SemaStmt.cpp revision f031774aa2638b4d3f487e7e44180c1f89b867ef 
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/Lex/Preprocessor.h"
24#include "clang/Basic/TargetInfo.h"
25#include "llvm/ADT/STLExtras.h"
26#include "llvm/ADT/SmallVector.h"
27using namespace clang;
28
29Sema::OwningStmtResult Sema::ActOnExprStmt(FullExprArg expr) {
30  Expr *E = expr->takeAs<Expr>();
31  assert(E && "ActOnExprStmt(): missing expression");
32  if (E->getType()->isObjCInterfaceType()) {
33    if (LangOpts.ObjCNonFragileABI)
34      Diag(E->getLocEnd(), diag::err_indirection_requires_nonfragile_object)
35             << E->getType();
36    else
37      Diag(E->getLocEnd(), diag::err_direct_interface_unsupported)
38             << E->getType();
39    return StmtError();
40  }
41  // C99 6.8.3p2: The expression in an expression statement is evaluated as a
42  // void expression for its side effects.  Conversion to void allows any
43  // operand, even incomplete types.
44
45  // Same thing in for stmt first clause (when expr) and third clause.
46  return Owned(static_cast<Stmt*>(E));
47}
48
49
50Sema::OwningStmtResult Sema::ActOnNullStmt(SourceLocation SemiLoc) {
51  return Owned(new (Context) NullStmt(SemiLoc));
52}
53
54Sema::OwningStmtResult Sema::ActOnDeclStmt(DeclGroupPtrTy dg,
55                                           SourceLocation StartLoc,
56                                           SourceLocation EndLoc) {
57  DeclGroupRef DG = dg.getAsVal<DeclGroupRef>();
58
59  // If we have an invalid decl, just return an error.
60  if (DG.isNull()) return StmtError();
61
62  return Owned(new (Context) DeclStmt(DG, StartLoc, EndLoc));
63}
64
65void Sema::ActOnForEachDeclStmt(DeclGroupPtrTy dg) {
66  DeclGroupRef DG = dg.getAsVal<DeclGroupRef>();
67
68  // If we have an invalid decl, just return.
69  if (DG.isNull() || !DG.isSingleDecl()) return;
70  // suppress any potential 'unused variable' warning.
71  DG.getSingleDecl()->setUsed();
72}
73
74void Sema::DiagnoseUnusedExprResult(const Stmt *S) {
75  const Expr *E = dyn_cast_or_null<Expr>(S);
76  if (!E)
77    return;
78
79  SourceLocation Loc;
80  SourceRange R1, R2;
81  if (!E->isUnusedResultAWarning(Loc, R1, R2, Context))
82    return;
83
84  // Okay, we have an unused result.  Depending on what the base expression is,
85  // we might want to make a more specific diagnostic.  Check for one of these
86  // cases now.
87  unsigned DiagID = diag::warn_unused_expr;
88  E = E->IgnoreParens();
89  if (isa<ObjCImplicitSetterGetterRefExpr>(E))
90    DiagID = diag::warn_unused_property_expr;
91
92  if (const CXXExprWithTemporaries *Temps = dyn_cast<CXXExprWithTemporaries>(E))
93    E = Temps->getSubExpr();
94  if (const CXXZeroInitValueExpr *Zero = dyn_cast<CXXZeroInitValueExpr>(E)) {
95    if (const RecordType *RecordT = Zero->getType()->getAs<RecordType>())
96      if (CXXRecordDecl *RecordD = dyn_cast<CXXRecordDecl>(RecordT->getDecl()))
97        if (!RecordD->hasTrivialDestructor())
98          return;
99  }
100
101  if (const CallExpr *CE = dyn_cast<CallExpr>(E)) {
102    if (E->getType()->isVoidType())
103      return;
104
105    // If the callee has attribute pure, const, or warn_unused_result, warn with
106    // a more specific message to make it clear what is happening.
107    if (const Decl *FD = CE->getCalleeDecl()) {
108      if (FD->getAttr<WarnUnusedResultAttr>()) {
109        Diag(Loc, diag::warn_unused_call) << R1 << R2 << "warn_unused_result";
110        return;
111      }
112      if (FD->getAttr<PureAttr>()) {
113        Diag(Loc, diag::warn_unused_call) << R1 << R2 << "pure";
114        return;
115      }
116      if (FD->getAttr<ConstAttr>()) {
117        Diag(Loc, diag::warn_unused_call) << R1 << R2 << "const";
118        return;
119      }
120    }
121  }
122  else if (const ObjCMessageExpr *ME = dyn_cast<ObjCMessageExpr>(E)) {
123    const ObjCMethodDecl *MD = ME->getMethodDecl();
124    if (MD && MD->getAttr<WarnUnusedResultAttr>()) {
125      Diag(Loc, diag::warn_unused_call) << R1 << R2 << "warn_unused_result";
126      return;
127    }
128  }
129  Diag(Loc, DiagID) << R1 << R2;
130}
131
132Action::OwningStmtResult
133Sema::ActOnCompoundStmt(SourceLocation L, SourceLocation R,
134                        MultiStmtArg elts, bool isStmtExpr) {
135  unsigned NumElts = elts.size();
136  Stmt **Elts = reinterpret_cast<Stmt**>(elts.release());
137  // If we're in C89 mode, check that we don't have any decls after stmts.  If
138  // so, emit an extension diagnostic.
139  if (!getLangOptions().C99 && !getLangOptions().CPlusPlus) {
140    // Note that __extension__ can be around a decl.
141    unsigned i = 0;
142    // Skip over all declarations.
143    for (; i != NumElts && isa<DeclStmt>(Elts[i]); ++i)
144      /*empty*/;
145
146    // We found the end of the list or a statement.  Scan for another declstmt.
147    for (; i != NumElts && !isa<DeclStmt>(Elts[i]); ++i)
148      /*empty*/;
149
150    if (i != NumElts) {
151      Decl *D = *cast<DeclStmt>(Elts[i])->decl_begin();
152      Diag(D->getLocation(), diag::ext_mixed_decls_code);
153    }
154  }
155  // Warn about unused expressions in statements.
156  for (unsigned i = 0; i != NumElts; ++i) {
157    // Ignore statements that are last in a statement expression.
158    if (isStmtExpr && i == NumElts - 1)
159      continue;
160
161    DiagnoseUnusedExprResult(Elts[i]);
162  }
163
164  return Owned(new (Context) CompoundStmt(Context, Elts, NumElts, L, R));
165}
166
167Action::OwningStmtResult
168Sema::ActOnCaseStmt(SourceLocation CaseLoc, ExprArg lhsval,
169                    SourceLocation DotDotDotLoc, ExprArg rhsval,
170                    SourceLocation ColonLoc) {
171  assert((lhsval.get() != 0) && "missing expression in case statement");
172
173  // C99 6.8.4.2p3: The expression shall be an integer constant.
174  // However, GCC allows any evaluatable integer expression.
175  Expr *LHSVal = static_cast<Expr*>(lhsval.get());
176  if (!LHSVal->isTypeDependent() && !LHSVal->isValueDependent() &&
177      VerifyIntegerConstantExpression(LHSVal))
178    return StmtError();
179
180  // GCC extension: The expression shall be an integer constant.
181
182  Expr *RHSVal = static_cast<Expr*>(rhsval.get());
183  if (RHSVal && !RHSVal->isTypeDependent() && !RHSVal->isValueDependent() &&
184      VerifyIntegerConstantExpression(RHSVal)) {
185    RHSVal = 0;  // Recover by just forgetting about it.
186    rhsval = 0;
187  }
188
189  if (getSwitchStack().empty()) {
190    Diag(CaseLoc, diag::err_case_not_in_switch);
191    return StmtError();
192  }
193
194  // Only now release the smart pointers.
195  lhsval.release();
196  rhsval.release();
197  CaseStmt *CS = new (Context) CaseStmt(LHSVal, RHSVal, CaseLoc, DotDotDotLoc,
198                                        ColonLoc);
199  getSwitchStack().back()->addSwitchCase(CS);
200  return Owned(CS);
201}
202
203/// ActOnCaseStmtBody - This installs a statement as the body of a case.
204void Sema::ActOnCaseStmtBody(StmtTy *caseStmt, StmtArg subStmt) {
205  CaseStmt *CS = static_cast<CaseStmt*>(caseStmt);
206  Stmt *SubStmt = subStmt.takeAs<Stmt>();
207  CS->setSubStmt(SubStmt);
208}
209
210Action::OwningStmtResult
211Sema::ActOnDefaultStmt(SourceLocation DefaultLoc, SourceLocation ColonLoc,
212                       StmtArg subStmt, Scope *CurScope) {
213  Stmt *SubStmt = subStmt.takeAs<Stmt>();
214
215  if (getSwitchStack().empty()) {
216    Diag(DefaultLoc, diag::err_default_not_in_switch);
217    return Owned(SubStmt);
218  }
219
220  DefaultStmt *DS = new (Context) DefaultStmt(DefaultLoc, ColonLoc, SubStmt);
221  getSwitchStack().back()->addSwitchCase(DS);
222  return Owned(DS);
223}
224
225Action::OwningStmtResult
226Sema::ActOnLabelStmt(SourceLocation IdentLoc, IdentifierInfo *II,
227                     SourceLocation ColonLoc, StmtArg subStmt) {
228  Stmt *SubStmt = subStmt.takeAs<Stmt>();
229  // Look up the record for this label identifier.
230  LabelStmt *&LabelDecl = getLabelMap()[II];
231
232  // If not forward referenced or defined already, just create a new LabelStmt.
233  if (LabelDecl == 0)
234    return Owned(LabelDecl = new (Context) LabelStmt(IdentLoc, II, SubStmt));
235
236  assert(LabelDecl->getID() == II && "Label mismatch!");
237
238  // Otherwise, this label was either forward reference or multiply defined.  If
239  // multiply defined, reject it now.
240  if (LabelDecl->getSubStmt()) {
241    Diag(IdentLoc, diag::err_redefinition_of_label) << LabelDecl->getID();
242    Diag(LabelDecl->getIdentLoc(), diag::note_previous_definition);
243    return Owned(SubStmt);
244  }
245
246  // Otherwise, this label was forward declared, and we just found its real
247  // definition.  Fill in the forward definition and return it.
248  LabelDecl->setIdentLoc(IdentLoc);
249  LabelDecl->setSubStmt(SubStmt);
250  return Owned(LabelDecl);
251}
252
253Action::OwningStmtResult
254Sema::ActOnIfStmt(SourceLocation IfLoc, FullExprArg CondVal, DeclPtrTy CondVar,
255                  StmtArg ThenVal, SourceLocation ElseLoc,
256                  StmtArg ElseVal) {
257  OwningExprResult CondResult(CondVal.release());
258
259  VarDecl *ConditionVar = 0;
260  if (CondVar.get()) {
261    ConditionVar = CondVar.getAs<VarDecl>();
262    CondResult = CheckConditionVariable(ConditionVar);
263    if (CondResult.isInvalid())
264      return StmtError();
265  }
266  Expr *ConditionExpr = CondResult.takeAs<Expr>();
267  if (!ConditionExpr)
268    return StmtError();
269
270  if (CheckBooleanCondition(ConditionExpr, IfLoc)) {
271    CondResult = ConditionExpr;
272    return StmtError();
273  }
274
275  Stmt *thenStmt = ThenVal.takeAs<Stmt>();
276  DiagnoseUnusedExprResult(thenStmt);
277
278  // Warn if the if block has a null body without an else value.
279  // this helps prevent bugs due to typos, such as
280  // if (condition);
281  //   do_stuff();
282  if (!ElseVal.get()) {
283    if (NullStmt* stmt = dyn_cast<NullStmt>(thenStmt))
284      Diag(stmt->getSemiLoc(), diag::warn_empty_if_body);
285  }
286
287  Stmt *elseStmt = ElseVal.takeAs<Stmt>();
288  DiagnoseUnusedExprResult(elseStmt);
289
290  CondResult.release();
291  return Owned(new (Context) IfStmt(IfLoc, ConditionVar, ConditionExpr,
292                                    thenStmt, ElseLoc, elseStmt));
293}
294
295Action::OwningStmtResult
296Sema::ActOnStartOfSwitchStmt(FullExprArg cond, DeclPtrTy CondVar) {
297  OwningExprResult CondResult(cond.release());
298
299  VarDecl *ConditionVar = 0;
300  if (CondVar.get()) {
301    ConditionVar = CondVar.getAs<VarDecl>();
302    CondResult = CheckConditionVariable(ConditionVar);
303    if (CondResult.isInvalid())
304      return StmtError();
305  }
306  SwitchStmt *SS = new (Context) SwitchStmt(ConditionVar,
307                                            CondResult.takeAs<Expr>());
308  getSwitchStack().push_back(SS);
309  return Owned(SS);
310}
311
312/// ConvertIntegerToTypeWarnOnOverflow - Convert the specified APInt to have
313/// the specified width and sign.  If an overflow occurs, detect it and emit
314/// the specified diagnostic.
315void Sema::ConvertIntegerToTypeWarnOnOverflow(llvm::APSInt &Val,
316                                              unsigned NewWidth, bool NewSign,
317                                              SourceLocation Loc,
318                                              unsigned DiagID) {
319  // Perform a conversion to the promoted condition type if needed.
320  if (NewWidth > Val.getBitWidth()) {
321    // If this is an extension, just do it.
322    Val.extend(NewWidth);
323    Val.setIsSigned(NewSign);
324
325    // If the input was signed and negative and the output is
326    // unsigned, don't bother to warn: this is implementation-defined
327    // behavior.
328    // FIXME: Introduce a second, default-ignored warning for this case?
329  } else if (NewWidth < Val.getBitWidth()) {
330    // If this is a truncation, check for overflow.
331    llvm::APSInt ConvVal(Val);
332    ConvVal.trunc(NewWidth);
333    ConvVal.setIsSigned(NewSign);
334    ConvVal.extend(Val.getBitWidth());
335    ConvVal.setIsSigned(Val.isSigned());
336    if (ConvVal != Val)
337      Diag(Loc, DiagID) << Val.toString(10) << ConvVal.toString(10);
338
339    // Regardless of whether a diagnostic was emitted, really do the
340    // truncation.
341    Val.trunc(NewWidth);
342    Val.setIsSigned(NewSign);
343  } else if (NewSign != Val.isSigned()) {
344    // Convert the sign to match the sign of the condition.  This can cause
345    // overflow as well: unsigned(INTMIN)
346    // We don't diagnose this overflow, because it is implementation-defined
347    // behavior.
348    // FIXME: Introduce a second, default-ignored warning for this case?
349    llvm::APSInt OldVal(Val);
350    Val.setIsSigned(NewSign);
351  }
352}
353
354namespace {
355  struct CaseCompareFunctor {
356    bool operator()(const std::pair<llvm::APSInt, CaseStmt*> &LHS,
357                    const llvm::APSInt &RHS) {
358      return LHS.first < RHS;
359    }
360    bool operator()(const std::pair<llvm::APSInt, CaseStmt*> &LHS,
361                    const std::pair<llvm::APSInt, CaseStmt*> &RHS) {
362      return LHS.first < RHS.first;
363    }
364    bool operator()(const llvm::APSInt &LHS,
365                    const std::pair<llvm::APSInt, CaseStmt*> &RHS) {
366      return LHS < RHS.first;
367    }
368  };
369}
370
371/// CmpCaseVals - Comparison predicate for sorting case values.
372///
373static bool CmpCaseVals(const std::pair<llvm::APSInt, CaseStmt*>& lhs,
374                        const std::pair<llvm::APSInt, CaseStmt*>& rhs) {
375  if (lhs.first < rhs.first)
376    return true;
377
378  if (lhs.first == rhs.first &&
379      lhs.second->getCaseLoc().getRawEncoding()
380       < rhs.second->getCaseLoc().getRawEncoding())
381    return true;
382  return false;
383}
384
385/// CmpEnumVals - Comparison predicate for sorting enumeration values.
386///
387static bool CmpEnumVals(const std::pair<llvm::APSInt, EnumConstantDecl*>& lhs,
388                        const std::pair<llvm::APSInt, EnumConstantDecl*>& rhs)
389{
390  return lhs.first < rhs.first;
391}
392
393/// EqEnumVals - Comparison preficate for uniqing enumeration values.
394///
395static bool EqEnumVals(const std::pair<llvm::APSInt, EnumConstantDecl*>& lhs,
396                       const std::pair<llvm::APSInt, EnumConstantDecl*>& rhs)
397{
398  return lhs.first == rhs.first;
399}
400
401/// GetTypeBeforeIntegralPromotion - Returns the pre-promotion type of
402/// potentially integral-promoted expression @p expr.
403static QualType GetTypeBeforeIntegralPromotion(const Expr* expr) {
404  const ImplicitCastExpr *ImplicitCast =
405      dyn_cast_or_null<ImplicitCastExpr>(expr);
406  if (ImplicitCast != NULL) {
407    const Expr *ExprBeforePromotion = ImplicitCast->getSubExpr();
408    QualType TypeBeforePromotion = ExprBeforePromotion->getType();
409    if (TypeBeforePromotion->isIntegralType()) {
410      return TypeBeforePromotion;
411    }
412  }
413  return expr->getType();
414}
415
416/// \brief Check (and possibly convert) the condition in a switch
417/// statement in C++.
418static bool CheckCXXSwitchCondition(Sema &S, SourceLocation SwitchLoc,
419                                    Expr *&CondExpr) {
420  if (CondExpr->isTypeDependent())
421    return false;
422
423  QualType CondType = CondExpr->getType();
424
425  // C++ 6.4.2.p2:
426  // The condition shall be of integral type, enumeration type, or of a class
427  // type for which a single conversion function to integral or enumeration
428  // type exists (12.3). If the condition is of class type, the condition is
429  // converted by calling that conversion function, and the result of the
430  // conversion is used in place of the original condition for the remainder
431  // of this section. Integral promotions are performed.
432
433  // Make sure that the condition expression has a complete type,
434  // otherwise we'll never find any conversions.
435  if (S.RequireCompleteType(SwitchLoc, CondType,
436                            S.PDiag(diag::err_switch_incomplete_class_type)
437                              << CondExpr->getSourceRange()))
438    return true;
439
440  llvm::SmallVector<CXXConversionDecl *, 4> ViableConversions;
441  llvm::SmallVector<CXXConversionDecl *, 4> ExplicitConversions;
442  if (const RecordType *RecordTy = CondType->getAs<RecordType>()) {
443    const UnresolvedSetImpl *Conversions
444      = cast<CXXRecordDecl>(RecordTy->getDecl())
445                                             ->getVisibleConversionFunctions();
446    for (UnresolvedSetImpl::iterator I = Conversions->begin(),
447           E = Conversions->end(); I != E; ++I) {
448      if (CXXConversionDecl *Conversion = dyn_cast<CXXConversionDecl>(*I))
449        if (Conversion->getConversionType().getNonReferenceType()
450              ->isIntegralType()) {
451          if (Conversion->isExplicit())
452            ExplicitConversions.push_back(Conversion);
453          else
454          ViableConversions.push_back(Conversion);
455        }
456    }
457
458    switch (ViableConversions.size()) {
459    case 0:
460      if (ExplicitConversions.size() == 1) {
461        // The user probably meant to invoke the given explicit
462        // conversion; use it.
463        QualType ConvTy
464          = ExplicitConversions[0]->getConversionType()
465                        .getNonReferenceType();
466        std::string TypeStr;
467        ConvTy.getAsStringInternal(TypeStr, S.Context.PrintingPolicy);
468
469        S.Diag(SwitchLoc, diag::err_switch_explicit_conversion)
470          << CondType << ConvTy << CondExpr->getSourceRange()
471          << CodeModificationHint::CreateInsertion(CondExpr->getLocStart(),
472                                         "static_cast<" + TypeStr + ">(")
473          << CodeModificationHint::CreateInsertion(
474                            S.PP.getLocForEndOfToken(CondExpr->getLocEnd()),
475                               ")");
476        S.Diag(ExplicitConversions[0]->getLocation(),
477             diag::note_switch_conversion)
478          << ConvTy->isEnumeralType() << ConvTy;
479
480        // If we aren't in a SFINAE context, build a call to the
481        // explicit conversion function.
482        if (S.isSFINAEContext())
483          return true;
484
485        CondExpr = S.BuildCXXMemberCallExpr(CondExpr, ExplicitConversions[0]);
486      }
487
488      // We'll complain below about a non-integral condition type.
489      break;
490
491    case 1:
492      // Apply this conversion.
493      CondExpr = S.BuildCXXMemberCallExpr(CondExpr, ViableConversions[0]);
494      break;
495
496    default:
497      S.Diag(SwitchLoc, diag::err_switch_multiple_conversions)
498        << CondType << CondExpr->getSourceRange();
499      for (unsigned I = 0, N = ViableConversions.size(); I != N; ++I) {
500        QualType ConvTy
501          = ViableConversions[I]->getConversionType().getNonReferenceType();
502        S.Diag(ViableConversions[I]->getLocation(),
503             diag::note_switch_conversion)
504          << ConvTy->isEnumeralType() << ConvTy;
505      }
506      return true;
507    }
508  }
509
510  return false;
511}
512
513/// ActOnSwitchBodyError - This is called if there is an error parsing the
514/// body of the switch stmt instead of ActOnFinishSwitchStmt.
515void Sema::ActOnSwitchBodyError(SourceLocation SwitchLoc, StmtArg Switch,
516                                StmtArg Body) {
517  // Keep the switch stack balanced.
518  assert(getSwitchStack().back() == (SwitchStmt*)Switch.get() &&
519         "switch stack missing push/pop!");
520  getSwitchStack().pop_back();
521}
522
523Action::OwningStmtResult
524Sema::ActOnFinishSwitchStmt(SourceLocation SwitchLoc, StmtArg Switch,
525                            StmtArg Body) {
526  Stmt *BodyStmt = Body.takeAs<Stmt>();
527
528  SwitchStmt *SS = getSwitchStack().back();
529  assert(SS == (SwitchStmt*)Switch.get() && "switch stack missing push/pop!");
530
531  SS->setBody(BodyStmt, SwitchLoc);
532  getSwitchStack().pop_back();
533
534  if (SS->getCond() == 0) {
535    SS->Destroy(Context);
536    return StmtError();
537  }
538
539  Expr *CondExpr = SS->getCond();
540  QualType CondTypeBeforePromotion =
541      GetTypeBeforeIntegralPromotion(CondExpr);
542
543  if (getLangOptions().CPlusPlus &&
544      CheckCXXSwitchCondition(*this, SwitchLoc, CondExpr))
545    return StmtError();
546
547  // C99 6.8.4.2p5 - Integer promotions are performed on the controlling expr.
548  UsualUnaryConversions(CondExpr);
549  QualType CondType = CondExpr->getType();
550  SS->setCond(CondExpr);
551
552  // C++ 6.4.2.p2:
553  // Integral promotions are performed (on the switch condition).
554  //
555  // A case value unrepresentable by the original switch condition
556  // type (before the promotion) doesn't make sense, even when it can
557  // be represented by the promoted type.  Therefore we need to find
558  // the pre-promotion type of the switch condition.
559  if (!CondExpr->isTypeDependent()) {
560    if (!CondType->isIntegerType()) { // C99 6.8.4.2p1
561      Diag(SwitchLoc, diag::err_typecheck_statement_requires_integer)
562          << CondType << CondExpr->getSourceRange();
563      return StmtError();
564    }
565
566    if (CondTypeBeforePromotion->isBooleanType()) {
567      // switch(bool_expr) {...} is often a programmer error, e.g.
568      //   switch(n && mask) { ... }  // Doh - should be "n & mask".
569      // One can always use an if statement instead of switch(bool_expr).
570      Diag(SwitchLoc, diag::warn_bool_switch_condition)
571          << CondExpr->getSourceRange();
572    }
573  }
574
575  // Get the bitwidth of the switched-on value before promotions.  We must
576  // convert the integer case values to this width before comparison.
577  bool HasDependentValue
578    = CondExpr->isTypeDependent() || CondExpr->isValueDependent();
579  unsigned CondWidth
580    = HasDependentValue? 0
581      : static_cast<unsigned>(Context.getTypeSize(CondTypeBeforePromotion));
582  bool CondIsSigned = CondTypeBeforePromotion->isSignedIntegerType();
583
584  // Accumulate all of the case values in a vector so that we can sort them
585  // and detect duplicates.  This vector contains the APInt for the case after
586  // it has been converted to the condition type.
587  typedef llvm::SmallVector<std::pair<llvm::APSInt, CaseStmt*>, 64> CaseValsTy;
588  CaseValsTy CaseVals;
589
590  // Keep track of any GNU case ranges we see.  The APSInt is the low value.
591  typedef std::vector<std::pair<llvm::APSInt, CaseStmt*> > CaseRangesTy;
592  CaseRangesTy CaseRanges;
593
594  DefaultStmt *TheDefaultStmt = 0;
595
596  bool CaseListIsErroneous = false;
597
598  for (SwitchCase *SC = SS->getSwitchCaseList(); SC && !HasDependentValue;
599       SC = SC->getNextSwitchCase()) {
600
601    if (DefaultStmt *DS = dyn_cast<DefaultStmt>(SC)) {
602      if (TheDefaultStmt) {
603        Diag(DS->getDefaultLoc(), diag::err_multiple_default_labels_defined);
604        Diag(TheDefaultStmt->getDefaultLoc(), diag::note_duplicate_case_prev);
605
606        // FIXME: Remove the default statement from the switch block so that
607        // we'll return a valid AST.  This requires recursing down the AST and
608        // finding it, not something we are set up to do right now.  For now,
609        // just lop the entire switch stmt out of the AST.
610        CaseListIsErroneous = true;
611      }
612      TheDefaultStmt = DS;
613
614    } else {
615      CaseStmt *CS = cast<CaseStmt>(SC);
616
617      // We already verified that the expression has a i-c-e value (C99
618      // 6.8.4.2p3) - get that value now.
619      Expr *Lo = CS->getLHS();
620
621      if (Lo->isTypeDependent() || Lo->isValueDependent()) {
622        HasDependentValue = true;
623        break;
624      }
625
626      llvm::APSInt LoVal = Lo->EvaluateAsInt(Context);
627
628      // Convert the value to the same width/sign as the condition.
629      ConvertIntegerToTypeWarnOnOverflow(LoVal, CondWidth, CondIsSigned,
630                                         CS->getLHS()->getLocStart(),
631                                         diag::warn_case_value_overflow);
632
633      // If the LHS is not the same type as the condition, insert an implicit
634      // cast.
635      ImpCastExprToType(Lo, CondType, CastExpr::CK_IntegralCast);
636      CS->setLHS(Lo);
637
638      // If this is a case range, remember it in CaseRanges, otherwise CaseVals.
639      if (CS->getRHS()) {
640        if (CS->getRHS()->isTypeDependent() ||
641            CS->getRHS()->isValueDependent()) {
642          HasDependentValue = true;
643          break;
644        }
645        CaseRanges.push_back(std::make_pair(LoVal, CS));
646      } else
647        CaseVals.push_back(std::make_pair(LoVal, CS));
648    }
649  }
650
651  if (!HasDependentValue) {
652    // Sort all the scalar case values so we can easily detect duplicates.
653    std::stable_sort(CaseVals.begin(), CaseVals.end(), CmpCaseVals);
654
655    if (!CaseVals.empty()) {
656      for (unsigned i = 0, e = CaseVals.size()-1; i != e; ++i) {
657        if (CaseVals[i].first == CaseVals[i+1].first) {
658          // If we have a duplicate, report it.
659          Diag(CaseVals[i+1].second->getLHS()->getLocStart(),
660               diag::err_duplicate_case) << CaseVals[i].first.toString(10);
661          Diag(CaseVals[i].second->getLHS()->getLocStart(),
662               diag::note_duplicate_case_prev);
663          // FIXME: We really want to remove the bogus case stmt from the
664          // substmt, but we have no way to do this right now.
665          CaseListIsErroneous = true;
666        }
667      }
668    }
669
670    // Detect duplicate case ranges, which usually don't exist at all in
671    // the first place.
672    if (!CaseRanges.empty()) {
673      // Sort all the case ranges by their low value so we can easily detect
674      // overlaps between ranges.
675      std::stable_sort(CaseRanges.begin(), CaseRanges.end());
676
677      // Scan the ranges, computing the high values and removing empty ranges.
678      std::vector<llvm::APSInt> HiVals;
679      for (unsigned i = 0, e = CaseRanges.size(); i != e; ++i) {
680        CaseStmt *CR = CaseRanges[i].second;
681        Expr *Hi = CR->getRHS();
682        llvm::APSInt HiVal = Hi->EvaluateAsInt(Context);
683
684        // Convert the value to the same width/sign as the condition.
685        ConvertIntegerToTypeWarnOnOverflow(HiVal, CondWidth, CondIsSigned,
686                                           CR->getRHS()->getLocStart(),
687                                           diag::warn_case_value_overflow);
688
689        // If the LHS is not the same type as the condition, insert an implicit
690        // cast.
691        ImpCastExprToType(Hi, CondType, CastExpr::CK_IntegralCast);
692        CR->setRHS(Hi);
693
694        // If the low value is bigger than the high value, the case is empty.
695        if (CaseRanges[i].first > HiVal) {
696          Diag(CR->getLHS()->getLocStart(), diag::warn_case_empty_range)
697            << SourceRange(CR->getLHS()->getLocStart(),
698                           CR->getRHS()->getLocEnd());
699          CaseRanges.erase(CaseRanges.begin()+i);
700          --i, --e;
701          continue;
702        }
703        HiVals.push_back(HiVal);
704      }
705
706      // Rescan the ranges, looking for overlap with singleton values and other
707      // ranges.  Since the range list is sorted, we only need to compare case
708      // ranges with their neighbors.
709      for (unsigned i = 0, e = CaseRanges.size(); i != e; ++i) {
710        llvm::APSInt &CRLo = CaseRanges[i].first;
711        llvm::APSInt &CRHi = HiVals[i];
712        CaseStmt *CR = CaseRanges[i].second;
713
714        // Check to see whether the case range overlaps with any
715        // singleton cases.
716        CaseStmt *OverlapStmt = 0;
717        llvm::APSInt OverlapVal(32);
718
719        // Find the smallest value >= the lower bound.  If I is in the
720        // case range, then we have overlap.
721        CaseValsTy::iterator I = std::lower_bound(CaseVals.begin(),
722                                                  CaseVals.end(), CRLo,
723                                                  CaseCompareFunctor());
724        if (I != CaseVals.end() && I->first < CRHi) {
725          OverlapVal  = I->first;   // Found overlap with scalar.
726          OverlapStmt = I->second;
727        }
728
729        // Find the smallest value bigger than the upper bound.
730        I = std::upper_bound(I, CaseVals.end(), CRHi, CaseCompareFunctor());
731        if (I != CaseVals.begin() && (I-1)->first >= CRLo) {
732          OverlapVal  = (I-1)->first;      // Found overlap with scalar.
733          OverlapStmt = (I-1)->second;
734        }
735
736        // Check to see if this case stmt overlaps with the subsequent
737        // case range.
738        if (i && CRLo <= HiVals[i-1]) {
739          OverlapVal  = HiVals[i-1];       // Found overlap with range.
740          OverlapStmt = CaseRanges[i-1].second;
741        }
742
743        if (OverlapStmt) {
744          // If we have a duplicate, report it.
745          Diag(CR->getLHS()->getLocStart(), diag::err_duplicate_case)
746            << OverlapVal.toString(10);
747          Diag(OverlapStmt->getLHS()->getLocStart(),
748               diag::note_duplicate_case_prev);
749          // FIXME: We really want to remove the bogus case stmt from the
750          // substmt, but we have no way to do this right now.
751          CaseListIsErroneous = true;
752        }
753      }
754    }
755
756    // Check to see if switch is over an Enum and handles all of its
757    // values
758    const EnumType* ET = CondTypeBeforePromotion->getAs<EnumType>();
759    // If switch has default case, then ignore it.
760    if (!CaseListIsErroneous && !TheDefaultStmt && ET) {
761      const EnumDecl *ED = ET->getDecl();
762      typedef llvm::SmallVector<std::pair<llvm::APSInt, EnumConstantDecl*>, 64> EnumValsTy;
763      EnumValsTy EnumVals;
764
765      // Gather all enum values, set their type and sort them, allowing easier comparison
766      // with CaseVals.
767      for (EnumDecl::enumerator_iterator EDI = ED->enumerator_begin(); EDI != ED->enumerator_end(); EDI++) {
768        llvm::APSInt Val = (*EDI)->getInitVal();
769        if(Val.getBitWidth() < CondWidth)
770          Val.extend(CondWidth);
771        Val.setIsSigned(CondIsSigned);
772        EnumVals.push_back(std::make_pair(Val, (*EDI)));
773      }
774      std::stable_sort(EnumVals.begin(), EnumVals.end(), CmpEnumVals);
775      EnumValsTy::iterator EIend = std::unique(EnumVals.begin(), EnumVals.end(), EqEnumVals);
776      // See which case values aren't in enum
777      EnumValsTy::const_iterator EI = EnumVals.begin();
778      for (CaseValsTy::const_iterator CI = CaseVals.begin(); CI != CaseVals.end(); CI++) {
779        while (EI != EIend && EI->first < CI->first)
780          EI++;
781        if (EI == EIend || EI->first > CI->first)
782            Diag(CI->second->getLHS()->getExprLoc(), diag::not_in_enum) << ED->getDeclName();
783      }
784      // See which of case ranges aren't in enum
785      EI = EnumVals.begin();
786      for (CaseRangesTy::const_iterator RI = CaseRanges.begin(); RI != CaseRanges.end() && EI != EIend; RI++) {
787        while (EI != EIend && EI->first < RI->first)
788          EI++;
789
790        if (EI == EIend || EI->first != RI->first) {
791          Diag(RI->second->getLHS()->getExprLoc(), diag::not_in_enum) << ED->getDeclName();
792        }
793
794        llvm::APSInt Hi = RI->second->getRHS()->EvaluateAsInt(Context);
795        while (EI != EIend && EI->first < Hi)
796          EI++;
797        if (EI == EIend || EI->first != Hi)
798          Diag(RI->second->getRHS()->getExprLoc(), diag::not_in_enum) << ED->getDeclName();
799      }
800      //Check which enum vals aren't in switch
801      CaseValsTy::const_iterator CI = CaseVals.begin();
802      CaseRangesTy::const_iterator RI = CaseRanges.begin();
803      EI = EnumVals.begin();
804      for (; EI != EIend; EI++) {
805        //Drop unneeded case values
806        llvm::APSInt CIVal;
807        while (CI != CaseVals.end() && CI->first < EI->first)
808          CI++;
809
810        if (CI != CaseVals.end() && CI->first == EI->first)
811          continue;
812
813        //Drop unneeded case ranges
814        for (; RI != CaseRanges.end(); RI++) {
815          llvm::APSInt Hi = RI->second->getRHS()->EvaluateAsInt(Context);
816          if (EI->first <= Hi)
817            break;
818        }
819
820        if (RI == CaseRanges.end() || EI->first < RI->first)
821          Diag(CondExpr->getExprLoc(), diag::warn_missing_cases) << EI->second->getDeclName();
822      }
823    }
824  }
825
826  // FIXME: If the case list was broken is some way, we don't have a good system
827  // to patch it up.  Instead, just return the whole substmt as broken.
828  if (CaseListIsErroneous)
829    return StmtError();
830
831  Switch.release();
832  return Owned(SS);
833}
834
835Action::OwningStmtResult
836Sema::ActOnWhileStmt(SourceLocation WhileLoc, FullExprArg Cond,
837                     DeclPtrTy CondVar, StmtArg Body) {
838  OwningExprResult CondResult(Cond.release());
839
840  VarDecl *ConditionVar = 0;
841  if (CondVar.get()) {
842    ConditionVar = CondVar.getAs<VarDecl>();
843    CondResult = CheckConditionVariable(ConditionVar);
844    if (CondResult.isInvalid())
845      return StmtError();
846  }
847  Expr *ConditionExpr = CondResult.takeAs<Expr>();
848  if (!ConditionExpr)
849    return StmtError();
850
851  if (CheckBooleanCondition(ConditionExpr, WhileLoc)) {
852    CondResult = ConditionExpr;
853    return StmtError();
854  }
855
856  Stmt *bodyStmt = Body.takeAs<Stmt>();
857  DiagnoseUnusedExprResult(bodyStmt);
858
859  CondResult.release();
860  return Owned(new (Context) WhileStmt(ConditionVar, ConditionExpr, bodyStmt,
861                                       WhileLoc));
862}
863
864Action::OwningStmtResult
865Sema::ActOnDoStmt(SourceLocation DoLoc, StmtArg Body,
866                  SourceLocation WhileLoc, SourceLocation CondLParen,
867                  ExprArg Cond, SourceLocation CondRParen) {
868  Expr *condExpr = Cond.takeAs<Expr>();
869  assert(condExpr && "ActOnDoStmt(): missing expression");
870
871  if (CheckBooleanCondition(condExpr, DoLoc)) {
872    Cond = condExpr;
873    return StmtError();
874  }
875
876  Stmt *bodyStmt = Body.takeAs<Stmt>();
877  DiagnoseUnusedExprResult(bodyStmt);
878
879  Cond.release();
880  return Owned(new (Context) DoStmt(bodyStmt, condExpr, DoLoc,
881                                    WhileLoc, CondRParen));
882}
883
884Action::OwningStmtResult
885Sema::ActOnForStmt(SourceLocation ForLoc, SourceLocation LParenLoc,
886                   StmtArg first, FullExprArg second, DeclPtrTy secondVar,
887                   FullExprArg third,
888                   SourceLocation RParenLoc, StmtArg body) {
889  Stmt *First  = static_cast<Stmt*>(first.get());
890
891  if (!getLangOptions().CPlusPlus) {
892    if (DeclStmt *DS = dyn_cast_or_null<DeclStmt>(First)) {
893      // C99 6.8.5p3: The declaration part of a 'for' statement shall only
894      // declare identifiers for objects having storage class 'auto' or
895      // 'register'.
896      for (DeclStmt::decl_iterator DI=DS->decl_begin(), DE=DS->decl_end();
897           DI!=DE; ++DI) {
898        VarDecl *VD = dyn_cast<VarDecl>(*DI);
899        if (VD && VD->isBlockVarDecl() && !VD->hasLocalStorage())
900          VD = 0;
901        if (VD == 0)
902          Diag((*DI)->getLocation(), diag::err_non_variable_decl_in_for);
903        // FIXME: mark decl erroneous!
904      }
905    }
906  }
907
908  OwningExprResult SecondResult(second.release());
909  VarDecl *ConditionVar = 0;
910  if (secondVar.get()) {
911    ConditionVar = secondVar.getAs<VarDecl>();
912    SecondResult = CheckConditionVariable(ConditionVar);
913    if (SecondResult.isInvalid())
914      return StmtError();
915  }
916
917  Expr *Second = SecondResult.takeAs<Expr>();
918  if (Second && CheckBooleanCondition(Second, ForLoc)) {
919    SecondResult = Second;
920    return StmtError();
921  }
922
923  Expr *Third  = third.release().takeAs<Expr>();
924  Stmt *Body  = static_cast<Stmt*>(body.get());
925
926  DiagnoseUnusedExprResult(First);
927  DiagnoseUnusedExprResult(Third);
928  DiagnoseUnusedExprResult(Body);
929
930  first.release();
931  body.release();
932  return Owned(new (Context) ForStmt(First, Second, ConditionVar, Third, Body,
933                                     ForLoc, LParenLoc, RParenLoc));
934}
935
936Action::OwningStmtResult
937Sema::ActOnObjCForCollectionStmt(SourceLocation ForLoc,
938                                 SourceLocation LParenLoc,
939                                 StmtArg first, ExprArg second,
940                                 SourceLocation RParenLoc, StmtArg body) {
941  Stmt *First  = static_cast<Stmt*>(first.get());
942  Expr *Second = static_cast<Expr*>(second.get());
943  Stmt *Body  = static_cast<Stmt*>(body.get());
944  if (First) {
945    QualType FirstType;
946    if (DeclStmt *DS = dyn_cast<DeclStmt>(First)) {
947      if (!DS->isSingleDecl())
948        return StmtError(Diag((*DS->decl_begin())->getLocation(),
949                         diag::err_toomany_element_decls));
950
951      Decl *D = DS->getSingleDecl();
952      FirstType = cast<ValueDecl>(D)->getType();
953      // C99 6.8.5p3: The declaration part of a 'for' statement shall only
954      // declare identifiers for objects having storage class 'auto' or
955      // 'register'.
956      VarDecl *VD = cast<VarDecl>(D);
957      if (VD->isBlockVarDecl() && !VD->hasLocalStorage())
958        return StmtError(Diag(VD->getLocation(),
959                              diag::err_non_variable_decl_in_for));
960    } else {
961      if (cast<Expr>(First)->isLvalue(Context) != Expr::LV_Valid)
962        return StmtError(Diag(First->getLocStart(),
963                   diag::err_selector_element_not_lvalue)
964          << First->getSourceRange());
965
966      FirstType = static_cast<Expr*>(First)->getType();
967    }
968    if (!FirstType->isObjCObjectPointerType() &&
969        !FirstType->isBlockPointerType())
970        Diag(ForLoc, diag::err_selector_element_type)
971          << FirstType << First->getSourceRange();
972  }
973  if (Second) {
974    DefaultFunctionArrayLvalueConversion(Second);
975    QualType SecondType = Second->getType();
976    if (!SecondType->isObjCObjectPointerType())
977      Diag(ForLoc, diag::err_collection_expr_type)
978        << SecondType << Second->getSourceRange();
979  }
980  first.release();
981  second.release();
982  body.release();
983  return Owned(new (Context) ObjCForCollectionStmt(First, Second, Body,
984                                                   ForLoc, RParenLoc));
985}
986
987Action::OwningStmtResult
988Sema::ActOnGotoStmt(SourceLocation GotoLoc, SourceLocation LabelLoc,
989                    IdentifierInfo *LabelII) {
990  // Look up the record for this label identifier.
991  LabelStmt *&LabelDecl = getLabelMap()[LabelII];
992
993  // If we haven't seen this label yet, create a forward reference.
994  if (LabelDecl == 0)
995    LabelDecl = new (Context) LabelStmt(LabelLoc, LabelII, 0);
996
997  return Owned(new (Context) GotoStmt(LabelDecl, GotoLoc, LabelLoc));
998}
999
1000Action::OwningStmtResult
1001Sema::ActOnIndirectGotoStmt(SourceLocation GotoLoc, SourceLocation StarLoc,
1002                            ExprArg DestExp) {
1003  // Convert operand to void*
1004  Expr* E = DestExp.takeAs<Expr>();
1005  if (!E->isTypeDependent()) {
1006    QualType ETy = E->getType();
1007    QualType DestTy = Context.getPointerType(Context.VoidTy.withConst());
1008    AssignConvertType ConvTy =
1009      CheckSingleAssignmentConstraints(DestTy, E);
1010    if (DiagnoseAssignmentResult(ConvTy, StarLoc, DestTy, ETy, E, AA_Passing))
1011      return StmtError();
1012  }
1013  return Owned(new (Context) IndirectGotoStmt(GotoLoc, StarLoc, E));
1014}
1015
1016Action::OwningStmtResult
1017Sema::ActOnContinueStmt(SourceLocation ContinueLoc, Scope *CurScope) {
1018  Scope *S = CurScope->getContinueParent();
1019  if (!S) {
1020    // C99 6.8.6.2p1: A break shall appear only in or as a loop body.
1021    return StmtError(Diag(ContinueLoc, diag::err_continue_not_in_loop));
1022  }
1023
1024  return Owned(new (Context) ContinueStmt(ContinueLoc));
1025}
1026
1027Action::OwningStmtResult
1028Sema::ActOnBreakStmt(SourceLocation BreakLoc, Scope *CurScope) {
1029  Scope *S = CurScope->getBreakParent();
1030  if (!S) {
1031    // C99 6.8.6.3p1: A break shall appear only in or as a switch/loop body.
1032    return StmtError(Diag(BreakLoc, diag::err_break_not_in_loop_or_switch));
1033  }
1034
1035  return Owned(new (Context) BreakStmt(BreakLoc));
1036}
1037
1038/// ActOnBlockReturnStmt - Utility routine to figure out block's return type.
1039///
1040Action::OwningStmtResult
1041Sema::ActOnBlockReturnStmt(SourceLocation ReturnLoc, Expr *RetValExp) {
1042  // If this is the first return we've seen in the block, infer the type of
1043  // the block from it.
1044  BlockScopeInfo *CurBlock = getCurBlock();
1045  if (CurBlock->ReturnType.isNull()) {
1046    if (RetValExp) {
1047      // Don't call UsualUnaryConversions(), since we don't want to do
1048      // integer promotions here.
1049      DefaultFunctionArrayLvalueConversion(RetValExp);
1050      CurBlock->ReturnType = RetValExp->getType();
1051      if (BlockDeclRefExpr *CDRE = dyn_cast<BlockDeclRefExpr>(RetValExp)) {
1052        // We have to remove a 'const' added to copied-in variable which was
1053        // part of the implementation spec. and not the actual qualifier for
1054        // the variable.
1055        if (CDRE->isConstQualAdded())
1056           CurBlock->ReturnType.removeConst();
1057      }
1058    } else
1059      CurBlock->ReturnType = Context.VoidTy;
1060  }
1061  QualType FnRetType = CurBlock->ReturnType;
1062
1063  if (CurBlock->TheDecl->hasAttr<NoReturnAttr>()) {
1064    Diag(ReturnLoc, diag::err_noreturn_block_has_return_expr)
1065      << getCurFunctionOrMethodDecl()->getDeclName();
1066    return StmtError();
1067  }
1068
1069  // Otherwise, verify that this result type matches the previous one.  We are
1070  // pickier with blocks than for normal functions because we don't have GCC
1071  // compatibility to worry about here.
1072  if (CurBlock->ReturnType->isVoidType()) {
1073    if (RetValExp) {
1074      Diag(ReturnLoc, diag::err_return_block_has_expr);
1075      RetValExp->Destroy(Context);
1076      RetValExp = 0;
1077    }
1078    return Owned(new (Context) ReturnStmt(ReturnLoc, RetValExp));
1079  }
1080
1081  if (!RetValExp)
1082    return StmtError(Diag(ReturnLoc, diag::err_block_return_missing_expr));
1083
1084  if (!FnRetType->isDependentType() && !RetValExp->isTypeDependent()) {
1085    // we have a non-void block with an expression, continue checking
1086
1087    // C99 6.8.6.4p3(136): The return statement is not an assignment. The
1088    // overlap restriction of subclause 6.5.16.1 does not apply to the case of
1089    // function return.
1090
1091    // In C++ the return statement is handled via a copy initialization.
1092    // the C version of which boils down to CheckSingleAssignmentConstraints.
1093    OwningExprResult Res = PerformCopyInitialization(
1094                             InitializedEntity::InitializeResult(ReturnLoc,
1095                                                                 FnRetType),
1096                             SourceLocation(),
1097                             Owned(RetValExp));
1098    if (Res.isInvalid()) {
1099      // FIXME: Cleanup temporaries here, anyway?
1100      return StmtError();
1101    }
1102
1103    RetValExp = Res.takeAs<Expr>();
1104    if (RetValExp)
1105      CheckReturnStackAddr(RetValExp, FnRetType, ReturnLoc);
1106  }
1107
1108  return Owned(new (Context) ReturnStmt(ReturnLoc, RetValExp));
1109}
1110
1111/// IsReturnCopyElidable - Whether returning @p RetExpr from a function that
1112/// returns a @p RetType fulfills the criteria for copy elision (C++0x 12.8p15).
1113static bool IsReturnCopyElidable(ASTContext &Ctx, QualType RetType,
1114                                 Expr *RetExpr) {
1115  QualType ExprType = RetExpr->getType();
1116  // - in a return statement in a function with ...
1117  // ... a class return type ...
1118  if (!RetType->isRecordType())
1119    return false;
1120  // ... the same cv-unqualified type as the function return type ...
1121  if (!Ctx.hasSameUnqualifiedType(RetType, ExprType))
1122    return false;
1123  // ... the expression is the name of a non-volatile automatic object ...
1124  // We ignore parentheses here.
1125  // FIXME: Is this compliant?
1126  const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(RetExpr->IgnoreParens());
1127  if (!DR)
1128    return false;
1129  const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl());
1130  if (!VD)
1131    return false;
1132  return VD->hasLocalStorage() && !VD->getType()->isReferenceType()
1133    && !VD->getType().isVolatileQualified();
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  if (FnRetType->isVoidType()) {
1155    if (RetValExp && !RetValExp->isTypeDependent()) {
1156      // C99 6.8.6.4p1 (ext_ since GCC warns)
1157      unsigned D = diag::ext_return_has_expr;
1158      if (RetValExp->getType()->isVoidType())
1159        D = diag::ext_return_has_void_expr;
1160
1161      // return (some void expression); is legal in C++.
1162      if (D != diag::ext_return_has_void_expr ||
1163          !getLangOptions().CPlusPlus) {
1164        NamedDecl *CurDecl = getCurFunctionOrMethodDecl();
1165        Diag(ReturnLoc, D)
1166          << CurDecl->getDeclName() << isa<ObjCMethodDecl>(CurDecl)
1167          << RetValExp->getSourceRange();
1168      }
1169
1170      RetValExp = MaybeCreateCXXExprWithTemporaries(RetValExp);
1171    }
1172    return Owned(new (Context) ReturnStmt(ReturnLoc, RetValExp));
1173  }
1174
1175  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    return Owned(new (Context) ReturnStmt(ReturnLoc, (Expr*)0));
1185  }
1186
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    // C++0x 12.8p15: When certain criteria are met, an implementation is
1195    //   allowed to omit the copy construction of a class object, [...]
1196    //   - in a return statement in a function with a class return type, when
1197    //     the expression is the name of a non-volatile automatic object with
1198    //     the same cv-unqualified type as the function return type, the copy
1199    //     operation can be omitted [...]
1200    // C++0x 12.8p16: When the criteria for elision of a copy operation are met
1201    //   and the object to be copied is designated by an lvalue, overload
1202    //   resolution to select the constructor for the copy is first performed
1203    //   as if the object were designated by an rvalue.
1204    // Note that we only compute Elidable if we're in C++0x, since we don't
1205    // care otherwise.
1206    bool Elidable = getLangOptions().CPlusPlus0x ?
1207                      IsReturnCopyElidable(Context, FnRetType, RetValExp) :
1208                      false;
1209    // FIXME: Elidable
1210    (void)Elidable;
1211
1212    // In C++ the return statement is handled via a copy initialization.
1213    // the C version of which boils down to CheckSingleAssignmentConstraints.
1214    OwningExprResult Res = PerformCopyInitialization(
1215                             InitializedEntity::InitializeResult(ReturnLoc,
1216                                                                 FnRetType),
1217                             SourceLocation(),
1218                             Owned(RetValExp));
1219    if (Res.isInvalid()) {
1220      // FIXME: Cleanup temporaries here, anyway?
1221      return StmtError();
1222    }
1223
1224    RetValExp = Res.takeAs<Expr>();
1225    if (RetValExp)
1226      CheckReturnStackAddr(RetValExp, FnRetType, ReturnLoc);
1227  }
1228
1229  if (RetValExp)
1230    RetValExp = MaybeCreateCXXExprWithTemporaries(RetValExp);
1231  return Owned(new (Context) ReturnStmt(ReturnLoc, RetValExp));
1232}
1233
1234/// CheckAsmLValue - GNU C has an extremely ugly extension whereby they silently
1235/// ignore "noop" casts in places where an lvalue is required by an inline asm.
1236/// We emulate this behavior when -fheinous-gnu-extensions is specified, but
1237/// provide a strong guidance to not use it.
1238///
1239/// This method checks to see if the argument is an acceptable l-value and
1240/// returns false if it is a case we can handle.
1241static bool CheckAsmLValue(const Expr *E, Sema &S) {
1242  // Type dependent expressions will be checked during instantiation.
1243  if (E->isTypeDependent())
1244    return false;
1245
1246  if (E->isLvalue(S.Context) == Expr::LV_Valid)
1247    return false;  // Cool, this is an lvalue.
1248
1249  // Okay, this is not an lvalue, but perhaps it is the result of a cast that we
1250  // are supposed to allow.
1251  const Expr *E2 = E->IgnoreParenNoopCasts(S.Context);
1252  if (E != E2 && E2->isLvalue(S.Context) == Expr::LV_Valid) {
1253    if (!S.getLangOptions().HeinousExtensions)
1254      S.Diag(E2->getLocStart(), diag::err_invalid_asm_cast_lvalue)
1255        << E->getSourceRange();
1256    else
1257      S.Diag(E2->getLocStart(), diag::warn_invalid_asm_cast_lvalue)
1258        << E->getSourceRange();
1259    // Accept, even if we emitted an error diagnostic.
1260    return false;
1261  }
1262
1263  // None of the above, just randomly invalid non-lvalue.
1264  return true;
1265}
1266
1267
1268Sema::OwningStmtResult Sema::ActOnAsmStmt(SourceLocation AsmLoc,
1269                                          bool IsSimple,
1270                                          bool IsVolatile,
1271                                          unsigned NumOutputs,
1272                                          unsigned NumInputs,
1273                                          IdentifierInfo **Names,
1274                                          MultiExprArg constraints,
1275                                          MultiExprArg exprs,
1276                                          ExprArg asmString,
1277                                          MultiExprArg clobbers,
1278                                          SourceLocation RParenLoc,
1279                                          bool MSAsm) {
1280  unsigned NumClobbers = clobbers.size();
1281  StringLiteral **Constraints =
1282    reinterpret_cast<StringLiteral**>(constraints.get());
1283  Expr **Exprs = reinterpret_cast<Expr **>(exprs.get());
1284  StringLiteral *AsmString = cast<StringLiteral>((Expr *)asmString.get());
1285  StringLiteral **Clobbers = reinterpret_cast<StringLiteral**>(clobbers.get());
1286
1287  llvm::SmallVector<TargetInfo::ConstraintInfo, 4> OutputConstraintInfos;
1288
1289  // The parser verifies that there is a string literal here.
1290  if (AsmString->isWide())
1291    return StmtError(Diag(AsmString->getLocStart(),diag::err_asm_wide_character)
1292      << AsmString->getSourceRange());
1293
1294  for (unsigned i = 0; i != NumOutputs; i++) {
1295    StringLiteral *Literal = Constraints[i];
1296    if (Literal->isWide())
1297      return StmtError(Diag(Literal->getLocStart(),diag::err_asm_wide_character)
1298        << Literal->getSourceRange());
1299
1300    llvm::StringRef OutputName;
1301    if (Names[i])
1302      OutputName = Names[i]->getName();
1303
1304    TargetInfo::ConstraintInfo Info(Literal->getString(), OutputName);
1305    if (!Context.Target.validateOutputConstraint(Info))
1306      return StmtError(Diag(Literal->getLocStart(),
1307                            diag::err_asm_invalid_output_constraint)
1308                       << Info.getConstraintStr());
1309
1310    // Check that the output exprs are valid lvalues.
1311    Expr *OutputExpr = Exprs[i];
1312    if (CheckAsmLValue(OutputExpr, *this)) {
1313      return StmtError(Diag(OutputExpr->getLocStart(),
1314                  diag::err_asm_invalid_lvalue_in_output)
1315        << OutputExpr->getSourceRange());
1316    }
1317
1318    OutputConstraintInfos.push_back(Info);
1319  }
1320
1321  llvm::SmallVector<TargetInfo::ConstraintInfo, 4> InputConstraintInfos;
1322
1323  for (unsigned i = NumOutputs, e = NumOutputs + NumInputs; i != e; i++) {
1324    StringLiteral *Literal = Constraints[i];
1325    if (Literal->isWide())
1326      return StmtError(Diag(Literal->getLocStart(),diag::err_asm_wide_character)
1327        << Literal->getSourceRange());
1328
1329    llvm::StringRef InputName;
1330    if (Names[i])
1331      InputName = Names[i]->getName();
1332
1333    TargetInfo::ConstraintInfo Info(Literal->getString(), InputName);
1334    if (!Context.Target.validateInputConstraint(OutputConstraintInfos.data(),
1335                                                NumOutputs, Info)) {
1336      return StmtError(Diag(Literal->getLocStart(),
1337                            diag::err_asm_invalid_input_constraint)
1338                       << Info.getConstraintStr());
1339    }
1340
1341    Expr *InputExpr = Exprs[i];
1342
1343    // Only allow void types for memory constraints.
1344    if (Info.allowsMemory() && !Info.allowsRegister()) {
1345      if (CheckAsmLValue(InputExpr, *this))
1346        return StmtError(Diag(InputExpr->getLocStart(),
1347                              diag::err_asm_invalid_lvalue_in_input)
1348                         << Info.getConstraintStr()
1349                         << InputExpr->getSourceRange());
1350    }
1351
1352    if (Info.allowsRegister()) {
1353      if (InputExpr->getType()->isVoidType()) {
1354        return StmtError(Diag(InputExpr->getLocStart(),
1355                              diag::err_asm_invalid_type_in_input)
1356          << InputExpr->getType() << Info.getConstraintStr()
1357          << InputExpr->getSourceRange());
1358      }
1359    }
1360
1361    DefaultFunctionArrayLvalueConversion(Exprs[i]);
1362
1363    InputConstraintInfos.push_back(Info);
1364  }
1365
1366  // Check that the clobbers are valid.
1367  for (unsigned i = 0; i != NumClobbers; i++) {
1368    StringLiteral *Literal = Clobbers[i];
1369    if (Literal->isWide())
1370      return StmtError(Diag(Literal->getLocStart(),diag::err_asm_wide_character)
1371        << Literal->getSourceRange());
1372
1373    llvm::StringRef Clobber = Literal->getString();
1374
1375    if (!Context.Target.isValidGCCRegisterName(Clobber))
1376      return StmtError(Diag(Literal->getLocStart(),
1377                  diag::err_asm_unknown_register_name) << Clobber);
1378  }
1379
1380  constraints.release();
1381  exprs.release();
1382  asmString.release();
1383  clobbers.release();
1384  AsmStmt *NS =
1385    new (Context) AsmStmt(Context, AsmLoc, IsSimple, IsVolatile, MSAsm,
1386                          NumOutputs, NumInputs, Names, Constraints, Exprs,
1387                          AsmString, NumClobbers, Clobbers, RParenLoc);
1388  // Validate the asm string, ensuring it makes sense given the operands we
1389  // have.
1390  llvm::SmallVector<AsmStmt::AsmStringPiece, 8> Pieces;
1391  unsigned DiagOffs;
1392  if (unsigned DiagID = NS->AnalyzeAsmString(Pieces, Context, DiagOffs)) {
1393    Diag(getLocationOfStringLiteralByte(AsmString, DiagOffs), DiagID)
1394           << AsmString->getSourceRange();
1395    DeleteStmt(NS);
1396    return StmtError();
1397  }
1398
1399  // Validate tied input operands for type mismatches.
1400  for (unsigned i = 0, e = InputConstraintInfos.size(); i != e; ++i) {
1401    TargetInfo::ConstraintInfo &Info = InputConstraintInfos[i];
1402
1403    // If this is a tied constraint, verify that the output and input have
1404    // either exactly the same type, or that they are int/ptr operands with the
1405    // same size (int/long, int*/long, are ok etc).
1406    if (!Info.hasTiedOperand()) continue;
1407
1408    unsigned TiedTo = Info.getTiedOperand();
1409    Expr *OutputExpr = Exprs[TiedTo];
1410    Expr *InputExpr = Exprs[i+NumOutputs];
1411    QualType InTy = InputExpr->getType();
1412    QualType OutTy = OutputExpr->getType();
1413    if (Context.hasSameType(InTy, OutTy))
1414      continue;  // All types can be tied to themselves.
1415
1416    // Int/ptr operands have some special cases that we allow.
1417    if ((OutTy->isIntegerType() || OutTy->isPointerType()) &&
1418        (InTy->isIntegerType() || InTy->isPointerType())) {
1419
1420      // They are ok if they are the same size.  Tying void* to int is ok if
1421      // they are the same size, for example.  This also allows tying void* to
1422      // int*.
1423      uint64_t OutSize = Context.getTypeSize(OutTy);
1424      uint64_t InSize = Context.getTypeSize(InTy);
1425      if (OutSize == InSize)
1426        continue;
1427
1428      // If the smaller input/output operand is not mentioned in the asm string,
1429      // then we can promote it and the asm string won't notice.  Check this
1430      // case now.
1431      bool SmallerValueMentioned = false;
1432      for (unsigned p = 0, e = Pieces.size(); p != e; ++p) {
1433        AsmStmt::AsmStringPiece &Piece = Pieces[p];
1434        if (!Piece.isOperand()) continue;
1435
1436        // If this is a reference to the input and if the input was the smaller
1437        // one, then we have to reject this asm.
1438        if (Piece.getOperandNo() == i+NumOutputs) {
1439          if (InSize < OutSize) {
1440            SmallerValueMentioned = true;
1441            break;
1442          }
1443        }
1444
1445        // If this is a reference to the input and if the input was the smaller
1446        // one, then we have to reject this asm.
1447        if (Piece.getOperandNo() == TiedTo) {
1448          if (InSize > OutSize) {
1449            SmallerValueMentioned = true;
1450            break;
1451          }
1452        }
1453      }
1454
1455      // If the smaller value wasn't mentioned in the asm string, and if the
1456      // output was a register, just extend the shorter one to the size of the
1457      // larger one.
1458      if (!SmallerValueMentioned &&
1459          OutputConstraintInfos[TiedTo].allowsRegister())
1460        continue;
1461    }
1462
1463    Diag(InputExpr->getLocStart(),
1464         diag::err_asm_tying_incompatible_types)
1465      << InTy << OutTy << OutputExpr->getSourceRange()
1466      << InputExpr->getSourceRange();
1467    DeleteStmt(NS);
1468    return StmtError();
1469  }
1470
1471  return Owned(NS);
1472}
1473
1474Action::OwningStmtResult
1475Sema::ActOnObjCAtCatchStmt(SourceLocation AtLoc,
1476                           SourceLocation RParen, DeclPtrTy Parm,
1477                           StmtArg Body, StmtArg catchList) {
1478  Stmt *CatchList = catchList.takeAs<Stmt>();
1479  ParmVarDecl *PVD = cast_or_null<ParmVarDecl>(Parm.getAs<Decl>());
1480
1481  // PVD == 0 implies @catch(...).
1482  if (PVD) {
1483    // If we already know the decl is invalid, reject it.
1484    if (PVD->isInvalidDecl())
1485      return StmtError();
1486
1487    if (!PVD->getType()->isObjCObjectPointerType())
1488      return StmtError(Diag(PVD->getLocation(),
1489                       diag::err_catch_param_not_objc_type));
1490    if (PVD->getType()->isObjCQualifiedIdType())
1491      return StmtError(Diag(PVD->getLocation(),
1492                       diag::err_illegal_qualifiers_on_catch_parm));
1493  }
1494
1495  ObjCAtCatchStmt *CS = new (Context) ObjCAtCatchStmt(AtLoc, RParen,
1496    PVD, Body.takeAs<Stmt>(), CatchList);
1497  return Owned(CatchList ? CatchList : CS);
1498}
1499
1500Action::OwningStmtResult
1501Sema::ActOnObjCAtFinallyStmt(SourceLocation AtLoc, StmtArg Body) {
1502  return Owned(new (Context) ObjCAtFinallyStmt(AtLoc,
1503                                           static_cast<Stmt*>(Body.release())));
1504}
1505
1506Action::OwningStmtResult
1507Sema::ActOnObjCAtTryStmt(SourceLocation AtLoc,
1508                         StmtArg Try, StmtArg Catch, StmtArg Finally) {
1509  FunctionNeedsScopeChecking() = true;
1510  return Owned(new (Context) ObjCAtTryStmt(AtLoc, Try.takeAs<Stmt>(),
1511                                           Catch.takeAs<Stmt>(),
1512                                           Finally.takeAs<Stmt>()));
1513}
1514
1515Action::OwningStmtResult
1516Sema::ActOnObjCAtThrowStmt(SourceLocation AtLoc, ExprArg expr,Scope *CurScope) {
1517  Expr *ThrowExpr = expr.takeAs<Expr>();
1518  if (!ThrowExpr) {
1519    // @throw without an expression designates a rethrow (which much occur
1520    // in the context of an @catch clause).
1521    Scope *AtCatchParent = CurScope;
1522    while (AtCatchParent && !AtCatchParent->isAtCatchScope())
1523      AtCatchParent = AtCatchParent->getParent();
1524    if (!AtCatchParent)
1525      return StmtError(Diag(AtLoc, diag::error_rethrow_used_outside_catch));
1526  } else {
1527    QualType ThrowType = ThrowExpr->getType();
1528    // Make sure the expression type is an ObjC pointer or "void *".
1529    if (!ThrowType->isObjCObjectPointerType()) {
1530      const PointerType *PT = ThrowType->getAs<PointerType>();
1531      if (!PT || !PT->getPointeeType()->isVoidType())
1532        return StmtError(Diag(AtLoc, diag::error_objc_throw_expects_object)
1533                        << ThrowExpr->getType() << ThrowExpr->getSourceRange());
1534    }
1535  }
1536  return Owned(new (Context) ObjCAtThrowStmt(AtLoc, ThrowExpr));
1537}
1538
1539Action::OwningStmtResult
1540Sema::ActOnObjCAtSynchronizedStmt(SourceLocation AtLoc, ExprArg SynchExpr,
1541                                  StmtArg SynchBody) {
1542  FunctionNeedsScopeChecking() = true;
1543
1544  // Make sure the expression type is an ObjC pointer or "void *".
1545  Expr *SyncExpr = static_cast<Expr*>(SynchExpr.get());
1546  if (!SyncExpr->getType()->isObjCObjectPointerType()) {
1547    const PointerType *PT = SyncExpr->getType()->getAs<PointerType>();
1548    if (!PT || !PT->getPointeeType()->isVoidType())
1549      return StmtError(Diag(AtLoc, diag::error_objc_synchronized_expects_object)
1550                       << SyncExpr->getType() << SyncExpr->getSourceRange());
1551  }
1552
1553  return Owned(new (Context) ObjCAtSynchronizedStmt(AtLoc,
1554                                                    SynchExpr.takeAs<Stmt>(),
1555                                                    SynchBody.takeAs<Stmt>()));
1556}
1557
1558/// ActOnCXXCatchBlock - Takes an exception declaration and a handler block
1559/// and creates a proper catch handler from them.
1560Action::OwningStmtResult
1561Sema::ActOnCXXCatchBlock(SourceLocation CatchLoc, DeclPtrTy ExDecl,
1562                         StmtArg HandlerBlock) {
1563  // There's nothing to test that ActOnExceptionDecl didn't already test.
1564  return Owned(new (Context) CXXCatchStmt(CatchLoc,
1565                                  cast_or_null<VarDecl>(ExDecl.getAs<Decl>()),
1566                                          HandlerBlock.takeAs<Stmt>()));
1567}
1568
1569class TypeWithHandler {
1570  QualType t;
1571  CXXCatchStmt *stmt;
1572public:
1573  TypeWithHandler(const QualType &type, CXXCatchStmt *statement)
1574  : t(type), stmt(statement) {}
1575
1576  // An arbitrary order is fine as long as it places identical
1577  // types next to each other.
1578  bool operator<(const TypeWithHandler &y) const {
1579    if (t.getAsOpaquePtr() < y.t.getAsOpaquePtr())
1580      return true;
1581    if (t.getAsOpaquePtr() > y.t.getAsOpaquePtr())
1582      return false;
1583    else
1584      return getTypeSpecStartLoc() < y.getTypeSpecStartLoc();
1585  }
1586
1587  bool operator==(const TypeWithHandler& other) const {
1588    return t == other.t;
1589  }
1590
1591  QualType getQualType() const { return t; }
1592  CXXCatchStmt *getCatchStmt() const { return stmt; }
1593  SourceLocation getTypeSpecStartLoc() const {
1594    return stmt->getExceptionDecl()->getTypeSpecStartLoc();
1595  }
1596};
1597
1598/// ActOnCXXTryBlock - Takes a try compound-statement and a number of
1599/// handlers and creates a try statement from them.
1600Action::OwningStmtResult
1601Sema::ActOnCXXTryBlock(SourceLocation TryLoc, StmtArg TryBlock,
1602                       MultiStmtArg RawHandlers) {
1603  unsigned NumHandlers = RawHandlers.size();
1604  assert(NumHandlers > 0 &&
1605         "The parser shouldn't call this if there are no handlers.");
1606  Stmt **Handlers = reinterpret_cast<Stmt**>(RawHandlers.get());
1607
1608  llvm::SmallVector<TypeWithHandler, 8> TypesWithHandlers;
1609
1610  for (unsigned i = 0; i < NumHandlers; ++i) {
1611    CXXCatchStmt *Handler = llvm::cast<CXXCatchStmt>(Handlers[i]);
1612    if (!Handler->getExceptionDecl()) {
1613      if (i < NumHandlers - 1)
1614        return StmtError(Diag(Handler->getLocStart(),
1615                              diag::err_early_catch_all));
1616
1617      continue;
1618    }
1619
1620    const QualType CaughtType = Handler->getCaughtType();
1621    const QualType CanonicalCaughtType = Context.getCanonicalType(CaughtType);
1622    TypesWithHandlers.push_back(TypeWithHandler(CanonicalCaughtType, Handler));
1623  }
1624
1625  // Detect handlers for the same type as an earlier one.
1626  if (NumHandlers > 1) {
1627    llvm::array_pod_sort(TypesWithHandlers.begin(), TypesWithHandlers.end());
1628
1629    TypeWithHandler prev = TypesWithHandlers[0];
1630    for (unsigned i = 1; i < TypesWithHandlers.size(); ++i) {
1631      TypeWithHandler curr = TypesWithHandlers[i];
1632
1633      if (curr == prev) {
1634        Diag(curr.getTypeSpecStartLoc(),
1635             diag::warn_exception_caught_by_earlier_handler)
1636          << curr.getCatchStmt()->getCaughtType().getAsString();
1637        Diag(prev.getTypeSpecStartLoc(),
1638             diag::note_previous_exception_handler)
1639          << prev.getCatchStmt()->getCaughtType().getAsString();
1640      }
1641
1642      prev = curr;
1643    }
1644  }
1645
1646  // FIXME: We should detect handlers that cannot catch anything because an
1647  // earlier handler catches a superclass. Need to find a method that is not
1648  // quadratic for this.
1649  // Neither of these are explicitly forbidden, but every compiler detects them
1650  // and warns.
1651
1652  FunctionNeedsScopeChecking() = true;
1653  RawHandlers.release();
1654  return Owned(CXXTryStmt::Create(Context, TryLoc,
1655                                  static_cast<Stmt*>(TryBlock.release()),
1656                                  Handlers, NumHandlers));
1657}
1658