SemaStmt.cpp revision 0be3193b3bc695eb4b0debc7f85bc832026ce862 
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 "clang/AST/APValue.h"
16#include "clang/AST/ASTContext.h"
17#include "clang/AST/DeclObjC.h"
18#include "clang/AST/ExprCXX.h"
19#include "clang/AST/ExprObjC.h"
20#include "clang/AST/StmtObjC.h"
21#include "clang/AST/StmtCXX.h"
22#include "clang/Lex/Preprocessor.h"
23#include "clang/Basic/TargetInfo.h"
24#include "llvm/ADT/STLExtras.h"
25#include "llvm/ADT/SmallVector.h"
26using namespace clang;
27
28Sema::OwningStmtResult Sema::ActOnExprStmt(FullExprArg expr) {
29  Expr *E = expr->takeAs<Expr>();
30  assert(E && "ActOnExprStmt(): missing expression");
31  if (E->getType()->isObjCInterfaceType()) {
32    if (LangOpts.ObjCNonFragileABI)
33      Diag(E->getLocEnd(), diag::err_indirection_requires_nonfragile_object)
34             << E->getType();
35    else
36      Diag(E->getLocEnd(), diag::err_direct_interface_unsupported)
37             << E->getType();
38    return StmtError();
39  }
40  // C99 6.8.3p2: The expression in an expression statement is evaluated as a
41  // void expression for its side effects.  Conversion to void allows any
42  // operand, even incomplete types.
43
44  // Same thing in for stmt first clause (when expr) and third clause.
45  return Owned(static_cast<Stmt*>(E));
46}
47
48
49Sema::OwningStmtResult Sema::ActOnNullStmt(SourceLocation SemiLoc) {
50  return Owned(new (Context) NullStmt(SemiLoc));
51}
52
53Sema::OwningStmtResult Sema::ActOnDeclStmt(DeclGroupPtrTy dg,
54                                           SourceLocation StartLoc,
55                                           SourceLocation EndLoc) {
56  DeclGroupRef DG = dg.getAsVal<DeclGroupRef>();
57
58  // If we have an invalid decl, just return an error.
59  if (DG.isNull()) return StmtError();
60
61  return Owned(new (Context) DeclStmt(DG, StartLoc, EndLoc));
62}
63
64void Sema::ActOnForEachDeclStmt(DeclGroupPtrTy dg) {
65  DeclGroupRef DG = dg.getAsVal<DeclGroupRef>();
66
67  // If we have an invalid decl, just return.
68  if (DG.isNull() || !DG.isSingleDecl()) return;
69  // suppress any potential 'unused variable' warning.
70  DG.getSingleDecl()->setUsed();
71}
72
73void Sema::DiagnoseUnusedExprResult(const Stmt *S) {
74  const Expr *E = dyn_cast_or_null<Expr>(S);
75  if (!E)
76    return;
77
78  // Ignore expressions that have void type.
79  if (E->getType()->isVoidType())
80    return;
81
82  SourceLocation Loc;
83  SourceRange R1, R2;
84  if (!E->isUnusedResultAWarning(Loc, R1, R2, Context))
85    return;
86
87  // Okay, we have an unused result.  Depending on what the base expression is,
88  // we might want to make a more specific diagnostic.  Check for one of these
89  // cases now.
90  unsigned DiagID = diag::warn_unused_expr;
91  E = E->IgnoreParens();
92  if (isa<ObjCImplicitSetterGetterRefExpr>(E))
93    DiagID = diag::warn_unused_property_expr;
94
95  if (const CallExpr *CE = dyn_cast<CallExpr>(E)) {
96    // If the callee has attribute pure, const, or warn_unused_result, warn with
97    // a more specific message to make it clear what is happening.
98    if (const FunctionDecl *FD = CE->getDirectCallee()) {
99      if (FD->getAttr<WarnUnusedResultAttr>()) {
100        Diag(Loc, diag::warn_unused_call) << R1 << R2 << "warn_unused_result";
101        return;
102      }
103      if (FD->getAttr<PureAttr>()) {
104        Diag(Loc, diag::warn_unused_call) << R1 << R2 << "pure";
105        return;
106      }
107      if (FD->getAttr<ConstAttr>()) {
108        Diag(Loc, diag::warn_unused_call) << R1 << R2 << "const";
109        return;
110      }
111    }
112  }
113
114  Diag(Loc, DiagID) << R1 << R2;
115}
116
117Action::OwningStmtResult
118Sema::ActOnCompoundStmt(SourceLocation L, SourceLocation R,
119                        MultiStmtArg elts, bool isStmtExpr) {
120  unsigned NumElts = elts.size();
121  Stmt **Elts = reinterpret_cast<Stmt**>(elts.release());
122  // If we're in C89 mode, check that we don't have any decls after stmts.  If
123  // so, emit an extension diagnostic.
124  if (!getLangOptions().C99 && !getLangOptions().CPlusPlus) {
125    // Note that __extension__ can be around a decl.
126    unsigned i = 0;
127    // Skip over all declarations.
128    for (; i != NumElts && isa<DeclStmt>(Elts[i]); ++i)
129      /*empty*/;
130
131    // We found the end of the list or a statement.  Scan for another declstmt.
132    for (; i != NumElts && !isa<DeclStmt>(Elts[i]); ++i)
133      /*empty*/;
134
135    if (i != NumElts) {
136      Decl *D = *cast<DeclStmt>(Elts[i])->decl_begin();
137      Diag(D->getLocation(), diag::ext_mixed_decls_code);
138    }
139  }
140  // Warn about unused expressions in statements.
141  for (unsigned i = 0; i != NumElts; ++i) {
142    // Ignore statements that are last in a statement expression.
143    if (isStmtExpr && i == NumElts - 1)
144      continue;
145
146    DiagnoseUnusedExprResult(Elts[i]);
147  }
148
149  return Owned(new (Context) CompoundStmt(Context, Elts, NumElts, L, R));
150}
151
152Action::OwningStmtResult
153Sema::ActOnCaseStmt(SourceLocation CaseLoc, ExprArg lhsval,
154                    SourceLocation DotDotDotLoc, ExprArg rhsval,
155                    SourceLocation ColonLoc) {
156  assert((lhsval.get() != 0) && "missing expression in case statement");
157
158  // C99 6.8.4.2p3: The expression shall be an integer constant.
159  // However, GCC allows any evaluatable integer expression.
160  Expr *LHSVal = static_cast<Expr*>(lhsval.get());
161  if (!LHSVal->isTypeDependent() && !LHSVal->isValueDependent() &&
162      VerifyIntegerConstantExpression(LHSVal))
163    return StmtError();
164
165  // GCC extension: The expression shall be an integer constant.
166
167  Expr *RHSVal = static_cast<Expr*>(rhsval.get());
168  if (RHSVal && !RHSVal->isTypeDependent() && !RHSVal->isValueDependent() &&
169      VerifyIntegerConstantExpression(RHSVal)) {
170    RHSVal = 0;  // Recover by just forgetting about it.
171    rhsval = 0;
172  }
173
174  if (getSwitchStack().empty()) {
175    Diag(CaseLoc, diag::err_case_not_in_switch);
176    return StmtError();
177  }
178
179  // Only now release the smart pointers.
180  lhsval.release();
181  rhsval.release();
182  CaseStmt *CS = new (Context) CaseStmt(LHSVal, RHSVal, CaseLoc, DotDotDotLoc,
183                                        ColonLoc);
184  getSwitchStack().back()->addSwitchCase(CS);
185  return Owned(CS);
186}
187
188/// ActOnCaseStmtBody - This installs a statement as the body of a case.
189void Sema::ActOnCaseStmtBody(StmtTy *caseStmt, StmtArg subStmt) {
190  CaseStmt *CS = static_cast<CaseStmt*>(caseStmt);
191  Stmt *SubStmt = subStmt.takeAs<Stmt>();
192  CS->setSubStmt(SubStmt);
193}
194
195Action::OwningStmtResult
196Sema::ActOnDefaultStmt(SourceLocation DefaultLoc, SourceLocation ColonLoc,
197                       StmtArg subStmt, Scope *CurScope) {
198  Stmt *SubStmt = subStmt.takeAs<Stmt>();
199
200  if (getSwitchStack().empty()) {
201    Diag(DefaultLoc, diag::err_default_not_in_switch);
202    return Owned(SubStmt);
203  }
204
205  DefaultStmt *DS = new (Context) DefaultStmt(DefaultLoc, ColonLoc, SubStmt);
206  getSwitchStack().back()->addSwitchCase(DS);
207  return Owned(DS);
208}
209
210Action::OwningStmtResult
211Sema::ActOnLabelStmt(SourceLocation IdentLoc, IdentifierInfo *II,
212                     SourceLocation ColonLoc, StmtArg subStmt) {
213  Stmt *SubStmt = subStmt.takeAs<Stmt>();
214  // Look up the record for this label identifier.
215  LabelStmt *&LabelDecl = getLabelMap()[II];
216
217  // If not forward referenced or defined already, just create a new LabelStmt.
218  if (LabelDecl == 0)
219    return Owned(LabelDecl = new (Context) LabelStmt(IdentLoc, II, SubStmt));
220
221  assert(LabelDecl->getID() == II && "Label mismatch!");
222
223  // Otherwise, this label was either forward reference or multiply defined.  If
224  // multiply defined, reject it now.
225  if (LabelDecl->getSubStmt()) {
226    Diag(IdentLoc, diag::err_redefinition_of_label) << LabelDecl->getID();
227    Diag(LabelDecl->getIdentLoc(), diag::note_previous_definition);
228    return Owned(SubStmt);
229  }
230
231  // Otherwise, this label was forward declared, and we just found its real
232  // definition.  Fill in the forward definition and return it.
233  LabelDecl->setIdentLoc(IdentLoc);
234  LabelDecl->setSubStmt(SubStmt);
235  return Owned(LabelDecl);
236}
237
238Action::OwningStmtResult
239Sema::ActOnIfStmt(SourceLocation IfLoc, FullExprArg CondVal, DeclPtrTy CondVar,
240                  StmtArg ThenVal, SourceLocation ElseLoc,
241                  StmtArg ElseVal) {
242  OwningExprResult CondResult(CondVal.release());
243
244  VarDecl *ConditionVar = 0;
245  if (CondVar.get()) {
246    ConditionVar = CondVar.getAs<VarDecl>();
247    CondResult = CheckConditionVariable(ConditionVar);
248    if (CondResult.isInvalid())
249      return StmtError();
250  }
251  Expr *ConditionExpr = CondResult.takeAs<Expr>();
252  if (!ConditionExpr)
253    return StmtError();
254
255  if (CheckBooleanCondition(ConditionExpr, IfLoc)) {
256    CondResult = ConditionExpr;
257    return StmtError();
258  }
259
260  Stmt *thenStmt = ThenVal.takeAs<Stmt>();
261  DiagnoseUnusedExprResult(thenStmt);
262
263  // Warn if the if block has a null body without an else value.
264  // this helps prevent bugs due to typos, such as
265  // if (condition);
266  //   do_stuff();
267  if (!ElseVal.get()) {
268    if (NullStmt* stmt = dyn_cast<NullStmt>(thenStmt))
269      Diag(stmt->getSemiLoc(), diag::warn_empty_if_body);
270  }
271
272  Stmt *elseStmt = ElseVal.takeAs<Stmt>();
273  DiagnoseUnusedExprResult(elseStmt);
274
275  CondResult.release();
276  return Owned(new (Context) IfStmt(IfLoc, ConditionVar, ConditionExpr,
277                                    thenStmt, ElseLoc, elseStmt));
278}
279
280Action::OwningStmtResult
281Sema::ActOnStartOfSwitchStmt(FullExprArg cond, DeclPtrTy CondVar) {
282  OwningExprResult CondResult(cond.release());
283
284  VarDecl *ConditionVar = 0;
285  if (CondVar.get()) {
286    ConditionVar = CondVar.getAs<VarDecl>();
287    CondResult = CheckConditionVariable(ConditionVar);
288    if (CondResult.isInvalid())
289      return StmtError();
290  }
291  Expr *ConditionExpr = CondResult.takeAs<Expr>();
292  if (!ConditionExpr)
293    return StmtError();
294
295  CondResult.release();
296  SwitchStmt *SS = new (Context) SwitchStmt(ConditionVar, ConditionExpr);
297  getSwitchStack().push_back(SS);
298  return Owned(SS);
299}
300
301/// ConvertIntegerToTypeWarnOnOverflow - Convert the specified APInt to have
302/// the specified width and sign.  If an overflow occurs, detect it and emit
303/// the specified diagnostic.
304void Sema::ConvertIntegerToTypeWarnOnOverflow(llvm::APSInt &Val,
305                                              unsigned NewWidth, bool NewSign,
306                                              SourceLocation Loc,
307                                              unsigned DiagID) {
308  // Perform a conversion to the promoted condition type if needed.
309  if (NewWidth > Val.getBitWidth()) {
310    // If this is an extension, just do it.
311    llvm::APSInt OldVal(Val);
312    Val.extend(NewWidth);
313
314    // If the input was signed and negative and the output is unsigned,
315    // warn.
316    if (!NewSign && OldVal.isSigned() && OldVal.isNegative())
317      Diag(Loc, DiagID) << OldVal.toString(10) << Val.toString(10);
318
319    Val.setIsSigned(NewSign);
320  } else if (NewWidth < Val.getBitWidth()) {
321    // If this is a truncation, check for overflow.
322    llvm::APSInt ConvVal(Val);
323    ConvVal.trunc(NewWidth);
324    ConvVal.setIsSigned(NewSign);
325    ConvVal.extend(Val.getBitWidth());
326    ConvVal.setIsSigned(Val.isSigned());
327    if (ConvVal != Val)
328      Diag(Loc, DiagID) << Val.toString(10) << ConvVal.toString(10);
329
330    // Regardless of whether a diagnostic was emitted, really do the
331    // truncation.
332    Val.trunc(NewWidth);
333    Val.setIsSigned(NewSign);
334  } else if (NewSign != Val.isSigned()) {
335    // Convert the sign to match the sign of the condition.  This can cause
336    // overflow as well: unsigned(INTMIN)
337    llvm::APSInt OldVal(Val);
338    Val.setIsSigned(NewSign);
339
340    if (Val.isNegative())  // Sign bit changes meaning.
341      Diag(Loc, DiagID) << OldVal.toString(10) << Val.toString(10);
342  }
343}
344
345namespace {
346  struct CaseCompareFunctor {
347    bool operator()(const std::pair<llvm::APSInt, CaseStmt*> &LHS,
348                    const llvm::APSInt &RHS) {
349      return LHS.first < RHS;
350    }
351    bool operator()(const std::pair<llvm::APSInt, CaseStmt*> &LHS,
352                    const std::pair<llvm::APSInt, CaseStmt*> &RHS) {
353      return LHS.first < RHS.first;
354    }
355    bool operator()(const llvm::APSInt &LHS,
356                    const std::pair<llvm::APSInt, CaseStmt*> &RHS) {
357      return LHS < RHS.first;
358    }
359  };
360}
361
362/// CmpCaseVals - Comparison predicate for sorting case values.
363///
364static bool CmpCaseVals(const std::pair<llvm::APSInt, CaseStmt*>& lhs,
365                        const std::pair<llvm::APSInt, CaseStmt*>& rhs) {
366  if (lhs.first < rhs.first)
367    return true;
368
369  if (lhs.first == rhs.first &&
370      lhs.second->getCaseLoc().getRawEncoding()
371       < rhs.second->getCaseLoc().getRawEncoding())
372    return true;
373  return false;
374}
375
376/// GetTypeBeforeIntegralPromotion - Returns the pre-promotion type of
377/// potentially integral-promoted expression @p expr.
378static QualType GetTypeBeforeIntegralPromotion(const Expr* expr) {
379  const ImplicitCastExpr *ImplicitCast =
380      dyn_cast_or_null<ImplicitCastExpr>(expr);
381  if (ImplicitCast != NULL) {
382    const Expr *ExprBeforePromotion = ImplicitCast->getSubExpr();
383    QualType TypeBeforePromotion = ExprBeforePromotion->getType();
384    if (TypeBeforePromotion->isIntegralType()) {
385      return TypeBeforePromotion;
386    }
387  }
388  return expr->getType();
389}
390
391/// \brief Check (and possibly convert) the condition in a switch
392/// statement in C++.
393static bool CheckCXXSwitchCondition(Sema &S, SourceLocation SwitchLoc,
394                                    Expr *&CondExpr) {
395  if (CondExpr->isTypeDependent())
396    return false;
397
398  QualType CondType = CondExpr->getType();
399
400  // C++ 6.4.2.p2:
401  // The condition shall be of integral type, enumeration type, or of a class
402  // type for which a single conversion function to integral or enumeration
403  // type exists (12.3). If the condition is of class type, the condition is
404  // converted by calling that conversion function, and the result of the
405  // conversion is used in place of the original condition for the remainder
406  // of this section. Integral promotions are performed.
407
408  // Make sure that the condition expression has a complete type,
409  // otherwise we'll never find any conversions.
410  if (S.RequireCompleteType(SwitchLoc, CondType,
411                            PDiag(diag::err_switch_incomplete_class_type)
412                              << CondExpr->getSourceRange()))
413    return true;
414
415  llvm::SmallVector<CXXConversionDecl *, 4> ViableConversions;
416  llvm::SmallVector<CXXConversionDecl *, 4> ExplicitConversions;
417  if (const RecordType *RecordTy = CondType->getAs<RecordType>()) {
418    const UnresolvedSet *Conversions
419      = cast<CXXRecordDecl>(RecordTy->getDecl())
420                                             ->getVisibleConversionFunctions();
421    for (UnresolvedSet::iterator I = Conversions->begin(),
422           E = Conversions->end(); I != E; ++I) {
423      if (CXXConversionDecl *Conversion = dyn_cast<CXXConversionDecl>(*I))
424        if (Conversion->getConversionType().getNonReferenceType()
425              ->isIntegralType()) {
426          if (Conversion->isExplicit())
427            ExplicitConversions.push_back(Conversion);
428          else
429          ViableConversions.push_back(Conversion);
430        }
431    }
432
433    switch (ViableConversions.size()) {
434    case 0:
435      if (ExplicitConversions.size() == 1) {
436        // The user probably meant to invoke the given explicit
437        // conversion; use it.
438        QualType ConvTy
439          = ExplicitConversions[0]->getConversionType()
440                        .getNonReferenceType();
441        std::string TypeStr;
442        ConvTy.getAsStringInternal(TypeStr, S.Context.PrintingPolicy);
443
444        S.Diag(SwitchLoc, diag::err_switch_explicit_conversion)
445          << CondType << ConvTy << CondExpr->getSourceRange()
446          << CodeModificationHint::CreateInsertion(CondExpr->getLocStart(),
447                                         "static_cast<" + TypeStr + ">(")
448          << CodeModificationHint::CreateInsertion(
449                            S.PP.getLocForEndOfToken(CondExpr->getLocEnd()),
450                               ")");
451        S.Diag(ExplicitConversions[0]->getLocation(),
452             diag::note_switch_conversion)
453          << ConvTy->isEnumeralType() << ConvTy;
454
455        // If we aren't in a SFINAE context, build a call to the
456        // explicit conversion function.
457        if (S.isSFINAEContext())
458          return true;
459
460        CondExpr = S.BuildCXXMemberCallExpr(CondExpr, ExplicitConversions[0]);
461      }
462
463      // We'll complain below about a non-integral condition type.
464      break;
465
466    case 1:
467      // Apply this conversion.
468      CondExpr = S.BuildCXXMemberCallExpr(CondExpr, ViableConversions[0]);
469      break;
470
471    default:
472      S.Diag(SwitchLoc, diag::err_switch_multiple_conversions)
473        << CondType << CondExpr->getSourceRange();
474      for (unsigned I = 0, N = ViableConversions.size(); I != N; ++I) {
475        QualType ConvTy
476          = ViableConversions[I]->getConversionType().getNonReferenceType();
477        S.Diag(ViableConversions[I]->getLocation(),
478             diag::note_switch_conversion)
479          << ConvTy->isEnumeralType() << ConvTy;
480      }
481      return true;
482    }
483  }
484  CondType = CondExpr->getType();
485
486  // Integral promotions are performed.
487  if (CondType->isIntegralType() || CondType->isEnumeralType())
488    S.UsualUnaryConversions(CondExpr);
489
490  return false;
491}
492
493Action::OwningStmtResult
494Sema::ActOnFinishSwitchStmt(SourceLocation SwitchLoc, StmtArg Switch,
495                            StmtArg Body) {
496  Stmt *BodyStmt = Body.takeAs<Stmt>();
497
498  SwitchStmt *SS = getSwitchStack().back();
499  assert(SS == (SwitchStmt*)Switch.get() && "switch stack missing push/pop!");
500
501  SS->setBody(BodyStmt, SwitchLoc);
502  getSwitchStack().pop_back();
503
504  Expr *CondExpr = SS->getCond();
505  QualType CondTypeBeforePromotion =
506      GetTypeBeforeIntegralPromotion(CondExpr);
507  QualType CondType = CondExpr->getType();
508
509  if (getLangOptions().CPlusPlus) {
510    if (CheckCXXSwitchCondition(*this, SwitchLoc, CondExpr))
511      return StmtError();
512  } else {
513    // C99 6.8.4.2p5 - Integer promotions are performed on the
514    // controlling expr.
515    UsualUnaryConversions(CondExpr);
516  }
517  CondType = CondExpr->getType();
518  SS->setCond(CondExpr);
519
520  // C++ 6.4.2.p2:
521  // Integral promotions are performed (on the switch condition).
522  //
523  // A case value unrepresentable by the original switch condition
524  // type (before the promotion) doesn't make sense, even when it can
525  // be represented by the promoted type.  Therefore we need to find
526  // the pre-promotion type of the switch condition.
527  if (!CondExpr->isTypeDependent()) {
528    if (!CondType->isIntegerType()) { // C99 6.8.4.2p1
529      Diag(SwitchLoc, diag::err_typecheck_statement_requires_integer)
530          << CondType << CondExpr->getSourceRange();
531      return StmtError();
532    }
533
534    if (CondTypeBeforePromotion->isBooleanType()) {
535      // switch(bool_expr) {...} is often a programmer error, e.g.
536      //   switch(n && mask) { ... }  // Doh - should be "n & mask".
537      // One can always use an if statement instead of switch(bool_expr).
538      Diag(SwitchLoc, diag::warn_bool_switch_condition)
539          << CondExpr->getSourceRange();
540    }
541  }
542
543  // Get the bitwidth of the switched-on value before promotions.  We must
544  // convert the integer case values to this width before comparison.
545  bool HasDependentValue
546    = CondExpr->isTypeDependent() || CondExpr->isValueDependent();
547  unsigned CondWidth
548    = HasDependentValue? 0
549      : static_cast<unsigned>(Context.getTypeSize(CondTypeBeforePromotion));
550  bool CondIsSigned = CondTypeBeforePromotion->isSignedIntegerType();
551
552  // Accumulate all of the case values in a vector so that we can sort them
553  // and detect duplicates.  This vector contains the APInt for the case after
554  // it has been converted to the condition type.
555  typedef llvm::SmallVector<std::pair<llvm::APSInt, CaseStmt*>, 64> CaseValsTy;
556  CaseValsTy CaseVals;
557
558  // Keep track of any GNU case ranges we see.  The APSInt is the low value.
559  std::vector<std::pair<llvm::APSInt, CaseStmt*> > CaseRanges;
560
561  DefaultStmt *TheDefaultStmt = 0;
562
563  bool CaseListIsErroneous = false;
564
565  for (SwitchCase *SC = SS->getSwitchCaseList(); SC && !HasDependentValue;
566       SC = SC->getNextSwitchCase()) {
567
568    if (DefaultStmt *DS = dyn_cast<DefaultStmt>(SC)) {
569      if (TheDefaultStmt) {
570        Diag(DS->getDefaultLoc(), diag::err_multiple_default_labels_defined);
571        Diag(TheDefaultStmt->getDefaultLoc(), diag::note_duplicate_case_prev);
572
573        // FIXME: Remove the default statement from the switch block so that
574        // we'll return a valid AST.  This requires recursing down the AST and
575        // finding it, not something we are set up to do right now.  For now,
576        // just lop the entire switch stmt out of the AST.
577        CaseListIsErroneous = true;
578      }
579      TheDefaultStmt = DS;
580
581    } else {
582      CaseStmt *CS = cast<CaseStmt>(SC);
583
584      // We already verified that the expression has a i-c-e value (C99
585      // 6.8.4.2p3) - get that value now.
586      Expr *Lo = CS->getLHS();
587
588      if (Lo->isTypeDependent() || Lo->isValueDependent()) {
589        HasDependentValue = true;
590        break;
591      }
592
593      llvm::APSInt LoVal = Lo->EvaluateAsInt(Context);
594
595      // Convert the value to the same width/sign as the condition.
596      ConvertIntegerToTypeWarnOnOverflow(LoVal, CondWidth, CondIsSigned,
597                                         CS->getLHS()->getLocStart(),
598                                         diag::warn_case_value_overflow);
599
600      // If the LHS is not the same type as the condition, insert an implicit
601      // cast.
602      ImpCastExprToType(Lo, CondType, CastExpr::CK_IntegralCast);
603      CS->setLHS(Lo);
604
605      // If this is a case range, remember it in CaseRanges, otherwise CaseVals.
606      if (CS->getRHS()) {
607        if (CS->getRHS()->isTypeDependent() ||
608            CS->getRHS()->isValueDependent()) {
609          HasDependentValue = true;
610          break;
611        }
612        CaseRanges.push_back(std::make_pair(LoVal, CS));
613      } else
614        CaseVals.push_back(std::make_pair(LoVal, CS));
615    }
616  }
617
618  if (!HasDependentValue) {
619    // Sort all the scalar case values so we can easily detect duplicates.
620    std::stable_sort(CaseVals.begin(), CaseVals.end(), CmpCaseVals);
621
622    if (!CaseVals.empty()) {
623      for (unsigned i = 0, e = CaseVals.size()-1; i != e; ++i) {
624        if (CaseVals[i].first == CaseVals[i+1].first) {
625          // If we have a duplicate, report it.
626          Diag(CaseVals[i+1].second->getLHS()->getLocStart(),
627               diag::err_duplicate_case) << CaseVals[i].first.toString(10);
628          Diag(CaseVals[i].second->getLHS()->getLocStart(),
629               diag::note_duplicate_case_prev);
630          // FIXME: We really want to remove the bogus case stmt from the
631          // substmt, but we have no way to do this right now.
632          CaseListIsErroneous = true;
633        }
634      }
635    }
636
637    // Detect duplicate case ranges, which usually don't exist at all in
638    // the first place.
639    if (!CaseRanges.empty()) {
640      // Sort all the case ranges by their low value so we can easily detect
641      // overlaps between ranges.
642      std::stable_sort(CaseRanges.begin(), CaseRanges.end());
643
644      // Scan the ranges, computing the high values and removing empty ranges.
645      std::vector<llvm::APSInt> HiVals;
646      for (unsigned i = 0, e = CaseRanges.size(); i != e; ++i) {
647        CaseStmt *CR = CaseRanges[i].second;
648        Expr *Hi = CR->getRHS();
649        llvm::APSInt HiVal = Hi->EvaluateAsInt(Context);
650
651        // Convert the value to the same width/sign as the condition.
652        ConvertIntegerToTypeWarnOnOverflow(HiVal, CondWidth, CondIsSigned,
653                                           CR->getRHS()->getLocStart(),
654                                           diag::warn_case_value_overflow);
655
656        // If the LHS is not the same type as the condition, insert an implicit
657        // cast.
658        ImpCastExprToType(Hi, CondType, CastExpr::CK_IntegralCast);
659        CR->setRHS(Hi);
660
661        // If the low value is bigger than the high value, the case is empty.
662        if (CaseRanges[i].first > HiVal) {
663          Diag(CR->getLHS()->getLocStart(), diag::warn_case_empty_range)
664            << SourceRange(CR->getLHS()->getLocStart(),
665                           CR->getRHS()->getLocEnd());
666          CaseRanges.erase(CaseRanges.begin()+i);
667          --i, --e;
668          continue;
669        }
670        HiVals.push_back(HiVal);
671      }
672
673      // Rescan the ranges, looking for overlap with singleton values and other
674      // ranges.  Since the range list is sorted, we only need to compare case
675      // ranges with their neighbors.
676      for (unsigned i = 0, e = CaseRanges.size(); i != e; ++i) {
677        llvm::APSInt &CRLo = CaseRanges[i].first;
678        llvm::APSInt &CRHi = HiVals[i];
679        CaseStmt *CR = CaseRanges[i].second;
680
681        // Check to see whether the case range overlaps with any
682        // singleton cases.
683        CaseStmt *OverlapStmt = 0;
684        llvm::APSInt OverlapVal(32);
685
686        // Find the smallest value >= the lower bound.  If I is in the
687        // case range, then we have overlap.
688        CaseValsTy::iterator I = std::lower_bound(CaseVals.begin(),
689                                                  CaseVals.end(), CRLo,
690                                                  CaseCompareFunctor());
691        if (I != CaseVals.end() && I->first < CRHi) {
692          OverlapVal  = I->first;   // Found overlap with scalar.
693          OverlapStmt = I->second;
694        }
695
696        // Find the smallest value bigger than the upper bound.
697        I = std::upper_bound(I, CaseVals.end(), CRHi, CaseCompareFunctor());
698        if (I != CaseVals.begin() && (I-1)->first >= CRLo) {
699          OverlapVal  = (I-1)->first;      // Found overlap with scalar.
700          OverlapStmt = (I-1)->second;
701        }
702
703        // Check to see if this case stmt overlaps with the subsequent
704        // case range.
705        if (i && CRLo <= HiVals[i-1]) {
706          OverlapVal  = HiVals[i-1];       // Found overlap with range.
707          OverlapStmt = CaseRanges[i-1].second;
708        }
709
710        if (OverlapStmt) {
711          // If we have a duplicate, report it.
712          Diag(CR->getLHS()->getLocStart(), diag::err_duplicate_case)
713            << OverlapVal.toString(10);
714          Diag(OverlapStmt->getLHS()->getLocStart(),
715               diag::note_duplicate_case_prev);
716          // FIXME: We really want to remove the bogus case stmt from the
717          // substmt, but we have no way to do this right now.
718          CaseListIsErroneous = true;
719        }
720      }
721    }
722  }
723
724  // FIXME: If the case list was broken is some way, we don't have a good system
725  // to patch it up.  Instead, just return the whole substmt as broken.
726  if (CaseListIsErroneous)
727    return StmtError();
728
729  Switch.release();
730  return Owned(SS);
731}
732
733Action::OwningStmtResult
734Sema::ActOnWhileStmt(SourceLocation WhileLoc, FullExprArg Cond,
735                     DeclPtrTy CondVar, StmtArg Body) {
736  OwningExprResult CondResult(Cond.release());
737
738  VarDecl *ConditionVar = 0;
739  if (CondVar.get()) {
740    ConditionVar = CondVar.getAs<VarDecl>();
741    CondResult = CheckConditionVariable(ConditionVar);
742    if (CondResult.isInvalid())
743      return StmtError();
744  }
745  Expr *ConditionExpr = CondResult.takeAs<Expr>();
746  if (!ConditionExpr)
747    return StmtError();
748
749  if (CheckBooleanCondition(ConditionExpr, WhileLoc)) {
750    CondResult = ConditionExpr;
751    return StmtError();
752  }
753
754  Stmt *bodyStmt = Body.takeAs<Stmt>();
755  DiagnoseUnusedExprResult(bodyStmt);
756
757  CondResult.release();
758  return Owned(new (Context) WhileStmt(ConditionVar, ConditionExpr, bodyStmt,
759                                       WhileLoc));
760}
761
762Action::OwningStmtResult
763Sema::ActOnDoStmt(SourceLocation DoLoc, StmtArg Body,
764                  SourceLocation WhileLoc, SourceLocation CondLParen,
765                  ExprArg Cond, SourceLocation CondRParen) {
766  Expr *condExpr = Cond.takeAs<Expr>();
767  assert(condExpr && "ActOnDoStmt(): missing expression");
768
769  if (CheckBooleanCondition(condExpr, DoLoc)) {
770    Cond = condExpr;
771    return StmtError();
772  }
773
774  Stmt *bodyStmt = Body.takeAs<Stmt>();
775  DiagnoseUnusedExprResult(bodyStmt);
776
777  Cond.release();
778  return Owned(new (Context) DoStmt(bodyStmt, condExpr, DoLoc,
779                                    WhileLoc, CondRParen));
780}
781
782Action::OwningStmtResult
783Sema::ActOnForStmt(SourceLocation ForLoc, SourceLocation LParenLoc,
784                   StmtArg first, FullExprArg second, DeclPtrTy secondVar,
785                   FullExprArg third,
786                   SourceLocation RParenLoc, StmtArg body) {
787  Stmt *First  = static_cast<Stmt*>(first.get());
788
789  if (!getLangOptions().CPlusPlus) {
790    if (DeclStmt *DS = dyn_cast_or_null<DeclStmt>(First)) {
791      // C99 6.8.5p3: The declaration part of a 'for' statement shall only
792      // declare identifiers for objects having storage class 'auto' or
793      // 'register'.
794      for (DeclStmt::decl_iterator DI=DS->decl_begin(), DE=DS->decl_end();
795           DI!=DE; ++DI) {
796        VarDecl *VD = dyn_cast<VarDecl>(*DI);
797        if (VD && VD->isBlockVarDecl() && !VD->hasLocalStorage())
798          VD = 0;
799        if (VD == 0)
800          Diag((*DI)->getLocation(), diag::err_non_variable_decl_in_for);
801        // FIXME: mark decl erroneous!
802      }
803    }
804  }
805
806  OwningExprResult SecondResult(second.release());
807  VarDecl *ConditionVar = 0;
808  if (secondVar.get()) {
809    ConditionVar = secondVar.getAs<VarDecl>();
810    SecondResult = CheckConditionVariable(ConditionVar);
811    if (SecondResult.isInvalid())
812      return StmtError();
813  }
814
815  Expr *Second = SecondResult.takeAs<Expr>();
816  if (Second && CheckBooleanCondition(Second, ForLoc)) {
817    SecondResult = Second;
818    return StmtError();
819  }
820
821  Expr *Third  = third.release().takeAs<Expr>();
822  Stmt *Body  = static_cast<Stmt*>(body.get());
823
824  DiagnoseUnusedExprResult(First);
825  DiagnoseUnusedExprResult(Third);
826  DiagnoseUnusedExprResult(Body);
827
828  first.release();
829  body.release();
830  return Owned(new (Context) ForStmt(First, Second, ConditionVar, Third, Body,
831                                     ForLoc, LParenLoc, RParenLoc));
832}
833
834Action::OwningStmtResult
835Sema::ActOnObjCForCollectionStmt(SourceLocation ForLoc,
836                                 SourceLocation LParenLoc,
837                                 StmtArg first, ExprArg second,
838                                 SourceLocation RParenLoc, StmtArg body) {
839  Stmt *First  = static_cast<Stmt*>(first.get());
840  Expr *Second = static_cast<Expr*>(second.get());
841  Stmt *Body  = static_cast<Stmt*>(body.get());
842  if (First) {
843    QualType FirstType;
844    if (DeclStmt *DS = dyn_cast<DeclStmt>(First)) {
845      if (!DS->isSingleDecl())
846        return StmtError(Diag((*DS->decl_begin())->getLocation(),
847                         diag::err_toomany_element_decls));
848
849      Decl *D = DS->getSingleDecl();
850      FirstType = cast<ValueDecl>(D)->getType();
851      // C99 6.8.5p3: The declaration part of a 'for' statement shall only
852      // declare identifiers for objects having storage class 'auto' or
853      // 'register'.
854      VarDecl *VD = cast<VarDecl>(D);
855      if (VD->isBlockVarDecl() && !VD->hasLocalStorage())
856        return StmtError(Diag(VD->getLocation(),
857                              diag::err_non_variable_decl_in_for));
858    } else {
859      if (cast<Expr>(First)->isLvalue(Context) != Expr::LV_Valid)
860        return StmtError(Diag(First->getLocStart(),
861                   diag::err_selector_element_not_lvalue)
862          << First->getSourceRange());
863
864      FirstType = static_cast<Expr*>(First)->getType();
865    }
866    if (!FirstType->isObjCObjectPointerType() &&
867        !FirstType->isBlockPointerType())
868        Diag(ForLoc, diag::err_selector_element_type)
869          << FirstType << First->getSourceRange();
870  }
871  if (Second) {
872    DefaultFunctionArrayConversion(Second);
873    QualType SecondType = Second->getType();
874    if (!SecondType->isObjCObjectPointerType())
875      Diag(ForLoc, diag::err_collection_expr_type)
876        << SecondType << Second->getSourceRange();
877  }
878  first.release();
879  second.release();
880  body.release();
881  return Owned(new (Context) ObjCForCollectionStmt(First, Second, Body,
882                                                   ForLoc, RParenLoc));
883}
884
885Action::OwningStmtResult
886Sema::ActOnGotoStmt(SourceLocation GotoLoc, SourceLocation LabelLoc,
887                    IdentifierInfo *LabelII) {
888  // If we are in a block, reject all gotos for now.
889  if (CurBlock)
890    return StmtError(Diag(GotoLoc, diag::err_goto_in_block));
891
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    AssignConvertType ConvTy =
910      CheckSingleAssignmentConstraints(Context.VoidPtrTy, E);
911    if (DiagnoseAssignmentResult(ConvTy, StarLoc, Context.VoidPtrTy, ETy,
912                                 E, "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      DefaultFunctionArrayConversion(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    QualType RetValType = RetValExp->getType();
988
989    // C99 6.8.6.4p3(136): The return statement is not an assignment. The
990    // overlap restriction of subclause 6.5.16.1 does not apply to the case of
991    // function return.
992
993    // In C++ the return statement is handled via a copy initialization.
994    // the C version of which boils down to CheckSingleAssignmentConstraints.
995    // FIXME: Leaks RetValExp.
996    if (PerformCopyInitialization(RetValExp, FnRetType, "returning"))
997      return StmtError();
998
999    if (RetValExp) CheckReturnStackAddr(RetValExp, FnRetType, ReturnLoc);
1000  }
1001
1002  return Owned(new (Context) ReturnStmt(ReturnLoc, RetValExp));
1003}
1004
1005/// IsReturnCopyElidable - Whether returning @p RetExpr from a function that
1006/// returns a @p RetType fulfills the criteria for copy elision (C++0x 12.8p15).
1007static bool IsReturnCopyElidable(ASTContext &Ctx, QualType RetType,
1008                                 Expr *RetExpr) {
1009  QualType ExprType = RetExpr->getType();
1010  // - in a return statement in a function with ...
1011  // ... a class return type ...
1012  if (!RetType->isRecordType())
1013    return false;
1014  // ... the same cv-unqualified type as the function return type ...
1015  if (!Ctx.hasSameUnqualifiedType(RetType, ExprType))
1016    return false;
1017  // ... the expression is the name of a non-volatile automatic object ...
1018  // We ignore parentheses here.
1019  // FIXME: Is this compliant?
1020  const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(RetExpr->IgnoreParens());
1021  if (!DR)
1022    return false;
1023  const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl());
1024  if (!VD)
1025    return false;
1026  return VD->hasLocalStorage() && !VD->getType()->isReferenceType()
1027    && !VD->getType().isVolatileQualified();
1028}
1029
1030Action::OwningStmtResult
1031Sema::ActOnReturnStmt(SourceLocation ReturnLoc, ExprArg rex) {
1032  Expr *RetValExp = rex.takeAs<Expr>();
1033  if (CurBlock)
1034    return ActOnBlockReturnStmt(ReturnLoc, RetValExp);
1035
1036  QualType FnRetType;
1037  if (const FunctionDecl *FD = getCurFunctionDecl()) {
1038    FnRetType = FD->getResultType();
1039    if (FD->hasAttr<NoReturnAttr>())
1040      Diag(ReturnLoc, diag::warn_noreturn_function_has_return_expr)
1041        << getCurFunctionOrMethodDecl()->getDeclName();
1042  } else if (ObjCMethodDecl *MD = getCurMethodDecl())
1043    FnRetType = MD->getResultType();
1044  else // If we don't have a function/method context, bail.
1045    return StmtError();
1046
1047  if (FnRetType->isVoidType()) {
1048    if (RetValExp && !RetValExp->isTypeDependent()) {
1049      // C99 6.8.6.4p1 (ext_ since GCC warns)
1050      unsigned D = diag::ext_return_has_expr;
1051      if (RetValExp->getType()->isVoidType())
1052        D = diag::ext_return_has_void_expr;
1053
1054      // return (some void expression); is legal in C++.
1055      if (D != diag::ext_return_has_void_expr ||
1056          !getLangOptions().CPlusPlus) {
1057        NamedDecl *CurDecl = getCurFunctionOrMethodDecl();
1058        Diag(ReturnLoc, D)
1059          << CurDecl->getDeclName() << isa<ObjCMethodDecl>(CurDecl)
1060          << RetValExp->getSourceRange();
1061      }
1062
1063      RetValExp = MaybeCreateCXXExprWithTemporaries(RetValExp, true);
1064    }
1065    return Owned(new (Context) ReturnStmt(ReturnLoc, RetValExp));
1066  }
1067
1068  if (!RetValExp && !FnRetType->isDependentType()) {
1069    unsigned DiagID = diag::warn_return_missing_expr;  // C90 6.6.6.4p4
1070    // C99 6.8.6.4p1 (ext_ since GCC warns)
1071    if (getLangOptions().C99) DiagID = diag::ext_return_missing_expr;
1072
1073    if (FunctionDecl *FD = getCurFunctionDecl())
1074      Diag(ReturnLoc, DiagID) << FD->getIdentifier() << 0/*fn*/;
1075    else
1076      Diag(ReturnLoc, DiagID) << getCurMethodDecl()->getDeclName() << 1/*meth*/;
1077    return Owned(new (Context) ReturnStmt(ReturnLoc, (Expr*)0));
1078  }
1079
1080  if (!FnRetType->isDependentType() && !RetValExp->isTypeDependent()) {
1081    // we have a non-void function with an expression, continue checking
1082
1083    // C99 6.8.6.4p3(136): The return statement is not an assignment. The
1084    // overlap restriction of subclause 6.5.16.1 does not apply to the case of
1085    // function return.
1086
1087    // C++0x 12.8p15: When certain criteria are met, an implementation is
1088    //   allowed to omit the copy construction of a class object, [...]
1089    //   - in a return statement in a function with a class return type, when
1090    //     the expression is the name of a non-volatile automatic object with
1091    //     the same cv-unqualified type as the function return type, the copy
1092    //     operation can be omitted [...]
1093    // C++0x 12.8p16: When the criteria for elision of a copy operation are met
1094    //   and the object to be copied is designated by an lvalue, overload
1095    //   resolution to select the constructor for the copy is first performed
1096    //   as if the object were designated by an rvalue.
1097    // Note that we only compute Elidable if we're in C++0x, since we don't
1098    // care otherwise.
1099    bool Elidable = getLangOptions().CPlusPlus0x ?
1100                      IsReturnCopyElidable(Context, FnRetType, RetValExp) :
1101                      false;
1102
1103    // In C++ the return statement is handled via a copy initialization.
1104    // the C version of which boils down to CheckSingleAssignmentConstraints.
1105    // FIXME: Leaks RetValExp on error.
1106    if (PerformCopyInitialization(RetValExp, FnRetType, "returning", Elidable)){
1107      // We should still clean up our temporaries, even when we're failing!
1108      RetValExp = MaybeCreateCXXExprWithTemporaries(RetValExp, true);
1109      return StmtError();
1110    }
1111
1112    if (RetValExp) CheckReturnStackAddr(RetValExp, FnRetType, ReturnLoc);
1113  }
1114
1115  if (RetValExp)
1116    RetValExp = MaybeCreateCXXExprWithTemporaries(RetValExp, true);
1117  return Owned(new (Context) ReturnStmt(ReturnLoc, RetValExp));
1118}
1119
1120/// CheckAsmLValue - GNU C has an extremely ugly extension whereby they silently
1121/// ignore "noop" casts in places where an lvalue is required by an inline asm.
1122/// We emulate this behavior when -fheinous-gnu-extensions is specified, but
1123/// provide a strong guidance to not use it.
1124///
1125/// This method checks to see if the argument is an acceptable l-value and
1126/// returns false if it is a case we can handle.
1127static bool CheckAsmLValue(const Expr *E, Sema &S) {
1128  if (E->isLvalue(S.Context) == Expr::LV_Valid)
1129    return false;  // Cool, this is an lvalue.
1130
1131  // Okay, this is not an lvalue, but perhaps it is the result of a cast that we
1132  // are supposed to allow.
1133  const Expr *E2 = E->IgnoreParenNoopCasts(S.Context);
1134  if (E != E2 && E2->isLvalue(S.Context) == Expr::LV_Valid) {
1135    if (!S.getLangOptions().HeinousExtensions)
1136      S.Diag(E2->getLocStart(), diag::err_invalid_asm_cast_lvalue)
1137        << E->getSourceRange();
1138    else
1139      S.Diag(E2->getLocStart(), diag::warn_invalid_asm_cast_lvalue)
1140        << E->getSourceRange();
1141    // Accept, even if we emitted an error diagnostic.
1142    return false;
1143  }
1144
1145  // None of the above, just randomly invalid non-lvalue.
1146  return true;
1147}
1148
1149
1150Sema::OwningStmtResult Sema::ActOnAsmStmt(SourceLocation AsmLoc,
1151                                          bool IsSimple,
1152                                          bool IsVolatile,
1153                                          unsigned NumOutputs,
1154                                          unsigned NumInputs,
1155                                          std::string *Names,
1156                                          MultiExprArg constraints,
1157                                          MultiExprArg exprs,
1158                                          ExprArg asmString,
1159                                          MultiExprArg clobbers,
1160                                          SourceLocation RParenLoc) {
1161  unsigned NumClobbers = clobbers.size();
1162  StringLiteral **Constraints =
1163    reinterpret_cast<StringLiteral**>(constraints.get());
1164  Expr **Exprs = reinterpret_cast<Expr **>(exprs.get());
1165  StringLiteral *AsmString = cast<StringLiteral>((Expr *)asmString.get());
1166  StringLiteral **Clobbers = reinterpret_cast<StringLiteral**>(clobbers.get());
1167
1168  llvm::SmallVector<TargetInfo::ConstraintInfo, 4> OutputConstraintInfos;
1169
1170  // The parser verifies that there is a string literal here.
1171  if (AsmString->isWide())
1172    return StmtError(Diag(AsmString->getLocStart(),diag::err_asm_wide_character)
1173      << AsmString->getSourceRange());
1174
1175  for (unsigned i = 0; i != NumOutputs; i++) {
1176    StringLiteral *Literal = Constraints[i];
1177    if (Literal->isWide())
1178      return StmtError(Diag(Literal->getLocStart(),diag::err_asm_wide_character)
1179        << Literal->getSourceRange());
1180
1181    TargetInfo::ConstraintInfo Info(Literal->getStrData(),
1182                                    Literal->getByteLength(),
1183                                    Names[i]);
1184    if (!Context.Target.validateOutputConstraint(Info))
1185      return StmtError(Diag(Literal->getLocStart(),
1186                            diag::err_asm_invalid_output_constraint)
1187                       << Info.getConstraintStr());
1188
1189    // Check that the output exprs are valid lvalues.
1190    Expr *OutputExpr = Exprs[i];
1191    if (CheckAsmLValue(OutputExpr, *this)) {
1192      return StmtError(Diag(OutputExpr->getLocStart(),
1193                  diag::err_asm_invalid_lvalue_in_output)
1194        << OutputExpr->getSourceRange());
1195    }
1196
1197    OutputConstraintInfos.push_back(Info);
1198  }
1199
1200  llvm::SmallVector<TargetInfo::ConstraintInfo, 4> InputConstraintInfos;
1201
1202  for (unsigned i = NumOutputs, e = NumOutputs + NumInputs; i != e; i++) {
1203    StringLiteral *Literal = Constraints[i];
1204    if (Literal->isWide())
1205      return StmtError(Diag(Literal->getLocStart(),diag::err_asm_wide_character)
1206        << Literal->getSourceRange());
1207
1208    TargetInfo::ConstraintInfo Info(Literal->getStrData(),
1209                                    Literal->getByteLength(),
1210                                    Names[i]);
1211    if (!Context.Target.validateInputConstraint(OutputConstraintInfos.data(),
1212                                                NumOutputs, Info)) {
1213      return StmtError(Diag(Literal->getLocStart(),
1214                            diag::err_asm_invalid_input_constraint)
1215                       << Info.getConstraintStr());
1216    }
1217
1218    Expr *InputExpr = Exprs[i];
1219
1220    // Only allow void types for memory constraints.
1221    if (Info.allowsMemory() && !Info.allowsRegister()) {
1222      if (CheckAsmLValue(InputExpr, *this))
1223        return StmtError(Diag(InputExpr->getLocStart(),
1224                              diag::err_asm_invalid_lvalue_in_input)
1225                         << Info.getConstraintStr()
1226                         << InputExpr->getSourceRange());
1227    }
1228
1229    if (Info.allowsRegister()) {
1230      if (InputExpr->getType()->isVoidType()) {
1231        return StmtError(Diag(InputExpr->getLocStart(),
1232                              diag::err_asm_invalid_type_in_input)
1233          << InputExpr->getType() << Info.getConstraintStr()
1234          << InputExpr->getSourceRange());
1235      }
1236    }
1237
1238    DefaultFunctionArrayConversion(Exprs[i]);
1239
1240    InputConstraintInfos.push_back(Info);
1241  }
1242
1243  // Check that the clobbers are valid.
1244  for (unsigned i = 0; i != NumClobbers; i++) {
1245    StringLiteral *Literal = Clobbers[i];
1246    if (Literal->isWide())
1247      return StmtError(Diag(Literal->getLocStart(),diag::err_asm_wide_character)
1248        << Literal->getSourceRange());
1249
1250    std::string Clobber(Literal->getStrData(),
1251                        Literal->getStrData() +
1252                        Literal->getByteLength());
1253
1254    if (!Context.Target.isValidGCCRegisterName(Clobber.c_str()))
1255      return StmtError(Diag(Literal->getLocStart(),
1256                  diag::err_asm_unknown_register_name) << Clobber);
1257  }
1258
1259  constraints.release();
1260  exprs.release();
1261  asmString.release();
1262  clobbers.release();
1263  AsmStmt *NS =
1264    new (Context) AsmStmt(AsmLoc, IsSimple, IsVolatile, NumOutputs, NumInputs,
1265                          Names, Constraints, Exprs, AsmString, NumClobbers,
1266                          Clobbers, RParenLoc);
1267  // Validate the asm string, ensuring it makes sense given the operands we
1268  // have.
1269  llvm::SmallVector<AsmStmt::AsmStringPiece, 8> Pieces;
1270  unsigned DiagOffs;
1271  if (unsigned DiagID = NS->AnalyzeAsmString(Pieces, Context, DiagOffs)) {
1272    Diag(getLocationOfStringLiteralByte(AsmString, DiagOffs), DiagID)
1273           << AsmString->getSourceRange();
1274    DeleteStmt(NS);
1275    return StmtError();
1276  }
1277
1278  // Validate tied input operands for type mismatches.
1279  for (unsigned i = 0, e = InputConstraintInfos.size(); i != e; ++i) {
1280    TargetInfo::ConstraintInfo &Info = InputConstraintInfos[i];
1281
1282    // If this is a tied constraint, verify that the output and input have
1283    // either exactly the same type, or that they are int/ptr operands with the
1284    // same size (int/long, int*/long, are ok etc).
1285    if (!Info.hasTiedOperand()) continue;
1286
1287    unsigned TiedTo = Info.getTiedOperand();
1288    Expr *OutputExpr = Exprs[TiedTo];
1289    Expr *InputExpr = Exprs[i+NumOutputs];
1290    QualType InTy = InputExpr->getType();
1291    QualType OutTy = OutputExpr->getType();
1292    if (Context.hasSameType(InTy, OutTy))
1293      continue;  // All types can be tied to themselves.
1294
1295    // Int/ptr operands have some special cases that we allow.
1296    if ((OutTy->isIntegerType() || OutTy->isPointerType()) &&
1297        (InTy->isIntegerType() || InTy->isPointerType())) {
1298
1299      // They are ok if they are the same size.  Tying void* to int is ok if
1300      // they are the same size, for example.  This also allows tying void* to
1301      // int*.
1302      uint64_t OutSize = Context.getTypeSize(OutTy);
1303      uint64_t InSize = Context.getTypeSize(InTy);
1304      if (OutSize == InSize)
1305        continue;
1306
1307      // If the smaller input/output operand is not mentioned in the asm string,
1308      // then we can promote it and the asm string won't notice.  Check this
1309      // case now.
1310      bool SmallerValueMentioned = false;
1311      for (unsigned p = 0, e = Pieces.size(); p != e; ++p) {
1312        AsmStmt::AsmStringPiece &Piece = Pieces[p];
1313        if (!Piece.isOperand()) continue;
1314
1315        // If this is a reference to the input and if the input was the smaller
1316        // one, then we have to reject this asm.
1317        if (Piece.getOperandNo() == i+NumOutputs) {
1318          if (InSize < OutSize) {
1319            SmallerValueMentioned = true;
1320            break;
1321          }
1322        }
1323
1324        // If this is a reference to the input and if the input was the smaller
1325        // one, then we have to reject this asm.
1326        if (Piece.getOperandNo() == TiedTo) {
1327          if (InSize > OutSize) {
1328            SmallerValueMentioned = true;
1329            break;
1330          }
1331        }
1332      }
1333
1334      // If the smaller value wasn't mentioned in the asm string, and if the
1335      // output was a register, just extend the shorter one to the size of the
1336      // larger one.
1337      if (!SmallerValueMentioned &&
1338          OutputConstraintInfos[TiedTo].allowsRegister())
1339        continue;
1340    }
1341
1342    Diag(InputExpr->getLocStart(),
1343         diag::err_asm_tying_incompatible_types)
1344      << InTy << OutTy << OutputExpr->getSourceRange()
1345      << InputExpr->getSourceRange();
1346    DeleteStmt(NS);
1347    return StmtError();
1348  }
1349
1350  return Owned(NS);
1351}
1352
1353Action::OwningStmtResult
1354Sema::ActOnObjCAtCatchStmt(SourceLocation AtLoc,
1355                           SourceLocation RParen, DeclPtrTy Parm,
1356                           StmtArg Body, StmtArg catchList) {
1357  Stmt *CatchList = catchList.takeAs<Stmt>();
1358  ParmVarDecl *PVD = cast_or_null<ParmVarDecl>(Parm.getAs<Decl>());
1359
1360  // PVD == 0 implies @catch(...).
1361  if (PVD) {
1362    // If we already know the decl is invalid, reject it.
1363    if (PVD->isInvalidDecl())
1364      return StmtError();
1365
1366    if (!PVD->getType()->isObjCObjectPointerType())
1367      return StmtError(Diag(PVD->getLocation(),
1368                       diag::err_catch_param_not_objc_type));
1369    if (PVD->getType()->isObjCQualifiedIdType())
1370      return StmtError(Diag(PVD->getLocation(),
1371                       diag::err_illegal_qualifiers_on_catch_parm));
1372  }
1373
1374  ObjCAtCatchStmt *CS = new (Context) ObjCAtCatchStmt(AtLoc, RParen,
1375    PVD, Body.takeAs<Stmt>(), CatchList);
1376  return Owned(CatchList ? CatchList : CS);
1377}
1378
1379Action::OwningStmtResult
1380Sema::ActOnObjCAtFinallyStmt(SourceLocation AtLoc, StmtArg Body) {
1381  return Owned(new (Context) ObjCAtFinallyStmt(AtLoc,
1382                                           static_cast<Stmt*>(Body.release())));
1383}
1384
1385Action::OwningStmtResult
1386Sema::ActOnObjCAtTryStmt(SourceLocation AtLoc,
1387                         StmtArg Try, StmtArg Catch, StmtArg Finally) {
1388  CurFunctionNeedsScopeChecking = true;
1389  return Owned(new (Context) ObjCAtTryStmt(AtLoc, Try.takeAs<Stmt>(),
1390                                           Catch.takeAs<Stmt>(),
1391                                           Finally.takeAs<Stmt>()));
1392}
1393
1394Action::OwningStmtResult
1395Sema::ActOnObjCAtThrowStmt(SourceLocation AtLoc, ExprArg expr,Scope *CurScope) {
1396  Expr *ThrowExpr = expr.takeAs<Expr>();
1397  if (!ThrowExpr) {
1398    // @throw without an expression designates a rethrow (which much occur
1399    // in the context of an @catch clause).
1400    Scope *AtCatchParent = CurScope;
1401    while (AtCatchParent && !AtCatchParent->isAtCatchScope())
1402      AtCatchParent = AtCatchParent->getParent();
1403    if (!AtCatchParent)
1404      return StmtError(Diag(AtLoc, diag::error_rethrow_used_outside_catch));
1405  } else {
1406    QualType ThrowType = ThrowExpr->getType();
1407    // Make sure the expression type is an ObjC pointer or "void *".
1408    if (!ThrowType->isObjCObjectPointerType()) {
1409      const PointerType *PT = ThrowType->getAs<PointerType>();
1410      if (!PT || !PT->getPointeeType()->isVoidType())
1411        return StmtError(Diag(AtLoc, diag::error_objc_throw_expects_object)
1412                        << ThrowExpr->getType() << ThrowExpr->getSourceRange());
1413    }
1414  }
1415  return Owned(new (Context) ObjCAtThrowStmt(AtLoc, ThrowExpr));
1416}
1417
1418Action::OwningStmtResult
1419Sema::ActOnObjCAtSynchronizedStmt(SourceLocation AtLoc, ExprArg SynchExpr,
1420                                  StmtArg SynchBody) {
1421  CurFunctionNeedsScopeChecking = true;
1422
1423  // Make sure the expression type is an ObjC pointer or "void *".
1424  Expr *SyncExpr = static_cast<Expr*>(SynchExpr.get());
1425  if (!SyncExpr->getType()->isObjCObjectPointerType()) {
1426    const PointerType *PT = SyncExpr->getType()->getAs<PointerType>();
1427    if (!PT || !PT->getPointeeType()->isVoidType())
1428      return StmtError(Diag(AtLoc, diag::error_objc_synchronized_expects_object)
1429                       << SyncExpr->getType() << SyncExpr->getSourceRange());
1430  }
1431
1432  return Owned(new (Context) ObjCAtSynchronizedStmt(AtLoc,
1433                                                    SynchExpr.takeAs<Stmt>(),
1434                                                    SynchBody.takeAs<Stmt>()));
1435}
1436
1437/// ActOnCXXCatchBlock - Takes an exception declaration and a handler block
1438/// and creates a proper catch handler from them.
1439Action::OwningStmtResult
1440Sema::ActOnCXXCatchBlock(SourceLocation CatchLoc, DeclPtrTy ExDecl,
1441                         StmtArg HandlerBlock) {
1442  // There's nothing to test that ActOnExceptionDecl didn't already test.
1443  return Owned(new (Context) CXXCatchStmt(CatchLoc,
1444                                  cast_or_null<VarDecl>(ExDecl.getAs<Decl>()),
1445                                          HandlerBlock.takeAs<Stmt>()));
1446}
1447
1448class TypeWithHandler {
1449  QualType t;
1450  CXXCatchStmt *stmt;
1451public:
1452  TypeWithHandler(const QualType &type, CXXCatchStmt *statement)
1453  : t(type), stmt(statement) {}
1454
1455  // An arbitrary order is fine as long as it places identical
1456  // types next to each other.
1457  bool operator<(const TypeWithHandler &y) const {
1458    if (t.getAsOpaquePtr() < y.t.getAsOpaquePtr())
1459      return true;
1460    if (t.getAsOpaquePtr() > y.t.getAsOpaquePtr())
1461      return false;
1462    else
1463      return getTypeSpecStartLoc() < y.getTypeSpecStartLoc();
1464  }
1465
1466  bool operator==(const TypeWithHandler& other) const {
1467    return t == other.t;
1468  }
1469
1470  QualType getQualType() const { return t; }
1471  CXXCatchStmt *getCatchStmt() const { return stmt; }
1472  SourceLocation getTypeSpecStartLoc() const {
1473    return stmt->getExceptionDecl()->getTypeSpecStartLoc();
1474  }
1475};
1476
1477/// ActOnCXXTryBlock - Takes a try compound-statement and a number of
1478/// handlers and creates a try statement from them.
1479Action::OwningStmtResult
1480Sema::ActOnCXXTryBlock(SourceLocation TryLoc, StmtArg TryBlock,
1481                       MultiStmtArg RawHandlers) {
1482  unsigned NumHandlers = RawHandlers.size();
1483  assert(NumHandlers > 0 &&
1484         "The parser shouldn't call this if there are no handlers.");
1485  Stmt **Handlers = reinterpret_cast<Stmt**>(RawHandlers.get());
1486
1487  llvm::SmallVector<TypeWithHandler, 8> TypesWithHandlers;
1488
1489  for (unsigned i = 0; i < NumHandlers; ++i) {
1490    CXXCatchStmt *Handler = llvm::cast<CXXCatchStmt>(Handlers[i]);
1491    if (!Handler->getExceptionDecl()) {
1492      if (i < NumHandlers - 1)
1493        return StmtError(Diag(Handler->getLocStart(),
1494                              diag::err_early_catch_all));
1495
1496      continue;
1497    }
1498
1499    const QualType CaughtType = Handler->getCaughtType();
1500    const QualType CanonicalCaughtType = Context.getCanonicalType(CaughtType);
1501    TypesWithHandlers.push_back(TypeWithHandler(CanonicalCaughtType, Handler));
1502  }
1503
1504  // Detect handlers for the same type as an earlier one.
1505  if (NumHandlers > 1) {
1506    llvm::array_pod_sort(TypesWithHandlers.begin(), TypesWithHandlers.end());
1507
1508    TypeWithHandler prev = TypesWithHandlers[0];
1509    for (unsigned i = 1; i < TypesWithHandlers.size(); ++i) {
1510      TypeWithHandler curr = TypesWithHandlers[i];
1511
1512      if (curr == prev) {
1513        Diag(curr.getTypeSpecStartLoc(),
1514             diag::warn_exception_caught_by_earlier_handler)
1515          << curr.getCatchStmt()->getCaughtType().getAsString();
1516        Diag(prev.getTypeSpecStartLoc(),
1517             diag::note_previous_exception_handler)
1518          << prev.getCatchStmt()->getCaughtType().getAsString();
1519      }
1520
1521      prev = curr;
1522    }
1523  }
1524
1525  // FIXME: We should detect handlers that cannot catch anything because an
1526  // earlier handler catches a superclass. Need to find a method that is not
1527  // quadratic for this.
1528  // Neither of these are explicitly forbidden, but every compiler detects them
1529  // and warns.
1530
1531  CurFunctionNeedsScopeChecking = true;
1532  RawHandlers.release();
1533  return Owned(new (Context) CXXTryStmt(TryLoc,
1534                                        static_cast<Stmt*>(TryBlock.release()),
1535                                        Handlers, NumHandlers));
1536}
1537