Sema.cpp revision 6fd7d3067dd06584ef3940e88e31fea1a0e83588 
1//===--- Sema.cpp - AST Builder and Semantic Analysis Implementation ------===//
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 the actions class which performs semantic analysis and
11// builds an AST out of a parse stream.
12//
13//===----------------------------------------------------------------------===//
14
15#include "clang/Sema/SemaInternal.h"
16#include "TargetAttributesSema.h"
17#include "clang/AST/ASTContext.h"
18#include "clang/AST/ASTDiagnostic.h"
19#include "clang/AST/DeclCXX.h"
20#include "clang/AST/DeclFriend.h"
21#include "clang/AST/DeclObjC.h"
22#include "clang/AST/Expr.h"
23#include "clang/AST/ExprCXX.h"
24#include "clang/AST/StmtCXX.h"
25#include "clang/Basic/FileManager.h"
26#include "clang/Basic/PartialDiagnostic.h"
27#include "clang/Basic/TargetInfo.h"
28#include "clang/Lex/HeaderSearch.h"
29#include "clang/Lex/Preprocessor.h"
30#include "clang/Sema/CXXFieldCollector.h"
31#include "clang/Sema/DelayedDiagnostic.h"
32#include "clang/Sema/ExternalSemaSource.h"
33#include "clang/Sema/MultiplexExternalSemaSource.h"
34#include "clang/Sema/ObjCMethodList.h"
35#include "clang/Sema/PrettyDeclStackTrace.h"
36#include "clang/Sema/Scope.h"
37#include "clang/Sema/ScopeInfo.h"
38#include "clang/Sema/SemaConsumer.h"
39#include "clang/Sema/TemplateDeduction.h"
40#include "llvm/ADT/APFloat.h"
41#include "llvm/ADT/DenseMap.h"
42#include "llvm/ADT/SmallSet.h"
43#include "llvm/Support/CrashRecoveryContext.h"
44using namespace clang;
45using namespace sema;
46
47PrintingPolicy Sema::getPrintingPolicy(const ASTContext &Context,
48                                       const Preprocessor &PP) {
49  PrintingPolicy Policy = Context.getPrintingPolicy();
50  Policy.Bool = Context.getLangOpts().Bool;
51  if (!Policy.Bool) {
52    if (const MacroInfo *
53          BoolMacro = PP.getMacroInfo(&Context.Idents.get("bool"))) {
54      Policy.Bool = BoolMacro->isObjectLike() &&
55        BoolMacro->getNumTokens() == 1 &&
56        BoolMacro->getReplacementToken(0).is(tok::kw__Bool);
57    }
58  }
59
60  return Policy;
61}
62
63void Sema::ActOnTranslationUnitScope(Scope *S) {
64  TUScope = S;
65  PushDeclContext(S, Context.getTranslationUnitDecl());
66
67  VAListTagName = PP.getIdentifierInfo("__va_list_tag");
68}
69
70Sema::Sema(Preprocessor &pp, ASTContext &ctxt, ASTConsumer &consumer,
71           TranslationUnitKind TUKind,
72           CodeCompleteConsumer *CodeCompleter)
73  : TheTargetAttributesSema(0), ExternalSource(0),
74    isMultiplexExternalSource(false), FPFeatures(pp.getLangOpts()),
75    LangOpts(pp.getLangOpts()), PP(pp), Context(ctxt), Consumer(consumer),
76    Diags(PP.getDiagnostics()), SourceMgr(PP.getSourceManager()),
77    CollectStats(false), CodeCompleter(CodeCompleter),
78    CurContext(0), OriginalLexicalContext(0),
79    PackContext(0), MSStructPragmaOn(false), VisContext(0),
80    IsBuildingRecoveryCallExpr(false),
81    ExprNeedsCleanups(false), LateTemplateParser(0), OpaqueParser(0),
82    IdResolver(pp), StdInitializerList(0), CXXTypeInfoDecl(0), MSVCGuidDecl(0),
83    NSNumberDecl(0),
84    NSStringDecl(0), StringWithUTF8StringMethod(0),
85    NSArrayDecl(0), ArrayWithObjectsMethod(0),
86    NSDictionaryDecl(0), DictionaryWithObjectsMethod(0),
87    GlobalNewDeleteDeclared(false),
88    TUKind(TUKind),
89    NumSFINAEErrors(0), InFunctionDeclarator(0),
90    AccessCheckingSFINAE(false), InNonInstantiationSFINAEContext(false),
91    NonInstantiationEntries(0), ArgumentPackSubstitutionIndex(-1),
92    CurrentInstantiationScope(0), TyposCorrected(0),
93    AnalysisWarnings(*this), Ident_super(0)
94{
95  TUScope = 0;
96
97  LoadedExternalKnownNamespaces = false;
98  for (unsigned I = 0; I != NSAPI::NumNSNumberLiteralMethods; ++I)
99    NSNumberLiteralMethods[I] = 0;
100
101  if (getLangOpts().ObjC1)
102    NSAPIObj.reset(new NSAPI(Context));
103
104  if (getLangOpts().CPlusPlus)
105    FieldCollector.reset(new CXXFieldCollector());
106
107  // Tell diagnostics how to render things from the AST library.
108  PP.getDiagnostics().SetArgToStringFn(&FormatASTNodeDiagnosticArgument,
109                                       &Context);
110
111  ExprEvalContexts.push_back(
112        ExpressionEvaluationContextRecord(PotentiallyEvaluated, 0,
113                                          false, 0, false));
114
115  FunctionScopes.push_back(new FunctionScopeInfo(Diags));
116}
117
118void Sema::Initialize() {
119  // Tell the AST consumer about this Sema object.
120  Consumer.Initialize(Context);
121
122  // FIXME: Isn't this redundant with the initialization above?
123  if (SemaConsumer *SC = dyn_cast<SemaConsumer>(&Consumer))
124    SC->InitializeSema(*this);
125
126  // Tell the external Sema source about this Sema object.
127  if (ExternalSemaSource *ExternalSema
128      = dyn_cast_or_null<ExternalSemaSource>(Context.getExternalSource()))
129    ExternalSema->InitializeSema(*this);
130
131  // Initialize predefined 128-bit integer types, if needed.
132  if (PP.getTargetInfo().hasInt128Type()) {
133    // If either of the 128-bit integer types are unavailable to name lookup,
134    // define them now.
135    DeclarationName Int128 = &Context.Idents.get("__int128_t");
136    if (IdResolver.begin(Int128) == IdResolver.end())
137      PushOnScopeChains(Context.getInt128Decl(), TUScope);
138
139    DeclarationName UInt128 = &Context.Idents.get("__uint128_t");
140    if (IdResolver.begin(UInt128) == IdResolver.end())
141      PushOnScopeChains(Context.getUInt128Decl(), TUScope);
142  }
143
144
145  // Initialize predefined Objective-C types:
146  if (PP.getLangOpts().ObjC1) {
147    // If 'SEL' does not yet refer to any declarations, make it refer to the
148    // predefined 'SEL'.
149    DeclarationName SEL = &Context.Idents.get("SEL");
150    if (IdResolver.begin(SEL) == IdResolver.end())
151      PushOnScopeChains(Context.getObjCSelDecl(), TUScope);
152
153    // If 'id' does not yet refer to any declarations, make it refer to the
154    // predefined 'id'.
155    DeclarationName Id = &Context.Idents.get("id");
156    if (IdResolver.begin(Id) == IdResolver.end())
157      PushOnScopeChains(Context.getObjCIdDecl(), TUScope);
158
159    // Create the built-in typedef for 'Class'.
160    DeclarationName Class = &Context.Idents.get("Class");
161    if (IdResolver.begin(Class) == IdResolver.end())
162      PushOnScopeChains(Context.getObjCClassDecl(), TUScope);
163
164    // Create the built-in forward declaratino for 'Protocol'.
165    DeclarationName Protocol = &Context.Idents.get("Protocol");
166    if (IdResolver.begin(Protocol) == IdResolver.end())
167      PushOnScopeChains(Context.getObjCProtocolDecl(), TUScope);
168  }
169
170  DeclarationName BuiltinVaList = &Context.Idents.get("__builtin_va_list");
171  if (IdResolver.begin(BuiltinVaList) == IdResolver.end())
172    PushOnScopeChains(Context.getBuiltinVaListDecl(), TUScope);
173}
174
175Sema::~Sema() {
176  if (PackContext) FreePackedContext();
177  if (VisContext) FreeVisContext();
178  delete TheTargetAttributesSema;
179  MSStructPragmaOn = false;
180  // Kill all the active scopes.
181  for (unsigned I = 1, E = FunctionScopes.size(); I != E; ++I)
182    delete FunctionScopes[I];
183  if (FunctionScopes.size() == 1)
184    delete FunctionScopes[0];
185
186  // Tell the SemaConsumer to forget about us; we're going out of scope.
187  if (SemaConsumer *SC = dyn_cast<SemaConsumer>(&Consumer))
188    SC->ForgetSema();
189
190  // Detach from the external Sema source.
191  if (ExternalSemaSource *ExternalSema
192        = dyn_cast_or_null<ExternalSemaSource>(Context.getExternalSource()))
193    ExternalSema->ForgetSema();
194
195  // If Sema's ExternalSource is the multiplexer - we own it.
196  if (isMultiplexExternalSource)
197    delete ExternalSource;
198}
199
200/// makeUnavailableInSystemHeader - There is an error in the current
201/// context.  If we're still in a system header, and we can plausibly
202/// make the relevant declaration unavailable instead of erroring, do
203/// so and return true.
204bool Sema::makeUnavailableInSystemHeader(SourceLocation loc,
205                                         StringRef msg) {
206  // If we're not in a function, it's an error.
207  FunctionDecl *fn = dyn_cast<FunctionDecl>(CurContext);
208  if (!fn) return false;
209
210  // If we're in template instantiation, it's an error.
211  if (!ActiveTemplateInstantiations.empty())
212    return false;
213
214  // If that function's not in a system header, it's an error.
215  if (!Context.getSourceManager().isInSystemHeader(loc))
216    return false;
217
218  // If the function is already unavailable, it's not an error.
219  if (fn->hasAttr<UnavailableAttr>()) return true;
220
221  fn->addAttr(new (Context) UnavailableAttr(loc, Context, msg));
222  return true;
223}
224
225ASTMutationListener *Sema::getASTMutationListener() const {
226  return getASTConsumer().GetASTMutationListener();
227}
228
229///\brief Registers an external source. If an external source already exists,
230/// creates a multiplex external source and appends to it.
231///
232///\param[in] E - A non-null external sema source.
233///
234void Sema::addExternalSource(ExternalSemaSource *E) {
235  assert(E && "Cannot use with NULL ptr");
236
237  if (!ExternalSource) {
238    ExternalSource = E;
239    return;
240  }
241
242  if (isMultiplexExternalSource)
243    static_cast<MultiplexExternalSemaSource*>(ExternalSource)->addSource(*E);
244  else {
245    ExternalSource = new MultiplexExternalSemaSource(*ExternalSource, *E);
246    isMultiplexExternalSource = true;
247  }
248}
249
250/// \brief Print out statistics about the semantic analysis.
251void Sema::PrintStats() const {
252  llvm::errs() << "\n*** Semantic Analysis Stats:\n";
253  llvm::errs() << NumSFINAEErrors << " SFINAE diagnostics trapped.\n";
254
255  BumpAlloc.PrintStats();
256  AnalysisWarnings.PrintStats();
257}
258
259/// ImpCastExprToType - If Expr is not of type 'Type', insert an implicit cast.
260/// If there is already an implicit cast, merge into the existing one.
261/// The result is of the given category.
262ExprResult Sema::ImpCastExprToType(Expr *E, QualType Ty,
263                                   CastKind Kind, ExprValueKind VK,
264                                   const CXXCastPath *BasePath,
265                                   CheckedConversionKind CCK) {
266#ifndef NDEBUG
267  if (VK == VK_RValue && !E->isRValue()) {
268    switch (Kind) {
269    default:
270      assert(0 && "can't implicitly cast lvalue to rvalue with this cast kind");
271    case CK_LValueToRValue:
272    case CK_ArrayToPointerDecay:
273    case CK_FunctionToPointerDecay:
274    case CK_ToVoid:
275      break;
276    }
277  }
278  assert((VK == VK_RValue || !E->isRValue()) && "can't cast rvalue to lvalue");
279#endif
280
281  QualType ExprTy = Context.getCanonicalType(E->getType());
282  QualType TypeTy = Context.getCanonicalType(Ty);
283
284  if (ExprTy == TypeTy)
285    return Owned(E);
286
287  if (getLangOpts().ObjCAutoRefCount)
288    CheckObjCARCConversion(SourceRange(), Ty, E, CCK);
289
290  // If this is a derived-to-base cast to a through a virtual base, we
291  // need a vtable.
292  if (Kind == CK_DerivedToBase &&
293      BasePathInvolvesVirtualBase(*BasePath)) {
294    QualType T = E->getType();
295    if (const PointerType *Pointer = T->getAs<PointerType>())
296      T = Pointer->getPointeeType();
297    if (const RecordType *RecordTy = T->getAs<RecordType>())
298      MarkVTableUsed(E->getLocStart(),
299                     cast<CXXRecordDecl>(RecordTy->getDecl()));
300  }
301
302  if (ImplicitCastExpr *ImpCast = dyn_cast<ImplicitCastExpr>(E)) {
303    if (ImpCast->getCastKind() == Kind && (!BasePath || BasePath->empty())) {
304      ImpCast->setType(Ty);
305      ImpCast->setValueKind(VK);
306      return Owned(E);
307    }
308  }
309
310  return Owned(ImplicitCastExpr::Create(Context, Ty, Kind, E, BasePath, VK));
311}
312
313/// ScalarTypeToBooleanCastKind - Returns the cast kind corresponding
314/// to the conversion from scalar type ScalarTy to the Boolean type.
315CastKind Sema::ScalarTypeToBooleanCastKind(QualType ScalarTy) {
316  switch (ScalarTy->getScalarTypeKind()) {
317  case Type::STK_Bool: return CK_NoOp;
318  case Type::STK_CPointer: return CK_PointerToBoolean;
319  case Type::STK_BlockPointer: return CK_PointerToBoolean;
320  case Type::STK_ObjCObjectPointer: return CK_PointerToBoolean;
321  case Type::STK_MemberPointer: return CK_MemberPointerToBoolean;
322  case Type::STK_Integral: return CK_IntegralToBoolean;
323  case Type::STK_Floating: return CK_FloatingToBoolean;
324  case Type::STK_IntegralComplex: return CK_IntegralComplexToBoolean;
325  case Type::STK_FloatingComplex: return CK_FloatingComplexToBoolean;
326  }
327  return CK_Invalid;
328}
329
330/// \brief Used to prune the decls of Sema's UnusedFileScopedDecls vector.
331static bool ShouldRemoveFromUnused(Sema *SemaRef, const DeclaratorDecl *D) {
332  if (D->getMostRecentDecl()->isUsed())
333    return true;
334
335  if (D->hasExternalLinkage())
336    return true;
337
338  if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
339    // UnusedFileScopedDecls stores the first declaration.
340    // The declaration may have become definition so check again.
341    const FunctionDecl *DeclToCheck;
342    if (FD->hasBody(DeclToCheck))
343      return !SemaRef->ShouldWarnIfUnusedFileScopedDecl(DeclToCheck);
344
345    // Later redecls may add new information resulting in not having to warn,
346    // so check again.
347    DeclToCheck = FD->getMostRecentDecl();
348    if (DeclToCheck != FD)
349      return !SemaRef->ShouldWarnIfUnusedFileScopedDecl(DeclToCheck);
350  }
351
352  if (const VarDecl *VD = dyn_cast<VarDecl>(D)) {
353    // UnusedFileScopedDecls stores the first declaration.
354    // The declaration may have become definition so check again.
355    const VarDecl *DeclToCheck = VD->getDefinition();
356    if (DeclToCheck)
357      return !SemaRef->ShouldWarnIfUnusedFileScopedDecl(DeclToCheck);
358
359    // Later redecls may add new information resulting in not having to warn,
360    // so check again.
361    DeclToCheck = VD->getMostRecentDecl();
362    if (DeclToCheck != VD)
363      return !SemaRef->ShouldWarnIfUnusedFileScopedDecl(DeclToCheck);
364  }
365
366  return false;
367}
368
369namespace {
370  struct SortUndefinedButUsed {
371    const SourceManager &SM;
372    explicit SortUndefinedButUsed(SourceManager &SM) : SM(SM) {}
373
374    bool operator()(const std::pair<NamedDecl *, SourceLocation> &l,
375                    const std::pair<NamedDecl *, SourceLocation> &r) const {
376      if (l.second.isValid() && !r.second.isValid())
377        return true;
378      if (!l.second.isValid() && r.second.isValid())
379        return false;
380      if (l.second != r.second)
381        return SM.isBeforeInTranslationUnit(l.second, r.second);
382      return SM.isBeforeInTranslationUnit(l.first->getLocation(),
383                                          r.first->getLocation());
384    }
385  };
386}
387
388/// Obtains a sorted list of functions that are undefined but ODR-used.
389void Sema::getUndefinedButUsed(
390    SmallVectorImpl<std::pair<NamedDecl *, SourceLocation> > &Undefined) {
391  for (llvm::DenseMap<NamedDecl *, SourceLocation>::iterator
392         I = UndefinedButUsed.begin(), E = UndefinedButUsed.end();
393       I != E; ++I) {
394    NamedDecl *ND = I->first;
395
396    // Ignore attributes that have become invalid.
397    if (ND->isInvalidDecl()) continue;
398
399    // __attribute__((weakref)) is basically a definition.
400    if (ND->hasAttr<WeakRefAttr>()) continue;
401
402    if (FunctionDecl *FD = dyn_cast<FunctionDecl>(ND)) {
403      if (FD->isDefined())
404        continue;
405      if (FD->hasExternalLinkage() &&
406          !FD->getMostRecentDecl()->isInlined())
407        continue;
408    } else {
409      if (cast<VarDecl>(ND)->hasDefinition() != VarDecl::DeclarationOnly)
410        continue;
411      if (ND->hasExternalLinkage())
412        continue;
413    }
414
415    Undefined.push_back(std::make_pair(ND, I->second));
416  }
417
418  // Sort (in order of use site) so that we're not dependent on the iteration
419  // order through an llvm::DenseMap.
420  std::sort(Undefined.begin(), Undefined.end(),
421            SortUndefinedButUsed(Context.getSourceManager()));
422}
423
424/// checkUndefinedButUsed - Check for undefined objects with internal linkage
425/// or that are inline.
426static void checkUndefinedButUsed(Sema &S) {
427  if (S.UndefinedButUsed.empty()) return;
428
429  // Collect all the still-undefined entities with internal linkage.
430  SmallVector<std::pair<NamedDecl *, SourceLocation>, 16> Undefined;
431  S.getUndefinedButUsed(Undefined);
432  if (Undefined.empty()) return;
433
434  for (SmallVectorImpl<std::pair<NamedDecl *, SourceLocation> >::iterator
435         I = Undefined.begin(), E = Undefined.end(); I != E; ++I) {
436    NamedDecl *ND = I->first;
437
438    if (ND->getLinkage() != ExternalLinkage) {
439      S.Diag(ND->getLocation(), diag::warn_undefined_internal)
440        << isa<VarDecl>(ND) << ND;
441    } else {
442      assert(cast<FunctionDecl>(ND)->getMostRecentDecl()->isInlined() &&
443             "used object requires definition but isn't inline or internal?");
444      S.Diag(ND->getLocation(), diag::warn_undefined_inline) << ND;
445    }
446    if (I->second.isValid())
447      S.Diag(I->second, diag::note_used_here);
448  }
449}
450
451void Sema::LoadExternalWeakUndeclaredIdentifiers() {
452  if (!ExternalSource)
453    return;
454
455  SmallVector<std::pair<IdentifierInfo *, WeakInfo>, 4> WeakIDs;
456  ExternalSource->ReadWeakUndeclaredIdentifiers(WeakIDs);
457  for (unsigned I = 0, N = WeakIDs.size(); I != N; ++I) {
458    llvm::DenseMap<IdentifierInfo*,WeakInfo>::iterator Pos
459      = WeakUndeclaredIdentifiers.find(WeakIDs[I].first);
460    if (Pos != WeakUndeclaredIdentifiers.end())
461      continue;
462
463    WeakUndeclaredIdentifiers.insert(WeakIDs[I]);
464  }
465}
466
467
468typedef llvm::DenseMap<const CXXRecordDecl*, bool> RecordCompleteMap;
469
470/// \brief Returns true, if all methods and nested classes of the given
471/// CXXRecordDecl are defined in this translation unit.
472///
473/// Should only be called from ActOnEndOfTranslationUnit so that all
474/// definitions are actually read.
475static bool MethodsAndNestedClassesComplete(const CXXRecordDecl *RD,
476                                            RecordCompleteMap &MNCComplete) {
477  RecordCompleteMap::iterator Cache = MNCComplete.find(RD);
478  if (Cache != MNCComplete.end())
479    return Cache->second;
480  if (!RD->isCompleteDefinition())
481    return false;
482  bool Complete = true;
483  for (DeclContext::decl_iterator I = RD->decls_begin(),
484                                  E = RD->decls_end();
485       I != E && Complete; ++I) {
486    if (const CXXMethodDecl *M = dyn_cast<CXXMethodDecl>(*I))
487      Complete = M->isDefined() || (M->isPure() && !isa<CXXDestructorDecl>(M));
488    else if (const FunctionTemplateDecl *F = dyn_cast<FunctionTemplateDecl>(*I))
489      Complete = F->getTemplatedDecl()->isDefined();
490    else if (const CXXRecordDecl *R = dyn_cast<CXXRecordDecl>(*I)) {
491      if (R->isInjectedClassName())
492        continue;
493      if (R->hasDefinition())
494        Complete = MethodsAndNestedClassesComplete(R->getDefinition(),
495                                                   MNCComplete);
496      else
497        Complete = false;
498    }
499  }
500  MNCComplete[RD] = Complete;
501  return Complete;
502}
503
504/// \brief Returns true, if the given CXXRecordDecl is fully defined in this
505/// translation unit, i.e. all methods are defined or pure virtual and all
506/// friends, friend functions and nested classes are fully defined in this
507/// translation unit.
508///
509/// Should only be called from ActOnEndOfTranslationUnit so that all
510/// definitions are actually read.
511static bool IsRecordFullyDefined(const CXXRecordDecl *RD,
512                                 RecordCompleteMap &RecordsComplete,
513                                 RecordCompleteMap &MNCComplete) {
514  RecordCompleteMap::iterator Cache = RecordsComplete.find(RD);
515  if (Cache != RecordsComplete.end())
516    return Cache->second;
517  bool Complete = MethodsAndNestedClassesComplete(RD, MNCComplete);
518  for (CXXRecordDecl::friend_iterator I = RD->friend_begin(),
519                                      E = RD->friend_end();
520       I != E && Complete; ++I) {
521    // Check if friend classes and methods are complete.
522    if (TypeSourceInfo *TSI = (*I)->getFriendType()) {
523      // Friend classes are available as the TypeSourceInfo of the FriendDecl.
524      if (CXXRecordDecl *FriendD = TSI->getType()->getAsCXXRecordDecl())
525        Complete = MethodsAndNestedClassesComplete(FriendD, MNCComplete);
526      else
527        Complete = false;
528    } else {
529      // Friend functions are available through the NamedDecl of FriendDecl.
530      if (const FunctionDecl *FD =
531          dyn_cast<FunctionDecl>((*I)->getFriendDecl()))
532        Complete = FD->isDefined();
533      else
534        // This is a template friend, give up.
535        Complete = false;
536    }
537  }
538  RecordsComplete[RD] = Complete;
539  return Complete;
540}
541
542/// ActOnEndOfTranslationUnit - This is called at the very end of the
543/// translation unit when EOF is reached and all but the top-level scope is
544/// popped.
545void Sema::ActOnEndOfTranslationUnit() {
546  assert(DelayedDiagnostics.getCurrentPool() == NULL
547         && "reached end of translation unit with a pool attached?");
548
549  // If code completion is enabled, don't perform any end-of-translation-unit
550  // work.
551  if (PP.isCodeCompletionEnabled())
552    return;
553
554  // Only complete translation units define vtables and perform implicit
555  // instantiations.
556  if (TUKind == TU_Complete) {
557    DiagnoseUseOfUnimplementedSelectors();
558
559    // If any dynamic classes have their key function defined within
560    // this translation unit, then those vtables are considered "used" and must
561    // be emitted.
562    for (DynamicClassesType::iterator I = DynamicClasses.begin(ExternalSource),
563                                      E = DynamicClasses.end();
564         I != E; ++I) {
565      assert(!(*I)->isDependentType() &&
566             "Should not see dependent types here!");
567      if (const CXXMethodDecl *KeyFunction = Context.getCurrentKeyFunction(*I)) {
568        const FunctionDecl *Definition = 0;
569        if (KeyFunction->hasBody(Definition))
570          MarkVTableUsed(Definition->getLocation(), *I, true);
571      }
572    }
573
574    // If DefinedUsedVTables ends up marking any virtual member functions it
575    // might lead to more pending template instantiations, which we then need
576    // to instantiate.
577    DefineUsedVTables();
578
579    // C++: Perform implicit template instantiations.
580    //
581    // FIXME: When we perform these implicit instantiations, we do not
582    // carefully keep track of the point of instantiation (C++ [temp.point]).
583    // This means that name lookup that occurs within the template
584    // instantiation will always happen at the end of the translation unit,
585    // so it will find some names that should not be found. Although this is
586    // common behavior for C++ compilers, it is technically wrong. In the
587    // future, we either need to be able to filter the results of name lookup
588    // or we need to perform template instantiations earlier.
589    PerformPendingInstantiations();
590  }
591
592  // Remove file scoped decls that turned out to be used.
593  UnusedFileScopedDecls.erase(std::remove_if(UnusedFileScopedDecls.begin(0,
594                                                                         true),
595                                             UnusedFileScopedDecls.end(),
596                              std::bind1st(std::ptr_fun(ShouldRemoveFromUnused),
597                                           this)),
598                              UnusedFileScopedDecls.end());
599
600  if (TUKind == TU_Prefix) {
601    // Translation unit prefixes don't need any of the checking below.
602    TUScope = 0;
603    return;
604  }
605
606  // Check for #pragma weak identifiers that were never declared
607  // FIXME: This will cause diagnostics to be emitted in a non-determinstic
608  // order!  Iterating over a densemap like this is bad.
609  LoadExternalWeakUndeclaredIdentifiers();
610  for (llvm::DenseMap<IdentifierInfo*,WeakInfo>::iterator
611       I = WeakUndeclaredIdentifiers.begin(),
612       E = WeakUndeclaredIdentifiers.end(); I != E; ++I) {
613    if (I->second.getUsed()) continue;
614
615    Diag(I->second.getLocation(), diag::warn_weak_identifier_undeclared)
616      << I->first;
617  }
618
619  if (LangOpts.CPlusPlus11 &&
620      Diags.getDiagnosticLevel(diag::warn_delegating_ctor_cycle,
621                               SourceLocation())
622        != DiagnosticsEngine::Ignored)
623    CheckDelegatingCtorCycles();
624
625  if (TUKind == TU_Module) {
626    // If we are building a module, resolve all of the exported declarations
627    // now.
628    if (Module *CurrentModule = PP.getCurrentModule()) {
629      ModuleMap &ModMap = PP.getHeaderSearchInfo().getModuleMap();
630
631      SmallVector<Module *, 2> Stack;
632      Stack.push_back(CurrentModule);
633      while (!Stack.empty()) {
634        Module *Mod = Stack.back();
635        Stack.pop_back();
636
637        // Resolve the exported declarations and conflicts.
638        // FIXME: Actually complain, once we figure out how to teach the
639        // diagnostic client to deal with complaints in the module map at this
640        // point.
641        ModMap.resolveExports(Mod, /*Complain=*/false);
642        ModMap.resolveConflicts(Mod, /*Complain=*/false);
643
644        // Queue the submodules, so their exports will also be resolved.
645        for (Module::submodule_iterator Sub = Mod->submodule_begin(),
646                                     SubEnd = Mod->submodule_end();
647             Sub != SubEnd; ++Sub) {
648          Stack.push_back(*Sub);
649        }
650      }
651    }
652
653    // Modules don't need any of the checking below.
654    TUScope = 0;
655    return;
656  }
657
658  // C99 6.9.2p2:
659  //   A declaration of an identifier for an object that has file
660  //   scope without an initializer, and without a storage-class
661  //   specifier or with the storage-class specifier static,
662  //   constitutes a tentative definition. If a translation unit
663  //   contains one or more tentative definitions for an identifier,
664  //   and the translation unit contains no external definition for
665  //   that identifier, then the behavior is exactly as if the
666  //   translation unit contains a file scope declaration of that
667  //   identifier, with the composite type as of the end of the
668  //   translation unit, with an initializer equal to 0.
669  llvm::SmallSet<VarDecl *, 32> Seen;
670  for (TentativeDefinitionsType::iterator
671            T = TentativeDefinitions.begin(ExternalSource),
672         TEnd = TentativeDefinitions.end();
673       T != TEnd; ++T)
674  {
675    VarDecl *VD = (*T)->getActingDefinition();
676
677    // If the tentative definition was completed, getActingDefinition() returns
678    // null. If we've already seen this variable before, insert()'s second
679    // return value is false.
680    if (VD == 0 || VD->isInvalidDecl() || !Seen.insert(VD))
681      continue;
682
683    if (const IncompleteArrayType *ArrayT
684        = Context.getAsIncompleteArrayType(VD->getType())) {
685      if (RequireCompleteType(VD->getLocation(),
686                              ArrayT->getElementType(),
687                              diag::err_tentative_def_incomplete_type_arr)) {
688        VD->setInvalidDecl();
689        continue;
690      }
691
692      // Set the length of the array to 1 (C99 6.9.2p5).
693      Diag(VD->getLocation(), diag::warn_tentative_incomplete_array);
694      llvm::APInt One(Context.getTypeSize(Context.getSizeType()), true);
695      QualType T = Context.getConstantArrayType(ArrayT->getElementType(),
696                                                One, ArrayType::Normal, 0);
697      VD->setType(T);
698    } else if (RequireCompleteType(VD->getLocation(), VD->getType(),
699                                   diag::err_tentative_def_incomplete_type))
700      VD->setInvalidDecl();
701
702    CheckCompleteVariableDeclaration(VD);
703
704    // Notify the consumer that we've completed a tentative definition.
705    if (!VD->isInvalidDecl())
706      Consumer.CompleteTentativeDefinition(VD);
707
708  }
709
710  // If there were errors, disable 'unused' warnings since they will mostly be
711  // noise.
712  if (!Diags.hasErrorOccurred()) {
713    // Output warning for unused file scoped decls.
714    for (UnusedFileScopedDeclsType::iterator
715           I = UnusedFileScopedDecls.begin(ExternalSource),
716           E = UnusedFileScopedDecls.end(); I != E; ++I) {
717      if (ShouldRemoveFromUnused(this, *I))
718        continue;
719
720      if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(*I)) {
721        const FunctionDecl *DiagD;
722        if (!FD->hasBody(DiagD))
723          DiagD = FD;
724        if (DiagD->isDeleted())
725          continue; // Deleted functions are supposed to be unused.
726        if (DiagD->isReferenced()) {
727          if (isa<CXXMethodDecl>(DiagD))
728            Diag(DiagD->getLocation(), diag::warn_unneeded_member_function)
729                  << DiagD->getDeclName();
730          else {
731            if (FD->getStorageClass() == SC_Static &&
732                !FD->isInlineSpecified() &&
733                !SourceMgr.isFromMainFile(
734                   SourceMgr.getExpansionLoc(FD->getLocation())))
735              Diag(DiagD->getLocation(), diag::warn_unneeded_static_internal_decl)
736                << DiagD->getDeclName();
737            else
738              Diag(DiagD->getLocation(), diag::warn_unneeded_internal_decl)
739                   << /*function*/0 << DiagD->getDeclName();
740          }
741        } else {
742          Diag(DiagD->getLocation(),
743               isa<CXXMethodDecl>(DiagD) ? diag::warn_unused_member_function
744                                         : diag::warn_unused_function)
745                << DiagD->getDeclName();
746        }
747      } else {
748        const VarDecl *DiagD = cast<VarDecl>(*I)->getDefinition();
749        if (!DiagD)
750          DiagD = cast<VarDecl>(*I);
751        if (DiagD->isReferenced()) {
752          Diag(DiagD->getLocation(), diag::warn_unneeded_internal_decl)
753                << /*variable*/1 << DiagD->getDeclName();
754        } else if (getSourceManager().isFromMainFile(DiagD->getLocation())) {
755          // If the declaration is in a header which is included into multiple
756          // TUs, it will declare one variable per TU, and one of the other
757          // variables may be used. So, only warn if the declaration is in the
758          // main file.
759          Diag(DiagD->getLocation(), diag::warn_unused_variable)
760              << DiagD->getDeclName();
761        }
762      }
763    }
764
765    if (ExternalSource)
766      ExternalSource->ReadUndefinedButUsed(UndefinedButUsed);
767    checkUndefinedButUsed(*this);
768  }
769
770  if (Diags.getDiagnosticLevel(diag::warn_unused_private_field,
771                               SourceLocation())
772        != DiagnosticsEngine::Ignored) {
773    RecordCompleteMap RecordsComplete;
774    RecordCompleteMap MNCComplete;
775    for (NamedDeclSetType::iterator I = UnusedPrivateFields.begin(),
776         E = UnusedPrivateFields.end(); I != E; ++I) {
777      const NamedDecl *D = *I;
778      const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(D->getDeclContext());
779      if (RD && !RD->isUnion() &&
780          IsRecordFullyDefined(RD, RecordsComplete, MNCComplete)) {
781        Diag(D->getLocation(), diag::warn_unused_private_field)
782              << D->getDeclName();
783      }
784    }
785  }
786
787  // Check we've noticed that we're no longer parsing the initializer for every
788  // variable. If we miss cases, then at best we have a performance issue and
789  // at worst a rejects-valid bug.
790  assert(ParsingInitForAutoVars.empty() &&
791         "Didn't unmark var as having its initializer parsed");
792
793  TUScope = 0;
794}
795
796
797//===----------------------------------------------------------------------===//
798// Helper functions.
799//===----------------------------------------------------------------------===//
800
801DeclContext *Sema::getFunctionLevelDeclContext() {
802  DeclContext *DC = CurContext;
803
804  while (true) {
805    if (isa<BlockDecl>(DC) || isa<EnumDecl>(DC)) {
806      DC = DC->getParent();
807    } else if (isa<CXXMethodDecl>(DC) &&
808               cast<CXXMethodDecl>(DC)->getOverloadedOperator() == OO_Call &&
809               cast<CXXRecordDecl>(DC->getParent())->isLambda()) {
810      DC = DC->getParent()->getParent();
811    }
812    else break;
813  }
814
815  return DC;
816}
817
818/// getCurFunctionDecl - If inside of a function body, this returns a pointer
819/// to the function decl for the function being parsed.  If we're currently
820/// in a 'block', this returns the containing context.
821FunctionDecl *Sema::getCurFunctionDecl() {
822  DeclContext *DC = getFunctionLevelDeclContext();
823  return dyn_cast<FunctionDecl>(DC);
824}
825
826ObjCMethodDecl *Sema::getCurMethodDecl() {
827  DeclContext *DC = getFunctionLevelDeclContext();
828  return dyn_cast<ObjCMethodDecl>(DC);
829}
830
831NamedDecl *Sema::getCurFunctionOrMethodDecl() {
832  DeclContext *DC = getFunctionLevelDeclContext();
833  if (isa<ObjCMethodDecl>(DC) || isa<FunctionDecl>(DC))
834    return cast<NamedDecl>(DC);
835  return 0;
836}
837
838void Sema::EmitCurrentDiagnostic(unsigned DiagID) {
839  // FIXME: It doesn't make sense to me that DiagID is an incoming argument here
840  // and yet we also use the current diag ID on the DiagnosticsEngine. This has
841  // been made more painfully obvious by the refactor that introduced this
842  // function, but it is possible that the incoming argument can be
843  // eliminnated. If it truly cannot be (for example, there is some reentrancy
844  // issue I am not seeing yet), then there should at least be a clarifying
845  // comment somewhere.
846  if (Optional<TemplateDeductionInfo*> Info = isSFINAEContext()) {
847    switch (DiagnosticIDs::getDiagnosticSFINAEResponse(
848              Diags.getCurrentDiagID())) {
849    case DiagnosticIDs::SFINAE_Report:
850      // We'll report the diagnostic below.
851      break;
852
853    case DiagnosticIDs::SFINAE_SubstitutionFailure:
854      // Count this failure so that we know that template argument deduction
855      // has failed.
856      ++NumSFINAEErrors;
857
858      // Make a copy of this suppressed diagnostic and store it with the
859      // template-deduction information.
860      if (*Info && !(*Info)->hasSFINAEDiagnostic()) {
861        Diagnostic DiagInfo(&Diags);
862        (*Info)->addSFINAEDiagnostic(DiagInfo.getLocation(),
863                       PartialDiagnostic(DiagInfo, Context.getDiagAllocator()));
864      }
865
866      Diags.setLastDiagnosticIgnored();
867      Diags.Clear();
868      return;
869
870    case DiagnosticIDs::SFINAE_AccessControl: {
871      // Per C++ Core Issue 1170, access control is part of SFINAE.
872      // Additionally, the AccessCheckingSFINAE flag can be used to temporarily
873      // make access control a part of SFINAE for the purposes of checking
874      // type traits.
875      if (!AccessCheckingSFINAE && !getLangOpts().CPlusPlus11)
876        break;
877
878      SourceLocation Loc = Diags.getCurrentDiagLoc();
879
880      // Suppress this diagnostic.
881      ++NumSFINAEErrors;
882
883      // Make a copy of this suppressed diagnostic and store it with the
884      // template-deduction information.
885      if (*Info && !(*Info)->hasSFINAEDiagnostic()) {
886        Diagnostic DiagInfo(&Diags);
887        (*Info)->addSFINAEDiagnostic(DiagInfo.getLocation(),
888                       PartialDiagnostic(DiagInfo, Context.getDiagAllocator()));
889      }
890
891      Diags.setLastDiagnosticIgnored();
892      Diags.Clear();
893
894      // Now the diagnostic state is clear, produce a C++98 compatibility
895      // warning.
896      Diag(Loc, diag::warn_cxx98_compat_sfinae_access_control);
897
898      // The last diagnostic which Sema produced was ignored. Suppress any
899      // notes attached to it.
900      Diags.setLastDiagnosticIgnored();
901      return;
902    }
903
904    case DiagnosticIDs::SFINAE_Suppress:
905      // Make a copy of this suppressed diagnostic and store it with the
906      // template-deduction information;
907      if (*Info) {
908        Diagnostic DiagInfo(&Diags);
909        (*Info)->addSuppressedDiagnostic(DiagInfo.getLocation(),
910                       PartialDiagnostic(DiagInfo, Context.getDiagAllocator()));
911      }
912
913      // Suppress this diagnostic.
914      Diags.setLastDiagnosticIgnored();
915      Diags.Clear();
916      return;
917    }
918  }
919
920  // Set up the context's printing policy based on our current state.
921  Context.setPrintingPolicy(getPrintingPolicy());
922
923  // Emit the diagnostic.
924  if (!Diags.EmitCurrentDiagnostic())
925    return;
926
927  // If this is not a note, and we're in a template instantiation
928  // that is different from the last template instantiation where
929  // we emitted an error, print a template instantiation
930  // backtrace.
931  if (!DiagnosticIDs::isBuiltinNote(DiagID) &&
932      !ActiveTemplateInstantiations.empty() &&
933      ActiveTemplateInstantiations.back()
934        != LastTemplateInstantiationErrorContext) {
935    PrintInstantiationStack();
936    LastTemplateInstantiationErrorContext = ActiveTemplateInstantiations.back();
937  }
938}
939
940Sema::SemaDiagnosticBuilder
941Sema::Diag(SourceLocation Loc, const PartialDiagnostic& PD) {
942  SemaDiagnosticBuilder Builder(Diag(Loc, PD.getDiagID()));
943  PD.Emit(Builder);
944
945  return Builder;
946}
947
948/// \brief Looks through the macro-expansion chain for the given
949/// location, looking for a macro expansion with the given name.
950/// If one is found, returns true and sets the location to that
951/// expansion loc.
952bool Sema::findMacroSpelling(SourceLocation &locref, StringRef name) {
953  SourceLocation loc = locref;
954  if (!loc.isMacroID()) return false;
955
956  // There's no good way right now to look at the intermediate
957  // expansions, so just jump to the expansion location.
958  loc = getSourceManager().getExpansionLoc(loc);
959
960  // If that's written with the name, stop here.
961  SmallVector<char, 16> buffer;
962  if (getPreprocessor().getSpelling(loc, buffer) == name) {
963    locref = loc;
964    return true;
965  }
966  return false;
967}
968
969/// \brief Determines the active Scope associated with the given declaration
970/// context.
971///
972/// This routine maps a declaration context to the active Scope object that
973/// represents that declaration context in the parser. It is typically used
974/// from "scope-less" code (e.g., template instantiation, lazy creation of
975/// declarations) that injects a name for name-lookup purposes and, therefore,
976/// must update the Scope.
977///
978/// \returns The scope corresponding to the given declaraion context, or NULL
979/// if no such scope is open.
980Scope *Sema::getScopeForContext(DeclContext *Ctx) {
981
982  if (!Ctx)
983    return 0;
984
985  Ctx = Ctx->getPrimaryContext();
986  for (Scope *S = getCurScope(); S; S = S->getParent()) {
987    // Ignore scopes that cannot have declarations. This is important for
988    // out-of-line definitions of static class members.
989    if (S->getFlags() & (Scope::DeclScope | Scope::TemplateParamScope))
990      if (DeclContext *Entity = static_cast<DeclContext *> (S->getEntity()))
991        if (Ctx == Entity->getPrimaryContext())
992          return S;
993  }
994
995  return 0;
996}
997
998/// \brief Enter a new function scope
999void Sema::PushFunctionScope() {
1000  if (FunctionScopes.size() == 1) {
1001    // Use the "top" function scope rather than having to allocate
1002    // memory for a new scope.
1003    FunctionScopes.back()->Clear();
1004    FunctionScopes.push_back(FunctionScopes.back());
1005    return;
1006  }
1007
1008  FunctionScopes.push_back(new FunctionScopeInfo(getDiagnostics()));
1009}
1010
1011void Sema::PushBlockScope(Scope *BlockScope, BlockDecl *Block) {
1012  FunctionScopes.push_back(new BlockScopeInfo(getDiagnostics(),
1013                                              BlockScope, Block));
1014}
1015
1016void Sema::PushLambdaScope(CXXRecordDecl *Lambda,
1017                           CXXMethodDecl *CallOperator) {
1018  FunctionScopes.push_back(new LambdaScopeInfo(getDiagnostics(), Lambda,
1019                                               CallOperator));
1020}
1021
1022void Sema::PopFunctionScopeInfo(const AnalysisBasedWarnings::Policy *WP,
1023                                const Decl *D, const BlockExpr *blkExpr) {
1024  FunctionScopeInfo *Scope = FunctionScopes.pop_back_val();
1025  assert(!FunctionScopes.empty() && "mismatched push/pop!");
1026
1027  // Issue any analysis-based warnings.
1028  if (WP && D)
1029    AnalysisWarnings.IssueWarnings(*WP, Scope, D, blkExpr);
1030  else {
1031    for (SmallVectorImpl<sema::PossiblyUnreachableDiag>::iterator
1032         i = Scope->PossiblyUnreachableDiags.begin(),
1033         e = Scope->PossiblyUnreachableDiags.end();
1034         i != e; ++i) {
1035      const sema::PossiblyUnreachableDiag &D = *i;
1036      Diag(D.Loc, D.PD);
1037    }
1038  }
1039
1040  if (FunctionScopes.back() != Scope) {
1041    delete Scope;
1042  }
1043}
1044
1045void Sema::PushCompoundScope() {
1046  getCurFunction()->CompoundScopes.push_back(CompoundScopeInfo());
1047}
1048
1049void Sema::PopCompoundScope() {
1050  FunctionScopeInfo *CurFunction = getCurFunction();
1051  assert(!CurFunction->CompoundScopes.empty() && "mismatched push/pop");
1052
1053  CurFunction->CompoundScopes.pop_back();
1054}
1055
1056/// \brief Determine whether any errors occurred within this function/method/
1057/// block.
1058bool Sema::hasAnyUnrecoverableErrorsInThisFunction() const {
1059  return getCurFunction()->ErrorTrap.hasUnrecoverableErrorOccurred();
1060}
1061
1062BlockScopeInfo *Sema::getCurBlock() {
1063  if (FunctionScopes.empty())
1064    return 0;
1065
1066  return dyn_cast<BlockScopeInfo>(FunctionScopes.back());
1067}
1068
1069LambdaScopeInfo *Sema::getCurLambda() {
1070  if (FunctionScopes.empty())
1071    return 0;
1072
1073  return dyn_cast<LambdaScopeInfo>(FunctionScopes.back());
1074}
1075
1076void Sema::ActOnComment(SourceRange Comment) {
1077  if (!LangOpts.RetainCommentsFromSystemHeaders &&
1078      SourceMgr.isInSystemHeader(Comment.getBegin()))
1079    return;
1080  RawComment RC(SourceMgr, Comment, false,
1081                LangOpts.CommentOpts.ParseAllComments);
1082  if (RC.isAlmostTrailingComment()) {
1083    SourceRange MagicMarkerRange(Comment.getBegin(),
1084                                 Comment.getBegin().getLocWithOffset(3));
1085    StringRef MagicMarkerText;
1086    switch (RC.getKind()) {
1087    case RawComment::RCK_OrdinaryBCPL:
1088      MagicMarkerText = "///<";
1089      break;
1090    case RawComment::RCK_OrdinaryC:
1091      MagicMarkerText = "/**<";
1092      break;
1093    default:
1094      llvm_unreachable("if this is an almost Doxygen comment, "
1095                       "it should be ordinary");
1096    }
1097    Diag(Comment.getBegin(), diag::warn_not_a_doxygen_trailing_member_comment) <<
1098      FixItHint::CreateReplacement(MagicMarkerRange, MagicMarkerText);
1099  }
1100  Context.addComment(RC);
1101}
1102
1103// Pin this vtable to this file.
1104ExternalSemaSource::~ExternalSemaSource() {}
1105
1106void ExternalSemaSource::ReadMethodPool(Selector Sel) { }
1107
1108void ExternalSemaSource::ReadKnownNamespaces(
1109                           SmallVectorImpl<NamespaceDecl *> &Namespaces) {
1110}
1111
1112void ExternalSemaSource::ReadUndefinedButUsed(
1113                       llvm::DenseMap<NamedDecl *, SourceLocation> &Undefined) {
1114}
1115
1116void PrettyDeclStackTraceEntry::print(raw_ostream &OS) const {
1117  SourceLocation Loc = this->Loc;
1118  if (!Loc.isValid() && TheDecl) Loc = TheDecl->getLocation();
1119  if (Loc.isValid()) {
1120    Loc.print(OS, S.getSourceManager());
1121    OS << ": ";
1122  }
1123  OS << Message;
1124
1125  if (TheDecl && isa<NamedDecl>(TheDecl)) {
1126    std::string Name = cast<NamedDecl>(TheDecl)->getNameAsString();
1127    if (!Name.empty())
1128      OS << " '" << Name << '\'';
1129  }
1130
1131  OS << '\n';
1132}
1133
1134/// \brief Figure out if an expression could be turned into a call.
1135///
1136/// Use this when trying to recover from an error where the programmer may have
1137/// written just the name of a function instead of actually calling it.
1138///
1139/// \param E - The expression to examine.
1140/// \param ZeroArgCallReturnTy - If the expression can be turned into a call
1141///  with no arguments, this parameter is set to the type returned by such a
1142///  call; otherwise, it is set to an empty QualType.
1143/// \param OverloadSet - If the expression is an overloaded function
1144///  name, this parameter is populated with the decls of the various overloads.
1145bool Sema::isExprCallable(const Expr &E, QualType &ZeroArgCallReturnTy,
1146                          UnresolvedSetImpl &OverloadSet) {
1147  ZeroArgCallReturnTy = QualType();
1148  OverloadSet.clear();
1149
1150  if (E.getType() == Context.OverloadTy) {
1151    OverloadExpr::FindResult FR = OverloadExpr::find(const_cast<Expr*>(&E));
1152    const OverloadExpr *Overloads = FR.Expression;
1153
1154    for (OverloadExpr::decls_iterator it = Overloads->decls_begin(),
1155         DeclsEnd = Overloads->decls_end(); it != DeclsEnd; ++it) {
1156      OverloadSet.addDecl(*it);
1157
1158      // Check whether the function is a non-template which takes no
1159      // arguments.
1160      if (const FunctionDecl *OverloadDecl
1161            = dyn_cast<FunctionDecl>((*it)->getUnderlyingDecl())) {
1162        if (OverloadDecl->getMinRequiredArguments() == 0)
1163          ZeroArgCallReturnTy = OverloadDecl->getResultType();
1164      }
1165    }
1166
1167    // Ignore overloads that are pointer-to-member constants.
1168    if (FR.HasFormOfMemberPointer)
1169      return false;
1170
1171    return true;
1172  }
1173
1174  if (const DeclRefExpr *DeclRef = dyn_cast<DeclRefExpr>(E.IgnoreParens())) {
1175    if (const FunctionDecl *Fun = dyn_cast<FunctionDecl>(DeclRef->getDecl())) {
1176      if (Fun->getMinRequiredArguments() == 0)
1177        ZeroArgCallReturnTy = Fun->getResultType();
1178      return true;
1179    }
1180  }
1181
1182  // We don't have an expression that's convenient to get a FunctionDecl from,
1183  // but we can at least check if the type is "function of 0 arguments".
1184  QualType ExprTy = E.getType();
1185  const FunctionType *FunTy = NULL;
1186  QualType PointeeTy = ExprTy->getPointeeType();
1187  if (!PointeeTy.isNull())
1188    FunTy = PointeeTy->getAs<FunctionType>();
1189  if (!FunTy)
1190    FunTy = ExprTy->getAs<FunctionType>();
1191  if (!FunTy && ExprTy == Context.BoundMemberTy) {
1192    // Look for the bound-member type.  If it's still overloaded, give up,
1193    // although we probably should have fallen into the OverloadExpr case above
1194    // if we actually have an overloaded bound member.
1195    QualType BoundMemberTy = Expr::findBoundMemberType(&E);
1196    if (!BoundMemberTy.isNull())
1197      FunTy = BoundMemberTy->castAs<FunctionType>();
1198  }
1199
1200  if (const FunctionProtoType *FPT =
1201      dyn_cast_or_null<FunctionProtoType>(FunTy)) {
1202    if (FPT->getNumArgs() == 0)
1203      ZeroArgCallReturnTy = FunTy->getResultType();
1204    return true;
1205  }
1206  return false;
1207}
1208
1209/// \brief Give notes for a set of overloads.
1210///
1211/// A companion to isExprCallable. In cases when the name that the programmer
1212/// wrote was an overloaded function, we may be able to make some guesses about
1213/// plausible overloads based on their return types; such guesses can be handed
1214/// off to this method to be emitted as notes.
1215///
1216/// \param Overloads - The overloads to note.
1217/// \param FinalNoteLoc - If we've suppressed printing some overloads due to
1218///  -fshow-overloads=best, this is the location to attach to the note about too
1219///  many candidates. Typically this will be the location of the original
1220///  ill-formed expression.
1221static void noteOverloads(Sema &S, const UnresolvedSetImpl &Overloads,
1222                          const SourceLocation FinalNoteLoc) {
1223  int ShownOverloads = 0;
1224  int SuppressedOverloads = 0;
1225  for (UnresolvedSetImpl::iterator It = Overloads.begin(),
1226       DeclsEnd = Overloads.end(); It != DeclsEnd; ++It) {
1227    // FIXME: Magic number for max shown overloads stolen from
1228    // OverloadCandidateSet::NoteCandidates.
1229    if (ShownOverloads >= 4 && S.Diags.getShowOverloads() == Ovl_Best) {
1230      ++SuppressedOverloads;
1231      continue;
1232    }
1233
1234    NamedDecl *Fn = (*It)->getUnderlyingDecl();
1235    S.Diag(Fn->getLocation(), diag::note_possible_target_of_call);
1236    ++ShownOverloads;
1237  }
1238
1239  if (SuppressedOverloads)
1240    S.Diag(FinalNoteLoc, diag::note_ovl_too_many_candidates)
1241      << SuppressedOverloads;
1242}
1243
1244static void notePlausibleOverloads(Sema &S, SourceLocation Loc,
1245                                   const UnresolvedSetImpl &Overloads,
1246                                   bool (*IsPlausibleResult)(QualType)) {
1247  if (!IsPlausibleResult)
1248    return noteOverloads(S, Overloads, Loc);
1249
1250  UnresolvedSet<2> PlausibleOverloads;
1251  for (OverloadExpr::decls_iterator It = Overloads.begin(),
1252         DeclsEnd = Overloads.end(); It != DeclsEnd; ++It) {
1253    const FunctionDecl *OverloadDecl = cast<FunctionDecl>(*It);
1254    QualType OverloadResultTy = OverloadDecl->getResultType();
1255    if (IsPlausibleResult(OverloadResultTy))
1256      PlausibleOverloads.addDecl(It.getDecl());
1257  }
1258  noteOverloads(S, PlausibleOverloads, Loc);
1259}
1260
1261/// Determine whether the given expression can be called by just
1262/// putting parentheses after it.  Notably, expressions with unary
1263/// operators can't be because the unary operator will start parsing
1264/// outside the call.
1265static bool IsCallableWithAppend(Expr *E) {
1266  E = E->IgnoreImplicit();
1267  return (!isa<CStyleCastExpr>(E) &&
1268          !isa<UnaryOperator>(E) &&
1269          !isa<BinaryOperator>(E) &&
1270          !isa<CXXOperatorCallExpr>(E));
1271}
1272
1273bool Sema::tryToRecoverWithCall(ExprResult &E, const PartialDiagnostic &PD,
1274                                bool ForceComplain,
1275                                bool (*IsPlausibleResult)(QualType)) {
1276  SourceLocation Loc = E.get()->getExprLoc();
1277  SourceRange Range = E.get()->getSourceRange();
1278
1279  QualType ZeroArgCallTy;
1280  UnresolvedSet<4> Overloads;
1281  if (isExprCallable(*E.get(), ZeroArgCallTy, Overloads) &&
1282      !ZeroArgCallTy.isNull() &&
1283      (!IsPlausibleResult || IsPlausibleResult(ZeroArgCallTy))) {
1284    // At this point, we know E is potentially callable with 0
1285    // arguments and that it returns something of a reasonable type,
1286    // so we can emit a fixit and carry on pretending that E was
1287    // actually a CallExpr.
1288    SourceLocation ParenInsertionLoc =
1289      PP.getLocForEndOfToken(Range.getEnd());
1290    Diag(Loc, PD)
1291      << /*zero-arg*/ 1 << Range
1292      << (IsCallableWithAppend(E.get())
1293          ? FixItHint::CreateInsertion(ParenInsertionLoc, "()")
1294          : FixItHint());
1295    notePlausibleOverloads(*this, Loc, Overloads, IsPlausibleResult);
1296
1297    // FIXME: Try this before emitting the fixit, and suppress diagnostics
1298    // while doing so.
1299    E = ActOnCallExpr(0, E.take(), ParenInsertionLoc,
1300                      MultiExprArg(), ParenInsertionLoc.getLocWithOffset(1));
1301    return true;
1302  }
1303
1304  if (!ForceComplain) return false;
1305
1306  Diag(Loc, PD) << /*not zero-arg*/ 0 << Range;
1307  notePlausibleOverloads(*this, Loc, Overloads, IsPlausibleResult);
1308  E = ExprError();
1309  return true;
1310}
1311
1312IdentifierInfo *Sema::getSuperIdentifier() const {
1313  if (!Ident_super)
1314    Ident_super = &Context.Idents.get("super");
1315  return Ident_super;
1316}
1317