SemaStmt.cpp revision ff331c15729f7d4439d253c97f4d60f2a7ffd0c6 
1//===--- SemaStmt.cpp - Semantic Analysis for Statements ------------------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10//  This file implements semantic analysis for statements.
11//
12//===----------------------------------------------------------------------===//
13
14#include "Sema.h"
15#include "SemaInit.h"
16#include "clang/AST/APValue.h"
17#include "clang/AST/ASTContext.h"
18#include "clang/AST/DeclObjC.h"
19#include "clang/AST/ExprCXX.h"
20#include "clang/AST/ExprObjC.h"
21#include "clang/AST/StmtObjC.h"
22#include "clang/AST/StmtCXX.h"
23#include "clang/AST/TypeLoc.h"
24#include "clang/Lex/Preprocessor.h"
25#include "clang/Basic/TargetInfo.h"
26#include "llvm/ADT/STLExtras.h"
27#include "llvm/ADT/SmallVector.h"
28using namespace clang;
29
30Sema::OwningStmtResult Sema::ActOnExprStmt(FullExprArg expr) {
31  Expr *E = expr->takeAs<Expr>();
32  assert(E && "ActOnExprStmt(): missing expression");
33  if (E->getType()->isObjCObjectType()) {
34    if (LangOpts.ObjCNonFragileABI)
35      Diag(E->getLocEnd(), diag::err_indirection_requires_nonfragile_object)
36             << E->getType();
37    else
38      Diag(E->getLocEnd(), diag::err_direct_interface_unsupported)
39             << E->getType();
40    return StmtError();
41  }
42  // C99 6.8.3p2: The expression in an expression statement is evaluated as a
43  // void expression for its side effects.  Conversion to void allows any
44  // operand, even incomplete types.
45
46  // Same thing in for stmt first clause (when expr) and third clause.
47  return Owned(static_cast<Stmt*>(E));
48}
49
50
51Sema::OwningStmtResult Sema::ActOnNullStmt(SourceLocation SemiLoc) {
52  return Owned(new (Context) NullStmt(SemiLoc));
53}
54
55Sema::OwningStmtResult Sema::ActOnDeclStmt(DeclGroupPtrTy dg,
56                                           SourceLocation StartLoc,
57                                           SourceLocation EndLoc) {
58  DeclGroupRef DG = dg.getAsVal<DeclGroupRef>();
59
60  // If we have an invalid decl, just return an error.
61  if (DG.isNull()) return StmtError();
62
63  return Owned(new (Context) DeclStmt(DG, StartLoc, EndLoc));
64}
65
66void Sema::ActOnForEachDeclStmt(DeclGroupPtrTy dg) {
67  DeclGroupRef DG = dg.getAsVal<DeclGroupRef>();
68
69  // If we have an invalid decl, just return.
70  if (DG.isNull() || !DG.isSingleDecl()) return;
71  // suppress any potential 'unused variable' warning.
72  DG.getSingleDecl()->setUsed();
73}
74
75void Sema::DiagnoseUnusedExprResult(const Stmt *S) {
76  const Expr *E = dyn_cast_or_null<Expr>(S);
77  if (!E)
78    return;
79
80  SourceLocation Loc;
81  SourceRange R1, R2;
82  if (!E->isUnusedResultAWarning(Loc, R1, R2, Context))
83    return;
84
85  // Okay, we have an unused result.  Depending on what the base expression is,
86  // we might want to make a more specific diagnostic.  Check for one of these
87  // cases now.
88  unsigned DiagID = diag::warn_unused_expr;
89  E = E->IgnoreParens();
90  if (isa<ObjCImplicitSetterGetterRefExpr>(E))
91    DiagID = diag::warn_unused_property_expr;
92
93  if (const CXXExprWithTemporaries *Temps = dyn_cast<CXXExprWithTemporaries>(E))
94    E = Temps->getSubExpr();
95
96  if (const CallExpr *CE = dyn_cast<CallExpr>(E)) {
97    if (E->getType()->isVoidType())
98      return;
99
100    // If the callee has attribute pure, const, or warn_unused_result, warn with
101    // a more specific message to make it clear what is happening.
102    if (const Decl *FD = CE->getCalleeDecl()) {
103      if (FD->getAttr<WarnUnusedResultAttr>()) {
104        Diag(Loc, diag::warn_unused_call) << R1 << R2 << "warn_unused_result";
105        return;
106      }
107      if (FD->getAttr<PureAttr>()) {
108        Diag(Loc, diag::warn_unused_call) << R1 << R2 << "pure";
109        return;
110      }
111      if (FD->getAttr<ConstAttr>()) {
112        Diag(Loc, diag::warn_unused_call) << R1 << R2 << "const";
113        return;
114      }
115    }
116  }
117  else if (const ObjCMessageExpr *ME = dyn_cast<ObjCMessageExpr>(E)) {
118    const ObjCMethodDecl *MD = ME->getMethodDecl();
119    if (MD && MD->getAttr<WarnUnusedResultAttr>()) {
120      Diag(Loc, diag::warn_unused_call) << R1 << R2 << "warn_unused_result";
121      return;
122    }
123  } else if (const CXXFunctionalCastExpr *FC
124                                       = dyn_cast<CXXFunctionalCastExpr>(E)) {
125    if (isa<CXXConstructExpr>(FC->getSubExpr()) ||
126        isa<CXXTemporaryObjectExpr>(FC->getSubExpr()))
127      return;
128  }
129  // Diagnose "(void*) blah" as a typo for "(void) blah".
130  else if (const CStyleCastExpr *CE = dyn_cast<CStyleCastExpr>(E)) {
131    TypeSourceInfo *TI = CE->getTypeInfoAsWritten();
132    QualType T = TI->getType();
133
134    // We really do want to use the non-canonical type here.
135    if (T == Context.VoidPtrTy) {
136      PointerTypeLoc TL = cast<PointerTypeLoc>(TI->getTypeLoc());
137
138      Diag(Loc, diag::warn_unused_voidptr)
139        << FixItHint::CreateRemoval(TL.getStarLoc());
140      return;
141    }
142  }
143
144  DiagRuntimeBehavior(Loc, PDiag(DiagID) << R1 << R2);
145}
146
147Action::OwningStmtResult
148Sema::ActOnCompoundStmt(SourceLocation L, SourceLocation R,
149                        MultiStmtArg elts, bool isStmtExpr) {
150  unsigned NumElts = elts.size();
151  Stmt **Elts = reinterpret_cast<Stmt**>(elts.release());
152  // If we're in C89 mode, check that we don't have any decls after stmts.  If
153  // so, emit an extension diagnostic.
154  if (!getLangOptions().C99 && !getLangOptions().CPlusPlus) {
155    // Note that __extension__ can be around a decl.
156    unsigned i = 0;
157    // Skip over all declarations.
158    for (; i != NumElts && isa<DeclStmt>(Elts[i]); ++i)
159      /*empty*/;
160
161    // We found the end of the list or a statement.  Scan for another declstmt.
162    for (; i != NumElts && !isa<DeclStmt>(Elts[i]); ++i)
163      /*empty*/;
164
165    if (i != NumElts) {
166      Decl *D = *cast<DeclStmt>(Elts[i])->decl_begin();
167      Diag(D->getLocation(), diag::ext_mixed_decls_code);
168    }
169  }
170  // Warn about unused expressions in statements.
171  for (unsigned i = 0; i != NumElts; ++i) {
172    // Ignore statements that are last in a statement expression.
173    if (isStmtExpr && i == NumElts - 1)
174      continue;
175
176    DiagnoseUnusedExprResult(Elts[i]);
177  }
178
179  return Owned(new (Context) CompoundStmt(Context, Elts, NumElts, L, R));
180}
181
182Action::OwningStmtResult
183Sema::ActOnCaseStmt(SourceLocation CaseLoc, ExprArg lhsval,
184                    SourceLocation DotDotDotLoc, ExprArg rhsval,
185                    SourceLocation ColonLoc) {
186  assert((lhsval.get() != 0) && "missing expression in case statement");
187
188  // C99 6.8.4.2p3: The expression shall be an integer constant.
189  // However, GCC allows any evaluatable integer expression.
190  Expr *LHSVal = static_cast<Expr*>(lhsval.get());
191  if (!LHSVal->isTypeDependent() && !LHSVal->isValueDependent() &&
192      VerifyIntegerConstantExpression(LHSVal))
193    return StmtError();
194
195  // GCC extension: The expression shall be an integer constant.
196
197  Expr *RHSVal = static_cast<Expr*>(rhsval.get());
198  if (RHSVal && !RHSVal->isTypeDependent() && !RHSVal->isValueDependent() &&
199      VerifyIntegerConstantExpression(RHSVal)) {
200    RHSVal = 0;  // Recover by just forgetting about it.
201    rhsval = 0;
202  }
203
204  if (getSwitchStack().empty()) {
205    Diag(CaseLoc, diag::err_case_not_in_switch);
206    return StmtError();
207  }
208
209  // Only now release the smart pointers.
210  lhsval.release();
211  rhsval.release();
212  CaseStmt *CS = new (Context) CaseStmt(LHSVal, RHSVal, CaseLoc, DotDotDotLoc,
213                                        ColonLoc);
214  getSwitchStack().back()->addSwitchCase(CS);
215  return Owned(CS);
216}
217
218/// ActOnCaseStmtBody - This installs a statement as the body of a case.
219void Sema::ActOnCaseStmtBody(StmtTy *caseStmt, StmtArg subStmt) {
220  CaseStmt *CS = static_cast<CaseStmt*>(caseStmt);
221  Stmt *SubStmt = subStmt.takeAs<Stmt>();
222  CS->setSubStmt(SubStmt);
223}
224
225Action::OwningStmtResult
226Sema::ActOnDefaultStmt(SourceLocation DefaultLoc, SourceLocation ColonLoc,
227                       StmtArg subStmt, Scope *CurScope) {
228  Stmt *SubStmt = subStmt.takeAs<Stmt>();
229
230  if (getSwitchStack().empty()) {
231    Diag(DefaultLoc, diag::err_default_not_in_switch);
232    return Owned(SubStmt);
233  }
234
235  DefaultStmt *DS = new (Context) DefaultStmt(DefaultLoc, ColonLoc, SubStmt);
236  getSwitchStack().back()->addSwitchCase(DS);
237  return Owned(DS);
238}
239
240Action::OwningStmtResult
241Sema::ActOnLabelStmt(SourceLocation IdentLoc, IdentifierInfo *II,
242                     SourceLocation ColonLoc, StmtArg subStmt) {
243  Stmt *SubStmt = subStmt.takeAs<Stmt>();
244  // Look up the record for this label identifier.
245  LabelStmt *&LabelDecl = getLabelMap()[II];
246
247  // If not forward referenced or defined already, just create a new LabelStmt.
248  if (LabelDecl == 0)
249    return Owned(LabelDecl = new (Context) LabelStmt(IdentLoc, II, SubStmt));
250
251  assert(LabelDecl->getID() == II && "Label mismatch!");
252
253  // Otherwise, this label was either forward reference or multiply defined.  If
254  // multiply defined, reject it now.
255  if (LabelDecl->getSubStmt()) {
256    Diag(IdentLoc, diag::err_redefinition_of_label) << LabelDecl->getID();
257    Diag(LabelDecl->getIdentLoc(), diag::note_previous_definition);
258    return Owned(SubStmt);
259  }
260
261  // Otherwise, this label was forward declared, and we just found its real
262  // definition.  Fill in the forward definition and return it.
263  LabelDecl->setIdentLoc(IdentLoc);
264  LabelDecl->setSubStmt(SubStmt);
265  return Owned(LabelDecl);
266}
267
268Action::OwningStmtResult
269Sema::ActOnIfStmt(SourceLocation IfLoc, FullExprArg CondVal, DeclPtrTy CondVar,
270                  StmtArg ThenVal, SourceLocation ElseLoc,
271                  StmtArg ElseVal) {
272  OwningExprResult CondResult(CondVal.release());
273
274  VarDecl *ConditionVar = 0;
275  if (CondVar.get()) {
276    ConditionVar = CondVar.getAs<VarDecl>();
277    CondResult = CheckConditionVariable(ConditionVar, IfLoc, true);
278    if (CondResult.isInvalid())
279      return StmtError();
280  }
281  Expr *ConditionExpr = CondResult.takeAs<Expr>();
282  if (!ConditionExpr)
283    return StmtError();
284
285  Stmt *thenStmt = ThenVal.takeAs<Stmt>();
286  DiagnoseUnusedExprResult(thenStmt);
287
288  // Warn if the if block has a null body without an else value.
289  // this helps prevent bugs due to typos, such as
290  // if (condition);
291  //   do_stuff();
292  if (!ElseVal.get()) {
293    if (NullStmt* stmt = dyn_cast<NullStmt>(thenStmt))
294      Diag(stmt->getSemiLoc(), diag::warn_empty_if_body);
295  }
296
297  Stmt *elseStmt = ElseVal.takeAs<Stmt>();
298  DiagnoseUnusedExprResult(elseStmt);
299
300  CondResult.release();
301  return Owned(new (Context) IfStmt(Context, IfLoc, ConditionVar, ConditionExpr,
302                                    thenStmt, ElseLoc, elseStmt));
303}
304
305/// ConvertIntegerToTypeWarnOnOverflow - Convert the specified APInt to have
306/// the specified width and sign.  If an overflow occurs, detect it and emit
307/// the specified diagnostic.
308void Sema::ConvertIntegerToTypeWarnOnOverflow(llvm::APSInt &Val,
309                                              unsigned NewWidth, bool NewSign,
310                                              SourceLocation Loc,
311                                              unsigned DiagID) {
312  // Perform a conversion to the promoted condition type if needed.
313  if (NewWidth > Val.getBitWidth()) {
314    // If this is an extension, just do it.
315    Val.extend(NewWidth);
316    Val.setIsSigned(NewSign);
317
318    // If the input was signed and negative and the output is
319    // unsigned, don't bother to warn: this is implementation-defined
320    // behavior.
321    // FIXME: Introduce a second, default-ignored warning for this case?
322  } else if (NewWidth < Val.getBitWidth()) {
323    // If this is a truncation, check for overflow.
324    llvm::APSInt ConvVal(Val);
325    ConvVal.trunc(NewWidth);
326    ConvVal.setIsSigned(NewSign);
327    ConvVal.extend(Val.getBitWidth());
328    ConvVal.setIsSigned(Val.isSigned());
329    if (ConvVal != Val)
330      Diag(Loc, DiagID) << Val.toString(10) << ConvVal.toString(10);
331
332    // Regardless of whether a diagnostic was emitted, really do the
333    // truncation.
334    Val.trunc(NewWidth);
335    Val.setIsSigned(NewSign);
336  } else if (NewSign != Val.isSigned()) {
337    // Convert the sign to match the sign of the condition.  This can cause
338    // overflow as well: unsigned(INTMIN)
339    // We don't diagnose this overflow, because it is implementation-defined
340    // behavior.
341    // FIXME: Introduce a second, default-ignored warning for this case?
342    llvm::APSInt OldVal(Val);
343    Val.setIsSigned(NewSign);
344  }
345}
346
347namespace {
348  struct CaseCompareFunctor {
349    bool operator()(const std::pair<llvm::APSInt, CaseStmt*> &LHS,
350                    const llvm::APSInt &RHS) {
351      return LHS.first < RHS;
352    }
353    bool operator()(const std::pair<llvm::APSInt, CaseStmt*> &LHS,
354                    const std::pair<llvm::APSInt, CaseStmt*> &RHS) {
355      return LHS.first < RHS.first;
356    }
357    bool operator()(const llvm::APSInt &LHS,
358                    const std::pair<llvm::APSInt, CaseStmt*> &RHS) {
359      return LHS < RHS.first;
360    }
361  };
362}
363
364/// CmpCaseVals - Comparison predicate for sorting case values.
365///
366static bool CmpCaseVals(const std::pair<llvm::APSInt, CaseStmt*>& lhs,
367                        const std::pair<llvm::APSInt, CaseStmt*>& rhs) {
368  if (lhs.first < rhs.first)
369    return true;
370
371  if (lhs.first == rhs.first &&
372      lhs.second->getCaseLoc().getRawEncoding()
373       < rhs.second->getCaseLoc().getRawEncoding())
374    return true;
375  return false;
376}
377
378/// CmpEnumVals - Comparison predicate for sorting enumeration values.
379///
380static bool CmpEnumVals(const std::pair<llvm::APSInt, EnumConstantDecl*>& lhs,
381                        const std::pair<llvm::APSInt, EnumConstantDecl*>& rhs)
382{
383  return lhs.first < rhs.first;
384}
385
386/// EqEnumVals - Comparison preficate for uniqing enumeration values.
387///
388static bool EqEnumVals(const std::pair<llvm::APSInt, EnumConstantDecl*>& lhs,
389                       const std::pair<llvm::APSInt, EnumConstantDecl*>& rhs)
390{
391  return lhs.first == rhs.first;
392}
393
394/// GetTypeBeforeIntegralPromotion - Returns the pre-promotion type of
395/// potentially integral-promoted expression @p expr.
396static QualType GetTypeBeforeIntegralPromotion(const Expr* expr) {
397  if (const CastExpr *ImplicitCast = dyn_cast<ImplicitCastExpr>(expr)) {
398    const Expr *ExprBeforePromotion = ImplicitCast->getSubExpr();
399    QualType TypeBeforePromotion = ExprBeforePromotion->getType();
400    if (TypeBeforePromotion->isIntegralOrEnumerationType()) {
401      return TypeBeforePromotion;
402    }
403  }
404  return expr->getType();
405}
406
407Action::OwningStmtResult
408Sema::ActOnStartOfSwitchStmt(SourceLocation SwitchLoc, ExprArg Cond,
409                             DeclPtrTy CondVar) {
410  VarDecl *ConditionVar = 0;
411  if (CondVar.get()) {
412    ConditionVar = CondVar.getAs<VarDecl>();
413    OwningExprResult CondE = CheckConditionVariable(ConditionVar, SourceLocation(), false);
414    if (CondE.isInvalid())
415      return StmtError();
416
417    Cond = move(CondE);
418  }
419
420  if (!Cond.get())
421    return StmtError();
422
423  Expr *CondExpr = static_cast<Expr *>(Cond.get());
424  OwningExprResult ConvertedCond
425    = ConvertToIntegralOrEnumerationType(SwitchLoc, move(Cond),
426                          PDiag(diag::err_typecheck_statement_requires_integer),
427                                   PDiag(diag::err_switch_incomplete_class_type)
428                                     << CondExpr->getSourceRange(),
429                                   PDiag(diag::err_switch_explicit_conversion),
430                                         PDiag(diag::note_switch_conversion),
431                                   PDiag(diag::err_switch_multiple_conversions),
432                                         PDiag(diag::note_switch_conversion),
433                                         PDiag(0));
434  if (ConvertedCond.isInvalid())
435    return StmtError();
436
437  CondExpr = ConvertedCond.takeAs<Expr>();
438
439  if (!CondVar.get()) {
440    CondExpr = MaybeCreateCXXExprWithTemporaries(CondExpr);
441    if (!CondExpr)
442      return StmtError();
443  }
444
445  SwitchStmt *SS = new (Context) SwitchStmt(Context, ConditionVar, CondExpr);
446  getSwitchStack().push_back(SS);
447  return Owned(SS);
448}
449
450Action::OwningStmtResult
451Sema::ActOnFinishSwitchStmt(SourceLocation SwitchLoc, StmtArg Switch,
452                            StmtArg Body) {
453  Stmt *BodyStmt = Body.takeAs<Stmt>();
454
455  SwitchStmt *SS = getSwitchStack().back();
456  assert(SS == (SwitchStmt*)Switch.get() && "switch stack missing push/pop!");
457
458  SS->setBody(BodyStmt, SwitchLoc);
459  getSwitchStack().pop_back();
460
461  if (SS->getCond() == 0)
462    return StmtError();
463
464  Expr *CondExpr = SS->getCond();
465  Expr *CondExprBeforePromotion = CondExpr;
466  QualType CondTypeBeforePromotion =
467      GetTypeBeforeIntegralPromotion(CondExpr);
468
469  // C99 6.8.4.2p5 - Integer promotions are performed on the controlling expr.
470  UsualUnaryConversions(CondExpr);
471  QualType CondType = CondExpr->getType();
472  SS->setCond(CondExpr);
473
474  // C++ 6.4.2.p2:
475  // Integral promotions are performed (on the switch condition).
476  //
477  // A case value unrepresentable by the original switch condition
478  // type (before the promotion) doesn't make sense, even when it can
479  // be represented by the promoted type.  Therefore we need to find
480  // the pre-promotion type of the switch condition.
481  if (!CondExpr->isTypeDependent()) {
482    // We have already converted the expression to an integral or enumeration
483    // type, when we started the switch statement. If we don't have an
484    // appropriate type now, just return an error.
485    if (!CondType->isIntegralOrEnumerationType())
486      return StmtError();
487
488    if (CondExpr->isKnownToHaveBooleanValue()) {
489      // switch(bool_expr) {...} is often a programmer error, e.g.
490      //   switch(n && mask) { ... }  // Doh - should be "n & mask".
491      // One can always use an if statement instead of switch(bool_expr).
492      Diag(SwitchLoc, diag::warn_bool_switch_condition)
493          << CondExpr->getSourceRange();
494    }
495  }
496
497  // Get the bitwidth of the switched-on value before promotions.  We must
498  // convert the integer case values to this width before comparison.
499  bool HasDependentValue
500    = CondExpr->isTypeDependent() || CondExpr->isValueDependent();
501  unsigned CondWidth
502    = HasDependentValue? 0
503      : static_cast<unsigned>(Context.getTypeSize(CondTypeBeforePromotion));
504  bool CondIsSigned = CondTypeBeforePromotion->isSignedIntegerType();
505
506  // Accumulate all of the case values in a vector so that we can sort them
507  // and detect duplicates.  This vector contains the APInt for the case after
508  // it has been converted to the condition type.
509  typedef llvm::SmallVector<std::pair<llvm::APSInt, CaseStmt*>, 64> CaseValsTy;
510  CaseValsTy CaseVals;
511
512  // Keep track of any GNU case ranges we see.  The APSInt is the low value.
513  typedef std::vector<std::pair<llvm::APSInt, CaseStmt*> > CaseRangesTy;
514  CaseRangesTy CaseRanges;
515
516  DefaultStmt *TheDefaultStmt = 0;
517
518  bool CaseListIsErroneous = false;
519
520  for (SwitchCase *SC = SS->getSwitchCaseList(); SC && !HasDependentValue;
521       SC = SC->getNextSwitchCase()) {
522
523    if (DefaultStmt *DS = dyn_cast<DefaultStmt>(SC)) {
524      if (TheDefaultStmt) {
525        Diag(DS->getDefaultLoc(), diag::err_multiple_default_labels_defined);
526        Diag(TheDefaultStmt->getDefaultLoc(), diag::note_duplicate_case_prev);
527
528        // FIXME: Remove the default statement from the switch block so that
529        // we'll return a valid AST.  This requires recursing down the AST and
530        // finding it, not something we are set up to do right now.  For now,
531        // just lop the entire switch stmt out of the AST.
532        CaseListIsErroneous = true;
533      }
534      TheDefaultStmt = DS;
535
536    } else {
537      CaseStmt *CS = cast<CaseStmt>(SC);
538
539      // We already verified that the expression has a i-c-e value (C99
540      // 6.8.4.2p3) - get that value now.
541      Expr *Lo = CS->getLHS();
542
543      if (Lo->isTypeDependent() || Lo->isValueDependent()) {
544        HasDependentValue = true;
545        break;
546      }
547
548      llvm::APSInt LoVal = Lo->EvaluateAsInt(Context);
549
550      // Convert the value to the same width/sign as the condition.
551      ConvertIntegerToTypeWarnOnOverflow(LoVal, CondWidth, CondIsSigned,
552                                         CS->getLHS()->getLocStart(),
553                                         diag::warn_case_value_overflow);
554
555      // If the LHS is not the same type as the condition, insert an implicit
556      // cast.
557      ImpCastExprToType(Lo, CondType, CastExpr::CK_IntegralCast);
558      CS->setLHS(Lo);
559
560      // If this is a case range, remember it in CaseRanges, otherwise CaseVals.
561      if (CS->getRHS()) {
562        if (CS->getRHS()->isTypeDependent() ||
563            CS->getRHS()->isValueDependent()) {
564          HasDependentValue = true;
565          break;
566        }
567        CaseRanges.push_back(std::make_pair(LoVal, CS));
568      } else
569        CaseVals.push_back(std::make_pair(LoVal, CS));
570    }
571  }
572
573  if (!HasDependentValue) {
574    // If we don't have a default statement, check whether the
575    // condition is constant.
576    llvm::APSInt ConstantCondValue;
577    bool HasConstantCond = false;
578    bool ShouldCheckConstantCond = false;
579    if (!HasDependentValue && !TheDefaultStmt) {
580      Expr::EvalResult Result;
581      HasConstantCond = CondExprBeforePromotion->Evaluate(Result, Context);
582      if (HasConstantCond) {
583        assert(Result.Val.isInt() && "switch condition evaluated to non-int");
584        ConstantCondValue = Result.Val.getInt();
585        ShouldCheckConstantCond = true;
586
587        assert(ConstantCondValue.getBitWidth() == CondWidth &&
588               ConstantCondValue.isSigned() == CondIsSigned);
589      }
590    }
591
592    // Sort all the scalar case values so we can easily detect duplicates.
593    std::stable_sort(CaseVals.begin(), CaseVals.end(), CmpCaseVals);
594
595    if (!CaseVals.empty()) {
596      for (unsigned i = 0, e = CaseVals.size(); i != e; ++i) {
597        if (ShouldCheckConstantCond &&
598            CaseVals[i].first == ConstantCondValue)
599          ShouldCheckConstantCond = false;
600
601        if (i != 0 && CaseVals[i].first == CaseVals[i-1].first) {
602          // If we have a duplicate, report it.
603          Diag(CaseVals[i].second->getLHS()->getLocStart(),
604               diag::err_duplicate_case) << CaseVals[i].first.toString(10);
605          Diag(CaseVals[i-1].second->getLHS()->getLocStart(),
606               diag::note_duplicate_case_prev);
607          // FIXME: We really want to remove the bogus case stmt from the
608          // substmt, but we have no way to do this right now.
609          CaseListIsErroneous = true;
610        }
611      }
612    }
613
614    // Detect duplicate case ranges, which usually don't exist at all in
615    // the first place.
616    if (!CaseRanges.empty()) {
617      // Sort all the case ranges by their low value so we can easily detect
618      // overlaps between ranges.
619      std::stable_sort(CaseRanges.begin(), CaseRanges.end());
620
621      // Scan the ranges, computing the high values and removing empty ranges.
622      std::vector<llvm::APSInt> HiVals;
623      for (unsigned i = 0, e = CaseRanges.size(); i != e; ++i) {
624        llvm::APSInt &LoVal = CaseRanges[i].first;
625        CaseStmt *CR = CaseRanges[i].second;
626        Expr *Hi = CR->getRHS();
627        llvm::APSInt HiVal = Hi->EvaluateAsInt(Context);
628
629        // Convert the value to the same width/sign as the condition.
630        ConvertIntegerToTypeWarnOnOverflow(HiVal, CondWidth, CondIsSigned,
631                                           CR->getRHS()->getLocStart(),
632                                           diag::warn_case_value_overflow);
633
634        // If the LHS is not the same type as the condition, insert an implicit
635        // cast.
636        ImpCastExprToType(Hi, CondType, CastExpr::CK_IntegralCast);
637        CR->setRHS(Hi);
638
639        // If the low value is bigger than the high value, the case is empty.
640        if (LoVal > HiVal) {
641          Diag(CR->getLHS()->getLocStart(), diag::warn_case_empty_range)
642            << SourceRange(CR->getLHS()->getLocStart(),
643                           CR->getRHS()->getLocEnd());
644          CaseRanges.erase(CaseRanges.begin()+i);
645          --i, --e;
646          continue;
647        }
648
649        if (ShouldCheckConstantCond &&
650            LoVal <= ConstantCondValue &&
651            ConstantCondValue <= HiVal)
652          ShouldCheckConstantCond = false;
653
654        HiVals.push_back(HiVal);
655      }
656
657      // Rescan the ranges, looking for overlap with singleton values and other
658      // ranges.  Since the range list is sorted, we only need to compare case
659      // ranges with their neighbors.
660      for (unsigned i = 0, e = CaseRanges.size(); i != e; ++i) {
661        llvm::APSInt &CRLo = CaseRanges[i].first;
662        llvm::APSInt &CRHi = HiVals[i];
663        CaseStmt *CR = CaseRanges[i].second;
664
665        // Check to see whether the case range overlaps with any
666        // singleton cases.
667        CaseStmt *OverlapStmt = 0;
668        llvm::APSInt OverlapVal(32);
669
670        // Find the smallest value >= the lower bound.  If I is in the
671        // case range, then we have overlap.
672        CaseValsTy::iterator I = std::lower_bound(CaseVals.begin(),
673                                                  CaseVals.end(), CRLo,
674                                                  CaseCompareFunctor());
675        if (I != CaseVals.end() && I->first < CRHi) {
676          OverlapVal  = I->first;   // Found overlap with scalar.
677          OverlapStmt = I->second;
678        }
679
680        // Find the smallest value bigger than the upper bound.
681        I = std::upper_bound(I, CaseVals.end(), CRHi, CaseCompareFunctor());
682        if (I != CaseVals.begin() && (I-1)->first >= CRLo) {
683          OverlapVal  = (I-1)->first;      // Found overlap with scalar.
684          OverlapStmt = (I-1)->second;
685        }
686
687        // Check to see if this case stmt overlaps with the subsequent
688        // case range.
689        if (i && CRLo <= HiVals[i-1]) {
690          OverlapVal  = HiVals[i-1];       // Found overlap with range.
691          OverlapStmt = CaseRanges[i-1].second;
692        }
693
694        if (OverlapStmt) {
695          // If we have a duplicate, report it.
696          Diag(CR->getLHS()->getLocStart(), diag::err_duplicate_case)
697            << OverlapVal.toString(10);
698          Diag(OverlapStmt->getLHS()->getLocStart(),
699               diag::note_duplicate_case_prev);
700          // FIXME: We really want to remove the bogus case stmt from the
701          // substmt, but we have no way to do this right now.
702          CaseListIsErroneous = true;
703        }
704      }
705    }
706
707    // Complain if we have a constant condition and we didn't find a match.
708    if (!CaseListIsErroneous && ShouldCheckConstantCond) {
709      // TODO: it would be nice if we printed enums as enums, chars as
710      // chars, etc.
711      Diag(CondExpr->getExprLoc(), diag::warn_missing_case_for_condition)
712        << ConstantCondValue.toString(10)
713        << CondExpr->getSourceRange();
714    }
715
716    // Check to see if switch is over an Enum and handles all of its
717    // values.  We don't need to do this if there's a default
718    // statement or if we have a constant condition.
719    //
720    // TODO: we might want to check whether case values are out of the
721    // enum even if we don't want to check whether all cases are handled.
722    const EnumType* ET = CondTypeBeforePromotion->getAs<EnumType>();
723    // If switch has default case, then ignore it.
724    if (!CaseListIsErroneous && !TheDefaultStmt && !HasConstantCond && ET) {
725      const EnumDecl *ED = ET->getDecl();
726      typedef llvm::SmallVector<std::pair<llvm::APSInt, EnumConstantDecl*>, 64> EnumValsTy;
727      EnumValsTy EnumVals;
728
729      // Gather all enum values, set their type and sort them,
730      // allowing easier comparison with CaseVals.
731      for (EnumDecl::enumerator_iterator EDI = ED->enumerator_begin();
732             EDI != ED->enumerator_end(); EDI++) {
733        llvm::APSInt Val = (*EDI)->getInitVal();
734        if(Val.getBitWidth() < CondWidth)
735          Val.extend(CondWidth);
736        else if (Val.getBitWidth() > CondWidth)
737          Val.trunc(CondWidth);
738        Val.setIsSigned(CondIsSigned);
739        EnumVals.push_back(std::make_pair(Val, (*EDI)));
740      }
741      std::stable_sort(EnumVals.begin(), EnumVals.end(), CmpEnumVals);
742      EnumValsTy::iterator EIend =
743        std::unique(EnumVals.begin(), EnumVals.end(), EqEnumVals);
744      // See which case values aren't in enum
745      EnumValsTy::const_iterator EI = EnumVals.begin();
746      for (CaseValsTy::const_iterator CI = CaseVals.begin();
747             CI != CaseVals.end(); CI++) {
748        while (EI != EIend && EI->first < CI->first)
749          EI++;
750        if (EI == EIend || EI->first > CI->first)
751            Diag(CI->second->getLHS()->getExprLoc(), diag::warn_not_in_enum)
752              << ED->getDeclName();
753      }
754      // See which of case ranges aren't in enum
755      EI = EnumVals.begin();
756      for (CaseRangesTy::const_iterator RI = CaseRanges.begin();
757             RI != CaseRanges.end() && EI != EIend; RI++) {
758        while (EI != EIend && EI->first < RI->first)
759          EI++;
760
761        if (EI == EIend || EI->first != RI->first) {
762          Diag(RI->second->getLHS()->getExprLoc(), diag::warn_not_in_enum)
763            << ED->getDeclName();
764        }
765
766        llvm::APSInt Hi = RI->second->getRHS()->EvaluateAsInt(Context);
767        while (EI != EIend && EI->first < Hi)
768          EI++;
769        if (EI == EIend || EI->first != Hi)
770          Diag(RI->second->getRHS()->getExprLoc(), diag::warn_not_in_enum)
771            << ED->getDeclName();
772      }
773      //Check which enum vals aren't in switch
774      CaseValsTy::const_iterator CI = CaseVals.begin();
775      CaseRangesTy::const_iterator RI = CaseRanges.begin();
776      EI = EnumVals.begin();
777      for (; EI != EIend; EI++) {
778        //Drop unneeded case values
779        llvm::APSInt CIVal;
780        while (CI != CaseVals.end() && CI->first < EI->first)
781          CI++;
782
783        if (CI != CaseVals.end() && CI->first == EI->first)
784          continue;
785
786        //Drop unneeded case ranges
787        for (; RI != CaseRanges.end(); RI++) {
788          llvm::APSInt Hi = RI->second->getRHS()->EvaluateAsInt(Context);
789          if (EI->first <= Hi)
790            break;
791        }
792
793        if (RI == CaseRanges.end() || EI->first < RI->first)
794          Diag(CondExpr->getExprLoc(), diag::warn_missing_cases)
795            << EI->second->getDeclName();
796      }
797    }
798  }
799
800  // FIXME: If the case list was broken is some way, we don't have a good system
801  // to patch it up.  Instead, just return the whole substmt as broken.
802  if (CaseListIsErroneous)
803    return StmtError();
804
805  Switch.release();
806  return Owned(SS);
807}
808
809Action::OwningStmtResult
810Sema::ActOnWhileStmt(SourceLocation WhileLoc, FullExprArg Cond,
811                     DeclPtrTy CondVar, StmtArg Body) {
812  OwningExprResult CondResult(Cond.release());
813
814  VarDecl *ConditionVar = 0;
815  if (CondVar.get()) {
816    ConditionVar = CondVar.getAs<VarDecl>();
817    CondResult = CheckConditionVariable(ConditionVar, WhileLoc, true);
818    if (CondResult.isInvalid())
819      return StmtError();
820  }
821  Expr *ConditionExpr = CondResult.takeAs<Expr>();
822  if (!ConditionExpr)
823    return StmtError();
824
825  Stmt *bodyStmt = Body.takeAs<Stmt>();
826  DiagnoseUnusedExprResult(bodyStmt);
827
828  CondResult.release();
829  return Owned(new (Context) WhileStmt(Context, ConditionVar, ConditionExpr,
830                                       bodyStmt, WhileLoc));
831}
832
833Action::OwningStmtResult
834Sema::ActOnDoStmt(SourceLocation DoLoc, StmtArg Body,
835                  SourceLocation WhileLoc, SourceLocation CondLParen,
836                  ExprArg Cond, SourceLocation CondRParen) {
837  Expr *condExpr = Cond.takeAs<Expr>();
838  assert(condExpr && "ActOnDoStmt(): missing expression");
839
840  if (CheckBooleanCondition(condExpr, DoLoc)) {
841    Cond = condExpr;
842    return StmtError();
843  }
844
845  condExpr = MaybeCreateCXXExprWithTemporaries(condExpr);
846  if (!condExpr)
847    return StmtError();
848
849  Stmt *bodyStmt = Body.takeAs<Stmt>();
850  DiagnoseUnusedExprResult(bodyStmt);
851
852  Cond.release();
853  return Owned(new (Context) DoStmt(bodyStmt, condExpr, DoLoc,
854                                    WhileLoc, CondRParen));
855}
856
857Action::OwningStmtResult
858Sema::ActOnForStmt(SourceLocation ForLoc, SourceLocation LParenLoc,
859                   StmtArg first, FullExprArg second, DeclPtrTy secondVar,
860                   FullExprArg third,
861                   SourceLocation RParenLoc, StmtArg body) {
862  Stmt *First  = static_cast<Stmt*>(first.get());
863
864  if (!getLangOptions().CPlusPlus) {
865    if (DeclStmt *DS = dyn_cast_or_null<DeclStmt>(First)) {
866      // C99 6.8.5p3: The declaration part of a 'for' statement shall only
867      // declare identifiers for objects having storage class 'auto' or
868      // 'register'.
869      for (DeclStmt::decl_iterator DI=DS->decl_begin(), DE=DS->decl_end();
870           DI!=DE; ++DI) {
871        VarDecl *VD = dyn_cast<VarDecl>(*DI);
872        if (VD && VD->isBlockVarDecl() && !VD->hasLocalStorage())
873          VD = 0;
874        if (VD == 0)
875          Diag((*DI)->getLocation(), diag::err_non_variable_decl_in_for);
876        // FIXME: mark decl erroneous!
877      }
878    }
879  }
880
881  OwningExprResult SecondResult(second.release());
882  VarDecl *ConditionVar = 0;
883  if (secondVar.get()) {
884    ConditionVar = secondVar.getAs<VarDecl>();
885    SecondResult = CheckConditionVariable(ConditionVar, ForLoc, true);
886    if (SecondResult.isInvalid())
887      return StmtError();
888  }
889
890  Expr *Third  = third.release().takeAs<Expr>();
891  Stmt *Body  = static_cast<Stmt*>(body.get());
892
893  DiagnoseUnusedExprResult(First);
894  DiagnoseUnusedExprResult(Third);
895  DiagnoseUnusedExprResult(Body);
896
897  first.release();
898  body.release();
899  return Owned(new (Context) ForStmt(Context, First,
900                                     SecondResult.takeAs<Expr>(), ConditionVar,
901                                     Third, Body, ForLoc, LParenLoc,
902                                     RParenLoc));
903}
904
905Action::OwningStmtResult
906Sema::ActOnObjCForCollectionStmt(SourceLocation ForLoc,
907                                 SourceLocation LParenLoc,
908                                 StmtArg first, ExprArg second,
909                                 SourceLocation RParenLoc, StmtArg body) {
910  Stmt *First  = static_cast<Stmt*>(first.get());
911  Expr *Second = static_cast<Expr*>(second.get());
912  Stmt *Body  = static_cast<Stmt*>(body.get());
913  if (First) {
914    QualType FirstType;
915    if (DeclStmt *DS = dyn_cast<DeclStmt>(First)) {
916      if (!DS->isSingleDecl())
917        return StmtError(Diag((*DS->decl_begin())->getLocation(),
918                         diag::err_toomany_element_decls));
919
920      Decl *D = DS->getSingleDecl();
921      FirstType = cast<ValueDecl>(D)->getType();
922      // C99 6.8.5p3: The declaration part of a 'for' statement shall only
923      // declare identifiers for objects having storage class 'auto' or
924      // 'register'.
925      VarDecl *VD = cast<VarDecl>(D);
926      if (VD->isBlockVarDecl() && !VD->hasLocalStorage())
927        return StmtError(Diag(VD->getLocation(),
928                              diag::err_non_variable_decl_in_for));
929    } else {
930      Expr *FirstE = cast<Expr>(First);
931      if (!FirstE->isTypeDependent() &&
932          FirstE->isLvalue(Context) != Expr::LV_Valid)
933        return StmtError(Diag(First->getLocStart(),
934                   diag::err_selector_element_not_lvalue)
935          << First->getSourceRange());
936
937      FirstType = static_cast<Expr*>(First)->getType();
938    }
939    if (!FirstType->isDependentType() &&
940        !FirstType->isObjCObjectPointerType() &&
941        !FirstType->isBlockPointerType())
942        Diag(ForLoc, diag::err_selector_element_type)
943          << FirstType << First->getSourceRange();
944  }
945  if (Second && !Second->isTypeDependent()) {
946    DefaultFunctionArrayLvalueConversion(Second);
947    QualType SecondType = Second->getType();
948    if (!SecondType->isObjCObjectPointerType())
949      Diag(ForLoc, diag::err_collection_expr_type)
950        << SecondType << Second->getSourceRange();
951  }
952  first.release();
953  second.release();
954  body.release();
955  return Owned(new (Context) ObjCForCollectionStmt(First, Second, Body,
956                                                   ForLoc, RParenLoc));
957}
958
959Action::OwningStmtResult
960Sema::ActOnGotoStmt(SourceLocation GotoLoc, SourceLocation LabelLoc,
961                    IdentifierInfo *LabelII) {
962  // Look up the record for this label identifier.
963  LabelStmt *&LabelDecl = getLabelMap()[LabelII];
964
965  // If we haven't seen this label yet, create a forward reference.
966  if (LabelDecl == 0)
967    LabelDecl = new (Context) LabelStmt(LabelLoc, LabelII, 0);
968
969  return Owned(new (Context) GotoStmt(LabelDecl, GotoLoc, LabelLoc));
970}
971
972Action::OwningStmtResult
973Sema::ActOnIndirectGotoStmt(SourceLocation GotoLoc, SourceLocation StarLoc,
974                            ExprArg DestExp) {
975  // Convert operand to void*
976  Expr* E = DestExp.takeAs<Expr>();
977  if (!E->isTypeDependent()) {
978    QualType ETy = E->getType();
979    QualType DestTy = Context.getPointerType(Context.VoidTy.withConst());
980    AssignConvertType ConvTy =
981      CheckSingleAssignmentConstraints(DestTy, E);
982    if (DiagnoseAssignmentResult(ConvTy, StarLoc, DestTy, ETy, E, AA_Passing))
983      return StmtError();
984  }
985  return Owned(new (Context) IndirectGotoStmt(GotoLoc, StarLoc, E));
986}
987
988Action::OwningStmtResult
989Sema::ActOnContinueStmt(SourceLocation ContinueLoc, Scope *CurScope) {
990  Scope *S = CurScope->getContinueParent();
991  if (!S) {
992    // C99 6.8.6.2p1: A break shall appear only in or as a loop body.
993    return StmtError(Diag(ContinueLoc, diag::err_continue_not_in_loop));
994  }
995
996  return Owned(new (Context) ContinueStmt(ContinueLoc));
997}
998
999Action::OwningStmtResult
1000Sema::ActOnBreakStmt(SourceLocation BreakLoc, Scope *CurScope) {
1001  Scope *S = CurScope->getBreakParent();
1002  if (!S) {
1003    // C99 6.8.6.3p1: A break shall appear only in or as a switch/loop body.
1004    return StmtError(Diag(BreakLoc, diag::err_break_not_in_loop_or_switch));
1005  }
1006
1007  return Owned(new (Context) BreakStmt(BreakLoc));
1008}
1009
1010/// \brief Determine whether a return statement is a candidate for the named
1011/// return value optimization (C++0x 12.8p34, bullet 1).
1012///
1013/// \param Ctx The context in which the return expression and type occur.
1014///
1015/// \param RetType The return type of the function or block.
1016///
1017/// \param RetExpr The expression being returned from the function or block.
1018///
1019/// \returns The NRVO candidate variable, if the return statement may use the
1020/// NRVO, or NULL if there is no such candidate.
1021static const VarDecl *getNRVOCandidate(ASTContext &Ctx, QualType RetType,
1022                                       Expr *RetExpr) {
1023  QualType ExprType = RetExpr->getType();
1024  // - in a return statement in a function with ...
1025  // ... a class return type ...
1026  if (!RetType->isRecordType())
1027    return 0;
1028  // ... the same cv-unqualified type as the function return type ...
1029  if (!Ctx.hasSameUnqualifiedType(RetType, ExprType))
1030    return 0;
1031  // ... the expression is the name of a non-volatile automatic object ...
1032  // We ignore parentheses here.
1033  // FIXME: Is this compliant? (Everyone else does it)
1034  const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(RetExpr->IgnoreParens());
1035  if (!DR)
1036    return 0;
1037  const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl());
1038  if (!VD)
1039    return 0;
1040
1041  if (VD->getKind() == Decl::Var && VD->hasLocalStorage() &&
1042      !VD->getType()->isReferenceType() && !VD->hasAttr<BlocksAttr>() &&
1043      !VD->getType().isVolatileQualified())
1044    return VD;
1045
1046  return 0;
1047}
1048
1049/// ActOnBlockReturnStmt - Utility routine to figure out block's return type.
1050///
1051Action::OwningStmtResult
1052Sema::ActOnBlockReturnStmt(SourceLocation ReturnLoc, Expr *RetValExp) {
1053  // If this is the first return we've seen in the block, infer the type of
1054  // the block from it.
1055  BlockScopeInfo *CurBlock = getCurBlock();
1056  if (CurBlock->ReturnType.isNull()) {
1057    if (RetValExp) {
1058      // Don't call UsualUnaryConversions(), since we don't want to do
1059      // integer promotions here.
1060      DefaultFunctionArrayLvalueConversion(RetValExp);
1061      CurBlock->ReturnType = RetValExp->getType();
1062      if (BlockDeclRefExpr *CDRE = dyn_cast<BlockDeclRefExpr>(RetValExp)) {
1063        // We have to remove a 'const' added to copied-in variable which was
1064        // part of the implementation spec. and not the actual qualifier for
1065        // the variable.
1066        if (CDRE->isConstQualAdded())
1067           CurBlock->ReturnType.removeConst();
1068      }
1069    } else
1070      CurBlock->ReturnType = Context.VoidTy;
1071  }
1072  QualType FnRetType = CurBlock->ReturnType;
1073
1074  if (CurBlock->TheDecl->hasAttr<NoReturnAttr>()) {
1075    Diag(ReturnLoc, diag::err_noreturn_block_has_return_expr)
1076      << getCurFunctionOrMethodDecl()->getDeclName();
1077    return StmtError();
1078  }
1079
1080  // Otherwise, verify that this result type matches the previous one.  We are
1081  // pickier with blocks than for normal functions because we don't have GCC
1082  // compatibility to worry about here.
1083  ReturnStmt *Result = 0;
1084  if (CurBlock->ReturnType->isVoidType()) {
1085    if (RetValExp) {
1086      Diag(ReturnLoc, diag::err_return_block_has_expr);
1087      RetValExp = 0;
1088    }
1089    Result = new (Context) ReturnStmt(ReturnLoc, RetValExp, 0);
1090  } else if (!RetValExp) {
1091    return StmtError(Diag(ReturnLoc, diag::err_block_return_missing_expr));
1092  } else {
1093    const VarDecl *NRVOCandidate = 0;
1094
1095    if (!FnRetType->isDependentType() && !RetValExp->isTypeDependent()) {
1096      // we have a non-void block with an expression, continue checking
1097
1098      // C99 6.8.6.4p3(136): The return statement is not an assignment. The
1099      // overlap restriction of subclause 6.5.16.1 does not apply to the case of
1100      // function return.
1101
1102      // In C++ the return statement is handled via a copy initialization.
1103      // the C version of which boils down to CheckSingleAssignmentConstraints.
1104      NRVOCandidate = getNRVOCandidate(Context, FnRetType, RetValExp);
1105      OwningExprResult Res = PerformCopyInitialization(
1106                               InitializedEntity::InitializeResult(ReturnLoc,
1107                                                                   FnRetType,
1108                                                            NRVOCandidate != 0),
1109                               SourceLocation(),
1110                               Owned(RetValExp));
1111      if (Res.isInvalid()) {
1112        // FIXME: Cleanup temporaries here, anyway?
1113        return StmtError();
1114      }
1115
1116      if (RetValExp)
1117        RetValExp = MaybeCreateCXXExprWithTemporaries(RetValExp);
1118
1119      RetValExp = Res.takeAs<Expr>();
1120      if (RetValExp)
1121        CheckReturnStackAddr(RetValExp, FnRetType, ReturnLoc);
1122    }
1123
1124    Result = new (Context) ReturnStmt(ReturnLoc, RetValExp, NRVOCandidate);
1125  }
1126
1127  // If we need to check for the named return value optimization, save the
1128  // return statement in our scope for later processing.
1129  if (getLangOptions().CPlusPlus && FnRetType->isRecordType() &&
1130      !CurContext->isDependentContext())
1131    FunctionScopes.back()->Returns.push_back(Result);
1132
1133  return Owned(Result);
1134}
1135
1136Action::OwningStmtResult
1137Sema::ActOnReturnStmt(SourceLocation ReturnLoc, ExprArg rex) {
1138  Expr *RetValExp = rex.takeAs<Expr>();
1139  if (getCurBlock())
1140    return ActOnBlockReturnStmt(ReturnLoc, RetValExp);
1141
1142  QualType FnRetType;
1143  if (const FunctionDecl *FD = getCurFunctionDecl()) {
1144    FnRetType = FD->getResultType();
1145    if (FD->hasAttr<NoReturnAttr>() ||
1146        FD->getType()->getAs<FunctionType>()->getNoReturnAttr())
1147      Diag(ReturnLoc, diag::warn_noreturn_function_has_return_expr)
1148        << getCurFunctionOrMethodDecl()->getDeclName();
1149  } else if (ObjCMethodDecl *MD = getCurMethodDecl())
1150    FnRetType = MD->getResultType();
1151  else // If we don't have a function/method context, bail.
1152    return StmtError();
1153
1154  ReturnStmt *Result = 0;
1155  if (FnRetType->isVoidType()) {
1156    if (RetValExp && !RetValExp->isTypeDependent()) {
1157      // C99 6.8.6.4p1 (ext_ since GCC warns)
1158      unsigned D = diag::ext_return_has_expr;
1159      if (RetValExp->getType()->isVoidType())
1160        D = diag::ext_return_has_void_expr;
1161
1162      // return (some void expression); is legal in C++.
1163      if (D != diag::ext_return_has_void_expr ||
1164          !getLangOptions().CPlusPlus) {
1165        NamedDecl *CurDecl = getCurFunctionOrMethodDecl();
1166        Diag(ReturnLoc, D)
1167          << CurDecl->getDeclName() << isa<ObjCMethodDecl>(CurDecl)
1168          << RetValExp->getSourceRange();
1169      }
1170
1171      RetValExp = MaybeCreateCXXExprWithTemporaries(RetValExp);
1172    }
1173
1174    Result = new (Context) ReturnStmt(ReturnLoc, RetValExp, 0);
1175  } else if (!RetValExp && !FnRetType->isDependentType()) {
1176    unsigned DiagID = diag::warn_return_missing_expr;  // C90 6.6.6.4p4
1177    // C99 6.8.6.4p1 (ext_ since GCC warns)
1178    if (getLangOptions().C99) DiagID = diag::ext_return_missing_expr;
1179
1180    if (FunctionDecl *FD = getCurFunctionDecl())
1181      Diag(ReturnLoc, DiagID) << FD->getIdentifier() << 0/*fn*/;
1182    else
1183      Diag(ReturnLoc, DiagID) << getCurMethodDecl()->getDeclName() << 1/*meth*/;
1184    Result = new (Context) ReturnStmt(ReturnLoc);
1185  } else {
1186    const VarDecl *NRVOCandidate = 0;
1187    if (!FnRetType->isDependentType() && !RetValExp->isTypeDependent()) {
1188      // we have a non-void function with an expression, continue checking
1189
1190      // C99 6.8.6.4p3(136): The return statement is not an assignment. The
1191      // overlap restriction of subclause 6.5.16.1 does not apply to the case of
1192      // function return.
1193
1194      // In C++ the return statement is handled via a copy initialization.
1195      // the C version of which boils down to CheckSingleAssignmentConstraints.
1196      NRVOCandidate = getNRVOCandidate(Context, FnRetType, RetValExp);
1197      OwningExprResult Res = PerformCopyInitialization(
1198                               InitializedEntity::InitializeResult(ReturnLoc,
1199                                                                   FnRetType,
1200                                                            NRVOCandidate != 0),
1201                               SourceLocation(),
1202                               Owned(RetValExp));
1203      if (Res.isInvalid()) {
1204        // FIXME: Cleanup temporaries here, anyway?
1205        return StmtError();
1206      }
1207
1208      RetValExp = Res.takeAs<Expr>();
1209      if (RetValExp)
1210        CheckReturnStackAddr(RetValExp, FnRetType, ReturnLoc);
1211    }
1212
1213    if (RetValExp)
1214      RetValExp = MaybeCreateCXXExprWithTemporaries(RetValExp);
1215    Result = new (Context) ReturnStmt(ReturnLoc, RetValExp, NRVOCandidate);
1216  }
1217
1218  // If we need to check for the named return value optimization, save the
1219  // return statement in our scope for later processing.
1220  if (getLangOptions().CPlusPlus && FnRetType->isRecordType() &&
1221      !CurContext->isDependentContext())
1222    FunctionScopes.back()->Returns.push_back(Result);
1223
1224  return Owned(Result);
1225}
1226
1227/// CheckAsmLValue - GNU C has an extremely ugly extension whereby they silently
1228/// ignore "noop" casts in places where an lvalue is required by an inline asm.
1229/// We emulate this behavior when -fheinous-gnu-extensions is specified, but
1230/// provide a strong guidance to not use it.
1231///
1232/// This method checks to see if the argument is an acceptable l-value and
1233/// returns false if it is a case we can handle.
1234static bool CheckAsmLValue(const Expr *E, Sema &S) {
1235  // Type dependent expressions will be checked during instantiation.
1236  if (E->isTypeDependent())
1237    return false;
1238
1239  if (E->isLvalue(S.Context) == Expr::LV_Valid)
1240    return false;  // Cool, this is an lvalue.
1241
1242  // Okay, this is not an lvalue, but perhaps it is the result of a cast that we
1243  // are supposed to allow.
1244  const Expr *E2 = E->IgnoreParenNoopCasts(S.Context);
1245  if (E != E2 && E2->isLvalue(S.Context) == Expr::LV_Valid) {
1246    if (!S.getLangOptions().HeinousExtensions)
1247      S.Diag(E2->getLocStart(), diag::err_invalid_asm_cast_lvalue)
1248        << E->getSourceRange();
1249    else
1250      S.Diag(E2->getLocStart(), diag::warn_invalid_asm_cast_lvalue)
1251        << E->getSourceRange();
1252    // Accept, even if we emitted an error diagnostic.
1253    return false;
1254  }
1255
1256  // None of the above, just randomly invalid non-lvalue.
1257  return true;
1258}
1259
1260
1261Sema::OwningStmtResult Sema::ActOnAsmStmt(SourceLocation AsmLoc,
1262                                          bool IsSimple,
1263                                          bool IsVolatile,
1264                                          unsigned NumOutputs,
1265                                          unsigned NumInputs,
1266                                          IdentifierInfo **Names,
1267                                          MultiExprArg constraints,
1268                                          MultiExprArg exprs,
1269                                          ExprArg asmString,
1270                                          MultiExprArg clobbers,
1271                                          SourceLocation RParenLoc,
1272                                          bool MSAsm) {
1273  unsigned NumClobbers = clobbers.size();
1274  StringLiteral **Constraints =
1275    reinterpret_cast<StringLiteral**>(constraints.get());
1276  Expr **Exprs = reinterpret_cast<Expr **>(exprs.get());
1277  StringLiteral *AsmString = cast<StringLiteral>((Expr *)asmString.get());
1278  StringLiteral **Clobbers = reinterpret_cast<StringLiteral**>(clobbers.get());
1279
1280  llvm::SmallVector<TargetInfo::ConstraintInfo, 4> OutputConstraintInfos;
1281
1282  // The parser verifies that there is a string literal here.
1283  if (AsmString->isWide())
1284    return StmtError(Diag(AsmString->getLocStart(),diag::err_asm_wide_character)
1285      << AsmString->getSourceRange());
1286
1287  for (unsigned i = 0; i != NumOutputs; i++) {
1288    StringLiteral *Literal = Constraints[i];
1289    if (Literal->isWide())
1290      return StmtError(Diag(Literal->getLocStart(),diag::err_asm_wide_character)
1291        << Literal->getSourceRange());
1292
1293    llvm::StringRef OutputName;
1294    if (Names[i])
1295      OutputName = Names[i]->getName();
1296
1297    TargetInfo::ConstraintInfo Info(Literal->getString(), OutputName);
1298    if (!Context.Target.validateOutputConstraint(Info))
1299      return StmtError(Diag(Literal->getLocStart(),
1300                            diag::err_asm_invalid_output_constraint)
1301                       << Info.getConstraintStr());
1302
1303    // Check that the output exprs are valid lvalues.
1304    Expr *OutputExpr = Exprs[i];
1305    if (CheckAsmLValue(OutputExpr, *this)) {
1306      return StmtError(Diag(OutputExpr->getLocStart(),
1307                  diag::err_asm_invalid_lvalue_in_output)
1308        << OutputExpr->getSourceRange());
1309    }
1310
1311    OutputConstraintInfos.push_back(Info);
1312  }
1313
1314  llvm::SmallVector<TargetInfo::ConstraintInfo, 4> InputConstraintInfos;
1315
1316  for (unsigned i = NumOutputs, e = NumOutputs + NumInputs; i != e; i++) {
1317    StringLiteral *Literal = Constraints[i];
1318    if (Literal->isWide())
1319      return StmtError(Diag(Literal->getLocStart(),diag::err_asm_wide_character)
1320        << Literal->getSourceRange());
1321
1322    llvm::StringRef InputName;
1323    if (Names[i])
1324      InputName = Names[i]->getName();
1325
1326    TargetInfo::ConstraintInfo Info(Literal->getString(), InputName);
1327    if (!Context.Target.validateInputConstraint(OutputConstraintInfos.data(),
1328                                                NumOutputs, Info)) {
1329      return StmtError(Diag(Literal->getLocStart(),
1330                            diag::err_asm_invalid_input_constraint)
1331                       << Info.getConstraintStr());
1332    }
1333
1334    Expr *InputExpr = Exprs[i];
1335
1336    // Only allow void types for memory constraints.
1337    if (Info.allowsMemory() && !Info.allowsRegister()) {
1338      if (CheckAsmLValue(InputExpr, *this))
1339        return StmtError(Diag(InputExpr->getLocStart(),
1340                              diag::err_asm_invalid_lvalue_in_input)
1341                         << Info.getConstraintStr()
1342                         << InputExpr->getSourceRange());
1343    }
1344
1345    if (Info.allowsRegister()) {
1346      if (InputExpr->getType()->isVoidType()) {
1347        return StmtError(Diag(InputExpr->getLocStart(),
1348                              diag::err_asm_invalid_type_in_input)
1349          << InputExpr->getType() << Info.getConstraintStr()
1350          << InputExpr->getSourceRange());
1351      }
1352    }
1353
1354    DefaultFunctionArrayLvalueConversion(Exprs[i]);
1355
1356    InputConstraintInfos.push_back(Info);
1357  }
1358
1359  // Check that the clobbers are valid.
1360  for (unsigned i = 0; i != NumClobbers; i++) {
1361    StringLiteral *Literal = Clobbers[i];
1362    if (Literal->isWide())
1363      return StmtError(Diag(Literal->getLocStart(),diag::err_asm_wide_character)
1364        << Literal->getSourceRange());
1365
1366    llvm::StringRef Clobber = Literal->getString();
1367
1368    if (!Context.Target.isValidGCCRegisterName(Clobber))
1369      return StmtError(Diag(Literal->getLocStart(),
1370                  diag::err_asm_unknown_register_name) << Clobber);
1371  }
1372
1373  constraints.release();
1374  exprs.release();
1375  asmString.release();
1376  clobbers.release();
1377  AsmStmt *NS =
1378    new (Context) AsmStmt(Context, AsmLoc, IsSimple, IsVolatile, MSAsm,
1379                          NumOutputs, NumInputs, Names, Constraints, Exprs,
1380                          AsmString, NumClobbers, Clobbers, RParenLoc);
1381  // Validate the asm string, ensuring it makes sense given the operands we
1382  // have.
1383  llvm::SmallVector<AsmStmt::AsmStringPiece, 8> Pieces;
1384  unsigned DiagOffs;
1385  if (unsigned DiagID = NS->AnalyzeAsmString(Pieces, Context, DiagOffs)) {
1386    Diag(getLocationOfStringLiteralByte(AsmString, DiagOffs), DiagID)
1387           << AsmString->getSourceRange();
1388    DeleteStmt(NS);
1389    return StmtError();
1390  }
1391
1392  // Validate tied input operands for type mismatches.
1393  for (unsigned i = 0, e = InputConstraintInfos.size(); i != e; ++i) {
1394    TargetInfo::ConstraintInfo &Info = InputConstraintInfos[i];
1395
1396    // If this is a tied constraint, verify that the output and input have
1397    // either exactly the same type, or that they are int/ptr operands with the
1398    // same size (int/long, int*/long, are ok etc).
1399    if (!Info.hasTiedOperand()) continue;
1400
1401    unsigned TiedTo = Info.getTiedOperand();
1402    Expr *OutputExpr = Exprs[TiedTo];
1403    Expr *InputExpr = Exprs[i+NumOutputs];
1404    QualType InTy = InputExpr->getType();
1405    QualType OutTy = OutputExpr->getType();
1406    if (Context.hasSameType(InTy, OutTy))
1407      continue;  // All types can be tied to themselves.
1408
1409    // Decide if the input and output are in the same domain (integer/ptr or
1410    // floating point.
1411    enum AsmDomain {
1412      AD_Int, AD_FP, AD_Other
1413    } InputDomain, OutputDomain;
1414
1415    if (InTy->isIntegerType() || InTy->isPointerType())
1416      InputDomain = AD_Int;
1417    else if (InTy->isRealFloatingType())
1418      InputDomain = AD_FP;
1419    else
1420      InputDomain = AD_Other;
1421
1422    if (OutTy->isIntegerType() || OutTy->isPointerType())
1423      OutputDomain = AD_Int;
1424    else if (OutTy->isRealFloatingType())
1425      OutputDomain = AD_FP;
1426    else
1427      OutputDomain = AD_Other;
1428
1429    // They are ok if they are the same size and in the same domain.  This
1430    // allows tying things like:
1431    //   void* to int*
1432    //   void* to int            if they are the same size.
1433    //   double to long double   if they are the same size.
1434    //
1435    uint64_t OutSize = Context.getTypeSize(OutTy);
1436    uint64_t InSize = Context.getTypeSize(InTy);
1437    if (OutSize == InSize && InputDomain == OutputDomain &&
1438        InputDomain != AD_Other)
1439      continue;
1440
1441    // If the smaller input/output operand is not mentioned in the asm string,
1442    // then we can promote it and the asm string won't notice.  Check this
1443    // case now.
1444    bool SmallerValueMentioned = false;
1445    for (unsigned p = 0, e = Pieces.size(); p != e; ++p) {
1446      AsmStmt::AsmStringPiece &Piece = Pieces[p];
1447      if (!Piece.isOperand()) continue;
1448
1449      // If this is a reference to the input and if the input was the smaller
1450      // one, then we have to reject this asm.
1451      if (Piece.getOperandNo() == i+NumOutputs) {
1452        if (InSize < OutSize) {
1453          SmallerValueMentioned = true;
1454          break;
1455        }
1456      }
1457
1458      // If this is a reference to the input and if the input was the smaller
1459      // one, then we have to reject this asm.
1460      if (Piece.getOperandNo() == TiedTo) {
1461        if (InSize > OutSize) {
1462          SmallerValueMentioned = true;
1463          break;
1464        }
1465      }
1466    }
1467
1468    // If the smaller value wasn't mentioned in the asm string, and if the
1469    // output was a register, just extend the shorter one to the size of the
1470    // larger one.
1471    if (!SmallerValueMentioned && InputDomain != AD_Other &&
1472        OutputConstraintInfos[TiedTo].allowsRegister())
1473      continue;
1474
1475    Diag(InputExpr->getLocStart(),
1476         diag::err_asm_tying_incompatible_types)
1477      << InTy << OutTy << OutputExpr->getSourceRange()
1478      << InputExpr->getSourceRange();
1479    DeleteStmt(NS);
1480    return StmtError();
1481  }
1482
1483  return Owned(NS);
1484}
1485
1486Action::OwningStmtResult
1487Sema::ActOnObjCAtCatchStmt(SourceLocation AtLoc,
1488                           SourceLocation RParen, DeclPtrTy Parm,
1489                           StmtArg Body) {
1490  VarDecl *Var = cast_or_null<VarDecl>(Parm.getAs<Decl>());
1491  if (Var && Var->isInvalidDecl())
1492    return StmtError();
1493
1494  return Owned(new (Context) ObjCAtCatchStmt(AtLoc, RParen, Var,
1495                                             Body.takeAs<Stmt>()));
1496}
1497
1498Action::OwningStmtResult
1499Sema::ActOnObjCAtFinallyStmt(SourceLocation AtLoc, StmtArg Body) {
1500  return Owned(new (Context) ObjCAtFinallyStmt(AtLoc,
1501                                           static_cast<Stmt*>(Body.release())));
1502}
1503
1504Action::OwningStmtResult
1505Sema::ActOnObjCAtTryStmt(SourceLocation AtLoc, StmtArg Try,
1506                         MultiStmtArg CatchStmts, StmtArg Finally) {
1507  FunctionNeedsScopeChecking() = true;
1508  unsigned NumCatchStmts = CatchStmts.size();
1509  return Owned(ObjCAtTryStmt::Create(Context, AtLoc, Try.takeAs<Stmt>(),
1510                                     (Stmt **)CatchStmts.release(),
1511                                     NumCatchStmts,
1512                                     Finally.takeAs<Stmt>()));
1513}
1514
1515Sema::OwningStmtResult Sema::BuildObjCAtThrowStmt(SourceLocation AtLoc,
1516                                                  ExprArg ThrowE) {
1517  Expr *Throw = static_cast<Expr *>(ThrowE.get());
1518  if (Throw) {
1519    QualType ThrowType = Throw->getType();
1520    // Make sure the expression type is an ObjC pointer or "void *".
1521    if (!ThrowType->isDependentType() &&
1522        !ThrowType->isObjCObjectPointerType()) {
1523      const PointerType *PT = ThrowType->getAs<PointerType>();
1524      if (!PT || !PT->getPointeeType()->isVoidType())
1525        return StmtError(Diag(AtLoc, diag::error_objc_throw_expects_object)
1526                         << Throw->getType() << Throw->getSourceRange());
1527    }
1528  }
1529
1530  return Owned(new (Context) ObjCAtThrowStmt(AtLoc, ThrowE.takeAs<Expr>()));
1531}
1532
1533Action::OwningStmtResult
1534Sema::ActOnObjCAtThrowStmt(SourceLocation AtLoc, ExprArg Throw,
1535                           Scope *CurScope) {
1536  if (!Throw.get()) {
1537    // @throw without an expression designates a rethrow (which much occur
1538    // in the context of an @catch clause).
1539    Scope *AtCatchParent = CurScope;
1540    while (AtCatchParent && !AtCatchParent->isAtCatchScope())
1541      AtCatchParent = AtCatchParent->getParent();
1542    if (!AtCatchParent)
1543      return StmtError(Diag(AtLoc, diag::error_rethrow_used_outside_catch));
1544  }
1545
1546  return BuildObjCAtThrowStmt(AtLoc, move(Throw));
1547}
1548
1549Action::OwningStmtResult
1550Sema::ActOnObjCAtSynchronizedStmt(SourceLocation AtLoc, ExprArg SynchExpr,
1551                                  StmtArg SynchBody) {
1552  FunctionNeedsScopeChecking() = true;
1553
1554  // Make sure the expression type is an ObjC pointer or "void *".
1555  Expr *SyncExpr = static_cast<Expr*>(SynchExpr.get());
1556  if (!SyncExpr->getType()->isDependentType() &&
1557      !SyncExpr->getType()->isObjCObjectPointerType()) {
1558    const PointerType *PT = SyncExpr->getType()->getAs<PointerType>();
1559    if (!PT || !PT->getPointeeType()->isVoidType())
1560      return StmtError(Diag(AtLoc, diag::error_objc_synchronized_expects_object)
1561                       << SyncExpr->getType() << SyncExpr->getSourceRange());
1562  }
1563
1564  return Owned(new (Context) ObjCAtSynchronizedStmt(AtLoc,
1565                                                    SynchExpr.takeAs<Stmt>(),
1566                                                    SynchBody.takeAs<Stmt>()));
1567}
1568
1569/// ActOnCXXCatchBlock - Takes an exception declaration and a handler block
1570/// and creates a proper catch handler from them.
1571Action::OwningStmtResult
1572Sema::ActOnCXXCatchBlock(SourceLocation CatchLoc, DeclPtrTy ExDecl,
1573                         StmtArg HandlerBlock) {
1574  // There's nothing to test that ActOnExceptionDecl didn't already test.
1575  return Owned(new (Context) CXXCatchStmt(CatchLoc,
1576                                  cast_or_null<VarDecl>(ExDecl.getAs<Decl>()),
1577                                          HandlerBlock.takeAs<Stmt>()));
1578}
1579
1580class TypeWithHandler {
1581  QualType t;
1582  CXXCatchStmt *stmt;
1583public:
1584  TypeWithHandler(const QualType &type, CXXCatchStmt *statement)
1585  : t(type), stmt(statement) {}
1586
1587  // An arbitrary order is fine as long as it places identical
1588  // types next to each other.
1589  bool operator<(const TypeWithHandler &y) const {
1590    if (t.getAsOpaquePtr() < y.t.getAsOpaquePtr())
1591      return true;
1592    if (t.getAsOpaquePtr() > y.t.getAsOpaquePtr())
1593      return false;
1594    else
1595      return getTypeSpecStartLoc() < y.getTypeSpecStartLoc();
1596  }
1597
1598  bool operator==(const TypeWithHandler& other) const {
1599    return t == other.t;
1600  }
1601
1602  QualType getQualType() const { return t; }
1603  CXXCatchStmt *getCatchStmt() const { return stmt; }
1604  SourceLocation getTypeSpecStartLoc() const {
1605    return stmt->getExceptionDecl()->getTypeSpecStartLoc();
1606  }
1607};
1608
1609/// ActOnCXXTryBlock - Takes a try compound-statement and a number of
1610/// handlers and creates a try statement from them.
1611Action::OwningStmtResult
1612Sema::ActOnCXXTryBlock(SourceLocation TryLoc, StmtArg TryBlock,
1613                       MultiStmtArg RawHandlers) {
1614  unsigned NumHandlers = RawHandlers.size();
1615  assert(NumHandlers > 0 &&
1616         "The parser shouldn't call this if there are no handlers.");
1617  Stmt **Handlers = reinterpret_cast<Stmt**>(RawHandlers.get());
1618
1619  llvm::SmallVector<TypeWithHandler, 8> TypesWithHandlers;
1620
1621  for (unsigned i = 0; i < NumHandlers; ++i) {
1622    CXXCatchStmt *Handler = llvm::cast<CXXCatchStmt>(Handlers[i]);
1623    if (!Handler->getExceptionDecl()) {
1624      if (i < NumHandlers - 1)
1625        return StmtError(Diag(Handler->getLocStart(),
1626                              diag::err_early_catch_all));
1627
1628      continue;
1629    }
1630
1631    const QualType CaughtType = Handler->getCaughtType();
1632    const QualType CanonicalCaughtType = Context.getCanonicalType(CaughtType);
1633    TypesWithHandlers.push_back(TypeWithHandler(CanonicalCaughtType, Handler));
1634  }
1635
1636  // Detect handlers for the same type as an earlier one.
1637  if (NumHandlers > 1) {
1638    llvm::array_pod_sort(TypesWithHandlers.begin(), TypesWithHandlers.end());
1639
1640    TypeWithHandler prev = TypesWithHandlers[0];
1641    for (unsigned i = 1; i < TypesWithHandlers.size(); ++i) {
1642      TypeWithHandler curr = TypesWithHandlers[i];
1643
1644      if (curr == prev) {
1645        Diag(curr.getTypeSpecStartLoc(),
1646             diag::warn_exception_caught_by_earlier_handler)
1647          << curr.getCatchStmt()->getCaughtType().getAsString();
1648        Diag(prev.getTypeSpecStartLoc(),
1649             diag::note_previous_exception_handler)
1650          << prev.getCatchStmt()->getCaughtType().getAsString();
1651      }
1652
1653      prev = curr;
1654    }
1655  }
1656
1657  // FIXME: We should detect handlers that cannot catch anything because an
1658  // earlier handler catches a superclass. Need to find a method that is not
1659  // quadratic for this.
1660  // Neither of these are explicitly forbidden, but every compiler detects them
1661  // and warns.
1662
1663  FunctionNeedsScopeChecking() = true;
1664  RawHandlers.release();
1665  return Owned(CXXTryStmt::Create(Context, TryLoc,
1666                                  static_cast<Stmt*>(TryBlock.release()),
1667                                  Handlers, NumHandlers));
1668}
1669