SemaStmt.cpp revision b4eb64d8426c0eaa58d398961e0e74ff85063d7c 
1//===--- SemaStmt.cpp - Semantic Analysis for Statements ------------------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10//  This file implements semantic analysis for statements.
11//
12//===----------------------------------------------------------------------===//
13
14#include "clang/Sema/SemaInternal.h"
15#include "clang/Sema/Scope.h"
16#include "clang/Sema/ScopeInfo.h"
17#include "clang/Sema/Initialization.h"
18#include "clang/AST/APValue.h"
19#include "clang/AST/ASTContext.h"
20#include "clang/AST/DeclObjC.h"
21#include "clang/AST/ExprCXX.h"
22#include "clang/AST/ExprObjC.h"
23#include "clang/AST/StmtObjC.h"
24#include "clang/AST/StmtCXX.h"
25#include "clang/AST/TypeLoc.h"
26#include "clang/Lex/Preprocessor.h"
27#include "clang/Basic/TargetInfo.h"
28#include "llvm/ADT/STLExtras.h"
29#include "llvm/ADT/SmallVector.h"
30using namespace clang;
31using namespace sema;
32
33StmtResult Sema::ActOnExprStmt(FullExprArg expr) {
34  Expr *E = expr.get();
35  assert(E && "ActOnExprStmt(): missing expression");
36  // C99 6.8.3p2: The expression in an expression statement is evaluated as a
37  // void expression for its side effects.  Conversion to void allows any
38  // operand, even incomplete types.
39
40  // Same thing in for stmt first clause (when expr) and third clause.
41  return Owned(static_cast<Stmt*>(E));
42}
43
44
45StmtResult Sema::ActOnNullStmt(SourceLocation SemiLoc) {
46  return Owned(new (Context) NullStmt(SemiLoc));
47}
48
49StmtResult Sema::ActOnDeclStmt(DeclGroupPtrTy dg,
50                                           SourceLocation StartLoc,
51                                           SourceLocation EndLoc) {
52  DeclGroupRef DG = dg.getAsVal<DeclGroupRef>();
53
54  // If we have an invalid decl, just return an error.
55  if (DG.isNull()) return StmtError();
56
57  return Owned(new (Context) DeclStmt(DG, StartLoc, EndLoc));
58}
59
60void Sema::ActOnForEachDeclStmt(DeclGroupPtrTy dg) {
61  DeclGroupRef DG = dg.getAsVal<DeclGroupRef>();
62
63  // If we have an invalid decl, just return.
64  if (DG.isNull() || !DG.isSingleDecl()) return;
65  // suppress any potential 'unused variable' warning.
66  DG.getSingleDecl()->setUsed();
67}
68
69void Sema::DiagnoseUnusedExprResult(const Stmt *S) {
70  if (const LabelStmt *Label = dyn_cast_or_null<LabelStmt>(S))
71    return DiagnoseUnusedExprResult(Label->getSubStmt());
72
73  const Expr *E = dyn_cast_or_null<Expr>(S);
74  if (!E)
75    return;
76
77  SourceLocation Loc;
78  SourceRange R1, R2;
79  if (!E->isUnusedResultAWarning(Loc, R1, R2, Context))
80    return;
81
82  // Okay, we have an unused result.  Depending on what the base expression is,
83  // we might want to make a more specific diagnostic.  Check for one of these
84  // cases now.
85  unsigned DiagID = diag::warn_unused_expr;
86  E = E->IgnoreParens();
87  if (isa<ObjCImplicitSetterGetterRefExpr>(E))
88    DiagID = diag::warn_unused_property_expr;
89
90  if (const CXXExprWithTemporaries *Temps = dyn_cast<CXXExprWithTemporaries>(E))
91    E = Temps->getSubExpr();
92
93  if (const CallExpr *CE = dyn_cast<CallExpr>(E)) {
94    if (E->getType()->isVoidType())
95      return;
96
97    // If the callee has attribute pure, const, or warn_unused_result, warn with
98    // a more specific message to make it clear what is happening.
99    if (const Decl *FD = CE->getCalleeDecl()) {
100      if (FD->getAttr<WarnUnusedResultAttr>()) {
101        Diag(Loc, diag::warn_unused_call) << R1 << R2 << "warn_unused_result";
102        return;
103      }
104      if (FD->getAttr<PureAttr>()) {
105        Diag(Loc, diag::warn_unused_call) << R1 << R2 << "pure";
106        return;
107      }
108      if (FD->getAttr<ConstAttr>()) {
109        Diag(Loc, diag::warn_unused_call) << R1 << R2 << "const";
110        return;
111      }
112    }
113  }
114  else if (const ObjCMessageExpr *ME = dyn_cast<ObjCMessageExpr>(E)) {
115    const ObjCMethodDecl *MD = ME->getMethodDecl();
116    if (MD && MD->getAttr<WarnUnusedResultAttr>()) {
117      Diag(Loc, diag::warn_unused_call) << R1 << R2 << "warn_unused_result";
118      return;
119    }
120  } else if (const CXXFunctionalCastExpr *FC
121                                       = dyn_cast<CXXFunctionalCastExpr>(E)) {
122    if (isa<CXXConstructExpr>(FC->getSubExpr()) ||
123        isa<CXXTemporaryObjectExpr>(FC->getSubExpr()))
124      return;
125  }
126  // Diagnose "(void*) blah" as a typo for "(void) blah".
127  else if (const CStyleCastExpr *CE = dyn_cast<CStyleCastExpr>(E)) {
128    TypeSourceInfo *TI = CE->getTypeInfoAsWritten();
129    QualType T = TI->getType();
130
131    // We really do want to use the non-canonical type here.
132    if (T == Context.VoidPtrTy) {
133      PointerTypeLoc TL = cast<PointerTypeLoc>(TI->getTypeLoc());
134
135      Diag(Loc, diag::warn_unused_voidptr)
136        << FixItHint::CreateRemoval(TL.getStarLoc());
137      return;
138    }
139  }
140
141  DiagRuntimeBehavior(Loc, PDiag(DiagID) << R1 << R2);
142}
143
144StmtResult
145Sema::ActOnCompoundStmt(SourceLocation L, SourceLocation R,
146                        MultiStmtArg elts, bool isStmtExpr) {
147  unsigned NumElts = elts.size();
148  Stmt **Elts = reinterpret_cast<Stmt**>(elts.release());
149  // If we're in C89 mode, check that we don't have any decls after stmts.  If
150  // so, emit an extension diagnostic.
151  if (!getLangOptions().C99 && !getLangOptions().CPlusPlus) {
152    // Note that __extension__ can be around a decl.
153    unsigned i = 0;
154    // Skip over all declarations.
155    for (; i != NumElts && isa<DeclStmt>(Elts[i]); ++i)
156      /*empty*/;
157
158    // We found the end of the list or a statement.  Scan for another declstmt.
159    for (; i != NumElts && !isa<DeclStmt>(Elts[i]); ++i)
160      /*empty*/;
161
162    if (i != NumElts) {
163      Decl *D = *cast<DeclStmt>(Elts[i])->decl_begin();
164      Diag(D->getLocation(), diag::ext_mixed_decls_code);
165    }
166  }
167  // Warn about unused expressions in statements.
168  for (unsigned i = 0; i != NumElts; ++i) {
169    // Ignore statements that are last in a statement expression.
170    if (isStmtExpr && i == NumElts - 1)
171      continue;
172
173    DiagnoseUnusedExprResult(Elts[i]);
174  }
175
176  return Owned(new (Context) CompoundStmt(Context, Elts, NumElts, L, R));
177}
178
179StmtResult
180Sema::ActOnCaseStmt(SourceLocation CaseLoc, Expr *LHSVal,
181                    SourceLocation DotDotDotLoc, Expr *RHSVal,
182                    SourceLocation ColonLoc) {
183  assert((LHSVal != 0) && "missing expression in case statement");
184
185  // C99 6.8.4.2p3: The expression shall be an integer constant.
186  // However, GCC allows any evaluatable integer expression.
187  if (!LHSVal->isTypeDependent() && !LHSVal->isValueDependent() &&
188      VerifyIntegerConstantExpression(LHSVal))
189    return StmtError();
190
191  // GCC extension: The expression shall be an integer constant.
192
193  if (RHSVal && !RHSVal->isTypeDependent() && !RHSVal->isValueDependent() &&
194      VerifyIntegerConstantExpression(RHSVal)) {
195    RHSVal = 0;  // Recover by just forgetting about it.
196  }
197
198  if (getCurFunction()->SwitchStack.empty()) {
199    Diag(CaseLoc, diag::err_case_not_in_switch);
200    return StmtError();
201  }
202
203  CaseStmt *CS = new (Context) CaseStmt(LHSVal, RHSVal, CaseLoc, DotDotDotLoc,
204                                        ColonLoc);
205  getCurFunction()->SwitchStack.back()->addSwitchCase(CS);
206  return Owned(CS);
207}
208
209/// ActOnCaseStmtBody - This installs a statement as the body of a case.
210void Sema::ActOnCaseStmtBody(Stmt *caseStmt, Stmt *SubStmt) {
211  CaseStmt *CS = static_cast<CaseStmt*>(caseStmt);
212  CS->setSubStmt(SubStmt);
213}
214
215StmtResult
216Sema::ActOnDefaultStmt(SourceLocation DefaultLoc, SourceLocation ColonLoc,
217                       Stmt *SubStmt, Scope *CurScope) {
218  if (getCurFunction()->SwitchStack.empty()) {
219    Diag(DefaultLoc, diag::err_default_not_in_switch);
220    return Owned(SubStmt);
221  }
222
223  DefaultStmt *DS = new (Context) DefaultStmt(DefaultLoc, ColonLoc, SubStmt);
224  getCurFunction()->SwitchStack.back()->addSwitchCase(DS);
225  return Owned(DS);
226}
227
228StmtResult
229Sema::ActOnLabelStmt(SourceLocation IdentLoc, IdentifierInfo *II,
230                     SourceLocation ColonLoc, Stmt *SubStmt,
231                     const AttributeList *Attr) {
232  // According to GCC docs, "the only attribute that makes sense after a label
233  // is 'unused'".
234  bool HasUnusedAttr = false;
235  llvm::OwningPtr<const AttributeList> AttrList(Attr);
236  for (const AttributeList* a = AttrList.get(); a; a = a->getNext()) {
237    if (a->getKind() == AttributeList::AT_unused) {
238      HasUnusedAttr = true;
239    } else {
240      Diag(a->getLoc(), diag::warn_label_attribute_not_unused);
241      a->setInvalid(true);
242    }
243  }
244
245  return ActOnLabelStmt(IdentLoc, II, ColonLoc, SubStmt, HasUnusedAttr);
246}
247
248StmtResult
249Sema::ActOnLabelStmt(SourceLocation IdentLoc, IdentifierInfo *II,
250                     SourceLocation ColonLoc, Stmt *SubStmt,
251                     bool HasUnusedAttr) {
252  // Look up the record for this label identifier.
253  LabelStmt *&LabelDecl = getCurFunction()->LabelMap[II];
254
255  // If not forward referenced or defined already, just create a new LabelStmt.
256  if (LabelDecl == 0)
257    return Owned(LabelDecl = new (Context) LabelStmt(IdentLoc, II, SubStmt,
258                                                     HasUnusedAttr));
259
260  assert(LabelDecl->getID() == II && "Label mismatch!");
261
262  // Otherwise, this label was either forward reference or multiply defined.  If
263  // multiply defined, reject it now.
264  if (LabelDecl->getSubStmt()) {
265    Diag(IdentLoc, diag::err_redefinition_of_label) << LabelDecl->getID();
266    Diag(LabelDecl->getIdentLoc(), diag::note_previous_definition);
267    return Owned(SubStmt);
268  }
269
270  // Otherwise, this label was forward declared, and we just found its real
271  // definition.  Fill in the forward definition and return it.
272  LabelDecl->setIdentLoc(IdentLoc);
273  LabelDecl->setSubStmt(SubStmt);
274  LabelDecl->setUnusedAttribute(HasUnusedAttr);
275  return Owned(LabelDecl);
276}
277
278StmtResult
279Sema::ActOnIfStmt(SourceLocation IfLoc, FullExprArg CondVal, Decl *CondVar,
280                  Stmt *thenStmt, SourceLocation ElseLoc,
281                  Stmt *elseStmt) {
282  ExprResult CondResult(CondVal.release());
283
284  VarDecl *ConditionVar = 0;
285  if (CondVar) {
286    ConditionVar = cast<VarDecl>(CondVar);
287    CondResult = CheckConditionVariable(ConditionVar, IfLoc, true);
288    if (CondResult.isInvalid())
289      return StmtError();
290  }
291  Expr *ConditionExpr = CondResult.takeAs<Expr>();
292  if (!ConditionExpr)
293    return StmtError();
294
295  DiagnoseUnusedExprResult(thenStmt);
296
297  // Warn if the if block has a null body without an else value.
298  // this helps prevent bugs due to typos, such as
299  // if (condition);
300  //   do_stuff();
301  //
302  // NOTE: Do not emit this warning if the body is expanded from a macro.
303  if (!elseStmt) {
304    if (NullStmt* stmt = dyn_cast<NullStmt>(thenStmt))
305      if (!stmt->getLocStart().isMacroID())
306        Diag(stmt->getSemiLoc(), diag::warn_empty_if_body);
307  }
308
309  DiagnoseUnusedExprResult(elseStmt);
310
311  return Owned(new (Context) IfStmt(Context, IfLoc, ConditionVar, ConditionExpr,
312                                    thenStmt, ElseLoc, elseStmt));
313}
314
315/// ConvertIntegerToTypeWarnOnOverflow - Convert the specified APInt to have
316/// the specified width and sign.  If an overflow occurs, detect it and emit
317/// the specified diagnostic.
318void Sema::ConvertIntegerToTypeWarnOnOverflow(llvm::APSInt &Val,
319                                              unsigned NewWidth, bool NewSign,
320                                              SourceLocation Loc,
321                                              unsigned DiagID) {
322  // Perform a conversion to the promoted condition type if needed.
323  if (NewWidth > Val.getBitWidth()) {
324    // If this is an extension, just do it.
325    Val.extend(NewWidth);
326    Val.setIsSigned(NewSign);
327
328    // If the input was signed and negative and the output is
329    // unsigned, don't bother to warn: this is implementation-defined
330    // behavior.
331    // FIXME: Introduce a second, default-ignored warning for this case?
332  } else if (NewWidth < Val.getBitWidth()) {
333    // If this is a truncation, check for overflow.
334    llvm::APSInt ConvVal(Val);
335    ConvVal.trunc(NewWidth);
336    ConvVal.setIsSigned(NewSign);
337    ConvVal.extend(Val.getBitWidth());
338    ConvVal.setIsSigned(Val.isSigned());
339    if (ConvVal != Val)
340      Diag(Loc, DiagID) << Val.toString(10) << ConvVal.toString(10);
341
342    // Regardless of whether a diagnostic was emitted, really do the
343    // truncation.
344    Val.trunc(NewWidth);
345    Val.setIsSigned(NewSign);
346  } else if (NewSign != Val.isSigned()) {
347    // Convert the sign to match the sign of the condition.  This can cause
348    // overflow as well: unsigned(INTMIN)
349    // We don't diagnose this overflow, because it is implementation-defined
350    // behavior.
351    // FIXME: Introduce a second, default-ignored warning for this case?
352    llvm::APSInt OldVal(Val);
353    Val.setIsSigned(NewSign);
354  }
355}
356
357namespace {
358  struct CaseCompareFunctor {
359    bool operator()(const std::pair<llvm::APSInt, CaseStmt*> &LHS,
360                    const llvm::APSInt &RHS) {
361      return LHS.first < RHS;
362    }
363    bool operator()(const std::pair<llvm::APSInt, CaseStmt*> &LHS,
364                    const std::pair<llvm::APSInt, CaseStmt*> &RHS) {
365      return LHS.first < RHS.first;
366    }
367    bool operator()(const llvm::APSInt &LHS,
368                    const std::pair<llvm::APSInt, CaseStmt*> &RHS) {
369      return LHS < RHS.first;
370    }
371  };
372}
373
374/// CmpCaseVals - Comparison predicate for sorting case values.
375///
376static bool CmpCaseVals(const std::pair<llvm::APSInt, CaseStmt*>& lhs,
377                        const std::pair<llvm::APSInt, CaseStmt*>& rhs) {
378  if (lhs.first < rhs.first)
379    return true;
380
381  if (lhs.first == rhs.first &&
382      lhs.second->getCaseLoc().getRawEncoding()
383       < rhs.second->getCaseLoc().getRawEncoding())
384    return true;
385  return false;
386}
387
388/// CmpEnumVals - Comparison predicate for sorting enumeration values.
389///
390static bool CmpEnumVals(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/// EqEnumVals - Comparison preficate for uniqing enumeration values.
397///
398static bool EqEnumVals(const std::pair<llvm::APSInt, EnumConstantDecl*>& lhs,
399                       const std::pair<llvm::APSInt, EnumConstantDecl*>& rhs)
400{
401  return lhs.first == rhs.first;
402}
403
404/// GetTypeBeforeIntegralPromotion - Returns the pre-promotion type of
405/// potentially integral-promoted expression @p expr.
406static QualType GetTypeBeforeIntegralPromotion(const Expr* expr) {
407  if (const CastExpr *ImplicitCast = dyn_cast<ImplicitCastExpr>(expr)) {
408    const Expr *ExprBeforePromotion = ImplicitCast->getSubExpr();
409    QualType TypeBeforePromotion = ExprBeforePromotion->getType();
410    if (TypeBeforePromotion->isIntegralOrEnumerationType()) {
411      return TypeBeforePromotion;
412    }
413  }
414  return expr->getType();
415}
416
417StmtResult
418Sema::ActOnStartOfSwitchStmt(SourceLocation SwitchLoc, Expr *Cond,
419                             Decl *CondVar) {
420  ExprResult CondResult;
421
422  VarDecl *ConditionVar = 0;
423  if (CondVar) {
424    ConditionVar = cast<VarDecl>(CondVar);
425    CondResult = CheckConditionVariable(ConditionVar, SourceLocation(), false);
426    if (CondResult.isInvalid())
427      return StmtError();
428
429    Cond = CondResult.release();
430  }
431
432  if (!Cond)
433    return StmtError();
434
435  CondResult
436    = ConvertToIntegralOrEnumerationType(SwitchLoc, Cond,
437                          PDiag(diag::err_typecheck_statement_requires_integer),
438                                   PDiag(diag::err_switch_incomplete_class_type)
439                                     << Cond->getSourceRange(),
440                                   PDiag(diag::err_switch_explicit_conversion),
441                                         PDiag(diag::note_switch_conversion),
442                                   PDiag(diag::err_switch_multiple_conversions),
443                                         PDiag(diag::note_switch_conversion),
444                                         PDiag(0));
445  if (CondResult.isInvalid()) return StmtError();
446  Cond = CondResult.take();
447
448  if (!CondVar) {
449    CheckImplicitConversions(Cond, SwitchLoc);
450    CondResult = MaybeCreateCXXExprWithTemporaries(Cond);
451    if (CondResult.isInvalid())
452      return StmtError();
453    Cond = CondResult.take();
454  }
455
456  getCurFunction()->setHasBranchIntoScope();
457
458  SwitchStmt *SS = new (Context) SwitchStmt(Context, ConditionVar, Cond);
459  getCurFunction()->SwitchStack.push_back(SS);
460  return Owned(SS);
461}
462
463static void AdjustAPSInt(llvm::APSInt &Val, unsigned BitWidth, bool IsSigned) {
464  if (Val.getBitWidth() < BitWidth)
465    Val.extend(BitWidth);
466  else if (Val.getBitWidth() > BitWidth)
467    Val.trunc(BitWidth);
468  Val.setIsSigned(IsSigned);
469}
470
471StmtResult
472Sema::ActOnFinishSwitchStmt(SourceLocation SwitchLoc, Stmt *Switch,
473                            Stmt *BodyStmt) {
474  SwitchStmt *SS = cast<SwitchStmt>(Switch);
475  assert(SS == getCurFunction()->SwitchStack.back() &&
476         "switch stack missing push/pop!");
477
478  SS->setBody(BodyStmt, SwitchLoc);
479  getCurFunction()->SwitchStack.pop_back();
480
481  if (SS->getCond() == 0)
482    return StmtError();
483
484  Expr *CondExpr = SS->getCond();
485  Expr *CondExprBeforePromotion = CondExpr;
486  QualType CondTypeBeforePromotion =
487      GetTypeBeforeIntegralPromotion(CondExpr);
488
489  // C99 6.8.4.2p5 - Integer promotions are performed on the controlling expr.
490  UsualUnaryConversions(CondExpr);
491  QualType CondType = CondExpr->getType();
492  SS->setCond(CondExpr);
493
494  // C++ 6.4.2.p2:
495  // Integral promotions are performed (on the switch condition).
496  //
497  // A case value unrepresentable by the original switch condition
498  // type (before the promotion) doesn't make sense, even when it can
499  // be represented by the promoted type.  Therefore we need to find
500  // the pre-promotion type of the switch condition.
501  if (!CondExpr->isTypeDependent()) {
502    // We have already converted the expression to an integral or enumeration
503    // type, when we started the switch statement. If we don't have an
504    // appropriate type now, just return an error.
505    if (!CondType->isIntegralOrEnumerationType())
506      return StmtError();
507
508    if (CondExpr->isKnownToHaveBooleanValue()) {
509      // switch(bool_expr) {...} is often a programmer error, e.g.
510      //   switch(n && mask) { ... }  // Doh - should be "n & mask".
511      // One can always use an if statement instead of switch(bool_expr).
512      Diag(SwitchLoc, diag::warn_bool_switch_condition)
513          << CondExpr->getSourceRange();
514    }
515  }
516
517  // Get the bitwidth of the switched-on value before promotions.  We must
518  // convert the integer case values to this width before comparison.
519  bool HasDependentValue
520    = CondExpr->isTypeDependent() || CondExpr->isValueDependent();
521  unsigned CondWidth
522    = HasDependentValue? 0
523      : static_cast<unsigned>(Context.getTypeSize(CondTypeBeforePromotion));
524  bool CondIsSigned = CondTypeBeforePromotion->isSignedIntegerType();
525
526  // Accumulate all of the case values in a vector so that we can sort them
527  // and detect duplicates.  This vector contains the APInt for the case after
528  // it has been converted to the condition type.
529  typedef llvm::SmallVector<std::pair<llvm::APSInt, CaseStmt*>, 64> CaseValsTy;
530  CaseValsTy CaseVals;
531
532  // Keep track of any GNU case ranges we see.  The APSInt is the low value.
533  typedef std::vector<std::pair<llvm::APSInt, CaseStmt*> > CaseRangesTy;
534  CaseRangesTy CaseRanges;
535
536  DefaultStmt *TheDefaultStmt = 0;
537
538  bool CaseListIsErroneous = false;
539
540  for (SwitchCase *SC = SS->getSwitchCaseList(); SC && !HasDependentValue;
541       SC = SC->getNextSwitchCase()) {
542
543    if (DefaultStmt *DS = dyn_cast<DefaultStmt>(SC)) {
544      if (TheDefaultStmt) {
545        Diag(DS->getDefaultLoc(), diag::err_multiple_default_labels_defined);
546        Diag(TheDefaultStmt->getDefaultLoc(), diag::note_duplicate_case_prev);
547
548        // FIXME: Remove the default statement from the switch block so that
549        // we'll return a valid AST.  This requires recursing down the AST and
550        // finding it, not something we are set up to do right now.  For now,
551        // just lop the entire switch stmt out of the AST.
552        CaseListIsErroneous = true;
553      }
554      TheDefaultStmt = DS;
555
556    } else {
557      CaseStmt *CS = cast<CaseStmt>(SC);
558
559      // We already verified that the expression has a i-c-e value (C99
560      // 6.8.4.2p3) - get that value now.
561      Expr *Lo = CS->getLHS();
562
563      if (Lo->isTypeDependent() || Lo->isValueDependent()) {
564        HasDependentValue = true;
565        break;
566      }
567
568      llvm::APSInt LoVal = Lo->EvaluateAsInt(Context);
569
570      // Convert the value to the same width/sign as the condition.
571      ConvertIntegerToTypeWarnOnOverflow(LoVal, CondWidth, CondIsSigned,
572                                         Lo->getLocStart(),
573                                         diag::warn_case_value_overflow);
574
575      // If the LHS is not the same type as the condition, insert an implicit
576      // cast.
577      ImpCastExprToType(Lo, CondType, CK_IntegralCast);
578      CS->setLHS(Lo);
579
580      // If this is a case range, remember it in CaseRanges, otherwise CaseVals.
581      if (CS->getRHS()) {
582        if (CS->getRHS()->isTypeDependent() ||
583            CS->getRHS()->isValueDependent()) {
584          HasDependentValue = true;
585          break;
586        }
587        CaseRanges.push_back(std::make_pair(LoVal, CS));
588      } else
589        CaseVals.push_back(std::make_pair(LoVal, CS));
590    }
591  }
592
593  if (!HasDependentValue) {
594    // If we don't have a default statement, check whether the
595    // condition is constant.
596    llvm::APSInt ConstantCondValue;
597    bool HasConstantCond = false;
598    bool ShouldCheckConstantCond = false;
599    if (!HasDependentValue && !TheDefaultStmt) {
600      Expr::EvalResult Result;
601      HasConstantCond = CondExprBeforePromotion->Evaluate(Result, Context);
602      if (HasConstantCond) {
603        assert(Result.Val.isInt() && "switch condition evaluated to non-int");
604        ConstantCondValue = Result.Val.getInt();
605        ShouldCheckConstantCond = true;
606
607        assert(ConstantCondValue.getBitWidth() == CondWidth &&
608               ConstantCondValue.isSigned() == CondIsSigned);
609      }
610    }
611
612    // Sort all the scalar case values so we can easily detect duplicates.
613    std::stable_sort(CaseVals.begin(), CaseVals.end(), CmpCaseVals);
614
615    if (!CaseVals.empty()) {
616      for (unsigned i = 0, e = CaseVals.size(); i != e; ++i) {
617        if (ShouldCheckConstantCond &&
618            CaseVals[i].first == ConstantCondValue)
619          ShouldCheckConstantCond = false;
620
621        if (i != 0 && CaseVals[i].first == CaseVals[i-1].first) {
622          // If we have a duplicate, report it.
623          Diag(CaseVals[i].second->getLHS()->getLocStart(),
624               diag::err_duplicate_case) << CaseVals[i].first.toString(10);
625          Diag(CaseVals[i-1].second->getLHS()->getLocStart(),
626               diag::note_duplicate_case_prev);
627          // FIXME: We really want to remove the bogus case stmt from the
628          // substmt, but we have no way to do this right now.
629          CaseListIsErroneous = true;
630        }
631      }
632    }
633
634    // Detect duplicate case ranges, which usually don't exist at all in
635    // the first place.
636    if (!CaseRanges.empty()) {
637      // Sort all the case ranges by their low value so we can easily detect
638      // overlaps between ranges.
639      std::stable_sort(CaseRanges.begin(), CaseRanges.end());
640
641      // Scan the ranges, computing the high values and removing empty ranges.
642      std::vector<llvm::APSInt> HiVals;
643      for (unsigned i = 0, e = CaseRanges.size(); i != e; ++i) {
644        llvm::APSInt &LoVal = CaseRanges[i].first;
645        CaseStmt *CR = CaseRanges[i].second;
646        Expr *Hi = CR->getRHS();
647        llvm::APSInt HiVal = Hi->EvaluateAsInt(Context);
648
649        // Convert the value to the same width/sign as the condition.
650        ConvertIntegerToTypeWarnOnOverflow(HiVal, CondWidth, CondIsSigned,
651                                           Hi->getLocStart(),
652                                           diag::warn_case_value_overflow);
653
654        // If the LHS is not the same type as the condition, insert an implicit
655        // cast.
656        ImpCastExprToType(Hi, CondType, CK_IntegralCast);
657        CR->setRHS(Hi);
658
659        // If the low value is bigger than the high value, the case is empty.
660        if (LoVal > HiVal) {
661          Diag(CR->getLHS()->getLocStart(), diag::warn_case_empty_range)
662            << SourceRange(CR->getLHS()->getLocStart(),
663                           Hi->getLocEnd());
664          CaseRanges.erase(CaseRanges.begin()+i);
665          --i, --e;
666          continue;
667        }
668
669        if (ShouldCheckConstantCond &&
670            LoVal <= ConstantCondValue &&
671            ConstantCondValue <= HiVal)
672          ShouldCheckConstantCond = false;
673
674        HiVals.push_back(HiVal);
675      }
676
677      // Rescan the ranges, looking for overlap with singleton values and other
678      // ranges.  Since the range list is sorted, we only need to compare case
679      // ranges with their neighbors.
680      for (unsigned i = 0, e = CaseRanges.size(); i != e; ++i) {
681        llvm::APSInt &CRLo = CaseRanges[i].first;
682        llvm::APSInt &CRHi = HiVals[i];
683        CaseStmt *CR = CaseRanges[i].second;
684
685        // Check to see whether the case range overlaps with any
686        // singleton cases.
687        CaseStmt *OverlapStmt = 0;
688        llvm::APSInt OverlapVal(32);
689
690        // Find the smallest value >= the lower bound.  If I is in the
691        // case range, then we have overlap.
692        CaseValsTy::iterator I = std::lower_bound(CaseVals.begin(),
693                                                  CaseVals.end(), CRLo,
694                                                  CaseCompareFunctor());
695        if (I != CaseVals.end() && I->first < CRHi) {
696          OverlapVal  = I->first;   // Found overlap with scalar.
697          OverlapStmt = I->second;
698        }
699
700        // Find the smallest value bigger than the upper bound.
701        I = std::upper_bound(I, CaseVals.end(), CRHi, CaseCompareFunctor());
702        if (I != CaseVals.begin() && (I-1)->first >= CRLo) {
703          OverlapVal  = (I-1)->first;      // Found overlap with scalar.
704          OverlapStmt = (I-1)->second;
705        }
706
707        // Check to see if this case stmt overlaps with the subsequent
708        // case range.
709        if (i && CRLo <= HiVals[i-1]) {
710          OverlapVal  = HiVals[i-1];       // Found overlap with range.
711          OverlapStmt = CaseRanges[i-1].second;
712        }
713
714        if (OverlapStmt) {
715          // If we have a duplicate, report it.
716          Diag(CR->getLHS()->getLocStart(), diag::err_duplicate_case)
717            << OverlapVal.toString(10);
718          Diag(OverlapStmt->getLHS()->getLocStart(),
719               diag::note_duplicate_case_prev);
720          // FIXME: We really want to remove the bogus case stmt from the
721          // substmt, but we have no way to do this right now.
722          CaseListIsErroneous = true;
723        }
724      }
725    }
726
727    // Complain if we have a constant condition and we didn't find a match.
728    if (!CaseListIsErroneous && ShouldCheckConstantCond) {
729      // TODO: it would be nice if we printed enums as enums, chars as
730      // chars, etc.
731      Diag(CondExpr->getExprLoc(), diag::warn_missing_case_for_condition)
732        << ConstantCondValue.toString(10)
733        << CondExpr->getSourceRange();
734    }
735
736    // Check to see if switch is over an Enum and handles all of its
737    // values.  We only issue a warning if there is not 'default:', but
738    // we still do the analysis to preserve this information in the AST
739    // (which can be used by flow-based analyes).
740    //
741    const EnumType *ET = CondTypeBeforePromotion->getAs<EnumType>();
742
743    // If switch has default case, then ignore it.
744    if (!CaseListIsErroneous  && !HasConstantCond && ET) {
745      const EnumDecl *ED = ET->getDecl();
746      typedef llvm::SmallVector<std::pair<llvm::APSInt, EnumConstantDecl*>, 64> EnumValsTy;
747      EnumValsTy EnumVals;
748
749      // Gather all enum values, set their type and sort them,
750      // allowing easier comparison with CaseVals.
751      for (EnumDecl::enumerator_iterator EDI = ED->enumerator_begin();
752           EDI != ED->enumerator_end(); ++EDI) {
753        llvm::APSInt Val = EDI->getInitVal();
754        AdjustAPSInt(Val, CondWidth, CondIsSigned);
755        EnumVals.push_back(std::make_pair(Val, *EDI));
756      }
757      std::stable_sort(EnumVals.begin(), EnumVals.end(), CmpEnumVals);
758      EnumValsTy::iterator EIend =
759        std::unique(EnumVals.begin(), EnumVals.end(), EqEnumVals);
760
761      // See which case values aren't in enum.
762      // TODO: we might want to check whether case values are out of the
763      // enum even if we don't want to check whether all cases are handled.
764      if (!TheDefaultStmt) {
765        EnumValsTy::const_iterator EI = EnumVals.begin();
766        for (CaseValsTy::const_iterator CI = CaseVals.begin();
767             CI != CaseVals.end(); CI++) {
768          while (EI != EIend && EI->first < CI->first)
769            EI++;
770          if (EI == EIend || EI->first > CI->first)
771            Diag(CI->second->getLHS()->getExprLoc(), diag::warn_not_in_enum)
772              << ED->getDeclName();
773        }
774        // See which of case ranges aren't in enum
775        EI = EnumVals.begin();
776        for (CaseRangesTy::const_iterator RI = CaseRanges.begin();
777             RI != CaseRanges.end() && EI != EIend; RI++) {
778          while (EI != EIend && EI->first < RI->first)
779            EI++;
780
781          if (EI == EIend || EI->first != RI->first) {
782            Diag(RI->second->getLHS()->getExprLoc(), diag::warn_not_in_enum)
783              << ED->getDeclName();
784          }
785
786          llvm::APSInt Hi = RI->second->getRHS()->EvaluateAsInt(Context);
787          AdjustAPSInt(Hi, CondWidth, CondIsSigned);
788          while (EI != EIend && EI->first < Hi)
789            EI++;
790          if (EI == EIend || EI->first != Hi)
791            Diag(RI->second->getRHS()->getExprLoc(), diag::warn_not_in_enum)
792              << ED->getDeclName();
793        }
794      }
795
796      // Check which enum vals aren't in switch
797      CaseValsTy::const_iterator CI = CaseVals.begin();
798      CaseRangesTy::const_iterator RI = CaseRanges.begin();
799      bool hasCasesNotInSwitch = false;
800
801      llvm::SmallVector<DeclarationName,8> UnhandledNames;
802
803      for (EnumValsTy::const_iterator EI = EnumVals.begin(); EI != EIend; EI++){
804        // Drop unneeded case values
805        llvm::APSInt CIVal;
806        while (CI != CaseVals.end() && CI->first < EI->first)
807          CI++;
808
809        if (CI != CaseVals.end() && CI->first == EI->first)
810          continue;
811
812        // Drop unneeded case ranges
813        for (; RI != CaseRanges.end(); RI++) {
814          llvm::APSInt Hi = RI->second->getRHS()->EvaluateAsInt(Context);
815          AdjustAPSInt(Hi, CondWidth, CondIsSigned);
816          if (EI->first <= Hi)
817            break;
818        }
819
820        if (RI == CaseRanges.end() || EI->first < RI->first) {
821          hasCasesNotInSwitch = true;
822          if (!TheDefaultStmt)
823            UnhandledNames.push_back(EI->second->getDeclName());
824        }
825      }
826
827      // Produce a nice diagnostic if multiple values aren't handled.
828      switch (UnhandledNames.size()) {
829      case 0: break;
830      case 1:
831        Diag(CondExpr->getExprLoc(), diag::warn_missing_case1)
832          << UnhandledNames[0];
833        break;
834      case 2:
835        Diag(CondExpr->getExprLoc(), diag::warn_missing_case2)
836          << UnhandledNames[0] << UnhandledNames[1];
837        break;
838      case 3:
839        Diag(CondExpr->getExprLoc(), diag::warn_missing_case3)
840          << UnhandledNames[0] << UnhandledNames[1] << UnhandledNames[2];
841        break;
842      default:
843        Diag(CondExpr->getExprLoc(), diag::warn_missing_cases)
844          << (unsigned)UnhandledNames.size()
845          << UnhandledNames[0] << UnhandledNames[1] << UnhandledNames[2];
846        break;
847      }
848
849      if (!hasCasesNotInSwitch)
850        SS->setAllEnumCasesCovered();
851    }
852  }
853
854  // FIXME: If the case list was broken is some way, we don't have a good system
855  // to patch it up.  Instead, just return the whole substmt as broken.
856  if (CaseListIsErroneous)
857    return StmtError();
858
859  return Owned(SS);
860}
861
862StmtResult
863Sema::ActOnWhileStmt(SourceLocation WhileLoc, FullExprArg Cond,
864                     Decl *CondVar, Stmt *Body) {
865  ExprResult CondResult(Cond.release());
866
867  VarDecl *ConditionVar = 0;
868  if (CondVar) {
869    ConditionVar = cast<VarDecl>(CondVar);
870    CondResult = CheckConditionVariable(ConditionVar, WhileLoc, true);
871    if (CondResult.isInvalid())
872      return StmtError();
873  }
874  Expr *ConditionExpr = CondResult.take();
875  if (!ConditionExpr)
876    return StmtError();
877
878  DiagnoseUnusedExprResult(Body);
879
880  return Owned(new (Context) WhileStmt(Context, ConditionVar, ConditionExpr,
881                                       Body, WhileLoc));
882}
883
884StmtResult
885Sema::ActOnDoStmt(SourceLocation DoLoc, Stmt *Body,
886                  SourceLocation WhileLoc, SourceLocation CondLParen,
887                  Expr *Cond, SourceLocation CondRParen) {
888  assert(Cond && "ActOnDoStmt(): missing expression");
889
890  if (CheckBooleanCondition(Cond, DoLoc))
891    return StmtError();
892
893  CheckImplicitConversions(Cond, DoLoc);
894  ExprResult CondResult = MaybeCreateCXXExprWithTemporaries(Cond);
895  if (CondResult.isInvalid())
896    return StmtError();
897  Cond = CondResult.take();
898
899  DiagnoseUnusedExprResult(Body);
900
901  return Owned(new (Context) DoStmt(Body, Cond, DoLoc, WhileLoc, CondRParen));
902}
903
904StmtResult
905Sema::ActOnForStmt(SourceLocation ForLoc, SourceLocation LParenLoc,
906                   Stmt *First, FullExprArg second, Decl *secondVar,
907                   FullExprArg third,
908                   SourceLocation RParenLoc, Stmt *Body) {
909  if (!getLangOptions().CPlusPlus) {
910    if (DeclStmt *DS = dyn_cast_or_null<DeclStmt>(First)) {
911      // C99 6.8.5p3: The declaration part of a 'for' statement shall only
912      // declare identifiers for objects having storage class 'auto' or
913      // 'register'.
914      for (DeclStmt::decl_iterator DI=DS->decl_begin(), DE=DS->decl_end();
915           DI!=DE; ++DI) {
916        VarDecl *VD = dyn_cast<VarDecl>(*DI);
917        if (VD && VD->isBlockVarDecl() && !VD->hasLocalStorage())
918          VD = 0;
919        if (VD == 0)
920          Diag((*DI)->getLocation(), diag::err_non_variable_decl_in_for);
921        // FIXME: mark decl erroneous!
922      }
923    }
924  }
925
926  ExprResult SecondResult(second.release());
927  VarDecl *ConditionVar = 0;
928  if (secondVar) {
929    ConditionVar = cast<VarDecl>(secondVar);
930    SecondResult = CheckConditionVariable(ConditionVar, ForLoc, true);
931    if (SecondResult.isInvalid())
932      return StmtError();
933  }
934
935  Expr *Third  = third.release().takeAs<Expr>();
936
937  DiagnoseUnusedExprResult(First);
938  DiagnoseUnusedExprResult(Third);
939  DiagnoseUnusedExprResult(Body);
940
941  return Owned(new (Context) ForStmt(Context, First,
942                                     SecondResult.take(), ConditionVar,
943                                     Third, Body, ForLoc, LParenLoc,
944                                     RParenLoc));
945}
946
947StmtResult
948Sema::ActOnObjCForCollectionStmt(SourceLocation ForLoc,
949                                 SourceLocation LParenLoc,
950                                 Stmt *First, Expr *Second,
951                                 SourceLocation RParenLoc, Stmt *Body) {
952  if (First) {
953    QualType FirstType;
954    if (DeclStmt *DS = dyn_cast<DeclStmt>(First)) {
955      if (!DS->isSingleDecl())
956        return StmtError(Diag((*DS->decl_begin())->getLocation(),
957                         diag::err_toomany_element_decls));
958
959      Decl *D = DS->getSingleDecl();
960      FirstType = cast<ValueDecl>(D)->getType();
961      // C99 6.8.5p3: The declaration part of a 'for' statement shall only
962      // declare identifiers for objects having storage class 'auto' or
963      // 'register'.
964      VarDecl *VD = cast<VarDecl>(D);
965      if (VD->isBlockVarDecl() && !VD->hasLocalStorage())
966        return StmtError(Diag(VD->getLocation(),
967                              diag::err_non_variable_decl_in_for));
968    } else {
969      Expr *FirstE = cast<Expr>(First);
970      if (!FirstE->isTypeDependent() &&
971          FirstE->isLvalue(Context) != Expr::LV_Valid)
972        return StmtError(Diag(First->getLocStart(),
973                   diag::err_selector_element_not_lvalue)
974          << First->getSourceRange());
975
976      FirstType = static_cast<Expr*>(First)->getType();
977    }
978    if (!FirstType->isDependentType() &&
979        !FirstType->isObjCObjectPointerType() &&
980        !FirstType->isBlockPointerType())
981        Diag(ForLoc, diag::err_selector_element_type)
982          << FirstType << First->getSourceRange();
983  }
984  if (Second && !Second->isTypeDependent()) {
985    DefaultFunctionArrayLvalueConversion(Second);
986    QualType SecondType = Second->getType();
987    if (!SecondType->isObjCObjectPointerType())
988      Diag(ForLoc, diag::err_collection_expr_type)
989        << SecondType << Second->getSourceRange();
990    else if (const ObjCObjectPointerType *OPT =
991             SecondType->getAsObjCInterfacePointerType()) {
992      llvm::SmallVector<IdentifierInfo *, 4> KeyIdents;
993      IdentifierInfo* selIdent =
994        &Context.Idents.get("countByEnumeratingWithState");
995      KeyIdents.push_back(selIdent);
996      selIdent = &Context.Idents.get("objects");
997      KeyIdents.push_back(selIdent);
998      selIdent = &Context.Idents.get("count");
999      KeyIdents.push_back(selIdent);
1000      Selector CSelector = Context.Selectors.getSelector(3, &KeyIdents[0]);
1001      if (ObjCInterfaceDecl *IDecl = OPT->getInterfaceDecl()) {
1002        if (!IDecl->isForwardDecl() &&
1003            !IDecl->lookupInstanceMethod(CSelector)) {
1004          // Must further look into private implementation methods.
1005          if (!LookupPrivateInstanceMethod(CSelector, IDecl))
1006            Diag(ForLoc, diag::warn_collection_expr_type)
1007              << SecondType << CSelector << Second->getSourceRange();
1008        }
1009      }
1010    }
1011  }
1012  return Owned(new (Context) ObjCForCollectionStmt(First, Second, Body,
1013                                                   ForLoc, RParenLoc));
1014}
1015
1016StmtResult
1017Sema::ActOnGotoStmt(SourceLocation GotoLoc, SourceLocation LabelLoc,
1018                    IdentifierInfo *LabelII) {
1019  // Look up the record for this label identifier.
1020  LabelStmt *&LabelDecl = getCurFunction()->LabelMap[LabelII];
1021
1022  getCurFunction()->setHasBranchIntoScope();
1023
1024  // If we haven't seen this label yet, create a forward reference.
1025  if (LabelDecl == 0)
1026    LabelDecl = new (Context) LabelStmt(LabelLoc, LabelII, 0);
1027
1028  LabelDecl->setUsed();
1029  return Owned(new (Context) GotoStmt(LabelDecl, GotoLoc, LabelLoc));
1030}
1031
1032StmtResult
1033Sema::ActOnIndirectGotoStmt(SourceLocation GotoLoc, SourceLocation StarLoc,
1034                            Expr *E) {
1035  // Convert operand to void*
1036  if (!E->isTypeDependent()) {
1037    QualType ETy = E->getType();
1038    QualType DestTy = Context.getPointerType(Context.VoidTy.withConst());
1039    AssignConvertType ConvTy =
1040      CheckSingleAssignmentConstraints(DestTy, E);
1041    if (DiagnoseAssignmentResult(ConvTy, StarLoc, DestTy, ETy, E, AA_Passing))
1042      return StmtError();
1043  }
1044
1045  getCurFunction()->setHasIndirectGoto();
1046
1047  return Owned(new (Context) IndirectGotoStmt(GotoLoc, StarLoc, E));
1048}
1049
1050StmtResult
1051Sema::ActOnContinueStmt(SourceLocation ContinueLoc, Scope *CurScope) {
1052  Scope *S = CurScope->getContinueParent();
1053  if (!S) {
1054    // C99 6.8.6.2p1: A break shall appear only in or as a loop body.
1055    return StmtError(Diag(ContinueLoc, diag::err_continue_not_in_loop));
1056  }
1057
1058  return Owned(new (Context) ContinueStmt(ContinueLoc));
1059}
1060
1061StmtResult
1062Sema::ActOnBreakStmt(SourceLocation BreakLoc, Scope *CurScope) {
1063  Scope *S = CurScope->getBreakParent();
1064  if (!S) {
1065    // C99 6.8.6.3p1: A break shall appear only in or as a switch/loop body.
1066    return StmtError(Diag(BreakLoc, diag::err_break_not_in_loop_or_switch));
1067  }
1068
1069  return Owned(new (Context) BreakStmt(BreakLoc));
1070}
1071
1072/// \brief Determine whether a return statement is a candidate for the named
1073/// return value optimization (C++0x 12.8p34, bullet 1).
1074///
1075/// \param Ctx The context in which the return expression and type occur.
1076///
1077/// \param RetType The return type of the function or block.
1078///
1079/// \param RetExpr The expression being returned from the function or block.
1080///
1081/// \returns The NRVO candidate variable, if the return statement may use the
1082/// NRVO, or NULL if there is no such candidate.
1083static const VarDecl *getNRVOCandidate(ASTContext &Ctx, QualType RetType,
1084                                       Expr *RetExpr) {
1085  QualType ExprType = RetExpr->getType();
1086  // - in a return statement in a function with ...
1087  // ... a class return type ...
1088  if (!RetType->isRecordType())
1089    return 0;
1090  // ... the same cv-unqualified type as the function return type ...
1091  if (!Ctx.hasSameUnqualifiedType(RetType, ExprType))
1092    return 0;
1093  // ... the expression is the name of a non-volatile automatic object ...
1094  // We ignore parentheses here.
1095  // FIXME: Is this compliant? (Everyone else does it)
1096  const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(RetExpr->IgnoreParens());
1097  if (!DR)
1098    return 0;
1099  const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl());
1100  if (!VD)
1101    return 0;
1102
1103  if (VD->getKind() == Decl::Var && VD->hasLocalStorage() &&
1104      !VD->getType()->isReferenceType() && !VD->hasAttr<BlocksAttr>() &&
1105      !VD->getType().isVolatileQualified())
1106    return VD;
1107
1108  return 0;
1109}
1110
1111/// ActOnBlockReturnStmt - Utility routine to figure out block's return type.
1112///
1113StmtResult
1114Sema::ActOnBlockReturnStmt(SourceLocation ReturnLoc, Expr *RetValExp) {
1115  // If this is the first return we've seen in the block, infer the type of
1116  // the block from it.
1117  BlockScopeInfo *CurBlock = getCurBlock();
1118  if (CurBlock->ReturnType.isNull()) {
1119    if (RetValExp) {
1120      // Don't call UsualUnaryConversions(), since we don't want to do
1121      // integer promotions here.
1122      DefaultFunctionArrayLvalueConversion(RetValExp);
1123      CurBlock->ReturnType = RetValExp->getType();
1124      if (BlockDeclRefExpr *CDRE = dyn_cast<BlockDeclRefExpr>(RetValExp)) {
1125        // We have to remove a 'const' added to copied-in variable which was
1126        // part of the implementation spec. and not the actual qualifier for
1127        // the variable.
1128        if (CDRE->isConstQualAdded())
1129           CurBlock->ReturnType.removeConst();
1130      }
1131    } else
1132      CurBlock->ReturnType = Context.VoidTy;
1133  }
1134  QualType FnRetType = CurBlock->ReturnType;
1135
1136  if (CurBlock->TheDecl->hasAttr<NoReturnAttr>()) {
1137    Diag(ReturnLoc, diag::err_noreturn_block_has_return_expr)
1138      << getCurFunctionOrMethodDecl()->getDeclName();
1139    return StmtError();
1140  }
1141
1142  // Otherwise, verify that this result type matches the previous one.  We are
1143  // pickier with blocks than for normal functions because we don't have GCC
1144  // compatibility to worry about here.
1145  ReturnStmt *Result = 0;
1146  if (CurBlock->ReturnType->isVoidType()) {
1147    if (RetValExp) {
1148      Diag(ReturnLoc, diag::err_return_block_has_expr);
1149      RetValExp = 0;
1150    }
1151    Result = new (Context) ReturnStmt(ReturnLoc, RetValExp, 0);
1152  } else if (!RetValExp) {
1153    return StmtError(Diag(ReturnLoc, diag::err_block_return_missing_expr));
1154  } else {
1155    const VarDecl *NRVOCandidate = 0;
1156
1157    if (!FnRetType->isDependentType() && !RetValExp->isTypeDependent()) {
1158      // we have a non-void block with an expression, continue checking
1159
1160      // C99 6.8.6.4p3(136): The return statement is not an assignment. The
1161      // overlap restriction of subclause 6.5.16.1 does not apply to the case of
1162      // function return.
1163
1164      // In C++ the return statement is handled via a copy initialization.
1165      // the C version of which boils down to CheckSingleAssignmentConstraints.
1166      NRVOCandidate = getNRVOCandidate(Context, FnRetType, RetValExp);
1167      ExprResult Res = PerformCopyInitialization(
1168                               InitializedEntity::InitializeResult(ReturnLoc,
1169                                                                   FnRetType,
1170                                                            NRVOCandidate != 0),
1171                               SourceLocation(),
1172                               Owned(RetValExp));
1173      if (Res.isInvalid()) {
1174        // FIXME: Cleanup temporaries here, anyway?
1175        return StmtError();
1176      }
1177
1178      if (RetValExp) {
1179        CheckImplicitConversions(RetValExp, ReturnLoc);
1180        RetValExp = MaybeCreateCXXExprWithTemporaries(RetValExp);
1181      }
1182
1183      RetValExp = Res.takeAs<Expr>();
1184      if (RetValExp)
1185        CheckReturnStackAddr(RetValExp, FnRetType, ReturnLoc);
1186    }
1187
1188    Result = new (Context) ReturnStmt(ReturnLoc, RetValExp, NRVOCandidate);
1189  }
1190
1191  // If we need to check for the named return value optimization, save the
1192  // return statement in our scope for later processing.
1193  if (getLangOptions().CPlusPlus && FnRetType->isRecordType() &&
1194      !CurContext->isDependentContext())
1195    FunctionScopes.back()->Returns.push_back(Result);
1196
1197  return Owned(Result);
1198}
1199
1200StmtResult
1201Sema::ActOnReturnStmt(SourceLocation ReturnLoc, Expr *RetValExp) {
1202  if (getCurBlock())
1203    return ActOnBlockReturnStmt(ReturnLoc, RetValExp);
1204
1205  QualType FnRetType;
1206  if (const FunctionDecl *FD = getCurFunctionDecl()) {
1207    FnRetType = FD->getResultType();
1208    if (FD->hasAttr<NoReturnAttr>() ||
1209        FD->getType()->getAs<FunctionType>()->getNoReturnAttr())
1210      Diag(ReturnLoc, diag::warn_noreturn_function_has_return_expr)
1211        << getCurFunctionOrMethodDecl()->getDeclName();
1212  } else if (ObjCMethodDecl *MD = getCurMethodDecl())
1213    FnRetType = MD->getResultType();
1214  else // If we don't have a function/method context, bail.
1215    return StmtError();
1216
1217  ReturnStmt *Result = 0;
1218  if (FnRetType->isVoidType()) {
1219    if (RetValExp && !RetValExp->isTypeDependent()) {
1220      // C99 6.8.6.4p1 (ext_ since GCC warns)
1221      unsigned D = diag::ext_return_has_expr;
1222      if (RetValExp->getType()->isVoidType())
1223        D = diag::ext_return_has_void_expr;
1224
1225      // return (some void expression); is legal in C++.
1226      if (D != diag::ext_return_has_void_expr ||
1227          !getLangOptions().CPlusPlus) {
1228        NamedDecl *CurDecl = getCurFunctionOrMethodDecl();
1229        Diag(ReturnLoc, D)
1230          << CurDecl->getDeclName() << isa<ObjCMethodDecl>(CurDecl)
1231          << RetValExp->getSourceRange();
1232      }
1233
1234      CheckImplicitConversions(RetValExp, ReturnLoc);
1235      RetValExp = MaybeCreateCXXExprWithTemporaries(RetValExp);
1236    }
1237
1238    Result = new (Context) ReturnStmt(ReturnLoc, RetValExp, 0);
1239  } else if (!RetValExp && !FnRetType->isDependentType()) {
1240    unsigned DiagID = diag::warn_return_missing_expr;  // C90 6.6.6.4p4
1241    // C99 6.8.6.4p1 (ext_ since GCC warns)
1242    if (getLangOptions().C99) DiagID = diag::ext_return_missing_expr;
1243
1244    if (FunctionDecl *FD = getCurFunctionDecl())
1245      Diag(ReturnLoc, DiagID) << FD->getIdentifier() << 0/*fn*/;
1246    else
1247      Diag(ReturnLoc, DiagID) << getCurMethodDecl()->getDeclName() << 1/*meth*/;
1248    Result = new (Context) ReturnStmt(ReturnLoc);
1249  } else {
1250    const VarDecl *NRVOCandidate = 0;
1251    if (!FnRetType->isDependentType() && !RetValExp->isTypeDependent()) {
1252      // we have a non-void function with an expression, continue checking
1253
1254      // C99 6.8.6.4p3(136): The return statement is not an assignment. The
1255      // overlap restriction of subclause 6.5.16.1 does not apply to the case of
1256      // function return.
1257
1258      // In C++ the return statement is handled via a copy initialization.
1259      // the C version of which boils down to CheckSingleAssignmentConstraints.
1260      NRVOCandidate = getNRVOCandidate(Context, FnRetType, RetValExp);
1261      ExprResult Res = PerformCopyInitialization(
1262                               InitializedEntity::InitializeResult(ReturnLoc,
1263                                                                   FnRetType,
1264                                                            NRVOCandidate != 0),
1265                               SourceLocation(),
1266                               Owned(RetValExp));
1267      if (Res.isInvalid()) {
1268        // FIXME: Cleanup temporaries here, anyway?
1269        return StmtError();
1270      }
1271
1272      RetValExp = Res.takeAs<Expr>();
1273      if (RetValExp)
1274        CheckReturnStackAddr(RetValExp, FnRetType, ReturnLoc);
1275    }
1276
1277    if (RetValExp) {
1278      CheckImplicitConversions(RetValExp, ReturnLoc);
1279      RetValExp = MaybeCreateCXXExprWithTemporaries(RetValExp);
1280    }
1281    Result = new (Context) ReturnStmt(ReturnLoc, RetValExp, NRVOCandidate);
1282  }
1283
1284  // If we need to check for the named return value optimization, save the
1285  // return statement in our scope for later processing.
1286  if (getLangOptions().CPlusPlus && FnRetType->isRecordType() &&
1287      !CurContext->isDependentContext())
1288    FunctionScopes.back()->Returns.push_back(Result);
1289
1290  return Owned(Result);
1291}
1292
1293/// CheckAsmLValue - GNU C has an extremely ugly extension whereby they silently
1294/// ignore "noop" casts in places where an lvalue is required by an inline asm.
1295/// We emulate this behavior when -fheinous-gnu-extensions is specified, but
1296/// provide a strong guidance to not use it.
1297///
1298/// This method checks to see if the argument is an acceptable l-value and
1299/// returns false if it is a case we can handle.
1300static bool CheckAsmLValue(const Expr *E, Sema &S) {
1301  // Type dependent expressions will be checked during instantiation.
1302  if (E->isTypeDependent())
1303    return false;
1304
1305  if (E->isLvalue(S.Context) == Expr::LV_Valid)
1306    return false;  // Cool, this is an lvalue.
1307
1308  // Okay, this is not an lvalue, but perhaps it is the result of a cast that we
1309  // are supposed to allow.
1310  const Expr *E2 = E->IgnoreParenNoopCasts(S.Context);
1311  if (E != E2 && E2->isLvalue(S.Context) == Expr::LV_Valid) {
1312    if (!S.getLangOptions().HeinousExtensions)
1313      S.Diag(E2->getLocStart(), diag::err_invalid_asm_cast_lvalue)
1314        << E->getSourceRange();
1315    else
1316      S.Diag(E2->getLocStart(), diag::warn_invalid_asm_cast_lvalue)
1317        << E->getSourceRange();
1318    // Accept, even if we emitted an error diagnostic.
1319    return false;
1320  }
1321
1322  // None of the above, just randomly invalid non-lvalue.
1323  return true;
1324}
1325
1326
1327StmtResult Sema::ActOnAsmStmt(SourceLocation AsmLoc,
1328                                          bool IsSimple,
1329                                          bool IsVolatile,
1330                                          unsigned NumOutputs,
1331                                          unsigned NumInputs,
1332                                          IdentifierInfo **Names,
1333                                          MultiExprArg constraints,
1334                                          MultiExprArg exprs,
1335                                          Expr *asmString,
1336                                          MultiExprArg clobbers,
1337                                          SourceLocation RParenLoc,
1338                                          bool MSAsm) {
1339  unsigned NumClobbers = clobbers.size();
1340  StringLiteral **Constraints =
1341    reinterpret_cast<StringLiteral**>(constraints.get());
1342  Expr **Exprs = exprs.get();
1343  StringLiteral *AsmString = cast<StringLiteral>(asmString);
1344  StringLiteral **Clobbers = reinterpret_cast<StringLiteral**>(clobbers.get());
1345
1346  llvm::SmallVector<TargetInfo::ConstraintInfo, 4> OutputConstraintInfos;
1347
1348  // The parser verifies that there is a string literal here.
1349  if (AsmString->isWide())
1350    return StmtError(Diag(AsmString->getLocStart(),diag::err_asm_wide_character)
1351      << AsmString->getSourceRange());
1352
1353  for (unsigned i = 0; i != NumOutputs; i++) {
1354    StringLiteral *Literal = Constraints[i];
1355    if (Literal->isWide())
1356      return StmtError(Diag(Literal->getLocStart(),diag::err_asm_wide_character)
1357        << Literal->getSourceRange());
1358
1359    llvm::StringRef OutputName;
1360    if (Names[i])
1361      OutputName = Names[i]->getName();
1362
1363    TargetInfo::ConstraintInfo Info(Literal->getString(), OutputName);
1364    if (!Context.Target.validateOutputConstraint(Info))
1365      return StmtError(Diag(Literal->getLocStart(),
1366                            diag::err_asm_invalid_output_constraint)
1367                       << Info.getConstraintStr());
1368
1369    // Check that the output exprs are valid lvalues.
1370    Expr *OutputExpr = Exprs[i];
1371    if (CheckAsmLValue(OutputExpr, *this)) {
1372      return StmtError(Diag(OutputExpr->getLocStart(),
1373                  diag::err_asm_invalid_lvalue_in_output)
1374        << OutputExpr->getSourceRange());
1375    }
1376
1377    OutputConstraintInfos.push_back(Info);
1378  }
1379
1380  llvm::SmallVector<TargetInfo::ConstraintInfo, 4> InputConstraintInfos;
1381
1382  for (unsigned i = NumOutputs, e = NumOutputs + NumInputs; i != e; i++) {
1383    StringLiteral *Literal = Constraints[i];
1384    if (Literal->isWide())
1385      return StmtError(Diag(Literal->getLocStart(),diag::err_asm_wide_character)
1386        << Literal->getSourceRange());
1387
1388    llvm::StringRef InputName;
1389    if (Names[i])
1390      InputName = Names[i]->getName();
1391
1392    TargetInfo::ConstraintInfo Info(Literal->getString(), InputName);
1393    if (!Context.Target.validateInputConstraint(OutputConstraintInfos.data(),
1394                                                NumOutputs, Info)) {
1395      return StmtError(Diag(Literal->getLocStart(),
1396                            diag::err_asm_invalid_input_constraint)
1397                       << Info.getConstraintStr());
1398    }
1399
1400    Expr *InputExpr = Exprs[i];
1401
1402    // Only allow void types for memory constraints.
1403    if (Info.allowsMemory() && !Info.allowsRegister()) {
1404      if (CheckAsmLValue(InputExpr, *this))
1405        return StmtError(Diag(InputExpr->getLocStart(),
1406                              diag::err_asm_invalid_lvalue_in_input)
1407                         << Info.getConstraintStr()
1408                         << InputExpr->getSourceRange());
1409    }
1410
1411    if (Info.allowsRegister()) {
1412      if (InputExpr->getType()->isVoidType()) {
1413        return StmtError(Diag(InputExpr->getLocStart(),
1414                              diag::err_asm_invalid_type_in_input)
1415          << InputExpr->getType() << Info.getConstraintStr()
1416          << InputExpr->getSourceRange());
1417      }
1418    }
1419
1420    DefaultFunctionArrayLvalueConversion(Exprs[i]);
1421
1422    InputConstraintInfos.push_back(Info);
1423  }
1424
1425  // Check that the clobbers are valid.
1426  for (unsigned i = 0; i != NumClobbers; i++) {
1427    StringLiteral *Literal = Clobbers[i];
1428    if (Literal->isWide())
1429      return StmtError(Diag(Literal->getLocStart(),diag::err_asm_wide_character)
1430        << Literal->getSourceRange());
1431
1432    llvm::StringRef Clobber = Literal->getString();
1433
1434    if (!Context.Target.isValidGCCRegisterName(Clobber))
1435      return StmtError(Diag(Literal->getLocStart(),
1436                  diag::err_asm_unknown_register_name) << Clobber);
1437  }
1438
1439  AsmStmt *NS =
1440    new (Context) AsmStmt(Context, AsmLoc, IsSimple, IsVolatile, MSAsm,
1441                          NumOutputs, NumInputs, Names, Constraints, Exprs,
1442                          AsmString, NumClobbers, Clobbers, RParenLoc);
1443  // Validate the asm string, ensuring it makes sense given the operands we
1444  // have.
1445  llvm::SmallVector<AsmStmt::AsmStringPiece, 8> Pieces;
1446  unsigned DiagOffs;
1447  if (unsigned DiagID = NS->AnalyzeAsmString(Pieces, Context, DiagOffs)) {
1448    Diag(getLocationOfStringLiteralByte(AsmString, DiagOffs), DiagID)
1449           << AsmString->getSourceRange();
1450    return StmtError();
1451  }
1452
1453  // Validate tied input operands for type mismatches.
1454  for (unsigned i = 0, e = InputConstraintInfos.size(); i != e; ++i) {
1455    TargetInfo::ConstraintInfo &Info = InputConstraintInfos[i];
1456
1457    // If this is a tied constraint, verify that the output and input have
1458    // either exactly the same type, or that they are int/ptr operands with the
1459    // same size (int/long, int*/long, are ok etc).
1460    if (!Info.hasTiedOperand()) continue;
1461
1462    unsigned TiedTo = Info.getTiedOperand();
1463    Expr *OutputExpr = Exprs[TiedTo];
1464    Expr *InputExpr = Exprs[i+NumOutputs];
1465    QualType InTy = InputExpr->getType();
1466    QualType OutTy = OutputExpr->getType();
1467    if (Context.hasSameType(InTy, OutTy))
1468      continue;  // All types can be tied to themselves.
1469
1470    // Decide if the input and output are in the same domain (integer/ptr or
1471    // floating point.
1472    enum AsmDomain {
1473      AD_Int, AD_FP, AD_Other
1474    } InputDomain, OutputDomain;
1475
1476    if (InTy->isIntegerType() || InTy->isPointerType())
1477      InputDomain = AD_Int;
1478    else if (InTy->isRealFloatingType())
1479      InputDomain = AD_FP;
1480    else
1481      InputDomain = AD_Other;
1482
1483    if (OutTy->isIntegerType() || OutTy->isPointerType())
1484      OutputDomain = AD_Int;
1485    else if (OutTy->isRealFloatingType())
1486      OutputDomain = AD_FP;
1487    else
1488      OutputDomain = AD_Other;
1489
1490    // They are ok if they are the same size and in the same domain.  This
1491    // allows tying things like:
1492    //   void* to int*
1493    //   void* to int            if they are the same size.
1494    //   double to long double   if they are the same size.
1495    //
1496    uint64_t OutSize = Context.getTypeSize(OutTy);
1497    uint64_t InSize = Context.getTypeSize(InTy);
1498    if (OutSize == InSize && InputDomain == OutputDomain &&
1499        InputDomain != AD_Other)
1500      continue;
1501
1502    // If the smaller input/output operand is not mentioned in the asm string,
1503    // then we can promote it and the asm string won't notice.  Check this
1504    // case now.
1505    bool SmallerValueMentioned = false;
1506    for (unsigned p = 0, e = Pieces.size(); p != e; ++p) {
1507      AsmStmt::AsmStringPiece &Piece = Pieces[p];
1508      if (!Piece.isOperand()) continue;
1509
1510      // If this is a reference to the input and if the input was the smaller
1511      // one, then we have to reject this asm.
1512      if (Piece.getOperandNo() == i+NumOutputs) {
1513        if (InSize < OutSize) {
1514          SmallerValueMentioned = true;
1515          break;
1516        }
1517      }
1518
1519      // If this is a reference to the input and if the input was the smaller
1520      // one, then we have to reject this asm.
1521      if (Piece.getOperandNo() == TiedTo) {
1522        if (InSize > OutSize) {
1523          SmallerValueMentioned = true;
1524          break;
1525        }
1526      }
1527    }
1528
1529    // If the smaller value wasn't mentioned in the asm string, and if the
1530    // output was a register, just extend the shorter one to the size of the
1531    // larger one.
1532    if (!SmallerValueMentioned && InputDomain != AD_Other &&
1533        OutputConstraintInfos[TiedTo].allowsRegister())
1534      continue;
1535
1536    Diag(InputExpr->getLocStart(),
1537         diag::err_asm_tying_incompatible_types)
1538      << InTy << OutTy << OutputExpr->getSourceRange()
1539      << InputExpr->getSourceRange();
1540    return StmtError();
1541  }
1542
1543  return Owned(NS);
1544}
1545
1546StmtResult
1547Sema::ActOnObjCAtCatchStmt(SourceLocation AtLoc,
1548                           SourceLocation RParen, Decl *Parm,
1549                           Stmt *Body) {
1550  VarDecl *Var = cast_or_null<VarDecl>(Parm);
1551  if (Var && Var->isInvalidDecl())
1552    return StmtError();
1553
1554  return Owned(new (Context) ObjCAtCatchStmt(AtLoc, RParen, Var, Body));
1555}
1556
1557StmtResult
1558Sema::ActOnObjCAtFinallyStmt(SourceLocation AtLoc, Stmt *Body) {
1559  return Owned(new (Context) ObjCAtFinallyStmt(AtLoc, Body));
1560}
1561
1562StmtResult
1563Sema::ActOnObjCAtTryStmt(SourceLocation AtLoc, Stmt *Try,
1564                         MultiStmtArg CatchStmts, Stmt *Finally) {
1565  getCurFunction()->setHasBranchProtectedScope();
1566  unsigned NumCatchStmts = CatchStmts.size();
1567  return Owned(ObjCAtTryStmt::Create(Context, AtLoc, Try,
1568                                     CatchStmts.release(),
1569                                     NumCatchStmts,
1570                                     Finally));
1571}
1572
1573StmtResult Sema::BuildObjCAtThrowStmt(SourceLocation AtLoc,
1574                                                  Expr *Throw) {
1575  if (Throw) {
1576    QualType ThrowType = Throw->getType();
1577    // Make sure the expression type is an ObjC pointer or "void *".
1578    if (!ThrowType->isDependentType() &&
1579        !ThrowType->isObjCObjectPointerType()) {
1580      const PointerType *PT = ThrowType->getAs<PointerType>();
1581      if (!PT || !PT->getPointeeType()->isVoidType())
1582        return StmtError(Diag(AtLoc, diag::error_objc_throw_expects_object)
1583                         << Throw->getType() << Throw->getSourceRange());
1584    }
1585  }
1586
1587  return Owned(new (Context) ObjCAtThrowStmt(AtLoc, Throw));
1588}
1589
1590StmtResult
1591Sema::ActOnObjCAtThrowStmt(SourceLocation AtLoc, Expr *Throw,
1592                           Scope *CurScope) {
1593  if (!Throw) {
1594    // @throw without an expression designates a rethrow (which much occur
1595    // in the context of an @catch clause).
1596    Scope *AtCatchParent = CurScope;
1597    while (AtCatchParent && !AtCatchParent->isAtCatchScope())
1598      AtCatchParent = AtCatchParent->getParent();
1599    if (!AtCatchParent)
1600      return StmtError(Diag(AtLoc, diag::error_rethrow_used_outside_catch));
1601  }
1602
1603  return BuildObjCAtThrowStmt(AtLoc, Throw);
1604}
1605
1606StmtResult
1607Sema::ActOnObjCAtSynchronizedStmt(SourceLocation AtLoc, Expr *SyncExpr,
1608                                  Stmt *SyncBody) {
1609  getCurFunction()->setHasBranchProtectedScope();
1610
1611  // Make sure the expression type is an ObjC pointer or "void *".
1612  if (!SyncExpr->getType()->isDependentType() &&
1613      !SyncExpr->getType()->isObjCObjectPointerType()) {
1614    const PointerType *PT = SyncExpr->getType()->getAs<PointerType>();
1615    if (!PT || !PT->getPointeeType()->isVoidType())
1616      return StmtError(Diag(AtLoc, diag::error_objc_synchronized_expects_object)
1617                       << SyncExpr->getType() << SyncExpr->getSourceRange());
1618  }
1619
1620  return Owned(new (Context) ObjCAtSynchronizedStmt(AtLoc, SyncExpr, SyncBody));
1621}
1622
1623/// ActOnCXXCatchBlock - Takes an exception declaration and a handler block
1624/// and creates a proper catch handler from them.
1625StmtResult
1626Sema::ActOnCXXCatchBlock(SourceLocation CatchLoc, Decl *ExDecl,
1627                         Stmt *HandlerBlock) {
1628  // There's nothing to test that ActOnExceptionDecl didn't already test.
1629  return Owned(new (Context) CXXCatchStmt(CatchLoc,
1630                                          cast_or_null<VarDecl>(ExDecl),
1631                                          HandlerBlock));
1632}
1633
1634namespace {
1635
1636class TypeWithHandler {
1637  QualType t;
1638  CXXCatchStmt *stmt;
1639public:
1640  TypeWithHandler(const QualType &type, CXXCatchStmt *statement)
1641  : t(type), stmt(statement) {}
1642
1643  // An arbitrary order is fine as long as it places identical
1644  // types next to each other.
1645  bool operator<(const TypeWithHandler &y) const {
1646    if (t.getAsOpaquePtr() < y.t.getAsOpaquePtr())
1647      return true;
1648    if (t.getAsOpaquePtr() > y.t.getAsOpaquePtr())
1649      return false;
1650    else
1651      return getTypeSpecStartLoc() < y.getTypeSpecStartLoc();
1652  }
1653
1654  bool operator==(const TypeWithHandler& other) const {
1655    return t == other.t;
1656  }
1657
1658  CXXCatchStmt *getCatchStmt() const { return stmt; }
1659  SourceLocation getTypeSpecStartLoc() const {
1660    return stmt->getExceptionDecl()->getTypeSpecStartLoc();
1661  }
1662};
1663
1664}
1665
1666/// ActOnCXXTryBlock - Takes a try compound-statement and a number of
1667/// handlers and creates a try statement from them.
1668StmtResult
1669Sema::ActOnCXXTryBlock(SourceLocation TryLoc, Stmt *TryBlock,
1670                       MultiStmtArg RawHandlers) {
1671  unsigned NumHandlers = RawHandlers.size();
1672  assert(NumHandlers > 0 &&
1673         "The parser shouldn't call this if there are no handlers.");
1674  Stmt **Handlers = RawHandlers.get();
1675
1676  llvm::SmallVector<TypeWithHandler, 8> TypesWithHandlers;
1677
1678  for (unsigned i = 0; i < NumHandlers; ++i) {
1679    CXXCatchStmt *Handler = llvm::cast<CXXCatchStmt>(Handlers[i]);
1680    if (!Handler->getExceptionDecl()) {
1681      if (i < NumHandlers - 1)
1682        return StmtError(Diag(Handler->getLocStart(),
1683                              diag::err_early_catch_all));
1684
1685      continue;
1686    }
1687
1688    const QualType CaughtType = Handler->getCaughtType();
1689    const QualType CanonicalCaughtType = Context.getCanonicalType(CaughtType);
1690    TypesWithHandlers.push_back(TypeWithHandler(CanonicalCaughtType, Handler));
1691  }
1692
1693  // Detect handlers for the same type as an earlier one.
1694  if (NumHandlers > 1) {
1695    llvm::array_pod_sort(TypesWithHandlers.begin(), TypesWithHandlers.end());
1696
1697    TypeWithHandler prev = TypesWithHandlers[0];
1698    for (unsigned i = 1; i < TypesWithHandlers.size(); ++i) {
1699      TypeWithHandler curr = TypesWithHandlers[i];
1700
1701      if (curr == prev) {
1702        Diag(curr.getTypeSpecStartLoc(),
1703             diag::warn_exception_caught_by_earlier_handler)
1704          << curr.getCatchStmt()->getCaughtType().getAsString();
1705        Diag(prev.getTypeSpecStartLoc(),
1706             diag::note_previous_exception_handler)
1707          << prev.getCatchStmt()->getCaughtType().getAsString();
1708      }
1709
1710      prev = curr;
1711    }
1712  }
1713
1714  getCurFunction()->setHasBranchProtectedScope();
1715
1716  // FIXME: We should detect handlers that cannot catch anything because an
1717  // earlier handler catches a superclass. Need to find a method that is not
1718  // quadratic for this.
1719  // Neither of these are explicitly forbidden, but every compiler detects them
1720  // and warns.
1721
1722  return Owned(CXXTryStmt::Create(Context, TryLoc, TryBlock,
1723                                  Handlers, NumHandlers));
1724}
1725