SemaStmt.cpp revision d20254f2875d0004c57ee766f258dbcee29f4841 
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 CallExpr *CE = dyn_cast<CallExpr>(E)) {
97    // If the callee has attribute pure, const, or warn_unused_result, warn with
98    // a more specific message to make it clear what is happening.
99    if (const Decl *FD = CE->getCalleeDecl()) {
100      if (FD->getAttr<WarnUnusedResultAttr>()) {
101        Diag(Loc, diag::warn_unused_call) << R1 << R2 << "warn_unused_result";
102        return;
103      }
104      if (FD->getAttr<PureAttr>()) {
105        Diag(Loc, diag::warn_unused_call) << R1 << R2 << "pure";
106        return;
107      }
108      if (FD->getAttr<ConstAttr>()) {
109        Diag(Loc, diag::warn_unused_call) << R1 << R2 << "const";
110        return;
111      }
112    }
113  }
114
115  Diag(Loc, DiagID) << R1 << R2;
116}
117
118Action::OwningStmtResult
119Sema::ActOnCompoundStmt(SourceLocation L, SourceLocation R,
120                        MultiStmtArg elts, bool isStmtExpr) {
121  unsigned NumElts = elts.size();
122  Stmt **Elts = reinterpret_cast<Stmt**>(elts.release());
123  // If we're in C89 mode, check that we don't have any decls after stmts.  If
124  // so, emit an extension diagnostic.
125  if (!getLangOptions().C99 && !getLangOptions().CPlusPlus) {
126    // Note that __extension__ can be around a decl.
127    unsigned i = 0;
128    // Skip over all declarations.
129    for (; i != NumElts && isa<DeclStmt>(Elts[i]); ++i)
130      /*empty*/;
131
132    // We found the end of the list or a statement.  Scan for another declstmt.
133    for (; i != NumElts && !isa<DeclStmt>(Elts[i]); ++i)
134      /*empty*/;
135
136    if (i != NumElts) {
137      Decl *D = *cast<DeclStmt>(Elts[i])->decl_begin();
138      Diag(D->getLocation(), diag::ext_mixed_decls_code);
139    }
140  }
141  // Warn about unused expressions in statements.
142  for (unsigned i = 0; i != NumElts; ++i) {
143    // Ignore statements that are last in a statement expression.
144    if (isStmtExpr && i == NumElts - 1)
145      continue;
146
147    DiagnoseUnusedExprResult(Elts[i]);
148  }
149
150  return Owned(new (Context) CompoundStmt(Context, Elts, NumElts, L, R));
151}
152
153Action::OwningStmtResult
154Sema::ActOnCaseStmt(SourceLocation CaseLoc, ExprArg lhsval,
155                    SourceLocation DotDotDotLoc, ExprArg rhsval,
156                    SourceLocation ColonLoc) {
157  assert((lhsval.get() != 0) && "missing expression in case statement");
158
159  // C99 6.8.4.2p3: The expression shall be an integer constant.
160  // However, GCC allows any evaluatable integer expression.
161  Expr *LHSVal = static_cast<Expr*>(lhsval.get());
162  if (!LHSVal->isTypeDependent() && !LHSVal->isValueDependent() &&
163      VerifyIntegerConstantExpression(LHSVal))
164    return StmtError();
165
166  // GCC extension: The expression shall be an integer constant.
167
168  Expr *RHSVal = static_cast<Expr*>(rhsval.get());
169  if (RHSVal && !RHSVal->isTypeDependent() && !RHSVal->isValueDependent() &&
170      VerifyIntegerConstantExpression(RHSVal)) {
171    RHSVal = 0;  // Recover by just forgetting about it.
172    rhsval = 0;
173  }
174
175  if (getSwitchStack().empty()) {
176    Diag(CaseLoc, diag::err_case_not_in_switch);
177    return StmtError();
178  }
179
180  // Only now release the smart pointers.
181  lhsval.release();
182  rhsval.release();
183  CaseStmt *CS = new (Context) CaseStmt(LHSVal, RHSVal, CaseLoc, DotDotDotLoc,
184                                        ColonLoc);
185  getSwitchStack().back()->addSwitchCase(CS);
186  return Owned(CS);
187}
188
189/// ActOnCaseStmtBody - This installs a statement as the body of a case.
190void Sema::ActOnCaseStmtBody(StmtTy *caseStmt, StmtArg subStmt) {
191  CaseStmt *CS = static_cast<CaseStmt*>(caseStmt);
192  Stmt *SubStmt = subStmt.takeAs<Stmt>();
193  CS->setSubStmt(SubStmt);
194}
195
196Action::OwningStmtResult
197Sema::ActOnDefaultStmt(SourceLocation DefaultLoc, SourceLocation ColonLoc,
198                       StmtArg subStmt, Scope *CurScope) {
199  Stmt *SubStmt = subStmt.takeAs<Stmt>();
200
201  if (getSwitchStack().empty()) {
202    Diag(DefaultLoc, diag::err_default_not_in_switch);
203    return Owned(SubStmt);
204  }
205
206  DefaultStmt *DS = new (Context) DefaultStmt(DefaultLoc, ColonLoc, SubStmt);
207  getSwitchStack().back()->addSwitchCase(DS);
208  return Owned(DS);
209}
210
211Action::OwningStmtResult
212Sema::ActOnLabelStmt(SourceLocation IdentLoc, IdentifierInfo *II,
213                     SourceLocation ColonLoc, StmtArg subStmt) {
214  Stmt *SubStmt = subStmt.takeAs<Stmt>();
215  // Look up the record for this label identifier.
216  LabelStmt *&LabelDecl = getLabelMap()[II];
217
218  // If not forward referenced or defined already, just create a new LabelStmt.
219  if (LabelDecl == 0)
220    return Owned(LabelDecl = new (Context) LabelStmt(IdentLoc, II, SubStmt));
221
222  assert(LabelDecl->getID() == II && "Label mismatch!");
223
224  // Otherwise, this label was either forward reference or multiply defined.  If
225  // multiply defined, reject it now.
226  if (LabelDecl->getSubStmt()) {
227    Diag(IdentLoc, diag::err_redefinition_of_label) << LabelDecl->getID();
228    Diag(LabelDecl->getIdentLoc(), diag::note_previous_definition);
229    return Owned(SubStmt);
230  }
231
232  // Otherwise, this label was forward declared, and we just found its real
233  // definition.  Fill in the forward definition and return it.
234  LabelDecl->setIdentLoc(IdentLoc);
235  LabelDecl->setSubStmt(SubStmt);
236  return Owned(LabelDecl);
237}
238
239Action::OwningStmtResult
240Sema::ActOnIfStmt(SourceLocation IfLoc, FullExprArg CondVal, DeclPtrTy CondVar,
241                  StmtArg ThenVal, SourceLocation ElseLoc,
242                  StmtArg ElseVal) {
243  OwningExprResult CondResult(CondVal.release());
244
245  VarDecl *ConditionVar = 0;
246  if (CondVar.get()) {
247    ConditionVar = CondVar.getAs<VarDecl>();
248    CondResult = CheckConditionVariable(ConditionVar);
249    if (CondResult.isInvalid())
250      return StmtError();
251  }
252  Expr *ConditionExpr = CondResult.takeAs<Expr>();
253  if (!ConditionExpr)
254    return StmtError();
255
256  if (CheckBooleanCondition(ConditionExpr, IfLoc)) {
257    CondResult = ConditionExpr;
258    return StmtError();
259  }
260
261  Stmt *thenStmt = ThenVal.takeAs<Stmt>();
262  DiagnoseUnusedExprResult(thenStmt);
263
264  // Warn if the if block has a null body without an else value.
265  // this helps prevent bugs due to typos, such as
266  // if (condition);
267  //   do_stuff();
268  if (!ElseVal.get()) {
269    if (NullStmt* stmt = dyn_cast<NullStmt>(thenStmt))
270      Diag(stmt->getSemiLoc(), diag::warn_empty_if_body);
271  }
272
273  Stmt *elseStmt = ElseVal.takeAs<Stmt>();
274  DiagnoseUnusedExprResult(elseStmt);
275
276  CondResult.release();
277  return Owned(new (Context) IfStmt(IfLoc, ConditionVar, ConditionExpr,
278                                    thenStmt, ElseLoc, elseStmt));
279}
280
281Action::OwningStmtResult
282Sema::ActOnStartOfSwitchStmt(FullExprArg cond, DeclPtrTy CondVar) {
283  OwningExprResult CondResult(cond.release());
284
285  VarDecl *ConditionVar = 0;
286  if (CondVar.get()) {
287    ConditionVar = CondVar.getAs<VarDecl>();
288    CondResult = CheckConditionVariable(ConditionVar);
289    if (CondResult.isInvalid())
290      return StmtError();
291  }
292  SwitchStmt *SS = new (Context) SwitchStmt(ConditionVar,
293                                            CondResult.takeAs<Expr>());
294  getSwitchStack().push_back(SS);
295  return Owned(SS);
296}
297
298/// ConvertIntegerToTypeWarnOnOverflow - Convert the specified APInt to have
299/// the specified width and sign.  If an overflow occurs, detect it and emit
300/// the specified diagnostic.
301void Sema::ConvertIntegerToTypeWarnOnOverflow(llvm::APSInt &Val,
302                                              unsigned NewWidth, bool NewSign,
303                                              SourceLocation Loc,
304                                              unsigned DiagID) {
305  // Perform a conversion to the promoted condition type if needed.
306  if (NewWidth > Val.getBitWidth()) {
307    // If this is an extension, just do it.
308    llvm::APSInt OldVal(Val);
309    Val.extend(NewWidth);
310
311    // If the input was signed and negative and the output is unsigned,
312    // warn.
313    if (!NewSign && OldVal.isSigned() && OldVal.isNegative())
314      Diag(Loc, DiagID) << OldVal.toString(10) << Val.toString(10);
315
316    Val.setIsSigned(NewSign);
317  } else if (NewWidth < Val.getBitWidth()) {
318    // If this is a truncation, check for overflow.
319    llvm::APSInt ConvVal(Val);
320    ConvVal.trunc(NewWidth);
321    ConvVal.setIsSigned(NewSign);
322    ConvVal.extend(Val.getBitWidth());
323    ConvVal.setIsSigned(Val.isSigned());
324    if (ConvVal != Val)
325      Diag(Loc, DiagID) << Val.toString(10) << ConvVal.toString(10);
326
327    // Regardless of whether a diagnostic was emitted, really do the
328    // truncation.
329    Val.trunc(NewWidth);
330    Val.setIsSigned(NewSign);
331  } else if (NewSign != Val.isSigned()) {
332    // Convert the sign to match the sign of the condition.  This can cause
333    // overflow as well: unsigned(INTMIN)
334    llvm::APSInt OldVal(Val);
335    Val.setIsSigned(NewSign);
336
337    if (Val.isNegative())  // Sign bit changes meaning.
338      Diag(Loc, DiagID) << OldVal.toString(10) << Val.toString(10);
339  }
340}
341
342namespace {
343  struct CaseCompareFunctor {
344    bool operator()(const std::pair<llvm::APSInt, CaseStmt*> &LHS,
345                    const llvm::APSInt &RHS) {
346      return LHS.first < RHS;
347    }
348    bool operator()(const std::pair<llvm::APSInt, CaseStmt*> &LHS,
349                    const std::pair<llvm::APSInt, CaseStmt*> &RHS) {
350      return LHS.first < RHS.first;
351    }
352    bool operator()(const llvm::APSInt &LHS,
353                    const std::pair<llvm::APSInt, CaseStmt*> &RHS) {
354      return LHS < RHS.first;
355    }
356  };
357}
358
359/// CmpCaseVals - Comparison predicate for sorting case values.
360///
361static bool CmpCaseVals(const std::pair<llvm::APSInt, CaseStmt*>& lhs,
362                        const std::pair<llvm::APSInt, CaseStmt*>& rhs) {
363  if (lhs.first < rhs.first)
364    return true;
365
366  if (lhs.first == rhs.first &&
367      lhs.second->getCaseLoc().getRawEncoding()
368       < rhs.second->getCaseLoc().getRawEncoding())
369    return true;
370  return false;
371}
372
373/// GetTypeBeforeIntegralPromotion - Returns the pre-promotion type of
374/// potentially integral-promoted expression @p expr.
375static QualType GetTypeBeforeIntegralPromotion(const Expr* expr) {
376  const ImplicitCastExpr *ImplicitCast =
377      dyn_cast_or_null<ImplicitCastExpr>(expr);
378  if (ImplicitCast != NULL) {
379    const Expr *ExprBeforePromotion = ImplicitCast->getSubExpr();
380    QualType TypeBeforePromotion = ExprBeforePromotion->getType();
381    if (TypeBeforePromotion->isIntegralType()) {
382      return TypeBeforePromotion;
383    }
384  }
385  return expr->getType();
386}
387
388/// \brief Check (and possibly convert) the condition in a switch
389/// statement in C++.
390static bool CheckCXXSwitchCondition(Sema &S, SourceLocation SwitchLoc,
391                                    Expr *&CondExpr) {
392  if (CondExpr->isTypeDependent())
393    return false;
394
395  QualType CondType = CondExpr->getType();
396
397  // C++ 6.4.2.p2:
398  // The condition shall be of integral type, enumeration type, or of a class
399  // type for which a single conversion function to integral or enumeration
400  // type exists (12.3). If the condition is of class type, the condition is
401  // converted by calling that conversion function, and the result of the
402  // conversion is used in place of the original condition for the remainder
403  // of this section. Integral promotions are performed.
404
405  // Make sure that the condition expression has a complete type,
406  // otherwise we'll never find any conversions.
407  if (S.RequireCompleteType(SwitchLoc, CondType,
408                            PDiag(diag::err_switch_incomplete_class_type)
409                              << CondExpr->getSourceRange()))
410    return true;
411
412  llvm::SmallVector<CXXConversionDecl *, 4> ViableConversions;
413  llvm::SmallVector<CXXConversionDecl *, 4> ExplicitConversions;
414  if (const RecordType *RecordTy = CondType->getAs<RecordType>()) {
415    const UnresolvedSet *Conversions
416      = cast<CXXRecordDecl>(RecordTy->getDecl())
417                                             ->getVisibleConversionFunctions();
418    for (UnresolvedSet::iterator I = Conversions->begin(),
419           E = Conversions->end(); I != E; ++I) {
420      if (CXXConversionDecl *Conversion = dyn_cast<CXXConversionDecl>(*I))
421        if (Conversion->getConversionType().getNonReferenceType()
422              ->isIntegralType()) {
423          if (Conversion->isExplicit())
424            ExplicitConversions.push_back(Conversion);
425          else
426          ViableConversions.push_back(Conversion);
427        }
428    }
429
430    switch (ViableConversions.size()) {
431    case 0:
432      if (ExplicitConversions.size() == 1) {
433        // The user probably meant to invoke the given explicit
434        // conversion; use it.
435        QualType ConvTy
436          = ExplicitConversions[0]->getConversionType()
437                        .getNonReferenceType();
438        std::string TypeStr;
439        ConvTy.getAsStringInternal(TypeStr, S.Context.PrintingPolicy);
440
441        S.Diag(SwitchLoc, diag::err_switch_explicit_conversion)
442          << CondType << ConvTy << CondExpr->getSourceRange()
443          << CodeModificationHint::CreateInsertion(CondExpr->getLocStart(),
444                                         "static_cast<" + TypeStr + ">(")
445          << CodeModificationHint::CreateInsertion(
446                            S.PP.getLocForEndOfToken(CondExpr->getLocEnd()),
447                               ")");
448        S.Diag(ExplicitConversions[0]->getLocation(),
449             diag::note_switch_conversion)
450          << ConvTy->isEnumeralType() << ConvTy;
451
452        // If we aren't in a SFINAE context, build a call to the
453        // explicit conversion function.
454        if (S.isSFINAEContext())
455          return true;
456
457        CondExpr = S.BuildCXXMemberCallExpr(CondExpr, ExplicitConversions[0]);
458      }
459
460      // We'll complain below about a non-integral condition type.
461      break;
462
463    case 1:
464      // Apply this conversion.
465      CondExpr = S.BuildCXXMemberCallExpr(CondExpr, ViableConversions[0]);
466      break;
467
468    default:
469      S.Diag(SwitchLoc, diag::err_switch_multiple_conversions)
470        << CondType << CondExpr->getSourceRange();
471      for (unsigned I = 0, N = ViableConversions.size(); I != N; ++I) {
472        QualType ConvTy
473          = ViableConversions[I]->getConversionType().getNonReferenceType();
474        S.Diag(ViableConversions[I]->getLocation(),
475             diag::note_switch_conversion)
476          << ConvTy->isEnumeralType() << ConvTy;
477      }
478      return true;
479    }
480  }
481
482  return false;
483}
484
485Action::OwningStmtResult
486Sema::ActOnFinishSwitchStmt(SourceLocation SwitchLoc, StmtArg Switch,
487                            StmtArg Body) {
488  Stmt *BodyStmt = Body.takeAs<Stmt>();
489
490  SwitchStmt *SS = getSwitchStack().back();
491  assert(SS == (SwitchStmt*)Switch.get() && "switch stack missing push/pop!");
492
493  SS->setBody(BodyStmt, SwitchLoc);
494  getSwitchStack().pop_back();
495
496  if (SS->getCond() == 0) {
497    SS->Destroy(Context);
498    return StmtError();
499  }
500
501  Expr *CondExpr = SS->getCond();
502  QualType CondTypeBeforePromotion =
503      GetTypeBeforeIntegralPromotion(CondExpr);
504
505  if (getLangOptions().CPlusPlus &&
506      CheckCXXSwitchCondition(*this, SwitchLoc, CondExpr))
507    return StmtError();
508
509  // C99 6.8.4.2p5 - Integer promotions are performed on the controlling expr.
510  UsualUnaryConversions(CondExpr);
511  QualType CondType = CondExpr->getType();
512  SS->setCond(CondExpr);
513
514  // C++ 6.4.2.p2:
515  // Integral promotions are performed (on the switch condition).
516  //
517  // A case value unrepresentable by the original switch condition
518  // type (before the promotion) doesn't make sense, even when it can
519  // be represented by the promoted type.  Therefore we need to find
520  // the pre-promotion type of the switch condition.
521  if (!CondExpr->isTypeDependent()) {
522    if (!CondType->isIntegerType()) { // C99 6.8.4.2p1
523      Diag(SwitchLoc, diag::err_typecheck_statement_requires_integer)
524          << CondType << CondExpr->getSourceRange();
525      return StmtError();
526    }
527
528    if (CondTypeBeforePromotion->isBooleanType()) {
529      // switch(bool_expr) {...} is often a programmer error, e.g.
530      //   switch(n && mask) { ... }  // Doh - should be "n & mask".
531      // One can always use an if statement instead of switch(bool_expr).
532      Diag(SwitchLoc, diag::warn_bool_switch_condition)
533          << CondExpr->getSourceRange();
534    }
535  }
536
537  // Get the bitwidth of the switched-on value before promotions.  We must
538  // convert the integer case values to this width before comparison.
539  bool HasDependentValue
540    = CondExpr->isTypeDependent() || CondExpr->isValueDependent();
541  unsigned CondWidth
542    = HasDependentValue? 0
543      : static_cast<unsigned>(Context.getTypeSize(CondTypeBeforePromotion));
544  bool CondIsSigned = CondTypeBeforePromotion->isSignedIntegerType();
545
546  // Accumulate all of the case values in a vector so that we can sort them
547  // and detect duplicates.  This vector contains the APInt for the case after
548  // it has been converted to the condition type.
549  typedef llvm::SmallVector<std::pair<llvm::APSInt, CaseStmt*>, 64> CaseValsTy;
550  CaseValsTy CaseVals;
551
552  // Keep track of any GNU case ranges we see.  The APSInt is the low value.
553  std::vector<std::pair<llvm::APSInt, CaseStmt*> > CaseRanges;
554
555  DefaultStmt *TheDefaultStmt = 0;
556
557  bool CaseListIsErroneous = false;
558
559  for (SwitchCase *SC = SS->getSwitchCaseList(); SC && !HasDependentValue;
560       SC = SC->getNextSwitchCase()) {
561
562    if (DefaultStmt *DS = dyn_cast<DefaultStmt>(SC)) {
563      if (TheDefaultStmt) {
564        Diag(DS->getDefaultLoc(), diag::err_multiple_default_labels_defined);
565        Diag(TheDefaultStmt->getDefaultLoc(), diag::note_duplicate_case_prev);
566
567        // FIXME: Remove the default statement from the switch block so that
568        // we'll return a valid AST.  This requires recursing down the AST and
569        // finding it, not something we are set up to do right now.  For now,
570        // just lop the entire switch stmt out of the AST.
571        CaseListIsErroneous = true;
572      }
573      TheDefaultStmt = DS;
574
575    } else {
576      CaseStmt *CS = cast<CaseStmt>(SC);
577
578      // We already verified that the expression has a i-c-e value (C99
579      // 6.8.4.2p3) - get that value now.
580      Expr *Lo = CS->getLHS();
581
582      if (Lo->isTypeDependent() || Lo->isValueDependent()) {
583        HasDependentValue = true;
584        break;
585      }
586
587      llvm::APSInt LoVal = Lo->EvaluateAsInt(Context);
588
589      // Convert the value to the same width/sign as the condition.
590      ConvertIntegerToTypeWarnOnOverflow(LoVal, CondWidth, CondIsSigned,
591                                         CS->getLHS()->getLocStart(),
592                                         diag::warn_case_value_overflow);
593
594      // If the LHS is not the same type as the condition, insert an implicit
595      // cast.
596      ImpCastExprToType(Lo, CondType, CastExpr::CK_IntegralCast);
597      CS->setLHS(Lo);
598
599      // If this is a case range, remember it in CaseRanges, otherwise CaseVals.
600      if (CS->getRHS()) {
601        if (CS->getRHS()->isTypeDependent() ||
602            CS->getRHS()->isValueDependent()) {
603          HasDependentValue = true;
604          break;
605        }
606        CaseRanges.push_back(std::make_pair(LoVal, CS));
607      } else
608        CaseVals.push_back(std::make_pair(LoVal, CS));
609    }
610  }
611
612  if (!HasDependentValue) {
613    // Sort all the scalar case values so we can easily detect duplicates.
614    std::stable_sort(CaseVals.begin(), CaseVals.end(), CmpCaseVals);
615
616    if (!CaseVals.empty()) {
617      for (unsigned i = 0, e = CaseVals.size()-1; i != e; ++i) {
618        if (CaseVals[i].first == CaseVals[i+1].first) {
619          // If we have a duplicate, report it.
620          Diag(CaseVals[i+1].second->getLHS()->getLocStart(),
621               diag::err_duplicate_case) << CaseVals[i].first.toString(10);
622          Diag(CaseVals[i].second->getLHS()->getLocStart(),
623               diag::note_duplicate_case_prev);
624          // FIXME: We really want to remove the bogus case stmt from the
625          // substmt, but we have no way to do this right now.
626          CaseListIsErroneous = true;
627        }
628      }
629    }
630
631    // Detect duplicate case ranges, which usually don't exist at all in
632    // the first place.
633    if (!CaseRanges.empty()) {
634      // Sort all the case ranges by their low value so we can easily detect
635      // overlaps between ranges.
636      std::stable_sort(CaseRanges.begin(), CaseRanges.end());
637
638      // Scan the ranges, computing the high values and removing empty ranges.
639      std::vector<llvm::APSInt> HiVals;
640      for (unsigned i = 0, e = CaseRanges.size(); i != e; ++i) {
641        CaseStmt *CR = CaseRanges[i].second;
642        Expr *Hi = CR->getRHS();
643        llvm::APSInt HiVal = Hi->EvaluateAsInt(Context);
644
645        // Convert the value to the same width/sign as the condition.
646        ConvertIntegerToTypeWarnOnOverflow(HiVal, CondWidth, CondIsSigned,
647                                           CR->getRHS()->getLocStart(),
648                                           diag::warn_case_value_overflow);
649
650        // If the LHS is not the same type as the condition, insert an implicit
651        // cast.
652        ImpCastExprToType(Hi, CondType, CastExpr::CK_IntegralCast);
653        CR->setRHS(Hi);
654
655        // If the low value is bigger than the high value, the case is empty.
656        if (CaseRanges[i].first > HiVal) {
657          Diag(CR->getLHS()->getLocStart(), diag::warn_case_empty_range)
658            << SourceRange(CR->getLHS()->getLocStart(),
659                           CR->getRHS()->getLocEnd());
660          CaseRanges.erase(CaseRanges.begin()+i);
661          --i, --e;
662          continue;
663        }
664        HiVals.push_back(HiVal);
665      }
666
667      // Rescan the ranges, looking for overlap with singleton values and other
668      // ranges.  Since the range list is sorted, we only need to compare case
669      // ranges with their neighbors.
670      for (unsigned i = 0, e = CaseRanges.size(); i != e; ++i) {
671        llvm::APSInt &CRLo = CaseRanges[i].first;
672        llvm::APSInt &CRHi = HiVals[i];
673        CaseStmt *CR = CaseRanges[i].second;
674
675        // Check to see whether the case range overlaps with any
676        // singleton cases.
677        CaseStmt *OverlapStmt = 0;
678        llvm::APSInt OverlapVal(32);
679
680        // Find the smallest value >= the lower bound.  If I is in the
681        // case range, then we have overlap.
682        CaseValsTy::iterator I = std::lower_bound(CaseVals.begin(),
683                                                  CaseVals.end(), CRLo,
684                                                  CaseCompareFunctor());
685        if (I != CaseVals.end() && I->first < CRHi) {
686          OverlapVal  = I->first;   // Found overlap with scalar.
687          OverlapStmt = I->second;
688        }
689
690        // Find the smallest value bigger than the upper bound.
691        I = std::upper_bound(I, CaseVals.end(), CRHi, CaseCompareFunctor());
692        if (I != CaseVals.begin() && (I-1)->first >= CRLo) {
693          OverlapVal  = (I-1)->first;      // Found overlap with scalar.
694          OverlapStmt = (I-1)->second;
695        }
696
697        // Check to see if this case stmt overlaps with the subsequent
698        // case range.
699        if (i && CRLo <= HiVals[i-1]) {
700          OverlapVal  = HiVals[i-1];       // Found overlap with range.
701          OverlapStmt = CaseRanges[i-1].second;
702        }
703
704        if (OverlapStmt) {
705          // If we have a duplicate, report it.
706          Diag(CR->getLHS()->getLocStart(), diag::err_duplicate_case)
707            << OverlapVal.toString(10);
708          Diag(OverlapStmt->getLHS()->getLocStart(),
709               diag::note_duplicate_case_prev);
710          // FIXME: We really want to remove the bogus case stmt from the
711          // substmt, but we have no way to do this right now.
712          CaseListIsErroneous = true;
713        }
714      }
715    }
716  }
717
718  // FIXME: If the case list was broken is some way, we don't have a good system
719  // to patch it up.  Instead, just return the whole substmt as broken.
720  if (CaseListIsErroneous)
721    return StmtError();
722
723  Switch.release();
724  return Owned(SS);
725}
726
727Action::OwningStmtResult
728Sema::ActOnWhileStmt(SourceLocation WhileLoc, FullExprArg Cond,
729                     DeclPtrTy CondVar, StmtArg Body) {
730  OwningExprResult CondResult(Cond.release());
731
732  VarDecl *ConditionVar = 0;
733  if (CondVar.get()) {
734    ConditionVar = CondVar.getAs<VarDecl>();
735    CondResult = CheckConditionVariable(ConditionVar);
736    if (CondResult.isInvalid())
737      return StmtError();
738  }
739  Expr *ConditionExpr = CondResult.takeAs<Expr>();
740  if (!ConditionExpr)
741    return StmtError();
742
743  if (CheckBooleanCondition(ConditionExpr, WhileLoc)) {
744    CondResult = ConditionExpr;
745    return StmtError();
746  }
747
748  Stmt *bodyStmt = Body.takeAs<Stmt>();
749  DiagnoseUnusedExprResult(bodyStmt);
750
751  CondResult.release();
752  return Owned(new (Context) WhileStmt(ConditionVar, ConditionExpr, bodyStmt,
753                                       WhileLoc));
754}
755
756Action::OwningStmtResult
757Sema::ActOnDoStmt(SourceLocation DoLoc, StmtArg Body,
758                  SourceLocation WhileLoc, SourceLocation CondLParen,
759                  ExprArg Cond, SourceLocation CondRParen) {
760  Expr *condExpr = Cond.takeAs<Expr>();
761  assert(condExpr && "ActOnDoStmt(): missing expression");
762
763  if (CheckBooleanCondition(condExpr, DoLoc)) {
764    Cond = condExpr;
765    return StmtError();
766  }
767
768  Stmt *bodyStmt = Body.takeAs<Stmt>();
769  DiagnoseUnusedExprResult(bodyStmt);
770
771  Cond.release();
772  return Owned(new (Context) DoStmt(bodyStmt, condExpr, DoLoc,
773                                    WhileLoc, CondRParen));
774}
775
776Action::OwningStmtResult
777Sema::ActOnForStmt(SourceLocation ForLoc, SourceLocation LParenLoc,
778                   StmtArg first, FullExprArg second, DeclPtrTy secondVar,
779                   FullExprArg third,
780                   SourceLocation RParenLoc, StmtArg body) {
781  Stmt *First  = static_cast<Stmt*>(first.get());
782
783  if (!getLangOptions().CPlusPlus) {
784    if (DeclStmt *DS = dyn_cast_or_null<DeclStmt>(First)) {
785      // C99 6.8.5p3: The declaration part of a 'for' statement shall only
786      // declare identifiers for objects having storage class 'auto' or
787      // 'register'.
788      for (DeclStmt::decl_iterator DI=DS->decl_begin(), DE=DS->decl_end();
789           DI!=DE; ++DI) {
790        VarDecl *VD = dyn_cast<VarDecl>(*DI);
791        if (VD && VD->isBlockVarDecl() && !VD->hasLocalStorage())
792          VD = 0;
793        if (VD == 0)
794          Diag((*DI)->getLocation(), diag::err_non_variable_decl_in_for);
795        // FIXME: mark decl erroneous!
796      }
797    }
798  }
799
800  OwningExprResult SecondResult(second.release());
801  VarDecl *ConditionVar = 0;
802  if (secondVar.get()) {
803    ConditionVar = secondVar.getAs<VarDecl>();
804    SecondResult = CheckConditionVariable(ConditionVar);
805    if (SecondResult.isInvalid())
806      return StmtError();
807  }
808
809  Expr *Second = SecondResult.takeAs<Expr>();
810  if (Second && CheckBooleanCondition(Second, ForLoc)) {
811    SecondResult = Second;
812    return StmtError();
813  }
814
815  Expr *Third  = third.release().takeAs<Expr>();
816  Stmt *Body  = static_cast<Stmt*>(body.get());
817
818  DiagnoseUnusedExprResult(First);
819  DiagnoseUnusedExprResult(Third);
820  DiagnoseUnusedExprResult(Body);
821
822  first.release();
823  body.release();
824  return Owned(new (Context) ForStmt(First, Second, ConditionVar, Third, Body,
825                                     ForLoc, LParenLoc, RParenLoc));
826}
827
828Action::OwningStmtResult
829Sema::ActOnObjCForCollectionStmt(SourceLocation ForLoc,
830                                 SourceLocation LParenLoc,
831                                 StmtArg first, ExprArg second,
832                                 SourceLocation RParenLoc, StmtArg body) {
833  Stmt *First  = static_cast<Stmt*>(first.get());
834  Expr *Second = static_cast<Expr*>(second.get());
835  Stmt *Body  = static_cast<Stmt*>(body.get());
836  if (First) {
837    QualType FirstType;
838    if (DeclStmt *DS = dyn_cast<DeclStmt>(First)) {
839      if (!DS->isSingleDecl())
840        return StmtError(Diag((*DS->decl_begin())->getLocation(),
841                         diag::err_toomany_element_decls));
842
843      Decl *D = DS->getSingleDecl();
844      FirstType = cast<ValueDecl>(D)->getType();
845      // C99 6.8.5p3: The declaration part of a 'for' statement shall only
846      // declare identifiers for objects having storage class 'auto' or
847      // 'register'.
848      VarDecl *VD = cast<VarDecl>(D);
849      if (VD->isBlockVarDecl() && !VD->hasLocalStorage())
850        return StmtError(Diag(VD->getLocation(),
851                              diag::err_non_variable_decl_in_for));
852    } else {
853      if (cast<Expr>(First)->isLvalue(Context) != Expr::LV_Valid)
854        return StmtError(Diag(First->getLocStart(),
855                   diag::err_selector_element_not_lvalue)
856          << First->getSourceRange());
857
858      FirstType = static_cast<Expr*>(First)->getType();
859    }
860    if (!FirstType->isObjCObjectPointerType() &&
861        !FirstType->isBlockPointerType())
862        Diag(ForLoc, diag::err_selector_element_type)
863          << FirstType << First->getSourceRange();
864  }
865  if (Second) {
866    DefaultFunctionArrayConversion(Second);
867    QualType SecondType = Second->getType();
868    if (!SecondType->isObjCObjectPointerType())
869      Diag(ForLoc, diag::err_collection_expr_type)
870        << SecondType << Second->getSourceRange();
871  }
872  first.release();
873  second.release();
874  body.release();
875  return Owned(new (Context) ObjCForCollectionStmt(First, Second, Body,
876                                                   ForLoc, RParenLoc));
877}
878
879Action::OwningStmtResult
880Sema::ActOnGotoStmt(SourceLocation GotoLoc, SourceLocation LabelLoc,
881                    IdentifierInfo *LabelII) {
882  // If we are in a block, reject all gotos for now.
883  if (CurBlock)
884    return StmtError(Diag(GotoLoc, diag::err_goto_in_block));
885
886  // Look up the record for this label identifier.
887  LabelStmt *&LabelDecl = getLabelMap()[LabelII];
888
889  // If we haven't seen this label yet, create a forward reference.
890  if (LabelDecl == 0)
891    LabelDecl = new (Context) LabelStmt(LabelLoc, LabelII, 0);
892
893  return Owned(new (Context) GotoStmt(LabelDecl, GotoLoc, LabelLoc));
894}
895
896Action::OwningStmtResult
897Sema::ActOnIndirectGotoStmt(SourceLocation GotoLoc, SourceLocation StarLoc,
898                            ExprArg DestExp) {
899  // Convert operand to void*
900  Expr* E = DestExp.takeAs<Expr>();
901  if (!E->isTypeDependent()) {
902    QualType ETy = E->getType();
903    AssignConvertType ConvTy =
904      CheckSingleAssignmentConstraints(Context.VoidPtrTy, E);
905    if (DiagnoseAssignmentResult(ConvTy, StarLoc, Context.VoidPtrTy, ETy,
906                                 E, AA_Passing))
907      return StmtError();
908  }
909  return Owned(new (Context) IndirectGotoStmt(GotoLoc, StarLoc, E));
910}
911
912Action::OwningStmtResult
913Sema::ActOnContinueStmt(SourceLocation ContinueLoc, Scope *CurScope) {
914  Scope *S = CurScope->getContinueParent();
915  if (!S) {
916    // C99 6.8.6.2p1: A break shall appear only in or as a loop body.
917    return StmtError(Diag(ContinueLoc, diag::err_continue_not_in_loop));
918  }
919
920  return Owned(new (Context) ContinueStmt(ContinueLoc));
921}
922
923Action::OwningStmtResult
924Sema::ActOnBreakStmt(SourceLocation BreakLoc, Scope *CurScope) {
925  Scope *S = CurScope->getBreakParent();
926  if (!S) {
927    // C99 6.8.6.3p1: A break shall appear only in or as a switch/loop body.
928    return StmtError(Diag(BreakLoc, diag::err_break_not_in_loop_or_switch));
929  }
930
931  return Owned(new (Context) BreakStmt(BreakLoc));
932}
933
934/// ActOnBlockReturnStmt - Utility routine to figure out block's return type.
935///
936Action::OwningStmtResult
937Sema::ActOnBlockReturnStmt(SourceLocation ReturnLoc, Expr *RetValExp) {
938  // If this is the first return we've seen in the block, infer the type of
939  // the block from it.
940  if (CurBlock->ReturnType.isNull()) {
941    if (RetValExp) {
942      // Don't call UsualUnaryConversions(), since we don't want to do
943      // integer promotions here.
944      DefaultFunctionArrayConversion(RetValExp);
945      CurBlock->ReturnType = RetValExp->getType();
946      if (BlockDeclRefExpr *CDRE = dyn_cast<BlockDeclRefExpr>(RetValExp)) {
947        // We have to remove a 'const' added to copied-in variable which was
948        // part of the implementation spec. and not the actual qualifier for
949        // the variable.
950        if (CDRE->isConstQualAdded())
951           CurBlock->ReturnType.removeConst();
952      }
953    } else
954      CurBlock->ReturnType = Context.VoidTy;
955  }
956  QualType FnRetType = CurBlock->ReturnType;
957
958  if (CurBlock->TheDecl->hasAttr<NoReturnAttr>()) {
959    Diag(ReturnLoc, diag::err_noreturn_block_has_return_expr)
960      << getCurFunctionOrMethodDecl()->getDeclName();
961    return StmtError();
962  }
963
964  // Otherwise, verify that this result type matches the previous one.  We are
965  // pickier with blocks than for normal functions because we don't have GCC
966  // compatibility to worry about here.
967  if (CurBlock->ReturnType->isVoidType()) {
968    if (RetValExp) {
969      Diag(ReturnLoc, diag::err_return_block_has_expr);
970      RetValExp->Destroy(Context);
971      RetValExp = 0;
972    }
973    return Owned(new (Context) ReturnStmt(ReturnLoc, RetValExp));
974  }
975
976  if (!RetValExp)
977    return StmtError(Diag(ReturnLoc, diag::err_block_return_missing_expr));
978
979  if (!FnRetType->isDependentType() && !RetValExp->isTypeDependent()) {
980    // we have a non-void block with an expression, continue checking
981    QualType RetValType = RetValExp->getType();
982
983    // C99 6.8.6.4p3(136): The return statement is not an assignment. The
984    // overlap restriction of subclause 6.5.16.1 does not apply to the case of
985    // function return.
986
987    // In C++ the return statement is handled via a copy initialization.
988    // the C version of which boils down to CheckSingleAssignmentConstraints.
989    // FIXME: Leaks RetValExp.
990    if (PerformCopyInitialization(RetValExp, FnRetType, AA_Returning))
991      return StmtError();
992
993    if (RetValExp) CheckReturnStackAddr(RetValExp, FnRetType, ReturnLoc);
994  }
995
996  return Owned(new (Context) ReturnStmt(ReturnLoc, RetValExp));
997}
998
999/// IsReturnCopyElidable - Whether returning @p RetExpr from a function that
1000/// returns a @p RetType fulfills the criteria for copy elision (C++0x 12.8p15).
1001static bool IsReturnCopyElidable(ASTContext &Ctx, QualType RetType,
1002                                 Expr *RetExpr) {
1003  QualType ExprType = RetExpr->getType();
1004  // - in a return statement in a function with ...
1005  // ... a class return type ...
1006  if (!RetType->isRecordType())
1007    return false;
1008  // ... the same cv-unqualified type as the function return type ...
1009  if (!Ctx.hasSameUnqualifiedType(RetType, ExprType))
1010    return false;
1011  // ... the expression is the name of a non-volatile automatic object ...
1012  // We ignore parentheses here.
1013  // FIXME: Is this compliant?
1014  const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(RetExpr->IgnoreParens());
1015  if (!DR)
1016    return false;
1017  const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl());
1018  if (!VD)
1019    return false;
1020  return VD->hasLocalStorage() && !VD->getType()->isReferenceType()
1021    && !VD->getType().isVolatileQualified();
1022}
1023
1024Action::OwningStmtResult
1025Sema::ActOnReturnStmt(SourceLocation ReturnLoc, ExprArg rex) {
1026  Expr *RetValExp = rex.takeAs<Expr>();
1027  if (CurBlock)
1028    return ActOnBlockReturnStmt(ReturnLoc, RetValExp);
1029
1030  QualType FnRetType;
1031  TypeLoc FnRetTypeLoc;
1032  if (const FunctionDecl *FD = getCurFunctionDecl()) {
1033    FnRetType = FD->getResultType();
1034    if (FD->hasAttr<NoReturnAttr>())
1035      Diag(ReturnLoc, diag::warn_noreturn_function_has_return_expr)
1036        << getCurFunctionOrMethodDecl()->getDeclName();
1037
1038#if 0
1039    // FIXME: Useful, once we're sure it has all of the information we
1040    // need.
1041    if (TypeSourceInfo *TInfo = FD->getTypeSourceInfo()) {
1042      TypeLoc TL = TInfo->getTypeLoc();
1043      if (FunctionTypeLoc *FTL = dyn_cast<FunctionTypeLoc>(&TL))
1044        FnRetTypeLoc = FTL->getResultLoc();
1045    }
1046#endif
1047
1048  } else if (ObjCMethodDecl *MD = getCurMethodDecl())
1049    FnRetType = MD->getResultType();
1050  else // If we don't have a function/method context, bail.
1051    return StmtError();
1052
1053  if (FnRetType->isVoidType()) {
1054    if (RetValExp && !RetValExp->isTypeDependent()) {
1055      // C99 6.8.6.4p1 (ext_ since GCC warns)
1056      unsigned D = diag::ext_return_has_expr;
1057      if (RetValExp->getType()->isVoidType())
1058        D = diag::ext_return_has_void_expr;
1059
1060      // return (some void expression); is legal in C++.
1061      if (D != diag::ext_return_has_void_expr ||
1062          !getLangOptions().CPlusPlus) {
1063        NamedDecl *CurDecl = getCurFunctionOrMethodDecl();
1064        Diag(ReturnLoc, D)
1065          << CurDecl->getDeclName() << isa<ObjCMethodDecl>(CurDecl)
1066          << RetValExp->getSourceRange();
1067      }
1068
1069      RetValExp = MaybeCreateCXXExprWithTemporaries(RetValExp);
1070    }
1071    return Owned(new (Context) ReturnStmt(ReturnLoc, RetValExp));
1072  }
1073
1074  if (!RetValExp && !FnRetType->isDependentType()) {
1075    unsigned DiagID = diag::warn_return_missing_expr;  // C90 6.6.6.4p4
1076    // C99 6.8.6.4p1 (ext_ since GCC warns)
1077    if (getLangOptions().C99) DiagID = diag::ext_return_missing_expr;
1078
1079    if (FunctionDecl *FD = getCurFunctionDecl())
1080      Diag(ReturnLoc, DiagID) << FD->getIdentifier() << 0/*fn*/;
1081    else
1082      Diag(ReturnLoc, DiagID) << getCurMethodDecl()->getDeclName() << 1/*meth*/;
1083    return Owned(new (Context) ReturnStmt(ReturnLoc, (Expr*)0));
1084  }
1085
1086  if (!FnRetType->isDependentType() && !RetValExp->isTypeDependent()) {
1087    // we have a non-void function with an expression, continue checking
1088
1089    // C99 6.8.6.4p3(136): The return statement is not an assignment. The
1090    // overlap restriction of subclause 6.5.16.1 does not apply to the case of
1091    // function return.
1092
1093    // C++0x 12.8p15: When certain criteria are met, an implementation is
1094    //   allowed to omit the copy construction of a class object, [...]
1095    //   - in a return statement in a function with a class return type, when
1096    //     the expression is the name of a non-volatile automatic object with
1097    //     the same cv-unqualified type as the function return type, the copy
1098    //     operation can be omitted [...]
1099    // C++0x 12.8p16: When the criteria for elision of a copy operation are met
1100    //   and the object to be copied is designated by an lvalue, overload
1101    //   resolution to select the constructor for the copy is first performed
1102    //   as if the object were designated by an rvalue.
1103    // Note that we only compute Elidable if we're in C++0x, since we don't
1104    // care otherwise.
1105    bool Elidable = getLangOptions().CPlusPlus0x ?
1106                      IsReturnCopyElidable(Context, FnRetType, RetValExp) :
1107                      false;
1108    // FIXME: Elidable
1109    (void)Elidable;
1110
1111    // If we somehow didn't get a
1112
1113    // FIXME: Should we allocate the TypeSourceInfo and attach it to
1114    // the declaration? Alternatively, we could require that all
1115    // function and method declarations have TypeSourceInfos, so that
1116    // this is never required.  FIXME: Also, the allocated TInfo goes
1117    // into the bump pointer, so it cannot actually be freed.
1118    TypeSourceInfo *AllocatedTInfo = 0;
1119    if (!FnRetTypeLoc) {
1120      const FunctionDecl *FD = getCurFunctionDecl();
1121      SourceLocation Loc = FD? FD->getLocation()
1122                             : getCurMethodDecl()->getLocation();
1123      AllocatedTInfo = Context.getTrivialTypeSourceInfo(FnRetType, Loc);
1124      FnRetTypeLoc = AllocatedTInfo->getTypeLoc();
1125    }
1126
1127    // In C++ the return statement is handled via a copy initialization.
1128    // the C version of which boils down to CheckSingleAssignmentConstraints.
1129    OwningExprResult Res = PerformCopyInitialization(
1130                             InitializedEntity::InitializeResult(ReturnLoc,
1131                                                                 FnRetTypeLoc),
1132                             SourceLocation(),
1133                             Owned(RetValExp));
1134    if (Res.isInvalid()) {
1135      // FIXME: Cleanup temporaries here, anyway?
1136      return StmtError();
1137    }
1138
1139    RetValExp = Res.takeAs<Expr>();
1140    if (RetValExp)
1141      CheckReturnStackAddr(RetValExp, FnRetType, ReturnLoc);
1142  }
1143
1144  if (RetValExp)
1145    RetValExp = MaybeCreateCXXExprWithTemporaries(RetValExp);
1146  return Owned(new (Context) ReturnStmt(ReturnLoc, RetValExp));
1147}
1148
1149/// CheckAsmLValue - GNU C has an extremely ugly extension whereby they silently
1150/// ignore "noop" casts in places where an lvalue is required by an inline asm.
1151/// We emulate this behavior when -fheinous-gnu-extensions is specified, but
1152/// provide a strong guidance to not use it.
1153///
1154/// This method checks to see if the argument is an acceptable l-value and
1155/// returns false if it is a case we can handle.
1156static bool CheckAsmLValue(const Expr *E, Sema &S) {
1157  if (E->isLvalue(S.Context) == Expr::LV_Valid)
1158    return false;  // Cool, this is an lvalue.
1159
1160  // Okay, this is not an lvalue, but perhaps it is the result of a cast that we
1161  // are supposed to allow.
1162  const Expr *E2 = E->IgnoreParenNoopCasts(S.Context);
1163  if (E != E2 && E2->isLvalue(S.Context) == Expr::LV_Valid) {
1164    if (!S.getLangOptions().HeinousExtensions)
1165      S.Diag(E2->getLocStart(), diag::err_invalid_asm_cast_lvalue)
1166        << E->getSourceRange();
1167    else
1168      S.Diag(E2->getLocStart(), diag::warn_invalid_asm_cast_lvalue)
1169        << E->getSourceRange();
1170    // Accept, even if we emitted an error diagnostic.
1171    return false;
1172  }
1173
1174  // None of the above, just randomly invalid non-lvalue.
1175  return true;
1176}
1177
1178
1179Sema::OwningStmtResult Sema::ActOnAsmStmt(SourceLocation AsmLoc,
1180                                          bool IsSimple,
1181                                          bool IsVolatile,
1182                                          unsigned NumOutputs,
1183                                          unsigned NumInputs,
1184                                          std::string *Names,
1185                                          MultiExprArg constraints,
1186                                          MultiExprArg exprs,
1187                                          ExprArg asmString,
1188                                          MultiExprArg clobbers,
1189                                          SourceLocation RParenLoc) {
1190  unsigned NumClobbers = clobbers.size();
1191  StringLiteral **Constraints =
1192    reinterpret_cast<StringLiteral**>(constraints.get());
1193  Expr **Exprs = reinterpret_cast<Expr **>(exprs.get());
1194  StringLiteral *AsmString = cast<StringLiteral>((Expr *)asmString.get());
1195  StringLiteral **Clobbers = reinterpret_cast<StringLiteral**>(clobbers.get());
1196
1197  llvm::SmallVector<TargetInfo::ConstraintInfo, 4> OutputConstraintInfos;
1198
1199  // The parser verifies that there is a string literal here.
1200  if (AsmString->isWide())
1201    return StmtError(Diag(AsmString->getLocStart(),diag::err_asm_wide_character)
1202      << AsmString->getSourceRange());
1203
1204  for (unsigned i = 0; i != NumOutputs; i++) {
1205    StringLiteral *Literal = Constraints[i];
1206    if (Literal->isWide())
1207      return StmtError(Diag(Literal->getLocStart(),diag::err_asm_wide_character)
1208        << Literal->getSourceRange());
1209
1210    TargetInfo::ConstraintInfo Info(Literal->getStrData(),
1211                                    Literal->getByteLength(),
1212                                    Names[i]);
1213    if (!Context.Target.validateOutputConstraint(Info))
1214      return StmtError(Diag(Literal->getLocStart(),
1215                            diag::err_asm_invalid_output_constraint)
1216                       << Info.getConstraintStr());
1217
1218    // Check that the output exprs are valid lvalues.
1219    Expr *OutputExpr = Exprs[i];
1220    if (CheckAsmLValue(OutputExpr, *this)) {
1221      return StmtError(Diag(OutputExpr->getLocStart(),
1222                  diag::err_asm_invalid_lvalue_in_output)
1223        << OutputExpr->getSourceRange());
1224    }
1225
1226    OutputConstraintInfos.push_back(Info);
1227  }
1228
1229  llvm::SmallVector<TargetInfo::ConstraintInfo, 4> InputConstraintInfos;
1230
1231  for (unsigned i = NumOutputs, e = NumOutputs + NumInputs; i != e; i++) {
1232    StringLiteral *Literal = Constraints[i];
1233    if (Literal->isWide())
1234      return StmtError(Diag(Literal->getLocStart(),diag::err_asm_wide_character)
1235        << Literal->getSourceRange());
1236
1237    TargetInfo::ConstraintInfo Info(Literal->getStrData(),
1238                                    Literal->getByteLength(),
1239                                    Names[i]);
1240    if (!Context.Target.validateInputConstraint(OutputConstraintInfos.data(),
1241                                                NumOutputs, Info)) {
1242      return StmtError(Diag(Literal->getLocStart(),
1243                            diag::err_asm_invalid_input_constraint)
1244                       << Info.getConstraintStr());
1245    }
1246
1247    Expr *InputExpr = Exprs[i];
1248
1249    // Only allow void types for memory constraints.
1250    if (Info.allowsMemory() && !Info.allowsRegister()) {
1251      if (CheckAsmLValue(InputExpr, *this))
1252        return StmtError(Diag(InputExpr->getLocStart(),
1253                              diag::err_asm_invalid_lvalue_in_input)
1254                         << Info.getConstraintStr()
1255                         << InputExpr->getSourceRange());
1256    }
1257
1258    if (Info.allowsRegister()) {
1259      if (InputExpr->getType()->isVoidType()) {
1260        return StmtError(Diag(InputExpr->getLocStart(),
1261                              diag::err_asm_invalid_type_in_input)
1262          << InputExpr->getType() << Info.getConstraintStr()
1263          << InputExpr->getSourceRange());
1264      }
1265    }
1266
1267    DefaultFunctionArrayConversion(Exprs[i]);
1268
1269    InputConstraintInfos.push_back(Info);
1270  }
1271
1272  // Check that the clobbers are valid.
1273  for (unsigned i = 0; i != NumClobbers; i++) {
1274    StringLiteral *Literal = Clobbers[i];
1275    if (Literal->isWide())
1276      return StmtError(Diag(Literal->getLocStart(),diag::err_asm_wide_character)
1277        << Literal->getSourceRange());
1278
1279    std::string Clobber(Literal->getStrData(),
1280                        Literal->getStrData() +
1281                        Literal->getByteLength());
1282
1283    if (!Context.Target.isValidGCCRegisterName(Clobber.c_str()))
1284      return StmtError(Diag(Literal->getLocStart(),
1285                  diag::err_asm_unknown_register_name) << Clobber);
1286  }
1287
1288  constraints.release();
1289  exprs.release();
1290  asmString.release();
1291  clobbers.release();
1292  AsmStmt *NS =
1293    new (Context) AsmStmt(AsmLoc, IsSimple, IsVolatile, NumOutputs, NumInputs,
1294                          Names, Constraints, Exprs, AsmString, NumClobbers,
1295                          Clobbers, RParenLoc);
1296  // Validate the asm string, ensuring it makes sense given the operands we
1297  // have.
1298  llvm::SmallVector<AsmStmt::AsmStringPiece, 8> Pieces;
1299  unsigned DiagOffs;
1300  if (unsigned DiagID = NS->AnalyzeAsmString(Pieces, Context, DiagOffs)) {
1301    Diag(getLocationOfStringLiteralByte(AsmString, DiagOffs), DiagID)
1302           << AsmString->getSourceRange();
1303    DeleteStmt(NS);
1304    return StmtError();
1305  }
1306
1307  // Validate tied input operands for type mismatches.
1308  for (unsigned i = 0, e = InputConstraintInfos.size(); i != e; ++i) {
1309    TargetInfo::ConstraintInfo &Info = InputConstraintInfos[i];
1310
1311    // If this is a tied constraint, verify that the output and input have
1312    // either exactly the same type, or that they are int/ptr operands with the
1313    // same size (int/long, int*/long, are ok etc).
1314    if (!Info.hasTiedOperand()) continue;
1315
1316    unsigned TiedTo = Info.getTiedOperand();
1317    Expr *OutputExpr = Exprs[TiedTo];
1318    Expr *InputExpr = Exprs[i+NumOutputs];
1319    QualType InTy = InputExpr->getType();
1320    QualType OutTy = OutputExpr->getType();
1321    if (Context.hasSameType(InTy, OutTy))
1322      continue;  // All types can be tied to themselves.
1323
1324    // Int/ptr operands have some special cases that we allow.
1325    if ((OutTy->isIntegerType() || OutTy->isPointerType()) &&
1326        (InTy->isIntegerType() || InTy->isPointerType())) {
1327
1328      // They are ok if they are the same size.  Tying void* to int is ok if
1329      // they are the same size, for example.  This also allows tying void* to
1330      // int*.
1331      uint64_t OutSize = Context.getTypeSize(OutTy);
1332      uint64_t InSize = Context.getTypeSize(InTy);
1333      if (OutSize == InSize)
1334        continue;
1335
1336      // If the smaller input/output operand is not mentioned in the asm string,
1337      // then we can promote it and the asm string won't notice.  Check this
1338      // case now.
1339      bool SmallerValueMentioned = false;
1340      for (unsigned p = 0, e = Pieces.size(); p != e; ++p) {
1341        AsmStmt::AsmStringPiece &Piece = Pieces[p];
1342        if (!Piece.isOperand()) continue;
1343
1344        // If this is a reference to the input and if the input was the smaller
1345        // one, then we have to reject this asm.
1346        if (Piece.getOperandNo() == i+NumOutputs) {
1347          if (InSize < OutSize) {
1348            SmallerValueMentioned = true;
1349            break;
1350          }
1351        }
1352
1353        // If this is a reference to the input and if the input was the smaller
1354        // one, then we have to reject this asm.
1355        if (Piece.getOperandNo() == TiedTo) {
1356          if (InSize > OutSize) {
1357            SmallerValueMentioned = true;
1358            break;
1359          }
1360        }
1361      }
1362
1363      // If the smaller value wasn't mentioned in the asm string, and if the
1364      // output was a register, just extend the shorter one to the size of the
1365      // larger one.
1366      if (!SmallerValueMentioned &&
1367          OutputConstraintInfos[TiedTo].allowsRegister())
1368        continue;
1369    }
1370
1371    Diag(InputExpr->getLocStart(),
1372         diag::err_asm_tying_incompatible_types)
1373      << InTy << OutTy << OutputExpr->getSourceRange()
1374      << InputExpr->getSourceRange();
1375    DeleteStmt(NS);
1376    return StmtError();
1377  }
1378
1379  return Owned(NS);
1380}
1381
1382Action::OwningStmtResult
1383Sema::ActOnObjCAtCatchStmt(SourceLocation AtLoc,
1384                           SourceLocation RParen, DeclPtrTy Parm,
1385                           StmtArg Body, StmtArg catchList) {
1386  Stmt *CatchList = catchList.takeAs<Stmt>();
1387  ParmVarDecl *PVD = cast_or_null<ParmVarDecl>(Parm.getAs<Decl>());
1388
1389  // PVD == 0 implies @catch(...).
1390  if (PVD) {
1391    // If we already know the decl is invalid, reject it.
1392    if (PVD->isInvalidDecl())
1393      return StmtError();
1394
1395    if (!PVD->getType()->isObjCObjectPointerType())
1396      return StmtError(Diag(PVD->getLocation(),
1397                       diag::err_catch_param_not_objc_type));
1398    if (PVD->getType()->isObjCQualifiedIdType())
1399      return StmtError(Diag(PVD->getLocation(),
1400                       diag::err_illegal_qualifiers_on_catch_parm));
1401  }
1402
1403  ObjCAtCatchStmt *CS = new (Context) ObjCAtCatchStmt(AtLoc, RParen,
1404    PVD, Body.takeAs<Stmt>(), CatchList);
1405  return Owned(CatchList ? CatchList : CS);
1406}
1407
1408Action::OwningStmtResult
1409Sema::ActOnObjCAtFinallyStmt(SourceLocation AtLoc, StmtArg Body) {
1410  return Owned(new (Context) ObjCAtFinallyStmt(AtLoc,
1411                                           static_cast<Stmt*>(Body.release())));
1412}
1413
1414Action::OwningStmtResult
1415Sema::ActOnObjCAtTryStmt(SourceLocation AtLoc,
1416                         StmtArg Try, StmtArg Catch, StmtArg Finally) {
1417  CurFunctionNeedsScopeChecking = true;
1418  return Owned(new (Context) ObjCAtTryStmt(AtLoc, Try.takeAs<Stmt>(),
1419                                           Catch.takeAs<Stmt>(),
1420                                           Finally.takeAs<Stmt>()));
1421}
1422
1423Action::OwningStmtResult
1424Sema::ActOnObjCAtThrowStmt(SourceLocation AtLoc, ExprArg expr,Scope *CurScope) {
1425  Expr *ThrowExpr = expr.takeAs<Expr>();
1426  if (!ThrowExpr) {
1427    // @throw without an expression designates a rethrow (which much occur
1428    // in the context of an @catch clause).
1429    Scope *AtCatchParent = CurScope;
1430    while (AtCatchParent && !AtCatchParent->isAtCatchScope())
1431      AtCatchParent = AtCatchParent->getParent();
1432    if (!AtCatchParent)
1433      return StmtError(Diag(AtLoc, diag::error_rethrow_used_outside_catch));
1434  } else {
1435    QualType ThrowType = ThrowExpr->getType();
1436    // Make sure the expression type is an ObjC pointer or "void *".
1437    if (!ThrowType->isObjCObjectPointerType()) {
1438      const PointerType *PT = ThrowType->getAs<PointerType>();
1439      if (!PT || !PT->getPointeeType()->isVoidType())
1440        return StmtError(Diag(AtLoc, diag::error_objc_throw_expects_object)
1441                        << ThrowExpr->getType() << ThrowExpr->getSourceRange());
1442    }
1443  }
1444  return Owned(new (Context) ObjCAtThrowStmt(AtLoc, ThrowExpr));
1445}
1446
1447Action::OwningStmtResult
1448Sema::ActOnObjCAtSynchronizedStmt(SourceLocation AtLoc, ExprArg SynchExpr,
1449                                  StmtArg SynchBody) {
1450  CurFunctionNeedsScopeChecking = true;
1451
1452  // Make sure the expression type is an ObjC pointer or "void *".
1453  Expr *SyncExpr = static_cast<Expr*>(SynchExpr.get());
1454  if (!SyncExpr->getType()->isObjCObjectPointerType()) {
1455    const PointerType *PT = SyncExpr->getType()->getAs<PointerType>();
1456    if (!PT || !PT->getPointeeType()->isVoidType())
1457      return StmtError(Diag(AtLoc, diag::error_objc_synchronized_expects_object)
1458                       << SyncExpr->getType() << SyncExpr->getSourceRange());
1459  }
1460
1461  return Owned(new (Context) ObjCAtSynchronizedStmt(AtLoc,
1462                                                    SynchExpr.takeAs<Stmt>(),
1463                                                    SynchBody.takeAs<Stmt>()));
1464}
1465
1466/// ActOnCXXCatchBlock - Takes an exception declaration and a handler block
1467/// and creates a proper catch handler from them.
1468Action::OwningStmtResult
1469Sema::ActOnCXXCatchBlock(SourceLocation CatchLoc, DeclPtrTy ExDecl,
1470                         StmtArg HandlerBlock) {
1471  // There's nothing to test that ActOnExceptionDecl didn't already test.
1472  return Owned(new (Context) CXXCatchStmt(CatchLoc,
1473                                  cast_or_null<VarDecl>(ExDecl.getAs<Decl>()),
1474                                          HandlerBlock.takeAs<Stmt>()));
1475}
1476
1477class TypeWithHandler {
1478  QualType t;
1479  CXXCatchStmt *stmt;
1480public:
1481  TypeWithHandler(const QualType &type, CXXCatchStmt *statement)
1482  : t(type), stmt(statement) {}
1483
1484  // An arbitrary order is fine as long as it places identical
1485  // types next to each other.
1486  bool operator<(const TypeWithHandler &y) const {
1487    if (t.getAsOpaquePtr() < y.t.getAsOpaquePtr())
1488      return true;
1489    if (t.getAsOpaquePtr() > y.t.getAsOpaquePtr())
1490      return false;
1491    else
1492      return getTypeSpecStartLoc() < y.getTypeSpecStartLoc();
1493  }
1494
1495  bool operator==(const TypeWithHandler& other) const {
1496    return t == other.t;
1497  }
1498
1499  QualType getQualType() const { return t; }
1500  CXXCatchStmt *getCatchStmt() const { return stmt; }
1501  SourceLocation getTypeSpecStartLoc() const {
1502    return stmt->getExceptionDecl()->getTypeSpecStartLoc();
1503  }
1504};
1505
1506/// ActOnCXXTryBlock - Takes a try compound-statement and a number of
1507/// handlers and creates a try statement from them.
1508Action::OwningStmtResult
1509Sema::ActOnCXXTryBlock(SourceLocation TryLoc, StmtArg TryBlock,
1510                       MultiStmtArg RawHandlers) {
1511  unsigned NumHandlers = RawHandlers.size();
1512  assert(NumHandlers > 0 &&
1513         "The parser shouldn't call this if there are no handlers.");
1514  Stmt **Handlers = reinterpret_cast<Stmt**>(RawHandlers.get());
1515
1516  llvm::SmallVector<TypeWithHandler, 8> TypesWithHandlers;
1517
1518  for (unsigned i = 0; i < NumHandlers; ++i) {
1519    CXXCatchStmt *Handler = llvm::cast<CXXCatchStmt>(Handlers[i]);
1520    if (!Handler->getExceptionDecl()) {
1521      if (i < NumHandlers - 1)
1522        return StmtError(Diag(Handler->getLocStart(),
1523                              diag::err_early_catch_all));
1524
1525      continue;
1526    }
1527
1528    const QualType CaughtType = Handler->getCaughtType();
1529    const QualType CanonicalCaughtType = Context.getCanonicalType(CaughtType);
1530    TypesWithHandlers.push_back(TypeWithHandler(CanonicalCaughtType, Handler));
1531  }
1532
1533  // Detect handlers for the same type as an earlier one.
1534  if (NumHandlers > 1) {
1535    llvm::array_pod_sort(TypesWithHandlers.begin(), TypesWithHandlers.end());
1536
1537    TypeWithHandler prev = TypesWithHandlers[0];
1538    for (unsigned i = 1; i < TypesWithHandlers.size(); ++i) {
1539      TypeWithHandler curr = TypesWithHandlers[i];
1540
1541      if (curr == prev) {
1542        Diag(curr.getTypeSpecStartLoc(),
1543             diag::warn_exception_caught_by_earlier_handler)
1544          << curr.getCatchStmt()->getCaughtType().getAsString();
1545        Diag(prev.getTypeSpecStartLoc(),
1546             diag::note_previous_exception_handler)
1547          << prev.getCatchStmt()->getCaughtType().getAsString();
1548      }
1549
1550      prev = curr;
1551    }
1552  }
1553
1554  // FIXME: We should detect handlers that cannot catch anything because an
1555  // earlier handler catches a superclass. Need to find a method that is not
1556  // quadratic for this.
1557  // Neither of these are explicitly forbidden, but every compiler detects them
1558  // and warns.
1559
1560  CurFunctionNeedsScopeChecking = true;
1561  RawHandlers.release();
1562  return Owned(new (Context) CXXTryStmt(TryLoc,
1563                                        static_cast<Stmt*>(TryBlock.release()),
1564                                        Handlers, NumHandlers));
1565}
1566