SemaStmt.cpp revision 5354e77e60e82828c7c2361f5c688c2667ab59cc 
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/Sema/Scope.h"
16#include "clang/Sema/ScopeInfo.h"
17#include "clang/Sema/Initialization.h"
18#include "clang/Sema/Lookup.h"
19#include "clang/AST/ASTContext.h"
20#include "clang/AST/CharUnits.h"
21#include "clang/AST/DeclObjC.h"
22#include "clang/AST/EvaluatedExprVisitor.h"
23#include "clang/AST/ExprCXX.h"
24#include "clang/AST/ExprObjC.h"
25#include "clang/AST/StmtObjC.h"
26#include "clang/AST/StmtCXX.h"
27#include "clang/AST/TypeLoc.h"
28#include "clang/Lex/Preprocessor.h"
29#include "clang/Basic/TargetInfo.h"
30#include "llvm/ADT/ArrayRef.h"
31#include "llvm/ADT/STLExtras.h"
32#include "llvm/ADT/SmallPtrSet.h"
33#include "llvm/ADT/SmallString.h"
34#include "llvm/ADT/SmallVector.h"
35using namespace clang;
36using namespace sema;
37
38StmtResult Sema::ActOnExprStmt(FullExprArg expr) {
39  Expr *E = expr.get();
40  if (!E) // FIXME: FullExprArg has no error state?
41    return StmtError();
42
43  // C99 6.8.3p2: The expression in an expression statement is evaluated as a
44  // void expression for its side effects.  Conversion to void allows any
45  // operand, even incomplete types.
46
47  // Same thing in for stmt first clause (when expr) and third clause.
48  return Owned(static_cast<Stmt*>(E));
49}
50
51
52StmtResult Sema::ActOnNullStmt(SourceLocation SemiLoc,
53                               bool HasLeadingEmptyMacro) {
54  return Owned(new (Context) NullStmt(SemiLoc, HasLeadingEmptyMacro));
55}
56
57StmtResult Sema::ActOnDeclStmt(DeclGroupPtrTy dg, SourceLocation StartLoc,
58                               SourceLocation EndLoc) {
59  DeclGroupRef DG = dg.getAsVal<DeclGroupRef>();
60
61  // If we have an invalid decl, just return an error.
62  if (DG.isNull()) return StmtError();
63
64  return Owned(new (Context) DeclStmt(DG, StartLoc, EndLoc));
65}
66
67void Sema::ActOnForEachDeclStmt(DeclGroupPtrTy dg) {
68  DeclGroupRef DG = dg.getAsVal<DeclGroupRef>();
69
70  // If we have an invalid decl, just return.
71  if (DG.isNull() || !DG.isSingleDecl()) return;
72  VarDecl *var = cast<VarDecl>(DG.getSingleDecl());
73
74  // suppress any potential 'unused variable' warning.
75  var->setUsed();
76
77  // foreach variables are never actually initialized in the way that
78  // the parser came up with.
79  var->setInit(0);
80
81  // In ARC, we don't need to retain the iteration variable of a fast
82  // enumeration loop.  Rather than actually trying to catch that
83  // during declaration processing, we remove the consequences here.
84  if (getLangOpts().ObjCAutoRefCount) {
85    QualType type = var->getType();
86
87    // Only do this if we inferred the lifetime.  Inferred lifetime
88    // will show up as a local qualifier because explicit lifetime
89    // should have shown up as an AttributedType instead.
90    if (type.getLocalQualifiers().getObjCLifetime() == Qualifiers::OCL_Strong) {
91      // Add 'const' and mark the variable as pseudo-strong.
92      var->setType(type.withConst());
93      var->setARCPseudoStrong(true);
94    }
95  }
96}
97
98/// \brief Diagnose unused '==' and '!=' as likely typos for '=' or '|='.
99///
100/// Adding a cast to void (or other expression wrappers) will prevent the
101/// warning from firing.
102static bool DiagnoseUnusedComparison(Sema &S, const Expr *E) {
103  SourceLocation Loc;
104  bool IsNotEqual, CanAssign;
105
106  if (const BinaryOperator *Op = dyn_cast<BinaryOperator>(E)) {
107    if (Op->getOpcode() != BO_EQ && Op->getOpcode() != BO_NE)
108      return false;
109
110    Loc = Op->getOperatorLoc();
111    IsNotEqual = Op->getOpcode() == BO_NE;
112    CanAssign = Op->getLHS()->IgnoreParenImpCasts()->isLValue();
113  } else if (const CXXOperatorCallExpr *Op = dyn_cast<CXXOperatorCallExpr>(E)) {
114    if (Op->getOperator() != OO_EqualEqual &&
115        Op->getOperator() != OO_ExclaimEqual)
116      return false;
117
118    Loc = Op->getOperatorLoc();
119    IsNotEqual = Op->getOperator() == OO_ExclaimEqual;
120    CanAssign = Op->getArg(0)->IgnoreParenImpCasts()->isLValue();
121  } else {
122    // Not a typo-prone comparison.
123    return false;
124  }
125
126  // Suppress warnings when the operator, suspicious as it may be, comes from
127  // a macro expansion.
128  if (Loc.isMacroID())
129    return false;
130
131  S.Diag(Loc, diag::warn_unused_comparison)
132    << (unsigned)IsNotEqual << E->getSourceRange();
133
134  // If the LHS is a plausible entity to assign to, provide a fixit hint to
135  // correct common typos.
136  if (CanAssign) {
137    if (IsNotEqual)
138      S.Diag(Loc, diag::note_inequality_comparison_to_or_assign)
139        << FixItHint::CreateReplacement(Loc, "|=");
140    else
141      S.Diag(Loc, diag::note_equality_comparison_to_assign)
142        << FixItHint::CreateReplacement(Loc, "=");
143  }
144
145  return true;
146}
147
148void Sema::DiagnoseUnusedExprResult(const Stmt *S) {
149  if (const LabelStmt *Label = dyn_cast_or_null<LabelStmt>(S))
150    return DiagnoseUnusedExprResult(Label->getSubStmt());
151
152  const Expr *E = dyn_cast_or_null<Expr>(S);
153  if (!E)
154    return;
155
156  const Expr *WarnExpr;
157  SourceLocation Loc;
158  SourceRange R1, R2;
159  if (SourceMgr.isInSystemMacro(E->getExprLoc()) ||
160      !E->isUnusedResultAWarning(WarnExpr, Loc, R1, R2, Context))
161    return;
162
163  // Okay, we have an unused result.  Depending on what the base expression is,
164  // we might want to make a more specific diagnostic.  Check for one of these
165  // cases now.
166  unsigned DiagID = diag::warn_unused_expr;
167  if (const ExprWithCleanups *Temps = dyn_cast<ExprWithCleanups>(E))
168    E = Temps->getSubExpr();
169  if (const CXXBindTemporaryExpr *TempExpr = dyn_cast<CXXBindTemporaryExpr>(E))
170    E = TempExpr->getSubExpr();
171
172  if (DiagnoseUnusedComparison(*this, E))
173    return;
174
175  E = WarnExpr;
176  if (const CallExpr *CE = dyn_cast<CallExpr>(E)) {
177    if (E->getType()->isVoidType())
178      return;
179
180    // If the callee has attribute pure, const, or warn_unused_result, warn with
181    // a more specific message to make it clear what is happening.
182    if (const Decl *FD = CE->getCalleeDecl()) {
183      if (FD->getAttr<WarnUnusedResultAttr>()) {
184        Diag(Loc, diag::warn_unused_result) << R1 << R2;
185        return;
186      }
187      if (FD->getAttr<PureAttr>()) {
188        Diag(Loc, diag::warn_unused_call) << R1 << R2 << "pure";
189        return;
190      }
191      if (FD->getAttr<ConstAttr>()) {
192        Diag(Loc, diag::warn_unused_call) << R1 << R2 << "const";
193        return;
194      }
195    }
196  } else if (const ObjCMessageExpr *ME = dyn_cast<ObjCMessageExpr>(E)) {
197    if (getLangOpts().ObjCAutoRefCount && ME->isDelegateInitCall()) {
198      Diag(Loc, diag::err_arc_unused_init_message) << R1;
199      return;
200    }
201    const ObjCMethodDecl *MD = ME->getMethodDecl();
202    if (MD && MD->getAttr<WarnUnusedResultAttr>()) {
203      Diag(Loc, diag::warn_unused_result) << R1 << R2;
204      return;
205    }
206  } else if (const PseudoObjectExpr *POE = dyn_cast<PseudoObjectExpr>(E)) {
207    const Expr *Source = POE->getSyntacticForm();
208    if (isa<ObjCSubscriptRefExpr>(Source))
209      DiagID = diag::warn_unused_container_subscript_expr;
210    else
211      DiagID = diag::warn_unused_property_expr;
212  } else if (const CXXFunctionalCastExpr *FC
213                                       = dyn_cast<CXXFunctionalCastExpr>(E)) {
214    if (isa<CXXConstructExpr>(FC->getSubExpr()) ||
215        isa<CXXTemporaryObjectExpr>(FC->getSubExpr()))
216      return;
217  }
218  // Diagnose "(void*) blah" as a typo for "(void) blah".
219  else if (const CStyleCastExpr *CE = dyn_cast<CStyleCastExpr>(E)) {
220    TypeSourceInfo *TI = CE->getTypeInfoAsWritten();
221    QualType T = TI->getType();
222
223    // We really do want to use the non-canonical type here.
224    if (T == Context.VoidPtrTy) {
225      PointerTypeLoc TL = cast<PointerTypeLoc>(TI->getTypeLoc());
226
227      Diag(Loc, diag::warn_unused_voidptr)
228        << FixItHint::CreateRemoval(TL.getStarLoc());
229      return;
230    }
231  }
232
233  if (E->isGLValue() && E->getType().isVolatileQualified()) {
234    Diag(Loc, diag::warn_unused_volatile) << R1 << R2;
235    return;
236  }
237
238  DiagRuntimeBehavior(Loc, 0, PDiag(DiagID) << R1 << R2);
239}
240
241void Sema::ActOnStartOfCompoundStmt() {
242  PushCompoundScope();
243}
244
245void Sema::ActOnFinishOfCompoundStmt() {
246  PopCompoundScope();
247}
248
249sema::CompoundScopeInfo &Sema::getCurCompoundScope() const {
250  return getCurFunction()->CompoundScopes.back();
251}
252
253StmtResult
254Sema::ActOnCompoundStmt(SourceLocation L, SourceLocation R,
255                        MultiStmtArg elts, bool isStmtExpr) {
256  unsigned NumElts = elts.size();
257  Stmt **Elts = elts.data();
258  // If we're in C89 mode, check that we don't have any decls after stmts.  If
259  // so, emit an extension diagnostic.
260  if (!getLangOpts().C99 && !getLangOpts().CPlusPlus) {
261    // Note that __extension__ can be around a decl.
262    unsigned i = 0;
263    // Skip over all declarations.
264    for (; i != NumElts && isa<DeclStmt>(Elts[i]); ++i)
265      /*empty*/;
266
267    // We found the end of the list or a statement.  Scan for another declstmt.
268    for (; i != NumElts && !isa<DeclStmt>(Elts[i]); ++i)
269      /*empty*/;
270
271    if (i != NumElts) {
272      Decl *D = *cast<DeclStmt>(Elts[i])->decl_begin();
273      Diag(D->getLocation(), diag::ext_mixed_decls_code);
274    }
275  }
276  // Warn about unused expressions in statements.
277  for (unsigned i = 0; i != NumElts; ++i) {
278    // Ignore statements that are last in a statement expression.
279    if (isStmtExpr && i == NumElts - 1)
280      continue;
281
282    DiagnoseUnusedExprResult(Elts[i]);
283  }
284
285  // Check for suspicious empty body (null statement) in `for' and `while'
286  // statements.  Don't do anything for template instantiations, this just adds
287  // noise.
288  if (NumElts != 0 && !CurrentInstantiationScope &&
289      getCurCompoundScope().HasEmptyLoopBodies) {
290    for (unsigned i = 0; i != NumElts - 1; ++i)
291      DiagnoseEmptyLoopBody(Elts[i], Elts[i + 1]);
292  }
293
294  return Owned(new (Context) CompoundStmt(Context, Elts, NumElts, L, R));
295}
296
297StmtResult
298Sema::ActOnCaseStmt(SourceLocation CaseLoc, Expr *LHSVal,
299                    SourceLocation DotDotDotLoc, Expr *RHSVal,
300                    SourceLocation ColonLoc) {
301  assert((LHSVal != 0) && "missing expression in case statement");
302
303  if (getCurFunction()->SwitchStack.empty()) {
304    Diag(CaseLoc, diag::err_case_not_in_switch);
305    return StmtError();
306  }
307
308  if (!getLangOpts().CPlusPlus0x) {
309    // C99 6.8.4.2p3: The expression shall be an integer constant.
310    // However, GCC allows any evaluatable integer expression.
311    if (!LHSVal->isTypeDependent() && !LHSVal->isValueDependent()) {
312      LHSVal = VerifyIntegerConstantExpression(LHSVal).take();
313      if (!LHSVal)
314        return StmtError();
315    }
316
317    // GCC extension: The expression shall be an integer constant.
318
319    if (RHSVal && !RHSVal->isTypeDependent() && !RHSVal->isValueDependent()) {
320      RHSVal = VerifyIntegerConstantExpression(RHSVal).take();
321      // Recover from an error by just forgetting about it.
322    }
323  }
324
325  CaseStmt *CS = new (Context) CaseStmt(LHSVal, RHSVal, CaseLoc, DotDotDotLoc,
326                                        ColonLoc);
327  getCurFunction()->SwitchStack.back()->addSwitchCase(CS);
328  return Owned(CS);
329}
330
331/// ActOnCaseStmtBody - This installs a statement as the body of a case.
332void Sema::ActOnCaseStmtBody(Stmt *caseStmt, Stmt *SubStmt) {
333  DiagnoseUnusedExprResult(SubStmt);
334
335  CaseStmt *CS = static_cast<CaseStmt*>(caseStmt);
336  CS->setSubStmt(SubStmt);
337}
338
339StmtResult
340Sema::ActOnDefaultStmt(SourceLocation DefaultLoc, SourceLocation ColonLoc,
341                       Stmt *SubStmt, Scope *CurScope) {
342  DiagnoseUnusedExprResult(SubStmt);
343
344  if (getCurFunction()->SwitchStack.empty()) {
345    Diag(DefaultLoc, diag::err_default_not_in_switch);
346    return Owned(SubStmt);
347  }
348
349  DefaultStmt *DS = new (Context) DefaultStmt(DefaultLoc, ColonLoc, SubStmt);
350  getCurFunction()->SwitchStack.back()->addSwitchCase(DS);
351  return Owned(DS);
352}
353
354StmtResult
355Sema::ActOnLabelStmt(SourceLocation IdentLoc, LabelDecl *TheDecl,
356                     SourceLocation ColonLoc, Stmt *SubStmt) {
357  // If the label was multiply defined, reject it now.
358  if (TheDecl->getStmt()) {
359    Diag(IdentLoc, diag::err_redefinition_of_label) << TheDecl->getDeclName();
360    Diag(TheDecl->getLocation(), diag::note_previous_definition);
361    return Owned(SubStmt);
362  }
363
364  // Otherwise, things are good.  Fill in the declaration and return it.
365  LabelStmt *LS = new (Context) LabelStmt(IdentLoc, TheDecl, SubStmt);
366  TheDecl->setStmt(LS);
367  if (!TheDecl->isGnuLocal())
368    TheDecl->setLocation(IdentLoc);
369  return Owned(LS);
370}
371
372StmtResult Sema::ActOnAttributedStmt(SourceLocation AttrLoc,
373                                     ArrayRef<const Attr*> Attrs,
374                                     Stmt *SubStmt) {
375  // Fill in the declaration and return it.
376  AttributedStmt *LS = AttributedStmt::Create(Context, AttrLoc, Attrs, SubStmt);
377  return Owned(LS);
378}
379
380StmtResult
381Sema::ActOnIfStmt(SourceLocation IfLoc, FullExprArg CondVal, Decl *CondVar,
382                  Stmt *thenStmt, SourceLocation ElseLoc,
383                  Stmt *elseStmt) {
384  ExprResult CondResult(CondVal.release());
385
386  VarDecl *ConditionVar = 0;
387  if (CondVar) {
388    ConditionVar = cast<VarDecl>(CondVar);
389    CondResult = CheckConditionVariable(ConditionVar, IfLoc, true);
390    if (CondResult.isInvalid())
391      return StmtError();
392  }
393  Expr *ConditionExpr = CondResult.takeAs<Expr>();
394  if (!ConditionExpr)
395    return StmtError();
396
397  DiagnoseUnusedExprResult(thenStmt);
398
399  if (!elseStmt) {
400    DiagnoseEmptyStmtBody(ConditionExpr->getLocEnd(), thenStmt,
401                          diag::warn_empty_if_body);
402  }
403
404  DiagnoseUnusedExprResult(elseStmt);
405
406  return Owned(new (Context) IfStmt(Context, IfLoc, ConditionVar, ConditionExpr,
407                                    thenStmt, ElseLoc, elseStmt));
408}
409
410/// ConvertIntegerToTypeWarnOnOverflow - Convert the specified APInt to have
411/// the specified width and sign.  If an overflow occurs, detect it and emit
412/// the specified diagnostic.
413void Sema::ConvertIntegerToTypeWarnOnOverflow(llvm::APSInt &Val,
414                                              unsigned NewWidth, bool NewSign,
415                                              SourceLocation Loc,
416                                              unsigned DiagID) {
417  // Perform a conversion to the promoted condition type if needed.
418  if (NewWidth > Val.getBitWidth()) {
419    // If this is an extension, just do it.
420    Val = Val.extend(NewWidth);
421    Val.setIsSigned(NewSign);
422
423    // If the input was signed and negative and the output is
424    // unsigned, don't bother to warn: this is implementation-defined
425    // behavior.
426    // FIXME: Introduce a second, default-ignored warning for this case?
427  } else if (NewWidth < Val.getBitWidth()) {
428    // If this is a truncation, check for overflow.
429    llvm::APSInt ConvVal(Val);
430    ConvVal = ConvVal.trunc(NewWidth);
431    ConvVal.setIsSigned(NewSign);
432    ConvVal = ConvVal.extend(Val.getBitWidth());
433    ConvVal.setIsSigned(Val.isSigned());
434    if (ConvVal != Val)
435      Diag(Loc, DiagID) << Val.toString(10) << ConvVal.toString(10);
436
437    // Regardless of whether a diagnostic was emitted, really do the
438    // truncation.
439    Val = Val.trunc(NewWidth);
440    Val.setIsSigned(NewSign);
441  } else if (NewSign != Val.isSigned()) {
442    // Convert the sign to match the sign of the condition.  This can cause
443    // overflow as well: unsigned(INTMIN)
444    // We don't diagnose this overflow, because it is implementation-defined
445    // behavior.
446    // FIXME: Introduce a second, default-ignored warning for this case?
447    llvm::APSInt OldVal(Val);
448    Val.setIsSigned(NewSign);
449  }
450}
451
452namespace {
453  struct CaseCompareFunctor {
454    bool operator()(const std::pair<llvm::APSInt, CaseStmt*> &LHS,
455                    const llvm::APSInt &RHS) {
456      return LHS.first < RHS;
457    }
458    bool operator()(const std::pair<llvm::APSInt, CaseStmt*> &LHS,
459                    const std::pair<llvm::APSInt, CaseStmt*> &RHS) {
460      return LHS.first < RHS.first;
461    }
462    bool operator()(const llvm::APSInt &LHS,
463                    const std::pair<llvm::APSInt, CaseStmt*> &RHS) {
464      return LHS < RHS.first;
465    }
466  };
467}
468
469/// CmpCaseVals - Comparison predicate for sorting case values.
470///
471static bool CmpCaseVals(const std::pair<llvm::APSInt, CaseStmt*>& lhs,
472                        const std::pair<llvm::APSInt, CaseStmt*>& rhs) {
473  if (lhs.first < rhs.first)
474    return true;
475
476  if (lhs.first == rhs.first &&
477      lhs.second->getCaseLoc().getRawEncoding()
478       < rhs.second->getCaseLoc().getRawEncoding())
479    return true;
480  return false;
481}
482
483/// CmpEnumVals - Comparison predicate for sorting enumeration values.
484///
485static bool CmpEnumVals(const std::pair<llvm::APSInt, EnumConstantDecl*>& lhs,
486                        const std::pair<llvm::APSInt, EnumConstantDecl*>& rhs)
487{
488  return lhs.first < rhs.first;
489}
490
491/// EqEnumVals - Comparison preficate for uniqing enumeration values.
492///
493static bool EqEnumVals(const std::pair<llvm::APSInt, EnumConstantDecl*>& lhs,
494                       const std::pair<llvm::APSInt, EnumConstantDecl*>& rhs)
495{
496  return lhs.first == rhs.first;
497}
498
499/// GetTypeBeforeIntegralPromotion - Returns the pre-promotion type of
500/// potentially integral-promoted expression @p expr.
501static QualType GetTypeBeforeIntegralPromotion(Expr *&expr) {
502  if (ExprWithCleanups *cleanups = dyn_cast<ExprWithCleanups>(expr))
503    expr = cleanups->getSubExpr();
504  while (ImplicitCastExpr *impcast = dyn_cast<ImplicitCastExpr>(expr)) {
505    if (impcast->getCastKind() != CK_IntegralCast) break;
506    expr = impcast->getSubExpr();
507  }
508  return expr->getType();
509}
510
511StmtResult
512Sema::ActOnStartOfSwitchStmt(SourceLocation SwitchLoc, Expr *Cond,
513                             Decl *CondVar) {
514  ExprResult CondResult;
515
516  VarDecl *ConditionVar = 0;
517  if (CondVar) {
518    ConditionVar = cast<VarDecl>(CondVar);
519    CondResult = CheckConditionVariable(ConditionVar, SourceLocation(), false);
520    if (CondResult.isInvalid())
521      return StmtError();
522
523    Cond = CondResult.release();
524  }
525
526  if (!Cond)
527    return StmtError();
528
529  class SwitchConvertDiagnoser : public ICEConvertDiagnoser {
530    Expr *Cond;
531
532  public:
533    SwitchConvertDiagnoser(Expr *Cond)
534      : ICEConvertDiagnoser(false, true), Cond(Cond) { }
535
536    virtual DiagnosticBuilder diagnoseNotInt(Sema &S, SourceLocation Loc,
537                                             QualType T) {
538      return S.Diag(Loc, diag::err_typecheck_statement_requires_integer) << T;
539    }
540
541    virtual DiagnosticBuilder diagnoseIncomplete(Sema &S, SourceLocation Loc,
542                                                 QualType T) {
543      return S.Diag(Loc, diag::err_switch_incomplete_class_type)
544               << T << Cond->getSourceRange();
545    }
546
547    virtual DiagnosticBuilder diagnoseExplicitConv(Sema &S, SourceLocation Loc,
548                                                   QualType T,
549                                                   QualType ConvTy) {
550      return S.Diag(Loc, diag::err_switch_explicit_conversion) << T << ConvTy;
551    }
552
553    virtual DiagnosticBuilder noteExplicitConv(Sema &S, CXXConversionDecl *Conv,
554                                               QualType ConvTy) {
555      return S.Diag(Conv->getLocation(), diag::note_switch_conversion)
556        << ConvTy->isEnumeralType() << ConvTy;
557    }
558
559    virtual DiagnosticBuilder diagnoseAmbiguous(Sema &S, SourceLocation Loc,
560                                                QualType T) {
561      return S.Diag(Loc, diag::err_switch_multiple_conversions) << T;
562    }
563
564    virtual DiagnosticBuilder noteAmbiguous(Sema &S, CXXConversionDecl *Conv,
565                                            QualType ConvTy) {
566      return S.Diag(Conv->getLocation(), diag::note_switch_conversion)
567      << ConvTy->isEnumeralType() << ConvTy;
568    }
569
570    virtual DiagnosticBuilder diagnoseConversion(Sema &S, SourceLocation Loc,
571                                                 QualType T,
572                                                 QualType ConvTy) {
573      return DiagnosticBuilder::getEmpty();
574    }
575  } SwitchDiagnoser(Cond);
576
577  CondResult
578    = ConvertToIntegralOrEnumerationType(SwitchLoc, Cond, SwitchDiagnoser,
579                                         /*AllowScopedEnumerations*/ true);
580  if (CondResult.isInvalid()) return StmtError();
581  Cond = CondResult.take();
582
583  // C99 6.8.4.2p5 - Integer promotions are performed on the controlling expr.
584  CondResult = UsualUnaryConversions(Cond);
585  if (CondResult.isInvalid()) return StmtError();
586  Cond = CondResult.take();
587
588  if (!CondVar) {
589    CheckImplicitConversions(Cond, SwitchLoc);
590    CondResult = MaybeCreateExprWithCleanups(Cond);
591    if (CondResult.isInvalid())
592      return StmtError();
593    Cond = CondResult.take();
594  }
595
596  getCurFunction()->setHasBranchIntoScope();
597
598  SwitchStmt *SS = new (Context) SwitchStmt(Context, ConditionVar, Cond);
599  getCurFunction()->SwitchStack.push_back(SS);
600  return Owned(SS);
601}
602
603static void AdjustAPSInt(llvm::APSInt &Val, unsigned BitWidth, bool IsSigned) {
604  if (Val.getBitWidth() < BitWidth)
605    Val = Val.extend(BitWidth);
606  else if (Val.getBitWidth() > BitWidth)
607    Val = Val.trunc(BitWidth);
608  Val.setIsSigned(IsSigned);
609}
610
611StmtResult
612Sema::ActOnFinishSwitchStmt(SourceLocation SwitchLoc, Stmt *Switch,
613                            Stmt *BodyStmt) {
614  SwitchStmt *SS = cast<SwitchStmt>(Switch);
615  assert(SS == getCurFunction()->SwitchStack.back() &&
616         "switch stack missing push/pop!");
617
618  SS->setBody(BodyStmt, SwitchLoc);
619  getCurFunction()->SwitchStack.pop_back();
620
621  Expr *CondExpr = SS->getCond();
622  if (!CondExpr) return StmtError();
623
624  QualType CondType = CondExpr->getType();
625
626  Expr *CondExprBeforePromotion = CondExpr;
627  QualType CondTypeBeforePromotion =
628      GetTypeBeforeIntegralPromotion(CondExprBeforePromotion);
629
630  // C++ 6.4.2.p2:
631  // Integral promotions are performed (on the switch condition).
632  //
633  // A case value unrepresentable by the original switch condition
634  // type (before the promotion) doesn't make sense, even when it can
635  // be represented by the promoted type.  Therefore we need to find
636  // the pre-promotion type of the switch condition.
637  if (!CondExpr->isTypeDependent()) {
638    // We have already converted the expression to an integral or enumeration
639    // type, when we started the switch statement. If we don't have an
640    // appropriate type now, just return an error.
641    if (!CondType->isIntegralOrEnumerationType())
642      return StmtError();
643
644    if (CondExpr->isKnownToHaveBooleanValue()) {
645      // switch(bool_expr) {...} is often a programmer error, e.g.
646      //   switch(n && mask) { ... }  // Doh - should be "n & mask".
647      // One can always use an if statement instead of switch(bool_expr).
648      Diag(SwitchLoc, diag::warn_bool_switch_condition)
649          << CondExpr->getSourceRange();
650    }
651  }
652
653  // Get the bitwidth of the switched-on value before promotions.  We must
654  // convert the integer case values to this width before comparison.
655  bool HasDependentValue
656    = CondExpr->isTypeDependent() || CondExpr->isValueDependent();
657  unsigned CondWidth
658    = HasDependentValue ? 0 : Context.getIntWidth(CondTypeBeforePromotion);
659  bool CondIsSigned
660    = CondTypeBeforePromotion->isSignedIntegerOrEnumerationType();
661
662  // Accumulate all of the case values in a vector so that we can sort them
663  // and detect duplicates.  This vector contains the APInt for the case after
664  // it has been converted to the condition type.
665  typedef SmallVector<std::pair<llvm::APSInt, CaseStmt*>, 64> CaseValsTy;
666  CaseValsTy CaseVals;
667
668  // Keep track of any GNU case ranges we see.  The APSInt is the low value.
669  typedef std::vector<std::pair<llvm::APSInt, CaseStmt*> > CaseRangesTy;
670  CaseRangesTy CaseRanges;
671
672  DefaultStmt *TheDefaultStmt = 0;
673
674  bool CaseListIsErroneous = false;
675
676  for (SwitchCase *SC = SS->getSwitchCaseList(); SC && !HasDependentValue;
677       SC = SC->getNextSwitchCase()) {
678
679    if (DefaultStmt *DS = dyn_cast<DefaultStmt>(SC)) {
680      if (TheDefaultStmt) {
681        Diag(DS->getDefaultLoc(), diag::err_multiple_default_labels_defined);
682        Diag(TheDefaultStmt->getDefaultLoc(), diag::note_duplicate_case_prev);
683
684        // FIXME: Remove the default statement from the switch block so that
685        // we'll return a valid AST.  This requires recursing down the AST and
686        // finding it, not something we are set up to do right now.  For now,
687        // just lop the entire switch stmt out of the AST.
688        CaseListIsErroneous = true;
689      }
690      TheDefaultStmt = DS;
691
692    } else {
693      CaseStmt *CS = cast<CaseStmt>(SC);
694
695      Expr *Lo = CS->getLHS();
696
697      if (Lo->isTypeDependent() || Lo->isValueDependent()) {
698        HasDependentValue = true;
699        break;
700      }
701
702      llvm::APSInt LoVal;
703
704      if (getLangOpts().CPlusPlus0x) {
705        // C++11 [stmt.switch]p2: the constant-expression shall be a converted
706        // constant expression of the promoted type of the switch condition.
707        ExprResult ConvLo =
708          CheckConvertedConstantExpression(Lo, CondType, LoVal, CCEK_CaseValue);
709        if (ConvLo.isInvalid()) {
710          CaseListIsErroneous = true;
711          continue;
712        }
713        Lo = ConvLo.take();
714      } else {
715        // We already verified that the expression has a i-c-e value (C99
716        // 6.8.4.2p3) - get that value now.
717        LoVal = Lo->EvaluateKnownConstInt(Context);
718
719        // If the LHS is not the same type as the condition, insert an implicit
720        // cast.
721        Lo = DefaultLvalueConversion(Lo).take();
722        Lo = ImpCastExprToType(Lo, CondType, CK_IntegralCast).take();
723      }
724
725      // Convert the value to the same width/sign as the condition had prior to
726      // integral promotions.
727      //
728      // FIXME: This causes us to reject valid code:
729      //   switch ((char)c) { case 256: case 0: return 0; }
730      // Here we claim there is a duplicated condition value, but there is not.
731      ConvertIntegerToTypeWarnOnOverflow(LoVal, CondWidth, CondIsSigned,
732                                         Lo->getLocStart(),
733                                         diag::warn_case_value_overflow);
734
735      CS->setLHS(Lo);
736
737      // If this is a case range, remember it in CaseRanges, otherwise CaseVals.
738      if (CS->getRHS()) {
739        if (CS->getRHS()->isTypeDependent() ||
740            CS->getRHS()->isValueDependent()) {
741          HasDependentValue = true;
742          break;
743        }
744        CaseRanges.push_back(std::make_pair(LoVal, CS));
745      } else
746        CaseVals.push_back(std::make_pair(LoVal, CS));
747    }
748  }
749
750  if (!HasDependentValue) {
751    // If we don't have a default statement, check whether the
752    // condition is constant.
753    llvm::APSInt ConstantCondValue;
754    bool HasConstantCond = false;
755    if (!HasDependentValue && !TheDefaultStmt) {
756      HasConstantCond
757        = CondExprBeforePromotion->EvaluateAsInt(ConstantCondValue, Context,
758                                                 Expr::SE_AllowSideEffects);
759      assert(!HasConstantCond ||
760             (ConstantCondValue.getBitWidth() == CondWidth &&
761              ConstantCondValue.isSigned() == CondIsSigned));
762    }
763    bool ShouldCheckConstantCond = HasConstantCond;
764
765    // Sort all the scalar case values so we can easily detect duplicates.
766    std::stable_sort(CaseVals.begin(), CaseVals.end(), CmpCaseVals);
767
768    if (!CaseVals.empty()) {
769      for (unsigned i = 0, e = CaseVals.size(); i != e; ++i) {
770        if (ShouldCheckConstantCond &&
771            CaseVals[i].first == ConstantCondValue)
772          ShouldCheckConstantCond = false;
773
774        if (i != 0 && CaseVals[i].first == CaseVals[i-1].first) {
775          // If we have a duplicate, report it.
776          // First, determine if either case value has a name
777          StringRef PrevString, CurrString;
778          Expr *PrevCase = CaseVals[i-1].second->getLHS()->IgnoreParenCasts();
779          Expr *CurrCase = CaseVals[i].second->getLHS()->IgnoreParenCasts();
780          if (DeclRefExpr *DeclRef = dyn_cast<DeclRefExpr>(PrevCase)) {
781            PrevString = DeclRef->getDecl()->getName();
782          }
783          if (DeclRefExpr *DeclRef = dyn_cast<DeclRefExpr>(CurrCase)) {
784            CurrString = DeclRef->getDecl()->getName();
785          }
786          llvm::SmallString<16> CaseValStr;
787          CaseVals[i-1].first.toString(CaseValStr);
788
789          if (PrevString == CurrString)
790            Diag(CaseVals[i].second->getLHS()->getLocStart(),
791                 diag::err_duplicate_case) <<
792                 (PrevString.empty() ? CaseValStr.str() : PrevString);
793          else
794            Diag(CaseVals[i].second->getLHS()->getLocStart(),
795                 diag::err_duplicate_case_differing_expr) <<
796                 (PrevString.empty() ? CaseValStr.str() : PrevString) <<
797                 (CurrString.empty() ? CaseValStr.str() : CurrString) <<
798                 CaseValStr;
799
800          Diag(CaseVals[i-1].second->getLHS()->getLocStart(),
801               diag::note_duplicate_case_prev);
802          // FIXME: We really want to remove the bogus case stmt from the
803          // substmt, but we have no way to do this right now.
804          CaseListIsErroneous = true;
805        }
806      }
807    }
808
809    // Detect duplicate case ranges, which usually don't exist at all in
810    // the first place.
811    if (!CaseRanges.empty()) {
812      // Sort all the case ranges by their low value so we can easily detect
813      // overlaps between ranges.
814      std::stable_sort(CaseRanges.begin(), CaseRanges.end());
815
816      // Scan the ranges, computing the high values and removing empty ranges.
817      std::vector<llvm::APSInt> HiVals;
818      for (unsigned i = 0, e = CaseRanges.size(); i != e; ++i) {
819        llvm::APSInt &LoVal = CaseRanges[i].first;
820        CaseStmt *CR = CaseRanges[i].second;
821        Expr *Hi = CR->getRHS();
822        llvm::APSInt HiVal;
823
824        if (getLangOpts().CPlusPlus0x) {
825          // C++11 [stmt.switch]p2: the constant-expression shall be a converted
826          // constant expression of the promoted type of the switch condition.
827          ExprResult ConvHi =
828            CheckConvertedConstantExpression(Hi, CondType, HiVal,
829                                             CCEK_CaseValue);
830          if (ConvHi.isInvalid()) {
831            CaseListIsErroneous = true;
832            continue;
833          }
834          Hi = ConvHi.take();
835        } else {
836          HiVal = Hi->EvaluateKnownConstInt(Context);
837
838          // If the RHS is not the same type as the condition, insert an
839          // implicit cast.
840          Hi = DefaultLvalueConversion(Hi).take();
841          Hi = ImpCastExprToType(Hi, CondType, CK_IntegralCast).take();
842        }
843
844        // Convert the value to the same width/sign as the condition.
845        ConvertIntegerToTypeWarnOnOverflow(HiVal, CondWidth, CondIsSigned,
846                                           Hi->getLocStart(),
847                                           diag::warn_case_value_overflow);
848
849        CR->setRHS(Hi);
850
851        // If the low value is bigger than the high value, the case is empty.
852        if (LoVal > HiVal) {
853          Diag(CR->getLHS()->getLocStart(), diag::warn_case_empty_range)
854            << SourceRange(CR->getLHS()->getLocStart(),
855                           Hi->getLocEnd());
856          CaseRanges.erase(CaseRanges.begin()+i);
857          --i, --e;
858          continue;
859        }
860
861        if (ShouldCheckConstantCond &&
862            LoVal <= ConstantCondValue &&
863            ConstantCondValue <= HiVal)
864          ShouldCheckConstantCond = false;
865
866        HiVals.push_back(HiVal);
867      }
868
869      // Rescan the ranges, looking for overlap with singleton values and other
870      // ranges.  Since the range list is sorted, we only need to compare case
871      // ranges with their neighbors.
872      for (unsigned i = 0, e = CaseRanges.size(); i != e; ++i) {
873        llvm::APSInt &CRLo = CaseRanges[i].first;
874        llvm::APSInt &CRHi = HiVals[i];
875        CaseStmt *CR = CaseRanges[i].second;
876
877        // Check to see whether the case range overlaps with any
878        // singleton cases.
879        CaseStmt *OverlapStmt = 0;
880        llvm::APSInt OverlapVal(32);
881
882        // Find the smallest value >= the lower bound.  If I is in the
883        // case range, then we have overlap.
884        CaseValsTy::iterator I = std::lower_bound(CaseVals.begin(),
885                                                  CaseVals.end(), CRLo,
886                                                  CaseCompareFunctor());
887        if (I != CaseVals.end() && I->first < CRHi) {
888          OverlapVal  = I->first;   // Found overlap with scalar.
889          OverlapStmt = I->second;
890        }
891
892        // Find the smallest value bigger than the upper bound.
893        I = std::upper_bound(I, CaseVals.end(), CRHi, CaseCompareFunctor());
894        if (I != CaseVals.begin() && (I-1)->first >= CRLo) {
895          OverlapVal  = (I-1)->first;      // Found overlap with scalar.
896          OverlapStmt = (I-1)->second;
897        }
898
899        // Check to see if this case stmt overlaps with the subsequent
900        // case range.
901        if (i && CRLo <= HiVals[i-1]) {
902          OverlapVal  = HiVals[i-1];       // Found overlap with range.
903          OverlapStmt = CaseRanges[i-1].second;
904        }
905
906        if (OverlapStmt) {
907          // If we have a duplicate, report it.
908          Diag(CR->getLHS()->getLocStart(), diag::err_duplicate_case)
909            << OverlapVal.toString(10);
910          Diag(OverlapStmt->getLHS()->getLocStart(),
911               diag::note_duplicate_case_prev);
912          // FIXME: We really want to remove the bogus case stmt from the
913          // substmt, but we have no way to do this right now.
914          CaseListIsErroneous = true;
915        }
916      }
917    }
918
919    // Complain if we have a constant condition and we didn't find a match.
920    if (!CaseListIsErroneous && ShouldCheckConstantCond) {
921      // TODO: it would be nice if we printed enums as enums, chars as
922      // chars, etc.
923      Diag(CondExpr->getExprLoc(), diag::warn_missing_case_for_condition)
924        << ConstantCondValue.toString(10)
925        << CondExpr->getSourceRange();
926    }
927
928    // Check to see if switch is over an Enum and handles all of its
929    // values.  We only issue a warning if there is not 'default:', but
930    // we still do the analysis to preserve this information in the AST
931    // (which can be used by flow-based analyes).
932    //
933    const EnumType *ET = CondTypeBeforePromotion->getAs<EnumType>();
934
935    // If switch has default case, then ignore it.
936    if (!CaseListIsErroneous  && !HasConstantCond && ET) {
937      const EnumDecl *ED = ET->getDecl();
938      typedef SmallVector<std::pair<llvm::APSInt, EnumConstantDecl*>, 64>
939        EnumValsTy;
940      EnumValsTy EnumVals;
941
942      // Gather all enum values, set their type and sort them,
943      // allowing easier comparison with CaseVals.
944      for (EnumDecl::enumerator_iterator EDI = ED->enumerator_begin();
945           EDI != ED->enumerator_end(); ++EDI) {
946        llvm::APSInt Val = EDI->getInitVal();
947        AdjustAPSInt(Val, CondWidth, CondIsSigned);
948        EnumVals.push_back(std::make_pair(Val, *EDI));
949      }
950      std::stable_sort(EnumVals.begin(), EnumVals.end(), CmpEnumVals);
951      EnumValsTy::iterator EIend =
952        std::unique(EnumVals.begin(), EnumVals.end(), EqEnumVals);
953
954      // See which case values aren't in enum.
955      EnumValsTy::const_iterator EI = EnumVals.begin();
956      for (CaseValsTy::const_iterator CI = CaseVals.begin();
957           CI != CaseVals.end(); CI++) {
958        while (EI != EIend && EI->first < CI->first)
959          EI++;
960        if (EI == EIend || EI->first > CI->first)
961          Diag(CI->second->getLHS()->getExprLoc(), diag::warn_not_in_enum)
962            << CondTypeBeforePromotion;
963      }
964      // See which of case ranges aren't in enum
965      EI = EnumVals.begin();
966      for (CaseRangesTy::const_iterator RI = CaseRanges.begin();
967           RI != CaseRanges.end() && EI != EIend; RI++) {
968        while (EI != EIend && EI->first < RI->first)
969          EI++;
970
971        if (EI == EIend || EI->first != RI->first) {
972          Diag(RI->second->getLHS()->getExprLoc(), diag::warn_not_in_enum)
973            << CondTypeBeforePromotion;
974        }
975
976        llvm::APSInt Hi =
977          RI->second->getRHS()->EvaluateKnownConstInt(Context);
978        AdjustAPSInt(Hi, CondWidth, CondIsSigned);
979        while (EI != EIend && EI->first < Hi)
980          EI++;
981        if (EI == EIend || EI->first != Hi)
982          Diag(RI->second->getRHS()->getExprLoc(), diag::warn_not_in_enum)
983            << CondTypeBeforePromotion;
984      }
985
986      // Check which enum vals aren't in switch
987      CaseValsTy::const_iterator CI = CaseVals.begin();
988      CaseRangesTy::const_iterator RI = CaseRanges.begin();
989      bool hasCasesNotInSwitch = false;
990
991      SmallVector<DeclarationName,8> UnhandledNames;
992
993      for (EI = EnumVals.begin(); EI != EIend; EI++){
994        // Drop unneeded case values
995        llvm::APSInt CIVal;
996        while (CI != CaseVals.end() && CI->first < EI->first)
997          CI++;
998
999        if (CI != CaseVals.end() && CI->first == EI->first)
1000          continue;
1001
1002        // Drop unneeded case ranges
1003        for (; RI != CaseRanges.end(); RI++) {
1004          llvm::APSInt Hi =
1005            RI->second->getRHS()->EvaluateKnownConstInt(Context);
1006          AdjustAPSInt(Hi, CondWidth, CondIsSigned);
1007          if (EI->first <= Hi)
1008            break;
1009        }
1010
1011        if (RI == CaseRanges.end() || EI->first < RI->first) {
1012          hasCasesNotInSwitch = true;
1013          UnhandledNames.push_back(EI->second->getDeclName());
1014        }
1015      }
1016
1017      if (TheDefaultStmt && UnhandledNames.empty())
1018        Diag(TheDefaultStmt->getDefaultLoc(), diag::warn_unreachable_default);
1019
1020      // Produce a nice diagnostic if multiple values aren't handled.
1021      switch (UnhandledNames.size()) {
1022      case 0: break;
1023      case 1:
1024        Diag(CondExpr->getExprLoc(), TheDefaultStmt
1025          ? diag::warn_def_missing_case1 : diag::warn_missing_case1)
1026          << UnhandledNames[0];
1027        break;
1028      case 2:
1029        Diag(CondExpr->getExprLoc(), TheDefaultStmt
1030          ? diag::warn_def_missing_case2 : diag::warn_missing_case2)
1031          << UnhandledNames[0] << UnhandledNames[1];
1032        break;
1033      case 3:
1034        Diag(CondExpr->getExprLoc(), TheDefaultStmt
1035          ? diag::warn_def_missing_case3 : diag::warn_missing_case3)
1036          << UnhandledNames[0] << UnhandledNames[1] << UnhandledNames[2];
1037        break;
1038      default:
1039        Diag(CondExpr->getExprLoc(), TheDefaultStmt
1040          ? diag::warn_def_missing_cases : diag::warn_missing_cases)
1041          << (unsigned)UnhandledNames.size()
1042          << UnhandledNames[0] << UnhandledNames[1] << UnhandledNames[2];
1043        break;
1044      }
1045
1046      if (!hasCasesNotInSwitch)
1047        SS->setAllEnumCasesCovered();
1048    }
1049  }
1050
1051  DiagnoseEmptyStmtBody(CondExpr->getLocEnd(), BodyStmt,
1052                        diag::warn_empty_switch_body);
1053
1054  // FIXME: If the case list was broken is some way, we don't have a good system
1055  // to patch it up.  Instead, just return the whole substmt as broken.
1056  if (CaseListIsErroneous)
1057    return StmtError();
1058
1059  return Owned(SS);
1060}
1061
1062void
1063Sema::DiagnoseAssignmentEnum(QualType DstType, QualType SrcType,
1064                             Expr *SrcExpr) {
1065  unsigned DIAG = diag::warn_not_in_enum_assignement;
1066  if (Diags.getDiagnosticLevel(DIAG, SrcExpr->getExprLoc())
1067      == DiagnosticsEngine::Ignored)
1068    return;
1069
1070  if (const EnumType *ET = DstType->getAs<EnumType>())
1071    if (!Context.hasSameType(SrcType, DstType) &&
1072        SrcType->isIntegerType()) {
1073      if (!SrcExpr->isTypeDependent() && !SrcExpr->isValueDependent() &&
1074          SrcExpr->isIntegerConstantExpr(Context)) {
1075        // Get the bitwidth of the enum value before promotions.
1076        unsigned DstWith = Context.getIntWidth(DstType);
1077        bool DstIsSigned = DstType->isSignedIntegerOrEnumerationType();
1078
1079        llvm::APSInt RhsVal = SrcExpr->EvaluateKnownConstInt(Context);
1080        const EnumDecl *ED = ET->getDecl();
1081        typedef SmallVector<std::pair<llvm::APSInt, EnumConstantDecl*>, 64>
1082        EnumValsTy;
1083        EnumValsTy EnumVals;
1084
1085        // Gather all enum values, set their type and sort them,
1086        // allowing easier comparison with rhs constant.
1087        for (EnumDecl::enumerator_iterator EDI = ED->enumerator_begin();
1088             EDI != ED->enumerator_end(); ++EDI) {
1089          llvm::APSInt Val = EDI->getInitVal();
1090          AdjustAPSInt(Val, DstWith, DstIsSigned);
1091          EnumVals.push_back(std::make_pair(Val, *EDI));
1092        }
1093        if (EnumVals.empty())
1094          return;
1095        std::stable_sort(EnumVals.begin(), EnumVals.end(), CmpEnumVals);
1096        EnumValsTy::iterator EIend =
1097        std::unique(EnumVals.begin(), EnumVals.end(), EqEnumVals);
1098
1099        // See which case values aren't in enum.
1100        EnumValsTy::const_iterator EI = EnumVals.begin();
1101        while (EI != EIend && EI->first < RhsVal)
1102          EI++;
1103        if (EI == EIend || EI->first != RhsVal) {
1104          Diag(SrcExpr->getExprLoc(), diag::warn_not_in_enum_assignement)
1105          << DstType;
1106        }
1107      }
1108    }
1109}
1110
1111StmtResult
1112Sema::ActOnWhileStmt(SourceLocation WhileLoc, FullExprArg Cond,
1113                     Decl *CondVar, Stmt *Body) {
1114  ExprResult CondResult(Cond.release());
1115
1116  VarDecl *ConditionVar = 0;
1117  if (CondVar) {
1118    ConditionVar = cast<VarDecl>(CondVar);
1119    CondResult = CheckConditionVariable(ConditionVar, WhileLoc, true);
1120    if (CondResult.isInvalid())
1121      return StmtError();
1122  }
1123  Expr *ConditionExpr = CondResult.take();
1124  if (!ConditionExpr)
1125    return StmtError();
1126
1127  DiagnoseUnusedExprResult(Body);
1128
1129  if (isa<NullStmt>(Body))
1130    getCurCompoundScope().setHasEmptyLoopBodies();
1131
1132  return Owned(new (Context) WhileStmt(Context, ConditionVar, ConditionExpr,
1133                                       Body, WhileLoc));
1134}
1135
1136StmtResult
1137Sema::ActOnDoStmt(SourceLocation DoLoc, Stmt *Body,
1138                  SourceLocation WhileLoc, SourceLocation CondLParen,
1139                  Expr *Cond, SourceLocation CondRParen) {
1140  assert(Cond && "ActOnDoStmt(): missing expression");
1141
1142  ExprResult CondResult = CheckBooleanCondition(Cond, DoLoc);
1143  if (CondResult.isInvalid() || CondResult.isInvalid())
1144    return StmtError();
1145  Cond = CondResult.take();
1146
1147  CheckImplicitConversions(Cond, DoLoc);
1148  CondResult = MaybeCreateExprWithCleanups(Cond);
1149  if (CondResult.isInvalid())
1150    return StmtError();
1151  Cond = CondResult.take();
1152
1153  DiagnoseUnusedExprResult(Body);
1154
1155  return Owned(new (Context) DoStmt(Body, Cond, DoLoc, WhileLoc, CondRParen));
1156}
1157
1158namespace {
1159  // This visitor will traverse a conditional statement and store all
1160  // the evaluated decls into a vector.  Simple is set to true if none
1161  // of the excluded constructs are used.
1162  class DeclExtractor : public EvaluatedExprVisitor<DeclExtractor> {
1163    llvm::SmallPtrSet<VarDecl*, 8> &Decls;
1164    llvm::SmallVector<SourceRange, 10> &Ranges;
1165    bool Simple;
1166public:
1167  typedef EvaluatedExprVisitor<DeclExtractor> Inherited;
1168
1169  DeclExtractor(Sema &S, llvm::SmallPtrSet<VarDecl*, 8> &Decls,
1170                llvm::SmallVector<SourceRange, 10> &Ranges) :
1171      Inherited(S.Context),
1172      Decls(Decls),
1173      Ranges(Ranges),
1174      Simple(true) {}
1175
1176  bool isSimple() { return Simple; }
1177
1178  // Replaces the method in EvaluatedExprVisitor.
1179  void VisitMemberExpr(MemberExpr* E) {
1180    Simple = false;
1181  }
1182
1183  // Any Stmt not whitelisted will cause the condition to be marked complex.
1184  void VisitStmt(Stmt *S) {
1185    Simple = false;
1186  }
1187
1188  void VisitBinaryOperator(BinaryOperator *E) {
1189    Visit(E->getLHS());
1190    Visit(E->getRHS());
1191  }
1192
1193  void VisitCastExpr(CastExpr *E) {
1194    Visit(E->getSubExpr());
1195  }
1196
1197  void VisitUnaryOperator(UnaryOperator *E) {
1198    // Skip checking conditionals with derefernces.
1199    if (E->getOpcode() == UO_Deref)
1200      Simple = false;
1201    else
1202      Visit(E->getSubExpr());
1203  }
1204
1205  void VisitConditionalOperator(ConditionalOperator *E) {
1206    Visit(E->getCond());
1207    Visit(E->getTrueExpr());
1208    Visit(E->getFalseExpr());
1209  }
1210
1211  void VisitParenExpr(ParenExpr *E) {
1212    Visit(E->getSubExpr());
1213  }
1214
1215  void VisitBinaryConditionalOperator(BinaryConditionalOperator *E) {
1216    Visit(E->getOpaqueValue()->getSourceExpr());
1217    Visit(E->getFalseExpr());
1218  }
1219
1220  void VisitIntegerLiteral(IntegerLiteral *E) { }
1221  void VisitFloatingLiteral(FloatingLiteral *E) { }
1222  void VisitCXXBoolLiteralExpr(CXXBoolLiteralExpr *E) { }
1223  void VisitCharacterLiteral(CharacterLiteral *E) { }
1224  void VisitGNUNullExpr(GNUNullExpr *E) { }
1225  void VisitImaginaryLiteral(ImaginaryLiteral *E) { }
1226
1227  void VisitDeclRefExpr(DeclRefExpr *E) {
1228    VarDecl *VD = dyn_cast<VarDecl>(E->getDecl());
1229    if (!VD) return;
1230
1231    Ranges.push_back(E->getSourceRange());
1232
1233    Decls.insert(VD);
1234  }
1235
1236  }; // end class DeclExtractor
1237
1238  // DeclMatcher checks to see if the decls are used in a non-evauluated
1239  // context.
1240  class DeclMatcher : public EvaluatedExprVisitor<DeclMatcher> {
1241    llvm::SmallPtrSet<VarDecl*, 8> &Decls;
1242    bool FoundDecl;
1243
1244public:
1245  typedef EvaluatedExprVisitor<DeclMatcher> Inherited;
1246
1247  DeclMatcher(Sema &S, llvm::SmallPtrSet<VarDecl*, 8> &Decls, Stmt *Statement) :
1248      Inherited(S.Context), Decls(Decls), FoundDecl(false) {
1249    if (!Statement) return;
1250
1251    Visit(Statement);
1252  }
1253
1254  void VisitReturnStmt(ReturnStmt *S) {
1255    FoundDecl = true;
1256  }
1257
1258  void VisitBreakStmt(BreakStmt *S) {
1259    FoundDecl = true;
1260  }
1261
1262  void VisitGotoStmt(GotoStmt *S) {
1263    FoundDecl = true;
1264  }
1265
1266  void VisitCastExpr(CastExpr *E) {
1267    if (E->getCastKind() == CK_LValueToRValue)
1268      CheckLValueToRValueCast(E->getSubExpr());
1269    else
1270      Visit(E->getSubExpr());
1271  }
1272
1273  void CheckLValueToRValueCast(Expr *E) {
1274    E = E->IgnoreParenImpCasts();
1275
1276    if (isa<DeclRefExpr>(E)) {
1277      return;
1278    }
1279
1280    if (ConditionalOperator *CO = dyn_cast<ConditionalOperator>(E)) {
1281      Visit(CO->getCond());
1282      CheckLValueToRValueCast(CO->getTrueExpr());
1283      CheckLValueToRValueCast(CO->getFalseExpr());
1284      return;
1285    }
1286
1287    if (BinaryConditionalOperator *BCO =
1288            dyn_cast<BinaryConditionalOperator>(E)) {
1289      CheckLValueToRValueCast(BCO->getOpaqueValue()->getSourceExpr());
1290      CheckLValueToRValueCast(BCO->getFalseExpr());
1291      return;
1292    }
1293
1294    Visit(E);
1295  }
1296
1297  void VisitDeclRefExpr(DeclRefExpr *E) {
1298    if (VarDecl *VD = dyn_cast<VarDecl>(E->getDecl()))
1299      if (Decls.count(VD))
1300        FoundDecl = true;
1301  }
1302
1303  bool FoundDeclInUse() { return FoundDecl; }
1304
1305  };  // end class DeclMatcher
1306
1307  void CheckForLoopConditionalStatement(Sema &S, Expr *Second,
1308                                        Expr *Third, Stmt *Body) {
1309    // Condition is empty
1310    if (!Second) return;
1311
1312    if (S.Diags.getDiagnosticLevel(diag::warn_variables_not_in_loop_body,
1313                                   Second->getLocStart())
1314        == DiagnosticsEngine::Ignored)
1315      return;
1316
1317    PartialDiagnostic PDiag = S.PDiag(diag::warn_variables_not_in_loop_body);
1318    llvm::SmallPtrSet<VarDecl*, 8> Decls;
1319    llvm::SmallVector<SourceRange, 10> Ranges;
1320    DeclExtractor DE(S, Decls, Ranges);
1321    DE.Visit(Second);
1322
1323    // Don't analyze complex conditionals.
1324    if (!DE.isSimple()) return;
1325
1326    // No decls found.
1327    if (Decls.size() == 0) return;
1328
1329    // Don't warn on volatile, static, or global variables.
1330    for (llvm::SmallPtrSet<VarDecl*, 8>::iterator I = Decls.begin(),
1331                                                  E = Decls.end();
1332         I != E; ++I)
1333      if ((*I)->getType().isVolatileQualified() ||
1334          (*I)->hasGlobalStorage()) return;
1335
1336    if (DeclMatcher(S, Decls, Second).FoundDeclInUse() ||
1337        DeclMatcher(S, Decls, Third).FoundDeclInUse() ||
1338        DeclMatcher(S, Decls, Body).FoundDeclInUse())
1339      return;
1340
1341    // Load decl names into diagnostic.
1342    if (Decls.size() > 4)
1343      PDiag << 0;
1344    else {
1345      PDiag << Decls.size();
1346      for (llvm::SmallPtrSet<VarDecl*, 8>::iterator I = Decls.begin(),
1347                                                    E = Decls.end();
1348           I != E; ++I)
1349        PDiag << (*I)->getDeclName();
1350    }
1351
1352    // Load SourceRanges into diagnostic if there is room.
1353    // Otherwise, load the SourceRange of the conditional expression.
1354    if (Ranges.size() <= PartialDiagnostic::MaxArguments)
1355      for (llvm::SmallVector<SourceRange, 10>::iterator I = Ranges.begin(),
1356                                                        E = Ranges.end();
1357           I != E; ++I)
1358        PDiag << *I;
1359    else
1360      PDiag << Second->getSourceRange();
1361
1362    S.Diag(Ranges.begin()->getBegin(), PDiag);
1363  }
1364
1365} // end namespace
1366
1367StmtResult
1368Sema::ActOnForStmt(SourceLocation ForLoc, SourceLocation LParenLoc,
1369                   Stmt *First, FullExprArg second, Decl *secondVar,
1370                   FullExprArg third,
1371                   SourceLocation RParenLoc, Stmt *Body) {
1372  if (!getLangOpts().CPlusPlus) {
1373    if (DeclStmt *DS = dyn_cast_or_null<DeclStmt>(First)) {
1374      // C99 6.8.5p3: The declaration part of a 'for' statement shall only
1375      // declare identifiers for objects having storage class 'auto' or
1376      // 'register'.
1377      for (DeclStmt::decl_iterator DI=DS->decl_begin(), DE=DS->decl_end();
1378           DI!=DE; ++DI) {
1379        VarDecl *VD = dyn_cast<VarDecl>(*DI);
1380        if (VD && VD->isLocalVarDecl() && !VD->hasLocalStorage())
1381          VD = 0;
1382        if (VD == 0)
1383          Diag((*DI)->getLocation(), diag::err_non_variable_decl_in_for);
1384        // FIXME: mark decl erroneous!
1385      }
1386    }
1387  }
1388
1389  CheckForLoopConditionalStatement(*this, second.get(), third.get(), Body);
1390
1391  ExprResult SecondResult(second.release());
1392  VarDecl *ConditionVar = 0;
1393  if (secondVar) {
1394    ConditionVar = cast<VarDecl>(secondVar);
1395    SecondResult = CheckConditionVariable(ConditionVar, ForLoc, true);
1396    if (SecondResult.isInvalid())
1397      return StmtError();
1398  }
1399
1400  Expr *Third  = third.release().takeAs<Expr>();
1401
1402  DiagnoseUnusedExprResult(First);
1403  DiagnoseUnusedExprResult(Third);
1404  DiagnoseUnusedExprResult(Body);
1405
1406  if (isa<NullStmt>(Body))
1407    getCurCompoundScope().setHasEmptyLoopBodies();
1408
1409  return Owned(new (Context) ForStmt(Context, First,
1410                                     SecondResult.take(), ConditionVar,
1411                                     Third, Body, ForLoc, LParenLoc,
1412                                     RParenLoc));
1413}
1414
1415/// In an Objective C collection iteration statement:
1416///   for (x in y)
1417/// x can be an arbitrary l-value expression.  Bind it up as a
1418/// full-expression.
1419StmtResult Sema::ActOnForEachLValueExpr(Expr *E) {
1420  // Reduce placeholder expressions here.  Note that this rejects the
1421  // use of pseudo-object l-values in this position.
1422  ExprResult result = CheckPlaceholderExpr(E);
1423  if (result.isInvalid()) return StmtError();
1424  E = result.take();
1425
1426  CheckImplicitConversions(E);
1427
1428  result = MaybeCreateExprWithCleanups(E);
1429  if (result.isInvalid()) return StmtError();
1430
1431  return Owned(static_cast<Stmt*>(result.take()));
1432}
1433
1434ExprResult
1435Sema::CheckObjCForCollectionOperand(SourceLocation forLoc, Expr *collection) {
1436  if (!collection)
1437    return ExprError();
1438
1439  // Bail out early if we've got a type-dependent expression.
1440  if (collection->isTypeDependent()) return Owned(collection);
1441
1442  // Perform normal l-value conversion.
1443  ExprResult result = DefaultFunctionArrayLvalueConversion(collection);
1444  if (result.isInvalid())
1445    return ExprError();
1446  collection = result.take();
1447
1448  // The operand needs to have object-pointer type.
1449  // TODO: should we do a contextual conversion?
1450  const ObjCObjectPointerType *pointerType =
1451    collection->getType()->getAs<ObjCObjectPointerType>();
1452  if (!pointerType)
1453    return Diag(forLoc, diag::err_collection_expr_type)
1454             << collection->getType() << collection->getSourceRange();
1455
1456  // Check that the operand provides
1457  //   - countByEnumeratingWithState:objects:count:
1458  const ObjCObjectType *objectType = pointerType->getObjectType();
1459  ObjCInterfaceDecl *iface = objectType->getInterface();
1460
1461  // If we have a forward-declared type, we can't do this check.
1462  // Under ARC, it is an error not to have a forward-declared class.
1463  if (iface &&
1464      RequireCompleteType(forLoc, QualType(objectType, 0),
1465                          getLangOpts().ObjCAutoRefCount
1466                            ? diag::err_arc_collection_forward
1467                            : 0,
1468                          collection)) {
1469    // Otherwise, if we have any useful type information, check that
1470    // the type declares the appropriate method.
1471  } else if (iface || !objectType->qual_empty()) {
1472    IdentifierInfo *selectorIdents[] = {
1473      &Context.Idents.get("countByEnumeratingWithState"),
1474      &Context.Idents.get("objects"),
1475      &Context.Idents.get("count")
1476    };
1477    Selector selector = Context.Selectors.getSelector(3, &selectorIdents[0]);
1478
1479    ObjCMethodDecl *method = 0;
1480
1481    // If there's an interface, look in both the public and private APIs.
1482    if (iface) {
1483      method = iface->lookupInstanceMethod(selector);
1484      if (!method) method = iface->lookupPrivateMethod(selector);
1485    }
1486
1487    // Also check protocol qualifiers.
1488    if (!method)
1489      method = LookupMethodInQualifiedType(selector, pointerType,
1490                                           /*instance*/ true);
1491
1492    // If we didn't find it anywhere, give up.
1493    if (!method) {
1494      Diag(forLoc, diag::warn_collection_expr_type)
1495        << collection->getType() << selector << collection->getSourceRange();
1496    }
1497
1498    // TODO: check for an incompatible signature?
1499  }
1500
1501  // Wrap up any cleanups in the expression.
1502  return Owned(MaybeCreateExprWithCleanups(collection));
1503}
1504
1505StmtResult
1506Sema::ActOnObjCForCollectionStmt(SourceLocation ForLoc,
1507                                 Stmt *First, Expr *collection,
1508                                 SourceLocation RParenLoc) {
1509
1510  ExprResult CollectionExprResult =
1511    CheckObjCForCollectionOperand(ForLoc, collection);
1512
1513  if (First) {
1514    QualType FirstType;
1515    if (DeclStmt *DS = dyn_cast<DeclStmt>(First)) {
1516      if (!DS->isSingleDecl())
1517        return StmtError(Diag((*DS->decl_begin())->getLocation(),
1518                         diag::err_toomany_element_decls));
1519
1520      VarDecl *D = cast<VarDecl>(DS->getSingleDecl());
1521      FirstType = D->getType();
1522      // C99 6.8.5p3: The declaration part of a 'for' statement shall only
1523      // declare identifiers for objects having storage class 'auto' or
1524      // 'register'.
1525      if (!D->hasLocalStorage())
1526        return StmtError(Diag(D->getLocation(),
1527                              diag::err_non_variable_decl_in_for));
1528    } else {
1529      Expr *FirstE = cast<Expr>(First);
1530      if (!FirstE->isTypeDependent() && !FirstE->isLValue())
1531        return StmtError(Diag(First->getLocStart(),
1532                   diag::err_selector_element_not_lvalue)
1533          << First->getSourceRange());
1534
1535      FirstType = static_cast<Expr*>(First)->getType();
1536    }
1537    if (!FirstType->isDependentType() &&
1538        !FirstType->isObjCObjectPointerType() &&
1539        !FirstType->isBlockPointerType())
1540        return StmtError(Diag(ForLoc, diag::err_selector_element_type)
1541                           << FirstType << First->getSourceRange());
1542  }
1543
1544  if (CollectionExprResult.isInvalid())
1545    return StmtError();
1546
1547  return Owned(new (Context) ObjCForCollectionStmt(First,
1548                                                   CollectionExprResult.take(), 0,
1549                                                   ForLoc, RParenLoc));
1550}
1551
1552/// Finish building a variable declaration for a for-range statement.
1553/// \return true if an error occurs.
1554static bool FinishForRangeVarDecl(Sema &SemaRef, VarDecl *Decl, Expr *Init,
1555                                  SourceLocation Loc, int diag) {
1556  // Deduce the type for the iterator variable now rather than leaving it to
1557  // AddInitializerToDecl, so we can produce a more suitable diagnostic.
1558  TypeSourceInfo *InitTSI = 0;
1559  if ((!isa<InitListExpr>(Init) && Init->getType()->isVoidType()) ||
1560      SemaRef.DeduceAutoType(Decl->getTypeSourceInfo(), Init, InitTSI) ==
1561          Sema::DAR_Failed)
1562    SemaRef.Diag(Loc, diag) << Init->getType();
1563  if (!InitTSI) {
1564    Decl->setInvalidDecl();
1565    return true;
1566  }
1567  Decl->setTypeSourceInfo(InitTSI);
1568  Decl->setType(InitTSI->getType());
1569
1570  // In ARC, infer lifetime.
1571  // FIXME: ARC may want to turn this into 'const __unsafe_unretained' if
1572  // we're doing the equivalent of fast iteration.
1573  if (SemaRef.getLangOpts().ObjCAutoRefCount &&
1574      SemaRef.inferObjCARCLifetime(Decl))
1575    Decl->setInvalidDecl();
1576
1577  SemaRef.AddInitializerToDecl(Decl, Init, /*DirectInit=*/false,
1578                               /*TypeMayContainAuto=*/false);
1579  SemaRef.FinalizeDeclaration(Decl);
1580  SemaRef.CurContext->addHiddenDecl(Decl);
1581  return false;
1582}
1583
1584namespace {
1585
1586/// Produce a note indicating which begin/end function was implicitly called
1587/// by a C++11 for-range statement. This is often not obvious from the code,
1588/// nor from the diagnostics produced when analysing the implicit expressions
1589/// required in a for-range statement.
1590void NoteForRangeBeginEndFunction(Sema &SemaRef, Expr *E,
1591                                  Sema::BeginEndFunction BEF) {
1592  CallExpr *CE = dyn_cast<CallExpr>(E);
1593  if (!CE)
1594    return;
1595  FunctionDecl *D = dyn_cast<FunctionDecl>(CE->getCalleeDecl());
1596  if (!D)
1597    return;
1598  SourceLocation Loc = D->getLocation();
1599
1600  std::string Description;
1601  bool IsTemplate = false;
1602  if (FunctionTemplateDecl *FunTmpl = D->getPrimaryTemplate()) {
1603    Description = SemaRef.getTemplateArgumentBindingsText(
1604      FunTmpl->getTemplateParameters(), *D->getTemplateSpecializationArgs());
1605    IsTemplate = true;
1606  }
1607
1608  SemaRef.Diag(Loc, diag::note_for_range_begin_end)
1609    << BEF << IsTemplate << Description << E->getType();
1610}
1611
1612/// Build a variable declaration for a for-range statement.
1613VarDecl *BuildForRangeVarDecl(Sema &SemaRef, SourceLocation Loc,
1614                              QualType Type, const char *Name) {
1615  DeclContext *DC = SemaRef.CurContext;
1616  IdentifierInfo *II = &SemaRef.PP.getIdentifierTable().get(Name);
1617  TypeSourceInfo *TInfo = SemaRef.Context.getTrivialTypeSourceInfo(Type, Loc);
1618  VarDecl *Decl = VarDecl::Create(SemaRef.Context, DC, Loc, Loc, II, Type,
1619                                  TInfo, SC_Auto, SC_None);
1620  Decl->setImplicit();
1621  return Decl;
1622}
1623
1624}
1625
1626static bool ObjCEnumerationCollection(Expr *Collection) {
1627  return !Collection->isTypeDependent()
1628          && Collection->getType()->getAs<ObjCObjectPointerType>() != 0;
1629}
1630
1631/// ActOnCXXForRangeStmt - Check and build a C++11 for-range statement.
1632///
1633/// C++11 [stmt.ranged]:
1634///   A range-based for statement is equivalent to
1635///
1636///   {
1637///     auto && __range = range-init;
1638///     for ( auto __begin = begin-expr,
1639///           __end = end-expr;
1640///           __begin != __end;
1641///           ++__begin ) {
1642///       for-range-declaration = *__begin;
1643///       statement
1644///     }
1645///   }
1646///
1647/// The body of the loop is not available yet, since it cannot be analysed until
1648/// we have determined the type of the for-range-declaration.
1649StmtResult
1650Sema::ActOnCXXForRangeStmt(SourceLocation ForLoc,
1651                           Stmt *First, SourceLocation ColonLoc, Expr *Range,
1652                           SourceLocation RParenLoc, bool ShouldTryDeref) {
1653  if (!First || !Range)
1654    return StmtError();
1655
1656  if (ObjCEnumerationCollection(Range))
1657    return ActOnObjCForCollectionStmt(ForLoc, First, Range, RParenLoc);
1658
1659  DeclStmt *DS = dyn_cast<DeclStmt>(First);
1660  assert(DS && "first part of for range not a decl stmt");
1661
1662  if (!DS->isSingleDecl()) {
1663    Diag(DS->getStartLoc(), diag::err_type_defined_in_for_range);
1664    return StmtError();
1665  }
1666  if (DS->getSingleDecl()->isInvalidDecl())
1667    return StmtError();
1668
1669  if (DiagnoseUnexpandedParameterPack(Range, UPPC_Expression))
1670    return StmtError();
1671
1672  // Build  auto && __range = range-init
1673  SourceLocation RangeLoc = Range->getLocStart();
1674  VarDecl *RangeVar = BuildForRangeVarDecl(*this, RangeLoc,
1675                                           Context.getAutoRRefDeductType(),
1676                                           "__range");
1677  if (FinishForRangeVarDecl(*this, RangeVar, Range, RangeLoc,
1678                            diag::err_for_range_deduction_failure))
1679    return StmtError();
1680
1681  // Claim the type doesn't contain auto: we've already done the checking.
1682  DeclGroupPtrTy RangeGroup =
1683    BuildDeclaratorGroup((Decl**)&RangeVar, 1, /*TypeMayContainAuto=*/false);
1684  StmtResult RangeDecl = ActOnDeclStmt(RangeGroup, RangeLoc, RangeLoc);
1685  if (RangeDecl.isInvalid())
1686    return StmtError();
1687
1688  return BuildCXXForRangeStmt(ForLoc, ColonLoc, RangeDecl.get(),
1689                              /*BeginEndDecl=*/0, /*Cond=*/0, /*Inc=*/0, DS,
1690                              RParenLoc, ShouldTryDeref);
1691}
1692
1693/// \brief Create the initialization, compare, and increment steps for
1694/// the range-based for loop expression.
1695/// This function does not handle array-based for loops,
1696/// which are created in Sema::BuildCXXForRangeStmt.
1697///
1698/// \returns a ForRangeStatus indicating success or what kind of error occurred.
1699/// BeginExpr and EndExpr are set and FRS_Success is returned on success;
1700/// CandidateSet and BEF are set and some non-success value is returned on
1701/// failure.
1702static Sema::ForRangeStatus BuildNonArrayForRange(Sema &SemaRef, Scope *S,
1703                                            Expr *BeginRange, Expr *EndRange,
1704                                            QualType RangeType,
1705                                            VarDecl *BeginVar,
1706                                            VarDecl *EndVar,
1707                                            SourceLocation ColonLoc,
1708                                            OverloadCandidateSet *CandidateSet,
1709                                            ExprResult *BeginExpr,
1710                                            ExprResult *EndExpr,
1711                                            Sema::BeginEndFunction *BEF) {
1712  DeclarationNameInfo BeginNameInfo(
1713      &SemaRef.PP.getIdentifierTable().get("begin"), ColonLoc);
1714  DeclarationNameInfo EndNameInfo(&SemaRef.PP.getIdentifierTable().get("end"),
1715                                  ColonLoc);
1716
1717  LookupResult BeginMemberLookup(SemaRef, BeginNameInfo,
1718                                 Sema::LookupMemberName);
1719  LookupResult EndMemberLookup(SemaRef, EndNameInfo, Sema::LookupMemberName);
1720
1721  if (CXXRecordDecl *D = RangeType->getAsCXXRecordDecl()) {
1722    // - if _RangeT is a class type, the unqualified-ids begin and end are
1723    //   looked up in the scope of class _RangeT as if by class member access
1724    //   lookup (3.4.5), and if either (or both) finds at least one
1725    //   declaration, begin-expr and end-expr are __range.begin() and
1726    //   __range.end(), respectively;
1727    SemaRef.LookupQualifiedName(BeginMemberLookup, D);
1728    SemaRef.LookupQualifiedName(EndMemberLookup, D);
1729
1730    if (BeginMemberLookup.empty() != EndMemberLookup.empty()) {
1731      SourceLocation RangeLoc = BeginVar->getLocation();
1732      *BEF = BeginMemberLookup.empty() ? Sema::BEF_end : Sema::BEF_begin;
1733
1734      SemaRef.Diag(RangeLoc, diag::err_for_range_member_begin_end_mismatch)
1735          << RangeLoc << BeginRange->getType() << *BEF;
1736      return Sema::FRS_DiagnosticIssued;
1737    }
1738  } else {
1739    // - otherwise, begin-expr and end-expr are begin(__range) and
1740    //   end(__range), respectively, where begin and end are looked up with
1741    //   argument-dependent lookup (3.4.2). For the purposes of this name
1742    //   lookup, namespace std is an associated namespace.
1743
1744  }
1745
1746  *BEF = Sema::BEF_begin;
1747  Sema::ForRangeStatus RangeStatus =
1748      SemaRef.BuildForRangeBeginEndCall(S, ColonLoc, ColonLoc, BeginVar,
1749                                        Sema::BEF_begin, BeginNameInfo,
1750                                        BeginMemberLookup, CandidateSet,
1751                                        BeginRange, BeginExpr);
1752
1753  if (RangeStatus != Sema::FRS_Success)
1754    return RangeStatus;
1755  if (FinishForRangeVarDecl(SemaRef, BeginVar, BeginExpr->get(), ColonLoc,
1756                            diag::err_for_range_iter_deduction_failure)) {
1757    NoteForRangeBeginEndFunction(SemaRef, BeginExpr->get(), *BEF);
1758    return Sema::FRS_DiagnosticIssued;
1759  }
1760
1761  *BEF = Sema::BEF_end;
1762  RangeStatus =
1763      SemaRef.BuildForRangeBeginEndCall(S, ColonLoc, ColonLoc, EndVar,
1764                                        Sema::BEF_end, EndNameInfo,
1765                                        EndMemberLookup, CandidateSet,
1766                                        EndRange, EndExpr);
1767  if (RangeStatus != Sema::FRS_Success)
1768    return RangeStatus;
1769  if (FinishForRangeVarDecl(SemaRef, EndVar, EndExpr->get(), ColonLoc,
1770                            diag::err_for_range_iter_deduction_failure)) {
1771    NoteForRangeBeginEndFunction(SemaRef, EndExpr->get(), *BEF);
1772    return Sema::FRS_DiagnosticIssued;
1773  }
1774  return Sema::FRS_Success;
1775}
1776
1777/// Speculatively attempt to dereference an invalid range expression.
1778/// This function will not emit diagnostics, but returns StmtError if
1779/// an error occurs.
1780static StmtResult RebuildForRangeWithDereference(Sema &SemaRef, Scope *S,
1781                                                 SourceLocation ForLoc,
1782                                                 Stmt *LoopVarDecl,
1783                                                 SourceLocation ColonLoc,
1784                                                 Expr *Range,
1785                                                 SourceLocation RangeLoc,
1786                                                 SourceLocation RParenLoc) {
1787  Sema::SFINAETrap Trap(SemaRef);
1788  ExprResult AdjustedRange = SemaRef.BuildUnaryOp(S, RangeLoc, UO_Deref, Range);
1789  StmtResult SR =
1790    SemaRef.ActOnCXXForRangeStmt(ForLoc, LoopVarDecl, ColonLoc,
1791                                 AdjustedRange.get(), RParenLoc, false);
1792  if (Trap.hasErrorOccurred())
1793    return StmtError();
1794  return SR;
1795}
1796
1797/// BuildCXXForRangeStmt - Build or instantiate a C++0x for-range statement.
1798StmtResult
1799Sema::BuildCXXForRangeStmt(SourceLocation ForLoc, SourceLocation ColonLoc,
1800                           Stmt *RangeDecl, Stmt *BeginEnd, Expr *Cond,
1801                           Expr *Inc, Stmt *LoopVarDecl,
1802                           SourceLocation RParenLoc, bool ShouldTryDeref) {
1803  Scope *S = getCurScope();
1804
1805  DeclStmt *RangeDS = cast<DeclStmt>(RangeDecl);
1806  VarDecl *RangeVar = cast<VarDecl>(RangeDS->getSingleDecl());
1807  QualType RangeVarType = RangeVar->getType();
1808
1809  DeclStmt *LoopVarDS = cast<DeclStmt>(LoopVarDecl);
1810  VarDecl *LoopVar = cast<VarDecl>(LoopVarDS->getSingleDecl());
1811
1812  StmtResult BeginEndDecl = BeginEnd;
1813  ExprResult NotEqExpr = Cond, IncrExpr = Inc;
1814
1815  if (!BeginEndDecl.get() && !RangeVarType->isDependentType()) {
1816    SourceLocation RangeLoc = RangeVar->getLocation();
1817
1818    const QualType RangeVarNonRefType = RangeVarType.getNonReferenceType();
1819
1820    ExprResult BeginRangeRef = BuildDeclRefExpr(RangeVar, RangeVarNonRefType,
1821                                                VK_LValue, ColonLoc);
1822    if (BeginRangeRef.isInvalid())
1823      return StmtError();
1824
1825    ExprResult EndRangeRef = BuildDeclRefExpr(RangeVar, RangeVarNonRefType,
1826                                              VK_LValue, ColonLoc);
1827    if (EndRangeRef.isInvalid())
1828      return StmtError();
1829
1830    QualType AutoType = Context.getAutoDeductType();
1831    Expr *Range = RangeVar->getInit();
1832    if (!Range)
1833      return StmtError();
1834    QualType RangeType = Range->getType();
1835
1836    if (RequireCompleteType(RangeLoc, RangeType,
1837                            diag::err_for_range_incomplete_type))
1838      return StmtError();
1839
1840    // Build auto __begin = begin-expr, __end = end-expr.
1841    VarDecl *BeginVar = BuildForRangeVarDecl(*this, ColonLoc, AutoType,
1842                                             "__begin");
1843    VarDecl *EndVar = BuildForRangeVarDecl(*this, ColonLoc, AutoType,
1844                                           "__end");
1845
1846    // Build begin-expr and end-expr and attach to __begin and __end variables.
1847    ExprResult BeginExpr, EndExpr;
1848    if (const ArrayType *UnqAT = RangeType->getAsArrayTypeUnsafe()) {
1849      // - if _RangeT is an array type, begin-expr and end-expr are __range and
1850      //   __range + __bound, respectively, where __bound is the array bound. If
1851      //   _RangeT is an array of unknown size or an array of incomplete type,
1852      //   the program is ill-formed;
1853
1854      // begin-expr is __range.
1855      BeginExpr = BeginRangeRef;
1856      if (FinishForRangeVarDecl(*this, BeginVar, BeginRangeRef.get(), ColonLoc,
1857                                diag::err_for_range_iter_deduction_failure)) {
1858        NoteForRangeBeginEndFunction(*this, BeginExpr.get(), BEF_begin);
1859        return StmtError();
1860      }
1861
1862      // Find the array bound.
1863      ExprResult BoundExpr;
1864      if (const ConstantArrayType *CAT = dyn_cast<ConstantArrayType>(UnqAT))
1865        BoundExpr = Owned(IntegerLiteral::Create(Context, CAT->getSize(),
1866                                                 Context.getPointerDiffType(),
1867                                                 RangeLoc));
1868      else if (const VariableArrayType *VAT =
1869               dyn_cast<VariableArrayType>(UnqAT))
1870        BoundExpr = VAT->getSizeExpr();
1871      else {
1872        // Can't be a DependentSizedArrayType or an IncompleteArrayType since
1873        // UnqAT is not incomplete and Range is not type-dependent.
1874        llvm_unreachable("Unexpected array type in for-range");
1875      }
1876
1877      // end-expr is __range + __bound.
1878      EndExpr = ActOnBinOp(S, ColonLoc, tok::plus, EndRangeRef.get(),
1879                           BoundExpr.get());
1880      if (EndExpr.isInvalid())
1881        return StmtError();
1882      if (FinishForRangeVarDecl(*this, EndVar, EndExpr.get(), ColonLoc,
1883                                diag::err_for_range_iter_deduction_failure)) {
1884        NoteForRangeBeginEndFunction(*this, EndExpr.get(), BEF_end);
1885        return StmtError();
1886      }
1887    } else {
1888      OverloadCandidateSet CandidateSet(RangeLoc);
1889      Sema::BeginEndFunction BEFFailure;
1890      ForRangeStatus RangeStatus =
1891          BuildNonArrayForRange(*this, S, BeginRangeRef.get(),
1892                                EndRangeRef.get(), RangeType,
1893                                BeginVar, EndVar, ColonLoc, &CandidateSet,
1894                                &BeginExpr, &EndExpr, &BEFFailure);
1895
1896      // If building the range failed, try dereferencing the range expression
1897      // unless a diagnostic was issued or the end function is problematic.
1898      if (ShouldTryDeref && RangeStatus == FRS_NoViableFunction &&
1899          BEFFailure == BEF_begin) {
1900        StmtResult SR = RebuildForRangeWithDereference(*this, S, ForLoc,
1901                                                       LoopVarDecl, ColonLoc,
1902                                                       Range, RangeLoc,
1903                                                       RParenLoc);
1904        if (!SR.isInvalid()) {
1905          // The attempt to dereference would succeed; return the result of
1906          // recovery.
1907          Diag(RangeLoc, diag::err_for_range_dereference)
1908              << RangeLoc << RangeType
1909              << FixItHint::CreateInsertion(RangeLoc, "*");
1910          return SR;
1911        }
1912      }
1913
1914      // Otherwise, emit diagnostics if we haven't already.
1915      if (RangeStatus == FRS_NoViableFunction) {
1916        Expr *Range = BEFFailure ?  EndRangeRef.get() : BeginRangeRef.get();
1917        Diag(Range->getLocStart(), diag::err_for_range_invalid)
1918            << RangeLoc << Range->getType() << BEFFailure;
1919        CandidateSet.NoteCandidates(*this, OCD_AllCandidates,
1920                                    llvm::makeArrayRef(&Range, /*NumArgs=*/1));
1921      }
1922      // Return an error if no fix was discovered.
1923      if (RangeStatus != FRS_Success)
1924        return StmtError();
1925    }
1926
1927    assert(!BeginExpr.isInvalid() && !EndExpr.isInvalid() &&
1928           "invalid range expression in for loop");
1929
1930    // C++11 [dcl.spec.auto]p7: BeginType and EndType must be the same.
1931    QualType BeginType = BeginVar->getType(), EndType = EndVar->getType();
1932    if (!Context.hasSameType(BeginType, EndType)) {
1933      Diag(RangeLoc, diag::err_for_range_begin_end_types_differ)
1934        << BeginType << EndType;
1935      NoteForRangeBeginEndFunction(*this, BeginExpr.get(), BEF_begin);
1936      NoteForRangeBeginEndFunction(*this, EndExpr.get(), BEF_end);
1937    }
1938
1939    Decl *BeginEndDecls[] = { BeginVar, EndVar };
1940    // Claim the type doesn't contain auto: we've already done the checking.
1941    DeclGroupPtrTy BeginEndGroup =
1942      BuildDeclaratorGroup(BeginEndDecls, 2, /*TypeMayContainAuto=*/false);
1943    BeginEndDecl = ActOnDeclStmt(BeginEndGroup, ColonLoc, ColonLoc);
1944
1945    const QualType BeginRefNonRefType = BeginType.getNonReferenceType();
1946    ExprResult BeginRef = BuildDeclRefExpr(BeginVar, BeginRefNonRefType,
1947                                           VK_LValue, ColonLoc);
1948    if (BeginRef.isInvalid())
1949      return StmtError();
1950
1951    ExprResult EndRef = BuildDeclRefExpr(EndVar, EndType.getNonReferenceType(),
1952                                         VK_LValue, ColonLoc);
1953    if (EndRef.isInvalid())
1954      return StmtError();
1955
1956    // Build and check __begin != __end expression.
1957    NotEqExpr = ActOnBinOp(S, ColonLoc, tok::exclaimequal,
1958                           BeginRef.get(), EndRef.get());
1959    NotEqExpr = ActOnBooleanCondition(S, ColonLoc, NotEqExpr.get());
1960    NotEqExpr = ActOnFinishFullExpr(NotEqExpr.get());
1961    if (NotEqExpr.isInvalid()) {
1962      NoteForRangeBeginEndFunction(*this, BeginExpr.get(), BEF_begin);
1963      if (!Context.hasSameType(BeginType, EndType))
1964        NoteForRangeBeginEndFunction(*this, EndExpr.get(), BEF_end);
1965      return StmtError();
1966    }
1967
1968    // Build and check ++__begin expression.
1969    BeginRef = BuildDeclRefExpr(BeginVar, BeginRefNonRefType,
1970                                VK_LValue, ColonLoc);
1971    if (BeginRef.isInvalid())
1972      return StmtError();
1973
1974    IncrExpr = ActOnUnaryOp(S, ColonLoc, tok::plusplus, BeginRef.get());
1975    IncrExpr = ActOnFinishFullExpr(IncrExpr.get());
1976    if (IncrExpr.isInvalid()) {
1977      NoteForRangeBeginEndFunction(*this, BeginExpr.get(), BEF_begin);
1978      return StmtError();
1979    }
1980
1981    // Build and check *__begin  expression.
1982    BeginRef = BuildDeclRefExpr(BeginVar, BeginRefNonRefType,
1983                                VK_LValue, ColonLoc);
1984    if (BeginRef.isInvalid())
1985      return StmtError();
1986
1987    ExprResult DerefExpr = ActOnUnaryOp(S, ColonLoc, tok::star, BeginRef.get());
1988    if (DerefExpr.isInvalid()) {
1989      NoteForRangeBeginEndFunction(*this, BeginExpr.get(), BEF_begin);
1990      return StmtError();
1991    }
1992
1993    // Attach  *__begin  as initializer for VD.
1994    if (!LoopVar->isInvalidDecl()) {
1995      AddInitializerToDecl(LoopVar, DerefExpr.get(), /*DirectInit=*/false,
1996                           /*TypeMayContainAuto=*/true);
1997      if (LoopVar->isInvalidDecl())
1998        NoteForRangeBeginEndFunction(*this, BeginExpr.get(), BEF_begin);
1999    }
2000  } else {
2001    // The range is implicitly used as a placeholder when it is dependent.
2002    RangeVar->setUsed();
2003  }
2004
2005  return Owned(new (Context) CXXForRangeStmt(RangeDS,
2006                                     cast_or_null<DeclStmt>(BeginEndDecl.get()),
2007                                             NotEqExpr.take(), IncrExpr.take(),
2008                                             LoopVarDS, /*Body=*/0, ForLoc,
2009                                             ColonLoc, RParenLoc));
2010}
2011
2012/// FinishObjCForCollectionStmt - Attach the body to a objective-C foreach
2013/// statement.
2014StmtResult Sema::FinishObjCForCollectionStmt(Stmt *S, Stmt *B) {
2015  if (!S || !B)
2016    return StmtError();
2017  ObjCForCollectionStmt * ForStmt = cast<ObjCForCollectionStmt>(S);
2018
2019  ForStmt->setBody(B);
2020  return S;
2021}
2022
2023/// FinishCXXForRangeStmt - Attach the body to a C++0x for-range statement.
2024/// This is a separate step from ActOnCXXForRangeStmt because analysis of the
2025/// body cannot be performed until after the type of the range variable is
2026/// determined.
2027StmtResult Sema::FinishCXXForRangeStmt(Stmt *S, Stmt *B) {
2028  if (!S || !B)
2029    return StmtError();
2030
2031  if (isa<ObjCForCollectionStmt>(S))
2032    return FinishObjCForCollectionStmt(S, B);
2033
2034  CXXForRangeStmt *ForStmt = cast<CXXForRangeStmt>(S);
2035  ForStmt->setBody(B);
2036
2037  DiagnoseEmptyStmtBody(ForStmt->getRParenLoc(), B,
2038                        diag::warn_empty_range_based_for_body);
2039
2040  return S;
2041}
2042
2043StmtResult Sema::ActOnGotoStmt(SourceLocation GotoLoc,
2044                               SourceLocation LabelLoc,
2045                               LabelDecl *TheDecl) {
2046  getCurFunction()->setHasBranchIntoScope();
2047  TheDecl->setUsed();
2048  return Owned(new (Context) GotoStmt(TheDecl, GotoLoc, LabelLoc));
2049}
2050
2051StmtResult
2052Sema::ActOnIndirectGotoStmt(SourceLocation GotoLoc, SourceLocation StarLoc,
2053                            Expr *E) {
2054  // Convert operand to void*
2055  if (!E->isTypeDependent()) {
2056    QualType ETy = E->getType();
2057    QualType DestTy = Context.getPointerType(Context.VoidTy.withConst());
2058    ExprResult ExprRes = Owned(E);
2059    AssignConvertType ConvTy =
2060      CheckSingleAssignmentConstraints(DestTy, ExprRes);
2061    if (ExprRes.isInvalid())
2062      return StmtError();
2063    E = ExprRes.take();
2064    if (DiagnoseAssignmentResult(ConvTy, StarLoc, DestTy, ETy, E, AA_Passing))
2065      return StmtError();
2066    E = MaybeCreateExprWithCleanups(E);
2067  }
2068
2069  getCurFunction()->setHasIndirectGoto();
2070
2071  return Owned(new (Context) IndirectGotoStmt(GotoLoc, StarLoc, E));
2072}
2073
2074StmtResult
2075Sema::ActOnContinueStmt(SourceLocation ContinueLoc, Scope *CurScope) {
2076  Scope *S = CurScope->getContinueParent();
2077  if (!S) {
2078    // C99 6.8.6.2p1: A break shall appear only in or as a loop body.
2079    return StmtError(Diag(ContinueLoc, diag::err_continue_not_in_loop));
2080  }
2081
2082  return Owned(new (Context) ContinueStmt(ContinueLoc));
2083}
2084
2085StmtResult
2086Sema::ActOnBreakStmt(SourceLocation BreakLoc, Scope *CurScope) {
2087  Scope *S = CurScope->getBreakParent();
2088  if (!S) {
2089    // C99 6.8.6.3p1: A break shall appear only in or as a switch/loop body.
2090    return StmtError(Diag(BreakLoc, diag::err_break_not_in_loop_or_switch));
2091  }
2092
2093  return Owned(new (Context) BreakStmt(BreakLoc));
2094}
2095
2096/// \brief Determine whether the given expression is a candidate for
2097/// copy elision in either a return statement or a throw expression.
2098///
2099/// \param ReturnType If we're determining the copy elision candidate for
2100/// a return statement, this is the return type of the function. If we're
2101/// determining the copy elision candidate for a throw expression, this will
2102/// be a NULL type.
2103///
2104/// \param E The expression being returned from the function or block, or
2105/// being thrown.
2106///
2107/// \param AllowFunctionParameter Whether we allow function parameters to
2108/// be considered NRVO candidates. C++ prohibits this for NRVO itself, but
2109/// we re-use this logic to determine whether we should try to move as part of
2110/// a return or throw (which does allow function parameters).
2111///
2112/// \returns The NRVO candidate variable, if the return statement may use the
2113/// NRVO, or NULL if there is no such candidate.
2114const VarDecl *Sema::getCopyElisionCandidate(QualType ReturnType,
2115                                             Expr *E,
2116                                             bool AllowFunctionParameter) {
2117  QualType ExprType = E->getType();
2118  // - in a return statement in a function with ...
2119  // ... a class return type ...
2120  if (!ReturnType.isNull()) {
2121    if (!ReturnType->isRecordType())
2122      return 0;
2123    // ... the same cv-unqualified type as the function return type ...
2124    if (!Context.hasSameUnqualifiedType(ReturnType, ExprType))
2125      return 0;
2126  }
2127
2128  // ... the expression is the name of a non-volatile automatic object
2129  // (other than a function or catch-clause parameter)) ...
2130  const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(E->IgnoreParens());
2131  if (!DR || DR->refersToEnclosingLocal())
2132    return 0;
2133  const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl());
2134  if (!VD)
2135    return 0;
2136
2137  // ...object (other than a function or catch-clause parameter)...
2138  if (VD->getKind() != Decl::Var &&
2139      !(AllowFunctionParameter && VD->getKind() == Decl::ParmVar))
2140    return 0;
2141  if (VD->isExceptionVariable()) return 0;
2142
2143  // ...automatic...
2144  if (!VD->hasLocalStorage()) return 0;
2145
2146  // ...non-volatile...
2147  if (VD->getType().isVolatileQualified()) return 0;
2148  if (VD->getType()->isReferenceType()) return 0;
2149
2150  // __block variables can't be allocated in a way that permits NRVO.
2151  if (VD->hasAttr<BlocksAttr>()) return 0;
2152
2153  // Variables with higher required alignment than their type's ABI
2154  // alignment cannot use NRVO.
2155  if (VD->hasAttr<AlignedAttr>() &&
2156      Context.getDeclAlign(VD) > Context.getTypeAlignInChars(VD->getType()))
2157    return 0;
2158
2159  return VD;
2160}
2161
2162/// \brief Perform the initialization of a potentially-movable value, which
2163/// is the result of return value.
2164///
2165/// This routine implements C++0x [class.copy]p33, which attempts to treat
2166/// returned lvalues as rvalues in certain cases (to prefer move construction),
2167/// then falls back to treating them as lvalues if that failed.
2168ExprResult
2169Sema::PerformMoveOrCopyInitialization(const InitializedEntity &Entity,
2170                                      const VarDecl *NRVOCandidate,
2171                                      QualType ResultType,
2172                                      Expr *Value,
2173                                      bool AllowNRVO) {
2174  // C++0x [class.copy]p33:
2175  //   When the criteria for elision of a copy operation are met or would
2176  //   be met save for the fact that the source object is a function
2177  //   parameter, and the object to be copied is designated by an lvalue,
2178  //   overload resolution to select the constructor for the copy is first
2179  //   performed as if the object were designated by an rvalue.
2180  ExprResult Res = ExprError();
2181  if (AllowNRVO &&
2182      (NRVOCandidate || getCopyElisionCandidate(ResultType, Value, true))) {
2183    ImplicitCastExpr AsRvalue(ImplicitCastExpr::OnStack,
2184                              Value->getType(), CK_NoOp, Value, VK_XValue);
2185
2186    Expr *InitExpr = &AsRvalue;
2187    InitializationKind Kind
2188      = InitializationKind::CreateCopy(Value->getLocStart(),
2189                                       Value->getLocStart());
2190    InitializationSequence Seq(*this, Entity, Kind, &InitExpr, 1);
2191
2192    //   [...] If overload resolution fails, or if the type of the first
2193    //   parameter of the selected constructor is not an rvalue reference
2194    //   to the object's type (possibly cv-qualified), overload resolution
2195    //   is performed again, considering the object as an lvalue.
2196    if (Seq) {
2197      for (InitializationSequence::step_iterator Step = Seq.step_begin(),
2198           StepEnd = Seq.step_end();
2199           Step != StepEnd; ++Step) {
2200        if (Step->Kind != InitializationSequence::SK_ConstructorInitialization)
2201          continue;
2202
2203        CXXConstructorDecl *Constructor
2204        = cast<CXXConstructorDecl>(Step->Function.Function);
2205
2206        const RValueReferenceType *RRefType
2207          = Constructor->getParamDecl(0)->getType()
2208                                                 ->getAs<RValueReferenceType>();
2209
2210        // If we don't meet the criteria, break out now.
2211        if (!RRefType ||
2212            !Context.hasSameUnqualifiedType(RRefType->getPointeeType(),
2213                            Context.getTypeDeclType(Constructor->getParent())))
2214          break;
2215
2216        // Promote "AsRvalue" to the heap, since we now need this
2217        // expression node to persist.
2218        Value = ImplicitCastExpr::Create(Context, Value->getType(),
2219                                         CK_NoOp, Value, 0, VK_XValue);
2220
2221        // Complete type-checking the initialization of the return type
2222        // using the constructor we found.
2223        Res = Seq.Perform(*this, Entity, Kind, MultiExprArg(&Value, 1));
2224      }
2225    }
2226  }
2227
2228  // Either we didn't meet the criteria for treating an lvalue as an rvalue,
2229  // above, or overload resolution failed. Either way, we need to try
2230  // (again) now with the return value expression as written.
2231  if (Res.isInvalid())
2232    Res = PerformCopyInitialization(Entity, SourceLocation(), Value);
2233
2234  return Res;
2235}
2236
2237/// ActOnCapScopeReturnStmt - Utility routine to type-check return statements
2238/// for capturing scopes.
2239///
2240StmtResult
2241Sema::ActOnCapScopeReturnStmt(SourceLocation ReturnLoc, Expr *RetValExp) {
2242  // If this is the first return we've seen, infer the return type.
2243  // [expr.prim.lambda]p4 in C++11; block literals follow a superset of those
2244  // rules which allows multiple return statements.
2245  CapturingScopeInfo *CurCap = cast<CapturingScopeInfo>(getCurFunction());
2246  QualType FnRetType = CurCap->ReturnType;
2247
2248  // For blocks/lambdas with implicit return types, we check each return
2249  // statement individually, and deduce the common return type when the block
2250  // or lambda is completed.
2251  if (CurCap->HasImplicitReturnType) {
2252    if (RetValExp && !isa<InitListExpr>(RetValExp)) {
2253      ExprResult Result = DefaultFunctionArrayLvalueConversion(RetValExp);
2254      if (Result.isInvalid())
2255        return StmtError();
2256      RetValExp = Result.take();
2257
2258      if (!RetValExp->isTypeDependent())
2259        FnRetType = RetValExp->getType();
2260      else
2261        FnRetType = CurCap->ReturnType = Context.DependentTy;
2262    } else {
2263      if (RetValExp) {
2264        // C++11 [expr.lambda.prim]p4 bans inferring the result from an
2265        // initializer list, because it is not an expression (even
2266        // though we represent it as one). We still deduce 'void'.
2267        Diag(ReturnLoc, diag::err_lambda_return_init_list)
2268          << RetValExp->getSourceRange();
2269      }
2270
2271      FnRetType = Context.VoidTy;
2272    }
2273
2274    // Although we'll properly infer the type of the block once it's completed,
2275    // make sure we provide a return type now for better error recovery.
2276    if (CurCap->ReturnType.isNull())
2277      CurCap->ReturnType = FnRetType;
2278  }
2279  assert(!FnRetType.isNull());
2280
2281  if (BlockScopeInfo *CurBlock = dyn_cast<BlockScopeInfo>(CurCap)) {
2282    if (CurBlock->FunctionType->getAs<FunctionType>()->getNoReturnAttr()) {
2283      Diag(ReturnLoc, diag::err_noreturn_block_has_return_expr);
2284      return StmtError();
2285    }
2286  } else {
2287    LambdaScopeInfo *LSI = cast<LambdaScopeInfo>(CurCap);
2288    if (LSI->CallOperator->getType()->getAs<FunctionType>()->getNoReturnAttr()){
2289      Diag(ReturnLoc, diag::err_noreturn_lambda_has_return_expr);
2290      return StmtError();
2291    }
2292  }
2293
2294  // Otherwise, verify that this result type matches the previous one.  We are
2295  // pickier with blocks than for normal functions because we don't have GCC
2296  // compatibility to worry about here.
2297  const VarDecl *NRVOCandidate = 0;
2298  if (FnRetType->isDependentType()) {
2299    // Delay processing for now.  TODO: there are lots of dependent
2300    // types we can conclusively prove aren't void.
2301  } else if (FnRetType->isVoidType()) {
2302    if (RetValExp && !isa<InitListExpr>(RetValExp) &&
2303        !(getLangOpts().CPlusPlus &&
2304          (RetValExp->isTypeDependent() ||
2305           RetValExp->getType()->isVoidType()))) {
2306      if (!getLangOpts().CPlusPlus &&
2307          RetValExp->getType()->isVoidType())
2308        Diag(ReturnLoc, diag::ext_return_has_void_expr) << "literal" << 2;
2309      else {
2310        Diag(ReturnLoc, diag::err_return_block_has_expr);
2311        RetValExp = 0;
2312      }
2313    }
2314  } else if (!RetValExp) {
2315    return StmtError(Diag(ReturnLoc, diag::err_block_return_missing_expr));
2316  } else if (!RetValExp->isTypeDependent()) {
2317    // we have a non-void block with an expression, continue checking
2318
2319    // C99 6.8.6.4p3(136): The return statement is not an assignment. The
2320    // overlap restriction of subclause 6.5.16.1 does not apply to the case of
2321    // function return.
2322
2323    // In C++ the return statement is handled via a copy initialization.
2324    // the C version of which boils down to CheckSingleAssignmentConstraints.
2325    NRVOCandidate = getCopyElisionCandidate(FnRetType, RetValExp, false);
2326    InitializedEntity Entity = InitializedEntity::InitializeResult(ReturnLoc,
2327                                                                   FnRetType,
2328                                                          NRVOCandidate != 0);
2329    ExprResult Res = PerformMoveOrCopyInitialization(Entity, NRVOCandidate,
2330                                                     FnRetType, RetValExp);
2331    if (Res.isInvalid()) {
2332      // FIXME: Cleanup temporaries here, anyway?
2333      return StmtError();
2334    }
2335    RetValExp = Res.take();
2336    CheckReturnStackAddr(RetValExp, FnRetType, ReturnLoc);
2337  }
2338
2339  if (RetValExp) {
2340    CheckImplicitConversions(RetValExp, ReturnLoc);
2341    RetValExp = MaybeCreateExprWithCleanups(RetValExp);
2342  }
2343  ReturnStmt *Result = new (Context) ReturnStmt(ReturnLoc, RetValExp,
2344                                                NRVOCandidate);
2345
2346  // If we need to check for the named return value optimization,
2347  // or if we need to infer the return type,
2348  // save the return statement in our scope for later processing.
2349  if (CurCap->HasImplicitReturnType ||
2350      (getLangOpts().CPlusPlus && FnRetType->isRecordType() &&
2351       !CurContext->isDependentContext()))
2352    FunctionScopes.back()->Returns.push_back(Result);
2353
2354  return Owned(Result);
2355}
2356
2357StmtResult
2358Sema::ActOnReturnStmt(SourceLocation ReturnLoc, Expr *RetValExp) {
2359  // Check for unexpanded parameter packs.
2360  if (RetValExp && DiagnoseUnexpandedParameterPack(RetValExp))
2361    return StmtError();
2362
2363  if (isa<CapturingScopeInfo>(getCurFunction()))
2364    return ActOnCapScopeReturnStmt(ReturnLoc, RetValExp);
2365
2366  QualType FnRetType;
2367  QualType RelatedRetType;
2368  if (const FunctionDecl *FD = getCurFunctionDecl()) {
2369    FnRetType = FD->getResultType();
2370    if (FD->hasAttr<NoReturnAttr>() ||
2371        FD->getType()->getAs<FunctionType>()->getNoReturnAttr())
2372      Diag(ReturnLoc, diag::warn_noreturn_function_has_return_expr)
2373        << FD->getDeclName();
2374  } else if (ObjCMethodDecl *MD = getCurMethodDecl()) {
2375    FnRetType = MD->getResultType();
2376    if (MD->hasRelatedResultType() && MD->getClassInterface()) {
2377      // In the implementation of a method with a related return type, the
2378      // type used to type-check the validity of return statements within the
2379      // method body is a pointer to the type of the class being implemented.
2380      RelatedRetType = Context.getObjCInterfaceType(MD->getClassInterface());
2381      RelatedRetType = Context.getObjCObjectPointerType(RelatedRetType);
2382    }
2383  } else // If we don't have a function/method context, bail.
2384    return StmtError();
2385
2386  ReturnStmt *Result = 0;
2387  if (FnRetType->isVoidType()) {
2388    if (RetValExp) {
2389      if (isa<InitListExpr>(RetValExp)) {
2390        // We simply never allow init lists as the return value of void
2391        // functions. This is compatible because this was never allowed before,
2392        // so there's no legacy code to deal with.
2393        NamedDecl *CurDecl = getCurFunctionOrMethodDecl();
2394        int FunctionKind = 0;
2395        if (isa<ObjCMethodDecl>(CurDecl))
2396          FunctionKind = 1;
2397        else if (isa<CXXConstructorDecl>(CurDecl))
2398          FunctionKind = 2;
2399        else if (isa<CXXDestructorDecl>(CurDecl))
2400          FunctionKind = 3;
2401
2402        Diag(ReturnLoc, diag::err_return_init_list)
2403          << CurDecl->getDeclName() << FunctionKind
2404          << RetValExp->getSourceRange();
2405
2406        // Drop the expression.
2407        RetValExp = 0;
2408      } else if (!RetValExp->isTypeDependent()) {
2409        // C99 6.8.6.4p1 (ext_ since GCC warns)
2410        unsigned D = diag::ext_return_has_expr;
2411        if (RetValExp->getType()->isVoidType())
2412          D = diag::ext_return_has_void_expr;
2413        else {
2414          ExprResult Result = Owned(RetValExp);
2415          Result = IgnoredValueConversions(Result.take());
2416          if (Result.isInvalid())
2417            return StmtError();
2418          RetValExp = Result.take();
2419          RetValExp = ImpCastExprToType(RetValExp,
2420                                        Context.VoidTy, CK_ToVoid).take();
2421        }
2422
2423        // return (some void expression); is legal in C++.
2424        if (D != diag::ext_return_has_void_expr ||
2425            !getLangOpts().CPlusPlus) {
2426          NamedDecl *CurDecl = getCurFunctionOrMethodDecl();
2427
2428          int FunctionKind = 0;
2429          if (isa<ObjCMethodDecl>(CurDecl))
2430            FunctionKind = 1;
2431          else if (isa<CXXConstructorDecl>(CurDecl))
2432            FunctionKind = 2;
2433          else if (isa<CXXDestructorDecl>(CurDecl))
2434            FunctionKind = 3;
2435
2436          Diag(ReturnLoc, D)
2437            << CurDecl->getDeclName() << FunctionKind
2438            << RetValExp->getSourceRange();
2439        }
2440      }
2441
2442      if (RetValExp) {
2443        CheckImplicitConversions(RetValExp, ReturnLoc);
2444        RetValExp = MaybeCreateExprWithCleanups(RetValExp);
2445      }
2446    }
2447
2448    Result = new (Context) ReturnStmt(ReturnLoc, RetValExp, 0);
2449  } else if (!RetValExp && !FnRetType->isDependentType()) {
2450    unsigned DiagID = diag::warn_return_missing_expr;  // C90 6.6.6.4p4
2451    // C99 6.8.6.4p1 (ext_ since GCC warns)
2452    if (getLangOpts().C99) DiagID = diag::ext_return_missing_expr;
2453
2454    if (FunctionDecl *FD = getCurFunctionDecl())
2455      Diag(ReturnLoc, DiagID) << FD->getIdentifier() << 0/*fn*/;
2456    else
2457      Diag(ReturnLoc, DiagID) << getCurMethodDecl()->getDeclName() << 1/*meth*/;
2458    Result = new (Context) ReturnStmt(ReturnLoc);
2459  } else {
2460    const VarDecl *NRVOCandidate = 0;
2461    if (!FnRetType->isDependentType() && !RetValExp->isTypeDependent()) {
2462      // we have a non-void function with an expression, continue checking
2463
2464      if (!RelatedRetType.isNull()) {
2465        // If we have a related result type, perform an extra conversion here.
2466        // FIXME: The diagnostics here don't really describe what is happening.
2467        InitializedEntity Entity =
2468            InitializedEntity::InitializeTemporary(RelatedRetType);
2469
2470        ExprResult Res = PerformCopyInitialization(Entity, SourceLocation(),
2471                                                   RetValExp);
2472        if (Res.isInvalid()) {
2473          // FIXME: Cleanup temporaries here, anyway?
2474          return StmtError();
2475        }
2476        RetValExp = Res.takeAs<Expr>();
2477      }
2478
2479      // C99 6.8.6.4p3(136): The return statement is not an assignment. The
2480      // overlap restriction of subclause 6.5.16.1 does not apply to the case of
2481      // function return.
2482
2483      // In C++ the return statement is handled via a copy initialization,
2484      // the C version of which boils down to CheckSingleAssignmentConstraints.
2485      NRVOCandidate = getCopyElisionCandidate(FnRetType, RetValExp, false);
2486      InitializedEntity Entity = InitializedEntity::InitializeResult(ReturnLoc,
2487                                                                     FnRetType,
2488                                                            NRVOCandidate != 0);
2489      ExprResult Res = PerformMoveOrCopyInitialization(Entity, NRVOCandidate,
2490                                                       FnRetType, RetValExp);
2491      if (Res.isInvalid()) {
2492        // FIXME: Cleanup temporaries here, anyway?
2493        return StmtError();
2494      }
2495
2496      RetValExp = Res.takeAs<Expr>();
2497      if (RetValExp)
2498        CheckReturnStackAddr(RetValExp, FnRetType, ReturnLoc);
2499    }
2500
2501    if (RetValExp) {
2502      CheckImplicitConversions(RetValExp, ReturnLoc);
2503      RetValExp = MaybeCreateExprWithCleanups(RetValExp);
2504    }
2505    Result = new (Context) ReturnStmt(ReturnLoc, RetValExp, NRVOCandidate);
2506  }
2507
2508  // If we need to check for the named return value optimization, save the
2509  // return statement in our scope for later processing.
2510  if (getLangOpts().CPlusPlus && FnRetType->isRecordType() &&
2511      !CurContext->isDependentContext())
2512    FunctionScopes.back()->Returns.push_back(Result);
2513
2514  return Owned(Result);
2515}
2516
2517StmtResult
2518Sema::ActOnObjCAtCatchStmt(SourceLocation AtLoc,
2519                           SourceLocation RParen, Decl *Parm,
2520                           Stmt *Body) {
2521  VarDecl *Var = cast_or_null<VarDecl>(Parm);
2522  if (Var && Var->isInvalidDecl())
2523    return StmtError();
2524
2525  return Owned(new (Context) ObjCAtCatchStmt(AtLoc, RParen, Var, Body));
2526}
2527
2528StmtResult
2529Sema::ActOnObjCAtFinallyStmt(SourceLocation AtLoc, Stmt *Body) {
2530  return Owned(new (Context) ObjCAtFinallyStmt(AtLoc, Body));
2531}
2532
2533StmtResult
2534Sema::ActOnObjCAtTryStmt(SourceLocation AtLoc, Stmt *Try,
2535                         MultiStmtArg CatchStmts, Stmt *Finally) {
2536  if (!getLangOpts().ObjCExceptions)
2537    Diag(AtLoc, diag::err_objc_exceptions_disabled) << "@try";
2538
2539  getCurFunction()->setHasBranchProtectedScope();
2540  unsigned NumCatchStmts = CatchStmts.size();
2541  return Owned(ObjCAtTryStmt::Create(Context, AtLoc, Try,
2542                                     CatchStmts.data(),
2543                                     NumCatchStmts,
2544                                     Finally));
2545}
2546
2547StmtResult Sema::BuildObjCAtThrowStmt(SourceLocation AtLoc, Expr *Throw) {
2548  if (Throw) {
2549    ExprResult Result = DefaultLvalueConversion(Throw);
2550    if (Result.isInvalid())
2551      return StmtError();
2552
2553    Throw = MaybeCreateExprWithCleanups(Result.take());
2554    QualType ThrowType = Throw->getType();
2555    // Make sure the expression type is an ObjC pointer or "void *".
2556    if (!ThrowType->isDependentType() &&
2557        !ThrowType->isObjCObjectPointerType()) {
2558      const PointerType *PT = ThrowType->getAs<PointerType>();
2559      if (!PT || !PT->getPointeeType()->isVoidType())
2560        return StmtError(Diag(AtLoc, diag::error_objc_throw_expects_object)
2561                         << Throw->getType() << Throw->getSourceRange());
2562    }
2563  }
2564
2565  return Owned(new (Context) ObjCAtThrowStmt(AtLoc, Throw));
2566}
2567
2568StmtResult
2569Sema::ActOnObjCAtThrowStmt(SourceLocation AtLoc, Expr *Throw,
2570                           Scope *CurScope) {
2571  if (!getLangOpts().ObjCExceptions)
2572    Diag(AtLoc, diag::err_objc_exceptions_disabled) << "@throw";
2573
2574  if (!Throw) {
2575    // @throw without an expression designates a rethrow (which much occur
2576    // in the context of an @catch clause).
2577    Scope *AtCatchParent = CurScope;
2578    while (AtCatchParent && !AtCatchParent->isAtCatchScope())
2579      AtCatchParent = AtCatchParent->getParent();
2580    if (!AtCatchParent)
2581      return StmtError(Diag(AtLoc, diag::error_rethrow_used_outside_catch));
2582  }
2583  return BuildObjCAtThrowStmt(AtLoc, Throw);
2584}
2585
2586ExprResult
2587Sema::ActOnObjCAtSynchronizedOperand(SourceLocation atLoc, Expr *operand) {
2588  ExprResult result = DefaultLvalueConversion(operand);
2589  if (result.isInvalid())
2590    return ExprError();
2591  operand = result.take();
2592
2593  // Make sure the expression type is an ObjC pointer or "void *".
2594  QualType type = operand->getType();
2595  if (!type->isDependentType() &&
2596      !type->isObjCObjectPointerType()) {
2597    const PointerType *pointerType = type->getAs<PointerType>();
2598    if (!pointerType || !pointerType->getPointeeType()->isVoidType())
2599      return Diag(atLoc, diag::error_objc_synchronized_expects_object)
2600               << type << operand->getSourceRange();
2601  }
2602
2603  // The operand to @synchronized is a full-expression.
2604  return MaybeCreateExprWithCleanups(operand);
2605}
2606
2607StmtResult
2608Sema::ActOnObjCAtSynchronizedStmt(SourceLocation AtLoc, Expr *SyncExpr,
2609                                  Stmt *SyncBody) {
2610  // We can't jump into or indirect-jump out of a @synchronized block.
2611  getCurFunction()->setHasBranchProtectedScope();
2612  return Owned(new (Context) ObjCAtSynchronizedStmt(AtLoc, SyncExpr, SyncBody));
2613}
2614
2615/// ActOnCXXCatchBlock - Takes an exception declaration and a handler block
2616/// and creates a proper catch handler from them.
2617StmtResult
2618Sema::ActOnCXXCatchBlock(SourceLocation CatchLoc, Decl *ExDecl,
2619                         Stmt *HandlerBlock) {
2620  // There's nothing to test that ActOnExceptionDecl didn't already test.
2621  return Owned(new (Context) CXXCatchStmt(CatchLoc,
2622                                          cast_or_null<VarDecl>(ExDecl),
2623                                          HandlerBlock));
2624}
2625
2626StmtResult
2627Sema::ActOnObjCAutoreleasePoolStmt(SourceLocation AtLoc, Stmt *Body) {
2628  getCurFunction()->setHasBranchProtectedScope();
2629  return Owned(new (Context) ObjCAutoreleasePoolStmt(AtLoc, Body));
2630}
2631
2632namespace {
2633
2634class TypeWithHandler {
2635  QualType t;
2636  CXXCatchStmt *stmt;
2637public:
2638  TypeWithHandler(const QualType &type, CXXCatchStmt *statement)
2639  : t(type), stmt(statement) {}
2640
2641  // An arbitrary order is fine as long as it places identical
2642  // types next to each other.
2643  bool operator<(const TypeWithHandler &y) const {
2644    if (t.getAsOpaquePtr() < y.t.getAsOpaquePtr())
2645      return true;
2646    if (t.getAsOpaquePtr() > y.t.getAsOpaquePtr())
2647      return false;
2648    else
2649      return getTypeSpecStartLoc() < y.getTypeSpecStartLoc();
2650  }
2651
2652  bool operator==(const TypeWithHandler& other) const {
2653    return t == other.t;
2654  }
2655
2656  CXXCatchStmt *getCatchStmt() const { return stmt; }
2657  SourceLocation getTypeSpecStartLoc() const {
2658    return stmt->getExceptionDecl()->getTypeSpecStartLoc();
2659  }
2660};
2661
2662}
2663
2664/// ActOnCXXTryBlock - Takes a try compound-statement and a number of
2665/// handlers and creates a try statement from them.
2666StmtResult
2667Sema::ActOnCXXTryBlock(SourceLocation TryLoc, Stmt *TryBlock,
2668                       MultiStmtArg RawHandlers) {
2669  // Don't report an error if 'try' is used in system headers.
2670  if (!getLangOpts().CXXExceptions &&
2671      !getSourceManager().isInSystemHeader(TryLoc))
2672      Diag(TryLoc, diag::err_exceptions_disabled) << "try";
2673
2674  unsigned NumHandlers = RawHandlers.size();
2675  assert(NumHandlers > 0 &&
2676         "The parser shouldn't call this if there are no handlers.");
2677  Stmt **Handlers = RawHandlers.data();
2678
2679  SmallVector<TypeWithHandler, 8> TypesWithHandlers;
2680
2681  for (unsigned i = 0; i < NumHandlers; ++i) {
2682    CXXCatchStmt *Handler = cast<CXXCatchStmt>(Handlers[i]);
2683    if (!Handler->getExceptionDecl()) {
2684      if (i < NumHandlers - 1)
2685        return StmtError(Diag(Handler->getLocStart(),
2686                              diag::err_early_catch_all));
2687
2688      continue;
2689    }
2690
2691    const QualType CaughtType = Handler->getCaughtType();
2692    const QualType CanonicalCaughtType = Context.getCanonicalType(CaughtType);
2693    TypesWithHandlers.push_back(TypeWithHandler(CanonicalCaughtType, Handler));
2694  }
2695
2696  // Detect handlers for the same type as an earlier one.
2697  if (NumHandlers > 1) {
2698    llvm::array_pod_sort(TypesWithHandlers.begin(), TypesWithHandlers.end());
2699
2700    TypeWithHandler prev = TypesWithHandlers[0];
2701    for (unsigned i = 1; i < TypesWithHandlers.size(); ++i) {
2702      TypeWithHandler curr = TypesWithHandlers[i];
2703
2704      if (curr == prev) {
2705        Diag(curr.getTypeSpecStartLoc(),
2706             diag::warn_exception_caught_by_earlier_handler)
2707          << curr.getCatchStmt()->getCaughtType().getAsString();
2708        Diag(prev.getTypeSpecStartLoc(),
2709             diag::note_previous_exception_handler)
2710          << prev.getCatchStmt()->getCaughtType().getAsString();
2711      }
2712
2713      prev = curr;
2714    }
2715  }
2716
2717  getCurFunction()->setHasBranchProtectedScope();
2718
2719  // FIXME: We should detect handlers that cannot catch anything because an
2720  // earlier handler catches a superclass. Need to find a method that is not
2721  // quadratic for this.
2722  // Neither of these are explicitly forbidden, but every compiler detects them
2723  // and warns.
2724
2725  return Owned(CXXTryStmt::Create(Context, TryLoc, TryBlock,
2726                                  Handlers, NumHandlers));
2727}
2728
2729StmtResult
2730Sema::ActOnSEHTryBlock(bool IsCXXTry,
2731                       SourceLocation TryLoc,
2732                       Stmt *TryBlock,
2733                       Stmt *Handler) {
2734  assert(TryBlock && Handler);
2735
2736  getCurFunction()->setHasBranchProtectedScope();
2737
2738  return Owned(SEHTryStmt::Create(Context,IsCXXTry,TryLoc,TryBlock,Handler));
2739}
2740
2741StmtResult
2742Sema::ActOnSEHExceptBlock(SourceLocation Loc,
2743                          Expr *FilterExpr,
2744                          Stmt *Block) {
2745  assert(FilterExpr && Block);
2746
2747  if(!FilterExpr->getType()->isIntegerType()) {
2748    return StmtError(Diag(FilterExpr->getExprLoc(),
2749                     diag::err_filter_expression_integral)
2750                     << FilterExpr->getType());
2751  }
2752
2753  return Owned(SEHExceptStmt::Create(Context,Loc,FilterExpr,Block));
2754}
2755
2756StmtResult
2757Sema::ActOnSEHFinallyBlock(SourceLocation Loc,
2758                           Stmt *Block) {
2759  assert(Block);
2760  return Owned(SEHFinallyStmt::Create(Context,Loc,Block));
2761}
2762
2763StmtResult Sema::BuildMSDependentExistsStmt(SourceLocation KeywordLoc,
2764                                            bool IsIfExists,
2765                                            NestedNameSpecifierLoc QualifierLoc,
2766                                            DeclarationNameInfo NameInfo,
2767                                            Stmt *Nested)
2768{
2769  return new (Context) MSDependentExistsStmt(KeywordLoc, IsIfExists,
2770                                             QualifierLoc, NameInfo,
2771                                             cast<CompoundStmt>(Nested));
2772}
2773
2774
2775StmtResult Sema::ActOnMSDependentExistsStmt(SourceLocation KeywordLoc,
2776                                            bool IsIfExists,
2777                                            CXXScopeSpec &SS,
2778                                            UnqualifiedId &Name,
2779                                            Stmt *Nested) {
2780  return BuildMSDependentExistsStmt(KeywordLoc, IsIfExists,
2781                                    SS.getWithLocInContext(Context),
2782                                    GetNameFromUnqualifiedId(Name),
2783                                    Nested);
2784}
2785