SemaStmt.cpp revision 8113ecfa4e41e2c888b1794389dfe3bce6386493 
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  if (E->isBoundMemberFunction(Context)) {
78    Diag(E->getLocStart(), diag::err_invalid_use_of_bound_member_func)
79      << E->getSourceRange();
80    return;
81  }
82
83  SourceLocation Loc;
84  SourceRange R1, R2;
85  if (!E->isUnusedResultAWarning(Loc, R1, R2, Context))
86    return;
87
88  // Okay, we have an unused result.  Depending on what the base expression is,
89  // we might want to make a more specific diagnostic.  Check for one of these
90  // cases now.
91  unsigned DiagID = diag::warn_unused_expr;
92  E = E->IgnoreParens();
93  if (isa<ObjCImplicitSetterGetterRefExpr>(E))
94    DiagID = diag::warn_unused_property_expr;
95
96  if (const CXXExprWithTemporaries *Temps = dyn_cast<CXXExprWithTemporaries>(E))
97    E = Temps->getSubExpr();
98
99  if (const CallExpr *CE = dyn_cast<CallExpr>(E)) {
100    if (E->getType()->isVoidType())
101      return;
102
103    // If the callee has attribute pure, const, or warn_unused_result, warn with
104    // a more specific message to make it clear what is happening.
105    if (const Decl *FD = CE->getCalleeDecl()) {
106      if (FD->getAttr<WarnUnusedResultAttr>()) {
107        Diag(Loc, diag::warn_unused_call) << R1 << R2 << "warn_unused_result";
108        return;
109      }
110      if (FD->getAttr<PureAttr>()) {
111        Diag(Loc, diag::warn_unused_call) << R1 << R2 << "pure";
112        return;
113      }
114      if (FD->getAttr<ConstAttr>()) {
115        Diag(Loc, diag::warn_unused_call) << R1 << R2 << "const";
116        return;
117      }
118    }
119  }
120  else if (const ObjCMessageExpr *ME = dyn_cast<ObjCMessageExpr>(E)) {
121    const ObjCMethodDecl *MD = ME->getMethodDecl();
122    if (MD && MD->getAttr<WarnUnusedResultAttr>()) {
123      Diag(Loc, diag::warn_unused_call) << R1 << R2 << "warn_unused_result";
124      return;
125    }
126  } else if (const CXXFunctionalCastExpr *FC
127                                       = dyn_cast<CXXFunctionalCastExpr>(E)) {
128    if (isa<CXXConstructExpr>(FC->getSubExpr()) ||
129        isa<CXXTemporaryObjectExpr>(FC->getSubExpr()))
130      return;
131  }
132  // Diagnose "(void*) blah" as a typo for "(void) blah".
133  else if (const CStyleCastExpr *CE = dyn_cast<CStyleCastExpr>(E)) {
134    TypeSourceInfo *TI = CE->getTypeInfoAsWritten();
135    QualType T = TI->getType();
136
137    // We really do want to use the non-canonical type here.
138    if (T == Context.VoidPtrTy) {
139      PointerTypeLoc TL = cast<PointerTypeLoc>(TI->getTypeLoc());
140
141      Diag(Loc, diag::warn_unused_voidptr)
142        << FixItHint::CreateRemoval(TL.getStarLoc());
143      return;
144    }
145  }
146
147  DiagRuntimeBehavior(Loc, PDiag(DiagID) << R1 << R2);
148}
149
150StmtResult
151Sema::ActOnCompoundStmt(SourceLocation L, SourceLocation R,
152                        MultiStmtArg elts, bool isStmtExpr) {
153  unsigned NumElts = elts.size();
154  Stmt **Elts = reinterpret_cast<Stmt**>(elts.release());
155  // If we're in C89 mode, check that we don't have any decls after stmts.  If
156  // so, emit an extension diagnostic.
157  if (!getLangOptions().C99 && !getLangOptions().CPlusPlus) {
158    // Note that __extension__ can be around a decl.
159    unsigned i = 0;
160    // Skip over all declarations.
161    for (; i != NumElts && isa<DeclStmt>(Elts[i]); ++i)
162      /*empty*/;
163
164    // We found the end of the list or a statement.  Scan for another declstmt.
165    for (; i != NumElts && !isa<DeclStmt>(Elts[i]); ++i)
166      /*empty*/;
167
168    if (i != NumElts) {
169      Decl *D = *cast<DeclStmt>(Elts[i])->decl_begin();
170      Diag(D->getLocation(), diag::ext_mixed_decls_code);
171    }
172  }
173  // Warn about unused expressions in statements.
174  for (unsigned i = 0; i != NumElts; ++i) {
175    // Ignore statements that are last in a statement expression.
176    if (isStmtExpr && i == NumElts - 1)
177      continue;
178
179    DiagnoseUnusedExprResult(Elts[i]);
180  }
181
182  return Owned(new (Context) CompoundStmt(Context, Elts, NumElts, L, R));
183}
184
185StmtResult
186Sema::ActOnCaseStmt(SourceLocation CaseLoc, Expr *LHSVal,
187                    SourceLocation DotDotDotLoc, Expr *RHSVal,
188                    SourceLocation ColonLoc) {
189  assert((LHSVal != 0) && "missing expression in case statement");
190
191  // C99 6.8.4.2p3: The expression shall be an integer constant.
192  // However, GCC allows any evaluatable integer expression.
193  if (!LHSVal->isTypeDependent() && !LHSVal->isValueDependent() &&
194      VerifyIntegerConstantExpression(LHSVal))
195    return StmtError();
196
197  // GCC extension: The expression shall be an integer constant.
198
199  if (RHSVal && !RHSVal->isTypeDependent() && !RHSVal->isValueDependent() &&
200      VerifyIntegerConstantExpression(RHSVal)) {
201    RHSVal = 0;  // Recover by just forgetting about it.
202  }
203
204  if (getCurFunction()->SwitchStack.empty()) {
205    Diag(CaseLoc, diag::err_case_not_in_switch);
206    return StmtError();
207  }
208
209  CaseStmt *CS = new (Context) CaseStmt(LHSVal, RHSVal, CaseLoc, DotDotDotLoc,
210                                        ColonLoc);
211  getCurFunction()->SwitchStack.back()->addSwitchCase(CS);
212  return Owned(CS);
213}
214
215/// ActOnCaseStmtBody - This installs a statement as the body of a case.
216void Sema::ActOnCaseStmtBody(Stmt *caseStmt, Stmt *SubStmt) {
217  CaseStmt *CS = static_cast<CaseStmt*>(caseStmt);
218  CS->setSubStmt(SubStmt);
219}
220
221StmtResult
222Sema::ActOnDefaultStmt(SourceLocation DefaultLoc, SourceLocation ColonLoc,
223                       Stmt *SubStmt, Scope *CurScope) {
224  if (getCurFunction()->SwitchStack.empty()) {
225    Diag(DefaultLoc, diag::err_default_not_in_switch);
226    return Owned(SubStmt);
227  }
228
229  DefaultStmt *DS = new (Context) DefaultStmt(DefaultLoc, ColonLoc, SubStmt);
230  getCurFunction()->SwitchStack.back()->addSwitchCase(DS);
231  return Owned(DS);
232}
233
234StmtResult
235Sema::ActOnLabelStmt(SourceLocation IdentLoc, IdentifierInfo *II,
236                     SourceLocation ColonLoc, Stmt *SubStmt,
237                     const AttributeList *Attr) {
238  // According to GCC docs, "the only attribute that makes sense after a label
239  // is 'unused'".
240  bool HasUnusedAttr = false;
241  for ( ; Attr; Attr = Attr->getNext()) {
242    if (Attr->getKind() == AttributeList::AT_unused) {
243      HasUnusedAttr = true;
244    } else {
245      Diag(Attr->getLoc(), diag::warn_label_attribute_not_unused);
246      Attr->setInvalid(true);
247    }
248  }
249
250  return ActOnLabelStmt(IdentLoc, II, ColonLoc, SubStmt, HasUnusedAttr);
251}
252
253StmtResult
254Sema::ActOnLabelStmt(SourceLocation IdentLoc, IdentifierInfo *II,
255                     SourceLocation ColonLoc, Stmt *SubStmt,
256                     bool HasUnusedAttr) {
257  // Look up the record for this label identifier.
258  LabelStmt *&LabelDecl = getCurFunction()->LabelMap[II];
259
260  // If not forward referenced or defined already, just create a new LabelStmt.
261  if (LabelDecl == 0)
262    return Owned(LabelDecl = new (Context) LabelStmt(IdentLoc, II, SubStmt,
263                                                     HasUnusedAttr));
264
265  assert(LabelDecl->getID() == II && "Label mismatch!");
266
267  // Otherwise, this label was either forward reference or multiply defined.  If
268  // multiply defined, reject it now.
269  if (LabelDecl->getSubStmt()) {
270    Diag(IdentLoc, diag::err_redefinition_of_label) << LabelDecl->getID();
271    Diag(LabelDecl->getIdentLoc(), diag::note_previous_definition);
272    return Owned(SubStmt);
273  }
274
275  // Otherwise, this label was forward declared, and we just found its real
276  // definition.  Fill in the forward definition and return it.
277  LabelDecl->setIdentLoc(IdentLoc);
278  LabelDecl->setSubStmt(SubStmt);
279  LabelDecl->setUnusedAttribute(HasUnusedAttr);
280  return Owned(LabelDecl);
281}
282
283StmtResult
284Sema::ActOnIfStmt(SourceLocation IfLoc, FullExprArg CondVal, Decl *CondVar,
285                  Stmt *thenStmt, SourceLocation ElseLoc,
286                  Stmt *elseStmt) {
287  ExprResult CondResult(CondVal.release());
288
289  VarDecl *ConditionVar = 0;
290  if (CondVar) {
291    ConditionVar = cast<VarDecl>(CondVar);
292    CondResult = CheckConditionVariable(ConditionVar, IfLoc, true);
293    if (CondResult.isInvalid())
294      return StmtError();
295  }
296  Expr *ConditionExpr = CondResult.takeAs<Expr>();
297  if (!ConditionExpr)
298    return StmtError();
299
300  DiagnoseUnusedExprResult(thenStmt);
301
302  // Warn if the if block has a null body without an else value.
303  // this helps prevent bugs due to typos, such as
304  // if (condition);
305  //   do_stuff();
306  //
307  // NOTE: Do not emit this warning if the body is expanded from a macro.
308  if (!elseStmt) {
309    if (NullStmt* stmt = dyn_cast<NullStmt>(thenStmt))
310      if (!stmt->getLocStart().isMacroID())
311        Diag(stmt->getSemiLoc(), diag::warn_empty_if_body);
312  }
313
314  DiagnoseUnusedExprResult(elseStmt);
315
316  return Owned(new (Context) IfStmt(Context, IfLoc, ConditionVar, ConditionExpr,
317                                    thenStmt, ElseLoc, elseStmt));
318}
319
320/// ConvertIntegerToTypeWarnOnOverflow - Convert the specified APInt to have
321/// the specified width and sign.  If an overflow occurs, detect it and emit
322/// the specified diagnostic.
323void Sema::ConvertIntegerToTypeWarnOnOverflow(llvm::APSInt &Val,
324                                              unsigned NewWidth, bool NewSign,
325                                              SourceLocation Loc,
326                                              unsigned DiagID) {
327  // Perform a conversion to the promoted condition type if needed.
328  if (NewWidth > Val.getBitWidth()) {
329    // If this is an extension, just do it.
330    Val.extend(NewWidth);
331    Val.setIsSigned(NewSign);
332
333    // If the input was signed and negative and the output is
334    // unsigned, don't bother to warn: this is implementation-defined
335    // behavior.
336    // FIXME: Introduce a second, default-ignored warning for this case?
337  } else if (NewWidth < Val.getBitWidth()) {
338    // If this is a truncation, check for overflow.
339    llvm::APSInt ConvVal(Val);
340    ConvVal.trunc(NewWidth);
341    ConvVal.setIsSigned(NewSign);
342    ConvVal.extend(Val.getBitWidth());
343    ConvVal.setIsSigned(Val.isSigned());
344    if (ConvVal != Val)
345      Diag(Loc, DiagID) << Val.toString(10) << ConvVal.toString(10);
346
347    // Regardless of whether a diagnostic was emitted, really do the
348    // truncation.
349    Val.trunc(NewWidth);
350    Val.setIsSigned(NewSign);
351  } else if (NewSign != Val.isSigned()) {
352    // Convert the sign to match the sign of the condition.  This can cause
353    // overflow as well: unsigned(INTMIN)
354    // We don't diagnose this overflow, because it is implementation-defined
355    // behavior.
356    // FIXME: Introduce a second, default-ignored warning for this case?
357    llvm::APSInt OldVal(Val);
358    Val.setIsSigned(NewSign);
359  }
360}
361
362namespace {
363  struct CaseCompareFunctor {
364    bool operator()(const std::pair<llvm::APSInt, CaseStmt*> &LHS,
365                    const llvm::APSInt &RHS) {
366      return LHS.first < RHS;
367    }
368    bool operator()(const std::pair<llvm::APSInt, CaseStmt*> &LHS,
369                    const std::pair<llvm::APSInt, CaseStmt*> &RHS) {
370      return LHS.first < RHS.first;
371    }
372    bool operator()(const llvm::APSInt &LHS,
373                    const std::pair<llvm::APSInt, CaseStmt*> &RHS) {
374      return LHS < RHS.first;
375    }
376  };
377}
378
379/// CmpCaseVals - Comparison predicate for sorting case values.
380///
381static bool CmpCaseVals(const std::pair<llvm::APSInt, CaseStmt*>& lhs,
382                        const std::pair<llvm::APSInt, CaseStmt*>& rhs) {
383  if (lhs.first < rhs.first)
384    return true;
385
386  if (lhs.first == rhs.first &&
387      lhs.second->getCaseLoc().getRawEncoding()
388       < rhs.second->getCaseLoc().getRawEncoding())
389    return true;
390  return false;
391}
392
393/// CmpEnumVals - Comparison predicate for sorting enumeration values.
394///
395static bool CmpEnumVals(const std::pair<llvm::APSInt, EnumConstantDecl*>& lhs,
396                        const std::pair<llvm::APSInt, EnumConstantDecl*>& rhs)
397{
398  return lhs.first < rhs.first;
399}
400
401/// EqEnumVals - Comparison preficate for uniqing enumeration values.
402///
403static bool EqEnumVals(const std::pair<llvm::APSInt, EnumConstantDecl*>& lhs,
404                       const std::pair<llvm::APSInt, EnumConstantDecl*>& rhs)
405{
406  return lhs.first == rhs.first;
407}
408
409/// GetTypeBeforeIntegralPromotion - Returns the pre-promotion type of
410/// potentially integral-promoted expression @p expr.
411static QualType GetTypeBeforeIntegralPromotion(const Expr* expr) {
412  if (const CastExpr *ImplicitCast = dyn_cast<ImplicitCastExpr>(expr)) {
413    const Expr *ExprBeforePromotion = ImplicitCast->getSubExpr();
414    QualType TypeBeforePromotion = ExprBeforePromotion->getType();
415    if (TypeBeforePromotion->isIntegralOrEnumerationType()) {
416      return TypeBeforePromotion;
417    }
418  }
419  return expr->getType();
420}
421
422StmtResult
423Sema::ActOnStartOfSwitchStmt(SourceLocation SwitchLoc, Expr *Cond,
424                             Decl *CondVar) {
425  ExprResult CondResult;
426
427  VarDecl *ConditionVar = 0;
428  if (CondVar) {
429    ConditionVar = cast<VarDecl>(CondVar);
430    CondResult = CheckConditionVariable(ConditionVar, SourceLocation(), false);
431    if (CondResult.isInvalid())
432      return StmtError();
433
434    Cond = CondResult.release();
435  }
436
437  if (!Cond)
438    return StmtError();
439
440  CondResult
441    = ConvertToIntegralOrEnumerationType(SwitchLoc, Cond,
442                          PDiag(diag::err_typecheck_statement_requires_integer),
443                                   PDiag(diag::err_switch_incomplete_class_type)
444                                     << Cond->getSourceRange(),
445                                   PDiag(diag::err_switch_explicit_conversion),
446                                         PDiag(diag::note_switch_conversion),
447                                   PDiag(diag::err_switch_multiple_conversions),
448                                         PDiag(diag::note_switch_conversion),
449                                         PDiag(0));
450  if (CondResult.isInvalid()) return StmtError();
451  Cond = CondResult.take();
452
453  if (!CondVar) {
454    CheckImplicitConversions(Cond, SwitchLoc);
455    CondResult = MaybeCreateCXXExprWithTemporaries(Cond);
456    if (CondResult.isInvalid())
457      return StmtError();
458    Cond = CondResult.take();
459  }
460
461  getCurFunction()->setHasBranchIntoScope();
462
463  SwitchStmt *SS = new (Context) SwitchStmt(Context, ConditionVar, Cond);
464  getCurFunction()->SwitchStack.push_back(SS);
465  return Owned(SS);
466}
467
468static void AdjustAPSInt(llvm::APSInt &Val, unsigned BitWidth, bool IsSigned) {
469  if (Val.getBitWidth() < BitWidth)
470    Val.extend(BitWidth);
471  else if (Val.getBitWidth() > BitWidth)
472    Val.trunc(BitWidth);
473  Val.setIsSigned(IsSigned);
474}
475
476StmtResult
477Sema::ActOnFinishSwitchStmt(SourceLocation SwitchLoc, Stmt *Switch,
478                            Stmt *BodyStmt) {
479  SwitchStmt *SS = cast<SwitchStmt>(Switch);
480  assert(SS == getCurFunction()->SwitchStack.back() &&
481         "switch stack missing push/pop!");
482
483  SS->setBody(BodyStmt, SwitchLoc);
484  getCurFunction()->SwitchStack.pop_back();
485
486  if (SS->getCond() == 0)
487    return StmtError();
488
489  Expr *CondExpr = SS->getCond();
490  Expr *CondExprBeforePromotion = CondExpr;
491  QualType CondTypeBeforePromotion =
492      GetTypeBeforeIntegralPromotion(CondExpr);
493
494  // C99 6.8.4.2p5 - Integer promotions are performed on the controlling expr.
495  UsualUnaryConversions(CondExpr);
496  QualType CondType = CondExpr->getType();
497  SS->setCond(CondExpr);
498
499  // C++ 6.4.2.p2:
500  // Integral promotions are performed (on the switch condition).
501  //
502  // A case value unrepresentable by the original switch condition
503  // type (before the promotion) doesn't make sense, even when it can
504  // be represented by the promoted type.  Therefore we need to find
505  // the pre-promotion type of the switch condition.
506  if (!CondExpr->isTypeDependent()) {
507    // We have already converted the expression to an integral or enumeration
508    // type, when we started the switch statement. If we don't have an
509    // appropriate type now, just return an error.
510    if (!CondType->isIntegralOrEnumerationType())
511      return StmtError();
512
513    if (CondExpr->isKnownToHaveBooleanValue()) {
514      // switch(bool_expr) {...} is often a programmer error, e.g.
515      //   switch(n && mask) { ... }  // Doh - should be "n & mask".
516      // One can always use an if statement instead of switch(bool_expr).
517      Diag(SwitchLoc, diag::warn_bool_switch_condition)
518          << CondExpr->getSourceRange();
519    }
520  }
521
522  // Get the bitwidth of the switched-on value before promotions.  We must
523  // convert the integer case values to this width before comparison.
524  bool HasDependentValue
525    = CondExpr->isTypeDependent() || CondExpr->isValueDependent();
526  unsigned CondWidth
527    = HasDependentValue? 0
528      : static_cast<unsigned>(Context.getTypeSize(CondTypeBeforePromotion));
529  bool CondIsSigned = CondTypeBeforePromotion->isSignedIntegerType();
530
531  // Accumulate all of the case values in a vector so that we can sort them
532  // and detect duplicates.  This vector contains the APInt for the case after
533  // it has been converted to the condition type.
534  typedef llvm::SmallVector<std::pair<llvm::APSInt, CaseStmt*>, 64> CaseValsTy;
535  CaseValsTy CaseVals;
536
537  // Keep track of any GNU case ranges we see.  The APSInt is the low value.
538  typedef std::vector<std::pair<llvm::APSInt, CaseStmt*> > CaseRangesTy;
539  CaseRangesTy CaseRanges;
540
541  DefaultStmt *TheDefaultStmt = 0;
542
543  bool CaseListIsErroneous = false;
544
545  for (SwitchCase *SC = SS->getSwitchCaseList(); SC && !HasDependentValue;
546       SC = SC->getNextSwitchCase()) {
547
548    if (DefaultStmt *DS = dyn_cast<DefaultStmt>(SC)) {
549      if (TheDefaultStmt) {
550        Diag(DS->getDefaultLoc(), diag::err_multiple_default_labels_defined);
551        Diag(TheDefaultStmt->getDefaultLoc(), diag::note_duplicate_case_prev);
552
553        // FIXME: Remove the default statement from the switch block so that
554        // we'll return a valid AST.  This requires recursing down the AST and
555        // finding it, not something we are set up to do right now.  For now,
556        // just lop the entire switch stmt out of the AST.
557        CaseListIsErroneous = true;
558      }
559      TheDefaultStmt = DS;
560
561    } else {
562      CaseStmt *CS = cast<CaseStmt>(SC);
563
564      // We already verified that the expression has a i-c-e value (C99
565      // 6.8.4.2p3) - get that value now.
566      Expr *Lo = CS->getLHS();
567
568      if (Lo->isTypeDependent() || Lo->isValueDependent()) {
569        HasDependentValue = true;
570        break;
571      }
572
573      llvm::APSInt LoVal = Lo->EvaluateAsInt(Context);
574
575      // Convert the value to the same width/sign as the condition.
576      ConvertIntegerToTypeWarnOnOverflow(LoVal, CondWidth, CondIsSigned,
577                                         Lo->getLocStart(),
578                                         diag::warn_case_value_overflow);
579
580      // If the LHS is not the same type as the condition, insert an implicit
581      // cast.
582      ImpCastExprToType(Lo, CondType, CK_IntegralCast);
583      CS->setLHS(Lo);
584
585      // If this is a case range, remember it in CaseRanges, otherwise CaseVals.
586      if (CS->getRHS()) {
587        if (CS->getRHS()->isTypeDependent() ||
588            CS->getRHS()->isValueDependent()) {
589          HasDependentValue = true;
590          break;
591        }
592        CaseRanges.push_back(std::make_pair(LoVal, CS));
593      } else
594        CaseVals.push_back(std::make_pair(LoVal, CS));
595    }
596  }
597
598  if (!HasDependentValue) {
599    // If we don't have a default statement, check whether the
600    // condition is constant.
601    llvm::APSInt ConstantCondValue;
602    bool HasConstantCond = false;
603    bool ShouldCheckConstantCond = false;
604    if (!HasDependentValue && !TheDefaultStmt) {
605      Expr::EvalResult Result;
606      HasConstantCond = CondExprBeforePromotion->Evaluate(Result, Context);
607      if (HasConstantCond) {
608        assert(Result.Val.isInt() && "switch condition evaluated to non-int");
609        ConstantCondValue = Result.Val.getInt();
610        ShouldCheckConstantCond = true;
611
612        assert(ConstantCondValue.getBitWidth() == CondWidth &&
613               ConstantCondValue.isSigned() == CondIsSigned);
614      }
615    }
616
617    // Sort all the scalar case values so we can easily detect duplicates.
618    std::stable_sort(CaseVals.begin(), CaseVals.end(), CmpCaseVals);
619
620    if (!CaseVals.empty()) {
621      for (unsigned i = 0, e = CaseVals.size(); i != e; ++i) {
622        if (ShouldCheckConstantCond &&
623            CaseVals[i].first == ConstantCondValue)
624          ShouldCheckConstantCond = false;
625
626        if (i != 0 && CaseVals[i].first == CaseVals[i-1].first) {
627          // If we have a duplicate, report it.
628          Diag(CaseVals[i].second->getLHS()->getLocStart(),
629               diag::err_duplicate_case) << CaseVals[i].first.toString(10);
630          Diag(CaseVals[i-1].second->getLHS()->getLocStart(),
631               diag::note_duplicate_case_prev);
632          // FIXME: We really want to remove the bogus case stmt from the
633          // substmt, but we have no way to do this right now.
634          CaseListIsErroneous = true;
635        }
636      }
637    }
638
639    // Detect duplicate case ranges, which usually don't exist at all in
640    // the first place.
641    if (!CaseRanges.empty()) {
642      // Sort all the case ranges by their low value so we can easily detect
643      // overlaps between ranges.
644      std::stable_sort(CaseRanges.begin(), CaseRanges.end());
645
646      // Scan the ranges, computing the high values and removing empty ranges.
647      std::vector<llvm::APSInt> HiVals;
648      for (unsigned i = 0, e = CaseRanges.size(); i != e; ++i) {
649        llvm::APSInt &LoVal = CaseRanges[i].first;
650        CaseStmt *CR = CaseRanges[i].second;
651        Expr *Hi = CR->getRHS();
652        llvm::APSInt HiVal = Hi->EvaluateAsInt(Context);
653
654        // Convert the value to the same width/sign as the condition.
655        ConvertIntegerToTypeWarnOnOverflow(HiVal, CondWidth, CondIsSigned,
656                                           Hi->getLocStart(),
657                                           diag::warn_case_value_overflow);
658
659        // If the LHS is not the same type as the condition, insert an implicit
660        // cast.
661        ImpCastExprToType(Hi, CondType, CK_IntegralCast);
662        CR->setRHS(Hi);
663
664        // If the low value is bigger than the high value, the case is empty.
665        if (LoVal > HiVal) {
666          Diag(CR->getLHS()->getLocStart(), diag::warn_case_empty_range)
667            << SourceRange(CR->getLHS()->getLocStart(),
668                           Hi->getLocEnd());
669          CaseRanges.erase(CaseRanges.begin()+i);
670          --i, --e;
671          continue;
672        }
673
674        if (ShouldCheckConstantCond &&
675            LoVal <= ConstantCondValue &&
676            ConstantCondValue <= HiVal)
677          ShouldCheckConstantCond = false;
678
679        HiVals.push_back(HiVal);
680      }
681
682      // Rescan the ranges, looking for overlap with singleton values and other
683      // ranges.  Since the range list is sorted, we only need to compare case
684      // ranges with their neighbors.
685      for (unsigned i = 0, e = CaseRanges.size(); i != e; ++i) {
686        llvm::APSInt &CRLo = CaseRanges[i].first;
687        llvm::APSInt &CRHi = HiVals[i];
688        CaseStmt *CR = CaseRanges[i].second;
689
690        // Check to see whether the case range overlaps with any
691        // singleton cases.
692        CaseStmt *OverlapStmt = 0;
693        llvm::APSInt OverlapVal(32);
694
695        // Find the smallest value >= the lower bound.  If I is in the
696        // case range, then we have overlap.
697        CaseValsTy::iterator I = std::lower_bound(CaseVals.begin(),
698                                                  CaseVals.end(), CRLo,
699                                                  CaseCompareFunctor());
700        if (I != CaseVals.end() && I->first < CRHi) {
701          OverlapVal  = I->first;   // Found overlap with scalar.
702          OverlapStmt = I->second;
703        }
704
705        // Find the smallest value bigger than the upper bound.
706        I = std::upper_bound(I, CaseVals.end(), CRHi, CaseCompareFunctor());
707        if (I != CaseVals.begin() && (I-1)->first >= CRLo) {
708          OverlapVal  = (I-1)->first;      // Found overlap with scalar.
709          OverlapStmt = (I-1)->second;
710        }
711
712        // Check to see if this case stmt overlaps with the subsequent
713        // case range.
714        if (i && CRLo <= HiVals[i-1]) {
715          OverlapVal  = HiVals[i-1];       // Found overlap with range.
716          OverlapStmt = CaseRanges[i-1].second;
717        }
718
719        if (OverlapStmt) {
720          // If we have a duplicate, report it.
721          Diag(CR->getLHS()->getLocStart(), diag::err_duplicate_case)
722            << OverlapVal.toString(10);
723          Diag(OverlapStmt->getLHS()->getLocStart(),
724               diag::note_duplicate_case_prev);
725          // FIXME: We really want to remove the bogus case stmt from the
726          // substmt, but we have no way to do this right now.
727          CaseListIsErroneous = true;
728        }
729      }
730    }
731
732    // Complain if we have a constant condition and we didn't find a match.
733    if (!CaseListIsErroneous && ShouldCheckConstantCond) {
734      // TODO: it would be nice if we printed enums as enums, chars as
735      // chars, etc.
736      Diag(CondExpr->getExprLoc(), diag::warn_missing_case_for_condition)
737        << ConstantCondValue.toString(10)
738        << CondExpr->getSourceRange();
739    }
740
741    // Check to see if switch is over an Enum and handles all of its
742    // values.  We only issue a warning if there is not 'default:', but
743    // we still do the analysis to preserve this information in the AST
744    // (which can be used by flow-based analyes).
745    //
746    const EnumType *ET = CondTypeBeforePromotion->getAs<EnumType>();
747
748    // If switch has default case, then ignore it.
749    if (!CaseListIsErroneous  && !HasConstantCond && ET) {
750      const EnumDecl *ED = ET->getDecl();
751      typedef llvm::SmallVector<std::pair<llvm::APSInt, EnumConstantDecl*>, 64> EnumValsTy;
752      EnumValsTy EnumVals;
753
754      // Gather all enum values, set their type and sort them,
755      // allowing easier comparison with CaseVals.
756      for (EnumDecl::enumerator_iterator EDI = ED->enumerator_begin();
757           EDI != ED->enumerator_end(); ++EDI) {
758        llvm::APSInt Val = EDI->getInitVal();
759        AdjustAPSInt(Val, CondWidth, CondIsSigned);
760        EnumVals.push_back(std::make_pair(Val, *EDI));
761      }
762      std::stable_sort(EnumVals.begin(), EnumVals.end(), CmpEnumVals);
763      EnumValsTy::iterator EIend =
764        std::unique(EnumVals.begin(), EnumVals.end(), EqEnumVals);
765
766      // See which case values aren't in enum.
767      // TODO: we might want to check whether case values are out of the
768      // enum even if we don't want to check whether all cases are handled.
769      if (!TheDefaultStmt) {
770        EnumValsTy::const_iterator EI = EnumVals.begin();
771        for (CaseValsTy::const_iterator CI = CaseVals.begin();
772             CI != CaseVals.end(); CI++) {
773          while (EI != EIend && EI->first < CI->first)
774            EI++;
775          if (EI == EIend || EI->first > CI->first)
776            Diag(CI->second->getLHS()->getExprLoc(), diag::warn_not_in_enum)
777              << ED->getDeclName();
778        }
779        // See which of case ranges aren't in enum
780        EI = EnumVals.begin();
781        for (CaseRangesTy::const_iterator RI = CaseRanges.begin();
782             RI != CaseRanges.end() && EI != EIend; RI++) {
783          while (EI != EIend && EI->first < RI->first)
784            EI++;
785
786          if (EI == EIend || EI->first != RI->first) {
787            Diag(RI->second->getLHS()->getExprLoc(), diag::warn_not_in_enum)
788              << ED->getDeclName();
789          }
790
791          llvm::APSInt Hi = RI->second->getRHS()->EvaluateAsInt(Context);
792          AdjustAPSInt(Hi, CondWidth, CondIsSigned);
793          while (EI != EIend && EI->first < Hi)
794            EI++;
795          if (EI == EIend || EI->first != Hi)
796            Diag(RI->second->getRHS()->getExprLoc(), diag::warn_not_in_enum)
797              << ED->getDeclName();
798        }
799      }
800
801      // Check which enum vals aren't in switch
802      CaseValsTy::const_iterator CI = CaseVals.begin();
803      CaseRangesTy::const_iterator RI = CaseRanges.begin();
804      bool hasCasesNotInSwitch = false;
805
806      llvm::SmallVector<DeclarationName,8> UnhandledNames;
807
808      for (EnumValsTy::const_iterator EI = EnumVals.begin(); EI != EIend; EI++){
809        // Drop unneeded case values
810        llvm::APSInt CIVal;
811        while (CI != CaseVals.end() && CI->first < EI->first)
812          CI++;
813
814        if (CI != CaseVals.end() && CI->first == EI->first)
815          continue;
816
817        // Drop unneeded case ranges
818        for (; RI != CaseRanges.end(); RI++) {
819          llvm::APSInt Hi = RI->second->getRHS()->EvaluateAsInt(Context);
820          AdjustAPSInt(Hi, CondWidth, CondIsSigned);
821          if (EI->first <= Hi)
822            break;
823        }
824
825        if (RI == CaseRanges.end() || EI->first < RI->first) {
826          hasCasesNotInSwitch = true;
827          if (!TheDefaultStmt)
828            UnhandledNames.push_back(EI->second->getDeclName());
829        }
830      }
831
832      // Produce a nice diagnostic if multiple values aren't handled.
833      switch (UnhandledNames.size()) {
834      case 0: break;
835      case 1:
836        Diag(CondExpr->getExprLoc(), diag::warn_missing_case1)
837          << UnhandledNames[0];
838        break;
839      case 2:
840        Diag(CondExpr->getExprLoc(), diag::warn_missing_case2)
841          << UnhandledNames[0] << UnhandledNames[1];
842        break;
843      case 3:
844        Diag(CondExpr->getExprLoc(), diag::warn_missing_case3)
845          << UnhandledNames[0] << UnhandledNames[1] << UnhandledNames[2];
846        break;
847      default:
848        Diag(CondExpr->getExprLoc(), diag::warn_missing_cases)
849          << (unsigned)UnhandledNames.size()
850          << UnhandledNames[0] << UnhandledNames[1] << UnhandledNames[2];
851        break;
852      }
853
854      if (!hasCasesNotInSwitch)
855        SS->setAllEnumCasesCovered();
856    }
857  }
858
859  // FIXME: If the case list was broken is some way, we don't have a good system
860  // to patch it up.  Instead, just return the whole substmt as broken.
861  if (CaseListIsErroneous)
862    return StmtError();
863
864  return Owned(SS);
865}
866
867StmtResult
868Sema::ActOnWhileStmt(SourceLocation WhileLoc, FullExprArg Cond,
869                     Decl *CondVar, Stmt *Body) {
870  ExprResult CondResult(Cond.release());
871
872  VarDecl *ConditionVar = 0;
873  if (CondVar) {
874    ConditionVar = cast<VarDecl>(CondVar);
875    CondResult = CheckConditionVariable(ConditionVar, WhileLoc, true);
876    if (CondResult.isInvalid())
877      return StmtError();
878  }
879  Expr *ConditionExpr = CondResult.take();
880  if (!ConditionExpr)
881    return StmtError();
882
883  DiagnoseUnusedExprResult(Body);
884
885  return Owned(new (Context) WhileStmt(Context, ConditionVar, ConditionExpr,
886                                       Body, WhileLoc));
887}
888
889StmtResult
890Sema::ActOnDoStmt(SourceLocation DoLoc, Stmt *Body,
891                  SourceLocation WhileLoc, SourceLocation CondLParen,
892                  Expr *Cond, SourceLocation CondRParen) {
893  assert(Cond && "ActOnDoStmt(): missing expression");
894
895  if (CheckBooleanCondition(Cond, DoLoc))
896    return StmtError();
897
898  CheckImplicitConversions(Cond, DoLoc);
899  ExprResult CondResult = MaybeCreateCXXExprWithTemporaries(Cond);
900  if (CondResult.isInvalid())
901    return StmtError();
902  Cond = CondResult.take();
903
904  DiagnoseUnusedExprResult(Body);
905
906  return Owned(new (Context) DoStmt(Body, Cond, DoLoc, WhileLoc, CondRParen));
907}
908
909StmtResult
910Sema::ActOnForStmt(SourceLocation ForLoc, SourceLocation LParenLoc,
911                   Stmt *First, FullExprArg second, Decl *secondVar,
912                   FullExprArg third,
913                   SourceLocation RParenLoc, Stmt *Body) {
914  if (!getLangOptions().CPlusPlus) {
915    if (DeclStmt *DS = dyn_cast_or_null<DeclStmt>(First)) {
916      // C99 6.8.5p3: The declaration part of a 'for' statement shall only
917      // declare identifiers for objects having storage class 'auto' or
918      // 'register'.
919      for (DeclStmt::decl_iterator DI=DS->decl_begin(), DE=DS->decl_end();
920           DI!=DE; ++DI) {
921        VarDecl *VD = dyn_cast<VarDecl>(*DI);
922        if (VD && VD->isLocalVarDecl() && !VD->hasLocalStorage())
923          VD = 0;
924        if (VD == 0)
925          Diag((*DI)->getLocation(), diag::err_non_variable_decl_in_for);
926        // FIXME: mark decl erroneous!
927      }
928    }
929  }
930
931  ExprResult SecondResult(second.release());
932  VarDecl *ConditionVar = 0;
933  if (secondVar) {
934    ConditionVar = cast<VarDecl>(secondVar);
935    SecondResult = CheckConditionVariable(ConditionVar, ForLoc, true);
936    if (SecondResult.isInvalid())
937      return StmtError();
938  }
939
940  Expr *Third  = third.release().takeAs<Expr>();
941
942  DiagnoseUnusedExprResult(First);
943  DiagnoseUnusedExprResult(Third);
944  DiagnoseUnusedExprResult(Body);
945
946  return Owned(new (Context) ForStmt(Context, First,
947                                     SecondResult.take(), ConditionVar,
948                                     Third, Body, ForLoc, LParenLoc,
949                                     RParenLoc));
950}
951
952StmtResult
953Sema::ActOnObjCForCollectionStmt(SourceLocation ForLoc,
954                                 SourceLocation LParenLoc,
955                                 Stmt *First, Expr *Second,
956                                 SourceLocation RParenLoc, Stmt *Body) {
957  if (First) {
958    QualType FirstType;
959    if (DeclStmt *DS = dyn_cast<DeclStmt>(First)) {
960      if (!DS->isSingleDecl())
961        return StmtError(Diag((*DS->decl_begin())->getLocation(),
962                         diag::err_toomany_element_decls));
963
964      Decl *D = DS->getSingleDecl();
965      FirstType = cast<ValueDecl>(D)->getType();
966      // C99 6.8.5p3: The declaration part of a 'for' statement shall only
967      // declare identifiers for objects having storage class 'auto' or
968      // 'register'.
969      VarDecl *VD = cast<VarDecl>(D);
970      if (VD->isLocalVarDecl() && !VD->hasLocalStorage())
971        return StmtError(Diag(VD->getLocation(),
972                              diag::err_non_variable_decl_in_for));
973    } else {
974      Expr *FirstE = cast<Expr>(First);
975      if (!FirstE->isTypeDependent() &&
976          FirstE->isLvalue(Context) != Expr::LV_Valid)
977        return StmtError(Diag(First->getLocStart(),
978                   diag::err_selector_element_not_lvalue)
979          << First->getSourceRange());
980
981      FirstType = static_cast<Expr*>(First)->getType();
982    }
983    if (!FirstType->isDependentType() &&
984        !FirstType->isObjCObjectPointerType() &&
985        !FirstType->isBlockPointerType())
986        Diag(ForLoc, diag::err_selector_element_type)
987          << FirstType << First->getSourceRange();
988  }
989  if (Second && !Second->isTypeDependent()) {
990    DefaultFunctionArrayLvalueConversion(Second);
991    QualType SecondType = Second->getType();
992    if (!SecondType->isObjCObjectPointerType())
993      Diag(ForLoc, diag::err_collection_expr_type)
994        << SecondType << Second->getSourceRange();
995    else if (const ObjCObjectPointerType *OPT =
996             SecondType->getAsObjCInterfacePointerType()) {
997      llvm::SmallVector<IdentifierInfo *, 4> KeyIdents;
998      IdentifierInfo* selIdent =
999        &Context.Idents.get("countByEnumeratingWithState");
1000      KeyIdents.push_back(selIdent);
1001      selIdent = &Context.Idents.get("objects");
1002      KeyIdents.push_back(selIdent);
1003      selIdent = &Context.Idents.get("count");
1004      KeyIdents.push_back(selIdent);
1005      Selector CSelector = Context.Selectors.getSelector(3, &KeyIdents[0]);
1006      if (ObjCInterfaceDecl *IDecl = OPT->getInterfaceDecl()) {
1007        if (!IDecl->isForwardDecl() &&
1008            !IDecl->lookupInstanceMethod(CSelector)) {
1009          // Must further look into private implementation methods.
1010          if (!LookupPrivateInstanceMethod(CSelector, IDecl))
1011            Diag(ForLoc, diag::warn_collection_expr_type)
1012              << SecondType << CSelector << Second->getSourceRange();
1013        }
1014      }
1015    }
1016  }
1017  return Owned(new (Context) ObjCForCollectionStmt(First, Second, Body,
1018                                                   ForLoc, RParenLoc));
1019}
1020
1021StmtResult
1022Sema::ActOnGotoStmt(SourceLocation GotoLoc, SourceLocation LabelLoc,
1023                    IdentifierInfo *LabelII) {
1024  // Look up the record for this label identifier.
1025  LabelStmt *&LabelDecl = getCurFunction()->LabelMap[LabelII];
1026
1027  getCurFunction()->setHasBranchIntoScope();
1028
1029  // If we haven't seen this label yet, create a forward reference.
1030  if (LabelDecl == 0)
1031    LabelDecl = new (Context) LabelStmt(LabelLoc, LabelII, 0);
1032
1033  LabelDecl->setUsed();
1034  return Owned(new (Context) GotoStmt(LabelDecl, GotoLoc, LabelLoc));
1035}
1036
1037StmtResult
1038Sema::ActOnIndirectGotoStmt(SourceLocation GotoLoc, SourceLocation StarLoc,
1039                            Expr *E) {
1040  // Convert operand to void*
1041  if (!E->isTypeDependent()) {
1042    QualType ETy = E->getType();
1043    QualType DestTy = Context.getPointerType(Context.VoidTy.withConst());
1044    AssignConvertType ConvTy =
1045      CheckSingleAssignmentConstraints(DestTy, E);
1046    if (DiagnoseAssignmentResult(ConvTy, StarLoc, DestTy, ETy, E, AA_Passing))
1047      return StmtError();
1048  }
1049
1050  getCurFunction()->setHasIndirectGoto();
1051
1052  return Owned(new (Context) IndirectGotoStmt(GotoLoc, StarLoc, E));
1053}
1054
1055StmtResult
1056Sema::ActOnContinueStmt(SourceLocation ContinueLoc, Scope *CurScope) {
1057  Scope *S = CurScope->getContinueParent();
1058  if (!S) {
1059    // C99 6.8.6.2p1: A break shall appear only in or as a loop body.
1060    return StmtError(Diag(ContinueLoc, diag::err_continue_not_in_loop));
1061  }
1062
1063  return Owned(new (Context) ContinueStmt(ContinueLoc));
1064}
1065
1066StmtResult
1067Sema::ActOnBreakStmt(SourceLocation BreakLoc, Scope *CurScope) {
1068  Scope *S = CurScope->getBreakParent();
1069  if (!S) {
1070    // C99 6.8.6.3p1: A break shall appear only in or as a switch/loop body.
1071    return StmtError(Diag(BreakLoc, diag::err_break_not_in_loop_or_switch));
1072  }
1073
1074  return Owned(new (Context) BreakStmt(BreakLoc));
1075}
1076
1077/// \brief Determine whether a return statement is a candidate for the named
1078/// return value optimization (C++0x 12.8p34, bullet 1).
1079///
1080/// \param Ctx The context in which the return expression and type occur.
1081///
1082/// \param RetType The return type of the function or block.
1083///
1084/// \param RetExpr The expression being returned from the function or block.
1085///
1086/// \returns The NRVO candidate variable, if the return statement may use the
1087/// NRVO, or NULL if there is no such candidate.
1088static const VarDecl *getNRVOCandidate(ASTContext &Ctx, QualType RetType,
1089                                       Expr *RetExpr) {
1090  QualType ExprType = RetExpr->getType();
1091  // - in a return statement in a function with ...
1092  // ... a class return type ...
1093  if (!RetType->isRecordType())
1094    return 0;
1095  // ... the same cv-unqualified type as the function return type ...
1096  if (!Ctx.hasSameUnqualifiedType(RetType, ExprType))
1097    return 0;
1098  // ... the expression is the name of a non-volatile automatic object ...
1099  // We ignore parentheses here.
1100  // FIXME: Is this compliant? (Everyone else does it)
1101  const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(RetExpr->IgnoreParens());
1102  if (!DR)
1103    return 0;
1104  const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl());
1105  if (!VD)
1106    return 0;
1107
1108  if (VD->getKind() == Decl::Var && VD->hasLocalStorage() &&
1109      !VD->getType()->isReferenceType() && !VD->hasAttr<BlocksAttr>() &&
1110      !VD->getType().isVolatileQualified())
1111    return VD;
1112
1113  return 0;
1114}
1115
1116/// ActOnBlockReturnStmt - Utility routine to figure out block's return type.
1117///
1118StmtResult
1119Sema::ActOnBlockReturnStmt(SourceLocation ReturnLoc, Expr *RetValExp) {
1120  // If this is the first return we've seen in the block, infer the type of
1121  // the block from it.
1122  BlockScopeInfo *CurBlock = getCurBlock();
1123  if (CurBlock->ReturnType.isNull()) {
1124    if (RetValExp) {
1125      // Don't call UsualUnaryConversions(), since we don't want to do
1126      // integer promotions here.
1127      DefaultFunctionArrayLvalueConversion(RetValExp);
1128      CurBlock->ReturnType = RetValExp->getType();
1129      if (BlockDeclRefExpr *CDRE = dyn_cast<BlockDeclRefExpr>(RetValExp)) {
1130        // We have to remove a 'const' added to copied-in variable which was
1131        // part of the implementation spec. and not the actual qualifier for
1132        // the variable.
1133        if (CDRE->isConstQualAdded())
1134           CurBlock->ReturnType.removeConst();
1135      }
1136    } else
1137      CurBlock->ReturnType = Context.VoidTy;
1138  }
1139  QualType FnRetType = CurBlock->ReturnType;
1140
1141  if (CurBlock->TheDecl->hasAttr<NoReturnAttr>()) {
1142    Diag(ReturnLoc, diag::err_noreturn_block_has_return_expr)
1143      << getCurFunctionOrMethodDecl()->getDeclName();
1144    return StmtError();
1145  }
1146
1147  // Otherwise, verify that this result type matches the previous one.  We are
1148  // pickier with blocks than for normal functions because we don't have GCC
1149  // compatibility to worry about here.
1150  ReturnStmt *Result = 0;
1151  if (CurBlock->ReturnType->isVoidType()) {
1152    if (RetValExp) {
1153      Diag(ReturnLoc, diag::err_return_block_has_expr);
1154      RetValExp = 0;
1155    }
1156    Result = new (Context) ReturnStmt(ReturnLoc, RetValExp, 0);
1157  } else if (!RetValExp) {
1158    return StmtError(Diag(ReturnLoc, diag::err_block_return_missing_expr));
1159  } else {
1160    const VarDecl *NRVOCandidate = 0;
1161
1162    if (!FnRetType->isDependentType() && !RetValExp->isTypeDependent()) {
1163      // we have a non-void block with an expression, continue checking
1164
1165      // C99 6.8.6.4p3(136): The return statement is not an assignment. The
1166      // overlap restriction of subclause 6.5.16.1 does not apply to the case of
1167      // function return.
1168
1169      // In C++ the return statement is handled via a copy initialization.
1170      // the C version of which boils down to CheckSingleAssignmentConstraints.
1171      NRVOCandidate = getNRVOCandidate(Context, FnRetType, RetValExp);
1172      ExprResult Res = PerformCopyInitialization(
1173                               InitializedEntity::InitializeResult(ReturnLoc,
1174                                                                   FnRetType,
1175                                                            NRVOCandidate != 0),
1176                               SourceLocation(),
1177                               Owned(RetValExp));
1178      if (Res.isInvalid()) {
1179        // FIXME: Cleanup temporaries here, anyway?
1180        return StmtError();
1181      }
1182
1183      if (RetValExp) {
1184        CheckImplicitConversions(RetValExp, ReturnLoc);
1185        RetValExp = MaybeCreateCXXExprWithTemporaries(RetValExp);
1186      }
1187
1188      RetValExp = Res.takeAs<Expr>();
1189      if (RetValExp)
1190        CheckReturnStackAddr(RetValExp, FnRetType, ReturnLoc);
1191    }
1192
1193    Result = new (Context) ReturnStmt(ReturnLoc, RetValExp, NRVOCandidate);
1194  }
1195
1196  // If we need to check for the named return value optimization, save the
1197  // return statement in our scope for later processing.
1198  if (getLangOptions().CPlusPlus && FnRetType->isRecordType() &&
1199      !CurContext->isDependentContext())
1200    FunctionScopes.back()->Returns.push_back(Result);
1201
1202  return Owned(Result);
1203}
1204
1205StmtResult
1206Sema::ActOnReturnStmt(SourceLocation ReturnLoc, Expr *RetValExp) {
1207  if (getCurBlock())
1208    return ActOnBlockReturnStmt(ReturnLoc, RetValExp);
1209
1210  QualType FnRetType;
1211  if (const FunctionDecl *FD = getCurFunctionDecl()) {
1212    FnRetType = FD->getResultType();
1213    if (FD->hasAttr<NoReturnAttr>() ||
1214        FD->getType()->getAs<FunctionType>()->getNoReturnAttr())
1215      Diag(ReturnLoc, diag::warn_noreturn_function_has_return_expr)
1216        << getCurFunctionOrMethodDecl()->getDeclName();
1217  } else if (ObjCMethodDecl *MD = getCurMethodDecl())
1218    FnRetType = MD->getResultType();
1219  else // If we don't have a function/method context, bail.
1220    return StmtError();
1221
1222  ReturnStmt *Result = 0;
1223  if (FnRetType->isVoidType()) {
1224    if (RetValExp && !RetValExp->isTypeDependent()) {
1225      // C99 6.8.6.4p1 (ext_ since GCC warns)
1226      unsigned D = diag::ext_return_has_expr;
1227      if (RetValExp->getType()->isVoidType())
1228        D = diag::ext_return_has_void_expr;
1229
1230      // return (some void expression); is legal in C++.
1231      if (D != diag::ext_return_has_void_expr ||
1232          !getLangOptions().CPlusPlus) {
1233        NamedDecl *CurDecl = getCurFunctionOrMethodDecl();
1234        Diag(ReturnLoc, D)
1235          << CurDecl->getDeclName() << isa<ObjCMethodDecl>(CurDecl)
1236          << RetValExp->getSourceRange();
1237      }
1238
1239      CheckImplicitConversions(RetValExp, ReturnLoc);
1240      RetValExp = MaybeCreateCXXExprWithTemporaries(RetValExp);
1241    }
1242
1243    Result = new (Context) ReturnStmt(ReturnLoc, RetValExp, 0);
1244  } else if (!RetValExp && !FnRetType->isDependentType()) {
1245    unsigned DiagID = diag::warn_return_missing_expr;  // C90 6.6.6.4p4
1246    // C99 6.8.6.4p1 (ext_ since GCC warns)
1247    if (getLangOptions().C99) DiagID = diag::ext_return_missing_expr;
1248
1249    if (FunctionDecl *FD = getCurFunctionDecl())
1250      Diag(ReturnLoc, DiagID) << FD->getIdentifier() << 0/*fn*/;
1251    else
1252      Diag(ReturnLoc, DiagID) << getCurMethodDecl()->getDeclName() << 1/*meth*/;
1253    Result = new (Context) ReturnStmt(ReturnLoc);
1254  } else {
1255    const VarDecl *NRVOCandidate = 0;
1256    if (!FnRetType->isDependentType() && !RetValExp->isTypeDependent()) {
1257      // we have a non-void function with an expression, continue checking
1258
1259      // C99 6.8.6.4p3(136): The return statement is not an assignment. The
1260      // overlap restriction of subclause 6.5.16.1 does not apply to the case of
1261      // function return.
1262
1263      // In C++ the return statement is handled via a copy initialization.
1264      // the C version of which boils down to CheckSingleAssignmentConstraints.
1265      NRVOCandidate = getNRVOCandidate(Context, FnRetType, RetValExp);
1266      ExprResult Res = PerformCopyInitialization(
1267                               InitializedEntity::InitializeResult(ReturnLoc,
1268                                                                   FnRetType,
1269                                                            NRVOCandidate != 0),
1270                               SourceLocation(),
1271                               Owned(RetValExp));
1272      if (Res.isInvalid()) {
1273        // FIXME: Cleanup temporaries here, anyway?
1274        return StmtError();
1275      }
1276
1277      RetValExp = Res.takeAs<Expr>();
1278      if (RetValExp)
1279        CheckReturnStackAddr(RetValExp, FnRetType, ReturnLoc);
1280    }
1281
1282    if (RetValExp) {
1283      CheckImplicitConversions(RetValExp, ReturnLoc);
1284      RetValExp = MaybeCreateCXXExprWithTemporaries(RetValExp);
1285    }
1286    Result = new (Context) ReturnStmt(ReturnLoc, RetValExp, NRVOCandidate);
1287  }
1288
1289  // If we need to check for the named return value optimization, save the
1290  // return statement in our scope for later processing.
1291  if (getLangOptions().CPlusPlus && FnRetType->isRecordType() &&
1292      !CurContext->isDependentContext())
1293    FunctionScopes.back()->Returns.push_back(Result);
1294
1295  return Owned(Result);
1296}
1297
1298/// CheckAsmLValue - GNU C has an extremely ugly extension whereby they silently
1299/// ignore "noop" casts in places where an lvalue is required by an inline asm.
1300/// We emulate this behavior when -fheinous-gnu-extensions is specified, but
1301/// provide a strong guidance to not use it.
1302///
1303/// This method checks to see if the argument is an acceptable l-value and
1304/// returns false if it is a case we can handle.
1305static bool CheckAsmLValue(const Expr *E, Sema &S) {
1306  // Type dependent expressions will be checked during instantiation.
1307  if (E->isTypeDependent())
1308    return false;
1309
1310  if (E->isLvalue(S.Context) == Expr::LV_Valid)
1311    return false;  // Cool, this is an lvalue.
1312
1313  // Okay, this is not an lvalue, but perhaps it is the result of a cast that we
1314  // are supposed to allow.
1315  const Expr *E2 = E->IgnoreParenNoopCasts(S.Context);
1316  if (E != E2 && E2->isLvalue(S.Context) == Expr::LV_Valid) {
1317    if (!S.getLangOptions().HeinousExtensions)
1318      S.Diag(E2->getLocStart(), diag::err_invalid_asm_cast_lvalue)
1319        << E->getSourceRange();
1320    else
1321      S.Diag(E2->getLocStart(), diag::warn_invalid_asm_cast_lvalue)
1322        << E->getSourceRange();
1323    // Accept, even if we emitted an error diagnostic.
1324    return false;
1325  }
1326
1327  // None of the above, just randomly invalid non-lvalue.
1328  return true;
1329}
1330
1331
1332StmtResult Sema::ActOnAsmStmt(SourceLocation AsmLoc,
1333                                          bool IsSimple,
1334                                          bool IsVolatile,
1335                                          unsigned NumOutputs,
1336                                          unsigned NumInputs,
1337                                          IdentifierInfo **Names,
1338                                          MultiExprArg constraints,
1339                                          MultiExprArg exprs,
1340                                          Expr *asmString,
1341                                          MultiExprArg clobbers,
1342                                          SourceLocation RParenLoc,
1343                                          bool MSAsm) {
1344  unsigned NumClobbers = clobbers.size();
1345  StringLiteral **Constraints =
1346    reinterpret_cast<StringLiteral**>(constraints.get());
1347  Expr **Exprs = exprs.get();
1348  StringLiteral *AsmString = cast<StringLiteral>(asmString);
1349  StringLiteral **Clobbers = reinterpret_cast<StringLiteral**>(clobbers.get());
1350
1351  llvm::SmallVector<TargetInfo::ConstraintInfo, 4> OutputConstraintInfos;
1352
1353  // The parser verifies that there is a string literal here.
1354  if (AsmString->isWide())
1355    return StmtError(Diag(AsmString->getLocStart(),diag::err_asm_wide_character)
1356      << AsmString->getSourceRange());
1357
1358  for (unsigned i = 0; i != NumOutputs; i++) {
1359    StringLiteral *Literal = Constraints[i];
1360    if (Literal->isWide())
1361      return StmtError(Diag(Literal->getLocStart(),diag::err_asm_wide_character)
1362        << Literal->getSourceRange());
1363
1364    llvm::StringRef OutputName;
1365    if (Names[i])
1366      OutputName = Names[i]->getName();
1367
1368    TargetInfo::ConstraintInfo Info(Literal->getString(), OutputName);
1369    if (!Context.Target.validateOutputConstraint(Info))
1370      return StmtError(Diag(Literal->getLocStart(),
1371                            diag::err_asm_invalid_output_constraint)
1372                       << Info.getConstraintStr());
1373
1374    // Check that the output exprs are valid lvalues.
1375    Expr *OutputExpr = Exprs[i];
1376    if (CheckAsmLValue(OutputExpr, *this)) {
1377      return StmtError(Diag(OutputExpr->getLocStart(),
1378                  diag::err_asm_invalid_lvalue_in_output)
1379        << OutputExpr->getSourceRange());
1380    }
1381
1382    OutputConstraintInfos.push_back(Info);
1383  }
1384
1385  llvm::SmallVector<TargetInfo::ConstraintInfo, 4> InputConstraintInfos;
1386
1387  for (unsigned i = NumOutputs, e = NumOutputs + NumInputs; i != e; i++) {
1388    StringLiteral *Literal = Constraints[i];
1389    if (Literal->isWide())
1390      return StmtError(Diag(Literal->getLocStart(),diag::err_asm_wide_character)
1391        << Literal->getSourceRange());
1392
1393    llvm::StringRef InputName;
1394    if (Names[i])
1395      InputName = Names[i]->getName();
1396
1397    TargetInfo::ConstraintInfo Info(Literal->getString(), InputName);
1398    if (!Context.Target.validateInputConstraint(OutputConstraintInfos.data(),
1399                                                NumOutputs, Info)) {
1400      return StmtError(Diag(Literal->getLocStart(),
1401                            diag::err_asm_invalid_input_constraint)
1402                       << Info.getConstraintStr());
1403    }
1404
1405    Expr *InputExpr = Exprs[i];
1406
1407    // Only allow void types for memory constraints.
1408    if (Info.allowsMemory() && !Info.allowsRegister()) {
1409      if (CheckAsmLValue(InputExpr, *this))
1410        return StmtError(Diag(InputExpr->getLocStart(),
1411                              diag::err_asm_invalid_lvalue_in_input)
1412                         << Info.getConstraintStr()
1413                         << InputExpr->getSourceRange());
1414    }
1415
1416    if (Info.allowsRegister()) {
1417      if (InputExpr->getType()->isVoidType()) {
1418        return StmtError(Diag(InputExpr->getLocStart(),
1419                              diag::err_asm_invalid_type_in_input)
1420          << InputExpr->getType() << Info.getConstraintStr()
1421          << InputExpr->getSourceRange());
1422      }
1423    }
1424
1425    DefaultFunctionArrayLvalueConversion(Exprs[i]);
1426
1427    InputConstraintInfos.push_back(Info);
1428  }
1429
1430  // Check that the clobbers are valid.
1431  for (unsigned i = 0; i != NumClobbers; i++) {
1432    StringLiteral *Literal = Clobbers[i];
1433    if (Literal->isWide())
1434      return StmtError(Diag(Literal->getLocStart(),diag::err_asm_wide_character)
1435        << Literal->getSourceRange());
1436
1437    llvm::StringRef Clobber = Literal->getString();
1438
1439    if (!Context.Target.isValidGCCRegisterName(Clobber))
1440      return StmtError(Diag(Literal->getLocStart(),
1441                  diag::err_asm_unknown_register_name) << Clobber);
1442  }
1443
1444  AsmStmt *NS =
1445    new (Context) AsmStmt(Context, AsmLoc, IsSimple, IsVolatile, MSAsm,
1446                          NumOutputs, NumInputs, Names, Constraints, Exprs,
1447                          AsmString, NumClobbers, Clobbers, RParenLoc);
1448  // Validate the asm string, ensuring it makes sense given the operands we
1449  // have.
1450  llvm::SmallVector<AsmStmt::AsmStringPiece, 8> Pieces;
1451  unsigned DiagOffs;
1452  if (unsigned DiagID = NS->AnalyzeAsmString(Pieces, Context, DiagOffs)) {
1453    Diag(getLocationOfStringLiteralByte(AsmString, DiagOffs), DiagID)
1454           << AsmString->getSourceRange();
1455    return StmtError();
1456  }
1457
1458  // Validate tied input operands for type mismatches.
1459  for (unsigned i = 0, e = InputConstraintInfos.size(); i != e; ++i) {
1460    TargetInfo::ConstraintInfo &Info = InputConstraintInfos[i];
1461
1462    // If this is a tied constraint, verify that the output and input have
1463    // either exactly the same type, or that they are int/ptr operands with the
1464    // same size (int/long, int*/long, are ok etc).
1465    if (!Info.hasTiedOperand()) continue;
1466
1467    unsigned TiedTo = Info.getTiedOperand();
1468    Expr *OutputExpr = Exprs[TiedTo];
1469    Expr *InputExpr = Exprs[i+NumOutputs];
1470    QualType InTy = InputExpr->getType();
1471    QualType OutTy = OutputExpr->getType();
1472    if (Context.hasSameType(InTy, OutTy))
1473      continue;  // All types can be tied to themselves.
1474
1475    // Decide if the input and output are in the same domain (integer/ptr or
1476    // floating point.
1477    enum AsmDomain {
1478      AD_Int, AD_FP, AD_Other
1479    } InputDomain, OutputDomain;
1480
1481    if (InTy->isIntegerType() || InTy->isPointerType())
1482      InputDomain = AD_Int;
1483    else if (InTy->isRealFloatingType())
1484      InputDomain = AD_FP;
1485    else
1486      InputDomain = AD_Other;
1487
1488    if (OutTy->isIntegerType() || OutTy->isPointerType())
1489      OutputDomain = AD_Int;
1490    else if (OutTy->isRealFloatingType())
1491      OutputDomain = AD_FP;
1492    else
1493      OutputDomain = AD_Other;
1494
1495    // They are ok if they are the same size and in the same domain.  This
1496    // allows tying things like:
1497    //   void* to int*
1498    //   void* to int            if they are the same size.
1499    //   double to long double   if they are the same size.
1500    //
1501    uint64_t OutSize = Context.getTypeSize(OutTy);
1502    uint64_t InSize = Context.getTypeSize(InTy);
1503    if (OutSize == InSize && InputDomain == OutputDomain &&
1504        InputDomain != AD_Other)
1505      continue;
1506
1507    // If the smaller input/output operand is not mentioned in the asm string,
1508    // then we can promote it and the asm string won't notice.  Check this
1509    // case now.
1510    bool SmallerValueMentioned = false;
1511    for (unsigned p = 0, e = Pieces.size(); p != e; ++p) {
1512      AsmStmt::AsmStringPiece &Piece = Pieces[p];
1513      if (!Piece.isOperand()) continue;
1514
1515      // If this is a reference to the input and if the input was the smaller
1516      // one, then we have to reject this asm.
1517      if (Piece.getOperandNo() == i+NumOutputs) {
1518        if (InSize < OutSize) {
1519          SmallerValueMentioned = true;
1520          break;
1521        }
1522      }
1523
1524      // If this is a reference to the input and if the input was the smaller
1525      // one, then we have to reject this asm.
1526      if (Piece.getOperandNo() == TiedTo) {
1527        if (InSize > OutSize) {
1528          SmallerValueMentioned = true;
1529          break;
1530        }
1531      }
1532    }
1533
1534    // If the smaller value wasn't mentioned in the asm string, and if the
1535    // output was a register, just extend the shorter one to the size of the
1536    // larger one.
1537    if (!SmallerValueMentioned && InputDomain != AD_Other &&
1538        OutputConstraintInfos[TiedTo].allowsRegister())
1539      continue;
1540
1541    Diag(InputExpr->getLocStart(),
1542         diag::err_asm_tying_incompatible_types)
1543      << InTy << OutTy << OutputExpr->getSourceRange()
1544      << InputExpr->getSourceRange();
1545    return StmtError();
1546  }
1547
1548  return Owned(NS);
1549}
1550
1551StmtResult
1552Sema::ActOnObjCAtCatchStmt(SourceLocation AtLoc,
1553                           SourceLocation RParen, Decl *Parm,
1554                           Stmt *Body) {
1555  VarDecl *Var = cast_or_null<VarDecl>(Parm);
1556  if (Var && Var->isInvalidDecl())
1557    return StmtError();
1558
1559  return Owned(new (Context) ObjCAtCatchStmt(AtLoc, RParen, Var, Body));
1560}
1561
1562StmtResult
1563Sema::ActOnObjCAtFinallyStmt(SourceLocation AtLoc, Stmt *Body) {
1564  return Owned(new (Context) ObjCAtFinallyStmt(AtLoc, Body));
1565}
1566
1567StmtResult
1568Sema::ActOnObjCAtTryStmt(SourceLocation AtLoc, Stmt *Try,
1569                         MultiStmtArg CatchStmts, Stmt *Finally) {
1570  getCurFunction()->setHasBranchProtectedScope();
1571  unsigned NumCatchStmts = CatchStmts.size();
1572  return Owned(ObjCAtTryStmt::Create(Context, AtLoc, Try,
1573                                     CatchStmts.release(),
1574                                     NumCatchStmts,
1575                                     Finally));
1576}
1577
1578StmtResult Sema::BuildObjCAtThrowStmt(SourceLocation AtLoc,
1579                                                  Expr *Throw) {
1580  if (Throw) {
1581    QualType ThrowType = Throw->getType();
1582    // Make sure the expression type is an ObjC pointer or "void *".
1583    if (!ThrowType->isDependentType() &&
1584        !ThrowType->isObjCObjectPointerType()) {
1585      const PointerType *PT = ThrowType->getAs<PointerType>();
1586      if (!PT || !PT->getPointeeType()->isVoidType())
1587        return StmtError(Diag(AtLoc, diag::error_objc_throw_expects_object)
1588                         << Throw->getType() << Throw->getSourceRange());
1589    }
1590  }
1591
1592  return Owned(new (Context) ObjCAtThrowStmt(AtLoc, Throw));
1593}
1594
1595StmtResult
1596Sema::ActOnObjCAtThrowStmt(SourceLocation AtLoc, Expr *Throw,
1597                           Scope *CurScope) {
1598  if (!Throw) {
1599    // @throw without an expression designates a rethrow (which much occur
1600    // in the context of an @catch clause).
1601    Scope *AtCatchParent = CurScope;
1602    while (AtCatchParent && !AtCatchParent->isAtCatchScope())
1603      AtCatchParent = AtCatchParent->getParent();
1604    if (!AtCatchParent)
1605      return StmtError(Diag(AtLoc, diag::error_rethrow_used_outside_catch));
1606  }
1607
1608  return BuildObjCAtThrowStmt(AtLoc, Throw);
1609}
1610
1611StmtResult
1612Sema::ActOnObjCAtSynchronizedStmt(SourceLocation AtLoc, Expr *SyncExpr,
1613                                  Stmt *SyncBody) {
1614  getCurFunction()->setHasBranchProtectedScope();
1615
1616  // Make sure the expression type is an ObjC pointer or "void *".
1617  if (!SyncExpr->getType()->isDependentType() &&
1618      !SyncExpr->getType()->isObjCObjectPointerType()) {
1619    const PointerType *PT = SyncExpr->getType()->getAs<PointerType>();
1620    if (!PT || !PT->getPointeeType()->isVoidType())
1621      return StmtError(Diag(AtLoc, diag::error_objc_synchronized_expects_object)
1622                       << SyncExpr->getType() << SyncExpr->getSourceRange());
1623  }
1624
1625  return Owned(new (Context) ObjCAtSynchronizedStmt(AtLoc, SyncExpr, SyncBody));
1626}
1627
1628/// ActOnCXXCatchBlock - Takes an exception declaration and a handler block
1629/// and creates a proper catch handler from them.
1630StmtResult
1631Sema::ActOnCXXCatchBlock(SourceLocation CatchLoc, Decl *ExDecl,
1632                         Stmt *HandlerBlock) {
1633  // There's nothing to test that ActOnExceptionDecl didn't already test.
1634  return Owned(new (Context) CXXCatchStmt(CatchLoc,
1635                                          cast_or_null<VarDecl>(ExDecl),
1636                                          HandlerBlock));
1637}
1638
1639namespace {
1640
1641class TypeWithHandler {
1642  QualType t;
1643  CXXCatchStmt *stmt;
1644public:
1645  TypeWithHandler(const QualType &type, CXXCatchStmt *statement)
1646  : t(type), stmt(statement) {}
1647
1648  // An arbitrary order is fine as long as it places identical
1649  // types next to each other.
1650  bool operator<(const TypeWithHandler &y) const {
1651    if (t.getAsOpaquePtr() < y.t.getAsOpaquePtr())
1652      return true;
1653    if (t.getAsOpaquePtr() > y.t.getAsOpaquePtr())
1654      return false;
1655    else
1656      return getTypeSpecStartLoc() < y.getTypeSpecStartLoc();
1657  }
1658
1659  bool operator==(const TypeWithHandler& other) const {
1660    return t == other.t;
1661  }
1662
1663  CXXCatchStmt *getCatchStmt() const { return stmt; }
1664  SourceLocation getTypeSpecStartLoc() const {
1665    return stmt->getExceptionDecl()->getTypeSpecStartLoc();
1666  }
1667};
1668
1669}
1670
1671/// ActOnCXXTryBlock - Takes a try compound-statement and a number of
1672/// handlers and creates a try statement from them.
1673StmtResult
1674Sema::ActOnCXXTryBlock(SourceLocation TryLoc, Stmt *TryBlock,
1675                       MultiStmtArg RawHandlers) {
1676  unsigned NumHandlers = RawHandlers.size();
1677  assert(NumHandlers > 0 &&
1678         "The parser shouldn't call this if there are no handlers.");
1679  Stmt **Handlers = RawHandlers.get();
1680
1681  llvm::SmallVector<TypeWithHandler, 8> TypesWithHandlers;
1682
1683  for (unsigned i = 0; i < NumHandlers; ++i) {
1684    CXXCatchStmt *Handler = llvm::cast<CXXCatchStmt>(Handlers[i]);
1685    if (!Handler->getExceptionDecl()) {
1686      if (i < NumHandlers - 1)
1687        return StmtError(Diag(Handler->getLocStart(),
1688                              diag::err_early_catch_all));
1689
1690      continue;
1691    }
1692
1693    const QualType CaughtType = Handler->getCaughtType();
1694    const QualType CanonicalCaughtType = Context.getCanonicalType(CaughtType);
1695    TypesWithHandlers.push_back(TypeWithHandler(CanonicalCaughtType, Handler));
1696  }
1697
1698  // Detect handlers for the same type as an earlier one.
1699  if (NumHandlers > 1) {
1700    llvm::array_pod_sort(TypesWithHandlers.begin(), TypesWithHandlers.end());
1701
1702    TypeWithHandler prev = TypesWithHandlers[0];
1703    for (unsigned i = 1; i < TypesWithHandlers.size(); ++i) {
1704      TypeWithHandler curr = TypesWithHandlers[i];
1705
1706      if (curr == prev) {
1707        Diag(curr.getTypeSpecStartLoc(),
1708             diag::warn_exception_caught_by_earlier_handler)
1709          << curr.getCatchStmt()->getCaughtType().getAsString();
1710        Diag(prev.getTypeSpecStartLoc(),
1711             diag::note_previous_exception_handler)
1712          << prev.getCatchStmt()->getCaughtType().getAsString();
1713      }
1714
1715      prev = curr;
1716    }
1717  }
1718
1719  getCurFunction()->setHasBranchProtectedScope();
1720
1721  // FIXME: We should detect handlers that cannot catch anything because an
1722  // earlier handler catches a superclass. Need to find a method that is not
1723  // quadratic for this.
1724  // Neither of these are explicitly forbidden, but every compiler detects them
1725  // and warns.
1726
1727  return Owned(CXXTryStmt::Create(Context, TryLoc, TryBlock,
1728                                  Handlers, NumHandlers));
1729}
1730