Sema.cpp revision b9725cfb0a50731930a6331beb70f361b4d52a29 
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 (MacroInfo *BoolMacro = PP.getMacroInfo(&Context.Idents.get("bool"))) {
53      Policy.Bool = BoolMacro->isObjectLike() &&
54        BoolMacro->getNumTokens() == 1 &&
55        BoolMacro->getReplacementToken(0).is(tok::kw__Bool);
56    }
57  }
58
59  return Policy;
60}
61
62void Sema::ActOnTranslationUnitScope(Scope *S) {
63  TUScope = S;
64  PushDeclContext(S, Context.getTranslationUnitDecl());
65
66  VAListTagName = PP.getIdentifierInfo("__va_list_tag");
67}
68
69Sema::Sema(Preprocessor &pp, ASTContext &ctxt, ASTConsumer &consumer,
70           TranslationUnitKind TUKind,
71           CodeCompleteConsumer *CodeCompleter)
72  : TheTargetAttributesSema(0), ExternalSource(0),
73    isMultiplexExternalSource(false), FPFeatures(pp.getLangOpts()),
74    LangOpts(pp.getLangOpts()), PP(pp), Context(ctxt), Consumer(consumer),
75    Diags(PP.getDiagnostics()), SourceMgr(PP.getSourceManager()),
76    CollectStats(false), CodeCompleter(CodeCompleter),
77    CurContext(0), OriginalLexicalContext(0),
78    PackContext(0), MSStructPragmaOn(false), VisContext(0),
79    IsBuildingRecoveryCallExpr(false),
80    ExprNeedsCleanups(false), LateTemplateParser(0), OpaqueParser(0),
81    IdResolver(pp), StdInitializerList(0), CXXTypeInfoDecl(0), MSVCGuidDecl(0),
82    NSNumberDecl(0),
83    NSStringDecl(0), StringWithUTF8StringMethod(0),
84    NSArrayDecl(0), ArrayWithObjectsMethod(0),
85    NSDictionaryDecl(0), DictionaryWithObjectsMethod(0),
86    GlobalNewDeleteDeclared(false),
87    TUKind(TUKind),
88    NumSFINAEErrors(0), InFunctionDeclarator(0),
89    AccessCheckingSFINAE(false), InNonInstantiationSFINAEContext(false),
90    NonInstantiationEntries(0), ArgumentPackSubstitutionIndex(-1),
91    CurrentInstantiationScope(0), TyposCorrected(0),
92    AnalysisWarnings(*this)
93{
94  TUScope = 0;
95
96  LoadedExternalKnownNamespaces = false;
97  for (unsigned I = 0; I != NSAPI::NumNSNumberLiteralMethods; ++I)
98    NSNumberLiteralMethods[I] = 0;
99
100  if (getLangOpts().ObjC1)
101    NSAPIObj.reset(new NSAPI(Context));
102
103  if (getLangOpts().CPlusPlus)
104    FieldCollector.reset(new CXXFieldCollector());
105
106  // Tell diagnostics how to render things from the AST library.
107  PP.getDiagnostics().SetArgToStringFn(&FormatASTNodeDiagnosticArgument,
108                                       &Context);
109
110  ExprEvalContexts.push_back(
111        ExpressionEvaluationContextRecord(PotentiallyEvaluated, 0,
112                                          false, 0, false));
113
114  FunctionScopes.push_back(new FunctionScopeInfo(Diags));
115}
116
117void Sema::Initialize() {
118  // Tell the AST consumer about this Sema object.
119  Consumer.Initialize(Context);
120
121  // FIXME: Isn't this redundant with the initialization above?
122  if (SemaConsumer *SC = dyn_cast<SemaConsumer>(&Consumer))
123    SC->InitializeSema(*this);
124
125  // Tell the external Sema source about this Sema object.
126  if (ExternalSemaSource *ExternalSema
127      = dyn_cast_or_null<ExternalSemaSource>(Context.getExternalSource()))
128    ExternalSema->InitializeSema(*this);
129
130  // Initialize predefined 128-bit integer types, if needed.
131  if (PP.getTargetInfo().hasInt128Type()) {
132    // If either of the 128-bit integer types are unavailable to name lookup,
133    // define them now.
134    DeclarationName Int128 = &Context.Idents.get("__int128_t");
135    if (IdResolver.begin(Int128) == IdResolver.end())
136      PushOnScopeChains(Context.getInt128Decl(), TUScope);
137
138    DeclarationName UInt128 = &Context.Idents.get("__uint128_t");
139    if (IdResolver.begin(UInt128) == IdResolver.end())
140      PushOnScopeChains(Context.getUInt128Decl(), TUScope);
141  }
142
143
144  // Initialize predefined Objective-C types:
145  if (PP.getLangOpts().ObjC1) {
146    // If 'SEL' does not yet refer to any declarations, make it refer to the
147    // predefined 'SEL'.
148    DeclarationName SEL = &Context.Idents.get("SEL");
149    if (IdResolver.begin(SEL) == IdResolver.end())
150      PushOnScopeChains(Context.getObjCSelDecl(), TUScope);
151
152    // If 'id' does not yet refer to any declarations, make it refer to the
153    // predefined 'id'.
154    DeclarationName Id = &Context.Idents.get("id");
155    if (IdResolver.begin(Id) == IdResolver.end())
156      PushOnScopeChains(Context.getObjCIdDecl(), TUScope);
157
158    // Create the built-in typedef for 'Class'.
159    DeclarationName Class = &Context.Idents.get("Class");
160    if (IdResolver.begin(Class) == IdResolver.end())
161      PushOnScopeChains(Context.getObjCClassDecl(), TUScope);
162
163    // Create the built-in forward declaratino for 'Protocol'.
164    DeclarationName Protocol = &Context.Idents.get("Protocol");
165    if (IdResolver.begin(Protocol) == IdResolver.end())
166      PushOnScopeChains(Context.getObjCProtocolDecl(), TUScope);
167  }
168
169  DeclarationName BuiltinVaList = &Context.Idents.get("__builtin_va_list");
170  if (IdResolver.begin(BuiltinVaList) == IdResolver.end())
171    PushOnScopeChains(Context.getBuiltinVaListDecl(), TUScope);
172}
173
174Sema::~Sema() {
175  if (PackContext) FreePackedContext();
176  if (VisContext) FreeVisContext();
177  delete TheTargetAttributesSema;
178  MSStructPragmaOn = false;
179  // Kill all the active scopes.
180  for (unsigned I = 1, E = FunctionScopes.size(); I != E; ++I)
181    delete FunctionScopes[I];
182  if (FunctionScopes.size() == 1)
183    delete FunctionScopes[0];
184
185  // Tell the SemaConsumer to forget about us; we're going out of scope.
186  if (SemaConsumer *SC = dyn_cast<SemaConsumer>(&Consumer))
187    SC->ForgetSema();
188
189  // Detach from the external Sema source.
190  if (ExternalSemaSource *ExternalSema
191        = dyn_cast_or_null<ExternalSemaSource>(Context.getExternalSource()))
192    ExternalSema->ForgetSema();
193
194  // If Sema's ExternalSource is the multiplexer - we own it.
195  if (isMultiplexExternalSource)
196    delete ExternalSource;
197}
198
199/// makeUnavailableInSystemHeader - There is an error in the current
200/// context.  If we're still in a system header, and we can plausibly
201/// make the relevant declaration unavailable instead of erroring, do
202/// so and return true.
203bool Sema::makeUnavailableInSystemHeader(SourceLocation loc,
204                                         StringRef msg) {
205  // If we're not in a function, it's an error.
206  FunctionDecl *fn = dyn_cast<FunctionDecl>(CurContext);
207  if (!fn) return false;
208
209  // If we're in template instantiation, it's an error.
210  if (!ActiveTemplateInstantiations.empty())
211    return false;
212
213  // If that function's not in a system header, it's an error.
214  if (!Context.getSourceManager().isInSystemHeader(loc))
215    return false;
216
217  // If the function is already unavailable, it's not an error.
218  if (fn->hasAttr<UnavailableAttr>()) return true;
219
220  fn->addAttr(new (Context) UnavailableAttr(loc, Context, msg));
221  return true;
222}
223
224ASTMutationListener *Sema::getASTMutationListener() const {
225  return getASTConsumer().GetASTMutationListener();
226}
227
228///\brief Registers an external source. If an external source already exists,
229/// creates a multiplex external source and appends to it.
230///
231///\param[in] E - A non-null external sema source.
232///
233void Sema::addExternalSource(ExternalSemaSource *E) {
234  assert(E && "Cannot use with NULL ptr");
235
236  if (!ExternalSource) {
237    ExternalSource = E;
238    return;
239  }
240
241  if (isMultiplexExternalSource)
242    static_cast<MultiplexExternalSemaSource*>(ExternalSource)->addSource(*E);
243  else {
244    ExternalSource = new MultiplexExternalSemaSource(*ExternalSource, *E);
245    isMultiplexExternalSource = true;
246  }
247}
248
249/// \brief Print out statistics about the semantic analysis.
250void Sema::PrintStats() const {
251  llvm::errs() << "\n*** Semantic Analysis Stats:\n";
252  llvm::errs() << NumSFINAEErrors << " SFINAE diagnostics trapped.\n";
253
254  BumpAlloc.PrintStats();
255  AnalysisWarnings.PrintStats();
256}
257
258/// ImpCastExprToType - If Expr is not of type 'Type', insert an implicit cast.
259/// If there is already an implicit cast, merge into the existing one.
260/// The result is of the given category.
261ExprResult Sema::ImpCastExprToType(Expr *E, QualType Ty,
262                                   CastKind Kind, ExprValueKind VK,
263                                   const CXXCastPath *BasePath,
264                                   CheckedConversionKind CCK) {
265#ifndef NDEBUG
266  if (VK == VK_RValue && !E->isRValue()) {
267    switch (Kind) {
268    default:
269      assert(0 && "can't implicitly cast lvalue to rvalue with this cast kind");
270    case CK_LValueToRValue:
271    case CK_ArrayToPointerDecay:
272    case CK_FunctionToPointerDecay:
273    case CK_ToVoid:
274      break;
275    }
276  }
277  assert((VK == VK_RValue || !E->isRValue()) && "can't cast rvalue to lvalue");
278#endif
279
280  QualType ExprTy = Context.getCanonicalType(E->getType());
281  QualType TypeTy = Context.getCanonicalType(Ty);
282
283  if (ExprTy == TypeTy)
284    return Owned(E);
285
286  if (getLangOpts().ObjCAutoRefCount)
287    CheckObjCARCConversion(SourceRange(), Ty, E, CCK);
288
289  // If this is a derived-to-base cast to a through a virtual base, we
290  // need a vtable.
291  if (Kind == CK_DerivedToBase &&
292      BasePathInvolvesVirtualBase(*BasePath)) {
293    QualType T = E->getType();
294    if (const PointerType *Pointer = T->getAs<PointerType>())
295      T = Pointer->getPointeeType();
296    if (const RecordType *RecordTy = T->getAs<RecordType>())
297      MarkVTableUsed(E->getLocStart(),
298                     cast<CXXRecordDecl>(RecordTy->getDecl()));
299  }
300
301  if (ImplicitCastExpr *ImpCast = dyn_cast<ImplicitCastExpr>(E)) {
302    if (ImpCast->getCastKind() == Kind && (!BasePath || BasePath->empty())) {
303      ImpCast->setType(Ty);
304      ImpCast->setValueKind(VK);
305      return Owned(E);
306    }
307  }
308
309  return Owned(ImplicitCastExpr::Create(Context, Ty, Kind, E, BasePath, VK));
310}
311
312/// ScalarTypeToBooleanCastKind - Returns the cast kind corresponding
313/// to the conversion from scalar type ScalarTy to the Boolean type.
314CastKind Sema::ScalarTypeToBooleanCastKind(QualType ScalarTy) {
315  switch (ScalarTy->getScalarTypeKind()) {
316  case Type::STK_Bool: return CK_NoOp;
317  case Type::STK_CPointer: return CK_PointerToBoolean;
318  case Type::STK_BlockPointer: return CK_PointerToBoolean;
319  case Type::STK_ObjCObjectPointer: return CK_PointerToBoolean;
320  case Type::STK_MemberPointer: return CK_MemberPointerToBoolean;
321  case Type::STK_Integral: return CK_IntegralToBoolean;
322  case Type::STK_Floating: return CK_FloatingToBoolean;
323  case Type::STK_IntegralComplex: return CK_IntegralComplexToBoolean;
324  case Type::STK_FloatingComplex: return CK_FloatingComplexToBoolean;
325  }
326  return CK_Invalid;
327}
328
329/// \brief Used to prune the decls of Sema's UnusedFileScopedDecls vector.
330static bool ShouldRemoveFromUnused(Sema *SemaRef, const DeclaratorDecl *D) {
331  if (D->getMostRecentDecl()->isUsed())
332    return true;
333
334  if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
335    // UnusedFileScopedDecls stores the first declaration.
336    // The declaration may have become definition so check again.
337    const FunctionDecl *DeclToCheck;
338    if (FD->hasBody(DeclToCheck))
339      return !SemaRef->ShouldWarnIfUnusedFileScopedDecl(DeclToCheck);
340
341    // Later redecls may add new information resulting in not having to warn,
342    // so check again.
343    DeclToCheck = FD->getMostRecentDecl();
344    if (DeclToCheck != FD)
345      return !SemaRef->ShouldWarnIfUnusedFileScopedDecl(DeclToCheck);
346  }
347
348  if (const VarDecl *VD = dyn_cast<VarDecl>(D)) {
349    // UnusedFileScopedDecls stores the first declaration.
350    // The declaration may have become definition so check again.
351    const VarDecl *DeclToCheck = VD->getDefinition();
352    if (DeclToCheck)
353      return !SemaRef->ShouldWarnIfUnusedFileScopedDecl(DeclToCheck);
354
355    // Later redecls may add new information resulting in not having to warn,
356    // so check again.
357    DeclToCheck = VD->getMostRecentDecl();
358    if (DeclToCheck != VD)
359      return !SemaRef->ShouldWarnIfUnusedFileScopedDecl(DeclToCheck);
360  }
361
362  if (D->getLinkage() == ExternalLinkage)
363    return true;
364
365  return false;
366}
367
368namespace {
369  struct UndefinedInternal {
370    NamedDecl *decl;
371    FullSourceLoc useLoc;
372
373    UndefinedInternal(NamedDecl *decl, FullSourceLoc useLoc)
374      : decl(decl), useLoc(useLoc) {}
375  };
376
377  bool operator<(const UndefinedInternal &l, const UndefinedInternal &r) {
378    return l.useLoc.isBeforeInTranslationUnitThan(r.useLoc);
379  }
380}
381
382/// checkUndefinedInternals - Check for undefined objects with internal linkage.
383static void checkUndefinedInternals(Sema &S) {
384  if (S.UndefinedInternals.empty()) return;
385
386  // Collect all the still-undefined entities with internal linkage.
387  SmallVector<UndefinedInternal, 16> undefined;
388  for (llvm::DenseMap<NamedDecl*,SourceLocation>::iterator
389         i = S.UndefinedInternals.begin(), e = S.UndefinedInternals.end();
390       i != e; ++i) {
391    NamedDecl *decl = i->first;
392
393    // Ignore attributes that have become invalid.
394    if (decl->isInvalidDecl()) continue;
395
396    // If we found out that the decl is external, don't warn.
397    if (decl->getLinkage() == ExternalLinkage) continue;
398
399    // __attribute__((weakref)) is basically a definition.
400    if (decl->hasAttr<WeakRefAttr>()) continue;
401
402    if (FunctionDecl *fn = dyn_cast<FunctionDecl>(decl)) {
403      if (fn->isPure() || fn->hasBody())
404        continue;
405    } else {
406      if (cast<VarDecl>(decl)->hasDefinition() != VarDecl::DeclarationOnly)
407        continue;
408    }
409
410    // We build a FullSourceLoc so that we can sort with array_pod_sort.
411    FullSourceLoc loc(i->second, S.Context.getSourceManager());
412    undefined.push_back(UndefinedInternal(decl, loc));
413  }
414
415  if (undefined.empty()) return;
416
417  // Sort (in order of use site) so that we're not (as) dependent on
418  // the iteration order through an llvm::DenseMap.
419  llvm::array_pod_sort(undefined.begin(), undefined.end());
420
421  for (SmallVectorImpl<UndefinedInternal>::iterator
422         i = undefined.begin(), e = undefined.end(); i != e; ++i) {
423    NamedDecl *decl = i->decl;
424    S.Diag(decl->getLocation(), diag::warn_undefined_internal)
425      << isa<VarDecl>(decl) << decl;
426    S.Diag(i->useLoc, diag::note_used_here);
427  }
428}
429
430void Sema::LoadExternalWeakUndeclaredIdentifiers() {
431  if (!ExternalSource)
432    return;
433
434  SmallVector<std::pair<IdentifierInfo *, WeakInfo>, 4> WeakIDs;
435  ExternalSource->ReadWeakUndeclaredIdentifiers(WeakIDs);
436  for (unsigned I = 0, N = WeakIDs.size(); I != N; ++I) {
437    llvm::DenseMap<IdentifierInfo*,WeakInfo>::iterator Pos
438      = WeakUndeclaredIdentifiers.find(WeakIDs[I].first);
439    if (Pos != WeakUndeclaredIdentifiers.end())
440      continue;
441
442    WeakUndeclaredIdentifiers.insert(WeakIDs[I]);
443  }
444}
445
446
447typedef llvm::DenseMap<const CXXRecordDecl*, bool> RecordCompleteMap;
448
449/// \brief Returns true, if all methods and nested classes of the given
450/// CXXRecordDecl are defined in this translation unit.
451///
452/// Should only be called from ActOnEndOfTranslationUnit so that all
453/// definitions are actually read.
454static bool MethodsAndNestedClassesComplete(const CXXRecordDecl *RD,
455                                            RecordCompleteMap &MNCComplete) {
456  RecordCompleteMap::iterator Cache = MNCComplete.find(RD);
457  if (Cache != MNCComplete.end())
458    return Cache->second;
459  if (!RD->isCompleteDefinition())
460    return false;
461  bool Complete = true;
462  for (DeclContext::decl_iterator I = RD->decls_begin(),
463                                  E = RD->decls_end();
464       I != E && Complete; ++I) {
465    if (const CXXMethodDecl *M = dyn_cast<CXXMethodDecl>(*I))
466      Complete = M->isDefined() || (M->isPure() && !isa<CXXDestructorDecl>(M));
467    else if (const FunctionTemplateDecl *F = dyn_cast<FunctionTemplateDecl>(*I))
468      Complete = F->getTemplatedDecl()->isDefined();
469    else if (const CXXRecordDecl *R = dyn_cast<CXXRecordDecl>(*I)) {
470      if (R->isInjectedClassName())
471        continue;
472      if (R->hasDefinition())
473        Complete = MethodsAndNestedClassesComplete(R->getDefinition(),
474                                                   MNCComplete);
475      else
476        Complete = false;
477    }
478  }
479  MNCComplete[RD] = Complete;
480  return Complete;
481}
482
483/// \brief Returns true, if the given CXXRecordDecl is fully defined in this
484/// translation unit, i.e. all methods are defined or pure virtual and all
485/// friends, friend functions and nested classes are fully defined in this
486/// translation unit.
487///
488/// Should only be called from ActOnEndOfTranslationUnit so that all
489/// definitions are actually read.
490static bool IsRecordFullyDefined(const CXXRecordDecl *RD,
491                                 RecordCompleteMap &RecordsComplete,
492                                 RecordCompleteMap &MNCComplete) {
493  RecordCompleteMap::iterator Cache = RecordsComplete.find(RD);
494  if (Cache != RecordsComplete.end())
495    return Cache->second;
496  bool Complete = MethodsAndNestedClassesComplete(RD, MNCComplete);
497  for (CXXRecordDecl::friend_iterator I = RD->friend_begin(),
498                                      E = RD->friend_end();
499       I != E && Complete; ++I) {
500    // Check if friend classes and methods are complete.
501    if (TypeSourceInfo *TSI = (*I)->getFriendType()) {
502      // Friend classes are available as the TypeSourceInfo of the FriendDecl.
503      if (CXXRecordDecl *FriendD = TSI->getType()->getAsCXXRecordDecl())
504        Complete = MethodsAndNestedClassesComplete(FriendD, MNCComplete);
505      else
506        Complete = false;
507    } else {
508      // Friend functions are available through the NamedDecl of FriendDecl.
509      if (const FunctionDecl *FD =
510          dyn_cast<FunctionDecl>((*I)->getFriendDecl()))
511        Complete = FD->isDefined();
512      else
513        // This is a template friend, give up.
514        Complete = false;
515    }
516  }
517  RecordsComplete[RD] = Complete;
518  return Complete;
519}
520
521/// ActOnEndOfTranslationUnit - This is called at the very end of the
522/// translation unit when EOF is reached and all but the top-level scope is
523/// popped.
524void Sema::ActOnEndOfTranslationUnit() {
525  assert(DelayedDiagnostics.getCurrentPool() == NULL
526         && "reached end of translation unit with a pool attached?");
527
528  // If code completion is enabled, don't perform any end-of-translation-unit
529  // work.
530  if (PP.isCodeCompletionEnabled())
531    return;
532
533  // Only complete translation units define vtables and perform implicit
534  // instantiations.
535  if (TUKind == TU_Complete) {
536    DiagnoseUseOfUnimplementedSelectors();
537
538    // If any dynamic classes have their key function defined within
539    // this translation unit, then those vtables are considered "used" and must
540    // be emitted.
541    for (DynamicClassesType::iterator I = DynamicClasses.begin(ExternalSource),
542                                      E = DynamicClasses.end();
543         I != E; ++I) {
544      assert(!(*I)->isDependentType() &&
545             "Should not see dependent types here!");
546      if (const CXXMethodDecl *KeyFunction = Context.getKeyFunction(*I)) {
547        const FunctionDecl *Definition = 0;
548        if (KeyFunction->hasBody(Definition))
549          MarkVTableUsed(Definition->getLocation(), *I, true);
550      }
551    }
552
553    // If DefinedUsedVTables ends up marking any virtual member functions it
554    // might lead to more pending template instantiations, which we then need
555    // to instantiate.
556    DefineUsedVTables();
557
558    // C++: Perform implicit template instantiations.
559    //
560    // FIXME: When we perform these implicit instantiations, we do not
561    // carefully keep track of the point of instantiation (C++ [temp.point]).
562    // This means that name lookup that occurs within the template
563    // instantiation will always happen at the end of the translation unit,
564    // so it will find some names that should not be found. Although this is
565    // common behavior for C++ compilers, it is technically wrong. In the
566    // future, we either need to be able to filter the results of name lookup
567    // or we need to perform template instantiations earlier.
568    PerformPendingInstantiations();
569  }
570
571  // Remove file scoped decls that turned out to be used.
572  UnusedFileScopedDecls.erase(std::remove_if(UnusedFileScopedDecls.begin(0,
573                                                                         true),
574                                             UnusedFileScopedDecls.end(),
575                              std::bind1st(std::ptr_fun(ShouldRemoveFromUnused),
576                                           this)),
577                              UnusedFileScopedDecls.end());
578
579  if (TUKind == TU_Prefix) {
580    // Translation unit prefixes don't need any of the checking below.
581    TUScope = 0;
582    return;
583  }
584
585  // Check for #pragma weak identifiers that were never declared
586  // FIXME: This will cause diagnostics to be emitted in a non-determinstic
587  // order!  Iterating over a densemap like this is bad.
588  LoadExternalWeakUndeclaredIdentifiers();
589  for (llvm::DenseMap<IdentifierInfo*,WeakInfo>::iterator
590       I = WeakUndeclaredIdentifiers.begin(),
591       E = WeakUndeclaredIdentifiers.end(); I != E; ++I) {
592    if (I->second.getUsed()) continue;
593
594    Diag(I->second.getLocation(), diag::warn_weak_identifier_undeclared)
595      << I->first;
596  }
597
598  if (TUKind == TU_Module) {
599    // If we are building a module, resolve all of the exported declarations
600    // now.
601    if (Module *CurrentModule = PP.getCurrentModule()) {
602      ModuleMap &ModMap = PP.getHeaderSearchInfo().getModuleMap();
603
604      llvm::SmallVector<Module *, 2> Stack;
605      Stack.push_back(CurrentModule);
606      while (!Stack.empty()) {
607        Module *Mod = Stack.back();
608        Stack.pop_back();
609
610        // Resolve the exported declarations.
611        // FIXME: Actually complain, once we figure out how to teach the
612        // diagnostic client to deal with complains in the module map at this
613        // point.
614        ModMap.resolveExports(Mod, /*Complain=*/false);
615
616        // Queue the submodules, so their exports will also be resolved.
617        for (Module::submodule_iterator Sub = Mod->submodule_begin(),
618                                     SubEnd = Mod->submodule_end();
619             Sub != SubEnd; ++Sub) {
620          Stack.push_back(*Sub);
621        }
622      }
623    }
624
625    // Modules don't need any of the checking below.
626    TUScope = 0;
627    return;
628  }
629
630  // C99 6.9.2p2:
631  //   A declaration of an identifier for an object that has file
632  //   scope without an initializer, and without a storage-class
633  //   specifier or with the storage-class specifier static,
634  //   constitutes a tentative definition. If a translation unit
635  //   contains one or more tentative definitions for an identifier,
636  //   and the translation unit contains no external definition for
637  //   that identifier, then the behavior is exactly as if the
638  //   translation unit contains a file scope declaration of that
639  //   identifier, with the composite type as of the end of the
640  //   translation unit, with an initializer equal to 0.
641  llvm::SmallSet<VarDecl *, 32> Seen;
642  for (TentativeDefinitionsType::iterator
643            T = TentativeDefinitions.begin(ExternalSource),
644         TEnd = TentativeDefinitions.end();
645       T != TEnd; ++T)
646  {
647    VarDecl *VD = (*T)->getActingDefinition();
648
649    // If the tentative definition was completed, getActingDefinition() returns
650    // null. If we've already seen this variable before, insert()'s second
651    // return value is false.
652    if (VD == 0 || VD->isInvalidDecl() || !Seen.insert(VD))
653      continue;
654
655    if (const IncompleteArrayType *ArrayT
656        = Context.getAsIncompleteArrayType(VD->getType())) {
657      if (RequireCompleteType(VD->getLocation(),
658                              ArrayT->getElementType(),
659                              diag::err_tentative_def_incomplete_type_arr)) {
660        VD->setInvalidDecl();
661        continue;
662      }
663
664      // Set the length of the array to 1 (C99 6.9.2p5).
665      Diag(VD->getLocation(), diag::warn_tentative_incomplete_array);
666      llvm::APInt One(Context.getTypeSize(Context.getSizeType()), true);
667      QualType T = Context.getConstantArrayType(ArrayT->getElementType(),
668                                                One, ArrayType::Normal, 0);
669      VD->setType(T);
670    } else if (RequireCompleteType(VD->getLocation(), VD->getType(),
671                                   diag::err_tentative_def_incomplete_type))
672      VD->setInvalidDecl();
673
674    CheckCompleteVariableDeclaration(VD);
675
676    // Notify the consumer that we've completed a tentative definition.
677    if (!VD->isInvalidDecl())
678      Consumer.CompleteTentativeDefinition(VD);
679
680  }
681
682  if (LangOpts.CPlusPlus11 &&
683      Diags.getDiagnosticLevel(diag::warn_delegating_ctor_cycle,
684                               SourceLocation())
685        != DiagnosticsEngine::Ignored)
686    CheckDelegatingCtorCycles();
687
688  // If there were errors, disable 'unused' warnings since they will mostly be
689  // noise.
690  if (!Diags.hasErrorOccurred()) {
691    // Output warning for unused file scoped decls.
692    for (UnusedFileScopedDeclsType::iterator
693           I = UnusedFileScopedDecls.begin(ExternalSource),
694           E = UnusedFileScopedDecls.end(); I != E; ++I) {
695      if (ShouldRemoveFromUnused(this, *I))
696        continue;
697
698      if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(*I)) {
699        const FunctionDecl *DiagD;
700        if (!FD->hasBody(DiagD))
701          DiagD = FD;
702        if (DiagD->isDeleted())
703          continue; // Deleted functions are supposed to be unused.
704        if (DiagD->isReferenced()) {
705          if (isa<CXXMethodDecl>(DiagD))
706            Diag(DiagD->getLocation(), diag::warn_unneeded_member_function)
707                  << DiagD->getDeclName();
708          else {
709            if (FD->getStorageClassAsWritten() == SC_Static &&
710                !FD->isInlineSpecified() &&
711                !SourceMgr.isFromMainFile(
712                   SourceMgr.getExpansionLoc(FD->getLocation())))
713              Diag(DiagD->getLocation(), diag::warn_unneeded_static_internal_decl)
714                << DiagD->getDeclName();
715            else
716              Diag(DiagD->getLocation(), diag::warn_unneeded_internal_decl)
717                   << /*function*/0 << DiagD->getDeclName();
718          }
719        } else {
720          Diag(DiagD->getLocation(),
721               isa<CXXMethodDecl>(DiagD) ? diag::warn_unused_member_function
722                                         : diag::warn_unused_function)
723                << DiagD->getDeclName();
724        }
725      } else {
726        const VarDecl *DiagD = cast<VarDecl>(*I)->getDefinition();
727        if (!DiagD)
728          DiagD = cast<VarDecl>(*I);
729        if (DiagD->isReferenced()) {
730          Diag(DiagD->getLocation(), diag::warn_unneeded_internal_decl)
731                << /*variable*/1 << DiagD->getDeclName();
732        } else {
733          Diag(DiagD->getLocation(), diag::warn_unused_variable)
734                << DiagD->getDeclName();
735        }
736      }
737    }
738
739    checkUndefinedInternals(*this);
740  }
741
742  if (Diags.getDiagnosticLevel(diag::warn_unused_private_field,
743                               SourceLocation())
744        != DiagnosticsEngine::Ignored) {
745    RecordCompleteMap RecordsComplete;
746    RecordCompleteMap MNCComplete;
747    for (NamedDeclSetType::iterator I = UnusedPrivateFields.begin(),
748         E = UnusedPrivateFields.end(); I != E; ++I) {
749      const NamedDecl *D = *I;
750      const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(D->getDeclContext());
751      if (RD && !RD->isUnion() &&
752          IsRecordFullyDefined(RD, RecordsComplete, MNCComplete)) {
753        Diag(D->getLocation(), diag::warn_unused_private_field)
754              << D->getDeclName();
755      }
756    }
757  }
758
759  // Check we've noticed that we're no longer parsing the initializer for every
760  // variable. If we miss cases, then at best we have a performance issue and
761  // at worst a rejects-valid bug.
762  assert(ParsingInitForAutoVars.empty() &&
763         "Didn't unmark var as having its initializer parsed");
764
765  TUScope = 0;
766}
767
768
769//===----------------------------------------------------------------------===//
770// Helper functions.
771//===----------------------------------------------------------------------===//
772
773DeclContext *Sema::getFunctionLevelDeclContext() {
774  DeclContext *DC = CurContext;
775
776  while (true) {
777    if (isa<BlockDecl>(DC) || isa<EnumDecl>(DC)) {
778      DC = DC->getParent();
779    } else if (isa<CXXMethodDecl>(DC) &&
780               cast<CXXMethodDecl>(DC)->getOverloadedOperator() == OO_Call &&
781               cast<CXXRecordDecl>(DC->getParent())->isLambda()) {
782      DC = DC->getParent()->getParent();
783    }
784    else break;
785  }
786
787  return DC;
788}
789
790/// getCurFunctionDecl - If inside of a function body, this returns a pointer
791/// to the function decl for the function being parsed.  If we're currently
792/// in a 'block', this returns the containing context.
793FunctionDecl *Sema::getCurFunctionDecl() {
794  DeclContext *DC = getFunctionLevelDeclContext();
795  return dyn_cast<FunctionDecl>(DC);
796}
797
798ObjCMethodDecl *Sema::getCurMethodDecl() {
799  DeclContext *DC = getFunctionLevelDeclContext();
800  return dyn_cast<ObjCMethodDecl>(DC);
801}
802
803NamedDecl *Sema::getCurFunctionOrMethodDecl() {
804  DeclContext *DC = getFunctionLevelDeclContext();
805  if (isa<ObjCMethodDecl>(DC) || isa<FunctionDecl>(DC))
806    return cast<NamedDecl>(DC);
807  return 0;
808}
809
810void Sema::EmitCurrentDiagnostic(unsigned DiagID) {
811  // FIXME: It doesn't make sense to me that DiagID is an incoming argument here
812  // and yet we also use the current diag ID on the DiagnosticsEngine. This has
813  // been made more painfully obvious by the refactor that introduced this
814  // function, but it is possible that the incoming argument can be
815  // eliminnated. If it truly cannot be (for example, there is some reentrancy
816  // issue I am not seeing yet), then there should at least be a clarifying
817  // comment somewhere.
818  if (llvm::Optional<TemplateDeductionInfo*> Info = isSFINAEContext()) {
819    switch (DiagnosticIDs::getDiagnosticSFINAEResponse(
820              Diags.getCurrentDiagID())) {
821    case DiagnosticIDs::SFINAE_Report:
822      // We'll report the diagnostic below.
823      break;
824
825    case DiagnosticIDs::SFINAE_SubstitutionFailure:
826      // Count this failure so that we know that template argument deduction
827      // has failed.
828      ++NumSFINAEErrors;
829
830      // Make a copy of this suppressed diagnostic and store it with the
831      // template-deduction information.
832      if (*Info && !(*Info)->hasSFINAEDiagnostic()) {
833        Diagnostic DiagInfo(&Diags);
834        (*Info)->addSFINAEDiagnostic(DiagInfo.getLocation(),
835                       PartialDiagnostic(DiagInfo, Context.getDiagAllocator()));
836      }
837
838      Diags.setLastDiagnosticIgnored();
839      Diags.Clear();
840      return;
841
842    case DiagnosticIDs::SFINAE_AccessControl: {
843      // Per C++ Core Issue 1170, access control is part of SFINAE.
844      // Additionally, the AccessCheckingSFINAE flag can be used to temporarily
845      // make access control a part of SFINAE for the purposes of checking
846      // type traits.
847      if (!AccessCheckingSFINAE && !getLangOpts().CPlusPlus11)
848        break;
849
850      SourceLocation Loc = Diags.getCurrentDiagLoc();
851
852      // Suppress this diagnostic.
853      ++NumSFINAEErrors;
854
855      // Make a copy of this suppressed diagnostic and store it with the
856      // template-deduction information.
857      if (*Info && !(*Info)->hasSFINAEDiagnostic()) {
858        Diagnostic DiagInfo(&Diags);
859        (*Info)->addSFINAEDiagnostic(DiagInfo.getLocation(),
860                       PartialDiagnostic(DiagInfo, Context.getDiagAllocator()));
861      }
862
863      Diags.setLastDiagnosticIgnored();
864      Diags.Clear();
865
866      // Now the diagnostic state is clear, produce a C++98 compatibility
867      // warning.
868      Diag(Loc, diag::warn_cxx98_compat_sfinae_access_control);
869
870      // The last diagnostic which Sema produced was ignored. Suppress any
871      // notes attached to it.
872      Diags.setLastDiagnosticIgnored();
873      return;
874    }
875
876    case DiagnosticIDs::SFINAE_Suppress:
877      // Make a copy of this suppressed diagnostic and store it with the
878      // template-deduction information;
879      if (*Info) {
880        Diagnostic DiagInfo(&Diags);
881        (*Info)->addSuppressedDiagnostic(DiagInfo.getLocation(),
882                       PartialDiagnostic(DiagInfo, Context.getDiagAllocator()));
883      }
884
885      // Suppress this diagnostic.
886      Diags.setLastDiagnosticIgnored();
887      Diags.Clear();
888      return;
889    }
890  }
891
892  // Set up the context's printing policy based on our current state.
893  Context.setPrintingPolicy(getPrintingPolicy());
894
895  // Emit the diagnostic.
896  if (!Diags.EmitCurrentDiagnostic())
897    return;
898
899  // If this is not a note, and we're in a template instantiation
900  // that is different from the last template instantiation where
901  // we emitted an error, print a template instantiation
902  // backtrace.
903  if (!DiagnosticIDs::isBuiltinNote(DiagID) &&
904      !ActiveTemplateInstantiations.empty() &&
905      ActiveTemplateInstantiations.back()
906        != LastTemplateInstantiationErrorContext) {
907    PrintInstantiationStack();
908    LastTemplateInstantiationErrorContext = ActiveTemplateInstantiations.back();
909  }
910}
911
912Sema::SemaDiagnosticBuilder
913Sema::Diag(SourceLocation Loc, const PartialDiagnostic& PD) {
914  SemaDiagnosticBuilder Builder(Diag(Loc, PD.getDiagID()));
915  PD.Emit(Builder);
916
917  return Builder;
918}
919
920/// \brief Looks through the macro-expansion chain for the given
921/// location, looking for a macro expansion with the given name.
922/// If one is found, returns true and sets the location to that
923/// expansion loc.
924bool Sema::findMacroSpelling(SourceLocation &locref, StringRef name) {
925  SourceLocation loc = locref;
926  if (!loc.isMacroID()) return false;
927
928  // There's no good way right now to look at the intermediate
929  // expansions, so just jump to the expansion location.
930  loc = getSourceManager().getExpansionLoc(loc);
931
932  // If that's written with the name, stop here.
933  SmallVector<char, 16> buffer;
934  if (getPreprocessor().getSpelling(loc, buffer) == name) {
935    locref = loc;
936    return true;
937  }
938  return false;
939}
940
941/// \brief Determines the active Scope associated with the given declaration
942/// context.
943///
944/// This routine maps a declaration context to the active Scope object that
945/// represents that declaration context in the parser. It is typically used
946/// from "scope-less" code (e.g., template instantiation, lazy creation of
947/// declarations) that injects a name for name-lookup purposes and, therefore,
948/// must update the Scope.
949///
950/// \returns The scope corresponding to the given declaraion context, or NULL
951/// if no such scope is open.
952Scope *Sema::getScopeForContext(DeclContext *Ctx) {
953
954  if (!Ctx)
955    return 0;
956
957  Ctx = Ctx->getPrimaryContext();
958  for (Scope *S = getCurScope(); S; S = S->getParent()) {
959    // Ignore scopes that cannot have declarations. This is important for
960    // out-of-line definitions of static class members.
961    if (S->getFlags() & (Scope::DeclScope | Scope::TemplateParamScope))
962      if (DeclContext *Entity = static_cast<DeclContext *> (S->getEntity()))
963        if (Ctx == Entity->getPrimaryContext())
964          return S;
965  }
966
967  return 0;
968}
969
970/// \brief Enter a new function scope
971void Sema::PushFunctionScope() {
972  if (FunctionScopes.size() == 1) {
973    // Use the "top" function scope rather than having to allocate
974    // memory for a new scope.
975    FunctionScopes.back()->Clear();
976    FunctionScopes.push_back(FunctionScopes.back());
977    return;
978  }
979
980  FunctionScopes.push_back(new FunctionScopeInfo(getDiagnostics()));
981}
982
983void Sema::PushBlockScope(Scope *BlockScope, BlockDecl *Block) {
984  FunctionScopes.push_back(new BlockScopeInfo(getDiagnostics(),
985                                              BlockScope, Block));
986}
987
988void Sema::PushLambdaScope(CXXRecordDecl *Lambda,
989                           CXXMethodDecl *CallOperator) {
990  FunctionScopes.push_back(new LambdaScopeInfo(getDiagnostics(), Lambda,
991                                               CallOperator));
992}
993
994void Sema::PopFunctionScopeInfo(const AnalysisBasedWarnings::Policy *WP,
995                                const Decl *D, const BlockExpr *blkExpr) {
996  FunctionScopeInfo *Scope = FunctionScopes.pop_back_val();
997  assert(!FunctionScopes.empty() && "mismatched push/pop!");
998
999  // Issue any analysis-based warnings.
1000  if (WP && D)
1001    AnalysisWarnings.IssueWarnings(*WP, Scope, D, blkExpr);
1002  else {
1003    for (SmallVectorImpl<sema::PossiblyUnreachableDiag>::iterator
1004         i = Scope->PossiblyUnreachableDiags.begin(),
1005         e = Scope->PossiblyUnreachableDiags.end();
1006         i != e; ++i) {
1007      const sema::PossiblyUnreachableDiag &D = *i;
1008      Diag(D.Loc, D.PD);
1009    }
1010  }
1011
1012  if (FunctionScopes.back() != Scope) {
1013    delete Scope;
1014  }
1015}
1016
1017void Sema::PushCompoundScope() {
1018  getCurFunction()->CompoundScopes.push_back(CompoundScopeInfo());
1019}
1020
1021void Sema::PopCompoundScope() {
1022  FunctionScopeInfo *CurFunction = getCurFunction();
1023  assert(!CurFunction->CompoundScopes.empty() && "mismatched push/pop");
1024
1025  CurFunction->CompoundScopes.pop_back();
1026}
1027
1028/// \brief Determine whether any errors occurred within this function/method/
1029/// block.
1030bool Sema::hasAnyUnrecoverableErrorsInThisFunction() const {
1031  return getCurFunction()->ErrorTrap.hasUnrecoverableErrorOccurred();
1032}
1033
1034BlockScopeInfo *Sema::getCurBlock() {
1035  if (FunctionScopes.empty())
1036    return 0;
1037
1038  return dyn_cast<BlockScopeInfo>(FunctionScopes.back());
1039}
1040
1041LambdaScopeInfo *Sema::getCurLambda() {
1042  if (FunctionScopes.empty())
1043    return 0;
1044
1045  return dyn_cast<LambdaScopeInfo>(FunctionScopes.back());
1046}
1047
1048void Sema::ActOnComment(SourceRange Comment) {
1049  if (!LangOpts.RetainCommentsFromSystemHeaders &&
1050      SourceMgr.isInSystemHeader(Comment.getBegin()))
1051    return;
1052  RawComment RC(SourceMgr, Comment);
1053  if (RC.isAlmostTrailingComment()) {
1054    SourceRange MagicMarkerRange(Comment.getBegin(),
1055                                 Comment.getBegin().getLocWithOffset(3));
1056    StringRef MagicMarkerText;
1057    switch (RC.getKind()) {
1058    case RawComment::RCK_OrdinaryBCPL:
1059      MagicMarkerText = "///<";
1060      break;
1061    case RawComment::RCK_OrdinaryC:
1062      MagicMarkerText = "/**<";
1063      break;
1064    default:
1065      llvm_unreachable("if this is an almost Doxygen comment, "
1066                       "it should be ordinary");
1067    }
1068    Diag(Comment.getBegin(), diag::warn_not_a_doxygen_trailing_member_comment) <<
1069      FixItHint::CreateReplacement(MagicMarkerRange, MagicMarkerText);
1070  }
1071  Context.addComment(RC);
1072}
1073
1074// Pin this vtable to this file.
1075ExternalSemaSource::~ExternalSemaSource() {}
1076
1077void ExternalSemaSource::ReadMethodPool(Selector Sel) { }
1078
1079void ExternalSemaSource::ReadKnownNamespaces(
1080                           SmallVectorImpl<NamespaceDecl *> &Namespaces) {
1081}
1082
1083void PrettyDeclStackTraceEntry::print(raw_ostream &OS) const {
1084  SourceLocation Loc = this->Loc;
1085  if (!Loc.isValid() && TheDecl) Loc = TheDecl->getLocation();
1086  if (Loc.isValid()) {
1087    Loc.print(OS, S.getSourceManager());
1088    OS << ": ";
1089  }
1090  OS << Message;
1091
1092  if (TheDecl && isa<NamedDecl>(TheDecl)) {
1093    std::string Name = cast<NamedDecl>(TheDecl)->getNameAsString();
1094    if (!Name.empty())
1095      OS << " '" << Name << '\'';
1096  }
1097
1098  OS << '\n';
1099}
1100
1101/// \brief Figure out if an expression could be turned into a call.
1102///
1103/// Use this when trying to recover from an error where the programmer may have
1104/// written just the name of a function instead of actually calling it.
1105///
1106/// \param E - The expression to examine.
1107/// \param ZeroArgCallReturnTy - If the expression can be turned into a call
1108///  with no arguments, this parameter is set to the type returned by such a
1109///  call; otherwise, it is set to an empty QualType.
1110/// \param OverloadSet - If the expression is an overloaded function
1111///  name, this parameter is populated with the decls of the various overloads.
1112bool Sema::isExprCallable(const Expr &E, QualType &ZeroArgCallReturnTy,
1113                          UnresolvedSetImpl &OverloadSet) {
1114  ZeroArgCallReturnTy = QualType();
1115  OverloadSet.clear();
1116
1117  if (E.getType() == Context.OverloadTy) {
1118    OverloadExpr::FindResult FR = OverloadExpr::find(const_cast<Expr*>(&E));
1119    const OverloadExpr *Overloads = FR.Expression;
1120
1121    for (OverloadExpr::decls_iterator it = Overloads->decls_begin(),
1122         DeclsEnd = Overloads->decls_end(); it != DeclsEnd; ++it) {
1123      OverloadSet.addDecl(*it);
1124
1125      // Check whether the function is a non-template which takes no
1126      // arguments.
1127      if (const FunctionDecl *OverloadDecl
1128            = dyn_cast<FunctionDecl>((*it)->getUnderlyingDecl())) {
1129        if (OverloadDecl->getMinRequiredArguments() == 0)
1130          ZeroArgCallReturnTy = OverloadDecl->getResultType();
1131      }
1132    }
1133
1134    // Ignore overloads that are pointer-to-member constants.
1135    if (FR.HasFormOfMemberPointer)
1136      return false;
1137
1138    return true;
1139  }
1140
1141  if (const DeclRefExpr *DeclRef = dyn_cast<DeclRefExpr>(E.IgnoreParens())) {
1142    if (const FunctionDecl *Fun = dyn_cast<FunctionDecl>(DeclRef->getDecl())) {
1143      if (Fun->getMinRequiredArguments() == 0)
1144        ZeroArgCallReturnTy = Fun->getResultType();
1145      return true;
1146    }
1147  }
1148
1149  // We don't have an expression that's convenient to get a FunctionDecl from,
1150  // but we can at least check if the type is "function of 0 arguments".
1151  QualType ExprTy = E.getType();
1152  const FunctionType *FunTy = NULL;
1153  QualType PointeeTy = ExprTy->getPointeeType();
1154  if (!PointeeTy.isNull())
1155    FunTy = PointeeTy->getAs<FunctionType>();
1156  if (!FunTy)
1157    FunTy = ExprTy->getAs<FunctionType>();
1158  if (!FunTy && ExprTy == Context.BoundMemberTy) {
1159    // Look for the bound-member type.  If it's still overloaded, give up,
1160    // although we probably should have fallen into the OverloadExpr case above
1161    // if we actually have an overloaded bound member.
1162    QualType BoundMemberTy = Expr::findBoundMemberType(&E);
1163    if (!BoundMemberTy.isNull())
1164      FunTy = BoundMemberTy->castAs<FunctionType>();
1165  }
1166
1167  if (const FunctionProtoType *FPT =
1168      dyn_cast_or_null<FunctionProtoType>(FunTy)) {
1169    if (FPT->getNumArgs() == 0)
1170      ZeroArgCallReturnTy = FunTy->getResultType();
1171    return true;
1172  }
1173  return false;
1174}
1175
1176/// \brief Give notes for a set of overloads.
1177///
1178/// A companion to isExprCallable. In cases when the name that the programmer
1179/// wrote was an overloaded function, we may be able to make some guesses about
1180/// plausible overloads based on their return types; such guesses can be handed
1181/// off to this method to be emitted as notes.
1182///
1183/// \param Overloads - The overloads to note.
1184/// \param FinalNoteLoc - If we've suppressed printing some overloads due to
1185///  -fshow-overloads=best, this is the location to attach to the note about too
1186///  many candidates. Typically this will be the location of the original
1187///  ill-formed expression.
1188static void noteOverloads(Sema &S, const UnresolvedSetImpl &Overloads,
1189                          const SourceLocation FinalNoteLoc) {
1190  int ShownOverloads = 0;
1191  int SuppressedOverloads = 0;
1192  for (UnresolvedSetImpl::iterator It = Overloads.begin(),
1193       DeclsEnd = Overloads.end(); It != DeclsEnd; ++It) {
1194    // FIXME: Magic number for max shown overloads stolen from
1195    // OverloadCandidateSet::NoteCandidates.
1196    if (ShownOverloads >= 4 && S.Diags.getShowOverloads() == Ovl_Best) {
1197      ++SuppressedOverloads;
1198      continue;
1199    }
1200
1201    NamedDecl *Fn = (*It)->getUnderlyingDecl();
1202    S.Diag(Fn->getLocation(), diag::note_possible_target_of_call);
1203    ++ShownOverloads;
1204  }
1205
1206  if (SuppressedOverloads)
1207    S.Diag(FinalNoteLoc, diag::note_ovl_too_many_candidates)
1208      << SuppressedOverloads;
1209}
1210
1211static void notePlausibleOverloads(Sema &S, SourceLocation Loc,
1212                                   const UnresolvedSetImpl &Overloads,
1213                                   bool (*IsPlausibleResult)(QualType)) {
1214  if (!IsPlausibleResult)
1215    return noteOverloads(S, Overloads, Loc);
1216
1217  UnresolvedSet<2> PlausibleOverloads;
1218  for (OverloadExpr::decls_iterator It = Overloads.begin(),
1219         DeclsEnd = Overloads.end(); It != DeclsEnd; ++It) {
1220    const FunctionDecl *OverloadDecl = cast<FunctionDecl>(*It);
1221    QualType OverloadResultTy = OverloadDecl->getResultType();
1222    if (IsPlausibleResult(OverloadResultTy))
1223      PlausibleOverloads.addDecl(It.getDecl());
1224  }
1225  noteOverloads(S, PlausibleOverloads, Loc);
1226}
1227
1228/// Determine whether the given expression can be called by just
1229/// putting parentheses after it.  Notably, expressions with unary
1230/// operators can't be because the unary operator will start parsing
1231/// outside the call.
1232static bool IsCallableWithAppend(Expr *E) {
1233  E = E->IgnoreImplicit();
1234  return (!isa<CStyleCastExpr>(E) &&
1235          !isa<UnaryOperator>(E) &&
1236          !isa<BinaryOperator>(E) &&
1237          !isa<CXXOperatorCallExpr>(E));
1238}
1239
1240bool Sema::tryToRecoverWithCall(ExprResult &E, const PartialDiagnostic &PD,
1241                                bool ForceComplain,
1242                                bool (*IsPlausibleResult)(QualType)) {
1243  SourceLocation Loc = E.get()->getExprLoc();
1244  SourceRange Range = E.get()->getSourceRange();
1245
1246  QualType ZeroArgCallTy;
1247  UnresolvedSet<4> Overloads;
1248  if (isExprCallable(*E.get(), ZeroArgCallTy, Overloads) &&
1249      !ZeroArgCallTy.isNull() &&
1250      (!IsPlausibleResult || IsPlausibleResult(ZeroArgCallTy))) {
1251    // At this point, we know E is potentially callable with 0
1252    // arguments and that it returns something of a reasonable type,
1253    // so we can emit a fixit and carry on pretending that E was
1254    // actually a CallExpr.
1255    SourceLocation ParenInsertionLoc =
1256      PP.getLocForEndOfToken(Range.getEnd());
1257    Diag(Loc, PD)
1258      << /*zero-arg*/ 1 << Range
1259      << (IsCallableWithAppend(E.get())
1260          ? FixItHint::CreateInsertion(ParenInsertionLoc, "()")
1261          : FixItHint());
1262    notePlausibleOverloads(*this, Loc, Overloads, IsPlausibleResult);
1263
1264    // FIXME: Try this before emitting the fixit, and suppress diagnostics
1265    // while doing so.
1266    E = ActOnCallExpr(0, E.take(), ParenInsertionLoc,
1267                      MultiExprArg(), ParenInsertionLoc.getLocWithOffset(1));
1268    return true;
1269  }
1270
1271  if (!ForceComplain) return false;
1272
1273  Diag(Loc, PD) << /*not zero-arg*/ 0 << Range;
1274  notePlausibleOverloads(*this, Loc, Overloads, IsPlausibleResult);
1275  E = ExprError();
1276  return true;
1277}
1278