1 //===- ASTImporter.cpp - Importing ASTs from other Contexts ---------------===//
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 defines the ASTImporter class which imports AST nodes from one
11 //  context into another context.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #include "clang/AST/ASTImporter.h"
16 #include "clang/AST/ASTContext.h"
17 #include "clang/AST/ASTDiagnostic.h"
18 #include "clang/AST/ASTStructuralEquivalence.h"
19 #include "clang/AST/Attr.h"
20 #include "clang/AST/Decl.h"
21 #include "clang/AST/DeclAccessPair.h"
22 #include "clang/AST/DeclBase.h"
23 #include "clang/AST/DeclCXX.h"
24 #include "clang/AST/DeclFriend.h"
25 #include "clang/AST/DeclGroup.h"
26 #include "clang/AST/DeclObjC.h"
27 #include "clang/AST/DeclTemplate.h"
28 #include "clang/AST/DeclVisitor.h"
29 #include "clang/AST/DeclarationName.h"
30 #include "clang/AST/Expr.h"
31 #include "clang/AST/ExprCXX.h"
32 #include "clang/AST/ExprObjC.h"
33 #include "clang/AST/ExternalASTSource.h"
34 #include "clang/AST/LambdaCapture.h"
35 #include "clang/AST/NestedNameSpecifier.h"
36 #include "clang/AST/OperationKinds.h"
37 #include "clang/AST/Stmt.h"
38 #include "clang/AST/StmtCXX.h"
39 #include "clang/AST/StmtObjC.h"
40 #include "clang/AST/StmtVisitor.h"
41 #include "clang/AST/TemplateBase.h"
42 #include "clang/AST/TemplateName.h"
43 #include "clang/AST/Type.h"
44 #include "clang/AST/TypeLoc.h"
45 #include "clang/AST/TypeVisitor.h"
46 #include "clang/AST/UnresolvedSet.h"
47 #include "clang/Basic/ExceptionSpecificationType.h"
48 #include "clang/Basic/FileManager.h"
49 #include "clang/Basic/IdentifierTable.h"
50 #include "clang/Basic/LLVM.h"
51 #include "clang/Basic/LangOptions.h"
52 #include "clang/Basic/SourceLocation.h"
53 #include "clang/Basic/SourceManager.h"
54 #include "clang/Basic/Specifiers.h"
55 #include "llvm/ADT/APSInt.h"
56 #include "llvm/ADT/ArrayRef.h"
57 #include "llvm/ADT/DenseMap.h"
58 #include "llvm/ADT/None.h"
59 #include "llvm/ADT/Optional.h"
60 #include "llvm/ADT/STLExtras.h"
61 #include "llvm/ADT/SmallVector.h"
62 #include "llvm/Support/Casting.h"
63 #include "llvm/Support/ErrorHandling.h"
64 #include "llvm/Support/MemoryBuffer.h"
65 #include <algorithm>
66 #include <cassert>
67 #include <cstddef>
68 #include <memory>
69 #include <type_traits>
70 #include <utility>
71 
72 namespace clang {
73 
74   using llvm::make_error;
75   using llvm::Error;
76   using llvm::Expected;
77   using ExpectedType = llvm::Expected<QualType>;
78   using ExpectedStmt = llvm::Expected<Stmt *>;
79   using ExpectedExpr = llvm::Expected<Expr *>;
80   using ExpectedDecl = llvm::Expected<Decl *>;
81   using ExpectedSLoc = llvm::Expected<SourceLocation>;
82 
83   std::string ImportError::toString() const {
84     // FIXME: Improve error texts.
85     switch (Error) {
86     case NameConflict:
87       return "NameConflict";
88     case UnsupportedConstruct:
89       return "UnsupportedConstruct";
90     case Unknown:
91       return "Unknown error";
92     }
93     llvm_unreachable("Invalid error code.");
94     return "Invalid error code.";
95   }
96 
97   void ImportError::log(raw_ostream &OS) const {
98     OS << toString();
99   }
100 
101   std::error_code ImportError::convertToErrorCode() const {
102     llvm_unreachable("Function not implemented.");
103   }
104 
105   char ImportError::ID;
106 
107   template <class T>
108   SmallVector<Decl *, 2>
109   getCanonicalForwardRedeclChain(Redeclarable<T>* D) {
110     SmallVector<Decl *, 2> Redecls;
111     for (auto *R : D->getFirstDecl()->redecls()) {
112       if (R != D->getFirstDecl())
113         Redecls.push_back(R);
114     }
115     Redecls.push_back(D->getFirstDecl());
116     std::reverse(Redecls.begin(), Redecls.end());
117     return Redecls;
118   }
119 
120   SmallVector<Decl*, 2> getCanonicalForwardRedeclChain(Decl* D) {
121     if (auto *FD = dyn_cast<FunctionDecl>(D))
122       return getCanonicalForwardRedeclChain<FunctionDecl>(FD);
123     if (auto *VD = dyn_cast<VarDecl>(D))
124       return getCanonicalForwardRedeclChain<VarDecl>(VD);
125     llvm_unreachable("Bad declaration kind");
126   }
127 
128   void updateFlags(const Decl *From, Decl *To) {
129     // Check if some flags or attrs are new in 'From' and copy into 'To'.
130     // FIXME: Other flags or attrs?
131     if (From->isUsed(false) && !To->isUsed(false))
132       To->setIsUsed();
133   }
134 
135   Optional<unsigned> ASTImporter::getFieldIndex(Decl *F) {
136     assert(F && (isa<FieldDecl>(*F) || isa<IndirectFieldDecl>(*F)) &&
137         "Try to get field index for non-field.");
138 
139     auto *Owner = dyn_cast<RecordDecl>(F->getDeclContext());
140     if (!Owner)
141       return None;
142 
143     unsigned Index = 0;
144     for (const auto *D : Owner->decls()) {
145       if (D == F)
146         return Index;
147 
148       if (isa<FieldDecl>(*D) || isa<IndirectFieldDecl>(*D))
149         ++Index;
150     }
151 
152     llvm_unreachable("Field was not found in its parent context.");
153 
154     return None;
155   }
156 
157   // FIXME: Temporary until every import returns Expected.
158   template <>
159   LLVM_NODISCARD Error
160   ASTImporter::importInto(SourceLocation &To, const SourceLocation &From) {
161     To = Import(From);
162     if (From.isValid() && To.isInvalid())
163         return llvm::make_error<ImportError>();
164     return Error::success();
165   }
166   // FIXME: Temporary until every import returns Expected.
167   template <>
168   LLVM_NODISCARD Error
169   ASTImporter::importInto(QualType &To, const QualType &From) {
170     To = Import(From);
171     if (!From.isNull() && To.isNull())
172         return llvm::make_error<ImportError>();
173     return Error::success();
174   }
175 
176   class ASTNodeImporter : public TypeVisitor<ASTNodeImporter, ExpectedType>,
177                           public DeclVisitor<ASTNodeImporter, ExpectedDecl>,
178                           public StmtVisitor<ASTNodeImporter, ExpectedStmt> {
179     ASTImporter &Importer;
180 
181     // Use this instead of Importer.importInto .
182     template <typename ImportT>
183     LLVM_NODISCARD Error importInto(ImportT &To, const ImportT &From) {
184       return Importer.importInto(To, From);
185     }
186 
187     // Use this to import pointers of specific type.
188     template <typename ImportT>
189     LLVM_NODISCARD Error importInto(ImportT *&To, ImportT *From) {
190       auto ToI = Importer.Import(From);
191       if (!ToI && From)
192         return make_error<ImportError>();
193       To = cast_or_null<ImportT>(ToI);
194       return Error::success();
195       // FIXME: This should be the final code.
196       //auto ToOrErr = Importer.Import(From);
197       //if (ToOrErr) {
198       //  To = cast_or_null<ImportT>(*ToOrErr);
199       //}
200       //return ToOrErr.takeError();
201     }
202 
203     // Call the import function of ASTImporter for a baseclass of type `T` and
204     // cast the return value to `T`.
205     template <typename T>
206     Expected<T *> import(T *From) {
207       auto *To = Importer.Import(From);
208       if (!To && From)
209         return make_error<ImportError>();
210       return cast_or_null<T>(To);
211       // FIXME: This should be the final code.
212       //auto ToOrErr = Importer.Import(From);
213       //if (!ToOrErr)
214       //  return ToOrErr.takeError();
215       //return cast_or_null<T>(*ToOrErr);
216     }
217 
218     template <typename T>
219     Expected<T *> import(const T *From) {
220       return import(const_cast<T *>(From));
221     }
222 
223     // Call the import function of ASTImporter for type `T`.
224     template <typename T>
225     Expected<T> import(const T &From) {
226       T To = Importer.Import(From);
227       T DefaultT;
228       if (To == DefaultT && !(From == DefaultT))
229         return make_error<ImportError>();
230       return To;
231       // FIXME: This should be the final code.
232       //return Importer.Import(From);
233     }
234 
235     template <class T>
236     Expected<std::tuple<T>>
237     importSeq(const T &From) {
238       Expected<T> ToOrErr = import(From);
239       if (!ToOrErr)
240         return ToOrErr.takeError();
241       return std::make_tuple<T>(std::move(*ToOrErr));
242     }
243 
244     // Import multiple objects with a single function call.
245     // This should work for every type for which a variant of `import` exists.
246     // The arguments are processed from left to right and import is stopped on
247     // first error.
248     template <class THead, class... TTail>
249     Expected<std::tuple<THead, TTail...>>
250     importSeq(const THead &FromHead, const TTail &...FromTail) {
251       Expected<std::tuple<THead>> ToHeadOrErr = importSeq(FromHead);
252       if (!ToHeadOrErr)
253         return ToHeadOrErr.takeError();
254       Expected<std::tuple<TTail...>> ToTailOrErr = importSeq(FromTail...);
255       if (!ToTailOrErr)
256         return ToTailOrErr.takeError();
257       return std::tuple_cat(*ToHeadOrErr, *ToTailOrErr);
258     }
259 
260 // Wrapper for an overload set.
261     template <typename ToDeclT> struct CallOverloadedCreateFun {
262       template <typename... Args>
263       auto operator()(Args &&... args)
264           -> decltype(ToDeclT::Create(std::forward<Args>(args)...)) {
265         return ToDeclT::Create(std::forward<Args>(args)...);
266       }
267     };
268 
269     // Always use these functions to create a Decl during import. There are
270     // certain tasks which must be done after the Decl was created, e.g. we
271     // must immediately register that as an imported Decl.  The parameter `ToD`
272     // will be set to the newly created Decl or if had been imported before
273     // then to the already imported Decl.  Returns a bool value set to true if
274     // the `FromD` had been imported before.
275     template <typename ToDeclT, typename FromDeclT, typename... Args>
276     LLVM_NODISCARD bool GetImportedOrCreateDecl(ToDeclT *&ToD, FromDeclT *FromD,
277                                                 Args &&... args) {
278       // There may be several overloads of ToDeclT::Create. We must make sure
279       // to call the one which would be chosen by the arguments, thus we use a
280       // wrapper for the overload set.
281       CallOverloadedCreateFun<ToDeclT> OC;
282       return GetImportedOrCreateSpecialDecl(ToD, OC, FromD,
283                                             std::forward<Args>(args)...);
284     }
285     // Use this overload if a special Type is needed to be created.  E.g if we
286     // want to create a `TypeAliasDecl` and assign that to a `TypedefNameDecl`
287     // then:
288     // TypedefNameDecl *ToTypedef;
289     // GetImportedOrCreateDecl<TypeAliasDecl>(ToTypedef, FromD, ...);
290     template <typename NewDeclT, typename ToDeclT, typename FromDeclT,
291               typename... Args>
292     LLVM_NODISCARD bool GetImportedOrCreateDecl(ToDeclT *&ToD, FromDeclT *FromD,
293                                                 Args &&... args) {
294       CallOverloadedCreateFun<NewDeclT> OC;
295       return GetImportedOrCreateSpecialDecl(ToD, OC, FromD,
296                                             std::forward<Args>(args)...);
297     }
298     // Use this version if a special create function must be
299     // used, e.g. CXXRecordDecl::CreateLambda .
300     template <typename ToDeclT, typename CreateFunT, typename FromDeclT,
301               typename... Args>
302     LLVM_NODISCARD bool
303     GetImportedOrCreateSpecialDecl(ToDeclT *&ToD, CreateFunT CreateFun,
304                                    FromDeclT *FromD, Args &&... args) {
305       // FIXME: This code is needed later.
306       //if (Importer.getImportDeclErrorIfAny(FromD)) {
307       //  ToD = nullptr;
308       //  return true; // Already imported but with error.
309       //}
310       ToD = cast_or_null<ToDeclT>(Importer.GetAlreadyImportedOrNull(FromD));
311       if (ToD)
312         return true; // Already imported.
313       ToD = CreateFun(std::forward<Args>(args)...);
314       InitializeImportedDecl(FromD, ToD);
315       return false; // A new Decl is created.
316     }
317 
318     void InitializeImportedDecl(Decl *FromD, Decl *ToD) {
319       Importer.MapImported(FromD, ToD);
320       ToD->IdentifierNamespace = FromD->IdentifierNamespace;
321       if (FromD->hasAttrs())
322         for (const Attr *FromAttr : FromD->getAttrs())
323           ToD->addAttr(Importer.Import(FromAttr));
324       if (FromD->isUsed())
325         ToD->setIsUsed();
326       if (FromD->isImplicit())
327         ToD->setImplicit();
328     }
329 
330   public:
331     explicit ASTNodeImporter(ASTImporter &Importer) : Importer(Importer) {}
332 
333     using TypeVisitor<ASTNodeImporter, ExpectedType>::Visit;
334     using DeclVisitor<ASTNodeImporter, ExpectedDecl>::Visit;
335     using StmtVisitor<ASTNodeImporter, ExpectedStmt>::Visit;
336 
337     // Importing types
338     ExpectedType VisitType(const Type *T);
339     ExpectedType VisitAtomicType(const AtomicType *T);
340     ExpectedType VisitBuiltinType(const BuiltinType *T);
341     ExpectedType VisitDecayedType(const DecayedType *T);
342     ExpectedType VisitComplexType(const ComplexType *T);
343     ExpectedType VisitPointerType(const PointerType *T);
344     ExpectedType VisitBlockPointerType(const BlockPointerType *T);
345     ExpectedType VisitLValueReferenceType(const LValueReferenceType *T);
346     ExpectedType VisitRValueReferenceType(const RValueReferenceType *T);
347     ExpectedType VisitMemberPointerType(const MemberPointerType *T);
348     ExpectedType VisitConstantArrayType(const ConstantArrayType *T);
349     ExpectedType VisitIncompleteArrayType(const IncompleteArrayType *T);
350     ExpectedType VisitVariableArrayType(const VariableArrayType *T);
351     ExpectedType VisitDependentSizedArrayType(const DependentSizedArrayType *T);
352     // FIXME: DependentSizedExtVectorType
353     ExpectedType VisitVectorType(const VectorType *T);
354     ExpectedType VisitExtVectorType(const ExtVectorType *T);
355     ExpectedType VisitFunctionNoProtoType(const FunctionNoProtoType *T);
356     ExpectedType VisitFunctionProtoType(const FunctionProtoType *T);
357     ExpectedType VisitUnresolvedUsingType(const UnresolvedUsingType *T);
358     ExpectedType VisitParenType(const ParenType *T);
359     ExpectedType VisitTypedefType(const TypedefType *T);
360     ExpectedType VisitTypeOfExprType(const TypeOfExprType *T);
361     // FIXME: DependentTypeOfExprType
362     ExpectedType VisitTypeOfType(const TypeOfType *T);
363     ExpectedType VisitDecltypeType(const DecltypeType *T);
364     ExpectedType VisitUnaryTransformType(const UnaryTransformType *T);
365     ExpectedType VisitAutoType(const AutoType *T);
366     ExpectedType VisitInjectedClassNameType(const InjectedClassNameType *T);
367     // FIXME: DependentDecltypeType
368     ExpectedType VisitRecordType(const RecordType *T);
369     ExpectedType VisitEnumType(const EnumType *T);
370     ExpectedType VisitAttributedType(const AttributedType *T);
371     ExpectedType VisitTemplateTypeParmType(const TemplateTypeParmType *T);
372     ExpectedType VisitSubstTemplateTypeParmType(
373         const SubstTemplateTypeParmType *T);
374     ExpectedType VisitTemplateSpecializationType(
375         const TemplateSpecializationType *T);
376     ExpectedType VisitElaboratedType(const ElaboratedType *T);
377     ExpectedType VisitDependentNameType(const DependentNameType *T);
378     ExpectedType VisitPackExpansionType(const PackExpansionType *T);
379     ExpectedType VisitDependentTemplateSpecializationType(
380         const DependentTemplateSpecializationType *T);
381     ExpectedType VisitObjCInterfaceType(const ObjCInterfaceType *T);
382     ExpectedType VisitObjCObjectType(const ObjCObjectType *T);
383     ExpectedType VisitObjCObjectPointerType(const ObjCObjectPointerType *T);
384 
385     // Importing declarations
386     Error ImportDeclParts(
387         NamedDecl *D, DeclContext *&DC, DeclContext *&LexicalDC,
388         DeclarationName &Name, NamedDecl *&ToD, SourceLocation &Loc);
389     Error ImportDefinitionIfNeeded(Decl *FromD, Decl *ToD = nullptr);
390     Error ImportDeclarationNameLoc(
391         const DeclarationNameInfo &From, DeclarationNameInfo &To);
392     Error ImportDeclContext(DeclContext *FromDC, bool ForceImport = false);
393     Error ImportDeclContext(
394         Decl *From, DeclContext *&ToDC, DeclContext *&ToLexicalDC);
395     Error ImportImplicitMethods(const CXXRecordDecl *From, CXXRecordDecl *To);
396 
397     Expected<CXXCastPath> ImportCastPath(CastExpr *E);
398 
399     using Designator = DesignatedInitExpr::Designator;
400 
401     /// What we should import from the definition.
402     enum ImportDefinitionKind {
403       /// Import the default subset of the definition, which might be
404       /// nothing (if minimal import is set) or might be everything (if minimal
405       /// import is not set).
406       IDK_Default,
407       /// Import everything.
408       IDK_Everything,
409       /// Import only the bare bones needed to establish a valid
410       /// DeclContext.
411       IDK_Basic
412     };
413 
414     bool shouldForceImportDeclContext(ImportDefinitionKind IDK) {
415       return IDK == IDK_Everything ||
416              (IDK == IDK_Default && !Importer.isMinimalImport());
417     }
418 
419     Error ImportInitializer(VarDecl *From, VarDecl *To);
420     Error ImportDefinition(
421         RecordDecl *From, RecordDecl *To,
422         ImportDefinitionKind Kind = IDK_Default);
423     Error ImportDefinition(
424         EnumDecl *From, EnumDecl *To,
425         ImportDefinitionKind Kind = IDK_Default);
426     Error ImportDefinition(
427         ObjCInterfaceDecl *From, ObjCInterfaceDecl *To,
428         ImportDefinitionKind Kind = IDK_Default);
429     Error ImportDefinition(
430         ObjCProtocolDecl *From, ObjCProtocolDecl *To,
431         ImportDefinitionKind Kind = IDK_Default);
432     Expected<TemplateParameterList *> ImportTemplateParameterList(
433         TemplateParameterList *Params);
434     Error ImportTemplateArguments(
435         const TemplateArgument *FromArgs, unsigned NumFromArgs,
436         SmallVectorImpl<TemplateArgument> &ToArgs);
437     Expected<TemplateArgument>
438     ImportTemplateArgument(const TemplateArgument &From);
439 
440     template <typename InContainerTy>
441     Error ImportTemplateArgumentListInfo(
442         const InContainerTy &Container, TemplateArgumentListInfo &ToTAInfo);
443 
444     template<typename InContainerTy>
445     Error ImportTemplateArgumentListInfo(
446       SourceLocation FromLAngleLoc, SourceLocation FromRAngleLoc,
447       const InContainerTy &Container, TemplateArgumentListInfo &Result);
448 
449     using TemplateArgsTy = SmallVector<TemplateArgument, 8>;
450     using FunctionTemplateAndArgsTy =
451         std::tuple<FunctionTemplateDecl *, TemplateArgsTy>;
452     Expected<FunctionTemplateAndArgsTy>
453     ImportFunctionTemplateWithTemplateArgsFromSpecialization(
454         FunctionDecl *FromFD);
455 
456     Error ImportTemplateInformation(FunctionDecl *FromFD, FunctionDecl *ToFD);
457 
458     bool IsStructuralMatch(Decl *From, Decl *To, bool Complain);
459     bool IsStructuralMatch(RecordDecl *FromRecord, RecordDecl *ToRecord,
460                            bool Complain = true);
461     bool IsStructuralMatch(VarDecl *FromVar, VarDecl *ToVar,
462                            bool Complain = true);
463     bool IsStructuralMatch(EnumDecl *FromEnum, EnumDecl *ToRecord);
464     bool IsStructuralMatch(EnumConstantDecl *FromEC, EnumConstantDecl *ToEC);
465     bool IsStructuralMatch(FunctionTemplateDecl *From,
466                            FunctionTemplateDecl *To);
467     bool IsStructuralMatch(FunctionDecl *From, FunctionDecl *To);
468     bool IsStructuralMatch(ClassTemplateDecl *From, ClassTemplateDecl *To);
469     bool IsStructuralMatch(VarTemplateDecl *From, VarTemplateDecl *To);
470     ExpectedDecl VisitDecl(Decl *D);
471     ExpectedDecl VisitImportDecl(ImportDecl *D);
472     ExpectedDecl VisitEmptyDecl(EmptyDecl *D);
473     ExpectedDecl VisitAccessSpecDecl(AccessSpecDecl *D);
474     ExpectedDecl VisitStaticAssertDecl(StaticAssertDecl *D);
475     ExpectedDecl VisitTranslationUnitDecl(TranslationUnitDecl *D);
476     ExpectedDecl VisitNamespaceDecl(NamespaceDecl *D);
477     ExpectedDecl VisitNamespaceAliasDecl(NamespaceAliasDecl *D);
478     ExpectedDecl VisitTypedefNameDecl(TypedefNameDecl *D, bool IsAlias);
479     ExpectedDecl VisitTypedefDecl(TypedefDecl *D);
480     ExpectedDecl VisitTypeAliasDecl(TypeAliasDecl *D);
481     ExpectedDecl VisitTypeAliasTemplateDecl(TypeAliasTemplateDecl *D);
482     ExpectedDecl VisitLabelDecl(LabelDecl *D);
483     ExpectedDecl VisitEnumDecl(EnumDecl *D);
484     ExpectedDecl VisitRecordDecl(RecordDecl *D);
485     ExpectedDecl VisitEnumConstantDecl(EnumConstantDecl *D);
486     ExpectedDecl VisitFunctionDecl(FunctionDecl *D);
487     ExpectedDecl VisitCXXMethodDecl(CXXMethodDecl *D);
488     ExpectedDecl VisitCXXConstructorDecl(CXXConstructorDecl *D);
489     ExpectedDecl VisitCXXDestructorDecl(CXXDestructorDecl *D);
490     ExpectedDecl VisitCXXConversionDecl(CXXConversionDecl *D);
491     ExpectedDecl VisitFieldDecl(FieldDecl *D);
492     ExpectedDecl VisitIndirectFieldDecl(IndirectFieldDecl *D);
493     ExpectedDecl VisitFriendDecl(FriendDecl *D);
494     ExpectedDecl VisitObjCIvarDecl(ObjCIvarDecl *D);
495     ExpectedDecl VisitVarDecl(VarDecl *D);
496     ExpectedDecl VisitImplicitParamDecl(ImplicitParamDecl *D);
497     ExpectedDecl VisitParmVarDecl(ParmVarDecl *D);
498     ExpectedDecl VisitObjCMethodDecl(ObjCMethodDecl *D);
499     ExpectedDecl VisitObjCTypeParamDecl(ObjCTypeParamDecl *D);
500     ExpectedDecl VisitObjCCategoryDecl(ObjCCategoryDecl *D);
501     ExpectedDecl VisitObjCProtocolDecl(ObjCProtocolDecl *D);
502     ExpectedDecl VisitLinkageSpecDecl(LinkageSpecDecl *D);
503     ExpectedDecl VisitUsingDecl(UsingDecl *D);
504     ExpectedDecl VisitUsingShadowDecl(UsingShadowDecl *D);
505     ExpectedDecl VisitUsingDirectiveDecl(UsingDirectiveDecl *D);
506     ExpectedDecl VisitUnresolvedUsingValueDecl(UnresolvedUsingValueDecl *D);
507     ExpectedDecl VisitUnresolvedUsingTypenameDecl(UnresolvedUsingTypenameDecl *D);
508 
509     Expected<ObjCTypeParamList *>
510     ImportObjCTypeParamList(ObjCTypeParamList *list);
511 
512     ExpectedDecl VisitObjCInterfaceDecl(ObjCInterfaceDecl *D);
513     ExpectedDecl VisitObjCCategoryImplDecl(ObjCCategoryImplDecl *D);
514     ExpectedDecl VisitObjCImplementationDecl(ObjCImplementationDecl *D);
515     ExpectedDecl VisitObjCPropertyDecl(ObjCPropertyDecl *D);
516     ExpectedDecl VisitObjCPropertyImplDecl(ObjCPropertyImplDecl *D);
517     ExpectedDecl VisitTemplateTypeParmDecl(TemplateTypeParmDecl *D);
518     ExpectedDecl VisitNonTypeTemplateParmDecl(NonTypeTemplateParmDecl *D);
519     ExpectedDecl VisitTemplateTemplateParmDecl(TemplateTemplateParmDecl *D);
520     ExpectedDecl VisitClassTemplateDecl(ClassTemplateDecl *D);
521     ExpectedDecl VisitClassTemplateSpecializationDecl(
522                                             ClassTemplateSpecializationDecl *D);
523     ExpectedDecl VisitVarTemplateDecl(VarTemplateDecl *D);
524     ExpectedDecl VisitVarTemplateSpecializationDecl(VarTemplateSpecializationDecl *D);
525     ExpectedDecl VisitFunctionTemplateDecl(FunctionTemplateDecl *D);
526 
527     // Importing statements
528     ExpectedStmt VisitStmt(Stmt *S);
529     ExpectedStmt VisitGCCAsmStmt(GCCAsmStmt *S);
530     ExpectedStmt VisitDeclStmt(DeclStmt *S);
531     ExpectedStmt VisitNullStmt(NullStmt *S);
532     ExpectedStmt VisitCompoundStmt(CompoundStmt *S);
533     ExpectedStmt VisitCaseStmt(CaseStmt *S);
534     ExpectedStmt VisitDefaultStmt(DefaultStmt *S);
535     ExpectedStmt VisitLabelStmt(LabelStmt *S);
536     ExpectedStmt VisitAttributedStmt(AttributedStmt *S);
537     ExpectedStmt VisitIfStmt(IfStmt *S);
538     ExpectedStmt VisitSwitchStmt(SwitchStmt *S);
539     ExpectedStmt VisitWhileStmt(WhileStmt *S);
540     ExpectedStmt VisitDoStmt(DoStmt *S);
541     ExpectedStmt VisitForStmt(ForStmt *S);
542     ExpectedStmt VisitGotoStmt(GotoStmt *S);
543     ExpectedStmt VisitIndirectGotoStmt(IndirectGotoStmt *S);
544     ExpectedStmt VisitContinueStmt(ContinueStmt *S);
545     ExpectedStmt VisitBreakStmt(BreakStmt *S);
546     ExpectedStmt VisitReturnStmt(ReturnStmt *S);
547     // FIXME: MSAsmStmt
548     // FIXME: SEHExceptStmt
549     // FIXME: SEHFinallyStmt
550     // FIXME: SEHTryStmt
551     // FIXME: SEHLeaveStmt
552     // FIXME: CapturedStmt
553     ExpectedStmt VisitCXXCatchStmt(CXXCatchStmt *S);
554     ExpectedStmt VisitCXXTryStmt(CXXTryStmt *S);
555     ExpectedStmt VisitCXXForRangeStmt(CXXForRangeStmt *S);
556     // FIXME: MSDependentExistsStmt
557     ExpectedStmt VisitObjCForCollectionStmt(ObjCForCollectionStmt *S);
558     ExpectedStmt VisitObjCAtCatchStmt(ObjCAtCatchStmt *S);
559     ExpectedStmt VisitObjCAtFinallyStmt(ObjCAtFinallyStmt *S);
560     ExpectedStmt VisitObjCAtTryStmt(ObjCAtTryStmt *S);
561     ExpectedStmt VisitObjCAtSynchronizedStmt(ObjCAtSynchronizedStmt *S);
562     ExpectedStmt VisitObjCAtThrowStmt(ObjCAtThrowStmt *S);
563     ExpectedStmt VisitObjCAutoreleasePoolStmt(ObjCAutoreleasePoolStmt *S);
564 
565     // Importing expressions
566     ExpectedStmt VisitExpr(Expr *E);
567     ExpectedStmt VisitVAArgExpr(VAArgExpr *E);
568     ExpectedStmt VisitGNUNullExpr(GNUNullExpr *E);
569     ExpectedStmt VisitPredefinedExpr(PredefinedExpr *E);
570     ExpectedStmt VisitDeclRefExpr(DeclRefExpr *E);
571     ExpectedStmt VisitImplicitValueInitExpr(ImplicitValueInitExpr *E);
572     ExpectedStmt VisitDesignatedInitExpr(DesignatedInitExpr *E);
573     ExpectedStmt VisitCXXNullPtrLiteralExpr(CXXNullPtrLiteralExpr *E);
574     ExpectedStmt VisitIntegerLiteral(IntegerLiteral *E);
575     ExpectedStmt VisitFloatingLiteral(FloatingLiteral *E);
576     ExpectedStmt VisitImaginaryLiteral(ImaginaryLiteral *E);
577     ExpectedStmt VisitCharacterLiteral(CharacterLiteral *E);
578     ExpectedStmt VisitStringLiteral(StringLiteral *E);
579     ExpectedStmt VisitCompoundLiteralExpr(CompoundLiteralExpr *E);
580     ExpectedStmt VisitAtomicExpr(AtomicExpr *E);
581     ExpectedStmt VisitAddrLabelExpr(AddrLabelExpr *E);
582     ExpectedStmt VisitParenExpr(ParenExpr *E);
583     ExpectedStmt VisitParenListExpr(ParenListExpr *E);
584     ExpectedStmt VisitStmtExpr(StmtExpr *E);
585     ExpectedStmt VisitUnaryOperator(UnaryOperator *E);
586     ExpectedStmt VisitUnaryExprOrTypeTraitExpr(UnaryExprOrTypeTraitExpr *E);
587     ExpectedStmt VisitBinaryOperator(BinaryOperator *E);
588     ExpectedStmt VisitConditionalOperator(ConditionalOperator *E);
589     ExpectedStmt VisitBinaryConditionalOperator(BinaryConditionalOperator *E);
590     ExpectedStmt VisitOpaqueValueExpr(OpaqueValueExpr *E);
591     ExpectedStmt VisitArrayTypeTraitExpr(ArrayTypeTraitExpr *E);
592     ExpectedStmt VisitExpressionTraitExpr(ExpressionTraitExpr *E);
593     ExpectedStmt VisitArraySubscriptExpr(ArraySubscriptExpr *E);
594     ExpectedStmt VisitCompoundAssignOperator(CompoundAssignOperator *E);
595     ExpectedStmt VisitImplicitCastExpr(ImplicitCastExpr *E);
596     ExpectedStmt VisitExplicitCastExpr(ExplicitCastExpr *E);
597     ExpectedStmt VisitOffsetOfExpr(OffsetOfExpr *OE);
598     ExpectedStmt VisitCXXThrowExpr(CXXThrowExpr *E);
599     ExpectedStmt VisitCXXNoexceptExpr(CXXNoexceptExpr *E);
600     ExpectedStmt VisitCXXDefaultArgExpr(CXXDefaultArgExpr *E);
601     ExpectedStmt VisitCXXScalarValueInitExpr(CXXScalarValueInitExpr *E);
602     ExpectedStmt VisitCXXBindTemporaryExpr(CXXBindTemporaryExpr *E);
603     ExpectedStmt VisitCXXTemporaryObjectExpr(CXXTemporaryObjectExpr *E);
604     ExpectedStmt VisitMaterializeTemporaryExpr(MaterializeTemporaryExpr *E);
605     ExpectedStmt VisitPackExpansionExpr(PackExpansionExpr *E);
606     ExpectedStmt VisitSizeOfPackExpr(SizeOfPackExpr *E);
607     ExpectedStmt VisitCXXNewExpr(CXXNewExpr *E);
608     ExpectedStmt VisitCXXDeleteExpr(CXXDeleteExpr *E);
609     ExpectedStmt VisitCXXConstructExpr(CXXConstructExpr *E);
610     ExpectedStmt VisitCXXMemberCallExpr(CXXMemberCallExpr *E);
611     ExpectedStmt VisitCXXDependentScopeMemberExpr(CXXDependentScopeMemberExpr *E);
612     ExpectedStmt VisitDependentScopeDeclRefExpr(DependentScopeDeclRefExpr *E);
613     ExpectedStmt VisitCXXUnresolvedConstructExpr(CXXUnresolvedConstructExpr *E);
614     ExpectedStmt VisitUnresolvedLookupExpr(UnresolvedLookupExpr *E);
615     ExpectedStmt VisitUnresolvedMemberExpr(UnresolvedMemberExpr *E);
616     ExpectedStmt VisitExprWithCleanups(ExprWithCleanups *E);
617     ExpectedStmt VisitCXXThisExpr(CXXThisExpr *E);
618     ExpectedStmt VisitCXXBoolLiteralExpr(CXXBoolLiteralExpr *E);
619     ExpectedStmt VisitCXXPseudoDestructorExpr(CXXPseudoDestructorExpr *E);
620     ExpectedStmt VisitMemberExpr(MemberExpr *E);
621     ExpectedStmt VisitCallExpr(CallExpr *E);
622     ExpectedStmt VisitLambdaExpr(LambdaExpr *LE);
623     ExpectedStmt VisitInitListExpr(InitListExpr *E);
624     ExpectedStmt VisitCXXStdInitializerListExpr(CXXStdInitializerListExpr *E);
625     ExpectedStmt VisitCXXInheritedCtorInitExpr(CXXInheritedCtorInitExpr *E);
626     ExpectedStmt VisitArrayInitLoopExpr(ArrayInitLoopExpr *E);
627     ExpectedStmt VisitArrayInitIndexExpr(ArrayInitIndexExpr *E);
628     ExpectedStmt VisitCXXDefaultInitExpr(CXXDefaultInitExpr *E);
629     ExpectedStmt VisitCXXNamedCastExpr(CXXNamedCastExpr *E);
630     ExpectedStmt VisitSubstNonTypeTemplateParmExpr(SubstNonTypeTemplateParmExpr *E);
631     ExpectedStmt VisitTypeTraitExpr(TypeTraitExpr *E);
632     ExpectedStmt VisitCXXTypeidExpr(CXXTypeidExpr *E);
633 
634     template<typename IIter, typename OIter>
635     Error ImportArrayChecked(IIter Ibegin, IIter Iend, OIter Obegin) {
636       using ItemT = typename std::remove_reference<decltype(*Obegin)>::type;
637       for (; Ibegin != Iend; ++Ibegin, ++Obegin) {
638         Expected<ItemT> ToOrErr = import(*Ibegin);
639         if (!ToOrErr)
640           return ToOrErr.takeError();
641         *Obegin = *ToOrErr;
642       }
643       return Error::success();
644     }
645 
646     // Import every item from a container structure into an output container.
647     // If error occurs, stops at first error and returns the error.
648     // The output container should have space for all needed elements (it is not
649     // expanded, new items are put into from the beginning).
650     template<typename InContainerTy, typename OutContainerTy>
651     Error ImportContainerChecked(
652         const InContainerTy &InContainer, OutContainerTy &OutContainer) {
653       return ImportArrayChecked(
654           InContainer.begin(), InContainer.end(), OutContainer.begin());
655     }
656 
657     template<typename InContainerTy, typename OIter>
658     Error ImportArrayChecked(const InContainerTy &InContainer, OIter Obegin) {
659       return ImportArrayChecked(InContainer.begin(), InContainer.end(), Obegin);
660     }
661 
662     void ImportOverrides(CXXMethodDecl *ToMethod, CXXMethodDecl *FromMethod);
663 
664     Expected<FunctionDecl *> FindFunctionTemplateSpecialization(
665         FunctionDecl *FromFD);
666   };
667 
668 // FIXME: Temporary until every import returns Expected.
669 template <>
670 Expected<TemplateName> ASTNodeImporter::import(const TemplateName &From) {
671   TemplateName To = Importer.Import(From);
672   if (To.isNull() && !From.isNull())
673     return make_error<ImportError>();
674   return To;
675 }
676 
677 template <typename InContainerTy>
678 Error ASTNodeImporter::ImportTemplateArgumentListInfo(
679     SourceLocation FromLAngleLoc, SourceLocation FromRAngleLoc,
680     const InContainerTy &Container, TemplateArgumentListInfo &Result) {
681   auto ToLAngleLocOrErr = import(FromLAngleLoc);
682   if (!ToLAngleLocOrErr)
683     return ToLAngleLocOrErr.takeError();
684   auto ToRAngleLocOrErr = import(FromRAngleLoc);
685   if (!ToRAngleLocOrErr)
686     return ToRAngleLocOrErr.takeError();
687 
688   TemplateArgumentListInfo ToTAInfo(*ToLAngleLocOrErr, *ToRAngleLocOrErr);
689   if (auto Err = ImportTemplateArgumentListInfo(Container, ToTAInfo))
690     return Err;
691   Result = ToTAInfo;
692   return Error::success();
693 }
694 
695 template <>
696 Error ASTNodeImporter::ImportTemplateArgumentListInfo<TemplateArgumentListInfo>(
697     const TemplateArgumentListInfo &From, TemplateArgumentListInfo &Result) {
698   return ImportTemplateArgumentListInfo(
699       From.getLAngleLoc(), From.getRAngleLoc(), From.arguments(), Result);
700 }
701 
702 template <>
703 Error ASTNodeImporter::ImportTemplateArgumentListInfo<
704     ASTTemplateArgumentListInfo>(
705         const ASTTemplateArgumentListInfo &From,
706         TemplateArgumentListInfo &Result) {
707   return ImportTemplateArgumentListInfo(
708       From.LAngleLoc, From.RAngleLoc, From.arguments(), Result);
709 }
710 
711 Expected<ASTNodeImporter::FunctionTemplateAndArgsTy>
712 ASTNodeImporter::ImportFunctionTemplateWithTemplateArgsFromSpecialization(
713     FunctionDecl *FromFD) {
714   assert(FromFD->getTemplatedKind() ==
715       FunctionDecl::TK_FunctionTemplateSpecialization);
716 
717   FunctionTemplateAndArgsTy Result;
718 
719   auto *FTSInfo = FromFD->getTemplateSpecializationInfo();
720   if (Error Err = importInto(std::get<0>(Result), FTSInfo->getTemplate()))
721     return std::move(Err);
722 
723   // Import template arguments.
724   auto TemplArgs = FTSInfo->TemplateArguments->asArray();
725   if (Error Err = ImportTemplateArguments(TemplArgs.data(), TemplArgs.size(),
726       std::get<1>(Result)))
727     return std::move(Err);
728 
729   return Result;
730 }
731 
732 template <>
733 Expected<TemplateParameterList *>
734 ASTNodeImporter::import(TemplateParameterList *From) {
735   SmallVector<NamedDecl *, 4> To(From->size());
736   if (Error Err = ImportContainerChecked(*From, To))
737     return std::move(Err);
738 
739   ExpectedExpr ToRequiresClause = import(From->getRequiresClause());
740   if (!ToRequiresClause)
741     return ToRequiresClause.takeError();
742 
743   auto ToTemplateLocOrErr = import(From->getTemplateLoc());
744   if (!ToTemplateLocOrErr)
745     return ToTemplateLocOrErr.takeError();
746   auto ToLAngleLocOrErr = import(From->getLAngleLoc());
747   if (!ToLAngleLocOrErr)
748     return ToLAngleLocOrErr.takeError();
749   auto ToRAngleLocOrErr = import(From->getRAngleLoc());
750   if (!ToRAngleLocOrErr)
751     return ToRAngleLocOrErr.takeError();
752 
753   return TemplateParameterList::Create(
754       Importer.getToContext(),
755       *ToTemplateLocOrErr,
756       *ToLAngleLocOrErr,
757       To,
758       *ToRAngleLocOrErr,
759       *ToRequiresClause);
760 }
761 
762 template <>
763 Expected<TemplateArgument>
764 ASTNodeImporter::import(const TemplateArgument &From) {
765   switch (From.getKind()) {
766   case TemplateArgument::Null:
767     return TemplateArgument();
768 
769   case TemplateArgument::Type: {
770     ExpectedType ToTypeOrErr = import(From.getAsType());
771     if (!ToTypeOrErr)
772       return ToTypeOrErr.takeError();
773     return TemplateArgument(*ToTypeOrErr);
774   }
775 
776   case TemplateArgument::Integral: {
777     ExpectedType ToTypeOrErr = import(From.getIntegralType());
778     if (!ToTypeOrErr)
779       return ToTypeOrErr.takeError();
780     return TemplateArgument(From, *ToTypeOrErr);
781   }
782 
783   case TemplateArgument::Declaration: {
784     Expected<ValueDecl *> ToOrErr = import(From.getAsDecl());
785     if (!ToOrErr)
786       return ToOrErr.takeError();
787     ExpectedType ToTypeOrErr = import(From.getParamTypeForDecl());
788     if (!ToTypeOrErr)
789       return ToTypeOrErr.takeError();
790     return TemplateArgument(*ToOrErr, *ToTypeOrErr);
791   }
792 
793   case TemplateArgument::NullPtr: {
794     ExpectedType ToTypeOrErr = import(From.getNullPtrType());
795     if (!ToTypeOrErr)
796       return ToTypeOrErr.takeError();
797     return TemplateArgument(*ToTypeOrErr, /*isNullPtr*/true);
798   }
799 
800   case TemplateArgument::Template: {
801     Expected<TemplateName> ToTemplateOrErr = import(From.getAsTemplate());
802     if (!ToTemplateOrErr)
803       return ToTemplateOrErr.takeError();
804 
805     return TemplateArgument(*ToTemplateOrErr);
806   }
807 
808   case TemplateArgument::TemplateExpansion: {
809     Expected<TemplateName> ToTemplateOrErr =
810         import(From.getAsTemplateOrTemplatePattern());
811     if (!ToTemplateOrErr)
812       return ToTemplateOrErr.takeError();
813 
814     return TemplateArgument(
815         *ToTemplateOrErr, From.getNumTemplateExpansions());
816   }
817 
818   case TemplateArgument::Expression:
819     if (ExpectedExpr ToExpr = import(From.getAsExpr()))
820       return TemplateArgument(*ToExpr);
821     else
822       return ToExpr.takeError();
823 
824   case TemplateArgument::Pack: {
825     SmallVector<TemplateArgument, 2> ToPack;
826     ToPack.reserve(From.pack_size());
827     if (Error Err = ImportTemplateArguments(
828         From.pack_begin(), From.pack_size(), ToPack))
829       return std::move(Err);
830 
831     return TemplateArgument(
832         llvm::makeArrayRef(ToPack).copy(Importer.getToContext()));
833   }
834   }
835 
836   llvm_unreachable("Invalid template argument kind");
837 }
838 
839 template <>
840 Expected<TemplateArgumentLoc>
841 ASTNodeImporter::import(const TemplateArgumentLoc &TALoc) {
842   Expected<TemplateArgument> ArgOrErr = import(TALoc.getArgument());
843   if (!ArgOrErr)
844     return ArgOrErr.takeError();
845   TemplateArgument Arg = *ArgOrErr;
846 
847   TemplateArgumentLocInfo FromInfo = TALoc.getLocInfo();
848 
849   TemplateArgumentLocInfo ToInfo;
850   if (Arg.getKind() == TemplateArgument::Expression) {
851     ExpectedExpr E = import(FromInfo.getAsExpr());
852     if (!E)
853       return E.takeError();
854     ToInfo = TemplateArgumentLocInfo(*E);
855   } else if (Arg.getKind() == TemplateArgument::Type) {
856     if (auto TSIOrErr = import(FromInfo.getAsTypeSourceInfo()))
857       ToInfo = TemplateArgumentLocInfo(*TSIOrErr);
858     else
859       return TSIOrErr.takeError();
860   } else {
861     auto ToTemplateQualifierLocOrErr =
862         import(FromInfo.getTemplateQualifierLoc());
863     if (!ToTemplateQualifierLocOrErr)
864       return ToTemplateQualifierLocOrErr.takeError();
865     auto ToTemplateNameLocOrErr = import(FromInfo.getTemplateNameLoc());
866     if (!ToTemplateNameLocOrErr)
867       return ToTemplateNameLocOrErr.takeError();
868     auto ToTemplateEllipsisLocOrErr =
869         import(FromInfo.getTemplateEllipsisLoc());
870     if (!ToTemplateEllipsisLocOrErr)
871       return ToTemplateEllipsisLocOrErr.takeError();
872 
873     ToInfo = TemplateArgumentLocInfo(
874           *ToTemplateQualifierLocOrErr,
875           *ToTemplateNameLocOrErr,
876           *ToTemplateEllipsisLocOrErr);
877   }
878 
879   return TemplateArgumentLoc(Arg, ToInfo);
880 }
881 
882 template <>
883 Expected<DeclGroupRef> ASTNodeImporter::import(const DeclGroupRef &DG) {
884   if (DG.isNull())
885     return DeclGroupRef::Create(Importer.getToContext(), nullptr, 0);
886   size_t NumDecls = DG.end() - DG.begin();
887   SmallVector<Decl *, 1> ToDecls;
888   ToDecls.reserve(NumDecls);
889   for (Decl *FromD : DG) {
890     if (auto ToDOrErr = import(FromD))
891       ToDecls.push_back(*ToDOrErr);
892     else
893       return ToDOrErr.takeError();
894   }
895   return DeclGroupRef::Create(Importer.getToContext(),
896                               ToDecls.begin(),
897                               NumDecls);
898 }
899 
900 template <>
901 Expected<ASTNodeImporter::Designator>
902 ASTNodeImporter::import(const Designator &D) {
903   if (D.isFieldDesignator()) {
904     IdentifierInfo *ToFieldName = Importer.Import(D.getFieldName());
905 
906     ExpectedSLoc ToDotLocOrErr = import(D.getDotLoc());
907     if (!ToDotLocOrErr)
908       return ToDotLocOrErr.takeError();
909 
910     ExpectedSLoc ToFieldLocOrErr = import(D.getFieldLoc());
911     if (!ToFieldLocOrErr)
912       return ToFieldLocOrErr.takeError();
913 
914     return Designator(ToFieldName, *ToDotLocOrErr, *ToFieldLocOrErr);
915   }
916 
917   ExpectedSLoc ToLBracketLocOrErr = import(D.getLBracketLoc());
918   if (!ToLBracketLocOrErr)
919     return ToLBracketLocOrErr.takeError();
920 
921   ExpectedSLoc ToRBracketLocOrErr = import(D.getRBracketLoc());
922   if (!ToRBracketLocOrErr)
923     return ToRBracketLocOrErr.takeError();
924 
925   if (D.isArrayDesignator())
926     return Designator(D.getFirstExprIndex(),
927                       *ToLBracketLocOrErr, *ToRBracketLocOrErr);
928 
929   ExpectedSLoc ToEllipsisLocOrErr = import(D.getEllipsisLoc());
930   if (!ToEllipsisLocOrErr)
931     return ToEllipsisLocOrErr.takeError();
932 
933   assert(D.isArrayRangeDesignator());
934   return Designator(
935       D.getFirstExprIndex(), *ToLBracketLocOrErr, *ToEllipsisLocOrErr,
936       *ToRBracketLocOrErr);
937 }
938 
939 template <>
940 Expected<LambdaCapture> ASTNodeImporter::import(const LambdaCapture &From) {
941   VarDecl *Var = nullptr;
942   if (From.capturesVariable()) {
943     if (auto VarOrErr = import(From.getCapturedVar()))
944       Var = *VarOrErr;
945     else
946       return VarOrErr.takeError();
947   }
948 
949   auto LocationOrErr = import(From.getLocation());
950   if (!LocationOrErr)
951     return LocationOrErr.takeError();
952 
953   SourceLocation EllipsisLoc;
954   if (From.isPackExpansion())
955     if (Error Err = importInto(EllipsisLoc, From.getEllipsisLoc()))
956       return std::move(Err);
957 
958   return LambdaCapture(
959       *LocationOrErr, From.isImplicit(), From.getCaptureKind(), Var,
960       EllipsisLoc);
961 }
962 
963 } // namespace clang
964 
965 //----------------------------------------------------------------------------
966 // Import Types
967 //----------------------------------------------------------------------------
968 
969 using namespace clang;
970 
971 ExpectedType ASTNodeImporter::VisitType(const Type *T) {
972   Importer.FromDiag(SourceLocation(), diag::err_unsupported_ast_node)
973     << T->getTypeClassName();
974   return make_error<ImportError>(ImportError::UnsupportedConstruct);
975 }
976 
977 ExpectedType ASTNodeImporter::VisitAtomicType(const AtomicType *T){
978   ExpectedType UnderlyingTypeOrErr = import(T->getValueType());
979   if (!UnderlyingTypeOrErr)
980     return UnderlyingTypeOrErr.takeError();
981 
982   return Importer.getToContext().getAtomicType(*UnderlyingTypeOrErr);
983 }
984 
985 ExpectedType ASTNodeImporter::VisitBuiltinType(const BuiltinType *T) {
986   switch (T->getKind()) {
987 #define IMAGE_TYPE(ImgType, Id, SingletonId, Access, Suffix) \
988   case BuiltinType::Id: \
989     return Importer.getToContext().SingletonId;
990 #include "clang/Basic/OpenCLImageTypes.def"
991 #define SHARED_SINGLETON_TYPE(Expansion)
992 #define BUILTIN_TYPE(Id, SingletonId) \
993   case BuiltinType::Id: return Importer.getToContext().SingletonId;
994 #include "clang/AST/BuiltinTypes.def"
995 
996   // FIXME: for Char16, Char32, and NullPtr, make sure that the "to"
997   // context supports C++.
998 
999   // FIXME: for ObjCId, ObjCClass, and ObjCSel, make sure that the "to"
1000   // context supports ObjC.
1001 
1002   case BuiltinType::Char_U:
1003     // The context we're importing from has an unsigned 'char'. If we're
1004     // importing into a context with a signed 'char', translate to
1005     // 'unsigned char' instead.
1006     if (Importer.getToContext().getLangOpts().CharIsSigned)
1007       return Importer.getToContext().UnsignedCharTy;
1008 
1009     return Importer.getToContext().CharTy;
1010 
1011   case BuiltinType::Char_S:
1012     // The context we're importing from has an unsigned 'char'. If we're
1013     // importing into a context with a signed 'char', translate to
1014     // 'unsigned char' instead.
1015     if (!Importer.getToContext().getLangOpts().CharIsSigned)
1016       return Importer.getToContext().SignedCharTy;
1017 
1018     return Importer.getToContext().CharTy;
1019 
1020   case BuiltinType::WChar_S:
1021   case BuiltinType::WChar_U:
1022     // FIXME: If not in C++, shall we translate to the C equivalent of
1023     // wchar_t?
1024     return Importer.getToContext().WCharTy;
1025   }
1026 
1027   llvm_unreachable("Invalid BuiltinType Kind!");
1028 }
1029 
1030 ExpectedType ASTNodeImporter::VisitDecayedType(const DecayedType *T) {
1031   ExpectedType ToOriginalTypeOrErr = import(T->getOriginalType());
1032   if (!ToOriginalTypeOrErr)
1033     return ToOriginalTypeOrErr.takeError();
1034 
1035   return Importer.getToContext().getDecayedType(*ToOriginalTypeOrErr);
1036 }
1037 
1038 ExpectedType ASTNodeImporter::VisitComplexType(const ComplexType *T) {
1039   ExpectedType ToElementTypeOrErr = import(T->getElementType());
1040   if (!ToElementTypeOrErr)
1041     return ToElementTypeOrErr.takeError();
1042 
1043   return Importer.getToContext().getComplexType(*ToElementTypeOrErr);
1044 }
1045 
1046 ExpectedType ASTNodeImporter::VisitPointerType(const PointerType *T) {
1047   ExpectedType ToPointeeTypeOrErr = import(T->getPointeeType());
1048   if (!ToPointeeTypeOrErr)
1049     return ToPointeeTypeOrErr.takeError();
1050 
1051   return Importer.getToContext().getPointerType(*ToPointeeTypeOrErr);
1052 }
1053 
1054 ExpectedType ASTNodeImporter::VisitBlockPointerType(const BlockPointerType *T) {
1055   // FIXME: Check for blocks support in "to" context.
1056   ExpectedType ToPointeeTypeOrErr = import(T->getPointeeType());
1057   if (!ToPointeeTypeOrErr)
1058     return ToPointeeTypeOrErr.takeError();
1059 
1060   return Importer.getToContext().getBlockPointerType(*ToPointeeTypeOrErr);
1061 }
1062 
1063 ExpectedType
1064 ASTNodeImporter::VisitLValueReferenceType(const LValueReferenceType *T) {
1065   // FIXME: Check for C++ support in "to" context.
1066   ExpectedType ToPointeeTypeOrErr = import(T->getPointeeTypeAsWritten());
1067   if (!ToPointeeTypeOrErr)
1068     return ToPointeeTypeOrErr.takeError();
1069 
1070   return Importer.getToContext().getLValueReferenceType(*ToPointeeTypeOrErr);
1071 }
1072 
1073 ExpectedType
1074 ASTNodeImporter::VisitRValueReferenceType(const RValueReferenceType *T) {
1075   // FIXME: Check for C++0x support in "to" context.
1076   ExpectedType ToPointeeTypeOrErr = import(T->getPointeeTypeAsWritten());
1077   if (!ToPointeeTypeOrErr)
1078     return ToPointeeTypeOrErr.takeError();
1079 
1080   return Importer.getToContext().getRValueReferenceType(*ToPointeeTypeOrErr);
1081 }
1082 
1083 ExpectedType
1084 ASTNodeImporter::VisitMemberPointerType(const MemberPointerType *T) {
1085   // FIXME: Check for C++ support in "to" context.
1086   ExpectedType ToPointeeTypeOrErr = import(T->getPointeeType());
1087   if (!ToPointeeTypeOrErr)
1088     return ToPointeeTypeOrErr.takeError();
1089 
1090   ExpectedType ClassTypeOrErr = import(QualType(T->getClass(), 0));
1091   if (!ClassTypeOrErr)
1092     return ClassTypeOrErr.takeError();
1093 
1094   return Importer.getToContext().getMemberPointerType(
1095       *ToPointeeTypeOrErr, (*ClassTypeOrErr).getTypePtr());
1096 }
1097 
1098 ExpectedType
1099 ASTNodeImporter::VisitConstantArrayType(const ConstantArrayType *T) {
1100   ExpectedType ToElementTypeOrErr = import(T->getElementType());
1101   if (!ToElementTypeOrErr)
1102     return ToElementTypeOrErr.takeError();
1103 
1104   return Importer.getToContext().getConstantArrayType(*ToElementTypeOrErr,
1105                                                       T->getSize(),
1106                                                       T->getSizeModifier(),
1107                                                T->getIndexTypeCVRQualifiers());
1108 }
1109 
1110 ExpectedType
1111 ASTNodeImporter::VisitIncompleteArrayType(const IncompleteArrayType *T) {
1112   ExpectedType ToElementTypeOrErr = import(T->getElementType());
1113   if (!ToElementTypeOrErr)
1114     return ToElementTypeOrErr.takeError();
1115 
1116   return Importer.getToContext().getIncompleteArrayType(*ToElementTypeOrErr,
1117                                                         T->getSizeModifier(),
1118                                                 T->getIndexTypeCVRQualifiers());
1119 }
1120 
1121 ExpectedType
1122 ASTNodeImporter::VisitVariableArrayType(const VariableArrayType *T) {
1123   QualType ToElementType;
1124   Expr *ToSizeExpr;
1125   SourceRange ToBracketsRange;
1126   if (auto Imp = importSeq(
1127       T->getElementType(), T->getSizeExpr(), T->getBracketsRange()))
1128     std::tie(ToElementType, ToSizeExpr, ToBracketsRange) = *Imp;
1129   else
1130     return Imp.takeError();
1131 
1132   return Importer.getToContext().getVariableArrayType(
1133       ToElementType, ToSizeExpr, T->getSizeModifier(),
1134       T->getIndexTypeCVRQualifiers(), ToBracketsRange);
1135 }
1136 
1137 ExpectedType ASTNodeImporter::VisitDependentSizedArrayType(
1138     const DependentSizedArrayType *T) {
1139   QualType ToElementType;
1140   Expr *ToSizeExpr;
1141   SourceRange ToBracketsRange;
1142   if (auto Imp = importSeq(
1143       T->getElementType(), T->getSizeExpr(), T->getBracketsRange()))
1144     std::tie(ToElementType, ToSizeExpr, ToBracketsRange) = *Imp;
1145   else
1146     return Imp.takeError();
1147   // SizeExpr may be null if size is not specified directly.
1148   // For example, 'int a[]'.
1149 
1150   return Importer.getToContext().getDependentSizedArrayType(
1151       ToElementType, ToSizeExpr, T->getSizeModifier(),
1152       T->getIndexTypeCVRQualifiers(), ToBracketsRange);
1153 }
1154 
1155 ExpectedType ASTNodeImporter::VisitVectorType(const VectorType *T) {
1156   ExpectedType ToElementTypeOrErr = import(T->getElementType());
1157   if (!ToElementTypeOrErr)
1158     return ToElementTypeOrErr.takeError();
1159 
1160   return Importer.getToContext().getVectorType(*ToElementTypeOrErr,
1161                                                T->getNumElements(),
1162                                                T->getVectorKind());
1163 }
1164 
1165 ExpectedType ASTNodeImporter::VisitExtVectorType(const ExtVectorType *T) {
1166   ExpectedType ToElementTypeOrErr = import(T->getElementType());
1167   if (!ToElementTypeOrErr)
1168     return ToElementTypeOrErr.takeError();
1169 
1170   return Importer.getToContext().getExtVectorType(*ToElementTypeOrErr,
1171                                                   T->getNumElements());
1172 }
1173 
1174 ExpectedType
1175 ASTNodeImporter::VisitFunctionNoProtoType(const FunctionNoProtoType *T) {
1176   // FIXME: What happens if we're importing a function without a prototype
1177   // into C++? Should we make it variadic?
1178   ExpectedType ToReturnTypeOrErr = import(T->getReturnType());
1179   if (!ToReturnTypeOrErr)
1180     return ToReturnTypeOrErr.takeError();
1181 
1182   return Importer.getToContext().getFunctionNoProtoType(*ToReturnTypeOrErr,
1183                                                         T->getExtInfo());
1184 }
1185 
1186 ExpectedType
1187 ASTNodeImporter::VisitFunctionProtoType(const FunctionProtoType *T) {
1188   ExpectedType ToReturnTypeOrErr = import(T->getReturnType());
1189   if (!ToReturnTypeOrErr)
1190     return ToReturnTypeOrErr.takeError();
1191 
1192   // Import argument types
1193   SmallVector<QualType, 4> ArgTypes;
1194   for (const auto &A : T->param_types()) {
1195     ExpectedType TyOrErr = import(A);
1196     if (!TyOrErr)
1197       return TyOrErr.takeError();
1198     ArgTypes.push_back(*TyOrErr);
1199   }
1200 
1201   // Import exception types
1202   SmallVector<QualType, 4> ExceptionTypes;
1203   for (const auto &E : T->exceptions()) {
1204     ExpectedType TyOrErr = import(E);
1205     if (!TyOrErr)
1206       return TyOrErr.takeError();
1207     ExceptionTypes.push_back(*TyOrErr);
1208   }
1209 
1210   FunctionProtoType::ExtProtoInfo FromEPI = T->getExtProtoInfo();
1211   FunctionProtoType::ExtProtoInfo ToEPI;
1212 
1213   auto Imp = importSeq(
1214       FromEPI.ExceptionSpec.NoexceptExpr,
1215       FromEPI.ExceptionSpec.SourceDecl,
1216       FromEPI.ExceptionSpec.SourceTemplate);
1217   if (!Imp)
1218     return Imp.takeError();
1219 
1220   ToEPI.ExtInfo = FromEPI.ExtInfo;
1221   ToEPI.Variadic = FromEPI.Variadic;
1222   ToEPI.HasTrailingReturn = FromEPI.HasTrailingReturn;
1223   ToEPI.TypeQuals = FromEPI.TypeQuals;
1224   ToEPI.RefQualifier = FromEPI.RefQualifier;
1225   ToEPI.ExceptionSpec.Type = FromEPI.ExceptionSpec.Type;
1226   ToEPI.ExceptionSpec.Exceptions = ExceptionTypes;
1227   std::tie(
1228       ToEPI.ExceptionSpec.NoexceptExpr,
1229       ToEPI.ExceptionSpec.SourceDecl,
1230       ToEPI.ExceptionSpec.SourceTemplate) = *Imp;
1231 
1232   return Importer.getToContext().getFunctionType(
1233       *ToReturnTypeOrErr, ArgTypes, ToEPI);
1234 }
1235 
1236 ExpectedType ASTNodeImporter::VisitUnresolvedUsingType(
1237     const UnresolvedUsingType *T) {
1238   UnresolvedUsingTypenameDecl *ToD;
1239   Decl *ToPrevD;
1240   if (auto Imp = importSeq(T->getDecl(), T->getDecl()->getPreviousDecl()))
1241     std::tie(ToD, ToPrevD) = *Imp;
1242   else
1243     return Imp.takeError();
1244 
1245   return Importer.getToContext().getTypeDeclType(
1246       ToD, cast_or_null<TypeDecl>(ToPrevD));
1247 }
1248 
1249 ExpectedType ASTNodeImporter::VisitParenType(const ParenType *T) {
1250   ExpectedType ToInnerTypeOrErr = import(T->getInnerType());
1251   if (!ToInnerTypeOrErr)
1252     return ToInnerTypeOrErr.takeError();
1253 
1254   return Importer.getToContext().getParenType(*ToInnerTypeOrErr);
1255 }
1256 
1257 ExpectedType ASTNodeImporter::VisitTypedefType(const TypedefType *T) {
1258   Expected<TypedefNameDecl *> ToDeclOrErr = import(T->getDecl());
1259   if (!ToDeclOrErr)
1260     return ToDeclOrErr.takeError();
1261 
1262   return Importer.getToContext().getTypeDeclType(*ToDeclOrErr);
1263 }
1264 
1265 ExpectedType ASTNodeImporter::VisitTypeOfExprType(const TypeOfExprType *T) {
1266   ExpectedExpr ToExprOrErr = import(T->getUnderlyingExpr());
1267   if (!ToExprOrErr)
1268     return ToExprOrErr.takeError();
1269 
1270   return Importer.getToContext().getTypeOfExprType(*ToExprOrErr);
1271 }
1272 
1273 ExpectedType ASTNodeImporter::VisitTypeOfType(const TypeOfType *T) {
1274   ExpectedType ToUnderlyingTypeOrErr = import(T->getUnderlyingType());
1275   if (!ToUnderlyingTypeOrErr)
1276     return ToUnderlyingTypeOrErr.takeError();
1277 
1278   return Importer.getToContext().getTypeOfType(*ToUnderlyingTypeOrErr);
1279 }
1280 
1281 ExpectedType ASTNodeImporter::VisitDecltypeType(const DecltypeType *T) {
1282   // FIXME: Make sure that the "to" context supports C++0x!
1283   ExpectedExpr ToExprOrErr = import(T->getUnderlyingExpr());
1284   if (!ToExprOrErr)
1285     return ToExprOrErr.takeError();
1286 
1287   ExpectedType ToUnderlyingTypeOrErr = import(T->getUnderlyingType());
1288   if (!ToUnderlyingTypeOrErr)
1289     return ToUnderlyingTypeOrErr.takeError();
1290 
1291   return Importer.getToContext().getDecltypeType(
1292       *ToExprOrErr, *ToUnderlyingTypeOrErr);
1293 }
1294 
1295 ExpectedType
1296 ASTNodeImporter::VisitUnaryTransformType(const UnaryTransformType *T) {
1297   ExpectedType ToBaseTypeOrErr = import(T->getBaseType());
1298   if (!ToBaseTypeOrErr)
1299     return ToBaseTypeOrErr.takeError();
1300 
1301   ExpectedType ToUnderlyingTypeOrErr = import(T->getUnderlyingType());
1302   if (!ToUnderlyingTypeOrErr)
1303     return ToUnderlyingTypeOrErr.takeError();
1304 
1305   return Importer.getToContext().getUnaryTransformType(
1306       *ToBaseTypeOrErr, *ToUnderlyingTypeOrErr, T->getUTTKind());
1307 }
1308 
1309 ExpectedType ASTNodeImporter::VisitAutoType(const AutoType *T) {
1310   // FIXME: Make sure that the "to" context supports C++11!
1311   ExpectedType ToDeducedTypeOrErr = import(T->getDeducedType());
1312   if (!ToDeducedTypeOrErr)
1313     return ToDeducedTypeOrErr.takeError();
1314 
1315   return Importer.getToContext().getAutoType(*ToDeducedTypeOrErr,
1316                                              T->getKeyword(),
1317                                              /*IsDependent*/false);
1318 }
1319 
1320 ExpectedType ASTNodeImporter::VisitInjectedClassNameType(
1321     const InjectedClassNameType *T) {
1322   Expected<CXXRecordDecl *> ToDeclOrErr = import(T->getDecl());
1323   if (!ToDeclOrErr)
1324     return ToDeclOrErr.takeError();
1325 
1326   ExpectedType ToInjTypeOrErr = import(T->getInjectedSpecializationType());
1327   if (!ToInjTypeOrErr)
1328     return ToInjTypeOrErr.takeError();
1329 
1330   // FIXME: ASTContext::getInjectedClassNameType is not suitable for AST reading
1331   // See comments in InjectedClassNameType definition for details
1332   // return Importer.getToContext().getInjectedClassNameType(D, InjType);
1333   enum {
1334     TypeAlignmentInBits = 4,
1335     TypeAlignment = 1 << TypeAlignmentInBits
1336   };
1337 
1338   return QualType(new (Importer.getToContext(), TypeAlignment)
1339                   InjectedClassNameType(*ToDeclOrErr, *ToInjTypeOrErr), 0);
1340 }
1341 
1342 ExpectedType ASTNodeImporter::VisitRecordType(const RecordType *T) {
1343   Expected<RecordDecl *> ToDeclOrErr = import(T->getDecl());
1344   if (!ToDeclOrErr)
1345     return ToDeclOrErr.takeError();
1346 
1347   return Importer.getToContext().getTagDeclType(*ToDeclOrErr);
1348 }
1349 
1350 ExpectedType ASTNodeImporter::VisitEnumType(const EnumType *T) {
1351   Expected<EnumDecl *> ToDeclOrErr = import(T->getDecl());
1352   if (!ToDeclOrErr)
1353     return ToDeclOrErr.takeError();
1354 
1355   return Importer.getToContext().getTagDeclType(*ToDeclOrErr);
1356 }
1357 
1358 ExpectedType ASTNodeImporter::VisitAttributedType(const AttributedType *T) {
1359   ExpectedType ToModifiedTypeOrErr = import(T->getModifiedType());
1360   if (!ToModifiedTypeOrErr)
1361     return ToModifiedTypeOrErr.takeError();
1362   ExpectedType ToEquivalentTypeOrErr = import(T->getEquivalentType());
1363   if (!ToEquivalentTypeOrErr)
1364     return ToEquivalentTypeOrErr.takeError();
1365 
1366   return Importer.getToContext().getAttributedType(T->getAttrKind(),
1367       *ToModifiedTypeOrErr, *ToEquivalentTypeOrErr);
1368 }
1369 
1370 ExpectedType ASTNodeImporter::VisitTemplateTypeParmType(
1371     const TemplateTypeParmType *T) {
1372   Expected<TemplateTypeParmDecl *> ToDeclOrErr = import(T->getDecl());
1373   if (!ToDeclOrErr)
1374     return ToDeclOrErr.takeError();
1375 
1376   return Importer.getToContext().getTemplateTypeParmType(
1377       T->getDepth(), T->getIndex(), T->isParameterPack(), *ToDeclOrErr);
1378 }
1379 
1380 ExpectedType ASTNodeImporter::VisitSubstTemplateTypeParmType(
1381     const SubstTemplateTypeParmType *T) {
1382   ExpectedType ReplacedOrErr = import(QualType(T->getReplacedParameter(), 0));
1383   if (!ReplacedOrErr)
1384     return ReplacedOrErr.takeError();
1385   const TemplateTypeParmType *Replaced =
1386       cast<TemplateTypeParmType>((*ReplacedOrErr).getTypePtr());
1387 
1388   ExpectedType ToReplacementTypeOrErr = import(T->getReplacementType());
1389   if (!ToReplacementTypeOrErr)
1390     return ToReplacementTypeOrErr.takeError();
1391 
1392   return Importer.getToContext().getSubstTemplateTypeParmType(
1393         Replaced, (*ToReplacementTypeOrErr).getCanonicalType());
1394 }
1395 
1396 ExpectedType ASTNodeImporter::VisitTemplateSpecializationType(
1397                                        const TemplateSpecializationType *T) {
1398   auto ToTemplateOrErr = import(T->getTemplateName());
1399   if (!ToTemplateOrErr)
1400     return ToTemplateOrErr.takeError();
1401 
1402   SmallVector<TemplateArgument, 2> ToTemplateArgs;
1403   if (Error Err = ImportTemplateArguments(
1404       T->getArgs(), T->getNumArgs(), ToTemplateArgs))
1405     return std::move(Err);
1406 
1407   QualType ToCanonType;
1408   if (!QualType(T, 0).isCanonical()) {
1409     QualType FromCanonType
1410       = Importer.getFromContext().getCanonicalType(QualType(T, 0));
1411     if (ExpectedType TyOrErr = import(FromCanonType))
1412       ToCanonType = *TyOrErr;
1413     else
1414       return TyOrErr.takeError();
1415   }
1416   return Importer.getToContext().getTemplateSpecializationType(*ToTemplateOrErr,
1417                                                                ToTemplateArgs,
1418                                                                ToCanonType);
1419 }
1420 
1421 ExpectedType ASTNodeImporter::VisitElaboratedType(const ElaboratedType *T) {
1422   // Note: the qualifier in an ElaboratedType is optional.
1423   auto ToQualifierOrErr = import(T->getQualifier());
1424   if (!ToQualifierOrErr)
1425     return ToQualifierOrErr.takeError();
1426 
1427   ExpectedType ToNamedTypeOrErr = import(T->getNamedType());
1428   if (!ToNamedTypeOrErr)
1429     return ToNamedTypeOrErr.takeError();
1430 
1431   Expected<TagDecl *> ToOwnedTagDeclOrErr = import(T->getOwnedTagDecl());
1432   if (!ToOwnedTagDeclOrErr)
1433     return ToOwnedTagDeclOrErr.takeError();
1434 
1435   return Importer.getToContext().getElaboratedType(T->getKeyword(),
1436                                                    *ToQualifierOrErr,
1437                                                    *ToNamedTypeOrErr,
1438                                                    *ToOwnedTagDeclOrErr);
1439 }
1440 
1441 ExpectedType
1442 ASTNodeImporter::VisitPackExpansionType(const PackExpansionType *T) {
1443   ExpectedType ToPatternOrErr = import(T->getPattern());
1444   if (!ToPatternOrErr)
1445     return ToPatternOrErr.takeError();
1446 
1447   return Importer.getToContext().getPackExpansionType(*ToPatternOrErr,
1448                                                       T->getNumExpansions());
1449 }
1450 
1451 ExpectedType ASTNodeImporter::VisitDependentTemplateSpecializationType(
1452     const DependentTemplateSpecializationType *T) {
1453   auto ToQualifierOrErr = import(T->getQualifier());
1454   if (!ToQualifierOrErr)
1455     return ToQualifierOrErr.takeError();
1456 
1457   IdentifierInfo *ToName = Importer.Import(T->getIdentifier());
1458 
1459   SmallVector<TemplateArgument, 2> ToPack;
1460   ToPack.reserve(T->getNumArgs());
1461   if (Error Err = ImportTemplateArguments(
1462       T->getArgs(), T->getNumArgs(), ToPack))
1463     return std::move(Err);
1464 
1465   return Importer.getToContext().getDependentTemplateSpecializationType(
1466       T->getKeyword(), *ToQualifierOrErr, ToName, ToPack);
1467 }
1468 
1469 ExpectedType
1470 ASTNodeImporter::VisitDependentNameType(const DependentNameType *T) {
1471   auto ToQualifierOrErr = import(T->getQualifier());
1472   if (!ToQualifierOrErr)
1473     return ToQualifierOrErr.takeError();
1474 
1475   IdentifierInfo *Name = Importer.Import(T->getIdentifier());
1476 
1477   QualType Canon;
1478   if (T != T->getCanonicalTypeInternal().getTypePtr()) {
1479     if (ExpectedType TyOrErr = import(T->getCanonicalTypeInternal()))
1480       Canon = (*TyOrErr).getCanonicalType();
1481     else
1482       return TyOrErr.takeError();
1483   }
1484 
1485   return Importer.getToContext().getDependentNameType(T->getKeyword(),
1486                                                       *ToQualifierOrErr,
1487                                                       Name, Canon);
1488 }
1489 
1490 ExpectedType
1491 ASTNodeImporter::VisitObjCInterfaceType(const ObjCInterfaceType *T) {
1492   Expected<ObjCInterfaceDecl *> ToDeclOrErr = import(T->getDecl());
1493   if (!ToDeclOrErr)
1494     return ToDeclOrErr.takeError();
1495 
1496   return Importer.getToContext().getObjCInterfaceType(*ToDeclOrErr);
1497 }
1498 
1499 ExpectedType ASTNodeImporter::VisitObjCObjectType(const ObjCObjectType *T) {
1500   ExpectedType ToBaseTypeOrErr = import(T->getBaseType());
1501   if (!ToBaseTypeOrErr)
1502     return ToBaseTypeOrErr.takeError();
1503 
1504   SmallVector<QualType, 4> TypeArgs;
1505   for (auto TypeArg : T->getTypeArgsAsWritten()) {
1506     if (ExpectedType TyOrErr = import(TypeArg))
1507       TypeArgs.push_back(*TyOrErr);
1508     else
1509       return TyOrErr.takeError();
1510   }
1511 
1512   SmallVector<ObjCProtocolDecl *, 4> Protocols;
1513   for (auto *P : T->quals()) {
1514     if (Expected<ObjCProtocolDecl *> ProtocolOrErr = import(P))
1515       Protocols.push_back(*ProtocolOrErr);
1516     else
1517       return ProtocolOrErr.takeError();
1518 
1519   }
1520 
1521   return Importer.getToContext().getObjCObjectType(*ToBaseTypeOrErr, TypeArgs,
1522                                                    Protocols,
1523                                                    T->isKindOfTypeAsWritten());
1524 }
1525 
1526 ExpectedType
1527 ASTNodeImporter::VisitObjCObjectPointerType(const ObjCObjectPointerType *T) {
1528   ExpectedType ToPointeeTypeOrErr = import(T->getPointeeType());
1529   if (!ToPointeeTypeOrErr)
1530     return ToPointeeTypeOrErr.takeError();
1531 
1532   return Importer.getToContext().getObjCObjectPointerType(*ToPointeeTypeOrErr);
1533 }
1534 
1535 //----------------------------------------------------------------------------
1536 // Import Declarations
1537 //----------------------------------------------------------------------------
1538 Error ASTNodeImporter::ImportDeclParts(
1539     NamedDecl *D, DeclContext *&DC, DeclContext *&LexicalDC,
1540     DeclarationName &Name, NamedDecl *&ToD, SourceLocation &Loc) {
1541   // Check if RecordDecl is in FunctionDecl parameters to avoid infinite loop.
1542   // example: int struct_in_proto(struct data_t{int a;int b;} *d);
1543   DeclContext *OrigDC = D->getDeclContext();
1544   FunctionDecl *FunDecl;
1545   if (isa<RecordDecl>(D) && (FunDecl = dyn_cast<FunctionDecl>(OrigDC)) &&
1546       FunDecl->hasBody()) {
1547     auto getLeafPointeeType = [](const Type *T) {
1548       while (T->isPointerType() || T->isArrayType()) {
1549         T = T->getPointeeOrArrayElementType();
1550       }
1551       return T;
1552     };
1553     for (const ParmVarDecl *P : FunDecl->parameters()) {
1554       const Type *LeafT =
1555           getLeafPointeeType(P->getType().getCanonicalType().getTypePtr());
1556       auto *RT = dyn_cast<RecordType>(LeafT);
1557       if (RT && RT->getDecl() == D) {
1558         Importer.FromDiag(D->getLocation(), diag::err_unsupported_ast_node)
1559             << D->getDeclKindName();
1560         return make_error<ImportError>(ImportError::UnsupportedConstruct);
1561       }
1562     }
1563   }
1564 
1565   // Import the context of this declaration.
1566   if (Error Err = ImportDeclContext(D, DC, LexicalDC))
1567     return Err;
1568 
1569   // Import the name of this declaration.
1570   if (Error Err = importInto(Name, D->getDeclName()))
1571     return Err;
1572 
1573   // Import the location of this declaration.
1574   if (Error Err = importInto(Loc, D->getLocation()))
1575     return Err;
1576 
1577   ToD = cast_or_null<NamedDecl>(Importer.GetAlreadyImportedOrNull(D));
1578 
1579   return Error::success();
1580 }
1581 
1582 Error ASTNodeImporter::ImportDefinitionIfNeeded(Decl *FromD, Decl *ToD) {
1583   if (!FromD)
1584     return Error::success();
1585 
1586   if (!ToD)
1587     if (Error Err = importInto(ToD, FromD))
1588       return Err;
1589 
1590   if (RecordDecl *FromRecord = dyn_cast<RecordDecl>(FromD)) {
1591     if (RecordDecl *ToRecord = cast<RecordDecl>(ToD)) {
1592       if (FromRecord->getDefinition() && FromRecord->isCompleteDefinition() &&
1593           !ToRecord->getDefinition()) {
1594         if (Error Err = ImportDefinition(FromRecord, ToRecord))
1595           return Err;
1596       }
1597     }
1598     return Error::success();
1599   }
1600 
1601   if (EnumDecl *FromEnum = dyn_cast<EnumDecl>(FromD)) {
1602     if (EnumDecl *ToEnum = cast<EnumDecl>(ToD)) {
1603       if (FromEnum->getDefinition() && !ToEnum->getDefinition()) {
1604         if (Error Err = ImportDefinition(FromEnum, ToEnum))
1605           return Err;
1606       }
1607     }
1608     return Error::success();
1609   }
1610 
1611   return Error::success();
1612 }
1613 
1614 Error
1615 ASTNodeImporter::ImportDeclarationNameLoc(
1616     const DeclarationNameInfo &From, DeclarationNameInfo& To) {
1617   // NOTE: To.Name and To.Loc are already imported.
1618   // We only have to import To.LocInfo.
1619   switch (To.getName().getNameKind()) {
1620   case DeclarationName::Identifier:
1621   case DeclarationName::ObjCZeroArgSelector:
1622   case DeclarationName::ObjCOneArgSelector:
1623   case DeclarationName::ObjCMultiArgSelector:
1624   case DeclarationName::CXXUsingDirective:
1625   case DeclarationName::CXXDeductionGuideName:
1626     return Error::success();
1627 
1628   case DeclarationName::CXXOperatorName: {
1629     if (auto ToRangeOrErr = import(From.getCXXOperatorNameRange()))
1630       To.setCXXOperatorNameRange(*ToRangeOrErr);
1631     else
1632       return ToRangeOrErr.takeError();
1633     return Error::success();
1634   }
1635   case DeclarationName::CXXLiteralOperatorName: {
1636     if (ExpectedSLoc LocOrErr = import(From.getCXXLiteralOperatorNameLoc()))
1637       To.setCXXLiteralOperatorNameLoc(*LocOrErr);
1638     else
1639       return LocOrErr.takeError();
1640     return Error::success();
1641   }
1642   case DeclarationName::CXXConstructorName:
1643   case DeclarationName::CXXDestructorName:
1644   case DeclarationName::CXXConversionFunctionName: {
1645     if (auto ToTInfoOrErr = import(From.getNamedTypeInfo()))
1646       To.setNamedTypeInfo(*ToTInfoOrErr);
1647     else
1648       return ToTInfoOrErr.takeError();
1649     return Error::success();
1650   }
1651   }
1652   llvm_unreachable("Unknown name kind.");
1653 }
1654 
1655 Error
1656 ASTNodeImporter::ImportDeclContext(DeclContext *FromDC, bool ForceImport) {
1657   if (Importer.isMinimalImport() && !ForceImport) {
1658     auto ToDCOrErr = Importer.ImportContext(FromDC);
1659     return ToDCOrErr.takeError();
1660   }
1661   llvm::SmallVector<Decl *, 8> ImportedDecls;
1662   for (auto *From : FromDC->decls()) {
1663     ExpectedDecl ImportedOrErr = import(From);
1664     if (!ImportedOrErr)
1665       // Ignore the error, continue with next Decl.
1666       // FIXME: Handle this case somehow better.
1667       consumeError(ImportedOrErr.takeError());
1668   }
1669 
1670   return Error::success();
1671 }
1672 
1673 Error ASTNodeImporter::ImportDeclContext(
1674     Decl *FromD, DeclContext *&ToDC, DeclContext *&ToLexicalDC) {
1675   auto ToDCOrErr = Importer.ImportContext(FromD->getDeclContext());
1676   if (!ToDCOrErr)
1677     return ToDCOrErr.takeError();
1678   ToDC = *ToDCOrErr;
1679 
1680   if (FromD->getDeclContext() != FromD->getLexicalDeclContext()) {
1681     auto ToLexicalDCOrErr = Importer.ImportContext(
1682         FromD->getLexicalDeclContext());
1683     if (!ToLexicalDCOrErr)
1684       return ToLexicalDCOrErr.takeError();
1685     ToLexicalDC = *ToLexicalDCOrErr;
1686   } else
1687     ToLexicalDC = ToDC;
1688 
1689   return Error::success();
1690 }
1691 
1692 Error ASTNodeImporter::ImportImplicitMethods(
1693     const CXXRecordDecl *From, CXXRecordDecl *To) {
1694   assert(From->isCompleteDefinition() && To->getDefinition() == To &&
1695       "Import implicit methods to or from non-definition");
1696 
1697   for (CXXMethodDecl *FromM : From->methods())
1698     if (FromM->isImplicit()) {
1699       Expected<CXXMethodDecl *> ToMOrErr = import(FromM);
1700       if (!ToMOrErr)
1701         return ToMOrErr.takeError();
1702     }
1703 
1704   return Error::success();
1705 }
1706 
1707 static Error setTypedefNameForAnonDecl(TagDecl *From, TagDecl *To,
1708                                        ASTImporter &Importer) {
1709   if (TypedefNameDecl *FromTypedef = From->getTypedefNameForAnonDecl()) {
1710     Decl *ToTypedef = Importer.Import(FromTypedef);
1711     if (!ToTypedef)
1712       return make_error<ImportError>();
1713     To->setTypedefNameForAnonDecl(cast<TypedefNameDecl>(ToTypedef));
1714     // FIXME: This should be the final code.
1715     //if (Expected<Decl *> ToTypedefOrErr = Importer.Import(FromTypedef))
1716     //  To->setTypedefNameForAnonDecl(cast<TypedefNameDecl>(*ToTypedefOrErr));
1717     //else
1718     //  return ToTypedefOrErr.takeError();
1719   }
1720   return Error::success();
1721 }
1722 
1723 Error ASTNodeImporter::ImportDefinition(
1724     RecordDecl *From, RecordDecl *To, ImportDefinitionKind Kind) {
1725   if (To->getDefinition() || To->isBeingDefined()) {
1726     if (Kind == IDK_Everything)
1727       return ImportDeclContext(From, /*ForceImport=*/true);
1728 
1729     return Error::success();
1730   }
1731 
1732   To->startDefinition();
1733 
1734   if (Error Err = setTypedefNameForAnonDecl(From, To, Importer))
1735     return Err;
1736 
1737   // Add base classes.
1738   if (auto *ToCXX = dyn_cast<CXXRecordDecl>(To)) {
1739     auto *FromCXX = cast<CXXRecordDecl>(From);
1740 
1741     struct CXXRecordDecl::DefinitionData &ToData = ToCXX->data();
1742     struct CXXRecordDecl::DefinitionData &FromData = FromCXX->data();
1743     ToData.UserDeclaredConstructor = FromData.UserDeclaredConstructor;
1744     ToData.UserDeclaredSpecialMembers = FromData.UserDeclaredSpecialMembers;
1745     ToData.Aggregate = FromData.Aggregate;
1746     ToData.PlainOldData = FromData.PlainOldData;
1747     ToData.Empty = FromData.Empty;
1748     ToData.Polymorphic = FromData.Polymorphic;
1749     ToData.Abstract = FromData.Abstract;
1750     ToData.IsStandardLayout = FromData.IsStandardLayout;
1751     ToData.IsCXX11StandardLayout = FromData.IsCXX11StandardLayout;
1752     ToData.HasBasesWithFields = FromData.HasBasesWithFields;
1753     ToData.HasBasesWithNonStaticDataMembers =
1754         FromData.HasBasesWithNonStaticDataMembers;
1755     ToData.HasPrivateFields = FromData.HasPrivateFields;
1756     ToData.HasProtectedFields = FromData.HasProtectedFields;
1757     ToData.HasPublicFields = FromData.HasPublicFields;
1758     ToData.HasMutableFields = FromData.HasMutableFields;
1759     ToData.HasVariantMembers = FromData.HasVariantMembers;
1760     ToData.HasOnlyCMembers = FromData.HasOnlyCMembers;
1761     ToData.HasInClassInitializer = FromData.HasInClassInitializer;
1762     ToData.HasUninitializedReferenceMember
1763       = FromData.HasUninitializedReferenceMember;
1764     ToData.HasUninitializedFields = FromData.HasUninitializedFields;
1765     ToData.HasInheritedConstructor = FromData.HasInheritedConstructor;
1766     ToData.HasInheritedAssignment = FromData.HasInheritedAssignment;
1767     ToData.NeedOverloadResolutionForCopyConstructor
1768       = FromData.NeedOverloadResolutionForCopyConstructor;
1769     ToData.NeedOverloadResolutionForMoveConstructor
1770       = FromData.NeedOverloadResolutionForMoveConstructor;
1771     ToData.NeedOverloadResolutionForMoveAssignment
1772       = FromData.NeedOverloadResolutionForMoveAssignment;
1773     ToData.NeedOverloadResolutionForDestructor
1774       = FromData.NeedOverloadResolutionForDestructor;
1775     ToData.DefaultedCopyConstructorIsDeleted
1776       = FromData.DefaultedCopyConstructorIsDeleted;
1777     ToData.DefaultedMoveConstructorIsDeleted
1778       = FromData.DefaultedMoveConstructorIsDeleted;
1779     ToData.DefaultedMoveAssignmentIsDeleted
1780       = FromData.DefaultedMoveAssignmentIsDeleted;
1781     ToData.DefaultedDestructorIsDeleted = FromData.DefaultedDestructorIsDeleted;
1782     ToData.HasTrivialSpecialMembers = FromData.HasTrivialSpecialMembers;
1783     ToData.HasIrrelevantDestructor = FromData.HasIrrelevantDestructor;
1784     ToData.HasConstexprNonCopyMoveConstructor
1785       = FromData.HasConstexprNonCopyMoveConstructor;
1786     ToData.HasDefaultedDefaultConstructor
1787       = FromData.HasDefaultedDefaultConstructor;
1788     ToData.DefaultedDefaultConstructorIsConstexpr
1789       = FromData.DefaultedDefaultConstructorIsConstexpr;
1790     ToData.HasConstexprDefaultConstructor
1791       = FromData.HasConstexprDefaultConstructor;
1792     ToData.HasNonLiteralTypeFieldsOrBases
1793       = FromData.HasNonLiteralTypeFieldsOrBases;
1794     // ComputedVisibleConversions not imported.
1795     ToData.UserProvidedDefaultConstructor
1796       = FromData.UserProvidedDefaultConstructor;
1797     ToData.DeclaredSpecialMembers = FromData.DeclaredSpecialMembers;
1798     ToData.ImplicitCopyConstructorCanHaveConstParamForVBase
1799       = FromData.ImplicitCopyConstructorCanHaveConstParamForVBase;
1800     ToData.ImplicitCopyConstructorCanHaveConstParamForNonVBase
1801       = FromData.ImplicitCopyConstructorCanHaveConstParamForNonVBase;
1802     ToData.ImplicitCopyAssignmentHasConstParam
1803       = FromData.ImplicitCopyAssignmentHasConstParam;
1804     ToData.HasDeclaredCopyConstructorWithConstParam
1805       = FromData.HasDeclaredCopyConstructorWithConstParam;
1806     ToData.HasDeclaredCopyAssignmentWithConstParam
1807       = FromData.HasDeclaredCopyAssignmentWithConstParam;
1808 
1809     SmallVector<CXXBaseSpecifier *, 4> Bases;
1810     for (const auto &Base1 : FromCXX->bases()) {
1811       ExpectedType TyOrErr = import(Base1.getType());
1812       if (!TyOrErr)
1813         return TyOrErr.takeError();
1814 
1815       SourceLocation EllipsisLoc;
1816       if (Base1.isPackExpansion()) {
1817         if (ExpectedSLoc LocOrErr = import(Base1.getEllipsisLoc()))
1818           EllipsisLoc = *LocOrErr;
1819         else
1820           return LocOrErr.takeError();
1821       }
1822 
1823       // Ensure that we have a definition for the base.
1824       if (Error Err =
1825           ImportDefinitionIfNeeded(Base1.getType()->getAsCXXRecordDecl()))
1826         return Err;
1827 
1828       auto RangeOrErr = import(Base1.getSourceRange());
1829       if (!RangeOrErr)
1830         return RangeOrErr.takeError();
1831 
1832       auto TSIOrErr = import(Base1.getTypeSourceInfo());
1833       if (!TSIOrErr)
1834         return TSIOrErr.takeError();
1835 
1836       Bases.push_back(
1837           new (Importer.getToContext()) CXXBaseSpecifier(
1838               *RangeOrErr,
1839               Base1.isVirtual(),
1840               Base1.isBaseOfClass(),
1841               Base1.getAccessSpecifierAsWritten(),
1842               *TSIOrErr,
1843               EllipsisLoc));
1844     }
1845     if (!Bases.empty())
1846       ToCXX->setBases(Bases.data(), Bases.size());
1847   }
1848 
1849   if (shouldForceImportDeclContext(Kind))
1850     if (Error Err = ImportDeclContext(From, /*ForceImport=*/true))
1851       return Err;
1852 
1853   To->completeDefinition();
1854   return Error::success();
1855 }
1856 
1857 Error ASTNodeImporter::ImportInitializer(VarDecl *From, VarDecl *To) {
1858   if (To->getAnyInitializer())
1859     return Error::success();
1860 
1861   Expr *FromInit = From->getInit();
1862   if (!FromInit)
1863     return Error::success();
1864 
1865   ExpectedExpr ToInitOrErr = import(FromInit);
1866   if (!ToInitOrErr)
1867     return ToInitOrErr.takeError();
1868 
1869   To->setInit(*ToInitOrErr);
1870   if (From->isInitKnownICE()) {
1871     EvaluatedStmt *Eval = To->ensureEvaluatedStmt();
1872     Eval->CheckedICE = true;
1873     Eval->IsICE = From->isInitICE();
1874   }
1875 
1876   // FIXME: Other bits to merge?
1877   return Error::success();
1878 }
1879 
1880 Error ASTNodeImporter::ImportDefinition(
1881     EnumDecl *From, EnumDecl *To, ImportDefinitionKind Kind) {
1882   if (To->getDefinition() || To->isBeingDefined()) {
1883     if (Kind == IDK_Everything)
1884       return ImportDeclContext(From, /*ForceImport=*/true);
1885     return Error::success();
1886   }
1887 
1888   To->startDefinition();
1889 
1890   if (Error Err = setTypedefNameForAnonDecl(From, To, Importer))
1891     return Err;
1892 
1893   ExpectedType ToTypeOrErr =
1894       import(Importer.getFromContext().getTypeDeclType(From));
1895   if (!ToTypeOrErr)
1896     return ToTypeOrErr.takeError();
1897 
1898   ExpectedType ToPromotionTypeOrErr = import(From->getPromotionType());
1899   if (!ToPromotionTypeOrErr)
1900     return ToPromotionTypeOrErr.takeError();
1901 
1902   if (shouldForceImportDeclContext(Kind))
1903     if (Error Err = ImportDeclContext(From, /*ForceImport=*/true))
1904       return Err;
1905 
1906   // FIXME: we might need to merge the number of positive or negative bits
1907   // if the enumerator lists don't match.
1908   To->completeDefinition(*ToTypeOrErr, *ToPromotionTypeOrErr,
1909                          From->getNumPositiveBits(),
1910                          From->getNumNegativeBits());
1911   return Error::success();
1912 }
1913 
1914 // FIXME: Remove this, use `import` instead.
1915 Expected<TemplateParameterList *> ASTNodeImporter::ImportTemplateParameterList(
1916     TemplateParameterList *Params) {
1917   SmallVector<NamedDecl *, 4> ToParams(Params->size());
1918   if (Error Err = ImportContainerChecked(*Params, ToParams))
1919     return std::move(Err);
1920 
1921   Expr *ToRequiresClause;
1922   if (Expr *const R = Params->getRequiresClause()) {
1923     if (Error Err = importInto(ToRequiresClause, R))
1924       return std::move(Err);
1925   } else {
1926     ToRequiresClause = nullptr;
1927   }
1928 
1929   auto ToTemplateLocOrErr = import(Params->getTemplateLoc());
1930   if (!ToTemplateLocOrErr)
1931     return ToTemplateLocOrErr.takeError();
1932   auto ToLAngleLocOrErr = import(Params->getLAngleLoc());
1933   if (!ToLAngleLocOrErr)
1934     return ToLAngleLocOrErr.takeError();
1935   auto ToRAngleLocOrErr = import(Params->getRAngleLoc());
1936   if (!ToRAngleLocOrErr)
1937     return ToRAngleLocOrErr.takeError();
1938 
1939   return TemplateParameterList::Create(
1940       Importer.getToContext(),
1941       *ToTemplateLocOrErr,
1942       *ToLAngleLocOrErr,
1943       ToParams,
1944       *ToRAngleLocOrErr,
1945       ToRequiresClause);
1946 }
1947 
1948 Error ASTNodeImporter::ImportTemplateArguments(
1949     const TemplateArgument *FromArgs, unsigned NumFromArgs,
1950     SmallVectorImpl<TemplateArgument> &ToArgs) {
1951   for (unsigned I = 0; I != NumFromArgs; ++I) {
1952     if (auto ToOrErr = import(FromArgs[I]))
1953       ToArgs.push_back(*ToOrErr);
1954     else
1955       return ToOrErr.takeError();
1956   }
1957 
1958   return Error::success();
1959 }
1960 
1961 // FIXME: Do not forget to remove this and use only 'import'.
1962 Expected<TemplateArgument>
1963 ASTNodeImporter::ImportTemplateArgument(const TemplateArgument &From) {
1964   return import(From);
1965 }
1966 
1967 template <typename InContainerTy>
1968 Error ASTNodeImporter::ImportTemplateArgumentListInfo(
1969     const InContainerTy &Container, TemplateArgumentListInfo &ToTAInfo) {
1970   for (const auto &FromLoc : Container) {
1971     if (auto ToLocOrErr = import(FromLoc))
1972       ToTAInfo.addArgument(*ToLocOrErr);
1973     else
1974       return ToLocOrErr.takeError();
1975   }
1976   return Error::success();
1977 }
1978 
1979 static StructuralEquivalenceKind
1980 getStructuralEquivalenceKind(const ASTImporter &Importer) {
1981   return Importer.isMinimalImport() ? StructuralEquivalenceKind::Minimal
1982                                     : StructuralEquivalenceKind::Default;
1983 }
1984 
1985 bool ASTNodeImporter::IsStructuralMatch(Decl *From, Decl *To, bool Complain) {
1986   StructuralEquivalenceContext Ctx(
1987       Importer.getFromContext(), Importer.getToContext(),
1988       Importer.getNonEquivalentDecls(), getStructuralEquivalenceKind(Importer),
1989       false, Complain);
1990   return Ctx.IsEquivalent(From, To);
1991 }
1992 
1993 bool ASTNodeImporter::IsStructuralMatch(RecordDecl *FromRecord,
1994                                         RecordDecl *ToRecord, bool Complain) {
1995   // Eliminate a potential failure point where we attempt to re-import
1996   // something we're trying to import while completing ToRecord.
1997   Decl *ToOrigin = Importer.GetOriginalDecl(ToRecord);
1998   if (ToOrigin) {
1999     auto *ToOriginRecord = dyn_cast<RecordDecl>(ToOrigin);
2000     if (ToOriginRecord)
2001       ToRecord = ToOriginRecord;
2002   }
2003 
2004   StructuralEquivalenceContext Ctx(Importer.getFromContext(),
2005                                    ToRecord->getASTContext(),
2006                                    Importer.getNonEquivalentDecls(),
2007                                    getStructuralEquivalenceKind(Importer),
2008                                    false, Complain);
2009   return Ctx.IsEquivalent(FromRecord, ToRecord);
2010 }
2011 
2012 bool ASTNodeImporter::IsStructuralMatch(VarDecl *FromVar, VarDecl *ToVar,
2013                                         bool Complain) {
2014   StructuralEquivalenceContext Ctx(
2015       Importer.getFromContext(), Importer.getToContext(),
2016       Importer.getNonEquivalentDecls(), getStructuralEquivalenceKind(Importer),
2017       false, Complain);
2018   return Ctx.IsEquivalent(FromVar, ToVar);
2019 }
2020 
2021 bool ASTNodeImporter::IsStructuralMatch(EnumDecl *FromEnum, EnumDecl *ToEnum) {
2022   StructuralEquivalenceContext Ctx(
2023       Importer.getFromContext(), Importer.getToContext(),
2024       Importer.getNonEquivalentDecls(), getStructuralEquivalenceKind(Importer));
2025   return Ctx.IsEquivalent(FromEnum, ToEnum);
2026 }
2027 
2028 bool ASTNodeImporter::IsStructuralMatch(FunctionTemplateDecl *From,
2029                                         FunctionTemplateDecl *To) {
2030   StructuralEquivalenceContext Ctx(
2031       Importer.getFromContext(), Importer.getToContext(),
2032       Importer.getNonEquivalentDecls(), getStructuralEquivalenceKind(Importer),
2033       false, false);
2034   return Ctx.IsEquivalent(From, To);
2035 }
2036 
2037 bool ASTNodeImporter::IsStructuralMatch(FunctionDecl *From, FunctionDecl *To) {
2038   StructuralEquivalenceContext Ctx(
2039       Importer.getFromContext(), Importer.getToContext(),
2040       Importer.getNonEquivalentDecls(), getStructuralEquivalenceKind(Importer),
2041       false, false);
2042   return Ctx.IsEquivalent(From, To);
2043 }
2044 
2045 bool ASTNodeImporter::IsStructuralMatch(EnumConstantDecl *FromEC,
2046                                         EnumConstantDecl *ToEC) {
2047   const llvm::APSInt &FromVal = FromEC->getInitVal();
2048   const llvm::APSInt &ToVal = ToEC->getInitVal();
2049 
2050   return FromVal.isSigned() == ToVal.isSigned() &&
2051          FromVal.getBitWidth() == ToVal.getBitWidth() &&
2052          FromVal == ToVal;
2053 }
2054 
2055 bool ASTNodeImporter::IsStructuralMatch(ClassTemplateDecl *From,
2056                                         ClassTemplateDecl *To) {
2057   StructuralEquivalenceContext Ctx(Importer.getFromContext(),
2058                                    Importer.getToContext(),
2059                                    Importer.getNonEquivalentDecls(),
2060                                    getStructuralEquivalenceKind(Importer));
2061   return Ctx.IsEquivalent(From, To);
2062 }
2063 
2064 bool ASTNodeImporter::IsStructuralMatch(VarTemplateDecl *From,
2065                                         VarTemplateDecl *To) {
2066   StructuralEquivalenceContext Ctx(Importer.getFromContext(),
2067                                    Importer.getToContext(),
2068                                    Importer.getNonEquivalentDecls(),
2069                                    getStructuralEquivalenceKind(Importer));
2070   return Ctx.IsEquivalent(From, To);
2071 }
2072 
2073 ExpectedDecl ASTNodeImporter::VisitDecl(Decl *D) {
2074   Importer.FromDiag(D->getLocation(), diag::err_unsupported_ast_node)
2075     << D->getDeclKindName();
2076   return make_error<ImportError>(ImportError::UnsupportedConstruct);
2077 }
2078 
2079 ExpectedDecl ASTNodeImporter::VisitImportDecl(ImportDecl *D) {
2080   Importer.FromDiag(D->getLocation(), diag::err_unsupported_ast_node)
2081       << D->getDeclKindName();
2082   return make_error<ImportError>(ImportError::UnsupportedConstruct);
2083 }
2084 
2085 ExpectedDecl ASTNodeImporter::VisitEmptyDecl(EmptyDecl *D) {
2086   // Import the context of this declaration.
2087   DeclContext *DC, *LexicalDC;
2088   if (Error Err = ImportDeclContext(D, DC, LexicalDC))
2089     return std::move(Err);
2090 
2091   // Import the location of this declaration.
2092   ExpectedSLoc LocOrErr = import(D->getLocation());
2093   if (!LocOrErr)
2094     return LocOrErr.takeError();
2095 
2096   EmptyDecl *ToD;
2097   if (GetImportedOrCreateDecl(ToD, D, Importer.getToContext(), DC, *LocOrErr))
2098     return ToD;
2099 
2100   ToD->setLexicalDeclContext(LexicalDC);
2101   LexicalDC->addDeclInternal(ToD);
2102   return ToD;
2103 }
2104 
2105 ExpectedDecl ASTNodeImporter::VisitTranslationUnitDecl(TranslationUnitDecl *D) {
2106   TranslationUnitDecl *ToD =
2107     Importer.getToContext().getTranslationUnitDecl();
2108 
2109   Importer.MapImported(D, ToD);
2110 
2111   return ToD;
2112 }
2113 
2114 ExpectedDecl ASTNodeImporter::VisitAccessSpecDecl(AccessSpecDecl *D) {
2115   ExpectedSLoc LocOrErr = import(D->getLocation());
2116   if (!LocOrErr)
2117     return LocOrErr.takeError();
2118   auto ColonLocOrErr = import(D->getColonLoc());
2119   if (!ColonLocOrErr)
2120     return ColonLocOrErr.takeError();
2121 
2122   // Import the context of this declaration.
2123   auto DCOrErr = Importer.ImportContext(D->getDeclContext());
2124   if (!DCOrErr)
2125     return DCOrErr.takeError();
2126   DeclContext *DC = *DCOrErr;
2127 
2128   AccessSpecDecl *ToD;
2129   if (GetImportedOrCreateDecl(ToD, D, Importer.getToContext(), D->getAccess(),
2130                               DC, *LocOrErr, *ColonLocOrErr))
2131     return ToD;
2132 
2133   // Lexical DeclContext and Semantic DeclContext
2134   // is always the same for the accessSpec.
2135   ToD->setLexicalDeclContext(DC);
2136   DC->addDeclInternal(ToD);
2137 
2138   return ToD;
2139 }
2140 
2141 ExpectedDecl ASTNodeImporter::VisitStaticAssertDecl(StaticAssertDecl *D) {
2142   auto DCOrErr = Importer.ImportContext(D->getDeclContext());
2143   if (!DCOrErr)
2144     return DCOrErr.takeError();
2145   DeclContext *DC = *DCOrErr;
2146   DeclContext *LexicalDC = DC;
2147 
2148   SourceLocation ToLocation, ToRParenLoc;
2149   Expr *ToAssertExpr;
2150   StringLiteral *ToMessage;
2151   if (auto Imp = importSeq(
2152       D->getLocation(), D->getAssertExpr(), D->getMessage(), D->getRParenLoc()))
2153     std::tie(ToLocation, ToAssertExpr, ToMessage, ToRParenLoc) = *Imp;
2154   else
2155     return Imp.takeError();
2156 
2157   StaticAssertDecl *ToD;
2158   if (GetImportedOrCreateDecl(
2159       ToD, D, Importer.getToContext(), DC, ToLocation, ToAssertExpr, ToMessage,
2160       ToRParenLoc, D->isFailed()))
2161     return ToD;
2162 
2163   ToD->setLexicalDeclContext(LexicalDC);
2164   LexicalDC->addDeclInternal(ToD);
2165   return ToD;
2166 }
2167 
2168 ExpectedDecl ASTNodeImporter::VisitNamespaceDecl(NamespaceDecl *D) {
2169   // Import the major distinguishing characteristics of this namespace.
2170   DeclContext *DC, *LexicalDC;
2171   DeclarationName Name;
2172   SourceLocation Loc;
2173   NamedDecl *ToD;
2174   if (Error Err = ImportDeclParts(D, DC, LexicalDC, Name, ToD, Loc))
2175     return std::move(Err);
2176   if (ToD)
2177     return ToD;
2178 
2179   NamespaceDecl *MergeWithNamespace = nullptr;
2180   if (!Name) {
2181     // This is an anonymous namespace. Adopt an existing anonymous
2182     // namespace if we can.
2183     // FIXME: Not testable.
2184     if (auto *TU = dyn_cast<TranslationUnitDecl>(DC))
2185       MergeWithNamespace = TU->getAnonymousNamespace();
2186     else
2187       MergeWithNamespace = cast<NamespaceDecl>(DC)->getAnonymousNamespace();
2188   } else {
2189     SmallVector<NamedDecl *, 4> ConflictingDecls;
2190     SmallVector<NamedDecl *, 2> FoundDecls;
2191     DC->getRedeclContext()->localUncachedLookup(Name, FoundDecls);
2192     for (auto *FoundDecl : FoundDecls) {
2193       if (!FoundDecl->isInIdentifierNamespace(Decl::IDNS_Namespace))
2194         continue;
2195 
2196       if (auto *FoundNS = dyn_cast<NamespaceDecl>(FoundDecl)) {
2197         MergeWithNamespace = FoundNS;
2198         ConflictingDecls.clear();
2199         break;
2200       }
2201 
2202       ConflictingDecls.push_back(FoundDecl);
2203     }
2204 
2205     if (!ConflictingDecls.empty()) {
2206       Name = Importer.HandleNameConflict(Name, DC, Decl::IDNS_Namespace,
2207                                          ConflictingDecls.data(),
2208                                          ConflictingDecls.size());
2209       if (!Name)
2210         return make_error<ImportError>(ImportError::NameConflict);
2211     }
2212   }
2213 
2214   ExpectedSLoc BeginLocOrErr = import(D->getBeginLoc());
2215   if (!BeginLocOrErr)
2216     return BeginLocOrErr.takeError();
2217 
2218   // Create the "to" namespace, if needed.
2219   NamespaceDecl *ToNamespace = MergeWithNamespace;
2220   if (!ToNamespace) {
2221     if (GetImportedOrCreateDecl(
2222             ToNamespace, D, Importer.getToContext(), DC, D->isInline(),
2223             *BeginLocOrErr, Loc, Name.getAsIdentifierInfo(),
2224             /*PrevDecl=*/nullptr))
2225       return ToNamespace;
2226     ToNamespace->setLexicalDeclContext(LexicalDC);
2227     LexicalDC->addDeclInternal(ToNamespace);
2228 
2229     // If this is an anonymous namespace, register it as the anonymous
2230     // namespace within its context.
2231     if (!Name) {
2232       if (auto *TU = dyn_cast<TranslationUnitDecl>(DC))
2233         TU->setAnonymousNamespace(ToNamespace);
2234       else
2235         cast<NamespaceDecl>(DC)->setAnonymousNamespace(ToNamespace);
2236     }
2237   }
2238   Importer.MapImported(D, ToNamespace);
2239 
2240   if (Error Err = ImportDeclContext(D))
2241     return std::move(Err);
2242 
2243   return ToNamespace;
2244 }
2245 
2246 ExpectedDecl ASTNodeImporter::VisitNamespaceAliasDecl(NamespaceAliasDecl *D) {
2247   // Import the major distinguishing characteristics of this namespace.
2248   DeclContext *DC, *LexicalDC;
2249   DeclarationName Name;
2250   SourceLocation Loc;
2251   NamedDecl *LookupD;
2252   if (Error Err = ImportDeclParts(D, DC, LexicalDC, Name, LookupD, Loc))
2253     return std::move(Err);
2254   if (LookupD)
2255     return LookupD;
2256 
2257   // NOTE: No conflict resolution is done for namespace aliases now.
2258 
2259   SourceLocation ToNamespaceLoc, ToAliasLoc, ToTargetNameLoc;
2260   NestedNameSpecifierLoc ToQualifierLoc;
2261   NamespaceDecl *ToNamespace;
2262   if (auto Imp = importSeq(
2263       D->getNamespaceLoc(), D->getAliasLoc(), D->getQualifierLoc(),
2264       D->getTargetNameLoc(), D->getNamespace()))
2265     std::tie(
2266         ToNamespaceLoc, ToAliasLoc, ToQualifierLoc, ToTargetNameLoc,
2267         ToNamespace) = *Imp;
2268   else
2269     return Imp.takeError();
2270   IdentifierInfo *ToIdentifier = Importer.Import(D->getIdentifier());
2271 
2272   NamespaceAliasDecl *ToD;
2273   if (GetImportedOrCreateDecl(
2274       ToD, D, Importer.getToContext(), DC, ToNamespaceLoc, ToAliasLoc,
2275       ToIdentifier, ToQualifierLoc, ToTargetNameLoc, ToNamespace))
2276     return ToD;
2277 
2278   ToD->setLexicalDeclContext(LexicalDC);
2279   LexicalDC->addDeclInternal(ToD);
2280 
2281   return ToD;
2282 }
2283 
2284 ExpectedDecl
2285 ASTNodeImporter::VisitTypedefNameDecl(TypedefNameDecl *D, bool IsAlias) {
2286   // Import the major distinguishing characteristics of this typedef.
2287   DeclContext *DC, *LexicalDC;
2288   DeclarationName Name;
2289   SourceLocation Loc;
2290   NamedDecl *ToD;
2291   if (Error Err = ImportDeclParts(D, DC, LexicalDC, Name, ToD, Loc))
2292     return std::move(Err);
2293   if (ToD)
2294     return ToD;
2295 
2296   // If this typedef is not in block scope, determine whether we've
2297   // seen a typedef with the same name (that we can merge with) or any
2298   // other entity by that name (which name lookup could conflict with).
2299   if (!DC->isFunctionOrMethod()) {
2300     SmallVector<NamedDecl *, 4> ConflictingDecls;
2301     unsigned IDNS = Decl::IDNS_Ordinary;
2302     SmallVector<NamedDecl *, 2> FoundDecls;
2303     DC->getRedeclContext()->localUncachedLookup(Name, FoundDecls);
2304     for (auto *FoundDecl : FoundDecls) {
2305       if (!FoundDecl->isInIdentifierNamespace(IDNS))
2306         continue;
2307       if (auto *FoundTypedef = dyn_cast<TypedefNameDecl>(FoundDecl)) {
2308         if (Importer.IsStructurallyEquivalent(
2309                 D->getUnderlyingType(), FoundTypedef->getUnderlyingType()))
2310             return Importer.MapImported(D, FoundTypedef);
2311       }
2312 
2313       ConflictingDecls.push_back(FoundDecl);
2314     }
2315 
2316     if (!ConflictingDecls.empty()) {
2317       Name = Importer.HandleNameConflict(Name, DC, IDNS,
2318                                          ConflictingDecls.data(),
2319                                          ConflictingDecls.size());
2320       if (!Name)
2321         return make_error<ImportError>(ImportError::NameConflict);
2322     }
2323   }
2324 
2325   QualType ToUnderlyingType;
2326   TypeSourceInfo *ToTypeSourceInfo;
2327   SourceLocation ToBeginLoc;
2328   if (auto Imp = importSeq(
2329       D->getUnderlyingType(), D->getTypeSourceInfo(), D->getBeginLoc()))
2330     std::tie(ToUnderlyingType, ToTypeSourceInfo, ToBeginLoc) = *Imp;
2331   else
2332     return Imp.takeError();
2333 
2334   // Create the new typedef node.
2335   // FIXME: ToUnderlyingType is not used.
2336   TypedefNameDecl *ToTypedef;
2337   if (IsAlias) {
2338     if (GetImportedOrCreateDecl<TypeAliasDecl>(
2339         ToTypedef, D, Importer.getToContext(), DC, ToBeginLoc, Loc,
2340         Name.getAsIdentifierInfo(), ToTypeSourceInfo))
2341       return ToTypedef;
2342   } else if (GetImportedOrCreateDecl<TypedefDecl>(
2343       ToTypedef, D, Importer.getToContext(), DC, ToBeginLoc, Loc,
2344       Name.getAsIdentifierInfo(), ToTypeSourceInfo))
2345     return ToTypedef;
2346 
2347   ToTypedef->setAccess(D->getAccess());
2348   ToTypedef->setLexicalDeclContext(LexicalDC);
2349 
2350   // Templated declarations should not appear in DeclContext.
2351   TypeAliasDecl *FromAlias = IsAlias ? cast<TypeAliasDecl>(D) : nullptr;
2352   if (!FromAlias || !FromAlias->getDescribedAliasTemplate())
2353     LexicalDC->addDeclInternal(ToTypedef);
2354 
2355   return ToTypedef;
2356 }
2357 
2358 ExpectedDecl ASTNodeImporter::VisitTypedefDecl(TypedefDecl *D) {
2359   return VisitTypedefNameDecl(D, /*IsAlias=*/false);
2360 }
2361 
2362 ExpectedDecl ASTNodeImporter::VisitTypeAliasDecl(TypeAliasDecl *D) {
2363   return VisitTypedefNameDecl(D, /*IsAlias=*/true);
2364 }
2365 
2366 ExpectedDecl
2367 ASTNodeImporter::VisitTypeAliasTemplateDecl(TypeAliasTemplateDecl *D) {
2368   // Import the major distinguishing characteristics of this typedef.
2369   DeclContext *DC, *LexicalDC;
2370   DeclarationName Name;
2371   SourceLocation Loc;
2372   NamedDecl *FoundD;
2373   if (Error Err = ImportDeclParts(D, DC, LexicalDC, Name, FoundD, Loc))
2374     return std::move(Err);
2375   if (FoundD)
2376     return FoundD;
2377 
2378   // If this typedef is not in block scope, determine whether we've
2379   // seen a typedef with the same name (that we can merge with) or any
2380   // other entity by that name (which name lookup could conflict with).
2381   if (!DC->isFunctionOrMethod()) {
2382     SmallVector<NamedDecl *, 4> ConflictingDecls;
2383     unsigned IDNS = Decl::IDNS_Ordinary;
2384     SmallVector<NamedDecl *, 2> FoundDecls;
2385     DC->getRedeclContext()->localUncachedLookup(Name, FoundDecls);
2386     for (auto *FoundDecl : FoundDecls) {
2387       if (!FoundDecl->isInIdentifierNamespace(IDNS))
2388         continue;
2389       if (auto *FoundAlias = dyn_cast<TypeAliasTemplateDecl>(FoundDecl))
2390         return Importer.MapImported(D, FoundAlias);
2391       ConflictingDecls.push_back(FoundDecl);
2392     }
2393 
2394     if (!ConflictingDecls.empty()) {
2395       Name = Importer.HandleNameConflict(Name, DC, IDNS,
2396                                          ConflictingDecls.data(),
2397                                          ConflictingDecls.size());
2398       if (!Name)
2399         return make_error<ImportError>(ImportError::NameConflict);
2400     }
2401   }
2402 
2403   TemplateParameterList *ToTemplateParameters;
2404   TypeAliasDecl *ToTemplatedDecl;
2405   if (auto Imp = importSeq(D->getTemplateParameters(), D->getTemplatedDecl()))
2406     std::tie(ToTemplateParameters, ToTemplatedDecl) = *Imp;
2407   else
2408     return Imp.takeError();
2409 
2410   TypeAliasTemplateDecl *ToAlias;
2411   if (GetImportedOrCreateDecl(ToAlias, D, Importer.getToContext(), DC, Loc,
2412                               Name, ToTemplateParameters, ToTemplatedDecl))
2413     return ToAlias;
2414 
2415   ToTemplatedDecl->setDescribedAliasTemplate(ToAlias);
2416 
2417   ToAlias->setAccess(D->getAccess());
2418   ToAlias->setLexicalDeclContext(LexicalDC);
2419   LexicalDC->addDeclInternal(ToAlias);
2420   return ToAlias;
2421 }
2422 
2423 ExpectedDecl ASTNodeImporter::VisitLabelDecl(LabelDecl *D) {
2424   // Import the major distinguishing characteristics of this label.
2425   DeclContext *DC, *LexicalDC;
2426   DeclarationName Name;
2427   SourceLocation Loc;
2428   NamedDecl *ToD;
2429   if (Error Err = ImportDeclParts(D, DC, LexicalDC, Name, ToD, Loc))
2430     return std::move(Err);
2431   if (ToD)
2432     return ToD;
2433 
2434   assert(LexicalDC->isFunctionOrMethod());
2435 
2436   LabelDecl *ToLabel;
2437   if (D->isGnuLocal()) {
2438     ExpectedSLoc BeginLocOrErr = import(D->getBeginLoc());
2439     if (!BeginLocOrErr)
2440       return BeginLocOrErr.takeError();
2441     if (GetImportedOrCreateDecl(ToLabel, D, Importer.getToContext(), DC, Loc,
2442                                 Name.getAsIdentifierInfo(), *BeginLocOrErr))
2443       return ToLabel;
2444 
2445   } else {
2446     if (GetImportedOrCreateDecl(ToLabel, D, Importer.getToContext(), DC, Loc,
2447                                 Name.getAsIdentifierInfo()))
2448       return ToLabel;
2449 
2450   }
2451 
2452   Expected<LabelStmt *> ToStmtOrErr = import(D->getStmt());
2453   if (!ToStmtOrErr)
2454     return ToStmtOrErr.takeError();
2455 
2456   ToLabel->setStmt(*ToStmtOrErr);
2457   ToLabel->setLexicalDeclContext(LexicalDC);
2458   LexicalDC->addDeclInternal(ToLabel);
2459   return ToLabel;
2460 }
2461 
2462 ExpectedDecl ASTNodeImporter::VisitEnumDecl(EnumDecl *D) {
2463   // Import the major distinguishing characteristics of this enum.
2464   DeclContext *DC, *LexicalDC;
2465   DeclarationName Name;
2466   SourceLocation Loc;
2467   NamedDecl *ToD;
2468   if (Error Err = ImportDeclParts(D, DC, LexicalDC, Name, ToD, Loc))
2469     return std::move(Err);
2470   if (ToD)
2471     return ToD;
2472 
2473   // Figure out what enum name we're looking for.
2474   unsigned IDNS = Decl::IDNS_Tag;
2475   DeclarationName SearchName = Name;
2476   if (!SearchName && D->getTypedefNameForAnonDecl()) {
2477     if (Error Err = importInto(
2478         SearchName, D->getTypedefNameForAnonDecl()->getDeclName()))
2479       return std::move(Err);
2480     IDNS = Decl::IDNS_Ordinary;
2481   } else if (Importer.getToContext().getLangOpts().CPlusPlus)
2482     IDNS |= Decl::IDNS_Ordinary;
2483 
2484   // We may already have an enum of the same name; try to find and match it.
2485   if (!DC->isFunctionOrMethod() && SearchName) {
2486     SmallVector<NamedDecl *, 4> ConflictingDecls;
2487     SmallVector<NamedDecl *, 2> FoundDecls;
2488     DC->getRedeclContext()->localUncachedLookup(SearchName, FoundDecls);
2489     for (auto *FoundDecl : FoundDecls) {
2490       if (!FoundDecl->isInIdentifierNamespace(IDNS))
2491         continue;
2492 
2493       if (auto *Typedef = dyn_cast<TypedefNameDecl>(FoundDecl)) {
2494         if (const auto *Tag = Typedef->getUnderlyingType()->getAs<TagType>())
2495           FoundDecl = Tag->getDecl();
2496       }
2497 
2498       if (auto *FoundEnum = dyn_cast<EnumDecl>(FoundDecl)) {
2499         if (IsStructuralMatch(D, FoundEnum))
2500           return Importer.MapImported(D, FoundEnum);
2501       }
2502 
2503       ConflictingDecls.push_back(FoundDecl);
2504     }
2505 
2506     if (!ConflictingDecls.empty()) {
2507       Name = Importer.HandleNameConflict(Name, DC, IDNS,
2508                                          ConflictingDecls.data(),
2509                                          ConflictingDecls.size());
2510       if (!Name)
2511         return make_error<ImportError>(ImportError::NameConflict);
2512     }
2513   }
2514 
2515   SourceLocation ToBeginLoc;
2516   NestedNameSpecifierLoc ToQualifierLoc;
2517   QualType ToIntegerType;
2518   if (auto Imp = importSeq(
2519       D->getBeginLoc(), D->getQualifierLoc(), D->getIntegerType()))
2520     std::tie(ToBeginLoc, ToQualifierLoc, ToIntegerType) = *Imp;
2521   else
2522     return Imp.takeError();
2523 
2524   // Create the enum declaration.
2525   EnumDecl *D2;
2526   if (GetImportedOrCreateDecl(
2527           D2, D, Importer.getToContext(), DC, ToBeginLoc,
2528           Loc, Name.getAsIdentifierInfo(), nullptr, D->isScoped(),
2529           D->isScopedUsingClassTag(), D->isFixed()))
2530     return D2;
2531 
2532   D2->setQualifierInfo(ToQualifierLoc);
2533   D2->setIntegerType(ToIntegerType);
2534   D2->setAccess(D->getAccess());
2535   D2->setLexicalDeclContext(LexicalDC);
2536   LexicalDC->addDeclInternal(D2);
2537 
2538   // Import the definition
2539   if (D->isCompleteDefinition())
2540     if (Error Err = ImportDefinition(D, D2))
2541       return std::move(Err);
2542 
2543   return D2;
2544 }
2545 
2546 ExpectedDecl ASTNodeImporter::VisitRecordDecl(RecordDecl *D) {
2547   bool IsFriendTemplate = false;
2548   if (auto *DCXX = dyn_cast<CXXRecordDecl>(D)) {
2549     IsFriendTemplate =
2550         DCXX->getDescribedClassTemplate() &&
2551         DCXX->getDescribedClassTemplate()->getFriendObjectKind() !=
2552             Decl::FOK_None;
2553   }
2554 
2555   // If this record has a definition in the translation unit we're coming from,
2556   // but this particular declaration is not that definition, import the
2557   // definition and map to that.
2558   TagDecl *Definition = D->getDefinition();
2559   if (Definition && Definition != D &&
2560       // Friend template declaration must be imported on its own.
2561       !IsFriendTemplate &&
2562       // In contrast to a normal CXXRecordDecl, the implicit
2563       // CXXRecordDecl of ClassTemplateSpecializationDecl is its redeclaration.
2564       // The definition of the implicit CXXRecordDecl in this case is the
2565       // ClassTemplateSpecializationDecl itself. Thus, we start with an extra
2566       // condition in order to be able to import the implict Decl.
2567       !D->isImplicit()) {
2568     ExpectedDecl ImportedDefOrErr = import(Definition);
2569     if (!ImportedDefOrErr)
2570       return ImportedDefOrErr.takeError();
2571 
2572     return Importer.MapImported(D, *ImportedDefOrErr);
2573   }
2574 
2575   // Import the major distinguishing characteristics of this record.
2576   DeclContext *DC, *LexicalDC;
2577   DeclarationName Name;
2578   SourceLocation Loc;
2579   NamedDecl *ToD;
2580   if (Error Err = ImportDeclParts(D, DC, LexicalDC, Name, ToD, Loc))
2581     return std::move(Err);
2582   if (ToD)
2583     return ToD;
2584 
2585   // Figure out what structure name we're looking for.
2586   unsigned IDNS = Decl::IDNS_Tag;
2587   DeclarationName SearchName = Name;
2588   if (!SearchName && D->getTypedefNameForAnonDecl()) {
2589     if (Error Err = importInto(
2590         SearchName, D->getTypedefNameForAnonDecl()->getDeclName()))
2591       return std::move(Err);
2592     IDNS = Decl::IDNS_Ordinary;
2593   } else if (Importer.getToContext().getLangOpts().CPlusPlus)
2594     IDNS |= Decl::IDNS_Ordinary;
2595 
2596   // We may already have a record of the same name; try to find and match it.
2597   RecordDecl *AdoptDecl = nullptr;
2598   RecordDecl *PrevDecl = nullptr;
2599   if (!DC->isFunctionOrMethod()) {
2600     SmallVector<NamedDecl *, 4> ConflictingDecls;
2601     SmallVector<NamedDecl *, 2> FoundDecls;
2602     DC->getRedeclContext()->localUncachedLookup(SearchName, FoundDecls);
2603 
2604     if (!FoundDecls.empty()) {
2605       // We're going to have to compare D against potentially conflicting Decls, so complete it.
2606       if (D->hasExternalLexicalStorage() && !D->isCompleteDefinition())
2607         D->getASTContext().getExternalSource()->CompleteType(D);
2608     }
2609 
2610     for (auto *FoundDecl : FoundDecls) {
2611       if (!FoundDecl->isInIdentifierNamespace(IDNS))
2612         continue;
2613 
2614       Decl *Found = FoundDecl;
2615       if (auto *Typedef = dyn_cast<TypedefNameDecl>(Found)) {
2616         if (const auto *Tag = Typedef->getUnderlyingType()->getAs<TagType>())
2617           Found = Tag->getDecl();
2618       }
2619 
2620       if (D->getDescribedTemplate()) {
2621         if (auto *Template = dyn_cast<ClassTemplateDecl>(Found)) {
2622           Found = Template->getTemplatedDecl();
2623         } else {
2624           ConflictingDecls.push_back(FoundDecl);
2625           continue;
2626         }
2627       }
2628 
2629       if (auto *FoundRecord = dyn_cast<RecordDecl>(Found)) {
2630         if (!SearchName) {
2631           if (!IsStructuralMatch(D, FoundRecord, false))
2632             continue;
2633         } else {
2634           if (!IsStructuralMatch(D, FoundRecord)) {
2635             ConflictingDecls.push_back(FoundDecl);
2636             continue;
2637           }
2638         }
2639 
2640         PrevDecl = FoundRecord;
2641 
2642         if (RecordDecl *FoundDef = FoundRecord->getDefinition()) {
2643           if ((SearchName && !D->isCompleteDefinition() && !IsFriendTemplate)
2644               || (D->isCompleteDefinition() &&
2645                   D->isAnonymousStructOrUnion()
2646                     == FoundDef->isAnonymousStructOrUnion())) {
2647             // The record types structurally match, or the "from" translation
2648             // unit only had a forward declaration anyway; call it the same
2649             // function.
2650             // FIXME: Structural equivalence check should check for same
2651             // user-defined methods.
2652             Importer.MapImported(D, FoundDef);
2653             if (const auto *DCXX = dyn_cast<CXXRecordDecl>(D)) {
2654               auto *FoundCXX = dyn_cast<CXXRecordDecl>(FoundDef);
2655               assert(FoundCXX && "Record type mismatch");
2656 
2657               if (D->isCompleteDefinition() && !Importer.isMinimalImport())
2658                 // FoundDef may not have every implicit method that D has
2659                 // because implicit methods are created only if they are used.
2660                 if (Error Err = ImportImplicitMethods(DCXX, FoundCXX))
2661                   return std::move(Err);
2662             }
2663             return FoundDef;
2664           }
2665           if (IsFriendTemplate)
2666             continue;
2667         } else if (!D->isCompleteDefinition()) {
2668           // We have a forward declaration of this type, so adopt that forward
2669           // declaration rather than building a new one.
2670 
2671           // If one or both can be completed from external storage then try one
2672           // last time to complete and compare them before doing this.
2673 
2674           if (FoundRecord->hasExternalLexicalStorage() &&
2675               !FoundRecord->isCompleteDefinition())
2676             FoundRecord->getASTContext().getExternalSource()->CompleteType(FoundRecord);
2677           if (D->hasExternalLexicalStorage())
2678             D->getASTContext().getExternalSource()->CompleteType(D);
2679 
2680           if (FoundRecord->isCompleteDefinition() &&
2681               D->isCompleteDefinition() &&
2682               !IsStructuralMatch(D, FoundRecord)) {
2683             ConflictingDecls.push_back(FoundDecl);
2684             continue;
2685           }
2686 
2687           AdoptDecl = FoundRecord;
2688           continue;
2689         }
2690 
2691         continue;
2692       } else if (isa<ValueDecl>(Found))
2693         continue;
2694 
2695       ConflictingDecls.push_back(FoundDecl);
2696     }
2697 
2698     if (!ConflictingDecls.empty() && SearchName) {
2699       Name = Importer.HandleNameConflict(Name, DC, IDNS,
2700                                          ConflictingDecls.data(),
2701                                          ConflictingDecls.size());
2702       if (!Name)
2703         return make_error<ImportError>(ImportError::NameConflict);
2704     }
2705   }
2706 
2707   ExpectedSLoc BeginLocOrErr = import(D->getBeginLoc());
2708   if (!BeginLocOrErr)
2709     return BeginLocOrErr.takeError();
2710 
2711   // Create the record declaration.
2712   RecordDecl *D2 = AdoptDecl;
2713   if (!D2) {
2714     CXXRecordDecl *D2CXX = nullptr;
2715     if (auto *DCXX = dyn_cast<CXXRecordDecl>(D)) {
2716       if (DCXX->isLambda()) {
2717         auto TInfoOrErr = import(DCXX->getLambdaTypeInfo());
2718         if (!TInfoOrErr)
2719           return TInfoOrErr.takeError();
2720         if (GetImportedOrCreateSpecialDecl(
2721                 D2CXX, CXXRecordDecl::CreateLambda, D, Importer.getToContext(),
2722                 DC, *TInfoOrErr, Loc, DCXX->isDependentLambda(),
2723                 DCXX->isGenericLambda(), DCXX->getLambdaCaptureDefault()))
2724           return D2CXX;
2725         ExpectedDecl CDeclOrErr = import(DCXX->getLambdaContextDecl());
2726         if (!CDeclOrErr)
2727           return CDeclOrErr.takeError();
2728         D2CXX->setLambdaMangling(DCXX->getLambdaManglingNumber(), *CDeclOrErr);
2729       } else if (DCXX->isInjectedClassName()) {
2730         // We have to be careful to do a similar dance to the one in
2731         // Sema::ActOnStartCXXMemberDeclarations
2732         CXXRecordDecl *const PrevDecl = nullptr;
2733         const bool DelayTypeCreation = true;
2734         if (GetImportedOrCreateDecl(D2CXX, D, Importer.getToContext(),
2735                                     D->getTagKind(), DC, *BeginLocOrErr, Loc,
2736                                     Name.getAsIdentifierInfo(), PrevDecl,
2737                                     DelayTypeCreation))
2738           return D2CXX;
2739         Importer.getToContext().getTypeDeclType(
2740             D2CXX, dyn_cast<CXXRecordDecl>(DC));
2741       } else {
2742         if (GetImportedOrCreateDecl(D2CXX, D, Importer.getToContext(),
2743                                     D->getTagKind(), DC, *BeginLocOrErr, Loc,
2744                                     Name.getAsIdentifierInfo(),
2745                                     cast_or_null<CXXRecordDecl>(PrevDecl)))
2746           return D2CXX;
2747       }
2748 
2749       D2 = D2CXX;
2750       D2->setAccess(D->getAccess());
2751       D2->setLexicalDeclContext(LexicalDC);
2752       if (!DCXX->getDescribedClassTemplate() || DCXX->isImplicit())
2753         LexicalDC->addDeclInternal(D2);
2754 
2755       if (ClassTemplateDecl *FromDescribed =
2756           DCXX->getDescribedClassTemplate()) {
2757         ClassTemplateDecl *ToDescribed;
2758         if (Error Err = importInto(ToDescribed, FromDescribed))
2759           return std::move(Err);
2760         D2CXX->setDescribedClassTemplate(ToDescribed);
2761         if (!DCXX->isInjectedClassName() && !IsFriendTemplate) {
2762           // In a record describing a template the type should be an
2763           // InjectedClassNameType (see Sema::CheckClassTemplate). Update the
2764           // previously set type to the correct value here (ToDescribed is not
2765           // available at record create).
2766           // FIXME: The previous type is cleared but not removed from
2767           // ASTContext's internal storage.
2768           CXXRecordDecl *Injected = nullptr;
2769           for (NamedDecl *Found : D2CXX->noload_lookup(Name)) {
2770             auto *Record = dyn_cast<CXXRecordDecl>(Found);
2771             if (Record && Record->isInjectedClassName()) {
2772               Injected = Record;
2773               break;
2774             }
2775           }
2776           D2CXX->setTypeForDecl(nullptr);
2777           Importer.getToContext().getInjectedClassNameType(D2CXX,
2778               ToDescribed->getInjectedClassNameSpecialization());
2779           if (Injected) {
2780             Injected->setTypeForDecl(nullptr);
2781             Importer.getToContext().getTypeDeclType(Injected, D2CXX);
2782           }
2783         }
2784       } else if (MemberSpecializationInfo *MemberInfo =
2785                    DCXX->getMemberSpecializationInfo()) {
2786         TemplateSpecializationKind SK =
2787             MemberInfo->getTemplateSpecializationKind();
2788         CXXRecordDecl *FromInst = DCXX->getInstantiatedFromMemberClass();
2789 
2790         if (Expected<CXXRecordDecl *> ToInstOrErr = import(FromInst))
2791           D2CXX->setInstantiationOfMemberClass(*ToInstOrErr, SK);
2792         else
2793           return ToInstOrErr.takeError();
2794 
2795         if (ExpectedSLoc POIOrErr =
2796             import(MemberInfo->getPointOfInstantiation()))
2797           D2CXX->getMemberSpecializationInfo()->setPointOfInstantiation(
2798             *POIOrErr);
2799         else
2800           return POIOrErr.takeError();
2801       }
2802 
2803     } else {
2804       if (GetImportedOrCreateDecl(D2, D, Importer.getToContext(),
2805                                   D->getTagKind(), DC, *BeginLocOrErr, Loc,
2806                                   Name.getAsIdentifierInfo(), PrevDecl))
2807         return D2;
2808       D2->setLexicalDeclContext(LexicalDC);
2809       LexicalDC->addDeclInternal(D2);
2810     }
2811 
2812     if (auto QualifierLocOrErr = import(D->getQualifierLoc()))
2813       D2->setQualifierInfo(*QualifierLocOrErr);
2814     else
2815       return QualifierLocOrErr.takeError();
2816 
2817     if (D->isAnonymousStructOrUnion())
2818       D2->setAnonymousStructOrUnion(true);
2819   }
2820 
2821   Importer.MapImported(D, D2);
2822 
2823   if (D->isCompleteDefinition())
2824     if (Error Err = ImportDefinition(D, D2, IDK_Default))
2825       return std::move(Err);
2826 
2827   return D2;
2828 }
2829 
2830 ExpectedDecl ASTNodeImporter::VisitEnumConstantDecl(EnumConstantDecl *D) {
2831   // Import the major distinguishing characteristics of this enumerator.
2832   DeclContext *DC, *LexicalDC;
2833   DeclarationName Name;
2834   SourceLocation Loc;
2835   NamedDecl *ToD;
2836   if (Error Err = ImportDeclParts(D, DC, LexicalDC, Name, ToD, Loc))
2837     return std::move(Err);
2838   if (ToD)
2839     return ToD;
2840 
2841   // Determine whether there are any other declarations with the same name and
2842   // in the same context.
2843   if (!LexicalDC->isFunctionOrMethod()) {
2844     SmallVector<NamedDecl *, 4> ConflictingDecls;
2845     unsigned IDNS = Decl::IDNS_Ordinary;
2846     SmallVector<NamedDecl *, 2> FoundDecls;
2847     DC->getRedeclContext()->localUncachedLookup(Name, FoundDecls);
2848     for (auto *FoundDecl : FoundDecls) {
2849       if (!FoundDecl->isInIdentifierNamespace(IDNS))
2850         continue;
2851 
2852       if (auto *FoundEnumConstant = dyn_cast<EnumConstantDecl>(FoundDecl)) {
2853         if (IsStructuralMatch(D, FoundEnumConstant))
2854           return Importer.MapImported(D, FoundEnumConstant);
2855       }
2856 
2857       ConflictingDecls.push_back(FoundDecl);
2858     }
2859 
2860     if (!ConflictingDecls.empty()) {
2861       Name = Importer.HandleNameConflict(Name, DC, IDNS,
2862                                          ConflictingDecls.data(),
2863                                          ConflictingDecls.size());
2864       if (!Name)
2865         return make_error<ImportError>(ImportError::NameConflict);
2866     }
2867   }
2868 
2869   ExpectedType TypeOrErr = import(D->getType());
2870   if (!TypeOrErr)
2871     return TypeOrErr.takeError();
2872 
2873   ExpectedExpr InitOrErr = import(D->getInitExpr());
2874   if (!InitOrErr)
2875     return InitOrErr.takeError();
2876 
2877   EnumConstantDecl *ToEnumerator;
2878   if (GetImportedOrCreateDecl(
2879           ToEnumerator, D, Importer.getToContext(), cast<EnumDecl>(DC), Loc,
2880           Name.getAsIdentifierInfo(), *TypeOrErr, *InitOrErr, D->getInitVal()))
2881     return ToEnumerator;
2882 
2883   ToEnumerator->setAccess(D->getAccess());
2884   ToEnumerator->setLexicalDeclContext(LexicalDC);
2885   LexicalDC->addDeclInternal(ToEnumerator);
2886   return ToEnumerator;
2887 }
2888 
2889 Error ASTNodeImporter::ImportTemplateInformation(
2890     FunctionDecl *FromFD, FunctionDecl *ToFD) {
2891   switch (FromFD->getTemplatedKind()) {
2892   case FunctionDecl::TK_NonTemplate:
2893   case FunctionDecl::TK_FunctionTemplate:
2894     return Error::success();
2895 
2896   case FunctionDecl::TK_MemberSpecialization: {
2897     TemplateSpecializationKind TSK = FromFD->getTemplateSpecializationKind();
2898 
2899     if (Expected<FunctionDecl *> InstFDOrErr =
2900         import(FromFD->getInstantiatedFromMemberFunction()))
2901       ToFD->setInstantiationOfMemberFunction(*InstFDOrErr, TSK);
2902     else
2903       return InstFDOrErr.takeError();
2904 
2905     if (ExpectedSLoc POIOrErr = import(
2906         FromFD->getMemberSpecializationInfo()->getPointOfInstantiation()))
2907       ToFD->getMemberSpecializationInfo()->setPointOfInstantiation(*POIOrErr);
2908     else
2909       return POIOrErr.takeError();
2910 
2911     return Error::success();
2912   }
2913 
2914   case FunctionDecl::TK_FunctionTemplateSpecialization: {
2915     auto FunctionAndArgsOrErr =
2916         ImportFunctionTemplateWithTemplateArgsFromSpecialization(FromFD);
2917     if (!FunctionAndArgsOrErr)
2918       return FunctionAndArgsOrErr.takeError();
2919 
2920     TemplateArgumentList *ToTAList = TemplateArgumentList::CreateCopy(
2921           Importer.getToContext(), std::get<1>(*FunctionAndArgsOrErr));
2922 
2923     auto *FTSInfo = FromFD->getTemplateSpecializationInfo();
2924     TemplateArgumentListInfo ToTAInfo;
2925     const auto *FromTAArgsAsWritten = FTSInfo->TemplateArgumentsAsWritten;
2926     if (FromTAArgsAsWritten)
2927       if (Error Err = ImportTemplateArgumentListInfo(
2928           *FromTAArgsAsWritten, ToTAInfo))
2929         return Err;
2930 
2931     ExpectedSLoc POIOrErr = import(FTSInfo->getPointOfInstantiation());
2932     if (!POIOrErr)
2933       return POIOrErr.takeError();
2934 
2935     TemplateSpecializationKind TSK = FTSInfo->getTemplateSpecializationKind();
2936     ToFD->setFunctionTemplateSpecialization(
2937         std::get<0>(*FunctionAndArgsOrErr), ToTAList, /* InsertPos= */ nullptr,
2938         TSK, FromTAArgsAsWritten ? &ToTAInfo : nullptr, *POIOrErr);
2939     return Error::success();
2940   }
2941 
2942   case FunctionDecl::TK_DependentFunctionTemplateSpecialization: {
2943     auto *FromInfo = FromFD->getDependentSpecializationInfo();
2944     UnresolvedSet<8> TemplDecls;
2945     unsigned NumTemplates = FromInfo->getNumTemplates();
2946     for (unsigned I = 0; I < NumTemplates; I++) {
2947       if (Expected<FunctionTemplateDecl *> ToFTDOrErr =
2948           import(FromInfo->getTemplate(I)))
2949         TemplDecls.addDecl(*ToFTDOrErr);
2950       else
2951         return ToFTDOrErr.takeError();
2952     }
2953 
2954     // Import TemplateArgumentListInfo.
2955     TemplateArgumentListInfo ToTAInfo;
2956     if (Error Err = ImportTemplateArgumentListInfo(
2957         FromInfo->getLAngleLoc(), FromInfo->getRAngleLoc(),
2958         llvm::makeArrayRef(
2959             FromInfo->getTemplateArgs(), FromInfo->getNumTemplateArgs()),
2960         ToTAInfo))
2961       return Err;
2962 
2963     ToFD->setDependentTemplateSpecialization(Importer.getToContext(),
2964                                              TemplDecls, ToTAInfo);
2965     return Error::success();
2966   }
2967   }
2968   llvm_unreachable("All cases should be covered!");
2969 }
2970 
2971 Expected<FunctionDecl *>
2972 ASTNodeImporter::FindFunctionTemplateSpecialization(FunctionDecl *FromFD) {
2973   auto FunctionAndArgsOrErr =
2974       ImportFunctionTemplateWithTemplateArgsFromSpecialization(FromFD);
2975   if (!FunctionAndArgsOrErr)
2976     return FunctionAndArgsOrErr.takeError();
2977 
2978   FunctionTemplateDecl *Template;
2979   TemplateArgsTy ToTemplArgs;
2980   std::tie(Template, ToTemplArgs) = *FunctionAndArgsOrErr;
2981   void *InsertPos = nullptr;
2982   auto *FoundSpec = Template->findSpecialization(ToTemplArgs, InsertPos);
2983   return FoundSpec;
2984 }
2985 
2986 ExpectedDecl ASTNodeImporter::VisitFunctionDecl(FunctionDecl *D) {
2987 
2988   SmallVector<Decl *, 2> Redecls = getCanonicalForwardRedeclChain(D);
2989   auto RedeclIt = Redecls.begin();
2990   // Import the first part of the decl chain. I.e. import all previous
2991   // declarations starting from the canonical decl.
2992   for (; RedeclIt != Redecls.end() && *RedeclIt != D; ++RedeclIt) {
2993     ExpectedDecl ToRedeclOrErr = import(*RedeclIt);
2994     if (!ToRedeclOrErr)
2995       return ToRedeclOrErr.takeError();
2996   }
2997   assert(*RedeclIt == D);
2998 
2999   // Import the major distinguishing characteristics of this function.
3000   DeclContext *DC, *LexicalDC;
3001   DeclarationName Name;
3002   SourceLocation Loc;
3003   NamedDecl *ToD;
3004   if (Error Err = ImportDeclParts(D, DC, LexicalDC, Name, ToD, Loc))
3005     return std::move(Err);
3006   if (ToD)
3007     return ToD;
3008 
3009   const FunctionDecl *FoundByLookup = nullptr;
3010   FunctionTemplateDecl *FromFT = D->getDescribedFunctionTemplate();
3011 
3012   // If this is a function template specialization, then try to find the same
3013   // existing specialization in the "to" context. The localUncachedLookup
3014   // below will not find any specialization, but would find the primary
3015   // template; thus, we have to skip normal lookup in case of specializations.
3016   // FIXME handle member function templates (TK_MemberSpecialization) similarly?
3017   if (D->getTemplatedKind() ==
3018       FunctionDecl::TK_FunctionTemplateSpecialization) {
3019     auto FoundFunctionOrErr = FindFunctionTemplateSpecialization(D);
3020     if (!FoundFunctionOrErr)
3021       return FoundFunctionOrErr.takeError();
3022     if (FunctionDecl *FoundFunction = *FoundFunctionOrErr) {
3023       if (D->doesThisDeclarationHaveABody() && FoundFunction->hasBody())
3024         return Importer.MapImported(D, FoundFunction);
3025       FoundByLookup = FoundFunction;
3026     }
3027   }
3028   // Try to find a function in our own ("to") context with the same name, same
3029   // type, and in the same context as the function we're importing.
3030   else if (!LexicalDC->isFunctionOrMethod()) {
3031     SmallVector<NamedDecl *, 4> ConflictingDecls;
3032     unsigned IDNS = Decl::IDNS_Ordinary | Decl::IDNS_OrdinaryFriend;
3033     SmallVector<NamedDecl *, 2> FoundDecls;
3034     DC->getRedeclContext()->localUncachedLookup(Name, FoundDecls);
3035     for (auto *FoundDecl : FoundDecls) {
3036       if (!FoundDecl->isInIdentifierNamespace(IDNS))
3037         continue;
3038 
3039       // If template was found, look at the templated function.
3040       if (FromFT) {
3041         if (auto *Template = dyn_cast<FunctionTemplateDecl>(FoundDecl))
3042           FoundDecl = Template->getTemplatedDecl();
3043         else
3044           continue;
3045       }
3046 
3047       if (auto *FoundFunction = dyn_cast<FunctionDecl>(FoundDecl)) {
3048         if (FoundFunction->hasExternalFormalLinkage() &&
3049             D->hasExternalFormalLinkage()) {
3050           if (IsStructuralMatch(D, FoundFunction)) {
3051             const FunctionDecl *Definition = nullptr;
3052             if (D->doesThisDeclarationHaveABody() &&
3053                 FoundFunction->hasBody(Definition)) {
3054               return Importer.MapImported(
3055                   D, const_cast<FunctionDecl *>(Definition));
3056             }
3057             FoundByLookup = FoundFunction;
3058             break;
3059           }
3060 
3061           // FIXME: Check for overloading more carefully, e.g., by boosting
3062           // Sema::IsOverload out to the AST library.
3063 
3064           // Function overloading is okay in C++.
3065           if (Importer.getToContext().getLangOpts().CPlusPlus)
3066             continue;
3067 
3068           // Complain about inconsistent function types.
3069           Importer.ToDiag(Loc, diag::err_odr_function_type_inconsistent)
3070             << Name << D->getType() << FoundFunction->getType();
3071           Importer.ToDiag(FoundFunction->getLocation(),
3072                           diag::note_odr_value_here)
3073             << FoundFunction->getType();
3074         }
3075       }
3076 
3077       ConflictingDecls.push_back(FoundDecl);
3078     }
3079 
3080     if (!ConflictingDecls.empty()) {
3081       Name = Importer.HandleNameConflict(Name, DC, IDNS,
3082                                          ConflictingDecls.data(),
3083                                          ConflictingDecls.size());
3084       if (!Name)
3085         return make_error<ImportError>(ImportError::NameConflict);
3086     }
3087   }
3088 
3089   DeclarationNameInfo NameInfo(Name, Loc);
3090   // Import additional name location/type info.
3091   if (Error Err = ImportDeclarationNameLoc(D->getNameInfo(), NameInfo))
3092     return std::move(Err);
3093 
3094   QualType FromTy = D->getType();
3095   bool usedDifferentExceptionSpec = false;
3096 
3097   if (const auto *FromFPT = D->getType()->getAs<FunctionProtoType>()) {
3098     FunctionProtoType::ExtProtoInfo FromEPI = FromFPT->getExtProtoInfo();
3099     // FunctionProtoType::ExtProtoInfo's ExceptionSpecDecl can point to the
3100     // FunctionDecl that we are importing the FunctionProtoType for.
3101     // To avoid an infinite recursion when importing, create the FunctionDecl
3102     // with a simplified function type and update it afterwards.
3103     if (FromEPI.ExceptionSpec.SourceDecl ||
3104         FromEPI.ExceptionSpec.SourceTemplate ||
3105         FromEPI.ExceptionSpec.NoexceptExpr) {
3106       FunctionProtoType::ExtProtoInfo DefaultEPI;
3107       FromTy = Importer.getFromContext().getFunctionType(
3108           FromFPT->getReturnType(), FromFPT->getParamTypes(), DefaultEPI);
3109       usedDifferentExceptionSpec = true;
3110     }
3111   }
3112 
3113   QualType T;
3114   TypeSourceInfo *TInfo;
3115   SourceLocation ToInnerLocStart, ToEndLoc;
3116   NestedNameSpecifierLoc ToQualifierLoc;
3117   if (auto Imp = importSeq(
3118       FromTy, D->getTypeSourceInfo(), D->getInnerLocStart(),
3119       D->getQualifierLoc(), D->getEndLoc()))
3120     std::tie(T, TInfo, ToInnerLocStart, ToQualifierLoc, ToEndLoc) = *Imp;
3121   else
3122     return Imp.takeError();
3123 
3124   // Import the function parameters.
3125   SmallVector<ParmVarDecl *, 8> Parameters;
3126   for (auto P : D->parameters()) {
3127     if (Expected<ParmVarDecl *> ToPOrErr = import(P))
3128       Parameters.push_back(*ToPOrErr);
3129     else
3130       return ToPOrErr.takeError();
3131   }
3132 
3133   // Create the imported function.
3134   FunctionDecl *ToFunction = nullptr;
3135   if (auto *FromConstructor = dyn_cast<CXXConstructorDecl>(D)) {
3136     if (GetImportedOrCreateDecl<CXXConstructorDecl>(
3137         ToFunction, D, Importer.getToContext(), cast<CXXRecordDecl>(DC),
3138         ToInnerLocStart, NameInfo, T, TInfo,
3139         FromConstructor->isExplicit(),
3140         D->isInlineSpecified(), D->isImplicit(), D->isConstexpr()))
3141       return ToFunction;
3142     if (unsigned NumInitializers = FromConstructor->getNumCtorInitializers()) {
3143       SmallVector<CXXCtorInitializer *, 4> CtorInitializers(NumInitializers);
3144       // Import first, then allocate memory and copy if there was no error.
3145       if (Error Err = ImportContainerChecked(
3146           FromConstructor->inits(), CtorInitializers))
3147         return std::move(Err);
3148       auto **Memory =
3149           new (Importer.getToContext()) CXXCtorInitializer *[NumInitializers];
3150       std::copy(CtorInitializers.begin(), CtorInitializers.end(), Memory);
3151       auto *ToCtor = cast<CXXConstructorDecl>(ToFunction);
3152       ToCtor->setCtorInitializers(Memory);
3153       ToCtor->setNumCtorInitializers(NumInitializers);
3154     }
3155   } else if (isa<CXXDestructorDecl>(D)) {
3156     if (GetImportedOrCreateDecl<CXXDestructorDecl>(
3157         ToFunction, D, Importer.getToContext(), cast<CXXRecordDecl>(DC),
3158         ToInnerLocStart, NameInfo, T, TInfo, D->isInlineSpecified(),
3159         D->isImplicit()))
3160       return ToFunction;
3161   } else if (CXXConversionDecl *FromConversion =
3162                  dyn_cast<CXXConversionDecl>(D)) {
3163     if (GetImportedOrCreateDecl<CXXConversionDecl>(
3164             ToFunction, D, Importer.getToContext(), cast<CXXRecordDecl>(DC),
3165             ToInnerLocStart, NameInfo, T, TInfo, D->isInlineSpecified(),
3166             FromConversion->isExplicit(), D->isConstexpr(), SourceLocation()))
3167       return ToFunction;
3168   } else if (auto *Method = dyn_cast<CXXMethodDecl>(D)) {
3169     if (GetImportedOrCreateDecl<CXXMethodDecl>(
3170             ToFunction, D, Importer.getToContext(), cast<CXXRecordDecl>(DC),
3171             ToInnerLocStart, NameInfo, T, TInfo, Method->getStorageClass(),
3172             Method->isInlineSpecified(), D->isConstexpr(), SourceLocation()))
3173       return ToFunction;
3174   } else {
3175     if (GetImportedOrCreateDecl(ToFunction, D, Importer.getToContext(), DC,
3176                                 ToInnerLocStart, NameInfo, T, TInfo,
3177                                 D->getStorageClass(), D->isInlineSpecified(),
3178                                 D->hasWrittenPrototype(), D->isConstexpr()))
3179       return ToFunction;
3180   }
3181 
3182   ToFunction->setQualifierInfo(ToQualifierLoc);
3183   ToFunction->setAccess(D->getAccess());
3184   ToFunction->setLexicalDeclContext(LexicalDC);
3185   ToFunction->setVirtualAsWritten(D->isVirtualAsWritten());
3186   ToFunction->setTrivial(D->isTrivial());
3187   ToFunction->setPure(D->isPure());
3188   ToFunction->setRangeEnd(ToEndLoc);
3189 
3190   // Set the parameters.
3191   for (auto *Param : Parameters) {
3192     Param->setOwningFunction(ToFunction);
3193     ToFunction->addDeclInternal(Param);
3194   }
3195   ToFunction->setParams(Parameters);
3196 
3197   if (FoundByLookup) {
3198     auto *Recent = const_cast<FunctionDecl *>(
3199           FoundByLookup->getMostRecentDecl());
3200     ToFunction->setPreviousDecl(Recent);
3201   }
3202 
3203   // We need to complete creation of FunctionProtoTypeLoc manually with setting
3204   // params it refers to.
3205   if (TInfo) {
3206     if (auto ProtoLoc =
3207         TInfo->getTypeLoc().IgnoreParens().getAs<FunctionProtoTypeLoc>()) {
3208       for (unsigned I = 0, N = Parameters.size(); I != N; ++I)
3209         ProtoLoc.setParam(I, Parameters[I]);
3210     }
3211   }
3212 
3213   if (usedDifferentExceptionSpec) {
3214     // Update FunctionProtoType::ExtProtoInfo.
3215     if (ExpectedType TyOrErr = import(D->getType()))
3216       ToFunction->setType(*TyOrErr);
3217     else
3218       return TyOrErr.takeError();
3219   }
3220 
3221   // Import the describing template function, if any.
3222   if (FromFT) {
3223     auto ToFTOrErr = import(FromFT);
3224     if (!ToFTOrErr)
3225       return ToFTOrErr.takeError();
3226   }
3227 
3228   if (D->doesThisDeclarationHaveABody()) {
3229     if (Stmt *FromBody = D->getBody()) {
3230       if (ExpectedStmt ToBodyOrErr = import(FromBody))
3231         ToFunction->setBody(*ToBodyOrErr);
3232       else
3233         return ToBodyOrErr.takeError();
3234     }
3235   }
3236 
3237   // FIXME: Other bits to merge?
3238 
3239   // If it is a template, import all related things.
3240   if (Error Err = ImportTemplateInformation(D, ToFunction))
3241     return std::move(Err);
3242 
3243   bool IsFriend = D->isInIdentifierNamespace(Decl::IDNS_OrdinaryFriend);
3244 
3245   // TODO Can we generalize this approach to other AST nodes as well?
3246   if (D->getDeclContext()->containsDeclAndLoad(D))
3247     DC->addDeclInternal(ToFunction);
3248   if (DC != LexicalDC && D->getLexicalDeclContext()->containsDeclAndLoad(D))
3249     LexicalDC->addDeclInternal(ToFunction);
3250 
3251   // Friend declaration's lexical context is the befriending class, but the
3252   // semantic context is the enclosing scope of the befriending class.
3253   // We want the friend functions to be found in the semantic context by lookup.
3254   // FIXME should we handle this generically in VisitFriendDecl?
3255   // In Other cases when LexicalDC != DC we don't want it to be added,
3256   // e.g out-of-class definitions like void B::f() {} .
3257   if (LexicalDC != DC && IsFriend) {
3258     DC->makeDeclVisibleInContext(ToFunction);
3259   }
3260 
3261   if (auto *FromCXXMethod = dyn_cast<CXXMethodDecl>(D))
3262     ImportOverrides(cast<CXXMethodDecl>(ToFunction), FromCXXMethod);
3263 
3264   // Import the rest of the chain. I.e. import all subsequent declarations.
3265   for (++RedeclIt; RedeclIt != Redecls.end(); ++RedeclIt) {
3266     ExpectedDecl ToRedeclOrErr = import(*RedeclIt);
3267     if (!ToRedeclOrErr)
3268       return ToRedeclOrErr.takeError();
3269   }
3270 
3271   return ToFunction;
3272 }
3273 
3274 ExpectedDecl ASTNodeImporter::VisitCXXMethodDecl(CXXMethodDecl *D) {
3275   return VisitFunctionDecl(D);
3276 }
3277 
3278 ExpectedDecl ASTNodeImporter::VisitCXXConstructorDecl(CXXConstructorDecl *D) {
3279   return VisitCXXMethodDecl(D);
3280 }
3281 
3282 ExpectedDecl ASTNodeImporter::VisitCXXDestructorDecl(CXXDestructorDecl *D) {
3283   return VisitCXXMethodDecl(D);
3284 }
3285 
3286 ExpectedDecl ASTNodeImporter::VisitCXXConversionDecl(CXXConversionDecl *D) {
3287   return VisitCXXMethodDecl(D);
3288 }
3289 
3290 ExpectedDecl ASTNodeImporter::VisitFieldDecl(FieldDecl *D) {
3291   // Import the major distinguishing characteristics of a variable.
3292   DeclContext *DC, *LexicalDC;
3293   DeclarationName Name;
3294   SourceLocation Loc;
3295   NamedDecl *ToD;
3296   if (Error Err = ImportDeclParts(D, DC, LexicalDC, Name, ToD, Loc))
3297     return std::move(Err);
3298   if (ToD)
3299     return ToD;
3300 
3301   // Determine whether we've already imported this field.
3302   SmallVector<NamedDecl *, 2> FoundDecls;
3303   DC->getRedeclContext()->localUncachedLookup(Name, FoundDecls);
3304   for (auto *FoundDecl : FoundDecls) {
3305     if (FieldDecl *FoundField = dyn_cast<FieldDecl>(FoundDecl)) {
3306       // For anonymous fields, match up by index.
3307       if (!Name &&
3308           ASTImporter::getFieldIndex(D) !=
3309           ASTImporter::getFieldIndex(FoundField))
3310         continue;
3311 
3312       if (Importer.IsStructurallyEquivalent(D->getType(),
3313                                             FoundField->getType())) {
3314         Importer.MapImported(D, FoundField);
3315         // In case of a FieldDecl of a ClassTemplateSpecializationDecl, the
3316         // initializer of a FieldDecl might not had been instantiated in the
3317         // "To" context.  However, the "From" context might instantiated that,
3318         // thus we have to merge that.
3319         if (Expr *FromInitializer = D->getInClassInitializer()) {
3320           // We don't have yet the initializer set.
3321           if (FoundField->hasInClassInitializer() &&
3322               !FoundField->getInClassInitializer()) {
3323             if (ExpectedExpr ToInitializerOrErr = import(FromInitializer))
3324               FoundField->setInClassInitializer(*ToInitializerOrErr);
3325             else {
3326               // We can't return error here,
3327               // since we already mapped D as imported.
3328               // FIXME: warning message?
3329               consumeError(ToInitializerOrErr.takeError());
3330               return FoundField;
3331             }
3332           }
3333         }
3334         return FoundField;
3335       }
3336 
3337       // FIXME: Why is this case not handled with calling HandleNameConflict?
3338       Importer.ToDiag(Loc, diag::err_odr_field_type_inconsistent)
3339         << Name << D->getType() << FoundField->getType();
3340       Importer.ToDiag(FoundField->getLocation(), diag::note_odr_value_here)
3341         << FoundField->getType();
3342 
3343       return make_error<ImportError>(ImportError::NameConflict);
3344     }
3345   }
3346 
3347   QualType ToType;
3348   TypeSourceInfo *ToTInfo;
3349   Expr *ToBitWidth;
3350   SourceLocation ToInnerLocStart;
3351   Expr *ToInitializer;
3352   if (auto Imp = importSeq(
3353       D->getType(), D->getTypeSourceInfo(), D->getBitWidth(),
3354       D->getInnerLocStart(), D->getInClassInitializer()))
3355     std::tie(
3356         ToType, ToTInfo, ToBitWidth, ToInnerLocStart, ToInitializer) = *Imp;
3357   else
3358     return Imp.takeError();
3359 
3360   FieldDecl *ToField;
3361   if (GetImportedOrCreateDecl(ToField, D, Importer.getToContext(), DC,
3362                               ToInnerLocStart, Loc, Name.getAsIdentifierInfo(),
3363                               ToType, ToTInfo, ToBitWidth, D->isMutable(),
3364                               D->getInClassInitStyle()))
3365     return ToField;
3366 
3367   ToField->setAccess(D->getAccess());
3368   ToField->setLexicalDeclContext(LexicalDC);
3369   if (ToInitializer)
3370     ToField->setInClassInitializer(ToInitializer);
3371   ToField->setImplicit(D->isImplicit());
3372   LexicalDC->addDeclInternal(ToField);
3373   return ToField;
3374 }
3375 
3376 ExpectedDecl ASTNodeImporter::VisitIndirectFieldDecl(IndirectFieldDecl *D) {
3377   // Import the major distinguishing characteristics of a variable.
3378   DeclContext *DC, *LexicalDC;
3379   DeclarationName Name;
3380   SourceLocation Loc;
3381   NamedDecl *ToD;
3382   if (Error Err = ImportDeclParts(D, DC, LexicalDC, Name, ToD, Loc))
3383     return std::move(Err);
3384   if (ToD)
3385     return ToD;
3386 
3387   // Determine whether we've already imported this field.
3388   SmallVector<NamedDecl *, 2> FoundDecls;
3389   DC->getRedeclContext()->localUncachedLookup(Name, FoundDecls);
3390   for (unsigned I = 0, N = FoundDecls.size(); I != N; ++I) {
3391     if (auto *FoundField = dyn_cast<IndirectFieldDecl>(FoundDecls[I])) {
3392       // For anonymous indirect fields, match up by index.
3393       if (!Name &&
3394           ASTImporter::getFieldIndex(D) !=
3395           ASTImporter::getFieldIndex(FoundField))
3396         continue;
3397 
3398       if (Importer.IsStructurallyEquivalent(D->getType(),
3399                                             FoundField->getType(),
3400                                             !Name.isEmpty())) {
3401         Importer.MapImported(D, FoundField);
3402         return FoundField;
3403       }
3404 
3405       // If there are more anonymous fields to check, continue.
3406       if (!Name && I < N-1)
3407         continue;
3408 
3409       // FIXME: Why is this case not handled with calling HandleNameConflict?
3410       Importer.ToDiag(Loc, diag::err_odr_field_type_inconsistent)
3411         << Name << D->getType() << FoundField->getType();
3412       Importer.ToDiag(FoundField->getLocation(), diag::note_odr_value_here)
3413         << FoundField->getType();
3414 
3415       return make_error<ImportError>(ImportError::NameConflict);
3416     }
3417   }
3418 
3419   // Import the type.
3420   auto TypeOrErr = import(D->getType());
3421   if (!TypeOrErr)
3422     return TypeOrErr.takeError();
3423 
3424   auto **NamedChain =
3425     new (Importer.getToContext()) NamedDecl*[D->getChainingSize()];
3426 
3427   unsigned i = 0;
3428   for (auto *PI : D->chain())
3429     if (Expected<NamedDecl *> ToD = import(PI))
3430       NamedChain[i++] = *ToD;
3431     else
3432       return ToD.takeError();
3433 
3434   llvm::MutableArrayRef<NamedDecl *> CH = {NamedChain, D->getChainingSize()};
3435   IndirectFieldDecl *ToIndirectField;
3436   if (GetImportedOrCreateDecl(ToIndirectField, D, Importer.getToContext(), DC,
3437                               Loc, Name.getAsIdentifierInfo(), *TypeOrErr, CH))
3438     // FIXME here we leak `NamedChain` which is allocated before
3439     return ToIndirectField;
3440 
3441   for (const auto *Attr : D->attrs())
3442     ToIndirectField->addAttr(Importer.Import(Attr));
3443 
3444   ToIndirectField->setAccess(D->getAccess());
3445   ToIndirectField->setLexicalDeclContext(LexicalDC);
3446   LexicalDC->addDeclInternal(ToIndirectField);
3447   return ToIndirectField;
3448 }
3449 
3450 ExpectedDecl ASTNodeImporter::VisitFriendDecl(FriendDecl *D) {
3451   // Import the major distinguishing characteristics of a declaration.
3452   DeclContext *DC, *LexicalDC;
3453   if (Error Err = ImportDeclContext(D, DC, LexicalDC))
3454     return std::move(Err);
3455 
3456   // Determine whether we've already imported this decl.
3457   // FriendDecl is not a NamedDecl so we cannot use localUncachedLookup.
3458   auto *RD = cast<CXXRecordDecl>(DC);
3459   FriendDecl *ImportedFriend = RD->getFirstFriend();
3460 
3461   while (ImportedFriend) {
3462     if (D->getFriendDecl() && ImportedFriend->getFriendDecl()) {
3463       if (IsStructuralMatch(D->getFriendDecl(), ImportedFriend->getFriendDecl(),
3464                             /*Complain=*/false))
3465         return Importer.MapImported(D, ImportedFriend);
3466 
3467     } else if (D->getFriendType() && ImportedFriend->getFriendType()) {
3468       if (Importer.IsStructurallyEquivalent(
3469             D->getFriendType()->getType(),
3470             ImportedFriend->getFriendType()->getType(), true))
3471         return Importer.MapImported(D, ImportedFriend);
3472     }
3473     ImportedFriend = ImportedFriend->getNextFriend();
3474   }
3475 
3476   // Not found. Create it.
3477   FriendDecl::FriendUnion ToFU;
3478   if (NamedDecl *FriendD = D->getFriendDecl()) {
3479     NamedDecl *ToFriendD;
3480     if (Error Err = importInto(ToFriendD, FriendD))
3481       return std::move(Err);
3482 
3483     if (FriendD->getFriendObjectKind() != Decl::FOK_None &&
3484         !(FriendD->isInIdentifierNamespace(Decl::IDNS_NonMemberOperator)))
3485       ToFriendD->setObjectOfFriendDecl(false);
3486 
3487     ToFU = ToFriendD;
3488   } else { // The friend is a type, not a decl.
3489     if (auto TSIOrErr = import(D->getFriendType()))
3490       ToFU = *TSIOrErr;
3491     else
3492       return TSIOrErr.takeError();
3493   }
3494 
3495   SmallVector<TemplateParameterList *, 1> ToTPLists(D->NumTPLists);
3496   auto **FromTPLists = D->getTrailingObjects<TemplateParameterList *>();
3497   for (unsigned I = 0; I < D->NumTPLists; I++) {
3498     if (auto ListOrErr = ImportTemplateParameterList(FromTPLists[I]))
3499       ToTPLists[I] = *ListOrErr;
3500     else
3501       return ListOrErr.takeError();
3502   }
3503 
3504   auto LocationOrErr = import(D->getLocation());
3505   if (!LocationOrErr)
3506     return LocationOrErr.takeError();
3507   auto FriendLocOrErr = import(D->getFriendLoc());
3508   if (!FriendLocOrErr)
3509     return FriendLocOrErr.takeError();
3510 
3511   FriendDecl *FrD;
3512   if (GetImportedOrCreateDecl(FrD, D, Importer.getToContext(), DC,
3513                               *LocationOrErr, ToFU,
3514                               *FriendLocOrErr, ToTPLists))
3515     return FrD;
3516 
3517   FrD->setAccess(D->getAccess());
3518   FrD->setLexicalDeclContext(LexicalDC);
3519   LexicalDC->addDeclInternal(FrD);
3520   return FrD;
3521 }
3522 
3523 ExpectedDecl ASTNodeImporter::VisitObjCIvarDecl(ObjCIvarDecl *D) {
3524   // Import the major distinguishing characteristics of an ivar.
3525   DeclContext *DC, *LexicalDC;
3526   DeclarationName Name;
3527   SourceLocation Loc;
3528   NamedDecl *ToD;
3529   if (Error Err = ImportDeclParts(D, DC, LexicalDC, Name, ToD, Loc))
3530     return std::move(Err);
3531   if (ToD)
3532     return ToD;
3533 
3534   // Determine whether we've already imported this ivar
3535   SmallVector<NamedDecl *, 2> FoundDecls;
3536   DC->getRedeclContext()->localUncachedLookup(Name, FoundDecls);
3537   for (auto *FoundDecl : FoundDecls) {
3538     if (ObjCIvarDecl *FoundIvar = dyn_cast<ObjCIvarDecl>(FoundDecl)) {
3539       if (Importer.IsStructurallyEquivalent(D->getType(),
3540                                             FoundIvar->getType())) {
3541         Importer.MapImported(D, FoundIvar);
3542         return FoundIvar;
3543       }
3544 
3545       Importer.ToDiag(Loc, diag::err_odr_ivar_type_inconsistent)
3546         << Name << D->getType() << FoundIvar->getType();
3547       Importer.ToDiag(FoundIvar->getLocation(), diag::note_odr_value_here)
3548         << FoundIvar->getType();
3549 
3550       return make_error<ImportError>(ImportError::NameConflict);
3551     }
3552   }
3553 
3554   QualType ToType;
3555   TypeSourceInfo *ToTypeSourceInfo;
3556   Expr *ToBitWidth;
3557   SourceLocation ToInnerLocStart;
3558   if (auto Imp = importSeq(
3559       D->getType(), D->getTypeSourceInfo(), D->getBitWidth(), D->getInnerLocStart()))
3560     std::tie(ToType, ToTypeSourceInfo, ToBitWidth, ToInnerLocStart) = *Imp;
3561   else
3562     return Imp.takeError();
3563 
3564   ObjCIvarDecl *ToIvar;
3565   if (GetImportedOrCreateDecl(
3566           ToIvar, D, Importer.getToContext(), cast<ObjCContainerDecl>(DC),
3567           ToInnerLocStart, Loc, Name.getAsIdentifierInfo(),
3568           ToType, ToTypeSourceInfo,
3569           D->getAccessControl(),ToBitWidth, D->getSynthesize()))
3570     return ToIvar;
3571 
3572   ToIvar->setLexicalDeclContext(LexicalDC);
3573   LexicalDC->addDeclInternal(ToIvar);
3574   return ToIvar;
3575 }
3576 
3577 ExpectedDecl ASTNodeImporter::VisitVarDecl(VarDecl *D) {
3578 
3579   SmallVector<Decl*, 2> Redecls = getCanonicalForwardRedeclChain(D);
3580   auto RedeclIt = Redecls.begin();
3581   // Import the first part of the decl chain. I.e. import all previous
3582   // declarations starting from the canonical decl.
3583   for (; RedeclIt != Redecls.end() && *RedeclIt != D; ++RedeclIt) {
3584     ExpectedDecl RedeclOrErr = import(*RedeclIt);
3585     if (!RedeclOrErr)
3586       return RedeclOrErr.takeError();
3587   }
3588   assert(*RedeclIt == D);
3589 
3590   // Import the major distinguishing characteristics of a variable.
3591   DeclContext *DC, *LexicalDC;
3592   DeclarationName Name;
3593   SourceLocation Loc;
3594   NamedDecl *ToD;
3595   if (Error Err = ImportDeclParts(D, DC, LexicalDC, Name, ToD, Loc))
3596     return std::move(Err);
3597   if (ToD)
3598     return ToD;
3599 
3600   // Try to find a variable in our own ("to") context with the same name and
3601   // in the same context as the variable we're importing.
3602   VarDecl *FoundByLookup = nullptr;
3603   if (D->isFileVarDecl()) {
3604     SmallVector<NamedDecl *, 4> ConflictingDecls;
3605     unsigned IDNS = Decl::IDNS_Ordinary;
3606     SmallVector<NamedDecl *, 2> FoundDecls;
3607     DC->getRedeclContext()->localUncachedLookup(Name, FoundDecls);
3608     for (auto *FoundDecl : FoundDecls) {
3609       if (!FoundDecl->isInIdentifierNamespace(IDNS))
3610         continue;
3611 
3612       if (auto *FoundVar = dyn_cast<VarDecl>(FoundDecl)) {
3613         // We have found a variable that we may need to merge with. Check it.
3614         if (FoundVar->hasExternalFormalLinkage() &&
3615             D->hasExternalFormalLinkage()) {
3616           if (Importer.IsStructurallyEquivalent(D->getType(),
3617                                                 FoundVar->getType())) {
3618 
3619             // The VarDecl in the "From" context has a definition, but in the
3620             // "To" context we already have a definition.
3621             VarDecl *FoundDef = FoundVar->getDefinition();
3622             if (D->isThisDeclarationADefinition() && FoundDef)
3623               // FIXME Check for ODR error if the two definitions have
3624               // different initializers?
3625               return Importer.MapImported(D, FoundDef);
3626 
3627             // The VarDecl in the "From" context has an initializer, but in the
3628             // "To" context we already have an initializer.
3629             const VarDecl *FoundDInit = nullptr;
3630             if (D->getInit() && FoundVar->getAnyInitializer(FoundDInit))
3631               // FIXME Diagnose ODR error if the two initializers are different?
3632               return Importer.MapImported(D, const_cast<VarDecl*>(FoundDInit));
3633 
3634             FoundByLookup = FoundVar;
3635             break;
3636           }
3637 
3638           const ArrayType *FoundArray
3639             = Importer.getToContext().getAsArrayType(FoundVar->getType());
3640           const ArrayType *TArray
3641             = Importer.getToContext().getAsArrayType(D->getType());
3642           if (FoundArray && TArray) {
3643             if (isa<IncompleteArrayType>(FoundArray) &&
3644                 isa<ConstantArrayType>(TArray)) {
3645               // Import the type.
3646               if (auto TyOrErr = import(D->getType()))
3647                 FoundVar->setType(*TyOrErr);
3648               else
3649                 return TyOrErr.takeError();
3650 
3651               FoundByLookup = FoundVar;
3652               break;
3653             } else if (isa<IncompleteArrayType>(TArray) &&
3654                        isa<ConstantArrayType>(FoundArray)) {
3655               FoundByLookup = FoundVar;
3656               break;
3657             }
3658           }
3659 
3660           Importer.ToDiag(Loc, diag::err_odr_variable_type_inconsistent)
3661             << Name << D->getType() << FoundVar->getType();
3662           Importer.ToDiag(FoundVar->getLocation(), diag::note_odr_value_here)
3663             << FoundVar->getType();
3664         }
3665       }
3666 
3667       ConflictingDecls.push_back(FoundDecl);
3668     }
3669 
3670     if (!ConflictingDecls.empty()) {
3671       Name = Importer.HandleNameConflict(Name, DC, IDNS,
3672                                          ConflictingDecls.data(),
3673                                          ConflictingDecls.size());
3674       if (!Name)
3675         return make_error<ImportError>(ImportError::NameConflict);
3676     }
3677   }
3678 
3679   QualType ToType;
3680   TypeSourceInfo *ToTypeSourceInfo;
3681   SourceLocation ToInnerLocStart;
3682   NestedNameSpecifierLoc ToQualifierLoc;
3683   if (auto Imp = importSeq(
3684       D->getType(), D->getTypeSourceInfo(), D->getInnerLocStart(),
3685       D->getQualifierLoc()))
3686     std::tie(ToType, ToTypeSourceInfo, ToInnerLocStart, ToQualifierLoc) = *Imp;
3687   else
3688     return Imp.takeError();
3689 
3690   // Create the imported variable.
3691   VarDecl *ToVar;
3692   if (GetImportedOrCreateDecl(ToVar, D, Importer.getToContext(), DC,
3693                               ToInnerLocStart, Loc,
3694                               Name.getAsIdentifierInfo(),
3695                               ToType, ToTypeSourceInfo,
3696                               D->getStorageClass()))
3697     return ToVar;
3698 
3699   ToVar->setQualifierInfo(ToQualifierLoc);
3700   ToVar->setAccess(D->getAccess());
3701   ToVar->setLexicalDeclContext(LexicalDC);
3702 
3703   if (FoundByLookup) {
3704     auto *Recent = const_cast<VarDecl *>(FoundByLookup->getMostRecentDecl());
3705     ToVar->setPreviousDecl(Recent);
3706   }
3707 
3708   if (Error Err = ImportInitializer(D, ToVar))
3709     return std::move(Err);
3710 
3711   if (D->isConstexpr())
3712     ToVar->setConstexpr(true);
3713 
3714   if (D->getDeclContext()->containsDeclAndLoad(D))
3715     DC->addDeclInternal(ToVar);
3716   if (DC != LexicalDC && D->getLexicalDeclContext()->containsDeclAndLoad(D))
3717     LexicalDC->addDeclInternal(ToVar);
3718 
3719   // Import the rest of the chain. I.e. import all subsequent declarations.
3720   for (++RedeclIt; RedeclIt != Redecls.end(); ++RedeclIt) {
3721     ExpectedDecl RedeclOrErr = import(*RedeclIt);
3722     if (!RedeclOrErr)
3723       return RedeclOrErr.takeError();
3724   }
3725 
3726   return ToVar;
3727 }
3728 
3729 ExpectedDecl ASTNodeImporter::VisitImplicitParamDecl(ImplicitParamDecl *D) {
3730   // Parameters are created in the translation unit's context, then moved
3731   // into the function declaration's context afterward.
3732   DeclContext *DC = Importer.getToContext().getTranslationUnitDecl();
3733 
3734   DeclarationName ToDeclName;
3735   SourceLocation ToLocation;
3736   QualType ToType;
3737   if (auto Imp = importSeq(D->getDeclName(), D->getLocation(), D->getType()))
3738     std::tie(ToDeclName, ToLocation, ToType) = *Imp;
3739   else
3740     return Imp.takeError();
3741 
3742   // Create the imported parameter.
3743   ImplicitParamDecl *ToParm = nullptr;
3744   if (GetImportedOrCreateDecl(ToParm, D, Importer.getToContext(), DC,
3745                               ToLocation, ToDeclName.getAsIdentifierInfo(),
3746                               ToType, D->getParameterKind()))
3747     return ToParm;
3748   return ToParm;
3749 }
3750 
3751 ExpectedDecl ASTNodeImporter::VisitParmVarDecl(ParmVarDecl *D) {
3752   // Parameters are created in the translation unit's context, then moved
3753   // into the function declaration's context afterward.
3754   DeclContext *DC = Importer.getToContext().getTranslationUnitDecl();
3755 
3756   DeclarationName ToDeclName;
3757   SourceLocation ToLocation, ToInnerLocStart;
3758   QualType ToType;
3759   TypeSourceInfo *ToTypeSourceInfo;
3760   if (auto Imp = importSeq(
3761       D->getDeclName(), D->getLocation(), D->getType(), D->getInnerLocStart(),
3762       D->getTypeSourceInfo()))
3763     std::tie(
3764         ToDeclName, ToLocation, ToType, ToInnerLocStart,
3765         ToTypeSourceInfo) = *Imp;
3766   else
3767     return Imp.takeError();
3768 
3769   ParmVarDecl *ToParm;
3770   if (GetImportedOrCreateDecl(ToParm, D, Importer.getToContext(), DC,
3771                               ToInnerLocStart, ToLocation,
3772                               ToDeclName.getAsIdentifierInfo(), ToType,
3773                               ToTypeSourceInfo, D->getStorageClass(),
3774                               /*DefaultArg*/ nullptr))
3775     return ToParm;
3776 
3777   // Set the default argument.
3778   ToParm->setHasInheritedDefaultArg(D->hasInheritedDefaultArg());
3779   ToParm->setKNRPromoted(D->isKNRPromoted());
3780 
3781   if (D->hasUninstantiatedDefaultArg()) {
3782     if (auto ToDefArgOrErr = import(D->getUninstantiatedDefaultArg()))
3783       ToParm->setUninstantiatedDefaultArg(*ToDefArgOrErr);
3784     else
3785       return ToDefArgOrErr.takeError();
3786   } else if (D->hasUnparsedDefaultArg()) {
3787     ToParm->setUnparsedDefaultArg();
3788   } else if (D->hasDefaultArg()) {
3789     if (auto ToDefArgOrErr = import(D->getDefaultArg()))
3790       ToParm->setDefaultArg(*ToDefArgOrErr);
3791     else
3792       return ToDefArgOrErr.takeError();
3793   }
3794 
3795   if (D->isObjCMethodParameter()) {
3796     ToParm->setObjCMethodScopeInfo(D->getFunctionScopeIndex());
3797     ToParm->setObjCDeclQualifier(D->getObjCDeclQualifier());
3798   } else {
3799     ToParm->setScopeInfo(D->getFunctionScopeDepth(),
3800                          D->getFunctionScopeIndex());
3801   }
3802 
3803   return ToParm;
3804 }
3805 
3806 ExpectedDecl ASTNodeImporter::VisitObjCMethodDecl(ObjCMethodDecl *D) {
3807   // Import the major distinguishing characteristics of a method.
3808   DeclContext *DC, *LexicalDC;
3809   DeclarationName Name;
3810   SourceLocation Loc;
3811   NamedDecl *ToD;
3812   if (Error Err = ImportDeclParts(D, DC, LexicalDC, Name, ToD, Loc))
3813     return std::move(Err);
3814   if (ToD)
3815     return ToD;
3816 
3817   SmallVector<NamedDecl *, 2> FoundDecls;
3818   DC->getRedeclContext()->localUncachedLookup(Name, FoundDecls);
3819   for (auto *FoundDecl : FoundDecls) {
3820     if (auto *FoundMethod = dyn_cast<ObjCMethodDecl>(FoundDecl)) {
3821       if (FoundMethod->isInstanceMethod() != D->isInstanceMethod())
3822         continue;
3823 
3824       // Check return types.
3825       if (!Importer.IsStructurallyEquivalent(D->getReturnType(),
3826                                              FoundMethod->getReturnType())) {
3827         Importer.ToDiag(Loc, diag::err_odr_objc_method_result_type_inconsistent)
3828             << D->isInstanceMethod() << Name << D->getReturnType()
3829             << FoundMethod->getReturnType();
3830         Importer.ToDiag(FoundMethod->getLocation(),
3831                         diag::note_odr_objc_method_here)
3832           << D->isInstanceMethod() << Name;
3833 
3834         return make_error<ImportError>(ImportError::NameConflict);
3835       }
3836 
3837       // Check the number of parameters.
3838       if (D->param_size() != FoundMethod->param_size()) {
3839         Importer.ToDiag(Loc, diag::err_odr_objc_method_num_params_inconsistent)
3840           << D->isInstanceMethod() << Name
3841           << D->param_size() << FoundMethod->param_size();
3842         Importer.ToDiag(FoundMethod->getLocation(),
3843                         diag::note_odr_objc_method_here)
3844           << D->isInstanceMethod() << Name;
3845 
3846         return make_error<ImportError>(ImportError::NameConflict);
3847       }
3848 
3849       // Check parameter types.
3850       for (ObjCMethodDecl::param_iterator P = D->param_begin(),
3851              PEnd = D->param_end(), FoundP = FoundMethod->param_begin();
3852            P != PEnd; ++P, ++FoundP) {
3853         if (!Importer.IsStructurallyEquivalent((*P)->getType(),
3854                                                (*FoundP)->getType())) {
3855           Importer.FromDiag((*P)->getLocation(),
3856                             diag::err_odr_objc_method_param_type_inconsistent)
3857             << D->isInstanceMethod() << Name
3858             << (*P)->getType() << (*FoundP)->getType();
3859           Importer.ToDiag((*FoundP)->getLocation(), diag::note_odr_value_here)
3860             << (*FoundP)->getType();
3861 
3862           return make_error<ImportError>(ImportError::NameConflict);
3863         }
3864       }
3865 
3866       // Check variadic/non-variadic.
3867       // Check the number of parameters.
3868       if (D->isVariadic() != FoundMethod->isVariadic()) {
3869         Importer.ToDiag(Loc, diag::err_odr_objc_method_variadic_inconsistent)
3870           << D->isInstanceMethod() << Name;
3871         Importer.ToDiag(FoundMethod->getLocation(),
3872                         diag::note_odr_objc_method_here)
3873           << D->isInstanceMethod() << Name;
3874 
3875         return make_error<ImportError>(ImportError::NameConflict);
3876       }
3877 
3878       // FIXME: Any other bits we need to merge?
3879       return Importer.MapImported(D, FoundMethod);
3880     }
3881   }
3882 
3883   SourceLocation ToEndLoc;
3884   QualType ToReturnType;
3885   TypeSourceInfo *ToReturnTypeSourceInfo;
3886   if (auto Imp = importSeq(
3887       D->getEndLoc(), D->getReturnType(), D->getReturnTypeSourceInfo()))
3888     std::tie(ToEndLoc, ToReturnType, ToReturnTypeSourceInfo) = *Imp;
3889   else
3890     return Imp.takeError();
3891 
3892   ObjCMethodDecl *ToMethod;
3893   if (GetImportedOrCreateDecl(
3894           ToMethod, D, Importer.getToContext(), Loc,
3895           ToEndLoc, Name.getObjCSelector(), ToReturnType,
3896           ToReturnTypeSourceInfo, DC, D->isInstanceMethod(), D->isVariadic(),
3897           D->isPropertyAccessor(), D->isImplicit(), D->isDefined(),
3898           D->getImplementationControl(), D->hasRelatedResultType()))
3899     return ToMethod;
3900 
3901   // FIXME: When we decide to merge method definitions, we'll need to
3902   // deal with implicit parameters.
3903 
3904   // Import the parameters
3905   SmallVector<ParmVarDecl *, 5> ToParams;
3906   for (auto *FromP : D->parameters()) {
3907     if (Expected<ParmVarDecl *> ToPOrErr = import(FromP))
3908       ToParams.push_back(*ToPOrErr);
3909     else
3910       return ToPOrErr.takeError();
3911   }
3912 
3913   // Set the parameters.
3914   for (auto *ToParam : ToParams) {
3915     ToParam->setOwningFunction(ToMethod);
3916     ToMethod->addDeclInternal(ToParam);
3917   }
3918 
3919   SmallVector<SourceLocation, 12> FromSelLocs;
3920   D->getSelectorLocs(FromSelLocs);
3921   SmallVector<SourceLocation, 12> ToSelLocs(FromSelLocs.size());
3922   if (Error Err = ImportContainerChecked(FromSelLocs, ToSelLocs))
3923     return std::move(Err);
3924 
3925   ToMethod->setMethodParams(Importer.getToContext(), ToParams, ToSelLocs);
3926 
3927   ToMethod->setLexicalDeclContext(LexicalDC);
3928   LexicalDC->addDeclInternal(ToMethod);
3929   return ToMethod;
3930 }
3931 
3932 ExpectedDecl ASTNodeImporter::VisitObjCTypeParamDecl(ObjCTypeParamDecl *D) {
3933   // Import the major distinguishing characteristics of a category.
3934   DeclContext *DC, *LexicalDC;
3935   DeclarationName Name;
3936   SourceLocation Loc;
3937   NamedDecl *ToD;
3938   if (Error Err = ImportDeclParts(D, DC, LexicalDC, Name, ToD, Loc))
3939     return std::move(Err);
3940   if (ToD)
3941     return ToD;
3942 
3943   SourceLocation ToVarianceLoc, ToLocation, ToColonLoc;
3944   TypeSourceInfo *ToTypeSourceInfo;
3945   if (auto Imp = importSeq(
3946       D->getVarianceLoc(), D->getLocation(), D->getColonLoc(),
3947       D->getTypeSourceInfo()))
3948     std::tie(ToVarianceLoc, ToLocation, ToColonLoc, ToTypeSourceInfo) = *Imp;
3949   else
3950     return Imp.takeError();
3951 
3952   ObjCTypeParamDecl *Result;
3953   if (GetImportedOrCreateDecl(
3954           Result, D, Importer.getToContext(), DC, D->getVariance(),
3955           ToVarianceLoc, D->getIndex(),
3956           ToLocation, Name.getAsIdentifierInfo(),
3957           ToColonLoc, ToTypeSourceInfo))
3958     return Result;
3959 
3960   Result->setLexicalDeclContext(LexicalDC);
3961   return Result;
3962 }
3963 
3964 ExpectedDecl ASTNodeImporter::VisitObjCCategoryDecl(ObjCCategoryDecl *D) {
3965   // Import the major distinguishing characteristics of a category.
3966   DeclContext *DC, *LexicalDC;
3967   DeclarationName Name;
3968   SourceLocation Loc;
3969   NamedDecl *ToD;
3970   if (Error Err = ImportDeclParts(D, DC, LexicalDC, Name, ToD, Loc))
3971     return std::move(Err);
3972   if (ToD)
3973     return ToD;
3974 
3975   ObjCInterfaceDecl *ToInterface;
3976   if (Error Err = importInto(ToInterface, D->getClassInterface()))
3977     return std::move(Err);
3978 
3979   // Determine if we've already encountered this category.
3980   ObjCCategoryDecl *MergeWithCategory
3981     = ToInterface->FindCategoryDeclaration(Name.getAsIdentifierInfo());
3982   ObjCCategoryDecl *ToCategory = MergeWithCategory;
3983   if (!ToCategory) {
3984     SourceLocation ToAtStartLoc, ToCategoryNameLoc;
3985     SourceLocation ToIvarLBraceLoc, ToIvarRBraceLoc;
3986     if (auto Imp = importSeq(
3987         D->getAtStartLoc(), D->getCategoryNameLoc(),
3988         D->getIvarLBraceLoc(), D->getIvarRBraceLoc()))
3989       std::tie(
3990           ToAtStartLoc, ToCategoryNameLoc,
3991           ToIvarLBraceLoc, ToIvarRBraceLoc) = *Imp;
3992     else
3993       return Imp.takeError();
3994 
3995     if (GetImportedOrCreateDecl(ToCategory, D, Importer.getToContext(), DC,
3996                                 ToAtStartLoc, Loc,
3997                                 ToCategoryNameLoc,
3998                                 Name.getAsIdentifierInfo(), ToInterface,
3999                                 /*TypeParamList=*/nullptr,
4000                                 ToIvarLBraceLoc,
4001                                 ToIvarRBraceLoc))
4002       return ToCategory;
4003 
4004     ToCategory->setLexicalDeclContext(LexicalDC);
4005     LexicalDC->addDeclInternal(ToCategory);
4006     // Import the type parameter list after MapImported, to avoid
4007     // loops when bringing in their DeclContext.
4008     if (auto PListOrErr = ImportObjCTypeParamList(D->getTypeParamList()))
4009       ToCategory->setTypeParamList(*PListOrErr);
4010     else
4011       return PListOrErr.takeError();
4012 
4013     // Import protocols
4014     SmallVector<ObjCProtocolDecl *, 4> Protocols;
4015     SmallVector<SourceLocation, 4> ProtocolLocs;
4016     ObjCCategoryDecl::protocol_loc_iterator FromProtoLoc
4017       = D->protocol_loc_begin();
4018     for (ObjCCategoryDecl::protocol_iterator FromProto = D->protocol_begin(),
4019                                           FromProtoEnd = D->protocol_end();
4020          FromProto != FromProtoEnd;
4021          ++FromProto, ++FromProtoLoc) {
4022       if (Expected<ObjCProtocolDecl *> ToProtoOrErr = import(*FromProto))
4023         Protocols.push_back(*ToProtoOrErr);
4024       else
4025         return ToProtoOrErr.takeError();
4026 
4027       if (ExpectedSLoc ToProtoLocOrErr = import(*FromProtoLoc))
4028         ProtocolLocs.push_back(*ToProtoLocOrErr);
4029       else
4030         return ToProtoLocOrErr.takeError();
4031     }
4032 
4033     // FIXME: If we're merging, make sure that the protocol list is the same.
4034     ToCategory->setProtocolList(Protocols.data(), Protocols.size(),
4035                                 ProtocolLocs.data(), Importer.getToContext());
4036 
4037   } else {
4038     Importer.MapImported(D, ToCategory);
4039   }
4040 
4041   // Import all of the members of this category.
4042   if (Error Err = ImportDeclContext(D))
4043     return std::move(Err);
4044 
4045   // If we have an implementation, import it as well.
4046   if (D->getImplementation()) {
4047     if (Expected<ObjCCategoryImplDecl *> ToImplOrErr =
4048         import(D->getImplementation()))
4049       ToCategory->setImplementation(*ToImplOrErr);
4050     else
4051       return ToImplOrErr.takeError();
4052   }
4053 
4054   return ToCategory;
4055 }
4056 
4057 Error ASTNodeImporter::ImportDefinition(
4058     ObjCProtocolDecl *From, ObjCProtocolDecl *To, ImportDefinitionKind Kind) {
4059   if (To->getDefinition()) {
4060     if (shouldForceImportDeclContext(Kind))
4061       if (Error Err = ImportDeclContext(From))
4062         return Err;
4063     return Error::success();
4064   }
4065 
4066   // Start the protocol definition
4067   To->startDefinition();
4068 
4069   // Import protocols
4070   SmallVector<ObjCProtocolDecl *, 4> Protocols;
4071   SmallVector<SourceLocation, 4> ProtocolLocs;
4072   ObjCProtocolDecl::protocol_loc_iterator FromProtoLoc =
4073       From->protocol_loc_begin();
4074   for (ObjCProtocolDecl::protocol_iterator FromProto = From->protocol_begin(),
4075                                         FromProtoEnd = From->protocol_end();
4076        FromProto != FromProtoEnd;
4077        ++FromProto, ++FromProtoLoc) {
4078     if (Expected<ObjCProtocolDecl *> ToProtoOrErr = import(*FromProto))
4079       Protocols.push_back(*ToProtoOrErr);
4080     else
4081       return ToProtoOrErr.takeError();
4082 
4083     if (ExpectedSLoc ToProtoLocOrErr = import(*FromProtoLoc))
4084       ProtocolLocs.push_back(*ToProtoLocOrErr);
4085     else
4086       return ToProtoLocOrErr.takeError();
4087 
4088   }
4089 
4090   // FIXME: If we're merging, make sure that the protocol list is the same.
4091   To->setProtocolList(Protocols.data(), Protocols.size(),
4092                       ProtocolLocs.data(), Importer.getToContext());
4093 
4094   if (shouldForceImportDeclContext(Kind)) {
4095     // Import all of the members of this protocol.
4096     if (Error Err = ImportDeclContext(From, /*ForceImport=*/true))
4097       return Err;
4098   }
4099   return Error::success();
4100 }
4101 
4102 ExpectedDecl ASTNodeImporter::VisitObjCProtocolDecl(ObjCProtocolDecl *D) {
4103   // If this protocol has a definition in the translation unit we're coming
4104   // from, but this particular declaration is not that definition, import the
4105   // definition and map to that.
4106   ObjCProtocolDecl *Definition = D->getDefinition();
4107   if (Definition && Definition != D) {
4108     if (ExpectedDecl ImportedDefOrErr = import(Definition))
4109       return Importer.MapImported(D, *ImportedDefOrErr);
4110     else
4111       return ImportedDefOrErr.takeError();
4112   }
4113 
4114   // Import the major distinguishing characteristics of a protocol.
4115   DeclContext *DC, *LexicalDC;
4116   DeclarationName Name;
4117   SourceLocation Loc;
4118   NamedDecl *ToD;
4119   if (Error Err = ImportDeclParts(D, DC, LexicalDC, Name, ToD, Loc))
4120     return std::move(Err);
4121   if (ToD)
4122     return ToD;
4123 
4124   ObjCProtocolDecl *MergeWithProtocol = nullptr;
4125   SmallVector<NamedDecl *, 2> FoundDecls;
4126   DC->getRedeclContext()->localUncachedLookup(Name, FoundDecls);
4127   for (auto *FoundDecl : FoundDecls) {
4128     if (!FoundDecl->isInIdentifierNamespace(Decl::IDNS_ObjCProtocol))
4129       continue;
4130 
4131     if ((MergeWithProtocol = dyn_cast<ObjCProtocolDecl>(FoundDecl)))
4132       break;
4133   }
4134 
4135   ObjCProtocolDecl *ToProto = MergeWithProtocol;
4136   if (!ToProto) {
4137     auto ToAtBeginLocOrErr = import(D->getAtStartLoc());
4138     if (!ToAtBeginLocOrErr)
4139       return ToAtBeginLocOrErr.takeError();
4140 
4141     if (GetImportedOrCreateDecl(ToProto, D, Importer.getToContext(), DC,
4142                                 Name.getAsIdentifierInfo(), Loc,
4143                                 *ToAtBeginLocOrErr,
4144                                 /*PrevDecl=*/nullptr))
4145       return ToProto;
4146     ToProto->setLexicalDeclContext(LexicalDC);
4147     LexicalDC->addDeclInternal(ToProto);
4148   }
4149 
4150   Importer.MapImported(D, ToProto);
4151 
4152   if (D->isThisDeclarationADefinition())
4153     if (Error Err = ImportDefinition(D, ToProto))
4154       return std::move(Err);
4155 
4156   return ToProto;
4157 }
4158 
4159 ExpectedDecl ASTNodeImporter::VisitLinkageSpecDecl(LinkageSpecDecl *D) {
4160   DeclContext *DC, *LexicalDC;
4161   if (Error Err = ImportDeclContext(D, DC, LexicalDC))
4162     return std::move(Err);
4163 
4164   ExpectedSLoc ExternLocOrErr = import(D->getExternLoc());
4165   if (!ExternLocOrErr)
4166     return ExternLocOrErr.takeError();
4167 
4168   ExpectedSLoc LangLocOrErr = import(D->getLocation());
4169   if (!LangLocOrErr)
4170     return LangLocOrErr.takeError();
4171 
4172   bool HasBraces = D->hasBraces();
4173 
4174   LinkageSpecDecl *ToLinkageSpec;
4175   if (GetImportedOrCreateDecl(ToLinkageSpec, D, Importer.getToContext(), DC,
4176                               *ExternLocOrErr, *LangLocOrErr,
4177                               D->getLanguage(), HasBraces))
4178     return ToLinkageSpec;
4179 
4180   if (HasBraces) {
4181     ExpectedSLoc RBraceLocOrErr = import(D->getRBraceLoc());
4182     if (!RBraceLocOrErr)
4183       return RBraceLocOrErr.takeError();
4184     ToLinkageSpec->setRBraceLoc(*RBraceLocOrErr);
4185   }
4186 
4187   ToLinkageSpec->setLexicalDeclContext(LexicalDC);
4188   LexicalDC->addDeclInternal(ToLinkageSpec);
4189 
4190   return ToLinkageSpec;
4191 }
4192 
4193 ExpectedDecl ASTNodeImporter::VisitUsingDecl(UsingDecl *D) {
4194   DeclContext *DC, *LexicalDC;
4195   DeclarationName Name;
4196   SourceLocation Loc;
4197   NamedDecl *ToD = nullptr;
4198   if (Error Err = ImportDeclParts(D, DC, LexicalDC, Name, ToD, Loc))
4199     return std::move(Err);
4200   if (ToD)
4201     return ToD;
4202 
4203   SourceLocation ToLoc, ToUsingLoc;
4204   NestedNameSpecifierLoc ToQualifierLoc;
4205   if (auto Imp = importSeq(
4206       D->getNameInfo().getLoc(), D->getUsingLoc(), D->getQualifierLoc()))
4207     std::tie(ToLoc, ToUsingLoc, ToQualifierLoc) = *Imp;
4208   else
4209     return Imp.takeError();
4210 
4211   DeclarationNameInfo NameInfo(Name, ToLoc);
4212   if (Error Err = ImportDeclarationNameLoc(D->getNameInfo(), NameInfo))
4213     return std::move(Err);
4214 
4215   UsingDecl *ToUsing;
4216   if (GetImportedOrCreateDecl(ToUsing, D, Importer.getToContext(), DC,
4217                               ToUsingLoc, ToQualifierLoc, NameInfo,
4218                               D->hasTypename()))
4219     return ToUsing;
4220 
4221   ToUsing->setLexicalDeclContext(LexicalDC);
4222   LexicalDC->addDeclInternal(ToUsing);
4223 
4224   if (NamedDecl *FromPattern =
4225       Importer.getFromContext().getInstantiatedFromUsingDecl(D)) {
4226     if (Expected<NamedDecl *> ToPatternOrErr = import(FromPattern))
4227       Importer.getToContext().setInstantiatedFromUsingDecl(
4228           ToUsing, *ToPatternOrErr);
4229     else
4230       return ToPatternOrErr.takeError();
4231   }
4232 
4233   for (UsingShadowDecl *FromShadow : D->shadows()) {
4234     if (Expected<UsingShadowDecl *> ToShadowOrErr = import(FromShadow))
4235       ToUsing->addShadowDecl(*ToShadowOrErr);
4236     else
4237       // FIXME: We return error here but the definition is already created
4238       // and available with lookups. How to fix this?..
4239       return ToShadowOrErr.takeError();
4240   }
4241   return ToUsing;
4242 }
4243 
4244 ExpectedDecl ASTNodeImporter::VisitUsingShadowDecl(UsingShadowDecl *D) {
4245   DeclContext *DC, *LexicalDC;
4246   DeclarationName Name;
4247   SourceLocation Loc;
4248   NamedDecl *ToD = nullptr;
4249   if (Error Err = ImportDeclParts(D, DC, LexicalDC, Name, ToD, Loc))
4250     return std::move(Err);
4251   if (ToD)
4252     return ToD;
4253 
4254   Expected<UsingDecl *> ToUsingOrErr = import(D->getUsingDecl());
4255   if (!ToUsingOrErr)
4256     return ToUsingOrErr.takeError();
4257 
4258   Expected<NamedDecl *> ToTargetOrErr = import(D->getTargetDecl());
4259   if (!ToTargetOrErr)
4260     return ToTargetOrErr.takeError();
4261 
4262   UsingShadowDecl *ToShadow;
4263   if (GetImportedOrCreateDecl(ToShadow, D, Importer.getToContext(), DC, Loc,
4264                               *ToUsingOrErr, *ToTargetOrErr))
4265     return ToShadow;
4266 
4267   ToShadow->setLexicalDeclContext(LexicalDC);
4268   ToShadow->setAccess(D->getAccess());
4269 
4270   if (UsingShadowDecl *FromPattern =
4271       Importer.getFromContext().getInstantiatedFromUsingShadowDecl(D)) {
4272     if (Expected<UsingShadowDecl *> ToPatternOrErr = import(FromPattern))
4273       Importer.getToContext().setInstantiatedFromUsingShadowDecl(
4274           ToShadow, *ToPatternOrErr);
4275     else
4276       // FIXME: We return error here but the definition is already created
4277       // and available with lookups. How to fix this?..
4278       return ToPatternOrErr.takeError();
4279   }
4280 
4281   LexicalDC->addDeclInternal(ToShadow);
4282 
4283   return ToShadow;
4284 }
4285 
4286 ExpectedDecl ASTNodeImporter::VisitUsingDirectiveDecl(UsingDirectiveDecl *D) {
4287   DeclContext *DC, *LexicalDC;
4288   DeclarationName Name;
4289   SourceLocation Loc;
4290   NamedDecl *ToD = nullptr;
4291   if (Error Err = ImportDeclParts(D, DC, LexicalDC, Name, ToD, Loc))
4292     return std::move(Err);
4293   if (ToD)
4294     return ToD;
4295 
4296   auto ToComAncestorOrErr = Importer.ImportContext(D->getCommonAncestor());
4297   if (!ToComAncestorOrErr)
4298     return ToComAncestorOrErr.takeError();
4299 
4300   NamespaceDecl *ToNominatedNamespace;
4301   SourceLocation ToUsingLoc, ToNamespaceKeyLocation, ToIdentLocation;
4302   NestedNameSpecifierLoc ToQualifierLoc;
4303   if (auto Imp = importSeq(
4304       D->getNominatedNamespace(), D->getUsingLoc(),
4305       D->getNamespaceKeyLocation(), D->getQualifierLoc(),
4306       D->getIdentLocation()))
4307     std::tie(
4308         ToNominatedNamespace, ToUsingLoc, ToNamespaceKeyLocation,
4309         ToQualifierLoc, ToIdentLocation) = *Imp;
4310   else
4311     return Imp.takeError();
4312 
4313   UsingDirectiveDecl *ToUsingDir;
4314   if (GetImportedOrCreateDecl(ToUsingDir, D, Importer.getToContext(), DC,
4315                               ToUsingLoc,
4316                               ToNamespaceKeyLocation,
4317                               ToQualifierLoc,
4318                               ToIdentLocation,
4319                               ToNominatedNamespace, *ToComAncestorOrErr))
4320     return ToUsingDir;
4321 
4322   ToUsingDir->setLexicalDeclContext(LexicalDC);
4323   LexicalDC->addDeclInternal(ToUsingDir);
4324 
4325   return ToUsingDir;
4326 }
4327 
4328 ExpectedDecl ASTNodeImporter::VisitUnresolvedUsingValueDecl(
4329     UnresolvedUsingValueDecl *D) {
4330   DeclContext *DC, *LexicalDC;
4331   DeclarationName Name;
4332   SourceLocation Loc;
4333   NamedDecl *ToD = nullptr;
4334   if (Error Err = ImportDeclParts(D, DC, LexicalDC, Name, ToD, Loc))
4335     return std::move(Err);
4336   if (ToD)
4337     return ToD;
4338 
4339   SourceLocation ToLoc, ToUsingLoc, ToEllipsisLoc;
4340   NestedNameSpecifierLoc ToQualifierLoc;
4341   if (auto Imp = importSeq(
4342       D->getNameInfo().getLoc(), D->getUsingLoc(), D->getQualifierLoc(),
4343       D->getEllipsisLoc()))
4344     std::tie(ToLoc, ToUsingLoc, ToQualifierLoc, ToEllipsisLoc) = *Imp;
4345   else
4346     return Imp.takeError();
4347 
4348   DeclarationNameInfo NameInfo(Name, ToLoc);
4349   if (Error Err = ImportDeclarationNameLoc(D->getNameInfo(), NameInfo))
4350     return std::move(Err);
4351 
4352   UnresolvedUsingValueDecl *ToUsingValue;
4353   if (GetImportedOrCreateDecl(ToUsingValue, D, Importer.getToContext(), DC,
4354                               ToUsingLoc, ToQualifierLoc, NameInfo,
4355                               ToEllipsisLoc))
4356     return ToUsingValue;
4357 
4358   ToUsingValue->setAccess(D->getAccess());
4359   ToUsingValue->setLexicalDeclContext(LexicalDC);
4360   LexicalDC->addDeclInternal(ToUsingValue);
4361 
4362   return ToUsingValue;
4363 }
4364 
4365 ExpectedDecl ASTNodeImporter::VisitUnresolvedUsingTypenameDecl(
4366     UnresolvedUsingTypenameDecl *D) {
4367   DeclContext *DC, *LexicalDC;
4368   DeclarationName Name;
4369   SourceLocation Loc;
4370   NamedDecl *ToD = nullptr;
4371   if (Error Err = ImportDeclParts(D, DC, LexicalDC, Name, ToD, Loc))
4372     return std::move(Err);
4373   if (ToD)
4374     return ToD;
4375 
4376   SourceLocation ToUsingLoc, ToTypenameLoc, ToEllipsisLoc;
4377   NestedNameSpecifierLoc ToQualifierLoc;
4378   if (auto Imp = importSeq(
4379       D->getUsingLoc(), D->getTypenameLoc(), D->getQualifierLoc(),
4380       D->getEllipsisLoc()))
4381     std::tie(ToUsingLoc, ToTypenameLoc, ToQualifierLoc, ToEllipsisLoc) = *Imp;
4382   else
4383     return Imp.takeError();
4384 
4385   UnresolvedUsingTypenameDecl *ToUsing;
4386   if (GetImportedOrCreateDecl(ToUsing, D, Importer.getToContext(), DC,
4387                               ToUsingLoc, ToTypenameLoc,
4388                               ToQualifierLoc, Loc, Name, ToEllipsisLoc))
4389     return ToUsing;
4390 
4391   ToUsing->setAccess(D->getAccess());
4392   ToUsing->setLexicalDeclContext(LexicalDC);
4393   LexicalDC->addDeclInternal(ToUsing);
4394 
4395   return ToUsing;
4396 }
4397 
4398 
4399 Error ASTNodeImporter::ImportDefinition(
4400     ObjCInterfaceDecl *From, ObjCInterfaceDecl *To, ImportDefinitionKind Kind) {
4401   if (To->getDefinition()) {
4402     // Check consistency of superclass.
4403     ObjCInterfaceDecl *FromSuper = From->getSuperClass();
4404     if (FromSuper) {
4405       if (auto FromSuperOrErr = import(FromSuper))
4406         FromSuper = *FromSuperOrErr;
4407       else
4408         return FromSuperOrErr.takeError();
4409     }
4410 
4411     ObjCInterfaceDecl *ToSuper = To->getSuperClass();
4412     if ((bool)FromSuper != (bool)ToSuper ||
4413         (FromSuper && !declaresSameEntity(FromSuper, ToSuper))) {
4414       Importer.ToDiag(To->getLocation(),
4415                       diag::err_odr_objc_superclass_inconsistent)
4416         << To->getDeclName();
4417       if (ToSuper)
4418         Importer.ToDiag(To->getSuperClassLoc(), diag::note_odr_objc_superclass)
4419           << To->getSuperClass()->getDeclName();
4420       else
4421         Importer.ToDiag(To->getLocation(),
4422                         diag::note_odr_objc_missing_superclass);
4423       if (From->getSuperClass())
4424         Importer.FromDiag(From->getSuperClassLoc(),
4425                           diag::note_odr_objc_superclass)
4426         << From->getSuperClass()->getDeclName();
4427       else
4428         Importer.FromDiag(From->getLocation(),
4429                           diag::note_odr_objc_missing_superclass);
4430     }
4431 
4432     if (shouldForceImportDeclContext(Kind))
4433       if (Error Err = ImportDeclContext(From))
4434         return Err;
4435     return Error::success();
4436   }
4437 
4438   // Start the definition.
4439   To->startDefinition();
4440 
4441   // If this class has a superclass, import it.
4442   if (From->getSuperClass()) {
4443     if (auto SuperTInfoOrErr = import(From->getSuperClassTInfo()))
4444       To->setSuperClass(*SuperTInfoOrErr);
4445     else
4446       return SuperTInfoOrErr.takeError();
4447   }
4448 
4449   // Import protocols
4450   SmallVector<ObjCProtocolDecl *, 4> Protocols;
4451   SmallVector<SourceLocation, 4> ProtocolLocs;
4452   ObjCInterfaceDecl::protocol_loc_iterator FromProtoLoc =
4453       From->protocol_loc_begin();
4454 
4455   for (ObjCInterfaceDecl::protocol_iterator FromProto = From->protocol_begin(),
4456                                          FromProtoEnd = From->protocol_end();
4457        FromProto != FromProtoEnd;
4458        ++FromProto, ++FromProtoLoc) {
4459     if (Expected<ObjCProtocolDecl *> ToProtoOrErr = import(*FromProto))
4460       Protocols.push_back(*ToProtoOrErr);
4461     else
4462       return ToProtoOrErr.takeError();
4463 
4464     if (ExpectedSLoc ToProtoLocOrErr = import(*FromProtoLoc))
4465       ProtocolLocs.push_back(*ToProtoLocOrErr);
4466     else
4467       return ToProtoLocOrErr.takeError();
4468 
4469   }
4470 
4471   // FIXME: If we're merging, make sure that the protocol list is the same.
4472   To->setProtocolList(Protocols.data(), Protocols.size(),
4473                       ProtocolLocs.data(), Importer.getToContext());
4474 
4475   // Import categories. When the categories themselves are imported, they'll
4476   // hook themselves into this interface.
4477   for (auto *Cat : From->known_categories()) {
4478     auto ToCatOrErr = import(Cat);
4479     if (!ToCatOrErr)
4480       return ToCatOrErr.takeError();
4481   }
4482 
4483   // If we have an @implementation, import it as well.
4484   if (From->getImplementation()) {
4485     if (Expected<ObjCImplementationDecl *> ToImplOrErr =
4486         import(From->getImplementation()))
4487       To->setImplementation(*ToImplOrErr);
4488     else
4489       return ToImplOrErr.takeError();
4490   }
4491 
4492   if (shouldForceImportDeclContext(Kind)) {
4493     // Import all of the members of this class.
4494     if (Error Err = ImportDeclContext(From, /*ForceImport=*/true))
4495       return Err;
4496   }
4497   return Error::success();
4498 }
4499 
4500 Expected<ObjCTypeParamList *>
4501 ASTNodeImporter::ImportObjCTypeParamList(ObjCTypeParamList *list) {
4502   if (!list)
4503     return nullptr;
4504 
4505   SmallVector<ObjCTypeParamDecl *, 4> toTypeParams;
4506   for (auto *fromTypeParam : *list) {
4507     if (auto toTypeParamOrErr = import(fromTypeParam))
4508       toTypeParams.push_back(*toTypeParamOrErr);
4509     else
4510       return toTypeParamOrErr.takeError();
4511   }
4512 
4513   auto LAngleLocOrErr = import(list->getLAngleLoc());
4514   if (!LAngleLocOrErr)
4515     return LAngleLocOrErr.takeError();
4516 
4517   auto RAngleLocOrErr = import(list->getRAngleLoc());
4518   if (!RAngleLocOrErr)
4519     return RAngleLocOrErr.takeError();
4520 
4521   return ObjCTypeParamList::create(Importer.getToContext(),
4522                                    *LAngleLocOrErr,
4523                                    toTypeParams,
4524                                    *RAngleLocOrErr);
4525 }
4526 
4527 ExpectedDecl ASTNodeImporter::VisitObjCInterfaceDecl(ObjCInterfaceDecl *D) {
4528   // If this class has a definition in the translation unit we're coming from,
4529   // but this particular declaration is not that definition, import the
4530   // definition and map to that.
4531   ObjCInterfaceDecl *Definition = D->getDefinition();
4532   if (Definition && Definition != D) {
4533     if (ExpectedDecl ImportedDefOrErr = import(Definition))
4534       return Importer.MapImported(D, *ImportedDefOrErr);
4535     else
4536       return ImportedDefOrErr.takeError();
4537   }
4538 
4539   // Import the major distinguishing characteristics of an @interface.
4540   DeclContext *DC, *LexicalDC;
4541   DeclarationName Name;
4542   SourceLocation Loc;
4543   NamedDecl *ToD;
4544   if (Error Err = ImportDeclParts(D, DC, LexicalDC, Name, ToD, Loc))
4545     return std::move(Err);
4546   if (ToD)
4547     return ToD;
4548 
4549   // Look for an existing interface with the same name.
4550   ObjCInterfaceDecl *MergeWithIface = nullptr;
4551   SmallVector<NamedDecl *, 2> FoundDecls;
4552   DC->getRedeclContext()->localUncachedLookup(Name, FoundDecls);
4553   for (auto *FoundDecl : FoundDecls) {
4554     if (!FoundDecl->isInIdentifierNamespace(Decl::IDNS_Ordinary))
4555       continue;
4556 
4557     if ((MergeWithIface = dyn_cast<ObjCInterfaceDecl>(FoundDecl)))
4558       break;
4559   }
4560 
4561   // Create an interface declaration, if one does not already exist.
4562   ObjCInterfaceDecl *ToIface = MergeWithIface;
4563   if (!ToIface) {
4564     ExpectedSLoc AtBeginLocOrErr = import(D->getAtStartLoc());
4565     if (!AtBeginLocOrErr)
4566       return AtBeginLocOrErr.takeError();
4567 
4568     if (GetImportedOrCreateDecl(
4569             ToIface, D, Importer.getToContext(), DC,
4570             *AtBeginLocOrErr, Name.getAsIdentifierInfo(),
4571             /*TypeParamList=*/nullptr,
4572             /*PrevDecl=*/nullptr, Loc, D->isImplicitInterfaceDecl()))
4573       return ToIface;
4574     ToIface->setLexicalDeclContext(LexicalDC);
4575     LexicalDC->addDeclInternal(ToIface);
4576   }
4577   Importer.MapImported(D, ToIface);
4578   // Import the type parameter list after MapImported, to avoid
4579   // loops when bringing in their DeclContext.
4580   if (auto ToPListOrErr =
4581       ImportObjCTypeParamList(D->getTypeParamListAsWritten()))
4582     ToIface->setTypeParamList(*ToPListOrErr);
4583   else
4584     return ToPListOrErr.takeError();
4585 
4586   if (D->isThisDeclarationADefinition())
4587     if (Error Err = ImportDefinition(D, ToIface))
4588       return std::move(Err);
4589 
4590   return ToIface;
4591 }
4592 
4593 ExpectedDecl
4594 ASTNodeImporter::VisitObjCCategoryImplDecl(ObjCCategoryImplDecl *D) {
4595   ObjCCategoryDecl *Category;
4596   if (Error Err = importInto(Category, D->getCategoryDecl()))
4597     return std::move(Err);
4598 
4599   ObjCCategoryImplDecl *ToImpl = Category->getImplementation();
4600   if (!ToImpl) {
4601     DeclContext *DC, *LexicalDC;
4602     if (Error Err = ImportDeclContext(D, DC, LexicalDC))
4603       return std::move(Err);
4604 
4605     SourceLocation ToLocation, ToAtStartLoc, ToCategoryNameLoc;
4606     if (auto Imp = importSeq(
4607         D->getLocation(), D->getAtStartLoc(), D->getCategoryNameLoc()))
4608       std::tie(ToLocation, ToAtStartLoc, ToCategoryNameLoc) = *Imp;
4609     else
4610       return Imp.takeError();
4611 
4612     if (GetImportedOrCreateDecl(
4613             ToImpl, D, Importer.getToContext(), DC,
4614             Importer.Import(D->getIdentifier()), Category->getClassInterface(),
4615             ToLocation, ToAtStartLoc, ToCategoryNameLoc))
4616       return ToImpl;
4617 
4618     ToImpl->setLexicalDeclContext(LexicalDC);
4619     LexicalDC->addDeclInternal(ToImpl);
4620     Category->setImplementation(ToImpl);
4621   }
4622 
4623   Importer.MapImported(D, ToImpl);
4624   if (Error Err = ImportDeclContext(D))
4625     return std::move(Err);
4626 
4627   return ToImpl;
4628 }
4629 
4630 ExpectedDecl
4631 ASTNodeImporter::VisitObjCImplementationDecl(ObjCImplementationDecl *D) {
4632   // Find the corresponding interface.
4633   ObjCInterfaceDecl *Iface;
4634   if (Error Err = importInto(Iface, D->getClassInterface()))
4635     return std::move(Err);
4636 
4637   // Import the superclass, if any.
4638   ObjCInterfaceDecl *Super;
4639   if (Error Err = importInto(Super, D->getSuperClass()))
4640     return std::move(Err);
4641 
4642   ObjCImplementationDecl *Impl = Iface->getImplementation();
4643   if (!Impl) {
4644     // We haven't imported an implementation yet. Create a new @implementation
4645     // now.
4646     DeclContext *DC, *LexicalDC;
4647     if (Error Err = ImportDeclContext(D, DC, LexicalDC))
4648       return std::move(Err);
4649 
4650     SourceLocation ToLocation, ToAtStartLoc, ToSuperClassLoc;
4651     SourceLocation ToIvarLBraceLoc, ToIvarRBraceLoc;
4652     if (auto Imp = importSeq(
4653         D->getLocation(), D->getAtStartLoc(), D->getSuperClassLoc(),
4654         D->getIvarLBraceLoc(), D->getIvarRBraceLoc()))
4655       std::tie(
4656           ToLocation, ToAtStartLoc, ToSuperClassLoc,
4657           ToIvarLBraceLoc, ToIvarRBraceLoc) = *Imp;
4658     else
4659       return Imp.takeError();
4660 
4661     if (GetImportedOrCreateDecl(Impl, D, Importer.getToContext(),
4662                                 DC, Iface, Super,
4663                                 ToLocation,
4664                                 ToAtStartLoc,
4665                                 ToSuperClassLoc,
4666                                 ToIvarLBraceLoc,
4667                                 ToIvarRBraceLoc))
4668       return Impl;
4669 
4670     Impl->setLexicalDeclContext(LexicalDC);
4671 
4672     // Associate the implementation with the class it implements.
4673     Iface->setImplementation(Impl);
4674     Importer.MapImported(D, Iface->getImplementation());
4675   } else {
4676     Importer.MapImported(D, Iface->getImplementation());
4677 
4678     // Verify that the existing @implementation has the same superclass.
4679     if ((Super && !Impl->getSuperClass()) ||
4680         (!Super && Impl->getSuperClass()) ||
4681         (Super && Impl->getSuperClass() &&
4682          !declaresSameEntity(Super->getCanonicalDecl(),
4683                              Impl->getSuperClass()))) {
4684       Importer.ToDiag(Impl->getLocation(),
4685                       diag::err_odr_objc_superclass_inconsistent)
4686         << Iface->getDeclName();
4687       // FIXME: It would be nice to have the location of the superclass
4688       // below.
4689       if (Impl->getSuperClass())
4690         Importer.ToDiag(Impl->getLocation(),
4691                         diag::note_odr_objc_superclass)
4692         << Impl->getSuperClass()->getDeclName();
4693       else
4694         Importer.ToDiag(Impl->getLocation(),
4695                         diag::note_odr_objc_missing_superclass);
4696       if (D->getSuperClass())
4697         Importer.FromDiag(D->getLocation(),
4698                           diag::note_odr_objc_superclass)
4699         << D->getSuperClass()->getDeclName();
4700       else
4701         Importer.FromDiag(D->getLocation(),
4702                           diag::note_odr_objc_missing_superclass);
4703 
4704       return make_error<ImportError>(ImportError::NameConflict);
4705     }
4706   }
4707 
4708   // Import all of the members of this @implementation.
4709   if (Error Err = ImportDeclContext(D))
4710     return std::move(Err);
4711 
4712   return Impl;
4713 }
4714 
4715 ExpectedDecl ASTNodeImporter::VisitObjCPropertyDecl(ObjCPropertyDecl *D) {
4716   // Import the major distinguishing characteristics of an @property.
4717   DeclContext *DC, *LexicalDC;
4718   DeclarationName Name;
4719   SourceLocation Loc;
4720   NamedDecl *ToD;
4721   if (Error Err = ImportDeclParts(D, DC, LexicalDC, Name, ToD, Loc))
4722     return std::move(Err);
4723   if (ToD)
4724     return ToD;
4725 
4726   // Check whether we have already imported this property.
4727   SmallVector<NamedDecl *, 2> FoundDecls;
4728   DC->getRedeclContext()->localUncachedLookup(Name, FoundDecls);
4729   for (auto *FoundDecl : FoundDecls) {
4730     if (auto *FoundProp = dyn_cast<ObjCPropertyDecl>(FoundDecl)) {
4731       // Check property types.
4732       if (!Importer.IsStructurallyEquivalent(D->getType(),
4733                                              FoundProp->getType())) {
4734         Importer.ToDiag(Loc, diag::err_odr_objc_property_type_inconsistent)
4735           << Name << D->getType() << FoundProp->getType();
4736         Importer.ToDiag(FoundProp->getLocation(), diag::note_odr_value_here)
4737           << FoundProp->getType();
4738 
4739         return make_error<ImportError>(ImportError::NameConflict);
4740       }
4741 
4742       // FIXME: Check property attributes, getters, setters, etc.?
4743 
4744       // Consider these properties to be equivalent.
4745       Importer.MapImported(D, FoundProp);
4746       return FoundProp;
4747     }
4748   }
4749 
4750   QualType ToType;
4751   TypeSourceInfo *ToTypeSourceInfo;
4752   SourceLocation ToAtLoc, ToLParenLoc;
4753   if (auto Imp = importSeq(
4754       D->getType(), D->getTypeSourceInfo(), D->getAtLoc(), D->getLParenLoc()))
4755     std::tie(ToType, ToTypeSourceInfo, ToAtLoc, ToLParenLoc) = *Imp;
4756   else
4757     return Imp.takeError();
4758 
4759   // Create the new property.
4760   ObjCPropertyDecl *ToProperty;
4761   if (GetImportedOrCreateDecl(
4762           ToProperty, D, Importer.getToContext(), DC, Loc,
4763           Name.getAsIdentifierInfo(), ToAtLoc,
4764           ToLParenLoc, ToType,
4765           ToTypeSourceInfo, D->getPropertyImplementation()))
4766     return ToProperty;
4767 
4768   Selector ToGetterName, ToSetterName;
4769   SourceLocation ToGetterNameLoc, ToSetterNameLoc;
4770   ObjCMethodDecl *ToGetterMethodDecl, *ToSetterMethodDecl;
4771   ObjCIvarDecl *ToPropertyIvarDecl;
4772   if (auto Imp = importSeq(
4773       D->getGetterName(), D->getSetterName(),
4774       D->getGetterNameLoc(), D->getSetterNameLoc(),
4775       D->getGetterMethodDecl(), D->getSetterMethodDecl(),
4776       D->getPropertyIvarDecl()))
4777     std::tie(
4778         ToGetterName, ToSetterName,
4779         ToGetterNameLoc, ToSetterNameLoc,
4780         ToGetterMethodDecl, ToSetterMethodDecl,
4781         ToPropertyIvarDecl) = *Imp;
4782   else
4783     return Imp.takeError();
4784 
4785   ToProperty->setLexicalDeclContext(LexicalDC);
4786   LexicalDC->addDeclInternal(ToProperty);
4787 
4788   ToProperty->setPropertyAttributes(D->getPropertyAttributes());
4789   ToProperty->setPropertyAttributesAsWritten(
4790                                       D->getPropertyAttributesAsWritten());
4791   ToProperty->setGetterName(ToGetterName, ToGetterNameLoc);
4792   ToProperty->setSetterName(ToSetterName, ToSetterNameLoc);
4793   ToProperty->setGetterMethodDecl(ToGetterMethodDecl);
4794   ToProperty->setSetterMethodDecl(ToSetterMethodDecl);
4795   ToProperty->setPropertyIvarDecl(ToPropertyIvarDecl);
4796   return ToProperty;
4797 }
4798 
4799 ExpectedDecl
4800 ASTNodeImporter::VisitObjCPropertyImplDecl(ObjCPropertyImplDecl *D) {
4801   ObjCPropertyDecl *Property;
4802   if (Error Err = importInto(Property, D->getPropertyDecl()))
4803     return std::move(Err);
4804 
4805   DeclContext *DC, *LexicalDC;
4806   if (Error Err = ImportDeclContext(D, DC, LexicalDC))
4807     return std::move(Err);
4808 
4809   auto *InImpl = cast<ObjCImplDecl>(LexicalDC);
4810 
4811   // Import the ivar (for an @synthesize).
4812   ObjCIvarDecl *Ivar = nullptr;
4813   if (Error Err = importInto(Ivar, D->getPropertyIvarDecl()))
4814     return std::move(Err);
4815 
4816   ObjCPropertyImplDecl *ToImpl
4817     = InImpl->FindPropertyImplDecl(Property->getIdentifier(),
4818                                    Property->getQueryKind());
4819   if (!ToImpl) {
4820     SourceLocation ToBeginLoc, ToLocation, ToPropertyIvarDeclLoc;
4821     if (auto Imp = importSeq(
4822         D->getBeginLoc(), D->getLocation(), D->getPropertyIvarDeclLoc()))
4823       std::tie(ToBeginLoc, ToLocation, ToPropertyIvarDeclLoc) = *Imp;
4824     else
4825       return Imp.takeError();
4826 
4827     if (GetImportedOrCreateDecl(ToImpl, D, Importer.getToContext(), DC,
4828                                 ToBeginLoc,
4829                                 ToLocation, Property,
4830                                 D->getPropertyImplementation(), Ivar,
4831                                 ToPropertyIvarDeclLoc))
4832       return ToImpl;
4833 
4834     ToImpl->setLexicalDeclContext(LexicalDC);
4835     LexicalDC->addDeclInternal(ToImpl);
4836   } else {
4837     // Check that we have the same kind of property implementation (@synthesize
4838     // vs. @dynamic).
4839     if (D->getPropertyImplementation() != ToImpl->getPropertyImplementation()) {
4840       Importer.ToDiag(ToImpl->getLocation(),
4841                       diag::err_odr_objc_property_impl_kind_inconsistent)
4842         << Property->getDeclName()
4843         << (ToImpl->getPropertyImplementation()
4844                                               == ObjCPropertyImplDecl::Dynamic);
4845       Importer.FromDiag(D->getLocation(),
4846                         diag::note_odr_objc_property_impl_kind)
4847         << D->getPropertyDecl()->getDeclName()
4848         << (D->getPropertyImplementation() == ObjCPropertyImplDecl::Dynamic);
4849 
4850       return make_error<ImportError>(ImportError::NameConflict);
4851     }
4852 
4853     // For @synthesize, check that we have the same
4854     if (D->getPropertyImplementation() == ObjCPropertyImplDecl::Synthesize &&
4855         Ivar != ToImpl->getPropertyIvarDecl()) {
4856       Importer.ToDiag(ToImpl->getPropertyIvarDeclLoc(),
4857                       diag::err_odr_objc_synthesize_ivar_inconsistent)
4858         << Property->getDeclName()
4859         << ToImpl->getPropertyIvarDecl()->getDeclName()
4860         << Ivar->getDeclName();
4861       Importer.FromDiag(D->getPropertyIvarDeclLoc(),
4862                         diag::note_odr_objc_synthesize_ivar_here)
4863         << D->getPropertyIvarDecl()->getDeclName();
4864 
4865       return make_error<ImportError>(ImportError::NameConflict);
4866     }
4867 
4868     // Merge the existing implementation with the new implementation.
4869     Importer.MapImported(D, ToImpl);
4870   }
4871 
4872   return ToImpl;
4873 }
4874 
4875 ExpectedDecl
4876 ASTNodeImporter::VisitTemplateTypeParmDecl(TemplateTypeParmDecl *D) {
4877   // For template arguments, we adopt the translation unit as our declaration
4878   // context. This context will be fixed when the actual template declaration
4879   // is created.
4880 
4881   // FIXME: Import default argument.
4882 
4883   ExpectedSLoc BeginLocOrErr = import(D->getBeginLoc());
4884   if (!BeginLocOrErr)
4885     return BeginLocOrErr.takeError();
4886 
4887   ExpectedSLoc LocationOrErr = import(D->getLocation());
4888   if (!LocationOrErr)
4889     return LocationOrErr.takeError();
4890 
4891   TemplateTypeParmDecl *ToD = nullptr;
4892   (void)GetImportedOrCreateDecl(
4893       ToD, D, Importer.getToContext(),
4894       Importer.getToContext().getTranslationUnitDecl(),
4895       *BeginLocOrErr, *LocationOrErr,
4896       D->getDepth(), D->getIndex(), Importer.Import(D->getIdentifier()),
4897       D->wasDeclaredWithTypename(), D->isParameterPack());
4898   return ToD;
4899 }
4900 
4901 ExpectedDecl
4902 ASTNodeImporter::VisitNonTypeTemplateParmDecl(NonTypeTemplateParmDecl *D) {
4903   DeclarationName ToDeclName;
4904   SourceLocation ToLocation, ToInnerLocStart;
4905   QualType ToType;
4906   TypeSourceInfo *ToTypeSourceInfo;
4907   if (auto Imp = importSeq(
4908       D->getDeclName(), D->getLocation(), D->getType(), D->getTypeSourceInfo(),
4909       D->getInnerLocStart()))
4910     std::tie(
4911         ToDeclName, ToLocation, ToType, ToTypeSourceInfo,
4912         ToInnerLocStart) = *Imp;
4913   else
4914     return Imp.takeError();
4915 
4916   // FIXME: Import default argument.
4917 
4918   NonTypeTemplateParmDecl *ToD = nullptr;
4919   (void)GetImportedOrCreateDecl(
4920       ToD, D, Importer.getToContext(),
4921       Importer.getToContext().getTranslationUnitDecl(),
4922       ToInnerLocStart, ToLocation, D->getDepth(),
4923       D->getPosition(), ToDeclName.getAsIdentifierInfo(), ToType,
4924       D->isParameterPack(), ToTypeSourceInfo);
4925   return ToD;
4926 }
4927 
4928 ExpectedDecl
4929 ASTNodeImporter::VisitTemplateTemplateParmDecl(TemplateTemplateParmDecl *D) {
4930   // Import the name of this declaration.
4931   auto NameOrErr = import(D->getDeclName());
4932   if (!NameOrErr)
4933     return NameOrErr.takeError();
4934 
4935   // Import the location of this declaration.
4936   ExpectedSLoc LocationOrErr = import(D->getLocation());
4937   if (!LocationOrErr)
4938     return LocationOrErr.takeError();
4939 
4940   // Import template parameters.
4941   auto TemplateParamsOrErr = ImportTemplateParameterList(
4942       D->getTemplateParameters());
4943   if (!TemplateParamsOrErr)
4944     return TemplateParamsOrErr.takeError();
4945 
4946   // FIXME: Import default argument.
4947 
4948   TemplateTemplateParmDecl *ToD = nullptr;
4949   (void)GetImportedOrCreateDecl(
4950       ToD, D, Importer.getToContext(),
4951       Importer.getToContext().getTranslationUnitDecl(), *LocationOrErr,
4952       D->getDepth(), D->getPosition(), D->isParameterPack(),
4953       (*NameOrErr).getAsIdentifierInfo(),
4954       *TemplateParamsOrErr);
4955   return ToD;
4956 }
4957 
4958 // Returns the definition for a (forward) declaration of a ClassTemplateDecl, if
4959 // it has any definition in the redecl chain.
4960 static ClassTemplateDecl *getDefinition(ClassTemplateDecl *D) {
4961   CXXRecordDecl *ToTemplatedDef = D->getTemplatedDecl()->getDefinition();
4962   if (!ToTemplatedDef)
4963     return nullptr;
4964   ClassTemplateDecl *TemplateWithDef =
4965       ToTemplatedDef->getDescribedClassTemplate();
4966   return TemplateWithDef;
4967 }
4968 
4969 ExpectedDecl ASTNodeImporter::VisitClassTemplateDecl(ClassTemplateDecl *D) {
4970   bool IsFriend = D->getFriendObjectKind() != Decl::FOK_None;
4971 
4972   // If this record has a definition in the translation unit we're coming from,
4973   // but this particular declaration is not that definition, import the
4974   // definition and map to that.
4975   auto *Definition =
4976       cast_or_null<CXXRecordDecl>(D->getTemplatedDecl()->getDefinition());
4977   if (Definition && Definition != D->getTemplatedDecl() && !IsFriend) {
4978     if (ExpectedDecl ImportedDefOrErr = import(
4979         Definition->getDescribedClassTemplate()))
4980       return Importer.MapImported(D, *ImportedDefOrErr);
4981     else
4982       return ImportedDefOrErr.takeError();
4983   }
4984 
4985   // Import the major distinguishing characteristics of this class template.
4986   DeclContext *DC, *LexicalDC;
4987   DeclarationName Name;
4988   SourceLocation Loc;
4989   NamedDecl *ToD;
4990   if (Error Err = ImportDeclParts(D, DC, LexicalDC, Name, ToD, Loc))
4991     return std::move(Err);
4992   if (ToD)
4993     return ToD;
4994 
4995   // We may already have a template of the same name; try to find and match it.
4996   if (!DC->isFunctionOrMethod()) {
4997     SmallVector<NamedDecl *, 4> ConflictingDecls;
4998     SmallVector<NamedDecl *, 2> FoundDecls;
4999     DC->getRedeclContext()->localUncachedLookup(Name, FoundDecls);
5000     for (auto *FoundDecl : FoundDecls) {
5001       if (!FoundDecl->isInIdentifierNamespace(Decl::IDNS_Ordinary))
5002         continue;
5003 
5004       Decl *Found = FoundDecl;
5005       if (auto *FoundTemplate = dyn_cast<ClassTemplateDecl>(Found)) {
5006 
5007         // The class to be imported is a definition.
5008         if (D->isThisDeclarationADefinition()) {
5009           // Lookup will find the fwd decl only if that is more recent than the
5010           // definition. So, try to get the definition if that is available in
5011           // the redecl chain.
5012           ClassTemplateDecl *TemplateWithDef = getDefinition(FoundTemplate);
5013           if (TemplateWithDef)
5014             FoundTemplate = TemplateWithDef;
5015           else
5016             continue;
5017         }
5018 
5019         if (IsStructuralMatch(D, FoundTemplate)) {
5020           if (!IsFriend) {
5021             Importer.MapImported(D->getTemplatedDecl(),
5022                                  FoundTemplate->getTemplatedDecl());
5023             return Importer.MapImported(D, FoundTemplate);
5024           }
5025 
5026           continue;
5027         }
5028       }
5029 
5030       ConflictingDecls.push_back(FoundDecl);
5031     }
5032 
5033     if (!ConflictingDecls.empty()) {
5034       Name = Importer.HandleNameConflict(Name, DC, Decl::IDNS_Ordinary,
5035                                          ConflictingDecls.data(),
5036                                          ConflictingDecls.size());
5037     }
5038 
5039     if (!Name)
5040       return make_error<ImportError>(ImportError::NameConflict);
5041   }
5042 
5043   CXXRecordDecl *FromTemplated = D->getTemplatedDecl();
5044 
5045   // Create the declaration that is being templated.
5046   CXXRecordDecl *ToTemplated;
5047   if (Error Err = importInto(ToTemplated, FromTemplated))
5048     return std::move(Err);
5049 
5050   // Create the class template declaration itself.
5051   auto TemplateParamsOrErr = ImportTemplateParameterList(
5052       D->getTemplateParameters());
5053   if (!TemplateParamsOrErr)
5054     return TemplateParamsOrErr.takeError();
5055 
5056   ClassTemplateDecl *D2;
5057   if (GetImportedOrCreateDecl(D2, D, Importer.getToContext(), DC, Loc, Name,
5058                               *TemplateParamsOrErr, ToTemplated))
5059     return D2;
5060 
5061   ToTemplated->setDescribedClassTemplate(D2);
5062 
5063   if (ToTemplated->getPreviousDecl()) {
5064     assert(
5065         ToTemplated->getPreviousDecl()->getDescribedClassTemplate() &&
5066         "Missing described template");
5067     D2->setPreviousDecl(
5068         ToTemplated->getPreviousDecl()->getDescribedClassTemplate());
5069   }
5070   D2->setAccess(D->getAccess());
5071   D2->setLexicalDeclContext(LexicalDC);
5072   if (!IsFriend)
5073     LexicalDC->addDeclInternal(D2);
5074 
5075   if (FromTemplated->isCompleteDefinition() &&
5076       !ToTemplated->isCompleteDefinition()) {
5077     // FIXME: Import definition!
5078   }
5079 
5080   return D2;
5081 }
5082 
5083 ExpectedDecl ASTNodeImporter::VisitClassTemplateSpecializationDecl(
5084                                           ClassTemplateSpecializationDecl *D) {
5085   // If this record has a definition in the translation unit we're coming from,
5086   // but this particular declaration is not that definition, import the
5087   // definition and map to that.
5088   TagDecl *Definition = D->getDefinition();
5089   if (Definition && Definition != D) {
5090     if (ExpectedDecl ImportedDefOrErr = import(Definition))
5091       return Importer.MapImported(D, *ImportedDefOrErr);
5092     else
5093       return ImportedDefOrErr.takeError();
5094   }
5095 
5096   ClassTemplateDecl *ClassTemplate;
5097   if (Error Err = importInto(ClassTemplate, D->getSpecializedTemplate()))
5098     return std::move(Err);
5099 
5100   // Import the context of this declaration.
5101   DeclContext *DC, *LexicalDC;
5102   if (Error Err = ImportDeclContext(D, DC, LexicalDC))
5103     return std::move(Err);
5104 
5105   // Import template arguments.
5106   SmallVector<TemplateArgument, 2> TemplateArgs;
5107   if (Error Err = ImportTemplateArguments(
5108       D->getTemplateArgs().data(), D->getTemplateArgs().size(), TemplateArgs))
5109     return std::move(Err);
5110 
5111   // Try to find an existing specialization with these template arguments.
5112   void *InsertPos = nullptr;
5113   ClassTemplateSpecializationDecl *D2 = nullptr;
5114   ClassTemplatePartialSpecializationDecl *PartialSpec =
5115             dyn_cast<ClassTemplatePartialSpecializationDecl>(D);
5116   if (PartialSpec)
5117     D2 = ClassTemplate->findPartialSpecialization(TemplateArgs, InsertPos);
5118   else
5119     D2 = ClassTemplate->findSpecialization(TemplateArgs, InsertPos);
5120   ClassTemplateSpecializationDecl * const PrevDecl = D2;
5121   RecordDecl *FoundDef = D2 ? D2->getDefinition() : nullptr;
5122   if (FoundDef) {
5123     if (!D->isCompleteDefinition()) {
5124       // The "From" translation unit only had a forward declaration; call it
5125       // the same declaration.
5126       // TODO Handle the redecl chain properly!
5127       return Importer.MapImported(D, FoundDef);
5128     }
5129 
5130     if (IsStructuralMatch(D, FoundDef)) {
5131 
5132       Importer.MapImported(D, FoundDef);
5133 
5134       // Import those those default field initializers which have been
5135       // instantiated in the "From" context, but not in the "To" context.
5136       for (auto *FromField : D->fields()) {
5137         auto ToOrErr = import(FromField);
5138         if (!ToOrErr)
5139           // FIXME: return the error?
5140           consumeError(ToOrErr.takeError());
5141       }
5142 
5143       // Import those methods which have been instantiated in the
5144       // "From" context, but not in the "To" context.
5145       for (CXXMethodDecl *FromM : D->methods()) {
5146         auto ToOrErr = import(FromM);
5147         if (!ToOrErr)
5148           // FIXME: return the error?
5149           consumeError(ToOrErr.takeError());
5150       }
5151 
5152       // TODO Import instantiated default arguments.
5153       // TODO Import instantiated exception specifications.
5154       //
5155       // Generally, ASTCommon.h/DeclUpdateKind enum gives a very good hint what
5156       // else could be fused during an AST merge.
5157 
5158       return FoundDef;
5159     }
5160   } else { // We either couldn't find any previous specialization in the "To"
5161            // context,  or we found one but without definition.  Let's create a
5162            // new specialization and register that at the class template.
5163 
5164     // Import the location of this declaration.
5165     ExpectedSLoc BeginLocOrErr = import(D->getBeginLoc());
5166     if (!BeginLocOrErr)
5167       return BeginLocOrErr.takeError();
5168     ExpectedSLoc IdLocOrErr = import(D->getLocation());
5169     if (!IdLocOrErr)
5170       return IdLocOrErr.takeError();
5171 
5172     if (PartialSpec) {
5173       // Import TemplateArgumentListInfo.
5174       TemplateArgumentListInfo ToTAInfo;
5175       const auto &ASTTemplateArgs = *PartialSpec->getTemplateArgsAsWritten();
5176       if (Error Err = ImportTemplateArgumentListInfo(ASTTemplateArgs, ToTAInfo))
5177         return std::move(Err);
5178 
5179       QualType CanonInjType;
5180       if (Error Err = importInto(
5181           CanonInjType, PartialSpec->getInjectedSpecializationType()))
5182         return std::move(Err);
5183       CanonInjType = CanonInjType.getCanonicalType();
5184 
5185       auto ToTPListOrErr = ImportTemplateParameterList(
5186           PartialSpec->getTemplateParameters());
5187       if (!ToTPListOrErr)
5188         return ToTPListOrErr.takeError();
5189 
5190       if (GetImportedOrCreateDecl<ClassTemplatePartialSpecializationDecl>(
5191               D2, D, Importer.getToContext(), D->getTagKind(), DC,
5192               *BeginLocOrErr, *IdLocOrErr, *ToTPListOrErr, ClassTemplate,
5193               llvm::makeArrayRef(TemplateArgs.data(), TemplateArgs.size()),
5194               ToTAInfo, CanonInjType,
5195               cast_or_null<ClassTemplatePartialSpecializationDecl>(PrevDecl)))
5196         return D2;
5197 
5198       // Update InsertPos, because preceding import calls may have invalidated
5199       // it by adding new specializations.
5200       if (!ClassTemplate->findPartialSpecialization(TemplateArgs, InsertPos))
5201         // Add this partial specialization to the class template.
5202         ClassTemplate->AddPartialSpecialization(
5203             cast<ClassTemplatePartialSpecializationDecl>(D2), InsertPos);
5204 
5205     } else { // Not a partial specialization.
5206       if (GetImportedOrCreateDecl(
5207               D2, D, Importer.getToContext(), D->getTagKind(), DC,
5208               *BeginLocOrErr, *IdLocOrErr, ClassTemplate, TemplateArgs,
5209               PrevDecl))
5210         return D2;
5211 
5212       // Update InsertPos, because preceding import calls may have invalidated
5213       // it by adding new specializations.
5214       if (!ClassTemplate->findSpecialization(TemplateArgs, InsertPos))
5215         // Add this specialization to the class template.
5216         ClassTemplate->AddSpecialization(D2, InsertPos);
5217     }
5218 
5219     D2->setSpecializationKind(D->getSpecializationKind());
5220 
5221     // Import the qualifier, if any.
5222     if (auto LocOrErr = import(D->getQualifierLoc()))
5223       D2->setQualifierInfo(*LocOrErr);
5224     else
5225       return LocOrErr.takeError();
5226 
5227     if (auto *TSI = D->getTypeAsWritten()) {
5228       if (auto TInfoOrErr = import(TSI))
5229         D2->setTypeAsWritten(*TInfoOrErr);
5230       else
5231         return TInfoOrErr.takeError();
5232 
5233       if (auto LocOrErr = import(D->getTemplateKeywordLoc()))
5234         D2->setTemplateKeywordLoc(*LocOrErr);
5235       else
5236         return LocOrErr.takeError();
5237 
5238       if (auto LocOrErr = import(D->getExternLoc()))
5239         D2->setExternLoc(*LocOrErr);
5240       else
5241         return LocOrErr.takeError();
5242     }
5243 
5244     if (D->getPointOfInstantiation().isValid()) {
5245       if (auto POIOrErr = import(D->getPointOfInstantiation()))
5246         D2->setPointOfInstantiation(*POIOrErr);
5247       else
5248         return POIOrErr.takeError();
5249     }
5250 
5251     D2->setTemplateSpecializationKind(D->getTemplateSpecializationKind());
5252 
5253     // Set the context of this specialization/instantiation.
5254     D2->setLexicalDeclContext(LexicalDC);
5255 
5256     // Add to the DC only if it was an explicit specialization/instantiation.
5257     if (D2->isExplicitInstantiationOrSpecialization()) {
5258       LexicalDC->addDeclInternal(D2);
5259     }
5260   }
5261   if (D->isCompleteDefinition())
5262     if (Error Err = ImportDefinition(D, D2))
5263       return std::move(Err);
5264 
5265   return D2;
5266 }
5267 
5268 ExpectedDecl ASTNodeImporter::VisitVarTemplateDecl(VarTemplateDecl *D) {
5269   // If this variable has a definition in the translation unit we're coming
5270   // from,
5271   // but this particular declaration is not that definition, import the
5272   // definition and map to that.
5273   auto *Definition =
5274       cast_or_null<VarDecl>(D->getTemplatedDecl()->getDefinition());
5275   if (Definition && Definition != D->getTemplatedDecl()) {
5276     if (ExpectedDecl ImportedDefOrErr = import(
5277         Definition->getDescribedVarTemplate()))
5278       return Importer.MapImported(D, *ImportedDefOrErr);
5279     else
5280       return ImportedDefOrErr.takeError();
5281   }
5282 
5283   // Import the major distinguishing characteristics of this variable template.
5284   DeclContext *DC, *LexicalDC;
5285   DeclarationName Name;
5286   SourceLocation Loc;
5287   NamedDecl *ToD;
5288   if (Error Err = ImportDeclParts(D, DC, LexicalDC, Name, ToD, Loc))
5289     return std::move(Err);
5290   if (ToD)
5291     return ToD;
5292 
5293   // We may already have a template of the same name; try to find and match it.
5294   assert(!DC->isFunctionOrMethod() &&
5295          "Variable templates cannot be declared at function scope");
5296   SmallVector<NamedDecl *, 4> ConflictingDecls;
5297   SmallVector<NamedDecl *, 2> FoundDecls;
5298   DC->getRedeclContext()->localUncachedLookup(Name, FoundDecls);
5299   for (auto *FoundDecl : FoundDecls) {
5300     if (!FoundDecl->isInIdentifierNamespace(Decl::IDNS_Ordinary))
5301       continue;
5302 
5303     Decl *Found = FoundDecl;
5304     if (VarTemplateDecl *FoundTemplate = dyn_cast<VarTemplateDecl>(Found)) {
5305       if (IsStructuralMatch(D, FoundTemplate)) {
5306         // The variable templates structurally match; call it the same template.
5307         Importer.MapImported(D->getTemplatedDecl(),
5308                              FoundTemplate->getTemplatedDecl());
5309         return Importer.MapImported(D, FoundTemplate);
5310       }
5311     }
5312 
5313     ConflictingDecls.push_back(FoundDecl);
5314   }
5315 
5316   if (!ConflictingDecls.empty()) {
5317     Name = Importer.HandleNameConflict(Name, DC, Decl::IDNS_Ordinary,
5318                                        ConflictingDecls.data(),
5319                                        ConflictingDecls.size());
5320   }
5321 
5322   if (!Name)
5323     // FIXME: Is it possible to get other error than name conflict?
5324     // (Put this `if` into the previous `if`?)
5325     return make_error<ImportError>(ImportError::NameConflict);
5326 
5327   VarDecl *DTemplated = D->getTemplatedDecl();
5328 
5329   // Import the type.
5330   // FIXME: Value not used?
5331   ExpectedType TypeOrErr = import(DTemplated->getType());
5332   if (!TypeOrErr)
5333     return TypeOrErr.takeError();
5334 
5335   // Create the declaration that is being templated.
5336   VarDecl *ToTemplated;
5337   if (Error Err = importInto(ToTemplated, DTemplated))
5338     return std::move(Err);
5339 
5340   // Create the variable template declaration itself.
5341   auto TemplateParamsOrErr = ImportTemplateParameterList(
5342       D->getTemplateParameters());
5343   if (!TemplateParamsOrErr)
5344     return TemplateParamsOrErr.takeError();
5345 
5346   VarTemplateDecl *ToVarTD;
5347   if (GetImportedOrCreateDecl(ToVarTD, D, Importer.getToContext(), DC, Loc,
5348                               Name, *TemplateParamsOrErr, ToTemplated))
5349     return ToVarTD;
5350 
5351   ToTemplated->setDescribedVarTemplate(ToVarTD);
5352 
5353   ToVarTD->setAccess(D->getAccess());
5354   ToVarTD->setLexicalDeclContext(LexicalDC);
5355   LexicalDC->addDeclInternal(ToVarTD);
5356 
5357   if (DTemplated->isThisDeclarationADefinition() &&
5358       !ToTemplated->isThisDeclarationADefinition()) {
5359     // FIXME: Import definition!
5360   }
5361 
5362   return ToVarTD;
5363 }
5364 
5365 ExpectedDecl ASTNodeImporter::VisitVarTemplateSpecializationDecl(
5366     VarTemplateSpecializationDecl *D) {
5367   // If this record has a definition in the translation unit we're coming from,
5368   // but this particular declaration is not that definition, import the
5369   // definition and map to that.
5370   VarDecl *Definition = D->getDefinition();
5371   if (Definition && Definition != D) {
5372     if (ExpectedDecl ImportedDefOrErr = import(Definition))
5373       return Importer.MapImported(D, *ImportedDefOrErr);
5374     else
5375       return ImportedDefOrErr.takeError();
5376   }
5377 
5378   VarTemplateDecl *VarTemplate;
5379   if (Error Err = importInto(VarTemplate, D->getSpecializedTemplate()))
5380     return std::move(Err);
5381 
5382   // Import the context of this declaration.
5383   DeclContext *DC, *LexicalDC;
5384   if (Error Err = ImportDeclContext(D, DC, LexicalDC))
5385     return std::move(Err);
5386 
5387   // Import the location of this declaration.
5388   ExpectedSLoc BeginLocOrErr = import(D->getBeginLoc());
5389   if (!BeginLocOrErr)
5390     return BeginLocOrErr.takeError();
5391 
5392   auto IdLocOrErr = import(D->getLocation());
5393   if (!IdLocOrErr)
5394     return IdLocOrErr.takeError();
5395 
5396   // Import template arguments.
5397   SmallVector<TemplateArgument, 2> TemplateArgs;
5398   if (Error Err = ImportTemplateArguments(
5399       D->getTemplateArgs().data(), D->getTemplateArgs().size(), TemplateArgs))
5400     return std::move(Err);
5401 
5402   // Try to find an existing specialization with these template arguments.
5403   void *InsertPos = nullptr;
5404   VarTemplateSpecializationDecl *D2 = VarTemplate->findSpecialization(
5405       TemplateArgs, InsertPos);
5406   if (D2) {
5407     // We already have a variable template specialization with these template
5408     // arguments.
5409 
5410     // FIXME: Check for specialization vs. instantiation errors.
5411 
5412     if (VarDecl *FoundDef = D2->getDefinition()) {
5413       if (!D->isThisDeclarationADefinition() ||
5414           IsStructuralMatch(D, FoundDef)) {
5415         // The record types structurally match, or the "from" translation
5416         // unit only had a forward declaration anyway; call it the same
5417         // variable.
5418         return Importer.MapImported(D, FoundDef);
5419       }
5420     }
5421   } else {
5422     // Import the type.
5423     QualType T;
5424     if (Error Err = importInto(T, D->getType()))
5425       return std::move(Err);
5426 
5427     auto TInfoOrErr = import(D->getTypeSourceInfo());
5428     if (!TInfoOrErr)
5429       return TInfoOrErr.takeError();
5430 
5431     TemplateArgumentListInfo ToTAInfo;
5432     if (Error Err = ImportTemplateArgumentListInfo(
5433         D->getTemplateArgsInfo(), ToTAInfo))
5434       return std::move(Err);
5435 
5436     using PartVarSpecDecl = VarTemplatePartialSpecializationDecl;
5437     // Create a new specialization.
5438     if (auto *FromPartial = dyn_cast<PartVarSpecDecl>(D)) {
5439       // Import TemplateArgumentListInfo
5440       TemplateArgumentListInfo ArgInfos;
5441       const auto *FromTAArgsAsWritten = FromPartial->getTemplateArgsAsWritten();
5442       // NOTE: FromTAArgsAsWritten and template parameter list are non-null.
5443       if (Error Err = ImportTemplateArgumentListInfo(
5444           *FromTAArgsAsWritten, ArgInfos))
5445         return std::move(Err);
5446 
5447       auto ToTPListOrErr = ImportTemplateParameterList(
5448           FromPartial->getTemplateParameters());
5449       if (!ToTPListOrErr)
5450         return ToTPListOrErr.takeError();
5451 
5452       PartVarSpecDecl *ToPartial;
5453       if (GetImportedOrCreateDecl(ToPartial, D, Importer.getToContext(), DC,
5454                                   *BeginLocOrErr, *IdLocOrErr, *ToTPListOrErr,
5455                                   VarTemplate, T, *TInfoOrErr,
5456                                   D->getStorageClass(), TemplateArgs, ArgInfos))
5457         return ToPartial;
5458 
5459       if (Expected<PartVarSpecDecl *> ToInstOrErr = import(
5460           FromPartial->getInstantiatedFromMember()))
5461         ToPartial->setInstantiatedFromMember(*ToInstOrErr);
5462       else
5463         return ToInstOrErr.takeError();
5464 
5465       if (FromPartial->isMemberSpecialization())
5466         ToPartial->setMemberSpecialization();
5467 
5468       D2 = ToPartial;
5469 
5470     } else { // Full specialization
5471       if (GetImportedOrCreateDecl(D2, D, Importer.getToContext(), DC,
5472                                   *BeginLocOrErr, *IdLocOrErr, VarTemplate,
5473                                   T, *TInfoOrErr,
5474                                   D->getStorageClass(), TemplateArgs))
5475         return D2;
5476     }
5477 
5478     if (D->getPointOfInstantiation().isValid()) {
5479       if (ExpectedSLoc POIOrErr = import(D->getPointOfInstantiation()))
5480         D2->setPointOfInstantiation(*POIOrErr);
5481       else
5482         return POIOrErr.takeError();
5483     }
5484 
5485     D2->setSpecializationKind(D->getSpecializationKind());
5486     D2->setTemplateArgsInfo(ToTAInfo);
5487 
5488     // Add this specialization to the class template.
5489     VarTemplate->AddSpecialization(D2, InsertPos);
5490 
5491     // Import the qualifier, if any.
5492     if (auto LocOrErr = import(D->getQualifierLoc()))
5493       D2->setQualifierInfo(*LocOrErr);
5494     else
5495       return LocOrErr.takeError();
5496 
5497     if (D->isConstexpr())
5498       D2->setConstexpr(true);
5499 
5500     // Add the specialization to this context.
5501     D2->setLexicalDeclContext(LexicalDC);
5502     LexicalDC->addDeclInternal(D2);
5503 
5504     D2->setAccess(D->getAccess());
5505   }
5506 
5507   if (Error Err = ImportInitializer(D, D2))
5508     return std::move(Err);
5509 
5510   return D2;
5511 }
5512 
5513 ExpectedDecl
5514 ASTNodeImporter::VisitFunctionTemplateDecl(FunctionTemplateDecl *D) {
5515   DeclContext *DC, *LexicalDC;
5516   DeclarationName Name;
5517   SourceLocation Loc;
5518   NamedDecl *ToD;
5519 
5520   if (Error Err = ImportDeclParts(D, DC, LexicalDC, Name, ToD, Loc))
5521     return std::move(Err);
5522 
5523   if (ToD)
5524     return ToD;
5525 
5526   // Try to find a function in our own ("to") context with the same name, same
5527   // type, and in the same context as the function we're importing.
5528   if (!LexicalDC->isFunctionOrMethod()) {
5529     unsigned IDNS = Decl::IDNS_Ordinary;
5530     SmallVector<NamedDecl *, 2> FoundDecls;
5531     DC->getRedeclContext()->localUncachedLookup(Name, FoundDecls);
5532     for (auto *FoundDecl : FoundDecls) {
5533       if (!FoundDecl->isInIdentifierNamespace(IDNS))
5534         continue;
5535 
5536       if (auto *FoundFunction =
5537           dyn_cast<FunctionTemplateDecl>(FoundDecl)) {
5538         if (FoundFunction->hasExternalFormalLinkage() &&
5539             D->hasExternalFormalLinkage()) {
5540           if (IsStructuralMatch(D, FoundFunction)) {
5541             Importer.MapImported(D, FoundFunction);
5542             // FIXME: Actually try to merge the body and other attributes.
5543             return FoundFunction;
5544           }
5545         }
5546       }
5547       // TODO: handle conflicting names
5548     }
5549   }
5550 
5551   auto ParamsOrErr = ImportTemplateParameterList(
5552       D->getTemplateParameters());
5553   if (!ParamsOrErr)
5554     return ParamsOrErr.takeError();
5555 
5556   FunctionDecl *TemplatedFD;
5557   if (Error Err = importInto(TemplatedFD, D->getTemplatedDecl()))
5558     return std::move(Err);
5559 
5560   FunctionTemplateDecl *ToFunc;
5561   if (GetImportedOrCreateDecl(ToFunc, D, Importer.getToContext(), DC, Loc, Name,
5562                               *ParamsOrErr, TemplatedFD))
5563     return ToFunc;
5564 
5565   TemplatedFD->setDescribedFunctionTemplate(ToFunc);
5566   ToFunc->setAccess(D->getAccess());
5567   ToFunc->setLexicalDeclContext(LexicalDC);
5568 
5569   LexicalDC->addDeclInternal(ToFunc);
5570   return ToFunc;
5571 }
5572 
5573 //----------------------------------------------------------------------------
5574 // Import Statements
5575 //----------------------------------------------------------------------------
5576 
5577 ExpectedStmt ASTNodeImporter::VisitStmt(Stmt *S) {
5578   Importer.FromDiag(S->getBeginLoc(), diag::err_unsupported_ast_node)
5579       << S->getStmtClassName();
5580   return make_error<ImportError>(ImportError::UnsupportedConstruct);
5581 }
5582 
5583 
5584 ExpectedStmt ASTNodeImporter::VisitGCCAsmStmt(GCCAsmStmt *S) {
5585   SmallVector<IdentifierInfo *, 4> Names;
5586   for (unsigned I = 0, E = S->getNumOutputs(); I != E; I++) {
5587     IdentifierInfo *ToII = Importer.Import(S->getOutputIdentifier(I));
5588     // ToII is nullptr when no symbolic name is given for output operand
5589     // see ParseStmtAsm::ParseAsmOperandsOpt
5590     Names.push_back(ToII);
5591   }
5592 
5593   for (unsigned I = 0, E = S->getNumInputs(); I != E; I++) {
5594     IdentifierInfo *ToII = Importer.Import(S->getInputIdentifier(I));
5595     // ToII is nullptr when no symbolic name is given for input operand
5596     // see ParseStmtAsm::ParseAsmOperandsOpt
5597     Names.push_back(ToII);
5598   }
5599 
5600   SmallVector<StringLiteral *, 4> Clobbers;
5601   for (unsigned I = 0, E = S->getNumClobbers(); I != E; I++) {
5602     if (auto ClobberOrErr = import(S->getClobberStringLiteral(I)))
5603       Clobbers.push_back(*ClobberOrErr);
5604     else
5605       return ClobberOrErr.takeError();
5606 
5607   }
5608 
5609   SmallVector<StringLiteral *, 4> Constraints;
5610   for (unsigned I = 0, E = S->getNumOutputs(); I != E; I++) {
5611     if (auto OutputOrErr = import(S->getOutputConstraintLiteral(I)))
5612       Constraints.push_back(*OutputOrErr);
5613     else
5614       return OutputOrErr.takeError();
5615   }
5616 
5617   for (unsigned I = 0, E = S->getNumInputs(); I != E; I++) {
5618     if (auto InputOrErr = import(S->getInputConstraintLiteral(I)))
5619       Constraints.push_back(*InputOrErr);
5620     else
5621       return InputOrErr.takeError();
5622   }
5623 
5624   SmallVector<Expr *, 4> Exprs(S->getNumOutputs() + S->getNumInputs());
5625   if (Error Err = ImportContainerChecked(S->outputs(), Exprs))
5626     return std::move(Err);
5627 
5628   if (Error Err = ImportArrayChecked(
5629       S->inputs(), Exprs.begin() + S->getNumOutputs()))
5630     return std::move(Err);
5631 
5632   ExpectedSLoc AsmLocOrErr = import(S->getAsmLoc());
5633   if (!AsmLocOrErr)
5634     return AsmLocOrErr.takeError();
5635   auto AsmStrOrErr = import(S->getAsmString());
5636   if (!AsmStrOrErr)
5637     return AsmStrOrErr.takeError();
5638   ExpectedSLoc RParenLocOrErr = import(S->getRParenLoc());
5639   if (!RParenLocOrErr)
5640     return RParenLocOrErr.takeError();
5641 
5642   return new (Importer.getToContext()) GCCAsmStmt(
5643       Importer.getToContext(),
5644       *AsmLocOrErr,
5645       S->isSimple(),
5646       S->isVolatile(),
5647       S->getNumOutputs(),
5648       S->getNumInputs(),
5649       Names.data(),
5650       Constraints.data(),
5651       Exprs.data(),
5652       *AsmStrOrErr,
5653       S->getNumClobbers(),
5654       Clobbers.data(),
5655       *RParenLocOrErr);
5656 }
5657 
5658 ExpectedStmt ASTNodeImporter::VisitDeclStmt(DeclStmt *S) {
5659   auto Imp = importSeq(S->getDeclGroup(), S->getBeginLoc(), S->getEndLoc());
5660   if (!Imp)
5661     return Imp.takeError();
5662 
5663   DeclGroupRef ToDG;
5664   SourceLocation ToBeginLoc, ToEndLoc;
5665   std::tie(ToDG, ToBeginLoc, ToEndLoc) = *Imp;
5666 
5667   return new (Importer.getToContext()) DeclStmt(ToDG, ToBeginLoc, ToEndLoc);
5668 }
5669 
5670 ExpectedStmt ASTNodeImporter::VisitNullStmt(NullStmt *S) {
5671   ExpectedSLoc ToSemiLocOrErr = import(S->getSemiLoc());
5672   if (!ToSemiLocOrErr)
5673     return ToSemiLocOrErr.takeError();
5674   return new (Importer.getToContext()) NullStmt(
5675       *ToSemiLocOrErr, S->hasLeadingEmptyMacro());
5676 }
5677 
5678 ExpectedStmt ASTNodeImporter::VisitCompoundStmt(CompoundStmt *S) {
5679   SmallVector<Stmt *, 8> ToStmts(S->size());
5680 
5681   if (Error Err = ImportContainerChecked(S->body(), ToStmts))
5682     return std::move(Err);
5683 
5684   ExpectedSLoc ToLBracLocOrErr = import(S->getLBracLoc());
5685   if (!ToLBracLocOrErr)
5686     return ToLBracLocOrErr.takeError();
5687 
5688   ExpectedSLoc ToRBracLocOrErr = import(S->getRBracLoc());
5689   if (!ToRBracLocOrErr)
5690     return ToRBracLocOrErr.takeError();
5691 
5692   return CompoundStmt::Create(
5693       Importer.getToContext(), ToStmts,
5694       *ToLBracLocOrErr, *ToRBracLocOrErr);
5695 }
5696 
5697 ExpectedStmt ASTNodeImporter::VisitCaseStmt(CaseStmt *S) {
5698   auto Imp = importSeq(
5699       S->getLHS(), S->getRHS(), S->getSubStmt(), S->getCaseLoc(),
5700       S->getEllipsisLoc(), S->getColonLoc());
5701   if (!Imp)
5702     return Imp.takeError();
5703 
5704   Expr *ToLHS, *ToRHS;
5705   Stmt *ToSubStmt;
5706   SourceLocation ToCaseLoc, ToEllipsisLoc, ToColonLoc;
5707   std::tie(ToLHS, ToRHS, ToSubStmt, ToCaseLoc, ToEllipsisLoc, ToColonLoc) =
5708       *Imp;
5709 
5710   auto *ToStmt = CaseStmt::Create(Importer.getToContext(), ToLHS, ToRHS,
5711                                   ToCaseLoc, ToEllipsisLoc, ToColonLoc);
5712   ToStmt->setSubStmt(ToSubStmt);
5713 
5714   return ToStmt;
5715 }
5716 
5717 ExpectedStmt ASTNodeImporter::VisitDefaultStmt(DefaultStmt *S) {
5718   auto Imp = importSeq(S->getDefaultLoc(), S->getColonLoc(), S->getSubStmt());
5719   if (!Imp)
5720     return Imp.takeError();
5721 
5722   SourceLocation ToDefaultLoc, ToColonLoc;
5723   Stmt *ToSubStmt;
5724   std::tie(ToDefaultLoc, ToColonLoc, ToSubStmt) = *Imp;
5725 
5726   return new (Importer.getToContext()) DefaultStmt(
5727     ToDefaultLoc, ToColonLoc, ToSubStmt);
5728 }
5729 
5730 ExpectedStmt ASTNodeImporter::VisitLabelStmt(LabelStmt *S) {
5731   auto Imp = importSeq(S->getIdentLoc(), S->getDecl(), S->getSubStmt());
5732   if (!Imp)
5733     return Imp.takeError();
5734 
5735   SourceLocation ToIdentLoc;
5736   LabelDecl *ToLabelDecl;
5737   Stmt *ToSubStmt;
5738   std::tie(ToIdentLoc, ToLabelDecl, ToSubStmt) = *Imp;
5739 
5740   return new (Importer.getToContext()) LabelStmt(
5741       ToIdentLoc, ToLabelDecl, ToSubStmt);
5742 }
5743 
5744 ExpectedStmt ASTNodeImporter::VisitAttributedStmt(AttributedStmt *S) {
5745   ExpectedSLoc ToAttrLocOrErr = import(S->getAttrLoc());
5746   if (!ToAttrLocOrErr)
5747     return ToAttrLocOrErr.takeError();
5748   ArrayRef<const Attr*> FromAttrs(S->getAttrs());
5749   SmallVector<const Attr *, 1> ToAttrs(FromAttrs.size());
5750   if (Error Err = ImportContainerChecked(FromAttrs, ToAttrs))
5751     return std::move(Err);
5752   ExpectedStmt ToSubStmtOrErr = import(S->getSubStmt());
5753   if (!ToSubStmtOrErr)
5754     return ToSubStmtOrErr.takeError();
5755 
5756   return AttributedStmt::Create(
5757       Importer.getToContext(), *ToAttrLocOrErr, ToAttrs, *ToSubStmtOrErr);
5758 }
5759 
5760 ExpectedStmt ASTNodeImporter::VisitIfStmt(IfStmt *S) {
5761   auto Imp = importSeq(
5762       S->getIfLoc(), S->getInit(), S->getConditionVariable(), S->getCond(),
5763       S->getThen(), S->getElseLoc(), S->getElse());
5764   if (!Imp)
5765     return Imp.takeError();
5766 
5767   SourceLocation ToIfLoc, ToElseLoc;
5768   Stmt *ToInit, *ToThen, *ToElse;
5769   VarDecl *ToConditionVariable;
5770   Expr *ToCond;
5771   std::tie(
5772       ToIfLoc, ToInit, ToConditionVariable, ToCond, ToThen, ToElseLoc, ToElse) =
5773           *Imp;
5774 
5775   return IfStmt::Create(Importer.getToContext(), ToIfLoc, S->isConstexpr(),
5776                         ToInit, ToConditionVariable, ToCond, ToThen, ToElseLoc,
5777                         ToElse);
5778 }
5779 
5780 ExpectedStmt ASTNodeImporter::VisitSwitchStmt(SwitchStmt *S) {
5781   auto Imp = importSeq(
5782       S->getInit(), S->getConditionVariable(), S->getCond(),
5783       S->getBody(), S->getSwitchLoc());
5784   if (!Imp)
5785     return Imp.takeError();
5786 
5787   Stmt *ToInit, *ToBody;
5788   VarDecl *ToConditionVariable;
5789   Expr *ToCond;
5790   SourceLocation ToSwitchLoc;
5791   std::tie(ToInit, ToConditionVariable, ToCond, ToBody, ToSwitchLoc) = *Imp;
5792 
5793   auto *ToStmt = SwitchStmt::Create(Importer.getToContext(), ToInit,
5794                                     ToConditionVariable, ToCond);
5795   ToStmt->setBody(ToBody);
5796   ToStmt->setSwitchLoc(ToSwitchLoc);
5797 
5798   // Now we have to re-chain the cases.
5799   SwitchCase *LastChainedSwitchCase = nullptr;
5800   for (SwitchCase *SC = S->getSwitchCaseList(); SC != nullptr;
5801        SC = SC->getNextSwitchCase()) {
5802     Expected<SwitchCase *> ToSCOrErr = import(SC);
5803     if (!ToSCOrErr)
5804       return ToSCOrErr.takeError();
5805     if (LastChainedSwitchCase)
5806       LastChainedSwitchCase->setNextSwitchCase(*ToSCOrErr);
5807     else
5808       ToStmt->setSwitchCaseList(*ToSCOrErr);
5809     LastChainedSwitchCase = *ToSCOrErr;
5810   }
5811 
5812   return ToStmt;
5813 }
5814 
5815 ExpectedStmt ASTNodeImporter::VisitWhileStmt(WhileStmt *S) {
5816   auto Imp = importSeq(
5817       S->getConditionVariable(), S->getCond(), S->getBody(), S->getWhileLoc());
5818   if (!Imp)
5819     return Imp.takeError();
5820 
5821   VarDecl *ToConditionVariable;
5822   Expr *ToCond;
5823   Stmt *ToBody;
5824   SourceLocation ToWhileLoc;
5825   std::tie(ToConditionVariable, ToCond, ToBody, ToWhileLoc) = *Imp;
5826 
5827   return WhileStmt::Create(Importer.getToContext(), ToConditionVariable, ToCond,
5828                            ToBody, ToWhileLoc);
5829 }
5830 
5831 ExpectedStmt ASTNodeImporter::VisitDoStmt(DoStmt *S) {
5832   auto Imp = importSeq(
5833       S->getBody(), S->getCond(), S->getDoLoc(), S->getWhileLoc(),
5834       S->getRParenLoc());
5835   if (!Imp)
5836     return Imp.takeError();
5837 
5838   Stmt *ToBody;
5839   Expr *ToCond;
5840   SourceLocation ToDoLoc, ToWhileLoc, ToRParenLoc;
5841   std::tie(ToBody, ToCond, ToDoLoc, ToWhileLoc, ToRParenLoc) = *Imp;
5842 
5843   return new (Importer.getToContext()) DoStmt(
5844       ToBody, ToCond, ToDoLoc, ToWhileLoc, ToRParenLoc);
5845 }
5846 
5847 ExpectedStmt ASTNodeImporter::VisitForStmt(ForStmt *S) {
5848   auto Imp = importSeq(
5849       S->getInit(), S->getCond(), S->getConditionVariable(), S->getInc(),
5850       S->getBody(), S->getForLoc(), S->getLParenLoc(), S->getRParenLoc());
5851   if (!Imp)
5852     return Imp.takeError();
5853 
5854   Stmt *ToInit;
5855   Expr *ToCond, *ToInc;
5856   VarDecl *ToConditionVariable;
5857   Stmt *ToBody;
5858   SourceLocation ToForLoc, ToLParenLoc, ToRParenLoc;
5859   std::tie(
5860       ToInit, ToCond, ToConditionVariable,  ToInc, ToBody, ToForLoc,
5861       ToLParenLoc, ToRParenLoc) = *Imp;
5862 
5863   return new (Importer.getToContext()) ForStmt(
5864       Importer.getToContext(),
5865       ToInit, ToCond, ToConditionVariable, ToInc, ToBody, ToForLoc, ToLParenLoc,
5866       ToRParenLoc);
5867 }
5868 
5869 ExpectedStmt ASTNodeImporter::VisitGotoStmt(GotoStmt *S) {
5870   auto Imp = importSeq(S->getLabel(), S->getGotoLoc(), S->getLabelLoc());
5871   if (!Imp)
5872     return Imp.takeError();
5873 
5874   LabelDecl *ToLabel;
5875   SourceLocation ToGotoLoc, ToLabelLoc;
5876   std::tie(ToLabel, ToGotoLoc, ToLabelLoc) = *Imp;
5877 
5878   return new (Importer.getToContext()) GotoStmt(
5879       ToLabel, ToGotoLoc, ToLabelLoc);
5880 }
5881 
5882 ExpectedStmt ASTNodeImporter::VisitIndirectGotoStmt(IndirectGotoStmt *S) {
5883   auto Imp = importSeq(S->getGotoLoc(), S->getStarLoc(), S->getTarget());
5884   if (!Imp)
5885     return Imp.takeError();
5886 
5887   SourceLocation ToGotoLoc, ToStarLoc;
5888   Expr *ToTarget;
5889   std::tie(ToGotoLoc, ToStarLoc, ToTarget) = *Imp;
5890 
5891   return new (Importer.getToContext()) IndirectGotoStmt(
5892       ToGotoLoc, ToStarLoc, ToTarget);
5893 }
5894 
5895 ExpectedStmt ASTNodeImporter::VisitContinueStmt(ContinueStmt *S) {
5896   ExpectedSLoc ToContinueLocOrErr = import(S->getContinueLoc());
5897   if (!ToContinueLocOrErr)
5898     return ToContinueLocOrErr.takeError();
5899   return new (Importer.getToContext()) ContinueStmt(*ToContinueLocOrErr);
5900 }
5901 
5902 ExpectedStmt ASTNodeImporter::VisitBreakStmt(BreakStmt *S) {
5903   auto ToBreakLocOrErr = import(S->getBreakLoc());
5904   if (!ToBreakLocOrErr)
5905     return ToBreakLocOrErr.takeError();
5906   return new (Importer.getToContext()) BreakStmt(*ToBreakLocOrErr);
5907 }
5908 
5909 ExpectedStmt ASTNodeImporter::VisitReturnStmt(ReturnStmt *S) {
5910   auto Imp = importSeq(
5911       S->getReturnLoc(), S->getRetValue(), S->getNRVOCandidate());
5912   if (!Imp)
5913     return Imp.takeError();
5914 
5915   SourceLocation ToReturnLoc;
5916   Expr *ToRetValue;
5917   const VarDecl *ToNRVOCandidate;
5918   std::tie(ToReturnLoc, ToRetValue, ToNRVOCandidate) = *Imp;
5919 
5920   return ReturnStmt::Create(Importer.getToContext(), ToReturnLoc, ToRetValue,
5921                             ToNRVOCandidate);
5922 }
5923 
5924 ExpectedStmt ASTNodeImporter::VisitCXXCatchStmt(CXXCatchStmt *S) {
5925   auto Imp = importSeq(
5926       S->getCatchLoc(), S->getExceptionDecl(), S->getHandlerBlock());
5927   if (!Imp)
5928     return Imp.takeError();
5929 
5930   SourceLocation ToCatchLoc;
5931   VarDecl *ToExceptionDecl;
5932   Stmt *ToHandlerBlock;
5933   std::tie(ToCatchLoc, ToExceptionDecl, ToHandlerBlock) = *Imp;
5934 
5935   return new (Importer.getToContext()) CXXCatchStmt (
5936       ToCatchLoc, ToExceptionDecl, ToHandlerBlock);
5937 }
5938 
5939 ExpectedStmt ASTNodeImporter::VisitCXXTryStmt(CXXTryStmt *S) {
5940   ExpectedSLoc ToTryLocOrErr = import(S->getTryLoc());
5941   if (!ToTryLocOrErr)
5942     return ToTryLocOrErr.takeError();
5943 
5944   ExpectedStmt ToTryBlockOrErr = import(S->getTryBlock());
5945   if (!ToTryBlockOrErr)
5946     return ToTryBlockOrErr.takeError();
5947 
5948   SmallVector<Stmt *, 1> ToHandlers(S->getNumHandlers());
5949   for (unsigned HI = 0, HE = S->getNumHandlers(); HI != HE; ++HI) {
5950     CXXCatchStmt *FromHandler = S->getHandler(HI);
5951     if (auto ToHandlerOrErr = import(FromHandler))
5952       ToHandlers[HI] = *ToHandlerOrErr;
5953     else
5954       return ToHandlerOrErr.takeError();
5955   }
5956 
5957   return CXXTryStmt::Create(
5958       Importer.getToContext(), *ToTryLocOrErr,*ToTryBlockOrErr, ToHandlers);
5959 }
5960 
5961 ExpectedStmt ASTNodeImporter::VisitCXXForRangeStmt(CXXForRangeStmt *S) {
5962   auto Imp1 = importSeq(
5963       S->getInit(), S->getRangeStmt(), S->getBeginStmt(), S->getEndStmt(),
5964       S->getCond(), S->getInc(), S->getLoopVarStmt(), S->getBody());
5965   if (!Imp1)
5966     return Imp1.takeError();
5967   auto Imp2 = importSeq(
5968       S->getForLoc(), S->getCoawaitLoc(), S->getColonLoc(), S->getRParenLoc());
5969   if (!Imp2)
5970     return Imp2.takeError();
5971 
5972   DeclStmt *ToRangeStmt, *ToBeginStmt, *ToEndStmt, *ToLoopVarStmt;
5973   Expr *ToCond, *ToInc;
5974   Stmt *ToInit, *ToBody;
5975   std::tie(
5976       ToInit, ToRangeStmt, ToBeginStmt, ToEndStmt, ToCond, ToInc, ToLoopVarStmt,
5977       ToBody) = *Imp1;
5978   SourceLocation ToForLoc, ToCoawaitLoc, ToColonLoc, ToRParenLoc;
5979   std::tie(ToForLoc, ToCoawaitLoc, ToColonLoc, ToRParenLoc) = *Imp2;
5980 
5981   return new (Importer.getToContext()) CXXForRangeStmt(
5982       ToInit, ToRangeStmt, ToBeginStmt, ToEndStmt, ToCond, ToInc, ToLoopVarStmt,
5983       ToBody, ToForLoc, ToCoawaitLoc, ToColonLoc, ToRParenLoc);
5984 }
5985 
5986 ExpectedStmt
5987 ASTNodeImporter::VisitObjCForCollectionStmt(ObjCForCollectionStmt *S) {
5988   auto Imp = importSeq(
5989       S->getElement(), S->getCollection(), S->getBody(),
5990       S->getForLoc(), S->getRParenLoc());
5991   if (!Imp)
5992     return Imp.takeError();
5993 
5994   Stmt *ToElement, *ToBody;
5995   Expr *ToCollection;
5996   SourceLocation ToForLoc, ToRParenLoc;
5997   std::tie(ToElement, ToCollection, ToBody, ToForLoc, ToRParenLoc) = *Imp;
5998 
5999   return new (Importer.getToContext()) ObjCForCollectionStmt(ToElement,
6000                                                              ToCollection,
6001                                                              ToBody,
6002                                                              ToForLoc,
6003                                                              ToRParenLoc);
6004 }
6005 
6006 ExpectedStmt ASTNodeImporter::VisitObjCAtCatchStmt(ObjCAtCatchStmt *S) {
6007   auto Imp = importSeq(
6008       S->getAtCatchLoc(), S->getRParenLoc(), S->getCatchParamDecl(),
6009       S->getCatchBody());
6010   if (!Imp)
6011     return Imp.takeError();
6012 
6013   SourceLocation ToAtCatchLoc, ToRParenLoc;
6014   VarDecl *ToCatchParamDecl;
6015   Stmt *ToCatchBody;
6016   std::tie(ToAtCatchLoc, ToRParenLoc, ToCatchParamDecl, ToCatchBody) = *Imp;
6017 
6018   return new (Importer.getToContext()) ObjCAtCatchStmt (
6019       ToAtCatchLoc, ToRParenLoc, ToCatchParamDecl, ToCatchBody);
6020 }
6021 
6022 ExpectedStmt ASTNodeImporter::VisitObjCAtFinallyStmt(ObjCAtFinallyStmt *S) {
6023   ExpectedSLoc ToAtFinallyLocOrErr = import(S->getAtFinallyLoc());
6024   if (!ToAtFinallyLocOrErr)
6025     return ToAtFinallyLocOrErr.takeError();
6026   ExpectedStmt ToAtFinallyStmtOrErr = import(S->getFinallyBody());
6027   if (!ToAtFinallyStmtOrErr)
6028     return ToAtFinallyStmtOrErr.takeError();
6029   return new (Importer.getToContext()) ObjCAtFinallyStmt(*ToAtFinallyLocOrErr,
6030                                                          *ToAtFinallyStmtOrErr);
6031 }
6032 
6033 ExpectedStmt ASTNodeImporter::VisitObjCAtTryStmt(ObjCAtTryStmt *S) {
6034   auto Imp = importSeq(
6035       S->getAtTryLoc(), S->getTryBody(), S->getFinallyStmt());
6036   if (!Imp)
6037     return Imp.takeError();
6038 
6039   SourceLocation ToAtTryLoc;
6040   Stmt *ToTryBody, *ToFinallyStmt;
6041   std::tie(ToAtTryLoc, ToTryBody, ToFinallyStmt) = *Imp;
6042 
6043   SmallVector<Stmt *, 1> ToCatchStmts(S->getNumCatchStmts());
6044   for (unsigned CI = 0, CE = S->getNumCatchStmts(); CI != CE; ++CI) {
6045     ObjCAtCatchStmt *FromCatchStmt = S->getCatchStmt(CI);
6046     if (ExpectedStmt ToCatchStmtOrErr = import(FromCatchStmt))
6047       ToCatchStmts[CI] = *ToCatchStmtOrErr;
6048     else
6049       return ToCatchStmtOrErr.takeError();
6050   }
6051 
6052   return ObjCAtTryStmt::Create(Importer.getToContext(),
6053                                ToAtTryLoc, ToTryBody,
6054                                ToCatchStmts.begin(), ToCatchStmts.size(),
6055                                ToFinallyStmt);
6056 }
6057 
6058 ExpectedStmt ASTNodeImporter::VisitObjCAtSynchronizedStmt
6059   (ObjCAtSynchronizedStmt *S) {
6060   auto Imp = importSeq(
6061       S->getAtSynchronizedLoc(), S->getSynchExpr(), S->getSynchBody());
6062   if (!Imp)
6063     return Imp.takeError();
6064 
6065   SourceLocation ToAtSynchronizedLoc;
6066   Expr *ToSynchExpr;
6067   Stmt *ToSynchBody;
6068   std::tie(ToAtSynchronizedLoc, ToSynchExpr, ToSynchBody) = *Imp;
6069 
6070   return new (Importer.getToContext()) ObjCAtSynchronizedStmt(
6071     ToAtSynchronizedLoc, ToSynchExpr, ToSynchBody);
6072 }
6073 
6074 ExpectedStmt ASTNodeImporter::VisitObjCAtThrowStmt(ObjCAtThrowStmt *S) {
6075   ExpectedSLoc ToThrowLocOrErr = import(S->getThrowLoc());
6076   if (!ToThrowLocOrErr)
6077     return ToThrowLocOrErr.takeError();
6078   ExpectedExpr ToThrowExprOrErr = import(S->getThrowExpr());
6079   if (!ToThrowExprOrErr)
6080     return ToThrowExprOrErr.takeError();
6081   return new (Importer.getToContext()) ObjCAtThrowStmt(
6082       *ToThrowLocOrErr, *ToThrowExprOrErr);
6083 }
6084 
6085 ExpectedStmt ASTNodeImporter::VisitObjCAutoreleasePoolStmt(
6086     ObjCAutoreleasePoolStmt *S) {
6087   ExpectedSLoc ToAtLocOrErr = import(S->getAtLoc());
6088   if (!ToAtLocOrErr)
6089     return ToAtLocOrErr.takeError();
6090   ExpectedStmt ToSubStmtOrErr = import(S->getSubStmt());
6091   if (!ToSubStmtOrErr)
6092     return ToSubStmtOrErr.takeError();
6093   return new (Importer.getToContext()) ObjCAutoreleasePoolStmt(*ToAtLocOrErr,
6094                                                                *ToSubStmtOrErr);
6095 }
6096 
6097 //----------------------------------------------------------------------------
6098 // Import Expressions
6099 //----------------------------------------------------------------------------
6100 ExpectedStmt ASTNodeImporter::VisitExpr(Expr *E) {
6101   Importer.FromDiag(E->getBeginLoc(), diag::err_unsupported_ast_node)
6102       << E->getStmtClassName();
6103   return make_error<ImportError>(ImportError::UnsupportedConstruct);
6104 }
6105 
6106 ExpectedStmt ASTNodeImporter::VisitVAArgExpr(VAArgExpr *E) {
6107   auto Imp = importSeq(
6108       E->getBuiltinLoc(), E->getSubExpr(), E->getWrittenTypeInfo(),
6109       E->getRParenLoc(), E->getType());
6110   if (!Imp)
6111     return Imp.takeError();
6112 
6113   SourceLocation ToBuiltinLoc, ToRParenLoc;
6114   Expr *ToSubExpr;
6115   TypeSourceInfo *ToWrittenTypeInfo;
6116   QualType ToType;
6117   std::tie(ToBuiltinLoc, ToSubExpr, ToWrittenTypeInfo, ToRParenLoc, ToType) =
6118       *Imp;
6119 
6120   return new (Importer.getToContext()) VAArgExpr(
6121       ToBuiltinLoc, ToSubExpr, ToWrittenTypeInfo, ToRParenLoc, ToType,
6122       E->isMicrosoftABI());
6123 }
6124 
6125 
6126 ExpectedStmt ASTNodeImporter::VisitGNUNullExpr(GNUNullExpr *E) {
6127   ExpectedType TypeOrErr = import(E->getType());
6128   if (!TypeOrErr)
6129     return TypeOrErr.takeError();
6130 
6131   ExpectedSLoc BeginLocOrErr = import(E->getBeginLoc());
6132   if (!BeginLocOrErr)
6133     return BeginLocOrErr.takeError();
6134 
6135   return new (Importer.getToContext()) GNUNullExpr(*TypeOrErr, *BeginLocOrErr);
6136 }
6137 
6138 ExpectedStmt ASTNodeImporter::VisitPredefinedExpr(PredefinedExpr *E) {
6139   auto Imp = importSeq(
6140       E->getBeginLoc(), E->getType(), E->getFunctionName());
6141   if (!Imp)
6142     return Imp.takeError();
6143 
6144   SourceLocation ToBeginLoc;
6145   QualType ToType;
6146   StringLiteral *ToFunctionName;
6147   std::tie(ToBeginLoc, ToType, ToFunctionName) = *Imp;
6148 
6149   return PredefinedExpr::Create(Importer.getToContext(), ToBeginLoc, ToType,
6150                                 E->getIdentKind(), ToFunctionName);
6151 }
6152 
6153 ExpectedStmt ASTNodeImporter::VisitDeclRefExpr(DeclRefExpr *E) {
6154   auto Imp = importSeq(
6155       E->getQualifierLoc(), E->getTemplateKeywordLoc(), E->getDecl(),
6156       E->getLocation(), E->getType());
6157   if (!Imp)
6158     return Imp.takeError();
6159 
6160   NestedNameSpecifierLoc ToQualifierLoc;
6161   SourceLocation ToTemplateKeywordLoc, ToLocation;
6162   ValueDecl *ToDecl;
6163   QualType ToType;
6164   std::tie(ToQualifierLoc, ToTemplateKeywordLoc, ToDecl, ToLocation, ToType) =
6165       *Imp;
6166 
6167   NamedDecl *ToFoundD = nullptr;
6168   if (E->getDecl() != E->getFoundDecl()) {
6169     auto FoundDOrErr = import(E->getFoundDecl());
6170     if (!FoundDOrErr)
6171       return FoundDOrErr.takeError();
6172     ToFoundD = *FoundDOrErr;
6173   }
6174 
6175   TemplateArgumentListInfo ToTAInfo;
6176   TemplateArgumentListInfo *ToResInfo = nullptr;
6177   if (E->hasExplicitTemplateArgs()) {
6178     if (Error Err =
6179         ImportTemplateArgumentListInfo(E->template_arguments(), ToTAInfo))
6180       return std::move(Err);
6181     ToResInfo = &ToTAInfo;
6182   }
6183 
6184   auto *ToE = DeclRefExpr::Create(
6185       Importer.getToContext(), ToQualifierLoc, ToTemplateKeywordLoc, ToDecl,
6186       E->refersToEnclosingVariableOrCapture(), ToLocation, ToType,
6187       E->getValueKind(), ToFoundD, ToResInfo);
6188   if (E->hadMultipleCandidates())
6189     ToE->setHadMultipleCandidates(true);
6190   return ToE;
6191 }
6192 
6193 ExpectedStmt ASTNodeImporter::VisitImplicitValueInitExpr(ImplicitValueInitExpr *E) {
6194   ExpectedType TypeOrErr = import(E->getType());
6195   if (!TypeOrErr)
6196     return TypeOrErr.takeError();
6197 
6198   return new (Importer.getToContext()) ImplicitValueInitExpr(*TypeOrErr);
6199 }
6200 
6201 ExpectedStmt ASTNodeImporter::VisitDesignatedInitExpr(DesignatedInitExpr *E) {
6202   ExpectedExpr ToInitOrErr = import(E->getInit());
6203   if (!ToInitOrErr)
6204     return ToInitOrErr.takeError();
6205 
6206   ExpectedSLoc ToEqualOrColonLocOrErr = import(E->getEqualOrColonLoc());
6207   if (!ToEqualOrColonLocOrErr)
6208     return ToEqualOrColonLocOrErr.takeError();
6209 
6210   SmallVector<Expr *, 4> ToIndexExprs(E->getNumSubExprs() - 1);
6211   // List elements from the second, the first is Init itself
6212   for (unsigned I = 1, N = E->getNumSubExprs(); I < N; I++) {
6213     if (ExpectedExpr ToArgOrErr = import(E->getSubExpr(I)))
6214       ToIndexExprs[I - 1] = *ToArgOrErr;
6215     else
6216       return ToArgOrErr.takeError();
6217   }
6218 
6219   SmallVector<Designator, 4> ToDesignators(E->size());
6220   if (Error Err = ImportContainerChecked(E->designators(), ToDesignators))
6221     return std::move(Err);
6222 
6223   return DesignatedInitExpr::Create(
6224         Importer.getToContext(), ToDesignators,
6225         ToIndexExprs, *ToEqualOrColonLocOrErr,
6226         E->usesGNUSyntax(), *ToInitOrErr);
6227 }
6228 
6229 ExpectedStmt
6230 ASTNodeImporter::VisitCXXNullPtrLiteralExpr(CXXNullPtrLiteralExpr *E) {
6231   ExpectedType ToTypeOrErr = import(E->getType());
6232   if (!ToTypeOrErr)
6233     return ToTypeOrErr.takeError();
6234 
6235   ExpectedSLoc ToLocationOrErr = import(E->getLocation());
6236   if (!ToLocationOrErr)
6237     return ToLocationOrErr.takeError();
6238 
6239   return new (Importer.getToContext()) CXXNullPtrLiteralExpr(
6240       *ToTypeOrErr, *ToLocationOrErr);
6241 }
6242 
6243 ExpectedStmt ASTNodeImporter::VisitIntegerLiteral(IntegerLiteral *E) {
6244   ExpectedType ToTypeOrErr = import(E->getType());
6245   if (!ToTypeOrErr)
6246     return ToTypeOrErr.takeError();
6247 
6248   ExpectedSLoc ToLocationOrErr = import(E->getLocation());
6249   if (!ToLocationOrErr)
6250     return ToLocationOrErr.takeError();
6251 
6252   return IntegerLiteral::Create(
6253       Importer.getToContext(), E->getValue(), *ToTypeOrErr, *ToLocationOrErr);
6254 }
6255 
6256 
6257 ExpectedStmt ASTNodeImporter::VisitFloatingLiteral(FloatingLiteral *E) {
6258   ExpectedType ToTypeOrErr = import(E->getType());
6259   if (!ToTypeOrErr)
6260     return ToTypeOrErr.takeError();
6261 
6262   ExpectedSLoc ToLocationOrErr = import(E->getLocation());
6263   if (!ToLocationOrErr)
6264     return ToLocationOrErr.takeError();
6265 
6266   return FloatingLiteral::Create(
6267       Importer.getToContext(), E->getValue(), E->isExact(),
6268       *ToTypeOrErr, *ToLocationOrErr);
6269 }
6270 
6271 ExpectedStmt ASTNodeImporter::VisitImaginaryLiteral(ImaginaryLiteral *E) {
6272   auto ToTypeOrErr = import(E->getType());
6273   if (!ToTypeOrErr)
6274     return ToTypeOrErr.takeError();
6275 
6276   ExpectedExpr ToSubExprOrErr = import(E->getSubExpr());
6277   if (!ToSubExprOrErr)
6278     return ToSubExprOrErr.takeError();
6279 
6280   return new (Importer.getToContext()) ImaginaryLiteral(
6281       *ToSubExprOrErr, *ToTypeOrErr);
6282 }
6283 
6284 ExpectedStmt ASTNodeImporter::VisitCharacterLiteral(CharacterLiteral *E) {
6285   ExpectedType ToTypeOrErr = import(E->getType());
6286   if (!ToTypeOrErr)
6287     return ToTypeOrErr.takeError();
6288 
6289   ExpectedSLoc ToLocationOrErr = import(E->getLocation());
6290   if (!ToLocationOrErr)
6291     return ToLocationOrErr.takeError();
6292 
6293   return new (Importer.getToContext()) CharacterLiteral(
6294       E->getValue(), E->getKind(), *ToTypeOrErr, *ToLocationOrErr);
6295 }
6296 
6297 ExpectedStmt ASTNodeImporter::VisitStringLiteral(StringLiteral *E) {
6298   ExpectedType ToTypeOrErr = import(E->getType());
6299   if (!ToTypeOrErr)
6300     return ToTypeOrErr.takeError();
6301 
6302   SmallVector<SourceLocation, 4> ToLocations(E->getNumConcatenated());
6303   if (Error Err = ImportArrayChecked(
6304       E->tokloc_begin(), E->tokloc_end(), ToLocations.begin()))
6305     return std::move(Err);
6306 
6307   return StringLiteral::Create(
6308       Importer.getToContext(), E->getBytes(), E->getKind(), E->isPascal(),
6309       *ToTypeOrErr, ToLocations.data(), ToLocations.size());
6310 }
6311 
6312 ExpectedStmt ASTNodeImporter::VisitCompoundLiteralExpr(CompoundLiteralExpr *E) {
6313   auto Imp = importSeq(
6314       E->getLParenLoc(), E->getTypeSourceInfo(), E->getType(),
6315       E->getInitializer());
6316   if (!Imp)
6317     return Imp.takeError();
6318 
6319   SourceLocation ToLParenLoc;
6320   TypeSourceInfo *ToTypeSourceInfo;
6321   QualType ToType;
6322   Expr *ToInitializer;
6323   std::tie(ToLParenLoc, ToTypeSourceInfo, ToType, ToInitializer) = *Imp;
6324 
6325   return new (Importer.getToContext()) CompoundLiteralExpr(
6326         ToLParenLoc, ToTypeSourceInfo, ToType, E->getValueKind(),
6327         ToInitializer, E->isFileScope());
6328 }
6329 
6330 ExpectedStmt ASTNodeImporter::VisitAtomicExpr(AtomicExpr *E) {
6331   auto Imp = importSeq(
6332       E->getBuiltinLoc(), E->getType(), E->getRParenLoc());
6333   if (!Imp)
6334     return Imp.takeError();
6335 
6336   SourceLocation ToBuiltinLoc, ToRParenLoc;
6337   QualType ToType;
6338   std::tie(ToBuiltinLoc, ToType, ToRParenLoc) = *Imp;
6339 
6340   SmallVector<Expr *, 6> ToExprs(E->getNumSubExprs());
6341   if (Error Err = ImportArrayChecked(
6342       E->getSubExprs(), E->getSubExprs() + E->getNumSubExprs(),
6343       ToExprs.begin()))
6344     return std::move(Err);
6345 
6346   return new (Importer.getToContext()) AtomicExpr(
6347       ToBuiltinLoc, ToExprs, ToType, E->getOp(), ToRParenLoc);
6348 }
6349 
6350 ExpectedStmt ASTNodeImporter::VisitAddrLabelExpr(AddrLabelExpr *E) {
6351   auto Imp = importSeq(
6352       E->getAmpAmpLoc(), E->getLabelLoc(), E->getLabel(), E->getType());
6353   if (!Imp)
6354     return Imp.takeError();
6355 
6356   SourceLocation ToAmpAmpLoc, ToLabelLoc;
6357   LabelDecl *ToLabel;
6358   QualType ToType;
6359   std::tie(ToAmpAmpLoc, ToLabelLoc, ToLabel, ToType) = *Imp;
6360 
6361   return new (Importer.getToContext()) AddrLabelExpr(
6362       ToAmpAmpLoc, ToLabelLoc, ToLabel, ToType);
6363 }
6364 
6365 ExpectedStmt ASTNodeImporter::VisitParenExpr(ParenExpr *E) {
6366   auto Imp = importSeq(E->getLParen(), E->getRParen(), E->getSubExpr());
6367   if (!Imp)
6368     return Imp.takeError();
6369 
6370   SourceLocation ToLParen, ToRParen;
6371   Expr *ToSubExpr;
6372   std::tie(ToLParen, ToRParen, ToSubExpr) = *Imp;
6373 
6374   return new (Importer.getToContext())
6375       ParenExpr(ToLParen, ToRParen, ToSubExpr);
6376 }
6377 
6378 ExpectedStmt ASTNodeImporter::VisitParenListExpr(ParenListExpr *E) {
6379   SmallVector<Expr *, 4> ToExprs(E->getNumExprs());
6380   if (Error Err = ImportContainerChecked(E->exprs(), ToExprs))
6381     return std::move(Err);
6382 
6383   ExpectedSLoc ToLParenLocOrErr = import(E->getLParenLoc());
6384   if (!ToLParenLocOrErr)
6385     return ToLParenLocOrErr.takeError();
6386 
6387   ExpectedSLoc ToRParenLocOrErr = import(E->getRParenLoc());
6388   if (!ToRParenLocOrErr)
6389     return ToRParenLocOrErr.takeError();
6390 
6391   return new (Importer.getToContext()) ParenListExpr(
6392       Importer.getToContext(), *ToLParenLocOrErr, ToExprs, *ToRParenLocOrErr);
6393 }
6394 
6395 ExpectedStmt ASTNodeImporter::VisitStmtExpr(StmtExpr *E) {
6396   auto Imp = importSeq(
6397       E->getSubStmt(), E->getType(), E->getLParenLoc(), E->getRParenLoc());
6398   if (!Imp)
6399     return Imp.takeError();
6400 
6401   CompoundStmt *ToSubStmt;
6402   QualType ToType;
6403   SourceLocation ToLParenLoc, ToRParenLoc;
6404   std::tie(ToSubStmt, ToType, ToLParenLoc, ToRParenLoc) = *Imp;
6405 
6406   return new (Importer.getToContext()) StmtExpr(
6407       ToSubStmt, ToType, ToLParenLoc, ToRParenLoc);
6408 }
6409 
6410 ExpectedStmt ASTNodeImporter::VisitUnaryOperator(UnaryOperator *E) {
6411   auto Imp = importSeq(
6412       E->getSubExpr(), E->getType(), E->getOperatorLoc());
6413   if (!Imp)
6414     return Imp.takeError();
6415 
6416   Expr *ToSubExpr;
6417   QualType ToType;
6418   SourceLocation ToOperatorLoc;
6419   std::tie(ToSubExpr, ToType, ToOperatorLoc) = *Imp;
6420 
6421   return new (Importer.getToContext()) UnaryOperator(
6422       ToSubExpr, E->getOpcode(), ToType, E->getValueKind(), E->getObjectKind(),
6423       ToOperatorLoc, E->canOverflow());
6424 }
6425 
6426 ExpectedStmt
6427 ASTNodeImporter::VisitUnaryExprOrTypeTraitExpr(UnaryExprOrTypeTraitExpr *E) {
6428   auto Imp = importSeq(E->getType(), E->getOperatorLoc(), E->getRParenLoc());
6429   if (!Imp)
6430     return Imp.takeError();
6431 
6432   QualType ToType;
6433   SourceLocation ToOperatorLoc, ToRParenLoc;
6434   std::tie(ToType, ToOperatorLoc, ToRParenLoc) = *Imp;
6435 
6436   if (E->isArgumentType()) {
6437     Expected<TypeSourceInfo *> ToArgumentTypeInfoOrErr =
6438         import(E->getArgumentTypeInfo());
6439     if (!ToArgumentTypeInfoOrErr)
6440       return ToArgumentTypeInfoOrErr.takeError();
6441 
6442     return new (Importer.getToContext()) UnaryExprOrTypeTraitExpr(
6443         E->getKind(), *ToArgumentTypeInfoOrErr, ToType, ToOperatorLoc,
6444         ToRParenLoc);
6445   }
6446 
6447   ExpectedExpr ToArgumentExprOrErr = import(E->getArgumentExpr());
6448   if (!ToArgumentExprOrErr)
6449     return ToArgumentExprOrErr.takeError();
6450 
6451   return new (Importer.getToContext()) UnaryExprOrTypeTraitExpr(
6452       E->getKind(), *ToArgumentExprOrErr, ToType, ToOperatorLoc, ToRParenLoc);
6453 }
6454 
6455 ExpectedStmt ASTNodeImporter::VisitBinaryOperator(BinaryOperator *E) {
6456   auto Imp = importSeq(
6457       E->getLHS(), E->getRHS(), E->getType(), E->getOperatorLoc());
6458   if (!Imp)
6459     return Imp.takeError();
6460 
6461   Expr *ToLHS, *ToRHS;
6462   QualType ToType;
6463   SourceLocation  ToOperatorLoc;
6464   std::tie(ToLHS, ToRHS, ToType, ToOperatorLoc) = *Imp;
6465 
6466   return new (Importer.getToContext()) BinaryOperator(
6467       ToLHS, ToRHS, E->getOpcode(), ToType, E->getValueKind(),
6468       E->getObjectKind(), ToOperatorLoc, E->getFPFeatures());
6469 }
6470 
6471 ExpectedStmt ASTNodeImporter::VisitConditionalOperator(ConditionalOperator *E) {
6472   auto Imp = importSeq(
6473       E->getCond(), E->getQuestionLoc(), E->getLHS(), E->getColonLoc(),
6474       E->getRHS(), E->getType());
6475   if (!Imp)
6476     return Imp.takeError();
6477 
6478   Expr *ToCond, *ToLHS, *ToRHS;
6479   SourceLocation ToQuestionLoc, ToColonLoc;
6480   QualType ToType;
6481   std::tie(ToCond, ToQuestionLoc, ToLHS, ToColonLoc, ToRHS, ToType) = *Imp;
6482 
6483   return new (Importer.getToContext()) ConditionalOperator(
6484       ToCond, ToQuestionLoc, ToLHS, ToColonLoc, ToRHS, ToType,
6485       E->getValueKind(), E->getObjectKind());
6486 }
6487 
6488 ExpectedStmt ASTNodeImporter::VisitBinaryConditionalOperator(
6489     BinaryConditionalOperator *E) {
6490   auto Imp = importSeq(
6491       E->getCommon(), E->getOpaqueValue(), E->getCond(), E->getTrueExpr(),
6492       E->getFalseExpr(), E->getQuestionLoc(), E->getColonLoc(), E->getType());
6493   if (!Imp)
6494     return Imp.takeError();
6495 
6496   Expr *ToCommon, *ToCond, *ToTrueExpr, *ToFalseExpr;
6497   OpaqueValueExpr *ToOpaqueValue;
6498   SourceLocation ToQuestionLoc, ToColonLoc;
6499   QualType ToType;
6500   std::tie(
6501       ToCommon, ToOpaqueValue, ToCond, ToTrueExpr, ToFalseExpr, ToQuestionLoc,
6502       ToColonLoc, ToType) = *Imp;
6503 
6504   return new (Importer.getToContext()) BinaryConditionalOperator(
6505       ToCommon, ToOpaqueValue, ToCond, ToTrueExpr, ToFalseExpr,
6506       ToQuestionLoc, ToColonLoc, ToType, E->getValueKind(),
6507       E->getObjectKind());
6508 }
6509 
6510 ExpectedStmt ASTNodeImporter::VisitArrayTypeTraitExpr(ArrayTypeTraitExpr *E) {
6511   auto Imp = importSeq(
6512       E->getBeginLoc(), E->getQueriedTypeSourceInfo(),
6513       E->getDimensionExpression(), E->getEndLoc(), E->getType());
6514   if (!Imp)
6515     return Imp.takeError();
6516 
6517   SourceLocation ToBeginLoc, ToEndLoc;
6518   TypeSourceInfo *ToQueriedTypeSourceInfo;
6519   Expr *ToDimensionExpression;
6520   QualType ToType;
6521   std::tie(
6522       ToBeginLoc, ToQueriedTypeSourceInfo, ToDimensionExpression, ToEndLoc,
6523       ToType) = *Imp;
6524 
6525   return new (Importer.getToContext()) ArrayTypeTraitExpr(
6526       ToBeginLoc, E->getTrait(), ToQueriedTypeSourceInfo, E->getValue(),
6527       ToDimensionExpression, ToEndLoc, ToType);
6528 }
6529 
6530 ExpectedStmt ASTNodeImporter::VisitExpressionTraitExpr(ExpressionTraitExpr *E) {
6531   auto Imp = importSeq(
6532       E->getBeginLoc(), E->getQueriedExpression(), E->getEndLoc(), E->getType());
6533   if (!Imp)
6534     return Imp.takeError();
6535 
6536   SourceLocation ToBeginLoc, ToEndLoc;
6537   Expr *ToQueriedExpression;
6538   QualType ToType;
6539   std::tie(ToBeginLoc, ToQueriedExpression, ToEndLoc, ToType) = *Imp;
6540 
6541   return new (Importer.getToContext()) ExpressionTraitExpr(
6542       ToBeginLoc, E->getTrait(), ToQueriedExpression, E->getValue(),
6543       ToEndLoc, ToType);
6544 }
6545 
6546 ExpectedStmt ASTNodeImporter::VisitOpaqueValueExpr(OpaqueValueExpr *E) {
6547   auto Imp = importSeq(
6548       E->getLocation(), E->getType(), E->getSourceExpr());
6549   if (!Imp)
6550     return Imp.takeError();
6551 
6552   SourceLocation ToLocation;
6553   QualType ToType;
6554   Expr *ToSourceExpr;
6555   std::tie(ToLocation, ToType, ToSourceExpr) = *Imp;
6556 
6557   return new (Importer.getToContext()) OpaqueValueExpr(
6558       ToLocation, ToType, E->getValueKind(), E->getObjectKind(), ToSourceExpr);
6559 }
6560 
6561 ExpectedStmt ASTNodeImporter::VisitArraySubscriptExpr(ArraySubscriptExpr *E) {
6562   auto Imp = importSeq(
6563       E->getLHS(), E->getRHS(), E->getType(), E->getRBracketLoc());
6564   if (!Imp)
6565     return Imp.takeError();
6566 
6567   Expr *ToLHS, *ToRHS;
6568   SourceLocation ToRBracketLoc;
6569   QualType ToType;
6570   std::tie(ToLHS, ToRHS, ToType, ToRBracketLoc) = *Imp;
6571 
6572   return new (Importer.getToContext()) ArraySubscriptExpr(
6573       ToLHS, ToRHS, ToType, E->getValueKind(), E->getObjectKind(),
6574       ToRBracketLoc);
6575 }
6576 
6577 ExpectedStmt
6578 ASTNodeImporter::VisitCompoundAssignOperator(CompoundAssignOperator *E) {
6579   auto Imp = importSeq(
6580       E->getLHS(), E->getRHS(), E->getType(), E->getComputationLHSType(),
6581       E->getComputationResultType(), E->getOperatorLoc());
6582   if (!Imp)
6583     return Imp.takeError();
6584 
6585   Expr *ToLHS, *ToRHS;
6586   QualType ToType, ToComputationLHSType, ToComputationResultType;
6587   SourceLocation ToOperatorLoc;
6588   std::tie(ToLHS, ToRHS, ToType, ToComputationLHSType, ToComputationResultType,
6589       ToOperatorLoc) = *Imp;
6590 
6591   return new (Importer.getToContext()) CompoundAssignOperator(
6592       ToLHS, ToRHS, E->getOpcode(), ToType, E->getValueKind(),
6593       E->getObjectKind(), ToComputationLHSType, ToComputationResultType,
6594       ToOperatorLoc, E->getFPFeatures());
6595 }
6596 
6597 Expected<CXXCastPath>
6598 ASTNodeImporter::ImportCastPath(CastExpr *CE) {
6599   CXXCastPath Path;
6600   for (auto I = CE->path_begin(), E = CE->path_end(); I != E; ++I) {
6601     if (auto SpecOrErr = import(*I))
6602       Path.push_back(*SpecOrErr);
6603     else
6604       return SpecOrErr.takeError();
6605   }
6606   return Path;
6607 }
6608 
6609 ExpectedStmt ASTNodeImporter::VisitImplicitCastExpr(ImplicitCastExpr *E) {
6610   ExpectedType ToTypeOrErr = import(E->getType());
6611   if (!ToTypeOrErr)
6612     return ToTypeOrErr.takeError();
6613 
6614   ExpectedExpr ToSubExprOrErr = import(E->getSubExpr());
6615   if (!ToSubExprOrErr)
6616     return ToSubExprOrErr.takeError();
6617 
6618   Expected<CXXCastPath> ToBasePathOrErr = ImportCastPath(E);
6619   if (!ToBasePathOrErr)
6620     return ToBasePathOrErr.takeError();
6621 
6622   return ImplicitCastExpr::Create(
6623       Importer.getToContext(), *ToTypeOrErr, E->getCastKind(), *ToSubExprOrErr,
6624       &(*ToBasePathOrErr), E->getValueKind());
6625 }
6626 
6627 ExpectedStmt ASTNodeImporter::VisitExplicitCastExpr(ExplicitCastExpr *E) {
6628   auto Imp1 = importSeq(
6629       E->getType(), E->getSubExpr(), E->getTypeInfoAsWritten());
6630   if (!Imp1)
6631     return Imp1.takeError();
6632 
6633   QualType ToType;
6634   Expr *ToSubExpr;
6635   TypeSourceInfo *ToTypeInfoAsWritten;
6636   std::tie(ToType, ToSubExpr, ToTypeInfoAsWritten) = *Imp1;
6637 
6638   Expected<CXXCastPath> ToBasePathOrErr = ImportCastPath(E);
6639   if (!ToBasePathOrErr)
6640     return ToBasePathOrErr.takeError();
6641   CXXCastPath *ToBasePath = &(*ToBasePathOrErr);
6642 
6643   switch (E->getStmtClass()) {
6644   case Stmt::CStyleCastExprClass: {
6645     auto *CCE = cast<CStyleCastExpr>(E);
6646     ExpectedSLoc ToLParenLocOrErr = import(CCE->getLParenLoc());
6647     if (!ToLParenLocOrErr)
6648       return ToLParenLocOrErr.takeError();
6649     ExpectedSLoc ToRParenLocOrErr = import(CCE->getRParenLoc());
6650     if (!ToRParenLocOrErr)
6651       return ToRParenLocOrErr.takeError();
6652     return CStyleCastExpr::Create(
6653         Importer.getToContext(), ToType, E->getValueKind(), E->getCastKind(),
6654         ToSubExpr, ToBasePath, ToTypeInfoAsWritten, *ToLParenLocOrErr,
6655         *ToRParenLocOrErr);
6656   }
6657 
6658   case Stmt::CXXFunctionalCastExprClass: {
6659     auto *FCE = cast<CXXFunctionalCastExpr>(E);
6660     ExpectedSLoc ToLParenLocOrErr = import(FCE->getLParenLoc());
6661     if (!ToLParenLocOrErr)
6662       return ToLParenLocOrErr.takeError();
6663     ExpectedSLoc ToRParenLocOrErr = import(FCE->getRParenLoc());
6664     if (!ToRParenLocOrErr)
6665       return ToRParenLocOrErr.takeError();
6666     return CXXFunctionalCastExpr::Create(
6667         Importer.getToContext(), ToType, E->getValueKind(), ToTypeInfoAsWritten,
6668         E->getCastKind(), ToSubExpr, ToBasePath, *ToLParenLocOrErr,
6669         *ToRParenLocOrErr);
6670   }
6671 
6672   case Stmt::ObjCBridgedCastExprClass: {
6673     auto *OCE = cast<ObjCBridgedCastExpr>(E);
6674     ExpectedSLoc ToLParenLocOrErr = import(OCE->getLParenLoc());
6675     if (!ToLParenLocOrErr)
6676       return ToLParenLocOrErr.takeError();
6677     ExpectedSLoc ToBridgeKeywordLocOrErr = import(OCE->getBridgeKeywordLoc());
6678     if (!ToBridgeKeywordLocOrErr)
6679       return ToBridgeKeywordLocOrErr.takeError();
6680     return new (Importer.getToContext()) ObjCBridgedCastExpr(
6681         *ToLParenLocOrErr, OCE->getBridgeKind(), E->getCastKind(),
6682         *ToBridgeKeywordLocOrErr, ToTypeInfoAsWritten, ToSubExpr);
6683   }
6684   default:
6685     llvm_unreachable("Cast expression of unsupported type!");
6686     return make_error<ImportError>(ImportError::UnsupportedConstruct);
6687   }
6688 }
6689 
6690 ExpectedStmt ASTNodeImporter::VisitOffsetOfExpr(OffsetOfExpr *E) {
6691   SmallVector<OffsetOfNode, 4> ToNodes;
6692   for (int I = 0, N = E->getNumComponents(); I < N; ++I) {
6693     const OffsetOfNode &FromNode = E->getComponent(I);
6694 
6695     SourceLocation ToBeginLoc, ToEndLoc;
6696     if (FromNode.getKind() != OffsetOfNode::Base) {
6697       auto Imp = importSeq(FromNode.getBeginLoc(), FromNode.getEndLoc());
6698       if (!Imp)
6699         return Imp.takeError();
6700       std::tie(ToBeginLoc, ToEndLoc) = *Imp;
6701     }
6702 
6703     switch (FromNode.getKind()) {
6704     case OffsetOfNode::Array:
6705       ToNodes.push_back(
6706           OffsetOfNode(ToBeginLoc, FromNode.getArrayExprIndex(), ToEndLoc));
6707       break;
6708     case OffsetOfNode::Base: {
6709       auto ToBSOrErr = import(FromNode.getBase());
6710       if (!ToBSOrErr)
6711         return ToBSOrErr.takeError();
6712       ToNodes.push_back(OffsetOfNode(*ToBSOrErr));
6713       break;
6714     }
6715     case OffsetOfNode::Field: {
6716       auto ToFieldOrErr = import(FromNode.getField());
6717       if (!ToFieldOrErr)
6718         return ToFieldOrErr.takeError();
6719       ToNodes.push_back(OffsetOfNode(ToBeginLoc, *ToFieldOrErr, ToEndLoc));
6720       break;
6721     }
6722     case OffsetOfNode::Identifier: {
6723       IdentifierInfo *ToII = Importer.Import(FromNode.getFieldName());
6724       ToNodes.push_back(OffsetOfNode(ToBeginLoc, ToII, ToEndLoc));
6725       break;
6726     }
6727     }
6728   }
6729 
6730   SmallVector<Expr *, 4> ToExprs(E->getNumExpressions());
6731   for (int I = 0, N = E->getNumExpressions(); I < N; ++I) {
6732     ExpectedExpr ToIndexExprOrErr = import(E->getIndexExpr(I));
6733     if (!ToIndexExprOrErr)
6734       return ToIndexExprOrErr.takeError();
6735     ToExprs[I] = *ToIndexExprOrErr;
6736   }
6737 
6738   auto Imp = importSeq(
6739       E->getType(), E->getTypeSourceInfo(), E->getOperatorLoc(),
6740       E->getRParenLoc());
6741   if (!Imp)
6742     return Imp.takeError();
6743 
6744   QualType ToType;
6745   TypeSourceInfo *ToTypeSourceInfo;
6746   SourceLocation ToOperatorLoc, ToRParenLoc;
6747   std::tie(ToType, ToTypeSourceInfo, ToOperatorLoc, ToRParenLoc) = *Imp;
6748 
6749   return OffsetOfExpr::Create(
6750       Importer.getToContext(), ToType, ToOperatorLoc, ToTypeSourceInfo, ToNodes,
6751       ToExprs, ToRParenLoc);
6752 }
6753 
6754 ExpectedStmt ASTNodeImporter::VisitCXXNoexceptExpr(CXXNoexceptExpr *E) {
6755   auto Imp = importSeq(
6756       E->getType(), E->getOperand(), E->getBeginLoc(), E->getEndLoc());
6757   if (!Imp)
6758     return Imp.takeError();
6759 
6760   QualType ToType;
6761   Expr *ToOperand;
6762   SourceLocation ToBeginLoc, ToEndLoc;
6763   std::tie(ToType, ToOperand, ToBeginLoc, ToEndLoc) = *Imp;
6764 
6765   CanThrowResult ToCanThrow;
6766   if (E->isValueDependent())
6767     ToCanThrow = CT_Dependent;
6768   else
6769     ToCanThrow = E->getValue() ? CT_Can : CT_Cannot;
6770 
6771   return new (Importer.getToContext()) CXXNoexceptExpr(
6772       ToType, ToOperand, ToCanThrow, ToBeginLoc, ToEndLoc);
6773 }
6774 
6775 ExpectedStmt ASTNodeImporter::VisitCXXThrowExpr(CXXThrowExpr *E) {
6776   auto Imp = importSeq(E->getSubExpr(), E->getType(), E->getThrowLoc());
6777   if (!Imp)
6778     return Imp.takeError();
6779 
6780   Expr *ToSubExpr;
6781   QualType ToType;
6782   SourceLocation ToThrowLoc;
6783   std::tie(ToSubExpr, ToType, ToThrowLoc) = *Imp;
6784 
6785   return new (Importer.getToContext()) CXXThrowExpr(
6786       ToSubExpr, ToType, ToThrowLoc, E->isThrownVariableInScope());
6787 }
6788 
6789 ExpectedStmt ASTNodeImporter::VisitCXXDefaultArgExpr(CXXDefaultArgExpr *E) {
6790   ExpectedSLoc ToUsedLocOrErr = import(E->getUsedLocation());
6791   if (!ToUsedLocOrErr)
6792     return ToUsedLocOrErr.takeError();
6793 
6794   auto ToParamOrErr = import(E->getParam());
6795   if (!ToParamOrErr)
6796     return ToParamOrErr.takeError();
6797 
6798   return CXXDefaultArgExpr::Create(
6799       Importer.getToContext(), *ToUsedLocOrErr, *ToParamOrErr);
6800 }
6801 
6802 ExpectedStmt
6803 ASTNodeImporter::VisitCXXScalarValueInitExpr(CXXScalarValueInitExpr *E) {
6804   auto Imp = importSeq(
6805       E->getType(), E->getTypeSourceInfo(), E->getRParenLoc());
6806   if (!Imp)
6807     return Imp.takeError();
6808 
6809   QualType ToType;
6810   TypeSourceInfo *ToTypeSourceInfo;
6811   SourceLocation ToRParenLoc;
6812   std::tie(ToType, ToTypeSourceInfo, ToRParenLoc) = *Imp;
6813 
6814   return new (Importer.getToContext()) CXXScalarValueInitExpr(
6815       ToType, ToTypeSourceInfo, ToRParenLoc);
6816 }
6817 
6818 ExpectedStmt
6819 ASTNodeImporter::VisitCXXBindTemporaryExpr(CXXBindTemporaryExpr *E) {
6820   ExpectedExpr ToSubExprOrErr = import(E->getSubExpr());
6821   if (!ToSubExprOrErr)
6822     return ToSubExprOrErr.takeError();
6823 
6824   auto ToDtorOrErr = import(E->getTemporary()->getDestructor());
6825   if (!ToDtorOrErr)
6826     return ToDtorOrErr.takeError();
6827 
6828   ASTContext &ToCtx = Importer.getToContext();
6829   CXXTemporary *Temp = CXXTemporary::Create(ToCtx, *ToDtorOrErr);
6830   return CXXBindTemporaryExpr::Create(ToCtx, Temp, *ToSubExprOrErr);
6831 }
6832 
6833 ExpectedStmt
6834 ASTNodeImporter::VisitCXXTemporaryObjectExpr(CXXTemporaryObjectExpr *E) {
6835   auto Imp = importSeq(
6836       E->getConstructor(), E->getType(), E->getTypeSourceInfo(),
6837       E->getParenOrBraceRange());
6838   if (!Imp)
6839     return Imp.takeError();
6840 
6841   CXXConstructorDecl *ToConstructor;
6842   QualType ToType;
6843   TypeSourceInfo *ToTypeSourceInfo;
6844   SourceRange ToParenOrBraceRange;
6845   std::tie(ToConstructor, ToType, ToTypeSourceInfo, ToParenOrBraceRange) = *Imp;
6846 
6847   SmallVector<Expr *, 8> ToArgs(E->getNumArgs());
6848   if (Error Err = ImportContainerChecked(E->arguments(), ToArgs))
6849     return std::move(Err);
6850 
6851   return new (Importer.getToContext()) CXXTemporaryObjectExpr(
6852       Importer.getToContext(), ToConstructor, ToType, ToTypeSourceInfo, ToArgs,
6853       ToParenOrBraceRange, E->hadMultipleCandidates(),
6854       E->isListInitialization(), E->isStdInitListInitialization(),
6855       E->requiresZeroInitialization());
6856 }
6857 
6858 ExpectedStmt
6859 ASTNodeImporter::VisitMaterializeTemporaryExpr(MaterializeTemporaryExpr *E) {
6860   auto Imp = importSeq(
6861       E->getType(), E->GetTemporaryExpr(), E->getExtendingDecl());
6862   if (!Imp)
6863     return Imp.takeError();
6864 
6865   QualType ToType;
6866   Expr *ToTemporaryExpr;
6867   const ValueDecl *ToExtendingDecl;
6868   std::tie(ToType, ToTemporaryExpr, ToExtendingDecl) = *Imp;
6869 
6870   auto *ToMTE =  new (Importer.getToContext()) MaterializeTemporaryExpr(
6871       ToType, ToTemporaryExpr, E->isBoundToLvalueReference());
6872 
6873   // FIXME: Should ManglingNumber get numbers associated with 'to' context?
6874   ToMTE->setExtendingDecl(ToExtendingDecl, E->getManglingNumber());
6875   return ToMTE;
6876 }
6877 
6878 ExpectedStmt ASTNodeImporter::VisitPackExpansionExpr(PackExpansionExpr *E) {
6879   auto Imp = importSeq(
6880       E->getType(), E->getPattern(), E->getEllipsisLoc());
6881   if (!Imp)
6882     return Imp.takeError();
6883 
6884   QualType ToType;
6885   Expr *ToPattern;
6886   SourceLocation ToEllipsisLoc;
6887   std::tie(ToType, ToPattern, ToEllipsisLoc) = *Imp;
6888 
6889   return new (Importer.getToContext()) PackExpansionExpr(
6890       ToType, ToPattern, ToEllipsisLoc, E->getNumExpansions());
6891 }
6892 
6893 ExpectedStmt ASTNodeImporter::VisitSizeOfPackExpr(SizeOfPackExpr *E) {
6894   auto Imp = importSeq(
6895       E->getOperatorLoc(), E->getPack(), E->getPackLoc(), E->getRParenLoc());
6896   if (!Imp)
6897     return Imp.takeError();
6898 
6899   SourceLocation ToOperatorLoc, ToPackLoc, ToRParenLoc;
6900   NamedDecl *ToPack;
6901   std::tie(ToOperatorLoc, ToPack, ToPackLoc, ToRParenLoc) = *Imp;
6902 
6903   Optional<unsigned> Length;
6904   if (!E->isValueDependent())
6905     Length = E->getPackLength();
6906 
6907   SmallVector<TemplateArgument, 8> ToPartialArguments;
6908   if (E->isPartiallySubstituted()) {
6909     if (Error Err = ImportTemplateArguments(
6910         E->getPartialArguments().data(),
6911         E->getPartialArguments().size(),
6912         ToPartialArguments))
6913       return std::move(Err);
6914   }
6915 
6916   return SizeOfPackExpr::Create(
6917       Importer.getToContext(), ToOperatorLoc, ToPack, ToPackLoc, ToRParenLoc,
6918       Length, ToPartialArguments);
6919 }
6920 
6921 
6922 ExpectedStmt ASTNodeImporter::VisitCXXNewExpr(CXXNewExpr *E) {
6923   auto Imp = importSeq(
6924       E->getOperatorNew(), E->getOperatorDelete(), E->getTypeIdParens(),
6925       E->getArraySize(), E->getInitializer(), E->getType(),
6926       E->getAllocatedTypeSourceInfo(), E->getSourceRange(),
6927       E->getDirectInitRange());
6928   if (!Imp)
6929     return Imp.takeError();
6930 
6931   FunctionDecl *ToOperatorNew, *ToOperatorDelete;
6932   SourceRange ToTypeIdParens, ToSourceRange, ToDirectInitRange;
6933   Expr *ToArraySize, *ToInitializer;
6934   QualType ToType;
6935   TypeSourceInfo *ToAllocatedTypeSourceInfo;
6936   std::tie(
6937     ToOperatorNew, ToOperatorDelete, ToTypeIdParens, ToArraySize, ToInitializer,
6938     ToType, ToAllocatedTypeSourceInfo, ToSourceRange, ToDirectInitRange) = *Imp;
6939 
6940   SmallVector<Expr *, 4> ToPlacementArgs(E->getNumPlacementArgs());
6941   if (Error Err =
6942       ImportContainerChecked(E->placement_arguments(), ToPlacementArgs))
6943     return std::move(Err);
6944 
6945   return new (Importer.getToContext()) CXXNewExpr(
6946       Importer.getToContext(), E->isGlobalNew(), ToOperatorNew,
6947       ToOperatorDelete, E->passAlignment(), E->doesUsualArrayDeleteWantSize(),
6948       ToPlacementArgs, ToTypeIdParens, ToArraySize, E->getInitializationStyle(),
6949       ToInitializer, ToType, ToAllocatedTypeSourceInfo, ToSourceRange,
6950       ToDirectInitRange);
6951 }
6952 
6953 ExpectedStmt ASTNodeImporter::VisitCXXDeleteExpr(CXXDeleteExpr *E) {
6954   auto Imp = importSeq(
6955       E->getType(), E->getOperatorDelete(), E->getArgument(), E->getBeginLoc());
6956   if (!Imp)
6957     return Imp.takeError();
6958 
6959   QualType ToType;
6960   FunctionDecl *ToOperatorDelete;
6961   Expr *ToArgument;
6962   SourceLocation ToBeginLoc;
6963   std::tie(ToType, ToOperatorDelete, ToArgument, ToBeginLoc) = *Imp;
6964 
6965   return new (Importer.getToContext()) CXXDeleteExpr(
6966       ToType, E->isGlobalDelete(), E->isArrayForm(), E->isArrayFormAsWritten(),
6967       E->doesUsualArrayDeleteWantSize(), ToOperatorDelete, ToArgument,
6968       ToBeginLoc);
6969 }
6970 
6971 ExpectedStmt ASTNodeImporter::VisitCXXConstructExpr(CXXConstructExpr *E) {
6972   auto Imp = importSeq(
6973       E->getType(), E->getLocation(), E->getConstructor(),
6974       E->getParenOrBraceRange());
6975   if (!Imp)
6976     return Imp.takeError();
6977 
6978   QualType ToType;
6979   SourceLocation ToLocation;
6980   CXXConstructorDecl *ToConstructor;
6981   SourceRange ToParenOrBraceRange;
6982   std::tie(ToType, ToLocation, ToConstructor, ToParenOrBraceRange) = *Imp;
6983 
6984   SmallVector<Expr *, 6> ToArgs(E->getNumArgs());
6985   if (Error Err = ImportContainerChecked(E->arguments(), ToArgs))
6986     return std::move(Err);
6987 
6988   return CXXConstructExpr::Create(
6989       Importer.getToContext(), ToType, ToLocation, ToConstructor,
6990       E->isElidable(), ToArgs, E->hadMultipleCandidates(),
6991       E->isListInitialization(), E->isStdInitListInitialization(),
6992       E->requiresZeroInitialization(), E->getConstructionKind(),
6993       ToParenOrBraceRange);
6994 }
6995 
6996 ExpectedStmt ASTNodeImporter::VisitExprWithCleanups(ExprWithCleanups *E) {
6997   ExpectedExpr ToSubExprOrErr = import(E->getSubExpr());
6998   if (!ToSubExprOrErr)
6999     return ToSubExprOrErr.takeError();
7000 
7001   SmallVector<ExprWithCleanups::CleanupObject, 8> ToObjects(E->getNumObjects());
7002   if (Error Err = ImportContainerChecked(E->getObjects(), ToObjects))
7003     return std::move(Err);
7004 
7005   return ExprWithCleanups::Create(
7006       Importer.getToContext(), *ToSubExprOrErr, E->cleanupsHaveSideEffects(),
7007       ToObjects);
7008 }
7009 
7010 ExpectedStmt ASTNodeImporter::VisitCXXMemberCallExpr(CXXMemberCallExpr *E) {
7011   auto Imp = importSeq(
7012       E->getCallee(), E->getType(), E->getRParenLoc());
7013   if (!Imp)
7014     return Imp.takeError();
7015 
7016   Expr *ToCallee;
7017   QualType ToType;
7018   SourceLocation ToRParenLoc;
7019   std::tie(ToCallee, ToType, ToRParenLoc) = *Imp;
7020 
7021   SmallVector<Expr *, 4> ToArgs(E->getNumArgs());
7022   if (Error Err = ImportContainerChecked(E->arguments(), ToArgs))
7023     return std::move(Err);
7024 
7025   return new (Importer.getToContext()) CXXMemberCallExpr(
7026       Importer.getToContext(), ToCallee, ToArgs, ToType, E->getValueKind(),
7027       ToRParenLoc);
7028 }
7029 
7030 ExpectedStmt ASTNodeImporter::VisitCXXThisExpr(CXXThisExpr *E) {
7031   ExpectedType ToTypeOrErr = import(E->getType());
7032   if (!ToTypeOrErr)
7033     return ToTypeOrErr.takeError();
7034 
7035   ExpectedSLoc ToLocationOrErr = import(E->getLocation());
7036   if (!ToLocationOrErr)
7037     return ToLocationOrErr.takeError();
7038 
7039   return new (Importer.getToContext()) CXXThisExpr(
7040       *ToLocationOrErr, *ToTypeOrErr, E->isImplicit());
7041 }
7042 
7043 ExpectedStmt ASTNodeImporter::VisitCXXBoolLiteralExpr(CXXBoolLiteralExpr *E) {
7044   ExpectedType ToTypeOrErr = import(E->getType());
7045   if (!ToTypeOrErr)
7046     return ToTypeOrErr.takeError();
7047 
7048   ExpectedSLoc ToLocationOrErr = import(E->getLocation());
7049   if (!ToLocationOrErr)
7050     return ToLocationOrErr.takeError();
7051 
7052   return new (Importer.getToContext()) CXXBoolLiteralExpr(
7053       E->getValue(), *ToTypeOrErr, *ToLocationOrErr);
7054 }
7055 
7056 ExpectedStmt ASTNodeImporter::VisitMemberExpr(MemberExpr *E) {
7057   auto Imp1 = importSeq(
7058       E->getBase(), E->getOperatorLoc(), E->getQualifierLoc(),
7059       E->getTemplateKeywordLoc(), E->getMemberDecl(), E->getType());
7060   if (!Imp1)
7061     return Imp1.takeError();
7062 
7063   Expr *ToBase;
7064   SourceLocation ToOperatorLoc, ToTemplateKeywordLoc;
7065   NestedNameSpecifierLoc ToQualifierLoc;
7066   ValueDecl *ToMemberDecl;
7067   QualType ToType;
7068   std::tie(
7069       ToBase, ToOperatorLoc, ToQualifierLoc, ToTemplateKeywordLoc, ToMemberDecl,
7070       ToType) = *Imp1;
7071 
7072   auto Imp2 = importSeq(
7073       E->getFoundDecl().getDecl(), E->getMemberNameInfo().getName(),
7074       E->getMemberNameInfo().getLoc(), E->getLAngleLoc(), E->getRAngleLoc());
7075   if (!Imp2)
7076     return Imp2.takeError();
7077   NamedDecl *ToDecl;
7078   DeclarationName ToName;
7079   SourceLocation ToLoc, ToLAngleLoc, ToRAngleLoc;
7080   std::tie(ToDecl, ToName, ToLoc, ToLAngleLoc, ToRAngleLoc) = *Imp2;
7081 
7082   DeclAccessPair ToFoundDecl =
7083       DeclAccessPair::make(ToDecl, E->getFoundDecl().getAccess());
7084 
7085   DeclarationNameInfo ToMemberNameInfo(ToName, ToLoc);
7086 
7087   if (E->hasExplicitTemplateArgs()) {
7088     // FIXME: handle template arguments
7089     return make_error<ImportError>(ImportError::UnsupportedConstruct);
7090   }
7091 
7092   return MemberExpr::Create(
7093       Importer.getToContext(), ToBase, E->isArrow(), ToOperatorLoc,
7094       ToQualifierLoc, ToTemplateKeywordLoc, ToMemberDecl, ToFoundDecl,
7095       ToMemberNameInfo, nullptr, ToType, E->getValueKind(), E->getObjectKind());
7096 }
7097 
7098 ExpectedStmt
7099 ASTNodeImporter::VisitCXXPseudoDestructorExpr(CXXPseudoDestructorExpr *E) {
7100   auto Imp = importSeq(
7101       E->getBase(), E->getOperatorLoc(), E->getQualifierLoc(),
7102       E->getScopeTypeInfo(), E->getColonColonLoc(), E->getTildeLoc());
7103   if (!Imp)
7104     return Imp.takeError();
7105 
7106   Expr *ToBase;
7107   SourceLocation ToOperatorLoc, ToColonColonLoc, ToTildeLoc;
7108   NestedNameSpecifierLoc ToQualifierLoc;
7109   TypeSourceInfo *ToScopeTypeInfo;
7110   std::tie(
7111       ToBase, ToOperatorLoc, ToQualifierLoc, ToScopeTypeInfo, ToColonColonLoc,
7112       ToTildeLoc) = *Imp;
7113 
7114   PseudoDestructorTypeStorage Storage;
7115   if (IdentifierInfo *FromII = E->getDestroyedTypeIdentifier()) {
7116     IdentifierInfo *ToII = Importer.Import(FromII);
7117     ExpectedSLoc ToDestroyedTypeLocOrErr = import(E->getDestroyedTypeLoc());
7118     if (!ToDestroyedTypeLocOrErr)
7119       return ToDestroyedTypeLocOrErr.takeError();
7120     Storage = PseudoDestructorTypeStorage(ToII, *ToDestroyedTypeLocOrErr);
7121   } else {
7122     if (auto ToTIOrErr = import(E->getDestroyedTypeInfo()))
7123       Storage = PseudoDestructorTypeStorage(*ToTIOrErr);
7124     else
7125       return ToTIOrErr.takeError();
7126   }
7127 
7128   return new (Importer.getToContext()) CXXPseudoDestructorExpr(
7129       Importer.getToContext(), ToBase, E->isArrow(), ToOperatorLoc,
7130       ToQualifierLoc, ToScopeTypeInfo, ToColonColonLoc, ToTildeLoc, Storage);
7131 }
7132 
7133 ExpectedStmt ASTNodeImporter::VisitCXXDependentScopeMemberExpr(
7134     CXXDependentScopeMemberExpr *E) {
7135   auto Imp = importSeq(
7136       E->getType(), E->getOperatorLoc(), E->getQualifierLoc(),
7137       E->getTemplateKeywordLoc(), E->getFirstQualifierFoundInScope());
7138   if (!Imp)
7139     return Imp.takeError();
7140 
7141   QualType ToType;
7142   SourceLocation ToOperatorLoc, ToTemplateKeywordLoc;
7143   NestedNameSpecifierLoc ToQualifierLoc;
7144   NamedDecl *ToFirstQualifierFoundInScope;
7145   std::tie(
7146       ToType, ToOperatorLoc, ToQualifierLoc, ToTemplateKeywordLoc,
7147       ToFirstQualifierFoundInScope) = *Imp;
7148 
7149   Expr *ToBase = nullptr;
7150   if (!E->isImplicitAccess()) {
7151     if (ExpectedExpr ToBaseOrErr = import(E->getBase()))
7152       ToBase = *ToBaseOrErr;
7153     else
7154       return ToBaseOrErr.takeError();
7155   }
7156 
7157   TemplateArgumentListInfo ToTAInfo, *ResInfo = nullptr;
7158   if (E->hasExplicitTemplateArgs()) {
7159     if (Error Err = ImportTemplateArgumentListInfo(
7160         E->getLAngleLoc(), E->getRAngleLoc(), E->template_arguments(),
7161         ToTAInfo))
7162       return std::move(Err);
7163     ResInfo = &ToTAInfo;
7164   }
7165 
7166   auto ToMemberNameInfoOrErr = importSeq(E->getMember(), E->getMemberLoc());
7167   if (!ToMemberNameInfoOrErr)
7168     return ToMemberNameInfoOrErr.takeError();
7169   DeclarationNameInfo ToMemberNameInfo(
7170       std::get<0>(*ToMemberNameInfoOrErr), std::get<1>(*ToMemberNameInfoOrErr));
7171   // Import additional name location/type info.
7172   if (Error Err = ImportDeclarationNameLoc(
7173       E->getMemberNameInfo(), ToMemberNameInfo))
7174     return std::move(Err);
7175 
7176   return CXXDependentScopeMemberExpr::Create(
7177       Importer.getToContext(), ToBase, ToType, E->isArrow(), ToOperatorLoc,
7178       ToQualifierLoc, ToTemplateKeywordLoc, ToFirstQualifierFoundInScope,
7179       ToMemberNameInfo, ResInfo);
7180 }
7181 
7182 ExpectedStmt
7183 ASTNodeImporter::VisitDependentScopeDeclRefExpr(DependentScopeDeclRefExpr *E) {
7184   auto Imp = importSeq(
7185       E->getQualifierLoc(), E->getTemplateKeywordLoc(), E->getDeclName(),
7186       E->getExprLoc(), E->getLAngleLoc(), E->getRAngleLoc());
7187   if (!Imp)
7188     return Imp.takeError();
7189 
7190   NestedNameSpecifierLoc ToQualifierLoc;
7191   SourceLocation ToTemplateKeywordLoc, ToExprLoc, ToLAngleLoc, ToRAngleLoc;
7192   DeclarationName ToDeclName;
7193   std::tie(
7194       ToQualifierLoc, ToTemplateKeywordLoc, ToDeclName, ToExprLoc,
7195       ToLAngleLoc, ToRAngleLoc) = *Imp;
7196 
7197   DeclarationNameInfo ToNameInfo(ToDeclName, ToExprLoc);
7198   if (Error Err = ImportDeclarationNameLoc(E->getNameInfo(), ToNameInfo))
7199     return std::move(Err);
7200 
7201   TemplateArgumentListInfo ToTAInfo(ToLAngleLoc, ToRAngleLoc);
7202   TemplateArgumentListInfo *ResInfo = nullptr;
7203   if (E->hasExplicitTemplateArgs()) {
7204     if (Error Err =
7205         ImportTemplateArgumentListInfo(E->template_arguments(), ToTAInfo))
7206       return std::move(Err);
7207     ResInfo = &ToTAInfo;
7208   }
7209 
7210   return DependentScopeDeclRefExpr::Create(
7211       Importer.getToContext(), ToQualifierLoc, ToTemplateKeywordLoc,
7212       ToNameInfo, ResInfo);
7213 }
7214 
7215 ExpectedStmt ASTNodeImporter::VisitCXXUnresolvedConstructExpr(
7216     CXXUnresolvedConstructExpr *E) {
7217   auto Imp = importSeq(
7218       E->getLParenLoc(), E->getRParenLoc(), E->getTypeSourceInfo());
7219   if (!Imp)
7220     return Imp.takeError();
7221 
7222   SourceLocation ToLParenLoc, ToRParenLoc;
7223   TypeSourceInfo *ToTypeSourceInfo;
7224   std::tie(ToLParenLoc, ToRParenLoc, ToTypeSourceInfo) = *Imp;
7225 
7226   SmallVector<Expr *, 8> ToArgs(E->arg_size());
7227   if (Error Err =
7228       ImportArrayChecked(E->arg_begin(), E->arg_end(), ToArgs.begin()))
7229     return std::move(Err);
7230 
7231   return CXXUnresolvedConstructExpr::Create(
7232       Importer.getToContext(), ToTypeSourceInfo, ToLParenLoc,
7233       llvm::makeArrayRef(ToArgs), ToRParenLoc);
7234 }
7235 
7236 ExpectedStmt
7237 ASTNodeImporter::VisitUnresolvedLookupExpr(UnresolvedLookupExpr *E) {
7238   Expected<CXXRecordDecl *> ToNamingClassOrErr = import(E->getNamingClass());
7239   if (!ToNamingClassOrErr)
7240     return ToNamingClassOrErr.takeError();
7241 
7242   auto ToQualifierLocOrErr = import(E->getQualifierLoc());
7243   if (!ToQualifierLocOrErr)
7244     return ToQualifierLocOrErr.takeError();
7245 
7246   auto ToNameInfoOrErr = importSeq(E->getName(), E->getNameLoc());
7247   if (!ToNameInfoOrErr)
7248     return ToNameInfoOrErr.takeError();
7249   DeclarationNameInfo ToNameInfo(
7250       std::get<0>(*ToNameInfoOrErr), std::get<1>(*ToNameInfoOrErr));
7251   // Import additional name location/type info.
7252   if (Error Err = ImportDeclarationNameLoc(E->getNameInfo(), ToNameInfo))
7253     return std::move(Err);
7254 
7255   UnresolvedSet<8> ToDecls;
7256   for (auto *D : E->decls())
7257     if (auto ToDOrErr = import(D))
7258       ToDecls.addDecl(cast<NamedDecl>(*ToDOrErr));
7259     else
7260       return ToDOrErr.takeError();
7261 
7262   if (E->hasExplicitTemplateArgs() && E->getTemplateKeywordLoc().isValid()) {
7263     TemplateArgumentListInfo ToTAInfo;
7264     if (Error Err = ImportTemplateArgumentListInfo(
7265         E->getLAngleLoc(), E->getRAngleLoc(), E->template_arguments(),
7266         ToTAInfo))
7267       return std::move(Err);
7268 
7269     ExpectedSLoc ToTemplateKeywordLocOrErr = import(E->getTemplateKeywordLoc());
7270     if (!ToTemplateKeywordLocOrErr)
7271       return ToTemplateKeywordLocOrErr.takeError();
7272 
7273     return UnresolvedLookupExpr::Create(
7274         Importer.getToContext(), *ToNamingClassOrErr, *ToQualifierLocOrErr,
7275         *ToTemplateKeywordLocOrErr, ToNameInfo, E->requiresADL(), &ToTAInfo,
7276         ToDecls.begin(), ToDecls.end());
7277   }
7278 
7279   return UnresolvedLookupExpr::Create(
7280       Importer.getToContext(), *ToNamingClassOrErr, *ToQualifierLocOrErr,
7281       ToNameInfo, E->requiresADL(), E->isOverloaded(), ToDecls.begin(),
7282       ToDecls.end());
7283 }
7284 
7285 ExpectedStmt
7286 ASTNodeImporter::VisitUnresolvedMemberExpr(UnresolvedMemberExpr *E) {
7287   auto Imp1 = importSeq(
7288       E->getType(), E->getOperatorLoc(), E->getQualifierLoc(),
7289       E->getTemplateKeywordLoc());
7290   if (!Imp1)
7291     return Imp1.takeError();
7292 
7293   QualType ToType;
7294   SourceLocation ToOperatorLoc, ToTemplateKeywordLoc;
7295   NestedNameSpecifierLoc ToQualifierLoc;
7296   std::tie(ToType, ToOperatorLoc, ToQualifierLoc, ToTemplateKeywordLoc) = *Imp1;
7297 
7298   auto Imp2 = importSeq(E->getName(), E->getNameLoc());
7299   if (!Imp2)
7300     return Imp2.takeError();
7301   DeclarationNameInfo ToNameInfo(std::get<0>(*Imp2), std::get<1>(*Imp2));
7302   // Import additional name location/type info.
7303   if (Error Err = ImportDeclarationNameLoc(E->getNameInfo(), ToNameInfo))
7304     return std::move(Err);
7305 
7306   UnresolvedSet<8> ToDecls;
7307   for (Decl *D : E->decls())
7308     if (auto ToDOrErr = import(D))
7309       ToDecls.addDecl(cast<NamedDecl>(*ToDOrErr));
7310     else
7311       return ToDOrErr.takeError();
7312 
7313   TemplateArgumentListInfo ToTAInfo;
7314   TemplateArgumentListInfo *ResInfo = nullptr;
7315   if (E->hasExplicitTemplateArgs()) {
7316     if (Error Err =
7317         ImportTemplateArgumentListInfo(E->template_arguments(), ToTAInfo))
7318       return std::move(Err);
7319     ResInfo = &ToTAInfo;
7320   }
7321 
7322   Expr *ToBase = nullptr;
7323   if (!E->isImplicitAccess()) {
7324     if (ExpectedExpr ToBaseOrErr = import(E->getBase()))
7325       ToBase = *ToBaseOrErr;
7326     else
7327       return ToBaseOrErr.takeError();
7328   }
7329 
7330   return UnresolvedMemberExpr::Create(
7331       Importer.getToContext(), E->hasUnresolvedUsing(), ToBase, ToType,
7332       E->isArrow(), ToOperatorLoc, ToQualifierLoc, ToTemplateKeywordLoc,
7333       ToNameInfo, ResInfo, ToDecls.begin(), ToDecls.end());
7334 }
7335 
7336 ExpectedStmt ASTNodeImporter::VisitCallExpr(CallExpr *E) {
7337   auto Imp = importSeq(E->getCallee(), E->getType(), E->getRParenLoc());
7338   if (!Imp)
7339     return Imp.takeError();
7340 
7341   Expr *ToCallee;
7342   QualType ToType;
7343   SourceLocation ToRParenLoc;
7344   std::tie(ToCallee, ToType, ToRParenLoc) = *Imp;
7345 
7346   unsigned NumArgs = E->getNumArgs();
7347   llvm::SmallVector<Expr *, 2> ToArgs(NumArgs);
7348   if (Error Err = ImportContainerChecked(E->arguments(), ToArgs))
7349      return std::move(Err);
7350 
7351   if (const auto *OCE = dyn_cast<CXXOperatorCallExpr>(E)) {
7352     return new (Importer.getToContext()) CXXOperatorCallExpr(
7353         Importer.getToContext(), OCE->getOperator(), ToCallee, ToArgs, ToType,
7354         OCE->getValueKind(), ToRParenLoc, OCE->getFPFeatures());
7355   }
7356 
7357   return new (Importer.getToContext()) CallExpr(
7358       Importer.getToContext(), ToCallee, ToArgs, ToType, E->getValueKind(),
7359       ToRParenLoc);
7360 }
7361 
7362 ExpectedStmt ASTNodeImporter::VisitLambdaExpr(LambdaExpr *E) {
7363   CXXRecordDecl *FromClass = E->getLambdaClass();
7364   auto ToClassOrErr = import(FromClass);
7365   if (!ToClassOrErr)
7366     return ToClassOrErr.takeError();
7367   CXXRecordDecl *ToClass = *ToClassOrErr;
7368 
7369   // NOTE: lambda classes are created with BeingDefined flag set up.
7370   // It means that ImportDefinition doesn't work for them and we should fill it
7371   // manually.
7372   if (ToClass->isBeingDefined()) {
7373     for (auto FromField : FromClass->fields()) {
7374       auto ToFieldOrErr = import(FromField);
7375       if (!ToFieldOrErr)
7376         return ToFieldOrErr.takeError();
7377     }
7378   }
7379 
7380   auto ToCallOpOrErr = import(E->getCallOperator());
7381   if (!ToCallOpOrErr)
7382     return ToCallOpOrErr.takeError();
7383 
7384   ToClass->completeDefinition();
7385 
7386   SmallVector<LambdaCapture, 8> ToCaptures;
7387   ToCaptures.reserve(E->capture_size());
7388   for (const auto &FromCapture : E->captures()) {
7389     if (auto ToCaptureOrErr = import(FromCapture))
7390       ToCaptures.push_back(*ToCaptureOrErr);
7391     else
7392       return ToCaptureOrErr.takeError();
7393   }
7394 
7395   SmallVector<Expr *, 8> ToCaptureInits(E->capture_size());
7396   if (Error Err = ImportContainerChecked(E->capture_inits(), ToCaptureInits))
7397     return std::move(Err);
7398 
7399   auto Imp = importSeq(
7400       E->getIntroducerRange(), E->getCaptureDefaultLoc(), E->getEndLoc());
7401   if (!Imp)
7402     return Imp.takeError();
7403 
7404   SourceRange ToIntroducerRange;
7405   SourceLocation ToCaptureDefaultLoc, ToEndLoc;
7406   std::tie(ToIntroducerRange, ToCaptureDefaultLoc, ToEndLoc) = *Imp;
7407 
7408   return LambdaExpr::Create(
7409       Importer.getToContext(), ToClass, ToIntroducerRange,
7410       E->getCaptureDefault(), ToCaptureDefaultLoc, ToCaptures,
7411       E->hasExplicitParameters(), E->hasExplicitResultType(), ToCaptureInits,
7412       ToEndLoc, E->containsUnexpandedParameterPack());
7413 }
7414 
7415 
7416 ExpectedStmt ASTNodeImporter::VisitInitListExpr(InitListExpr *E) {
7417   auto Imp = importSeq(E->getLBraceLoc(), E->getRBraceLoc(), E->getType());
7418   if (!Imp)
7419     return Imp.takeError();
7420 
7421   SourceLocation ToLBraceLoc, ToRBraceLoc;
7422   QualType ToType;
7423   std::tie(ToLBraceLoc, ToRBraceLoc, ToType) = *Imp;
7424 
7425   SmallVector<Expr *, 4> ToExprs(E->getNumInits());
7426   if (Error Err = ImportContainerChecked(E->inits(), ToExprs))
7427     return std::move(Err);
7428 
7429   ASTContext &ToCtx = Importer.getToContext();
7430   InitListExpr *To = new (ToCtx) InitListExpr(
7431       ToCtx, ToLBraceLoc, ToExprs, ToRBraceLoc);
7432   To->setType(ToType);
7433 
7434   if (E->hasArrayFiller()) {
7435     if (ExpectedExpr ToFillerOrErr = import(E->getArrayFiller()))
7436       To->setArrayFiller(*ToFillerOrErr);
7437     else
7438       return ToFillerOrErr.takeError();
7439   }
7440 
7441   if (FieldDecl *FromFD = E->getInitializedFieldInUnion()) {
7442     if (auto ToFDOrErr = import(FromFD))
7443       To->setInitializedFieldInUnion(*ToFDOrErr);
7444     else
7445       return ToFDOrErr.takeError();
7446   }
7447 
7448   if (InitListExpr *SyntForm = E->getSyntacticForm()) {
7449     if (auto ToSyntFormOrErr = import(SyntForm))
7450       To->setSyntacticForm(*ToSyntFormOrErr);
7451     else
7452       return ToSyntFormOrErr.takeError();
7453   }
7454 
7455   // Copy InitListExprBitfields, which are not handled in the ctor of
7456   // InitListExpr.
7457   To->sawArrayRangeDesignator(E->hadArrayRangeDesignator());
7458 
7459   return To;
7460 }
7461 
7462 ExpectedStmt ASTNodeImporter::VisitCXXStdInitializerListExpr(
7463     CXXStdInitializerListExpr *E) {
7464   ExpectedType ToTypeOrErr = import(E->getType());
7465   if (!ToTypeOrErr)
7466     return ToTypeOrErr.takeError();
7467 
7468   ExpectedExpr ToSubExprOrErr = import(E->getSubExpr());
7469   if (!ToSubExprOrErr)
7470     return ToSubExprOrErr.takeError();
7471 
7472   return new (Importer.getToContext()) CXXStdInitializerListExpr(
7473       *ToTypeOrErr, *ToSubExprOrErr);
7474 }
7475 
7476 ExpectedStmt ASTNodeImporter::VisitCXXInheritedCtorInitExpr(
7477     CXXInheritedCtorInitExpr *E) {
7478   auto Imp = importSeq(E->getLocation(), E->getType(), E->getConstructor());
7479   if (!Imp)
7480     return Imp.takeError();
7481 
7482   SourceLocation ToLocation;
7483   QualType ToType;
7484   CXXConstructorDecl *ToConstructor;
7485   std::tie(ToLocation, ToType, ToConstructor) = *Imp;
7486 
7487   return new (Importer.getToContext()) CXXInheritedCtorInitExpr(
7488       ToLocation, ToType, ToConstructor, E->constructsVBase(),
7489       E->inheritedFromVBase());
7490 }
7491 
7492 ExpectedStmt ASTNodeImporter::VisitArrayInitLoopExpr(ArrayInitLoopExpr *E) {
7493   auto Imp = importSeq(E->getType(), E->getCommonExpr(), E->getSubExpr());
7494   if (!Imp)
7495     return Imp.takeError();
7496 
7497   QualType ToType;
7498   Expr *ToCommonExpr, *ToSubExpr;
7499   std::tie(ToType, ToCommonExpr, ToSubExpr) = *Imp;
7500 
7501   return new (Importer.getToContext()) ArrayInitLoopExpr(
7502       ToType, ToCommonExpr, ToSubExpr);
7503 }
7504 
7505 ExpectedStmt ASTNodeImporter::VisitArrayInitIndexExpr(ArrayInitIndexExpr *E) {
7506   ExpectedType ToTypeOrErr = import(E->getType());
7507   if (!ToTypeOrErr)
7508     return ToTypeOrErr.takeError();
7509   return new (Importer.getToContext()) ArrayInitIndexExpr(*ToTypeOrErr);
7510 }
7511 
7512 ExpectedStmt ASTNodeImporter::VisitCXXDefaultInitExpr(CXXDefaultInitExpr *E) {
7513   ExpectedSLoc ToBeginLocOrErr = import(E->getBeginLoc());
7514   if (!ToBeginLocOrErr)
7515     return ToBeginLocOrErr.takeError();
7516 
7517   auto ToFieldOrErr = import(E->getField());
7518   if (!ToFieldOrErr)
7519     return ToFieldOrErr.takeError();
7520 
7521   return CXXDefaultInitExpr::Create(
7522       Importer.getToContext(), *ToBeginLocOrErr, *ToFieldOrErr);
7523 }
7524 
7525 ExpectedStmt ASTNodeImporter::VisitCXXNamedCastExpr(CXXNamedCastExpr *E) {
7526   auto Imp = importSeq(
7527       E->getType(), E->getSubExpr(), E->getTypeInfoAsWritten(),
7528       E->getOperatorLoc(), E->getRParenLoc(), E->getAngleBrackets());
7529   if (!Imp)
7530     return Imp.takeError();
7531 
7532   QualType ToType;
7533   Expr *ToSubExpr;
7534   TypeSourceInfo *ToTypeInfoAsWritten;
7535   SourceLocation ToOperatorLoc, ToRParenLoc;
7536   SourceRange ToAngleBrackets;
7537   std::tie(
7538       ToType, ToSubExpr, ToTypeInfoAsWritten, ToOperatorLoc, ToRParenLoc,
7539       ToAngleBrackets) = *Imp;
7540 
7541   ExprValueKind VK = E->getValueKind();
7542   CastKind CK = E->getCastKind();
7543   auto ToBasePathOrErr = ImportCastPath(E);
7544   if (!ToBasePathOrErr)
7545     return ToBasePathOrErr.takeError();
7546 
7547   if (isa<CXXStaticCastExpr>(E)) {
7548     return CXXStaticCastExpr::Create(
7549         Importer.getToContext(), ToType, VK, CK, ToSubExpr, &(*ToBasePathOrErr),
7550         ToTypeInfoAsWritten, ToOperatorLoc, ToRParenLoc, ToAngleBrackets);
7551   } else if (isa<CXXDynamicCastExpr>(E)) {
7552     return CXXDynamicCastExpr::Create(
7553         Importer.getToContext(), ToType, VK, CK, ToSubExpr, &(*ToBasePathOrErr),
7554         ToTypeInfoAsWritten, ToOperatorLoc, ToRParenLoc, ToAngleBrackets);
7555   } else if (isa<CXXReinterpretCastExpr>(E)) {
7556     return CXXReinterpretCastExpr::Create(
7557         Importer.getToContext(), ToType, VK, CK, ToSubExpr, &(*ToBasePathOrErr),
7558         ToTypeInfoAsWritten, ToOperatorLoc, ToRParenLoc, ToAngleBrackets);
7559   } else if (isa<CXXConstCastExpr>(E)) {
7560     return CXXConstCastExpr::Create(
7561         Importer.getToContext(), ToType, VK, ToSubExpr, ToTypeInfoAsWritten,
7562         ToOperatorLoc, ToRParenLoc, ToAngleBrackets);
7563   } else {
7564     llvm_unreachable("Unknown cast type");
7565     return make_error<ImportError>();
7566   }
7567 }
7568 
7569 ExpectedStmt ASTNodeImporter::VisitSubstNonTypeTemplateParmExpr(
7570     SubstNonTypeTemplateParmExpr *E) {
7571   auto Imp = importSeq(
7572       E->getType(), E->getExprLoc(), E->getParameter(), E->getReplacement());
7573   if (!Imp)
7574     return Imp.takeError();
7575 
7576   QualType ToType;
7577   SourceLocation ToExprLoc;
7578   NonTypeTemplateParmDecl *ToParameter;
7579   Expr *ToReplacement;
7580   std::tie(ToType, ToExprLoc, ToParameter, ToReplacement) = *Imp;
7581 
7582   return new (Importer.getToContext()) SubstNonTypeTemplateParmExpr(
7583       ToType, E->getValueKind(), ToExprLoc, ToParameter, ToReplacement);
7584 }
7585 
7586 ExpectedStmt ASTNodeImporter::VisitTypeTraitExpr(TypeTraitExpr *E) {
7587   auto Imp = importSeq(
7588       E->getType(), E->getBeginLoc(), E->getEndLoc());
7589   if (!Imp)
7590     return Imp.takeError();
7591 
7592   QualType ToType;
7593   SourceLocation ToBeginLoc, ToEndLoc;
7594   std::tie(ToType, ToBeginLoc, ToEndLoc) = *Imp;
7595 
7596   SmallVector<TypeSourceInfo *, 4> ToArgs(E->getNumArgs());
7597   if (Error Err = ImportContainerChecked(E->getArgs(), ToArgs))
7598     return std::move(Err);
7599 
7600   // According to Sema::BuildTypeTrait(), if E is value-dependent,
7601   // Value is always false.
7602   bool ToValue = (E->isValueDependent() ? false : E->getValue());
7603 
7604   return TypeTraitExpr::Create(
7605       Importer.getToContext(), ToType, ToBeginLoc, E->getTrait(), ToArgs,
7606       ToEndLoc, ToValue);
7607 }
7608 
7609 ExpectedStmt ASTNodeImporter::VisitCXXTypeidExpr(CXXTypeidExpr *E) {
7610   ExpectedType ToTypeOrErr = import(E->getType());
7611   if (!ToTypeOrErr)
7612     return ToTypeOrErr.takeError();
7613 
7614   auto ToSourceRangeOrErr = import(E->getSourceRange());
7615   if (!ToSourceRangeOrErr)
7616     return ToSourceRangeOrErr.takeError();
7617 
7618   if (E->isTypeOperand()) {
7619     if (auto ToTSIOrErr = import(E->getTypeOperandSourceInfo()))
7620       return new (Importer.getToContext()) CXXTypeidExpr(
7621           *ToTypeOrErr, *ToTSIOrErr, *ToSourceRangeOrErr);
7622     else
7623       return ToTSIOrErr.takeError();
7624   }
7625 
7626   ExpectedExpr ToExprOperandOrErr = import(E->getExprOperand());
7627   if (!ToExprOperandOrErr)
7628     return ToExprOperandOrErr.takeError();
7629 
7630   return new (Importer.getToContext()) CXXTypeidExpr(
7631       *ToTypeOrErr, *ToExprOperandOrErr, *ToSourceRangeOrErr);
7632 }
7633 
7634 void ASTNodeImporter::ImportOverrides(CXXMethodDecl *ToMethod,
7635                                       CXXMethodDecl *FromMethod) {
7636   for (auto *FromOverriddenMethod : FromMethod->overridden_methods()) {
7637     if (auto ImportedOrErr = import(FromOverriddenMethod))
7638       ToMethod->getCanonicalDecl()->addOverriddenMethod(cast<CXXMethodDecl>(
7639           (*ImportedOrErr)->getCanonicalDecl()));
7640     else
7641       consumeError(ImportedOrErr.takeError());
7642   }
7643 }
7644 
7645 ASTImporter::ASTImporter(ASTContext &ToContext, FileManager &ToFileManager,
7646                          ASTContext &FromContext, FileManager &FromFileManager,
7647                          bool MinimalImport)
7648     : ToContext(ToContext), FromContext(FromContext),
7649       ToFileManager(ToFileManager), FromFileManager(FromFileManager),
7650       Minimal(MinimalImport) {
7651   ImportedDecls[FromContext.getTranslationUnitDecl()]
7652     = ToContext.getTranslationUnitDecl();
7653 }
7654 
7655 ASTImporter::~ASTImporter() = default;
7656 
7657 QualType ASTImporter::Import(QualType FromT) {
7658   if (FromT.isNull())
7659     return {};
7660 
7661   const Type *FromTy = FromT.getTypePtr();
7662 
7663   // Check whether we've already imported this type.
7664   llvm::DenseMap<const Type *, const Type *>::iterator Pos
7665     = ImportedTypes.find(FromTy);
7666   if (Pos != ImportedTypes.end())
7667     return ToContext.getQualifiedType(Pos->second, FromT.getLocalQualifiers());
7668 
7669   // Import the type
7670   ASTNodeImporter Importer(*this);
7671   ExpectedType ToTOrErr = Importer.Visit(FromTy);
7672   if (!ToTOrErr) {
7673     llvm::consumeError(ToTOrErr.takeError());
7674     return {};
7675   }
7676 
7677   // Record the imported type.
7678   ImportedTypes[FromTy] = (*ToTOrErr).getTypePtr();
7679 
7680   return ToContext.getQualifiedType(*ToTOrErr, FromT.getLocalQualifiers());
7681 }
7682 
7683 TypeSourceInfo *ASTImporter::Import(TypeSourceInfo *FromTSI) {
7684   if (!FromTSI)
7685     return FromTSI;
7686 
7687   // FIXME: For now we just create a "trivial" type source info based
7688   // on the type and a single location. Implement a real version of this.
7689   QualType T = Import(FromTSI->getType());
7690   if (T.isNull())
7691     return nullptr;
7692 
7693   return ToContext.getTrivialTypeSourceInfo(
7694       T, Import(FromTSI->getTypeLoc().getBeginLoc()));
7695 }
7696 
7697 Attr *ASTImporter::Import(const Attr *FromAttr) {
7698   Attr *ToAttr = FromAttr->clone(ToContext);
7699   ToAttr->setRange(Import(FromAttr->getRange()));
7700   return ToAttr;
7701 }
7702 
7703 Decl *ASTImporter::GetAlreadyImportedOrNull(Decl *FromD) {
7704   llvm::DenseMap<Decl *, Decl *>::iterator Pos = ImportedDecls.find(FromD);
7705   if (Pos != ImportedDecls.end()) {
7706     Decl *ToD = Pos->second;
7707     // FIXME: move this call to ImportDeclParts().
7708     if (Error Err = ASTNodeImporter(*this).ImportDefinitionIfNeeded(FromD, ToD))
7709       llvm::consumeError(std::move(Err));
7710     return ToD;
7711   } else {
7712     return nullptr;
7713   }
7714 }
7715 
7716 Decl *ASTImporter::Import(Decl *FromD) {
7717   if (!FromD)
7718     return nullptr;
7719 
7720   ASTNodeImporter Importer(*this);
7721 
7722   // Check whether we've already imported this declaration.
7723   Decl *ToD = GetAlreadyImportedOrNull(FromD);
7724   if (ToD) {
7725     // If FromD has some updated flags after last import, apply it
7726     updateFlags(FromD, ToD);
7727     return ToD;
7728   }
7729 
7730   // Import the type.
7731   ExpectedDecl ToDOrErr = Importer.Visit(FromD);
7732   if (!ToDOrErr) {
7733     llvm::consumeError(ToDOrErr.takeError());
7734     return nullptr;
7735   }
7736   ToD = *ToDOrErr;
7737 
7738   // Notify subclasses.
7739   Imported(FromD, ToD);
7740 
7741   updateFlags(FromD, ToD);
7742   return ToD;
7743 }
7744 
7745 Expected<DeclContext *> ASTImporter::ImportContext(DeclContext *FromDC) {
7746   if (!FromDC)
7747     return FromDC;
7748 
7749   auto *ToDC = cast_or_null<DeclContext>(Import(cast<Decl>(FromDC)));
7750   if (!ToDC)
7751     return nullptr;
7752 
7753   // When we're using a record/enum/Objective-C class/protocol as a context, we
7754   // need it to have a definition.
7755   if (auto *ToRecord = dyn_cast<RecordDecl>(ToDC)) {
7756     auto *FromRecord = cast<RecordDecl>(FromDC);
7757     if (ToRecord->isCompleteDefinition()) {
7758       // Do nothing.
7759     } else if (FromRecord->isCompleteDefinition()) {
7760       if (Error Err = ASTNodeImporter(*this).ImportDefinition(
7761           FromRecord, ToRecord, ASTNodeImporter::IDK_Basic))
7762         return std::move(Err);
7763     } else {
7764       CompleteDecl(ToRecord);
7765     }
7766   } else if (auto *ToEnum = dyn_cast<EnumDecl>(ToDC)) {
7767     auto *FromEnum = cast<EnumDecl>(FromDC);
7768     if (ToEnum->isCompleteDefinition()) {
7769       // Do nothing.
7770     } else if (FromEnum->isCompleteDefinition()) {
7771       if (Error Err = ASTNodeImporter(*this).ImportDefinition(
7772           FromEnum, ToEnum, ASTNodeImporter::IDK_Basic))
7773         return std::move(Err);
7774     } else {
7775       CompleteDecl(ToEnum);
7776     }
7777   } else if (auto *ToClass = dyn_cast<ObjCInterfaceDecl>(ToDC)) {
7778     auto *FromClass = cast<ObjCInterfaceDecl>(FromDC);
7779     if (ToClass->getDefinition()) {
7780       // Do nothing.
7781     } else if (ObjCInterfaceDecl *FromDef = FromClass->getDefinition()) {
7782       if (Error Err = ASTNodeImporter(*this).ImportDefinition(
7783           FromDef, ToClass, ASTNodeImporter::IDK_Basic))
7784         return std::move(Err);
7785     } else {
7786       CompleteDecl(ToClass);
7787     }
7788   } else if (auto *ToProto = dyn_cast<ObjCProtocolDecl>(ToDC)) {
7789     auto *FromProto = cast<ObjCProtocolDecl>(FromDC);
7790     if (ToProto->getDefinition()) {
7791       // Do nothing.
7792     } else if (ObjCProtocolDecl *FromDef = FromProto->getDefinition()) {
7793       if (Error Err = ASTNodeImporter(*this).ImportDefinition(
7794           FromDef, ToProto, ASTNodeImporter::IDK_Basic))
7795         return std::move(Err);
7796     } else {
7797       CompleteDecl(ToProto);
7798     }
7799   }
7800 
7801   return ToDC;
7802 }
7803 
7804 Expr *ASTImporter::Import(Expr *FromE) {
7805   if (!FromE)
7806     return nullptr;
7807 
7808   return cast_or_null<Expr>(Import(cast<Stmt>(FromE)));
7809 }
7810 
7811 Stmt *ASTImporter::Import(Stmt *FromS) {
7812   if (!FromS)
7813     return nullptr;
7814 
7815   // Check whether we've already imported this declaration.
7816   llvm::DenseMap<Stmt *, Stmt *>::iterator Pos = ImportedStmts.find(FromS);
7817   if (Pos != ImportedStmts.end())
7818     return Pos->second;
7819 
7820   // Import the statement.
7821   ASTNodeImporter Importer(*this);
7822   ExpectedStmt ToSOrErr = Importer.Visit(FromS);
7823   if (!ToSOrErr) {
7824     llvm::consumeError(ToSOrErr.takeError());
7825     return nullptr;
7826   }
7827 
7828   if (auto *ToE = dyn_cast<Expr>(*ToSOrErr)) {
7829     auto *FromE = cast<Expr>(FromS);
7830     // Copy ExprBitfields, which may not be handled in Expr subclasses
7831     // constructors.
7832     ToE->setValueKind(FromE->getValueKind());
7833     ToE->setObjectKind(FromE->getObjectKind());
7834     ToE->setTypeDependent(FromE->isTypeDependent());
7835     ToE->setValueDependent(FromE->isValueDependent());
7836     ToE->setInstantiationDependent(FromE->isInstantiationDependent());
7837     ToE->setContainsUnexpandedParameterPack(
7838         FromE->containsUnexpandedParameterPack());
7839   }
7840 
7841   // Record the imported declaration.
7842   ImportedStmts[FromS] = *ToSOrErr;
7843   return *ToSOrErr;
7844 }
7845 
7846 NestedNameSpecifier *ASTImporter::Import(NestedNameSpecifier *FromNNS) {
7847   if (!FromNNS)
7848     return nullptr;
7849 
7850   NestedNameSpecifier *prefix = Import(FromNNS->getPrefix());
7851 
7852   switch (FromNNS->getKind()) {
7853   case NestedNameSpecifier::Identifier:
7854     if (IdentifierInfo *II = Import(FromNNS->getAsIdentifier())) {
7855       return NestedNameSpecifier::Create(ToContext, prefix, II);
7856     }
7857     return nullptr;
7858 
7859   case NestedNameSpecifier::Namespace:
7860     if (auto *NS =
7861             cast_or_null<NamespaceDecl>(Import(FromNNS->getAsNamespace()))) {
7862       return NestedNameSpecifier::Create(ToContext, prefix, NS);
7863     }
7864     return nullptr;
7865 
7866   case NestedNameSpecifier::NamespaceAlias:
7867     if (auto *NSAD =
7868           cast_or_null<NamespaceAliasDecl>(Import(FromNNS->getAsNamespaceAlias()))) {
7869       return NestedNameSpecifier::Create(ToContext, prefix, NSAD);
7870     }
7871     return nullptr;
7872 
7873   case NestedNameSpecifier::Global:
7874     return NestedNameSpecifier::GlobalSpecifier(ToContext);
7875 
7876   case NestedNameSpecifier::Super:
7877     if (auto *RD =
7878             cast_or_null<CXXRecordDecl>(Import(FromNNS->getAsRecordDecl()))) {
7879       return NestedNameSpecifier::SuperSpecifier(ToContext, RD);
7880     }
7881     return nullptr;
7882 
7883   case NestedNameSpecifier::TypeSpec:
7884   case NestedNameSpecifier::TypeSpecWithTemplate: {
7885       QualType T = Import(QualType(FromNNS->getAsType(), 0u));
7886       if (!T.isNull()) {
7887         bool bTemplate = FromNNS->getKind() ==
7888                          NestedNameSpecifier::TypeSpecWithTemplate;
7889         return NestedNameSpecifier::Create(ToContext, prefix,
7890                                            bTemplate, T.getTypePtr());
7891       }
7892     }
7893       return nullptr;
7894   }
7895 
7896   llvm_unreachable("Invalid nested name specifier kind");
7897 }
7898 
7899 NestedNameSpecifierLoc ASTImporter::Import(NestedNameSpecifierLoc FromNNS) {
7900   // Copied from NestedNameSpecifier mostly.
7901   SmallVector<NestedNameSpecifierLoc , 8> NestedNames;
7902   NestedNameSpecifierLoc NNS = FromNNS;
7903 
7904   // Push each of the nested-name-specifiers's onto a stack for
7905   // serialization in reverse order.
7906   while (NNS) {
7907     NestedNames.push_back(NNS);
7908     NNS = NNS.getPrefix();
7909   }
7910 
7911   NestedNameSpecifierLocBuilder Builder;
7912 
7913   while (!NestedNames.empty()) {
7914     NNS = NestedNames.pop_back_val();
7915     NestedNameSpecifier *Spec = Import(NNS.getNestedNameSpecifier());
7916     if (!Spec)
7917       return NestedNameSpecifierLoc();
7918 
7919     NestedNameSpecifier::SpecifierKind Kind = Spec->getKind();
7920     switch (Kind) {
7921     case NestedNameSpecifier::Identifier:
7922       Builder.Extend(getToContext(),
7923                      Spec->getAsIdentifier(),
7924                      Import(NNS.getLocalBeginLoc()),
7925                      Import(NNS.getLocalEndLoc()));
7926       break;
7927 
7928     case NestedNameSpecifier::Namespace:
7929       Builder.Extend(getToContext(),
7930                      Spec->getAsNamespace(),
7931                      Import(NNS.getLocalBeginLoc()),
7932                      Import(NNS.getLocalEndLoc()));
7933       break;
7934 
7935     case NestedNameSpecifier::NamespaceAlias:
7936       Builder.Extend(getToContext(),
7937                      Spec->getAsNamespaceAlias(),
7938                      Import(NNS.getLocalBeginLoc()),
7939                      Import(NNS.getLocalEndLoc()));
7940       break;
7941 
7942     case NestedNameSpecifier::TypeSpec:
7943     case NestedNameSpecifier::TypeSpecWithTemplate: {
7944       TypeSourceInfo *TSI = getToContext().getTrivialTypeSourceInfo(
7945             QualType(Spec->getAsType(), 0));
7946       Builder.Extend(getToContext(),
7947                      Import(NNS.getLocalBeginLoc()),
7948                      TSI->getTypeLoc(),
7949                      Import(NNS.getLocalEndLoc()));
7950       break;
7951     }
7952 
7953     case NestedNameSpecifier::Global:
7954       Builder.MakeGlobal(getToContext(), Import(NNS.getLocalBeginLoc()));
7955       break;
7956 
7957     case NestedNameSpecifier::Super: {
7958       SourceRange ToRange = Import(NNS.getSourceRange());
7959       Builder.MakeSuper(getToContext(),
7960                         Spec->getAsRecordDecl(),
7961                         ToRange.getBegin(),
7962                         ToRange.getEnd());
7963     }
7964   }
7965   }
7966 
7967   return Builder.getWithLocInContext(getToContext());
7968 }
7969 
7970 TemplateName ASTImporter::Import(TemplateName From) {
7971   switch (From.getKind()) {
7972   case TemplateName::Template:
7973     if (auto *ToTemplate =
7974             cast_or_null<TemplateDecl>(Import(From.getAsTemplateDecl())))
7975       return TemplateName(ToTemplate);
7976 
7977     return {};
7978 
7979   case TemplateName::OverloadedTemplate: {
7980     OverloadedTemplateStorage *FromStorage = From.getAsOverloadedTemplate();
7981     UnresolvedSet<2> ToTemplates;
7982     for (auto *I : *FromStorage) {
7983       if (auto *To = cast_or_null<NamedDecl>(Import(I)))
7984         ToTemplates.addDecl(To);
7985       else
7986         return {};
7987     }
7988     return ToContext.getOverloadedTemplateName(ToTemplates.begin(),
7989                                                ToTemplates.end());
7990   }
7991 
7992   case TemplateName::QualifiedTemplate: {
7993     QualifiedTemplateName *QTN = From.getAsQualifiedTemplateName();
7994     NestedNameSpecifier *Qualifier = Import(QTN->getQualifier());
7995     if (!Qualifier)
7996       return {};
7997 
7998     if (auto *ToTemplate =
7999             cast_or_null<TemplateDecl>(Import(From.getAsTemplateDecl())))
8000       return ToContext.getQualifiedTemplateName(Qualifier,
8001                                                 QTN->hasTemplateKeyword(),
8002                                                 ToTemplate);
8003 
8004     return {};
8005   }
8006 
8007   case TemplateName::DependentTemplate: {
8008     DependentTemplateName *DTN = From.getAsDependentTemplateName();
8009     NestedNameSpecifier *Qualifier = Import(DTN->getQualifier());
8010     if (!Qualifier)
8011       return {};
8012 
8013     if (DTN->isIdentifier()) {
8014       return ToContext.getDependentTemplateName(Qualifier,
8015                                                 Import(DTN->getIdentifier()));
8016     }
8017 
8018     return ToContext.getDependentTemplateName(Qualifier, DTN->getOperator());
8019   }
8020 
8021   case TemplateName::SubstTemplateTemplateParm: {
8022     SubstTemplateTemplateParmStorage *subst
8023       = From.getAsSubstTemplateTemplateParm();
8024     auto *param =
8025         cast_or_null<TemplateTemplateParmDecl>(Import(subst->getParameter()));
8026     if (!param)
8027       return {};
8028 
8029     TemplateName replacement = Import(subst->getReplacement());
8030     if (replacement.isNull())
8031       return {};
8032 
8033     return ToContext.getSubstTemplateTemplateParm(param, replacement);
8034   }
8035 
8036   case TemplateName::SubstTemplateTemplateParmPack: {
8037     SubstTemplateTemplateParmPackStorage *SubstPack
8038       = From.getAsSubstTemplateTemplateParmPack();
8039     auto *Param =
8040         cast_or_null<TemplateTemplateParmDecl>(
8041             Import(SubstPack->getParameterPack()));
8042     if (!Param)
8043       return {};
8044 
8045     ASTNodeImporter Importer(*this);
8046     Expected<TemplateArgument> ArgPack
8047       = Importer.ImportTemplateArgument(SubstPack->getArgumentPack());
8048     if (!ArgPack) {
8049       llvm::consumeError(ArgPack.takeError());
8050       return {};
8051     }
8052 
8053     return ToContext.getSubstTemplateTemplateParmPack(Param, *ArgPack);
8054   }
8055   }
8056 
8057   llvm_unreachable("Invalid template name kind");
8058 }
8059 
8060 SourceLocation ASTImporter::Import(SourceLocation FromLoc) {
8061   if (FromLoc.isInvalid())
8062     return {};
8063 
8064   SourceManager &FromSM = FromContext.getSourceManager();
8065 
8066   std::pair<FileID, unsigned> Decomposed = FromSM.getDecomposedLoc(FromLoc);
8067   FileID ToFileID = Import(Decomposed.first);
8068   if (ToFileID.isInvalid())
8069     return {};
8070   SourceManager &ToSM = ToContext.getSourceManager();
8071   return ToSM.getComposedLoc(ToFileID, Decomposed.second);
8072 }
8073 
8074 SourceRange ASTImporter::Import(SourceRange FromRange) {
8075   return SourceRange(Import(FromRange.getBegin()), Import(FromRange.getEnd()));
8076 }
8077 
8078 FileID ASTImporter::Import(FileID FromID) {
8079   llvm::DenseMap<FileID, FileID>::iterator Pos = ImportedFileIDs.find(FromID);
8080   if (Pos != ImportedFileIDs.end())
8081     return Pos->second;
8082 
8083   SourceManager &FromSM = FromContext.getSourceManager();
8084   SourceManager &ToSM = ToContext.getSourceManager();
8085   const SrcMgr::SLocEntry &FromSLoc = FromSM.getSLocEntry(FromID);
8086 
8087   // Map the FromID to the "to" source manager.
8088   FileID ToID;
8089   if (FromSLoc.isExpansion()) {
8090     const SrcMgr::ExpansionInfo &FromEx = FromSLoc.getExpansion();
8091     SourceLocation ToSpLoc = Import(FromEx.getSpellingLoc());
8092     SourceLocation ToExLocS = Import(FromEx.getExpansionLocStart());
8093     unsigned TokenLen = FromSM.getFileIDSize(FromID);
8094     SourceLocation MLoc;
8095     if (FromEx.isMacroArgExpansion()) {
8096       MLoc = ToSM.createMacroArgExpansionLoc(ToSpLoc, ToExLocS, TokenLen);
8097     } else {
8098       SourceLocation ToExLocE = Import(FromEx.getExpansionLocEnd());
8099       MLoc = ToSM.createExpansionLoc(ToSpLoc, ToExLocS, ToExLocE, TokenLen,
8100                                      FromEx.isExpansionTokenRange());
8101     }
8102     ToID = ToSM.getFileID(MLoc);
8103   } else {
8104     // Include location of this file.
8105     SourceLocation ToIncludeLoc = Import(FromSLoc.getFile().getIncludeLoc());
8106 
8107     const SrcMgr::ContentCache *Cache = FromSLoc.getFile().getContentCache();
8108     if (Cache->OrigEntry && Cache->OrigEntry->getDir()) {
8109       // FIXME: We probably want to use getVirtualFile(), so we don't hit the
8110       // disk again
8111       // FIXME: We definitely want to re-use the existing MemoryBuffer, rather
8112       // than mmap the files several times.
8113       const FileEntry *Entry =
8114           ToFileManager.getFile(Cache->OrigEntry->getName());
8115       if (!Entry)
8116         return {};
8117       ToID = ToSM.createFileID(Entry, ToIncludeLoc,
8118                                FromSLoc.getFile().getFileCharacteristic());
8119     } else {
8120       // FIXME: We want to re-use the existing MemoryBuffer!
8121       const llvm::MemoryBuffer *FromBuf =
8122           Cache->getBuffer(FromContext.getDiagnostics(), FromSM);
8123       std::unique_ptr<llvm::MemoryBuffer> ToBuf =
8124           llvm::MemoryBuffer::getMemBufferCopy(FromBuf->getBuffer(),
8125                                                FromBuf->getBufferIdentifier());
8126       ToID = ToSM.createFileID(std::move(ToBuf),
8127                                FromSLoc.getFile().getFileCharacteristic());
8128     }
8129   }
8130 
8131   ImportedFileIDs[FromID] = ToID;
8132   return ToID;
8133 }
8134 
8135 CXXCtorInitializer *ASTImporter::Import(CXXCtorInitializer *From) {
8136   Expr *ToExpr = Import(From->getInit());
8137   if (!ToExpr && From->getInit())
8138     return nullptr;
8139 
8140   if (From->isBaseInitializer()) {
8141     TypeSourceInfo *ToTInfo = Import(From->getTypeSourceInfo());
8142     if (!ToTInfo && From->getTypeSourceInfo())
8143       return nullptr;
8144 
8145     return new (ToContext) CXXCtorInitializer(
8146         ToContext, ToTInfo, From->isBaseVirtual(), Import(From->getLParenLoc()),
8147         ToExpr, Import(From->getRParenLoc()),
8148         From->isPackExpansion() ? Import(From->getEllipsisLoc())
8149                                 : SourceLocation());
8150   } else if (From->isMemberInitializer()) {
8151     auto *ToField = cast_or_null<FieldDecl>(Import(From->getMember()));
8152     if (!ToField && From->getMember())
8153       return nullptr;
8154 
8155     return new (ToContext) CXXCtorInitializer(
8156         ToContext, ToField, Import(From->getMemberLocation()),
8157         Import(From->getLParenLoc()), ToExpr, Import(From->getRParenLoc()));
8158   } else if (From->isIndirectMemberInitializer()) {
8159     auto *ToIField = cast_or_null<IndirectFieldDecl>(
8160         Import(From->getIndirectMember()));
8161     if (!ToIField && From->getIndirectMember())
8162       return nullptr;
8163 
8164     return new (ToContext) CXXCtorInitializer(
8165         ToContext, ToIField, Import(From->getMemberLocation()),
8166         Import(From->getLParenLoc()), ToExpr, Import(From->getRParenLoc()));
8167   } else if (From->isDelegatingInitializer()) {
8168     TypeSourceInfo *ToTInfo = Import(From->getTypeSourceInfo());
8169     if (!ToTInfo && From->getTypeSourceInfo())
8170       return nullptr;
8171 
8172     return new (ToContext)
8173         CXXCtorInitializer(ToContext, ToTInfo, Import(From->getLParenLoc()),
8174                            ToExpr, Import(From->getRParenLoc()));
8175   } else {
8176     return nullptr;
8177   }
8178 }
8179 
8180 CXXBaseSpecifier *ASTImporter::Import(const CXXBaseSpecifier *BaseSpec) {
8181   auto Pos = ImportedCXXBaseSpecifiers.find(BaseSpec);
8182   if (Pos != ImportedCXXBaseSpecifiers.end())
8183     return Pos->second;
8184 
8185   CXXBaseSpecifier *Imported = new (ToContext) CXXBaseSpecifier(
8186         Import(BaseSpec->getSourceRange()),
8187         BaseSpec->isVirtual(), BaseSpec->isBaseOfClass(),
8188         BaseSpec->getAccessSpecifierAsWritten(),
8189         Import(BaseSpec->getTypeSourceInfo()),
8190         Import(BaseSpec->getEllipsisLoc()));
8191   ImportedCXXBaseSpecifiers[BaseSpec] = Imported;
8192   return Imported;
8193 }
8194 
8195 Error ASTImporter::ImportDefinition_New(Decl *From) {
8196   Decl *To = Import(From);
8197   if (!To)
8198     return llvm::make_error<ImportError>();
8199 
8200   if (auto *FromDC = cast<DeclContext>(From)) {
8201     ASTNodeImporter Importer(*this);
8202 
8203     if (auto *ToRecord = dyn_cast<RecordDecl>(To)) {
8204       if (!ToRecord->getDefinition()) {
8205         return Importer.ImportDefinition(
8206             cast<RecordDecl>(FromDC), ToRecord,
8207             ASTNodeImporter::IDK_Everything);
8208       }
8209     }
8210 
8211     if (auto *ToEnum = dyn_cast<EnumDecl>(To)) {
8212       if (!ToEnum->getDefinition()) {
8213         return Importer.ImportDefinition(
8214             cast<EnumDecl>(FromDC), ToEnum, ASTNodeImporter::IDK_Everything);
8215       }
8216     }
8217 
8218     if (auto *ToIFace = dyn_cast<ObjCInterfaceDecl>(To)) {
8219       if (!ToIFace->getDefinition()) {
8220         return Importer.ImportDefinition(
8221             cast<ObjCInterfaceDecl>(FromDC), ToIFace,
8222             ASTNodeImporter::IDK_Everything);
8223       }
8224     }
8225 
8226     if (auto *ToProto = dyn_cast<ObjCProtocolDecl>(To)) {
8227       if (!ToProto->getDefinition()) {
8228         return Importer.ImportDefinition(
8229             cast<ObjCProtocolDecl>(FromDC), ToProto,
8230             ASTNodeImporter::IDK_Everything);
8231       }
8232     }
8233 
8234     return Importer.ImportDeclContext(FromDC, true);
8235   }
8236 
8237   return Error::success();
8238 }
8239 
8240 void ASTImporter::ImportDefinition(Decl *From) {
8241   Error Err = ImportDefinition_New(From);
8242   llvm::consumeError(std::move(Err));
8243 }
8244 
8245 DeclarationName ASTImporter::Import(DeclarationName FromName) {
8246   if (!FromName)
8247     return {};
8248 
8249   switch (FromName.getNameKind()) {
8250   case DeclarationName::Identifier:
8251     return Import(FromName.getAsIdentifierInfo());
8252 
8253   case DeclarationName::ObjCZeroArgSelector:
8254   case DeclarationName::ObjCOneArgSelector:
8255   case DeclarationName::ObjCMultiArgSelector:
8256     return Import(FromName.getObjCSelector());
8257 
8258   case DeclarationName::CXXConstructorName: {
8259     QualType T = Import(FromName.getCXXNameType());
8260     if (T.isNull())
8261       return {};
8262 
8263     return ToContext.DeclarationNames.getCXXConstructorName(
8264                                                ToContext.getCanonicalType(T));
8265   }
8266 
8267   case DeclarationName::CXXDestructorName: {
8268     QualType T = Import(FromName.getCXXNameType());
8269     if (T.isNull())
8270       return {};
8271 
8272     return ToContext.DeclarationNames.getCXXDestructorName(
8273                                                ToContext.getCanonicalType(T));
8274   }
8275 
8276   case DeclarationName::CXXDeductionGuideName: {
8277     auto *Template = cast_or_null<TemplateDecl>(
8278         Import(FromName.getCXXDeductionGuideTemplate()));
8279     if (!Template)
8280       return {};
8281     return ToContext.DeclarationNames.getCXXDeductionGuideName(Template);
8282   }
8283 
8284   case DeclarationName::CXXConversionFunctionName: {
8285     QualType T = Import(FromName.getCXXNameType());
8286     if (T.isNull())
8287       return {};
8288 
8289     return ToContext.DeclarationNames.getCXXConversionFunctionName(
8290                                                ToContext.getCanonicalType(T));
8291   }
8292 
8293   case DeclarationName::CXXOperatorName:
8294     return ToContext.DeclarationNames.getCXXOperatorName(
8295                                           FromName.getCXXOverloadedOperator());
8296 
8297   case DeclarationName::CXXLiteralOperatorName:
8298     return ToContext.DeclarationNames.getCXXLiteralOperatorName(
8299                                    Import(FromName.getCXXLiteralIdentifier()));
8300 
8301   case DeclarationName::CXXUsingDirective:
8302     // FIXME: STATICS!
8303     return DeclarationName::getUsingDirectiveName();
8304   }
8305 
8306   llvm_unreachable("Invalid DeclarationName Kind!");
8307 }
8308 
8309 IdentifierInfo *ASTImporter::Import(const IdentifierInfo *FromId) {
8310   if (!FromId)
8311     return nullptr;
8312 
8313   IdentifierInfo *ToId = &ToContext.Idents.get(FromId->getName());
8314 
8315   if (!ToId->getBuiltinID() && FromId->getBuiltinID())
8316     ToId->setBuiltinID(FromId->getBuiltinID());
8317 
8318   return ToId;
8319 }
8320 
8321 Selector ASTImporter::Import(Selector FromSel) {
8322   if (FromSel.isNull())
8323     return {};
8324 
8325   SmallVector<IdentifierInfo *, 4> Idents;
8326   Idents.push_back(Import(FromSel.getIdentifierInfoForSlot(0)));
8327   for (unsigned I = 1, N = FromSel.getNumArgs(); I < N; ++I)
8328     Idents.push_back(Import(FromSel.getIdentifierInfoForSlot(I)));
8329   return ToContext.Selectors.getSelector(FromSel.getNumArgs(), Idents.data());
8330 }
8331 
8332 DeclarationName ASTImporter::HandleNameConflict(DeclarationName Name,
8333                                                 DeclContext *DC,
8334                                                 unsigned IDNS,
8335                                                 NamedDecl **Decls,
8336                                                 unsigned NumDecls) {
8337   return Name;
8338 }
8339 
8340 DiagnosticBuilder ASTImporter::ToDiag(SourceLocation Loc, unsigned DiagID) {
8341   if (LastDiagFromFrom)
8342     ToContext.getDiagnostics().notePriorDiagnosticFrom(
8343       FromContext.getDiagnostics());
8344   LastDiagFromFrom = false;
8345   return ToContext.getDiagnostics().Report(Loc, DiagID);
8346 }
8347 
8348 DiagnosticBuilder ASTImporter::FromDiag(SourceLocation Loc, unsigned DiagID) {
8349   if (!LastDiagFromFrom)
8350     FromContext.getDiagnostics().notePriorDiagnosticFrom(
8351       ToContext.getDiagnostics());
8352   LastDiagFromFrom = true;
8353   return FromContext.getDiagnostics().Report(Loc, DiagID);
8354 }
8355 
8356 void ASTImporter::CompleteDecl (Decl *D) {
8357   if (auto *ID = dyn_cast<ObjCInterfaceDecl>(D)) {
8358     if (!ID->getDefinition())
8359       ID->startDefinition();
8360   }
8361   else if (auto *PD = dyn_cast<ObjCProtocolDecl>(D)) {
8362     if (!PD->getDefinition())
8363       PD->startDefinition();
8364   }
8365   else if (auto *TD = dyn_cast<TagDecl>(D)) {
8366     if (!TD->getDefinition() && !TD->isBeingDefined()) {
8367       TD->startDefinition();
8368       TD->setCompleteDefinition(true);
8369     }
8370   }
8371   else {
8372     assert(0 && "CompleteDecl called on a Decl that can't be completed");
8373   }
8374 }
8375 
8376 Decl *ASTImporter::MapImported(Decl *From, Decl *To) {
8377   llvm::DenseMap<Decl *, Decl *>::iterator Pos = ImportedDecls.find(From);
8378   assert((Pos == ImportedDecls.end() || Pos->second == To) &&
8379       "Try to import an already imported Decl");
8380   if (Pos != ImportedDecls.end())
8381     return Pos->second;
8382   ImportedDecls[From] = To;
8383   return To;
8384 }
8385 
8386 bool ASTImporter::IsStructurallyEquivalent(QualType From, QualType To,
8387                                            bool Complain) {
8388   llvm::DenseMap<const Type *, const Type *>::iterator Pos
8389    = ImportedTypes.find(From.getTypePtr());
8390   if (Pos != ImportedTypes.end() && ToContext.hasSameType(Import(From), To))
8391     return true;
8392 
8393   StructuralEquivalenceContext Ctx(FromContext, ToContext, NonEquivalentDecls,
8394                                    getStructuralEquivalenceKind(*this), false,
8395                                    Complain);
8396   return Ctx.IsEquivalent(From, To);
8397 }
8398