SemaStmt.cpp revision 04a67a6aa3dfdc92d57f7f8d93ba397348c868a4 
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 UnresolvedSetImpl *Conversions
416      = cast<CXXRecordDecl>(RecordTy->getDecl())
417                                             ->getVisibleConversionFunctions();
418    for (UnresolvedSetImpl::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
485/// ActOnSwitchBodyError - This is called if there is an error parsing the
486/// body of the switch stmt instead of ActOnFinishSwitchStmt.
487void Sema::ActOnSwitchBodyError(SourceLocation SwitchLoc, StmtArg Switch,
488                                StmtArg Body) {
489  // Keep the switch stack balanced.
490  assert(getSwitchStack().back() == (SwitchStmt*)Switch.get() &&
491         "switch stack missing push/pop!");
492  getSwitchStack().pop_back();
493}
494
495Action::OwningStmtResult
496Sema::ActOnFinishSwitchStmt(SourceLocation SwitchLoc, StmtArg Switch,
497                            StmtArg Body) {
498  Stmt *BodyStmt = Body.takeAs<Stmt>();
499
500  SwitchStmt *SS = getSwitchStack().back();
501  assert(SS == (SwitchStmt*)Switch.get() && "switch stack missing push/pop!");
502
503  SS->setBody(BodyStmt, SwitchLoc);
504  getSwitchStack().pop_back();
505
506  if (SS->getCond() == 0) {
507    SS->Destroy(Context);
508    return StmtError();
509  }
510
511  Expr *CondExpr = SS->getCond();
512  QualType CondTypeBeforePromotion =
513      GetTypeBeforeIntegralPromotion(CondExpr);
514
515  if (getLangOptions().CPlusPlus &&
516      CheckCXXSwitchCondition(*this, SwitchLoc, CondExpr))
517    return StmtError();
518
519  // C99 6.8.4.2p5 - Integer promotions are performed on the controlling expr.
520  UsualUnaryConversions(CondExpr);
521  QualType CondType = CondExpr->getType();
522  SS->setCond(CondExpr);
523
524  // C++ 6.4.2.p2:
525  // Integral promotions are performed (on the switch condition).
526  //
527  // A case value unrepresentable by the original switch condition
528  // type (before the promotion) doesn't make sense, even when it can
529  // be represented by the promoted type.  Therefore we need to find
530  // the pre-promotion type of the switch condition.
531  if (!CondExpr->isTypeDependent()) {
532    if (!CondType->isIntegerType()) { // C99 6.8.4.2p1
533      Diag(SwitchLoc, diag::err_typecheck_statement_requires_integer)
534          << CondType << CondExpr->getSourceRange();
535      return StmtError();
536    }
537
538    if (CondTypeBeforePromotion->isBooleanType()) {
539      // switch(bool_expr) {...} is often a programmer error, e.g.
540      //   switch(n && mask) { ... }  // Doh - should be "n & mask".
541      // One can always use an if statement instead of switch(bool_expr).
542      Diag(SwitchLoc, diag::warn_bool_switch_condition)
543          << CondExpr->getSourceRange();
544    }
545  }
546
547  // Get the bitwidth of the switched-on value before promotions.  We must
548  // convert the integer case values to this width before comparison.
549  bool HasDependentValue
550    = CondExpr->isTypeDependent() || CondExpr->isValueDependent();
551  unsigned CondWidth
552    = HasDependentValue? 0
553      : static_cast<unsigned>(Context.getTypeSize(CondTypeBeforePromotion));
554  bool CondIsSigned = CondTypeBeforePromotion->isSignedIntegerType();
555
556  // Accumulate all of the case values in a vector so that we can sort them
557  // and detect duplicates.  This vector contains the APInt for the case after
558  // it has been converted to the condition type.
559  typedef llvm::SmallVector<std::pair<llvm::APSInt, CaseStmt*>, 64> CaseValsTy;
560  CaseValsTy CaseVals;
561
562  // Keep track of any GNU case ranges we see.  The APSInt is the low value.
563  std::vector<std::pair<llvm::APSInt, CaseStmt*> > CaseRanges;
564
565  DefaultStmt *TheDefaultStmt = 0;
566
567  bool CaseListIsErroneous = false;
568
569  for (SwitchCase *SC = SS->getSwitchCaseList(); SC && !HasDependentValue;
570       SC = SC->getNextSwitchCase()) {
571
572    if (DefaultStmt *DS = dyn_cast<DefaultStmt>(SC)) {
573      if (TheDefaultStmt) {
574        Diag(DS->getDefaultLoc(), diag::err_multiple_default_labels_defined);
575        Diag(TheDefaultStmt->getDefaultLoc(), diag::note_duplicate_case_prev);
576
577        // FIXME: Remove the default statement from the switch block so that
578        // we'll return a valid AST.  This requires recursing down the AST and
579        // finding it, not something we are set up to do right now.  For now,
580        // just lop the entire switch stmt out of the AST.
581        CaseListIsErroneous = true;
582      }
583      TheDefaultStmt = DS;
584
585    } else {
586      CaseStmt *CS = cast<CaseStmt>(SC);
587
588      // We already verified that the expression has a i-c-e value (C99
589      // 6.8.4.2p3) - get that value now.
590      Expr *Lo = CS->getLHS();
591
592      if (Lo->isTypeDependent() || Lo->isValueDependent()) {
593        HasDependentValue = true;
594        break;
595      }
596
597      llvm::APSInt LoVal = Lo->EvaluateAsInt(Context);
598
599      // Convert the value to the same width/sign as the condition.
600      ConvertIntegerToTypeWarnOnOverflow(LoVal, CondWidth, CondIsSigned,
601                                         CS->getLHS()->getLocStart(),
602                                         diag::warn_case_value_overflow);
603
604      // If the LHS is not the same type as the condition, insert an implicit
605      // cast.
606      ImpCastExprToType(Lo, CondType, CastExpr::CK_IntegralCast);
607      CS->setLHS(Lo);
608
609      // If this is a case range, remember it in CaseRanges, otherwise CaseVals.
610      if (CS->getRHS()) {
611        if (CS->getRHS()->isTypeDependent() ||
612            CS->getRHS()->isValueDependent()) {
613          HasDependentValue = true;
614          break;
615        }
616        CaseRanges.push_back(std::make_pair(LoVal, CS));
617      } else
618        CaseVals.push_back(std::make_pair(LoVal, CS));
619    }
620  }
621
622  if (!HasDependentValue) {
623    // Sort all the scalar case values so we can easily detect duplicates.
624    std::stable_sort(CaseVals.begin(), CaseVals.end(), CmpCaseVals);
625
626    if (!CaseVals.empty()) {
627      for (unsigned i = 0, e = CaseVals.size()-1; i != e; ++i) {
628        if (CaseVals[i].first == CaseVals[i+1].first) {
629          // If we have a duplicate, report it.
630          Diag(CaseVals[i+1].second->getLHS()->getLocStart(),
631               diag::err_duplicate_case) << CaseVals[i].first.toString(10);
632          Diag(CaseVals[i].second->getLHS()->getLocStart(),
633               diag::note_duplicate_case_prev);
634          // FIXME: We really want to remove the bogus case stmt from the
635          // substmt, but we have no way to do this right now.
636          CaseListIsErroneous = true;
637        }
638      }
639    }
640
641    // Detect duplicate case ranges, which usually don't exist at all in
642    // the first place.
643    if (!CaseRanges.empty()) {
644      // Sort all the case ranges by their low value so we can easily detect
645      // overlaps between ranges.
646      std::stable_sort(CaseRanges.begin(), CaseRanges.end());
647
648      // Scan the ranges, computing the high values and removing empty ranges.
649      std::vector<llvm::APSInt> HiVals;
650      for (unsigned i = 0, e = CaseRanges.size(); i != e; ++i) {
651        CaseStmt *CR = CaseRanges[i].second;
652        Expr *Hi = CR->getRHS();
653        llvm::APSInt HiVal = Hi->EvaluateAsInt(Context);
654
655        // Convert the value to the same width/sign as the condition.
656        ConvertIntegerToTypeWarnOnOverflow(HiVal, CondWidth, CondIsSigned,
657                                           CR->getRHS()->getLocStart(),
658                                           diag::warn_case_value_overflow);
659
660        // If the LHS is not the same type as the condition, insert an implicit
661        // cast.
662        ImpCastExprToType(Hi, CondType, CastExpr::CK_IntegralCast);
663        CR->setRHS(Hi);
664
665        // If the low value is bigger than the high value, the case is empty.
666        if (CaseRanges[i].first > HiVal) {
667          Diag(CR->getLHS()->getLocStart(), diag::warn_case_empty_range)
668            << SourceRange(CR->getLHS()->getLocStart(),
669                           CR->getRHS()->getLocEnd());
670          CaseRanges.erase(CaseRanges.begin()+i);
671          --i, --e;
672          continue;
673        }
674        HiVals.push_back(HiVal);
675      }
676
677      // Rescan the ranges, looking for overlap with singleton values and other
678      // ranges.  Since the range list is sorted, we only need to compare case
679      // ranges with their neighbors.
680      for (unsigned i = 0, e = CaseRanges.size(); i != e; ++i) {
681        llvm::APSInt &CRLo = CaseRanges[i].first;
682        llvm::APSInt &CRHi = HiVals[i];
683        CaseStmt *CR = CaseRanges[i].second;
684
685        // Check to see whether the case range overlaps with any
686        // singleton cases.
687        CaseStmt *OverlapStmt = 0;
688        llvm::APSInt OverlapVal(32);
689
690        // Find the smallest value >= the lower bound.  If I is in the
691        // case range, then we have overlap.
692        CaseValsTy::iterator I = std::lower_bound(CaseVals.begin(),
693                                                  CaseVals.end(), CRLo,
694                                                  CaseCompareFunctor());
695        if (I != CaseVals.end() && I->first < CRHi) {
696          OverlapVal  = I->first;   // Found overlap with scalar.
697          OverlapStmt = I->second;
698        }
699
700        // Find the smallest value bigger than the upper bound.
701        I = std::upper_bound(I, CaseVals.end(), CRHi, CaseCompareFunctor());
702        if (I != CaseVals.begin() && (I-1)->first >= CRLo) {
703          OverlapVal  = (I-1)->first;      // Found overlap with scalar.
704          OverlapStmt = (I-1)->second;
705        }
706
707        // Check to see if this case stmt overlaps with the subsequent
708        // case range.
709        if (i && CRLo <= HiVals[i-1]) {
710          OverlapVal  = HiVals[i-1];       // Found overlap with range.
711          OverlapStmt = CaseRanges[i-1].second;
712        }
713
714        if (OverlapStmt) {
715          // If we have a duplicate, report it.
716          Diag(CR->getLHS()->getLocStart(), diag::err_duplicate_case)
717            << OverlapVal.toString(10);
718          Diag(OverlapStmt->getLHS()->getLocStart(),
719               diag::note_duplicate_case_prev);
720          // FIXME: We really want to remove the bogus case stmt from the
721          // substmt, but we have no way to do this right now.
722          CaseListIsErroneous = true;
723        }
724      }
725    }
726  }
727
728  // FIXME: If the case list was broken is some way, we don't have a good system
729  // to patch it up.  Instead, just return the whole substmt as broken.
730  if (CaseListIsErroneous)
731    return StmtError();
732
733  Switch.release();
734  return Owned(SS);
735}
736
737Action::OwningStmtResult
738Sema::ActOnWhileStmt(SourceLocation WhileLoc, FullExprArg Cond,
739                     DeclPtrTy CondVar, StmtArg Body) {
740  OwningExprResult CondResult(Cond.release());
741
742  VarDecl *ConditionVar = 0;
743  if (CondVar.get()) {
744    ConditionVar = CondVar.getAs<VarDecl>();
745    CondResult = CheckConditionVariable(ConditionVar);
746    if (CondResult.isInvalid())
747      return StmtError();
748  }
749  Expr *ConditionExpr = CondResult.takeAs<Expr>();
750  if (!ConditionExpr)
751    return StmtError();
752
753  if (CheckBooleanCondition(ConditionExpr, WhileLoc)) {
754    CondResult = ConditionExpr;
755    return StmtError();
756  }
757
758  Stmt *bodyStmt = Body.takeAs<Stmt>();
759  DiagnoseUnusedExprResult(bodyStmt);
760
761  CondResult.release();
762  return Owned(new (Context) WhileStmt(ConditionVar, ConditionExpr, bodyStmt,
763                                       WhileLoc));
764}
765
766Action::OwningStmtResult
767Sema::ActOnDoStmt(SourceLocation DoLoc, StmtArg Body,
768                  SourceLocation WhileLoc, SourceLocation CondLParen,
769                  ExprArg Cond, SourceLocation CondRParen) {
770  Expr *condExpr = Cond.takeAs<Expr>();
771  assert(condExpr && "ActOnDoStmt(): missing expression");
772
773  if (CheckBooleanCondition(condExpr, DoLoc)) {
774    Cond = condExpr;
775    return StmtError();
776  }
777
778  Stmt *bodyStmt = Body.takeAs<Stmt>();
779  DiagnoseUnusedExprResult(bodyStmt);
780
781  Cond.release();
782  return Owned(new (Context) DoStmt(bodyStmt, condExpr, DoLoc,
783                                    WhileLoc, CondRParen));
784}
785
786Action::OwningStmtResult
787Sema::ActOnForStmt(SourceLocation ForLoc, SourceLocation LParenLoc,
788                   StmtArg first, FullExprArg second, DeclPtrTy secondVar,
789                   FullExprArg third,
790                   SourceLocation RParenLoc, StmtArg body) {
791  Stmt *First  = static_cast<Stmt*>(first.get());
792
793  if (!getLangOptions().CPlusPlus) {
794    if (DeclStmt *DS = dyn_cast_or_null<DeclStmt>(First)) {
795      // C99 6.8.5p3: The declaration part of a 'for' statement shall only
796      // declare identifiers for objects having storage class 'auto' or
797      // 'register'.
798      for (DeclStmt::decl_iterator DI=DS->decl_begin(), DE=DS->decl_end();
799           DI!=DE; ++DI) {
800        VarDecl *VD = dyn_cast<VarDecl>(*DI);
801        if (VD && VD->isBlockVarDecl() && !VD->hasLocalStorage())
802          VD = 0;
803        if (VD == 0)
804          Diag((*DI)->getLocation(), diag::err_non_variable_decl_in_for);
805        // FIXME: mark decl erroneous!
806      }
807    }
808  }
809
810  OwningExprResult SecondResult(second.release());
811  VarDecl *ConditionVar = 0;
812  if (secondVar.get()) {
813    ConditionVar = secondVar.getAs<VarDecl>();
814    SecondResult = CheckConditionVariable(ConditionVar);
815    if (SecondResult.isInvalid())
816      return StmtError();
817  }
818
819  Expr *Second = SecondResult.takeAs<Expr>();
820  if (Second && CheckBooleanCondition(Second, ForLoc)) {
821    SecondResult = Second;
822    return StmtError();
823  }
824
825  Expr *Third  = third.release().takeAs<Expr>();
826  Stmt *Body  = static_cast<Stmt*>(body.get());
827
828  DiagnoseUnusedExprResult(First);
829  DiagnoseUnusedExprResult(Third);
830  DiagnoseUnusedExprResult(Body);
831
832  first.release();
833  body.release();
834  return Owned(new (Context) ForStmt(First, Second, ConditionVar, Third, Body,
835                                     ForLoc, LParenLoc, RParenLoc));
836}
837
838Action::OwningStmtResult
839Sema::ActOnObjCForCollectionStmt(SourceLocation ForLoc,
840                                 SourceLocation LParenLoc,
841                                 StmtArg first, ExprArg second,
842                                 SourceLocation RParenLoc, StmtArg body) {
843  Stmt *First  = static_cast<Stmt*>(first.get());
844  Expr *Second = static_cast<Expr*>(second.get());
845  Stmt *Body  = static_cast<Stmt*>(body.get());
846  if (First) {
847    QualType FirstType;
848    if (DeclStmt *DS = dyn_cast<DeclStmt>(First)) {
849      if (!DS->isSingleDecl())
850        return StmtError(Diag((*DS->decl_begin())->getLocation(),
851                         diag::err_toomany_element_decls));
852
853      Decl *D = DS->getSingleDecl();
854      FirstType = cast<ValueDecl>(D)->getType();
855      // C99 6.8.5p3: The declaration part of a 'for' statement shall only
856      // declare identifiers for objects having storage class 'auto' or
857      // 'register'.
858      VarDecl *VD = cast<VarDecl>(D);
859      if (VD->isBlockVarDecl() && !VD->hasLocalStorage())
860        return StmtError(Diag(VD->getLocation(),
861                              diag::err_non_variable_decl_in_for));
862    } else {
863      if (cast<Expr>(First)->isLvalue(Context) != Expr::LV_Valid)
864        return StmtError(Diag(First->getLocStart(),
865                   diag::err_selector_element_not_lvalue)
866          << First->getSourceRange());
867
868      FirstType = static_cast<Expr*>(First)->getType();
869    }
870    if (!FirstType->isObjCObjectPointerType() &&
871        !FirstType->isBlockPointerType())
872        Diag(ForLoc, diag::err_selector_element_type)
873          << FirstType << First->getSourceRange();
874  }
875  if (Second) {
876    DefaultFunctionArrayLvalueConversion(Second);
877    QualType SecondType = Second->getType();
878    if (!SecondType->isObjCObjectPointerType())
879      Diag(ForLoc, diag::err_collection_expr_type)
880        << SecondType << Second->getSourceRange();
881  }
882  first.release();
883  second.release();
884  body.release();
885  return Owned(new (Context) ObjCForCollectionStmt(First, Second, Body,
886                                                   ForLoc, RParenLoc));
887}
888
889Action::OwningStmtResult
890Sema::ActOnGotoStmt(SourceLocation GotoLoc, SourceLocation LabelLoc,
891                    IdentifierInfo *LabelII) {
892  // Look up the record for this label identifier.
893  LabelStmt *&LabelDecl = getLabelMap()[LabelII];
894
895  // If we haven't seen this label yet, create a forward reference.
896  if (LabelDecl == 0)
897    LabelDecl = new (Context) LabelStmt(LabelLoc, LabelII, 0);
898
899  return Owned(new (Context) GotoStmt(LabelDecl, GotoLoc, LabelLoc));
900}
901
902Action::OwningStmtResult
903Sema::ActOnIndirectGotoStmt(SourceLocation GotoLoc, SourceLocation StarLoc,
904                            ExprArg DestExp) {
905  // Convert operand to void*
906  Expr* E = DestExp.takeAs<Expr>();
907  if (!E->isTypeDependent()) {
908    QualType ETy = E->getType();
909    QualType DestTy = Context.getPointerType(Context.VoidTy.withConst());
910    AssignConvertType ConvTy =
911      CheckSingleAssignmentConstraints(DestTy, E);
912    if (DiagnoseAssignmentResult(ConvTy, StarLoc, DestTy, ETy, E, AA_Passing))
913      return StmtError();
914  }
915  return Owned(new (Context) IndirectGotoStmt(GotoLoc, StarLoc, E));
916}
917
918Action::OwningStmtResult
919Sema::ActOnContinueStmt(SourceLocation ContinueLoc, Scope *CurScope) {
920  Scope *S = CurScope->getContinueParent();
921  if (!S) {
922    // C99 6.8.6.2p1: A break shall appear only in or as a loop body.
923    return StmtError(Diag(ContinueLoc, diag::err_continue_not_in_loop));
924  }
925
926  return Owned(new (Context) ContinueStmt(ContinueLoc));
927}
928
929Action::OwningStmtResult
930Sema::ActOnBreakStmt(SourceLocation BreakLoc, Scope *CurScope) {
931  Scope *S = CurScope->getBreakParent();
932  if (!S) {
933    // C99 6.8.6.3p1: A break shall appear only in or as a switch/loop body.
934    return StmtError(Diag(BreakLoc, diag::err_break_not_in_loop_or_switch));
935  }
936
937  return Owned(new (Context) BreakStmt(BreakLoc));
938}
939
940/// ActOnBlockReturnStmt - Utility routine to figure out block's return type.
941///
942Action::OwningStmtResult
943Sema::ActOnBlockReturnStmt(SourceLocation ReturnLoc, Expr *RetValExp) {
944  // If this is the first return we've seen in the block, infer the type of
945  // the block from it.
946  if (CurBlock->ReturnType.isNull()) {
947    if (RetValExp) {
948      // Don't call UsualUnaryConversions(), since we don't want to do
949      // integer promotions here.
950      DefaultFunctionArrayLvalueConversion(RetValExp);
951      CurBlock->ReturnType = RetValExp->getType();
952      if (BlockDeclRefExpr *CDRE = dyn_cast<BlockDeclRefExpr>(RetValExp)) {
953        // We have to remove a 'const' added to copied-in variable which was
954        // part of the implementation spec. and not the actual qualifier for
955        // the variable.
956        if (CDRE->isConstQualAdded())
957           CurBlock->ReturnType.removeConst();
958      }
959    } else
960      CurBlock->ReturnType = Context.VoidTy;
961  }
962  QualType FnRetType = CurBlock->ReturnType;
963
964  if (CurBlock->TheDecl->hasAttr<NoReturnAttr>()) {
965    Diag(ReturnLoc, diag::err_noreturn_block_has_return_expr)
966      << getCurFunctionOrMethodDecl()->getDeclName();
967    return StmtError();
968  }
969
970  // Otherwise, verify that this result type matches the previous one.  We are
971  // pickier with blocks than for normal functions because we don't have GCC
972  // compatibility to worry about here.
973  if (CurBlock->ReturnType->isVoidType()) {
974    if (RetValExp) {
975      Diag(ReturnLoc, diag::err_return_block_has_expr);
976      RetValExp->Destroy(Context);
977      RetValExp = 0;
978    }
979    return Owned(new (Context) ReturnStmt(ReturnLoc, RetValExp));
980  }
981
982  if (!RetValExp)
983    return StmtError(Diag(ReturnLoc, diag::err_block_return_missing_expr));
984
985  if (!FnRetType->isDependentType() && !RetValExp->isTypeDependent()) {
986    // we have a non-void block with an expression, continue checking
987
988    // C99 6.8.6.4p3(136): The return statement is not an assignment. The
989    // overlap restriction of subclause 6.5.16.1 does not apply to the case of
990    // function return.
991
992    // In C++ the return statement is handled via a copy initialization.
993    // the C version of which boils down to CheckSingleAssignmentConstraints.
994    OwningExprResult Res = PerformCopyInitialization(
995                             InitializedEntity::InitializeResult(ReturnLoc,
996                                                                 FnRetType),
997                             SourceLocation(),
998                             Owned(RetValExp));
999    if (Res.isInvalid()) {
1000      // FIXME: Cleanup temporaries here, anyway?
1001      return StmtError();
1002    }
1003
1004    RetValExp = Res.takeAs<Expr>();
1005    if (RetValExp)
1006      CheckReturnStackAddr(RetValExp, FnRetType, ReturnLoc);
1007  }
1008
1009  return Owned(new (Context) ReturnStmt(ReturnLoc, RetValExp));
1010}
1011
1012/// IsReturnCopyElidable - Whether returning @p RetExpr from a function that
1013/// returns a @p RetType fulfills the criteria for copy elision (C++0x 12.8p15).
1014static bool IsReturnCopyElidable(ASTContext &Ctx, QualType RetType,
1015                                 Expr *RetExpr) {
1016  QualType ExprType = RetExpr->getType();
1017  // - in a return statement in a function with ...
1018  // ... a class return type ...
1019  if (!RetType->isRecordType())
1020    return false;
1021  // ... the same cv-unqualified type as the function return type ...
1022  if (!Ctx.hasSameUnqualifiedType(RetType, ExprType))
1023    return false;
1024  // ... the expression is the name of a non-volatile automatic object ...
1025  // We ignore parentheses here.
1026  // FIXME: Is this compliant?
1027  const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(RetExpr->IgnoreParens());
1028  if (!DR)
1029    return false;
1030  const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl());
1031  if (!VD)
1032    return false;
1033  return VD->hasLocalStorage() && !VD->getType()->isReferenceType()
1034    && !VD->getType().isVolatileQualified();
1035}
1036
1037Action::OwningStmtResult
1038Sema::ActOnReturnStmt(SourceLocation ReturnLoc, ExprArg rex) {
1039  Expr *RetValExp = rex.takeAs<Expr>();
1040  if (CurBlock)
1041    return ActOnBlockReturnStmt(ReturnLoc, RetValExp);
1042
1043  QualType FnRetType;
1044  if (const FunctionDecl *FD = getCurFunctionDecl()) {
1045    FnRetType = FD->getResultType();
1046    if (FD->hasAttr<NoReturnAttr>() ||
1047        FD->getType()->getAs<FunctionType>()->getNoReturnAttr())
1048      Diag(ReturnLoc, diag::warn_noreturn_function_has_return_expr)
1049        << getCurFunctionOrMethodDecl()->getDeclName();
1050  } else if (ObjCMethodDecl *MD = getCurMethodDecl())
1051    FnRetType = MD->getResultType();
1052  else // If we don't have a function/method context, bail.
1053    return StmtError();
1054
1055  if (FnRetType->isVoidType()) {
1056    if (RetValExp && !RetValExp->isTypeDependent()) {
1057      // C99 6.8.6.4p1 (ext_ since GCC warns)
1058      unsigned D = diag::ext_return_has_expr;
1059      if (RetValExp->getType()->isVoidType())
1060        D = diag::ext_return_has_void_expr;
1061
1062      // return (some void expression); is legal in C++.
1063      if (D != diag::ext_return_has_void_expr ||
1064          !getLangOptions().CPlusPlus) {
1065        NamedDecl *CurDecl = getCurFunctionOrMethodDecl();
1066        Diag(ReturnLoc, D)
1067          << CurDecl->getDeclName() << isa<ObjCMethodDecl>(CurDecl)
1068          << RetValExp->getSourceRange();
1069      }
1070
1071      RetValExp = MaybeCreateCXXExprWithTemporaries(RetValExp);
1072    }
1073    return Owned(new (Context) ReturnStmt(ReturnLoc, RetValExp));
1074  }
1075
1076  if (!RetValExp && !FnRetType->isDependentType()) {
1077    unsigned DiagID = diag::warn_return_missing_expr;  // C90 6.6.6.4p4
1078    // C99 6.8.6.4p1 (ext_ since GCC warns)
1079    if (getLangOptions().C99) DiagID = diag::ext_return_missing_expr;
1080
1081    if (FunctionDecl *FD = getCurFunctionDecl())
1082      Diag(ReturnLoc, DiagID) << FD->getIdentifier() << 0/*fn*/;
1083    else
1084      Diag(ReturnLoc, DiagID) << getCurMethodDecl()->getDeclName() << 1/*meth*/;
1085    return Owned(new (Context) ReturnStmt(ReturnLoc, (Expr*)0));
1086  }
1087
1088  if (!FnRetType->isDependentType() && !RetValExp->isTypeDependent()) {
1089    // we have a non-void function with an expression, continue checking
1090
1091    // C99 6.8.6.4p3(136): The return statement is not an assignment. The
1092    // overlap restriction of subclause 6.5.16.1 does not apply to the case of
1093    // function return.
1094
1095    // C++0x 12.8p15: When certain criteria are met, an implementation is
1096    //   allowed to omit the copy construction of a class object, [...]
1097    //   - in a return statement in a function with a class return type, when
1098    //     the expression is the name of a non-volatile automatic object with
1099    //     the same cv-unqualified type as the function return type, the copy
1100    //     operation can be omitted [...]
1101    // C++0x 12.8p16: When the criteria for elision of a copy operation are met
1102    //   and the object to be copied is designated by an lvalue, overload
1103    //   resolution to select the constructor for the copy is first performed
1104    //   as if the object were designated by an rvalue.
1105    // Note that we only compute Elidable if we're in C++0x, since we don't
1106    // care otherwise.
1107    bool Elidable = getLangOptions().CPlusPlus0x ?
1108                      IsReturnCopyElidable(Context, FnRetType, RetValExp) :
1109                      false;
1110    // FIXME: Elidable
1111    (void)Elidable;
1112
1113    // In C++ the return statement is handled via a copy initialization.
1114    // the C version of which boils down to CheckSingleAssignmentConstraints.
1115    OwningExprResult Res = PerformCopyInitialization(
1116                             InitializedEntity::InitializeResult(ReturnLoc,
1117                                                                 FnRetType),
1118                             SourceLocation(),
1119                             Owned(RetValExp));
1120    if (Res.isInvalid()) {
1121      // FIXME: Cleanup temporaries here, anyway?
1122      return StmtError();
1123    }
1124
1125    RetValExp = Res.takeAs<Expr>();
1126    if (RetValExp)
1127      CheckReturnStackAddr(RetValExp, FnRetType, ReturnLoc);
1128  }
1129
1130  if (RetValExp)
1131    RetValExp = MaybeCreateCXXExprWithTemporaries(RetValExp);
1132  return Owned(new (Context) ReturnStmt(ReturnLoc, RetValExp));
1133}
1134
1135/// CheckAsmLValue - GNU C has an extremely ugly extension whereby they silently
1136/// ignore "noop" casts in places where an lvalue is required by an inline asm.
1137/// We emulate this behavior when -fheinous-gnu-extensions is specified, but
1138/// provide a strong guidance to not use it.
1139///
1140/// This method checks to see if the argument is an acceptable l-value and
1141/// returns false if it is a case we can handle.
1142static bool CheckAsmLValue(const Expr *E, Sema &S) {
1143  // Type dependent expressions will be checked during instantiation.
1144  if (E->isTypeDependent())
1145    return false;
1146
1147  if (E->isLvalue(S.Context) == Expr::LV_Valid)
1148    return false;  // Cool, this is an lvalue.
1149
1150  // Okay, this is not an lvalue, but perhaps it is the result of a cast that we
1151  // are supposed to allow.
1152  const Expr *E2 = E->IgnoreParenNoopCasts(S.Context);
1153  if (E != E2 && E2->isLvalue(S.Context) == Expr::LV_Valid) {
1154    if (!S.getLangOptions().HeinousExtensions)
1155      S.Diag(E2->getLocStart(), diag::err_invalid_asm_cast_lvalue)
1156        << E->getSourceRange();
1157    else
1158      S.Diag(E2->getLocStart(), diag::warn_invalid_asm_cast_lvalue)
1159        << E->getSourceRange();
1160    // Accept, even if we emitted an error diagnostic.
1161    return false;
1162  }
1163
1164  // None of the above, just randomly invalid non-lvalue.
1165  return true;
1166}
1167
1168
1169Sema::OwningStmtResult Sema::ActOnAsmStmt(SourceLocation AsmLoc,
1170                                          bool IsSimple,
1171                                          bool IsVolatile,
1172                                          unsigned NumOutputs,
1173                                          unsigned NumInputs,
1174                                          IdentifierInfo **Names,
1175                                          MultiExprArg constraints,
1176                                          MultiExprArg exprs,
1177                                          ExprArg asmString,
1178                                          MultiExprArg clobbers,
1179                                          SourceLocation RParenLoc,
1180                                          bool MSAsm) {
1181  unsigned NumClobbers = clobbers.size();
1182  StringLiteral **Constraints =
1183    reinterpret_cast<StringLiteral**>(constraints.get());
1184  Expr **Exprs = reinterpret_cast<Expr **>(exprs.get());
1185  StringLiteral *AsmString = cast<StringLiteral>((Expr *)asmString.get());
1186  StringLiteral **Clobbers = reinterpret_cast<StringLiteral**>(clobbers.get());
1187
1188  llvm::SmallVector<TargetInfo::ConstraintInfo, 4> OutputConstraintInfos;
1189
1190  // The parser verifies that there is a string literal here.
1191  if (AsmString->isWide())
1192    return StmtError(Diag(AsmString->getLocStart(),diag::err_asm_wide_character)
1193      << AsmString->getSourceRange());
1194
1195  for (unsigned i = 0; i != NumOutputs; i++) {
1196    StringLiteral *Literal = Constraints[i];
1197    if (Literal->isWide())
1198      return StmtError(Diag(Literal->getLocStart(),diag::err_asm_wide_character)
1199        << Literal->getSourceRange());
1200
1201    llvm::StringRef OutputName;
1202    if (Names[i])
1203      OutputName = Names[i]->getName();
1204
1205    TargetInfo::ConstraintInfo Info(Literal->getString(), OutputName);
1206    if (!Context.Target.validateOutputConstraint(Info))
1207      return StmtError(Diag(Literal->getLocStart(),
1208                            diag::err_asm_invalid_output_constraint)
1209                       << Info.getConstraintStr());
1210
1211    // Check that the output exprs are valid lvalues.
1212    Expr *OutputExpr = Exprs[i];
1213    if (CheckAsmLValue(OutputExpr, *this)) {
1214      return StmtError(Diag(OutputExpr->getLocStart(),
1215                  diag::err_asm_invalid_lvalue_in_output)
1216        << OutputExpr->getSourceRange());
1217    }
1218
1219    OutputConstraintInfos.push_back(Info);
1220  }
1221
1222  llvm::SmallVector<TargetInfo::ConstraintInfo, 4> InputConstraintInfos;
1223
1224  for (unsigned i = NumOutputs, e = NumOutputs + NumInputs; i != e; i++) {
1225    StringLiteral *Literal = Constraints[i];
1226    if (Literal->isWide())
1227      return StmtError(Diag(Literal->getLocStart(),diag::err_asm_wide_character)
1228        << Literal->getSourceRange());
1229
1230    llvm::StringRef InputName;
1231    if (Names[i])
1232      InputName = Names[i]->getName();
1233
1234    TargetInfo::ConstraintInfo Info(Literal->getString(), InputName);
1235    if (!Context.Target.validateInputConstraint(OutputConstraintInfos.data(),
1236                                                NumOutputs, Info)) {
1237      return StmtError(Diag(Literal->getLocStart(),
1238                            diag::err_asm_invalid_input_constraint)
1239                       << Info.getConstraintStr());
1240    }
1241
1242    Expr *InputExpr = Exprs[i];
1243
1244    // Only allow void types for memory constraints.
1245    if (Info.allowsMemory() && !Info.allowsRegister()) {
1246      if (CheckAsmLValue(InputExpr, *this))
1247        return StmtError(Diag(InputExpr->getLocStart(),
1248                              diag::err_asm_invalid_lvalue_in_input)
1249                         << Info.getConstraintStr()
1250                         << InputExpr->getSourceRange());
1251    }
1252
1253    if (Info.allowsRegister()) {
1254      if (InputExpr->getType()->isVoidType()) {
1255        return StmtError(Diag(InputExpr->getLocStart(),
1256                              diag::err_asm_invalid_type_in_input)
1257          << InputExpr->getType() << Info.getConstraintStr()
1258          << InputExpr->getSourceRange());
1259      }
1260    }
1261
1262    DefaultFunctionArrayLvalueConversion(Exprs[i]);
1263
1264    InputConstraintInfos.push_back(Info);
1265  }
1266
1267  // Check that the clobbers are valid.
1268  for (unsigned i = 0; i != NumClobbers; i++) {
1269    StringLiteral *Literal = Clobbers[i];
1270    if (Literal->isWide())
1271      return StmtError(Diag(Literal->getLocStart(),diag::err_asm_wide_character)
1272        << Literal->getSourceRange());
1273
1274    llvm::StringRef Clobber = Literal->getString();
1275
1276    if (!Context.Target.isValidGCCRegisterName(Clobber))
1277      return StmtError(Diag(Literal->getLocStart(),
1278                  diag::err_asm_unknown_register_name) << Clobber);
1279  }
1280
1281  constraints.release();
1282  exprs.release();
1283  asmString.release();
1284  clobbers.release();
1285  AsmStmt *NS =
1286    new (Context) AsmStmt(Context, AsmLoc, IsSimple, IsVolatile, MSAsm,
1287                          NumOutputs, NumInputs, Names, Constraints, Exprs,
1288                          AsmString, NumClobbers, Clobbers, RParenLoc);
1289  // Validate the asm string, ensuring it makes sense given the operands we
1290  // have.
1291  llvm::SmallVector<AsmStmt::AsmStringPiece, 8> Pieces;
1292  unsigned DiagOffs;
1293  if (unsigned DiagID = NS->AnalyzeAsmString(Pieces, Context, DiagOffs)) {
1294    Diag(getLocationOfStringLiteralByte(AsmString, DiagOffs), DiagID)
1295           << AsmString->getSourceRange();
1296    DeleteStmt(NS);
1297    return StmtError();
1298  }
1299
1300  // Validate tied input operands for type mismatches.
1301  for (unsigned i = 0, e = InputConstraintInfos.size(); i != e; ++i) {
1302    TargetInfo::ConstraintInfo &Info = InputConstraintInfos[i];
1303
1304    // If this is a tied constraint, verify that the output and input have
1305    // either exactly the same type, or that they are int/ptr operands with the
1306    // same size (int/long, int*/long, are ok etc).
1307    if (!Info.hasTiedOperand()) continue;
1308
1309    unsigned TiedTo = Info.getTiedOperand();
1310    Expr *OutputExpr = Exprs[TiedTo];
1311    Expr *InputExpr = Exprs[i+NumOutputs];
1312    QualType InTy = InputExpr->getType();
1313    QualType OutTy = OutputExpr->getType();
1314    if (Context.hasSameType(InTy, OutTy))
1315      continue;  // All types can be tied to themselves.
1316
1317    // Int/ptr operands have some special cases that we allow.
1318    if ((OutTy->isIntegerType() || OutTy->isPointerType()) &&
1319        (InTy->isIntegerType() || InTy->isPointerType())) {
1320
1321      // They are ok if they are the same size.  Tying void* to int is ok if
1322      // they are the same size, for example.  This also allows tying void* to
1323      // int*.
1324      uint64_t OutSize = Context.getTypeSize(OutTy);
1325      uint64_t InSize = Context.getTypeSize(InTy);
1326      if (OutSize == InSize)
1327        continue;
1328
1329      // If the smaller input/output operand is not mentioned in the asm string,
1330      // then we can promote it and the asm string won't notice.  Check this
1331      // case now.
1332      bool SmallerValueMentioned = false;
1333      for (unsigned p = 0, e = Pieces.size(); p != e; ++p) {
1334        AsmStmt::AsmStringPiece &Piece = Pieces[p];
1335        if (!Piece.isOperand()) continue;
1336
1337        // If this is a reference to the input and if the input was the smaller
1338        // one, then we have to reject this asm.
1339        if (Piece.getOperandNo() == i+NumOutputs) {
1340          if (InSize < OutSize) {
1341            SmallerValueMentioned = true;
1342            break;
1343          }
1344        }
1345
1346        // If this is a reference to the input and if the input was the smaller
1347        // one, then we have to reject this asm.
1348        if (Piece.getOperandNo() == TiedTo) {
1349          if (InSize > OutSize) {
1350            SmallerValueMentioned = true;
1351            break;
1352          }
1353        }
1354      }
1355
1356      // If the smaller value wasn't mentioned in the asm string, and if the
1357      // output was a register, just extend the shorter one to the size of the
1358      // larger one.
1359      if (!SmallerValueMentioned &&
1360          OutputConstraintInfos[TiedTo].allowsRegister())
1361        continue;
1362    }
1363
1364    Diag(InputExpr->getLocStart(),
1365         diag::err_asm_tying_incompatible_types)
1366      << InTy << OutTy << OutputExpr->getSourceRange()
1367      << InputExpr->getSourceRange();
1368    DeleteStmt(NS);
1369    return StmtError();
1370  }
1371
1372  return Owned(NS);
1373}
1374
1375Action::OwningStmtResult
1376Sema::ActOnObjCAtCatchStmt(SourceLocation AtLoc,
1377                           SourceLocation RParen, DeclPtrTy Parm,
1378                           StmtArg Body, StmtArg catchList) {
1379  Stmt *CatchList = catchList.takeAs<Stmt>();
1380  ParmVarDecl *PVD = cast_or_null<ParmVarDecl>(Parm.getAs<Decl>());
1381
1382  // PVD == 0 implies @catch(...).
1383  if (PVD) {
1384    // If we already know the decl is invalid, reject it.
1385    if (PVD->isInvalidDecl())
1386      return StmtError();
1387
1388    if (!PVD->getType()->isObjCObjectPointerType())
1389      return StmtError(Diag(PVD->getLocation(),
1390                       diag::err_catch_param_not_objc_type));
1391    if (PVD->getType()->isObjCQualifiedIdType())
1392      return StmtError(Diag(PVD->getLocation(),
1393                       diag::err_illegal_qualifiers_on_catch_parm));
1394  }
1395
1396  ObjCAtCatchStmt *CS = new (Context) ObjCAtCatchStmt(AtLoc, RParen,
1397    PVD, Body.takeAs<Stmt>(), CatchList);
1398  return Owned(CatchList ? CatchList : CS);
1399}
1400
1401Action::OwningStmtResult
1402Sema::ActOnObjCAtFinallyStmt(SourceLocation AtLoc, StmtArg Body) {
1403  return Owned(new (Context) ObjCAtFinallyStmt(AtLoc,
1404                                           static_cast<Stmt*>(Body.release())));
1405}
1406
1407Action::OwningStmtResult
1408Sema::ActOnObjCAtTryStmt(SourceLocation AtLoc,
1409                         StmtArg Try, StmtArg Catch, StmtArg Finally) {
1410  CurFunctionNeedsScopeChecking = true;
1411  return Owned(new (Context) ObjCAtTryStmt(AtLoc, Try.takeAs<Stmt>(),
1412                                           Catch.takeAs<Stmt>(),
1413                                           Finally.takeAs<Stmt>()));
1414}
1415
1416Action::OwningStmtResult
1417Sema::ActOnObjCAtThrowStmt(SourceLocation AtLoc, ExprArg expr,Scope *CurScope) {
1418  Expr *ThrowExpr = expr.takeAs<Expr>();
1419  if (!ThrowExpr) {
1420    // @throw without an expression designates a rethrow (which much occur
1421    // in the context of an @catch clause).
1422    Scope *AtCatchParent = CurScope;
1423    while (AtCatchParent && !AtCatchParent->isAtCatchScope())
1424      AtCatchParent = AtCatchParent->getParent();
1425    if (!AtCatchParent)
1426      return StmtError(Diag(AtLoc, diag::error_rethrow_used_outside_catch));
1427  } else {
1428    QualType ThrowType = ThrowExpr->getType();
1429    // Make sure the expression type is an ObjC pointer or "void *".
1430    if (!ThrowType->isObjCObjectPointerType()) {
1431      const PointerType *PT = ThrowType->getAs<PointerType>();
1432      if (!PT || !PT->getPointeeType()->isVoidType())
1433        return StmtError(Diag(AtLoc, diag::error_objc_throw_expects_object)
1434                        << ThrowExpr->getType() << ThrowExpr->getSourceRange());
1435    }
1436  }
1437  return Owned(new (Context) ObjCAtThrowStmt(AtLoc, ThrowExpr));
1438}
1439
1440Action::OwningStmtResult
1441Sema::ActOnObjCAtSynchronizedStmt(SourceLocation AtLoc, ExprArg SynchExpr,
1442                                  StmtArg SynchBody) {
1443  CurFunctionNeedsScopeChecking = true;
1444
1445  // Make sure the expression type is an ObjC pointer or "void *".
1446  Expr *SyncExpr = static_cast<Expr*>(SynchExpr.get());
1447  if (!SyncExpr->getType()->isObjCObjectPointerType()) {
1448    const PointerType *PT = SyncExpr->getType()->getAs<PointerType>();
1449    if (!PT || !PT->getPointeeType()->isVoidType())
1450      return StmtError(Diag(AtLoc, diag::error_objc_synchronized_expects_object)
1451                       << SyncExpr->getType() << SyncExpr->getSourceRange());
1452  }
1453
1454  return Owned(new (Context) ObjCAtSynchronizedStmt(AtLoc,
1455                                                    SynchExpr.takeAs<Stmt>(),
1456                                                    SynchBody.takeAs<Stmt>()));
1457}
1458
1459/// ActOnCXXCatchBlock - Takes an exception declaration and a handler block
1460/// and creates a proper catch handler from them.
1461Action::OwningStmtResult
1462Sema::ActOnCXXCatchBlock(SourceLocation CatchLoc, DeclPtrTy ExDecl,
1463                         StmtArg HandlerBlock) {
1464  // There's nothing to test that ActOnExceptionDecl didn't already test.
1465  return Owned(new (Context) CXXCatchStmt(CatchLoc,
1466                                  cast_or_null<VarDecl>(ExDecl.getAs<Decl>()),
1467                                          HandlerBlock.takeAs<Stmt>()));
1468}
1469
1470class TypeWithHandler {
1471  QualType t;
1472  CXXCatchStmt *stmt;
1473public:
1474  TypeWithHandler(const QualType &type, CXXCatchStmt *statement)
1475  : t(type), stmt(statement) {}
1476
1477  // An arbitrary order is fine as long as it places identical
1478  // types next to each other.
1479  bool operator<(const TypeWithHandler &y) const {
1480    if (t.getAsOpaquePtr() < y.t.getAsOpaquePtr())
1481      return true;
1482    if (t.getAsOpaquePtr() > y.t.getAsOpaquePtr())
1483      return false;
1484    else
1485      return getTypeSpecStartLoc() < y.getTypeSpecStartLoc();
1486  }
1487
1488  bool operator==(const TypeWithHandler& other) const {
1489    return t == other.t;
1490  }
1491
1492  QualType getQualType() const { return t; }
1493  CXXCatchStmt *getCatchStmt() const { return stmt; }
1494  SourceLocation getTypeSpecStartLoc() const {
1495    return stmt->getExceptionDecl()->getTypeSpecStartLoc();
1496  }
1497};
1498
1499/// ActOnCXXTryBlock - Takes a try compound-statement and a number of
1500/// handlers and creates a try statement from them.
1501Action::OwningStmtResult
1502Sema::ActOnCXXTryBlock(SourceLocation TryLoc, StmtArg TryBlock,
1503                       MultiStmtArg RawHandlers) {
1504  unsigned NumHandlers = RawHandlers.size();
1505  assert(NumHandlers > 0 &&
1506         "The parser shouldn't call this if there are no handlers.");
1507  Stmt **Handlers = reinterpret_cast<Stmt**>(RawHandlers.get());
1508
1509  llvm::SmallVector<TypeWithHandler, 8> TypesWithHandlers;
1510
1511  for (unsigned i = 0; i < NumHandlers; ++i) {
1512    CXXCatchStmt *Handler = llvm::cast<CXXCatchStmt>(Handlers[i]);
1513    if (!Handler->getExceptionDecl()) {
1514      if (i < NumHandlers - 1)
1515        return StmtError(Diag(Handler->getLocStart(),
1516                              diag::err_early_catch_all));
1517
1518      continue;
1519    }
1520
1521    const QualType CaughtType = Handler->getCaughtType();
1522    const QualType CanonicalCaughtType = Context.getCanonicalType(CaughtType);
1523    TypesWithHandlers.push_back(TypeWithHandler(CanonicalCaughtType, Handler));
1524  }
1525
1526  // Detect handlers for the same type as an earlier one.
1527  if (NumHandlers > 1) {
1528    llvm::array_pod_sort(TypesWithHandlers.begin(), TypesWithHandlers.end());
1529
1530    TypeWithHandler prev = TypesWithHandlers[0];
1531    for (unsigned i = 1; i < TypesWithHandlers.size(); ++i) {
1532      TypeWithHandler curr = TypesWithHandlers[i];
1533
1534      if (curr == prev) {
1535        Diag(curr.getTypeSpecStartLoc(),
1536             diag::warn_exception_caught_by_earlier_handler)
1537          << curr.getCatchStmt()->getCaughtType().getAsString();
1538        Diag(prev.getTypeSpecStartLoc(),
1539             diag::note_previous_exception_handler)
1540          << prev.getCatchStmt()->getCaughtType().getAsString();
1541      }
1542
1543      prev = curr;
1544    }
1545  }
1546
1547  // FIXME: We should detect handlers that cannot catch anything because an
1548  // earlier handler catches a superclass. Need to find a method that is not
1549  // quadratic for this.
1550  // Neither of these are explicitly forbidden, but every compiler detects them
1551  // and warns.
1552
1553  CurFunctionNeedsScopeChecking = true;
1554  RawHandlers.release();
1555  return Owned(CXXTryStmt::Create(Context, TryLoc,
1556                                  static_cast<Stmt*>(TryBlock.release()),
1557                                  Handlers, NumHandlers));
1558}
1559