Sema.cpp revision dc7b641574a733624489bd87fc7061771edf2113 
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 "clang/Sema/DelayedDiagnostic.h"
17#include "TargetAttributesSema.h"
18#include "llvm/ADT/DenseMap.h"
19#include "llvm/ADT/SmallSet.h"
20#include "llvm/ADT/APFloat.h"
21#include "llvm/Support/CrashRecoveryContext.h"
22#include "clang/Sema/CXXFieldCollector.h"
23#include "clang/Sema/TemplateDeduction.h"
24#include "clang/Sema/ExternalSemaSource.h"
25#include "clang/Sema/MultiplexExternalSemaSource.h"
26#include "clang/Sema/ObjCMethodList.h"
27#include "clang/Sema/PrettyDeclStackTrace.h"
28#include "clang/Sema/Scope.h"
29#include "clang/Sema/ScopeInfo.h"
30#include "clang/Sema/SemaConsumer.h"
31#include "clang/AST/ASTContext.h"
32#include "clang/AST/ASTDiagnostic.h"
33#include "clang/AST/DeclCXX.h"
34#include "clang/AST/DeclFriend.h"
35#include "clang/AST/DeclObjC.h"
36#include "clang/AST/Expr.h"
37#include "clang/AST/ExprCXX.h"
38#include "clang/AST/StmtCXX.h"
39#include "clang/Lex/HeaderSearch.h"
40#include "clang/Lex/Preprocessor.h"
41#include "clang/Basic/FileManager.h"
42#include "clang/Basic/PartialDiagnostic.h"
43#include "clang/Basic/TargetInfo.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().getPointerWidth(0) >= 64) {
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->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  return false;
363}
364
365namespace {
366  struct UndefinedInternal {
367    NamedDecl *decl;
368    FullSourceLoc useLoc;
369
370    UndefinedInternal(NamedDecl *decl, FullSourceLoc useLoc)
371      : decl(decl), useLoc(useLoc) {}
372  };
373
374  bool operator<(const UndefinedInternal &l, const UndefinedInternal &r) {
375    return l.useLoc.isBeforeInTranslationUnitThan(r.useLoc);
376  }
377}
378
379/// checkUndefinedInternals - Check for undefined objects with internal linkage.
380static void checkUndefinedInternals(Sema &S) {
381  if (S.UndefinedInternals.empty()) return;
382
383  // Collect all the still-undefined entities with internal linkage.
384  SmallVector<UndefinedInternal, 16> undefined;
385  for (llvm::DenseMap<NamedDecl*,SourceLocation>::iterator
386         i = S.UndefinedInternals.begin(), e = S.UndefinedInternals.end();
387       i != e; ++i) {
388    NamedDecl *decl = i->first;
389
390    // Ignore attributes that have become invalid.
391    if (decl->isInvalidDecl()) continue;
392
393    // __attribute__((weakref)) is basically a definition.
394    if (decl->hasAttr<WeakRefAttr>()) continue;
395
396    if (FunctionDecl *fn = dyn_cast<FunctionDecl>(decl)) {
397      if (fn->isPure() || fn->hasBody())
398        continue;
399    } else {
400      if (cast<VarDecl>(decl)->hasDefinition() != VarDecl::DeclarationOnly)
401        continue;
402    }
403
404    // We build a FullSourceLoc so that we can sort with array_pod_sort.
405    FullSourceLoc loc(i->second, S.Context.getSourceManager());
406    undefined.push_back(UndefinedInternal(decl, loc));
407  }
408
409  if (undefined.empty()) return;
410
411  // Sort (in order of use site) so that we're not (as) dependent on
412  // the iteration order through an llvm::DenseMap.
413  llvm::array_pod_sort(undefined.begin(), undefined.end());
414
415  for (SmallVectorImpl<UndefinedInternal>::iterator
416         i = undefined.begin(), e = undefined.end(); i != e; ++i) {
417    NamedDecl *decl = i->decl;
418    S.Diag(decl->getLocation(), diag::warn_undefined_internal)
419      << isa<VarDecl>(decl) << decl;
420    S.Diag(i->useLoc, diag::note_used_here);
421  }
422}
423
424void Sema::LoadExternalWeakUndeclaredIdentifiers() {
425  if (!ExternalSource)
426    return;
427
428  SmallVector<std::pair<IdentifierInfo *, WeakInfo>, 4> WeakIDs;
429  ExternalSource->ReadWeakUndeclaredIdentifiers(WeakIDs);
430  for (unsigned I = 0, N = WeakIDs.size(); I != N; ++I) {
431    llvm::DenseMap<IdentifierInfo*,WeakInfo>::iterator Pos
432      = WeakUndeclaredIdentifiers.find(WeakIDs[I].first);
433    if (Pos != WeakUndeclaredIdentifiers.end())
434      continue;
435
436    WeakUndeclaredIdentifiers.insert(WeakIDs[I]);
437  }
438}
439
440
441typedef llvm::DenseMap<const CXXRecordDecl*, bool> RecordCompleteMap;
442
443/// \brief Returns true, if all methods and nested classes of the given
444/// CXXRecordDecl are defined in this translation unit.
445///
446/// Should only be called from ActOnEndOfTranslationUnit so that all
447/// definitions are actually read.
448static bool MethodsAndNestedClassesComplete(const CXXRecordDecl *RD,
449                                            RecordCompleteMap &MNCComplete) {
450  RecordCompleteMap::iterator Cache = MNCComplete.find(RD);
451  if (Cache != MNCComplete.end())
452    return Cache->second;
453  if (!RD->isCompleteDefinition())
454    return false;
455  bool Complete = true;
456  for (DeclContext::decl_iterator I = RD->decls_begin(),
457                                  E = RD->decls_end();
458       I != E && Complete; ++I) {
459    if (const CXXMethodDecl *M = dyn_cast<CXXMethodDecl>(*I))
460      Complete = M->isDefined() || (M->isPure() && !isa<CXXDestructorDecl>(M));
461    else if (const FunctionTemplateDecl *F = dyn_cast<FunctionTemplateDecl>(*I))
462      Complete = F->getTemplatedDecl()->isDefined();
463    else if (const CXXRecordDecl *R = dyn_cast<CXXRecordDecl>(*I)) {
464      if (R->isInjectedClassName())
465        continue;
466      if (R->hasDefinition())
467        Complete = MethodsAndNestedClassesComplete(R->getDefinition(),
468                                                   MNCComplete);
469      else
470        Complete = false;
471    }
472  }
473  MNCComplete[RD] = Complete;
474  return Complete;
475}
476
477/// \brief Returns true, if the given CXXRecordDecl is fully defined in this
478/// translation unit, i.e. all methods are defined or pure virtual and all
479/// friends, friend functions and nested classes are fully defined in this
480/// translation unit.
481///
482/// Should only be called from ActOnEndOfTranslationUnit so that all
483/// definitions are actually read.
484static bool IsRecordFullyDefined(const CXXRecordDecl *RD,
485                                 RecordCompleteMap &RecordsComplete,
486                                 RecordCompleteMap &MNCComplete) {
487  RecordCompleteMap::iterator Cache = RecordsComplete.find(RD);
488  if (Cache != RecordsComplete.end())
489    return Cache->second;
490  bool Complete = MethodsAndNestedClassesComplete(RD, MNCComplete);
491  for (CXXRecordDecl::friend_iterator I = RD->friend_begin(),
492                                      E = RD->friend_end();
493       I != E && Complete; ++I) {
494    // Check if friend classes and methods are complete.
495    if (TypeSourceInfo *TSI = (*I)->getFriendType()) {
496      // Friend classes are available as the TypeSourceInfo of the FriendDecl.
497      if (CXXRecordDecl *FriendD = TSI->getType()->getAsCXXRecordDecl())
498        Complete = MethodsAndNestedClassesComplete(FriendD, MNCComplete);
499      else
500        Complete = false;
501    } else {
502      // Friend functions are available through the NamedDecl of FriendDecl.
503      if (const FunctionDecl *FD =
504          dyn_cast<FunctionDecl>((*I)->getFriendDecl()))
505        Complete = FD->isDefined();
506      else
507        // This is a template friend, give up.
508        Complete = false;
509    }
510  }
511  RecordsComplete[RD] = Complete;
512  return Complete;
513}
514
515/// ActOnEndOfTranslationUnit - This is called at the very end of the
516/// translation unit when EOF is reached and all but the top-level scope is
517/// popped.
518void Sema::ActOnEndOfTranslationUnit() {
519  assert(DelayedDiagnostics.getCurrentPool() == NULL
520         && "reached end of translation unit with a pool attached?");
521
522  // If code completion is enabled, don't perform any end-of-translation-unit
523  // work.
524  if (PP.isCodeCompletionEnabled())
525    return;
526
527  // Only complete translation units define vtables and perform implicit
528  // instantiations.
529  if (TUKind == TU_Complete) {
530    DiagnoseUseOfUnimplementedSelectors();
531
532    // If any dynamic classes have their key function defined within
533    // this translation unit, then those vtables are considered "used" and must
534    // be emitted.
535    for (DynamicClassesType::iterator I = DynamicClasses.begin(ExternalSource),
536                                      E = DynamicClasses.end();
537         I != E; ++I) {
538      assert(!(*I)->isDependentType() &&
539             "Should not see dependent types here!");
540      if (const CXXMethodDecl *KeyFunction = Context.getKeyFunction(*I)) {
541        const FunctionDecl *Definition = 0;
542        if (KeyFunction->hasBody(Definition))
543          MarkVTableUsed(Definition->getLocation(), *I, true);
544      }
545    }
546
547    // If DefinedUsedVTables ends up marking any virtual member functions it
548    // might lead to more pending template instantiations, which we then need
549    // to instantiate.
550    DefineUsedVTables();
551
552    // C++: Perform implicit template instantiations.
553    //
554    // FIXME: When we perform these implicit instantiations, we do not
555    // carefully keep track of the point of instantiation (C++ [temp.point]).
556    // This means that name lookup that occurs within the template
557    // instantiation will always happen at the end of the translation unit,
558    // so it will find some names that should not be found. Although this is
559    // common behavior for C++ compilers, it is technically wrong. In the
560    // future, we either need to be able to filter the results of name lookup
561    // or we need to perform template instantiations earlier.
562    PerformPendingInstantiations();
563  }
564
565  // Remove file scoped decls that turned out to be used.
566  UnusedFileScopedDecls.erase(std::remove_if(UnusedFileScopedDecls.begin(0,
567                                                                         true),
568                                             UnusedFileScopedDecls.end(),
569                              std::bind1st(std::ptr_fun(ShouldRemoveFromUnused),
570                                           this)),
571                              UnusedFileScopedDecls.end());
572
573  if (TUKind == TU_Prefix) {
574    // Translation unit prefixes don't need any of the checking below.
575    TUScope = 0;
576    return;
577  }
578
579  // Check for #pragma weak identifiers that were never declared
580  // FIXME: This will cause diagnostics to be emitted in a non-determinstic
581  // order!  Iterating over a densemap like this is bad.
582  LoadExternalWeakUndeclaredIdentifiers();
583  for (llvm::DenseMap<IdentifierInfo*,WeakInfo>::iterator
584       I = WeakUndeclaredIdentifiers.begin(),
585       E = WeakUndeclaredIdentifiers.end(); I != E; ++I) {
586    if (I->second.getUsed()) continue;
587
588    Diag(I->second.getLocation(), diag::warn_weak_identifier_undeclared)
589      << I->first;
590  }
591
592  if (TUKind == TU_Module) {
593    // If we are building a module, resolve all of the exported declarations
594    // now.
595    if (Module *CurrentModule = PP.getCurrentModule()) {
596      ModuleMap &ModMap = PP.getHeaderSearchInfo().getModuleMap();
597
598      llvm::SmallVector<Module *, 2> Stack;
599      Stack.push_back(CurrentModule);
600      while (!Stack.empty()) {
601        Module *Mod = Stack.back();
602        Stack.pop_back();
603
604        // Resolve the exported declarations.
605        // FIXME: Actually complain, once we figure out how to teach the
606        // diagnostic client to deal with complains in the module map at this
607        // point.
608        ModMap.resolveExports(Mod, /*Complain=*/false);
609
610        // Queue the submodules, so their exports will also be resolved.
611        for (Module::submodule_iterator Sub = Mod->submodule_begin(),
612                                     SubEnd = Mod->submodule_end();
613             Sub != SubEnd; ++Sub) {
614          Stack.push_back(*Sub);
615        }
616      }
617    }
618
619    // Modules don't need any of the checking below.
620    TUScope = 0;
621    return;
622  }
623
624  // C99 6.9.2p2:
625  //   A declaration of an identifier for an object that has file
626  //   scope without an initializer, and without a storage-class
627  //   specifier or with the storage-class specifier static,
628  //   constitutes a tentative definition. If a translation unit
629  //   contains one or more tentative definitions for an identifier,
630  //   and the translation unit contains no external definition for
631  //   that identifier, then the behavior is exactly as if the
632  //   translation unit contains a file scope declaration of that
633  //   identifier, with the composite type as of the end of the
634  //   translation unit, with an initializer equal to 0.
635  llvm::SmallSet<VarDecl *, 32> Seen;
636  for (TentativeDefinitionsType::iterator
637            T = TentativeDefinitions.begin(ExternalSource),
638         TEnd = TentativeDefinitions.end();
639       T != TEnd; ++T)
640  {
641    VarDecl *VD = (*T)->getActingDefinition();
642
643    // If the tentative definition was completed, getActingDefinition() returns
644    // null. If we've already seen this variable before, insert()'s second
645    // return value is false.
646    if (VD == 0 || VD->isInvalidDecl() || !Seen.insert(VD))
647      continue;
648
649    if (const IncompleteArrayType *ArrayT
650        = Context.getAsIncompleteArrayType(VD->getType())) {
651      if (RequireCompleteType(VD->getLocation(),
652                              ArrayT->getElementType(),
653                              diag::err_tentative_def_incomplete_type_arr)) {
654        VD->setInvalidDecl();
655        continue;
656      }
657
658      // Set the length of the array to 1 (C99 6.9.2p5).
659      Diag(VD->getLocation(), diag::warn_tentative_incomplete_array);
660      llvm::APInt One(Context.getTypeSize(Context.getSizeType()), true);
661      QualType T = Context.getConstantArrayType(ArrayT->getElementType(),
662                                                One, ArrayType::Normal, 0);
663      VD->setType(T);
664    } else if (RequireCompleteType(VD->getLocation(), VD->getType(),
665                                   diag::err_tentative_def_incomplete_type))
666      VD->setInvalidDecl();
667
668    CheckCompleteVariableDeclaration(VD);
669
670    // Notify the consumer that we've completed a tentative definition.
671    if (!VD->isInvalidDecl())
672      Consumer.CompleteTentativeDefinition(VD);
673
674  }
675
676  if (LangOpts.CPlusPlus0x &&
677      Diags.getDiagnosticLevel(diag::warn_delegating_ctor_cycle,
678                               SourceLocation())
679        != DiagnosticsEngine::Ignored)
680    CheckDelegatingCtorCycles();
681
682  // If there were errors, disable 'unused' warnings since they will mostly be
683  // noise.
684  if (!Diags.hasErrorOccurred()) {
685    // Output warning for unused file scoped decls.
686    for (UnusedFileScopedDeclsType::iterator
687           I = UnusedFileScopedDecls.begin(ExternalSource),
688           E = UnusedFileScopedDecls.end(); I != E; ++I) {
689      if (ShouldRemoveFromUnused(this, *I))
690        continue;
691
692      if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(*I)) {
693        const FunctionDecl *DiagD;
694        if (!FD->hasBody(DiagD))
695          DiagD = FD;
696        if (DiagD->isDeleted())
697          continue; // Deleted functions are supposed to be unused.
698        if (DiagD->isReferenced()) {
699          if (isa<CXXMethodDecl>(DiagD))
700            Diag(DiagD->getLocation(), diag::warn_unneeded_member_function)
701                  << DiagD->getDeclName();
702          else {
703            if (FD->getStorageClassAsWritten() == SC_Static &&
704                !FD->isInlineSpecified() &&
705                !SourceMgr.isFromMainFile(
706                   SourceMgr.getExpansionLoc(FD->getLocation())))
707              Diag(DiagD->getLocation(), diag::warn_unneeded_static_internal_decl)
708                << DiagD->getDeclName();
709            else
710              Diag(DiagD->getLocation(), diag::warn_unneeded_internal_decl)
711                   << /*function*/0 << DiagD->getDeclName();
712          }
713        } else {
714          Diag(DiagD->getLocation(),
715               isa<CXXMethodDecl>(DiagD) ? diag::warn_unused_member_function
716                                         : diag::warn_unused_function)
717                << DiagD->getDeclName();
718        }
719      } else {
720        const VarDecl *DiagD = cast<VarDecl>(*I)->getDefinition();
721        if (!DiagD)
722          DiagD = cast<VarDecl>(*I);
723        if (DiagD->isReferenced()) {
724          Diag(DiagD->getLocation(), diag::warn_unneeded_internal_decl)
725                << /*variable*/1 << DiagD->getDeclName();
726        } else {
727          Diag(DiagD->getLocation(), diag::warn_unused_variable)
728                << DiagD->getDeclName();
729        }
730      }
731    }
732
733    checkUndefinedInternals(*this);
734  }
735
736  if (Diags.getDiagnosticLevel(diag::warn_unused_private_field,
737                               SourceLocation())
738        != DiagnosticsEngine::Ignored) {
739    RecordCompleteMap RecordsComplete;
740    RecordCompleteMap MNCComplete;
741    for (NamedDeclSetType::iterator I = UnusedPrivateFields.begin(),
742         E = UnusedPrivateFields.end(); I != E; ++I) {
743      const NamedDecl *D = *I;
744      const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(D->getDeclContext());
745      if (RD && !RD->isUnion() &&
746          IsRecordFullyDefined(RD, RecordsComplete, MNCComplete)) {
747        Diag(D->getLocation(), diag::warn_unused_private_field)
748              << D->getDeclName();
749      }
750    }
751  }
752
753  // Check we've noticed that we're no longer parsing the initializer for every
754  // variable. If we miss cases, then at best we have a performance issue and
755  // at worst a rejects-valid bug.
756  assert(ParsingInitForAutoVars.empty() &&
757         "Didn't unmark var as having its initializer parsed");
758
759  TUScope = 0;
760}
761
762
763//===----------------------------------------------------------------------===//
764// Helper functions.
765//===----------------------------------------------------------------------===//
766
767DeclContext *Sema::getFunctionLevelDeclContext() {
768  DeclContext *DC = CurContext;
769
770  while (true) {
771    if (isa<BlockDecl>(DC) || isa<EnumDecl>(DC)) {
772      DC = DC->getParent();
773    } else if (isa<CXXMethodDecl>(DC) &&
774               cast<CXXMethodDecl>(DC)->getOverloadedOperator() == OO_Call &&
775               cast<CXXRecordDecl>(DC->getParent())->isLambda()) {
776      DC = DC->getParent()->getParent();
777    }
778    else break;
779  }
780
781  return DC;
782}
783
784/// getCurFunctionDecl - If inside of a function body, this returns a pointer
785/// to the function decl for the function being parsed.  If we're currently
786/// in a 'block', this returns the containing context.
787FunctionDecl *Sema::getCurFunctionDecl() {
788  DeclContext *DC = getFunctionLevelDeclContext();
789  return dyn_cast<FunctionDecl>(DC);
790}
791
792ObjCMethodDecl *Sema::getCurMethodDecl() {
793  DeclContext *DC = getFunctionLevelDeclContext();
794  return dyn_cast<ObjCMethodDecl>(DC);
795}
796
797NamedDecl *Sema::getCurFunctionOrMethodDecl() {
798  DeclContext *DC = getFunctionLevelDeclContext();
799  if (isa<ObjCMethodDecl>(DC) || isa<FunctionDecl>(DC))
800    return cast<NamedDecl>(DC);
801  return 0;
802}
803
804void Sema::EmitCurrentDiagnostic(unsigned DiagID) {
805  // FIXME: It doesn't make sense to me that DiagID is an incoming argument here
806  // and yet we also use the current diag ID on the DiagnosticsEngine. This has
807  // been made more painfully obvious by the refactor that introduced this
808  // function, but it is possible that the incoming argument can be
809  // eliminnated. If it truly cannot be (for example, there is some reentrancy
810  // issue I am not seeing yet), then there should at least be a clarifying
811  // comment somewhere.
812  if (llvm::Optional<TemplateDeductionInfo*> Info = isSFINAEContext()) {
813    switch (DiagnosticIDs::getDiagnosticSFINAEResponse(
814              Diags.getCurrentDiagID())) {
815    case DiagnosticIDs::SFINAE_Report:
816      // We'll report the diagnostic below.
817      break;
818
819    case DiagnosticIDs::SFINAE_SubstitutionFailure:
820      // Count this failure so that we know that template argument deduction
821      // has failed.
822      ++NumSFINAEErrors;
823
824      // Make a copy of this suppressed diagnostic and store it with the
825      // template-deduction information.
826      if (*Info && !(*Info)->hasSFINAEDiagnostic()) {
827        Diagnostic DiagInfo(&Diags);
828        (*Info)->addSFINAEDiagnostic(DiagInfo.getLocation(),
829                       PartialDiagnostic(DiagInfo, Context.getDiagAllocator()));
830      }
831
832      Diags.setLastDiagnosticIgnored();
833      Diags.Clear();
834      return;
835
836    case DiagnosticIDs::SFINAE_AccessControl: {
837      // Per C++ Core Issue 1170, access control is part of SFINAE.
838      // Additionally, the AccessCheckingSFINAE flag can be used to temporarily
839      // make access control a part of SFINAE for the purposes of checking
840      // type traits.
841      if (!AccessCheckingSFINAE && !getLangOpts().CPlusPlus0x)
842        break;
843
844      SourceLocation Loc = Diags.getCurrentDiagLoc();
845
846      // Suppress this diagnostic.
847      ++NumSFINAEErrors;
848
849      // Make a copy of this suppressed diagnostic and store it with the
850      // template-deduction information.
851      if (*Info && !(*Info)->hasSFINAEDiagnostic()) {
852        Diagnostic DiagInfo(&Diags);
853        (*Info)->addSFINAEDiagnostic(DiagInfo.getLocation(),
854                       PartialDiagnostic(DiagInfo, Context.getDiagAllocator()));
855      }
856
857      Diags.setLastDiagnosticIgnored();
858      Diags.Clear();
859
860      // Now the diagnostic state is clear, produce a C++98 compatibility
861      // warning.
862      Diag(Loc, diag::warn_cxx98_compat_sfinae_access_control);
863
864      // The last diagnostic which Sema produced was ignored. Suppress any
865      // notes attached to it.
866      Diags.setLastDiagnosticIgnored();
867      return;
868    }
869
870    case DiagnosticIDs::SFINAE_Suppress:
871      // Make a copy of this suppressed diagnostic and store it with the
872      // template-deduction information;
873      if (*Info) {
874        Diagnostic DiagInfo(&Diags);
875        (*Info)->addSuppressedDiagnostic(DiagInfo.getLocation(),
876                       PartialDiagnostic(DiagInfo, Context.getDiagAllocator()));
877      }
878
879      // Suppress this diagnostic.
880      Diags.setLastDiagnosticIgnored();
881      Diags.Clear();
882      return;
883    }
884  }
885
886  // Set up the context's printing policy based on our current state.
887  Context.setPrintingPolicy(getPrintingPolicy());
888
889  // Emit the diagnostic.
890  if (!Diags.EmitCurrentDiagnostic())
891    return;
892
893  // If this is not a note, and we're in a template instantiation
894  // that is different from the last template instantiation where
895  // we emitted an error, print a template instantiation
896  // backtrace.
897  if (!DiagnosticIDs::isBuiltinNote(DiagID) &&
898      !ActiveTemplateInstantiations.empty() &&
899      ActiveTemplateInstantiations.back()
900        != LastTemplateInstantiationErrorContext) {
901    PrintInstantiationStack();
902    LastTemplateInstantiationErrorContext = ActiveTemplateInstantiations.back();
903  }
904}
905
906Sema::SemaDiagnosticBuilder
907Sema::Diag(SourceLocation Loc, const PartialDiagnostic& PD) {
908  SemaDiagnosticBuilder Builder(Diag(Loc, PD.getDiagID()));
909  PD.Emit(Builder);
910
911  return Builder;
912}
913
914/// \brief Looks through the macro-expansion chain for the given
915/// location, looking for a macro expansion with the given name.
916/// If one is found, returns true and sets the location to that
917/// expansion loc.
918bool Sema::findMacroSpelling(SourceLocation &locref, StringRef name) {
919  SourceLocation loc = locref;
920  if (!loc.isMacroID()) return false;
921
922  // There's no good way right now to look at the intermediate
923  // expansions, so just jump to the expansion location.
924  loc = getSourceManager().getExpansionLoc(loc);
925
926  // If that's written with the name, stop here.
927  SmallVector<char, 16> buffer;
928  if (getPreprocessor().getSpelling(loc, buffer) == name) {
929    locref = loc;
930    return true;
931  }
932  return false;
933}
934
935/// \brief Determines the active Scope associated with the given declaration
936/// context.
937///
938/// This routine maps a declaration context to the active Scope object that
939/// represents that declaration context in the parser. It is typically used
940/// from "scope-less" code (e.g., template instantiation, lazy creation of
941/// declarations) that injects a name for name-lookup purposes and, therefore,
942/// must update the Scope.
943///
944/// \returns The scope corresponding to the given declaraion context, or NULL
945/// if no such scope is open.
946Scope *Sema::getScopeForContext(DeclContext *Ctx) {
947
948  if (!Ctx)
949    return 0;
950
951  Ctx = Ctx->getPrimaryContext();
952  for (Scope *S = getCurScope(); S; S = S->getParent()) {
953    // Ignore scopes that cannot have declarations. This is important for
954    // out-of-line definitions of static class members.
955    if (S->getFlags() & (Scope::DeclScope | Scope::TemplateParamScope))
956      if (DeclContext *Entity = static_cast<DeclContext *> (S->getEntity()))
957        if (Ctx == Entity->getPrimaryContext())
958          return S;
959  }
960
961  return 0;
962}
963
964/// \brief Enter a new function scope
965void Sema::PushFunctionScope() {
966  if (FunctionScopes.size() == 1) {
967    // Use the "top" function scope rather than having to allocate
968    // memory for a new scope.
969    FunctionScopes.back()->Clear();
970    FunctionScopes.push_back(FunctionScopes.back());
971    return;
972  }
973
974  FunctionScopes.push_back(new FunctionScopeInfo(getDiagnostics()));
975}
976
977void Sema::PushBlockScope(Scope *BlockScope, BlockDecl *Block) {
978  FunctionScopes.push_back(new BlockScopeInfo(getDiagnostics(),
979                                              BlockScope, Block));
980}
981
982void Sema::PushLambdaScope(CXXRecordDecl *Lambda,
983                           CXXMethodDecl *CallOperator) {
984  FunctionScopes.push_back(new LambdaScopeInfo(getDiagnostics(), Lambda,
985                                               CallOperator));
986}
987
988void Sema::PopFunctionScopeInfo(const AnalysisBasedWarnings::Policy *WP,
989                                const Decl *D, const BlockExpr *blkExpr) {
990  FunctionScopeInfo *Scope = FunctionScopes.pop_back_val();
991  assert(!FunctionScopes.empty() && "mismatched push/pop!");
992
993  // Issue any analysis-based warnings.
994  if (WP && D)
995    AnalysisWarnings.IssueWarnings(*WP, Scope, D, blkExpr);
996  else {
997    for (SmallVectorImpl<sema::PossiblyUnreachableDiag>::iterator
998         i = Scope->PossiblyUnreachableDiags.begin(),
999         e = Scope->PossiblyUnreachableDiags.end();
1000         i != e; ++i) {
1001      const sema::PossiblyUnreachableDiag &D = *i;
1002      Diag(D.Loc, D.PD);
1003    }
1004  }
1005
1006  if (FunctionScopes.back() != Scope) {
1007    delete Scope;
1008  }
1009}
1010
1011void Sema::PushCompoundScope() {
1012  getCurFunction()->CompoundScopes.push_back(CompoundScopeInfo());
1013}
1014
1015void Sema::PopCompoundScope() {
1016  FunctionScopeInfo *CurFunction = getCurFunction();
1017  assert(!CurFunction->CompoundScopes.empty() && "mismatched push/pop");
1018
1019  CurFunction->CompoundScopes.pop_back();
1020}
1021
1022/// \brief Determine whether any errors occurred within this function/method/
1023/// block.
1024bool Sema::hasAnyUnrecoverableErrorsInThisFunction() const {
1025  return getCurFunction()->ErrorTrap.hasUnrecoverableErrorOccurred();
1026}
1027
1028BlockScopeInfo *Sema::getCurBlock() {
1029  if (FunctionScopes.empty())
1030    return 0;
1031
1032  return dyn_cast<BlockScopeInfo>(FunctionScopes.back());
1033}
1034
1035LambdaScopeInfo *Sema::getCurLambda() {
1036  if (FunctionScopes.empty())
1037    return 0;
1038
1039  return dyn_cast<LambdaScopeInfo>(FunctionScopes.back());
1040}
1041
1042void Sema::ActOnComment(SourceRange Comment) {
1043  if (!LangOpts.RetainCommentsFromSystemHeaders &&
1044      SourceMgr.isInSystemHeader(Comment.getBegin()))
1045    return;
1046  RawComment RC(SourceMgr, Comment);
1047  if (RC.isAlmostTrailingComment()) {
1048    SourceRange MagicMarkerRange(Comment.getBegin(),
1049                                 Comment.getBegin().getLocWithOffset(3));
1050    StringRef MagicMarkerText;
1051    switch (RC.getKind()) {
1052    case RawComment::RCK_OrdinaryBCPL:
1053      MagicMarkerText = "///<";
1054      break;
1055    case RawComment::RCK_OrdinaryC:
1056      MagicMarkerText = "/**<";
1057      break;
1058    default:
1059      llvm_unreachable("if this is an almost Doxygen comment, "
1060                       "it should be ordinary");
1061    }
1062    Diag(Comment.getBegin(), diag::warn_not_a_doxygen_trailing_member_comment) <<
1063      FixItHint::CreateReplacement(MagicMarkerRange, MagicMarkerText);
1064  }
1065  Context.addComment(RC);
1066}
1067
1068// Pin this vtable to this file.
1069ExternalSemaSource::~ExternalSemaSource() {}
1070
1071void ExternalSemaSource::ReadMethodPool(Selector Sel) { }
1072
1073void ExternalSemaSource::ReadKnownNamespaces(
1074                           SmallVectorImpl<NamespaceDecl *> &Namespaces) {
1075}
1076
1077void PrettyDeclStackTraceEntry::print(raw_ostream &OS) const {
1078  SourceLocation Loc = this->Loc;
1079  if (!Loc.isValid() && TheDecl) Loc = TheDecl->getLocation();
1080  if (Loc.isValid()) {
1081    Loc.print(OS, S.getSourceManager());
1082    OS << ": ";
1083  }
1084  OS << Message;
1085
1086  if (TheDecl && isa<NamedDecl>(TheDecl)) {
1087    std::string Name = cast<NamedDecl>(TheDecl)->getNameAsString();
1088    if (!Name.empty())
1089      OS << " '" << Name << '\'';
1090  }
1091
1092  OS << '\n';
1093}
1094
1095/// \brief Figure out if an expression could be turned into a call.
1096///
1097/// Use this when trying to recover from an error where the programmer may have
1098/// written just the name of a function instead of actually calling it.
1099///
1100/// \param E - The expression to examine.
1101/// \param ZeroArgCallReturnTy - If the expression can be turned into a call
1102///  with no arguments, this parameter is set to the type returned by such a
1103///  call; otherwise, it is set to an empty QualType.
1104/// \param OverloadSet - If the expression is an overloaded function
1105///  name, this parameter is populated with the decls of the various overloads.
1106bool Sema::isExprCallable(const Expr &E, QualType &ZeroArgCallReturnTy,
1107                          UnresolvedSetImpl &OverloadSet) {
1108  ZeroArgCallReturnTy = QualType();
1109  OverloadSet.clear();
1110
1111  if (E.getType() == Context.OverloadTy) {
1112    OverloadExpr::FindResult FR = OverloadExpr::find(const_cast<Expr*>(&E));
1113    const OverloadExpr *Overloads = FR.Expression;
1114
1115    for (OverloadExpr::decls_iterator it = Overloads->decls_begin(),
1116         DeclsEnd = Overloads->decls_end(); it != DeclsEnd; ++it) {
1117      OverloadSet.addDecl(*it);
1118
1119      // Check whether the function is a non-template which takes no
1120      // arguments.
1121      if (const FunctionDecl *OverloadDecl
1122            = dyn_cast<FunctionDecl>((*it)->getUnderlyingDecl())) {
1123        if (OverloadDecl->getMinRequiredArguments() == 0)
1124          ZeroArgCallReturnTy = OverloadDecl->getResultType();
1125      }
1126    }
1127
1128    // Ignore overloads that are pointer-to-member constants.
1129    if (FR.HasFormOfMemberPointer)
1130      return false;
1131
1132    return true;
1133  }
1134
1135  if (const DeclRefExpr *DeclRef = dyn_cast<DeclRefExpr>(E.IgnoreParens())) {
1136    if (const FunctionDecl *Fun = dyn_cast<FunctionDecl>(DeclRef->getDecl())) {
1137      if (Fun->getMinRequiredArguments() == 0)
1138        ZeroArgCallReturnTy = Fun->getResultType();
1139      return true;
1140    }
1141  }
1142
1143  // We don't have an expression that's convenient to get a FunctionDecl from,
1144  // but we can at least check if the type is "function of 0 arguments".
1145  QualType ExprTy = E.getType();
1146  const FunctionType *FunTy = NULL;
1147  QualType PointeeTy = ExprTy->getPointeeType();
1148  if (!PointeeTy.isNull())
1149    FunTy = PointeeTy->getAs<FunctionType>();
1150  if (!FunTy)
1151    FunTy = ExprTy->getAs<FunctionType>();
1152  if (!FunTy && ExprTy == Context.BoundMemberTy) {
1153    // Look for the bound-member type.  If it's still overloaded, give up,
1154    // although we probably should have fallen into the OverloadExpr case above
1155    // if we actually have an overloaded bound member.
1156    QualType BoundMemberTy = Expr::findBoundMemberType(&E);
1157    if (!BoundMemberTy.isNull())
1158      FunTy = BoundMemberTy->castAs<FunctionType>();
1159  }
1160
1161  if (const FunctionProtoType *FPT =
1162      dyn_cast_or_null<FunctionProtoType>(FunTy)) {
1163    if (FPT->getNumArgs() == 0)
1164      ZeroArgCallReturnTy = FunTy->getResultType();
1165    return true;
1166  }
1167  return false;
1168}
1169
1170/// \brief Give notes for a set of overloads.
1171///
1172/// A companion to isExprCallable. In cases when the name that the programmer
1173/// wrote was an overloaded function, we may be able to make some guesses about
1174/// plausible overloads based on their return types; such guesses can be handed
1175/// off to this method to be emitted as notes.
1176///
1177/// \param Overloads - The overloads to note.
1178/// \param FinalNoteLoc - If we've suppressed printing some overloads due to
1179///  -fshow-overloads=best, this is the location to attach to the note about too
1180///  many candidates. Typically this will be the location of the original
1181///  ill-formed expression.
1182static void noteOverloads(Sema &S, const UnresolvedSetImpl &Overloads,
1183                          const SourceLocation FinalNoteLoc) {
1184  int ShownOverloads = 0;
1185  int SuppressedOverloads = 0;
1186  for (UnresolvedSetImpl::iterator It = Overloads.begin(),
1187       DeclsEnd = Overloads.end(); It != DeclsEnd; ++It) {
1188    // FIXME: Magic number for max shown overloads stolen from
1189    // OverloadCandidateSet::NoteCandidates.
1190    if (ShownOverloads >= 4 && S.Diags.getShowOverloads() == Ovl_Best) {
1191      ++SuppressedOverloads;
1192      continue;
1193    }
1194
1195    NamedDecl *Fn = (*It)->getUnderlyingDecl();
1196    S.Diag(Fn->getLocation(), diag::note_possible_target_of_call);
1197    ++ShownOverloads;
1198  }
1199
1200  if (SuppressedOverloads)
1201    S.Diag(FinalNoteLoc, diag::note_ovl_too_many_candidates)
1202      << SuppressedOverloads;
1203}
1204
1205static void notePlausibleOverloads(Sema &S, SourceLocation Loc,
1206                                   const UnresolvedSetImpl &Overloads,
1207                                   bool (*IsPlausibleResult)(QualType)) {
1208  if (!IsPlausibleResult)
1209    return noteOverloads(S, Overloads, Loc);
1210
1211  UnresolvedSet<2> PlausibleOverloads;
1212  for (OverloadExpr::decls_iterator It = Overloads.begin(),
1213         DeclsEnd = Overloads.end(); It != DeclsEnd; ++It) {
1214    const FunctionDecl *OverloadDecl = cast<FunctionDecl>(*It);
1215    QualType OverloadResultTy = OverloadDecl->getResultType();
1216    if (IsPlausibleResult(OverloadResultTy))
1217      PlausibleOverloads.addDecl(It.getDecl());
1218  }
1219  noteOverloads(S, PlausibleOverloads, Loc);
1220}
1221
1222/// Determine whether the given expression can be called by just
1223/// putting parentheses after it.  Notably, expressions with unary
1224/// operators can't be because the unary operator will start parsing
1225/// outside the call.
1226static bool IsCallableWithAppend(Expr *E) {
1227  E = E->IgnoreImplicit();
1228  return (!isa<CStyleCastExpr>(E) &&
1229          !isa<UnaryOperator>(E) &&
1230          !isa<BinaryOperator>(E) &&
1231          !isa<CXXOperatorCallExpr>(E));
1232}
1233
1234bool Sema::tryToRecoverWithCall(ExprResult &E, const PartialDiagnostic &PD,
1235                                bool ForceComplain,
1236                                bool (*IsPlausibleResult)(QualType)) {
1237  SourceLocation Loc = E.get()->getExprLoc();
1238  SourceRange Range = E.get()->getSourceRange();
1239
1240  QualType ZeroArgCallTy;
1241  UnresolvedSet<4> Overloads;
1242  if (isExprCallable(*E.get(), ZeroArgCallTy, Overloads) &&
1243      !ZeroArgCallTy.isNull() &&
1244      (!IsPlausibleResult || IsPlausibleResult(ZeroArgCallTy))) {
1245    // At this point, we know E is potentially callable with 0
1246    // arguments and that it returns something of a reasonable type,
1247    // so we can emit a fixit and carry on pretending that E was
1248    // actually a CallExpr.
1249    SourceLocation ParenInsertionLoc =
1250      PP.getLocForEndOfToken(Range.getEnd());
1251    Diag(Loc, PD)
1252      << /*zero-arg*/ 1 << Range
1253      << (IsCallableWithAppend(E.get())
1254          ? FixItHint::CreateInsertion(ParenInsertionLoc, "()")
1255          : FixItHint());
1256    notePlausibleOverloads(*this, Loc, Overloads, IsPlausibleResult);
1257
1258    // FIXME: Try this before emitting the fixit, and suppress diagnostics
1259    // while doing so.
1260    E = ActOnCallExpr(0, E.take(), ParenInsertionLoc,
1261                      MultiExprArg(), ParenInsertionLoc.getLocWithOffset(1));
1262    return true;
1263  }
1264
1265  if (!ForceComplain) return false;
1266
1267  Diag(Loc, PD) << /*not zero-arg*/ 0 << Range;
1268  notePlausibleOverloads(*this, Loc, Overloads, IsPlausibleResult);
1269  E = ExprError();
1270  return true;
1271}
1272