SemaStmt.cpp revision 49d10ab2aeef21d10751226aa7a39efa089986a8 
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/AST/TypeLoc.h"
24#include "clang/Lex/Preprocessor.h"
25#include "clang/Basic/TargetInfo.h"
26#include "llvm/ADT/STLExtras.h"
27#include "llvm/ADT/SmallVector.h"
28using namespace clang;
29
30Sema::OwningStmtResult Sema::ActOnExprStmt(FullExprArg expr) {
31  Expr *E = expr->takeAs<Expr>();
32  assert(E && "ActOnExprStmt(): missing expression");
33  if (E->getType()->isObjCInterfaceType()) {
34    if (LangOpts.ObjCNonFragileABI)
35      Diag(E->getLocEnd(), diag::err_indirection_requires_nonfragile_object)
36             << E->getType();
37    else
38      Diag(E->getLocEnd(), diag::err_direct_interface_unsupported)
39             << E->getType();
40    return StmtError();
41  }
42  // C99 6.8.3p2: The expression in an expression statement is evaluated as a
43  // void expression for its side effects.  Conversion to void allows any
44  // operand, even incomplete types.
45
46  // Same thing in for stmt first clause (when expr) and third clause.
47  return Owned(static_cast<Stmt*>(E));
48}
49
50
51Sema::OwningStmtResult Sema::ActOnNullStmt(SourceLocation SemiLoc) {
52  return Owned(new (Context) NullStmt(SemiLoc));
53}
54
55Sema::OwningStmtResult Sema::ActOnDeclStmt(DeclGroupPtrTy dg,
56                                           SourceLocation StartLoc,
57                                           SourceLocation EndLoc) {
58  DeclGroupRef DG = dg.getAsVal<DeclGroupRef>();
59
60  // If we have an invalid decl, just return an error.
61  if (DG.isNull()) return StmtError();
62
63  return Owned(new (Context) DeclStmt(DG, StartLoc, EndLoc));
64}
65
66void Sema::ActOnForEachDeclStmt(DeclGroupPtrTy dg) {
67  DeclGroupRef DG = dg.getAsVal<DeclGroupRef>();
68
69  // If we have an invalid decl, just return.
70  if (DG.isNull() || !DG.isSingleDecl()) return;
71  // suppress any potential 'unused variable' warning.
72  DG.getSingleDecl()->setUsed();
73}
74
75void Sema::DiagnoseUnusedExprResult(const Stmt *S) {
76  const Expr *E = dyn_cast_or_null<Expr>(S);
77  if (!E)
78    return;
79
80  SourceLocation Loc;
81  SourceRange R1, R2;
82  if (!E->isUnusedResultAWarning(Loc, R1, R2, Context))
83    return;
84
85  // Okay, we have an unused result.  Depending on what the base expression is,
86  // we might want to make a more specific diagnostic.  Check for one of these
87  // cases now.
88  unsigned DiagID = diag::warn_unused_expr;
89  E = E->IgnoreParens();
90  if (isa<ObjCImplicitSetterGetterRefExpr>(E))
91    DiagID = diag::warn_unused_property_expr;
92
93  if (const CXXExprWithTemporaries *Temps = dyn_cast<CXXExprWithTemporaries>(E))
94    E = Temps->getSubExpr();
95  if (const CXXZeroInitValueExpr *Zero = dyn_cast<CXXZeroInitValueExpr>(E)) {
96    if (const RecordType *RecordT = Zero->getType()->getAs<RecordType>())
97      if (CXXRecordDecl *RecordD = dyn_cast<CXXRecordDecl>(RecordT->getDecl()))
98        if (!RecordD->hasTrivialDestructor())
99          return;
100  }
101
102  if (const CallExpr *CE = dyn_cast<CallExpr>(E)) {
103    if (E->getType()->isVoidType())
104      return;
105
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  else if (const ObjCMessageExpr *ME = dyn_cast<ObjCMessageExpr>(E)) {
124    const ObjCMethodDecl *MD = ME->getMethodDecl();
125    if (MD && MD->getAttr<WarnUnusedResultAttr>()) {
126      Diag(Loc, diag::warn_unused_call) << R1 << R2 << "warn_unused_result";
127      return;
128    }
129  } else if (const CXXFunctionalCastExpr *FC
130                                       = dyn_cast<CXXFunctionalCastExpr>(E)) {
131    if (isa<CXXConstructExpr>(FC->getSubExpr()) ||
132        isa<CXXTemporaryObjectExpr>(FC->getSubExpr()))
133      return;
134  }
135  // Diagnose "(void*) blah" as a typo for "(void) blah".
136  else if (const CStyleCastExpr *CE = dyn_cast<CStyleCastExpr>(E)) {
137    TypeSourceInfo *TI = CE->getTypeInfoAsWritten();
138    QualType T = TI->getType();
139
140    // We really do want to use the non-canonical type here.
141    if (T == Context.VoidPtrTy) {
142      PointerTypeLoc TL = cast<PointerTypeLoc>(TI->getTypeLoc());
143
144      Diag(Loc, diag::warn_unused_voidptr)
145        << FixItHint::CreateRemoval(TL.getStarLoc());
146      return;
147    }
148  }
149
150  Diag(Loc, DiagID) << R1 << R2;
151}
152
153Action::OwningStmtResult
154Sema::ActOnCompoundStmt(SourceLocation L, SourceLocation R,
155                        MultiStmtArg elts, bool isStmtExpr) {
156  unsigned NumElts = elts.size();
157  Stmt **Elts = reinterpret_cast<Stmt**>(elts.release());
158  // If we're in C89 mode, check that we don't have any decls after stmts.  If
159  // so, emit an extension diagnostic.
160  if (!getLangOptions().C99 && !getLangOptions().CPlusPlus) {
161    // Note that __extension__ can be around a decl.
162    unsigned i = 0;
163    // Skip over all declarations.
164    for (; i != NumElts && isa<DeclStmt>(Elts[i]); ++i)
165      /*empty*/;
166
167    // We found the end of the list or a statement.  Scan for another declstmt.
168    for (; i != NumElts && !isa<DeclStmt>(Elts[i]); ++i)
169      /*empty*/;
170
171    if (i != NumElts) {
172      Decl *D = *cast<DeclStmt>(Elts[i])->decl_begin();
173      Diag(D->getLocation(), diag::ext_mixed_decls_code);
174    }
175  }
176  // Warn about unused expressions in statements.
177  for (unsigned i = 0; i != NumElts; ++i) {
178    // Ignore statements that are last in a statement expression.
179    if (isStmtExpr && i == NumElts - 1)
180      continue;
181
182    DiagnoseUnusedExprResult(Elts[i]);
183  }
184
185  return Owned(new (Context) CompoundStmt(Context, Elts, NumElts, L, R));
186}
187
188Action::OwningStmtResult
189Sema::ActOnCaseStmt(SourceLocation CaseLoc, ExprArg lhsval,
190                    SourceLocation DotDotDotLoc, ExprArg rhsval,
191                    SourceLocation ColonLoc) {
192  assert((lhsval.get() != 0) && "missing expression in case statement");
193
194  // C99 6.8.4.2p3: The expression shall be an integer constant.
195  // However, GCC allows any evaluatable integer expression.
196  Expr *LHSVal = static_cast<Expr*>(lhsval.get());
197  if (!LHSVal->isTypeDependent() && !LHSVal->isValueDependent() &&
198      VerifyIntegerConstantExpression(LHSVal))
199    return StmtError();
200
201  // GCC extension: The expression shall be an integer constant.
202
203  Expr *RHSVal = static_cast<Expr*>(rhsval.get());
204  if (RHSVal && !RHSVal->isTypeDependent() && !RHSVal->isValueDependent() &&
205      VerifyIntegerConstantExpression(RHSVal)) {
206    RHSVal = 0;  // Recover by just forgetting about it.
207    rhsval = 0;
208  }
209
210  if (getSwitchStack().empty()) {
211    Diag(CaseLoc, diag::err_case_not_in_switch);
212    return StmtError();
213  }
214
215  // Only now release the smart pointers.
216  lhsval.release();
217  rhsval.release();
218  CaseStmt *CS = new (Context) CaseStmt(LHSVal, RHSVal, CaseLoc, DotDotDotLoc,
219                                        ColonLoc);
220  getSwitchStack().back()->addSwitchCase(CS);
221  return Owned(CS);
222}
223
224/// ActOnCaseStmtBody - This installs a statement as the body of a case.
225void Sema::ActOnCaseStmtBody(StmtTy *caseStmt, StmtArg subStmt) {
226  CaseStmt *CS = static_cast<CaseStmt*>(caseStmt);
227  Stmt *SubStmt = subStmt.takeAs<Stmt>();
228  CS->setSubStmt(SubStmt);
229}
230
231Action::OwningStmtResult
232Sema::ActOnDefaultStmt(SourceLocation DefaultLoc, SourceLocation ColonLoc,
233                       StmtArg subStmt, Scope *CurScope) {
234  Stmt *SubStmt = subStmt.takeAs<Stmt>();
235
236  if (getSwitchStack().empty()) {
237    Diag(DefaultLoc, diag::err_default_not_in_switch);
238    return Owned(SubStmt);
239  }
240
241  DefaultStmt *DS = new (Context) DefaultStmt(DefaultLoc, ColonLoc, SubStmt);
242  getSwitchStack().back()->addSwitchCase(DS);
243  return Owned(DS);
244}
245
246Action::OwningStmtResult
247Sema::ActOnLabelStmt(SourceLocation IdentLoc, IdentifierInfo *II,
248                     SourceLocation ColonLoc, StmtArg subStmt) {
249  Stmt *SubStmt = subStmt.takeAs<Stmt>();
250  // Look up the record for this label identifier.
251  LabelStmt *&LabelDecl = getLabelMap()[II];
252
253  // If not forward referenced or defined already, just create a new LabelStmt.
254  if (LabelDecl == 0)
255    return Owned(LabelDecl = new (Context) LabelStmt(IdentLoc, II, SubStmt));
256
257  assert(LabelDecl->getID() == II && "Label mismatch!");
258
259  // Otherwise, this label was either forward reference or multiply defined.  If
260  // multiply defined, reject it now.
261  if (LabelDecl->getSubStmt()) {
262    Diag(IdentLoc, diag::err_redefinition_of_label) << LabelDecl->getID();
263    Diag(LabelDecl->getIdentLoc(), diag::note_previous_definition);
264    return Owned(SubStmt);
265  }
266
267  // Otherwise, this label was forward declared, and we just found its real
268  // definition.  Fill in the forward definition and return it.
269  LabelDecl->setIdentLoc(IdentLoc);
270  LabelDecl->setSubStmt(SubStmt);
271  return Owned(LabelDecl);
272}
273
274Action::OwningStmtResult
275Sema::ActOnIfStmt(SourceLocation IfLoc, FullExprArg CondVal, DeclPtrTy CondVar,
276                  StmtArg ThenVal, SourceLocation ElseLoc,
277                  StmtArg ElseVal) {
278  OwningExprResult CondResult(CondVal.release());
279
280  VarDecl *ConditionVar = 0;
281  if (CondVar.get()) {
282    ConditionVar = CondVar.getAs<VarDecl>();
283    CondResult = CheckConditionVariable(ConditionVar);
284    if (CondResult.isInvalid())
285      return StmtError();
286  }
287  Expr *ConditionExpr = CondResult.takeAs<Expr>();
288  if (!ConditionExpr)
289    return StmtError();
290
291  if (CheckBooleanCondition(ConditionExpr, IfLoc)) {
292    CondResult = ConditionExpr;
293    return StmtError();
294  }
295
296  Stmt *thenStmt = ThenVal.takeAs<Stmt>();
297  DiagnoseUnusedExprResult(thenStmt);
298
299  // Warn if the if block has a null body without an else value.
300  // this helps prevent bugs due to typos, such as
301  // if (condition);
302  //   do_stuff();
303  if (!ElseVal.get()) {
304    if (NullStmt* stmt = dyn_cast<NullStmt>(thenStmt))
305      Diag(stmt->getSemiLoc(), diag::warn_empty_if_body);
306  }
307
308  Stmt *elseStmt = ElseVal.takeAs<Stmt>();
309  DiagnoseUnusedExprResult(elseStmt);
310
311  CondResult.release();
312  return Owned(new (Context) IfStmt(IfLoc, ConditionVar, ConditionExpr,
313                                    thenStmt, ElseLoc, elseStmt));
314}
315
316Action::OwningStmtResult
317Sema::ActOnStartOfSwitchStmt(FullExprArg cond, DeclPtrTy CondVar) {
318  OwningExprResult CondResult(cond.release());
319
320  VarDecl *ConditionVar = 0;
321  if (CondVar.get()) {
322    ConditionVar = CondVar.getAs<VarDecl>();
323    CondResult = CheckConditionVariable(ConditionVar);
324    if (CondResult.isInvalid())
325      return StmtError();
326  }
327  SwitchStmt *SS = new (Context) SwitchStmt(ConditionVar,
328                                            CondResult.takeAs<Expr>());
329  getSwitchStack().push_back(SS);
330  return Owned(SS);
331}
332
333/// ConvertIntegerToTypeWarnOnOverflow - Convert the specified APInt to have
334/// the specified width and sign.  If an overflow occurs, detect it and emit
335/// the specified diagnostic.
336void Sema::ConvertIntegerToTypeWarnOnOverflow(llvm::APSInt &Val,
337                                              unsigned NewWidth, bool NewSign,
338                                              SourceLocation Loc,
339                                              unsigned DiagID) {
340  // Perform a conversion to the promoted condition type if needed.
341  if (NewWidth > Val.getBitWidth()) {
342    // If this is an extension, just do it.
343    Val.extend(NewWidth);
344    Val.setIsSigned(NewSign);
345
346    // If the input was signed and negative and the output is
347    // unsigned, don't bother to warn: this is implementation-defined
348    // behavior.
349    // FIXME: Introduce a second, default-ignored warning for this case?
350  } else if (NewWidth < Val.getBitWidth()) {
351    // If this is a truncation, check for overflow.
352    llvm::APSInt ConvVal(Val);
353    ConvVal.trunc(NewWidth);
354    ConvVal.setIsSigned(NewSign);
355    ConvVal.extend(Val.getBitWidth());
356    ConvVal.setIsSigned(Val.isSigned());
357    if (ConvVal != Val)
358      Diag(Loc, DiagID) << Val.toString(10) << ConvVal.toString(10);
359
360    // Regardless of whether a diagnostic was emitted, really do the
361    // truncation.
362    Val.trunc(NewWidth);
363    Val.setIsSigned(NewSign);
364  } else if (NewSign != Val.isSigned()) {
365    // Convert the sign to match the sign of the condition.  This can cause
366    // overflow as well: unsigned(INTMIN)
367    // We don't diagnose this overflow, because it is implementation-defined
368    // behavior.
369    // FIXME: Introduce a second, default-ignored warning for this case?
370    llvm::APSInt OldVal(Val);
371    Val.setIsSigned(NewSign);
372  }
373}
374
375namespace {
376  struct CaseCompareFunctor {
377    bool operator()(const std::pair<llvm::APSInt, CaseStmt*> &LHS,
378                    const llvm::APSInt &RHS) {
379      return LHS.first < RHS;
380    }
381    bool operator()(const std::pair<llvm::APSInt, CaseStmt*> &LHS,
382                    const std::pair<llvm::APSInt, CaseStmt*> &RHS) {
383      return LHS.first < RHS.first;
384    }
385    bool operator()(const llvm::APSInt &LHS,
386                    const std::pair<llvm::APSInt, CaseStmt*> &RHS) {
387      return LHS < RHS.first;
388    }
389  };
390}
391
392/// CmpCaseVals - Comparison predicate for sorting case values.
393///
394static bool CmpCaseVals(const std::pair<llvm::APSInt, CaseStmt*>& lhs,
395                        const std::pair<llvm::APSInt, CaseStmt*>& rhs) {
396  if (lhs.first < rhs.first)
397    return true;
398
399  if (lhs.first == rhs.first &&
400      lhs.second->getCaseLoc().getRawEncoding()
401       < rhs.second->getCaseLoc().getRawEncoding())
402    return true;
403  return false;
404}
405
406/// CmpEnumVals - Comparison predicate for sorting enumeration values.
407///
408static bool CmpEnumVals(const std::pair<llvm::APSInt, EnumConstantDecl*>& lhs,
409                        const std::pair<llvm::APSInt, EnumConstantDecl*>& rhs)
410{
411  return lhs.first < rhs.first;
412}
413
414/// EqEnumVals - Comparison preficate for uniqing enumeration values.
415///
416static bool EqEnumVals(const std::pair<llvm::APSInt, EnumConstantDecl*>& lhs,
417                       const std::pair<llvm::APSInt, EnumConstantDecl*>& rhs)
418{
419  return lhs.first == rhs.first;
420}
421
422/// GetTypeBeforeIntegralPromotion - Returns the pre-promotion type of
423/// potentially integral-promoted expression @p expr.
424static QualType GetTypeBeforeIntegralPromotion(const Expr* expr) {
425  const ImplicitCastExpr *ImplicitCast =
426      dyn_cast_or_null<ImplicitCastExpr>(expr);
427  if (ImplicitCast != NULL) {
428    const Expr *ExprBeforePromotion = ImplicitCast->getSubExpr();
429    QualType TypeBeforePromotion = ExprBeforePromotion->getType();
430    if (TypeBeforePromotion->isIntegralType()) {
431      return TypeBeforePromotion;
432    }
433  }
434  return expr->getType();
435}
436
437/// \brief Check (and possibly convert) the condition in a switch
438/// statement in C++.
439static bool CheckCXXSwitchCondition(Sema &S, SourceLocation SwitchLoc,
440                                    Expr *&CondExpr) {
441  if (CondExpr->isTypeDependent())
442    return false;
443
444  QualType CondType = CondExpr->getType();
445
446  // C++ 6.4.2.p2:
447  // The condition shall be of integral type, enumeration type, or of a class
448  // type for which a single conversion function to integral or enumeration
449  // type exists (12.3). If the condition is of class type, the condition is
450  // converted by calling that conversion function, and the result of the
451  // conversion is used in place of the original condition for the remainder
452  // of this section. Integral promotions are performed.
453
454  // Make sure that the condition expression has a complete type,
455  // otherwise we'll never find any conversions.
456  if (S.RequireCompleteType(SwitchLoc, CondType,
457                            S.PDiag(diag::err_switch_incomplete_class_type)
458                              << CondExpr->getSourceRange()))
459    return true;
460
461  UnresolvedSet<4> ViableConversions;
462  UnresolvedSet<4> ExplicitConversions;
463  if (const RecordType *RecordTy = CondType->getAs<RecordType>()) {
464    const UnresolvedSetImpl *Conversions
465      = cast<CXXRecordDecl>(RecordTy->getDecl())
466                                             ->getVisibleConversionFunctions();
467    for (UnresolvedSetImpl::iterator I = Conversions->begin(),
468           E = Conversions->end(); I != E; ++I) {
469      if (CXXConversionDecl *Conversion
470            = dyn_cast<CXXConversionDecl>((*I)->getUnderlyingDecl()))
471        if (Conversion->getConversionType().getNonReferenceType()
472              ->isIntegralType()) {
473          if (Conversion->isExplicit())
474            ExplicitConversions.addDecl(I.getDecl(), I.getAccess());
475          else
476            ViableConversions.addDecl(I.getDecl(), I.getAccess());
477        }
478    }
479
480    switch (ViableConversions.size()) {
481    case 0:
482      if (ExplicitConversions.size() == 1) {
483        DeclAccessPair Found = ExplicitConversions[0];
484        CXXConversionDecl *Conversion =
485          cast<CXXConversionDecl>(Found->getUnderlyingDecl());
486        // The user probably meant to invoke the given explicit
487        // conversion; use it.
488        QualType ConvTy
489          = Conversion->getConversionType().getNonReferenceType();
490        std::string TypeStr;
491        ConvTy.getAsStringInternal(TypeStr, S.Context.PrintingPolicy);
492
493        S.Diag(SwitchLoc, diag::err_switch_explicit_conversion)
494          << CondType << ConvTy << CondExpr->getSourceRange()
495          << FixItHint::CreateInsertion(CondExpr->getLocStart(),
496                                        "static_cast<" + TypeStr + ">(")
497          << FixItHint::CreateInsertion(
498                            S.PP.getLocForEndOfToken(CondExpr->getLocEnd()),
499                               ")");
500        S.Diag(Conversion->getLocation(), diag::note_switch_conversion)
501          << ConvTy->isEnumeralType() << ConvTy;
502
503        // If we aren't in a SFINAE context, build a call to the
504        // explicit conversion function.
505        if (S.isSFINAEContext())
506          return true;
507
508        S.CheckMemberOperatorAccess(CondExpr->getExprLoc(),
509                                    CondExpr, 0, Found);
510        CondExpr = S.BuildCXXMemberCallExpr(CondExpr, Found, Conversion);
511      }
512
513      // We'll complain below about a non-integral condition type.
514      break;
515
516    case 1: {
517      // Apply this conversion.
518      DeclAccessPair Found = ViableConversions[0];
519      S.CheckMemberOperatorAccess(CondExpr->getExprLoc(),
520                                  CondExpr, 0, Found);
521      CondExpr = S.BuildCXXMemberCallExpr(CondExpr, Found,
522                        cast<CXXConversionDecl>(Found->getUnderlyingDecl()));
523      break;
524    }
525
526    default:
527      S.Diag(SwitchLoc, diag::err_switch_multiple_conversions)
528        << CondType << CondExpr->getSourceRange();
529      for (unsigned I = 0, N = ViableConversions.size(); I != N; ++I) {
530        CXXConversionDecl *Conv
531          = cast<CXXConversionDecl>(ViableConversions[I]->getUnderlyingDecl());
532        QualType ConvTy = Conv->getConversionType().getNonReferenceType();
533        S.Diag(Conv->getLocation(), diag::note_switch_conversion)
534          << ConvTy->isEnumeralType() << ConvTy;
535      }
536      return true;
537    }
538  }
539
540  return false;
541}
542
543/// ActOnSwitchBodyError - This is called if there is an error parsing the
544/// body of the switch stmt instead of ActOnFinishSwitchStmt.
545void Sema::ActOnSwitchBodyError(SourceLocation SwitchLoc, StmtArg Switch,
546                                StmtArg Body) {
547  // Keep the switch stack balanced.
548  assert(getSwitchStack().back() == (SwitchStmt*)Switch.get() &&
549         "switch stack missing push/pop!");
550  getSwitchStack().pop_back();
551}
552
553Action::OwningStmtResult
554Sema::ActOnFinishSwitchStmt(SourceLocation SwitchLoc, StmtArg Switch,
555                            StmtArg Body) {
556  Stmt *BodyStmt = Body.takeAs<Stmt>();
557
558  SwitchStmt *SS = getSwitchStack().back();
559  assert(SS == (SwitchStmt*)Switch.get() && "switch stack missing push/pop!");
560
561  SS->setBody(BodyStmt, SwitchLoc);
562  getSwitchStack().pop_back();
563
564  if (SS->getCond() == 0) {
565    SS->Destroy(Context);
566    return StmtError();
567  }
568
569  Expr *CondExpr = SS->getCond();
570  QualType CondTypeBeforePromotion =
571      GetTypeBeforeIntegralPromotion(CondExpr);
572
573  if (getLangOptions().CPlusPlus &&
574      CheckCXXSwitchCondition(*this, SwitchLoc, CondExpr))
575    return StmtError();
576
577  // C99 6.8.4.2p5 - Integer promotions are performed on the controlling expr.
578  UsualUnaryConversions(CondExpr);
579  QualType CondType = CondExpr->getType();
580  SS->setCond(CondExpr);
581
582  // C++ 6.4.2.p2:
583  // Integral promotions are performed (on the switch condition).
584  //
585  // A case value unrepresentable by the original switch condition
586  // type (before the promotion) doesn't make sense, even when it can
587  // be represented by the promoted type.  Therefore we need to find
588  // the pre-promotion type of the switch condition.
589  if (!CondExpr->isTypeDependent()) {
590    if (!CondType->isIntegerType()) { // C99 6.8.4.2p1
591      Diag(SwitchLoc, diag::err_typecheck_statement_requires_integer)
592          << CondType << CondExpr->getSourceRange();
593      return StmtError();
594    }
595
596    if (CondExpr->isKnownToHaveBooleanValue()) {
597      // switch(bool_expr) {...} is often a programmer error, e.g.
598      //   switch(n && mask) { ... }  // Doh - should be "n & mask".
599      // One can always use an if statement instead of switch(bool_expr).
600      Diag(SwitchLoc, diag::warn_bool_switch_condition)
601          << CondExpr->getSourceRange();
602    }
603  }
604
605  // Get the bitwidth of the switched-on value before promotions.  We must
606  // convert the integer case values to this width before comparison.
607  bool HasDependentValue
608    = CondExpr->isTypeDependent() || CondExpr->isValueDependent();
609  unsigned CondWidth
610    = HasDependentValue? 0
611      : static_cast<unsigned>(Context.getTypeSize(CondTypeBeforePromotion));
612  bool CondIsSigned = CondTypeBeforePromotion->isSignedIntegerType();
613
614  // Accumulate all of the case values in a vector so that we can sort them
615  // and detect duplicates.  This vector contains the APInt for the case after
616  // it has been converted to the condition type.
617  typedef llvm::SmallVector<std::pair<llvm::APSInt, CaseStmt*>, 64> CaseValsTy;
618  CaseValsTy CaseVals;
619
620  // Keep track of any GNU case ranges we see.  The APSInt is the low value.
621  typedef std::vector<std::pair<llvm::APSInt, CaseStmt*> > CaseRangesTy;
622  CaseRangesTy CaseRanges;
623
624  DefaultStmt *TheDefaultStmt = 0;
625
626  bool CaseListIsErroneous = false;
627
628  for (SwitchCase *SC = SS->getSwitchCaseList(); SC && !HasDependentValue;
629       SC = SC->getNextSwitchCase()) {
630
631    if (DefaultStmt *DS = dyn_cast<DefaultStmt>(SC)) {
632      if (TheDefaultStmt) {
633        Diag(DS->getDefaultLoc(), diag::err_multiple_default_labels_defined);
634        Diag(TheDefaultStmt->getDefaultLoc(), diag::note_duplicate_case_prev);
635
636        // FIXME: Remove the default statement from the switch block so that
637        // we'll return a valid AST.  This requires recursing down the AST and
638        // finding it, not something we are set up to do right now.  For now,
639        // just lop the entire switch stmt out of the AST.
640        CaseListIsErroneous = true;
641      }
642      TheDefaultStmt = DS;
643
644    } else {
645      CaseStmt *CS = cast<CaseStmt>(SC);
646
647      // We already verified that the expression has a i-c-e value (C99
648      // 6.8.4.2p3) - get that value now.
649      Expr *Lo = CS->getLHS();
650
651      if (Lo->isTypeDependent() || Lo->isValueDependent()) {
652        HasDependentValue = true;
653        break;
654      }
655
656      llvm::APSInt LoVal = Lo->EvaluateAsInt(Context);
657
658      // Convert the value to the same width/sign as the condition.
659      ConvertIntegerToTypeWarnOnOverflow(LoVal, CondWidth, CondIsSigned,
660                                         CS->getLHS()->getLocStart(),
661                                         diag::warn_case_value_overflow);
662
663      // If the LHS is not the same type as the condition, insert an implicit
664      // cast.
665      ImpCastExprToType(Lo, CondType, CastExpr::CK_IntegralCast);
666      CS->setLHS(Lo);
667
668      // If this is a case range, remember it in CaseRanges, otherwise CaseVals.
669      if (CS->getRHS()) {
670        if (CS->getRHS()->isTypeDependent() ||
671            CS->getRHS()->isValueDependent()) {
672          HasDependentValue = true;
673          break;
674        }
675        CaseRanges.push_back(std::make_pair(LoVal, CS));
676      } else
677        CaseVals.push_back(std::make_pair(LoVal, CS));
678    }
679  }
680
681  if (!HasDependentValue) {
682    // Sort all the scalar case values so we can easily detect duplicates.
683    std::stable_sort(CaseVals.begin(), CaseVals.end(), CmpCaseVals);
684
685    if (!CaseVals.empty()) {
686      for (unsigned i = 0, e = CaseVals.size()-1; i != e; ++i) {
687        if (CaseVals[i].first == CaseVals[i+1].first) {
688          // If we have a duplicate, report it.
689          Diag(CaseVals[i+1].second->getLHS()->getLocStart(),
690               diag::err_duplicate_case) << CaseVals[i].first.toString(10);
691          Diag(CaseVals[i].second->getLHS()->getLocStart(),
692               diag::note_duplicate_case_prev);
693          // FIXME: We really want to remove the bogus case stmt from the
694          // substmt, but we have no way to do this right now.
695          CaseListIsErroneous = true;
696        }
697      }
698    }
699
700    // Detect duplicate case ranges, which usually don't exist at all in
701    // the first place.
702    if (!CaseRanges.empty()) {
703      // Sort all the case ranges by their low value so we can easily detect
704      // overlaps between ranges.
705      std::stable_sort(CaseRanges.begin(), CaseRanges.end());
706
707      // Scan the ranges, computing the high values and removing empty ranges.
708      std::vector<llvm::APSInt> HiVals;
709      for (unsigned i = 0, e = CaseRanges.size(); i != e; ++i) {
710        CaseStmt *CR = CaseRanges[i].second;
711        Expr *Hi = CR->getRHS();
712        llvm::APSInt HiVal = Hi->EvaluateAsInt(Context);
713
714        // Convert the value to the same width/sign as the condition.
715        ConvertIntegerToTypeWarnOnOverflow(HiVal, CondWidth, CondIsSigned,
716                                           CR->getRHS()->getLocStart(),
717                                           diag::warn_case_value_overflow);
718
719        // If the LHS is not the same type as the condition, insert an implicit
720        // cast.
721        ImpCastExprToType(Hi, CondType, CastExpr::CK_IntegralCast);
722        CR->setRHS(Hi);
723
724        // If the low value is bigger than the high value, the case is empty.
725        if (CaseRanges[i].first > HiVal) {
726          Diag(CR->getLHS()->getLocStart(), diag::warn_case_empty_range)
727            << SourceRange(CR->getLHS()->getLocStart(),
728                           CR->getRHS()->getLocEnd());
729          CaseRanges.erase(CaseRanges.begin()+i);
730          --i, --e;
731          continue;
732        }
733        HiVals.push_back(HiVal);
734      }
735
736      // Rescan the ranges, looking for overlap with singleton values and other
737      // ranges.  Since the range list is sorted, we only need to compare case
738      // ranges with their neighbors.
739      for (unsigned i = 0, e = CaseRanges.size(); i != e; ++i) {
740        llvm::APSInt &CRLo = CaseRanges[i].first;
741        llvm::APSInt &CRHi = HiVals[i];
742        CaseStmt *CR = CaseRanges[i].second;
743
744        // Check to see whether the case range overlaps with any
745        // singleton cases.
746        CaseStmt *OverlapStmt = 0;
747        llvm::APSInt OverlapVal(32);
748
749        // Find the smallest value >= the lower bound.  If I is in the
750        // case range, then we have overlap.
751        CaseValsTy::iterator I = std::lower_bound(CaseVals.begin(),
752                                                  CaseVals.end(), CRLo,
753                                                  CaseCompareFunctor());
754        if (I != CaseVals.end() && I->first < CRHi) {
755          OverlapVal  = I->first;   // Found overlap with scalar.
756          OverlapStmt = I->second;
757        }
758
759        // Find the smallest value bigger than the upper bound.
760        I = std::upper_bound(I, CaseVals.end(), CRHi, CaseCompareFunctor());
761        if (I != CaseVals.begin() && (I-1)->first >= CRLo) {
762          OverlapVal  = (I-1)->first;      // Found overlap with scalar.
763          OverlapStmt = (I-1)->second;
764        }
765
766        // Check to see if this case stmt overlaps with the subsequent
767        // case range.
768        if (i && CRLo <= HiVals[i-1]) {
769          OverlapVal  = HiVals[i-1];       // Found overlap with range.
770          OverlapStmt = CaseRanges[i-1].second;
771        }
772
773        if (OverlapStmt) {
774          // If we have a duplicate, report it.
775          Diag(CR->getLHS()->getLocStart(), diag::err_duplicate_case)
776            << OverlapVal.toString(10);
777          Diag(OverlapStmt->getLHS()->getLocStart(),
778               diag::note_duplicate_case_prev);
779          // FIXME: We really want to remove the bogus case stmt from the
780          // substmt, but we have no way to do this right now.
781          CaseListIsErroneous = true;
782        }
783      }
784    }
785
786    // Check to see if switch is over an Enum and handles all of its
787    // values
788    const EnumType* ET = CondTypeBeforePromotion->getAs<EnumType>();
789    // If switch has default case, then ignore it.
790    if (!CaseListIsErroneous && !TheDefaultStmt && ET) {
791      const EnumDecl *ED = ET->getDecl();
792      typedef llvm::SmallVector<std::pair<llvm::APSInt, EnumConstantDecl*>, 64> EnumValsTy;
793      EnumValsTy EnumVals;
794
795      // Gather all enum values, set their type and sort them, allowing easier comparison
796      // with CaseVals.
797      for (EnumDecl::enumerator_iterator EDI = ED->enumerator_begin(); EDI != ED->enumerator_end(); EDI++) {
798        llvm::APSInt Val = (*EDI)->getInitVal();
799        if(Val.getBitWidth() < CondWidth)
800          Val.extend(CondWidth);
801        Val.setIsSigned(CondIsSigned);
802        EnumVals.push_back(std::make_pair(Val, (*EDI)));
803      }
804      std::stable_sort(EnumVals.begin(), EnumVals.end(), CmpEnumVals);
805      EnumValsTy::iterator EIend = std::unique(EnumVals.begin(), EnumVals.end(), EqEnumVals);
806      // See which case values aren't in enum
807      EnumValsTy::const_iterator EI = EnumVals.begin();
808      for (CaseValsTy::const_iterator CI = CaseVals.begin(); CI != CaseVals.end(); CI++) {
809        while (EI != EIend && EI->first < CI->first)
810          EI++;
811        if (EI == EIend || EI->first > CI->first)
812            Diag(CI->second->getLHS()->getExprLoc(), diag::not_in_enum) << ED->getDeclName();
813      }
814      // See which of case ranges aren't in enum
815      EI = EnumVals.begin();
816      for (CaseRangesTy::const_iterator RI = CaseRanges.begin(); RI != CaseRanges.end() && EI != EIend; RI++) {
817        while (EI != EIend && EI->first < RI->first)
818          EI++;
819
820        if (EI == EIend || EI->first != RI->first) {
821          Diag(RI->second->getLHS()->getExprLoc(), diag::not_in_enum) << ED->getDeclName();
822        }
823
824        llvm::APSInt Hi = RI->second->getRHS()->EvaluateAsInt(Context);
825        while (EI != EIend && EI->first < Hi)
826          EI++;
827        if (EI == EIend || EI->first != Hi)
828          Diag(RI->second->getRHS()->getExprLoc(), diag::not_in_enum) << ED->getDeclName();
829      }
830      //Check which enum vals aren't in switch
831      CaseValsTy::const_iterator CI = CaseVals.begin();
832      CaseRangesTy::const_iterator RI = CaseRanges.begin();
833      EI = EnumVals.begin();
834      for (; EI != EIend; EI++) {
835        //Drop unneeded case values
836        llvm::APSInt CIVal;
837        while (CI != CaseVals.end() && CI->first < EI->first)
838          CI++;
839
840        if (CI != CaseVals.end() && CI->first == EI->first)
841          continue;
842
843        //Drop unneeded case ranges
844        for (; RI != CaseRanges.end(); RI++) {
845          llvm::APSInt Hi = RI->second->getRHS()->EvaluateAsInt(Context);
846          if (EI->first <= Hi)
847            break;
848        }
849
850        if (RI == CaseRanges.end() || EI->first < RI->first)
851          Diag(CondExpr->getExprLoc(), diag::warn_missing_cases) << EI->second->getDeclName();
852      }
853    }
854  }
855
856  // FIXME: If the case list was broken is some way, we don't have a good system
857  // to patch it up.  Instead, just return the whole substmt as broken.
858  if (CaseListIsErroneous)
859    return StmtError();
860
861  Switch.release();
862  return Owned(SS);
863}
864
865Action::OwningStmtResult
866Sema::ActOnWhileStmt(SourceLocation WhileLoc, FullExprArg Cond,
867                     DeclPtrTy CondVar, StmtArg Body) {
868  OwningExprResult CondResult(Cond.release());
869
870  VarDecl *ConditionVar = 0;
871  if (CondVar.get()) {
872    ConditionVar = CondVar.getAs<VarDecl>();
873    CondResult = CheckConditionVariable(ConditionVar);
874    if (CondResult.isInvalid())
875      return StmtError();
876  }
877  Expr *ConditionExpr = CondResult.takeAs<Expr>();
878  if (!ConditionExpr)
879    return StmtError();
880
881  if (CheckBooleanCondition(ConditionExpr, WhileLoc)) {
882    CondResult = ConditionExpr;
883    return StmtError();
884  }
885
886  Stmt *bodyStmt = Body.takeAs<Stmt>();
887  DiagnoseUnusedExprResult(bodyStmt);
888
889  CondResult.release();
890  return Owned(new (Context) WhileStmt(ConditionVar, ConditionExpr, bodyStmt,
891                                       WhileLoc));
892}
893
894Action::OwningStmtResult
895Sema::ActOnDoStmt(SourceLocation DoLoc, StmtArg Body,
896                  SourceLocation WhileLoc, SourceLocation CondLParen,
897                  ExprArg Cond, SourceLocation CondRParen) {
898  Expr *condExpr = Cond.takeAs<Expr>();
899  assert(condExpr && "ActOnDoStmt(): missing expression");
900
901  if (CheckBooleanCondition(condExpr, DoLoc)) {
902    Cond = condExpr;
903    return StmtError();
904  }
905
906  Stmt *bodyStmt = Body.takeAs<Stmt>();
907  DiagnoseUnusedExprResult(bodyStmt);
908
909  Cond.release();
910  return Owned(new (Context) DoStmt(bodyStmt, condExpr, DoLoc,
911                                    WhileLoc, CondRParen));
912}
913
914Action::OwningStmtResult
915Sema::ActOnForStmt(SourceLocation ForLoc, SourceLocation LParenLoc,
916                   StmtArg first, FullExprArg second, DeclPtrTy secondVar,
917                   FullExprArg third,
918                   SourceLocation RParenLoc, StmtArg body) {
919  Stmt *First  = static_cast<Stmt*>(first.get());
920
921  if (!getLangOptions().CPlusPlus) {
922    if (DeclStmt *DS = dyn_cast_or_null<DeclStmt>(First)) {
923      // C99 6.8.5p3: The declaration part of a 'for' statement shall only
924      // declare identifiers for objects having storage class 'auto' or
925      // 'register'.
926      for (DeclStmt::decl_iterator DI=DS->decl_begin(), DE=DS->decl_end();
927           DI!=DE; ++DI) {
928        VarDecl *VD = dyn_cast<VarDecl>(*DI);
929        if (VD && VD->isBlockVarDecl() && !VD->hasLocalStorage())
930          VD = 0;
931        if (VD == 0)
932          Diag((*DI)->getLocation(), diag::err_non_variable_decl_in_for);
933        // FIXME: mark decl erroneous!
934      }
935    }
936  }
937
938  OwningExprResult SecondResult(second.release());
939  VarDecl *ConditionVar = 0;
940  if (secondVar.get()) {
941    ConditionVar = secondVar.getAs<VarDecl>();
942    SecondResult = CheckConditionVariable(ConditionVar);
943    if (SecondResult.isInvalid())
944      return StmtError();
945  }
946
947  Expr *Second = SecondResult.takeAs<Expr>();
948  if (Second && CheckBooleanCondition(Second, ForLoc)) {
949    SecondResult = Second;
950    return StmtError();
951  }
952
953  Expr *Third  = third.release().takeAs<Expr>();
954  Stmt *Body  = static_cast<Stmt*>(body.get());
955
956  DiagnoseUnusedExprResult(First);
957  DiagnoseUnusedExprResult(Third);
958  DiagnoseUnusedExprResult(Body);
959
960  first.release();
961  body.release();
962  return Owned(new (Context) ForStmt(First, Second, ConditionVar, Third, Body,
963                                     ForLoc, LParenLoc, RParenLoc));
964}
965
966Action::OwningStmtResult
967Sema::ActOnObjCForCollectionStmt(SourceLocation ForLoc,
968                                 SourceLocation LParenLoc,
969                                 StmtArg first, ExprArg second,
970                                 SourceLocation RParenLoc, StmtArg body) {
971  Stmt *First  = static_cast<Stmt*>(first.get());
972  Expr *Second = static_cast<Expr*>(second.get());
973  Stmt *Body  = static_cast<Stmt*>(body.get());
974  if (First) {
975    QualType FirstType;
976    if (DeclStmt *DS = dyn_cast<DeclStmt>(First)) {
977      if (!DS->isSingleDecl())
978        return StmtError(Diag((*DS->decl_begin())->getLocation(),
979                         diag::err_toomany_element_decls));
980
981      Decl *D = DS->getSingleDecl();
982      FirstType = cast<ValueDecl>(D)->getType();
983      // C99 6.8.5p3: The declaration part of a 'for' statement shall only
984      // declare identifiers for objects having storage class 'auto' or
985      // 'register'.
986      VarDecl *VD = cast<VarDecl>(D);
987      if (VD->isBlockVarDecl() && !VD->hasLocalStorage())
988        return StmtError(Diag(VD->getLocation(),
989                              diag::err_non_variable_decl_in_for));
990    } else {
991      Expr *FirstE = cast<Expr>(First);
992      if (!FirstE->isTypeDependent() &&
993          FirstE->isLvalue(Context) != Expr::LV_Valid)
994        return StmtError(Diag(First->getLocStart(),
995                   diag::err_selector_element_not_lvalue)
996          << First->getSourceRange());
997
998      FirstType = static_cast<Expr*>(First)->getType();
999    }
1000    if (!FirstType->isDependentType() &&
1001        !FirstType->isObjCObjectPointerType() &&
1002        !FirstType->isBlockPointerType())
1003        Diag(ForLoc, diag::err_selector_element_type)
1004          << FirstType << First->getSourceRange();
1005  }
1006  if (Second && !Second->isTypeDependent()) {
1007    DefaultFunctionArrayLvalueConversion(Second);
1008    QualType SecondType = Second->getType();
1009    if (!SecondType->isObjCObjectPointerType())
1010      Diag(ForLoc, diag::err_collection_expr_type)
1011        << SecondType << Second->getSourceRange();
1012  }
1013  first.release();
1014  second.release();
1015  body.release();
1016  return Owned(new (Context) ObjCForCollectionStmt(First, Second, Body,
1017                                                   ForLoc, RParenLoc));
1018}
1019
1020Action::OwningStmtResult
1021Sema::ActOnGotoStmt(SourceLocation GotoLoc, SourceLocation LabelLoc,
1022                    IdentifierInfo *LabelII) {
1023  // Look up the record for this label identifier.
1024  LabelStmt *&LabelDecl = getLabelMap()[LabelII];
1025
1026  // If we haven't seen this label yet, create a forward reference.
1027  if (LabelDecl == 0)
1028    LabelDecl = new (Context) LabelStmt(LabelLoc, LabelII, 0);
1029
1030  return Owned(new (Context) GotoStmt(LabelDecl, GotoLoc, LabelLoc));
1031}
1032
1033Action::OwningStmtResult
1034Sema::ActOnIndirectGotoStmt(SourceLocation GotoLoc, SourceLocation StarLoc,
1035                            ExprArg DestExp) {
1036  // Convert operand to void*
1037  Expr* E = DestExp.takeAs<Expr>();
1038  if (!E->isTypeDependent()) {
1039    QualType ETy = E->getType();
1040    QualType DestTy = Context.getPointerType(Context.VoidTy.withConst());
1041    AssignConvertType ConvTy =
1042      CheckSingleAssignmentConstraints(DestTy, E);
1043    if (DiagnoseAssignmentResult(ConvTy, StarLoc, DestTy, ETy, E, AA_Passing))
1044      return StmtError();
1045  }
1046  return Owned(new (Context) IndirectGotoStmt(GotoLoc, StarLoc, E));
1047}
1048
1049Action::OwningStmtResult
1050Sema::ActOnContinueStmt(SourceLocation ContinueLoc, Scope *CurScope) {
1051  Scope *S = CurScope->getContinueParent();
1052  if (!S) {
1053    // C99 6.8.6.2p1: A break shall appear only in or as a loop body.
1054    return StmtError(Diag(ContinueLoc, diag::err_continue_not_in_loop));
1055  }
1056
1057  return Owned(new (Context) ContinueStmt(ContinueLoc));
1058}
1059
1060Action::OwningStmtResult
1061Sema::ActOnBreakStmt(SourceLocation BreakLoc, Scope *CurScope) {
1062  Scope *S = CurScope->getBreakParent();
1063  if (!S) {
1064    // C99 6.8.6.3p1: A break shall appear only in or as a switch/loop body.
1065    return StmtError(Diag(BreakLoc, diag::err_break_not_in_loop_or_switch));
1066  }
1067
1068  return Owned(new (Context) BreakStmt(BreakLoc));
1069}
1070
1071/// ActOnBlockReturnStmt - Utility routine to figure out block's return type.
1072///
1073Action::OwningStmtResult
1074Sema::ActOnBlockReturnStmt(SourceLocation ReturnLoc, Expr *RetValExp) {
1075  // If this is the first return we've seen in the block, infer the type of
1076  // the block from it.
1077  BlockScopeInfo *CurBlock = getCurBlock();
1078  if (CurBlock->ReturnType.isNull()) {
1079    if (RetValExp) {
1080      // Don't call UsualUnaryConversions(), since we don't want to do
1081      // integer promotions here.
1082      DefaultFunctionArrayLvalueConversion(RetValExp);
1083      CurBlock->ReturnType = RetValExp->getType();
1084      if (BlockDeclRefExpr *CDRE = dyn_cast<BlockDeclRefExpr>(RetValExp)) {
1085        // We have to remove a 'const' added to copied-in variable which was
1086        // part of the implementation spec. and not the actual qualifier for
1087        // the variable.
1088        if (CDRE->isConstQualAdded())
1089           CurBlock->ReturnType.removeConst();
1090      }
1091    } else
1092      CurBlock->ReturnType = Context.VoidTy;
1093  }
1094  QualType FnRetType = CurBlock->ReturnType;
1095
1096  if (CurBlock->TheDecl->hasAttr<NoReturnAttr>()) {
1097    Diag(ReturnLoc, diag::err_noreturn_block_has_return_expr)
1098      << getCurFunctionOrMethodDecl()->getDeclName();
1099    return StmtError();
1100  }
1101
1102  // Otherwise, verify that this result type matches the previous one.  We are
1103  // pickier with blocks than for normal functions because we don't have GCC
1104  // compatibility to worry about here.
1105  if (CurBlock->ReturnType->isVoidType()) {
1106    if (RetValExp) {
1107      Diag(ReturnLoc, diag::err_return_block_has_expr);
1108      RetValExp->Destroy(Context);
1109      RetValExp = 0;
1110    }
1111    return Owned(new (Context) ReturnStmt(ReturnLoc, RetValExp));
1112  }
1113
1114  if (!RetValExp)
1115    return StmtError(Diag(ReturnLoc, diag::err_block_return_missing_expr));
1116
1117  if (!FnRetType->isDependentType() && !RetValExp->isTypeDependent()) {
1118    // we have a non-void block with an expression, continue checking
1119
1120    // C99 6.8.6.4p3(136): The return statement is not an assignment. The
1121    // overlap restriction of subclause 6.5.16.1 does not apply to the case of
1122    // function return.
1123
1124    // In C++ the return statement is handled via a copy initialization.
1125    // the C version of which boils down to CheckSingleAssignmentConstraints.
1126    OwningExprResult Res = PerformCopyInitialization(
1127                             InitializedEntity::InitializeResult(ReturnLoc,
1128                                                                 FnRetType),
1129                             SourceLocation(),
1130                             Owned(RetValExp));
1131    if (Res.isInvalid()) {
1132      // FIXME: Cleanup temporaries here, anyway?
1133      return StmtError();
1134    }
1135
1136    RetValExp = Res.takeAs<Expr>();
1137    if (RetValExp)
1138      CheckReturnStackAddr(RetValExp, FnRetType, ReturnLoc);
1139  }
1140
1141  return Owned(new (Context) ReturnStmt(ReturnLoc, RetValExp));
1142}
1143
1144/// IsReturnCopyElidable - Whether returning @p RetExpr from a function that
1145/// returns a @p RetType fulfills the criteria for copy elision (C++0x 12.8p15).
1146static bool IsReturnCopyElidable(ASTContext &Ctx, QualType RetType,
1147                                 Expr *RetExpr) {
1148  QualType ExprType = RetExpr->getType();
1149  // - in a return statement in a function with ...
1150  // ... a class return type ...
1151  if (!RetType->isRecordType())
1152    return false;
1153  // ... the same cv-unqualified type as the function return type ...
1154  if (!Ctx.hasSameUnqualifiedType(RetType, ExprType))
1155    return false;
1156  // ... the expression is the name of a non-volatile automatic object ...
1157  // We ignore parentheses here.
1158  // FIXME: Is this compliant?
1159  const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(RetExpr->IgnoreParens());
1160  if (!DR)
1161    return false;
1162  const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl());
1163  if (!VD)
1164    return false;
1165  return VD->hasLocalStorage() && !VD->getType()->isReferenceType()
1166    && !VD->getType().isVolatileQualified();
1167}
1168
1169Action::OwningStmtResult
1170Sema::ActOnReturnStmt(SourceLocation ReturnLoc, ExprArg rex) {
1171  Expr *RetValExp = rex.takeAs<Expr>();
1172  if (getCurBlock())
1173    return ActOnBlockReturnStmt(ReturnLoc, RetValExp);
1174
1175  QualType FnRetType;
1176  if (const FunctionDecl *FD = getCurFunctionDecl()) {
1177    FnRetType = FD->getResultType();
1178    if (FD->hasAttr<NoReturnAttr>() ||
1179        FD->getType()->getAs<FunctionType>()->getNoReturnAttr())
1180      Diag(ReturnLoc, diag::warn_noreturn_function_has_return_expr)
1181        << getCurFunctionOrMethodDecl()->getDeclName();
1182  } else if (ObjCMethodDecl *MD = getCurMethodDecl())
1183    FnRetType = MD->getResultType();
1184  else // If we don't have a function/method context, bail.
1185    return StmtError();
1186
1187  if (FnRetType->isVoidType()) {
1188    if (RetValExp && !RetValExp->isTypeDependent()) {
1189      // C99 6.8.6.4p1 (ext_ since GCC warns)
1190      unsigned D = diag::ext_return_has_expr;
1191      if (RetValExp->getType()->isVoidType())
1192        D = diag::ext_return_has_void_expr;
1193
1194      // return (some void expression); is legal in C++.
1195      if (D != diag::ext_return_has_void_expr ||
1196          !getLangOptions().CPlusPlus) {
1197        NamedDecl *CurDecl = getCurFunctionOrMethodDecl();
1198        Diag(ReturnLoc, D)
1199          << CurDecl->getDeclName() << isa<ObjCMethodDecl>(CurDecl)
1200          << RetValExp->getSourceRange();
1201      }
1202
1203      RetValExp = MaybeCreateCXXExprWithTemporaries(RetValExp);
1204    }
1205    return Owned(new (Context) ReturnStmt(ReturnLoc, RetValExp));
1206  }
1207
1208  if (!RetValExp && !FnRetType->isDependentType()) {
1209    unsigned DiagID = diag::warn_return_missing_expr;  // C90 6.6.6.4p4
1210    // C99 6.8.6.4p1 (ext_ since GCC warns)
1211    if (getLangOptions().C99) DiagID = diag::ext_return_missing_expr;
1212
1213    if (FunctionDecl *FD = getCurFunctionDecl())
1214      Diag(ReturnLoc, DiagID) << FD->getIdentifier() << 0/*fn*/;
1215    else
1216      Diag(ReturnLoc, DiagID) << getCurMethodDecl()->getDeclName() << 1/*meth*/;
1217    return Owned(new (Context) ReturnStmt(ReturnLoc, (Expr*)0));
1218  }
1219
1220  if (!FnRetType->isDependentType() && !RetValExp->isTypeDependent()) {
1221    // we have a non-void function with an expression, continue checking
1222
1223    // C99 6.8.6.4p3(136): The return statement is not an assignment. The
1224    // overlap restriction of subclause 6.5.16.1 does not apply to the case of
1225    // function return.
1226
1227    // C++0x 12.8p15: When certain criteria are met, an implementation is
1228    //   allowed to omit the copy construction of a class object, [...]
1229    //   - in a return statement in a function with a class return type, when
1230    //     the expression is the name of a non-volatile automatic object with
1231    //     the same cv-unqualified type as the function return type, the copy
1232    //     operation can be omitted [...]
1233    // C++0x 12.8p16: When the criteria for elision of a copy operation are met
1234    //   and the object to be copied is designated by an lvalue, overload
1235    //   resolution to select the constructor for the copy is first performed
1236    //   as if the object were designated by an rvalue.
1237    // Note that we only compute Elidable if we're in C++0x, since we don't
1238    // care otherwise.
1239    bool Elidable = getLangOptions().CPlusPlus0x ?
1240                      IsReturnCopyElidable(Context, FnRetType, RetValExp) :
1241                      false;
1242    // FIXME: Elidable
1243    (void)Elidable;
1244
1245    // In C++ the return statement is handled via a copy initialization.
1246    // the C version of which boils down to CheckSingleAssignmentConstraints.
1247    OwningExprResult Res = PerformCopyInitialization(
1248                             InitializedEntity::InitializeResult(ReturnLoc,
1249                                                                 FnRetType),
1250                             SourceLocation(),
1251                             Owned(RetValExp));
1252    if (Res.isInvalid()) {
1253      // FIXME: Cleanup temporaries here, anyway?
1254      return StmtError();
1255    }
1256
1257    RetValExp = Res.takeAs<Expr>();
1258    if (RetValExp)
1259      CheckReturnStackAddr(RetValExp, FnRetType, ReturnLoc);
1260  }
1261
1262  if (RetValExp)
1263    RetValExp = MaybeCreateCXXExprWithTemporaries(RetValExp);
1264  return Owned(new (Context) ReturnStmt(ReturnLoc, RetValExp));
1265}
1266
1267/// CheckAsmLValue - GNU C has an extremely ugly extension whereby they silently
1268/// ignore "noop" casts in places where an lvalue is required by an inline asm.
1269/// We emulate this behavior when -fheinous-gnu-extensions is specified, but
1270/// provide a strong guidance to not use it.
1271///
1272/// This method checks to see if the argument is an acceptable l-value and
1273/// returns false if it is a case we can handle.
1274static bool CheckAsmLValue(const Expr *E, Sema &S) {
1275  // Type dependent expressions will be checked during instantiation.
1276  if (E->isTypeDependent())
1277    return false;
1278
1279  if (E->isLvalue(S.Context) == Expr::LV_Valid)
1280    return false;  // Cool, this is an lvalue.
1281
1282  // Okay, this is not an lvalue, but perhaps it is the result of a cast that we
1283  // are supposed to allow.
1284  const Expr *E2 = E->IgnoreParenNoopCasts(S.Context);
1285  if (E != E2 && E2->isLvalue(S.Context) == Expr::LV_Valid) {
1286    if (!S.getLangOptions().HeinousExtensions)
1287      S.Diag(E2->getLocStart(), diag::err_invalid_asm_cast_lvalue)
1288        << E->getSourceRange();
1289    else
1290      S.Diag(E2->getLocStart(), diag::warn_invalid_asm_cast_lvalue)
1291        << E->getSourceRange();
1292    // Accept, even if we emitted an error diagnostic.
1293    return false;
1294  }
1295
1296  // None of the above, just randomly invalid non-lvalue.
1297  return true;
1298}
1299
1300
1301Sema::OwningStmtResult Sema::ActOnAsmStmt(SourceLocation AsmLoc,
1302                                          bool IsSimple,
1303                                          bool IsVolatile,
1304                                          unsigned NumOutputs,
1305                                          unsigned NumInputs,
1306                                          IdentifierInfo **Names,
1307                                          MultiExprArg constraints,
1308                                          MultiExprArg exprs,
1309                                          ExprArg asmString,
1310                                          MultiExprArg clobbers,
1311                                          SourceLocation RParenLoc,
1312                                          bool MSAsm) {
1313  unsigned NumClobbers = clobbers.size();
1314  StringLiteral **Constraints =
1315    reinterpret_cast<StringLiteral**>(constraints.get());
1316  Expr **Exprs = reinterpret_cast<Expr **>(exprs.get());
1317  StringLiteral *AsmString = cast<StringLiteral>((Expr *)asmString.get());
1318  StringLiteral **Clobbers = reinterpret_cast<StringLiteral**>(clobbers.get());
1319
1320  llvm::SmallVector<TargetInfo::ConstraintInfo, 4> OutputConstraintInfos;
1321
1322  // The parser verifies that there is a string literal here.
1323  if (AsmString->isWide())
1324    return StmtError(Diag(AsmString->getLocStart(),diag::err_asm_wide_character)
1325      << AsmString->getSourceRange());
1326
1327  for (unsigned i = 0; i != NumOutputs; i++) {
1328    StringLiteral *Literal = Constraints[i];
1329    if (Literal->isWide())
1330      return StmtError(Diag(Literal->getLocStart(),diag::err_asm_wide_character)
1331        << Literal->getSourceRange());
1332
1333    llvm::StringRef OutputName;
1334    if (Names[i])
1335      OutputName = Names[i]->getName();
1336
1337    TargetInfo::ConstraintInfo Info(Literal->getString(), OutputName);
1338    if (!Context.Target.validateOutputConstraint(Info))
1339      return StmtError(Diag(Literal->getLocStart(),
1340                            diag::err_asm_invalid_output_constraint)
1341                       << Info.getConstraintStr());
1342
1343    // Check that the output exprs are valid lvalues.
1344    Expr *OutputExpr = Exprs[i];
1345    if (CheckAsmLValue(OutputExpr, *this)) {
1346      return StmtError(Diag(OutputExpr->getLocStart(),
1347                  diag::err_asm_invalid_lvalue_in_output)
1348        << OutputExpr->getSourceRange());
1349    }
1350
1351    OutputConstraintInfos.push_back(Info);
1352  }
1353
1354  llvm::SmallVector<TargetInfo::ConstraintInfo, 4> InputConstraintInfos;
1355
1356  for (unsigned i = NumOutputs, e = NumOutputs + NumInputs; i != e; i++) {
1357    StringLiteral *Literal = Constraints[i];
1358    if (Literal->isWide())
1359      return StmtError(Diag(Literal->getLocStart(),diag::err_asm_wide_character)
1360        << Literal->getSourceRange());
1361
1362    llvm::StringRef InputName;
1363    if (Names[i])
1364      InputName = Names[i]->getName();
1365
1366    TargetInfo::ConstraintInfo Info(Literal->getString(), InputName);
1367    if (!Context.Target.validateInputConstraint(OutputConstraintInfos.data(),
1368                                                NumOutputs, Info)) {
1369      return StmtError(Diag(Literal->getLocStart(),
1370                            diag::err_asm_invalid_input_constraint)
1371                       << Info.getConstraintStr());
1372    }
1373
1374    Expr *InputExpr = Exprs[i];
1375
1376    // Only allow void types for memory constraints.
1377    if (Info.allowsMemory() && !Info.allowsRegister()) {
1378      if (CheckAsmLValue(InputExpr, *this))
1379        return StmtError(Diag(InputExpr->getLocStart(),
1380                              diag::err_asm_invalid_lvalue_in_input)
1381                         << Info.getConstraintStr()
1382                         << InputExpr->getSourceRange());
1383    }
1384
1385    if (Info.allowsRegister()) {
1386      if (InputExpr->getType()->isVoidType()) {
1387        return StmtError(Diag(InputExpr->getLocStart(),
1388                              diag::err_asm_invalid_type_in_input)
1389          << InputExpr->getType() << Info.getConstraintStr()
1390          << InputExpr->getSourceRange());
1391      }
1392    }
1393
1394    DefaultFunctionArrayLvalueConversion(Exprs[i]);
1395
1396    InputConstraintInfos.push_back(Info);
1397  }
1398
1399  // Check that the clobbers are valid.
1400  for (unsigned i = 0; i != NumClobbers; i++) {
1401    StringLiteral *Literal = Clobbers[i];
1402    if (Literal->isWide())
1403      return StmtError(Diag(Literal->getLocStart(),diag::err_asm_wide_character)
1404        << Literal->getSourceRange());
1405
1406    llvm::StringRef Clobber = Literal->getString();
1407
1408    if (!Context.Target.isValidGCCRegisterName(Clobber))
1409      return StmtError(Diag(Literal->getLocStart(),
1410                  diag::err_asm_unknown_register_name) << Clobber);
1411  }
1412
1413  constraints.release();
1414  exprs.release();
1415  asmString.release();
1416  clobbers.release();
1417  AsmStmt *NS =
1418    new (Context) AsmStmt(Context, AsmLoc, IsSimple, IsVolatile, MSAsm,
1419                          NumOutputs, NumInputs, Names, Constraints, Exprs,
1420                          AsmString, NumClobbers, Clobbers, RParenLoc);
1421  // Validate the asm string, ensuring it makes sense given the operands we
1422  // have.
1423  llvm::SmallVector<AsmStmt::AsmStringPiece, 8> Pieces;
1424  unsigned DiagOffs;
1425  if (unsigned DiagID = NS->AnalyzeAsmString(Pieces, Context, DiagOffs)) {
1426    Diag(getLocationOfStringLiteralByte(AsmString, DiagOffs), DiagID)
1427           << AsmString->getSourceRange();
1428    DeleteStmt(NS);
1429    return StmtError();
1430  }
1431
1432  // Validate tied input operands for type mismatches.
1433  for (unsigned i = 0, e = InputConstraintInfos.size(); i != e; ++i) {
1434    TargetInfo::ConstraintInfo &Info = InputConstraintInfos[i];
1435
1436    // If this is a tied constraint, verify that the output and input have
1437    // either exactly the same type, or that they are int/ptr operands with the
1438    // same size (int/long, int*/long, are ok etc).
1439    if (!Info.hasTiedOperand()) continue;
1440
1441    unsigned TiedTo = Info.getTiedOperand();
1442    Expr *OutputExpr = Exprs[TiedTo];
1443    Expr *InputExpr = Exprs[i+NumOutputs];
1444    QualType InTy = InputExpr->getType();
1445    QualType OutTy = OutputExpr->getType();
1446    if (Context.hasSameType(InTy, OutTy))
1447      continue;  // All types can be tied to themselves.
1448
1449    // Decide if the input and output are in the same domain (integer/ptr or
1450    // floating point.
1451    enum AsmDomain {
1452      AD_Int, AD_FP, AD_Other
1453    } InputDomain, OutputDomain;
1454
1455    if (InTy->isIntegerType() || InTy->isPointerType())
1456      InputDomain = AD_Int;
1457    else if (InTy->isFloatingType())
1458      InputDomain = AD_FP;
1459    else
1460      InputDomain = AD_Other;
1461
1462    if (OutTy->isIntegerType() || OutTy->isPointerType())
1463      OutputDomain = AD_Int;
1464    else if (OutTy->isFloatingType())
1465      OutputDomain = AD_FP;
1466    else
1467      OutputDomain = AD_Other;
1468
1469    // They are ok if they are the same size and in the same domain.  This
1470    // allows tying things like:
1471    //   void* to int*
1472    //   void* to int            if they are the same size.
1473    //   double to long double   if they are the same size.
1474    //
1475    uint64_t OutSize = Context.getTypeSize(OutTy);
1476    uint64_t InSize = Context.getTypeSize(InTy);
1477    if (OutSize == InSize && InputDomain == OutputDomain &&
1478        InputDomain != AD_Other)
1479      continue;
1480
1481    // If the smaller input/output operand is not mentioned in the asm string,
1482    // then we can promote it and the asm string won't notice.  Check this
1483    // case now.
1484    bool SmallerValueMentioned = false;
1485    for (unsigned p = 0, e = Pieces.size(); p != e; ++p) {
1486      AsmStmt::AsmStringPiece &Piece = Pieces[p];
1487      if (!Piece.isOperand()) continue;
1488
1489      // If this is a reference to the input and if the input was the smaller
1490      // one, then we have to reject this asm.
1491      if (Piece.getOperandNo() == i+NumOutputs) {
1492        if (InSize < OutSize) {
1493          SmallerValueMentioned = true;
1494          break;
1495        }
1496      }
1497
1498      // If this is a reference to the input and if the input was the smaller
1499      // one, then we have to reject this asm.
1500      if (Piece.getOperandNo() == TiedTo) {
1501        if (InSize > OutSize) {
1502          SmallerValueMentioned = true;
1503          break;
1504        }
1505      }
1506    }
1507
1508    // If the smaller value wasn't mentioned in the asm string, and if the
1509    // output was a register, just extend the shorter one to the size of the
1510    // larger one.
1511    if (!SmallerValueMentioned && InputDomain != AD_Other &&
1512        OutputConstraintInfos[TiedTo].allowsRegister())
1513      continue;
1514
1515    Diag(InputExpr->getLocStart(),
1516         diag::err_asm_tying_incompatible_types)
1517      << InTy << OutTy << OutputExpr->getSourceRange()
1518      << InputExpr->getSourceRange();
1519    DeleteStmt(NS);
1520    return StmtError();
1521  }
1522
1523  return Owned(NS);
1524}
1525
1526Action::OwningStmtResult
1527Sema::ActOnObjCAtCatchStmt(SourceLocation AtLoc,
1528                           SourceLocation RParen, DeclPtrTy Parm,
1529                           StmtArg Body, StmtArg catchList) {
1530  Stmt *CatchList = catchList.takeAs<Stmt>();
1531  ParmVarDecl *PVD = cast_or_null<ParmVarDecl>(Parm.getAs<Decl>());
1532
1533  // PVD == 0 implies @catch(...).
1534  if (PVD) {
1535    // If we already know the decl is invalid, reject it.
1536    if (PVD->isInvalidDecl())
1537      return StmtError();
1538
1539    if (!PVD->getType()->isObjCObjectPointerType())
1540      return StmtError(Diag(PVD->getLocation(),
1541                       diag::err_catch_param_not_objc_type));
1542    if (PVD->getType()->isObjCQualifiedIdType())
1543      return StmtError(Diag(PVD->getLocation(),
1544                       diag::err_illegal_qualifiers_on_catch_parm));
1545  }
1546
1547  ObjCAtCatchStmt *CS = new (Context) ObjCAtCatchStmt(AtLoc, RParen,
1548    PVD, Body.takeAs<Stmt>(), CatchList);
1549  return Owned(CatchList ? CatchList : CS);
1550}
1551
1552Action::OwningStmtResult
1553Sema::ActOnObjCAtFinallyStmt(SourceLocation AtLoc, StmtArg Body) {
1554  return Owned(new (Context) ObjCAtFinallyStmt(AtLoc,
1555                                           static_cast<Stmt*>(Body.release())));
1556}
1557
1558Action::OwningStmtResult
1559Sema::ActOnObjCAtTryStmt(SourceLocation AtLoc,
1560                         StmtArg Try, StmtArg Catch, StmtArg Finally) {
1561  FunctionNeedsScopeChecking() = true;
1562  return Owned(new (Context) ObjCAtTryStmt(AtLoc, Try.takeAs<Stmt>(),
1563                                           Catch.takeAs<Stmt>(),
1564                                           Finally.takeAs<Stmt>()));
1565}
1566
1567Sema::OwningStmtResult Sema::BuildObjCAtThrowStmt(SourceLocation AtLoc,
1568                                                  ExprArg ThrowE) {
1569  Expr *Throw = static_cast<Expr *>(ThrowE.get());
1570  if (Throw) {
1571    QualType ThrowType = Throw->getType();
1572    // Make sure the expression type is an ObjC pointer or "void *".
1573    if (!ThrowType->isDependentType() &&
1574        !ThrowType->isObjCObjectPointerType()) {
1575      const PointerType *PT = ThrowType->getAs<PointerType>();
1576      if (!PT || !PT->getPointeeType()->isVoidType())
1577        return StmtError(Diag(AtLoc, diag::error_objc_throw_expects_object)
1578                         << Throw->getType() << Throw->getSourceRange());
1579    }
1580  }
1581
1582  return Owned(new (Context) ObjCAtThrowStmt(AtLoc, ThrowE.takeAs<Expr>()));
1583}
1584
1585Action::OwningStmtResult
1586Sema::ActOnObjCAtThrowStmt(SourceLocation AtLoc, ExprArg Throw,
1587                           Scope *CurScope) {
1588  if (!Throw.get()) {
1589    // @throw without an expression designates a rethrow (which much occur
1590    // in the context of an @catch clause).
1591    Scope *AtCatchParent = CurScope;
1592    while (AtCatchParent && !AtCatchParent->isAtCatchScope())
1593      AtCatchParent = AtCatchParent->getParent();
1594    if (!AtCatchParent)
1595      return StmtError(Diag(AtLoc, diag::error_rethrow_used_outside_catch));
1596  }
1597
1598  return BuildObjCAtThrowStmt(AtLoc, move(Throw));
1599}
1600
1601Action::OwningStmtResult
1602Sema::ActOnObjCAtSynchronizedStmt(SourceLocation AtLoc, ExprArg SynchExpr,
1603                                  StmtArg SynchBody) {
1604  FunctionNeedsScopeChecking() = true;
1605
1606  // Make sure the expression type is an ObjC pointer or "void *".
1607  Expr *SyncExpr = static_cast<Expr*>(SynchExpr.get());
1608  if (!SyncExpr->getType()->isDependentType() &&
1609      !SyncExpr->getType()->isObjCObjectPointerType()) {
1610    const PointerType *PT = SyncExpr->getType()->getAs<PointerType>();
1611    if (!PT || !PT->getPointeeType()->isVoidType())
1612      return StmtError(Diag(AtLoc, diag::error_objc_synchronized_expects_object)
1613                       << SyncExpr->getType() << SyncExpr->getSourceRange());
1614  }
1615
1616  return Owned(new (Context) ObjCAtSynchronizedStmt(AtLoc,
1617                                                    SynchExpr.takeAs<Stmt>(),
1618                                                    SynchBody.takeAs<Stmt>()));
1619}
1620
1621/// ActOnCXXCatchBlock - Takes an exception declaration and a handler block
1622/// and creates a proper catch handler from them.
1623Action::OwningStmtResult
1624Sema::ActOnCXXCatchBlock(SourceLocation CatchLoc, DeclPtrTy ExDecl,
1625                         StmtArg HandlerBlock) {
1626  // There's nothing to test that ActOnExceptionDecl didn't already test.
1627  return Owned(new (Context) CXXCatchStmt(CatchLoc,
1628                                  cast_or_null<VarDecl>(ExDecl.getAs<Decl>()),
1629                                          HandlerBlock.takeAs<Stmt>()));
1630}
1631
1632class TypeWithHandler {
1633  QualType t;
1634  CXXCatchStmt *stmt;
1635public:
1636  TypeWithHandler(const QualType &type, CXXCatchStmt *statement)
1637  : t(type), stmt(statement) {}
1638
1639  // An arbitrary order is fine as long as it places identical
1640  // types next to each other.
1641  bool operator<(const TypeWithHandler &y) const {
1642    if (t.getAsOpaquePtr() < y.t.getAsOpaquePtr())
1643      return true;
1644    if (t.getAsOpaquePtr() > y.t.getAsOpaquePtr())
1645      return false;
1646    else
1647      return getTypeSpecStartLoc() < y.getTypeSpecStartLoc();
1648  }
1649
1650  bool operator==(const TypeWithHandler& other) const {
1651    return t == other.t;
1652  }
1653
1654  QualType getQualType() const { return t; }
1655  CXXCatchStmt *getCatchStmt() const { return stmt; }
1656  SourceLocation getTypeSpecStartLoc() const {
1657    return stmt->getExceptionDecl()->getTypeSpecStartLoc();
1658  }
1659};
1660
1661/// ActOnCXXTryBlock - Takes a try compound-statement and a number of
1662/// handlers and creates a try statement from them.
1663Action::OwningStmtResult
1664Sema::ActOnCXXTryBlock(SourceLocation TryLoc, StmtArg TryBlock,
1665                       MultiStmtArg RawHandlers) {
1666  unsigned NumHandlers = RawHandlers.size();
1667  assert(NumHandlers > 0 &&
1668         "The parser shouldn't call this if there are no handlers.");
1669  Stmt **Handlers = reinterpret_cast<Stmt**>(RawHandlers.get());
1670
1671  llvm::SmallVector<TypeWithHandler, 8> TypesWithHandlers;
1672
1673  for (unsigned i = 0; i < NumHandlers; ++i) {
1674    CXXCatchStmt *Handler = llvm::cast<CXXCatchStmt>(Handlers[i]);
1675    if (!Handler->getExceptionDecl()) {
1676      if (i < NumHandlers - 1)
1677        return StmtError(Diag(Handler->getLocStart(),
1678                              diag::err_early_catch_all));
1679
1680      continue;
1681    }
1682
1683    const QualType CaughtType = Handler->getCaughtType();
1684    const QualType CanonicalCaughtType = Context.getCanonicalType(CaughtType);
1685    TypesWithHandlers.push_back(TypeWithHandler(CanonicalCaughtType, Handler));
1686  }
1687
1688  // Detect handlers for the same type as an earlier one.
1689  if (NumHandlers > 1) {
1690    llvm::array_pod_sort(TypesWithHandlers.begin(), TypesWithHandlers.end());
1691
1692    TypeWithHandler prev = TypesWithHandlers[0];
1693    for (unsigned i = 1; i < TypesWithHandlers.size(); ++i) {
1694      TypeWithHandler curr = TypesWithHandlers[i];
1695
1696      if (curr == prev) {
1697        Diag(curr.getTypeSpecStartLoc(),
1698             diag::warn_exception_caught_by_earlier_handler)
1699          << curr.getCatchStmt()->getCaughtType().getAsString();
1700        Diag(prev.getTypeSpecStartLoc(),
1701             diag::note_previous_exception_handler)
1702          << prev.getCatchStmt()->getCaughtType().getAsString();
1703      }
1704
1705      prev = curr;
1706    }
1707  }
1708
1709  // FIXME: We should detect handlers that cannot catch anything because an
1710  // earlier handler catches a superclass. Need to find a method that is not
1711  // quadratic for this.
1712  // Neither of these are explicitly forbidden, but every compiler detects them
1713  // and warns.
1714
1715  FunctionNeedsScopeChecking() = true;
1716  RawHandlers.release();
1717  return Owned(CXXTryStmt::Create(Context, TryLoc,
1718                                  static_cast<Stmt*>(TryBlock.release()),
1719                                  Handlers, NumHandlers));
1720}
1721