SemaStmt.cpp revision 9ea9bdbc14374f7bacdb50d3e52c664ff12150ff 
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 "Sema.h"
15#include "SemaInit.h"
16#include "clang/AST/APValue.h"
17#include "clang/AST/ASTContext.h"
18#include "clang/AST/DeclObjC.h"
19#include "clang/AST/ExprCXX.h"
20#include "clang/AST/ExprObjC.h"
21#include "clang/AST/StmtObjC.h"
22#include "clang/AST/StmtCXX.h"
23#include "clang/Lex/Preprocessor.h"
24#include "clang/Basic/TargetInfo.h"
25#include "llvm/ADT/STLExtras.h"
26#include "llvm/ADT/SmallVector.h"
27using namespace clang;
28
29Sema::OwningStmtResult Sema::ActOnExprStmt(FullExprArg expr) {
30  Expr *E = expr->takeAs<Expr>();
31  assert(E && "ActOnExprStmt(): missing expression");
32  if (E->getType()->isObjCInterfaceType()) {
33    if (LangOpts.ObjCNonFragileABI)
34      Diag(E->getLocEnd(), diag::err_indirection_requires_nonfragile_object)
35             << E->getType();
36    else
37      Diag(E->getLocEnd(), diag::err_direct_interface_unsupported)
38             << E->getType();
39    return StmtError();
40  }
41  // C99 6.8.3p2: The expression in an expression statement is evaluated as a
42  // void expression for its side effects.  Conversion to void allows any
43  // operand, even incomplete types.
44
45  // Same thing in for stmt first clause (when expr) and third clause.
46  return Owned(static_cast<Stmt*>(E));
47}
48
49
50Sema::OwningStmtResult Sema::ActOnNullStmt(SourceLocation SemiLoc) {
51  return Owned(new (Context) NullStmt(SemiLoc));
52}
53
54Sema::OwningStmtResult Sema::ActOnDeclStmt(DeclGroupPtrTy dg,
55                                           SourceLocation StartLoc,
56                                           SourceLocation EndLoc) {
57  DeclGroupRef DG = dg.getAsVal<DeclGroupRef>();
58
59  // If we have an invalid decl, just return an error.
60  if (DG.isNull()) return StmtError();
61
62  return Owned(new (Context) DeclStmt(DG, StartLoc, EndLoc));
63}
64
65void Sema::ActOnForEachDeclStmt(DeclGroupPtrTy dg) {
66  DeclGroupRef DG = dg.getAsVal<DeclGroupRef>();
67
68  // If we have an invalid decl, just return.
69  if (DG.isNull() || !DG.isSingleDecl()) return;
70  // suppress any potential 'unused variable' warning.
71  DG.getSingleDecl()->setUsed();
72}
73
74void Sema::DiagnoseUnusedExprResult(const Stmt *S) {
75  const Expr *E = dyn_cast_or_null<Expr>(S);
76  if (!E)
77    return;
78
79  // Ignore expressions that have void type.
80  if (E->getType()->isVoidType())
81    return;
82
83  SourceLocation Loc;
84  SourceRange R1, R2;
85  if (!E->isUnusedResultAWarning(Loc, R1, R2, Context))
86    return;
87
88  // Okay, we have an unused result.  Depending on what the base expression is,
89  // we might want to make a more specific diagnostic.  Check for one of these
90  // cases now.
91  unsigned DiagID = diag::warn_unused_expr;
92  E = E->IgnoreParens();
93  if (isa<ObjCImplicitSetterGetterRefExpr>(E))
94    DiagID = diag::warn_unused_property_expr;
95
96  if (const CXXExprWithTemporaries *Temps = dyn_cast<CXXExprWithTemporaries>(E))
97    E = Temps->getSubExpr();
98  if (const CXXZeroInitValueExpr *Zero = dyn_cast<CXXZeroInitValueExpr>(E)) {
99    if (const RecordType *RecordT = Zero->getType()->getAs<RecordType>())
100      if (CXXRecordDecl *RecordD = dyn_cast<CXXRecordDecl>(RecordT->getDecl()))
101        if (!RecordD->hasTrivialDestructor())
102          return;
103  }
104
105  if (const CallExpr *CE = dyn_cast<CallExpr>(E)) {
106    // If the callee has attribute pure, const, or warn_unused_result, warn with
107    // a more specific message to make it clear what is happening.
108    if (const Decl *FD = CE->getCalleeDecl()) {
109      if (FD->getAttr<WarnUnusedResultAttr>()) {
110        Diag(Loc, diag::warn_unused_call) << R1 << R2 << "warn_unused_result";
111        return;
112      }
113      if (FD->getAttr<PureAttr>()) {
114        Diag(Loc, diag::warn_unused_call) << R1 << R2 << "pure";
115        return;
116      }
117      if (FD->getAttr<ConstAttr>()) {
118        Diag(Loc, diag::warn_unused_call) << R1 << R2 << "const";
119        return;
120      }
121    }
122  }
123
124  Diag(Loc, DiagID) << R1 << R2;
125}
126
127Action::OwningStmtResult
128Sema::ActOnCompoundStmt(SourceLocation L, SourceLocation R,
129                        MultiStmtArg elts, bool isStmtExpr) {
130  unsigned NumElts = elts.size();
131  Stmt **Elts = reinterpret_cast<Stmt**>(elts.release());
132  // If we're in C89 mode, check that we don't have any decls after stmts.  If
133  // so, emit an extension diagnostic.
134  if (!getLangOptions().C99 && !getLangOptions().CPlusPlus) {
135    // Note that __extension__ can be around a decl.
136    unsigned i = 0;
137    // Skip over all declarations.
138    for (; i != NumElts && isa<DeclStmt>(Elts[i]); ++i)
139      /*empty*/;
140
141    // We found the end of the list or a statement.  Scan for another declstmt.
142    for (; i != NumElts && !isa<DeclStmt>(Elts[i]); ++i)
143      /*empty*/;
144
145    if (i != NumElts) {
146      Decl *D = *cast<DeclStmt>(Elts[i])->decl_begin();
147      Diag(D->getLocation(), diag::ext_mixed_decls_code);
148    }
149  }
150  // Warn about unused expressions in statements.
151  for (unsigned i = 0; i != NumElts; ++i) {
152    // Ignore statements that are last in a statement expression.
153    if (isStmtExpr && i == NumElts - 1)
154      continue;
155
156    DiagnoseUnusedExprResult(Elts[i]);
157  }
158
159  return Owned(new (Context) CompoundStmt(Context, Elts, NumElts, L, R));
160}
161
162Action::OwningStmtResult
163Sema::ActOnCaseStmt(SourceLocation CaseLoc, ExprArg lhsval,
164                    SourceLocation DotDotDotLoc, ExprArg rhsval,
165                    SourceLocation ColonLoc) {
166  assert((lhsval.get() != 0) && "missing expression in case statement");
167
168  // C99 6.8.4.2p3: The expression shall be an integer constant.
169  // However, GCC allows any evaluatable integer expression.
170  Expr *LHSVal = static_cast<Expr*>(lhsval.get());
171  if (!LHSVal->isTypeDependent() && !LHSVal->isValueDependent() &&
172      VerifyIntegerConstantExpression(LHSVal))
173    return StmtError();
174
175  // GCC extension: The expression shall be an integer constant.
176
177  Expr *RHSVal = static_cast<Expr*>(rhsval.get());
178  if (RHSVal && !RHSVal->isTypeDependent() && !RHSVal->isValueDependent() &&
179      VerifyIntegerConstantExpression(RHSVal)) {
180    RHSVal = 0;  // Recover by just forgetting about it.
181    rhsval = 0;
182  }
183
184  if (getSwitchStack().empty()) {
185    Diag(CaseLoc, diag::err_case_not_in_switch);
186    return StmtError();
187  }
188
189  // Only now release the smart pointers.
190  lhsval.release();
191  rhsval.release();
192  CaseStmt *CS = new (Context) CaseStmt(LHSVal, RHSVal, CaseLoc, DotDotDotLoc,
193                                        ColonLoc);
194  getSwitchStack().back()->addSwitchCase(CS);
195  return Owned(CS);
196}
197
198/// ActOnCaseStmtBody - This installs a statement as the body of a case.
199void Sema::ActOnCaseStmtBody(StmtTy *caseStmt, StmtArg subStmt) {
200  CaseStmt *CS = static_cast<CaseStmt*>(caseStmt);
201  Stmt *SubStmt = subStmt.takeAs<Stmt>();
202  CS->setSubStmt(SubStmt);
203}
204
205Action::OwningStmtResult
206Sema::ActOnDefaultStmt(SourceLocation DefaultLoc, SourceLocation ColonLoc,
207                       StmtArg subStmt, Scope *CurScope) {
208  Stmt *SubStmt = subStmt.takeAs<Stmt>();
209
210  if (getSwitchStack().empty()) {
211    Diag(DefaultLoc, diag::err_default_not_in_switch);
212    return Owned(SubStmt);
213  }
214
215  DefaultStmt *DS = new (Context) DefaultStmt(DefaultLoc, ColonLoc, SubStmt);
216  getSwitchStack().back()->addSwitchCase(DS);
217  return Owned(DS);
218}
219
220Action::OwningStmtResult
221Sema::ActOnLabelStmt(SourceLocation IdentLoc, IdentifierInfo *II,
222                     SourceLocation ColonLoc, StmtArg subStmt) {
223  Stmt *SubStmt = subStmt.takeAs<Stmt>();
224  // Look up the record for this label identifier.
225  LabelStmt *&LabelDecl = getLabelMap()[II];
226
227  // If not forward referenced or defined already, just create a new LabelStmt.
228  if (LabelDecl == 0)
229    return Owned(LabelDecl = new (Context) LabelStmt(IdentLoc, II, SubStmt));
230
231  assert(LabelDecl->getID() == II && "Label mismatch!");
232
233  // Otherwise, this label was either forward reference or multiply defined.  If
234  // multiply defined, reject it now.
235  if (LabelDecl->getSubStmt()) {
236    Diag(IdentLoc, diag::err_redefinition_of_label) << LabelDecl->getID();
237    Diag(LabelDecl->getIdentLoc(), diag::note_previous_definition);
238    return Owned(SubStmt);
239  }
240
241  // Otherwise, this label was forward declared, and we just found its real
242  // definition.  Fill in the forward definition and return it.
243  LabelDecl->setIdentLoc(IdentLoc);
244  LabelDecl->setSubStmt(SubStmt);
245  return Owned(LabelDecl);
246}
247
248Action::OwningStmtResult
249Sema::ActOnIfStmt(SourceLocation IfLoc, FullExprArg CondVal, DeclPtrTy CondVar,
250                  StmtArg ThenVal, SourceLocation ElseLoc,
251                  StmtArg ElseVal) {
252  OwningExprResult CondResult(CondVal.release());
253
254  VarDecl *ConditionVar = 0;
255  if (CondVar.get()) {
256    ConditionVar = CondVar.getAs<VarDecl>();
257    CondResult = CheckConditionVariable(ConditionVar);
258    if (CondResult.isInvalid())
259      return StmtError();
260  }
261  Expr *ConditionExpr = CondResult.takeAs<Expr>();
262  if (!ConditionExpr)
263    return StmtError();
264
265  if (CheckBooleanCondition(ConditionExpr, IfLoc)) {
266    CondResult = ConditionExpr;
267    return StmtError();
268  }
269
270  Stmt *thenStmt = ThenVal.takeAs<Stmt>();
271  DiagnoseUnusedExprResult(thenStmt);
272
273  // Warn if the if block has a null body without an else value.
274  // this helps prevent bugs due to typos, such as
275  // if (condition);
276  //   do_stuff();
277  if (!ElseVal.get()) {
278    if (NullStmt* stmt = dyn_cast<NullStmt>(thenStmt))
279      Diag(stmt->getSemiLoc(), diag::warn_empty_if_body);
280  }
281
282  Stmt *elseStmt = ElseVal.takeAs<Stmt>();
283  DiagnoseUnusedExprResult(elseStmt);
284
285  CondResult.release();
286  return Owned(new (Context) IfStmt(IfLoc, ConditionVar, ConditionExpr,
287                                    thenStmt, ElseLoc, elseStmt));
288}
289
290Action::OwningStmtResult
291Sema::ActOnStartOfSwitchStmt(FullExprArg cond, DeclPtrTy CondVar) {
292  OwningExprResult CondResult(cond.release());
293
294  VarDecl *ConditionVar = 0;
295  if (CondVar.get()) {
296    ConditionVar = CondVar.getAs<VarDecl>();
297    CondResult = CheckConditionVariable(ConditionVar);
298    if (CondResult.isInvalid())
299      return StmtError();
300  }
301  SwitchStmt *SS = new (Context) SwitchStmt(ConditionVar,
302                                            CondResult.takeAs<Expr>());
303  getSwitchStack().push_back(SS);
304  return Owned(SS);
305}
306
307/// ConvertIntegerToTypeWarnOnOverflow - Convert the specified APInt to have
308/// the specified width and sign.  If an overflow occurs, detect it and emit
309/// the specified diagnostic.
310void Sema::ConvertIntegerToTypeWarnOnOverflow(llvm::APSInt &Val,
311                                              unsigned NewWidth, bool NewSign,
312                                              SourceLocation Loc,
313                                              unsigned DiagID) {
314  // Perform a conversion to the promoted condition type if needed.
315  if (NewWidth > Val.getBitWidth()) {
316    // If this is an extension, just do it.
317    Val.extend(NewWidth);
318    Val.setIsSigned(NewSign);
319
320    // If the input was signed and negative and the output is
321    // unsigned, don't bother to warn: this is implementation-defined
322    // behavior.
323    // FIXME: Introduce a second, default-ignored warning for this case?
324  } else if (NewWidth < Val.getBitWidth()) {
325    // If this is a truncation, check for overflow.
326    llvm::APSInt ConvVal(Val);
327    ConvVal.trunc(NewWidth);
328    ConvVal.setIsSigned(NewSign);
329    ConvVal.extend(Val.getBitWidth());
330    ConvVal.setIsSigned(Val.isSigned());
331    if (ConvVal != Val)
332      Diag(Loc, DiagID) << Val.toString(10) << ConvVal.toString(10);
333
334    // Regardless of whether a diagnostic was emitted, really do the
335    // truncation.
336    Val.trunc(NewWidth);
337    Val.setIsSigned(NewSign);
338  } else if (NewSign != Val.isSigned()) {
339    // Convert the sign to match the sign of the condition.  This can cause
340    // overflow as well: unsigned(INTMIN)
341    // We don't diagnose this overflow, because it is implementation-defined
342    // behavior.
343    // FIXME: Introduce a second, default-ignored warning for this case?
344    llvm::APSInt OldVal(Val);
345    Val.setIsSigned(NewSign);
346  }
347}
348
349namespace {
350  struct CaseCompareFunctor {
351    bool operator()(const std::pair<llvm::APSInt, CaseStmt*> &LHS,
352                    const llvm::APSInt &RHS) {
353      return LHS.first < RHS;
354    }
355    bool operator()(const std::pair<llvm::APSInt, CaseStmt*> &LHS,
356                    const std::pair<llvm::APSInt, CaseStmt*> &RHS) {
357      return LHS.first < RHS.first;
358    }
359    bool operator()(const llvm::APSInt &LHS,
360                    const std::pair<llvm::APSInt, CaseStmt*> &RHS) {
361      return LHS < RHS.first;
362    }
363  };
364}
365
366/// CmpCaseVals - Comparison predicate for sorting case values.
367///
368static bool CmpCaseVals(const std::pair<llvm::APSInt, CaseStmt*>& lhs,
369                        const std::pair<llvm::APSInt, CaseStmt*>& rhs) {
370  if (lhs.first < rhs.first)
371    return true;
372
373  if (lhs.first == rhs.first &&
374      lhs.second->getCaseLoc().getRawEncoding()
375       < rhs.second->getCaseLoc().getRawEncoding())
376    return true;
377  return false;
378}
379
380/// CmpEnumVals - Comparison predicate for sorting enumeration values.
381///
382static bool CmpEnumVals(const std::pair<llvm::APSInt, EnumConstantDecl*>& lhs,
383                        const std::pair<llvm::APSInt, EnumConstantDecl*>& rhs)
384{
385  return lhs.first < rhs.first;
386}
387
388/// EqEnumVals - Comparison preficate for uniqing enumeration values.
389///
390static bool EqEnumVals(const std::pair<llvm::APSInt, EnumConstantDecl*>& lhs,
391                       const std::pair<llvm::APSInt, EnumConstantDecl*>& rhs)
392{
393  return lhs.first == rhs.first;
394}
395
396/// GetTypeBeforeIntegralPromotion - Returns the pre-promotion type of
397/// potentially integral-promoted expression @p expr.
398static QualType GetTypeBeforeIntegralPromotion(const Expr* expr) {
399  const ImplicitCastExpr *ImplicitCast =
400      dyn_cast_or_null<ImplicitCastExpr>(expr);
401  if (ImplicitCast != NULL) {
402    const Expr *ExprBeforePromotion = ImplicitCast->getSubExpr();
403    QualType TypeBeforePromotion = ExprBeforePromotion->getType();
404    if (TypeBeforePromotion->isIntegralType()) {
405      return TypeBeforePromotion;
406    }
407  }
408  return expr->getType();
409}
410
411/// \brief Check (and possibly convert) the condition in a switch
412/// statement in C++.
413static bool CheckCXXSwitchCondition(Sema &S, SourceLocation SwitchLoc,
414                                    Expr *&CondExpr) {
415  if (CondExpr->isTypeDependent())
416    return false;
417
418  QualType CondType = CondExpr->getType();
419
420  // C++ 6.4.2.p2:
421  // The condition shall be of integral type, enumeration type, or of a class
422  // type for which a single conversion function to integral or enumeration
423  // type exists (12.3). If the condition is of class type, the condition is
424  // converted by calling that conversion function, and the result of the
425  // conversion is used in place of the original condition for the remainder
426  // of this section. Integral promotions are performed.
427
428  // Make sure that the condition expression has a complete type,
429  // otherwise we'll never find any conversions.
430  if (S.RequireCompleteType(SwitchLoc, CondType,
431                            PDiag(diag::err_switch_incomplete_class_type)
432                              << CondExpr->getSourceRange()))
433    return true;
434
435  llvm::SmallVector<CXXConversionDecl *, 4> ViableConversions;
436  llvm::SmallVector<CXXConversionDecl *, 4> ExplicitConversions;
437  if (const RecordType *RecordTy = CondType->getAs<RecordType>()) {
438    const UnresolvedSetImpl *Conversions
439      = cast<CXXRecordDecl>(RecordTy->getDecl())
440                                             ->getVisibleConversionFunctions();
441    for (UnresolvedSetImpl::iterator I = Conversions->begin(),
442           E = Conversions->end(); I != E; ++I) {
443      if (CXXConversionDecl *Conversion = dyn_cast<CXXConversionDecl>(*I))
444        if (Conversion->getConversionType().getNonReferenceType()
445              ->isIntegralType()) {
446          if (Conversion->isExplicit())
447            ExplicitConversions.push_back(Conversion);
448          else
449          ViableConversions.push_back(Conversion);
450        }
451    }
452
453    switch (ViableConversions.size()) {
454    case 0:
455      if (ExplicitConversions.size() == 1) {
456        // The user probably meant to invoke the given explicit
457        // conversion; use it.
458        QualType ConvTy
459          = ExplicitConversions[0]->getConversionType()
460                        .getNonReferenceType();
461        std::string TypeStr;
462        ConvTy.getAsStringInternal(TypeStr, S.Context.PrintingPolicy);
463
464        S.Diag(SwitchLoc, diag::err_switch_explicit_conversion)
465          << CondType << ConvTy << CondExpr->getSourceRange()
466          << CodeModificationHint::CreateInsertion(CondExpr->getLocStart(),
467                                         "static_cast<" + TypeStr + ">(")
468          << CodeModificationHint::CreateInsertion(
469                            S.PP.getLocForEndOfToken(CondExpr->getLocEnd()),
470                               ")");
471        S.Diag(ExplicitConversions[0]->getLocation(),
472             diag::note_switch_conversion)
473          << ConvTy->isEnumeralType() << ConvTy;
474
475        // If we aren't in a SFINAE context, build a call to the
476        // explicit conversion function.
477        if (S.isSFINAEContext())
478          return true;
479
480        CondExpr = S.BuildCXXMemberCallExpr(CondExpr, ExplicitConversions[0]);
481      }
482
483      // We'll complain below about a non-integral condition type.
484      break;
485
486    case 1:
487      // Apply this conversion.
488      CondExpr = S.BuildCXXMemberCallExpr(CondExpr, ViableConversions[0]);
489      break;
490
491    default:
492      S.Diag(SwitchLoc, diag::err_switch_multiple_conversions)
493        << CondType << CondExpr->getSourceRange();
494      for (unsigned I = 0, N = ViableConversions.size(); I != N; ++I) {
495        QualType ConvTy
496          = ViableConversions[I]->getConversionType().getNonReferenceType();
497        S.Diag(ViableConversions[I]->getLocation(),
498             diag::note_switch_conversion)
499          << ConvTy->isEnumeralType() << ConvTy;
500      }
501      return true;
502    }
503  }
504
505  return false;
506}
507
508/// ActOnSwitchBodyError - This is called if there is an error parsing the
509/// body of the switch stmt instead of ActOnFinishSwitchStmt.
510void Sema::ActOnSwitchBodyError(SourceLocation SwitchLoc, StmtArg Switch,
511                                StmtArg Body) {
512  // Keep the switch stack balanced.
513  assert(getSwitchStack().back() == (SwitchStmt*)Switch.get() &&
514         "switch stack missing push/pop!");
515  getSwitchStack().pop_back();
516}
517
518Action::OwningStmtResult
519Sema::ActOnFinishSwitchStmt(SourceLocation SwitchLoc, StmtArg Switch,
520                            StmtArg Body) {
521  Stmt *BodyStmt = Body.takeAs<Stmt>();
522
523  SwitchStmt *SS = getSwitchStack().back();
524  assert(SS == (SwitchStmt*)Switch.get() && "switch stack missing push/pop!");
525
526  SS->setBody(BodyStmt, SwitchLoc);
527  getSwitchStack().pop_back();
528
529  if (SS->getCond() == 0) {
530    SS->Destroy(Context);
531    return StmtError();
532  }
533
534  Expr *CondExpr = SS->getCond();
535  QualType CondTypeBeforePromotion =
536      GetTypeBeforeIntegralPromotion(CondExpr);
537
538  if (getLangOptions().CPlusPlus &&
539      CheckCXXSwitchCondition(*this, SwitchLoc, CondExpr))
540    return StmtError();
541
542  // C99 6.8.4.2p5 - Integer promotions are performed on the controlling expr.
543  UsualUnaryConversions(CondExpr);
544  QualType CondType = CondExpr->getType();
545  SS->setCond(CondExpr);
546
547  // C++ 6.4.2.p2:
548  // Integral promotions are performed (on the switch condition).
549  //
550  // A case value unrepresentable by the original switch condition
551  // type (before the promotion) doesn't make sense, even when it can
552  // be represented by the promoted type.  Therefore we need to find
553  // the pre-promotion type of the switch condition.
554  if (!CondExpr->isTypeDependent()) {
555    if (!CondType->isIntegerType()) { // C99 6.8.4.2p1
556      Diag(SwitchLoc, diag::err_typecheck_statement_requires_integer)
557          << CondType << CondExpr->getSourceRange();
558      return StmtError();
559    }
560
561    if (CondTypeBeforePromotion->isBooleanType()) {
562      // switch(bool_expr) {...} is often a programmer error, e.g.
563      //   switch(n && mask) { ... }  // Doh - should be "n & mask".
564      // One can always use an if statement instead of switch(bool_expr).
565      Diag(SwitchLoc, diag::warn_bool_switch_condition)
566          << CondExpr->getSourceRange();
567    }
568  }
569
570  // Get the bitwidth of the switched-on value before promotions.  We must
571  // convert the integer case values to this width before comparison.
572  bool HasDependentValue
573    = CondExpr->isTypeDependent() || CondExpr->isValueDependent();
574  unsigned CondWidth
575    = HasDependentValue? 0
576      : static_cast<unsigned>(Context.getTypeSize(CondTypeBeforePromotion));
577  bool CondIsSigned = CondTypeBeforePromotion->isSignedIntegerType();
578
579  // Accumulate all of the case values in a vector so that we can sort them
580  // and detect duplicates.  This vector contains the APInt for the case after
581  // it has been converted to the condition type.
582  typedef llvm::SmallVector<std::pair<llvm::APSInt, CaseStmt*>, 64> CaseValsTy;
583  CaseValsTy CaseVals;
584
585  // Keep track of any GNU case ranges we see.  The APSInt is the low value.
586  typedef std::vector<std::pair<llvm::APSInt, CaseStmt*> > CaseRangesTy;
587  CaseRangesTy CaseRanges;
588
589  DefaultStmt *TheDefaultStmt = 0;
590
591  bool CaseListIsErroneous = false;
592
593  for (SwitchCase *SC = SS->getSwitchCaseList(); SC && !HasDependentValue;
594       SC = SC->getNextSwitchCase()) {
595
596    if (DefaultStmt *DS = dyn_cast<DefaultStmt>(SC)) {
597      if (TheDefaultStmt) {
598        Diag(DS->getDefaultLoc(), diag::err_multiple_default_labels_defined);
599        Diag(TheDefaultStmt->getDefaultLoc(), diag::note_duplicate_case_prev);
600
601        // FIXME: Remove the default statement from the switch block so that
602        // we'll return a valid AST.  This requires recursing down the AST and
603        // finding it, not something we are set up to do right now.  For now,
604        // just lop the entire switch stmt out of the AST.
605        CaseListIsErroneous = true;
606      }
607      TheDefaultStmt = DS;
608
609    } else {
610      CaseStmt *CS = cast<CaseStmt>(SC);
611
612      // We already verified that the expression has a i-c-e value (C99
613      // 6.8.4.2p3) - get that value now.
614      Expr *Lo = CS->getLHS();
615
616      if (Lo->isTypeDependent() || Lo->isValueDependent()) {
617        HasDependentValue = true;
618        break;
619      }
620
621      llvm::APSInt LoVal = Lo->EvaluateAsInt(Context);
622
623      // Convert the value to the same width/sign as the condition.
624      ConvertIntegerToTypeWarnOnOverflow(LoVal, CondWidth, CondIsSigned,
625                                         CS->getLHS()->getLocStart(),
626                                         diag::warn_case_value_overflow);
627
628      // If the LHS is not the same type as the condition, insert an implicit
629      // cast.
630      ImpCastExprToType(Lo, CondType, CastExpr::CK_IntegralCast);
631      CS->setLHS(Lo);
632
633      // If this is a case range, remember it in CaseRanges, otherwise CaseVals.
634      if (CS->getRHS()) {
635        if (CS->getRHS()->isTypeDependent() ||
636            CS->getRHS()->isValueDependent()) {
637          HasDependentValue = true;
638          break;
639        }
640        CaseRanges.push_back(std::make_pair(LoVal, CS));
641      } else
642        CaseVals.push_back(std::make_pair(LoVal, CS));
643    }
644  }
645
646  if (!HasDependentValue) {
647    // Sort all the scalar case values so we can easily detect duplicates.
648    std::stable_sort(CaseVals.begin(), CaseVals.end(), CmpCaseVals);
649
650    if (!CaseVals.empty()) {
651      for (unsigned i = 0, e = CaseVals.size()-1; i != e; ++i) {
652        if (CaseVals[i].first == CaseVals[i+1].first) {
653          // If we have a duplicate, report it.
654          Diag(CaseVals[i+1].second->getLHS()->getLocStart(),
655               diag::err_duplicate_case) << CaseVals[i].first.toString(10);
656          Diag(CaseVals[i].second->getLHS()->getLocStart(),
657               diag::note_duplicate_case_prev);
658          // FIXME: We really want to remove the bogus case stmt from the
659          // substmt, but we have no way to do this right now.
660          CaseListIsErroneous = true;
661        }
662      }
663    }
664
665    // Detect duplicate case ranges, which usually don't exist at all in
666    // the first place.
667    if (!CaseRanges.empty()) {
668      // Sort all the case ranges by their low value so we can easily detect
669      // overlaps between ranges.
670      std::stable_sort(CaseRanges.begin(), CaseRanges.end());
671
672      // Scan the ranges, computing the high values and removing empty ranges.
673      std::vector<llvm::APSInt> HiVals;
674      for (unsigned i = 0, e = CaseRanges.size(); i != e; ++i) {
675        CaseStmt *CR = CaseRanges[i].second;
676        Expr *Hi = CR->getRHS();
677        llvm::APSInt HiVal = Hi->EvaluateAsInt(Context);
678
679        // Convert the value to the same width/sign as the condition.
680        ConvertIntegerToTypeWarnOnOverflow(HiVal, CondWidth, CondIsSigned,
681                                           CR->getRHS()->getLocStart(),
682                                           diag::warn_case_value_overflow);
683
684        // If the LHS is not the same type as the condition, insert an implicit
685        // cast.
686        ImpCastExprToType(Hi, CondType, CastExpr::CK_IntegralCast);
687        CR->setRHS(Hi);
688
689        // If the low value is bigger than the high value, the case is empty.
690        if (CaseRanges[i].first > HiVal) {
691          Diag(CR->getLHS()->getLocStart(), diag::warn_case_empty_range)
692            << SourceRange(CR->getLHS()->getLocStart(),
693                           CR->getRHS()->getLocEnd());
694          CaseRanges.erase(CaseRanges.begin()+i);
695          --i, --e;
696          continue;
697        }
698        HiVals.push_back(HiVal);
699      }
700
701      // Rescan the ranges, looking for overlap with singleton values and other
702      // ranges.  Since the range list is sorted, we only need to compare case
703      // ranges with their neighbors.
704      for (unsigned i = 0, e = CaseRanges.size(); i != e; ++i) {
705        llvm::APSInt &CRLo = CaseRanges[i].first;
706        llvm::APSInt &CRHi = HiVals[i];
707        CaseStmt *CR = CaseRanges[i].second;
708
709        // Check to see whether the case range overlaps with any
710        // singleton cases.
711        CaseStmt *OverlapStmt = 0;
712        llvm::APSInt OverlapVal(32);
713
714        // Find the smallest value >= the lower bound.  If I is in the
715        // case range, then we have overlap.
716        CaseValsTy::iterator I = std::lower_bound(CaseVals.begin(),
717                                                  CaseVals.end(), CRLo,
718                                                  CaseCompareFunctor());
719        if (I != CaseVals.end() && I->first < CRHi) {
720          OverlapVal  = I->first;   // Found overlap with scalar.
721          OverlapStmt = I->second;
722        }
723
724        // Find the smallest value bigger than the upper bound.
725        I = std::upper_bound(I, CaseVals.end(), CRHi, CaseCompareFunctor());
726        if (I != CaseVals.begin() && (I-1)->first >= CRLo) {
727          OverlapVal  = (I-1)->first;      // Found overlap with scalar.
728          OverlapStmt = (I-1)->second;
729        }
730
731        // Check to see if this case stmt overlaps with the subsequent
732        // case range.
733        if (i && CRLo <= HiVals[i-1]) {
734          OverlapVal  = HiVals[i-1];       // Found overlap with range.
735          OverlapStmt = CaseRanges[i-1].second;
736        }
737
738        if (OverlapStmt) {
739          // If we have a duplicate, report it.
740          Diag(CR->getLHS()->getLocStart(), diag::err_duplicate_case)
741            << OverlapVal.toString(10);
742          Diag(OverlapStmt->getLHS()->getLocStart(),
743               diag::note_duplicate_case_prev);
744          // FIXME: We really want to remove the bogus case stmt from the
745          // substmt, but we have no way to do this right now.
746          CaseListIsErroneous = true;
747        }
748      }
749    }
750
751    // Check to see if switch is over an Enum and handles all of its
752    // values
753    const EnumType* ET = CondTypeBeforePromotion->getAs<EnumType>();
754    // If switch has default case, then ignore it.
755    if (!CaseListIsErroneous && !TheDefaultStmt && ET) {
756      const EnumDecl *ED = ET->getDecl();
757      typedef llvm::SmallVector<std::pair<llvm::APSInt, EnumConstantDecl*>, 64> EnumValsTy;
758      EnumValsTy EnumVals;
759
760      // Gather all enum values, set their type and sort them, allowing easier comparison
761      // with CaseVals.
762      for (EnumDecl::enumerator_iterator EDI = ED->enumerator_begin(); EDI != ED->enumerator_end(); EDI++) {
763        llvm::APSInt Val = (*EDI)->getInitVal();
764        if(Val.getBitWidth() < CondWidth)
765          Val.extend(CondWidth);
766        Val.setIsSigned(CondIsSigned);
767        EnumVals.push_back(std::make_pair(Val, (*EDI)));
768      }
769      std::stable_sort(EnumVals.begin(), EnumVals.end(), CmpEnumVals);
770      EnumValsTy::iterator EIend = std::unique(EnumVals.begin(), EnumVals.end(), EqEnumVals);
771      // See which case values aren't in enum
772      EnumValsTy::const_iterator EI = EnumVals.begin();
773      for (CaseValsTy::const_iterator CI = CaseVals.begin(); CI != CaseVals.end(); CI++) {
774        while (EI != EIend && EI->first < CI->first)
775          EI++;
776        if (EI == EIend || EI->first > CI->first)
777            Diag(CI->second->getLHS()->getExprLoc(), diag::not_in_enum) << ED->getDeclName();
778      }
779      // See which of case ranges aren't in enum
780      EI = EnumVals.begin();
781      for (CaseRangesTy::const_iterator RI = CaseRanges.begin(); RI != CaseRanges.end() && EI != EIend; RI++) {
782        while (EI != EIend && EI->first < RI->first)
783          EI++;
784
785        if (EI == EIend || EI->first != RI->first) {
786          Diag(RI->second->getLHS()->getExprLoc(), diag::not_in_enum) << ED->getDeclName();
787        }
788
789        llvm::APSInt Hi = RI->second->getRHS()->EvaluateAsInt(Context);
790        while (EI != EIend && EI->first < Hi)
791          EI++;
792        if (EI == EIend || EI->first != Hi)
793          Diag(RI->second->getRHS()->getExprLoc(), diag::not_in_enum) << ED->getDeclName();
794      }
795      //Check which enum vals aren't in switch
796      CaseValsTy::const_iterator CI = CaseVals.begin();
797      CaseRangesTy::const_iterator RI = CaseRanges.begin();
798      EI = EnumVals.begin();
799      for (; EI != EIend; EI++) {
800        //Drop unneeded case values
801        llvm::APSInt CIVal;
802        while (CI != CaseVals.end() && CI->first < EI->first)
803          CI++;
804
805        if (CI != CaseVals.end() && CI->first == EI->first)
806          continue;
807
808        //Drop unneeded case ranges
809        for (; RI != CaseRanges.end(); RI++) {
810          llvm::APSInt Hi = RI->second->getRHS()->EvaluateAsInt(Context);
811          if (EI->first <= Hi)
812            break;
813        }
814
815        if (RI == CaseRanges.end() || EI->first < RI->first)
816          Diag(CondExpr->getExprLoc(), diag::warn_missing_cases) << EI->second->getDeclName();
817      }
818    }
819  }
820
821  // FIXME: If the case list was broken is some way, we don't have a good system
822  // to patch it up.  Instead, just return the whole substmt as broken.
823  if (CaseListIsErroneous)
824    return StmtError();
825
826  Switch.release();
827  return Owned(SS);
828}
829
830Action::OwningStmtResult
831Sema::ActOnWhileStmt(SourceLocation WhileLoc, FullExprArg Cond,
832                     DeclPtrTy CondVar, StmtArg Body) {
833  OwningExprResult CondResult(Cond.release());
834
835  VarDecl *ConditionVar = 0;
836  if (CondVar.get()) {
837    ConditionVar = CondVar.getAs<VarDecl>();
838    CondResult = CheckConditionVariable(ConditionVar);
839    if (CondResult.isInvalid())
840      return StmtError();
841  }
842  Expr *ConditionExpr = CondResult.takeAs<Expr>();
843  if (!ConditionExpr)
844    return StmtError();
845
846  if (CheckBooleanCondition(ConditionExpr, WhileLoc)) {
847    CondResult = ConditionExpr;
848    return StmtError();
849  }
850
851  Stmt *bodyStmt = Body.takeAs<Stmt>();
852  DiagnoseUnusedExprResult(bodyStmt);
853
854  CondResult.release();
855  return Owned(new (Context) WhileStmt(ConditionVar, ConditionExpr, bodyStmt,
856                                       WhileLoc));
857}
858
859Action::OwningStmtResult
860Sema::ActOnDoStmt(SourceLocation DoLoc, StmtArg Body,
861                  SourceLocation WhileLoc, SourceLocation CondLParen,
862                  ExprArg Cond, SourceLocation CondRParen) {
863  Expr *condExpr = Cond.takeAs<Expr>();
864  assert(condExpr && "ActOnDoStmt(): missing expression");
865
866  if (CheckBooleanCondition(condExpr, DoLoc)) {
867    Cond = condExpr;
868    return StmtError();
869  }
870
871  Stmt *bodyStmt = Body.takeAs<Stmt>();
872  DiagnoseUnusedExprResult(bodyStmt);
873
874  Cond.release();
875  return Owned(new (Context) DoStmt(bodyStmt, condExpr, DoLoc,
876                                    WhileLoc, CondRParen));
877}
878
879Action::OwningStmtResult
880Sema::ActOnForStmt(SourceLocation ForLoc, SourceLocation LParenLoc,
881                   StmtArg first, FullExprArg second, DeclPtrTy secondVar,
882                   FullExprArg third,
883                   SourceLocation RParenLoc, StmtArg body) {
884  Stmt *First  = static_cast<Stmt*>(first.get());
885
886  if (!getLangOptions().CPlusPlus) {
887    if (DeclStmt *DS = dyn_cast_or_null<DeclStmt>(First)) {
888      // C99 6.8.5p3: The declaration part of a 'for' statement shall only
889      // declare identifiers for objects having storage class 'auto' or
890      // 'register'.
891      for (DeclStmt::decl_iterator DI=DS->decl_begin(), DE=DS->decl_end();
892           DI!=DE; ++DI) {
893        VarDecl *VD = dyn_cast<VarDecl>(*DI);
894        if (VD && VD->isBlockVarDecl() && !VD->hasLocalStorage())
895          VD = 0;
896        if (VD == 0)
897          Diag((*DI)->getLocation(), diag::err_non_variable_decl_in_for);
898        // FIXME: mark decl erroneous!
899      }
900    }
901  }
902
903  OwningExprResult SecondResult(second.release());
904  VarDecl *ConditionVar = 0;
905  if (secondVar.get()) {
906    ConditionVar = secondVar.getAs<VarDecl>();
907    SecondResult = CheckConditionVariable(ConditionVar);
908    if (SecondResult.isInvalid())
909      return StmtError();
910  }
911
912  Expr *Second = SecondResult.takeAs<Expr>();
913  if (Second && CheckBooleanCondition(Second, ForLoc)) {
914    SecondResult = Second;
915    return StmtError();
916  }
917
918  Expr *Third  = third.release().takeAs<Expr>();
919  Stmt *Body  = static_cast<Stmt*>(body.get());
920
921  DiagnoseUnusedExprResult(First);
922  DiagnoseUnusedExprResult(Third);
923  DiagnoseUnusedExprResult(Body);
924
925  first.release();
926  body.release();
927  return Owned(new (Context) ForStmt(First, Second, ConditionVar, Third, Body,
928                                     ForLoc, LParenLoc, RParenLoc));
929}
930
931Action::OwningStmtResult
932Sema::ActOnObjCForCollectionStmt(SourceLocation ForLoc,
933                                 SourceLocation LParenLoc,
934                                 StmtArg first, ExprArg second,
935                                 SourceLocation RParenLoc, StmtArg body) {
936  Stmt *First  = static_cast<Stmt*>(first.get());
937  Expr *Second = static_cast<Expr*>(second.get());
938  Stmt *Body  = static_cast<Stmt*>(body.get());
939  if (First) {
940    QualType FirstType;
941    if (DeclStmt *DS = dyn_cast<DeclStmt>(First)) {
942      if (!DS->isSingleDecl())
943        return StmtError(Diag((*DS->decl_begin())->getLocation(),
944                         diag::err_toomany_element_decls));
945
946      Decl *D = DS->getSingleDecl();
947      FirstType = cast<ValueDecl>(D)->getType();
948      // C99 6.8.5p3: The declaration part of a 'for' statement shall only
949      // declare identifiers for objects having storage class 'auto' or
950      // 'register'.
951      VarDecl *VD = cast<VarDecl>(D);
952      if (VD->isBlockVarDecl() && !VD->hasLocalStorage())
953        return StmtError(Diag(VD->getLocation(),
954                              diag::err_non_variable_decl_in_for));
955    } else {
956      if (cast<Expr>(First)->isLvalue(Context) != Expr::LV_Valid)
957        return StmtError(Diag(First->getLocStart(),
958                   diag::err_selector_element_not_lvalue)
959          << First->getSourceRange());
960
961      FirstType = static_cast<Expr*>(First)->getType();
962    }
963    if (!FirstType->isObjCObjectPointerType() &&
964        !FirstType->isBlockPointerType())
965        Diag(ForLoc, diag::err_selector_element_type)
966          << FirstType << First->getSourceRange();
967  }
968  if (Second) {
969    DefaultFunctionArrayLvalueConversion(Second);
970    QualType SecondType = Second->getType();
971    if (!SecondType->isObjCObjectPointerType())
972      Diag(ForLoc, diag::err_collection_expr_type)
973        << SecondType << Second->getSourceRange();
974  }
975  first.release();
976  second.release();
977  body.release();
978  return Owned(new (Context) ObjCForCollectionStmt(First, Second, Body,
979                                                   ForLoc, RParenLoc));
980}
981
982Action::OwningStmtResult
983Sema::ActOnGotoStmt(SourceLocation GotoLoc, SourceLocation LabelLoc,
984                    IdentifierInfo *LabelII) {
985  // Look up the record for this label identifier.
986  LabelStmt *&LabelDecl = getLabelMap()[LabelII];
987
988  // If we haven't seen this label yet, create a forward reference.
989  if (LabelDecl == 0)
990    LabelDecl = new (Context) LabelStmt(LabelLoc, LabelII, 0);
991
992  return Owned(new (Context) GotoStmt(LabelDecl, GotoLoc, LabelLoc));
993}
994
995Action::OwningStmtResult
996Sema::ActOnIndirectGotoStmt(SourceLocation GotoLoc, SourceLocation StarLoc,
997                            ExprArg DestExp) {
998  // Convert operand to void*
999  Expr* E = DestExp.takeAs<Expr>();
1000  if (!E->isTypeDependent()) {
1001    QualType ETy = E->getType();
1002    QualType DestTy = Context.getPointerType(Context.VoidTy.withConst());
1003    AssignConvertType ConvTy =
1004      CheckSingleAssignmentConstraints(DestTy, E);
1005    if (DiagnoseAssignmentResult(ConvTy, StarLoc, DestTy, ETy, E, AA_Passing))
1006      return StmtError();
1007  }
1008  return Owned(new (Context) IndirectGotoStmt(GotoLoc, StarLoc, E));
1009}
1010
1011Action::OwningStmtResult
1012Sema::ActOnContinueStmt(SourceLocation ContinueLoc, Scope *CurScope) {
1013  Scope *S = CurScope->getContinueParent();
1014  if (!S) {
1015    // C99 6.8.6.2p1: A break shall appear only in or as a loop body.
1016    return StmtError(Diag(ContinueLoc, diag::err_continue_not_in_loop));
1017  }
1018
1019  return Owned(new (Context) ContinueStmt(ContinueLoc));
1020}
1021
1022Action::OwningStmtResult
1023Sema::ActOnBreakStmt(SourceLocation BreakLoc, Scope *CurScope) {
1024  Scope *S = CurScope->getBreakParent();
1025  if (!S) {
1026    // C99 6.8.6.3p1: A break shall appear only in or as a switch/loop body.
1027    return StmtError(Diag(BreakLoc, diag::err_break_not_in_loop_or_switch));
1028  }
1029
1030  return Owned(new (Context) BreakStmt(BreakLoc));
1031}
1032
1033/// ActOnBlockReturnStmt - Utility routine to figure out block's return type.
1034///
1035Action::OwningStmtResult
1036Sema::ActOnBlockReturnStmt(SourceLocation ReturnLoc, Expr *RetValExp) {
1037  // If this is the first return we've seen in the block, infer the type of
1038  // the block from it.
1039  BlockScopeInfo *CurBlock = getCurBlock();
1040  if (CurBlock->ReturnType.isNull()) {
1041    if (RetValExp) {
1042      // Don't call UsualUnaryConversions(), since we don't want to do
1043      // integer promotions here.
1044      DefaultFunctionArrayLvalueConversion(RetValExp);
1045      CurBlock->ReturnType = RetValExp->getType();
1046      if (BlockDeclRefExpr *CDRE = dyn_cast<BlockDeclRefExpr>(RetValExp)) {
1047        // We have to remove a 'const' added to copied-in variable which was
1048        // part of the implementation spec. and not the actual qualifier for
1049        // the variable.
1050        if (CDRE->isConstQualAdded())
1051           CurBlock->ReturnType.removeConst();
1052      }
1053    } else
1054      CurBlock->ReturnType = Context.VoidTy;
1055  }
1056  QualType FnRetType = CurBlock->ReturnType;
1057
1058  if (CurBlock->TheDecl->hasAttr<NoReturnAttr>()) {
1059    Diag(ReturnLoc, diag::err_noreturn_block_has_return_expr)
1060      << getCurFunctionOrMethodDecl()->getDeclName();
1061    return StmtError();
1062  }
1063
1064  // Otherwise, verify that this result type matches the previous one.  We are
1065  // pickier with blocks than for normal functions because we don't have GCC
1066  // compatibility to worry about here.
1067  if (CurBlock->ReturnType->isVoidType()) {
1068    if (RetValExp) {
1069      Diag(ReturnLoc, diag::err_return_block_has_expr);
1070      RetValExp->Destroy(Context);
1071      RetValExp = 0;
1072    }
1073    return Owned(new (Context) ReturnStmt(ReturnLoc, RetValExp));
1074  }
1075
1076  if (!RetValExp)
1077    return StmtError(Diag(ReturnLoc, diag::err_block_return_missing_expr));
1078
1079  if (!FnRetType->isDependentType() && !RetValExp->isTypeDependent()) {
1080    // we have a non-void block with an expression, continue checking
1081
1082    // C99 6.8.6.4p3(136): The return statement is not an assignment. The
1083    // overlap restriction of subclause 6.5.16.1 does not apply to the case of
1084    // function return.
1085
1086    // In C++ the return statement is handled via a copy initialization.
1087    // the C version of which boils down to CheckSingleAssignmentConstraints.
1088    OwningExprResult Res = PerformCopyInitialization(
1089                             InitializedEntity::InitializeResult(ReturnLoc,
1090                                                                 FnRetType),
1091                             SourceLocation(),
1092                             Owned(RetValExp));
1093    if (Res.isInvalid()) {
1094      // FIXME: Cleanup temporaries here, anyway?
1095      return StmtError();
1096    }
1097
1098    RetValExp = Res.takeAs<Expr>();
1099    if (RetValExp)
1100      CheckReturnStackAddr(RetValExp, FnRetType, ReturnLoc);
1101  }
1102
1103  return Owned(new (Context) ReturnStmt(ReturnLoc, RetValExp));
1104}
1105
1106/// IsReturnCopyElidable - Whether returning @p RetExpr from a function that
1107/// returns a @p RetType fulfills the criteria for copy elision (C++0x 12.8p15).
1108static bool IsReturnCopyElidable(ASTContext &Ctx, QualType RetType,
1109                                 Expr *RetExpr) {
1110  QualType ExprType = RetExpr->getType();
1111  // - in a return statement in a function with ...
1112  // ... a class return type ...
1113  if (!RetType->isRecordType())
1114    return false;
1115  // ... the same cv-unqualified type as the function return type ...
1116  if (!Ctx.hasSameUnqualifiedType(RetType, ExprType))
1117    return false;
1118  // ... the expression is the name of a non-volatile automatic object ...
1119  // We ignore parentheses here.
1120  // FIXME: Is this compliant?
1121  const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(RetExpr->IgnoreParens());
1122  if (!DR)
1123    return false;
1124  const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl());
1125  if (!VD)
1126    return false;
1127  return VD->hasLocalStorage() && !VD->getType()->isReferenceType()
1128    && !VD->getType().isVolatileQualified();
1129}
1130
1131Action::OwningStmtResult
1132Sema::ActOnReturnStmt(SourceLocation ReturnLoc, ExprArg rex) {
1133  Expr *RetValExp = rex.takeAs<Expr>();
1134  if (getCurBlock())
1135    return ActOnBlockReturnStmt(ReturnLoc, RetValExp);
1136
1137  QualType FnRetType;
1138  if (const FunctionDecl *FD = getCurFunctionDecl()) {
1139    FnRetType = FD->getResultType();
1140    if (FD->hasAttr<NoReturnAttr>() ||
1141        FD->getType()->getAs<FunctionType>()->getNoReturnAttr())
1142      Diag(ReturnLoc, diag::warn_noreturn_function_has_return_expr)
1143        << getCurFunctionOrMethodDecl()->getDeclName();
1144  } else if (ObjCMethodDecl *MD = getCurMethodDecl())
1145    FnRetType = MD->getResultType();
1146  else // If we don't have a function/method context, bail.
1147    return StmtError();
1148
1149  if (FnRetType->isVoidType()) {
1150    if (RetValExp && !RetValExp->isTypeDependent()) {
1151      // C99 6.8.6.4p1 (ext_ since GCC warns)
1152      unsigned D = diag::ext_return_has_expr;
1153      if (RetValExp->getType()->isVoidType())
1154        D = diag::ext_return_has_void_expr;
1155
1156      // return (some void expression); is legal in C++.
1157      if (D != diag::ext_return_has_void_expr ||
1158          !getLangOptions().CPlusPlus) {
1159        NamedDecl *CurDecl = getCurFunctionOrMethodDecl();
1160        Diag(ReturnLoc, D)
1161          << CurDecl->getDeclName() << isa<ObjCMethodDecl>(CurDecl)
1162          << RetValExp->getSourceRange();
1163      }
1164
1165      RetValExp = MaybeCreateCXXExprWithTemporaries(RetValExp);
1166    }
1167    return Owned(new (Context) ReturnStmt(ReturnLoc, RetValExp));
1168  }
1169
1170  if (!RetValExp && !FnRetType->isDependentType()) {
1171    unsigned DiagID = diag::warn_return_missing_expr;  // C90 6.6.6.4p4
1172    // C99 6.8.6.4p1 (ext_ since GCC warns)
1173    if (getLangOptions().C99) DiagID = diag::ext_return_missing_expr;
1174
1175    if (FunctionDecl *FD = getCurFunctionDecl())
1176      Diag(ReturnLoc, DiagID) << FD->getIdentifier() << 0/*fn*/;
1177    else
1178      Diag(ReturnLoc, DiagID) << getCurMethodDecl()->getDeclName() << 1/*meth*/;
1179    return Owned(new (Context) ReturnStmt(ReturnLoc, (Expr*)0));
1180  }
1181
1182  if (!FnRetType->isDependentType() && !RetValExp->isTypeDependent()) {
1183    // we have a non-void function with an expression, continue checking
1184
1185    // C99 6.8.6.4p3(136): The return statement is not an assignment. The
1186    // overlap restriction of subclause 6.5.16.1 does not apply to the case of
1187    // function return.
1188
1189    // C++0x 12.8p15: When certain criteria are met, an implementation is
1190    //   allowed to omit the copy construction of a class object, [...]
1191    //   - in a return statement in a function with a class return type, when
1192    //     the expression is the name of a non-volatile automatic object with
1193    //     the same cv-unqualified type as the function return type, the copy
1194    //     operation can be omitted [...]
1195    // C++0x 12.8p16: When the criteria for elision of a copy operation are met
1196    //   and the object to be copied is designated by an lvalue, overload
1197    //   resolution to select the constructor for the copy is first performed
1198    //   as if the object were designated by an rvalue.
1199    // Note that we only compute Elidable if we're in C++0x, since we don't
1200    // care otherwise.
1201    bool Elidable = getLangOptions().CPlusPlus0x ?
1202                      IsReturnCopyElidable(Context, FnRetType, RetValExp) :
1203                      false;
1204    // FIXME: Elidable
1205    (void)Elidable;
1206
1207    // In C++ the return statement is handled via a copy initialization.
1208    // the C version of which boils down to CheckSingleAssignmentConstraints.
1209    OwningExprResult Res = PerformCopyInitialization(
1210                             InitializedEntity::InitializeResult(ReturnLoc,
1211                                                                 FnRetType),
1212                             SourceLocation(),
1213                             Owned(RetValExp));
1214    if (Res.isInvalid()) {
1215      // FIXME: Cleanup temporaries here, anyway?
1216      return StmtError();
1217    }
1218
1219    RetValExp = Res.takeAs<Expr>();
1220    if (RetValExp)
1221      CheckReturnStackAddr(RetValExp, FnRetType, ReturnLoc);
1222  }
1223
1224  if (RetValExp)
1225    RetValExp = MaybeCreateCXXExprWithTemporaries(RetValExp);
1226  return Owned(new (Context) ReturnStmt(ReturnLoc, RetValExp));
1227}
1228
1229/// CheckAsmLValue - GNU C has an extremely ugly extension whereby they silently
1230/// ignore "noop" casts in places where an lvalue is required by an inline asm.
1231/// We emulate this behavior when -fheinous-gnu-extensions is specified, but
1232/// provide a strong guidance to not use it.
1233///
1234/// This method checks to see if the argument is an acceptable l-value and
1235/// returns false if it is a case we can handle.
1236static bool CheckAsmLValue(const Expr *E, Sema &S) {
1237  // Type dependent expressions will be checked during instantiation.
1238  if (E->isTypeDependent())
1239    return false;
1240
1241  if (E->isLvalue(S.Context) == Expr::LV_Valid)
1242    return false;  // Cool, this is an lvalue.
1243
1244  // Okay, this is not an lvalue, but perhaps it is the result of a cast that we
1245  // are supposed to allow.
1246  const Expr *E2 = E->IgnoreParenNoopCasts(S.Context);
1247  if (E != E2 && E2->isLvalue(S.Context) == Expr::LV_Valid) {
1248    if (!S.getLangOptions().HeinousExtensions)
1249      S.Diag(E2->getLocStart(), diag::err_invalid_asm_cast_lvalue)
1250        << E->getSourceRange();
1251    else
1252      S.Diag(E2->getLocStart(), diag::warn_invalid_asm_cast_lvalue)
1253        << E->getSourceRange();
1254    // Accept, even if we emitted an error diagnostic.
1255    return false;
1256  }
1257
1258  // None of the above, just randomly invalid non-lvalue.
1259  return true;
1260}
1261
1262
1263Sema::OwningStmtResult Sema::ActOnAsmStmt(SourceLocation AsmLoc,
1264                                          bool IsSimple,
1265                                          bool IsVolatile,
1266                                          unsigned NumOutputs,
1267                                          unsigned NumInputs,
1268                                          IdentifierInfo **Names,
1269                                          MultiExprArg constraints,
1270                                          MultiExprArg exprs,
1271                                          ExprArg asmString,
1272                                          MultiExprArg clobbers,
1273                                          SourceLocation RParenLoc,
1274                                          bool MSAsm) {
1275  unsigned NumClobbers = clobbers.size();
1276  StringLiteral **Constraints =
1277    reinterpret_cast<StringLiteral**>(constraints.get());
1278  Expr **Exprs = reinterpret_cast<Expr **>(exprs.get());
1279  StringLiteral *AsmString = cast<StringLiteral>((Expr *)asmString.get());
1280  StringLiteral **Clobbers = reinterpret_cast<StringLiteral**>(clobbers.get());
1281
1282  llvm::SmallVector<TargetInfo::ConstraintInfo, 4> OutputConstraintInfos;
1283
1284  // The parser verifies that there is a string literal here.
1285  if (AsmString->isWide())
1286    return StmtError(Diag(AsmString->getLocStart(),diag::err_asm_wide_character)
1287      << AsmString->getSourceRange());
1288
1289  for (unsigned i = 0; i != NumOutputs; i++) {
1290    StringLiteral *Literal = Constraints[i];
1291    if (Literal->isWide())
1292      return StmtError(Diag(Literal->getLocStart(),diag::err_asm_wide_character)
1293        << Literal->getSourceRange());
1294
1295    llvm::StringRef OutputName;
1296    if (Names[i])
1297      OutputName = Names[i]->getName();
1298
1299    TargetInfo::ConstraintInfo Info(Literal->getString(), OutputName);
1300    if (!Context.Target.validateOutputConstraint(Info))
1301      return StmtError(Diag(Literal->getLocStart(),
1302                            diag::err_asm_invalid_output_constraint)
1303                       << Info.getConstraintStr());
1304
1305    // Check that the output exprs are valid lvalues.
1306    Expr *OutputExpr = Exprs[i];
1307    if (CheckAsmLValue(OutputExpr, *this)) {
1308      return StmtError(Diag(OutputExpr->getLocStart(),
1309                  diag::err_asm_invalid_lvalue_in_output)
1310        << OutputExpr->getSourceRange());
1311    }
1312
1313    OutputConstraintInfos.push_back(Info);
1314  }
1315
1316  llvm::SmallVector<TargetInfo::ConstraintInfo, 4> InputConstraintInfos;
1317
1318  for (unsigned i = NumOutputs, e = NumOutputs + NumInputs; i != e; i++) {
1319    StringLiteral *Literal = Constraints[i];
1320    if (Literal->isWide())
1321      return StmtError(Diag(Literal->getLocStart(),diag::err_asm_wide_character)
1322        << Literal->getSourceRange());
1323
1324    llvm::StringRef InputName;
1325    if (Names[i])
1326      InputName = Names[i]->getName();
1327
1328    TargetInfo::ConstraintInfo Info(Literal->getString(), InputName);
1329    if (!Context.Target.validateInputConstraint(OutputConstraintInfos.data(),
1330                                                NumOutputs, Info)) {
1331      return StmtError(Diag(Literal->getLocStart(),
1332                            diag::err_asm_invalid_input_constraint)
1333                       << Info.getConstraintStr());
1334    }
1335
1336    Expr *InputExpr = Exprs[i];
1337
1338    // Only allow void types for memory constraints.
1339    if (Info.allowsMemory() && !Info.allowsRegister()) {
1340      if (CheckAsmLValue(InputExpr, *this))
1341        return StmtError(Diag(InputExpr->getLocStart(),
1342                              diag::err_asm_invalid_lvalue_in_input)
1343                         << Info.getConstraintStr()
1344                         << InputExpr->getSourceRange());
1345    }
1346
1347    if (Info.allowsRegister()) {
1348      if (InputExpr->getType()->isVoidType()) {
1349        return StmtError(Diag(InputExpr->getLocStart(),
1350                              diag::err_asm_invalid_type_in_input)
1351          << InputExpr->getType() << Info.getConstraintStr()
1352          << InputExpr->getSourceRange());
1353      }
1354    }
1355
1356    DefaultFunctionArrayLvalueConversion(Exprs[i]);
1357
1358    InputConstraintInfos.push_back(Info);
1359  }
1360
1361  // Check that the clobbers are valid.
1362  for (unsigned i = 0; i != NumClobbers; i++) {
1363    StringLiteral *Literal = Clobbers[i];
1364    if (Literal->isWide())
1365      return StmtError(Diag(Literal->getLocStart(),diag::err_asm_wide_character)
1366        << Literal->getSourceRange());
1367
1368    llvm::StringRef Clobber = Literal->getString();
1369
1370    if (!Context.Target.isValidGCCRegisterName(Clobber))
1371      return StmtError(Diag(Literal->getLocStart(),
1372                  diag::err_asm_unknown_register_name) << Clobber);
1373  }
1374
1375  constraints.release();
1376  exprs.release();
1377  asmString.release();
1378  clobbers.release();
1379  AsmStmt *NS =
1380    new (Context) AsmStmt(Context, AsmLoc, IsSimple, IsVolatile, MSAsm,
1381                          NumOutputs, NumInputs, Names, Constraints, Exprs,
1382                          AsmString, NumClobbers, Clobbers, RParenLoc);
1383  // Validate the asm string, ensuring it makes sense given the operands we
1384  // have.
1385  llvm::SmallVector<AsmStmt::AsmStringPiece, 8> Pieces;
1386  unsigned DiagOffs;
1387  if (unsigned DiagID = NS->AnalyzeAsmString(Pieces, Context, DiagOffs)) {
1388    Diag(getLocationOfStringLiteralByte(AsmString, DiagOffs), DiagID)
1389           << AsmString->getSourceRange();
1390    DeleteStmt(NS);
1391    return StmtError();
1392  }
1393
1394  // Validate tied input operands for type mismatches.
1395  for (unsigned i = 0, e = InputConstraintInfos.size(); i != e; ++i) {
1396    TargetInfo::ConstraintInfo &Info = InputConstraintInfos[i];
1397
1398    // If this is a tied constraint, verify that the output and input have
1399    // either exactly the same type, or that they are int/ptr operands with the
1400    // same size (int/long, int*/long, are ok etc).
1401    if (!Info.hasTiedOperand()) continue;
1402
1403    unsigned TiedTo = Info.getTiedOperand();
1404    Expr *OutputExpr = Exprs[TiedTo];
1405    Expr *InputExpr = Exprs[i+NumOutputs];
1406    QualType InTy = InputExpr->getType();
1407    QualType OutTy = OutputExpr->getType();
1408    if (Context.hasSameType(InTy, OutTy))
1409      continue;  // All types can be tied to themselves.
1410
1411    // Int/ptr operands have some special cases that we allow.
1412    if ((OutTy->isIntegerType() || OutTy->isPointerType()) &&
1413        (InTy->isIntegerType() || InTy->isPointerType())) {
1414
1415      // They are ok if they are the same size.  Tying void* to int is ok if
1416      // they are the same size, for example.  This also allows tying void* to
1417      // int*.
1418      uint64_t OutSize = Context.getTypeSize(OutTy);
1419      uint64_t InSize = Context.getTypeSize(InTy);
1420      if (OutSize == InSize)
1421        continue;
1422
1423      // If the smaller input/output operand is not mentioned in the asm string,
1424      // then we can promote it and the asm string won't notice.  Check this
1425      // case now.
1426      bool SmallerValueMentioned = false;
1427      for (unsigned p = 0, e = Pieces.size(); p != e; ++p) {
1428        AsmStmt::AsmStringPiece &Piece = Pieces[p];
1429        if (!Piece.isOperand()) continue;
1430
1431        // If this is a reference to the input and if the input was the smaller
1432        // one, then we have to reject this asm.
1433        if (Piece.getOperandNo() == i+NumOutputs) {
1434          if (InSize < OutSize) {
1435            SmallerValueMentioned = true;
1436            break;
1437          }
1438        }
1439
1440        // If this is a reference to the input and if the input was the smaller
1441        // one, then we have to reject this asm.
1442        if (Piece.getOperandNo() == TiedTo) {
1443          if (InSize > OutSize) {
1444            SmallerValueMentioned = true;
1445            break;
1446          }
1447        }
1448      }
1449
1450      // If the smaller value wasn't mentioned in the asm string, and if the
1451      // output was a register, just extend the shorter one to the size of the
1452      // larger one.
1453      if (!SmallerValueMentioned &&
1454          OutputConstraintInfos[TiedTo].allowsRegister())
1455        continue;
1456    }
1457
1458    Diag(InputExpr->getLocStart(),
1459         diag::err_asm_tying_incompatible_types)
1460      << InTy << OutTy << OutputExpr->getSourceRange()
1461      << InputExpr->getSourceRange();
1462    DeleteStmt(NS);
1463    return StmtError();
1464  }
1465
1466  return Owned(NS);
1467}
1468
1469Action::OwningStmtResult
1470Sema::ActOnObjCAtCatchStmt(SourceLocation AtLoc,
1471                           SourceLocation RParen, DeclPtrTy Parm,
1472                           StmtArg Body, StmtArg catchList) {
1473  Stmt *CatchList = catchList.takeAs<Stmt>();
1474  ParmVarDecl *PVD = cast_or_null<ParmVarDecl>(Parm.getAs<Decl>());
1475
1476  // PVD == 0 implies @catch(...).
1477  if (PVD) {
1478    // If we already know the decl is invalid, reject it.
1479    if (PVD->isInvalidDecl())
1480      return StmtError();
1481
1482    if (!PVD->getType()->isObjCObjectPointerType())
1483      return StmtError(Diag(PVD->getLocation(),
1484                       diag::err_catch_param_not_objc_type));
1485    if (PVD->getType()->isObjCQualifiedIdType())
1486      return StmtError(Diag(PVD->getLocation(),
1487                       diag::err_illegal_qualifiers_on_catch_parm));
1488  }
1489
1490  ObjCAtCatchStmt *CS = new (Context) ObjCAtCatchStmt(AtLoc, RParen,
1491    PVD, Body.takeAs<Stmt>(), CatchList);
1492  return Owned(CatchList ? CatchList : CS);
1493}
1494
1495Action::OwningStmtResult
1496Sema::ActOnObjCAtFinallyStmt(SourceLocation AtLoc, StmtArg Body) {
1497  return Owned(new (Context) ObjCAtFinallyStmt(AtLoc,
1498                                           static_cast<Stmt*>(Body.release())));
1499}
1500
1501Action::OwningStmtResult
1502Sema::ActOnObjCAtTryStmt(SourceLocation AtLoc,
1503                         StmtArg Try, StmtArg Catch, StmtArg Finally) {
1504  FunctionNeedsScopeChecking() = true;
1505  return Owned(new (Context) ObjCAtTryStmt(AtLoc, Try.takeAs<Stmt>(),
1506                                           Catch.takeAs<Stmt>(),
1507                                           Finally.takeAs<Stmt>()));
1508}
1509
1510Action::OwningStmtResult
1511Sema::ActOnObjCAtThrowStmt(SourceLocation AtLoc, ExprArg expr,Scope *CurScope) {
1512  Expr *ThrowExpr = expr.takeAs<Expr>();
1513  if (!ThrowExpr) {
1514    // @throw without an expression designates a rethrow (which much occur
1515    // in the context of an @catch clause).
1516    Scope *AtCatchParent = CurScope;
1517    while (AtCatchParent && !AtCatchParent->isAtCatchScope())
1518      AtCatchParent = AtCatchParent->getParent();
1519    if (!AtCatchParent)
1520      return StmtError(Diag(AtLoc, diag::error_rethrow_used_outside_catch));
1521  } else {
1522    QualType ThrowType = ThrowExpr->getType();
1523    // Make sure the expression type is an ObjC pointer or "void *".
1524    if (!ThrowType->isObjCObjectPointerType()) {
1525      const PointerType *PT = ThrowType->getAs<PointerType>();
1526      if (!PT || !PT->getPointeeType()->isVoidType())
1527        return StmtError(Diag(AtLoc, diag::error_objc_throw_expects_object)
1528                        << ThrowExpr->getType() << ThrowExpr->getSourceRange());
1529    }
1530  }
1531  return Owned(new (Context) ObjCAtThrowStmt(AtLoc, ThrowExpr));
1532}
1533
1534Action::OwningStmtResult
1535Sema::ActOnObjCAtSynchronizedStmt(SourceLocation AtLoc, ExprArg SynchExpr,
1536                                  StmtArg SynchBody) {
1537  FunctionNeedsScopeChecking() = true;
1538
1539  // Make sure the expression type is an ObjC pointer or "void *".
1540  Expr *SyncExpr = static_cast<Expr*>(SynchExpr.get());
1541  if (!SyncExpr->getType()->isObjCObjectPointerType()) {
1542    const PointerType *PT = SyncExpr->getType()->getAs<PointerType>();
1543    if (!PT || !PT->getPointeeType()->isVoidType())
1544      return StmtError(Diag(AtLoc, diag::error_objc_synchronized_expects_object)
1545                       << SyncExpr->getType() << SyncExpr->getSourceRange());
1546  }
1547
1548  return Owned(new (Context) ObjCAtSynchronizedStmt(AtLoc,
1549                                                    SynchExpr.takeAs<Stmt>(),
1550                                                    SynchBody.takeAs<Stmt>()));
1551}
1552
1553/// ActOnCXXCatchBlock - Takes an exception declaration and a handler block
1554/// and creates a proper catch handler from them.
1555Action::OwningStmtResult
1556Sema::ActOnCXXCatchBlock(SourceLocation CatchLoc, DeclPtrTy ExDecl,
1557                         StmtArg HandlerBlock) {
1558  // There's nothing to test that ActOnExceptionDecl didn't already test.
1559  return Owned(new (Context) CXXCatchStmt(CatchLoc,
1560                                  cast_or_null<VarDecl>(ExDecl.getAs<Decl>()),
1561                                          HandlerBlock.takeAs<Stmt>()));
1562}
1563
1564class TypeWithHandler {
1565  QualType t;
1566  CXXCatchStmt *stmt;
1567public:
1568  TypeWithHandler(const QualType &type, CXXCatchStmt *statement)
1569  : t(type), stmt(statement) {}
1570
1571  // An arbitrary order is fine as long as it places identical
1572  // types next to each other.
1573  bool operator<(const TypeWithHandler &y) const {
1574    if (t.getAsOpaquePtr() < y.t.getAsOpaquePtr())
1575      return true;
1576    if (t.getAsOpaquePtr() > y.t.getAsOpaquePtr())
1577      return false;
1578    else
1579      return getTypeSpecStartLoc() < y.getTypeSpecStartLoc();
1580  }
1581
1582  bool operator==(const TypeWithHandler& other) const {
1583    return t == other.t;
1584  }
1585
1586  QualType getQualType() const { return t; }
1587  CXXCatchStmt *getCatchStmt() const { return stmt; }
1588  SourceLocation getTypeSpecStartLoc() const {
1589    return stmt->getExceptionDecl()->getTypeSpecStartLoc();
1590  }
1591};
1592
1593/// ActOnCXXTryBlock - Takes a try compound-statement and a number of
1594/// handlers and creates a try statement from them.
1595Action::OwningStmtResult
1596Sema::ActOnCXXTryBlock(SourceLocation TryLoc, StmtArg TryBlock,
1597                       MultiStmtArg RawHandlers) {
1598  unsigned NumHandlers = RawHandlers.size();
1599  assert(NumHandlers > 0 &&
1600         "The parser shouldn't call this if there are no handlers.");
1601  Stmt **Handlers = reinterpret_cast<Stmt**>(RawHandlers.get());
1602
1603  llvm::SmallVector<TypeWithHandler, 8> TypesWithHandlers;
1604
1605  for (unsigned i = 0; i < NumHandlers; ++i) {
1606    CXXCatchStmt *Handler = llvm::cast<CXXCatchStmt>(Handlers[i]);
1607    if (!Handler->getExceptionDecl()) {
1608      if (i < NumHandlers - 1)
1609        return StmtError(Diag(Handler->getLocStart(),
1610                              diag::err_early_catch_all));
1611
1612      continue;
1613    }
1614
1615    const QualType CaughtType = Handler->getCaughtType();
1616    const QualType CanonicalCaughtType = Context.getCanonicalType(CaughtType);
1617    TypesWithHandlers.push_back(TypeWithHandler(CanonicalCaughtType, Handler));
1618  }
1619
1620  // Detect handlers for the same type as an earlier one.
1621  if (NumHandlers > 1) {
1622    llvm::array_pod_sort(TypesWithHandlers.begin(), TypesWithHandlers.end());
1623
1624    TypeWithHandler prev = TypesWithHandlers[0];
1625    for (unsigned i = 1; i < TypesWithHandlers.size(); ++i) {
1626      TypeWithHandler curr = TypesWithHandlers[i];
1627
1628      if (curr == prev) {
1629        Diag(curr.getTypeSpecStartLoc(),
1630             diag::warn_exception_caught_by_earlier_handler)
1631          << curr.getCatchStmt()->getCaughtType().getAsString();
1632        Diag(prev.getTypeSpecStartLoc(),
1633             diag::note_previous_exception_handler)
1634          << prev.getCatchStmt()->getCaughtType().getAsString();
1635      }
1636
1637      prev = curr;
1638    }
1639  }
1640
1641  // FIXME: We should detect handlers that cannot catch anything because an
1642  // earlier handler catches a superclass. Need to find a method that is not
1643  // quadratic for this.
1644  // Neither of these are explicitly forbidden, but every compiler detects them
1645  // and warns.
1646
1647  FunctionNeedsScopeChecking() = true;
1648  RawHandlers.release();
1649  return Owned(CXXTryStmt::Create(Context, TryLoc,
1650                                  static_cast<Stmt*>(TryBlock.release()),
1651                                  Handlers, NumHandlers));
1652}
1653