SemaStmt.cpp revision 30ab37122300a5f6664b8ae2d0b43b4396eb6bcb 
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  // Ignore expressions that have void type.
80  if (E->getType()->isVoidType())
81    return;
82
83  SourceLocation Loc;
84  SourceRange R1, R2;
85  if (!E->isUnusedResultAWarning(Loc, R1, R2, Context))
86    return;
87
88  // Okay, we have an unused result.  Depending on what the base expression is,
89  // we might want to make a more specific diagnostic.  Check for one of these
90  // cases now.
91  unsigned DiagID = diag::warn_unused_expr;
92  E = E->IgnoreParens();
93  if (isa<ObjCImplicitSetterGetterRefExpr>(E))
94    DiagID = diag::warn_unused_property_expr;
95
96  if (const CXXExprWithTemporaries *Temps = dyn_cast<CXXExprWithTemporaries>(E))
97    E = Temps->getSubExpr();
98  if (const CXXZeroInitValueExpr *Zero = dyn_cast<CXXZeroInitValueExpr>(E)) {
99    if (const RecordType *RecordT = Zero->getType()->getAs<RecordType>())
100      if (CXXRecordDecl *RecordD = dyn_cast<CXXRecordDecl>(RecordT->getDecl()))
101        if (!RecordD->hasTrivialDestructor())
102          return;
103  }
104
105  if (const CallExpr *CE = dyn_cast<CallExpr>(E)) {
106    // If the callee has attribute pure, const, or warn_unused_result, warn with
107    // a more specific message to make it clear what is happening.
108    if (const Decl *FD = CE->getCalleeDecl()) {
109      if (FD->getAttr<WarnUnusedResultAttr>()) {
110        Diag(Loc, diag::warn_unused_call) << R1 << R2 << "warn_unused_result";
111        return;
112      }
113      if (FD->getAttr<PureAttr>()) {
114        Diag(Loc, diag::warn_unused_call) << R1 << R2 << "pure";
115        return;
116      }
117      if (FD->getAttr<ConstAttr>()) {
118        Diag(Loc, diag::warn_unused_call) << R1 << R2 << "const";
119        return;
120      }
121    }
122  }
123
124  Diag(Loc, DiagID) << R1 << R2;
125}
126
127Action::OwningStmtResult
128Sema::ActOnCompoundStmt(SourceLocation L, SourceLocation R,
129                        MultiStmtArg elts, bool isStmtExpr) {
130  unsigned NumElts = elts.size();
131  Stmt **Elts = reinterpret_cast<Stmt**>(elts.release());
132  // If we're in C89 mode, check that we don't have any decls after stmts.  If
133  // so, emit an extension diagnostic.
134  if (!getLangOptions().C99 && !getLangOptions().CPlusPlus) {
135    // Note that __extension__ can be around a decl.
136    unsigned i = 0;
137    // Skip over all declarations.
138    for (; i != NumElts && isa<DeclStmt>(Elts[i]); ++i)
139      /*empty*/;
140
141    // We found the end of the list or a statement.  Scan for another declstmt.
142    for (; i != NumElts && !isa<DeclStmt>(Elts[i]); ++i)
143      /*empty*/;
144
145    if (i != NumElts) {
146      Decl *D = *cast<DeclStmt>(Elts[i])->decl_begin();
147      Diag(D->getLocation(), diag::ext_mixed_decls_code);
148    }
149  }
150  // Warn about unused expressions in statements.
151  for (unsigned i = 0; i != NumElts; ++i) {
152    // Ignore statements that are last in a statement expression.
153    if (isStmtExpr && i == NumElts - 1)
154      continue;
155
156    DiagnoseUnusedExprResult(Elts[i]);
157  }
158
159  return Owned(new (Context) CompoundStmt(Context, Elts, NumElts, L, R));
160}
161
162Action::OwningStmtResult
163Sema::ActOnCaseStmt(SourceLocation CaseLoc, ExprArg lhsval,
164                    SourceLocation DotDotDotLoc, ExprArg rhsval,
165                    SourceLocation ColonLoc) {
166  assert((lhsval.get() != 0) && "missing expression in case statement");
167
168  // C99 6.8.4.2p3: The expression shall be an integer constant.
169  // However, GCC allows any evaluatable integer expression.
170  Expr *LHSVal = static_cast<Expr*>(lhsval.get());
171  if (!LHSVal->isTypeDependent() && !LHSVal->isValueDependent() &&
172      VerifyIntegerConstantExpression(LHSVal))
173    return StmtError();
174
175  // GCC extension: The expression shall be an integer constant.
176
177  Expr *RHSVal = static_cast<Expr*>(rhsval.get());
178  if (RHSVal && !RHSVal->isTypeDependent() && !RHSVal->isValueDependent() &&
179      VerifyIntegerConstantExpression(RHSVal)) {
180    RHSVal = 0;  // Recover by just forgetting about it.
181    rhsval = 0;
182  }
183
184  if (getSwitchStack().empty()) {
185    Diag(CaseLoc, diag::err_case_not_in_switch);
186    return StmtError();
187  }
188
189  // Only now release the smart pointers.
190  lhsval.release();
191  rhsval.release();
192  CaseStmt *CS = new (Context) CaseStmt(LHSVal, RHSVal, CaseLoc, DotDotDotLoc,
193                                        ColonLoc);
194  getSwitchStack().back()->addSwitchCase(CS);
195  return Owned(CS);
196}
197
198/// ActOnCaseStmtBody - This installs a statement as the body of a case.
199void Sema::ActOnCaseStmtBody(StmtTy *caseStmt, StmtArg subStmt) {
200  CaseStmt *CS = static_cast<CaseStmt*>(caseStmt);
201  Stmt *SubStmt = subStmt.takeAs<Stmt>();
202  CS->setSubStmt(SubStmt);
203}
204
205Action::OwningStmtResult
206Sema::ActOnDefaultStmt(SourceLocation DefaultLoc, SourceLocation ColonLoc,
207                       StmtArg subStmt, Scope *CurScope) {
208  Stmt *SubStmt = subStmt.takeAs<Stmt>();
209
210  if (getSwitchStack().empty()) {
211    Diag(DefaultLoc, diag::err_default_not_in_switch);
212    return Owned(SubStmt);
213  }
214
215  DefaultStmt *DS = new (Context) DefaultStmt(DefaultLoc, ColonLoc, SubStmt);
216  getSwitchStack().back()->addSwitchCase(DS);
217  return Owned(DS);
218}
219
220Action::OwningStmtResult
221Sema::ActOnLabelStmt(SourceLocation IdentLoc, IdentifierInfo *II,
222                     SourceLocation ColonLoc, StmtArg subStmt) {
223  Stmt *SubStmt = subStmt.takeAs<Stmt>();
224  // Look up the record for this label identifier.
225  LabelStmt *&LabelDecl = getLabelMap()[II];
226
227  // If not forward referenced or defined already, just create a new LabelStmt.
228  if (LabelDecl == 0)
229    return Owned(LabelDecl = new (Context) LabelStmt(IdentLoc, II, SubStmt));
230
231  assert(LabelDecl->getID() == II && "Label mismatch!");
232
233  // Otherwise, this label was either forward reference or multiply defined.  If
234  // multiply defined, reject it now.
235  if (LabelDecl->getSubStmt()) {
236    Diag(IdentLoc, diag::err_redefinition_of_label) << LabelDecl->getID();
237    Diag(LabelDecl->getIdentLoc(), diag::note_previous_definition);
238    return Owned(SubStmt);
239  }
240
241  // Otherwise, this label was forward declared, and we just found its real
242  // definition.  Fill in the forward definition and return it.
243  LabelDecl->setIdentLoc(IdentLoc);
244  LabelDecl->setSubStmt(SubStmt);
245  return Owned(LabelDecl);
246}
247
248Action::OwningStmtResult
249Sema::ActOnIfStmt(SourceLocation IfLoc, FullExprArg CondVal, DeclPtrTy CondVar,
250                  StmtArg ThenVal, SourceLocation ElseLoc,
251                  StmtArg ElseVal) {
252  OwningExprResult CondResult(CondVal.release());
253
254  VarDecl *ConditionVar = 0;
255  if (CondVar.get()) {
256    ConditionVar = CondVar.getAs<VarDecl>();
257    CondResult = CheckConditionVariable(ConditionVar);
258    if (CondResult.isInvalid())
259      return StmtError();
260  }
261  Expr *ConditionExpr = CondResult.takeAs<Expr>();
262  if (!ConditionExpr)
263    return StmtError();
264
265  if (CheckBooleanCondition(ConditionExpr, IfLoc)) {
266    CondResult = ConditionExpr;
267    return StmtError();
268  }
269
270  Stmt *thenStmt = ThenVal.takeAs<Stmt>();
271  DiagnoseUnusedExprResult(thenStmt);
272
273  // Warn if the if block has a null body without an else value.
274  // this helps prevent bugs due to typos, such as
275  // if (condition);
276  //   do_stuff();
277  if (!ElseVal.get()) {
278    if (NullStmt* stmt = dyn_cast<NullStmt>(thenStmt))
279      Diag(stmt->getSemiLoc(), diag::warn_empty_if_body);
280  }
281
282  Stmt *elseStmt = ElseVal.takeAs<Stmt>();
283  DiagnoseUnusedExprResult(elseStmt);
284
285  CondResult.release();
286  return Owned(new (Context) IfStmt(IfLoc, ConditionVar, ConditionExpr,
287                                    thenStmt, ElseLoc, elseStmt));
288}
289
290Action::OwningStmtResult
291Sema::ActOnStartOfSwitchStmt(FullExprArg cond, DeclPtrTy CondVar) {
292  OwningExprResult CondResult(cond.release());
293
294  VarDecl *ConditionVar = 0;
295  if (CondVar.get()) {
296    ConditionVar = CondVar.getAs<VarDecl>();
297    CondResult = CheckConditionVariable(ConditionVar);
298    if (CondResult.isInvalid())
299      return StmtError();
300  }
301  SwitchStmt *SS = new (Context) SwitchStmt(ConditionVar,
302                                            CondResult.takeAs<Expr>());
303  getSwitchStack().push_back(SS);
304  return Owned(SS);
305}
306
307/// ConvertIntegerToTypeWarnOnOverflow - Convert the specified APInt to have
308/// the specified width and sign.  If an overflow occurs, detect it and emit
309/// the specified diagnostic.
310void Sema::ConvertIntegerToTypeWarnOnOverflow(llvm::APSInt &Val,
311                                              unsigned NewWidth, bool NewSign,
312                                              SourceLocation Loc,
313                                              unsigned DiagID) {
314  // Perform a conversion to the promoted condition type if needed.
315  if (NewWidth > Val.getBitWidth()) {
316    // If this is an extension, just do it.
317    llvm::APSInt OldVal(Val);
318    Val.extend(NewWidth);
319
320    // If the input was signed and negative and the output is unsigned,
321    // warn.
322    if (!NewSign && OldVal.isSigned() && OldVal.isNegative())
323      Diag(Loc, DiagID) << OldVal.toString(10) << Val.toString(10);
324
325    Val.setIsSigned(NewSign);
326  } else if (NewWidth < Val.getBitWidth()) {
327    // If this is a truncation, check for overflow.
328    llvm::APSInt ConvVal(Val);
329    ConvVal.trunc(NewWidth);
330    ConvVal.setIsSigned(NewSign);
331    ConvVal.extend(Val.getBitWidth());
332    ConvVal.setIsSigned(Val.isSigned());
333    if (ConvVal != Val)
334      Diag(Loc, DiagID) << Val.toString(10) << ConvVal.toString(10);
335
336    // Regardless of whether a diagnostic was emitted, really do the
337    // truncation.
338    Val.trunc(NewWidth);
339    Val.setIsSigned(NewSign);
340  } else if (NewSign != Val.isSigned()) {
341    // Convert the sign to match the sign of the condition.  This can cause
342    // overflow as well: unsigned(INTMIN)
343    llvm::APSInt OldVal(Val);
344    Val.setIsSigned(NewSign);
345
346    if (Val.isNegative())  // Sign bit changes meaning.
347      Diag(Loc, DiagID) << OldVal.toString(10) << Val.toString(10);
348  }
349}
350
351namespace {
352  struct CaseCompareFunctor {
353    bool operator()(const std::pair<llvm::APSInt, CaseStmt*> &LHS,
354                    const llvm::APSInt &RHS) {
355      return LHS.first < RHS;
356    }
357    bool operator()(const std::pair<llvm::APSInt, CaseStmt*> &LHS,
358                    const std::pair<llvm::APSInt, CaseStmt*> &RHS) {
359      return LHS.first < RHS.first;
360    }
361    bool operator()(const llvm::APSInt &LHS,
362                    const std::pair<llvm::APSInt, CaseStmt*> &RHS) {
363      return LHS < RHS.first;
364    }
365  };
366}
367
368/// CmpCaseVals - Comparison predicate for sorting case values.
369///
370static bool CmpCaseVals(const std::pair<llvm::APSInt, CaseStmt*>& lhs,
371                        const std::pair<llvm::APSInt, CaseStmt*>& rhs) {
372  if (lhs.first < rhs.first)
373    return true;
374
375  if (lhs.first == rhs.first &&
376      lhs.second->getCaseLoc().getRawEncoding()
377       < rhs.second->getCaseLoc().getRawEncoding())
378    return true;
379  return false;
380}
381
382/// CmpEnumVals - Comparison predicate for sorting enumeration values.
383///
384static bool CmpEnumVals(const std::pair<llvm::APSInt, EnumConstantDecl*>& lhs,
385                        const std::pair<llvm::APSInt, EnumConstantDecl*>& rhs)
386{
387  return lhs.first < rhs.first;
388}
389
390/// EqEnumVals - Comparison preficate for uniqing enumeration values.
391///
392static bool EqEnumVals(const std::pair<llvm::APSInt, EnumConstantDecl*>& lhs,
393                       const std::pair<llvm::APSInt, EnumConstantDecl*>& rhs)
394{
395  return lhs.first == rhs.first;
396}
397
398/// GetTypeBeforeIntegralPromotion - Returns the pre-promotion type of
399/// potentially integral-promoted expression @p expr.
400static QualType GetTypeBeforeIntegralPromotion(const Expr* expr) {
401  const ImplicitCastExpr *ImplicitCast =
402      dyn_cast_or_null<ImplicitCastExpr>(expr);
403  if (ImplicitCast != NULL) {
404    const Expr *ExprBeforePromotion = ImplicitCast->getSubExpr();
405    QualType TypeBeforePromotion = ExprBeforePromotion->getType();
406    if (TypeBeforePromotion->isIntegralType()) {
407      return TypeBeforePromotion;
408    }
409  }
410  return expr->getType();
411}
412
413/// \brief Check (and possibly convert) the condition in a switch
414/// statement in C++.
415static bool CheckCXXSwitchCondition(Sema &S, SourceLocation SwitchLoc,
416                                    Expr *&CondExpr) {
417  if (CondExpr->isTypeDependent())
418    return false;
419
420  QualType CondType = CondExpr->getType();
421
422  // C++ 6.4.2.p2:
423  // The condition shall be of integral type, enumeration type, or of a class
424  // type for which a single conversion function to integral or enumeration
425  // type exists (12.3). If the condition is of class type, the condition is
426  // converted by calling that conversion function, and the result of the
427  // conversion is used in place of the original condition for the remainder
428  // of this section. Integral promotions are performed.
429
430  // Make sure that the condition expression has a complete type,
431  // otherwise we'll never find any conversions.
432  if (S.RequireCompleteType(SwitchLoc, CondType,
433                            PDiag(diag::err_switch_incomplete_class_type)
434                              << CondExpr->getSourceRange()))
435    return true;
436
437  llvm::SmallVector<CXXConversionDecl *, 4> ViableConversions;
438  llvm::SmallVector<CXXConversionDecl *, 4> ExplicitConversions;
439  if (const RecordType *RecordTy = CondType->getAs<RecordType>()) {
440    const UnresolvedSetImpl *Conversions
441      = cast<CXXRecordDecl>(RecordTy->getDecl())
442                                             ->getVisibleConversionFunctions();
443    for (UnresolvedSetImpl::iterator I = Conversions->begin(),
444           E = Conversions->end(); I != E; ++I) {
445      if (CXXConversionDecl *Conversion = dyn_cast<CXXConversionDecl>(*I))
446        if (Conversion->getConversionType().getNonReferenceType()
447              ->isIntegralType()) {
448          if (Conversion->isExplicit())
449            ExplicitConversions.push_back(Conversion);
450          else
451          ViableConversions.push_back(Conversion);
452        }
453    }
454
455    switch (ViableConversions.size()) {
456    case 0:
457      if (ExplicitConversions.size() == 1) {
458        // The user probably meant to invoke the given explicit
459        // conversion; use it.
460        QualType ConvTy
461          = ExplicitConversions[0]->getConversionType()
462                        .getNonReferenceType();
463        std::string TypeStr;
464        ConvTy.getAsStringInternal(TypeStr, S.Context.PrintingPolicy);
465
466        S.Diag(SwitchLoc, diag::err_switch_explicit_conversion)
467          << CondType << ConvTy << CondExpr->getSourceRange()
468          << CodeModificationHint::CreateInsertion(CondExpr->getLocStart(),
469                                         "static_cast<" + TypeStr + ">(")
470          << CodeModificationHint::CreateInsertion(
471                            S.PP.getLocForEndOfToken(CondExpr->getLocEnd()),
472                               ")");
473        S.Diag(ExplicitConversions[0]->getLocation(),
474             diag::note_switch_conversion)
475          << ConvTy->isEnumeralType() << ConvTy;
476
477        // If we aren't in a SFINAE context, build a call to the
478        // explicit conversion function.
479        if (S.isSFINAEContext())
480          return true;
481
482        CondExpr = S.BuildCXXMemberCallExpr(CondExpr, ExplicitConversions[0]);
483      }
484
485      // We'll complain below about a non-integral condition type.
486      break;
487
488    case 1:
489      // Apply this conversion.
490      CondExpr = S.BuildCXXMemberCallExpr(CondExpr, ViableConversions[0]);
491      break;
492
493    default:
494      S.Diag(SwitchLoc, diag::err_switch_multiple_conversions)
495        << CondType << CondExpr->getSourceRange();
496      for (unsigned I = 0, N = ViableConversions.size(); I != N; ++I) {
497        QualType ConvTy
498          = ViableConversions[I]->getConversionType().getNonReferenceType();
499        S.Diag(ViableConversions[I]->getLocation(),
500             diag::note_switch_conversion)
501          << ConvTy->isEnumeralType() << ConvTy;
502      }
503      return true;
504    }
505  }
506
507  return false;
508}
509
510/// ActOnSwitchBodyError - This is called if there is an error parsing the
511/// body of the switch stmt instead of ActOnFinishSwitchStmt.
512void Sema::ActOnSwitchBodyError(SourceLocation SwitchLoc, StmtArg Switch,
513                                StmtArg Body) {
514  // Keep the switch stack balanced.
515  assert(getSwitchStack().back() == (SwitchStmt*)Switch.get() &&
516         "switch stack missing push/pop!");
517  getSwitchStack().pop_back();
518}
519
520Action::OwningStmtResult
521Sema::ActOnFinishSwitchStmt(SourceLocation SwitchLoc, StmtArg Switch,
522                            StmtArg Body) {
523  Stmt *BodyStmt = Body.takeAs<Stmt>();
524
525  SwitchStmt *SS = getSwitchStack().back();
526  assert(SS == (SwitchStmt*)Switch.get() && "switch stack missing push/pop!");
527
528  SS->setBody(BodyStmt, SwitchLoc);
529  getSwitchStack().pop_back();
530
531  if (SS->getCond() == 0) {
532    SS->Destroy(Context);
533    return StmtError();
534  }
535
536  Expr *CondExpr = SS->getCond();
537  QualType CondTypeBeforePromotion =
538      GetTypeBeforeIntegralPromotion(CondExpr);
539
540  if (getLangOptions().CPlusPlus &&
541      CheckCXXSwitchCondition(*this, SwitchLoc, CondExpr))
542    return StmtError();
543
544  // C99 6.8.4.2p5 - Integer promotions are performed on the controlling expr.
545  UsualUnaryConversions(CondExpr);
546  QualType CondType = CondExpr->getType();
547  SS->setCond(CondExpr);
548
549  // C++ 6.4.2.p2:
550  // Integral promotions are performed (on the switch condition).
551  //
552  // A case value unrepresentable by the original switch condition
553  // type (before the promotion) doesn't make sense, even when it can
554  // be represented by the promoted type.  Therefore we need to find
555  // the pre-promotion type of the switch condition.
556  if (!CondExpr->isTypeDependent()) {
557    if (!CondType->isIntegerType()) { // C99 6.8.4.2p1
558      Diag(SwitchLoc, diag::err_typecheck_statement_requires_integer)
559          << CondType << CondExpr->getSourceRange();
560      return StmtError();
561    }
562
563    if (CondTypeBeforePromotion->isBooleanType()) {
564      // switch(bool_expr) {...} is often a programmer error, e.g.
565      //   switch(n && mask) { ... }  // Doh - should be "n & mask".
566      // One can always use an if statement instead of switch(bool_expr).
567      Diag(SwitchLoc, diag::warn_bool_switch_condition)
568          << CondExpr->getSourceRange();
569    }
570  }
571
572  // Get the bitwidth of the switched-on value before promotions.  We must
573  // convert the integer case values to this width before comparison.
574  bool HasDependentValue
575    = CondExpr->isTypeDependent() || CondExpr->isValueDependent();
576  unsigned CondWidth
577    = HasDependentValue? 0
578      : static_cast<unsigned>(Context.getTypeSize(CondTypeBeforePromotion));
579  bool CondIsSigned = CondTypeBeforePromotion->isSignedIntegerType();
580
581  // Accumulate all of the case values in a vector so that we can sort them
582  // and detect duplicates.  This vector contains the APInt for the case after
583  // it has been converted to the condition type.
584  typedef llvm::SmallVector<std::pair<llvm::APSInt, CaseStmt*>, 64> CaseValsTy;
585  CaseValsTy CaseVals;
586
587  // Keep track of any GNU case ranges we see.  The APSInt is the low value.
588  typedef std::vector<std::pair<llvm::APSInt, CaseStmt*> > CaseRangesTy;
589  CaseRangesTy CaseRanges;
590
591  DefaultStmt *TheDefaultStmt = 0;
592
593  bool CaseListIsErroneous = false;
594
595  for (SwitchCase *SC = SS->getSwitchCaseList(); SC && !HasDependentValue;
596       SC = SC->getNextSwitchCase()) {
597
598    if (DefaultStmt *DS = dyn_cast<DefaultStmt>(SC)) {
599      if (TheDefaultStmt) {
600        Diag(DS->getDefaultLoc(), diag::err_multiple_default_labels_defined);
601        Diag(TheDefaultStmt->getDefaultLoc(), diag::note_duplicate_case_prev);
602
603        // FIXME: Remove the default statement from the switch block so that
604        // we'll return a valid AST.  This requires recursing down the AST and
605        // finding it, not something we are set up to do right now.  For now,
606        // just lop the entire switch stmt out of the AST.
607        CaseListIsErroneous = true;
608      }
609      TheDefaultStmt = DS;
610
611    } else {
612      CaseStmt *CS = cast<CaseStmt>(SC);
613
614      // We already verified that the expression has a i-c-e value (C99
615      // 6.8.4.2p3) - get that value now.
616      Expr *Lo = CS->getLHS();
617
618      if (Lo->isTypeDependent() || Lo->isValueDependent()) {
619        HasDependentValue = true;
620        break;
621      }
622
623      llvm::APSInt LoVal = Lo->EvaluateAsInt(Context);
624
625      // Convert the value to the same width/sign as the condition.
626      ConvertIntegerToTypeWarnOnOverflow(LoVal, CondWidth, CondIsSigned,
627                                         CS->getLHS()->getLocStart(),
628                                         diag::warn_case_value_overflow);
629
630      // If the LHS is not the same type as the condition, insert an implicit
631      // cast.
632      ImpCastExprToType(Lo, CondType, CastExpr::CK_IntegralCast);
633      CS->setLHS(Lo);
634
635      // If this is a case range, remember it in CaseRanges, otherwise CaseVals.
636      if (CS->getRHS()) {
637        if (CS->getRHS()->isTypeDependent() ||
638            CS->getRHS()->isValueDependent()) {
639          HasDependentValue = true;
640          break;
641        }
642        CaseRanges.push_back(std::make_pair(LoVal, CS));
643      } else
644        CaseVals.push_back(std::make_pair(LoVal, CS));
645    }
646  }
647
648  if (!HasDependentValue) {
649    // Sort all the scalar case values so we can easily detect duplicates.
650    std::stable_sort(CaseVals.begin(), CaseVals.end(), CmpCaseVals);
651
652    if (!CaseVals.empty()) {
653      for (unsigned i = 0, e = CaseVals.size()-1; i != e; ++i) {
654        if (CaseVals[i].first == CaseVals[i+1].first) {
655          // If we have a duplicate, report it.
656          Diag(CaseVals[i+1].second->getLHS()->getLocStart(),
657               diag::err_duplicate_case) << CaseVals[i].first.toString(10);
658          Diag(CaseVals[i].second->getLHS()->getLocStart(),
659               diag::note_duplicate_case_prev);
660          // FIXME: We really want to remove the bogus case stmt from the
661          // substmt, but we have no way to do this right now.
662          CaseListIsErroneous = true;
663        }
664      }
665    }
666
667    // Detect duplicate case ranges, which usually don't exist at all in
668    // the first place.
669    if (!CaseRanges.empty()) {
670      // Sort all the case ranges by their low value so we can easily detect
671      // overlaps between ranges.
672      std::stable_sort(CaseRanges.begin(), CaseRanges.end());
673
674      // Scan the ranges, computing the high values and removing empty ranges.
675      std::vector<llvm::APSInt> HiVals;
676      for (unsigned i = 0, e = CaseRanges.size(); i != e; ++i) {
677        CaseStmt *CR = CaseRanges[i].second;
678        Expr *Hi = CR->getRHS();
679        llvm::APSInt HiVal = Hi->EvaluateAsInt(Context);
680
681        // Convert the value to the same width/sign as the condition.
682        ConvertIntegerToTypeWarnOnOverflow(HiVal, CondWidth, CondIsSigned,
683                                           CR->getRHS()->getLocStart(),
684                                           diag::warn_case_value_overflow);
685
686        // If the LHS is not the same type as the condition, insert an implicit
687        // cast.
688        ImpCastExprToType(Hi, CondType, CastExpr::CK_IntegralCast);
689        CR->setRHS(Hi);
690
691        // If the low value is bigger than the high value, the case is empty.
692        if (CaseRanges[i].first > HiVal) {
693          Diag(CR->getLHS()->getLocStart(), diag::warn_case_empty_range)
694            << SourceRange(CR->getLHS()->getLocStart(),
695                           CR->getRHS()->getLocEnd());
696          CaseRanges.erase(CaseRanges.begin()+i);
697          --i, --e;
698          continue;
699        }
700        HiVals.push_back(HiVal);
701      }
702
703      // Rescan the ranges, looking for overlap with singleton values and other
704      // ranges.  Since the range list is sorted, we only need to compare case
705      // ranges with their neighbors.
706      for (unsigned i = 0, e = CaseRanges.size(); i != e; ++i) {
707        llvm::APSInt &CRLo = CaseRanges[i].first;
708        llvm::APSInt &CRHi = HiVals[i];
709        CaseStmt *CR = CaseRanges[i].second;
710
711        // Check to see whether the case range overlaps with any
712        // singleton cases.
713        CaseStmt *OverlapStmt = 0;
714        llvm::APSInt OverlapVal(32);
715
716        // Find the smallest value >= the lower bound.  If I is in the
717        // case range, then we have overlap.
718        CaseValsTy::iterator I = std::lower_bound(CaseVals.begin(),
719                                                  CaseVals.end(), CRLo,
720                                                  CaseCompareFunctor());
721        if (I != CaseVals.end() && I->first < CRHi) {
722          OverlapVal  = I->first;   // Found overlap with scalar.
723          OverlapStmt = I->second;
724        }
725
726        // Find the smallest value bigger than the upper bound.
727        I = std::upper_bound(I, CaseVals.end(), CRHi, CaseCompareFunctor());
728        if (I != CaseVals.begin() && (I-1)->first >= CRLo) {
729          OverlapVal  = (I-1)->first;      // Found overlap with scalar.
730          OverlapStmt = (I-1)->second;
731        }
732
733        // Check to see if this case stmt overlaps with the subsequent
734        // case range.
735        if (i && CRLo <= HiVals[i-1]) {
736          OverlapVal  = HiVals[i-1];       // Found overlap with range.
737          OverlapStmt = CaseRanges[i-1].second;
738        }
739
740        if (OverlapStmt) {
741          // If we have a duplicate, report it.
742          Diag(CR->getLHS()->getLocStart(), diag::err_duplicate_case)
743            << OverlapVal.toString(10);
744          Diag(OverlapStmt->getLHS()->getLocStart(),
745               diag::note_duplicate_case_prev);
746          // FIXME: We really want to remove the bogus case stmt from the
747          // substmt, but we have no way to do this right now.
748          CaseListIsErroneous = true;
749        }
750      }
751    }
752
753    // Check to see if switch is over an Enum and handles all of its
754    // values
755    const EnumType* ET = CondTypeBeforePromotion->getAs<EnumType>();
756    // If switch has default case, then ignore it.
757    if (!CaseListIsErroneous && !TheDefaultStmt && ET) {
758      const EnumDecl *ED = ET->getDecl();
759      typedef llvm::SmallVector<std::pair<llvm::APSInt, EnumConstantDecl*>, 64> EnumValsTy;
760      EnumValsTy EnumVals;
761
762      // Gather all enum values, set their type and sort them, allowing easier comparison
763      // with CaseVals.
764      for (EnumDecl::enumerator_iterator EDI = ED->enumerator_begin(); EDI != ED->enumerator_end(); EDI++) {
765        llvm::APSInt Val = (*EDI)->getInitVal();
766        if(Val.getBitWidth() < CondWidth)
767          Val.extend(CondWidth);
768        Val.setIsSigned(CondIsSigned);
769        EnumVals.push_back(std::make_pair(Val, (*EDI)));
770      }
771      std::stable_sort(EnumVals.begin(), EnumVals.end(), CmpEnumVals);
772      EnumValsTy::iterator EIend = std::unique(EnumVals.begin(), EnumVals.end(), EqEnumVals);
773      // See which case values aren't in enum
774      EnumValsTy::const_iterator EI = EnumVals.begin();
775      for (CaseValsTy::const_iterator CI = CaseVals.begin(); CI != CaseVals.end(); CI++) {
776        while (EI != EIend && EI->first < CI->first)
777          EI++;
778        if (EI == EIend || EI->first > CI->first)
779            Diag(CI->second->getLHS()->getExprLoc(), diag::not_in_enum) << ED->getDeclName();
780      }
781      // See which of case ranges aren't in enum
782      EI = EnumVals.begin();
783      for (CaseRangesTy::const_iterator RI = CaseRanges.begin(); RI != CaseRanges.end() && EI != EIend; RI++) {
784        while (EI != EIend && EI->first < RI->first)
785          EI++;
786
787        if (EI == EIend || EI->first != RI->first) {
788          Diag(RI->second->getLHS()->getExprLoc(), diag::not_in_enum) << ED->getDeclName();
789        }
790
791        llvm::APSInt Hi = RI->second->getRHS()->EvaluateAsInt(Context);
792        while (EI != EIend && EI->first < Hi)
793          EI++;
794        if (EI == EIend || EI->first != Hi)
795          Diag(RI->second->getRHS()->getExprLoc(), diag::not_in_enum) << ED->getDeclName();
796      }
797      //Check which enum vals aren't in switch
798      CaseValsTy::const_iterator CI = CaseVals.begin();
799      CaseRangesTy::const_iterator RI = CaseRanges.begin();
800      EI = EnumVals.begin();
801      for (; EI != EIend; EI++) {
802        //Drop unneeded case values
803        llvm::APSInt CIVal;
804        while (CI != CaseVals.end() && CI->first < EI->first)
805          CI++;
806
807        if (CI != CaseVals.end() && CI->first == EI->first)
808          continue;
809
810        //Drop unneeded case ranges
811        for (; RI != CaseRanges.end(); RI++) {
812          llvm::APSInt Hi = RI->second->getRHS()->EvaluateAsInt(Context);
813          if (EI->first <= Hi)
814            break;
815        }
816
817        if (RI == CaseRanges.end() || EI->first < RI->first)
818          Diag(CondExpr->getExprLoc(), diag::warn_missing_cases) << EI->second->getDeclName();
819      }
820    }
821  }
822
823  // FIXME: If the case list was broken is some way, we don't have a good system
824  // to patch it up.  Instead, just return the whole substmt as broken.
825  if (CaseListIsErroneous)
826    return StmtError();
827
828  Switch.release();
829  return Owned(SS);
830}
831
832Action::OwningStmtResult
833Sema::ActOnWhileStmt(SourceLocation WhileLoc, FullExprArg Cond,
834                     DeclPtrTy CondVar, StmtArg Body) {
835  OwningExprResult CondResult(Cond.release());
836
837  VarDecl *ConditionVar = 0;
838  if (CondVar.get()) {
839    ConditionVar = CondVar.getAs<VarDecl>();
840    CondResult = CheckConditionVariable(ConditionVar);
841    if (CondResult.isInvalid())
842      return StmtError();
843  }
844  Expr *ConditionExpr = CondResult.takeAs<Expr>();
845  if (!ConditionExpr)
846    return StmtError();
847
848  if (CheckBooleanCondition(ConditionExpr, WhileLoc)) {
849    CondResult = ConditionExpr;
850    return StmtError();
851  }
852
853  Stmt *bodyStmt = Body.takeAs<Stmt>();
854  DiagnoseUnusedExprResult(bodyStmt);
855
856  CondResult.release();
857  return Owned(new (Context) WhileStmt(ConditionVar, ConditionExpr, bodyStmt,
858                                       WhileLoc));
859}
860
861Action::OwningStmtResult
862Sema::ActOnDoStmt(SourceLocation DoLoc, StmtArg Body,
863                  SourceLocation WhileLoc, SourceLocation CondLParen,
864                  ExprArg Cond, SourceLocation CondRParen) {
865  Expr *condExpr = Cond.takeAs<Expr>();
866  assert(condExpr && "ActOnDoStmt(): missing expression");
867
868  if (CheckBooleanCondition(condExpr, DoLoc)) {
869    Cond = condExpr;
870    return StmtError();
871  }
872
873  Stmt *bodyStmt = Body.takeAs<Stmt>();
874  DiagnoseUnusedExprResult(bodyStmt);
875
876  Cond.release();
877  return Owned(new (Context) DoStmt(bodyStmt, condExpr, DoLoc,
878                                    WhileLoc, CondRParen));
879}
880
881Action::OwningStmtResult
882Sema::ActOnForStmt(SourceLocation ForLoc, SourceLocation LParenLoc,
883                   StmtArg first, FullExprArg second, DeclPtrTy secondVar,
884                   FullExprArg third,
885                   SourceLocation RParenLoc, StmtArg body) {
886  Stmt *First  = static_cast<Stmt*>(first.get());
887
888  if (!getLangOptions().CPlusPlus) {
889    if (DeclStmt *DS = dyn_cast_or_null<DeclStmt>(First)) {
890      // C99 6.8.5p3: The declaration part of a 'for' statement shall only
891      // declare identifiers for objects having storage class 'auto' or
892      // 'register'.
893      for (DeclStmt::decl_iterator DI=DS->decl_begin(), DE=DS->decl_end();
894           DI!=DE; ++DI) {
895        VarDecl *VD = dyn_cast<VarDecl>(*DI);
896        if (VD && VD->isBlockVarDecl() && !VD->hasLocalStorage())
897          VD = 0;
898        if (VD == 0)
899          Diag((*DI)->getLocation(), diag::err_non_variable_decl_in_for);
900        // FIXME: mark decl erroneous!
901      }
902    }
903  }
904
905  OwningExprResult SecondResult(second.release());
906  VarDecl *ConditionVar = 0;
907  if (secondVar.get()) {
908    ConditionVar = secondVar.getAs<VarDecl>();
909    SecondResult = CheckConditionVariable(ConditionVar);
910    if (SecondResult.isInvalid())
911      return StmtError();
912  }
913
914  Expr *Second = SecondResult.takeAs<Expr>();
915  if (Second && CheckBooleanCondition(Second, ForLoc)) {
916    SecondResult = Second;
917    return StmtError();
918  }
919
920  Expr *Third  = third.release().takeAs<Expr>();
921  Stmt *Body  = static_cast<Stmt*>(body.get());
922
923  DiagnoseUnusedExprResult(First);
924  DiagnoseUnusedExprResult(Third);
925  DiagnoseUnusedExprResult(Body);
926
927  first.release();
928  body.release();
929  return Owned(new (Context) ForStmt(First, Second, ConditionVar, Third, Body,
930                                     ForLoc, LParenLoc, RParenLoc));
931}
932
933Action::OwningStmtResult
934Sema::ActOnObjCForCollectionStmt(SourceLocation ForLoc,
935                                 SourceLocation LParenLoc,
936                                 StmtArg first, ExprArg second,
937                                 SourceLocation RParenLoc, StmtArg body) {
938  Stmt *First  = static_cast<Stmt*>(first.get());
939  Expr *Second = static_cast<Expr*>(second.get());
940  Stmt *Body  = static_cast<Stmt*>(body.get());
941  if (First) {
942    QualType FirstType;
943    if (DeclStmt *DS = dyn_cast<DeclStmt>(First)) {
944      if (!DS->isSingleDecl())
945        return StmtError(Diag((*DS->decl_begin())->getLocation(),
946                         diag::err_toomany_element_decls));
947
948      Decl *D = DS->getSingleDecl();
949      FirstType = cast<ValueDecl>(D)->getType();
950      // C99 6.8.5p3: The declaration part of a 'for' statement shall only
951      // declare identifiers for objects having storage class 'auto' or
952      // 'register'.
953      VarDecl *VD = cast<VarDecl>(D);
954      if (VD->isBlockVarDecl() && !VD->hasLocalStorage())
955        return StmtError(Diag(VD->getLocation(),
956                              diag::err_non_variable_decl_in_for));
957    } else {
958      if (cast<Expr>(First)->isLvalue(Context) != Expr::LV_Valid)
959        return StmtError(Diag(First->getLocStart(),
960                   diag::err_selector_element_not_lvalue)
961          << First->getSourceRange());
962
963      FirstType = static_cast<Expr*>(First)->getType();
964    }
965    if (!FirstType->isObjCObjectPointerType() &&
966        !FirstType->isBlockPointerType())
967        Diag(ForLoc, diag::err_selector_element_type)
968          << FirstType << First->getSourceRange();
969  }
970  if (Second) {
971    DefaultFunctionArrayLvalueConversion(Second);
972    QualType SecondType = Second->getType();
973    if (!SecondType->isObjCObjectPointerType())
974      Diag(ForLoc, diag::err_collection_expr_type)
975        << SecondType << Second->getSourceRange();
976  }
977  first.release();
978  second.release();
979  body.release();
980  return Owned(new (Context) ObjCForCollectionStmt(First, Second, Body,
981                                                   ForLoc, RParenLoc));
982}
983
984Action::OwningStmtResult
985Sema::ActOnGotoStmt(SourceLocation GotoLoc, SourceLocation LabelLoc,
986                    IdentifierInfo *LabelII) {
987  // Look up the record for this label identifier.
988  LabelStmt *&LabelDecl = getLabelMap()[LabelII];
989
990  // If we haven't seen this label yet, create a forward reference.
991  if (LabelDecl == 0)
992    LabelDecl = new (Context) LabelStmt(LabelLoc, LabelII, 0);
993
994  return Owned(new (Context) GotoStmt(LabelDecl, GotoLoc, LabelLoc));
995}
996
997Action::OwningStmtResult
998Sema::ActOnIndirectGotoStmt(SourceLocation GotoLoc, SourceLocation StarLoc,
999                            ExprArg DestExp) {
1000  // Convert operand to void*
1001  Expr* E = DestExp.takeAs<Expr>();
1002  if (!E->isTypeDependent()) {
1003    QualType ETy = E->getType();
1004    QualType DestTy = Context.getPointerType(Context.VoidTy.withConst());
1005    AssignConvertType ConvTy =
1006      CheckSingleAssignmentConstraints(DestTy, E);
1007    if (DiagnoseAssignmentResult(ConvTy, StarLoc, DestTy, ETy, E, AA_Passing))
1008      return StmtError();
1009  }
1010  return Owned(new (Context) IndirectGotoStmt(GotoLoc, StarLoc, E));
1011}
1012
1013Action::OwningStmtResult
1014Sema::ActOnContinueStmt(SourceLocation ContinueLoc, Scope *CurScope) {
1015  Scope *S = CurScope->getContinueParent();
1016  if (!S) {
1017    // C99 6.8.6.2p1: A break shall appear only in or as a loop body.
1018    return StmtError(Diag(ContinueLoc, diag::err_continue_not_in_loop));
1019  }
1020
1021  return Owned(new (Context) ContinueStmt(ContinueLoc));
1022}
1023
1024Action::OwningStmtResult
1025Sema::ActOnBreakStmt(SourceLocation BreakLoc, Scope *CurScope) {
1026  Scope *S = CurScope->getBreakParent();
1027  if (!S) {
1028    // C99 6.8.6.3p1: A break shall appear only in or as a switch/loop body.
1029    return StmtError(Diag(BreakLoc, diag::err_break_not_in_loop_or_switch));
1030  }
1031
1032  return Owned(new (Context) BreakStmt(BreakLoc));
1033}
1034
1035/// ActOnBlockReturnStmt - Utility routine to figure out block's return type.
1036///
1037Action::OwningStmtResult
1038Sema::ActOnBlockReturnStmt(SourceLocation ReturnLoc, Expr *RetValExp) {
1039  // If this is the first return we've seen in the block, infer the type of
1040  // the block from it.
1041  if (CurBlock->ReturnType.isNull()) {
1042    if (RetValExp) {
1043      // Don't call UsualUnaryConversions(), since we don't want to do
1044      // integer promotions here.
1045      DefaultFunctionArrayLvalueConversion(RetValExp);
1046      CurBlock->ReturnType = RetValExp->getType();
1047      if (BlockDeclRefExpr *CDRE = dyn_cast<BlockDeclRefExpr>(RetValExp)) {
1048        // We have to remove a 'const' added to copied-in variable which was
1049        // part of the implementation spec. and not the actual qualifier for
1050        // the variable.
1051        if (CDRE->isConstQualAdded())
1052           CurBlock->ReturnType.removeConst();
1053      }
1054    } else
1055      CurBlock->ReturnType = Context.VoidTy;
1056  }
1057  QualType FnRetType = CurBlock->ReturnType;
1058
1059  if (CurBlock->TheDecl->hasAttr<NoReturnAttr>()) {
1060    Diag(ReturnLoc, diag::err_noreturn_block_has_return_expr)
1061      << getCurFunctionOrMethodDecl()->getDeclName();
1062    return StmtError();
1063  }
1064
1065  // Otherwise, verify that this result type matches the previous one.  We are
1066  // pickier with blocks than for normal functions because we don't have GCC
1067  // compatibility to worry about here.
1068  if (CurBlock->ReturnType->isVoidType()) {
1069    if (RetValExp) {
1070      Diag(ReturnLoc, diag::err_return_block_has_expr);
1071      RetValExp->Destroy(Context);
1072      RetValExp = 0;
1073    }
1074    return Owned(new (Context) ReturnStmt(ReturnLoc, RetValExp));
1075  }
1076
1077  if (!RetValExp)
1078    return StmtError(Diag(ReturnLoc, diag::err_block_return_missing_expr));
1079
1080  if (!FnRetType->isDependentType() && !RetValExp->isTypeDependent()) {
1081    // we have a non-void block with an expression, continue checking
1082
1083    // C99 6.8.6.4p3(136): The return statement is not an assignment. The
1084    // overlap restriction of subclause 6.5.16.1 does not apply to the case of
1085    // function return.
1086
1087    // In C++ the return statement is handled via a copy initialization.
1088    // the C version of which boils down to CheckSingleAssignmentConstraints.
1089    OwningExprResult Res = PerformCopyInitialization(
1090                             InitializedEntity::InitializeResult(ReturnLoc,
1091                                                                 FnRetType),
1092                             SourceLocation(),
1093                             Owned(RetValExp));
1094    if (Res.isInvalid()) {
1095      // FIXME: Cleanup temporaries here, anyway?
1096      return StmtError();
1097    }
1098
1099    RetValExp = Res.takeAs<Expr>();
1100    if (RetValExp)
1101      CheckReturnStackAddr(RetValExp, FnRetType, ReturnLoc);
1102  }
1103
1104  return Owned(new (Context) ReturnStmt(ReturnLoc, RetValExp));
1105}
1106
1107/// IsReturnCopyElidable - Whether returning @p RetExpr from a function that
1108/// returns a @p RetType fulfills the criteria for copy elision (C++0x 12.8p15).
1109static bool IsReturnCopyElidable(ASTContext &Ctx, QualType RetType,
1110                                 Expr *RetExpr) {
1111  QualType ExprType = RetExpr->getType();
1112  // - in a return statement in a function with ...
1113  // ... a class return type ...
1114  if (!RetType->isRecordType())
1115    return false;
1116  // ... the same cv-unqualified type as the function return type ...
1117  if (!Ctx.hasSameUnqualifiedType(RetType, ExprType))
1118    return false;
1119  // ... the expression is the name of a non-volatile automatic object ...
1120  // We ignore parentheses here.
1121  // FIXME: Is this compliant?
1122  const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(RetExpr->IgnoreParens());
1123  if (!DR)
1124    return false;
1125  const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl());
1126  if (!VD)
1127    return false;
1128  return VD->hasLocalStorage() && !VD->getType()->isReferenceType()
1129    && !VD->getType().isVolatileQualified();
1130}
1131
1132Action::OwningStmtResult
1133Sema::ActOnReturnStmt(SourceLocation ReturnLoc, ExprArg rex) {
1134  Expr *RetValExp = rex.takeAs<Expr>();
1135  if (CurBlock)
1136    return ActOnBlockReturnStmt(ReturnLoc, RetValExp);
1137
1138  QualType FnRetType;
1139  if (const FunctionDecl *FD = getCurFunctionDecl()) {
1140    FnRetType = FD->getResultType();
1141    if (FD->hasAttr<NoReturnAttr>() ||
1142        FD->getType()->getAs<FunctionType>()->getNoReturnAttr())
1143      Diag(ReturnLoc, diag::warn_noreturn_function_has_return_expr)
1144        << getCurFunctionOrMethodDecl()->getDeclName();
1145  } else if (ObjCMethodDecl *MD = getCurMethodDecl())
1146    FnRetType = MD->getResultType();
1147  else // If we don't have a function/method context, bail.
1148    return StmtError();
1149
1150  if (FnRetType->isVoidType()) {
1151    if (RetValExp && !RetValExp->isTypeDependent()) {
1152      // C99 6.8.6.4p1 (ext_ since GCC warns)
1153      unsigned D = diag::ext_return_has_expr;
1154      if (RetValExp->getType()->isVoidType())
1155        D = diag::ext_return_has_void_expr;
1156
1157      // return (some void expression); is legal in C++.
1158      if (D != diag::ext_return_has_void_expr ||
1159          !getLangOptions().CPlusPlus) {
1160        NamedDecl *CurDecl = getCurFunctionOrMethodDecl();
1161        Diag(ReturnLoc, D)
1162          << CurDecl->getDeclName() << isa<ObjCMethodDecl>(CurDecl)
1163          << RetValExp->getSourceRange();
1164      }
1165
1166      RetValExp = MaybeCreateCXXExprWithTemporaries(RetValExp);
1167    }
1168    return Owned(new (Context) ReturnStmt(ReturnLoc, RetValExp));
1169  }
1170
1171  if (!RetValExp && !FnRetType->isDependentType()) {
1172    unsigned DiagID = diag::warn_return_missing_expr;  // C90 6.6.6.4p4
1173    // C99 6.8.6.4p1 (ext_ since GCC warns)
1174    if (getLangOptions().C99) DiagID = diag::ext_return_missing_expr;
1175
1176    if (FunctionDecl *FD = getCurFunctionDecl())
1177      Diag(ReturnLoc, DiagID) << FD->getIdentifier() << 0/*fn*/;
1178    else
1179      Diag(ReturnLoc, DiagID) << getCurMethodDecl()->getDeclName() << 1/*meth*/;
1180    return Owned(new (Context) ReturnStmt(ReturnLoc, (Expr*)0));
1181  }
1182
1183  if (!FnRetType->isDependentType() && !RetValExp->isTypeDependent()) {
1184    // we have a non-void function with an expression, continue checking
1185
1186    // C99 6.8.6.4p3(136): The return statement is not an assignment. The
1187    // overlap restriction of subclause 6.5.16.1 does not apply to the case of
1188    // function return.
1189
1190    // C++0x 12.8p15: When certain criteria are met, an implementation is
1191    //   allowed to omit the copy construction of a class object, [...]
1192    //   - in a return statement in a function with a class return type, when
1193    //     the expression is the name of a non-volatile automatic object with
1194    //     the same cv-unqualified type as the function return type, the copy
1195    //     operation can be omitted [...]
1196    // C++0x 12.8p16: When the criteria for elision of a copy operation are met
1197    //   and the object to be copied is designated by an lvalue, overload
1198    //   resolution to select the constructor for the copy is first performed
1199    //   as if the object were designated by an rvalue.
1200    // Note that we only compute Elidable if we're in C++0x, since we don't
1201    // care otherwise.
1202    bool Elidable = getLangOptions().CPlusPlus0x ?
1203                      IsReturnCopyElidable(Context, FnRetType, RetValExp) :
1204                      false;
1205    // FIXME: Elidable
1206    (void)Elidable;
1207
1208    // In C++ the return statement is handled via a copy initialization.
1209    // the C version of which boils down to CheckSingleAssignmentConstraints.
1210    OwningExprResult Res = PerformCopyInitialization(
1211                             InitializedEntity::InitializeResult(ReturnLoc,
1212                                                                 FnRetType),
1213                             SourceLocation(),
1214                             Owned(RetValExp));
1215    if (Res.isInvalid()) {
1216      // FIXME: Cleanup temporaries here, anyway?
1217      return StmtError();
1218    }
1219
1220    RetValExp = Res.takeAs<Expr>();
1221    if (RetValExp)
1222      CheckReturnStackAddr(RetValExp, FnRetType, ReturnLoc);
1223  }
1224
1225  if (RetValExp)
1226    RetValExp = MaybeCreateCXXExprWithTemporaries(RetValExp);
1227  return Owned(new (Context) ReturnStmt(ReturnLoc, RetValExp));
1228}
1229
1230/// CheckAsmLValue - GNU C has an extremely ugly extension whereby they silently
1231/// ignore "noop" casts in places where an lvalue is required by an inline asm.
1232/// We emulate this behavior when -fheinous-gnu-extensions is specified, but
1233/// provide a strong guidance to not use it.
1234///
1235/// This method checks to see if the argument is an acceptable l-value and
1236/// returns false if it is a case we can handle.
1237static bool CheckAsmLValue(const Expr *E, Sema &S) {
1238  // Type dependent expressions will be checked during instantiation.
1239  if (E->isTypeDependent())
1240    return false;
1241
1242  if (E->isLvalue(S.Context) == Expr::LV_Valid)
1243    return false;  // Cool, this is an lvalue.
1244
1245  // Okay, this is not an lvalue, but perhaps it is the result of a cast that we
1246  // are supposed to allow.
1247  const Expr *E2 = E->IgnoreParenNoopCasts(S.Context);
1248  if (E != E2 && E2->isLvalue(S.Context) == Expr::LV_Valid) {
1249    if (!S.getLangOptions().HeinousExtensions)
1250      S.Diag(E2->getLocStart(), diag::err_invalid_asm_cast_lvalue)
1251        << E->getSourceRange();
1252    else
1253      S.Diag(E2->getLocStart(), diag::warn_invalid_asm_cast_lvalue)
1254        << E->getSourceRange();
1255    // Accept, even if we emitted an error diagnostic.
1256    return false;
1257  }
1258
1259  // None of the above, just randomly invalid non-lvalue.
1260  return true;
1261}
1262
1263
1264Sema::OwningStmtResult Sema::ActOnAsmStmt(SourceLocation AsmLoc,
1265                                          bool IsSimple,
1266                                          bool IsVolatile,
1267                                          unsigned NumOutputs,
1268                                          unsigned NumInputs,
1269                                          IdentifierInfo **Names,
1270                                          MultiExprArg constraints,
1271                                          MultiExprArg exprs,
1272                                          ExprArg asmString,
1273                                          MultiExprArg clobbers,
1274                                          SourceLocation RParenLoc,
1275                                          bool MSAsm) {
1276  unsigned NumClobbers = clobbers.size();
1277  StringLiteral **Constraints =
1278    reinterpret_cast<StringLiteral**>(constraints.get());
1279  Expr **Exprs = reinterpret_cast<Expr **>(exprs.get());
1280  StringLiteral *AsmString = cast<StringLiteral>((Expr *)asmString.get());
1281  StringLiteral **Clobbers = reinterpret_cast<StringLiteral**>(clobbers.get());
1282
1283  llvm::SmallVector<TargetInfo::ConstraintInfo, 4> OutputConstraintInfos;
1284
1285  // The parser verifies that there is a string literal here.
1286  if (AsmString->isWide())
1287    return StmtError(Diag(AsmString->getLocStart(),diag::err_asm_wide_character)
1288      << AsmString->getSourceRange());
1289
1290  for (unsigned i = 0; i != NumOutputs; i++) {
1291    StringLiteral *Literal = Constraints[i];
1292    if (Literal->isWide())
1293      return StmtError(Diag(Literal->getLocStart(),diag::err_asm_wide_character)
1294        << Literal->getSourceRange());
1295
1296    llvm::StringRef OutputName;
1297    if (Names[i])
1298      OutputName = Names[i]->getName();
1299
1300    TargetInfo::ConstraintInfo Info(Literal->getString(), OutputName);
1301    if (!Context.Target.validateOutputConstraint(Info))
1302      return StmtError(Diag(Literal->getLocStart(),
1303                            diag::err_asm_invalid_output_constraint)
1304                       << Info.getConstraintStr());
1305
1306    // Check that the output exprs are valid lvalues.
1307    Expr *OutputExpr = Exprs[i];
1308    if (CheckAsmLValue(OutputExpr, *this)) {
1309      return StmtError(Diag(OutputExpr->getLocStart(),
1310                  diag::err_asm_invalid_lvalue_in_output)
1311        << OutputExpr->getSourceRange());
1312    }
1313
1314    OutputConstraintInfos.push_back(Info);
1315  }
1316
1317  llvm::SmallVector<TargetInfo::ConstraintInfo, 4> InputConstraintInfos;
1318
1319  for (unsigned i = NumOutputs, e = NumOutputs + NumInputs; i != e; i++) {
1320    StringLiteral *Literal = Constraints[i];
1321    if (Literal->isWide())
1322      return StmtError(Diag(Literal->getLocStart(),diag::err_asm_wide_character)
1323        << Literal->getSourceRange());
1324
1325    llvm::StringRef InputName;
1326    if (Names[i])
1327      InputName = Names[i]->getName();
1328
1329    TargetInfo::ConstraintInfo Info(Literal->getString(), InputName);
1330    if (!Context.Target.validateInputConstraint(OutputConstraintInfos.data(),
1331                                                NumOutputs, Info)) {
1332      return StmtError(Diag(Literal->getLocStart(),
1333                            diag::err_asm_invalid_input_constraint)
1334                       << Info.getConstraintStr());
1335    }
1336
1337    Expr *InputExpr = Exprs[i];
1338
1339    // Only allow void types for memory constraints.
1340    if (Info.allowsMemory() && !Info.allowsRegister()) {
1341      if (CheckAsmLValue(InputExpr, *this))
1342        return StmtError(Diag(InputExpr->getLocStart(),
1343                              diag::err_asm_invalid_lvalue_in_input)
1344                         << Info.getConstraintStr()
1345                         << InputExpr->getSourceRange());
1346    }
1347
1348    if (Info.allowsRegister()) {
1349      if (InputExpr->getType()->isVoidType()) {
1350        return StmtError(Diag(InputExpr->getLocStart(),
1351                              diag::err_asm_invalid_type_in_input)
1352          << InputExpr->getType() << Info.getConstraintStr()
1353          << InputExpr->getSourceRange());
1354      }
1355    }
1356
1357    DefaultFunctionArrayLvalueConversion(Exprs[i]);
1358
1359    InputConstraintInfos.push_back(Info);
1360  }
1361
1362  // Check that the clobbers are valid.
1363  for (unsigned i = 0; i != NumClobbers; i++) {
1364    StringLiteral *Literal = Clobbers[i];
1365    if (Literal->isWide())
1366      return StmtError(Diag(Literal->getLocStart(),diag::err_asm_wide_character)
1367        << Literal->getSourceRange());
1368
1369    llvm::StringRef Clobber = Literal->getString();
1370
1371    if (!Context.Target.isValidGCCRegisterName(Clobber))
1372      return StmtError(Diag(Literal->getLocStart(),
1373                  diag::err_asm_unknown_register_name) << Clobber);
1374  }
1375
1376  constraints.release();
1377  exprs.release();
1378  asmString.release();
1379  clobbers.release();
1380  AsmStmt *NS =
1381    new (Context) AsmStmt(Context, AsmLoc, IsSimple, IsVolatile, MSAsm,
1382                          NumOutputs, NumInputs, Names, Constraints, Exprs,
1383                          AsmString, NumClobbers, Clobbers, RParenLoc);
1384  // Validate the asm string, ensuring it makes sense given the operands we
1385  // have.
1386  llvm::SmallVector<AsmStmt::AsmStringPiece, 8> Pieces;
1387  unsigned DiagOffs;
1388  if (unsigned DiagID = NS->AnalyzeAsmString(Pieces, Context, DiagOffs)) {
1389    Diag(getLocationOfStringLiteralByte(AsmString, DiagOffs), DiagID)
1390           << AsmString->getSourceRange();
1391    DeleteStmt(NS);
1392    return StmtError();
1393  }
1394
1395  // Validate tied input operands for type mismatches.
1396  for (unsigned i = 0, e = InputConstraintInfos.size(); i != e; ++i) {
1397    TargetInfo::ConstraintInfo &Info = InputConstraintInfos[i];
1398
1399    // If this is a tied constraint, verify that the output and input have
1400    // either exactly the same type, or that they are int/ptr operands with the
1401    // same size (int/long, int*/long, are ok etc).
1402    if (!Info.hasTiedOperand()) continue;
1403
1404    unsigned TiedTo = Info.getTiedOperand();
1405    Expr *OutputExpr = Exprs[TiedTo];
1406    Expr *InputExpr = Exprs[i+NumOutputs];
1407    QualType InTy = InputExpr->getType();
1408    QualType OutTy = OutputExpr->getType();
1409    if (Context.hasSameType(InTy, OutTy))
1410      continue;  // All types can be tied to themselves.
1411
1412    // Int/ptr operands have some special cases that we allow.
1413    if ((OutTy->isIntegerType() || OutTy->isPointerType()) &&
1414        (InTy->isIntegerType() || InTy->isPointerType())) {
1415
1416      // They are ok if they are the same size.  Tying void* to int is ok if
1417      // they are the same size, for example.  This also allows tying void* to
1418      // int*.
1419      uint64_t OutSize = Context.getTypeSize(OutTy);
1420      uint64_t InSize = Context.getTypeSize(InTy);
1421      if (OutSize == InSize)
1422        continue;
1423
1424      // If the smaller input/output operand is not mentioned in the asm string,
1425      // then we can promote it and the asm string won't notice.  Check this
1426      // case now.
1427      bool SmallerValueMentioned = false;
1428      for (unsigned p = 0, e = Pieces.size(); p != e; ++p) {
1429        AsmStmt::AsmStringPiece &Piece = Pieces[p];
1430        if (!Piece.isOperand()) continue;
1431
1432        // If this is a reference to the input and if the input was the smaller
1433        // one, then we have to reject this asm.
1434        if (Piece.getOperandNo() == i+NumOutputs) {
1435          if (InSize < OutSize) {
1436            SmallerValueMentioned = true;
1437            break;
1438          }
1439        }
1440
1441        // If this is a reference to the input and if the input was the smaller
1442        // one, then we have to reject this asm.
1443        if (Piece.getOperandNo() == TiedTo) {
1444          if (InSize > OutSize) {
1445            SmallerValueMentioned = true;
1446            break;
1447          }
1448        }
1449      }
1450
1451      // If the smaller value wasn't mentioned in the asm string, and if the
1452      // output was a register, just extend the shorter one to the size of the
1453      // larger one.
1454      if (!SmallerValueMentioned &&
1455          OutputConstraintInfos[TiedTo].allowsRegister())
1456        continue;
1457    }
1458
1459    Diag(InputExpr->getLocStart(),
1460         diag::err_asm_tying_incompatible_types)
1461      << InTy << OutTy << OutputExpr->getSourceRange()
1462      << InputExpr->getSourceRange();
1463    DeleteStmt(NS);
1464    return StmtError();
1465  }
1466
1467  return Owned(NS);
1468}
1469
1470Action::OwningStmtResult
1471Sema::ActOnObjCAtCatchStmt(SourceLocation AtLoc,
1472                           SourceLocation RParen, DeclPtrTy Parm,
1473                           StmtArg Body, StmtArg catchList) {
1474  Stmt *CatchList = catchList.takeAs<Stmt>();
1475  ParmVarDecl *PVD = cast_or_null<ParmVarDecl>(Parm.getAs<Decl>());
1476
1477  // PVD == 0 implies @catch(...).
1478  if (PVD) {
1479    // If we already know the decl is invalid, reject it.
1480    if (PVD->isInvalidDecl())
1481      return StmtError();
1482
1483    if (!PVD->getType()->isObjCObjectPointerType())
1484      return StmtError(Diag(PVD->getLocation(),
1485                       diag::err_catch_param_not_objc_type));
1486    if (PVD->getType()->isObjCQualifiedIdType())
1487      return StmtError(Diag(PVD->getLocation(),
1488                       diag::err_illegal_qualifiers_on_catch_parm));
1489  }
1490
1491  ObjCAtCatchStmt *CS = new (Context) ObjCAtCatchStmt(AtLoc, RParen,
1492    PVD, Body.takeAs<Stmt>(), CatchList);
1493  return Owned(CatchList ? CatchList : CS);
1494}
1495
1496Action::OwningStmtResult
1497Sema::ActOnObjCAtFinallyStmt(SourceLocation AtLoc, StmtArg Body) {
1498  return Owned(new (Context) ObjCAtFinallyStmt(AtLoc,
1499                                           static_cast<Stmt*>(Body.release())));
1500}
1501
1502Action::OwningStmtResult
1503Sema::ActOnObjCAtTryStmt(SourceLocation AtLoc,
1504                         StmtArg Try, StmtArg Catch, StmtArg Finally) {
1505  CurFunctionNeedsScopeChecking = true;
1506  return Owned(new (Context) ObjCAtTryStmt(AtLoc, Try.takeAs<Stmt>(),
1507                                           Catch.takeAs<Stmt>(),
1508                                           Finally.takeAs<Stmt>()));
1509}
1510
1511Action::OwningStmtResult
1512Sema::ActOnObjCAtThrowStmt(SourceLocation AtLoc, ExprArg expr,Scope *CurScope) {
1513  Expr *ThrowExpr = expr.takeAs<Expr>();
1514  if (!ThrowExpr) {
1515    // @throw without an expression designates a rethrow (which much occur
1516    // in the context of an @catch clause).
1517    Scope *AtCatchParent = CurScope;
1518    while (AtCatchParent && !AtCatchParent->isAtCatchScope())
1519      AtCatchParent = AtCatchParent->getParent();
1520    if (!AtCatchParent)
1521      return StmtError(Diag(AtLoc, diag::error_rethrow_used_outside_catch));
1522  } else {
1523    QualType ThrowType = ThrowExpr->getType();
1524    // Make sure the expression type is an ObjC pointer or "void *".
1525    if (!ThrowType->isObjCObjectPointerType()) {
1526      const PointerType *PT = ThrowType->getAs<PointerType>();
1527      if (!PT || !PT->getPointeeType()->isVoidType())
1528        return StmtError(Diag(AtLoc, diag::error_objc_throw_expects_object)
1529                        << ThrowExpr->getType() << ThrowExpr->getSourceRange());
1530    }
1531  }
1532  return Owned(new (Context) ObjCAtThrowStmt(AtLoc, ThrowExpr));
1533}
1534
1535Action::OwningStmtResult
1536Sema::ActOnObjCAtSynchronizedStmt(SourceLocation AtLoc, ExprArg SynchExpr,
1537                                  StmtArg SynchBody) {
1538  CurFunctionNeedsScopeChecking = true;
1539
1540  // Make sure the expression type is an ObjC pointer or "void *".
1541  Expr *SyncExpr = static_cast<Expr*>(SynchExpr.get());
1542  if (!SyncExpr->getType()->isObjCObjectPointerType()) {
1543    const PointerType *PT = SyncExpr->getType()->getAs<PointerType>();
1544    if (!PT || !PT->getPointeeType()->isVoidType())
1545      return StmtError(Diag(AtLoc, diag::error_objc_synchronized_expects_object)
1546                       << SyncExpr->getType() << SyncExpr->getSourceRange());
1547  }
1548
1549  return Owned(new (Context) ObjCAtSynchronizedStmt(AtLoc,
1550                                                    SynchExpr.takeAs<Stmt>(),
1551                                                    SynchBody.takeAs<Stmt>()));
1552}
1553
1554/// ActOnCXXCatchBlock - Takes an exception declaration and a handler block
1555/// and creates a proper catch handler from them.
1556Action::OwningStmtResult
1557Sema::ActOnCXXCatchBlock(SourceLocation CatchLoc, DeclPtrTy ExDecl,
1558                         StmtArg HandlerBlock) {
1559  // There's nothing to test that ActOnExceptionDecl didn't already test.
1560  return Owned(new (Context) CXXCatchStmt(CatchLoc,
1561                                  cast_or_null<VarDecl>(ExDecl.getAs<Decl>()),
1562                                          HandlerBlock.takeAs<Stmt>()));
1563}
1564
1565class TypeWithHandler {
1566  QualType t;
1567  CXXCatchStmt *stmt;
1568public:
1569  TypeWithHandler(const QualType &type, CXXCatchStmt *statement)
1570  : t(type), stmt(statement) {}
1571
1572  // An arbitrary order is fine as long as it places identical
1573  // types next to each other.
1574  bool operator<(const TypeWithHandler &y) const {
1575    if (t.getAsOpaquePtr() < y.t.getAsOpaquePtr())
1576      return true;
1577    if (t.getAsOpaquePtr() > y.t.getAsOpaquePtr())
1578      return false;
1579    else
1580      return getTypeSpecStartLoc() < y.getTypeSpecStartLoc();
1581  }
1582
1583  bool operator==(const TypeWithHandler& other) const {
1584    return t == other.t;
1585  }
1586
1587  QualType getQualType() const { return t; }
1588  CXXCatchStmt *getCatchStmt() const { return stmt; }
1589  SourceLocation getTypeSpecStartLoc() const {
1590    return stmt->getExceptionDecl()->getTypeSpecStartLoc();
1591  }
1592};
1593
1594/// ActOnCXXTryBlock - Takes a try compound-statement and a number of
1595/// handlers and creates a try statement from them.
1596Action::OwningStmtResult
1597Sema::ActOnCXXTryBlock(SourceLocation TryLoc, StmtArg TryBlock,
1598                       MultiStmtArg RawHandlers) {
1599  unsigned NumHandlers = RawHandlers.size();
1600  assert(NumHandlers > 0 &&
1601         "The parser shouldn't call this if there are no handlers.");
1602  Stmt **Handlers = reinterpret_cast<Stmt**>(RawHandlers.get());
1603
1604  llvm::SmallVector<TypeWithHandler, 8> TypesWithHandlers;
1605
1606  for (unsigned i = 0; i < NumHandlers; ++i) {
1607    CXXCatchStmt *Handler = llvm::cast<CXXCatchStmt>(Handlers[i]);
1608    if (!Handler->getExceptionDecl()) {
1609      if (i < NumHandlers - 1)
1610        return StmtError(Diag(Handler->getLocStart(),
1611                              diag::err_early_catch_all));
1612
1613      continue;
1614    }
1615
1616    const QualType CaughtType = Handler->getCaughtType();
1617    const QualType CanonicalCaughtType = Context.getCanonicalType(CaughtType);
1618    TypesWithHandlers.push_back(TypeWithHandler(CanonicalCaughtType, Handler));
1619  }
1620
1621  // Detect handlers for the same type as an earlier one.
1622  if (NumHandlers > 1) {
1623    llvm::array_pod_sort(TypesWithHandlers.begin(), TypesWithHandlers.end());
1624
1625    TypeWithHandler prev = TypesWithHandlers[0];
1626    for (unsigned i = 1; i < TypesWithHandlers.size(); ++i) {
1627      TypeWithHandler curr = TypesWithHandlers[i];
1628
1629      if (curr == prev) {
1630        Diag(curr.getTypeSpecStartLoc(),
1631             diag::warn_exception_caught_by_earlier_handler)
1632          << curr.getCatchStmt()->getCaughtType().getAsString();
1633        Diag(prev.getTypeSpecStartLoc(),
1634             diag::note_previous_exception_handler)
1635          << prev.getCatchStmt()->getCaughtType().getAsString();
1636      }
1637
1638      prev = curr;
1639    }
1640  }
1641
1642  // FIXME: We should detect handlers that cannot catch anything because an
1643  // earlier handler catches a superclass. Need to find a method that is not
1644  // quadratic for this.
1645  // Neither of these are explicitly forbidden, but every compiler detects them
1646  // and warns.
1647
1648  CurFunctionNeedsScopeChecking = true;
1649  RawHandlers.release();
1650  return Owned(CXXTryStmt::Create(Context, TryLoc,
1651                                  static_cast<Stmt*>(TryBlock.release()),
1652                                  Handlers, NumHandlers));
1653}
1654