SemaStmt.cpp revision 6b1d283fe879fb11d7ce7a69feecf66e77b0eaf3
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/Expr.h"
19#include "clang/AST/StmtObjC.h"
20#include "clang/AST/StmtCXX.h"
21#include "clang/Basic/TargetInfo.h"
22using namespace clang;
23
24Sema::OwningStmtResult Sema::ActOnExprStmt(FullExprArg expr) {
25  Expr *E = expr->takeAs<Expr>();
26  assert(E && "ActOnExprStmt(): missing expression");
27
28  // C99 6.8.3p2: The expression in an expression statement is evaluated as a
29  // void expression for its side effects.  Conversion to void allows any
30  // operand, even incomplete types.
31
32  // Same thing in for stmt first clause (when expr) and third clause.
33  return Owned(static_cast<Stmt*>(E));
34}
35
36
37Sema::OwningStmtResult Sema::ActOnNullStmt(SourceLocation SemiLoc) {
38  return Owned(new (Context) NullStmt(SemiLoc));
39}
40
41Sema::OwningStmtResult Sema::ActOnDeclStmt(DeclGroupPtrTy dg,
42                                           SourceLocation StartLoc,
43                                           SourceLocation EndLoc) {
44  DeclGroupRef DG = dg.getAsVal<DeclGroupRef>();
45
46  // If we have an invalid decl, just return an error.
47  if (DG.isNull()) return StmtError();
48
49  return Owned(new (Context) DeclStmt(DG, StartLoc, EndLoc));
50}
51
52Action::OwningStmtResult
53Sema::ActOnCompoundStmt(SourceLocation L, SourceLocation R,
54                        MultiStmtArg elts, bool isStmtExpr) {
55  unsigned NumElts = elts.size();
56  Stmt **Elts = reinterpret_cast<Stmt**>(elts.release());
57  // If we're in C89 mode, check that we don't have any decls after stmts.  If
58  // so, emit an extension diagnostic.
59  if (!getLangOptions().C99 && !getLangOptions().CPlusPlus) {
60    // Note that __extension__ can be around a decl.
61    unsigned i = 0;
62    // Skip over all declarations.
63    for (; i != NumElts && isa<DeclStmt>(Elts[i]); ++i)
64      /*empty*/;
65
66    // We found the end of the list or a statement.  Scan for another declstmt.
67    for (; i != NumElts && !isa<DeclStmt>(Elts[i]); ++i)
68      /*empty*/;
69
70    if (i != NumElts) {
71      Decl *D = *cast<DeclStmt>(Elts[i])->decl_begin();
72      Diag(D->getLocation(), diag::ext_mixed_decls_code);
73    }
74  }
75  // Warn about unused expressions in statements.
76  for (unsigned i = 0; i != NumElts; ++i) {
77    Expr *E = dyn_cast<Expr>(Elts[i]);
78    if (!E) continue;
79
80    // Warn about expressions with unused results if they are non-void and if
81    // this not the last stmt in a stmt expr.
82    if (E->getType()->isVoidType() || (isStmtExpr && i == NumElts-1))
83      continue;
84
85    SourceLocation Loc;
86    SourceRange R1, R2;
87    if (!E->isUnusedResultAWarning(Loc, R1, R2))
88      continue;
89
90    Diag(Loc, diag::warn_unused_expr) << R1 << R2;
91  }
92
93  return Owned(new (Context) CompoundStmt(Context, Elts, NumElts, L, R));
94}
95
96Action::OwningStmtResult
97Sema::ActOnCaseStmt(SourceLocation CaseLoc, ExprArg lhsval,
98                    SourceLocation DotDotDotLoc, ExprArg rhsval,
99                    SourceLocation ColonLoc) {
100  assert((lhsval.get() != 0) && "missing expression in case statement");
101
102  // C99 6.8.4.2p3: The expression shall be an integer constant.
103  // However, GCC allows any evaluatable integer expression.
104  Expr *LHSVal = static_cast<Expr*>(lhsval.get());
105  if (!LHSVal->isTypeDependent() && !LHSVal->isValueDependent() &&
106      VerifyIntegerConstantExpression(LHSVal))
107    return StmtError();
108
109  // GCC extension: The expression shall be an integer constant.
110
111  Expr *RHSVal = static_cast<Expr*>(rhsval.get());
112  if (RHSVal && !RHSVal->isTypeDependent() && !RHSVal->isValueDependent() &&
113      VerifyIntegerConstantExpression(RHSVal)) {
114    RHSVal = 0;  // Recover by just forgetting about it.
115    rhsval = 0;
116  }
117
118  if (getSwitchStack().empty()) {
119    Diag(CaseLoc, diag::err_case_not_in_switch);
120    return StmtError();
121  }
122
123  // Only now release the smart pointers.
124  lhsval.release();
125  rhsval.release();
126  CaseStmt *CS = new (Context) CaseStmt(LHSVal, RHSVal, CaseLoc, DotDotDotLoc,
127                                        ColonLoc);
128  getSwitchStack().back()->addSwitchCase(CS);
129  return Owned(CS);
130}
131
132/// ActOnCaseStmtBody - This installs a statement as the body of a case.
133void Sema::ActOnCaseStmtBody(StmtTy *caseStmt, StmtArg subStmt) {
134  CaseStmt *CS = static_cast<CaseStmt*>(caseStmt);
135  Stmt *SubStmt = subStmt.takeAs<Stmt>();
136  CS->setSubStmt(SubStmt);
137}
138
139Action::OwningStmtResult
140Sema::ActOnDefaultStmt(SourceLocation DefaultLoc, SourceLocation ColonLoc,
141                       StmtArg subStmt, Scope *CurScope) {
142  Stmt *SubStmt = subStmt.takeAs<Stmt>();
143
144  if (getSwitchStack().empty()) {
145    Diag(DefaultLoc, diag::err_default_not_in_switch);
146    return Owned(SubStmt);
147  }
148
149  DefaultStmt *DS = new (Context) DefaultStmt(DefaultLoc, ColonLoc, SubStmt);
150  getSwitchStack().back()->addSwitchCase(DS);
151  return Owned(DS);
152}
153
154Action::OwningStmtResult
155Sema::ActOnLabelStmt(SourceLocation IdentLoc, IdentifierInfo *II,
156                     SourceLocation ColonLoc, StmtArg subStmt) {
157  Stmt *SubStmt = subStmt.takeAs<Stmt>();
158  // Look up the record for this label identifier.
159  LabelStmt *&LabelDecl = getLabelMap()[II];
160
161  // If not forward referenced or defined already, just create a new LabelStmt.
162  if (LabelDecl == 0)
163    return Owned(LabelDecl = new (Context) LabelStmt(IdentLoc, II, SubStmt));
164
165  assert(LabelDecl->getID() == II && "Label mismatch!");
166
167  // Otherwise, this label was either forward reference or multiply defined.  If
168  // multiply defined, reject it now.
169  if (LabelDecl->getSubStmt()) {
170    Diag(IdentLoc, diag::err_redefinition_of_label) << LabelDecl->getID();
171    Diag(LabelDecl->getIdentLoc(), diag::note_previous_definition);
172    return Owned(SubStmt);
173  }
174
175  // Otherwise, this label was forward declared, and we just found its real
176  // definition.  Fill in the forward definition and return it.
177  LabelDecl->setIdentLoc(IdentLoc);
178  LabelDecl->setSubStmt(SubStmt);
179  return Owned(LabelDecl);
180}
181
182Action::OwningStmtResult
183Sema::ActOnIfStmt(SourceLocation IfLoc, FullExprArg CondVal,
184                  StmtArg ThenVal, SourceLocation ElseLoc,
185                  StmtArg ElseVal) {
186  OwningExprResult CondResult(CondVal.release());
187
188  Expr *condExpr = CondResult.takeAs<Expr>();
189
190  assert(condExpr && "ActOnIfStmt(): missing expression");
191
192  if (!condExpr->isTypeDependent()) {
193    DefaultFunctionArrayConversion(condExpr);
194    // Take ownership again until we're past the error checking.
195    CondResult = condExpr;
196    QualType condType = condExpr->getType();
197
198    if (getLangOptions().CPlusPlus) {
199      if (CheckCXXBooleanCondition(condExpr)) // C++ 6.4p4
200        return StmtError();
201    } else if (!condType->isScalarType()) // C99 6.8.4.1p1
202      return StmtError(Diag(IfLoc,
203                            diag::err_typecheck_statement_requires_scalar)
204                       << condType << condExpr->getSourceRange());
205  }
206
207  Stmt *thenStmt = ThenVal.takeAs<Stmt>();
208
209  // Warn if the if block has a null body without an else value.
210  // this helps prevent bugs due to typos, such as
211  // if (condition);
212  //   do_stuff();
213  if (!ElseVal.get()) {
214    if (NullStmt* stmt = dyn_cast<NullStmt>(thenStmt))
215      Diag(stmt->getSemiLoc(), diag::warn_empty_if_body);
216  }
217
218  CondResult.release();
219  return Owned(new (Context) IfStmt(IfLoc, condExpr, thenStmt,
220                                    ElseLoc, ElseVal.takeAs<Stmt>()));
221}
222
223Action::OwningStmtResult
224Sema::ActOnStartOfSwitchStmt(ExprArg cond) {
225  Expr *Cond = cond.takeAs<Expr>();
226
227  if (getLangOptions().CPlusPlus) {
228    // C++ 6.4.2.p2:
229    // The condition shall be of integral type, enumeration type, or of a class
230    // type for which a single conversion function to integral or enumeration
231    // type exists (12.3). If the condition is of class type, the condition is
232    // converted by calling that conversion function, and the result of the
233    // conversion is used in place of the original condition for the remainder
234    // of this section. Integral promotions are performed.
235    if (!Cond->isTypeDependent()) {
236      QualType Ty = Cond->getType();
237
238      // FIXME: Handle class types.
239
240      // If the type is wrong a diagnostic will be emitted later at
241      // ActOnFinishSwitchStmt.
242      if (Ty->isIntegralType() || Ty->isEnumeralType()) {
243        // Integral promotions are performed.
244        // FIXME: Integral promotions for C++ are not complete.
245        UsualUnaryConversions(Cond);
246      }
247    }
248  } else {
249    // C99 6.8.4.2p5 - Integer promotions are performed on the controlling expr.
250    UsualUnaryConversions(Cond);
251  }
252
253  SwitchStmt *SS = new (Context) SwitchStmt(Cond);
254  getSwitchStack().push_back(SS);
255  return Owned(SS);
256}
257
258/// ConvertIntegerToTypeWarnOnOverflow - Convert the specified APInt to have
259/// the specified width and sign.  If an overflow occurs, detect it and emit
260/// the specified diagnostic.
261void Sema::ConvertIntegerToTypeWarnOnOverflow(llvm::APSInt &Val,
262                                              unsigned NewWidth, bool NewSign,
263                                              SourceLocation Loc,
264                                              unsigned DiagID) {
265  // Perform a conversion to the promoted condition type if needed.
266  if (NewWidth > Val.getBitWidth()) {
267    // If this is an extension, just do it.
268    llvm::APSInt OldVal(Val);
269    Val.extend(NewWidth);
270
271    // If the input was signed and negative and the output is unsigned,
272    // warn.
273    if (!NewSign && OldVal.isSigned() && OldVal.isNegative())
274      Diag(Loc, DiagID) << OldVal.toString(10) << Val.toString(10);
275
276    Val.setIsSigned(NewSign);
277  } else if (NewWidth < Val.getBitWidth()) {
278    // If this is a truncation, check for overflow.
279    llvm::APSInt ConvVal(Val);
280    ConvVal.trunc(NewWidth);
281    ConvVal.setIsSigned(NewSign);
282    ConvVal.extend(Val.getBitWidth());
283    ConvVal.setIsSigned(Val.isSigned());
284    if (ConvVal != Val)
285      Diag(Loc, DiagID) << Val.toString(10) << ConvVal.toString(10);
286
287    // Regardless of whether a diagnostic was emitted, really do the
288    // truncation.
289    Val.trunc(NewWidth);
290    Val.setIsSigned(NewSign);
291  } else if (NewSign != Val.isSigned()) {
292    // Convert the sign to match the sign of the condition.  This can cause
293    // overflow as well: unsigned(INTMIN)
294    llvm::APSInt OldVal(Val);
295    Val.setIsSigned(NewSign);
296
297    if (Val.isNegative())  // Sign bit changes meaning.
298      Diag(Loc, DiagID) << OldVal.toString(10) << Val.toString(10);
299  }
300}
301
302namespace {
303  struct CaseCompareFunctor {
304    bool operator()(const std::pair<llvm::APSInt, CaseStmt*> &LHS,
305                    const llvm::APSInt &RHS) {
306      return LHS.first < RHS;
307    }
308    bool operator()(const std::pair<llvm::APSInt, CaseStmt*> &LHS,
309                    const std::pair<llvm::APSInt, CaseStmt*> &RHS) {
310      return LHS.first < RHS.first;
311    }
312    bool operator()(const llvm::APSInt &LHS,
313                    const std::pair<llvm::APSInt, CaseStmt*> &RHS) {
314      return LHS < RHS.first;
315    }
316  };
317}
318
319/// CmpCaseVals - Comparison predicate for sorting case values.
320///
321static bool CmpCaseVals(const std::pair<llvm::APSInt, CaseStmt*>& lhs,
322                        const std::pair<llvm::APSInt, CaseStmt*>& rhs) {
323  if (lhs.first < rhs.first)
324    return true;
325
326  if (lhs.first == rhs.first &&
327      lhs.second->getCaseLoc().getRawEncoding()
328       < rhs.second->getCaseLoc().getRawEncoding())
329    return true;
330  return false;
331}
332
333Action::OwningStmtResult
334Sema::ActOnFinishSwitchStmt(SourceLocation SwitchLoc, StmtArg Switch,
335                            StmtArg Body) {
336  Stmt *BodyStmt = Body.takeAs<Stmt>();
337
338  SwitchStmt *SS = getSwitchStack().back();
339  assert(SS == (SwitchStmt*)Switch.get() && "switch stack missing push/pop!");
340
341  SS->setBody(BodyStmt, SwitchLoc);
342  getSwitchStack().pop_back();
343
344  Expr *CondExpr = SS->getCond();
345  QualType CondType = CondExpr->getType();
346
347  if (!CondExpr->isTypeDependent() &&
348      !CondType->isIntegerType()) { // C99 6.8.4.2p1
349    Diag(SwitchLoc, diag::err_typecheck_statement_requires_integer)
350      << CondType << CondExpr->getSourceRange();
351    return StmtError();
352  }
353
354  // Get the bitwidth of the switched-on value before promotions.  We must
355  // convert the integer case values to this width before comparison.
356  bool HasDependentValue
357    = CondExpr->isTypeDependent() || CondExpr->isValueDependent();
358  unsigned CondWidth
359    = HasDependentValue? 0
360                       : static_cast<unsigned>(Context.getTypeSize(CondType));
361  bool CondIsSigned = CondType->isSignedIntegerType();
362
363  // Accumulate all of the case values in a vector so that we can sort them
364  // and detect duplicates.  This vector contains the APInt for the case after
365  // it has been converted to the condition type.
366  typedef llvm::SmallVector<std::pair<llvm::APSInt, CaseStmt*>, 64> CaseValsTy;
367  CaseValsTy CaseVals;
368
369  // Keep track of any GNU case ranges we see.  The APSInt is the low value.
370  std::vector<std::pair<llvm::APSInt, CaseStmt*> > CaseRanges;
371
372  DefaultStmt *TheDefaultStmt = 0;
373
374  bool CaseListIsErroneous = false;
375
376  for (SwitchCase *SC = SS->getSwitchCaseList(); SC && !HasDependentValue;
377       SC = SC->getNextSwitchCase()) {
378
379    if (DefaultStmt *DS = dyn_cast<DefaultStmt>(SC)) {
380      if (TheDefaultStmt) {
381        Diag(DS->getDefaultLoc(), diag::err_multiple_default_labels_defined);
382        Diag(TheDefaultStmt->getDefaultLoc(), diag::note_duplicate_case_prev);
383
384        // FIXME: Remove the default statement from the switch block so that
385        // we'll return a valid AST.  This requires recursing down the AST and
386        // finding it, not something we are set up to do right now.  For now,
387        // just lop the entire switch stmt out of the AST.
388        CaseListIsErroneous = true;
389      }
390      TheDefaultStmt = DS;
391
392    } else {
393      CaseStmt *CS = cast<CaseStmt>(SC);
394
395      // We already verified that the expression has a i-c-e value (C99
396      // 6.8.4.2p3) - get that value now.
397      Expr *Lo = CS->getLHS();
398
399      if (Lo->isTypeDependent() || Lo->isValueDependent()) {
400        HasDependentValue = true;
401        break;
402      }
403
404      llvm::APSInt LoVal = Lo->EvaluateAsInt(Context);
405
406      // Convert the value to the same width/sign as the condition.
407      ConvertIntegerToTypeWarnOnOverflow(LoVal, CondWidth, CondIsSigned,
408                                         CS->getLHS()->getLocStart(),
409                                         diag::warn_case_value_overflow);
410
411      // If the LHS is not the same type as the condition, insert an implicit
412      // cast.
413      ImpCastExprToType(Lo, CondType);
414      CS->setLHS(Lo);
415
416      // If this is a case range, remember it in CaseRanges, otherwise CaseVals.
417      if (CS->getRHS()) {
418        if (CS->getRHS()->isTypeDependent() ||
419            CS->getRHS()->isValueDependent()) {
420          HasDependentValue = true;
421          break;
422        }
423        CaseRanges.push_back(std::make_pair(LoVal, CS));
424      } else
425        CaseVals.push_back(std::make_pair(LoVal, CS));
426    }
427  }
428
429  if (!HasDependentValue) {
430    // Sort all the scalar case values so we can easily detect duplicates.
431    std::stable_sort(CaseVals.begin(), CaseVals.end(), CmpCaseVals);
432
433    if (!CaseVals.empty()) {
434      for (unsigned i = 0, e = CaseVals.size()-1; i != e; ++i) {
435        if (CaseVals[i].first == CaseVals[i+1].first) {
436          // If we have a duplicate, report it.
437          Diag(CaseVals[i+1].second->getLHS()->getLocStart(),
438               diag::err_duplicate_case) << CaseVals[i].first.toString(10);
439          Diag(CaseVals[i].second->getLHS()->getLocStart(),
440               diag::note_duplicate_case_prev);
441          // FIXME: We really want to remove the bogus case stmt from the
442          // substmt, but we have no way to do this right now.
443          CaseListIsErroneous = true;
444        }
445      }
446    }
447
448    // Detect duplicate case ranges, which usually don't exist at all in
449    // the first place.
450    if (!CaseRanges.empty()) {
451      // Sort all the case ranges by their low value so we can easily detect
452      // overlaps between ranges.
453      std::stable_sort(CaseRanges.begin(), CaseRanges.end());
454
455      // Scan the ranges, computing the high values and removing empty ranges.
456      std::vector<llvm::APSInt> HiVals;
457      for (unsigned i = 0, e = CaseRanges.size(); i != e; ++i) {
458        CaseStmt *CR = CaseRanges[i].second;
459        Expr *Hi = CR->getRHS();
460        llvm::APSInt HiVal = Hi->EvaluateAsInt(Context);
461
462        // Convert the value to the same width/sign as the condition.
463        ConvertIntegerToTypeWarnOnOverflow(HiVal, CondWidth, CondIsSigned,
464                                           CR->getRHS()->getLocStart(),
465                                           diag::warn_case_value_overflow);
466
467        // If the LHS is not the same type as the condition, insert an implicit
468        // cast.
469        ImpCastExprToType(Hi, CondType);
470        CR->setRHS(Hi);
471
472        // If the low value is bigger than the high value, the case is empty.
473        if (CaseRanges[i].first > HiVal) {
474          Diag(CR->getLHS()->getLocStart(), diag::warn_case_empty_range)
475            << SourceRange(CR->getLHS()->getLocStart(),
476                           CR->getRHS()->getLocEnd());
477          CaseRanges.erase(CaseRanges.begin()+i);
478          --i, --e;
479          continue;
480        }
481        HiVals.push_back(HiVal);
482      }
483
484      // Rescan the ranges, looking for overlap with singleton values and other
485      // ranges.  Since the range list is sorted, we only need to compare case
486      // ranges with their neighbors.
487      for (unsigned i = 0, e = CaseRanges.size(); i != e; ++i) {
488        llvm::APSInt &CRLo = CaseRanges[i].first;
489        llvm::APSInt &CRHi = HiVals[i];
490        CaseStmt *CR = CaseRanges[i].second;
491
492        // Check to see whether the case range overlaps with any
493        // singleton cases.
494        CaseStmt *OverlapStmt = 0;
495        llvm::APSInt OverlapVal(32);
496
497        // Find the smallest value >= the lower bound.  If I is in the
498        // case range, then we have overlap.
499        CaseValsTy::iterator I = std::lower_bound(CaseVals.begin(),
500                                                  CaseVals.end(), CRLo,
501                                                  CaseCompareFunctor());
502        if (I != CaseVals.end() && I->first < CRHi) {
503          OverlapVal  = I->first;   // Found overlap with scalar.
504          OverlapStmt = I->second;
505        }
506
507        // Find the smallest value bigger than the upper bound.
508        I = std::upper_bound(I, CaseVals.end(), CRHi, CaseCompareFunctor());
509        if (I != CaseVals.begin() && (I-1)->first >= CRLo) {
510          OverlapVal  = (I-1)->first;      // Found overlap with scalar.
511          OverlapStmt = (I-1)->second;
512        }
513
514        // Check to see if this case stmt overlaps with the subsequent
515        // case range.
516        if (i && CRLo <= HiVals[i-1]) {
517          OverlapVal  = HiVals[i-1];       // Found overlap with range.
518          OverlapStmt = CaseRanges[i-1].second;
519        }
520
521        if (OverlapStmt) {
522          // If we have a duplicate, report it.
523          Diag(CR->getLHS()->getLocStart(), diag::err_duplicate_case)
524            << OverlapVal.toString(10);
525          Diag(OverlapStmt->getLHS()->getLocStart(),
526               diag::note_duplicate_case_prev);
527          // FIXME: We really want to remove the bogus case stmt from the
528          // substmt, but we have no way to do this right now.
529          CaseListIsErroneous = true;
530        }
531      }
532    }
533  }
534
535  // FIXME: If the case list was broken is some way, we don't have a good system
536  // to patch it up.  Instead, just return the whole substmt as broken.
537  if (CaseListIsErroneous)
538    return StmtError();
539
540  Switch.release();
541  return Owned(SS);
542}
543
544Action::OwningStmtResult
545Sema::ActOnWhileStmt(SourceLocation WhileLoc, ExprArg Cond, StmtArg Body) {
546  Expr *condExpr = Cond.takeAs<Expr>();
547  assert(condExpr && "ActOnWhileStmt(): missing expression");
548
549  if (!condExpr->isTypeDependent()) {
550    DefaultFunctionArrayConversion(condExpr);
551    Cond = condExpr;
552    QualType condType = condExpr->getType();
553
554    if (getLangOptions().CPlusPlus) {
555      if (CheckCXXBooleanCondition(condExpr)) // C++ 6.4p4
556        return StmtError();
557    } else if (!condType->isScalarType()) // C99 6.8.5p2
558      return StmtError(Diag(WhileLoc,
559                            diag::err_typecheck_statement_requires_scalar)
560                       << condType << condExpr->getSourceRange());
561  }
562
563  Cond.release();
564  return Owned(new (Context) WhileStmt(condExpr, Body.takeAs<Stmt>(),
565                                       WhileLoc));
566}
567
568Action::OwningStmtResult
569Sema::ActOnDoStmt(SourceLocation DoLoc, StmtArg Body,
570                  SourceLocation WhileLoc, ExprArg Cond) {
571  Expr *condExpr = Cond.takeAs<Expr>();
572  assert(condExpr && "ActOnDoStmt(): missing expression");
573
574  if (!condExpr->isTypeDependent()) {
575    DefaultFunctionArrayConversion(condExpr);
576    Cond = condExpr;
577    QualType condType = condExpr->getType();
578
579    if (getLangOptions().CPlusPlus) {
580      if (CheckCXXBooleanCondition(condExpr)) // C++ 6.4p4
581        return StmtError();
582    } else if (!condType->isScalarType()) // C99 6.8.5p2
583      return StmtError(Diag(DoLoc,
584                            diag::err_typecheck_statement_requires_scalar)
585                       << condType << condExpr->getSourceRange());
586  }
587
588  Cond.release();
589  return Owned(new (Context) DoStmt(Body.takeAs<Stmt>(), condExpr, DoLoc,
590                                    WhileLoc));
591}
592
593Action::OwningStmtResult
594Sema::ActOnForStmt(SourceLocation ForLoc, SourceLocation LParenLoc,
595                   StmtArg first, ExprArg second, ExprArg third,
596                   SourceLocation RParenLoc, StmtArg body) {
597  Stmt *First  = static_cast<Stmt*>(first.get());
598  Expr *Second = static_cast<Expr*>(second.get());
599  Expr *Third  = static_cast<Expr*>(third.get());
600  Stmt *Body  = static_cast<Stmt*>(body.get());
601
602  if (!getLangOptions().CPlusPlus) {
603    if (DeclStmt *DS = dyn_cast_or_null<DeclStmt>(First)) {
604      // C99 6.8.5p3: The declaration part of a 'for' statement shall only
605      // declare identifiers for objects having storage class 'auto' or
606      // 'register'.
607      for (DeclStmt::decl_iterator DI=DS->decl_begin(), DE=DS->decl_end();
608           DI!=DE; ++DI) {
609        VarDecl *VD = dyn_cast<VarDecl>(*DI);
610        if (VD && VD->isBlockVarDecl() && !VD->hasLocalStorage())
611          VD = 0;
612        if (VD == 0)
613          Diag((*DI)->getLocation(), diag::err_non_variable_decl_in_for);
614        // FIXME: mark decl erroneous!
615      }
616    }
617  }
618  if (Second && !Second->isTypeDependent()) {
619    DefaultFunctionArrayConversion(Second);
620    QualType SecondType = Second->getType();
621
622    if (getLangOptions().CPlusPlus) {
623      if (CheckCXXBooleanCondition(Second)) // C++ 6.4p4
624        return StmtError();
625    } else if (!SecondType->isScalarType()) // C99 6.8.5p2
626      return StmtError(Diag(ForLoc,
627                            diag::err_typecheck_statement_requires_scalar)
628        << SecondType << Second->getSourceRange());
629  }
630  first.release();
631  second.release();
632  third.release();
633  body.release();
634  return Owned(new (Context) ForStmt(First, Second, Third, Body, ForLoc,
635                                     LParenLoc, RParenLoc));
636}
637
638Action::OwningStmtResult
639Sema::ActOnObjCForCollectionStmt(SourceLocation ForLoc,
640                                 SourceLocation LParenLoc,
641                                 StmtArg first, ExprArg second,
642                                 SourceLocation RParenLoc, StmtArg body) {
643  Stmt *First  = static_cast<Stmt*>(first.get());
644  Expr *Second = static_cast<Expr*>(second.get());
645  Stmt *Body  = static_cast<Stmt*>(body.get());
646  if (First) {
647    QualType FirstType;
648    if (DeclStmt *DS = dyn_cast<DeclStmt>(First)) {
649      if (!DS->isSingleDecl())
650        return StmtError(Diag((*DS->decl_begin())->getLocation(),
651                         diag::err_toomany_element_decls));
652
653      Decl *D = DS->getSingleDecl();
654      FirstType = cast<ValueDecl>(D)->getType();
655      // C99 6.8.5p3: The declaration part of a 'for' statement shall only
656      // declare identifiers for objects having storage class 'auto' or
657      // 'register'.
658      VarDecl *VD = cast<VarDecl>(D);
659      if (VD->isBlockVarDecl() && !VD->hasLocalStorage())
660        return StmtError(Diag(VD->getLocation(),
661                              diag::err_non_variable_decl_in_for));
662    } else {
663      if (cast<Expr>(First)->isLvalue(Context) != Expr::LV_Valid)
664        return StmtError(Diag(First->getLocStart(),
665                   diag::err_selector_element_not_lvalue)
666          << First->getSourceRange());
667
668      FirstType = static_cast<Expr*>(First)->getType();
669    }
670    if (!Context.isObjCObjectPointerType(FirstType))
671        Diag(ForLoc, diag::err_selector_element_type)
672          << FirstType << First->getSourceRange();
673  }
674  if (Second) {
675    DefaultFunctionArrayConversion(Second);
676    QualType SecondType = Second->getType();
677    if (!Context.isObjCObjectPointerType(SecondType))
678      Diag(ForLoc, diag::err_collection_expr_type)
679        << SecondType << Second->getSourceRange();
680  }
681  first.release();
682  second.release();
683  body.release();
684  return Owned(new (Context) ObjCForCollectionStmt(First, Second, Body,
685                                                   ForLoc, RParenLoc));
686}
687
688Action::OwningStmtResult
689Sema::ActOnGotoStmt(SourceLocation GotoLoc, SourceLocation LabelLoc,
690                    IdentifierInfo *LabelII) {
691  // If we are in a block, reject all gotos for now.
692  if (CurBlock)
693    return StmtError(Diag(GotoLoc, diag::err_goto_in_block));
694
695  // Look up the record for this label identifier.
696  LabelStmt *&LabelDecl = getLabelMap()[LabelII];
697
698  // If we haven't seen this label yet, create a forward reference.
699  if (LabelDecl == 0)
700    LabelDecl = new (Context) LabelStmt(LabelLoc, LabelII, 0);
701
702  return Owned(new (Context) GotoStmt(LabelDecl, GotoLoc, LabelLoc));
703}
704
705Action::OwningStmtResult
706Sema::ActOnIndirectGotoStmt(SourceLocation GotoLoc, SourceLocation StarLoc,
707                            ExprArg DestExp) {
708  // Convert operand to void*
709  Expr* E = DestExp.takeAs<Expr>();
710  if (!E->isTypeDependent()) {
711    QualType ETy = E->getType();
712    AssignConvertType ConvTy =
713      CheckSingleAssignmentConstraints(Context.VoidPtrTy, E);
714    if (DiagnoseAssignmentResult(ConvTy, StarLoc, Context.VoidPtrTy, ETy,
715                                 E, "passing"))
716      return StmtError();
717  }
718  return Owned(new (Context) IndirectGotoStmt(GotoLoc, StarLoc, E));
719}
720
721Action::OwningStmtResult
722Sema::ActOnContinueStmt(SourceLocation ContinueLoc, Scope *CurScope) {
723  Scope *S = CurScope->getContinueParent();
724  if (!S) {
725    // C99 6.8.6.2p1: A break shall appear only in or as a loop body.
726    return StmtError(Diag(ContinueLoc, diag::err_continue_not_in_loop));
727  }
728
729  return Owned(new (Context) ContinueStmt(ContinueLoc));
730}
731
732Action::OwningStmtResult
733Sema::ActOnBreakStmt(SourceLocation BreakLoc, Scope *CurScope) {
734  Scope *S = CurScope->getBreakParent();
735  if (!S) {
736    // C99 6.8.6.3p1: A break shall appear only in or as a switch/loop body.
737    return StmtError(Diag(BreakLoc, diag::err_break_not_in_loop_or_switch));
738  }
739
740  return Owned(new (Context) BreakStmt(BreakLoc));
741}
742
743/// ActOnBlockReturnStmt - Utility routine to figure out block's return type.
744///
745Action::OwningStmtResult
746Sema::ActOnBlockReturnStmt(SourceLocation ReturnLoc, Expr *RetValExp) {
747  // If this is the first return we've seen in the block, infer the type of
748  // the block from it.
749  if (CurBlock->ReturnType == 0) {
750    if (RetValExp) {
751      // Don't call UsualUnaryConversions(), since we don't want to do
752      // integer promotions here.
753      DefaultFunctionArrayConversion(RetValExp);
754      CurBlock->ReturnType = RetValExp->getType().getTypePtr();
755    } else
756      CurBlock->ReturnType = Context.VoidTy.getTypePtr();
757  }
758  QualType FnRetType = QualType(CurBlock->ReturnType, 0);
759
760  if (CurBlock->TheDecl->hasAttr<NoReturnAttr>()) {
761    Diag(ReturnLoc, diag::err_noreturn_block_has_return_expr)
762      << getCurFunctionOrMethodDecl()->getDeclName();
763    return StmtError();
764  }
765
766  // Otherwise, verify that this result type matches the previous one.  We are
767  // pickier with blocks than for normal functions because we don't have GCC
768  // compatibility to worry about here.
769  if (CurBlock->ReturnType->isVoidType()) {
770    if (RetValExp) {
771      Diag(ReturnLoc, diag::err_return_block_has_expr);
772      RetValExp->Destroy(Context);
773      RetValExp = 0;
774    }
775    return Owned(new (Context) ReturnStmt(ReturnLoc, RetValExp));
776  }
777
778  if (!RetValExp)
779    return StmtError(Diag(ReturnLoc, diag::err_block_return_missing_expr));
780
781  if (!FnRetType->isDependentType() && !RetValExp->isTypeDependent()) {
782    // we have a non-void block with an expression, continue checking
783    QualType RetValType = RetValExp->getType();
784
785    // C99 6.8.6.4p3(136): The return statement is not an assignment. The
786    // overlap restriction of subclause 6.5.16.1 does not apply to the case of
787    // function return.
788
789    // In C++ the return statement is handled via a copy initialization.
790    // the C version of which boils down to CheckSingleAssignmentConstraints.
791    // FIXME: Leaks RetValExp.
792    if (PerformCopyInitialization(RetValExp, FnRetType, "returning"))
793      return StmtError();
794
795    if (RetValExp) CheckReturnStackAddr(RetValExp, FnRetType, ReturnLoc);
796  }
797
798  return Owned(new (Context) ReturnStmt(ReturnLoc, RetValExp));
799}
800
801/// IsReturnCopyElidable - Whether returning @p RetExpr from a function that
802/// returns a @p RetType fulfills the criteria for copy elision (C++0x 12.8p15).
803static bool IsReturnCopyElidable(ASTContext &Ctx, QualType RetType,
804                                 Expr *RetExpr) {
805  QualType ExprType = RetExpr->getType();
806  // - in a return statement in a function with ...
807  // ... a class return type ...
808  if (!RetType->isRecordType())
809    return false;
810  // ... the same cv-unqualified type as the function return type ...
811  if (Ctx.getCanonicalType(RetType).getUnqualifiedType() !=
812      Ctx.getCanonicalType(ExprType).getUnqualifiedType())
813    return false;
814  // ... the expression is the name of a non-volatile automatic object ...
815  // We ignore parentheses here.
816  // FIXME: Is this compliant?
817  const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(RetExpr->IgnoreParens());
818  if (!DR)
819    return false;
820  const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl());
821  if (!VD)
822    return false;
823  return VD->hasLocalStorage() && !VD->getType()->isReferenceType()
824    && !VD->getType().isVolatileQualified();
825}
826
827Action::OwningStmtResult
828Sema::ActOnReturnStmt(SourceLocation ReturnLoc, ExprArg rex) {
829  Expr *RetValExp = rex.takeAs<Expr>();
830  if (CurBlock)
831    return ActOnBlockReturnStmt(ReturnLoc, RetValExp);
832
833  QualType FnRetType;
834  if (const FunctionDecl *FD = getCurFunctionDecl()) {
835    FnRetType = FD->getResultType();
836    if (FD->hasAttr<NoReturnAttr>()) {
837      Diag(ReturnLoc, diag::err_noreturn_function_has_return_expr)
838        << getCurFunctionOrMethodDecl()->getDeclName();
839      return StmtError();
840    }
841  } else if (ObjCMethodDecl *MD = getCurMethodDecl())
842    FnRetType = MD->getResultType();
843  else // If we don't have a function/method context, bail.
844    return StmtError();
845
846  if (FnRetType->isVoidType()) {
847    if (RetValExp) {// C99 6.8.6.4p1 (ext_ since GCC warns)
848      unsigned D = diag::ext_return_has_expr;
849      if (RetValExp->getType()->isVoidType())
850        D = diag::ext_return_has_void_expr;
851
852      // return (some void expression); is legal in C++.
853      if (D != diag::ext_return_has_void_expr ||
854          !getLangOptions().CPlusPlus) {
855        NamedDecl *CurDecl = getCurFunctionOrMethodDecl();
856        Diag(ReturnLoc, D)
857          << CurDecl->getDeclName() << isa<ObjCMethodDecl>(CurDecl)
858          << RetValExp->getSourceRange();
859      }
860    }
861    return Owned(new (Context) ReturnStmt(ReturnLoc, RetValExp));
862  }
863
864  if (!RetValExp && !FnRetType->isDependentType()) {
865    unsigned DiagID = diag::warn_return_missing_expr;  // C90 6.6.6.4p4
866    // C99 6.8.6.4p1 (ext_ since GCC warns)
867    if (getLangOptions().C99) DiagID = diag::ext_return_missing_expr;
868
869    if (FunctionDecl *FD = getCurFunctionDecl())
870      Diag(ReturnLoc, DiagID) << FD->getIdentifier() << 0/*fn*/;
871    else
872      Diag(ReturnLoc, DiagID) << getCurMethodDecl()->getDeclName() << 1/*meth*/;
873    return Owned(new (Context) ReturnStmt(ReturnLoc, (Expr*)0));
874  }
875
876  if (!FnRetType->isDependentType() && !RetValExp->isTypeDependent()) {
877    // we have a non-void function with an expression, continue checking
878
879    // C99 6.8.6.4p3(136): The return statement is not an assignment. The
880    // overlap restriction of subclause 6.5.16.1 does not apply to the case of
881    // function return.
882
883    // C++0x 12.8p15: When certain criteria are met, an implementation is
884    //   allowed to omit the copy construction of a class object, [...]
885    //   - in a return statement in a function with a class return type, when
886    //     the expression is the name of a non-volatile automatic object with
887    //     the same cv-unqualified type as the function return type, the copy
888    //     operation can be omitted [...]
889    // C++0x 12.8p16: When the criteria for elision of a copy operation are met
890    //   and the object to be copied is designated by an lvalue, overload
891    //   resolution to select the constructor for the copy is first performed
892    //   as if the object were designated by an rvalue.
893    // Note that we only compute Elidable if we're in C++0x, since we don't
894    // care otherwise.
895    bool Elidable = getLangOptions().CPlusPlus0x ?
896                      IsReturnCopyElidable(Context, FnRetType, RetValExp) :
897                      false;
898
899    // In C++ the return statement is handled via a copy initialization.
900    // the C version of which boils down to CheckSingleAssignmentConstraints.
901    // FIXME: Leaks RetValExp on error.
902    if (PerformCopyInitialization(RetValExp, FnRetType, "returning", Elidable))
903      return StmtError();
904
905    if (RetValExp) CheckReturnStackAddr(RetValExp, FnRetType, ReturnLoc);
906  }
907
908  return Owned(new (Context) ReturnStmt(ReturnLoc, RetValExp));
909}
910
911/// CheckAsmLValue - GNU C has an extremely ugly extension whereby they silently
912/// ignore "noop" casts in places where an lvalue is required by an inline asm.
913/// We emulate this behavior when -fheinous-gnu-extensions is specified, but
914/// provide a strong guidance to not use it.
915///
916/// This method checks to see if the argument is an acceptable l-value and
917/// returns false if it is a case we can handle.
918static bool CheckAsmLValue(const Expr *E, Sema &S) {
919  if (E->isLvalue(S.Context) == Expr::LV_Valid)
920    return false;  // Cool, this is an lvalue.
921
922  // Okay, this is not an lvalue, but perhaps it is the result of a cast that we
923  // are supposed to allow.
924  const Expr *E2 = E->IgnoreParenNoopCasts(S.Context);
925  if (E != E2 && E2->isLvalue(S.Context) == Expr::LV_Valid) {
926    if (!S.getLangOptions().HeinousExtensions)
927      S.Diag(E2->getLocStart(), diag::err_invalid_asm_cast_lvalue)
928        << E->getSourceRange();
929    else
930      S.Diag(E2->getLocStart(), diag::warn_invalid_asm_cast_lvalue)
931        << E->getSourceRange();
932    // Accept, even if we emitted an error diagnostic.
933    return false;
934  }
935
936  // None of the above, just randomly invalid non-lvalue.
937  return true;
938}
939
940
941Sema::OwningStmtResult Sema::ActOnAsmStmt(SourceLocation AsmLoc,
942                                          bool IsSimple,
943                                          bool IsVolatile,
944                                          unsigned NumOutputs,
945                                          unsigned NumInputs,
946                                          std::string *Names,
947                                          MultiExprArg constraints,
948                                          MultiExprArg exprs,
949                                          ExprArg asmString,
950                                          MultiExprArg clobbers,
951                                          SourceLocation RParenLoc) {
952  unsigned NumClobbers = clobbers.size();
953  StringLiteral **Constraints =
954    reinterpret_cast<StringLiteral**>(constraints.get());
955  Expr **Exprs = reinterpret_cast<Expr **>(exprs.get());
956  StringLiteral *AsmString = cast<StringLiteral>((Expr *)asmString.get());
957  StringLiteral **Clobbers = reinterpret_cast<StringLiteral**>(clobbers.get());
958
959  llvm::SmallVector<TargetInfo::ConstraintInfo, 4> OutputConstraintInfos;
960
961  // The parser verifies that there is a string literal here.
962  if (AsmString->isWide())
963    return StmtError(Diag(AsmString->getLocStart(),diag::err_asm_wide_character)
964      << AsmString->getSourceRange());
965
966  for (unsigned i = 0; i != NumOutputs; i++) {
967    StringLiteral *Literal = Constraints[i];
968    if (Literal->isWide())
969      return StmtError(Diag(Literal->getLocStart(),diag::err_asm_wide_character)
970        << Literal->getSourceRange());
971
972    TargetInfo::ConstraintInfo Info(Literal->getStrData(),
973                                    Literal->getByteLength(),
974                                    Names[i]);
975    if (!Context.Target.validateOutputConstraint(Info))
976      return StmtError(Diag(Literal->getLocStart(),
977                            diag::err_asm_invalid_output_constraint)
978                       << Info.getConstraintStr());
979
980    // Check that the output exprs are valid lvalues.
981    Expr *OutputExpr = Exprs[i];
982    if (CheckAsmLValue(OutputExpr, *this)) {
983      return StmtError(Diag(OutputExpr->getLocStart(),
984                  diag::err_asm_invalid_lvalue_in_output)
985        << OutputExpr->getSourceRange());
986    }
987
988    OutputConstraintInfos.push_back(Info);
989  }
990
991  llvm::SmallVector<TargetInfo::ConstraintInfo, 4> InputConstraintInfos;
992
993  for (unsigned i = NumOutputs, e = NumOutputs + NumInputs; i != e; i++) {
994    StringLiteral *Literal = Constraints[i];
995    if (Literal->isWide())
996      return StmtError(Diag(Literal->getLocStart(),diag::err_asm_wide_character)
997        << Literal->getSourceRange());
998
999    TargetInfo::ConstraintInfo Info(Literal->getStrData(),
1000                                    Literal->getByteLength(),
1001                                    Names[i]);
1002    if (!Context.Target.validateInputConstraint(&OutputConstraintInfos[0],
1003                                                NumOutputs, Info)) {
1004      return StmtError(Diag(Literal->getLocStart(),
1005                            diag::err_asm_invalid_input_constraint)
1006                       << Info.getConstraintStr());
1007    }
1008
1009    Expr *InputExpr = Exprs[i];
1010
1011    // Only allow void types for memory constraints.
1012    if (Info.allowsMemory() && !Info.allowsRegister()) {
1013      if (CheckAsmLValue(InputExpr, *this))
1014        return StmtError(Diag(InputExpr->getLocStart(),
1015                              diag::err_asm_invalid_lvalue_in_input)
1016                         << Info.getConstraintStr()
1017                         << InputExpr->getSourceRange());
1018    }
1019
1020    if (Info.allowsRegister()) {
1021      if (InputExpr->getType()->isVoidType()) {
1022        return StmtError(Diag(InputExpr->getLocStart(),
1023                              diag::err_asm_invalid_type_in_input)
1024          << InputExpr->getType() << Info.getConstraintStr()
1025          << InputExpr->getSourceRange());
1026      }
1027    }
1028
1029    DefaultFunctionArrayConversion(Exprs[i]);
1030
1031    InputConstraintInfos.push_back(Info);
1032  }
1033
1034  // Check that the clobbers are valid.
1035  for (unsigned i = 0; i != NumClobbers; i++) {
1036    StringLiteral *Literal = Clobbers[i];
1037    if (Literal->isWide())
1038      return StmtError(Diag(Literal->getLocStart(),diag::err_asm_wide_character)
1039        << Literal->getSourceRange());
1040
1041    llvm::SmallString<16> Clobber(Literal->getStrData(),
1042                                  Literal->getStrData() +
1043                                  Literal->getByteLength());
1044
1045    if (!Context.Target.isValidGCCRegisterName(Clobber.c_str()))
1046      return StmtError(Diag(Literal->getLocStart(),
1047                  diag::err_asm_unknown_register_name) << Clobber.c_str());
1048  }
1049
1050  constraints.release();
1051  exprs.release();
1052  asmString.release();
1053  clobbers.release();
1054  AsmStmt *NS =
1055    new (Context) AsmStmt(AsmLoc, IsSimple, IsVolatile, NumOutputs, NumInputs,
1056                          Names, Constraints, Exprs, AsmString, NumClobbers,
1057                          Clobbers, RParenLoc);
1058  // Validate the asm string, ensuring it makes sense given the operands we
1059  // have.
1060  llvm::SmallVector<AsmStmt::AsmStringPiece, 8> Pieces;
1061  unsigned DiagOffs;
1062  if (unsigned DiagID = NS->AnalyzeAsmString(Pieces, Context, DiagOffs)) {
1063    Diag(getLocationOfStringLiteralByte(AsmString, DiagOffs), DiagID)
1064           << AsmString->getSourceRange();
1065    DeleteStmt(NS);
1066    return StmtError();
1067  }
1068
1069  // Validate tied input operands for type mismatches.
1070  for (unsigned i = 0, e = InputConstraintInfos.size(); i != e; ++i) {
1071    TargetInfo::ConstraintInfo &Info = InputConstraintInfos[i];
1072
1073    // If this is a tied constraint, verify that the output and input have
1074    // either exactly the same type, or that they are int/ptr operands with the
1075    // same size (int/long, int*/long, are ok etc).
1076    if (!Info.hasTiedOperand()) continue;
1077
1078    unsigned TiedTo = Info.getTiedOperand();
1079    Expr *OutputExpr = Exprs[TiedTo];
1080    Expr *InputExpr = Exprs[i+NumOutputs];
1081    QualType InTy = InputExpr->getType();
1082    QualType OutTy = OutputExpr->getType();
1083    if (Context.hasSameType(InTy, OutTy))
1084      continue;  // All types can be tied to themselves.
1085
1086    // Int/ptr operands have some special cases that we allow.
1087    if ((OutTy->isIntegerType() || OutTy->isPointerType()) &&
1088        (InTy->isIntegerType() || InTy->isPointerType())) {
1089
1090      // They are ok if they are the same size.  Tying void* to int is ok if
1091      // they are the same size, for example.  This also allows tying void* to
1092      // int*.
1093      uint64_t OutSize = Context.getTypeSize(OutTy);
1094      uint64_t InSize = Context.getTypeSize(InTy);
1095      if (OutSize == InSize)
1096        continue;
1097
1098      // If the smaller input/output operand is not mentioned in the asm string,
1099      // then we can promote it and the asm string won't notice.  Check this
1100      // case now.
1101      bool SmallerValueMentioned = false;
1102      for (unsigned p = 0, e = Pieces.size(); p != e; ++p) {
1103        AsmStmt::AsmStringPiece &Piece = Pieces[p];
1104        if (!Piece.isOperand()) continue;
1105
1106        // If this is a reference to the input and if the input was the smaller
1107        // one, then we have to reject this asm.
1108        if (Piece.getOperandNo() == i+NumOutputs) {
1109          if (InSize < OutSize) {
1110            SmallerValueMentioned = true;
1111            break;
1112          }
1113        }
1114
1115        // If this is a reference to the input and if the input was the smaller
1116        // one, then we have to reject this asm.
1117        if (Piece.getOperandNo() == TiedTo) {
1118          if (InSize > OutSize) {
1119            SmallerValueMentioned = true;
1120            break;
1121          }
1122        }
1123      }
1124
1125      // If the smaller value wasn't mentioned in the asm string, and if the
1126      // output was a register, just extend the shorter one to the size of the
1127      // larger one.
1128      if (!SmallerValueMentioned &&
1129          OutputConstraintInfos[TiedTo].allowsRegister())
1130        continue;
1131    }
1132
1133    Diag(InputExpr->getLocStart(),
1134         diag::err_asm_tying_incompatible_types)
1135      << InTy << OutTy << OutputExpr->getSourceRange()
1136      << InputExpr->getSourceRange();
1137    DeleteStmt(NS);
1138    return StmtError();
1139  }
1140
1141  return Owned(NS);
1142}
1143
1144Action::OwningStmtResult
1145Sema::ActOnObjCAtCatchStmt(SourceLocation AtLoc,
1146                           SourceLocation RParen, DeclPtrTy Parm,
1147                           StmtArg Body, StmtArg catchList) {
1148  Stmt *CatchList = catchList.takeAs<Stmt>();
1149  ParmVarDecl *PVD = cast_or_null<ParmVarDecl>(Parm.getAs<Decl>());
1150
1151  // PVD == 0 implies @catch(...).
1152  if (PVD) {
1153    // If we already know the decl is invalid, reject it.
1154    if (PVD->isInvalidDecl())
1155      return StmtError();
1156
1157    if (!Context.isObjCObjectPointerType(PVD->getType()))
1158      return StmtError(Diag(PVD->getLocation(),
1159                       diag::err_catch_param_not_objc_type));
1160    if (PVD->getType()->isObjCQualifiedIdType())
1161      return StmtError(Diag(PVD->getLocation(),
1162                       diag::err_illegal_qualifiers_on_catch_parm));
1163  }
1164
1165  ObjCAtCatchStmt *CS = new (Context) ObjCAtCatchStmt(AtLoc, RParen,
1166    PVD, Body.takeAs<Stmt>(), CatchList);
1167  return Owned(CatchList ? CatchList : CS);
1168}
1169
1170Action::OwningStmtResult
1171Sema::ActOnObjCAtFinallyStmt(SourceLocation AtLoc, StmtArg Body) {
1172  return Owned(new (Context) ObjCAtFinallyStmt(AtLoc,
1173                                           static_cast<Stmt*>(Body.release())));
1174}
1175
1176Action::OwningStmtResult
1177Sema::ActOnObjCAtTryStmt(SourceLocation AtLoc,
1178                         StmtArg Try, StmtArg Catch, StmtArg Finally) {
1179  CurFunctionNeedsScopeChecking = true;
1180  return Owned(new (Context) ObjCAtTryStmt(AtLoc, Try.takeAs<Stmt>(),
1181                                           Catch.takeAs<Stmt>(),
1182                                           Finally.takeAs<Stmt>()));
1183}
1184
1185Action::OwningStmtResult
1186Sema::ActOnObjCAtThrowStmt(SourceLocation AtLoc, ExprArg expr,Scope *CurScope) {
1187  Expr *ThrowExpr = expr.takeAs<Expr>();
1188  if (!ThrowExpr) {
1189    // @throw without an expression designates a rethrow (which much occur
1190    // in the context of an @catch clause).
1191    Scope *AtCatchParent = CurScope;
1192    while (AtCatchParent && !AtCatchParent->isAtCatchScope())
1193      AtCatchParent = AtCatchParent->getParent();
1194    if (!AtCatchParent)
1195      return StmtError(Diag(AtLoc, diag::error_rethrow_used_outside_catch));
1196  } else {
1197    QualType ThrowType = ThrowExpr->getType();
1198    // Make sure the expression type is an ObjC pointer or "void *".
1199    if (!Context.isObjCObjectPointerType(ThrowType)) {
1200      const PointerType *PT = ThrowType->getAsPointerType();
1201      if (!PT || !PT->getPointeeType()->isVoidType())
1202        return StmtError(Diag(AtLoc, diag::error_objc_throw_expects_object)
1203                        << ThrowExpr->getType() << ThrowExpr->getSourceRange());
1204    }
1205  }
1206  return Owned(new (Context) ObjCAtThrowStmt(AtLoc, ThrowExpr));
1207}
1208
1209Action::OwningStmtResult
1210Sema::ActOnObjCAtSynchronizedStmt(SourceLocation AtLoc, ExprArg SynchExpr,
1211                                  StmtArg SynchBody) {
1212  CurFunctionNeedsScopeChecking = true;
1213
1214  // Make sure the expression type is an ObjC pointer or "void *".
1215  Expr *SyncExpr = static_cast<Expr*>(SynchExpr.get());
1216  if (!Context.isObjCObjectPointerType(SyncExpr->getType())) {
1217    const PointerType *PT = SyncExpr->getType()->getAsPointerType();
1218    if (!PT || !PT->getPointeeType()->isVoidType())
1219      return StmtError(Diag(AtLoc, diag::error_objc_synchronized_expects_object)
1220                       << SyncExpr->getType() << SyncExpr->getSourceRange());
1221  }
1222
1223  return Owned(new (Context) ObjCAtSynchronizedStmt(AtLoc,
1224                                                    SynchExpr.takeAs<Stmt>(),
1225                                                    SynchBody.takeAs<Stmt>()));
1226}
1227
1228/// ActOnCXXCatchBlock - Takes an exception declaration and a handler block
1229/// and creates a proper catch handler from them.
1230Action::OwningStmtResult
1231Sema::ActOnCXXCatchBlock(SourceLocation CatchLoc, DeclPtrTy ExDecl,
1232                         StmtArg HandlerBlock) {
1233  // There's nothing to test that ActOnExceptionDecl didn't already test.
1234  return Owned(new (Context) CXXCatchStmt(CatchLoc,
1235                                  cast_or_null<VarDecl>(ExDecl.getAs<Decl>()),
1236                                          HandlerBlock.takeAs<Stmt>()));
1237}
1238
1239/// ActOnCXXTryBlock - Takes a try compound-statement and a number of
1240/// handlers and creates a try statement from them.
1241Action::OwningStmtResult
1242Sema::ActOnCXXTryBlock(SourceLocation TryLoc, StmtArg TryBlock,
1243                       MultiStmtArg RawHandlers) {
1244  unsigned NumHandlers = RawHandlers.size();
1245  assert(NumHandlers > 0 &&
1246         "The parser shouldn't call this if there are no handlers.");
1247  Stmt **Handlers = reinterpret_cast<Stmt**>(RawHandlers.get());
1248
1249  for(unsigned i = 0; i < NumHandlers - 1; ++i) {
1250    CXXCatchStmt *Handler = llvm::cast<CXXCatchStmt>(Handlers[i]);
1251    if (!Handler->getExceptionDecl())
1252      return StmtError(Diag(Handler->getLocStart(), diag::err_early_catch_all));
1253  }
1254  // FIXME: We should detect handlers for the same type as an earlier one.
1255  // This one is rather easy.
1256  // FIXME: We should detect handlers that cannot catch anything because an
1257  // earlier handler catches a superclass. Need to find a method that is not
1258  // quadratic for this.
1259  // Neither of these are explicitly forbidden, but every compiler detects them
1260  // and warns.
1261
1262  CurFunctionNeedsScopeChecking = true;
1263  RawHandlers.release();
1264  return Owned(new (Context) CXXTryStmt(TryLoc,
1265                                        static_cast<Stmt*>(TryBlock.release()),
1266                                        Handlers, NumHandlers));
1267}
1268