SemaStmt.cpp revision 12356b119032edd64e9c32f9f01920d12c2acc57 
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/ExprObjC.h"
19#include "clang/AST/StmtObjC.h"
20#include "clang/AST/StmtCXX.h"
21#include "clang/Basic/TargetInfo.h"
22#include "llvm/ADT/STLExtras.h"
23#include "llvm/ADT/SmallVector.h"
24using namespace clang;
25
26Sema::OwningStmtResult Sema::ActOnExprStmt(FullExprArg expr) {
27  Expr *E = expr->takeAs<Expr>();
28  assert(E && "ActOnExprStmt(): missing expression");
29  if (E->getType()->isObjCInterfaceType()) {
30    if (LangOpts.ObjCNonFragileABI)
31      Diag(E->getLocEnd(), diag::err_indirection_requires_nonfragile_object)
32             << E->getType();
33    else
34      Diag(E->getLocEnd(), diag::err_direct_interface_unsupported)
35             << E->getType();
36    return StmtError();
37  }
38  // C99 6.8.3p2: The expression in an expression statement is evaluated as a
39  // void expression for its side effects.  Conversion to void allows any
40  // operand, even incomplete types.
41
42  // Same thing in for stmt first clause (when expr) and third clause.
43  return Owned(static_cast<Stmt*>(E));
44}
45
46
47Sema::OwningStmtResult Sema::ActOnNullStmt(SourceLocation SemiLoc) {
48  return Owned(new (Context) NullStmt(SemiLoc));
49}
50
51Sema::OwningStmtResult Sema::ActOnDeclStmt(DeclGroupPtrTy dg,
52                                           SourceLocation StartLoc,
53                                           SourceLocation EndLoc) {
54  DeclGroupRef DG = dg.getAsVal<DeclGroupRef>();
55
56  // If we have an invalid decl, just return an error.
57  if (DG.isNull()) return StmtError();
58
59  return Owned(new (Context) DeclStmt(DG, StartLoc, EndLoc));
60}
61
62void Sema::DiagnoseUnusedExprResult(const Stmt *S) {
63  const Expr *E = dyn_cast_or_null<Expr>(S);
64  if (!E)
65    return;
66
67  // Ignore expressions that have void type.
68  if (E->getType()->isVoidType())
69    return;
70
71  SourceLocation Loc;
72  SourceRange R1, R2;
73  if (!E->isUnusedResultAWarning(Loc, R1, R2))
74    return;
75
76  // Okay, we have an unused result.  Depending on what the base expression is,
77  // we might want to make a more specific diagnostic.  Check for one of these
78  // cases now.
79  unsigned DiagID = diag::warn_unused_expr;
80  E = E->IgnoreParens();
81  if (isa<ObjCImplicitSetterGetterRefExpr>(E))
82    DiagID = diag::warn_unused_property_expr;
83
84  if (const CallExpr *CE = dyn_cast<CallExpr>(E)) {
85    // If the callee has attribute pure, const, or warn_unused_result, warn with
86    // a more specific message to make it clear what is happening.
87    if (const FunctionDecl *FD = CE->getDirectCallee()) {
88      if (FD->getAttr<WarnUnusedResultAttr>()) {
89        Diag(Loc, diag::warn_unused_call) << R1 << R2 << "warn_unused_result";
90        return;
91      }
92      if (FD->getAttr<PureAttr>()) {
93        Diag(Loc, diag::warn_unused_call) << R1 << R2 << "pure";
94        return;
95      }
96      if (FD->getAttr<ConstAttr>()) {
97        Diag(Loc, diag::warn_unused_call) << R1 << R2 << "const";
98        return;
99      }
100    }
101  }
102
103  Diag(Loc, DiagID) << R1 << R2;
104}
105
106Action::OwningStmtResult
107Sema::ActOnCompoundStmt(SourceLocation L, SourceLocation R,
108                        MultiStmtArg elts, bool isStmtExpr) {
109  unsigned NumElts = elts.size();
110  Stmt **Elts = reinterpret_cast<Stmt**>(elts.release());
111  // If we're in C89 mode, check that we don't have any decls after stmts.  If
112  // so, emit an extension diagnostic.
113  if (!getLangOptions().C99 && !getLangOptions().CPlusPlus) {
114    // Note that __extension__ can be around a decl.
115    unsigned i = 0;
116    // Skip over all declarations.
117    for (; i != NumElts && isa<DeclStmt>(Elts[i]); ++i)
118      /*empty*/;
119
120    // We found the end of the list or a statement.  Scan for another declstmt.
121    for (; i != NumElts && !isa<DeclStmt>(Elts[i]); ++i)
122      /*empty*/;
123
124    if (i != NumElts) {
125      Decl *D = *cast<DeclStmt>(Elts[i])->decl_begin();
126      Diag(D->getLocation(), diag::ext_mixed_decls_code);
127    }
128  }
129  // Warn about unused expressions in statements.
130  for (unsigned i = 0; i != NumElts; ++i) {
131    // Ignore statements that are last in a statement expression.
132    if (isStmtExpr && i == NumElts - 1)
133      continue;
134
135    DiagnoseUnusedExprResult(Elts[i]);
136  }
137
138  return Owned(new (Context) CompoundStmt(Context, Elts, NumElts, L, R));
139}
140
141Action::OwningStmtResult
142Sema::ActOnCaseStmt(SourceLocation CaseLoc, ExprArg lhsval,
143                    SourceLocation DotDotDotLoc, ExprArg rhsval,
144                    SourceLocation ColonLoc) {
145  assert((lhsval.get() != 0) && "missing expression in case statement");
146
147  // C99 6.8.4.2p3: The expression shall be an integer constant.
148  // However, GCC allows any evaluatable integer expression.
149  Expr *LHSVal = static_cast<Expr*>(lhsval.get());
150  if (!LHSVal->isTypeDependent() && !LHSVal->isValueDependent() &&
151      VerifyIntegerConstantExpression(LHSVal))
152    return StmtError();
153
154  // GCC extension: The expression shall be an integer constant.
155
156  Expr *RHSVal = static_cast<Expr*>(rhsval.get());
157  if (RHSVal && !RHSVal->isTypeDependent() && !RHSVal->isValueDependent() &&
158      VerifyIntegerConstantExpression(RHSVal)) {
159    RHSVal = 0;  // Recover by just forgetting about it.
160    rhsval = 0;
161  }
162
163  if (getSwitchStack().empty()) {
164    Diag(CaseLoc, diag::err_case_not_in_switch);
165    return StmtError();
166  }
167
168  // Only now release the smart pointers.
169  lhsval.release();
170  rhsval.release();
171  CaseStmt *CS = new (Context) CaseStmt(LHSVal, RHSVal, CaseLoc, DotDotDotLoc,
172                                        ColonLoc);
173  getSwitchStack().back()->addSwitchCase(CS);
174  return Owned(CS);
175}
176
177/// ActOnCaseStmtBody - This installs a statement as the body of a case.
178void Sema::ActOnCaseStmtBody(StmtTy *caseStmt, StmtArg subStmt) {
179  CaseStmt *CS = static_cast<CaseStmt*>(caseStmt);
180  Stmt *SubStmt = subStmt.takeAs<Stmt>();
181  CS->setSubStmt(SubStmt);
182}
183
184Action::OwningStmtResult
185Sema::ActOnDefaultStmt(SourceLocation DefaultLoc, SourceLocation ColonLoc,
186                       StmtArg subStmt, Scope *CurScope) {
187  Stmt *SubStmt = subStmt.takeAs<Stmt>();
188
189  if (getSwitchStack().empty()) {
190    Diag(DefaultLoc, diag::err_default_not_in_switch);
191    return Owned(SubStmt);
192  }
193
194  DefaultStmt *DS = new (Context) DefaultStmt(DefaultLoc, ColonLoc, SubStmt);
195  getSwitchStack().back()->addSwitchCase(DS);
196  return Owned(DS);
197}
198
199Action::OwningStmtResult
200Sema::ActOnLabelStmt(SourceLocation IdentLoc, IdentifierInfo *II,
201                     SourceLocation ColonLoc, StmtArg subStmt) {
202  Stmt *SubStmt = subStmt.takeAs<Stmt>();
203  // Look up the record for this label identifier.
204  LabelStmt *&LabelDecl = getLabelMap()[II];
205
206  // If not forward referenced or defined already, just create a new LabelStmt.
207  if (LabelDecl == 0)
208    return Owned(LabelDecl = new (Context) LabelStmt(IdentLoc, II, SubStmt));
209
210  assert(LabelDecl->getID() == II && "Label mismatch!");
211
212  // Otherwise, this label was either forward reference or multiply defined.  If
213  // multiply defined, reject it now.
214  if (LabelDecl->getSubStmt()) {
215    Diag(IdentLoc, diag::err_redefinition_of_label) << LabelDecl->getID();
216    Diag(LabelDecl->getIdentLoc(), diag::note_previous_definition);
217    return Owned(SubStmt);
218  }
219
220  // Otherwise, this label was forward declared, and we just found its real
221  // definition.  Fill in the forward definition and return it.
222  LabelDecl->setIdentLoc(IdentLoc);
223  LabelDecl->setSubStmt(SubStmt);
224  return Owned(LabelDecl);
225}
226
227Action::OwningStmtResult
228Sema::ActOnIfStmt(SourceLocation IfLoc, FullExprArg CondVal,
229                  StmtArg ThenVal, SourceLocation ElseLoc,
230                  StmtArg ElseVal) {
231  OwningExprResult CondResult(CondVal.release());
232
233  Expr *condExpr = CondResult.takeAs<Expr>();
234
235  assert(condExpr && "ActOnIfStmt(): missing expression");
236  if (CheckBooleanCondition(condExpr, IfLoc)) {
237    CondResult = condExpr;
238    return StmtError();
239  }
240
241  Stmt *thenStmt = ThenVal.takeAs<Stmt>();
242  DiagnoseUnusedExprResult(thenStmt);
243
244  // Warn if the if block has a null body without an else value.
245  // this helps prevent bugs due to typos, such as
246  // if (condition);
247  //   do_stuff();
248  if (!ElseVal.get()) {
249    if (NullStmt* stmt = dyn_cast<NullStmt>(thenStmt))
250      Diag(stmt->getSemiLoc(), diag::warn_empty_if_body);
251  }
252
253  Stmt *elseStmt = ElseVal.takeAs<Stmt>();
254  DiagnoseUnusedExprResult(elseStmt);
255
256  CondResult.release();
257  return Owned(new (Context) IfStmt(IfLoc, condExpr, thenStmt,
258                                    ElseLoc, elseStmt));
259}
260
261Action::OwningStmtResult
262Sema::ActOnStartOfSwitchStmt(ExprArg cond) {
263  Expr *Cond = cond.takeAs<Expr>();
264
265  if (getLangOptions().CPlusPlus) {
266    // C++ 6.4.2.p2:
267    // The condition shall be of integral type, enumeration type, or of a class
268    // type for which a single conversion function to integral or enumeration
269    // type exists (12.3). If the condition is of class type, the condition is
270    // converted by calling that conversion function, and the result of the
271    // conversion is used in place of the original condition for the remainder
272    // of this section. Integral promotions are performed.
273    if (!Cond->isTypeDependent()) {
274      QualType Ty = Cond->getType();
275
276      // FIXME: Handle class types.
277
278      // If the type is wrong a diagnostic will be emitted later at
279      // ActOnFinishSwitchStmt.
280      if (Ty->isIntegralType() || Ty->isEnumeralType()) {
281        // Integral promotions are performed.
282        // FIXME: Integral promotions for C++ are not complete.
283        UsualUnaryConversions(Cond);
284      }
285    }
286  } else {
287    // C99 6.8.4.2p5 - Integer promotions are performed on the controlling expr.
288    UsualUnaryConversions(Cond);
289  }
290
291  SwitchStmt *SS = new (Context) SwitchStmt(Cond);
292  getSwitchStack().push_back(SS);
293  return Owned(SS);
294}
295
296/// ConvertIntegerToTypeWarnOnOverflow - Convert the specified APInt to have
297/// the specified width and sign.  If an overflow occurs, detect it and emit
298/// the specified diagnostic.
299void Sema::ConvertIntegerToTypeWarnOnOverflow(llvm::APSInt &Val,
300                                              unsigned NewWidth, bool NewSign,
301                                              SourceLocation Loc,
302                                              unsigned DiagID) {
303  // Perform a conversion to the promoted condition type if needed.
304  if (NewWidth > Val.getBitWidth()) {
305    // If this is an extension, just do it.
306    llvm::APSInt OldVal(Val);
307    Val.extend(NewWidth);
308
309    // If the input was signed and negative and the output is unsigned,
310    // warn.
311    if (!NewSign && OldVal.isSigned() && OldVal.isNegative())
312      Diag(Loc, DiagID) << OldVal.toString(10) << Val.toString(10);
313
314    Val.setIsSigned(NewSign);
315  } else if (NewWidth < Val.getBitWidth()) {
316    // If this is a truncation, check for overflow.
317    llvm::APSInt ConvVal(Val);
318    ConvVal.trunc(NewWidth);
319    ConvVal.setIsSigned(NewSign);
320    ConvVal.extend(Val.getBitWidth());
321    ConvVal.setIsSigned(Val.isSigned());
322    if (ConvVal != Val)
323      Diag(Loc, DiagID) << Val.toString(10) << ConvVal.toString(10);
324
325    // Regardless of whether a diagnostic was emitted, really do the
326    // truncation.
327    Val.trunc(NewWidth);
328    Val.setIsSigned(NewSign);
329  } else if (NewSign != Val.isSigned()) {
330    // Convert the sign to match the sign of the condition.  This can cause
331    // overflow as well: unsigned(INTMIN)
332    llvm::APSInt OldVal(Val);
333    Val.setIsSigned(NewSign);
334
335    if (Val.isNegative())  // Sign bit changes meaning.
336      Diag(Loc, DiagID) << OldVal.toString(10) << Val.toString(10);
337  }
338}
339
340namespace {
341  struct CaseCompareFunctor {
342    bool operator()(const std::pair<llvm::APSInt, CaseStmt*> &LHS,
343                    const llvm::APSInt &RHS) {
344      return LHS.first < RHS;
345    }
346    bool operator()(const std::pair<llvm::APSInt, CaseStmt*> &LHS,
347                    const std::pair<llvm::APSInt, CaseStmt*> &RHS) {
348      return LHS.first < RHS.first;
349    }
350    bool operator()(const llvm::APSInt &LHS,
351                    const std::pair<llvm::APSInt, CaseStmt*> &RHS) {
352      return LHS < RHS.first;
353    }
354  };
355}
356
357/// CmpCaseVals - Comparison predicate for sorting case values.
358///
359static bool CmpCaseVals(const std::pair<llvm::APSInt, CaseStmt*>& lhs,
360                        const std::pair<llvm::APSInt, CaseStmt*>& rhs) {
361  if (lhs.first < rhs.first)
362    return true;
363
364  if (lhs.first == rhs.first &&
365      lhs.second->getCaseLoc().getRawEncoding()
366       < rhs.second->getCaseLoc().getRawEncoding())
367    return true;
368  return false;
369}
370
371/// GetTypeBeforeIntegralPromotion - Returns the pre-promotion type of
372/// potentially integral-promoted expression @p expr.
373static QualType GetTypeBeforeIntegralPromotion(const Expr* expr) {
374  const ImplicitCastExpr *ImplicitCast =
375      dyn_cast_or_null<ImplicitCastExpr>(expr);
376  if (ImplicitCast != NULL) {
377    const Expr *ExprBeforePromotion = ImplicitCast->getSubExpr();
378    QualType TypeBeforePromotion = ExprBeforePromotion->getType();
379    if (TypeBeforePromotion->isIntegralType()) {
380      return TypeBeforePromotion;
381    }
382  }
383  return expr->getType();
384}
385
386Action::OwningStmtResult
387Sema::ActOnFinishSwitchStmt(SourceLocation SwitchLoc, StmtArg Switch,
388                            StmtArg Body) {
389  Stmt *BodyStmt = Body.takeAs<Stmt>();
390
391  SwitchStmt *SS = getSwitchStack().back();
392  assert(SS == (SwitchStmt*)Switch.get() && "switch stack missing push/pop!");
393
394  SS->setBody(BodyStmt, SwitchLoc);
395  getSwitchStack().pop_back();
396
397  Expr *CondExpr = SS->getCond();
398  QualType CondType = CondExpr->getType();
399
400  // C++ 6.4.2.p2:
401  // Integral promotions are performed (on the switch condition).
402  //
403  // A case value unrepresentable by the original switch condition
404  // type (before the promotion) doesn't make sense, even when it can
405  // be represented by the promoted type.  Therefore we need to find
406  // the pre-promotion type of the switch condition.
407  QualType CondTypeBeforePromotion =
408      GetTypeBeforeIntegralPromotion(CondExpr);
409
410  if (!CondExpr->isTypeDependent()) {
411    if (!CondType->isIntegerType()) { // C99 6.8.4.2p1
412      Diag(SwitchLoc, diag::err_typecheck_statement_requires_integer)
413          << CondType << CondExpr->getSourceRange();
414      return StmtError();
415    }
416
417    if (CondTypeBeforePromotion->isBooleanType()) {
418      // switch(bool_expr) {...} is often a programmer error, e.g.
419      //   switch(n && mask) { ... }  // Doh - should be "n & mask".
420      // One can always use an if statement instead of switch(bool_expr).
421      Diag(SwitchLoc, diag::warn_bool_switch_condition)
422          << CondExpr->getSourceRange();
423    }
424  }
425
426  // Get the bitwidth of the switched-on value before promotions.  We must
427  // convert the integer case values to this width before comparison.
428  bool HasDependentValue
429    = CondExpr->isTypeDependent() || CondExpr->isValueDependent();
430  unsigned CondWidth
431    = HasDependentValue? 0
432      : static_cast<unsigned>(Context.getTypeSize(CondTypeBeforePromotion));
433  bool CondIsSigned = CondTypeBeforePromotion->isSignedIntegerType();
434
435  // Accumulate all of the case values in a vector so that we can sort them
436  // and detect duplicates.  This vector contains the APInt for the case after
437  // it has been converted to the condition type.
438  typedef llvm::SmallVector<std::pair<llvm::APSInt, CaseStmt*>, 64> CaseValsTy;
439  CaseValsTy CaseVals;
440
441  // Keep track of any GNU case ranges we see.  The APSInt is the low value.
442  std::vector<std::pair<llvm::APSInt, CaseStmt*> > CaseRanges;
443
444  DefaultStmt *TheDefaultStmt = 0;
445
446  bool CaseListIsErroneous = false;
447
448  for (SwitchCase *SC = SS->getSwitchCaseList(); SC && !HasDependentValue;
449       SC = SC->getNextSwitchCase()) {
450
451    if (DefaultStmt *DS = dyn_cast<DefaultStmt>(SC)) {
452      if (TheDefaultStmt) {
453        Diag(DS->getDefaultLoc(), diag::err_multiple_default_labels_defined);
454        Diag(TheDefaultStmt->getDefaultLoc(), diag::note_duplicate_case_prev);
455
456        // FIXME: Remove the default statement from the switch block so that
457        // we'll return a valid AST.  This requires recursing down the AST and
458        // finding it, not something we are set up to do right now.  For now,
459        // just lop the entire switch stmt out of the AST.
460        CaseListIsErroneous = true;
461      }
462      TheDefaultStmt = DS;
463
464    } else {
465      CaseStmt *CS = cast<CaseStmt>(SC);
466
467      // We already verified that the expression has a i-c-e value (C99
468      // 6.8.4.2p3) - get that value now.
469      Expr *Lo = CS->getLHS();
470
471      if (Lo->isTypeDependent() || Lo->isValueDependent()) {
472        HasDependentValue = true;
473        break;
474      }
475
476      llvm::APSInt LoVal = Lo->EvaluateAsInt(Context);
477
478      // Convert the value to the same width/sign as the condition.
479      ConvertIntegerToTypeWarnOnOverflow(LoVal, CondWidth, CondIsSigned,
480                                         CS->getLHS()->getLocStart(),
481                                         diag::warn_case_value_overflow);
482
483      // If the LHS is not the same type as the condition, insert an implicit
484      // cast.
485      ImpCastExprToType(Lo, CondType);
486      CS->setLHS(Lo);
487
488      // If this is a case range, remember it in CaseRanges, otherwise CaseVals.
489      if (CS->getRHS()) {
490        if (CS->getRHS()->isTypeDependent() ||
491            CS->getRHS()->isValueDependent()) {
492          HasDependentValue = true;
493          break;
494        }
495        CaseRanges.push_back(std::make_pair(LoVal, CS));
496      } else
497        CaseVals.push_back(std::make_pair(LoVal, CS));
498    }
499  }
500
501  if (!HasDependentValue) {
502    // Sort all the scalar case values so we can easily detect duplicates.
503    std::stable_sort(CaseVals.begin(), CaseVals.end(), CmpCaseVals);
504
505    if (!CaseVals.empty()) {
506      for (unsigned i = 0, e = CaseVals.size()-1; i != e; ++i) {
507        if (CaseVals[i].first == CaseVals[i+1].first) {
508          // If we have a duplicate, report it.
509          Diag(CaseVals[i+1].second->getLHS()->getLocStart(),
510               diag::err_duplicate_case) << CaseVals[i].first.toString(10);
511          Diag(CaseVals[i].second->getLHS()->getLocStart(),
512               diag::note_duplicate_case_prev);
513          // FIXME: We really want to remove the bogus case stmt from the
514          // substmt, but we have no way to do this right now.
515          CaseListIsErroneous = true;
516        }
517      }
518    }
519
520    // Detect duplicate case ranges, which usually don't exist at all in
521    // the first place.
522    if (!CaseRanges.empty()) {
523      // Sort all the case ranges by their low value so we can easily detect
524      // overlaps between ranges.
525      std::stable_sort(CaseRanges.begin(), CaseRanges.end());
526
527      // Scan the ranges, computing the high values and removing empty ranges.
528      std::vector<llvm::APSInt> HiVals;
529      for (unsigned i = 0, e = CaseRanges.size(); i != e; ++i) {
530        CaseStmt *CR = CaseRanges[i].second;
531        Expr *Hi = CR->getRHS();
532        llvm::APSInt HiVal = Hi->EvaluateAsInt(Context);
533
534        // Convert the value to the same width/sign as the condition.
535        ConvertIntegerToTypeWarnOnOverflow(HiVal, CondWidth, CondIsSigned,
536                                           CR->getRHS()->getLocStart(),
537                                           diag::warn_case_value_overflow);
538
539        // If the LHS is not the same type as the condition, insert an implicit
540        // cast.
541        ImpCastExprToType(Hi, CondType);
542        CR->setRHS(Hi);
543
544        // If the low value is bigger than the high value, the case is empty.
545        if (CaseRanges[i].first > HiVal) {
546          Diag(CR->getLHS()->getLocStart(), diag::warn_case_empty_range)
547            << SourceRange(CR->getLHS()->getLocStart(),
548                           CR->getRHS()->getLocEnd());
549          CaseRanges.erase(CaseRanges.begin()+i);
550          --i, --e;
551          continue;
552        }
553        HiVals.push_back(HiVal);
554      }
555
556      // Rescan the ranges, looking for overlap with singleton values and other
557      // ranges.  Since the range list is sorted, we only need to compare case
558      // ranges with their neighbors.
559      for (unsigned i = 0, e = CaseRanges.size(); i != e; ++i) {
560        llvm::APSInt &CRLo = CaseRanges[i].first;
561        llvm::APSInt &CRHi = HiVals[i];
562        CaseStmt *CR = CaseRanges[i].second;
563
564        // Check to see whether the case range overlaps with any
565        // singleton cases.
566        CaseStmt *OverlapStmt = 0;
567        llvm::APSInt OverlapVal(32);
568
569        // Find the smallest value >= the lower bound.  If I is in the
570        // case range, then we have overlap.
571        CaseValsTy::iterator I = std::lower_bound(CaseVals.begin(),
572                                                  CaseVals.end(), CRLo,
573                                                  CaseCompareFunctor());
574        if (I != CaseVals.end() && I->first < CRHi) {
575          OverlapVal  = I->first;   // Found overlap with scalar.
576          OverlapStmt = I->second;
577        }
578
579        // Find the smallest value bigger than the upper bound.
580        I = std::upper_bound(I, CaseVals.end(), CRHi, CaseCompareFunctor());
581        if (I != CaseVals.begin() && (I-1)->first >= CRLo) {
582          OverlapVal  = (I-1)->first;      // Found overlap with scalar.
583          OverlapStmt = (I-1)->second;
584        }
585
586        // Check to see if this case stmt overlaps with the subsequent
587        // case range.
588        if (i && CRLo <= HiVals[i-1]) {
589          OverlapVal  = HiVals[i-1];       // Found overlap with range.
590          OverlapStmt = CaseRanges[i-1].second;
591        }
592
593        if (OverlapStmt) {
594          // If we have a duplicate, report it.
595          Diag(CR->getLHS()->getLocStart(), diag::err_duplicate_case)
596            << OverlapVal.toString(10);
597          Diag(OverlapStmt->getLHS()->getLocStart(),
598               diag::note_duplicate_case_prev);
599          // FIXME: We really want to remove the bogus case stmt from the
600          // substmt, but we have no way to do this right now.
601          CaseListIsErroneous = true;
602        }
603      }
604    }
605  }
606
607  // FIXME: If the case list was broken is some way, we don't have a good system
608  // to patch it up.  Instead, just return the whole substmt as broken.
609  if (CaseListIsErroneous)
610    return StmtError();
611
612  Switch.release();
613  return Owned(SS);
614}
615
616Action::OwningStmtResult
617Sema::ActOnWhileStmt(SourceLocation WhileLoc, FullExprArg Cond, StmtArg Body) {
618  ExprArg CondArg(Cond.release());
619  Expr *condExpr = CondArg.takeAs<Expr>();
620  assert(condExpr && "ActOnWhileStmt(): missing expression");
621
622  if (CheckBooleanCondition(condExpr, WhileLoc)) {
623    CondArg = condExpr;
624    return StmtError();
625  }
626
627  Stmt *bodyStmt = Body.takeAs<Stmt>();
628  DiagnoseUnusedExprResult(bodyStmt);
629
630  CondArg.release();
631  return Owned(new (Context) WhileStmt(condExpr, bodyStmt, WhileLoc));
632}
633
634Action::OwningStmtResult
635Sema::ActOnDoStmt(SourceLocation DoLoc, StmtArg Body,
636                  SourceLocation WhileLoc, SourceLocation CondLParen,
637                  ExprArg Cond, SourceLocation CondRParen) {
638  Expr *condExpr = Cond.takeAs<Expr>();
639  assert(condExpr && "ActOnDoStmt(): missing expression");
640
641  if (CheckBooleanCondition(condExpr, DoLoc)) {
642    Cond = condExpr;
643    return StmtError();
644  }
645
646  Stmt *bodyStmt = Body.takeAs<Stmt>();
647  DiagnoseUnusedExprResult(bodyStmt);
648
649  Cond.release();
650  return Owned(new (Context) DoStmt(bodyStmt, condExpr, DoLoc,
651                                    WhileLoc, CondRParen));
652}
653
654Action::OwningStmtResult
655Sema::ActOnForStmt(SourceLocation ForLoc, SourceLocation LParenLoc,
656                   StmtArg first, ExprArg second, ExprArg third,
657                   SourceLocation RParenLoc, StmtArg body) {
658  Stmt *First  = static_cast<Stmt*>(first.get());
659  Expr *Second = second.takeAs<Expr>();
660  Expr *Third  = static_cast<Expr*>(third.get());
661  Stmt *Body  = static_cast<Stmt*>(body.get());
662
663  if (!getLangOptions().CPlusPlus) {
664    if (DeclStmt *DS = dyn_cast_or_null<DeclStmt>(First)) {
665      // C99 6.8.5p3: The declaration part of a 'for' statement shall only
666      // declare identifiers for objects having storage class 'auto' or
667      // 'register'.
668      for (DeclStmt::decl_iterator DI=DS->decl_begin(), DE=DS->decl_end();
669           DI!=DE; ++DI) {
670        VarDecl *VD = dyn_cast<VarDecl>(*DI);
671        if (VD && VD->isBlockVarDecl() && !VD->hasLocalStorage())
672          VD = 0;
673        if (VD == 0)
674          Diag((*DI)->getLocation(), diag::err_non_variable_decl_in_for);
675        // FIXME: mark decl erroneous!
676      }
677    }
678  }
679  if (Second && CheckBooleanCondition(Second, ForLoc)) {
680    second = Second;
681    return StmtError();
682  }
683
684  DiagnoseUnusedExprResult(First);
685  DiagnoseUnusedExprResult(Third);
686  DiagnoseUnusedExprResult(Body);
687
688  first.release();
689  third.release();
690  body.release();
691  return Owned(new (Context) ForStmt(First, Second, Third, Body, ForLoc,
692                                     LParenLoc, RParenLoc));
693}
694
695Action::OwningStmtResult
696Sema::ActOnObjCForCollectionStmt(SourceLocation ForLoc,
697                                 SourceLocation LParenLoc,
698                                 StmtArg first, ExprArg second,
699                                 SourceLocation RParenLoc, StmtArg body) {
700  Stmt *First  = static_cast<Stmt*>(first.get());
701  Expr *Second = static_cast<Expr*>(second.get());
702  Stmt *Body  = static_cast<Stmt*>(body.get());
703  if (First) {
704    QualType FirstType;
705    if (DeclStmt *DS = dyn_cast<DeclStmt>(First)) {
706      if (!DS->isSingleDecl())
707        return StmtError(Diag((*DS->decl_begin())->getLocation(),
708                         diag::err_toomany_element_decls));
709
710      Decl *D = DS->getSingleDecl();
711      FirstType = cast<ValueDecl>(D)->getType();
712      // C99 6.8.5p3: The declaration part of a 'for' statement shall only
713      // declare identifiers for objects having storage class 'auto' or
714      // 'register'.
715      VarDecl *VD = cast<VarDecl>(D);
716      if (VD->isBlockVarDecl() && !VD->hasLocalStorage())
717        return StmtError(Diag(VD->getLocation(),
718                              diag::err_non_variable_decl_in_for));
719    } else {
720      if (cast<Expr>(First)->isLvalue(Context) != Expr::LV_Valid)
721        return StmtError(Diag(First->getLocStart(),
722                   diag::err_selector_element_not_lvalue)
723          << First->getSourceRange());
724
725      FirstType = static_cast<Expr*>(First)->getType();
726    }
727    if (!FirstType->isObjCObjectPointerType() &&
728        !FirstType->isBlockPointerType())
729        Diag(ForLoc, diag::err_selector_element_type)
730          << FirstType << First->getSourceRange();
731  }
732  if (Second) {
733    DefaultFunctionArrayConversion(Second);
734    QualType SecondType = Second->getType();
735    if (!SecondType->isObjCObjectPointerType())
736      Diag(ForLoc, diag::err_collection_expr_type)
737        << SecondType << Second->getSourceRange();
738  }
739  first.release();
740  second.release();
741  body.release();
742  return Owned(new (Context) ObjCForCollectionStmt(First, Second, Body,
743                                                   ForLoc, RParenLoc));
744}
745
746Action::OwningStmtResult
747Sema::ActOnGotoStmt(SourceLocation GotoLoc, SourceLocation LabelLoc,
748                    IdentifierInfo *LabelII) {
749  // If we are in a block, reject all gotos for now.
750  if (CurBlock)
751    return StmtError(Diag(GotoLoc, diag::err_goto_in_block));
752
753  // Look up the record for this label identifier.
754  LabelStmt *&LabelDecl = getLabelMap()[LabelII];
755
756  // If we haven't seen this label yet, create a forward reference.
757  if (LabelDecl == 0)
758    LabelDecl = new (Context) LabelStmt(LabelLoc, LabelII, 0);
759
760  return Owned(new (Context) GotoStmt(LabelDecl, GotoLoc, LabelLoc));
761}
762
763Action::OwningStmtResult
764Sema::ActOnIndirectGotoStmt(SourceLocation GotoLoc, SourceLocation StarLoc,
765                            ExprArg DestExp) {
766  // Convert operand to void*
767  Expr* E = DestExp.takeAs<Expr>();
768  if (!E->isTypeDependent()) {
769    QualType ETy = E->getType();
770    AssignConvertType ConvTy =
771      CheckSingleAssignmentConstraints(Context.VoidPtrTy, E);
772    if (DiagnoseAssignmentResult(ConvTy, StarLoc, Context.VoidPtrTy, ETy,
773                                 E, "passing"))
774      return StmtError();
775  }
776  return Owned(new (Context) IndirectGotoStmt(GotoLoc, StarLoc, E));
777}
778
779Action::OwningStmtResult
780Sema::ActOnContinueStmt(SourceLocation ContinueLoc, Scope *CurScope) {
781  Scope *S = CurScope->getContinueParent();
782  if (!S) {
783    // C99 6.8.6.2p1: A break shall appear only in or as a loop body.
784    return StmtError(Diag(ContinueLoc, diag::err_continue_not_in_loop));
785  }
786
787  return Owned(new (Context) ContinueStmt(ContinueLoc));
788}
789
790Action::OwningStmtResult
791Sema::ActOnBreakStmt(SourceLocation BreakLoc, Scope *CurScope) {
792  Scope *S = CurScope->getBreakParent();
793  if (!S) {
794    // C99 6.8.6.3p1: A break shall appear only in or as a switch/loop body.
795    return StmtError(Diag(BreakLoc, diag::err_break_not_in_loop_or_switch));
796  }
797
798  return Owned(new (Context) BreakStmt(BreakLoc));
799}
800
801/// ActOnBlockReturnStmt - Utility routine to figure out block's return type.
802///
803Action::OwningStmtResult
804Sema::ActOnBlockReturnStmt(SourceLocation ReturnLoc, Expr *RetValExp) {
805  // If this is the first return we've seen in the block, infer the type of
806  // the block from it.
807  if (CurBlock->ReturnType.isNull()) {
808    if (RetValExp) {
809      // Don't call UsualUnaryConversions(), since we don't want to do
810      // integer promotions here.
811      DefaultFunctionArrayConversion(RetValExp);
812      CurBlock->ReturnType = RetValExp->getType();
813      if (BlockDeclRefExpr *CDRE = dyn_cast<BlockDeclRefExpr>(RetValExp)) {
814        // We have to remove a 'const' added to copied-in variable which was
815        // part of the implementation spec. and not the actual qualifier for
816        // the variable.
817        if (CDRE->isConstQualAdded())
818           CurBlock->ReturnType.removeConst();
819      }
820    } else
821      CurBlock->ReturnType = Context.VoidTy;
822  }
823  QualType FnRetType = CurBlock->ReturnType;
824
825  if (CurBlock->TheDecl->hasAttr<NoReturnAttr>()) {
826    Diag(ReturnLoc, diag::err_noreturn_block_has_return_expr)
827      << getCurFunctionOrMethodDecl()->getDeclName();
828    return StmtError();
829  }
830
831  // Otherwise, verify that this result type matches the previous one.  We are
832  // pickier with blocks than for normal functions because we don't have GCC
833  // compatibility to worry about here.
834  if (CurBlock->ReturnType->isVoidType()) {
835    if (RetValExp) {
836      Diag(ReturnLoc, diag::err_return_block_has_expr);
837      RetValExp->Destroy(Context);
838      RetValExp = 0;
839    }
840    return Owned(new (Context) ReturnStmt(ReturnLoc, RetValExp));
841  }
842
843  if (!RetValExp)
844    return StmtError(Diag(ReturnLoc, diag::err_block_return_missing_expr));
845
846  if (!FnRetType->isDependentType() && !RetValExp->isTypeDependent()) {
847    // we have a non-void block with an expression, continue checking
848    QualType RetValType = RetValExp->getType();
849
850    // C99 6.8.6.4p3(136): The return statement is not an assignment. The
851    // overlap restriction of subclause 6.5.16.1 does not apply to the case of
852    // function return.
853
854    // In C++ the return statement is handled via a copy initialization.
855    // the C version of which boils down to CheckSingleAssignmentConstraints.
856    // FIXME: Leaks RetValExp.
857    if (PerformCopyInitialization(RetValExp, FnRetType, "returning"))
858      return StmtError();
859
860    if (RetValExp) CheckReturnStackAddr(RetValExp, FnRetType, ReturnLoc);
861  }
862
863  return Owned(new (Context) ReturnStmt(ReturnLoc, RetValExp));
864}
865
866/// IsReturnCopyElidable - Whether returning @p RetExpr from a function that
867/// returns a @p RetType fulfills the criteria for copy elision (C++0x 12.8p15).
868static bool IsReturnCopyElidable(ASTContext &Ctx, QualType RetType,
869                                 Expr *RetExpr) {
870  QualType ExprType = RetExpr->getType();
871  // - in a return statement in a function with ...
872  // ... a class return type ...
873  if (!RetType->isRecordType())
874    return false;
875  // ... the same cv-unqualified type as the function return type ...
876  if (Ctx.getCanonicalType(RetType).getUnqualifiedType() !=
877      Ctx.getCanonicalType(ExprType).getUnqualifiedType())
878    return false;
879  // ... the expression is the name of a non-volatile automatic object ...
880  // We ignore parentheses here.
881  // FIXME: Is this compliant?
882  const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(RetExpr->IgnoreParens());
883  if (!DR)
884    return false;
885  const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl());
886  if (!VD)
887    return false;
888  return VD->hasLocalStorage() && !VD->getType()->isReferenceType()
889    && !VD->getType().isVolatileQualified();
890}
891
892Action::OwningStmtResult
893Sema::ActOnReturnStmt(SourceLocation ReturnLoc, ExprArg rex) {
894  Expr *RetValExp = rex.takeAs<Expr>();
895  if (CurBlock)
896    return ActOnBlockReturnStmt(ReturnLoc, RetValExp);
897
898  QualType FnRetType;
899  if (const FunctionDecl *FD = getCurFunctionDecl()) {
900    FnRetType = FD->getResultType();
901    if (FD->hasAttr<NoReturnAttr>())
902      Diag(ReturnLoc, diag::warn_noreturn_function_has_return_expr)
903        << getCurFunctionOrMethodDecl()->getDeclName();
904  } else if (ObjCMethodDecl *MD = getCurMethodDecl())
905    FnRetType = MD->getResultType();
906  else // If we don't have a function/method context, bail.
907    return StmtError();
908
909  if (FnRetType->isVoidType()) {
910    if (RetValExp && !RetValExp->isTypeDependent()) {
911      // C99 6.8.6.4p1 (ext_ since GCC warns)
912      unsigned D = diag::ext_return_has_expr;
913      if (RetValExp->getType()->isVoidType())
914        D = diag::ext_return_has_void_expr;
915
916      // return (some void expression); is legal in C++.
917      if (D != diag::ext_return_has_void_expr ||
918          !getLangOptions().CPlusPlus) {
919        NamedDecl *CurDecl = getCurFunctionOrMethodDecl();
920        Diag(ReturnLoc, D)
921          << CurDecl->getDeclName() << isa<ObjCMethodDecl>(CurDecl)
922          << RetValExp->getSourceRange();
923      }
924
925      RetValExp = MaybeCreateCXXExprWithTemporaries(RetValExp, true);
926    }
927    return Owned(new (Context) ReturnStmt(ReturnLoc, RetValExp));
928  }
929
930  if (!RetValExp && !FnRetType->isDependentType()) {
931    unsigned DiagID = diag::warn_return_missing_expr;  // C90 6.6.6.4p4
932    // C99 6.8.6.4p1 (ext_ since GCC warns)
933    if (getLangOptions().C99) DiagID = diag::ext_return_missing_expr;
934
935    if (FunctionDecl *FD = getCurFunctionDecl())
936      Diag(ReturnLoc, DiagID) << FD->getIdentifier() << 0/*fn*/;
937    else
938      Diag(ReturnLoc, DiagID) << getCurMethodDecl()->getDeclName() << 1/*meth*/;
939    return Owned(new (Context) ReturnStmt(ReturnLoc, (Expr*)0));
940  }
941
942  if (!FnRetType->isDependentType() && !RetValExp->isTypeDependent()) {
943    // we have a non-void function with an expression, continue checking
944
945    // C99 6.8.6.4p3(136): The return statement is not an assignment. The
946    // overlap restriction of subclause 6.5.16.1 does not apply to the case of
947    // function return.
948
949    // C++0x 12.8p15: When certain criteria are met, an implementation is
950    //   allowed to omit the copy construction of a class object, [...]
951    //   - in a return statement in a function with a class return type, when
952    //     the expression is the name of a non-volatile automatic object with
953    //     the same cv-unqualified type as the function return type, the copy
954    //     operation can be omitted [...]
955    // C++0x 12.8p16: When the criteria for elision of a copy operation are met
956    //   and the object to be copied is designated by an lvalue, overload
957    //   resolution to select the constructor for the copy is first performed
958    //   as if the object were designated by an rvalue.
959    // Note that we only compute Elidable if we're in C++0x, since we don't
960    // care otherwise.
961    bool Elidable = getLangOptions().CPlusPlus0x ?
962                      IsReturnCopyElidable(Context, FnRetType, RetValExp) :
963                      false;
964
965    // In C++ the return statement is handled via a copy initialization.
966    // the C version of which boils down to CheckSingleAssignmentConstraints.
967    // FIXME: Leaks RetValExp on error.
968    if (PerformCopyInitialization(RetValExp, FnRetType, "returning", Elidable))
969      return StmtError();
970
971    if (RetValExp) CheckReturnStackAddr(RetValExp, FnRetType, ReturnLoc);
972  }
973
974  if (RetValExp)
975    RetValExp = MaybeCreateCXXExprWithTemporaries(RetValExp, true);
976  return Owned(new (Context) ReturnStmt(ReturnLoc, RetValExp));
977}
978
979/// CheckAsmLValue - GNU C has an extremely ugly extension whereby they silently
980/// ignore "noop" casts in places where an lvalue is required by an inline asm.
981/// We emulate this behavior when -fheinous-gnu-extensions is specified, but
982/// provide a strong guidance to not use it.
983///
984/// This method checks to see if the argument is an acceptable l-value and
985/// returns false if it is a case we can handle.
986static bool CheckAsmLValue(const Expr *E, Sema &S) {
987  if (E->isLvalue(S.Context) == Expr::LV_Valid)
988    return false;  // Cool, this is an lvalue.
989
990  // Okay, this is not an lvalue, but perhaps it is the result of a cast that we
991  // are supposed to allow.
992  const Expr *E2 = E->IgnoreParenNoopCasts(S.Context);
993  if (E != E2 && E2->isLvalue(S.Context) == Expr::LV_Valid) {
994    if (!S.getLangOptions().HeinousExtensions)
995      S.Diag(E2->getLocStart(), diag::err_invalid_asm_cast_lvalue)
996        << E->getSourceRange();
997    else
998      S.Diag(E2->getLocStart(), diag::warn_invalid_asm_cast_lvalue)
999        << E->getSourceRange();
1000    // Accept, even if we emitted an error diagnostic.
1001    return false;
1002  }
1003
1004  // None of the above, just randomly invalid non-lvalue.
1005  return true;
1006}
1007
1008
1009Sema::OwningStmtResult Sema::ActOnAsmStmt(SourceLocation AsmLoc,
1010                                          bool IsSimple,
1011                                          bool IsVolatile,
1012                                          unsigned NumOutputs,
1013                                          unsigned NumInputs,
1014                                          std::string *Names,
1015                                          MultiExprArg constraints,
1016                                          MultiExprArg exprs,
1017                                          ExprArg asmString,
1018                                          MultiExprArg clobbers,
1019                                          SourceLocation RParenLoc) {
1020  unsigned NumClobbers = clobbers.size();
1021  StringLiteral **Constraints =
1022    reinterpret_cast<StringLiteral**>(constraints.get());
1023  Expr **Exprs = reinterpret_cast<Expr **>(exprs.get());
1024  StringLiteral *AsmString = cast<StringLiteral>((Expr *)asmString.get());
1025  StringLiteral **Clobbers = reinterpret_cast<StringLiteral**>(clobbers.get());
1026
1027  llvm::SmallVector<TargetInfo::ConstraintInfo, 4> OutputConstraintInfos;
1028
1029  // The parser verifies that there is a string literal here.
1030  if (AsmString->isWide())
1031    return StmtError(Diag(AsmString->getLocStart(),diag::err_asm_wide_character)
1032      << AsmString->getSourceRange());
1033
1034  for (unsigned i = 0; i != NumOutputs; i++) {
1035    StringLiteral *Literal = Constraints[i];
1036    if (Literal->isWide())
1037      return StmtError(Diag(Literal->getLocStart(),diag::err_asm_wide_character)
1038        << Literal->getSourceRange());
1039
1040    TargetInfo::ConstraintInfo Info(Literal->getStrData(),
1041                                    Literal->getByteLength(),
1042                                    Names[i]);
1043    if (!Context.Target.validateOutputConstraint(Info))
1044      return StmtError(Diag(Literal->getLocStart(),
1045                            diag::err_asm_invalid_output_constraint)
1046                       << Info.getConstraintStr());
1047
1048    // Check that the output exprs are valid lvalues.
1049    Expr *OutputExpr = Exprs[i];
1050    if (CheckAsmLValue(OutputExpr, *this)) {
1051      return StmtError(Diag(OutputExpr->getLocStart(),
1052                  diag::err_asm_invalid_lvalue_in_output)
1053        << OutputExpr->getSourceRange());
1054    }
1055
1056    OutputConstraintInfos.push_back(Info);
1057  }
1058
1059  llvm::SmallVector<TargetInfo::ConstraintInfo, 4> InputConstraintInfos;
1060
1061  for (unsigned i = NumOutputs, e = NumOutputs + NumInputs; i != e; i++) {
1062    StringLiteral *Literal = Constraints[i];
1063    if (Literal->isWide())
1064      return StmtError(Diag(Literal->getLocStart(),diag::err_asm_wide_character)
1065        << Literal->getSourceRange());
1066
1067    TargetInfo::ConstraintInfo Info(Literal->getStrData(),
1068                                    Literal->getByteLength(),
1069                                    Names[i]);
1070    if (!Context.Target.validateInputConstraint(OutputConstraintInfos.data(),
1071                                                NumOutputs, Info)) {
1072      return StmtError(Diag(Literal->getLocStart(),
1073                            diag::err_asm_invalid_input_constraint)
1074                       << Info.getConstraintStr());
1075    }
1076
1077    Expr *InputExpr = Exprs[i];
1078
1079    // Only allow void types for memory constraints.
1080    if (Info.allowsMemory() && !Info.allowsRegister()) {
1081      if (CheckAsmLValue(InputExpr, *this))
1082        return StmtError(Diag(InputExpr->getLocStart(),
1083                              diag::err_asm_invalid_lvalue_in_input)
1084                         << Info.getConstraintStr()
1085                         << InputExpr->getSourceRange());
1086    }
1087
1088    if (Info.allowsRegister()) {
1089      if (InputExpr->getType()->isVoidType()) {
1090        return StmtError(Diag(InputExpr->getLocStart(),
1091                              diag::err_asm_invalid_type_in_input)
1092          << InputExpr->getType() << Info.getConstraintStr()
1093          << InputExpr->getSourceRange());
1094      }
1095    }
1096
1097    DefaultFunctionArrayConversion(Exprs[i]);
1098
1099    InputConstraintInfos.push_back(Info);
1100  }
1101
1102  // Check that the clobbers are valid.
1103  for (unsigned i = 0; i != NumClobbers; i++) {
1104    StringLiteral *Literal = Clobbers[i];
1105    if (Literal->isWide())
1106      return StmtError(Diag(Literal->getLocStart(),diag::err_asm_wide_character)
1107        << Literal->getSourceRange());
1108
1109    std::string Clobber(Literal->getStrData(),
1110                        Literal->getStrData() +
1111                        Literal->getByteLength());
1112
1113    if (!Context.Target.isValidGCCRegisterName(Clobber.c_str()))
1114      return StmtError(Diag(Literal->getLocStart(),
1115                  diag::err_asm_unknown_register_name) << Clobber);
1116  }
1117
1118  constraints.release();
1119  exprs.release();
1120  asmString.release();
1121  clobbers.release();
1122  AsmStmt *NS =
1123    new (Context) AsmStmt(AsmLoc, IsSimple, IsVolatile, NumOutputs, NumInputs,
1124                          Names, Constraints, Exprs, AsmString, NumClobbers,
1125                          Clobbers, RParenLoc);
1126  // Validate the asm string, ensuring it makes sense given the operands we
1127  // have.
1128  llvm::SmallVector<AsmStmt::AsmStringPiece, 8> Pieces;
1129  unsigned DiagOffs;
1130  if (unsigned DiagID = NS->AnalyzeAsmString(Pieces, Context, DiagOffs)) {
1131    Diag(getLocationOfStringLiteralByte(AsmString, DiagOffs), DiagID)
1132           << AsmString->getSourceRange();
1133    DeleteStmt(NS);
1134    return StmtError();
1135  }
1136
1137  // Validate tied input operands for type mismatches.
1138  for (unsigned i = 0, e = InputConstraintInfos.size(); i != e; ++i) {
1139    TargetInfo::ConstraintInfo &Info = InputConstraintInfos[i];
1140
1141    // If this is a tied constraint, verify that the output and input have
1142    // either exactly the same type, or that they are int/ptr operands with the
1143    // same size (int/long, int*/long, are ok etc).
1144    if (!Info.hasTiedOperand()) continue;
1145
1146    unsigned TiedTo = Info.getTiedOperand();
1147    Expr *OutputExpr = Exprs[TiedTo];
1148    Expr *InputExpr = Exprs[i+NumOutputs];
1149    QualType InTy = InputExpr->getType();
1150    QualType OutTy = OutputExpr->getType();
1151    if (Context.hasSameType(InTy, OutTy))
1152      continue;  // All types can be tied to themselves.
1153
1154    // Int/ptr operands have some special cases that we allow.
1155    if ((OutTy->isIntegerType() || OutTy->isPointerType()) &&
1156        (InTy->isIntegerType() || InTy->isPointerType())) {
1157
1158      // They are ok if they are the same size.  Tying void* to int is ok if
1159      // they are the same size, for example.  This also allows tying void* to
1160      // int*.
1161      uint64_t OutSize = Context.getTypeSize(OutTy);
1162      uint64_t InSize = Context.getTypeSize(InTy);
1163      if (OutSize == InSize)
1164        continue;
1165
1166      // If the smaller input/output operand is not mentioned in the asm string,
1167      // then we can promote it and the asm string won't notice.  Check this
1168      // case now.
1169      bool SmallerValueMentioned = false;
1170      for (unsigned p = 0, e = Pieces.size(); p != e; ++p) {
1171        AsmStmt::AsmStringPiece &Piece = Pieces[p];
1172        if (!Piece.isOperand()) continue;
1173
1174        // If this is a reference to the input and if the input was the smaller
1175        // one, then we have to reject this asm.
1176        if (Piece.getOperandNo() == i+NumOutputs) {
1177          if (InSize < OutSize) {
1178            SmallerValueMentioned = true;
1179            break;
1180          }
1181        }
1182
1183        // If this is a reference to the input and if the input was the smaller
1184        // one, then we have to reject this asm.
1185        if (Piece.getOperandNo() == TiedTo) {
1186          if (InSize > OutSize) {
1187            SmallerValueMentioned = true;
1188            break;
1189          }
1190        }
1191      }
1192
1193      // If the smaller value wasn't mentioned in the asm string, and if the
1194      // output was a register, just extend the shorter one to the size of the
1195      // larger one.
1196      if (!SmallerValueMentioned &&
1197          OutputConstraintInfos[TiedTo].allowsRegister())
1198        continue;
1199    }
1200
1201    Diag(InputExpr->getLocStart(),
1202         diag::err_asm_tying_incompatible_types)
1203      << InTy << OutTy << OutputExpr->getSourceRange()
1204      << InputExpr->getSourceRange();
1205    DeleteStmt(NS);
1206    return StmtError();
1207  }
1208
1209  return Owned(NS);
1210}
1211
1212Action::OwningStmtResult
1213Sema::ActOnObjCAtCatchStmt(SourceLocation AtLoc,
1214                           SourceLocation RParen, DeclPtrTy Parm,
1215                           StmtArg Body, StmtArg catchList) {
1216  Stmt *CatchList = catchList.takeAs<Stmt>();
1217  ParmVarDecl *PVD = cast_or_null<ParmVarDecl>(Parm.getAs<Decl>());
1218
1219  // PVD == 0 implies @catch(...).
1220  if (PVD) {
1221    // If we already know the decl is invalid, reject it.
1222    if (PVD->isInvalidDecl())
1223      return StmtError();
1224
1225    if (!PVD->getType()->isObjCObjectPointerType())
1226      return StmtError(Diag(PVD->getLocation(),
1227                       diag::err_catch_param_not_objc_type));
1228    if (PVD->getType()->isObjCQualifiedIdType())
1229      return StmtError(Diag(PVD->getLocation(),
1230                       diag::err_illegal_qualifiers_on_catch_parm));
1231  }
1232
1233  ObjCAtCatchStmt *CS = new (Context) ObjCAtCatchStmt(AtLoc, RParen,
1234    PVD, Body.takeAs<Stmt>(), CatchList);
1235  return Owned(CatchList ? CatchList : CS);
1236}
1237
1238Action::OwningStmtResult
1239Sema::ActOnObjCAtFinallyStmt(SourceLocation AtLoc, StmtArg Body) {
1240  return Owned(new (Context) ObjCAtFinallyStmt(AtLoc,
1241                                           static_cast<Stmt*>(Body.release())));
1242}
1243
1244Action::OwningStmtResult
1245Sema::ActOnObjCAtTryStmt(SourceLocation AtLoc,
1246                         StmtArg Try, StmtArg Catch, StmtArg Finally) {
1247  CurFunctionNeedsScopeChecking = true;
1248  return Owned(new (Context) ObjCAtTryStmt(AtLoc, Try.takeAs<Stmt>(),
1249                                           Catch.takeAs<Stmt>(),
1250                                           Finally.takeAs<Stmt>()));
1251}
1252
1253Action::OwningStmtResult
1254Sema::ActOnObjCAtThrowStmt(SourceLocation AtLoc, ExprArg expr,Scope *CurScope) {
1255  Expr *ThrowExpr = expr.takeAs<Expr>();
1256  if (!ThrowExpr) {
1257    // @throw without an expression designates a rethrow (which much occur
1258    // in the context of an @catch clause).
1259    Scope *AtCatchParent = CurScope;
1260    while (AtCatchParent && !AtCatchParent->isAtCatchScope())
1261      AtCatchParent = AtCatchParent->getParent();
1262    if (!AtCatchParent)
1263      return StmtError(Diag(AtLoc, diag::error_rethrow_used_outside_catch));
1264  } else {
1265    QualType ThrowType = ThrowExpr->getType();
1266    // Make sure the expression type is an ObjC pointer or "void *".
1267    if (!ThrowType->isObjCObjectPointerType()) {
1268      const PointerType *PT = ThrowType->getAs<PointerType>();
1269      if (!PT || !PT->getPointeeType()->isVoidType())
1270        return StmtError(Diag(AtLoc, diag::error_objc_throw_expects_object)
1271                        << ThrowExpr->getType() << ThrowExpr->getSourceRange());
1272    }
1273  }
1274  return Owned(new (Context) ObjCAtThrowStmt(AtLoc, ThrowExpr));
1275}
1276
1277Action::OwningStmtResult
1278Sema::ActOnObjCAtSynchronizedStmt(SourceLocation AtLoc, ExprArg SynchExpr,
1279                                  StmtArg SynchBody) {
1280  CurFunctionNeedsScopeChecking = true;
1281
1282  // Make sure the expression type is an ObjC pointer or "void *".
1283  Expr *SyncExpr = static_cast<Expr*>(SynchExpr.get());
1284  if (!SyncExpr->getType()->isObjCObjectPointerType()) {
1285    const PointerType *PT = SyncExpr->getType()->getAs<PointerType>();
1286    if (!PT || !PT->getPointeeType()->isVoidType())
1287      return StmtError(Diag(AtLoc, diag::error_objc_synchronized_expects_object)
1288                       << SyncExpr->getType() << SyncExpr->getSourceRange());
1289  }
1290
1291  return Owned(new (Context) ObjCAtSynchronizedStmt(AtLoc,
1292                                                    SynchExpr.takeAs<Stmt>(),
1293                                                    SynchBody.takeAs<Stmt>()));
1294}
1295
1296/// ActOnCXXCatchBlock - Takes an exception declaration and a handler block
1297/// and creates a proper catch handler from them.
1298Action::OwningStmtResult
1299Sema::ActOnCXXCatchBlock(SourceLocation CatchLoc, DeclPtrTy ExDecl,
1300                         StmtArg HandlerBlock) {
1301  // There's nothing to test that ActOnExceptionDecl didn't already test.
1302  return Owned(new (Context) CXXCatchStmt(CatchLoc,
1303                                  cast_or_null<VarDecl>(ExDecl.getAs<Decl>()),
1304                                          HandlerBlock.takeAs<Stmt>()));
1305}
1306
1307class TypeWithHandler {
1308  QualType t;
1309  CXXCatchStmt *stmt;
1310public:
1311  TypeWithHandler(const QualType &type, CXXCatchStmt *statement)
1312  : t(type), stmt(statement) {}
1313
1314  // An arbitrary order is fine as long as it places identical
1315  // types next to each other.
1316  bool operator<(const TypeWithHandler &y) const {
1317    if (t.getAsOpaquePtr() < y.t.getAsOpaquePtr())
1318      return true;
1319    if (t.getAsOpaquePtr() > y.t.getAsOpaquePtr())
1320      return false;
1321    else
1322      return getTypeSpecStartLoc() < y.getTypeSpecStartLoc();
1323  }
1324
1325  bool operator==(const TypeWithHandler& other) const {
1326    return t == other.t;
1327  }
1328
1329  QualType getQualType() const { return t; }
1330  CXXCatchStmt *getCatchStmt() const { return stmt; }
1331  SourceLocation getTypeSpecStartLoc() const {
1332    return stmt->getExceptionDecl()->getTypeSpecStartLoc();
1333  }
1334};
1335
1336/// ActOnCXXTryBlock - Takes a try compound-statement and a number of
1337/// handlers and creates a try statement from them.
1338Action::OwningStmtResult
1339Sema::ActOnCXXTryBlock(SourceLocation TryLoc, StmtArg TryBlock,
1340                       MultiStmtArg RawHandlers) {
1341  unsigned NumHandlers = RawHandlers.size();
1342  assert(NumHandlers > 0 &&
1343         "The parser shouldn't call this if there are no handlers.");
1344  Stmt **Handlers = reinterpret_cast<Stmt**>(RawHandlers.get());
1345
1346  llvm::SmallVector<TypeWithHandler, 8> TypesWithHandlers;
1347
1348  for (unsigned i = 0; i < NumHandlers; ++i) {
1349    CXXCatchStmt *Handler = llvm::cast<CXXCatchStmt>(Handlers[i]);
1350    if (!Handler->getExceptionDecl()) {
1351      if (i < NumHandlers - 1)
1352        return StmtError(Diag(Handler->getLocStart(),
1353                              diag::err_early_catch_all));
1354
1355      continue;
1356    }
1357
1358    const QualType CaughtType = Handler->getCaughtType();
1359    const QualType CanonicalCaughtType = Context.getCanonicalType(CaughtType);
1360    TypesWithHandlers.push_back(TypeWithHandler(CanonicalCaughtType, Handler));
1361  }
1362
1363  // Detect handlers for the same type as an earlier one.
1364  if (NumHandlers > 1) {
1365    llvm::array_pod_sort(TypesWithHandlers.begin(), TypesWithHandlers.end());
1366
1367    TypeWithHandler prev = TypesWithHandlers[0];
1368    for (unsigned i = 1; i < TypesWithHandlers.size(); ++i) {
1369      TypeWithHandler curr = TypesWithHandlers[i];
1370
1371      if (curr == prev) {
1372        Diag(curr.getTypeSpecStartLoc(),
1373             diag::warn_exception_caught_by_earlier_handler)
1374          << curr.getCatchStmt()->getCaughtType().getAsString();
1375        Diag(prev.getTypeSpecStartLoc(),
1376             diag::note_previous_exception_handler)
1377          << prev.getCatchStmt()->getCaughtType().getAsString();
1378      }
1379
1380      prev = curr;
1381    }
1382  }
1383
1384  // FIXME: We should detect handlers that cannot catch anything because an
1385  // earlier handler catches a superclass. Need to find a method that is not
1386  // quadratic for this.
1387  // Neither of these are explicitly forbidden, but every compiler detects them
1388  // and warns.
1389
1390  CurFunctionNeedsScopeChecking = true;
1391  RawHandlers.release();
1392  return Owned(new (Context) CXXTryStmt(TryLoc,
1393                                        static_cast<Stmt*>(TryBlock.release()),
1394                                        Handlers, NumHandlers));
1395}
1396