Sema.cpp revision c50a0e3900f1b44503be48457508af372f4dd05a 
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/ObjCMethodList.h"
26#include "clang/Sema/PrettyDeclStackTrace.h"
27#include "clang/Sema/Scope.h"
28#include "clang/Sema/ScopeInfo.h"
29#include "clang/Sema/SemaConsumer.h"
30#include "clang/AST/ASTContext.h"
31#include "clang/AST/ASTDiagnostic.h"
32#include "clang/AST/DeclCXX.h"
33#include "clang/AST/DeclFriend.h"
34#include "clang/AST/DeclObjC.h"
35#include "clang/AST/Expr.h"
36#include "clang/AST/ExprCXX.h"
37#include "clang/AST/StmtCXX.h"
38#include "clang/Lex/HeaderSearch.h"
39#include "clang/Lex/Preprocessor.h"
40#include "clang/Basic/FileManager.h"
41#include "clang/Basic/PartialDiagnostic.h"
42#include "clang/Basic/TargetInfo.h"
43using namespace clang;
44using namespace sema;
45
46FunctionScopeInfo::~FunctionScopeInfo() { }
47
48void FunctionScopeInfo::Clear() {
49  HasBranchProtectedScope = false;
50  HasBranchIntoScope = false;
51  HasIndirectGoto = false;
52
53  SwitchStack.clear();
54  Returns.clear();
55  ErrorTrap.reset();
56  PossiblyUnreachableDiags.clear();
57}
58
59BlockScopeInfo::~BlockScopeInfo() { }
60LambdaScopeInfo::~LambdaScopeInfo() { }
61
62PrintingPolicy Sema::getPrintingPolicy(const ASTContext &Context,
63                                       const Preprocessor &PP) {
64  PrintingPolicy Policy = Context.getPrintingPolicy();
65  Policy.Bool = Context.getLangOpts().Bool;
66  if (!Policy.Bool) {
67    if (MacroInfo *BoolMacro = PP.getMacroInfo(&Context.Idents.get("bool"))) {
68      Policy.Bool = BoolMacro->isObjectLike() &&
69        BoolMacro->getNumTokens() == 1 &&
70        BoolMacro->getReplacementToken(0).is(tok::kw__Bool);
71    }
72  }
73
74  return Policy;
75}
76
77void Sema::ActOnTranslationUnitScope(Scope *S) {
78  TUScope = S;
79  PushDeclContext(S, Context.getTranslationUnitDecl());
80
81  VAListTagName = PP.getIdentifierInfo("__va_list_tag");
82}
83
84Sema::Sema(Preprocessor &pp, ASTContext &ctxt, ASTConsumer &consumer,
85           TranslationUnitKind TUKind,
86           CodeCompleteConsumer *CodeCompleter)
87  : TheTargetAttributesSema(0), FPFeatures(pp.getLangOpts()),
88    LangOpts(pp.getLangOpts()), PP(pp), Context(ctxt), Consumer(consumer),
89    Diags(PP.getDiagnostics()), SourceMgr(PP.getSourceManager()),
90    CollectStats(false), ExternalSource(0), CodeCompleter(CodeCompleter),
91    CurContext(0), OriginalLexicalContext(0),
92    PackContext(0), MSStructPragmaOn(false), VisContext(0),
93    ExprNeedsCleanups(false), LateTemplateParser(0), OpaqueParser(0),
94    IdResolver(pp), StdInitializerList(0), CXXTypeInfoDecl(0), MSVCGuidDecl(0),
95    NSNumberDecl(0),
96    NSStringDecl(0), StringWithUTF8StringMethod(0),
97    NSArrayDecl(0), ArrayWithObjectsMethod(0),
98    NSDictionaryDecl(0), DictionaryWithObjectsMethod(0),
99    GlobalNewDeleteDeclared(false),
100    ObjCShouldCallSuperDealloc(false),
101    ObjCShouldCallSuperFinalize(false),
102    TUKind(TUKind),
103    NumSFINAEErrors(0), InFunctionDeclarator(0),
104    AccessCheckingSFINAE(false), InNonInstantiationSFINAEContext(false),
105    NonInstantiationEntries(0), ArgumentPackSubstitutionIndex(-1),
106    CurrentInstantiationScope(0), TyposCorrected(0),
107    AnalysisWarnings(*this)
108{
109  TUScope = 0;
110
111  LoadedExternalKnownNamespaces = false;
112  for (unsigned I = 0; I != NSAPI::NumNSNumberLiteralMethods; ++I)
113    NSNumberLiteralMethods[I] = 0;
114
115  if (getLangOpts().ObjC1)
116    NSAPIObj.reset(new NSAPI(Context));
117
118  if (getLangOpts().CPlusPlus)
119    FieldCollector.reset(new CXXFieldCollector());
120
121  // Tell diagnostics how to render things from the AST library.
122  PP.getDiagnostics().SetArgToStringFn(&FormatASTNodeDiagnosticArgument,
123                                       &Context);
124
125  ExprEvalContexts.push_back(
126        ExpressionEvaluationContextRecord(PotentiallyEvaluated, 0,
127                                          false, 0, false));
128
129  FunctionScopes.push_back(new FunctionScopeInfo(Diags));
130}
131
132void Sema::Initialize() {
133  // Tell the AST consumer about this Sema object.
134  Consumer.Initialize(Context);
135
136  // FIXME: Isn't this redundant with the initialization above?
137  if (SemaConsumer *SC = dyn_cast<SemaConsumer>(&Consumer))
138    SC->InitializeSema(*this);
139
140  // Tell the external Sema source about this Sema object.
141  if (ExternalSemaSource *ExternalSema
142      = dyn_cast_or_null<ExternalSemaSource>(Context.getExternalSource()))
143    ExternalSema->InitializeSema(*this);
144
145  // Initialize predefined 128-bit integer types, if needed.
146  if (PP.getTargetInfo().getPointerWidth(0) >= 64) {
147    // If either of the 128-bit integer types are unavailable to name lookup,
148    // define them now.
149    DeclarationName Int128 = &Context.Idents.get("__int128_t");
150    if (IdResolver.begin(Int128) == IdResolver.end())
151      PushOnScopeChains(Context.getInt128Decl(), TUScope);
152
153    DeclarationName UInt128 = &Context.Idents.get("__uint128_t");
154    if (IdResolver.begin(UInt128) == IdResolver.end())
155      PushOnScopeChains(Context.getUInt128Decl(), TUScope);
156  }
157
158
159  // Initialize predefined Objective-C types:
160  if (PP.getLangOpts().ObjC1) {
161    // If 'SEL' does not yet refer to any declarations, make it refer to the
162    // predefined 'SEL'.
163    DeclarationName SEL = &Context.Idents.get("SEL");
164    if (IdResolver.begin(SEL) == IdResolver.end())
165      PushOnScopeChains(Context.getObjCSelDecl(), TUScope);
166
167    // If 'id' does not yet refer to any declarations, make it refer to the
168    // predefined 'id'.
169    DeclarationName Id = &Context.Idents.get("id");
170    if (IdResolver.begin(Id) == IdResolver.end())
171      PushOnScopeChains(Context.getObjCIdDecl(), TUScope);
172
173    // Create the built-in typedef for 'Class'.
174    DeclarationName Class = &Context.Idents.get("Class");
175    if (IdResolver.begin(Class) == IdResolver.end())
176      PushOnScopeChains(Context.getObjCClassDecl(), TUScope);
177
178    // Create the built-in forward declaratino for 'Protocol'.
179    DeclarationName Protocol = &Context.Idents.get("Protocol");
180    if (IdResolver.begin(Protocol) == IdResolver.end())
181      PushOnScopeChains(Context.getObjCProtocolDecl(), TUScope);
182  }
183
184  DeclarationName BuiltinVaList = &Context.Idents.get("__builtin_va_list");
185  if (IdResolver.begin(BuiltinVaList) == IdResolver.end())
186    PushOnScopeChains(Context.getBuiltinVaListDecl(), TUScope);
187}
188
189Sema::~Sema() {
190  if (PackContext) FreePackedContext();
191  if (VisContext) FreeVisContext();
192  delete TheTargetAttributesSema;
193  MSStructPragmaOn = false;
194  // Kill all the active scopes.
195  for (unsigned I = 1, E = FunctionScopes.size(); I != E; ++I)
196    delete FunctionScopes[I];
197  if (FunctionScopes.size() == 1)
198    delete FunctionScopes[0];
199
200  // Tell the SemaConsumer to forget about us; we're going out of scope.
201  if (SemaConsumer *SC = dyn_cast<SemaConsumer>(&Consumer))
202    SC->ForgetSema();
203
204  // Detach from the external Sema source.
205  if (ExternalSemaSource *ExternalSema
206        = dyn_cast_or_null<ExternalSemaSource>(Context.getExternalSource()))
207    ExternalSema->ForgetSema();
208}
209
210/// makeUnavailableInSystemHeader - There is an error in the current
211/// context.  If we're still in a system header, and we can plausibly
212/// make the relevant declaration unavailable instead of erroring, do
213/// so and return true.
214bool Sema::makeUnavailableInSystemHeader(SourceLocation loc,
215                                         StringRef msg) {
216  // If we're not in a function, it's an error.
217  FunctionDecl *fn = dyn_cast<FunctionDecl>(CurContext);
218  if (!fn) return false;
219
220  // If we're in template instantiation, it's an error.
221  if (!ActiveTemplateInstantiations.empty())
222    return false;
223
224  // If that function's not in a system header, it's an error.
225  if (!Context.getSourceManager().isInSystemHeader(loc))
226    return false;
227
228  // If the function is already unavailable, it's not an error.
229  if (fn->hasAttr<UnavailableAttr>()) return true;
230
231  fn->addAttr(new (Context) UnavailableAttr(loc, Context, msg));
232  return true;
233}
234
235ASTMutationListener *Sema::getASTMutationListener() const {
236  return getASTConsumer().GetASTMutationListener();
237}
238
239/// \brief Print out statistics about the semantic analysis.
240void Sema::PrintStats() const {
241  llvm::errs() << "\n*** Semantic Analysis Stats:\n";
242  llvm::errs() << NumSFINAEErrors << " SFINAE diagnostics trapped.\n";
243
244  BumpAlloc.PrintStats();
245  AnalysisWarnings.PrintStats();
246}
247
248/// ImpCastExprToType - If Expr is not of type 'Type', insert an implicit cast.
249/// If there is already an implicit cast, merge into the existing one.
250/// The result is of the given category.
251ExprResult Sema::ImpCastExprToType(Expr *E, QualType Ty,
252                                   CastKind Kind, ExprValueKind VK,
253                                   const CXXCastPath *BasePath,
254                                   CheckedConversionKind CCK) {
255#ifndef NDEBUG
256  if (VK == VK_RValue && !E->isRValue()) {
257    switch (Kind) {
258    default:
259      assert(0 && "can't implicitly cast lvalue to rvalue with this cast kind");
260    case CK_LValueToRValue:
261    case CK_ArrayToPointerDecay:
262    case CK_FunctionToPointerDecay:
263    case CK_ToVoid:
264      break;
265    }
266  }
267  assert((VK == VK_RValue || !E->isRValue()) && "can't cast rvalue to lvalue");
268#endif
269
270  QualType ExprTy = Context.getCanonicalType(E->getType());
271  QualType TypeTy = Context.getCanonicalType(Ty);
272
273  if (ExprTy == TypeTy)
274    return Owned(E);
275
276  if (getLangOpts().ObjCAutoRefCount)
277    CheckObjCARCConversion(SourceRange(), Ty, E, CCK);
278
279  // If this is a derived-to-base cast to a through a virtual base, we
280  // need a vtable.
281  if (Kind == CK_DerivedToBase &&
282      BasePathInvolvesVirtualBase(*BasePath)) {
283    QualType T = E->getType();
284    if (const PointerType *Pointer = T->getAs<PointerType>())
285      T = Pointer->getPointeeType();
286    if (const RecordType *RecordTy = T->getAs<RecordType>())
287      MarkVTableUsed(E->getLocStart(),
288                     cast<CXXRecordDecl>(RecordTy->getDecl()));
289  }
290
291  if (ImplicitCastExpr *ImpCast = dyn_cast<ImplicitCastExpr>(E)) {
292    if (ImpCast->getCastKind() == Kind && (!BasePath || BasePath->empty())) {
293      ImpCast->setType(Ty);
294      ImpCast->setValueKind(VK);
295      return Owned(E);
296    }
297  }
298
299  return Owned(ImplicitCastExpr::Create(Context, Ty, Kind, E, BasePath, VK));
300}
301
302/// ScalarTypeToBooleanCastKind - Returns the cast kind corresponding
303/// to the conversion from scalar type ScalarTy to the Boolean type.
304CastKind Sema::ScalarTypeToBooleanCastKind(QualType ScalarTy) {
305  switch (ScalarTy->getScalarTypeKind()) {
306  case Type::STK_Bool: return CK_NoOp;
307  case Type::STK_CPointer: return CK_PointerToBoolean;
308  case Type::STK_BlockPointer: return CK_PointerToBoolean;
309  case Type::STK_ObjCObjectPointer: return CK_PointerToBoolean;
310  case Type::STK_MemberPointer: return CK_MemberPointerToBoolean;
311  case Type::STK_Integral: return CK_IntegralToBoolean;
312  case Type::STK_Floating: return CK_FloatingToBoolean;
313  case Type::STK_IntegralComplex: return CK_IntegralComplexToBoolean;
314  case Type::STK_FloatingComplex: return CK_FloatingComplexToBoolean;
315  }
316  return CK_Invalid;
317}
318
319/// \brief Used to prune the decls of Sema's UnusedFileScopedDecls vector.
320static bool ShouldRemoveFromUnused(Sema *SemaRef, const DeclaratorDecl *D) {
321  if (D->isUsed())
322    return true;
323
324  if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
325    // UnusedFileScopedDecls stores the first declaration.
326    // The declaration may have become definition so check again.
327    const FunctionDecl *DeclToCheck;
328    if (FD->hasBody(DeclToCheck))
329      return !SemaRef->ShouldWarnIfUnusedFileScopedDecl(DeclToCheck);
330
331    // Later redecls may add new information resulting in not having to warn,
332    // so check again.
333    DeclToCheck = FD->getMostRecentDecl();
334    if (DeclToCheck != FD)
335      return !SemaRef->ShouldWarnIfUnusedFileScopedDecl(DeclToCheck);
336  }
337
338  if (const VarDecl *VD = dyn_cast<VarDecl>(D)) {
339    // UnusedFileScopedDecls stores the first declaration.
340    // The declaration may have become definition so check again.
341    const VarDecl *DeclToCheck = VD->getDefinition();
342    if (DeclToCheck)
343      return !SemaRef->ShouldWarnIfUnusedFileScopedDecl(DeclToCheck);
344
345    // Later redecls may add new information resulting in not having to warn,
346    // so check again.
347    DeclToCheck = VD->getMostRecentDecl();
348    if (DeclToCheck != VD)
349      return !SemaRef->ShouldWarnIfUnusedFileScopedDecl(DeclToCheck);
350  }
351
352  return false;
353}
354
355namespace {
356  struct UndefinedInternal {
357    NamedDecl *decl;
358    FullSourceLoc useLoc;
359
360    UndefinedInternal(NamedDecl *decl, FullSourceLoc useLoc)
361      : decl(decl), useLoc(useLoc) {}
362  };
363
364  bool operator<(const UndefinedInternal &l, const UndefinedInternal &r) {
365    return l.useLoc.isBeforeInTranslationUnitThan(r.useLoc);
366  }
367}
368
369/// checkUndefinedInternals - Check for undefined objects with internal linkage.
370static void checkUndefinedInternals(Sema &S) {
371  if (S.UndefinedInternals.empty()) return;
372
373  // Collect all the still-undefined entities with internal linkage.
374  SmallVector<UndefinedInternal, 16> undefined;
375  for (llvm::DenseMap<NamedDecl*,SourceLocation>::iterator
376         i = S.UndefinedInternals.begin(), e = S.UndefinedInternals.end();
377       i != e; ++i) {
378    NamedDecl *decl = i->first;
379
380    // Ignore attributes that have become invalid.
381    if (decl->isInvalidDecl()) continue;
382
383    // __attribute__((weakref)) is basically a definition.
384    if (decl->hasAttr<WeakRefAttr>()) continue;
385
386    if (FunctionDecl *fn = dyn_cast<FunctionDecl>(decl)) {
387      if (fn->isPure() || fn->hasBody())
388        continue;
389    } else {
390      if (cast<VarDecl>(decl)->hasDefinition() != VarDecl::DeclarationOnly)
391        continue;
392    }
393
394    // We build a FullSourceLoc so that we can sort with array_pod_sort.
395    FullSourceLoc loc(i->second, S.Context.getSourceManager());
396    undefined.push_back(UndefinedInternal(decl, loc));
397  }
398
399  if (undefined.empty()) return;
400
401  // Sort (in order of use site) so that we're not (as) dependent on
402  // the iteration order through an llvm::DenseMap.
403  llvm::array_pod_sort(undefined.begin(), undefined.end());
404
405  for (SmallVectorImpl<UndefinedInternal>::iterator
406         i = undefined.begin(), e = undefined.end(); i != e; ++i) {
407    NamedDecl *decl = i->decl;
408    S.Diag(decl->getLocation(), diag::warn_undefined_internal)
409      << isa<VarDecl>(decl) << decl;
410    S.Diag(i->useLoc, diag::note_used_here);
411  }
412}
413
414void Sema::LoadExternalWeakUndeclaredIdentifiers() {
415  if (!ExternalSource)
416    return;
417
418  SmallVector<std::pair<IdentifierInfo *, WeakInfo>, 4> WeakIDs;
419  ExternalSource->ReadWeakUndeclaredIdentifiers(WeakIDs);
420  for (unsigned I = 0, N = WeakIDs.size(); I != N; ++I) {
421    llvm::DenseMap<IdentifierInfo*,WeakInfo>::iterator Pos
422      = WeakUndeclaredIdentifiers.find(WeakIDs[I].first);
423    if (Pos != WeakUndeclaredIdentifiers.end())
424      continue;
425
426    WeakUndeclaredIdentifiers.insert(WeakIDs[I]);
427  }
428}
429
430
431typedef llvm::DenseMap<const CXXRecordDecl*, bool> RecordCompleteMap;
432
433/// \brief Returns true, if all methods and nested classes of the given
434/// CXXRecordDecl are defined in this translation unit.
435///
436/// Should only be called from ActOnEndOfTranslationUnit so that all
437/// definitions are actually read.
438static bool MethodsAndNestedClassesComplete(const CXXRecordDecl *RD,
439                                            RecordCompleteMap &MNCComplete) {
440  RecordCompleteMap::iterator Cache = MNCComplete.find(RD);
441  if (Cache != MNCComplete.end())
442    return Cache->second;
443  if (!RD->isCompleteDefinition())
444    return false;
445  bool Complete = true;
446  for (DeclContext::decl_iterator I = RD->decls_begin(),
447                                  E = RD->decls_end();
448       I != E && Complete; ++I) {
449    if (const CXXMethodDecl *M = dyn_cast<CXXMethodDecl>(*I))
450      Complete = M->isDefined() || (M->isPure() && !isa<CXXDestructorDecl>(M));
451    else if (const FunctionTemplateDecl *F = dyn_cast<FunctionTemplateDecl>(*I))
452      Complete = F->getTemplatedDecl()->isDefined();
453    else if (const CXXRecordDecl *R = dyn_cast<CXXRecordDecl>(*I)) {
454      if (R->isInjectedClassName())
455        continue;
456      if (R->hasDefinition())
457        Complete = MethodsAndNestedClassesComplete(R->getDefinition(),
458                                                   MNCComplete);
459      else
460        Complete = false;
461    }
462  }
463  MNCComplete[RD] = Complete;
464  return Complete;
465}
466
467/// \brief Returns true, if the given CXXRecordDecl is fully defined in this
468/// translation unit, i.e. all methods are defined or pure virtual and all
469/// friends, friend functions and nested classes are fully defined in this
470/// translation unit.
471///
472/// Should only be called from ActOnEndOfTranslationUnit so that all
473/// definitions are actually read.
474static bool IsRecordFullyDefined(const CXXRecordDecl *RD,
475                                 RecordCompleteMap &RecordsComplete,
476                                 RecordCompleteMap &MNCComplete) {
477  RecordCompleteMap::iterator Cache = RecordsComplete.find(RD);
478  if (Cache != RecordsComplete.end())
479    return Cache->second;
480  bool Complete = MethodsAndNestedClassesComplete(RD, MNCComplete);
481  for (CXXRecordDecl::friend_iterator I = RD->friend_begin(),
482                                      E = RD->friend_end();
483       I != E && Complete; ++I) {
484    // Check if friend classes and methods are complete.
485    if (TypeSourceInfo *TSI = (*I)->getFriendType()) {
486      // Friend classes are available as the TypeSourceInfo of the FriendDecl.
487      if (CXXRecordDecl *FriendD = TSI->getType()->getAsCXXRecordDecl())
488        Complete = MethodsAndNestedClassesComplete(FriendD, MNCComplete);
489      else
490        Complete = false;
491    } else {
492      // Friend functions are available through the NamedDecl of FriendDecl.
493      if (const FunctionDecl *FD =
494          dyn_cast<FunctionDecl>((*I)->getFriendDecl()))
495        Complete = FD->isDefined();
496      else
497        // This is a template friend, give up.
498        Complete = false;
499    }
500  }
501  RecordsComplete[RD] = Complete;
502  return Complete;
503}
504
505/// ActOnEndOfTranslationUnit - This is called at the very end of the
506/// translation unit when EOF is reached and all but the top-level scope is
507/// popped.
508void Sema::ActOnEndOfTranslationUnit() {
509  assert(DelayedDiagnostics.getCurrentPool() == NULL
510         && "reached end of translation unit with a pool attached?");
511
512  // Only complete translation units define vtables and perform implicit
513  // instantiations.
514  if (TUKind == TU_Complete) {
515    DiagnoseUseOfUnimplementedSelectors();
516
517    // If any dynamic classes have their key function defined within
518    // this translation unit, then those vtables are considered "used" and must
519    // be emitted.
520    for (DynamicClassesType::iterator I = DynamicClasses.begin(ExternalSource),
521                                      E = DynamicClasses.end();
522         I != E; ++I) {
523      assert(!(*I)->isDependentType() &&
524             "Should not see dependent types here!");
525      if (const CXXMethodDecl *KeyFunction = Context.getKeyFunction(*I)) {
526        const FunctionDecl *Definition = 0;
527        if (KeyFunction->hasBody(Definition))
528          MarkVTableUsed(Definition->getLocation(), *I, true);
529      }
530    }
531
532    // If DefinedUsedVTables ends up marking any virtual member functions it
533    // might lead to more pending template instantiations, which we then need
534    // to instantiate.
535    DefineUsedVTables();
536
537    // C++: Perform implicit template instantiations.
538    //
539    // FIXME: When we perform these implicit instantiations, we do not
540    // carefully keep track of the point of instantiation (C++ [temp.point]).
541    // This means that name lookup that occurs within the template
542    // instantiation will always happen at the end of the translation unit,
543    // so it will find some names that should not be found. Although this is
544    // common behavior for C++ compilers, it is technically wrong. In the
545    // future, we either need to be able to filter the results of name lookup
546    // or we need to perform template instantiations earlier.
547    PerformPendingInstantiations();
548  }
549
550  // Remove file scoped decls that turned out to be used.
551  UnusedFileScopedDecls.erase(std::remove_if(UnusedFileScopedDecls.begin(0,
552                                                                         true),
553                                             UnusedFileScopedDecls.end(),
554                              std::bind1st(std::ptr_fun(ShouldRemoveFromUnused),
555                                           this)),
556                              UnusedFileScopedDecls.end());
557
558  if (TUKind == TU_Prefix) {
559    // Translation unit prefixes don't need any of the checking below.
560    TUScope = 0;
561    return;
562  }
563
564  // Check for #pragma weak identifiers that were never declared
565  // FIXME: This will cause diagnostics to be emitted in a non-determinstic
566  // order!  Iterating over a densemap like this is bad.
567  LoadExternalWeakUndeclaredIdentifiers();
568  for (llvm::DenseMap<IdentifierInfo*,WeakInfo>::iterator
569       I = WeakUndeclaredIdentifiers.begin(),
570       E = WeakUndeclaredIdentifiers.end(); I != E; ++I) {
571    if (I->second.getUsed()) continue;
572
573    Diag(I->second.getLocation(), diag::warn_weak_identifier_undeclared)
574      << I->first;
575  }
576
577  if (TUKind == TU_Module) {
578    // If we are building a module, resolve all of the exported declarations
579    // now.
580    if (Module *CurrentModule = PP.getCurrentModule()) {
581      ModuleMap &ModMap = PP.getHeaderSearchInfo().getModuleMap();
582
583      llvm::SmallVector<Module *, 2> Stack;
584      Stack.push_back(CurrentModule);
585      while (!Stack.empty()) {
586        Module *Mod = Stack.back();
587        Stack.pop_back();
588
589        // Resolve the exported declarations.
590        // FIXME: Actually complain, once we figure out how to teach the
591        // diagnostic client to deal with complains in the module map at this
592        // point.
593        ModMap.resolveExports(Mod, /*Complain=*/false);
594
595        // Queue the submodules, so their exports will also be resolved.
596        for (Module::submodule_iterator Sub = Mod->submodule_begin(),
597                                     SubEnd = Mod->submodule_end();
598             Sub != SubEnd; ++Sub) {
599          Stack.push_back(*Sub);
600        }
601      }
602    }
603
604    // Modules don't need any of the checking below.
605    TUScope = 0;
606    return;
607  }
608
609  // C99 6.9.2p2:
610  //   A declaration of an identifier for an object that has file
611  //   scope without an initializer, and without a storage-class
612  //   specifier or with the storage-class specifier static,
613  //   constitutes a tentative definition. If a translation unit
614  //   contains one or more tentative definitions for an identifier,
615  //   and the translation unit contains no external definition for
616  //   that identifier, then the behavior is exactly as if the
617  //   translation unit contains a file scope declaration of that
618  //   identifier, with the composite type as of the end of the
619  //   translation unit, with an initializer equal to 0.
620  llvm::SmallSet<VarDecl *, 32> Seen;
621  for (TentativeDefinitionsType::iterator
622            T = TentativeDefinitions.begin(ExternalSource),
623         TEnd = TentativeDefinitions.end();
624       T != TEnd; ++T)
625  {
626    VarDecl *VD = (*T)->getActingDefinition();
627
628    // If the tentative definition was completed, getActingDefinition() returns
629    // null. If we've already seen this variable before, insert()'s second
630    // return value is false.
631    if (VD == 0 || VD->isInvalidDecl() || !Seen.insert(VD))
632      continue;
633
634    if (const IncompleteArrayType *ArrayT
635        = Context.getAsIncompleteArrayType(VD->getType())) {
636      if (RequireCompleteType(VD->getLocation(),
637                              ArrayT->getElementType(),
638                              diag::err_tentative_def_incomplete_type_arr)) {
639        VD->setInvalidDecl();
640        continue;
641      }
642
643      // Set the length of the array to 1 (C99 6.9.2p5).
644      Diag(VD->getLocation(), diag::warn_tentative_incomplete_array);
645      llvm::APInt One(Context.getTypeSize(Context.getSizeType()), true);
646      QualType T = Context.getConstantArrayType(ArrayT->getElementType(),
647                                                One, ArrayType::Normal, 0);
648      VD->setType(T);
649    } else if (RequireCompleteType(VD->getLocation(), VD->getType(),
650                                   diag::err_tentative_def_incomplete_type))
651      VD->setInvalidDecl();
652
653    // Notify the consumer that we've completed a tentative definition.
654    if (!VD->isInvalidDecl())
655      Consumer.CompleteTentativeDefinition(VD);
656
657  }
658
659  if (LangOpts.CPlusPlus0x &&
660      Diags.getDiagnosticLevel(diag::warn_delegating_ctor_cycle,
661                               SourceLocation())
662        != DiagnosticsEngine::Ignored)
663    CheckDelegatingCtorCycles();
664
665  // If there were errors, disable 'unused' warnings since they will mostly be
666  // noise.
667  if (!Diags.hasErrorOccurred()) {
668    // Output warning for unused file scoped decls.
669    for (UnusedFileScopedDeclsType::iterator
670           I = UnusedFileScopedDecls.begin(ExternalSource),
671           E = UnusedFileScopedDecls.end(); I != E; ++I) {
672      if (ShouldRemoveFromUnused(this, *I))
673        continue;
674
675      if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(*I)) {
676        const FunctionDecl *DiagD;
677        if (!FD->hasBody(DiagD))
678          DiagD = FD;
679        if (DiagD->isDeleted())
680          continue; // Deleted functions are supposed to be unused.
681        if (DiagD->isReferenced()) {
682          if (isa<CXXMethodDecl>(DiagD))
683            Diag(DiagD->getLocation(), diag::warn_unneeded_member_function)
684                  << DiagD->getDeclName();
685          else {
686            if (FD->getStorageClassAsWritten() == SC_Static &&
687                !FD->isInlineSpecified() &&
688                !SourceMgr.isFromMainFile(
689                   SourceMgr.getExpansionLoc(FD->getLocation())))
690              Diag(DiagD->getLocation(), diag::warn_unneeded_static_internal_decl)
691                << DiagD->getDeclName();
692            else
693              Diag(DiagD->getLocation(), diag::warn_unneeded_internal_decl)
694                   << /*function*/0 << DiagD->getDeclName();
695          }
696        } else {
697          Diag(DiagD->getLocation(),
698               isa<CXXMethodDecl>(DiagD) ? diag::warn_unused_member_function
699                                         : diag::warn_unused_function)
700                << DiagD->getDeclName();
701        }
702      } else {
703        const VarDecl *DiagD = cast<VarDecl>(*I)->getDefinition();
704        if (!DiagD)
705          DiagD = cast<VarDecl>(*I);
706        if (DiagD->isReferenced()) {
707          Diag(DiagD->getLocation(), diag::warn_unneeded_internal_decl)
708                << /*variable*/1 << DiagD->getDeclName();
709        } else {
710          Diag(DiagD->getLocation(), diag::warn_unused_variable)
711                << DiagD->getDeclName();
712        }
713      }
714    }
715
716    checkUndefinedInternals(*this);
717  }
718
719  if (Diags.getDiagnosticLevel(diag::warn_unused_private_field,
720                               SourceLocation())
721        != DiagnosticsEngine::Ignored) {
722    RecordCompleteMap RecordsComplete;
723    RecordCompleteMap MNCComplete;
724    for (NamedDeclSetType::iterator I = UnusedPrivateFields.begin(),
725         E = UnusedPrivateFields.end(); I != E; ++I) {
726      const NamedDecl *D = *I;
727      const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(D->getDeclContext());
728      if (RD && !RD->isUnion() &&
729          IsRecordFullyDefined(RD, RecordsComplete, MNCComplete)) {
730        Diag(D->getLocation(), diag::warn_unused_private_field)
731              << D->getDeclName();
732      }
733    }
734  }
735
736  // Check we've noticed that we're no longer parsing the initializer for every
737  // variable. If we miss cases, then at best we have a performance issue and
738  // at worst a rejects-valid bug.
739  assert(ParsingInitForAutoVars.empty() &&
740         "Didn't unmark var as having its initializer parsed");
741
742  TUScope = 0;
743}
744
745
746//===----------------------------------------------------------------------===//
747// Helper functions.
748//===----------------------------------------------------------------------===//
749
750DeclContext *Sema::getFunctionLevelDeclContext() {
751  DeclContext *DC = CurContext;
752
753  while (true) {
754    if (isa<BlockDecl>(DC) || isa<EnumDecl>(DC)) {
755      DC = DC->getParent();
756    } else if (isa<CXXMethodDecl>(DC) &&
757               cast<CXXMethodDecl>(DC)->getOverloadedOperator() == OO_Call &&
758               cast<CXXRecordDecl>(DC->getParent())->isLambda()) {
759      DC = DC->getParent()->getParent();
760    }
761    else break;
762  }
763
764  return DC;
765}
766
767/// getCurFunctionDecl - If inside of a function body, this returns a pointer
768/// to the function decl for the function being parsed.  If we're currently
769/// in a 'block', this returns the containing context.
770FunctionDecl *Sema::getCurFunctionDecl() {
771  DeclContext *DC = getFunctionLevelDeclContext();
772  return dyn_cast<FunctionDecl>(DC);
773}
774
775ObjCMethodDecl *Sema::getCurMethodDecl() {
776  DeclContext *DC = getFunctionLevelDeclContext();
777  return dyn_cast<ObjCMethodDecl>(DC);
778}
779
780NamedDecl *Sema::getCurFunctionOrMethodDecl() {
781  DeclContext *DC = getFunctionLevelDeclContext();
782  if (isa<ObjCMethodDecl>(DC) || isa<FunctionDecl>(DC))
783    return cast<NamedDecl>(DC);
784  return 0;
785}
786
787void Sema::EmitCurrentDiagnostic(unsigned DiagID) {
788  // FIXME: It doesn't make sense to me that DiagID is an incoming argument here
789  // and yet we also use the current diag ID on the DiagnosticsEngine. This has
790  // been made more painfully obvious by the refactor that introduced this
791  // function, but it is possible that the incoming argument can be
792  // eliminnated. If it truly cannot be (for example, there is some reentrancy
793  // issue I am not seeing yet), then there should at least be a clarifying
794  // comment somewhere.
795  if (llvm::Optional<TemplateDeductionInfo*> Info = isSFINAEContext()) {
796    switch (DiagnosticIDs::getDiagnosticSFINAEResponse(
797              Diags.getCurrentDiagID())) {
798    case DiagnosticIDs::SFINAE_Report:
799      // We'll report the diagnostic below.
800      break;
801
802    case DiagnosticIDs::SFINAE_SubstitutionFailure:
803      // Count this failure so that we know that template argument deduction
804      // has failed.
805      ++NumSFINAEErrors;
806
807      // Make a copy of this suppressed diagnostic and store it with the
808      // template-deduction information.
809      if (*Info && !(*Info)->hasSFINAEDiagnostic()) {
810        Diagnostic DiagInfo(&Diags);
811        (*Info)->addSFINAEDiagnostic(DiagInfo.getLocation(),
812                       PartialDiagnostic(DiagInfo, Context.getDiagAllocator()));
813      }
814
815      Diags.setLastDiagnosticIgnored();
816      Diags.Clear();
817      return;
818
819    case DiagnosticIDs::SFINAE_AccessControl: {
820      // Per C++ Core Issue 1170, access control is part of SFINAE.
821      // Additionally, the AccessCheckingSFINAE flag can be used to temporarily
822      // make access control a part of SFINAE for the purposes of checking
823      // type traits.
824      if (!AccessCheckingSFINAE && !getLangOpts().CPlusPlus0x)
825        break;
826
827      SourceLocation Loc = Diags.getCurrentDiagLoc();
828
829      // Suppress this diagnostic.
830      ++NumSFINAEErrors;
831
832      // Make a copy of this suppressed diagnostic and store it with the
833      // template-deduction information.
834      if (*Info && !(*Info)->hasSFINAEDiagnostic()) {
835        Diagnostic DiagInfo(&Diags);
836        (*Info)->addSFINAEDiagnostic(DiagInfo.getLocation(),
837                       PartialDiagnostic(DiagInfo, Context.getDiagAllocator()));
838      }
839
840      Diags.setLastDiagnosticIgnored();
841      Diags.Clear();
842
843      // Now the diagnostic state is clear, produce a C++98 compatibility
844      // warning.
845      Diag(Loc, diag::warn_cxx98_compat_sfinae_access_control);
846
847      // The last diagnostic which Sema produced was ignored. Suppress any
848      // notes attached to it.
849      Diags.setLastDiagnosticIgnored();
850      return;
851    }
852
853    case DiagnosticIDs::SFINAE_Suppress:
854      // Make a copy of this suppressed diagnostic and store it with the
855      // template-deduction information;
856      if (*Info) {
857        Diagnostic DiagInfo(&Diags);
858        (*Info)->addSuppressedDiagnostic(DiagInfo.getLocation(),
859                       PartialDiagnostic(DiagInfo, Context.getDiagAllocator()));
860      }
861
862      // Suppress this diagnostic.
863      Diags.setLastDiagnosticIgnored();
864      Diags.Clear();
865      return;
866    }
867  }
868
869  // Set up the context's printing policy based on our current state.
870  Context.setPrintingPolicy(getPrintingPolicy());
871
872  // Emit the diagnostic.
873  if (!Diags.EmitCurrentDiagnostic())
874    return;
875
876  // If this is not a note, and we're in a template instantiation
877  // that is different from the last template instantiation where
878  // we emitted an error, print a template instantiation
879  // backtrace.
880  if (!DiagnosticIDs::isBuiltinNote(DiagID) &&
881      !ActiveTemplateInstantiations.empty() &&
882      ActiveTemplateInstantiations.back()
883        != LastTemplateInstantiationErrorContext) {
884    PrintInstantiationStack();
885    LastTemplateInstantiationErrorContext = ActiveTemplateInstantiations.back();
886  }
887}
888
889Sema::SemaDiagnosticBuilder
890Sema::Diag(SourceLocation Loc, const PartialDiagnostic& PD) {
891  SemaDiagnosticBuilder Builder(Diag(Loc, PD.getDiagID()));
892  PD.Emit(Builder);
893
894  return Builder;
895}
896
897/// \brief Looks through the macro-expansion chain for the given
898/// location, looking for a macro expansion with the given name.
899/// If one is found, returns true and sets the location to that
900/// expansion loc.
901bool Sema::findMacroSpelling(SourceLocation &locref, StringRef name) {
902  SourceLocation loc = locref;
903  if (!loc.isMacroID()) return false;
904
905  // There's no good way right now to look at the intermediate
906  // expansions, so just jump to the expansion location.
907  loc = getSourceManager().getExpansionLoc(loc);
908
909  // If that's written with the name, stop here.
910  SmallVector<char, 16> buffer;
911  if (getPreprocessor().getSpelling(loc, buffer) == name) {
912    locref = loc;
913    return true;
914  }
915  return false;
916}
917
918/// \brief Determines the active Scope associated with the given declaration
919/// context.
920///
921/// This routine maps a declaration context to the active Scope object that
922/// represents that declaration context in the parser. It is typically used
923/// from "scope-less" code (e.g., template instantiation, lazy creation of
924/// declarations) that injects a name for name-lookup purposes and, therefore,
925/// must update the Scope.
926///
927/// \returns The scope corresponding to the given declaraion context, or NULL
928/// if no such scope is open.
929Scope *Sema::getScopeForContext(DeclContext *Ctx) {
930
931  if (!Ctx)
932    return 0;
933
934  Ctx = Ctx->getPrimaryContext();
935  for (Scope *S = getCurScope(); S; S = S->getParent()) {
936    // Ignore scopes that cannot have declarations. This is important for
937    // out-of-line definitions of static class members.
938    if (S->getFlags() & (Scope::DeclScope | Scope::TemplateParamScope))
939      if (DeclContext *Entity = static_cast<DeclContext *> (S->getEntity()))
940        if (Ctx == Entity->getPrimaryContext())
941          return S;
942  }
943
944  return 0;
945}
946
947/// \brief Enter a new function scope
948void Sema::PushFunctionScope() {
949  if (FunctionScopes.size() == 1) {
950    // Use the "top" function scope rather than having to allocate
951    // memory for a new scope.
952    FunctionScopes.back()->Clear();
953    FunctionScopes.push_back(FunctionScopes.back());
954    return;
955  }
956
957  FunctionScopes.push_back(new FunctionScopeInfo(getDiagnostics()));
958}
959
960void Sema::PushBlockScope(Scope *BlockScope, BlockDecl *Block) {
961  FunctionScopes.push_back(new BlockScopeInfo(getDiagnostics(),
962                                              BlockScope, Block));
963}
964
965void Sema::PushLambdaScope(CXXRecordDecl *Lambda,
966                           CXXMethodDecl *CallOperator) {
967  FunctionScopes.push_back(new LambdaScopeInfo(getDiagnostics(), Lambda,
968                                               CallOperator));
969}
970
971void Sema::PopFunctionScopeInfo(const AnalysisBasedWarnings::Policy *WP,
972                                const Decl *D, const BlockExpr *blkExpr) {
973  FunctionScopeInfo *Scope = FunctionScopes.pop_back_val();
974  assert(!FunctionScopes.empty() && "mismatched push/pop!");
975
976  // Issue any analysis-based warnings.
977  if (WP && D)
978    AnalysisWarnings.IssueWarnings(*WP, Scope, D, blkExpr);
979  else {
980    for (SmallVectorImpl<sema::PossiblyUnreachableDiag>::iterator
981         i = Scope->PossiblyUnreachableDiags.begin(),
982         e = Scope->PossiblyUnreachableDiags.end();
983         i != e; ++i) {
984      const sema::PossiblyUnreachableDiag &D = *i;
985      Diag(D.Loc, D.PD);
986    }
987  }
988
989  if (FunctionScopes.back() != Scope) {
990    delete Scope;
991  }
992}
993
994void Sema::PushCompoundScope() {
995  getCurFunction()->CompoundScopes.push_back(CompoundScopeInfo());
996}
997
998void Sema::PopCompoundScope() {
999  FunctionScopeInfo *CurFunction = getCurFunction();
1000  assert(!CurFunction->CompoundScopes.empty() && "mismatched push/pop");
1001
1002  CurFunction->CompoundScopes.pop_back();
1003}
1004
1005/// \brief Determine whether any errors occurred within this function/method/
1006/// block.
1007bool Sema::hasAnyUnrecoverableErrorsInThisFunction() const {
1008  return getCurFunction()->ErrorTrap.hasUnrecoverableErrorOccurred();
1009}
1010
1011BlockScopeInfo *Sema::getCurBlock() {
1012  if (FunctionScopes.empty())
1013    return 0;
1014
1015  return dyn_cast<BlockScopeInfo>(FunctionScopes.back());
1016}
1017
1018LambdaScopeInfo *Sema::getCurLambda() {
1019  if (FunctionScopes.empty())
1020    return 0;
1021
1022  return dyn_cast<LambdaScopeInfo>(FunctionScopes.back());
1023}
1024
1025void Sema::ActOnComment(SourceRange Comment) {
1026  RawComment RC(SourceMgr, Comment);
1027  if (RC.isAlmostTrailingComment()) {
1028    SourceRange MagicMarkerRange(Comment.getBegin(),
1029                                 Comment.getBegin().getLocWithOffset(3));
1030    StringRef MagicMarkerText;
1031    switch (RC.getKind()) {
1032    case RawComment::RCK_OrdinaryBCPL:
1033      MagicMarkerText = "///<";
1034      break;
1035    case RawComment::RCK_OrdinaryC:
1036      MagicMarkerText = "/**<";
1037      break;
1038    default:
1039      llvm_unreachable("if this is an almost Doxygen comment, "
1040                       "it should be ordinary");
1041    }
1042    Diag(Comment.getBegin(), diag::warn_not_a_doxygen_trailing_member_comment) <<
1043      FixItHint::CreateReplacement(MagicMarkerRange, MagicMarkerText);
1044  }
1045  Context.addComment(RC);
1046}
1047
1048// Pin this vtable to this file.
1049ExternalSemaSource::~ExternalSemaSource() {}
1050
1051void ExternalSemaSource::ReadMethodPool(Selector Sel) { }
1052
1053void ExternalSemaSource::ReadKnownNamespaces(
1054                           SmallVectorImpl<NamespaceDecl *> &Namespaces) {
1055}
1056
1057void PrettyDeclStackTraceEntry::print(raw_ostream &OS) const {
1058  SourceLocation Loc = this->Loc;
1059  if (!Loc.isValid() && TheDecl) Loc = TheDecl->getLocation();
1060  if (Loc.isValid()) {
1061    Loc.print(OS, S.getSourceManager());
1062    OS << ": ";
1063  }
1064  OS << Message;
1065
1066  if (TheDecl && isa<NamedDecl>(TheDecl)) {
1067    std::string Name = cast<NamedDecl>(TheDecl)->getNameAsString();
1068    if (!Name.empty())
1069      OS << " '" << Name << '\'';
1070  }
1071
1072  OS << '\n';
1073}
1074
1075/// \brief Figure out if an expression could be turned into a call.
1076///
1077/// Use this when trying to recover from an error where the programmer may have
1078/// written just the name of a function instead of actually calling it.
1079///
1080/// \param E - The expression to examine.
1081/// \param ZeroArgCallReturnTy - If the expression can be turned into a call
1082///  with no arguments, this parameter is set to the type returned by such a
1083///  call; otherwise, it is set to an empty QualType.
1084/// \param OverloadSet - If the expression is an overloaded function
1085///  name, this parameter is populated with the decls of the various overloads.
1086bool Sema::isExprCallable(const Expr &E, QualType &ZeroArgCallReturnTy,
1087                          UnresolvedSetImpl &OverloadSet) {
1088  ZeroArgCallReturnTy = QualType();
1089  OverloadSet.clear();
1090
1091  if (E.getType() == Context.OverloadTy) {
1092    OverloadExpr::FindResult FR = OverloadExpr::find(const_cast<Expr*>(&E));
1093    const OverloadExpr *Overloads = FR.Expression;
1094
1095    for (OverloadExpr::decls_iterator it = Overloads->decls_begin(),
1096         DeclsEnd = Overloads->decls_end(); it != DeclsEnd; ++it) {
1097      OverloadSet.addDecl(*it);
1098
1099      // Check whether the function is a non-template which takes no
1100      // arguments.
1101      if (const FunctionDecl *OverloadDecl
1102            = dyn_cast<FunctionDecl>((*it)->getUnderlyingDecl())) {
1103        if (OverloadDecl->getMinRequiredArguments() == 0)
1104          ZeroArgCallReturnTy = OverloadDecl->getResultType();
1105      }
1106    }
1107
1108    // Ignore overloads that are pointer-to-member constants.
1109    if (FR.HasFormOfMemberPointer)
1110      return false;
1111
1112    return true;
1113  }
1114
1115  if (const DeclRefExpr *DeclRef = dyn_cast<DeclRefExpr>(E.IgnoreParens())) {
1116    if (const FunctionDecl *Fun = dyn_cast<FunctionDecl>(DeclRef->getDecl())) {
1117      if (Fun->getMinRequiredArguments() == 0)
1118        ZeroArgCallReturnTy = Fun->getResultType();
1119      return true;
1120    }
1121  }
1122
1123  // We don't have an expression that's convenient to get a FunctionDecl from,
1124  // but we can at least check if the type is "function of 0 arguments".
1125  QualType ExprTy = E.getType();
1126  const FunctionType *FunTy = NULL;
1127  QualType PointeeTy = ExprTy->getPointeeType();
1128  if (!PointeeTy.isNull())
1129    FunTy = PointeeTy->getAs<FunctionType>();
1130  if (!FunTy)
1131    FunTy = ExprTy->getAs<FunctionType>();
1132  if (!FunTy && ExprTy == Context.BoundMemberTy) {
1133    // Look for the bound-member type.  If it's still overloaded, give up,
1134    // although we probably should have fallen into the OverloadExpr case above
1135    // if we actually have an overloaded bound member.
1136    QualType BoundMemberTy = Expr::findBoundMemberType(&E);
1137    if (!BoundMemberTy.isNull())
1138      FunTy = BoundMemberTy->castAs<FunctionType>();
1139  }
1140
1141  if (const FunctionProtoType *FPT =
1142      dyn_cast_or_null<FunctionProtoType>(FunTy)) {
1143    if (FPT->getNumArgs() == 0)
1144      ZeroArgCallReturnTy = FunTy->getResultType();
1145    return true;
1146  }
1147  return false;
1148}
1149
1150/// \brief Give notes for a set of overloads.
1151///
1152/// A companion to isExprCallable. In cases when the name that the programmer
1153/// wrote was an overloaded function, we may be able to make some guesses about
1154/// plausible overloads based on their return types; such guesses can be handed
1155/// off to this method to be emitted as notes.
1156///
1157/// \param Overloads - The overloads to note.
1158/// \param FinalNoteLoc - If we've suppressed printing some overloads due to
1159///  -fshow-overloads=best, this is the location to attach to the note about too
1160///  many candidates. Typically this will be the location of the original
1161///  ill-formed expression.
1162static void noteOverloads(Sema &S, const UnresolvedSetImpl &Overloads,
1163                          const SourceLocation FinalNoteLoc) {
1164  int ShownOverloads = 0;
1165  int SuppressedOverloads = 0;
1166  for (UnresolvedSetImpl::iterator It = Overloads.begin(),
1167       DeclsEnd = Overloads.end(); It != DeclsEnd; ++It) {
1168    // FIXME: Magic number for max shown overloads stolen from
1169    // OverloadCandidateSet::NoteCandidates.
1170    if (ShownOverloads >= 4 &&
1171        S.Diags.getShowOverloads() == DiagnosticsEngine::Ovl_Best) {
1172      ++SuppressedOverloads;
1173      continue;
1174    }
1175
1176    NamedDecl *Fn = (*It)->getUnderlyingDecl();
1177    S.Diag(Fn->getLocation(), diag::note_possible_target_of_call);
1178    ++ShownOverloads;
1179  }
1180
1181  if (SuppressedOverloads)
1182    S.Diag(FinalNoteLoc, diag::note_ovl_too_many_candidates)
1183      << SuppressedOverloads;
1184}
1185
1186static void notePlausibleOverloads(Sema &S, SourceLocation Loc,
1187                                   const UnresolvedSetImpl &Overloads,
1188                                   bool (*IsPlausibleResult)(QualType)) {
1189  if (!IsPlausibleResult)
1190    return noteOverloads(S, Overloads, Loc);
1191
1192  UnresolvedSet<2> PlausibleOverloads;
1193  for (OverloadExpr::decls_iterator It = Overloads.begin(),
1194         DeclsEnd = Overloads.end(); It != DeclsEnd; ++It) {
1195    const FunctionDecl *OverloadDecl = cast<FunctionDecl>(*It);
1196    QualType OverloadResultTy = OverloadDecl->getResultType();
1197    if (IsPlausibleResult(OverloadResultTy))
1198      PlausibleOverloads.addDecl(It.getDecl());
1199  }
1200  noteOverloads(S, PlausibleOverloads, Loc);
1201}
1202
1203/// Determine whether the given expression can be called by just
1204/// putting parentheses after it.  Notably, expressions with unary
1205/// operators can't be because the unary operator will start parsing
1206/// outside the call.
1207static bool IsCallableWithAppend(Expr *E) {
1208  E = E->IgnoreImplicit();
1209  return (!isa<CStyleCastExpr>(E) &&
1210          !isa<UnaryOperator>(E) &&
1211          !isa<BinaryOperator>(E) &&
1212          !isa<CXXOperatorCallExpr>(E));
1213}
1214
1215bool Sema::tryToRecoverWithCall(ExprResult &E, const PartialDiagnostic &PD,
1216                                bool ForceComplain,
1217                                bool (*IsPlausibleResult)(QualType)) {
1218  SourceLocation Loc = E.get()->getExprLoc();
1219  SourceRange Range = E.get()->getSourceRange();
1220
1221  QualType ZeroArgCallTy;
1222  UnresolvedSet<4> Overloads;
1223  if (isExprCallable(*E.get(), ZeroArgCallTy, Overloads) &&
1224      !ZeroArgCallTy.isNull() &&
1225      (!IsPlausibleResult || IsPlausibleResult(ZeroArgCallTy))) {
1226    // At this point, we know E is potentially callable with 0
1227    // arguments and that it returns something of a reasonable type,
1228    // so we can emit a fixit and carry on pretending that E was
1229    // actually a CallExpr.
1230    SourceLocation ParenInsertionLoc =
1231      PP.getLocForEndOfToken(Range.getEnd());
1232    Diag(Loc, PD)
1233      << /*zero-arg*/ 1 << Range
1234      << (IsCallableWithAppend(E.get())
1235          ? FixItHint::CreateInsertion(ParenInsertionLoc, "()")
1236          : FixItHint());
1237    notePlausibleOverloads(*this, Loc, Overloads, IsPlausibleResult);
1238
1239    // FIXME: Try this before emitting the fixit, and suppress diagnostics
1240    // while doing so.
1241    E = ActOnCallExpr(0, E.take(), ParenInsertionLoc,
1242                      MultiExprArg(*this, 0, 0),
1243                      ParenInsertionLoc.getLocWithOffset(1));
1244    return true;
1245  }
1246
1247  if (!ForceComplain) return false;
1248
1249  Diag(Loc, PD) << /*not zero-arg*/ 0 << Range;
1250  notePlausibleOverloads(*this, Loc, Overloads, IsPlausibleResult);
1251  E = ExprError();
1252  return true;
1253}
1254