                            Stmt *Nested) {
3822  return BuildMSDependentExistsStmt(KeywordLoc, IsIfExists,
3823                                    SS.getWithLocInContext(Context),
3824                                    GetNameFromUnqualifiedId(Name),
3825                                    Nested);
3826}
3827
3828RecordDecl*
3829Sema::CreateCapturedStmtRecordDecl(CapturedDecl *&CD, SourceLocation Loc,
3830                                   unsigned NumParams) {
3831  DeclContext *DC = CurContext;
3832  while (!(DC->isFunctionOrMethod() || DC->isRecord() || DC->isFileContext()))
3833    DC = DC->getParent();
3834
3835  RecordDecl *RD = nullptr;
3836  if (getLangOpts().CPlusPlus)
3837    RD = CXXRecordDecl::Create(Context, TTK_Struct, DC, Loc, Loc,
3838                               /*Id=*/nullptr);
3839  else
3840    RD = RecordDecl::Create(Context, TTK_Struct, DC, Loc, Loc, /*Id=*/nullptr);
3841
3842  RD->setCapturedRecord();
3843  DC->addDecl(RD);
3844  RD->setImplicit();
3845  RD->startDefinition();
3846
3847  assert(NumParams > 0 && "CapturedStmt requires context parameter");
3848  CD = CapturedDecl::Create(Context, CurContext, NumParams);
3849  DC->addDecl(CD);
3850  return RD;
3851}
3852
3853static void buildCapturedStmtCaptureList(
3854    SmallVectorImpl<CapturedStmt::Capture> &Captures,
3855    SmallVectorImpl<Expr *> &CaptureInits,
3856    ArrayRef<CapturingScopeInfo::Capture> Candidates) {
3857
3858  typedef ArrayRef<CapturingScopeInfo::Capture>::const_iterator CaptureIter;
3859  for (CaptureIter Cap = Candidates.begin(); Cap != Candidates.end(); ++Cap) {
3860
3861    if (Cap->isThisCapture()) {
3862      Captures.push_back(CapturedStmt::Capture(Cap->getLocation(),
3863                                               CapturedStmt::VCK_This));
3864      CaptureInits.push_back(Cap->getInitExpr());
3865      continue;
3866    } else if (Cap->isVLATypeCapture()) {
3867      Captures.push_back(
3868          CapturedStmt::Capture(Cap->getLocation(), CapturedStmt::VCK_VLAType));
3869      CaptureInits.push_back(nullptr);
3870      continue;
3871    }
3872
3873    Captures.push_back(CapturedStmt::Capture(Cap->getLocation(),
3874                                             Cap->isReferenceCapture()
3875                                                 ? CapturedStmt::VCK_ByRef
3876                                                 : CapturedStmt::VCK_ByCopy,
3877                                             Cap->getVariable()));
3878    CaptureInits.push_back(Cap->getInitExpr());
3879  }
3880}
3881
3882void Sema::ActOnCapturedRegionStart(SourceLocation Loc, Scope *CurScope,
3883                                    CapturedRegionKind Kind,
3884                                    unsigned NumParams) {
3885  CapturedDecl *CD = nullptr;
3886  RecordDecl *RD = CreateCapturedStmtRecordDecl(CD, Loc, NumParams);
3887
3888  // Build the context parameter
3889  DeclContext *DC = CapturedDecl::castToDeclContext(CD);
3890  IdentifierInfo *ParamName = &Context.Idents.get("__context");
3891  QualType ParamType = Context.getPointerType(Context.getTagDeclType(RD));
3892  ImplicitParamDecl *Param
3893    = ImplicitParamDecl::Create(Context, DC, Loc, ParamName, ParamType);
3894  DC->addDecl(Param);
3895
3896  CD->setContextParam(0, Param);
3897
3898  // Enter the capturing scope for this captured region.
3899  PushCapturedRegionScope(CurScope, CD, RD, Kind);
3900
3901  if (CurScope)
3902    PushDeclContext(CurScope, CD);
3903  else
3904    CurContext = CD;
3905
3906  PushExpressionEvaluationContext(PotentiallyEvaluated);
3907}
3908
3909void Sema::ActOnCapturedRegionStart(SourceLocation Loc, Scope *CurScope,
3910                                    CapturedRegionKind Kind,
3911                                    ArrayRef<CapturedParamNameType> Params) {
3912  CapturedDecl *CD = nullptr;
3913  RecordDecl *RD = CreateCapturedStmtRecordDecl(CD, Loc, Params.size());
3914
3915  // Build the context parameter
3916  DeclContext *DC = CapturedDecl::castToDeclContext(CD);
3917  bool ContextIsFound = false;
3918  unsigned ParamNum = 0;
3919  for (ArrayRef<CapturedParamNameType>::iterator I = Params.begin(),
3920                                                 E = Params.end();
3921       I != E; ++I, ++ParamNum) {
3922    if (I->second.isNull()) {
3923      assert(!ContextIsFound &&
3924             "null type has been found already for '__context' parameter");
3925      IdentifierInfo *ParamName = &Context.Idents.get("__context");
3926      QualType ParamType = Context.getPointerType(Context.getTagDeclType(RD));
3927      ImplicitParamDecl *Param
3928        = ImplicitParamDecl::Create(Context, DC, Loc, ParamName, ParamType);
3929      DC->addDecl(Param);
3930      CD->setContextParam(ParamNum, Param);
3931      ContextIsFound = true;
3932    } else {
3933      IdentifierInfo *ParamName = &Context.Idents.get(I->first);
3934      ImplicitParamDecl *Param
3935        = ImplicitParamDecl::Create(Context, DC, Loc, ParamName, I->second);
3936      DC->addDecl(Param);
3937      CD->setParam(ParamNum, Param);
3938    }
3939  }
3940  assert(ContextIsFound && "no null type for '__context' parameter");
3941  if (!ContextIsFound) {
3942    // Add __context implicitly if it is not specified.
3943    IdentifierInfo *ParamName = &Context.Idents.get("__context");
3944    QualType ParamType = Context.getPointerType(Context.getTagDeclType(RD));
3945    ImplicitParamDecl *Param =
3946        ImplicitParamDecl::Create(Context, DC, Loc, ParamName, ParamType);
3947    DC->addDecl(Param);
3948    CD->setContextParam(ParamNum, Param);
3949  }
3950  // Enter the capturing scope for this captured region.
3951  PushCapturedRegionScope(CurScope, CD, RD, Kind);
3952
3953  if (CurScope)
3954    PushDeclContext(CurScope, CD);
3955  else
3956    CurContext = CD;
3957
3958  PushExpressionEvaluationContext(PotentiallyEvaluated);
3959}
3960
3961void Sema::ActOnCapturedRegionError() {
3962  DiscardCleanupsInEvaluationContext();
3963  PopExpressionEvaluationContext();
3964
3965  CapturedRegionScopeInfo *RSI = getCurCapturedRegion();
3966  RecordDecl *Record = RSI->TheRecordDecl;
3967  Record->setInvalidDecl();
3968
3969  SmallVector<Decl*, 4> Fields(Record->fields());
3970  ActOnFields(/*Scope=*/nullptr, Record->getLocation(), Record, Fields,
3971              SourceLocation(), SourceLocation(), /*AttributeList=*/nullptr);
3972
3973  PopDeclContext();
3974  PopFunctionScopeInfo();
3975}
3976
3977StmtResult Sema::ActOnCapturedRegionEnd(Stmt *S) {
3978  CapturedRegionScopeInfo *RSI = getCurCapturedRegion();
3979
3980  SmallVector<CapturedStmt::Capture, 4> Captures;
3981  SmallVector<Expr *, 4> CaptureInits;
3982  buildCapturedStmtCaptureList(Captures, CaptureInits, RSI->Captures);
3983
3984  CapturedDecl *CD = RSI->TheCapturedDecl;
3985  RecordDecl *RD = RSI->TheRecordDecl;
3986
3987  CapturedStmt *Res = CapturedStmt::Create(
3988      getASTContext(), S, static_cast<CapturedRegionKind>(RSI->CapRegionKind),
3989      Captures, CaptureInits, CD, RD);
3990
3991  CD->setBody(Res->getCapturedStmt());
3992  RD->completeDefinition();
3993
3994  DiscardCleanupsInEvaluationContext();
3995  PopExpressionEvaluationContext();
3996
3997  PopDeclContext();
3998  PopFunctionScopeInfo();
3999
4000  return Res;
4001}
4002