Sema.cpp revision 4ceaf337be78fa89b4a97f351be6d0bda962d7de 
1//===--- Sema.cpp - AST Builder and Semantic Analysis Implementation ------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This file implements the actions class which performs semantic analysis and
11// builds an AST out of a parse stream.
12//
13//===----------------------------------------------------------------------===//
14
15#include "clang/Sema/SemaInternal.h"
16#include "TargetAttributesSema.h"
17#include "clang/AST/ASTContext.h"
18#include "clang/AST/ASTDiagnostic.h"
19#include "clang/AST/DeclCXX.h"
20#include "clang/AST/DeclFriend.h"
21#include "clang/AST/DeclObjC.h"
22#include "clang/AST/Expr.h"
23#include "clang/AST/ExprCXX.h"
24#include "clang/AST/StmtCXX.h"
25#include "clang/Basic/FileManager.h"
26#include "clang/Basic/PartialDiagnostic.h"
27#include "clang/Basic/TargetInfo.h"
28#include "clang/Lex/HeaderSearch.h"
29#include "clang/Lex/Preprocessor.h"
30#include "clang/Sema/CXXFieldCollector.h"
31#include "clang/Sema/DelayedDiagnostic.h"
32#include "clang/Sema/ExternalSemaSource.h"
33#include "clang/Sema/MultiplexExternalSemaSource.h"
34#include "clang/Sema/ObjCMethodList.h"
35#include "clang/Sema/PrettyDeclStackTrace.h"
36#include "clang/Sema/Scope.h"
37#include "clang/Sema/ScopeInfo.h"
38#include "clang/Sema/SemaConsumer.h"
39#include "clang/Sema/TemplateDeduction.h"
40#include "llvm/ADT/APFloat.h"
41#include "llvm/ADT/DenseMap.h"
42#include "llvm/ADT/SmallSet.h"
43#include "llvm/Support/CrashRecoveryContext.h"
44using namespace clang;
45using namespace sema;
46
47PrintingPolicy Sema::getPrintingPolicy(const ASTContext &Context,
48                                       const Preprocessor &PP) {
49  PrintingPolicy Policy = Context.getPrintingPolicy();
50  Policy.Bool = Context.getLangOpts().Bool;
51  if (!Policy.Bool) {
52    if (MacroInfo *BoolMacro = PP.getMacroInfo(&Context.Idents.get("bool"))) {
53      Policy.Bool = BoolMacro->isObjectLike() &&
54        BoolMacro->getNumTokens() == 1 &&
55        BoolMacro->getReplacementToken(0).is(tok::kw__Bool);
56    }
57  }
58
59  return Policy;
60}
61
62void Sema::ActOnTranslationUnitScope(Scope *S) {
63  TUScope = S;
64  PushDeclContext(S, Context.getTranslationUnitDecl());
65
66  VAListTagName = PP.getIdentifierInfo("__va_list_tag");
67}
68
69Sema::Sema(Preprocessor &pp, ASTContext &ctxt, ASTConsumer &consumer,
70           TranslationUnitKind TUKind,
71           CodeCompleteConsumer *CodeCompleter)
72  : TheTargetAttributesSema(0), ExternalSource(0),
73    isMultiplexExternalSource(false), FPFeatures(pp.getLangOpts()),
74    LangOpts(pp.getLangOpts()), PP(pp), Context(ctxt), Consumer(consumer),
75    Diags(PP.getDiagnostics()), SourceMgr(PP.getSourceManager()),
76    CollectStats(false), CodeCompleter(CodeCompleter),
77    CurContext(0), OriginalLexicalContext(0),
78    PackContext(0), MSStructPragmaOn(false), VisContext(0),
79    IsBuildingRecoveryCallExpr(false),
80    ExprNeedsCleanups(false), LateTemplateParser(0), OpaqueParser(0),
81    IdResolver(pp), StdInitializerList(0), CXXTypeInfoDecl(0), MSVCGuidDecl(0),
82    NSNumberDecl(0),
83    NSStringDecl(0), StringWithUTF8StringMethod(0),
84    NSArrayDecl(0), ArrayWithObjectsMethod(0),
85    NSDictionaryDecl(0), DictionaryWithObjectsMethod(0),
86    GlobalNewDeleteDeclared(false),
87    TUKind(TUKind),
88    NumSFINAEErrors(0), InFunctionDeclarator(0),
89    AccessCheckingSFINAE(false), InNonInstantiationSFINAEContext(false),
90    NonInstantiationEntries(0), ArgumentPackSubstitutionIndex(-1),
91    CurrentInstantiationScope(0), TyposCorrected(0),
92    AnalysisWarnings(*this)
93{
94  TUScope = 0;
95
96  LoadedExternalKnownNamespaces = false;
97  for (unsigned I = 0; I != NSAPI::NumNSNumberLiteralMethods; ++I)
98    NSNumberLiteralMethods[I] = 0;
99
100  if (getLangOpts().ObjC1)
101    NSAPIObj.reset(new NSAPI(Context));
102
103  if (getLangOpts().CPlusPlus)
104    FieldCollector.reset(new CXXFieldCollector());
105
106  // Tell diagnostics how to render things from the AST library.
107  PP.getDiagnostics().SetArgToStringFn(&FormatASTNodeDiagnosticArgument,
108                                       &Context);
109
110  ExprEvalContexts.push_back(
111        ExpressionEvaluationContextRecord(PotentiallyEvaluated, 0,
112                                          false, 0, false));
113
114  FunctionScopes.push_back(new FunctionScopeInfo(Diags));
115}
116
117void Sema::Initialize() {
118  // Tell the AST consumer about this Sema object.
119  Consumer.Initialize(Context);
120
121  // FIXME: Isn't this redundant with the initialization above?
122  if (SemaConsumer *SC = dyn_cast<SemaConsumer>(&Consumer))
123    SC->InitializeSema(*this);
124
125  // Tell the external Sema source about this Sema object.
126  if (ExternalSemaSource *ExternalSema
127      = dyn_cast_or_null<ExternalSemaSource>(Context.getExternalSource()))
128    ExternalSema->InitializeSema(*this);
129
130  // Initialize predefined 128-bit integer types, if needed.
131  if (PP.getTargetInfo().hasInt128Type()) {
132    // If either of the 128-bit integer types are unavailable to name lookup,
133    // define them now.
134    DeclarationName Int128 = &Context.Idents.get("__int128_t");
135    if (IdResolver.begin(Int128) == IdResolver.end())
136      PushOnScopeChains(Context.getInt128Decl(), TUScope);
137
138    DeclarationName UInt128 = &Context.Idents.get("__uint128_t");
139    if (IdResolver.begin(UInt128) == IdResolver.end())
140      PushOnScopeChains(Context.getUInt128Decl(), TUScope);
141  }
142
143
144  // Initialize predefined Objective-C types:
145  if (PP.getLangOpts().ObjC1) {
146    // If 'SEL' does not yet refer to any declarations, make it refer to the
147    // predefined 'SEL'.
148    DeclarationName SEL = &Context.Idents.get("SEL");
149    if (IdResolver.begin(SEL) == IdResolver.end())
150      PushOnScopeChains(Context.getObjCSelDecl(), TUScope);
151
152    // If 'id' does not yet refer to any declarations, make it refer to the
153    // predefined 'id'.
154    DeclarationName Id = &Context.Idents.get("id");
155    if (IdResolver.begin(Id) == IdResolver.end())
156      PushOnScopeChains(Context.getObjCIdDecl(), TUScope);
157
158    // Create the built-in typedef for 'Class'.
159    DeclarationName Class = &Context.Idents.get("Class");
160    if (IdResolver.begin(Class) == IdResolver.end())
161      PushOnScopeChains(Context.getObjCClassDecl(), TUScope);
162
163    // Create the built-in forward declaratino for 'Protocol'.
164    DeclarationName Protocol = &Context.Idents.get("Protocol");
165    if (IdResolver.begin(Protocol) == IdResolver.end())
166      PushOnScopeChains(Context.getObjCProtocolDecl(), TUScope);
167  }
168
169  DeclarationName BuiltinVaList = &Context.Idents.get("__builtin_va_list");
170  if (IdResolver.begin(BuiltinVaList) == IdResolver.end())
171    PushOnScopeChains(Context.getBuiltinVaListDecl(), TUScope);
172}
173
174Sema::~Sema() {
175  if (PackContext) FreePackedContext();
176  if (VisContext) FreeVisContext();
177  delete TheTargetAttributesSema;
178  MSStructPragmaOn = false;
179  // Kill all the active scopes.
180  for (unsigned I = 1, E = FunctionScopes.size(); I != E; ++I)
181    delete FunctionScopes[I];
182  if (FunctionScopes.size() == 1)
183    delete FunctionScopes[0];
184
185  // Tell the SemaConsumer to forget about us; we're going out of scope.
186  if (SemaConsumer *SC = dyn_cast<SemaConsumer>(&Consumer))
187    SC->ForgetSema();
188
189  // Detach from the external Sema source.
190  if (ExternalSemaSource *ExternalSema
191        = dyn_cast_or_null<ExternalSemaSource>(Context.getExternalSource()))
192    ExternalSema->ForgetSema();
193
194  // If Sema's ExternalSource is the multiplexer - we own it.
195  if (isMultiplexExternalSource)
196    delete ExternalSource;
197}
198
199/// makeUnavailableInSystemHeader - There is an error in the current
200/// context.  If we're still in a system header, and we can plausibly
201/// make the relevant declaration unavailable instead of erroring, do
202/// so and return true.
203bool Sema::makeUnavailableInSystemHeader(SourceLocation loc,
204                                         StringRef msg) {
205  // If we're not in a function, it's an error.
206  FunctionDecl *fn = dyn_cast<FunctionDecl>(CurContext);
207  if (!fn) return false;
208
209  // If we're in template instantiation, it's an error.
210  if (!ActiveTemplateInstantiations.empty())
211    return false;
212
213  // If that function's not in a system header, it's an error.
214  if (!Context.getSourceManager().isInSystemHeader(loc))
215    return false;
216
217  // If the function is already unavailable, it's not an error.
218  if (fn->hasAttr<UnavailableAttr>()) return true;
219
220  fn->addAttr(new (Context) UnavailableAttr(loc, Context, msg));
221  return true;
222}
223
224ASTMutationListener *Sema::getASTMutationListener() const {
225  return getASTConsumer().GetASTMutationListener();
226}
227
228///\brief Registers an external source. If an external source already exists,
229/// creates a multiplex external source and appends to it.
230///
231///\param[in] E - A non-null external sema source.
232///
233void Sema::addExternalSource(ExternalSemaSource *E) {
234  assert(E && "Cannot use with NULL ptr");
235
236  if (!ExternalSource) {
237    ExternalSource = E;
238    return;
239  }
240
241  if (isMultiplexExternalSource)
242    static_cast<MultiplexExternalSemaSource*>(ExternalSource)->addSource(*E);
243  else {
244    ExternalSource = new MultiplexExternalSemaSource(*ExternalSource, *E);
245    isMultiplexExternalSource = true;
246  }
247}
248
249/// \brief Print out statistics about the semantic analysis.
250void Sema::PrintStats() const {
251  llvm::errs() << "\n*** Semantic Analysis Stats:\n";
252  llvm::errs() << NumSFINAEErrors << " SFINAE diagnostics trapped.\n";
253
254  BumpAlloc.PrintStats();
255  AnalysisWarnings.PrintStats();
256}
257
258/// ImpCastExprToType - If Expr is not of type 'Type', insert an implicit cast.
259/// If there is already an implicit cast, merge into the existing one.
260/// The result is of the given category.
261ExprResult Sema::ImpCastExprToType(Expr *E, QualType Ty,
262                                   CastKind Kind, ExprValueKind VK,
263                                   const CXXCastPath *BasePath,
264                                   CheckedConversionKind CCK) {
265#ifndef NDEBUG
266  if (VK == VK_RValue && !E->isRValue()) {
267    switch (Kind) {
268    default:
269      assert(0 && "can't implicitly cast lvalue to rvalue with this cast kind");
270    case CK_LValueToRValue:
271    case CK_ArrayToPointerDecay:
272    case CK_FunctionToPointerDecay:
273    case CK_ToVoid:
274      break;
275    }
276  }
277  assert((VK == VK_RValue || !E->isRValue()) && "can't cast rvalue to lvalue");
278#endif
279
280  QualType ExprTy = Context.getCanonicalType(E->getType());
281  QualType TypeTy = Context.getCanonicalType(Ty);
282
283  if (ExprTy == TypeTy)
284    return Owned(E);
285
286  if (getLangOpts().ObjCAutoRefCount)
287    CheckObjCARCConversion(SourceRange(), Ty, E, CCK);
288
289  // If this is a derived-to-base cast to a through a virtual base, we
290  // need a vtable.
291  if (Kind == CK_DerivedToBase &&
292      BasePathInvolvesVirtualBase(*BasePath)) {
293    QualType T = E->getType();
294    if (const PointerType *Pointer = T->getAs<PointerType>())
295      T = Pointer->getPointeeType();
296    if (const RecordType *RecordTy = T->getAs<RecordType>())
297      MarkVTableUsed(E->getLocStart(),
298                     cast<CXXRecordDecl>(RecordTy->getDecl()));
299  }
300
301  if (ImplicitCastExpr *ImpCast = dyn_cast<ImplicitCastExpr>(E)) {
302    if (ImpCast->getCastKind() == Kind && (!BasePath || BasePath->empty())) {
303      ImpCast->setType(Ty);
304      ImpCast->setValueKind(VK);
305      return Owned(E);
306    }
307  }
308
309  return Owned(ImplicitCastExpr::Create(Context, Ty, Kind, E, BasePath, VK));
310}
311
312/// ScalarTypeToBooleanCastKind - Returns the cast kind corresponding
313/// to the conversion from scalar type ScalarTy to the Boolean type.
314CastKind Sema::ScalarTypeToBooleanCastKind(QualType ScalarTy) {
315  switch (ScalarTy->getScalarTypeKind()) {
316  case Type::STK_Bool: return CK_NoOp;
317  case Type::STK_CPointer: return CK_PointerToBoolean;
318  case Type::STK_BlockPointer: return CK_PointerToBoolean;
319  case Type::STK_ObjCObjectPointer: return CK_PointerToBoolean;
320  case Type::STK_MemberPointer: return CK_MemberPointerToBoolean;
321  case Type::STK_Integral: return CK_IntegralToBoolean;
322  case Type::STK_Floating: return CK_FloatingToBoolean;
323  case Type::STK_IntegralComplex: return CK_IntegralComplexToBoolean;
324  case Type::STK_FloatingComplex: return CK_FloatingComplexToBoolean;
325  }
326  return CK_Invalid;
327}
328
329/// \brief Used to prune the decls of Sema's UnusedFileScopedDecls vector.
330static bool ShouldRemoveFromUnused(Sema *SemaRef, const DeclaratorDecl *D) {
331  if (D->getMostRecentDecl()->isUsed())
332    return true;
333
334  if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
335    // UnusedFileScopedDecls stores the first declaration.
336    // The declaration may have become definition so check again.
337    const FunctionDecl *DeclToCheck;
338    if (FD->hasBody(DeclToCheck))
339      return !SemaRef->ShouldWarnIfUnusedFileScopedDecl(DeclToCheck);
340
341    // Later redecls may add new information resulting in not having to warn,
342    // so check again.
343    DeclToCheck = FD->getMostRecentDecl();
344    if (DeclToCheck != FD)
345      return !SemaRef->ShouldWarnIfUnusedFileScopedDecl(DeclToCheck);
346  }
347
348  if (const VarDecl *VD = dyn_cast<VarDecl>(D)) {
349    // UnusedFileScopedDecls stores the first declaration.
350    // The declaration may have become definition so check again.
351    const VarDecl *DeclToCheck = VD->getDefinition();
352    if (DeclToCheck)
353      return !SemaRef->ShouldWarnIfUnusedFileScopedDecl(DeclToCheck);
354
355    // Later redecls may add new information resulting in not having to warn,
356    // so check again.
357    DeclToCheck = VD->getMostRecentDecl();
358    if (DeclToCheck != VD)
359      return !SemaRef->ShouldWarnIfUnusedFileScopedDecl(DeclToCheck);
360  }
361
362  if (D->getLinkage() == ExternalLinkage)
363    return true;
364
365  return false;
366}
367
368namespace {
369  struct UndefinedInternal {
370    NamedDecl *decl;
371    FullSourceLoc useLoc;
372
373    UndefinedInternal(NamedDecl *decl, FullSourceLoc useLoc)
374      : decl(decl), useLoc(useLoc) {}
375  };
376}
377
378/// checkUndefinedInternals - Check for undefined objects with internal linkage.
379static void checkUndefinedInternals(Sema &S) {
380  if (S.UndefinedInternals.empty()) return;
381
382  // Collect all the still-undefined entities with internal linkage.
383  SmallVector<UndefinedInternal, 16> undefined;
384  for (llvm::MapVector<NamedDecl*,SourceLocation>::iterator
385         i = S.UndefinedInternals.begin(), e = S.UndefinedInternals.end();
386       i != e; ++i) {
387    NamedDecl *decl = i->first;
388
389    // Ignore attributes that have become invalid.
390    if (decl->isInvalidDecl()) continue;
391
392    // If we found out that the decl is external, don't warn.
393    if (decl->getLinkage() == ExternalLinkage) continue;
394
395    // __attribute__((weakref)) is basically a definition.
396    if (decl->hasAttr<WeakRefAttr>()) continue;
397
398    if (FunctionDecl *fn = dyn_cast<FunctionDecl>(decl)) {
399      if (fn->isDefined())
400        continue;
401    } else {
402      if (cast<VarDecl>(decl)->hasDefinition() != VarDecl::DeclarationOnly)
403        continue;
404    }
405
406    S.Diag(decl->getLocation(), diag::warn_undefined_internal)
407      << isa<VarDecl>(decl) << decl;
408    S.Diag(i->second, diag::note_used_here);
409  }
410}
411
412void Sema::LoadExternalWeakUndeclaredIdentifiers() {
413  if (!ExternalSource)
414    return;
415
416  SmallVector<std::pair<IdentifierInfo *, WeakInfo>, 4> WeakIDs;
417  ExternalSource->ReadWeakUndeclaredIdentifiers(WeakIDs);
418  for (unsigned I = 0, N = WeakIDs.size(); I != N; ++I) {
419    llvm::DenseMap<IdentifierInfo*,WeakInfo>::iterator Pos
420      = WeakUndeclaredIdentifiers.find(WeakIDs[I].first);
421    if (Pos != WeakUndeclaredIdentifiers.end())
422      continue;
423
424    WeakUndeclaredIdentifiers.insert(WeakIDs[I]);
425  }
426}
427
428
429typedef llvm::DenseMap<const CXXRecordDecl*, bool> RecordCompleteMap;
430
431/// \brief Returns true, if all methods and nested classes of the given
432/// CXXRecordDecl are defined in this translation unit.
433///
434/// Should only be called from ActOnEndOfTranslationUnit so that all
435/// definitions are actually read.
436static bool MethodsAndNestedClassesComplete(const CXXRecordDecl *RD,
437                                            RecordCompleteMap &MNCComplete) {
438  RecordCompleteMap::iterator Cache = MNCComplete.find(RD);
439  if (Cache != MNCComplete.end())
440    return Cache->second;
441  if (!RD->isCompleteDefinition())
442    return false;
443  bool Complete = true;
444  for (DeclContext::decl_iterator I = RD->decls_begin(),
445                                  E = RD->decls_end();
446       I != E && Complete; ++I) {
447    if (const CXXMethodDecl *M = dyn_cast<CXXMethodDecl>(*I))
448      Complete = M->isDefined() || (M->isPure() && !isa<CXXDestructorDecl>(M));
449    else if (const FunctionTemplateDecl *F = dyn_cast<FunctionTemplateDecl>(*I))
450      Complete = F->getTemplatedDecl()->isDefined();
451    else if (const CXXRecordDecl *R = dyn_cast<CXXRecordDecl>(*I)) {
452      if (R->isInjectedClassName())
453        continue;
454      if (R->hasDefinition())
455        Complete = MethodsAndNestedClassesComplete(R->getDefinition(),
456                                                   MNCComplete);
457      else
458        Complete = false;
459    }
460  }
461  MNCComplete[RD] = Complete;
462  return Complete;
463}
464
465/// \brief Returns true, if the given CXXRecordDecl is fully defined in this
466/// translation unit, i.e. all methods are defined or pure virtual and all
467/// friends, friend functions and nested classes are fully defined in this
468/// translation unit.
469///
470/// Should only be called from ActOnEndOfTranslationUnit so that all
471/// definitions are actually read.
472static bool IsRecordFullyDefined(const CXXRecordDecl *RD,
473                                 RecordCompleteMap &RecordsComplete,
474                                 RecordCompleteMap &MNCComplete) {
475  RecordCompleteMap::iterator Cache = RecordsComplete.find(RD);
476  if (Cache != RecordsComplete.end())
477    return Cache->second;
478  bool Complete = MethodsAndNestedClassesComplete(RD, MNCComplete);
479  for (CXXRecordDecl::friend_iterator I = RD->friend_begin(),
480                                      E = RD->friend_end();
481       I != E && Complete; ++I) {
482    // Check if friend classes and methods are complete.
483    if (TypeSourceInfo *TSI = (*I)->getFriendType()) {
484      // Friend classes are available as the TypeSourceInfo of the FriendDecl.
485      if (CXXRecordDecl *FriendD = TSI->getType()->getAsCXXRecordDecl())
486        Complete = MethodsAndNestedClassesComplete(FriendD, MNCComplete);
487      else
488        Complete = false;
489    } else {
490      // Friend functions are available through the NamedDecl of FriendDecl.
491      if (const FunctionDecl *FD =
492          dyn_cast<FunctionDecl>((*I)->getFriendDecl()))
493        Complete = FD->isDefined();
494      else
495        // This is a template friend, give up.
496        Complete = false;
497    }
498  }
499  RecordsComplete[RD] = Complete;
500  return Complete;
501}
502
503/// ActOnEndOfTranslationUnit - This is called at the very end of the
504/// translation unit when EOF is reached and all but the top-level scope is
505/// popped.
506void Sema::ActOnEndOfTranslationUnit() {
507  assert(DelayedDiagnostics.getCurrentPool() == NULL
508         && "reached end of translation unit with a pool attached?");
509
510  // If code completion is enabled, don't perform any end-of-translation-unit
511  // work.
512  if (PP.isCodeCompletionEnabled())
513    return;
514
515  // Only complete translation units define vtables and perform implicit
516  // instantiations.
517  if (TUKind == TU_Complete) {
518    DiagnoseUseOfUnimplementedSelectors();
519
520    // If any dynamic classes have their key function defined within
521    // this translation unit, then those vtables are considered "used" and must
522    // be emitted.
523    for (DynamicClassesType::iterator I = DynamicClasses.begin(ExternalSource),
524                                      E = DynamicClasses.end();
525         I != E; ++I) {
526      assert(!(*I)->isDependentType() &&
527             "Should not see dependent types here!");
528      if (const CXXMethodDecl *KeyFunction = Context.getCurrentKeyFunction(*I)) {
529        const FunctionDecl *Definition = 0;
530        if (KeyFunction->hasBody(Definition))
531          MarkVTableUsed(Definition->getLocation(), *I, true);
532      }
533    }
534
535    // If DefinedUsedVTables ends up marking any virtual member functions it
536    // might lead to more pending template instantiations, which we then need
537    // to instantiate.
538    DefineUsedVTables();
539
540    // C++: Perform implicit template instantiations.
541    //
542    // FIXME: When we perform these implicit instantiations, we do not
543    // carefully keep track of the point of instantiation (C++ [temp.point]).
544    // This means that name lookup that occurs within the template
545    // instantiation will always happen at the end of the translation unit,
546    // so it will find some names that should not be found. Although this is
547    // common behavior for C++ compilers, it is technically wrong. In the
548    // future, we either need to be able to filter the results of name lookup
549    // or we need to perform template instantiations earlier.
550    PerformPendingInstantiations();
551  }
552
553  // Remove file scoped decls that turned out to be used.
554  UnusedFileScopedDecls.erase(std::remove_if(UnusedFileScopedDecls.begin(0,
555                                                                         true),
556                                             UnusedFileScopedDecls.end(),
557                              std::bind1st(std::ptr_fun(ShouldRemoveFromUnused),
558                                           this)),
559                              UnusedFileScopedDecls.end());
560
561  if (TUKind == TU_Prefix) {
562    // Translation unit prefixes don't need any of the checking below.
563    TUScope = 0;
564    return;
565  }
566
567  // Check for #pragma weak identifiers that were never declared
568  // FIXME: This will cause diagnostics to be emitted in a non-determinstic
569  // order!  Iterating over a densemap like this is bad.
570  LoadExternalWeakUndeclaredIdentifiers();
571  for (llvm::DenseMap<IdentifierInfo*,WeakInfo>::iterator
572       I = WeakUndeclaredIdentifiers.begin(),
573       E = WeakUndeclaredIdentifiers.end(); I != E; ++I) {
574    if (I->second.getUsed()) continue;
575
576    Diag(I->second.getLocation(), diag::warn_weak_identifier_undeclared)
577      << I->first;
578  }
579
580  if (TUKind == TU_Module) {
581    // If we are building a module, resolve all of the exported declarations
582    // now.
583    if (Module *CurrentModule = PP.getCurrentModule()) {
584      ModuleMap &ModMap = PP.getHeaderSearchInfo().getModuleMap();
585
586      SmallVector<Module *, 2> Stack;
587      Stack.push_back(CurrentModule);
588      while (!Stack.empty()) {
589        Module *Mod = Stack.back();
590        Stack.pop_back();
591
592        // Resolve the exported declarations.
593        // FIXME: Actually complain, once we figure out how to teach the
594        // diagnostic client to deal with complains in the module map at this
595        // point.
596        ModMap.resolveExports(Mod, /*Complain=*/false);
597
598        // Queue the submodules, so their exports will also be resolved.
599        for (Module::submodule_iterator Sub = Mod->submodule_begin(),
600                                     SubEnd = Mod->submodule_end();
601             Sub != SubEnd; ++Sub) {
602          Stack.push_back(*Sub);
603        }
604      }
605    }
606
607    // Modules don't need any of the checking below.
608    TUScope = 0;
609    return;
610  }
611
612  // C99 6.9.2p2:
613  //   A declaration of an identifier for an object that has file
614  //   scope without an initializer, and without a storage-class
615  //   specifier or with the storage-class specifier static,
616  //   constitutes a tentative definition. If a translation unit
617  //   contains one or more tentative definitions for an identifier,
618  //   and the translation unit contains no external definition for
619  //   that identifier, then the behavior is exactly as if the
620  //   translation unit contains a file scope declaration of that
621  //   identifier, with the composite type as of the end of the
622  //   translation unit, with an initializer equal to 0.
623  llvm::SmallSet<VarDecl *, 32> Seen;
624  for (TentativeDefinitionsType::iterator
625            T = TentativeDefinitions.begin(ExternalSource),
626         TEnd = TentativeDefinitions.end();
627       T != TEnd; ++T)
628  {
629    VarDecl *VD = (*T)->getActingDefinition();
630
631    // If the tentative definition was completed, getActingDefinition() returns
632    // null. If we've already seen this variable before, insert()'s second
633    // return value is false.
634    if (VD == 0 || VD->isInvalidDecl() || !Seen.insert(VD))
635      continue;
636
637    if (const IncompleteArrayType *ArrayT
638        = Context.getAsIncompleteArrayType(VD->getType())) {
639      if (RequireCompleteType(VD->getLocation(),
640                              ArrayT->getElementType(),
641                              diag::err_tentative_def_incomplete_type_arr)) {
642        VD->setInvalidDecl();
643        continue;
644      }
645
646      // Set the length of the array to 1 (C99 6.9.2p5).
647      Diag(VD->getLocation(), diag::warn_tentative_incomplete_array);
648      llvm::APInt One(Context.getTypeSize(Context.getSizeType()), true);
649      QualType T = Context.getConstantArrayType(ArrayT->getElementType(),
650                                                One, ArrayType::Normal, 0);
651      VD->setType(T);
652    } else if (RequireCompleteType(VD->getLocation(), VD->getType(),
653                                   diag::err_tentative_def_incomplete_type))
654      VD->setInvalidDecl();
655
656    CheckCompleteVariableDeclaration(VD);
657
658    // Notify the consumer that we've completed a tentative definition.
659    if (!VD->isInvalidDecl())
660      Consumer.CompleteTentativeDefinition(VD);
661
662  }
663
664  if (LangOpts.CPlusPlus11 &&
665      Diags.getDiagnosticLevel(diag::warn_delegating_ctor_cycle,
666                               SourceLocation())
667        != DiagnosticsEngine::Ignored)
668    CheckDelegatingCtorCycles();
669
670  // If there were errors, disable 'unused' warnings since they will mostly be
671  // noise.
672  if (!Diags.hasErrorOccurred()) {
673    // Output warning for unused file scoped decls.
674    for (UnusedFileScopedDeclsType::iterator
675           I = UnusedFileScopedDecls.begin(ExternalSource),
676           E = UnusedFileScopedDecls.end(); I != E; ++I) {
677      if (ShouldRemoveFromUnused(this, *I))
678        continue;
679
680      if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(*I)) {
681        const FunctionDecl *DiagD;
682        if (!FD->hasBody(DiagD))
683          DiagD = FD;
684        if (DiagD->isDeleted())
685          continue; // Deleted functions are supposed to be unused.
686        if (DiagD->isReferenced()) {
687          if (isa<CXXMethodDecl>(DiagD))
688            Diag(DiagD->getLocation(), diag::warn_unneeded_member_function)
689                  << DiagD->getDeclName();
690          else {
691            if (FD->getStorageClassAsWritten() == SC_Static &&
692                !FD->isInlineSpecified() &&
693                !SourceMgr.isFromMainFile(
694                   SourceMgr.getExpansionLoc(FD->getLocation())))
695              Diag(DiagD->getLocation(), diag::warn_unneeded_static_internal_decl)
696                << DiagD->getDeclName();
697            else
698              Diag(DiagD->getLocation(), diag::warn_unneeded_internal_decl)
699                   << /*function*/0 << DiagD->getDeclName();
700          }
701        } else {
702          Diag(DiagD->getLocation(),
703               isa<CXXMethodDecl>(DiagD) ? diag::warn_unused_member_function
704                                         : diag::warn_unused_function)
705                << DiagD->getDeclName();
706        }
707      } else {
708        const VarDecl *DiagD = cast<VarDecl>(*I)->getDefinition();
709        if (!DiagD)
710          DiagD = cast<VarDecl>(*I);
711        if (DiagD->isReferenced()) {
712          Diag(DiagD->getLocation(), diag::warn_unneeded_internal_decl)
713                << /*variable*/1 << DiagD->getDeclName();
714        } else {
715          Diag(DiagD->getLocation(), diag::warn_unused_variable)
716                << DiagD->getDeclName();
717        }
718      }
719    }
720
721    if (ExternalSource)
722      ExternalSource->ReadUndefinedInternals(UndefinedInternals);
723    checkUndefinedInternals(*this);
724  }
725
726  if (Diags.getDiagnosticLevel(diag::warn_unused_private_field,
727                               SourceLocation())
728        != DiagnosticsEngine::Ignored) {
729    RecordCompleteMap RecordsComplete;
730    RecordCompleteMap MNCComplete;
731    for (NamedDeclSetType::iterator I = UnusedPrivateFields.begin(),
732         E = UnusedPrivateFields.end(); I != E; ++I) {
733      const NamedDecl *D = *I;
734      const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(D->getDeclContext());
735      if (RD && !RD->isUnion() &&
736          IsRecordFullyDefined(RD, RecordsComplete, MNCComplete)) {
737        Diag(D->getLocation(), diag::warn_unused_private_field)
738              << D->getDeclName();
739      }
740    }
741  }
742
743  // Check we've noticed that we're no longer parsing the initializer for every
744  // variable. If we miss cases, then at best we have a performance issue and
745  // at worst a rejects-valid bug.
746  assert(ParsingInitForAutoVars.empty() &&
747         "Didn't unmark var as having its initializer parsed");
748
749  TUScope = 0;
750}
751
752
753//===----------------------------------------------------------------------===//
754// Helper functions.
755//===----------------------------------------------------------------------===//
756
757DeclContext *Sema::getFunctionLevelDeclContext() {
758  DeclContext *DC = CurContext;
759
760  while (true) {
761    if (isa<BlockDecl>(DC) || isa<EnumDecl>(DC)) {
762      DC = DC->getParent();
763    } else if (isa<CXXMethodDecl>(DC) &&
764               cast<CXXMethodDecl>(DC)->getOverloadedOperator() == OO_Call &&
765               cast<CXXRecordDecl>(DC->getParent())->isLambda()) {
766      DC = DC->getParent()->getParent();
767    }
768    else break;
769  }
770
771  return DC;
772}
773
774/// getCurFunctionDecl - If inside of a function body, this returns a pointer
775/// to the function decl for the function being parsed.  If we're currently
776/// in a 'block', this returns the containing context.
777FunctionDecl *Sema::getCurFunctionDecl() {
778  DeclContext *DC = getFunctionLevelDeclContext();
779  return dyn_cast<FunctionDecl>(DC);
780}
781
782ObjCMethodDecl *Sema::getCurMethodDecl() {
783  DeclContext *DC = getFunctionLevelDeclContext();
784  return dyn_cast<ObjCMethodDecl>(DC);
785}
786
787NamedDecl *Sema::getCurFunctionOrMethodDecl() {
788  DeclContext *DC = getFunctionLevelDeclContext();
789  if (isa<ObjCMethodDecl>(DC) || isa<FunctionDecl>(DC))
790    return cast<NamedDecl>(DC);
791  return 0;
792}
793
794void Sema::EmitCurrentDiagnostic(unsigned DiagID) {
795  // FIXME: It doesn't make sense to me that DiagID is an incoming argument here
796  // and yet we also use the current diag ID on the DiagnosticsEngine. This has
797  // been made more painfully obvious by the refactor that introduced this
798  // function, but it is possible that the incoming argument can be
799  // eliminnated. If it truly cannot be (for example, there is some reentrancy
800  // issue I am not seeing yet), then there should at least be a clarifying
801  // comment somewhere.
802  if (llvm::Optional<TemplateDeductionInfo*> Info = isSFINAEContext()) {
803    switch (DiagnosticIDs::getDiagnosticSFINAEResponse(
804              Diags.getCurrentDiagID())) {
805    case DiagnosticIDs::SFINAE_Report:
806      // We'll report the diagnostic below.
807      break;
808
809    case DiagnosticIDs::SFINAE_SubstitutionFailure:
810      // Count this failure so that we know that template argument deduction
811      // has failed.
812      ++NumSFINAEErrors;
813
814      // Make a copy of this suppressed diagnostic and store it with the
815      // template-deduction information.
816      if (*Info && !(*Info)->hasSFINAEDiagnostic()) {
817        Diagnostic DiagInfo(&Diags);
818        (*Info)->addSFINAEDiagnostic(DiagInfo.getLocation(),
819                       PartialDiagnostic(DiagInfo, Context.getDiagAllocator()));
820      }
821
822      Diags.setLastDiagnosticIgnored();
823      Diags.Clear();
824      return;
825
826    case DiagnosticIDs::SFINAE_AccessControl: {
827      // Per C++ Core Issue 1170, access control is part of SFINAE.
828      // Additionally, the AccessCheckingSFINAE flag can be used to temporarily
829      // make access control a part of SFINAE for the purposes of checking
830      // type traits.
831      if (!AccessCheckingSFINAE && !getLangOpts().CPlusPlus11)
832        break;
833
834      SourceLocation Loc = Diags.getCurrentDiagLoc();
835
836      // Suppress this diagnostic.
837      ++NumSFINAEErrors;
838
839      // Make a copy of this suppressed diagnostic and store it with the
840      // template-deduction information.
841      if (*Info && !(*Info)->hasSFINAEDiagnostic()) {
842        Diagnostic DiagInfo(&Diags);
843        (*Info)->addSFINAEDiagnostic(DiagInfo.getLocation(),
844                       PartialDiagnostic(DiagInfo, Context.getDiagAllocator()));
845      }
846
847      Diags.setLastDiagnosticIgnored();
848      Diags.Clear();
849
850      // Now the diagnostic state is clear, produce a C++98 compatibility
851      // warning.
852      Diag(Loc, diag::warn_cxx98_compat_sfinae_access_control);
853
854      // The last diagnostic which Sema produced was ignored. Suppress any
855      // notes attached to it.
856      Diags.setLastDiagnosticIgnored();
857      return;
858    }
859
860    case DiagnosticIDs::SFINAE_Suppress:
861      // Make a copy of this suppressed diagnostic and store it with the
862      // template-deduction information;
863      if (*Info) {
864        Diagnostic DiagInfo(&Diags);
865        (*Info)->addSuppressedDiagnostic(DiagInfo.getLocation(),
866                       PartialDiagnostic(DiagInfo, Context.getDiagAllocator()));
867      }
868
869      // Suppress this diagnostic.
870      Diags.setLastDiagnosticIgnored();
871      Diags.Clear();
872      return;
873    }
874  }
875
876  // Set up the context's printing policy based on our current state.
877  Context.setPrintingPolicy(getPrintingPolicy());
878
879  // Emit the diagnostic.
880  if (!Diags.EmitCurrentDiagnostic())
881    return;
882
883  // If this is not a note, and we're in a template instantiation
884  // that is different from the last template instantiation where
885  // we emitted an error, print a template instantiation
886  // backtrace.
887  if (!DiagnosticIDs::isBuiltinNote(DiagID) &&
888      !ActiveTemplateInstantiations.empty() &&
889      ActiveTemplateInstantiations.back()
890        != LastTemplateInstantiationErrorContext) {
891    PrintInstantiationStack();
892    LastTemplateInstantiationErrorContext = ActiveTemplateInstantiations.back();
893  }
894}
895
896Sema::SemaDiagnosticBuilder
897Sema::Diag(SourceLocation Loc, const PartialDiagnostic& PD) {
898  SemaDiagnosticBuilder Builder(Diag(Loc, PD.getDiagID()));
899  PD.Emit(Builder);
900
901  return Builder;
902}
903
904/// \brief Looks through the macro-expansion chain for the given
905/// location, looking for a macro expansion with the given name.
906/// If one is found, returns true and sets the location to that
907/// expansion loc.
908bool Sema::findMacroSpelling(SourceLocation &locref, StringRef name) {
909  SourceLocation loc = locref;
910  if (!loc.isMacroID()) return false;
911
912  // There's no good way right now to look at the intermediate
913  // expansions, so just jump to the expansion location.
914  loc = getSourceManager().getExpansionLoc(loc);
915
916  // If that's written with the name, stop here.
917  SmallVector<char, 16> buffer;
918  if (getPreprocessor().getSpelling(loc, buffer) == name) {
919    locref = loc;
920    return true;
921  }
922  return false;
923}
924
925/// \brief Determines the active Scope associated with the given declaration
926/// context.
927///
928/// This routine maps a declaration context to the active Scope object that
929/// represents that declaration context in the parser. It is typically used
930/// from "scope-less" code (e.g., template instantiation, lazy creation of
931/// declarations) that injects a name for name-lookup purposes and, therefore,
932/// must update the Scope.
933///
934/// \returns The scope corresponding to the given declaraion context, or NULL
935/// if no such scope is open.
936Scope *Sema::getScopeForContext(DeclContext *Ctx) {
937
938  if (!Ctx)
939    return 0;
940
941  Ctx = Ctx->getPrimaryContext();
942  for (Scope *S = getCurScope(); S; S = S->getParent()) {
943    // Ignore scopes that cannot have declarations. This is important for
944    // out-of-line definitions of static class members.
945    if (S->getFlags() & (Scope::DeclScope | Scope::TemplateParamScope))
946      if (DeclContext *Entity = static_cast<DeclContext *> (S->getEntity()))
947        if (Ctx == Entity->getPrimaryContext())
948          return S;
949  }
950
951  return 0;
952}
953
954/// \brief Enter a new function scope
955void Sema::PushFunctionScope() {
956  if (FunctionScopes.size() == 1) {
957    // Use the "top" function scope rather than having to allocate
958    // memory for a new scope.
959    FunctionScopes.back()->Clear();
960    FunctionScopes.push_back(FunctionScopes.back());
961    return;
962  }
963
964  FunctionScopes.push_back(new FunctionScopeInfo(getDiagnostics()));
965}
966
967void Sema::PushBlockScope(Scope *BlockScope, BlockDecl *Block) {
968  FunctionScopes.push_back(new BlockScopeInfo(getDiagnostics(),
969                                              BlockScope, Block));
970}
971
972void Sema::PushLambdaScope(CXXRecordDecl *Lambda,
973                           CXXMethodDecl *CallOperator) {
974  FunctionScopes.push_back(new LambdaScopeInfo(getDiagnostics(), Lambda,
975                                               CallOperator));
976}
977
978void Sema::PopFunctionScopeInfo(const AnalysisBasedWarnings::Policy *WP,
979                                const Decl *D, const BlockExpr *blkExpr) {
980  FunctionScopeInfo *Scope = FunctionScopes.pop_back_val();
981  assert(!FunctionScopes.empty() && "mismatched push/pop!");
982
983  // Issue any analysis-based warnings.
984  if (WP && D)
985    AnalysisWarnings.IssueWarnings(*WP, Scope, D, blkExpr);
986  else {
987    for (SmallVectorImpl<sema::PossiblyUnreachableDiag>::iterator
988         i = Scope->PossiblyUnreachableDiags.begin(),
989         e = Scope->PossiblyUnreachableDiags.end();
990         i != e; ++i) {
991      const sema::PossiblyUnreachableDiag &D = *i;
992      Diag(D.Loc, D.PD);
993    }
994  }
995
996  if (FunctionScopes.back() != Scope) {
997    delete Scope;
998  }
999}
1000
1001void Sema::PushCompoundScope() {
1002  getCurFunction()->CompoundScopes.push_back(CompoundScopeInfo());
1003}
1004
1005void Sema::PopCompoundScope() {
1006  FunctionScopeInfo *CurFunction = getCurFunction();
1007  assert(!CurFunction->CompoundScopes.empty() && "mismatched push/pop");
1008
1009  CurFunction->CompoundScopes.pop_back();
1010}
1011
1012/// \brief Determine whether any errors occurred within this function/method/
1013/// block.
1014bool Sema::hasAnyUnrecoverableErrorsInThisFunction() const {
1015  return getCurFunction()->ErrorTrap.hasUnrecoverableErrorOccurred();
1016}
1017
1018BlockScopeInfo *Sema::getCurBlock() {
1019  if (FunctionScopes.empty())
1020    return 0;
1021
1022  return dyn_cast<BlockScopeInfo>(FunctionScopes.back());
1023}
1024
1025LambdaScopeInfo *Sema::getCurLambda() {
1026  if (FunctionScopes.empty())
1027    return 0;
1028
1029  return dyn_cast<LambdaScopeInfo>(FunctionScopes.back());
1030}
1031
1032void Sema::ActOnComment(SourceRange Comment) {
1033  if (!LangOpts.RetainCommentsFromSystemHeaders &&
1034      SourceMgr.isInSystemHeader(Comment.getBegin()))
1035    return;
1036  RawComment RC(SourceMgr, Comment);
1037  if (RC.isAlmostTrailingComment()) {
1038    SourceRange MagicMarkerRange(Comment.getBegin(),
1039                                 Comment.getBegin().getLocWithOffset(3));
1040    StringRef MagicMarkerText;
1041    switch (RC.getKind()) {
1042    case RawComment::RCK_OrdinaryBCPL:
1043      MagicMarkerText = "///<";
1044      break;
1045    case RawComment::RCK_OrdinaryC:
1046      MagicMarkerText = "/**<";
1047      break;
1048    default:
1049      llvm_unreachable("if this is an almost Doxygen comment, "
1050                       "it should be ordinary");
1051    }
1052    Diag(Comment.getBegin(), diag::warn_not_a_doxygen_trailing_member_comment) <<
1053      FixItHint::CreateReplacement(MagicMarkerRange, MagicMarkerText);
1054  }
1055  Context.addComment(RC);
1056}
1057
1058// Pin this vtable to this file.
1059ExternalSemaSource::~ExternalSemaSource() {}
1060
1061void ExternalSemaSource::ReadMethodPool(Selector Sel) { }
1062
1063void ExternalSemaSource::ReadKnownNamespaces(
1064                           SmallVectorImpl<NamespaceDecl *> &Namespaces) {
1065}
1066
1067void ExternalSemaSource::ReadUndefinedInternals(
1068                      llvm::MapVector<NamedDecl *, SourceLocation> &Undefined) {
1069}
1070
1071void PrettyDeclStackTraceEntry::print(raw_ostream &OS) const {
1072  SourceLocation Loc = this->Loc;
1073  if (!Loc.isValid() && TheDecl) Loc = TheDecl->getLocation();
1074  if (Loc.isValid()) {
1075    Loc.print(OS, S.getSourceManager());
1076    OS << ": ";
1077  }
1078  OS << Message;
1079
1080  if (TheDecl && isa<NamedDecl>(TheDecl)) {
1081    std::string Name = cast<NamedDecl>(TheDecl)->getNameAsString();
1082    if (!Name.empty())
1083      OS << " '" << Name << '\'';
1084  }
1085
1086  OS << '\n';
1087}
1088
1089/// \brief Figure out if an expression could be turned into a call.
1090///
1091/// Use this when trying to recover from an error where the programmer may have
1092/// written just the name of a function instead of actually calling it.
1093///
1094/// \param E - The expression to examine.
1095/// \param ZeroArgCallReturnTy - If the expression can be turned into a call
1096///  with no arguments, this parameter is set to the type returned by such a
1097///  call; otherwise, it is set to an empty QualType.
1098/// \param OverloadSet - If the expression is an overloaded function
1099///  name, this parameter is populated with the decls of the various overloads.
1100bool Sema::isExprCallable(const Expr &E, QualType &ZeroArgCallReturnTy,
1101                          UnresolvedSetImpl &OverloadSet) {
1102  ZeroArgCallReturnTy = QualType();
1103  OverloadSet.clear();
1104
1105  if (E.getType() == Context.OverloadTy) {
1106    OverloadExpr::FindResult FR = OverloadExpr::find(const_cast<Expr*>(&E));
1107    const OverloadExpr *Overloads = FR.Expression;
1108
1109    for (OverloadExpr::decls_iterator it = Overloads->decls_begin(),
1110         DeclsEnd = Overloads->decls_end(); it != DeclsEnd; ++it) {
1111      OverloadSet.addDecl(*it);
1112
1113      // Check whether the function is a non-template which takes no
1114      // arguments.
1115      if (const FunctionDecl *OverloadDecl
1116            = dyn_cast<FunctionDecl>((*it)->getUnderlyingDecl())) {
1117        if (OverloadDecl->getMinRequiredArguments() == 0)
1118          ZeroArgCallReturnTy = OverloadDecl->getResultType();
1119      }
1120    }
1121
1122    // Ignore overloads that are pointer-to-member constants.
1123    if (FR.HasFormOfMemberPointer)
1124      return false;
1125
1126    return true;
1127  }
1128
1129  if (const DeclRefExpr *DeclRef = dyn_cast<DeclRefExpr>(E.IgnoreParens())) {
1130    if (const FunctionDecl *Fun = dyn_cast<FunctionDecl>(DeclRef->getDecl())) {
1131      if (Fun->getMinRequiredArguments() == 0)
1132        ZeroArgCallReturnTy = Fun->getResultType();
1133      return true;
1134    }
1135  }
1136
1137  // We don't have an expression that's convenient to get a FunctionDecl from,
1138  // but we can at least check if the type is "function of 0 arguments".
1139  QualType ExprTy = E.getType();
1140  const FunctionType *FunTy = NULL;
1141  QualType PointeeTy = ExprTy->getPointeeType();
1142  if (!PointeeTy.isNull())
1143    FunTy = PointeeTy->getAs<FunctionType>();
1144  if (!FunTy)
1145    FunTy = ExprTy->getAs<FunctionType>();
1146  if (!FunTy && ExprTy == Context.BoundMemberTy) {
1147    // Look for the bound-member type.  If it's still overloaded, give up,
1148    // although we probably should have fallen into the OverloadExpr case above
1149    // if we actually have an overloaded bound member.
1150    QualType BoundMemberTy = Expr::findBoundMemberType(&E);
1151    if (!BoundMemberTy.isNull())
1152      FunTy = BoundMemberTy->castAs<FunctionType>();
1153  }
1154
1155  if (const FunctionProtoType *FPT =
1156      dyn_cast_or_null<FunctionProtoType>(FunTy)) {
1157    if (FPT->getNumArgs() == 0)
1158      ZeroArgCallReturnTy = FunTy->getResultType();
1159    return true;
1160  }
1161  return false;
1162}
1163
1164/// \brief Give notes for a set of overloads.
1165///
1166/// A companion to isExprCallable. In cases when the name that the programmer
1167/// wrote was an overloaded function, we may be able to make some guesses about
1168/// plausible overloads based on their return types; such guesses can be handed
1169/// off to this method to be emitted as notes.
1170///
1171/// \param Overloads - The overloads to note.
1172/// \param FinalNoteLoc - If we've suppressed printing some overloads due to
1173///  -fshow-overloads=best, this is the location to attach to the note about too
1174///  many candidates. Typically this will be the location of the original
1175///  ill-formed expression.
1176static void noteOverloads(Sema &S, const UnresolvedSetImpl &Overloads,
1177                          const SourceLocation FinalNoteLoc) {
1178  int ShownOverloads = 0;
1179  int SuppressedOverloads = 0;
1180  for (UnresolvedSetImpl::iterator It = Overloads.begin(),
1181       DeclsEnd = Overloads.end(); It != DeclsEnd; ++It) {
1182    // FIXME: Magic number for max shown overloads stolen from
1183    // OverloadCandidateSet::NoteCandidates.
1184    if (ShownOverloads >= 4 && S.Diags.getShowOverloads() == Ovl_Best) {
1185      ++SuppressedOverloads;
1186      continue;
1187    }
1188
1189    NamedDecl *Fn = (*It)->getUnderlyingDecl();
1190    S.Diag(Fn->getLocation(), diag::note_possible_target_of_call);
1191    ++ShownOverloads;
1192  }
1193
1194  if (SuppressedOverloads)
1195    S.Diag(FinalNoteLoc, diag::note_ovl_too_many_candidates)
1196      << SuppressedOverloads;
1197}
1198
1199static void notePlausibleOverloads(Sema &S, SourceLocation Loc,
1200                                   const UnresolvedSetImpl &Overloads,
1201                                   bool (*IsPlausibleResult)(QualType)) {
1202  if (!IsPlausibleResult)
1203    return noteOverloads(S, Overloads, Loc);
1204
1205  UnresolvedSet<2> PlausibleOverloads;
1206  for (OverloadExpr::decls_iterator It = Overloads.begin(),
1207         DeclsEnd = Overloads.end(); It != DeclsEnd; ++It) {
1208    const FunctionDecl *OverloadDecl = cast<FunctionDecl>(*It);
1209    QualType OverloadResultTy = OverloadDecl->getResultType();
1210    if (IsPlausibleResult(OverloadResultTy))
1211      PlausibleOverloads.addDecl(It.getDecl());
1212  }
1213  noteOverloads(S, PlausibleOverloads, Loc);
1214}
1215
1216/// Determine whether the given expression can be called by just
1217/// putting parentheses after it.  Notably, expressions with unary
1218/// operators can't be because the unary operator will start parsing
1219/// outside the call.
1220static bool IsCallableWithAppend(Expr *E) {
1221  E = E->IgnoreImplicit();
1222  return (!isa<CStyleCastExpr>(E) &&
1223          !isa<UnaryOperator>(E) &&
1224          !isa<BinaryOperator>(E) &&
1225          !isa<CXXOperatorCallExpr>(E));
1226}
1227
1228bool Sema::tryToRecoverWithCall(ExprResult &E, const PartialDiagnostic &PD,
1229                                bool ForceComplain,
1230                                bool (*IsPlausibleResult)(QualType)) {
1231  SourceLocation Loc = E.get()->getExprLoc();
1232  SourceRange Range = E.get()->getSourceRange();
1233
1234  QualType ZeroArgCallTy;
1235  UnresolvedSet<4> Overloads;
1236  if (isExprCallable(*E.get(), ZeroArgCallTy, Overloads) &&
1237      !ZeroArgCallTy.isNull() &&
1238      (!IsPlausibleResult || IsPlausibleResult(ZeroArgCallTy))) {
1239    // At this point, we know E is potentially callable with 0
1240    // arguments and that it returns something of a reasonable type,
1241    // so we can emit a fixit and carry on pretending that E was
1242    // actually a CallExpr.
1243    SourceLocation ParenInsertionLoc =
1244      PP.getLocForEndOfToken(Range.getEnd());
1245    Diag(Loc, PD)
1246      << /*zero-arg*/ 1 << Range
1247      << (IsCallableWithAppend(E.get())
1248          ? FixItHint::CreateInsertion(ParenInsertionLoc, "()")
1249          : FixItHint());
1250    notePlausibleOverloads(*this, Loc, Overloads, IsPlausibleResult);
1251
1252    // FIXME: Try this before emitting the fixit, and suppress diagnostics
1253    // while doing so.
1254    E = ActOnCallExpr(0, E.take(), ParenInsertionLoc,
1255                      MultiExprArg(), ParenInsertionLoc.getLocWithOffset(1));
1256    return true;
1257  }
1258
1259  if (!ForceComplain) return false;
1260
1261  Diag(Loc, PD) << /*not zero-arg*/ 0 << Range;
1262  notePlausibleOverloads(*this, Loc, Overloads, IsPlausibleResult);
1263  E = ExprError();
1264  return true;
1265}
1266