SemaStmt.cpp revision 908200b4754e1544a13c602c412e66ce32d74635 
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  llvm::OwningPtr<const AttributeList> AttrList(Attr);
242  for (const AttributeList* a = AttrList.get(); a; a = a->getNext()) {
243    if (a->getKind() == AttributeList::AT_unused) {
244      HasUnusedAttr = true;
245    } else {
246      Diag(a->getLoc(), diag::warn_label_attribute_not_unused);
247      a->setInvalid(true);
248    }
249  }
250
251  return ActOnLabelStmt(IdentLoc, II, ColonLoc, SubStmt, HasUnusedAttr);
252}
253
254StmtResult
255Sema::ActOnLabelStmt(SourceLocation IdentLoc, IdentifierInfo *II,
256                     SourceLocation ColonLoc, Stmt *SubStmt,
257                     bool HasUnusedAttr) {
258  // Look up the record for this label identifier.
259  LabelStmt *&LabelDecl = getCurFunction()->LabelMap[II];
260
261  // If not forward referenced or defined already, just create a new LabelStmt.
262  if (LabelDecl == 0)
263    return Owned(LabelDecl = new (Context) LabelStmt(IdentLoc, II, SubStmt,
264                                                     HasUnusedAttr));
265
266  assert(LabelDecl->getID() == II && "Label mismatch!");
267
268  // Otherwise, this label was either forward reference or multiply defined.  If
269  // multiply defined, reject it now.
270  if (LabelDecl->getSubStmt()) {
271    Diag(IdentLoc, diag::err_redefinition_of_label) << LabelDecl->getID();
272    Diag(LabelDecl->getIdentLoc(), diag::note_previous_definition);
273    return Owned(SubStmt);
274  }
275
276  // Otherwise, this label was forward declared, and we just found its real
277  // definition.  Fill in the forward definition and return it.
278  LabelDecl->setIdentLoc(IdentLoc);
279  LabelDecl->setSubStmt(SubStmt);
280  LabelDecl->setUnusedAttribute(HasUnusedAttr);
281  return Owned(LabelDecl);
282}
283
284StmtResult
285Sema::ActOnIfStmt(SourceLocation IfLoc, FullExprArg CondVal, Decl *CondVar,
286                  Stmt *thenStmt, SourceLocation ElseLoc,
287                  Stmt *elseStmt) {
288  ExprResult CondResult(CondVal.release());
289
290  VarDecl *ConditionVar = 0;
291  if (CondVar) {
292    ConditionVar = cast<VarDecl>(CondVar);
293    CondResult = CheckConditionVariable(ConditionVar, IfLoc, true);
294    if (CondResult.isInvalid())
295      return StmtError();
296  }
297  Expr *ConditionExpr = CondResult.takeAs<Expr>();
298  if (!ConditionExpr)
299    return StmtError();
300
301  DiagnoseUnusedExprResult(thenStmt);
302
303  // Warn if the if block has a null body without an else value.
304  // this helps prevent bugs due to typos, such as
305  // if (condition);
306  //   do_stuff();
307  //
308  // NOTE: Do not emit this warning if the body is expanded from a macro.
309  if (!elseStmt) {
310    if (NullStmt* stmt = dyn_cast<NullStmt>(thenStmt))
311      if (!stmt->getLocStart().isMacroID())
312        Diag(stmt->getSemiLoc(), diag::warn_empty_if_body);
313  }
314
315  DiagnoseUnusedExprResult(elseStmt);
316
317  return Owned(new (Context) IfStmt(Context, IfLoc, ConditionVar, ConditionExpr,
318                                    thenStmt, ElseLoc, elseStmt));
319}
320
321/// ConvertIntegerToTypeWarnOnOverflow - Convert the specified APInt to have
322/// the specified width and sign.  If an overflow occurs, detect it and emit
323/// the specified diagnostic.
324void Sema::ConvertIntegerToTypeWarnOnOverflow(llvm::APSInt &Val,
325                                              unsigned NewWidth, bool NewSign,
326                                              SourceLocation Loc,
327                                              unsigned DiagID) {
328  // Perform a conversion to the promoted condition type if needed.
329  if (NewWidth > Val.getBitWidth()) {
330    // If this is an extension, just do it.
331    Val.extend(NewWidth);
332    Val.setIsSigned(NewSign);
333
334    // If the input was signed and negative and the output is
335    // unsigned, don't bother to warn: this is implementation-defined
336    // behavior.
337    // FIXME: Introduce a second, default-ignored warning for this case?
338  } else if (NewWidth < Val.getBitWidth()) {
339    // If this is a truncation, check for overflow.
340    llvm::APSInt ConvVal(Val);
341    ConvVal.trunc(NewWidth);
342    ConvVal.setIsSigned(NewSign);
343    ConvVal.extend(Val.getBitWidth());
344    ConvVal.setIsSigned(Val.isSigned());
345    if (ConvVal != Val)
346      Diag(Loc, DiagID) << Val.toString(10) << ConvVal.toString(10);
347
348    // Regardless of whether a diagnostic was emitted, really do the
349    // truncation.
350    Val.trunc(NewWidth);
351    Val.setIsSigned(NewSign);
352  } else if (NewSign != Val.isSigned()) {
353    // Convert the sign to match the sign of the condition.  This can cause
354    // overflow as well: unsigned(INTMIN)
355    // We don't diagnose this overflow, because it is implementation-defined
356    // behavior.
357    // FIXME: Introduce a second, default-ignored warning for this case?
358    llvm::APSInt OldVal(Val);
359    Val.setIsSigned(NewSign);
360  }
361}
362
363namespace {
364  struct CaseCompareFunctor {
365    bool operator()(const std::pair<llvm::APSInt, CaseStmt*> &LHS,
366                    const llvm::APSInt &RHS) {
367      return LHS.first < RHS;
368    }
369    bool operator()(const std::pair<llvm::APSInt, CaseStmt*> &LHS,
370                    const std::pair<llvm::APSInt, CaseStmt*> &RHS) {
371      return LHS.first < RHS.first;
372    }
373    bool operator()(const llvm::APSInt &LHS,
374                    const std::pair<llvm::APSInt, CaseStmt*> &RHS) {
375      return LHS < RHS.first;
376    }
377  };
378}
379
380/// CmpCaseVals - Comparison predicate for sorting case values.
381///
382static bool CmpCaseVals(const std::pair<llvm::APSInt, CaseStmt*>& lhs,
383                        const std::pair<llvm::APSInt, CaseStmt*>& rhs) {
384  if (lhs.first < rhs.first)
385    return true;
386
387  if (lhs.first == rhs.first &&
388      lhs.second->getCaseLoc().getRawEncoding()
389       < rhs.second->getCaseLoc().getRawEncoding())
390    return true;
391  return false;
392}
393
394/// CmpEnumVals - Comparison predicate for sorting enumeration values.
395///
396static bool CmpEnumVals(const std::pair<llvm::APSInt, EnumConstantDecl*>& lhs,
397                        const std::pair<llvm::APSInt, EnumConstantDecl*>& rhs)
398{
399  return lhs.first < rhs.first;
400}
401
402/// EqEnumVals - Comparison preficate for uniqing enumeration values.
403///
404static bool EqEnumVals(const std::pair<llvm::APSInt, EnumConstantDecl*>& lhs,
405                       const std::pair<llvm::APSInt, EnumConstantDecl*>& rhs)
406{
407  return lhs.first == rhs.first;
408}
409
410/// GetTypeBeforeIntegralPromotion - Returns the pre-promotion type of
411/// potentially integral-promoted expression @p expr.
412static QualType GetTypeBeforeIntegralPromotion(const Expr* expr) {
413  if (const CastExpr *ImplicitCast = dyn_cast<ImplicitCastExpr>(expr)) {
414    const Expr *ExprBeforePromotion = ImplicitCast->getSubExpr();
415    QualType TypeBeforePromotion = ExprBeforePromotion->getType();
416    if (TypeBeforePromotion->isIntegralOrEnumerationType()) {
417      return TypeBeforePromotion;
418    }
419  }
420  return expr->getType();
421}
422
423StmtResult
424Sema::ActOnStartOfSwitchStmt(SourceLocation SwitchLoc, Expr *Cond,
425                             Decl *CondVar) {
426  ExprResult CondResult;
427
428  VarDecl *ConditionVar = 0;
429  if (CondVar) {
430    ConditionVar = cast<VarDecl>(CondVar);
431    CondResult = CheckConditionVariable(ConditionVar, SourceLocation(), false);
432    if (CondResult.isInvalid())
433      return StmtError();
434
435    Cond = CondResult.release();
436  }
437
438  if (!Cond)
439    return StmtError();
440
441  CondResult
442    = ConvertToIntegralOrEnumerationType(SwitchLoc, Cond,
443                          PDiag(diag::err_typecheck_statement_requires_integer),
444                                   PDiag(diag::err_switch_incomplete_class_type)
445                                     << Cond->getSourceRange(),
446                                   PDiag(diag::err_switch_explicit_conversion),
447                                         PDiag(diag::note_switch_conversion),
448                                   PDiag(diag::err_switch_multiple_conversions),
449                                         PDiag(diag::note_switch_conversion),
450                                         PDiag(0));
451  if (CondResult.isInvalid()) return StmtError();
452  Cond = CondResult.take();
453
454  if (!CondVar) {
455    CheckImplicitConversions(Cond, SwitchLoc);
456    CondResult = MaybeCreateCXXExprWithTemporaries(Cond);
457    if (CondResult.isInvalid())
458      return StmtError();
459    Cond = CondResult.take();
460  }
461
462  getCurFunction()->setHasBranchIntoScope();
463
464  SwitchStmt *SS = new (Context) SwitchStmt(Context, ConditionVar, Cond);
465  getCurFunction()->SwitchStack.push_back(SS);
466  return Owned(SS);
467}
468
469static void AdjustAPSInt(llvm::APSInt &Val, unsigned BitWidth, bool IsSigned) {
470  if (Val.getBitWidth() < BitWidth)
471    Val.extend(BitWidth);
472  else if (Val.getBitWidth() > BitWidth)
473    Val.trunc(BitWidth);
474  Val.setIsSigned(IsSigned);
475}
476
477StmtResult
478Sema::ActOnFinishSwitchStmt(SourceLocation SwitchLoc, Stmt *Switch,
479                            Stmt *BodyStmt) {
480  SwitchStmt *SS = cast<SwitchStmt>(Switch);
481  assert(SS == getCurFunction()->SwitchStack.back() &&
482         "switch stack missing push/pop!");
483
484  SS->setBody(BodyStmt, SwitchLoc);
485  getCurFunction()->SwitchStack.pop_back();
486
487  if (SS->getCond() == 0)
488    return StmtError();
489
490  Expr *CondExpr = SS->getCond();
491  Expr *CondExprBeforePromotion = CondExpr;
492  QualType CondTypeBeforePromotion =
493      GetTypeBeforeIntegralPromotion(CondExpr);
494
495  // C99 6.8.4.2p5 - Integer promotions are performed on the controlling expr.
496  UsualUnaryConversions(CondExpr);
497  QualType CondType = CondExpr->getType();
498  SS->setCond(CondExpr);
499
500  // C++ 6.4.2.p2:
501  // Integral promotions are performed (on the switch condition).
502  //
503  // A case value unrepresentable by the original switch condition
504  // type (before the promotion) doesn't make sense, even when it can
505  // be represented by the promoted type.  Therefore we need to find
506  // the pre-promotion type of the switch condition.
507  if (!CondExpr->isTypeDependent()) {
508    // We have already converted the expression to an integral or enumeration
509    // type, when we started the switch statement. If we don't have an
510    // appropriate type now, just return an error.
511    if (!CondType->isIntegralOrEnumerationType())
512      return StmtError();
513
514    if (CondExpr->isKnownToHaveBooleanValue()) {
515      // switch(bool_expr) {...} is often a programmer error, e.g.
516      //   switch(n && mask) { ... }  // Doh - should be "n & mask".
517      // One can always use an if statement instead of switch(bool_expr).
518      Diag(SwitchLoc, diag::warn_bool_switch_condition)
519          << CondExpr->getSourceRange();
520    }
521  }
522
523  // Get the bitwidth of the switched-on value before promotions.  We must
524  // convert the integer case values to this width before comparison.
525  bool HasDependentValue
526    = CondExpr->isTypeDependent() || CondExpr->isValueDependent();
527  unsigned CondWidth
528    = HasDependentValue? 0
529      : static_cast<unsigned>(Context.getTypeSize(CondTypeBeforePromotion));
530  bool CondIsSigned = CondTypeBeforePromotion->isSignedIntegerType();
531
532  // Accumulate all of the case values in a vector so that we can sort them
533  // and detect duplicates.  This vector contains the APInt for the case after
534  // it has been converted to the condition type.
535  typedef llvm::SmallVector<std::pair<llvm::APSInt, CaseStmt*>, 64> CaseValsTy;
536  CaseValsTy CaseVals;
537
538  // Keep track of any GNU case ranges we see.  The APSInt is the low value.
539  typedef std::vector<std::pair<llvm::APSInt, CaseStmt*> > CaseRangesTy;
540  CaseRangesTy CaseRanges;
541
542  DefaultStmt *TheDefaultStmt = 0;
543
544  bool CaseListIsErroneous = false;
545
546  for (SwitchCase *SC = SS->getSwitchCaseList(); SC && !HasDependentValue;
547       SC = SC->getNextSwitchCase()) {
548
549    if (DefaultStmt *DS = dyn_cast<DefaultStmt>(SC)) {
550      if (TheDefaultStmt) {
551        Diag(DS->getDefaultLoc(), diag::err_multiple_default_labels_defined);
552        Diag(TheDefaultStmt->getDefaultLoc(), diag::note_duplicate_case_prev);
553
554        // FIXME: Remove the default statement from the switch block so that
555        // we'll return a valid AST.  This requires recursing down the AST and
556        // finding it, not something we are set up to do right now.  For now,
557        // just lop the entire switch stmt out of the AST.
558        CaseListIsErroneous = true;
559      }
560      TheDefaultStmt = DS;
561
562    } else {
563      CaseStmt *CS = cast<CaseStmt>(SC);
564
565      // We already verified that the expression has a i-c-e value (C99
566      // 6.8.4.2p3) - get that value now.
567      Expr *Lo = CS->getLHS();
568
569      if (Lo->isTypeDependent() || Lo->isValueDependent()) {
570        HasDependentValue = true;
571        break;
572      }
573
574      llvm::APSInt LoVal = Lo->EvaluateAsInt(Context);
575
576      // Convert the value to the same width/sign as the condition.
577      ConvertIntegerToTypeWarnOnOverflow(LoVal, CondWidth, CondIsSigned,
578                                         Lo->getLocStart(),
579                                         diag::warn_case_value_overflow);
580
581      // If the LHS is not the same type as the condition, insert an implicit
582      // cast.
583      ImpCastExprToType(Lo, CondType, CK_IntegralCast);
584      CS->setLHS(Lo);
585
586      // If this is a case range, remember it in CaseRanges, otherwise CaseVals.
587      if (CS->getRHS()) {
588        if (CS->getRHS()->isTypeDependent() ||
589            CS->getRHS()->isValueDependent()) {
590          HasDependentValue = true;
591          break;
592        }
593        CaseRanges.push_back(std::make_pair(LoVal, CS));
594      } else
595        CaseVals.push_back(std::make_pair(LoVal, CS));
596    }
597  }
598
599  if (!HasDependentValue) {
600    // If we don't have a default statement, check whether the
601    // condition is constant.
602    llvm::APSInt ConstantCondValue;
603    bool HasConstantCond = false;
604    bool ShouldCheckConstantCond = false;
605    if (!HasDependentValue && !TheDefaultStmt) {
606      Expr::EvalResult Result;
607      HasConstantCond = CondExprBeforePromotion->Evaluate(Result, Context);
608      if (HasConstantCond) {
609        assert(Result.Val.isInt() && "switch condition evaluated to non-int");
610        ConstantCondValue = Result.Val.getInt();
611        ShouldCheckConstantCond = true;
612
613        assert(ConstantCondValue.getBitWidth() == CondWidth &&
614               ConstantCondValue.isSigned() == CondIsSigned);
615      }
616    }
617
618    // Sort all the scalar case values so we can easily detect duplicates.
619    std::stable_sort(CaseVals.begin(), CaseVals.end(), CmpCaseVals);
620
621    if (!CaseVals.empty()) {
622      for (unsigned i = 0, e = CaseVals.size(); i != e; ++i) {
623        if (ShouldCheckConstantCond &&
624            CaseVals[i].first == ConstantCondValue)
625          ShouldCheckConstantCond = false;
626
627        if (i != 0 && CaseVals[i].first == CaseVals[i-1].first) {
628          // If we have a duplicate, report it.
629          Diag(CaseVals[i].second->getLHS()->getLocStart(),
630               diag::err_duplicate_case) << CaseVals[i].first.toString(10);
631          Diag(CaseVals[i-1].second->getLHS()->getLocStart(),
632               diag::note_duplicate_case_prev);
633          // FIXME: We really want to remove the bogus case stmt from the
634          // substmt, but we have no way to do this right now.
635          CaseListIsErroneous = true;
636        }
637      }
638    }
639
640    // Detect duplicate case ranges, which usually don't exist at all in
641    // the first place.
642    if (!CaseRanges.empty()) {
643      // Sort all the case ranges by their low value so we can easily detect
644      // overlaps between ranges.
645      std::stable_sort(CaseRanges.begin(), CaseRanges.end());
646
647      // Scan the ranges, computing the high values and removing empty ranges.
648      std::vector<llvm::APSInt> HiVals;
649      for (unsigned i = 0, e = CaseRanges.size(); i != e; ++i) {
650        llvm::APSInt &LoVal = CaseRanges[i].first;
651        CaseStmt *CR = CaseRanges[i].second;
652        Expr *Hi = CR->getRHS();
653        llvm::APSInt HiVal = Hi->EvaluateAsInt(Context);
654
655        // Convert the value to the same width/sign as the condition.
656        ConvertIntegerToTypeWarnOnOverflow(HiVal, CondWidth, CondIsSigned,
657                                           Hi->getLocStart(),
658                                           diag::warn_case_value_overflow);
659
660        // If the LHS is not the same type as the condition, insert an implicit
661        // cast.
662        ImpCastExprToType(Hi, CondType, CK_IntegralCast);
663        CR->setRHS(Hi);
664
665        // If the low value is bigger than the high value, the case is empty.
666        if (LoVal > HiVal) {
667          Diag(CR->getLHS()->getLocStart(), diag::warn_case_empty_range)
668            << SourceRange(CR->getLHS()->getLocStart(),
669                           Hi->getLocEnd());
670          CaseRanges.erase(CaseRanges.begin()+i);
671          --i, --e;
672          continue;
673        }
674
675        if (ShouldCheckConstantCond &&
676            LoVal <= ConstantCondValue &&
677            ConstantCondValue <= HiVal)
678          ShouldCheckConstantCond = false;
679
680        HiVals.push_back(HiVal);
681      }
682
683      // Rescan the ranges, looking for overlap with singleton values and other
684      // ranges.  Since the range list is sorted, we only need to compare case
685      // ranges with their neighbors.
686      for (unsigned i = 0, e = CaseRanges.size(); i != e; ++i) {
687        llvm::APSInt &CRLo = CaseRanges[i].first;
688        llvm::APSInt &CRHi = HiVals[i];
689        CaseStmt *CR = CaseRanges[i].second;
690
691        // Check to see whether the case range overlaps with any
692        // singleton cases.
693        CaseStmt *OverlapStmt = 0;
694        llvm::APSInt OverlapVal(32);
695
696        // Find the smallest value >= the lower bound.  If I is in the
697        // case range, then we have overlap.
698        CaseValsTy::iterator I = std::lower_bound(CaseVals.begin(),
699                                                  CaseVals.end(), CRLo,
700                                                  CaseCompareFunctor());
701        if (I != CaseVals.end() && I->first < CRHi) {
702          OverlapVal  = I->first;   // Found overlap with scalar.
703          OverlapStmt = I->second;
704        }
705
706        // Find the smallest value bigger than the upper bound.
707        I = std::upper_bound(I, CaseVals.end(), CRHi, CaseCompareFunctor());
708        if (I != CaseVals.begin() && (I-1)->first >= CRLo) {
709          OverlapVal  = (I-1)->first;      // Found overlap with scalar.
710          OverlapStmt = (I-1)->second;
711        }
712
713        // Check to see if this case stmt overlaps with the subsequent
714        // case range.
715        if (i && CRLo <= HiVals[i-1]) {
716          OverlapVal  = HiVals[i-1];       // Found overlap with range.
717          OverlapStmt = CaseRanges[i-1].second;
718        }
719
720        if (OverlapStmt) {
721          // If we have a duplicate, report it.
722          Diag(CR->getLHS()->getLocStart(), diag::err_duplicate_case)
723            << OverlapVal.toString(10);
724          Diag(OverlapStmt->getLHS()->getLocStart(),
725               diag::note_duplicate_case_prev);
726          // FIXME: We really want to remove the bogus case stmt from the
727          // substmt, but we have no way to do this right now.
728          CaseListIsErroneous = true;
729        }
730      }
731    }
732
733    // Complain if we have a constant condition and we didn't find a match.
734    if (!CaseListIsErroneous && ShouldCheckConstantCond) {
735      // TODO: it would be nice if we printed enums as enums, chars as
736      // chars, etc.
737      Diag(CondExpr->getExprLoc(), diag::warn_missing_case_for_condition)
738        << ConstantCondValue.toString(10)
739        << CondExpr->getSourceRange();
740    }
741
742    // Check to see if switch is over an Enum and handles all of its
743    // values.  We only issue a warning if there is not 'default:', but
744    // we still do the analysis to preserve this information in the AST
745    // (which can be used by flow-based analyes).
746    //
747    const EnumType *ET = CondTypeBeforePromotion->getAs<EnumType>();
748
749    // If switch has default case, then ignore it.
750    if (!CaseListIsErroneous  && !HasConstantCond && ET) {
751      const EnumDecl *ED = ET->getDecl();
752      typedef llvm::SmallVector<std::pair<llvm::APSInt, EnumConstantDecl*>, 64> EnumValsTy;
753      EnumValsTy EnumVals;
754
755      // Gather all enum values, set their type and sort them,
756      // allowing easier comparison with CaseVals.
757      for (EnumDecl::enumerator_iterator EDI = ED->enumerator_begin();
758           EDI != ED->enumerator_end(); ++EDI) {
759        llvm::APSInt Val = EDI->getInitVal();
760        AdjustAPSInt(Val, CondWidth, CondIsSigned);
761        EnumVals.push_back(std::make_pair(Val, *EDI));
762      }
763      std::stable_sort(EnumVals.begin(), EnumVals.end(), CmpEnumVals);
764      EnumValsTy::iterator EIend =
765        std::unique(EnumVals.begin(), EnumVals.end(), EqEnumVals);
766
767      // See which case values aren't in enum.
768      // TODO: we might want to check whether case values are out of the
769      // enum even if we don't want to check whether all cases are handled.
770      if (!TheDefaultStmt) {
771        EnumValsTy::const_iterator EI = EnumVals.begin();
772        for (CaseValsTy::const_iterator CI = CaseVals.begin();
773             CI != CaseVals.end(); CI++) {
774          while (EI != EIend && EI->first < CI->first)
775            EI++;
776          if (EI == EIend || EI->first > CI->first)
777            Diag(CI->second->getLHS()->getExprLoc(), diag::warn_not_in_enum)
778              << ED->getDeclName();
779        }
780        // See which of case ranges aren't in enum
781        EI = EnumVals.begin();
782        for (CaseRangesTy::const_iterator RI = CaseRanges.begin();
783             RI != CaseRanges.end() && EI != EIend; RI++) {
784          while (EI != EIend && EI->first < RI->first)
785            EI++;
786
787          if (EI == EIend || EI->first != RI->first) {
788            Diag(RI->second->getLHS()->getExprLoc(), diag::warn_not_in_enum)
789              << ED->getDeclName();
790          }
791
792          llvm::APSInt Hi = RI->second->getRHS()->EvaluateAsInt(Context);
793          AdjustAPSInt(Hi, CondWidth, CondIsSigned);
794          while (EI != EIend && EI->first < Hi)
795            EI++;
796          if (EI == EIend || EI->first != Hi)
797            Diag(RI->second->getRHS()->getExprLoc(), diag::warn_not_in_enum)
798              << ED->getDeclName();
799        }
800      }
801
802      // Check which enum vals aren't in switch
803      CaseValsTy::const_iterator CI = CaseVals.begin();
804      CaseRangesTy::const_iterator RI = CaseRanges.begin();
805      bool hasCasesNotInSwitch = false;
806
807      llvm::SmallVector<DeclarationName,8> UnhandledNames;
808
809      for (EnumValsTy::const_iterator EI = EnumVals.begin(); EI != EIend; EI++){
810        // Drop unneeded case values
811        llvm::APSInt CIVal;
812        while (CI != CaseVals.end() && CI->first < EI->first)
813          CI++;
814
815        if (CI != CaseVals.end() && CI->first == EI->first)
816          continue;
817
818        // Drop unneeded case ranges
819        for (; RI != CaseRanges.end(); RI++) {
820          llvm::APSInt Hi = RI->second->getRHS()->EvaluateAsInt(Context);
821          AdjustAPSInt(Hi, CondWidth, CondIsSigned);
822          if (EI->first <= Hi)
823            break;
824        }
825
826        if (RI == CaseRanges.end() || EI->first < RI->first) {
827          hasCasesNotInSwitch = true;
828          if (!TheDefaultStmt)
829            UnhandledNames.push_back(EI->second->getDeclName());
830        }
831      }
832
833      // Produce a nice diagnostic if multiple values aren't handled.
834      switch (UnhandledNames.size()) {
835      case 0: break;
836      case 1:
837        Diag(CondExpr->getExprLoc(), diag::warn_missing_case1)
838          << UnhandledNames[0];
839        break;
840      case 2:
841        Diag(CondExpr->getExprLoc(), diag::warn_missing_case2)
842          << UnhandledNames[0] << UnhandledNames[1];
843        break;
844      case 3:
845        Diag(CondExpr->getExprLoc(), diag::warn_missing_case3)
846          << UnhandledNames[0] << UnhandledNames[1] << UnhandledNames[2];
847        break;
848      default:
849        Diag(CondExpr->getExprLoc(), diag::warn_missing_cases)
850          << (unsigned)UnhandledNames.size()
851          << UnhandledNames[0] << UnhandledNames[1] << UnhandledNames[2];
852        break;
853      }
854
855      if (!hasCasesNotInSwitch)
856        SS->setAllEnumCasesCovered();
857    }
858  }
859
860  // FIXME: If the case list was broken is some way, we don't have a good system
861  // to patch it up.  Instead, just return the whole substmt as broken.
862  if (CaseListIsErroneous)
863    return StmtError();
864
865  return Owned(SS);
866}
867
868StmtResult
869Sema::ActOnWhileStmt(SourceLocation WhileLoc, FullExprArg Cond,
870                     Decl *CondVar, Stmt *Body) {
871  ExprResult CondResult(Cond.release());
872
873  VarDecl *ConditionVar = 0;
874  if (CondVar) {
875    ConditionVar = cast<VarDecl>(CondVar);
876    CondResult = CheckConditionVariable(ConditionVar, WhileLoc, true);
877    if (CondResult.isInvalid())
878      return StmtError();
879  }
880  Expr *ConditionExpr = CondResult.take();
881  if (!ConditionExpr)
882    return StmtError();
883
884  DiagnoseUnusedExprResult(Body);
885
886  return Owned(new (Context) WhileStmt(Context, ConditionVar, ConditionExpr,
887                                       Body, WhileLoc));
888}
889
890StmtResult
891Sema::ActOnDoStmt(SourceLocation DoLoc, Stmt *Body,
892                  SourceLocation WhileLoc, SourceLocation CondLParen,
893                  Expr *Cond, SourceLocation CondRParen) {
894  assert(Cond && "ActOnDoStmt(): missing expression");
895
896  if (CheckBooleanCondition(Cond, DoLoc))
897    return StmtError();
898
899  CheckImplicitConversions(Cond, DoLoc);
900  ExprResult CondResult = MaybeCreateCXXExprWithTemporaries(Cond);
901  if (CondResult.isInvalid())
902    return StmtError();
903  Cond = CondResult.take();
904
905  DiagnoseUnusedExprResult(Body);
906
907  return Owned(new (Context) DoStmt(Body, Cond, DoLoc, WhileLoc, CondRParen));
908}
909
910StmtResult
911Sema::ActOnForStmt(SourceLocation ForLoc, SourceLocation LParenLoc,
912                   Stmt *First, FullExprArg second, Decl *secondVar,
913                   FullExprArg third,
914                   SourceLocation RParenLoc, Stmt *Body) {
915  if (!getLangOptions().CPlusPlus) {
916    if (DeclStmt *DS = dyn_cast_or_null<DeclStmt>(First)) {
917      // C99 6.8.5p3: The declaration part of a 'for' statement shall only
918      // declare identifiers for objects having storage class 'auto' or
919      // 'register'.
920      for (DeclStmt::decl_iterator DI=DS->decl_begin(), DE=DS->decl_end();
921           DI!=DE; ++DI) {
922        VarDecl *VD = dyn_cast<VarDecl>(*DI);
923        if (VD && VD->isLocalVarDecl() && !VD->hasLocalStorage())
924          VD = 0;
925        if (VD == 0)
926          Diag((*DI)->getLocation(), diag::err_non_variable_decl_in_for);
927        // FIXME: mark decl erroneous!
928      }
929    }
930  }
931
932  ExprResult SecondResult(second.release());
933  VarDecl *ConditionVar = 0;
934  if (secondVar) {
935    ConditionVar = cast<VarDecl>(secondVar);
936    SecondResult = CheckConditionVariable(ConditionVar, ForLoc, true);
937    if (SecondResult.isInvalid())
938      return StmtError();
939  }
940
941  Expr *Third  = third.release().takeAs<Expr>();
942
943  DiagnoseUnusedExprResult(First);
944  DiagnoseUnusedExprResult(Third);
945  DiagnoseUnusedExprResult(Body);
946
947  return Owned(new (Context) ForStmt(Context, First,
948                                     SecondResult.take(), ConditionVar,
949                                     Third, Body, ForLoc, LParenLoc,
950                                     RParenLoc));
951}
952
953StmtResult
954Sema::ActOnObjCForCollectionStmt(SourceLocation ForLoc,
955                                 SourceLocation LParenLoc,
956                                 Stmt *First, Expr *Second,
957                                 SourceLocation RParenLoc, Stmt *Body) {
958  if (First) {
959    QualType FirstType;
960    if (DeclStmt *DS = dyn_cast<DeclStmt>(First)) {
961      if (!DS->isSingleDecl())
962        return StmtError(Diag((*DS->decl_begin())->getLocation(),
963                         diag::err_toomany_element_decls));
964
965      Decl *D = DS->getSingleDecl();
966      FirstType = cast<ValueDecl>(D)->getType();
967      // C99 6.8.5p3: The declaration part of a 'for' statement shall only
968      // declare identifiers for objects having storage class 'auto' or
969      // 'register'.
970      VarDecl *VD = cast<VarDecl>(D);
971      if (VD->isLocalVarDecl() && !VD->hasLocalStorage())
972        return StmtError(Diag(VD->getLocation(),
973                              diag::err_non_variable_decl_in_for));
974    } else {
975      Expr *FirstE = cast<Expr>(First);
976      if (!FirstE->isTypeDependent() &&
977          FirstE->isLvalue(Context) != Expr::LV_Valid)
978        return StmtError(Diag(First->getLocStart(),
979                   diag::err_selector_element_not_lvalue)
980          << First->getSourceRange());
981
982      FirstType = static_cast<Expr*>(First)->getType();
983    }
984    if (!FirstType->isDependentType() &&
985        !FirstType->isObjCObjectPointerType() &&
986        !FirstType->isBlockPointerType())
987        Diag(ForLoc, diag::err_selector_element_type)
988          << FirstType << First->getSourceRange();
989  }
990  if (Second && !Second->isTypeDependent()) {
991    DefaultFunctionArrayLvalueConversion(Second);
992    QualType SecondType = Second->getType();
993    if (!SecondType->isObjCObjectPointerType())
994      Diag(ForLoc, diag::err_collection_expr_type)
995        << SecondType << Second->getSourceRange();
996    else if (const ObjCObjectPointerType *OPT =
997             SecondType->getAsObjCInterfacePointerType()) {
998      llvm::SmallVector<IdentifierInfo *, 4> KeyIdents;
999      IdentifierInfo* selIdent =
1000        &Context.Idents.get("countByEnumeratingWithState");
1001      KeyIdents.push_back(selIdent);
1002      selIdent = &Context.Idents.get("objects");
1003      KeyIdents.push_back(selIdent);
1004      selIdent = &Context.Idents.get("count");
1005      KeyIdents.push_back(selIdent);
1006      Selector CSelector = Context.Selectors.getSelector(3, &KeyIdents[0]);
1007      if (ObjCInterfaceDecl *IDecl = OPT->getInterfaceDecl()) {
1008        if (!IDecl->isForwardDecl() &&
1009            !IDecl->lookupInstanceMethod(CSelector)) {
1010          // Must further look into private implementation methods.
1011          if (!LookupPrivateInstanceMethod(CSelector, IDecl))
1012            Diag(ForLoc, diag::warn_collection_expr_type)
1013              << SecondType << CSelector << Second->getSourceRange();
1014        }
1015      }
1016    }
1017  }
1018  return Owned(new (Context) ObjCForCollectionStmt(First, Second, Body,
1019                                                   ForLoc, RParenLoc));
1020}
1021
1022StmtResult
1023Sema::ActOnGotoStmt(SourceLocation GotoLoc, SourceLocation LabelLoc,
1024                    IdentifierInfo *LabelII) {
1025  // Look up the record for this label identifier.
1026  LabelStmt *&LabelDecl = getCurFunction()->LabelMap[LabelII];
1027
1028  getCurFunction()->setHasBranchIntoScope();
1029
1030  // If we haven't seen this label yet, create a forward reference.
1031  if (LabelDecl == 0)
1032    LabelDecl = new (Context) LabelStmt(LabelLoc, LabelII, 0);
1033
1034  LabelDecl->setUsed();
1035  return Owned(new (Context) GotoStmt(LabelDecl, GotoLoc, LabelLoc));
1036}
1037
1038StmtResult
1039Sema::ActOnIndirectGotoStmt(SourceLocation GotoLoc, SourceLocation StarLoc,
1040                            Expr *E) {
1041  // Convert operand to void*
1042  if (!E->isTypeDependent()) {
1043    QualType ETy = E->getType();
1044    QualType DestTy = Context.getPointerType(Context.VoidTy.withConst());
1045    AssignConvertType ConvTy =
1046      CheckSingleAssignmentConstraints(DestTy, E);
1047    if (DiagnoseAssignmentResult(ConvTy, StarLoc, DestTy, ETy, E, AA_Passing))
1048      return StmtError();
1049  }
1050
1051  getCurFunction()->setHasIndirectGoto();
1052
1053  return Owned(new (Context) IndirectGotoStmt(GotoLoc, StarLoc, E));
1054}
1055
1056StmtResult
1057Sema::ActOnContinueStmt(SourceLocation ContinueLoc, Scope *CurScope) {
1058  Scope *S = CurScope->getContinueParent();
1059  if (!S) {
1060    // C99 6.8.6.2p1: A break shall appear only in or as a loop body.
1061    return StmtError(Diag(ContinueLoc, diag::err_continue_not_in_loop));
1062  }
1063
1064  return Owned(new (Context) ContinueStmt(ContinueLoc));
1065}
1066
1067StmtResult
1068Sema::ActOnBreakStmt(SourceLocation BreakLoc, Scope *CurScope) {
1069  Scope *S = CurScope->getBreakParent();
1070  if (!S) {
1071    // C99 6.8.6.3p1: A break shall appear only in or as a switch/loop body.
1072    return StmtError(Diag(BreakLoc, diag::err_break_not_in_loop_or_switch));
1073  }
1074
1075  return Owned(new (Context) BreakStmt(BreakLoc));
1076}
1077
1078/// \brief Determine whether a return statement is a candidate for the named
1079/// return value optimization (C++0x 12.8p34, bullet 1).
1080///
1081/// \param Ctx The context in which the return expression and type occur.
1082///
1083/// \param RetType The return type of the function or block.
1084///
1085/// \param RetExpr The expression being returned from the function or block.
1086///
1087/// \returns The NRVO candidate variable, if the return statement may use the
1088/// NRVO, or NULL if there is no such candidate.
1089static const VarDecl *getNRVOCandidate(ASTContext &Ctx, QualType RetType,
1090                                       Expr *RetExpr) {
1091  QualType ExprType = RetExpr->getType();
1092  // - in a return statement in a function with ...
1093  // ... a class return type ...
1094  if (!RetType->isRecordType())
1095    return 0;
1096  // ... the same cv-unqualified type as the function return type ...
1097  if (!Ctx.hasSameUnqualifiedType(RetType, ExprType))
1098    return 0;
1099  // ... the expression is the name of a non-volatile automatic object ...
1100  // We ignore parentheses here.
1101  // FIXME: Is this compliant? (Everyone else does it)
1102  const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(RetExpr->IgnoreParens());
1103  if (!DR)
1104    return 0;
1105  const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl());
1106  if (!VD)
1107    return 0;
1108
1109  if (VD->getKind() == Decl::Var && VD->hasLocalStorage() &&
1110      !VD->getType()->isReferenceType() && !VD->hasAttr<BlocksAttr>() &&
1111      !VD->getType().isVolatileQualified())
1112    return VD;
1113
1114  return 0;
1115}
1116
1117/// ActOnBlockReturnStmt - Utility routine to figure out block's return type.
1118///
1119StmtResult
1120Sema::ActOnBlockReturnStmt(SourceLocation ReturnLoc, Expr *RetValExp) {
1121  // If this is the first return we've seen in the block, infer the type of
1122  // the block from it.
1123  BlockScopeInfo *CurBlock = getCurBlock();
1124  if (CurBlock->ReturnType.isNull()) {
1125    if (RetValExp) {
1126      // Don't call UsualUnaryConversions(), since we don't want to do
1127      // integer promotions here.
1128      DefaultFunctionArrayLvalueConversion(RetValExp);
1129      CurBlock->ReturnType = RetValExp->getType();
1130      if (BlockDeclRefExpr *CDRE = dyn_cast<BlockDeclRefExpr>(RetValExp)) {
1131        // We have to remove a 'const' added to copied-in variable which was
1132        // part of the implementation spec. and not the actual qualifier for
1133        // the variable.
1134        if (CDRE->isConstQualAdded())
1135           CurBlock->ReturnType.removeConst();
1136      }
1137    } else
1138      CurBlock->ReturnType = Context.VoidTy;
1139  }
1140  QualType FnRetType = CurBlock->ReturnType;
1141
1142  if (CurBlock->TheDecl->hasAttr<NoReturnAttr>()) {
1143    Diag(ReturnLoc, diag::err_noreturn_block_has_return_expr)
1144      << getCurFunctionOrMethodDecl()->getDeclName();
1145    return StmtError();
1146  }
1147
1148  // Otherwise, verify that this result type matches the previous one.  We are
1149  // pickier with blocks than for normal functions because we don't have GCC
1150  // compatibility to worry about here.
1151  ReturnStmt *Result = 0;
1152  if (CurBlock->ReturnType->isVoidType()) {
1153    if (RetValExp) {
1154      Diag(ReturnLoc, diag::err_return_block_has_expr);
1155      RetValExp = 0;
1156    }
1157    Result = new (Context) ReturnStmt(ReturnLoc, RetValExp, 0);
1158  } else if (!RetValExp) {
1159    return StmtError(Diag(ReturnLoc, diag::err_block_return_missing_expr));
1160  } else {
1161    const VarDecl *NRVOCandidate = 0;
1162
1163    if (!FnRetType->isDependentType() && !RetValExp->isTypeDependent()) {
1164      // we have a non-void block with an expression, continue checking
1165
1166      // C99 6.8.6.4p3(136): The return statement is not an assignment. The
1167      // overlap restriction of subclause 6.5.16.1 does not apply to the case of
1168      // function return.
1169
1170      // In C++ the return statement is handled via a copy initialization.
1171      // the C version of which boils down to CheckSingleAssignmentConstraints.
1172      NRVOCandidate = getNRVOCandidate(Context, FnRetType, RetValExp);
1173      ExprResult Res = PerformCopyInitialization(
1174                               InitializedEntity::InitializeResult(ReturnLoc,
1175                                                                   FnRetType,
1176                                                            NRVOCandidate != 0),
1177                               SourceLocation(),
1178                               Owned(RetValExp));
1179      if (Res.isInvalid()) {
1180        // FIXME: Cleanup temporaries here, anyway?
1181        return StmtError();
1182      }
1183
1184      if (RetValExp) {
1185        CheckImplicitConversions(RetValExp, ReturnLoc);
1186        RetValExp = MaybeCreateCXXExprWithTemporaries(RetValExp);
1187      }
1188
1189      RetValExp = Res.takeAs<Expr>();
1190      if (RetValExp)
1191        CheckReturnStackAddr(RetValExp, FnRetType, ReturnLoc);
1192    }
1193
1194    Result = new (Context) ReturnStmt(ReturnLoc, RetValExp, NRVOCandidate);
1195  }
1196
1197  // If we need to check for the named return value optimization, save the
1198  // return statement in our scope for later processing.
1199  if (getLangOptions().CPlusPlus && FnRetType->isRecordType() &&
1200      !CurContext->isDependentContext())
1201    FunctionScopes.back()->Returns.push_back(Result);
1202
1203  return Owned(Result);
1204}
1205
1206StmtResult
1207Sema::ActOnReturnStmt(SourceLocation ReturnLoc, Expr *RetValExp) {
1208  if (getCurBlock())
1209    return ActOnBlockReturnStmt(ReturnLoc, RetValExp);
1210
1211  QualType FnRetType;
1212  if (const FunctionDecl *FD = getCurFunctionDecl()) {
1213    FnRetType = FD->getResultType();
1214    if (FD->hasAttr<NoReturnAttr>() ||
1215        FD->getType()->getAs<FunctionType>()->getNoReturnAttr())
1216      Diag(ReturnLoc, diag::warn_noreturn_function_has_return_expr)
1217        << getCurFunctionOrMethodDecl()->getDeclName();
1218  } else if (ObjCMethodDecl *MD = getCurMethodDecl())
1219    FnRetType = MD->getResultType();
1220  else // If we don't have a function/method context, bail.
1221    return StmtError();
1222
1223  ReturnStmt *Result = 0;
1224  if (FnRetType->isVoidType()) {
1225    if (RetValExp && !RetValExp->isTypeDependent()) {
1226      // C99 6.8.6.4p1 (ext_ since GCC warns)
1227      unsigned D = diag::ext_return_has_expr;
1228      if (RetValExp->getType()->isVoidType())
1229        D = diag::ext_return_has_void_expr;
1230
1231      // return (some void expression); is legal in C++.
1232      if (D != diag::ext_return_has_void_expr ||
1233          !getLangOptions().CPlusPlus) {
1234        NamedDecl *CurDecl = getCurFunctionOrMethodDecl();
1235        Diag(ReturnLoc, D)
1236          << CurDecl->getDeclName() << isa<ObjCMethodDecl>(CurDecl)
1237          << RetValExp->getSourceRange();
1238      }
1239
1240      CheckImplicitConversions(RetValExp, ReturnLoc);
1241      RetValExp = MaybeCreateCXXExprWithTemporaries(RetValExp);
1242    }
1243
1244    Result = new (Context) ReturnStmt(ReturnLoc, RetValExp, 0);
1245  } else if (!RetValExp && !FnRetType->isDependentType()) {
1246    unsigned DiagID = diag::warn_return_missing_expr;  // C90 6.6.6.4p4
1247    // C99 6.8.6.4p1 (ext_ since GCC warns)
1248    if (getLangOptions().C99) DiagID = diag::ext_return_missing_expr;
1249
1250    if (FunctionDecl *FD = getCurFunctionDecl())
1251      Diag(ReturnLoc, DiagID) << FD->getIdentifier() << 0/*fn*/;
1252    else
1253      Diag(ReturnLoc, DiagID) << getCurMethodDecl()->getDeclName() << 1/*meth*/;
1254    Result = new (Context) ReturnStmt(ReturnLoc);
1255  } else {
1256    const VarDecl *NRVOCandidate = 0;
1257    if (!FnRetType->isDependentType() && !RetValExp->isTypeDependent()) {
1258      // we have a non-void function with an expression, continue checking
1259
1260      // C99 6.8.6.4p3(136): The return statement is not an assignment. The
1261      // overlap restriction of subclause 6.5.16.1 does not apply to the case of
1262      // function return.
1263
1264      // In C++ the return statement is handled via a copy initialization.
1265      // the C version of which boils down to CheckSingleAssignmentConstraints.
1266      NRVOCandidate = getNRVOCandidate(Context, FnRetType, RetValExp);
1267      ExprResult Res = PerformCopyInitialization(
1268                               InitializedEntity::InitializeResult(ReturnLoc,
1269                                                                   FnRetType,
1270                                                            NRVOCandidate != 0),
1271                               SourceLocation(),
1272                               Owned(RetValExp));
1273      if (Res.isInvalid()) {
1274        // FIXME: Cleanup temporaries here, anyway?
1275        return StmtError();
1276      }
1277
1278      RetValExp = Res.takeAs<Expr>();
1279      if (RetValExp)
1280        CheckReturnStackAddr(RetValExp, FnRetType, ReturnLoc);
1281    }
1282
1283    if (RetValExp) {
1284      CheckImplicitConversions(RetValExp, ReturnLoc);
1285      RetValExp = MaybeCreateCXXExprWithTemporaries(RetValExp);
1286    }
1287    Result = new (Context) ReturnStmt(ReturnLoc, RetValExp, NRVOCandidate);
1288  }
1289
1290  // If we need to check for the named return value optimization, save the
1291  // return statement in our scope for later processing.
1292  if (getLangOptions().CPlusPlus && FnRetType->isRecordType() &&
1293      !CurContext->isDependentContext())
1294    FunctionScopes.back()->Returns.push_back(Result);
1295
1296  return Owned(Result);
1297}
1298
1299/// CheckAsmLValue - GNU C has an extremely ugly extension whereby they silently
1300/// ignore "noop" casts in places where an lvalue is required by an inline asm.
1301/// We emulate this behavior when -fheinous-gnu-extensions is specified, but
1302/// provide a strong guidance to not use it.
1303///
1304/// This method checks to see if the argument is an acceptable l-value and
1305/// returns false if it is a case we can handle.
1306static bool CheckAsmLValue(const Expr *E, Sema &S) {
1307  // Type dependent expressions will be checked during instantiation.
1308  if (E->isTypeDependent())
1309    return false;
1310
1311  if (E->isLvalue(S.Context) == Expr::LV_Valid)
1312    return false;  // Cool, this is an lvalue.
1313
1314  // Okay, this is not an lvalue, but perhaps it is the result of a cast that we
1315  // are supposed to allow.
1316  const Expr *E2 = E->IgnoreParenNoopCasts(S.Context);
1317  if (E != E2 && E2->isLvalue(S.Context) == Expr::LV_Valid) {
1318    if (!S.getLangOptions().HeinousExtensions)
1319      S.Diag(E2->getLocStart(), diag::err_invalid_asm_cast_lvalue)
1320        << E->getSourceRange();
1321    else
1322      S.Diag(E2->getLocStart(), diag::warn_invalid_asm_cast_lvalue)
1323        << E->getSourceRange();
1324    // Accept, even if we emitted an error diagnostic.
1325    return false;
1326  }
1327
1328  // None of the above, just randomly invalid non-lvalue.
1329  return true;
1330}
1331
1332
1333StmtResult Sema::ActOnAsmStmt(SourceLocation AsmLoc,
1334                                          bool IsSimple,
1335                                          bool IsVolatile,
1336                                          unsigned NumOutputs,
1337                                          unsigned NumInputs,
1338                                          IdentifierInfo **Names,
1339                                          MultiExprArg constraints,
1340                                          MultiExprArg exprs,
1341                                          Expr *asmString,
1342                                          MultiExprArg clobbers,
1343                                          SourceLocation RParenLoc,
1344                                          bool MSAsm) {
1345  unsigned NumClobbers = clobbers.size();
1346  StringLiteral **Constraints =
1347    reinterpret_cast<StringLiteral**>(constraints.get());
1348  Expr **Exprs = exprs.get();
1349  StringLiteral *AsmString = cast<StringLiteral>(asmString);
1350  StringLiteral **Clobbers = reinterpret_cast<StringLiteral**>(clobbers.get());
1351
1352  llvm::SmallVector<TargetInfo::ConstraintInfo, 4> OutputConstraintInfos;
1353
1354  // The parser verifies that there is a string literal here.
1355  if (AsmString->isWide())
1356    return StmtError(Diag(AsmString->getLocStart(),diag::err_asm_wide_character)
1357      << AsmString->getSourceRange());
1358
1359  for (unsigned i = 0; i != NumOutputs; i++) {
1360    StringLiteral *Literal = Constraints[i];
1361    if (Literal->isWide())
1362      return StmtError(Diag(Literal->getLocStart(),diag::err_asm_wide_character)
1363        << Literal->getSourceRange());
1364
1365    llvm::StringRef OutputName;
1366    if (Names[i])
1367      OutputName = Names[i]->getName();
1368
1369    TargetInfo::ConstraintInfo Info(Literal->getString(), OutputName);
1370    if (!Context.Target.validateOutputConstraint(Info))
1371      return StmtError(Diag(Literal->getLocStart(),
1372                            diag::err_asm_invalid_output_constraint)
1373                       << Info.getConstraintStr());
1374
1375    // Check that the output exprs are valid lvalues.
1376    Expr *OutputExpr = Exprs[i];
1377    if (CheckAsmLValue(OutputExpr, *this)) {
1378      return StmtError(Diag(OutputExpr->getLocStart(),
1379                  diag::err_asm_invalid_lvalue_in_output)
1380        << OutputExpr->getSourceRange());
1381    }
1382
1383    OutputConstraintInfos.push_back(Info);
1384  }
1385
1386  llvm::SmallVector<TargetInfo::ConstraintInfo, 4> InputConstraintInfos;
1387
1388  for (unsigned i = NumOutputs, e = NumOutputs + NumInputs; i != e; i++) {
1389    StringLiteral *Literal = Constraints[i];
1390    if (Literal->isWide())
1391      return StmtError(Diag(Literal->getLocStart(),diag::err_asm_wide_character)
1392        << Literal->getSourceRange());
1393
1394    llvm::StringRef InputName;
1395    if (Names[i])
1396      InputName = Names[i]->getName();
1397
1398    TargetInfo::ConstraintInfo Info(Literal->getString(), InputName);
1399    if (!Context.Target.validateInputConstraint(OutputConstraintInfos.data(),
1400                                                NumOutputs, Info)) {
1401      return StmtError(Diag(Literal->getLocStart(),
1402                            diag::err_asm_invalid_input_constraint)
1403                       << Info.getConstraintStr());
1404    }
1405
1406    Expr *InputExpr = Exprs[i];
1407
1408    // Only allow void types for memory constraints.
1409    if (Info.allowsMemory() && !Info.allowsRegister()) {
1410      if (CheckAsmLValue(InputExpr, *this))
1411        return StmtError(Diag(InputExpr->getLocStart(),
1412                              diag::err_asm_invalid_lvalue_in_input)
1413                         << Info.getConstraintStr()
1414                         << InputExpr->getSourceRange());
1415    }
1416
1417    if (Info.allowsRegister()) {
1418      if (InputExpr->getType()->isVoidType()) {
1419        return StmtError(Diag(InputExpr->getLocStart(),
1420                              diag::err_asm_invalid_type_in_input)
1421          << InputExpr->getType() << Info.getConstraintStr()
1422          << InputExpr->getSourceRange());
1423      }
1424    }
1425
1426    DefaultFunctionArrayLvalueConversion(Exprs[i]);
1427
1428    InputConstraintInfos.push_back(Info);
1429  }
1430
1431  // Check that the clobbers are valid.
1432  for (unsigned i = 0; i != NumClobbers; i++) {
1433    StringLiteral *Literal = Clobbers[i];
1434    if (Literal->isWide())
1435      return StmtError(Diag(Literal->getLocStart(),diag::err_asm_wide_character)
1436        << Literal->getSourceRange());
1437
1438    llvm::StringRef Clobber = Literal->getString();
1439
1440    if (!Context.Target.isValidGCCRegisterName(Clobber))
1441      return StmtError(Diag(Literal->getLocStart(),
1442                  diag::err_asm_unknown_register_name) << Clobber);
1443  }
1444
1445  AsmStmt *NS =
1446    new (Context) AsmStmt(Context, AsmLoc, IsSimple, IsVolatile, MSAsm,
1447                          NumOutputs, NumInputs, Names, Constraints, Exprs,
1448                          AsmString, NumClobbers, Clobbers, RParenLoc);
1449  // Validate the asm string, ensuring it makes sense given the operands we
1450  // have.
1451  llvm::SmallVector<AsmStmt::AsmStringPiece, 8> Pieces;
1452  unsigned DiagOffs;
1453  if (unsigned DiagID = NS->AnalyzeAsmString(Pieces, Context, DiagOffs)) {
1454    Diag(getLocationOfStringLiteralByte(AsmString, DiagOffs), DiagID)
1455           << AsmString->getSourceRange();
1456    return StmtError();
1457  }
1458
1459  // Validate tied input operands for type mismatches.
1460  for (unsigned i = 0, e = InputConstraintInfos.size(); i != e; ++i) {
1461    TargetInfo::ConstraintInfo &Info = InputConstraintInfos[i];
1462
1463    // If this is a tied constraint, verify that the output and input have
1464    // either exactly the same type, or that they are int/ptr operands with the
1465    // same size (int/long, int*/long, are ok etc).
1466    if (!Info.hasTiedOperand()) continue;
1467
1468    unsigned TiedTo = Info.getTiedOperand();
1469    Expr *OutputExpr = Exprs[TiedTo];
1470    Expr *InputExpr = Exprs[i+NumOutputs];
1471    QualType InTy = InputExpr->getType();
1472    QualType OutTy = OutputExpr->getType();
1473    if (Context.hasSameType(InTy, OutTy))
1474      continue;  // All types can be tied to themselves.
1475
1476    // Decide if the input and output are in the same domain (integer/ptr or
1477    // floating point.
1478    enum AsmDomain {
1479      AD_Int, AD_FP, AD_Other
1480    } InputDomain, OutputDomain;
1481
1482    if (InTy->isIntegerType() || InTy->isPointerType())
1483      InputDomain = AD_Int;
1484    else if (InTy->isRealFloatingType())
1485      InputDomain = AD_FP;
1486    else
1487      InputDomain = AD_Other;
1488
1489    if (OutTy->isIntegerType() || OutTy->isPointerType())
1490      OutputDomain = AD_Int;
1491    else if (OutTy->isRealFloatingType())
1492      OutputDomain = AD_FP;
1493    else
1494      OutputDomain = AD_Other;
1495
1496    // They are ok if they are the same size and in the same domain.  This
1497    // allows tying things like:
1498    //   void* to int*
1499    //   void* to int            if they are the same size.
1500    //   double to long double   if they are the same size.
1501    //
1502    uint64_t OutSize = Context.getTypeSize(OutTy);
1503    uint64_t InSize = Context.getTypeSize(InTy);
1504    if (OutSize == InSize && InputDomain == OutputDomain &&
1505        InputDomain != AD_Other)
1506      continue;
1507
1508    // If the smaller input/output operand is not mentioned in the asm string,
1509    // then we can promote it and the asm string won't notice.  Check this
1510    // case now.
1511    bool SmallerValueMentioned = false;
1512    for (unsigned p = 0, e = Pieces.size(); p != e; ++p) {
1513      AsmStmt::AsmStringPiece &Piece = Pieces[p];
1514      if (!Piece.isOperand()) continue;
1515
1516      // If this is a reference to the input and if the input was the smaller
1517      // one, then we have to reject this asm.
1518      if (Piece.getOperandNo() == i+NumOutputs) {
1519        if (InSize < OutSize) {
1520          SmallerValueMentioned = true;
1521          break;
1522        }
1523      }
1524
1525      // If this is a reference to the input and if the input was the smaller
1526      // one, then we have to reject this asm.
1527      if (Piece.getOperandNo() == TiedTo) {
1528        if (InSize > OutSize) {
1529          SmallerValueMentioned = true;
1530          break;
1531        }
1532      }
1533    }
1534
1535    // If the smaller value wasn't mentioned in the asm string, and if the
1536    // output was a register, just extend the shorter one to the size of the
1537    // larger one.
1538    if (!SmallerValueMentioned && InputDomain != AD_Other &&
1539        OutputConstraintInfos[TiedTo].allowsRegister())
1540      continue;
1541
1542    Diag(InputExpr->getLocStart(),
1543         diag::err_asm_tying_incompatible_types)
1544      << InTy << OutTy << OutputExpr->getSourceRange()
1545      << InputExpr->getSourceRange();
1546    return StmtError();
1547  }
1548
1549  return Owned(NS);
1550}
1551
1552StmtResult
1553Sema::ActOnObjCAtCatchStmt(SourceLocation AtLoc,
1554                           SourceLocation RParen, Decl *Parm,
1555                           Stmt *Body) {
1556  VarDecl *Var = cast_or_null<VarDecl>(Parm);
1557  if (Var && Var->isInvalidDecl())
1558    return StmtError();
1559
1560  return Owned(new (Context) ObjCAtCatchStmt(AtLoc, RParen, Var, Body));
1561}
1562
1563StmtResult
1564Sema::ActOnObjCAtFinallyStmt(SourceLocation AtLoc, Stmt *Body) {
1565  return Owned(new (Context) ObjCAtFinallyStmt(AtLoc, Body));
1566}
1567
1568StmtResult
1569Sema::ActOnObjCAtTryStmt(SourceLocation AtLoc, Stmt *Try,
1570                         MultiStmtArg CatchStmts, Stmt *Finally) {
1571  getCurFunction()->setHasBranchProtectedScope();
1572  unsigned NumCatchStmts = CatchStmts.size();
1573  return Owned(ObjCAtTryStmt::Create(Context, AtLoc, Try,
1574                                     CatchStmts.release(),
1575                                     NumCatchStmts,
1576                                     Finally));
1577}
1578
1579StmtResult Sema::BuildObjCAtThrowStmt(SourceLocation AtLoc,
1580                                                  Expr *Throw) {
1581  if (Throw) {
1582    QualType ThrowType = Throw->getType();
1583    // Make sure the expression type is an ObjC pointer or "void *".
1584    if (!ThrowType->isDependentType() &&
1585        !ThrowType->isObjCObjectPointerType()) {
1586      const PointerType *PT = ThrowType->getAs<PointerType>();
1587      if (!PT || !PT->getPointeeType()->isVoidType())
1588        return StmtError(Diag(AtLoc, diag::error_objc_throw_expects_object)
1589                         << Throw->getType() << Throw->getSourceRange());
1590    }
1591  }
1592
1593  return Owned(new (Context) ObjCAtThrowStmt(AtLoc, Throw));
1594}
1595
1596StmtResult
1597Sema::ActOnObjCAtThrowStmt(SourceLocation AtLoc, Expr *Throw,
1598                           Scope *CurScope) {
1599  if (!Throw) {
1600    // @throw without an expression designates a rethrow (which much occur
1601    // in the context of an @catch clause).
1602    Scope *AtCatchParent = CurScope;
1603    while (AtCatchParent && !AtCatchParent->isAtCatchScope())
1604      AtCatchParent = AtCatchParent->getParent();
1605    if (!AtCatchParent)
1606      return StmtError(Diag(AtLoc, diag::error_rethrow_used_outside_catch));
1607  }
1608
1609  return BuildObjCAtThrowStmt(AtLoc, Throw);
1610}
1611
1612StmtResult
1613Sema::ActOnObjCAtSynchronizedStmt(SourceLocation AtLoc, Expr *SyncExpr,
1614                                  Stmt *SyncBody) {
1615  getCurFunction()->setHasBranchProtectedScope();
1616
1617  // Make sure the expression type is an ObjC pointer or "void *".
1618  if (!SyncExpr->getType()->isDependentType() &&
1619      !SyncExpr->getType()->isObjCObjectPointerType()) {
1620    const PointerType *PT = SyncExpr->getType()->getAs<PointerType>();
1621    if (!PT || !PT->getPointeeType()->isVoidType())
1622      return StmtError(Diag(AtLoc, diag::error_objc_synchronized_expects_object)
1623                       << SyncExpr->getType() << SyncExpr->getSourceRange());
1624  }
1625
1626  return Owned(new (Context) ObjCAtSynchronizedStmt(AtLoc, SyncExpr, SyncBody));
1627}
1628
1629/// ActOnCXXCatchBlock - Takes an exception declaration and a handler block
1630/// and creates a proper catch handler from them.
1631StmtResult
1632Sema::ActOnCXXCatchBlock(SourceLocation CatchLoc, Decl *ExDecl,
1633                         Stmt *HandlerBlock) {
1634  // There's nothing to test that ActOnExceptionDecl didn't already test.
1635  return Owned(new (Context) CXXCatchStmt(CatchLoc,
1636                                          cast_or_null<VarDecl>(ExDecl),
1637                                          HandlerBlock));
1638}
1639
1640namespace {
1641
1642class TypeWithHandler {
1643  QualType t;
1644  CXXCatchStmt *stmt;
1645public:
1646  TypeWithHandler(const QualType &type, CXXCatchStmt *statement)
1647  : t(type), stmt(statement) {}
1648
1649  // An arbitrary order is fine as long as it places identical
1650  // types next to each other.
1651  bool operator<(const TypeWithHandler &y) const {
1652    if (t.getAsOpaquePtr() < y.t.getAsOpaquePtr())
1653      return true;
1654    if (t.getAsOpaquePtr() > y.t.getAsOpaquePtr())
1655      return false;
1656    else
1657      return getTypeSpecStartLoc() < y.getTypeSpecStartLoc();
1658  }
1659
1660  bool operator==(const TypeWithHandler& other) const {
1661    return t == other.t;
1662  }
1663
1664  CXXCatchStmt *getCatchStmt() const { return stmt; }
1665  SourceLocation getTypeSpecStartLoc() const {
1666    return stmt->getExceptionDecl()->getTypeSpecStartLoc();
1667  }
1668};
1669
1670}
1671
1672/// ActOnCXXTryBlock - Takes a try compound-statement and a number of
1673/// handlers and creates a try statement from them.
1674StmtResult
1675Sema::ActOnCXXTryBlock(SourceLocation TryLoc, Stmt *TryBlock,
1676                       MultiStmtArg RawHandlers) {
1677  unsigned NumHandlers = RawHandlers.size();
1678  assert(NumHandlers > 0 &&
1679         "The parser shouldn't call this if there are no handlers.");
1680  Stmt **Handlers = RawHandlers.get();
1681
1682  llvm::SmallVector<TypeWithHandler, 8> TypesWithHandlers;
1683
1684  for (unsigned i = 0; i < NumHandlers; ++i) {
1685    CXXCatchStmt *Handler = llvm::cast<CXXCatchStmt>(Handlers[i]);
1686    if (!Handler->getExceptionDecl()) {
1687      if (i < NumHandlers - 1)
1688        return StmtError(Diag(Handler->getLocStart(),
1689                              diag::err_early_catch_all));
1690
1691      continue;
1692    }
1693
1694    const QualType CaughtType = Handler->getCaughtType();
1695    const QualType CanonicalCaughtType = Context.getCanonicalType(CaughtType);
1696    TypesWithHandlers.push_back(TypeWithHandler(CanonicalCaughtType, Handler));
1697  }
1698
1699  // Detect handlers for the same type as an earlier one.
1700  if (NumHandlers > 1) {
1701    llvm::array_pod_sort(TypesWithHandlers.begin(), TypesWithHandlers.end());
1702
1703    TypeWithHandler prev = TypesWithHandlers[0];
1704    for (unsigned i = 1; i < TypesWithHandlers.size(); ++i) {
1705      TypeWithHandler curr = TypesWithHandlers[i];
1706
1707      if (curr == prev) {
1708        Diag(curr.getTypeSpecStartLoc(),
1709             diag::warn_exception_caught_by_earlier_handler)
1710          << curr.getCatchStmt()->getCaughtType().getAsString();
1711        Diag(prev.getTypeSpecStartLoc(),
1712             diag::note_previous_exception_handler)
1713          << prev.getCatchStmt()->getCaughtType().getAsString();
1714      }
1715
1716      prev = curr;
1717    }
1718  }
1719
1720  getCurFunction()->setHasBranchProtectedScope();
1721
1722  // FIXME: We should detect handlers that cannot catch anything because an
1723  // earlier handler catches a superclass. Need to find a method that is not
1724  // quadratic for this.
1725  // Neither of these are explicitly forbidden, but every compiler detects them
1726  // and warns.
1727
1728  return Owned(CXXTryStmt::Create(Context, TryLoc, TryBlock,
1729                                  Handlers, NumHandlers));
1730}
1731