1 //===--- ASTImporter.cpp - Importing ASTs from other Contexts ---*- C++ -*-===//
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 #include "clang/AST/ASTImporter.h"
15 #include "clang/AST/ASTContext.h"
16 #include "clang/AST/ASTDiagnostic.h"
17 #include "clang/AST/DeclCXX.h"
18 #include "clang/AST/DeclObjC.h"
19 #include "clang/AST/DeclVisitor.h"
20 #include "clang/AST/StmtVisitor.h"
21 #include "clang/AST/TypeVisitor.h"
22 #include "clang/Basic/FileManager.h"
23 #include "clang/Basic/SourceManager.h"
24 #include "llvm/Support/MemoryBuffer.h"
25 #include <deque>
26 
27 namespace clang {
28   class ASTNodeImporter : public TypeVisitor<ASTNodeImporter, QualType>,
29                           public DeclVisitor<ASTNodeImporter, Decl *>,
30                           public StmtVisitor<ASTNodeImporter, Stmt *> {
31     ASTImporter &Importer;
32 
33   public:
34     explicit ASTNodeImporter(ASTImporter &Importer) : Importer(Importer) { }
35 
36     using TypeVisitor<ASTNodeImporter, QualType>::Visit;
37     using DeclVisitor<ASTNodeImporter, Decl *>::Visit;
38     using StmtVisitor<ASTNodeImporter, Stmt *>::Visit;
39 
40     // Importing types
41     QualType VisitType(const Type *T);
42     QualType VisitBuiltinType(const BuiltinType *T);
43     QualType VisitComplexType(const ComplexType *T);
44     QualType VisitPointerType(const PointerType *T);
45     QualType VisitBlockPointerType(const BlockPointerType *T);
46     QualType VisitLValueReferenceType(const LValueReferenceType *T);
47     QualType VisitRValueReferenceType(const RValueReferenceType *T);
48     QualType VisitMemberPointerType(const MemberPointerType *T);
49     QualType VisitConstantArrayType(const ConstantArrayType *T);
50     QualType VisitIncompleteArrayType(const IncompleteArrayType *T);
51     QualType VisitVariableArrayType(const VariableArrayType *T);
52     // FIXME: DependentSizedArrayType
53     // FIXME: DependentSizedExtVectorType
54     QualType VisitVectorType(const VectorType *T);
55     QualType VisitExtVectorType(const ExtVectorType *T);
56     QualType VisitFunctionNoProtoType(const FunctionNoProtoType *T);
57     QualType VisitFunctionProtoType(const FunctionProtoType *T);
58     // FIXME: UnresolvedUsingType
59     QualType VisitParenType(const ParenType *T);
60     QualType VisitTypedefType(const TypedefType *T);
61     QualType VisitTypeOfExprType(const TypeOfExprType *T);
62     // FIXME: DependentTypeOfExprType
63     QualType VisitTypeOfType(const TypeOfType *T);
64     QualType VisitDecltypeType(const DecltypeType *T);
65     QualType VisitUnaryTransformType(const UnaryTransformType *T);
66     QualType VisitAutoType(const AutoType *T);
67     // FIXME: DependentDecltypeType
68     QualType VisitRecordType(const RecordType *T);
69     QualType VisitEnumType(const EnumType *T);
70     QualType VisitAttributedType(const AttributedType *T);
71     // FIXME: TemplateTypeParmType
72     // FIXME: SubstTemplateTypeParmType
73     QualType VisitTemplateSpecializationType(const TemplateSpecializationType *T);
74     QualType VisitElaboratedType(const ElaboratedType *T);
75     // FIXME: DependentNameType
76     // FIXME: DependentTemplateSpecializationType
77     QualType VisitObjCInterfaceType(const ObjCInterfaceType *T);
78     QualType VisitObjCObjectType(const ObjCObjectType *T);
79     QualType VisitObjCObjectPointerType(const ObjCObjectPointerType *T);
80 
81     // Importing declarations
82     bool ImportDeclParts(NamedDecl *D, DeclContext *&DC,
83                          DeclContext *&LexicalDC, DeclarationName &Name,
84                          NamedDecl *&ToD, SourceLocation &Loc);
85     void ImportDefinitionIfNeeded(Decl *FromD, Decl *ToD = nullptr);
86     void ImportDeclarationNameLoc(const DeclarationNameInfo &From,
87                                   DeclarationNameInfo& To);
88     void ImportDeclContext(DeclContext *FromDC, bool ForceImport = false);
89 
90     /// \brief What we should import from the definition.
91     enum ImportDefinitionKind {
92       /// \brief Import the default subset of the definition, which might be
93       /// nothing (if minimal import is set) or might be everything (if minimal
94       /// import is not set).
95       IDK_Default,
96       /// \brief Import everything.
97       IDK_Everything,
98       /// \brief Import only the bare bones needed to establish a valid
99       /// DeclContext.
100       IDK_Basic
101     };
102 
103     bool shouldForceImportDeclContext(ImportDefinitionKind IDK) {
104       return IDK == IDK_Everything ||
105              (IDK == IDK_Default && !Importer.isMinimalImport());
106     }
107 
108     bool ImportDefinition(RecordDecl *From, RecordDecl *To,
109                           ImportDefinitionKind Kind = IDK_Default);
110     bool ImportDefinition(VarDecl *From, VarDecl *To,
111                           ImportDefinitionKind Kind = IDK_Default);
112     bool ImportDefinition(EnumDecl *From, EnumDecl *To,
113                           ImportDefinitionKind Kind = IDK_Default);
114     bool ImportDefinition(ObjCInterfaceDecl *From, ObjCInterfaceDecl *To,
115                           ImportDefinitionKind Kind = IDK_Default);
116     bool ImportDefinition(ObjCProtocolDecl *From, ObjCProtocolDecl *To,
117                           ImportDefinitionKind Kind = IDK_Default);
118     TemplateParameterList *ImportTemplateParameterList(
119                                                  TemplateParameterList *Params);
120     TemplateArgument ImportTemplateArgument(const TemplateArgument &From);
121     bool ImportTemplateArguments(const TemplateArgument *FromArgs,
122                                  unsigned NumFromArgs,
123                                SmallVectorImpl<TemplateArgument> &ToArgs);
124     bool IsStructuralMatch(RecordDecl *FromRecord, RecordDecl *ToRecord,
125                            bool Complain = true);
126     bool IsStructuralMatch(VarDecl *FromVar, VarDecl *ToVar,
127                            bool Complain = true);
128     bool IsStructuralMatch(EnumDecl *FromEnum, EnumDecl *ToRecord);
129     bool IsStructuralMatch(EnumConstantDecl *FromEC, EnumConstantDecl *ToEC);
130     bool IsStructuralMatch(ClassTemplateDecl *From, ClassTemplateDecl *To);
131     bool IsStructuralMatch(VarTemplateDecl *From, VarTemplateDecl *To);
132     Decl *VisitDecl(Decl *D);
133     Decl *VisitTranslationUnitDecl(TranslationUnitDecl *D);
134     Decl *VisitNamespaceDecl(NamespaceDecl *D);
135     Decl *VisitTypedefNameDecl(TypedefNameDecl *D, bool IsAlias);
136     Decl *VisitTypedefDecl(TypedefDecl *D);
137     Decl *VisitTypeAliasDecl(TypeAliasDecl *D);
138     Decl *VisitEnumDecl(EnumDecl *D);
139     Decl *VisitRecordDecl(RecordDecl *D);
140     Decl *VisitEnumConstantDecl(EnumConstantDecl *D);
141     Decl *VisitFunctionDecl(FunctionDecl *D);
142     Decl *VisitCXXMethodDecl(CXXMethodDecl *D);
143     Decl *VisitCXXConstructorDecl(CXXConstructorDecl *D);
144     Decl *VisitCXXDestructorDecl(CXXDestructorDecl *D);
145     Decl *VisitCXXConversionDecl(CXXConversionDecl *D);
146     Decl *VisitFieldDecl(FieldDecl *D);
147     Decl *VisitIndirectFieldDecl(IndirectFieldDecl *D);
148     Decl *VisitObjCIvarDecl(ObjCIvarDecl *D);
149     Decl *VisitVarDecl(VarDecl *D);
150     Decl *VisitImplicitParamDecl(ImplicitParamDecl *D);
151     Decl *VisitParmVarDecl(ParmVarDecl *D);
152     Decl *VisitObjCMethodDecl(ObjCMethodDecl *D);
153     Decl *VisitObjCTypeParamDecl(ObjCTypeParamDecl *D);
154     Decl *VisitObjCCategoryDecl(ObjCCategoryDecl *D);
155     Decl *VisitObjCProtocolDecl(ObjCProtocolDecl *D);
156     Decl *VisitLinkageSpecDecl(LinkageSpecDecl *D);
157 
158     ObjCTypeParamList *ImportObjCTypeParamList(ObjCTypeParamList *list);
159     Decl *VisitObjCInterfaceDecl(ObjCInterfaceDecl *D);
160     Decl *VisitObjCCategoryImplDecl(ObjCCategoryImplDecl *D);
161     Decl *VisitObjCImplementationDecl(ObjCImplementationDecl *D);
162     Decl *VisitObjCPropertyDecl(ObjCPropertyDecl *D);
163     Decl *VisitObjCPropertyImplDecl(ObjCPropertyImplDecl *D);
164     Decl *VisitTemplateTypeParmDecl(TemplateTypeParmDecl *D);
165     Decl *VisitNonTypeTemplateParmDecl(NonTypeTemplateParmDecl *D);
166     Decl *VisitTemplateTemplateParmDecl(TemplateTemplateParmDecl *D);
167     Decl *VisitClassTemplateDecl(ClassTemplateDecl *D);
168     Decl *VisitClassTemplateSpecializationDecl(
169                                             ClassTemplateSpecializationDecl *D);
170     Decl *VisitVarTemplateDecl(VarTemplateDecl *D);
171     Decl *VisitVarTemplateSpecializationDecl(VarTemplateSpecializationDecl *D);
172 
173     // Importing statements
174     DeclGroupRef ImportDeclGroup(DeclGroupRef DG);
175 
176     Stmt *VisitStmt(Stmt *S);
177     Stmt *VisitDeclStmt(DeclStmt *S);
178     Stmt *VisitNullStmt(NullStmt *S);
179     Stmt *VisitCompoundStmt(CompoundStmt *S);
180     Stmt *VisitCaseStmt(CaseStmt *S);
181     Stmt *VisitDefaultStmt(DefaultStmt *S);
182     Stmt *VisitLabelStmt(LabelStmt *S);
183     Stmt *VisitAttributedStmt(AttributedStmt *S);
184     Stmt *VisitIfStmt(IfStmt *S);
185     Stmt *VisitSwitchStmt(SwitchStmt *S);
186     Stmt *VisitWhileStmt(WhileStmt *S);
187     Stmt *VisitDoStmt(DoStmt *S);
188     Stmt *VisitForStmt(ForStmt *S);
189     Stmt *VisitGotoStmt(GotoStmt *S);
190     Stmt *VisitIndirectGotoStmt(IndirectGotoStmt *S);
191     Stmt *VisitContinueStmt(ContinueStmt *S);
192     Stmt *VisitBreakStmt(BreakStmt *S);
193     Stmt *VisitReturnStmt(ReturnStmt *S);
194     // FIXME: GCCAsmStmt
195     // FIXME: MSAsmStmt
196     // FIXME: SEHExceptStmt
197     // FIXME: SEHFinallyStmt
198     // FIXME: SEHTryStmt
199     // FIXME: SEHLeaveStmt
200     // FIXME: CapturedStmt
201     Stmt *VisitCXXCatchStmt(CXXCatchStmt *S);
202     Stmt *VisitCXXTryStmt(CXXTryStmt *S);
203     Stmt *VisitCXXForRangeStmt(CXXForRangeStmt *S);
204     // FIXME: MSDependentExistsStmt
205     Stmt *VisitObjCForCollectionStmt(ObjCForCollectionStmt *S);
206     Stmt *VisitObjCAtCatchStmt(ObjCAtCatchStmt *S);
207     Stmt *VisitObjCAtFinallyStmt(ObjCAtFinallyStmt *S);
208     Stmt *VisitObjCAtTryStmt(ObjCAtTryStmt *S);
209     Stmt *VisitObjCAtSynchronizedStmt(ObjCAtSynchronizedStmt *S);
210     Stmt *VisitObjCAtThrowStmt(ObjCAtThrowStmt *S);
211     Stmt *VisitObjCAutoreleasePoolStmt(ObjCAutoreleasePoolStmt *S);
212 
213     // Importing expressions
214     Expr *VisitExpr(Expr *E);
215     Expr *VisitDeclRefExpr(DeclRefExpr *E);
216     Expr *VisitIntegerLiteral(IntegerLiteral *E);
217     Expr *VisitCharacterLiteral(CharacterLiteral *E);
218     Expr *VisitParenExpr(ParenExpr *E);
219     Expr *VisitUnaryOperator(UnaryOperator *E);
220     Expr *VisitUnaryExprOrTypeTraitExpr(UnaryExprOrTypeTraitExpr *E);
221     Expr *VisitBinaryOperator(BinaryOperator *E);
222     Expr *VisitCompoundAssignOperator(CompoundAssignOperator *E);
223     Expr *VisitImplicitCastExpr(ImplicitCastExpr *E);
224     Expr *VisitCStyleCastExpr(CStyleCastExpr *E);
225     Expr *VisitCXXConstructExpr(CXXConstructExpr *E);
226     Expr *VisitMemberExpr(MemberExpr *E);
227     Expr *VisitCallExpr(CallExpr *E);
228   };
229 }
230 using namespace clang;
231 
232 //----------------------------------------------------------------------------
233 // Structural Equivalence
234 //----------------------------------------------------------------------------
235 
236 namespace {
237   struct StructuralEquivalenceContext {
238     /// \brief AST contexts for which we are checking structural equivalence.
239     ASTContext &C1, &C2;
240 
241     /// \brief The set of "tentative" equivalences between two canonical
242     /// declarations, mapping from a declaration in the first context to the
243     /// declaration in the second context that we believe to be equivalent.
244     llvm::DenseMap<Decl *, Decl *> TentativeEquivalences;
245 
246     /// \brief Queue of declarations in the first context whose equivalence
247     /// with a declaration in the second context still needs to be verified.
248     std::deque<Decl *> DeclsToCheck;
249 
250     /// \brief Declaration (from, to) pairs that are known not to be equivalent
251     /// (which we have already complained about).
252     llvm::DenseSet<std::pair<Decl *, Decl *> > &NonEquivalentDecls;
253 
254     /// \brief Whether we're being strict about the spelling of types when
255     /// unifying two types.
256     bool StrictTypeSpelling;
257 
258     /// \brief Whether to complain about failures.
259     bool Complain;
260 
261     /// \brief \c true if the last diagnostic came from C2.
262     bool LastDiagFromC2;
263 
264     StructuralEquivalenceContext(ASTContext &C1, ASTContext &C2,
265                llvm::DenseSet<std::pair<Decl *, Decl *> > &NonEquivalentDecls,
266                                  bool StrictTypeSpelling = false,
267                                  bool Complain = true)
268       : C1(C1), C2(C2), NonEquivalentDecls(NonEquivalentDecls),
269         StrictTypeSpelling(StrictTypeSpelling), Complain(Complain),
270         LastDiagFromC2(false) {}
271 
272     /// \brief Determine whether the two declarations are structurally
273     /// equivalent.
274     bool IsStructurallyEquivalent(Decl *D1, Decl *D2);
275 
276     /// \brief Determine whether the two types are structurally equivalent.
277     bool IsStructurallyEquivalent(QualType T1, QualType T2);
278 
279   private:
280     /// \brief Finish checking all of the structural equivalences.
281     ///
282     /// \returns true if an error occurred, false otherwise.
283     bool Finish();
284 
285   public:
286     DiagnosticBuilder Diag1(SourceLocation Loc, unsigned DiagID) {
287       assert(Complain && "Not allowed to complain");
288       if (LastDiagFromC2)
289         C1.getDiagnostics().notePriorDiagnosticFrom(C2.getDiagnostics());
290       LastDiagFromC2 = false;
291       return C1.getDiagnostics().Report(Loc, DiagID);
292     }
293 
294     DiagnosticBuilder Diag2(SourceLocation Loc, unsigned DiagID) {
295       assert(Complain && "Not allowed to complain");
296       if (!LastDiagFromC2)
297         C2.getDiagnostics().notePriorDiagnosticFrom(C1.getDiagnostics());
298       LastDiagFromC2 = true;
299       return C2.getDiagnostics().Report(Loc, DiagID);
300     }
301   };
302 }
303 
304 static bool IsStructurallyEquivalent(StructuralEquivalenceContext &Context,
305                                      QualType T1, QualType T2);
306 static bool IsStructurallyEquivalent(StructuralEquivalenceContext &Context,
307                                      Decl *D1, Decl *D2);
308 
309 /// \brief Determine structural equivalence of two expressions.
310 static bool IsStructurallyEquivalent(StructuralEquivalenceContext &Context,
311                                      Expr *E1, Expr *E2) {
312   if (!E1 || !E2)
313     return E1 == E2;
314 
315   // FIXME: Actually perform a structural comparison!
316   return true;
317 }
318 
319 /// \brief Determine whether two identifiers are equivalent.
320 static bool IsStructurallyEquivalent(const IdentifierInfo *Name1,
321                                      const IdentifierInfo *Name2) {
322   if (!Name1 || !Name2)
323     return Name1 == Name2;
324 
325   return Name1->getName() == Name2->getName();
326 }
327 
328 /// \brief Determine whether two nested-name-specifiers are equivalent.
329 static bool IsStructurallyEquivalent(StructuralEquivalenceContext &Context,
330                                      NestedNameSpecifier *NNS1,
331                                      NestedNameSpecifier *NNS2) {
332   // FIXME: Implement!
333   return true;
334 }
335 
336 /// \brief Determine whether two template arguments are equivalent.
337 static bool IsStructurallyEquivalent(StructuralEquivalenceContext &Context,
338                                      const TemplateArgument &Arg1,
339                                      const TemplateArgument &Arg2) {
340   if (Arg1.getKind() != Arg2.getKind())
341     return false;
342 
343   switch (Arg1.getKind()) {
344   case TemplateArgument::Null:
345     return true;
346 
347   case TemplateArgument::Type:
348     return Context.IsStructurallyEquivalent(Arg1.getAsType(), Arg2.getAsType());
349 
350   case TemplateArgument::Integral:
351     if (!Context.IsStructurallyEquivalent(Arg1.getIntegralType(),
352                                           Arg2.getIntegralType()))
353       return false;
354 
355     return llvm::APSInt::isSameValue(Arg1.getAsIntegral(), Arg2.getAsIntegral());
356 
357   case TemplateArgument::Declaration:
358     return Context.IsStructurallyEquivalent(Arg1.getAsDecl(), Arg2.getAsDecl());
359 
360   case TemplateArgument::NullPtr:
361     return true; // FIXME: Is this correct?
362 
363   case TemplateArgument::Template:
364     return IsStructurallyEquivalent(Context,
365                                     Arg1.getAsTemplate(),
366                                     Arg2.getAsTemplate());
367 
368   case TemplateArgument::TemplateExpansion:
369     return IsStructurallyEquivalent(Context,
370                                     Arg1.getAsTemplateOrTemplatePattern(),
371                                     Arg2.getAsTemplateOrTemplatePattern());
372 
373   case TemplateArgument::Expression:
374     return IsStructurallyEquivalent(Context,
375                                     Arg1.getAsExpr(), Arg2.getAsExpr());
376 
377   case TemplateArgument::Pack:
378     if (Arg1.pack_size() != Arg2.pack_size())
379       return false;
380 
381     for (unsigned I = 0, N = Arg1.pack_size(); I != N; ++I)
382       if (!IsStructurallyEquivalent(Context,
383                                     Arg1.pack_begin()[I],
384                                     Arg2.pack_begin()[I]))
385         return false;
386 
387     return true;
388   }
389 
390   llvm_unreachable("Invalid template argument kind");
391 }
392 
393 /// \brief Determine structural equivalence for the common part of array
394 /// types.
395 static bool IsArrayStructurallyEquivalent(StructuralEquivalenceContext &Context,
396                                           const ArrayType *Array1,
397                                           const ArrayType *Array2) {
398   if (!IsStructurallyEquivalent(Context,
399                                 Array1->getElementType(),
400                                 Array2->getElementType()))
401     return false;
402   if (Array1->getSizeModifier() != Array2->getSizeModifier())
403     return false;
404   if (Array1->getIndexTypeQualifiers() != Array2->getIndexTypeQualifiers())
405     return false;
406 
407   return true;
408 }
409 
410 /// \brief Determine structural equivalence of two types.
411 static bool IsStructurallyEquivalent(StructuralEquivalenceContext &Context,
412                                      QualType T1, QualType T2) {
413   if (T1.isNull() || T2.isNull())
414     return T1.isNull() && T2.isNull();
415 
416   if (!Context.StrictTypeSpelling) {
417     // We aren't being strict about token-to-token equivalence of types,
418     // so map down to the canonical type.
419     T1 = Context.C1.getCanonicalType(T1);
420     T2 = Context.C2.getCanonicalType(T2);
421   }
422 
423   if (T1.getQualifiers() != T2.getQualifiers())
424     return false;
425 
426   Type::TypeClass TC = T1->getTypeClass();
427 
428   if (T1->getTypeClass() != T2->getTypeClass()) {
429     // Compare function types with prototypes vs. without prototypes as if
430     // both did not have prototypes.
431     if (T1->getTypeClass() == Type::FunctionProto &&
432         T2->getTypeClass() == Type::FunctionNoProto)
433       TC = Type::FunctionNoProto;
434     else if (T1->getTypeClass() == Type::FunctionNoProto &&
435              T2->getTypeClass() == Type::FunctionProto)
436       TC = Type::FunctionNoProto;
437     else
438       return false;
439   }
440 
441   switch (TC) {
442   case Type::Builtin:
443     // FIXME: Deal with Char_S/Char_U.
444     if (cast<BuiltinType>(T1)->getKind() != cast<BuiltinType>(T2)->getKind())
445       return false;
446     break;
447 
448   case Type::Complex:
449     if (!IsStructurallyEquivalent(Context,
450                                   cast<ComplexType>(T1)->getElementType(),
451                                   cast<ComplexType>(T2)->getElementType()))
452       return false;
453     break;
454 
455   case Type::Adjusted:
456   case Type::Decayed:
457     if (!IsStructurallyEquivalent(Context,
458                                   cast<AdjustedType>(T1)->getOriginalType(),
459                                   cast<AdjustedType>(T2)->getOriginalType()))
460       return false;
461     break;
462 
463   case Type::Pointer:
464     if (!IsStructurallyEquivalent(Context,
465                                   cast<PointerType>(T1)->getPointeeType(),
466                                   cast<PointerType>(T2)->getPointeeType()))
467       return false;
468     break;
469 
470   case Type::BlockPointer:
471     if (!IsStructurallyEquivalent(Context,
472                                   cast<BlockPointerType>(T1)->getPointeeType(),
473                                   cast<BlockPointerType>(T2)->getPointeeType()))
474       return false;
475     break;
476 
477   case Type::LValueReference:
478   case Type::RValueReference: {
479     const ReferenceType *Ref1 = cast<ReferenceType>(T1);
480     const ReferenceType *Ref2 = cast<ReferenceType>(T2);
481     if (Ref1->isSpelledAsLValue() != Ref2->isSpelledAsLValue())
482       return false;
483     if (Ref1->isInnerRef() != Ref2->isInnerRef())
484       return false;
485     if (!IsStructurallyEquivalent(Context,
486                                   Ref1->getPointeeTypeAsWritten(),
487                                   Ref2->getPointeeTypeAsWritten()))
488       return false;
489     break;
490   }
491 
492   case Type::MemberPointer: {
493     const MemberPointerType *MemPtr1 = cast<MemberPointerType>(T1);
494     const MemberPointerType *MemPtr2 = cast<MemberPointerType>(T2);
495     if (!IsStructurallyEquivalent(Context,
496                                   MemPtr1->getPointeeType(),
497                                   MemPtr2->getPointeeType()))
498       return false;
499     if (!IsStructurallyEquivalent(Context,
500                                   QualType(MemPtr1->getClass(), 0),
501                                   QualType(MemPtr2->getClass(), 0)))
502       return false;
503     break;
504   }
505 
506   case Type::ConstantArray: {
507     const ConstantArrayType *Array1 = cast<ConstantArrayType>(T1);
508     const ConstantArrayType *Array2 = cast<ConstantArrayType>(T2);
509     if (!llvm::APInt::isSameValue(Array1->getSize(), Array2->getSize()))
510       return false;
511 
512     if (!IsArrayStructurallyEquivalent(Context, Array1, Array2))
513       return false;
514     break;
515   }
516 
517   case Type::IncompleteArray:
518     if (!IsArrayStructurallyEquivalent(Context,
519                                        cast<ArrayType>(T1),
520                                        cast<ArrayType>(T2)))
521       return false;
522     break;
523 
524   case Type::VariableArray: {
525     const VariableArrayType *Array1 = cast<VariableArrayType>(T1);
526     const VariableArrayType *Array2 = cast<VariableArrayType>(T2);
527     if (!IsStructurallyEquivalent(Context,
528                                   Array1->getSizeExpr(), Array2->getSizeExpr()))
529       return false;
530 
531     if (!IsArrayStructurallyEquivalent(Context, Array1, Array2))
532       return false;
533 
534     break;
535   }
536 
537   case Type::DependentSizedArray: {
538     const DependentSizedArrayType *Array1 = cast<DependentSizedArrayType>(T1);
539     const DependentSizedArrayType *Array2 = cast<DependentSizedArrayType>(T2);
540     if (!IsStructurallyEquivalent(Context,
541                                   Array1->getSizeExpr(), Array2->getSizeExpr()))
542       return false;
543 
544     if (!IsArrayStructurallyEquivalent(Context, Array1, Array2))
545       return false;
546 
547     break;
548   }
549 
550   case Type::DependentSizedExtVector: {
551     const DependentSizedExtVectorType *Vec1
552       = cast<DependentSizedExtVectorType>(T1);
553     const DependentSizedExtVectorType *Vec2
554       = cast<DependentSizedExtVectorType>(T2);
555     if (!IsStructurallyEquivalent(Context,
556                                   Vec1->getSizeExpr(), Vec2->getSizeExpr()))
557       return false;
558     if (!IsStructurallyEquivalent(Context,
559                                   Vec1->getElementType(),
560                                   Vec2->getElementType()))
561       return false;
562     break;
563   }
564 
565   case Type::Vector:
566   case Type::ExtVector: {
567     const VectorType *Vec1 = cast<VectorType>(T1);
568     const VectorType *Vec2 = cast<VectorType>(T2);
569     if (!IsStructurallyEquivalent(Context,
570                                   Vec1->getElementType(),
571                                   Vec2->getElementType()))
572       return false;
573     if (Vec1->getNumElements() != Vec2->getNumElements())
574       return false;
575     if (Vec1->getVectorKind() != Vec2->getVectorKind())
576       return false;
577     break;
578   }
579 
580   case Type::FunctionProto: {
581     const FunctionProtoType *Proto1 = cast<FunctionProtoType>(T1);
582     const FunctionProtoType *Proto2 = cast<FunctionProtoType>(T2);
583     if (Proto1->getNumParams() != Proto2->getNumParams())
584       return false;
585     for (unsigned I = 0, N = Proto1->getNumParams(); I != N; ++I) {
586       if (!IsStructurallyEquivalent(Context, Proto1->getParamType(I),
587                                     Proto2->getParamType(I)))
588         return false;
589     }
590     if (Proto1->isVariadic() != Proto2->isVariadic())
591       return false;
592     if (Proto1->getExceptionSpecType() != Proto2->getExceptionSpecType())
593       return false;
594     if (Proto1->getExceptionSpecType() == EST_Dynamic) {
595       if (Proto1->getNumExceptions() != Proto2->getNumExceptions())
596         return false;
597       for (unsigned I = 0, N = Proto1->getNumExceptions(); I != N; ++I) {
598         if (!IsStructurallyEquivalent(Context,
599                                       Proto1->getExceptionType(I),
600                                       Proto2->getExceptionType(I)))
601           return false;
602       }
603     } else if (Proto1->getExceptionSpecType() == EST_ComputedNoexcept) {
604       if (!IsStructurallyEquivalent(Context,
605                                     Proto1->getNoexceptExpr(),
606                                     Proto2->getNoexceptExpr()))
607         return false;
608     }
609     if (Proto1->getTypeQuals() != Proto2->getTypeQuals())
610       return false;
611 
612     // Fall through to check the bits common with FunctionNoProtoType.
613   }
614 
615   case Type::FunctionNoProto: {
616     const FunctionType *Function1 = cast<FunctionType>(T1);
617     const FunctionType *Function2 = cast<FunctionType>(T2);
618     if (!IsStructurallyEquivalent(Context, Function1->getReturnType(),
619                                   Function2->getReturnType()))
620       return false;
621       if (Function1->getExtInfo() != Function2->getExtInfo())
622         return false;
623     break;
624   }
625 
626   case Type::UnresolvedUsing:
627     if (!IsStructurallyEquivalent(Context,
628                                   cast<UnresolvedUsingType>(T1)->getDecl(),
629                                   cast<UnresolvedUsingType>(T2)->getDecl()))
630       return false;
631 
632     break;
633 
634   case Type::Attributed:
635     if (!IsStructurallyEquivalent(Context,
636                                   cast<AttributedType>(T1)->getModifiedType(),
637                                   cast<AttributedType>(T2)->getModifiedType()))
638       return false;
639     if (!IsStructurallyEquivalent(Context,
640                                 cast<AttributedType>(T1)->getEquivalentType(),
641                                 cast<AttributedType>(T2)->getEquivalentType()))
642       return false;
643     break;
644 
645   case Type::Paren:
646     if (!IsStructurallyEquivalent(Context,
647                                   cast<ParenType>(T1)->getInnerType(),
648                                   cast<ParenType>(T2)->getInnerType()))
649       return false;
650     break;
651 
652   case Type::Typedef:
653     if (!IsStructurallyEquivalent(Context,
654                                   cast<TypedefType>(T1)->getDecl(),
655                                   cast<TypedefType>(T2)->getDecl()))
656       return false;
657     break;
658 
659   case Type::TypeOfExpr:
660     if (!IsStructurallyEquivalent(Context,
661                                 cast<TypeOfExprType>(T1)->getUnderlyingExpr(),
662                                 cast<TypeOfExprType>(T2)->getUnderlyingExpr()))
663       return false;
664     break;
665 
666   case Type::TypeOf:
667     if (!IsStructurallyEquivalent(Context,
668                                   cast<TypeOfType>(T1)->getUnderlyingType(),
669                                   cast<TypeOfType>(T2)->getUnderlyingType()))
670       return false;
671     break;
672 
673   case Type::UnaryTransform:
674     if (!IsStructurallyEquivalent(Context,
675                              cast<UnaryTransformType>(T1)->getUnderlyingType(),
676                              cast<UnaryTransformType>(T1)->getUnderlyingType()))
677       return false;
678     break;
679 
680   case Type::Decltype:
681     if (!IsStructurallyEquivalent(Context,
682                                   cast<DecltypeType>(T1)->getUnderlyingExpr(),
683                                   cast<DecltypeType>(T2)->getUnderlyingExpr()))
684       return false;
685     break;
686 
687   case Type::Auto:
688     if (!IsStructurallyEquivalent(Context,
689                                   cast<AutoType>(T1)->getDeducedType(),
690                                   cast<AutoType>(T2)->getDeducedType()))
691       return false;
692     break;
693 
694   case Type::Record:
695   case Type::Enum:
696     if (!IsStructurallyEquivalent(Context,
697                                   cast<TagType>(T1)->getDecl(),
698                                   cast<TagType>(T2)->getDecl()))
699       return false;
700     break;
701 
702   case Type::TemplateTypeParm: {
703     const TemplateTypeParmType *Parm1 = cast<TemplateTypeParmType>(T1);
704     const TemplateTypeParmType *Parm2 = cast<TemplateTypeParmType>(T2);
705     if (Parm1->getDepth() != Parm2->getDepth())
706       return false;
707     if (Parm1->getIndex() != Parm2->getIndex())
708       return false;
709     if (Parm1->isParameterPack() != Parm2->isParameterPack())
710       return false;
711 
712     // Names of template type parameters are never significant.
713     break;
714   }
715 
716   case Type::SubstTemplateTypeParm: {
717     const SubstTemplateTypeParmType *Subst1
718       = cast<SubstTemplateTypeParmType>(T1);
719     const SubstTemplateTypeParmType *Subst2
720       = cast<SubstTemplateTypeParmType>(T2);
721     if (!IsStructurallyEquivalent(Context,
722                                   QualType(Subst1->getReplacedParameter(), 0),
723                                   QualType(Subst2->getReplacedParameter(), 0)))
724       return false;
725     if (!IsStructurallyEquivalent(Context,
726                                   Subst1->getReplacementType(),
727                                   Subst2->getReplacementType()))
728       return false;
729     break;
730   }
731 
732   case Type::SubstTemplateTypeParmPack: {
733     const SubstTemplateTypeParmPackType *Subst1
734       = cast<SubstTemplateTypeParmPackType>(T1);
735     const SubstTemplateTypeParmPackType *Subst2
736       = cast<SubstTemplateTypeParmPackType>(T2);
737     if (!IsStructurallyEquivalent(Context,
738                                   QualType(Subst1->getReplacedParameter(), 0),
739                                   QualType(Subst2->getReplacedParameter(), 0)))
740       return false;
741     if (!IsStructurallyEquivalent(Context,
742                                   Subst1->getArgumentPack(),
743                                   Subst2->getArgumentPack()))
744       return false;
745     break;
746   }
747   case Type::TemplateSpecialization: {
748     const TemplateSpecializationType *Spec1
749       = cast<TemplateSpecializationType>(T1);
750     const TemplateSpecializationType *Spec2
751       = cast<TemplateSpecializationType>(T2);
752     if (!IsStructurallyEquivalent(Context,
753                                   Spec1->getTemplateName(),
754                                   Spec2->getTemplateName()))
755       return false;
756     if (Spec1->getNumArgs() != Spec2->getNumArgs())
757       return false;
758     for (unsigned I = 0, N = Spec1->getNumArgs(); I != N; ++I) {
759       if (!IsStructurallyEquivalent(Context,
760                                     Spec1->getArg(I), Spec2->getArg(I)))
761         return false;
762     }
763     break;
764   }
765 
766   case Type::Elaborated: {
767     const ElaboratedType *Elab1 = cast<ElaboratedType>(T1);
768     const ElaboratedType *Elab2 = cast<ElaboratedType>(T2);
769     // CHECKME: what if a keyword is ETK_None or ETK_typename ?
770     if (Elab1->getKeyword() != Elab2->getKeyword())
771       return false;
772     if (!IsStructurallyEquivalent(Context,
773                                   Elab1->getQualifier(),
774                                   Elab2->getQualifier()))
775       return false;
776     if (!IsStructurallyEquivalent(Context,
777                                   Elab1->getNamedType(),
778                                   Elab2->getNamedType()))
779       return false;
780     break;
781   }
782 
783   case Type::InjectedClassName: {
784     const InjectedClassNameType *Inj1 = cast<InjectedClassNameType>(T1);
785     const InjectedClassNameType *Inj2 = cast<InjectedClassNameType>(T2);
786     if (!IsStructurallyEquivalent(Context,
787                                   Inj1->getInjectedSpecializationType(),
788                                   Inj2->getInjectedSpecializationType()))
789       return false;
790     break;
791   }
792 
793   case Type::DependentName: {
794     const DependentNameType *Typename1 = cast<DependentNameType>(T1);
795     const DependentNameType *Typename2 = cast<DependentNameType>(T2);
796     if (!IsStructurallyEquivalent(Context,
797                                   Typename1->getQualifier(),
798                                   Typename2->getQualifier()))
799       return false;
800     if (!IsStructurallyEquivalent(Typename1->getIdentifier(),
801                                   Typename2->getIdentifier()))
802       return false;
803 
804     break;
805   }
806 
807   case Type::DependentTemplateSpecialization: {
808     const DependentTemplateSpecializationType *Spec1 =
809       cast<DependentTemplateSpecializationType>(T1);
810     const DependentTemplateSpecializationType *Spec2 =
811       cast<DependentTemplateSpecializationType>(T2);
812     if (!IsStructurallyEquivalent(Context,
813                                   Spec1->getQualifier(),
814                                   Spec2->getQualifier()))
815       return false;
816     if (!IsStructurallyEquivalent(Spec1->getIdentifier(),
817                                   Spec2->getIdentifier()))
818       return false;
819     if (Spec1->getNumArgs() != Spec2->getNumArgs())
820       return false;
821     for (unsigned I = 0, N = Spec1->getNumArgs(); I != N; ++I) {
822       if (!IsStructurallyEquivalent(Context,
823                                     Spec1->getArg(I), Spec2->getArg(I)))
824         return false;
825     }
826     break;
827   }
828 
829   case Type::PackExpansion:
830     if (!IsStructurallyEquivalent(Context,
831                                   cast<PackExpansionType>(T1)->getPattern(),
832                                   cast<PackExpansionType>(T2)->getPattern()))
833       return false;
834     break;
835 
836   case Type::ObjCInterface: {
837     const ObjCInterfaceType *Iface1 = cast<ObjCInterfaceType>(T1);
838     const ObjCInterfaceType *Iface2 = cast<ObjCInterfaceType>(T2);
839     if (!IsStructurallyEquivalent(Context,
840                                   Iface1->getDecl(), Iface2->getDecl()))
841       return false;
842     break;
843   }
844 
845   case Type::ObjCObject: {
846     const ObjCObjectType *Obj1 = cast<ObjCObjectType>(T1);
847     const ObjCObjectType *Obj2 = cast<ObjCObjectType>(T2);
848     if (!IsStructurallyEquivalent(Context,
849                                   Obj1->getBaseType(),
850                                   Obj2->getBaseType()))
851       return false;
852     if (Obj1->getNumProtocols() != Obj2->getNumProtocols())
853       return false;
854     for (unsigned I = 0, N = Obj1->getNumProtocols(); I != N; ++I) {
855       if (!IsStructurallyEquivalent(Context,
856                                     Obj1->getProtocol(I),
857                                     Obj2->getProtocol(I)))
858         return false;
859     }
860     break;
861   }
862 
863   case Type::ObjCObjectPointer: {
864     const ObjCObjectPointerType *Ptr1 = cast<ObjCObjectPointerType>(T1);
865     const ObjCObjectPointerType *Ptr2 = cast<ObjCObjectPointerType>(T2);
866     if (!IsStructurallyEquivalent(Context,
867                                   Ptr1->getPointeeType(),
868                                   Ptr2->getPointeeType()))
869       return false;
870     break;
871   }
872 
873   case Type::Atomic: {
874     if (!IsStructurallyEquivalent(Context,
875                                   cast<AtomicType>(T1)->getValueType(),
876                                   cast<AtomicType>(T2)->getValueType()))
877       return false;
878     break;
879   }
880 
881   } // end switch
882 
883   return true;
884 }
885 
886 /// \brief Determine structural equivalence of two fields.
887 static bool IsStructurallyEquivalent(StructuralEquivalenceContext &Context,
888                                      FieldDecl *Field1, FieldDecl *Field2) {
889   RecordDecl *Owner2 = cast<RecordDecl>(Field2->getDeclContext());
890 
891   // For anonymous structs/unions, match up the anonymous struct/union type
892   // declarations directly, so that we don't go off searching for anonymous
893   // types
894   if (Field1->isAnonymousStructOrUnion() &&
895       Field2->isAnonymousStructOrUnion()) {
896     RecordDecl *D1 = Field1->getType()->castAs<RecordType>()->getDecl();
897     RecordDecl *D2 = Field2->getType()->castAs<RecordType>()->getDecl();
898     return IsStructurallyEquivalent(Context, D1, D2);
899   }
900 
901   // Check for equivalent field names.
902   IdentifierInfo *Name1 = Field1->getIdentifier();
903   IdentifierInfo *Name2 = Field2->getIdentifier();
904   if (!::IsStructurallyEquivalent(Name1, Name2))
905     return false;
906 
907   if (!IsStructurallyEquivalent(Context,
908                                 Field1->getType(), Field2->getType())) {
909     if (Context.Complain) {
910       Context.Diag2(Owner2->getLocation(), diag::warn_odr_tag_type_inconsistent)
911         << Context.C2.getTypeDeclType(Owner2);
912       Context.Diag2(Field2->getLocation(), diag::note_odr_field)
913         << Field2->getDeclName() << Field2->getType();
914       Context.Diag1(Field1->getLocation(), diag::note_odr_field)
915         << Field1->getDeclName() << Field1->getType();
916     }
917     return false;
918   }
919 
920   if (Field1->isBitField() != Field2->isBitField()) {
921     if (Context.Complain) {
922       Context.Diag2(Owner2->getLocation(), diag::warn_odr_tag_type_inconsistent)
923         << Context.C2.getTypeDeclType(Owner2);
924       if (Field1->isBitField()) {
925         Context.Diag1(Field1->getLocation(), diag::note_odr_bit_field)
926         << Field1->getDeclName() << Field1->getType()
927         << Field1->getBitWidthValue(Context.C1);
928         Context.Diag2(Field2->getLocation(), diag::note_odr_not_bit_field)
929         << Field2->getDeclName();
930       } else {
931         Context.Diag2(Field2->getLocation(), diag::note_odr_bit_field)
932         << Field2->getDeclName() << Field2->getType()
933         << Field2->getBitWidthValue(Context.C2);
934         Context.Diag1(Field1->getLocation(), diag::note_odr_not_bit_field)
935         << Field1->getDeclName();
936       }
937     }
938     return false;
939   }
940 
941   if (Field1->isBitField()) {
942     // Make sure that the bit-fields are the same length.
943     unsigned Bits1 = Field1->getBitWidthValue(Context.C1);
944     unsigned Bits2 = Field2->getBitWidthValue(Context.C2);
945 
946     if (Bits1 != Bits2) {
947       if (Context.Complain) {
948         Context.Diag2(Owner2->getLocation(), diag::warn_odr_tag_type_inconsistent)
949           << Context.C2.getTypeDeclType(Owner2);
950         Context.Diag2(Field2->getLocation(), diag::note_odr_bit_field)
951           << Field2->getDeclName() << Field2->getType() << Bits2;
952         Context.Diag1(Field1->getLocation(), diag::note_odr_bit_field)
953           << Field1->getDeclName() << Field1->getType() << Bits1;
954       }
955       return false;
956     }
957   }
958 
959   return true;
960 }
961 
962 /// \brief Find the index of the given anonymous struct/union within its
963 /// context.
964 ///
965 /// \returns Returns the index of this anonymous struct/union in its context,
966 /// including the next assigned index (if none of them match). Returns an
967 /// empty option if the context is not a record, i.e.. if the anonymous
968 /// struct/union is at namespace or block scope.
969 static Optional<unsigned> findAnonymousStructOrUnionIndex(RecordDecl *Anon) {
970   ASTContext &Context = Anon->getASTContext();
971   QualType AnonTy = Context.getRecordType(Anon);
972 
973   RecordDecl *Owner = dyn_cast<RecordDecl>(Anon->getDeclContext());
974   if (!Owner)
975     return None;
976 
977   unsigned Index = 0;
978   for (const auto *D : Owner->noload_decls()) {
979     const auto *F = dyn_cast<FieldDecl>(D);
980     if (!F || !F->isAnonymousStructOrUnion())
981       continue;
982 
983     if (Context.hasSameType(F->getType(), AnonTy))
984       break;
985 
986     ++Index;
987   }
988 
989   return Index;
990 }
991 
992 /// \brief Determine structural equivalence of two records.
993 static bool IsStructurallyEquivalent(StructuralEquivalenceContext &Context,
994                                      RecordDecl *D1, RecordDecl *D2) {
995   if (D1->isUnion() != D2->isUnion()) {
996     if (Context.Complain) {
997       Context.Diag2(D2->getLocation(), diag::warn_odr_tag_type_inconsistent)
998         << Context.C2.getTypeDeclType(D2);
999       Context.Diag1(D1->getLocation(), diag::note_odr_tag_kind_here)
1000         << D1->getDeclName() << (unsigned)D1->getTagKind();
1001     }
1002     return false;
1003   }
1004 
1005   if (D1->isAnonymousStructOrUnion() && D2->isAnonymousStructOrUnion()) {
1006     // If both anonymous structs/unions are in a record context, make sure
1007     // they occur in the same location in the context records.
1008     if (Optional<unsigned> Index1 = findAnonymousStructOrUnionIndex(D1)) {
1009       if (Optional<unsigned> Index2 = findAnonymousStructOrUnionIndex(D2)) {
1010         if (*Index1 != *Index2)
1011           return false;
1012       }
1013     }
1014   }
1015 
1016   // If both declarations are class template specializations, we know
1017   // the ODR applies, so check the template and template arguments.
1018   ClassTemplateSpecializationDecl *Spec1
1019     = dyn_cast<ClassTemplateSpecializationDecl>(D1);
1020   ClassTemplateSpecializationDecl *Spec2
1021     = dyn_cast<ClassTemplateSpecializationDecl>(D2);
1022   if (Spec1 && Spec2) {
1023     // Check that the specialized templates are the same.
1024     if (!IsStructurallyEquivalent(Context, Spec1->getSpecializedTemplate(),
1025                                   Spec2->getSpecializedTemplate()))
1026       return false;
1027 
1028     // Check that the template arguments are the same.
1029     if (Spec1->getTemplateArgs().size() != Spec2->getTemplateArgs().size())
1030       return false;
1031 
1032     for (unsigned I = 0, N = Spec1->getTemplateArgs().size(); I != N; ++I)
1033       if (!IsStructurallyEquivalent(Context,
1034                                     Spec1->getTemplateArgs().get(I),
1035                                     Spec2->getTemplateArgs().get(I)))
1036         return false;
1037   }
1038   // If one is a class template specialization and the other is not, these
1039   // structures are different.
1040   else if (Spec1 || Spec2)
1041     return false;
1042 
1043   // Compare the definitions of these two records. If either or both are
1044   // incomplete, we assume that they are equivalent.
1045   D1 = D1->getDefinition();
1046   D2 = D2->getDefinition();
1047   if (!D1 || !D2)
1048     return true;
1049 
1050   if (CXXRecordDecl *D1CXX = dyn_cast<CXXRecordDecl>(D1)) {
1051     if (CXXRecordDecl *D2CXX = dyn_cast<CXXRecordDecl>(D2)) {
1052       if (D1CXX->getNumBases() != D2CXX->getNumBases()) {
1053         if (Context.Complain) {
1054           Context.Diag2(D2->getLocation(), diag::warn_odr_tag_type_inconsistent)
1055             << Context.C2.getTypeDeclType(D2);
1056           Context.Diag2(D2->getLocation(), diag::note_odr_number_of_bases)
1057             << D2CXX->getNumBases();
1058           Context.Diag1(D1->getLocation(), diag::note_odr_number_of_bases)
1059             << D1CXX->getNumBases();
1060         }
1061         return false;
1062       }
1063 
1064       // Check the base classes.
1065       for (CXXRecordDecl::base_class_iterator Base1 = D1CXX->bases_begin(),
1066                                            BaseEnd1 = D1CXX->bases_end(),
1067                                                 Base2 = D2CXX->bases_begin();
1068            Base1 != BaseEnd1;
1069            ++Base1, ++Base2) {
1070         if (!IsStructurallyEquivalent(Context,
1071                                       Base1->getType(), Base2->getType())) {
1072           if (Context.Complain) {
1073             Context.Diag2(D2->getLocation(), diag::warn_odr_tag_type_inconsistent)
1074               << Context.C2.getTypeDeclType(D2);
1075             Context.Diag2(Base2->getLocStart(), diag::note_odr_base)
1076               << Base2->getType()
1077               << Base2->getSourceRange();
1078             Context.Diag1(Base1->getLocStart(), diag::note_odr_base)
1079               << Base1->getType()
1080               << Base1->getSourceRange();
1081           }
1082           return false;
1083         }
1084 
1085         // Check virtual vs. non-virtual inheritance mismatch.
1086         if (Base1->isVirtual() != Base2->isVirtual()) {
1087           if (Context.Complain) {
1088             Context.Diag2(D2->getLocation(), diag::warn_odr_tag_type_inconsistent)
1089               << Context.C2.getTypeDeclType(D2);
1090             Context.Diag2(Base2->getLocStart(),
1091                           diag::note_odr_virtual_base)
1092               << Base2->isVirtual() << Base2->getSourceRange();
1093             Context.Diag1(Base1->getLocStart(), diag::note_odr_base)
1094               << Base1->isVirtual()
1095               << Base1->getSourceRange();
1096           }
1097           return false;
1098         }
1099       }
1100     } else if (D1CXX->getNumBases() > 0) {
1101       if (Context.Complain) {
1102         Context.Diag2(D2->getLocation(), diag::warn_odr_tag_type_inconsistent)
1103           << Context.C2.getTypeDeclType(D2);
1104         const CXXBaseSpecifier *Base1 = D1CXX->bases_begin();
1105         Context.Diag1(Base1->getLocStart(), diag::note_odr_base)
1106           << Base1->getType()
1107           << Base1->getSourceRange();
1108         Context.Diag2(D2->getLocation(), diag::note_odr_missing_base);
1109       }
1110       return false;
1111     }
1112   }
1113 
1114   // Check the fields for consistency.
1115   RecordDecl::field_iterator Field2 = D2->field_begin(),
1116                              Field2End = D2->field_end();
1117   for (RecordDecl::field_iterator Field1 = D1->field_begin(),
1118                                   Field1End = D1->field_end();
1119        Field1 != Field1End;
1120        ++Field1, ++Field2) {
1121     if (Field2 == Field2End) {
1122       if (Context.Complain) {
1123         Context.Diag2(D2->getLocation(), diag::warn_odr_tag_type_inconsistent)
1124           << Context.C2.getTypeDeclType(D2);
1125         Context.Diag1(Field1->getLocation(), diag::note_odr_field)
1126           << Field1->getDeclName() << Field1->getType();
1127         Context.Diag2(D2->getLocation(), diag::note_odr_missing_field);
1128       }
1129       return false;
1130     }
1131 
1132     if (!IsStructurallyEquivalent(Context, *Field1, *Field2))
1133       return false;
1134   }
1135 
1136   if (Field2 != Field2End) {
1137     if (Context.Complain) {
1138       Context.Diag2(D2->getLocation(), diag::warn_odr_tag_type_inconsistent)
1139         << Context.C2.getTypeDeclType(D2);
1140       Context.Diag2(Field2->getLocation(), diag::note_odr_field)
1141         << Field2->getDeclName() << Field2->getType();
1142       Context.Diag1(D1->getLocation(), diag::note_odr_missing_field);
1143     }
1144     return false;
1145   }
1146 
1147   return true;
1148 }
1149 
1150 /// \brief Determine structural equivalence of two enums.
1151 static bool IsStructurallyEquivalent(StructuralEquivalenceContext &Context,
1152                                      EnumDecl *D1, EnumDecl *D2) {
1153   EnumDecl::enumerator_iterator EC2 = D2->enumerator_begin(),
1154                              EC2End = D2->enumerator_end();
1155   for (EnumDecl::enumerator_iterator EC1 = D1->enumerator_begin(),
1156                                   EC1End = D1->enumerator_end();
1157        EC1 != EC1End; ++EC1, ++EC2) {
1158     if (EC2 == EC2End) {
1159       if (Context.Complain) {
1160         Context.Diag2(D2->getLocation(), diag::warn_odr_tag_type_inconsistent)
1161           << Context.C2.getTypeDeclType(D2);
1162         Context.Diag1(EC1->getLocation(), diag::note_odr_enumerator)
1163           << EC1->getDeclName()
1164           << EC1->getInitVal().toString(10);
1165         Context.Diag2(D2->getLocation(), diag::note_odr_missing_enumerator);
1166       }
1167       return false;
1168     }
1169 
1170     llvm::APSInt Val1 = EC1->getInitVal();
1171     llvm::APSInt Val2 = EC2->getInitVal();
1172     if (!llvm::APSInt::isSameValue(Val1, Val2) ||
1173         !IsStructurallyEquivalent(EC1->getIdentifier(), EC2->getIdentifier())) {
1174       if (Context.Complain) {
1175         Context.Diag2(D2->getLocation(), diag::warn_odr_tag_type_inconsistent)
1176           << Context.C2.getTypeDeclType(D2);
1177         Context.Diag2(EC2->getLocation(), diag::note_odr_enumerator)
1178           << EC2->getDeclName()
1179           << EC2->getInitVal().toString(10);
1180         Context.Diag1(EC1->getLocation(), diag::note_odr_enumerator)
1181           << EC1->getDeclName()
1182           << EC1->getInitVal().toString(10);
1183       }
1184       return false;
1185     }
1186   }
1187 
1188   if (EC2 != EC2End) {
1189     if (Context.Complain) {
1190       Context.Diag2(D2->getLocation(), diag::warn_odr_tag_type_inconsistent)
1191         << Context.C2.getTypeDeclType(D2);
1192       Context.Diag2(EC2->getLocation(), diag::note_odr_enumerator)
1193         << EC2->getDeclName()
1194         << EC2->getInitVal().toString(10);
1195       Context.Diag1(D1->getLocation(), diag::note_odr_missing_enumerator);
1196     }
1197     return false;
1198   }
1199 
1200   return true;
1201 }
1202 
1203 static bool IsStructurallyEquivalent(StructuralEquivalenceContext &Context,
1204                                      TemplateParameterList *Params1,
1205                                      TemplateParameterList *Params2) {
1206   if (Params1->size() != Params2->size()) {
1207     if (Context.Complain) {
1208       Context.Diag2(Params2->getTemplateLoc(),
1209                     diag::err_odr_different_num_template_parameters)
1210         << Params1->size() << Params2->size();
1211       Context.Diag1(Params1->getTemplateLoc(),
1212                     diag::note_odr_template_parameter_list);
1213     }
1214     return false;
1215   }
1216 
1217   for (unsigned I = 0, N = Params1->size(); I != N; ++I) {
1218     if (Params1->getParam(I)->getKind() != Params2->getParam(I)->getKind()) {
1219       if (Context.Complain) {
1220         Context.Diag2(Params2->getParam(I)->getLocation(),
1221                       diag::err_odr_different_template_parameter_kind);
1222         Context.Diag1(Params1->getParam(I)->getLocation(),
1223                       diag::note_odr_template_parameter_here);
1224       }
1225       return false;
1226     }
1227 
1228     if (!Context.IsStructurallyEquivalent(Params1->getParam(I),
1229                                           Params2->getParam(I))) {
1230 
1231       return false;
1232     }
1233   }
1234 
1235   return true;
1236 }
1237 
1238 static bool IsStructurallyEquivalent(StructuralEquivalenceContext &Context,
1239                                      TemplateTypeParmDecl *D1,
1240                                      TemplateTypeParmDecl *D2) {
1241   if (D1->isParameterPack() != D2->isParameterPack()) {
1242     if (Context.Complain) {
1243       Context.Diag2(D2->getLocation(), diag::err_odr_parameter_pack_non_pack)
1244         << D2->isParameterPack();
1245       Context.Diag1(D1->getLocation(), diag::note_odr_parameter_pack_non_pack)
1246         << D1->isParameterPack();
1247     }
1248     return false;
1249   }
1250 
1251   return true;
1252 }
1253 
1254 static bool IsStructurallyEquivalent(StructuralEquivalenceContext &Context,
1255                                      NonTypeTemplateParmDecl *D1,
1256                                      NonTypeTemplateParmDecl *D2) {
1257   if (D1->isParameterPack() != D2->isParameterPack()) {
1258     if (Context.Complain) {
1259       Context.Diag2(D2->getLocation(), diag::err_odr_parameter_pack_non_pack)
1260         << D2->isParameterPack();
1261       Context.Diag1(D1->getLocation(), diag::note_odr_parameter_pack_non_pack)
1262         << D1->isParameterPack();
1263     }
1264     return false;
1265   }
1266 
1267   // Check types.
1268   if (!Context.IsStructurallyEquivalent(D1->getType(), D2->getType())) {
1269     if (Context.Complain) {
1270       Context.Diag2(D2->getLocation(),
1271                     diag::err_odr_non_type_parameter_type_inconsistent)
1272         << D2->getType() << D1->getType();
1273       Context.Diag1(D1->getLocation(), diag::note_odr_value_here)
1274         << D1->getType();
1275     }
1276     return false;
1277   }
1278 
1279   return true;
1280 }
1281 
1282 static bool IsStructurallyEquivalent(StructuralEquivalenceContext &Context,
1283                                      TemplateTemplateParmDecl *D1,
1284                                      TemplateTemplateParmDecl *D2) {
1285   if (D1->isParameterPack() != D2->isParameterPack()) {
1286     if (Context.Complain) {
1287       Context.Diag2(D2->getLocation(), diag::err_odr_parameter_pack_non_pack)
1288         << D2->isParameterPack();
1289       Context.Diag1(D1->getLocation(), diag::note_odr_parameter_pack_non_pack)
1290         << D1->isParameterPack();
1291     }
1292     return false;
1293   }
1294 
1295   // Check template parameter lists.
1296   return IsStructurallyEquivalent(Context, D1->getTemplateParameters(),
1297                                   D2->getTemplateParameters());
1298 }
1299 
1300 static bool IsStructurallyEquivalent(StructuralEquivalenceContext &Context,
1301                                      ClassTemplateDecl *D1,
1302                                      ClassTemplateDecl *D2) {
1303   // Check template parameters.
1304   if (!IsStructurallyEquivalent(Context,
1305                                 D1->getTemplateParameters(),
1306                                 D2->getTemplateParameters()))
1307     return false;
1308 
1309   // Check the templated declaration.
1310   return Context.IsStructurallyEquivalent(D1->getTemplatedDecl(),
1311                                           D2->getTemplatedDecl());
1312 }
1313 
1314 /// \brief Determine structural equivalence of two declarations.
1315 static bool IsStructurallyEquivalent(StructuralEquivalenceContext &Context,
1316                                      Decl *D1, Decl *D2) {
1317   // FIXME: Check for known structural equivalences via a callback of some sort.
1318 
1319   // Check whether we already know that these two declarations are not
1320   // structurally equivalent.
1321   if (Context.NonEquivalentDecls.count(std::make_pair(D1->getCanonicalDecl(),
1322                                                       D2->getCanonicalDecl())))
1323     return false;
1324 
1325   // Determine whether we've already produced a tentative equivalence for D1.
1326   Decl *&EquivToD1 = Context.TentativeEquivalences[D1->getCanonicalDecl()];
1327   if (EquivToD1)
1328     return EquivToD1 == D2->getCanonicalDecl();
1329 
1330   // Produce a tentative equivalence D1 <-> D2, which will be checked later.
1331   EquivToD1 = D2->getCanonicalDecl();
1332   Context.DeclsToCheck.push_back(D1->getCanonicalDecl());
1333   return true;
1334 }
1335 
1336 bool StructuralEquivalenceContext::IsStructurallyEquivalent(Decl *D1,
1337                                                             Decl *D2) {
1338   if (!::IsStructurallyEquivalent(*this, D1, D2))
1339     return false;
1340 
1341   return !Finish();
1342 }
1343 
1344 bool StructuralEquivalenceContext::IsStructurallyEquivalent(QualType T1,
1345                                                             QualType T2) {
1346   if (!::IsStructurallyEquivalent(*this, T1, T2))
1347     return false;
1348 
1349   return !Finish();
1350 }
1351 
1352 bool StructuralEquivalenceContext::Finish() {
1353   while (!DeclsToCheck.empty()) {
1354     // Check the next declaration.
1355     Decl *D1 = DeclsToCheck.front();
1356     DeclsToCheck.pop_front();
1357 
1358     Decl *D2 = TentativeEquivalences[D1];
1359     assert(D2 && "Unrecorded tentative equivalence?");
1360 
1361     bool Equivalent = true;
1362 
1363     // FIXME: Switch on all declaration kinds. For now, we're just going to
1364     // check the obvious ones.
1365     if (RecordDecl *Record1 = dyn_cast<RecordDecl>(D1)) {
1366       if (RecordDecl *Record2 = dyn_cast<RecordDecl>(D2)) {
1367         // Check for equivalent structure names.
1368         IdentifierInfo *Name1 = Record1->getIdentifier();
1369         if (!Name1 && Record1->getTypedefNameForAnonDecl())
1370           Name1 = Record1->getTypedefNameForAnonDecl()->getIdentifier();
1371         IdentifierInfo *Name2 = Record2->getIdentifier();
1372         if (!Name2 && Record2->getTypedefNameForAnonDecl())
1373           Name2 = Record2->getTypedefNameForAnonDecl()->getIdentifier();
1374         if (!::IsStructurallyEquivalent(Name1, Name2) ||
1375             !::IsStructurallyEquivalent(*this, Record1, Record2))
1376           Equivalent = false;
1377       } else {
1378         // Record/non-record mismatch.
1379         Equivalent = false;
1380       }
1381     } else if (EnumDecl *Enum1 = dyn_cast<EnumDecl>(D1)) {
1382       if (EnumDecl *Enum2 = dyn_cast<EnumDecl>(D2)) {
1383         // Check for equivalent enum names.
1384         IdentifierInfo *Name1 = Enum1->getIdentifier();
1385         if (!Name1 && Enum1->getTypedefNameForAnonDecl())
1386           Name1 = Enum1->getTypedefNameForAnonDecl()->getIdentifier();
1387         IdentifierInfo *Name2 = Enum2->getIdentifier();
1388         if (!Name2 && Enum2->getTypedefNameForAnonDecl())
1389           Name2 = Enum2->getTypedefNameForAnonDecl()->getIdentifier();
1390         if (!::IsStructurallyEquivalent(Name1, Name2) ||
1391             !::IsStructurallyEquivalent(*this, Enum1, Enum2))
1392           Equivalent = false;
1393       } else {
1394         // Enum/non-enum mismatch
1395         Equivalent = false;
1396       }
1397     } else if (TypedefNameDecl *Typedef1 = dyn_cast<TypedefNameDecl>(D1)) {
1398       if (TypedefNameDecl *Typedef2 = dyn_cast<TypedefNameDecl>(D2)) {
1399         if (!::IsStructurallyEquivalent(Typedef1->getIdentifier(),
1400                                         Typedef2->getIdentifier()) ||
1401             !::IsStructurallyEquivalent(*this,
1402                                         Typedef1->getUnderlyingType(),
1403                                         Typedef2->getUnderlyingType()))
1404           Equivalent = false;
1405       } else {
1406         // Typedef/non-typedef mismatch.
1407         Equivalent = false;
1408       }
1409     } else if (ClassTemplateDecl *ClassTemplate1
1410                                            = dyn_cast<ClassTemplateDecl>(D1)) {
1411       if (ClassTemplateDecl *ClassTemplate2 = dyn_cast<ClassTemplateDecl>(D2)) {
1412         if (!::IsStructurallyEquivalent(ClassTemplate1->getIdentifier(),
1413                                         ClassTemplate2->getIdentifier()) ||
1414             !::IsStructurallyEquivalent(*this, ClassTemplate1, ClassTemplate2))
1415           Equivalent = false;
1416       } else {
1417         // Class template/non-class-template mismatch.
1418         Equivalent = false;
1419       }
1420     } else if (TemplateTypeParmDecl *TTP1= dyn_cast<TemplateTypeParmDecl>(D1)) {
1421       if (TemplateTypeParmDecl *TTP2 = dyn_cast<TemplateTypeParmDecl>(D2)) {
1422         if (!::IsStructurallyEquivalent(*this, TTP1, TTP2))
1423           Equivalent = false;
1424       } else {
1425         // Kind mismatch.
1426         Equivalent = false;
1427       }
1428     } else if (NonTypeTemplateParmDecl *NTTP1
1429                                      = dyn_cast<NonTypeTemplateParmDecl>(D1)) {
1430       if (NonTypeTemplateParmDecl *NTTP2
1431                                       = dyn_cast<NonTypeTemplateParmDecl>(D2)) {
1432         if (!::IsStructurallyEquivalent(*this, NTTP1, NTTP2))
1433           Equivalent = false;
1434       } else {
1435         // Kind mismatch.
1436         Equivalent = false;
1437       }
1438     } else if (TemplateTemplateParmDecl *TTP1
1439                                   = dyn_cast<TemplateTemplateParmDecl>(D1)) {
1440       if (TemplateTemplateParmDecl *TTP2
1441                                     = dyn_cast<TemplateTemplateParmDecl>(D2)) {
1442         if (!::IsStructurallyEquivalent(*this, TTP1, TTP2))
1443           Equivalent = false;
1444       } else {
1445         // Kind mismatch.
1446         Equivalent = false;
1447       }
1448     }
1449 
1450     if (!Equivalent) {
1451       // Note that these two declarations are not equivalent (and we already
1452       // know about it).
1453       NonEquivalentDecls.insert(std::make_pair(D1->getCanonicalDecl(),
1454                                                D2->getCanonicalDecl()));
1455       return true;
1456     }
1457     // FIXME: Check other declaration kinds!
1458   }
1459 
1460   return false;
1461 }
1462 
1463 //----------------------------------------------------------------------------
1464 // Import Types
1465 //----------------------------------------------------------------------------
1466 
1467 QualType ASTNodeImporter::VisitType(const Type *T) {
1468   Importer.FromDiag(SourceLocation(), diag::err_unsupported_ast_node)
1469     << T->getTypeClassName();
1470   return QualType();
1471 }
1472 
1473 QualType ASTNodeImporter::VisitBuiltinType(const BuiltinType *T) {
1474   switch (T->getKind()) {
1475 #define SHARED_SINGLETON_TYPE(Expansion)
1476 #define BUILTIN_TYPE(Id, SingletonId) \
1477   case BuiltinType::Id: return Importer.getToContext().SingletonId;
1478 #include "clang/AST/BuiltinTypes.def"
1479 
1480   // FIXME: for Char16, Char32, and NullPtr, make sure that the "to"
1481   // context supports C++.
1482 
1483   // FIXME: for ObjCId, ObjCClass, and ObjCSel, make sure that the "to"
1484   // context supports ObjC.
1485 
1486   case BuiltinType::Char_U:
1487     // The context we're importing from has an unsigned 'char'. If we're
1488     // importing into a context with a signed 'char', translate to
1489     // 'unsigned char' instead.
1490     if (Importer.getToContext().getLangOpts().CharIsSigned)
1491       return Importer.getToContext().UnsignedCharTy;
1492 
1493     return Importer.getToContext().CharTy;
1494 
1495   case BuiltinType::Char_S:
1496     // The context we're importing from has an unsigned 'char'. If we're
1497     // importing into a context with a signed 'char', translate to
1498     // 'unsigned char' instead.
1499     if (!Importer.getToContext().getLangOpts().CharIsSigned)
1500       return Importer.getToContext().SignedCharTy;
1501 
1502     return Importer.getToContext().CharTy;
1503 
1504   case BuiltinType::WChar_S:
1505   case BuiltinType::WChar_U:
1506     // FIXME: If not in C++, shall we translate to the C equivalent of
1507     // wchar_t?
1508     return Importer.getToContext().WCharTy;
1509   }
1510 
1511   llvm_unreachable("Invalid BuiltinType Kind!");
1512 }
1513 
1514 QualType ASTNodeImporter::VisitComplexType(const ComplexType *T) {
1515   QualType ToElementType = Importer.Import(T->getElementType());
1516   if (ToElementType.isNull())
1517     return QualType();
1518 
1519   return Importer.getToContext().getComplexType(ToElementType);
1520 }
1521 
1522 QualType ASTNodeImporter::VisitPointerType(const PointerType *T) {
1523   QualType ToPointeeType = Importer.Import(T->getPointeeType());
1524   if (ToPointeeType.isNull())
1525     return QualType();
1526 
1527   return Importer.getToContext().getPointerType(ToPointeeType);
1528 }
1529 
1530 QualType ASTNodeImporter::VisitBlockPointerType(const BlockPointerType *T) {
1531   // FIXME: Check for blocks support in "to" context.
1532   QualType ToPointeeType = Importer.Import(T->getPointeeType());
1533   if (ToPointeeType.isNull())
1534     return QualType();
1535 
1536   return Importer.getToContext().getBlockPointerType(ToPointeeType);
1537 }
1538 
1539 QualType
1540 ASTNodeImporter::VisitLValueReferenceType(const LValueReferenceType *T) {
1541   // FIXME: Check for C++ support in "to" context.
1542   QualType ToPointeeType = Importer.Import(T->getPointeeTypeAsWritten());
1543   if (ToPointeeType.isNull())
1544     return QualType();
1545 
1546   return Importer.getToContext().getLValueReferenceType(ToPointeeType);
1547 }
1548 
1549 QualType
1550 ASTNodeImporter::VisitRValueReferenceType(const RValueReferenceType *T) {
1551   // FIXME: Check for C++0x support in "to" context.
1552   QualType ToPointeeType = Importer.Import(T->getPointeeTypeAsWritten());
1553   if (ToPointeeType.isNull())
1554     return QualType();
1555 
1556   return Importer.getToContext().getRValueReferenceType(ToPointeeType);
1557 }
1558 
1559 QualType ASTNodeImporter::VisitMemberPointerType(const MemberPointerType *T) {
1560   // FIXME: Check for C++ support in "to" context.
1561   QualType ToPointeeType = Importer.Import(T->getPointeeType());
1562   if (ToPointeeType.isNull())
1563     return QualType();
1564 
1565   QualType ClassType = Importer.Import(QualType(T->getClass(), 0));
1566   return Importer.getToContext().getMemberPointerType(ToPointeeType,
1567                                                       ClassType.getTypePtr());
1568 }
1569 
1570 QualType ASTNodeImporter::VisitConstantArrayType(const ConstantArrayType *T) {
1571   QualType ToElementType = Importer.Import(T->getElementType());
1572   if (ToElementType.isNull())
1573     return QualType();
1574 
1575   return Importer.getToContext().getConstantArrayType(ToElementType,
1576                                                       T->getSize(),
1577                                                       T->getSizeModifier(),
1578                                                T->getIndexTypeCVRQualifiers());
1579 }
1580 
1581 QualType
1582 ASTNodeImporter::VisitIncompleteArrayType(const IncompleteArrayType *T) {
1583   QualType ToElementType = Importer.Import(T->getElementType());
1584   if (ToElementType.isNull())
1585     return QualType();
1586 
1587   return Importer.getToContext().getIncompleteArrayType(ToElementType,
1588                                                         T->getSizeModifier(),
1589                                                 T->getIndexTypeCVRQualifiers());
1590 }
1591 
1592 QualType ASTNodeImporter::VisitVariableArrayType(const VariableArrayType *T) {
1593   QualType ToElementType = Importer.Import(T->getElementType());
1594   if (ToElementType.isNull())
1595     return QualType();
1596 
1597   Expr *Size = Importer.Import(T->getSizeExpr());
1598   if (!Size)
1599     return QualType();
1600 
1601   SourceRange Brackets = Importer.Import(T->getBracketsRange());
1602   return Importer.getToContext().getVariableArrayType(ToElementType, Size,
1603                                                       T->getSizeModifier(),
1604                                                 T->getIndexTypeCVRQualifiers(),
1605                                                       Brackets);
1606 }
1607 
1608 QualType ASTNodeImporter::VisitVectorType(const VectorType *T) {
1609   QualType ToElementType = Importer.Import(T->getElementType());
1610   if (ToElementType.isNull())
1611     return QualType();
1612 
1613   return Importer.getToContext().getVectorType(ToElementType,
1614                                                T->getNumElements(),
1615                                                T->getVectorKind());
1616 }
1617 
1618 QualType ASTNodeImporter::VisitExtVectorType(const ExtVectorType *T) {
1619   QualType ToElementType = Importer.Import(T->getElementType());
1620   if (ToElementType.isNull())
1621     return QualType();
1622 
1623   return Importer.getToContext().getExtVectorType(ToElementType,
1624                                                   T->getNumElements());
1625 }
1626 
1627 QualType
1628 ASTNodeImporter::VisitFunctionNoProtoType(const FunctionNoProtoType *T) {
1629   // FIXME: What happens if we're importing a function without a prototype
1630   // into C++? Should we make it variadic?
1631   QualType ToResultType = Importer.Import(T->getReturnType());
1632   if (ToResultType.isNull())
1633     return QualType();
1634 
1635   return Importer.getToContext().getFunctionNoProtoType(ToResultType,
1636                                                         T->getExtInfo());
1637 }
1638 
1639 QualType ASTNodeImporter::VisitFunctionProtoType(const FunctionProtoType *T) {
1640   QualType ToResultType = Importer.Import(T->getReturnType());
1641   if (ToResultType.isNull())
1642     return QualType();
1643 
1644   // Import argument types
1645   SmallVector<QualType, 4> ArgTypes;
1646   for (const auto &A : T->param_types()) {
1647     QualType ArgType = Importer.Import(A);
1648     if (ArgType.isNull())
1649       return QualType();
1650     ArgTypes.push_back(ArgType);
1651   }
1652 
1653   // Import exception types
1654   SmallVector<QualType, 4> ExceptionTypes;
1655   for (const auto &E : T->exceptions()) {
1656     QualType ExceptionType = Importer.Import(E);
1657     if (ExceptionType.isNull())
1658       return QualType();
1659     ExceptionTypes.push_back(ExceptionType);
1660   }
1661 
1662   FunctionProtoType::ExtProtoInfo FromEPI = T->getExtProtoInfo();
1663   FunctionProtoType::ExtProtoInfo ToEPI;
1664 
1665   ToEPI.ExtInfo = FromEPI.ExtInfo;
1666   ToEPI.Variadic = FromEPI.Variadic;
1667   ToEPI.HasTrailingReturn = FromEPI.HasTrailingReturn;
1668   ToEPI.TypeQuals = FromEPI.TypeQuals;
1669   ToEPI.RefQualifier = FromEPI.RefQualifier;
1670   ToEPI.ExceptionSpec.Type = FromEPI.ExceptionSpec.Type;
1671   ToEPI.ExceptionSpec.Exceptions = ExceptionTypes;
1672   ToEPI.ExceptionSpec.NoexceptExpr =
1673       Importer.Import(FromEPI.ExceptionSpec.NoexceptExpr);
1674   ToEPI.ExceptionSpec.SourceDecl = cast_or_null<FunctionDecl>(
1675       Importer.Import(FromEPI.ExceptionSpec.SourceDecl));
1676   ToEPI.ExceptionSpec.SourceTemplate = cast_or_null<FunctionDecl>(
1677       Importer.Import(FromEPI.ExceptionSpec.SourceTemplate));
1678 
1679   return Importer.getToContext().getFunctionType(ToResultType, ArgTypes, ToEPI);
1680 }
1681 
1682 QualType ASTNodeImporter::VisitParenType(const ParenType *T) {
1683   QualType ToInnerType = Importer.Import(T->getInnerType());
1684   if (ToInnerType.isNull())
1685     return QualType();
1686 
1687   return Importer.getToContext().getParenType(ToInnerType);
1688 }
1689 
1690 QualType ASTNodeImporter::VisitTypedefType(const TypedefType *T) {
1691   TypedefNameDecl *ToDecl
1692              = dyn_cast_or_null<TypedefNameDecl>(Importer.Import(T->getDecl()));
1693   if (!ToDecl)
1694     return QualType();
1695 
1696   return Importer.getToContext().getTypeDeclType(ToDecl);
1697 }
1698 
1699 QualType ASTNodeImporter::VisitTypeOfExprType(const TypeOfExprType *T) {
1700   Expr *ToExpr = Importer.Import(T->getUnderlyingExpr());
1701   if (!ToExpr)
1702     return QualType();
1703 
1704   return Importer.getToContext().getTypeOfExprType(ToExpr);
1705 }
1706 
1707 QualType ASTNodeImporter::VisitTypeOfType(const TypeOfType *T) {
1708   QualType ToUnderlyingType = Importer.Import(T->getUnderlyingType());
1709   if (ToUnderlyingType.isNull())
1710     return QualType();
1711 
1712   return Importer.getToContext().getTypeOfType(ToUnderlyingType);
1713 }
1714 
1715 QualType ASTNodeImporter::VisitDecltypeType(const DecltypeType *T) {
1716   // FIXME: Make sure that the "to" context supports C++0x!
1717   Expr *ToExpr = Importer.Import(T->getUnderlyingExpr());
1718   if (!ToExpr)
1719     return QualType();
1720 
1721   QualType UnderlyingType = Importer.Import(T->getUnderlyingType());
1722   if (UnderlyingType.isNull())
1723     return QualType();
1724 
1725   return Importer.getToContext().getDecltypeType(ToExpr, UnderlyingType);
1726 }
1727 
1728 QualType ASTNodeImporter::VisitUnaryTransformType(const UnaryTransformType *T) {
1729   QualType ToBaseType = Importer.Import(T->getBaseType());
1730   QualType ToUnderlyingType = Importer.Import(T->getUnderlyingType());
1731   if (ToBaseType.isNull() || ToUnderlyingType.isNull())
1732     return QualType();
1733 
1734   return Importer.getToContext().getUnaryTransformType(ToBaseType,
1735                                                        ToUnderlyingType,
1736                                                        T->getUTTKind());
1737 }
1738 
1739 QualType ASTNodeImporter::VisitAutoType(const AutoType *T) {
1740   // FIXME: Make sure that the "to" context supports C++11!
1741   QualType FromDeduced = T->getDeducedType();
1742   QualType ToDeduced;
1743   if (!FromDeduced.isNull()) {
1744     ToDeduced = Importer.Import(FromDeduced);
1745     if (ToDeduced.isNull())
1746       return QualType();
1747   }
1748 
1749   return Importer.getToContext().getAutoType(ToDeduced, T->isDecltypeAuto(),
1750                                              /*IsDependent*/false);
1751 }
1752 
1753 QualType ASTNodeImporter::VisitRecordType(const RecordType *T) {
1754   RecordDecl *ToDecl
1755     = dyn_cast_or_null<RecordDecl>(Importer.Import(T->getDecl()));
1756   if (!ToDecl)
1757     return QualType();
1758 
1759   return Importer.getToContext().getTagDeclType(ToDecl);
1760 }
1761 
1762 QualType ASTNodeImporter::VisitEnumType(const EnumType *T) {
1763   EnumDecl *ToDecl
1764     = dyn_cast_or_null<EnumDecl>(Importer.Import(T->getDecl()));
1765   if (!ToDecl)
1766     return QualType();
1767 
1768   return Importer.getToContext().getTagDeclType(ToDecl);
1769 }
1770 
1771 QualType ASTNodeImporter::VisitAttributedType(const AttributedType *T) {
1772   QualType FromModifiedType = T->getModifiedType();
1773   QualType FromEquivalentType = T->getEquivalentType();
1774   QualType ToModifiedType;
1775   QualType ToEquivalentType;
1776 
1777   if (!FromModifiedType.isNull()) {
1778     ToModifiedType = Importer.Import(FromModifiedType);
1779     if (ToModifiedType.isNull())
1780       return QualType();
1781   }
1782   if (!FromEquivalentType.isNull()) {
1783     ToEquivalentType = Importer.Import(FromEquivalentType);
1784     if (ToEquivalentType.isNull())
1785       return QualType();
1786   }
1787 
1788   return Importer.getToContext().getAttributedType(T->getAttrKind(),
1789     ToModifiedType, ToEquivalentType);
1790 }
1791 
1792 QualType ASTNodeImporter::VisitTemplateSpecializationType(
1793                                        const TemplateSpecializationType *T) {
1794   TemplateName ToTemplate = Importer.Import(T->getTemplateName());
1795   if (ToTemplate.isNull())
1796     return QualType();
1797 
1798   SmallVector<TemplateArgument, 2> ToTemplateArgs;
1799   if (ImportTemplateArguments(T->getArgs(), T->getNumArgs(), ToTemplateArgs))
1800     return QualType();
1801 
1802   QualType ToCanonType;
1803   if (!QualType(T, 0).isCanonical()) {
1804     QualType FromCanonType
1805       = Importer.getFromContext().getCanonicalType(QualType(T, 0));
1806     ToCanonType =Importer.Import(FromCanonType);
1807     if (ToCanonType.isNull())
1808       return QualType();
1809   }
1810   return Importer.getToContext().getTemplateSpecializationType(ToTemplate,
1811                                                          ToTemplateArgs.data(),
1812                                                          ToTemplateArgs.size(),
1813                                                                ToCanonType);
1814 }
1815 
1816 QualType ASTNodeImporter::VisitElaboratedType(const ElaboratedType *T) {
1817   NestedNameSpecifier *ToQualifier = nullptr;
1818   // Note: the qualifier in an ElaboratedType is optional.
1819   if (T->getQualifier()) {
1820     ToQualifier = Importer.Import(T->getQualifier());
1821     if (!ToQualifier)
1822       return QualType();
1823   }
1824 
1825   QualType ToNamedType = Importer.Import(T->getNamedType());
1826   if (ToNamedType.isNull())
1827     return QualType();
1828 
1829   return Importer.getToContext().getElaboratedType(T->getKeyword(),
1830                                                    ToQualifier, ToNamedType);
1831 }
1832 
1833 QualType ASTNodeImporter::VisitObjCInterfaceType(const ObjCInterfaceType *T) {
1834   ObjCInterfaceDecl *Class
1835     = dyn_cast_or_null<ObjCInterfaceDecl>(Importer.Import(T->getDecl()));
1836   if (!Class)
1837     return QualType();
1838 
1839   return Importer.getToContext().getObjCInterfaceType(Class);
1840 }
1841 
1842 QualType ASTNodeImporter::VisitObjCObjectType(const ObjCObjectType *T) {
1843   QualType ToBaseType = Importer.Import(T->getBaseType());
1844   if (ToBaseType.isNull())
1845     return QualType();
1846 
1847   SmallVector<QualType, 4> TypeArgs;
1848   for (auto TypeArg : T->getTypeArgsAsWritten()) {
1849     QualType ImportedTypeArg = Importer.Import(TypeArg);
1850     if (ImportedTypeArg.isNull())
1851       return QualType();
1852 
1853     TypeArgs.push_back(ImportedTypeArg);
1854   }
1855 
1856   SmallVector<ObjCProtocolDecl *, 4> Protocols;
1857   for (auto *P : T->quals()) {
1858     ObjCProtocolDecl *Protocol
1859       = dyn_cast_or_null<ObjCProtocolDecl>(Importer.Import(P));
1860     if (!Protocol)
1861       return QualType();
1862     Protocols.push_back(Protocol);
1863   }
1864 
1865   return Importer.getToContext().getObjCObjectType(ToBaseType, TypeArgs,
1866                                                    Protocols,
1867                                                    T->isKindOfTypeAsWritten());
1868 }
1869 
1870 QualType
1871 ASTNodeImporter::VisitObjCObjectPointerType(const ObjCObjectPointerType *T) {
1872   QualType ToPointeeType = Importer.Import(T->getPointeeType());
1873   if (ToPointeeType.isNull())
1874     return QualType();
1875 
1876   return Importer.getToContext().getObjCObjectPointerType(ToPointeeType);
1877 }
1878 
1879 //----------------------------------------------------------------------------
1880 // Import Declarations
1881 //----------------------------------------------------------------------------
1882 bool ASTNodeImporter::ImportDeclParts(NamedDecl *D, DeclContext *&DC,
1883                                       DeclContext *&LexicalDC,
1884                                       DeclarationName &Name,
1885                                       NamedDecl *&ToD,
1886                                       SourceLocation &Loc) {
1887   // Import the context of this declaration.
1888   DC = Importer.ImportContext(D->getDeclContext());
1889   if (!DC)
1890     return true;
1891 
1892   LexicalDC = DC;
1893   if (D->getDeclContext() != D->getLexicalDeclContext()) {
1894     LexicalDC = Importer.ImportContext(D->getLexicalDeclContext());
1895     if (!LexicalDC)
1896       return true;
1897   }
1898 
1899   // Import the name of this declaration.
1900   Name = Importer.Import(D->getDeclName());
1901   if (D->getDeclName() && !Name)
1902     return true;
1903 
1904   // Import the location of this declaration.
1905   Loc = Importer.Import(D->getLocation());
1906   ToD = cast_or_null<NamedDecl>(Importer.GetAlreadyImportedOrNull(D));
1907   return false;
1908 }
1909 
1910 void ASTNodeImporter::ImportDefinitionIfNeeded(Decl *FromD, Decl *ToD) {
1911   if (!FromD)
1912     return;
1913 
1914   if (!ToD) {
1915     ToD = Importer.Import(FromD);
1916     if (!ToD)
1917       return;
1918   }
1919 
1920   if (RecordDecl *FromRecord = dyn_cast<RecordDecl>(FromD)) {
1921     if (RecordDecl *ToRecord = cast_or_null<RecordDecl>(ToD)) {
1922       if (FromRecord->getDefinition() && FromRecord->isCompleteDefinition() && !ToRecord->getDefinition()) {
1923         ImportDefinition(FromRecord, ToRecord);
1924       }
1925     }
1926     return;
1927   }
1928 
1929   if (EnumDecl *FromEnum = dyn_cast<EnumDecl>(FromD)) {
1930     if (EnumDecl *ToEnum = cast_or_null<EnumDecl>(ToD)) {
1931       if (FromEnum->getDefinition() && !ToEnum->getDefinition()) {
1932         ImportDefinition(FromEnum, ToEnum);
1933       }
1934     }
1935     return;
1936   }
1937 }
1938 
1939 void
1940 ASTNodeImporter::ImportDeclarationNameLoc(const DeclarationNameInfo &From,
1941                                           DeclarationNameInfo& To) {
1942   // NOTE: To.Name and To.Loc are already imported.
1943   // We only have to import To.LocInfo.
1944   switch (To.getName().getNameKind()) {
1945   case DeclarationName::Identifier:
1946   case DeclarationName::ObjCZeroArgSelector:
1947   case DeclarationName::ObjCOneArgSelector:
1948   case DeclarationName::ObjCMultiArgSelector:
1949   case DeclarationName::CXXUsingDirective:
1950     return;
1951 
1952   case DeclarationName::CXXOperatorName: {
1953     SourceRange Range = From.getCXXOperatorNameRange();
1954     To.setCXXOperatorNameRange(Importer.Import(Range));
1955     return;
1956   }
1957   case DeclarationName::CXXLiteralOperatorName: {
1958     SourceLocation Loc = From.getCXXLiteralOperatorNameLoc();
1959     To.setCXXLiteralOperatorNameLoc(Importer.Import(Loc));
1960     return;
1961   }
1962   case DeclarationName::CXXConstructorName:
1963   case DeclarationName::CXXDestructorName:
1964   case DeclarationName::CXXConversionFunctionName: {
1965     TypeSourceInfo *FromTInfo = From.getNamedTypeInfo();
1966     To.setNamedTypeInfo(Importer.Import(FromTInfo));
1967     return;
1968   }
1969   }
1970   llvm_unreachable("Unknown name kind.");
1971 }
1972 
1973 void ASTNodeImporter::ImportDeclContext(DeclContext *FromDC, bool ForceImport) {
1974   if (Importer.isMinimalImport() && !ForceImport) {
1975     Importer.ImportContext(FromDC);
1976     return;
1977   }
1978 
1979   for (auto *From : FromDC->decls())
1980     Importer.Import(From);
1981 }
1982 
1983 bool ASTNodeImporter::ImportDefinition(RecordDecl *From, RecordDecl *To,
1984                                        ImportDefinitionKind Kind) {
1985   if (To->getDefinition() || To->isBeingDefined()) {
1986     if (Kind == IDK_Everything)
1987       ImportDeclContext(From, /*ForceImport=*/true);
1988 
1989     return false;
1990   }
1991 
1992   To->startDefinition();
1993 
1994   // Add base classes.
1995   if (CXXRecordDecl *ToCXX = dyn_cast<CXXRecordDecl>(To)) {
1996     CXXRecordDecl *FromCXX = cast<CXXRecordDecl>(From);
1997 
1998     struct CXXRecordDecl::DefinitionData &ToData = ToCXX->data();
1999     struct CXXRecordDecl::DefinitionData &FromData = FromCXX->data();
2000     ToData.UserDeclaredConstructor = FromData.UserDeclaredConstructor;
2001     ToData.UserDeclaredSpecialMembers = FromData.UserDeclaredSpecialMembers;
2002     ToData.Aggregate = FromData.Aggregate;
2003     ToData.PlainOldData = FromData.PlainOldData;
2004     ToData.Empty = FromData.Empty;
2005     ToData.Polymorphic = FromData.Polymorphic;
2006     ToData.Abstract = FromData.Abstract;
2007     ToData.IsStandardLayout = FromData.IsStandardLayout;
2008     ToData.HasNoNonEmptyBases = FromData.HasNoNonEmptyBases;
2009     ToData.HasPrivateFields = FromData.HasPrivateFields;
2010     ToData.HasProtectedFields = FromData.HasProtectedFields;
2011     ToData.HasPublicFields = FromData.HasPublicFields;
2012     ToData.HasMutableFields = FromData.HasMutableFields;
2013     ToData.HasVariantMembers = FromData.HasVariantMembers;
2014     ToData.HasOnlyCMembers = FromData.HasOnlyCMembers;
2015     ToData.HasInClassInitializer = FromData.HasInClassInitializer;
2016     ToData.HasUninitializedReferenceMember
2017       = FromData.HasUninitializedReferenceMember;
2018     ToData.NeedOverloadResolutionForMoveConstructor
2019       = FromData.NeedOverloadResolutionForMoveConstructor;
2020     ToData.NeedOverloadResolutionForMoveAssignment
2021       = FromData.NeedOverloadResolutionForMoveAssignment;
2022     ToData.NeedOverloadResolutionForDestructor
2023       = FromData.NeedOverloadResolutionForDestructor;
2024     ToData.DefaultedMoveConstructorIsDeleted
2025       = FromData.DefaultedMoveConstructorIsDeleted;
2026     ToData.DefaultedMoveAssignmentIsDeleted
2027       = FromData.DefaultedMoveAssignmentIsDeleted;
2028     ToData.DefaultedDestructorIsDeleted = FromData.DefaultedDestructorIsDeleted;
2029     ToData.HasTrivialSpecialMembers = FromData.HasTrivialSpecialMembers;
2030     ToData.HasIrrelevantDestructor = FromData.HasIrrelevantDestructor;
2031     ToData.HasConstexprNonCopyMoveConstructor
2032       = FromData.HasConstexprNonCopyMoveConstructor;
2033     ToData.DefaultedDefaultConstructorIsConstexpr
2034       = FromData.DefaultedDefaultConstructorIsConstexpr;
2035     ToData.HasConstexprDefaultConstructor
2036       = FromData.HasConstexprDefaultConstructor;
2037     ToData.HasNonLiteralTypeFieldsOrBases
2038       = FromData.HasNonLiteralTypeFieldsOrBases;
2039     // ComputedVisibleConversions not imported.
2040     ToData.UserProvidedDefaultConstructor
2041       = FromData.UserProvidedDefaultConstructor;
2042     ToData.DeclaredSpecialMembers = FromData.DeclaredSpecialMembers;
2043     ToData.ImplicitCopyConstructorHasConstParam
2044       = FromData.ImplicitCopyConstructorHasConstParam;
2045     ToData.ImplicitCopyAssignmentHasConstParam
2046       = FromData.ImplicitCopyAssignmentHasConstParam;
2047     ToData.HasDeclaredCopyConstructorWithConstParam
2048       = FromData.HasDeclaredCopyConstructorWithConstParam;
2049     ToData.HasDeclaredCopyAssignmentWithConstParam
2050       = FromData.HasDeclaredCopyAssignmentWithConstParam;
2051     ToData.IsLambda = FromData.IsLambda;
2052 
2053     SmallVector<CXXBaseSpecifier *, 4> Bases;
2054     for (const auto &Base1 : FromCXX->bases()) {
2055       QualType T = Importer.Import(Base1.getType());
2056       if (T.isNull())
2057         return true;
2058 
2059       SourceLocation EllipsisLoc;
2060       if (Base1.isPackExpansion())
2061         EllipsisLoc = Importer.Import(Base1.getEllipsisLoc());
2062 
2063       // Ensure that we have a definition for the base.
2064       ImportDefinitionIfNeeded(Base1.getType()->getAsCXXRecordDecl());
2065 
2066       Bases.push_back(
2067                     new (Importer.getToContext())
2068                       CXXBaseSpecifier(Importer.Import(Base1.getSourceRange()),
2069                                        Base1.isVirtual(),
2070                                        Base1.isBaseOfClass(),
2071                                        Base1.getAccessSpecifierAsWritten(),
2072                                    Importer.Import(Base1.getTypeSourceInfo()),
2073                                        EllipsisLoc));
2074     }
2075     if (!Bases.empty())
2076       ToCXX->setBases(Bases.data(), Bases.size());
2077   }
2078 
2079   if (shouldForceImportDeclContext(Kind))
2080     ImportDeclContext(From, /*ForceImport=*/true);
2081 
2082   To->completeDefinition();
2083   return false;
2084 }
2085 
2086 bool ASTNodeImporter::ImportDefinition(VarDecl *From, VarDecl *To,
2087                                        ImportDefinitionKind Kind) {
2088   if (To->getAnyInitializer())
2089     return false;
2090 
2091   // FIXME: Can we really import any initializer? Alternatively, we could force
2092   // ourselves to import every declaration of a variable and then only use
2093   // getInit() here.
2094   To->setInit(Importer.Import(const_cast<Expr *>(From->getAnyInitializer())));
2095 
2096   // FIXME: Other bits to merge?
2097 
2098   return false;
2099 }
2100 
2101 bool ASTNodeImporter::ImportDefinition(EnumDecl *From, EnumDecl *To,
2102                                        ImportDefinitionKind Kind) {
2103   if (To->getDefinition() || To->isBeingDefined()) {
2104     if (Kind == IDK_Everything)
2105       ImportDeclContext(From, /*ForceImport=*/true);
2106     return false;
2107   }
2108 
2109   To->startDefinition();
2110 
2111   QualType T = Importer.Import(Importer.getFromContext().getTypeDeclType(From));
2112   if (T.isNull())
2113     return true;
2114 
2115   QualType ToPromotionType = Importer.Import(From->getPromotionType());
2116   if (ToPromotionType.isNull())
2117     return true;
2118 
2119   if (shouldForceImportDeclContext(Kind))
2120     ImportDeclContext(From, /*ForceImport=*/true);
2121 
2122   // FIXME: we might need to merge the number of positive or negative bits
2123   // if the enumerator lists don't match.
2124   To->completeDefinition(T, ToPromotionType,
2125                          From->getNumPositiveBits(),
2126                          From->getNumNegativeBits());
2127   return false;
2128 }
2129 
2130 TemplateParameterList *ASTNodeImporter::ImportTemplateParameterList(
2131                                                 TemplateParameterList *Params) {
2132   SmallVector<NamedDecl *, 4> ToParams;
2133   ToParams.reserve(Params->size());
2134   for (TemplateParameterList::iterator P = Params->begin(),
2135                                     PEnd = Params->end();
2136        P != PEnd; ++P) {
2137     Decl *To = Importer.Import(*P);
2138     if (!To)
2139       return nullptr;
2140 
2141     ToParams.push_back(cast<NamedDecl>(To));
2142   }
2143 
2144   return TemplateParameterList::Create(Importer.getToContext(),
2145                                        Importer.Import(Params->getTemplateLoc()),
2146                                        Importer.Import(Params->getLAngleLoc()),
2147                                        ToParams.data(), ToParams.size(),
2148                                        Importer.Import(Params->getRAngleLoc()));
2149 }
2150 
2151 TemplateArgument
2152 ASTNodeImporter::ImportTemplateArgument(const TemplateArgument &From) {
2153   switch (From.getKind()) {
2154   case TemplateArgument::Null:
2155     return TemplateArgument();
2156 
2157   case TemplateArgument::Type: {
2158     QualType ToType = Importer.Import(From.getAsType());
2159     if (ToType.isNull())
2160       return TemplateArgument();
2161     return TemplateArgument(ToType);
2162   }
2163 
2164   case TemplateArgument::Integral: {
2165     QualType ToType = Importer.Import(From.getIntegralType());
2166     if (ToType.isNull())
2167       return TemplateArgument();
2168     return TemplateArgument(From, ToType);
2169   }
2170 
2171   case TemplateArgument::Declaration: {
2172     ValueDecl *To = cast_or_null<ValueDecl>(Importer.Import(From.getAsDecl()));
2173     QualType ToType = Importer.Import(From.getParamTypeForDecl());
2174     if (!To || ToType.isNull())
2175       return TemplateArgument();
2176     return TemplateArgument(To, ToType);
2177   }
2178 
2179   case TemplateArgument::NullPtr: {
2180     QualType ToType = Importer.Import(From.getNullPtrType());
2181     if (ToType.isNull())
2182       return TemplateArgument();
2183     return TemplateArgument(ToType, /*isNullPtr*/true);
2184   }
2185 
2186   case TemplateArgument::Template: {
2187     TemplateName ToTemplate = Importer.Import(From.getAsTemplate());
2188     if (ToTemplate.isNull())
2189       return TemplateArgument();
2190 
2191     return TemplateArgument(ToTemplate);
2192   }
2193 
2194   case TemplateArgument::TemplateExpansion: {
2195     TemplateName ToTemplate
2196       = Importer.Import(From.getAsTemplateOrTemplatePattern());
2197     if (ToTemplate.isNull())
2198       return TemplateArgument();
2199 
2200     return TemplateArgument(ToTemplate, From.getNumTemplateExpansions());
2201   }
2202 
2203   case TemplateArgument::Expression:
2204     if (Expr *ToExpr = Importer.Import(From.getAsExpr()))
2205       return TemplateArgument(ToExpr);
2206     return TemplateArgument();
2207 
2208   case TemplateArgument::Pack: {
2209     SmallVector<TemplateArgument, 2> ToPack;
2210     ToPack.reserve(From.pack_size());
2211     if (ImportTemplateArguments(From.pack_begin(), From.pack_size(), ToPack))
2212       return TemplateArgument();
2213 
2214     TemplateArgument *ToArgs
2215       = new (Importer.getToContext()) TemplateArgument[ToPack.size()];
2216     std::copy(ToPack.begin(), ToPack.end(), ToArgs);
2217     return TemplateArgument(ToArgs, ToPack.size());
2218   }
2219   }
2220 
2221   llvm_unreachable("Invalid template argument kind");
2222 }
2223 
2224 bool ASTNodeImporter::ImportTemplateArguments(const TemplateArgument *FromArgs,
2225                                               unsigned NumFromArgs,
2226                               SmallVectorImpl<TemplateArgument> &ToArgs) {
2227   for (unsigned I = 0; I != NumFromArgs; ++I) {
2228     TemplateArgument To = ImportTemplateArgument(FromArgs[I]);
2229     if (To.isNull() && !FromArgs[I].isNull())
2230       return true;
2231 
2232     ToArgs.push_back(To);
2233   }
2234 
2235   return false;
2236 }
2237 
2238 bool ASTNodeImporter::IsStructuralMatch(RecordDecl *FromRecord,
2239                                         RecordDecl *ToRecord, bool Complain) {
2240   // Eliminate a potential failure point where we attempt to re-import
2241   // something we're trying to import while completing ToRecord.
2242   Decl *ToOrigin = Importer.GetOriginalDecl(ToRecord);
2243   if (ToOrigin) {
2244     RecordDecl *ToOriginRecord = dyn_cast<RecordDecl>(ToOrigin);
2245     if (ToOriginRecord)
2246       ToRecord = ToOriginRecord;
2247   }
2248 
2249   StructuralEquivalenceContext Ctx(Importer.getFromContext(),
2250                                    ToRecord->getASTContext(),
2251                                    Importer.getNonEquivalentDecls(),
2252                                    false, Complain);
2253   return Ctx.IsStructurallyEquivalent(FromRecord, ToRecord);
2254 }
2255 
2256 bool ASTNodeImporter::IsStructuralMatch(VarDecl *FromVar, VarDecl *ToVar,
2257                                         bool Complain) {
2258   StructuralEquivalenceContext Ctx(
2259       Importer.getFromContext(), Importer.getToContext(),
2260       Importer.getNonEquivalentDecls(), false, Complain);
2261   return Ctx.IsStructurallyEquivalent(FromVar, ToVar);
2262 }
2263 
2264 bool ASTNodeImporter::IsStructuralMatch(EnumDecl *FromEnum, EnumDecl *ToEnum) {
2265   StructuralEquivalenceContext Ctx(Importer.getFromContext(),
2266                                    Importer.getToContext(),
2267                                    Importer.getNonEquivalentDecls());
2268   return Ctx.IsStructurallyEquivalent(FromEnum, ToEnum);
2269 }
2270 
2271 bool ASTNodeImporter::IsStructuralMatch(EnumConstantDecl *FromEC,
2272                                         EnumConstantDecl *ToEC)
2273 {
2274   const llvm::APSInt &FromVal = FromEC->getInitVal();
2275   const llvm::APSInt &ToVal = ToEC->getInitVal();
2276 
2277   return FromVal.isSigned() == ToVal.isSigned() &&
2278          FromVal.getBitWidth() == ToVal.getBitWidth() &&
2279          FromVal == ToVal;
2280 }
2281 
2282 bool ASTNodeImporter::IsStructuralMatch(ClassTemplateDecl *From,
2283                                         ClassTemplateDecl *To) {
2284   StructuralEquivalenceContext Ctx(Importer.getFromContext(),
2285                                    Importer.getToContext(),
2286                                    Importer.getNonEquivalentDecls());
2287   return Ctx.IsStructurallyEquivalent(From, To);
2288 }
2289 
2290 bool ASTNodeImporter::IsStructuralMatch(VarTemplateDecl *From,
2291                                         VarTemplateDecl *To) {
2292   StructuralEquivalenceContext Ctx(Importer.getFromContext(),
2293                                    Importer.getToContext(),
2294                                    Importer.getNonEquivalentDecls());
2295   return Ctx.IsStructurallyEquivalent(From, To);
2296 }
2297 
2298 Decl *ASTNodeImporter::VisitDecl(Decl *D) {
2299   Importer.FromDiag(D->getLocation(), diag::err_unsupported_ast_node)
2300     << D->getDeclKindName();
2301   return nullptr;
2302 }
2303 
2304 Decl *ASTNodeImporter::VisitTranslationUnitDecl(TranslationUnitDecl *D) {
2305   TranslationUnitDecl *ToD =
2306     Importer.getToContext().getTranslationUnitDecl();
2307 
2308   Importer.Imported(D, ToD);
2309 
2310   return ToD;
2311 }
2312 
2313 Decl *ASTNodeImporter::VisitNamespaceDecl(NamespaceDecl *D) {
2314   // Import the major distinguishing characteristics of this namespace.
2315   DeclContext *DC, *LexicalDC;
2316   DeclarationName Name;
2317   SourceLocation Loc;
2318   NamedDecl *ToD;
2319   if (ImportDeclParts(D, DC, LexicalDC, Name, ToD, Loc))
2320     return nullptr;
2321   if (ToD)
2322     return ToD;
2323 
2324   NamespaceDecl *MergeWithNamespace = nullptr;
2325   if (!Name) {
2326     // This is an anonymous namespace. Adopt an existing anonymous
2327     // namespace if we can.
2328     // FIXME: Not testable.
2329     if (TranslationUnitDecl *TU = dyn_cast<TranslationUnitDecl>(DC))
2330       MergeWithNamespace = TU->getAnonymousNamespace();
2331     else
2332       MergeWithNamespace = cast<NamespaceDecl>(DC)->getAnonymousNamespace();
2333   } else {
2334     SmallVector<NamedDecl *, 4> ConflictingDecls;
2335     SmallVector<NamedDecl *, 2> FoundDecls;
2336     DC->getRedeclContext()->localUncachedLookup(Name, FoundDecls);
2337     for (unsigned I = 0, N = FoundDecls.size(); I != N; ++I) {
2338       if (!FoundDecls[I]->isInIdentifierNamespace(Decl::IDNS_Namespace))
2339         continue;
2340 
2341       if (NamespaceDecl *FoundNS = dyn_cast<NamespaceDecl>(FoundDecls[I])) {
2342         MergeWithNamespace = FoundNS;
2343         ConflictingDecls.clear();
2344         break;
2345       }
2346 
2347       ConflictingDecls.push_back(FoundDecls[I]);
2348     }
2349 
2350     if (!ConflictingDecls.empty()) {
2351       Name = Importer.HandleNameConflict(Name, DC, Decl::IDNS_Namespace,
2352                                          ConflictingDecls.data(),
2353                                          ConflictingDecls.size());
2354     }
2355   }
2356 
2357   // Create the "to" namespace, if needed.
2358   NamespaceDecl *ToNamespace = MergeWithNamespace;
2359   if (!ToNamespace) {
2360     ToNamespace = NamespaceDecl::Create(Importer.getToContext(), DC,
2361                                         D->isInline(),
2362                                         Importer.Import(D->getLocStart()),
2363                                         Loc, Name.getAsIdentifierInfo(),
2364                                         /*PrevDecl=*/nullptr);
2365     ToNamespace->setLexicalDeclContext(LexicalDC);
2366     LexicalDC->addDeclInternal(ToNamespace);
2367 
2368     // If this is an anonymous namespace, register it as the anonymous
2369     // namespace within its context.
2370     if (!Name) {
2371       if (TranslationUnitDecl *TU = dyn_cast<TranslationUnitDecl>(DC))
2372         TU->setAnonymousNamespace(ToNamespace);
2373       else
2374         cast<NamespaceDecl>(DC)->setAnonymousNamespace(ToNamespace);
2375     }
2376   }
2377   Importer.Imported(D, ToNamespace);
2378 
2379   ImportDeclContext(D);
2380 
2381   return ToNamespace;
2382 }
2383 
2384 Decl *ASTNodeImporter::VisitTypedefNameDecl(TypedefNameDecl *D, bool IsAlias) {
2385   // Import the major distinguishing characteristics of this typedef.
2386   DeclContext *DC, *LexicalDC;
2387   DeclarationName Name;
2388   SourceLocation Loc;
2389   NamedDecl *ToD;
2390   if (ImportDeclParts(D, DC, LexicalDC, Name, ToD, Loc))
2391     return nullptr;
2392   if (ToD)
2393     return ToD;
2394 
2395   // If this typedef is not in block scope, determine whether we've
2396   // seen a typedef with the same name (that we can merge with) or any
2397   // other entity by that name (which name lookup could conflict with).
2398   if (!DC->isFunctionOrMethod()) {
2399     SmallVector<NamedDecl *, 4> ConflictingDecls;
2400     unsigned IDNS = Decl::IDNS_Ordinary;
2401     SmallVector<NamedDecl *, 2> FoundDecls;
2402     DC->getRedeclContext()->localUncachedLookup(Name, FoundDecls);
2403     for (unsigned I = 0, N = FoundDecls.size(); I != N; ++I) {
2404       if (!FoundDecls[I]->isInIdentifierNamespace(IDNS))
2405         continue;
2406       if (TypedefNameDecl *FoundTypedef =
2407             dyn_cast<TypedefNameDecl>(FoundDecls[I])) {
2408         if (Importer.IsStructurallyEquivalent(D->getUnderlyingType(),
2409                                             FoundTypedef->getUnderlyingType()))
2410           return Importer.Imported(D, FoundTypedef);
2411       }
2412 
2413       ConflictingDecls.push_back(FoundDecls[I]);
2414     }
2415 
2416     if (!ConflictingDecls.empty()) {
2417       Name = Importer.HandleNameConflict(Name, DC, IDNS,
2418                                          ConflictingDecls.data(),
2419                                          ConflictingDecls.size());
2420       if (!Name)
2421         return nullptr;
2422     }
2423   }
2424 
2425   // Import the underlying type of this typedef;
2426   QualType T = Importer.Import(D->getUnderlyingType());
2427   if (T.isNull())
2428     return nullptr;
2429 
2430   // Create the new typedef node.
2431   TypeSourceInfo *TInfo = Importer.Import(D->getTypeSourceInfo());
2432   SourceLocation StartL = Importer.Import(D->getLocStart());
2433   TypedefNameDecl *ToTypedef;
2434   if (IsAlias)
2435     ToTypedef = TypeAliasDecl::Create(Importer.getToContext(), DC,
2436                                       StartL, Loc,
2437                                       Name.getAsIdentifierInfo(),
2438                                       TInfo);
2439   else
2440     ToTypedef = TypedefDecl::Create(Importer.getToContext(), DC,
2441                                     StartL, Loc,
2442                                     Name.getAsIdentifierInfo(),
2443                                     TInfo);
2444 
2445   ToTypedef->setAccess(D->getAccess());
2446   ToTypedef->setLexicalDeclContext(LexicalDC);
2447   Importer.Imported(D, ToTypedef);
2448   LexicalDC->addDeclInternal(ToTypedef);
2449 
2450   return ToTypedef;
2451 }
2452 
2453 Decl *ASTNodeImporter::VisitTypedefDecl(TypedefDecl *D) {
2454   return VisitTypedefNameDecl(D, /*IsAlias=*/false);
2455 }
2456 
2457 Decl *ASTNodeImporter::VisitTypeAliasDecl(TypeAliasDecl *D) {
2458   return VisitTypedefNameDecl(D, /*IsAlias=*/true);
2459 }
2460 
2461 Decl *ASTNodeImporter::VisitEnumDecl(EnumDecl *D) {
2462   // Import the major distinguishing characteristics of this enum.
2463   DeclContext *DC, *LexicalDC;
2464   DeclarationName Name;
2465   SourceLocation Loc;
2466   NamedDecl *ToD;
2467   if (ImportDeclParts(D, DC, LexicalDC, Name, ToD, Loc))
2468     return nullptr;
2469   if (ToD)
2470     return ToD;
2471 
2472   // Figure out what enum name we're looking for.
2473   unsigned IDNS = Decl::IDNS_Tag;
2474   DeclarationName SearchName = Name;
2475   if (!SearchName && D->getTypedefNameForAnonDecl()) {
2476     SearchName = Importer.Import(D->getTypedefNameForAnonDecl()->getDeclName());
2477     IDNS = Decl::IDNS_Ordinary;
2478   } else if (Importer.getToContext().getLangOpts().CPlusPlus)
2479     IDNS |= Decl::IDNS_Ordinary;
2480 
2481   // We may already have an enum of the same name; try to find and match it.
2482   if (!DC->isFunctionOrMethod() && SearchName) {
2483     SmallVector<NamedDecl *, 4> ConflictingDecls;
2484     SmallVector<NamedDecl *, 2> FoundDecls;
2485     DC->getRedeclContext()->localUncachedLookup(Name, FoundDecls);
2486     for (unsigned I = 0, N = FoundDecls.size(); I != N; ++I) {
2487       if (!FoundDecls[I]->isInIdentifierNamespace(IDNS))
2488         continue;
2489 
2490       Decl *Found = FoundDecls[I];
2491       if (TypedefNameDecl *Typedef = dyn_cast<TypedefNameDecl>(Found)) {
2492         if (const TagType *Tag = Typedef->getUnderlyingType()->getAs<TagType>())
2493           Found = Tag->getDecl();
2494       }
2495 
2496       if (EnumDecl *FoundEnum = dyn_cast<EnumDecl>(Found)) {
2497         if (IsStructuralMatch(D, FoundEnum))
2498           return Importer.Imported(D, FoundEnum);
2499       }
2500 
2501       ConflictingDecls.push_back(FoundDecls[I]);
2502     }
2503 
2504     if (!ConflictingDecls.empty()) {
2505       Name = Importer.HandleNameConflict(Name, DC, IDNS,
2506                                          ConflictingDecls.data(),
2507                                          ConflictingDecls.size());
2508     }
2509   }
2510 
2511   // Create the enum declaration.
2512   EnumDecl *D2 = EnumDecl::Create(Importer.getToContext(), DC,
2513                                   Importer.Import(D->getLocStart()),
2514                                   Loc, Name.getAsIdentifierInfo(), nullptr,
2515                                   D->isScoped(), D->isScopedUsingClassTag(),
2516                                   D->isFixed());
2517   // Import the qualifier, if any.
2518   D2->setQualifierInfo(Importer.Import(D->getQualifierLoc()));
2519   D2->setAccess(D->getAccess());
2520   D2->setLexicalDeclContext(LexicalDC);
2521   Importer.Imported(D, D2);
2522   LexicalDC->addDeclInternal(D2);
2523 
2524   // Import the integer type.
2525   QualType ToIntegerType = Importer.Import(D->getIntegerType());
2526   if (ToIntegerType.isNull())
2527     return nullptr;
2528   D2->setIntegerType(ToIntegerType);
2529 
2530   // Import the definition
2531   if (D->isCompleteDefinition() && ImportDefinition(D, D2))
2532     return nullptr;
2533 
2534   return D2;
2535 }
2536 
2537 Decl *ASTNodeImporter::VisitRecordDecl(RecordDecl *D) {
2538   // If this record has a definition in the translation unit we're coming from,
2539   // but this particular declaration is not that definition, import the
2540   // definition and map to that.
2541   TagDecl *Definition = D->getDefinition();
2542   if (Definition && Definition != D) {
2543     Decl *ImportedDef = Importer.Import(Definition);
2544     if (!ImportedDef)
2545       return nullptr;
2546 
2547     return Importer.Imported(D, ImportedDef);
2548   }
2549 
2550   // Import the major distinguishing characteristics of this record.
2551   DeclContext *DC, *LexicalDC;
2552   DeclarationName Name;
2553   SourceLocation Loc;
2554   NamedDecl *ToD;
2555   if (ImportDeclParts(D, DC, LexicalDC, Name, ToD, Loc))
2556     return nullptr;
2557   if (ToD)
2558     return ToD;
2559 
2560   // Figure out what structure name we're looking for.
2561   unsigned IDNS = Decl::IDNS_Tag;
2562   DeclarationName SearchName = Name;
2563   if (!SearchName && D->getTypedefNameForAnonDecl()) {
2564     SearchName = Importer.Import(D->getTypedefNameForAnonDecl()->getDeclName());
2565     IDNS = Decl::IDNS_Ordinary;
2566   } else if (Importer.getToContext().getLangOpts().CPlusPlus)
2567     IDNS |= Decl::IDNS_Ordinary;
2568 
2569   // We may already have a record of the same name; try to find and match it.
2570   RecordDecl *AdoptDecl = nullptr;
2571   if (!DC->isFunctionOrMethod()) {
2572     SmallVector<NamedDecl *, 4> ConflictingDecls;
2573     SmallVector<NamedDecl *, 2> FoundDecls;
2574     DC->getRedeclContext()->localUncachedLookup(Name, FoundDecls);
2575     for (unsigned I = 0, N = FoundDecls.size(); I != N; ++I) {
2576       if (!FoundDecls[I]->isInIdentifierNamespace(IDNS))
2577         continue;
2578 
2579       Decl *Found = FoundDecls[I];
2580       if (TypedefNameDecl *Typedef = dyn_cast<TypedefNameDecl>(Found)) {
2581         if (const TagType *Tag = Typedef->getUnderlyingType()->getAs<TagType>())
2582           Found = Tag->getDecl();
2583       }
2584 
2585       if (RecordDecl *FoundRecord = dyn_cast<RecordDecl>(Found)) {
2586         if (D->isAnonymousStructOrUnion() &&
2587             FoundRecord->isAnonymousStructOrUnion()) {
2588           // If both anonymous structs/unions are in a record context, make sure
2589           // they occur in the same location in the context records.
2590           if (Optional<unsigned> Index1
2591               = findAnonymousStructOrUnionIndex(D)) {
2592             if (Optional<unsigned> Index2 =
2593                     findAnonymousStructOrUnionIndex(FoundRecord)) {
2594               if (*Index1 != *Index2)
2595                 continue;
2596             }
2597           }
2598         }
2599 
2600         if (RecordDecl *FoundDef = FoundRecord->getDefinition()) {
2601           if ((SearchName && !D->isCompleteDefinition())
2602               || (D->isCompleteDefinition() &&
2603                   D->isAnonymousStructOrUnion()
2604                     == FoundDef->isAnonymousStructOrUnion() &&
2605                   IsStructuralMatch(D, FoundDef))) {
2606             // The record types structurally match, or the "from" translation
2607             // unit only had a forward declaration anyway; call it the same
2608             // function.
2609             // FIXME: For C++, we should also merge methods here.
2610             return Importer.Imported(D, FoundDef);
2611           }
2612         } else if (!D->isCompleteDefinition()) {
2613           // We have a forward declaration of this type, so adopt that forward
2614           // declaration rather than building a new one.
2615 
2616           // If one or both can be completed from external storage then try one
2617           // last time to complete and compare them before doing this.
2618 
2619           if (FoundRecord->hasExternalLexicalStorage() &&
2620               !FoundRecord->isCompleteDefinition())
2621             FoundRecord->getASTContext().getExternalSource()->CompleteType(FoundRecord);
2622           if (D->hasExternalLexicalStorage())
2623             D->getASTContext().getExternalSource()->CompleteType(D);
2624 
2625           if (FoundRecord->isCompleteDefinition() &&
2626               D->isCompleteDefinition() &&
2627               !IsStructuralMatch(D, FoundRecord))
2628             continue;
2629 
2630           AdoptDecl = FoundRecord;
2631           continue;
2632         } else if (!SearchName) {
2633           continue;
2634         }
2635       }
2636 
2637       ConflictingDecls.push_back(FoundDecls[I]);
2638     }
2639 
2640     if (!ConflictingDecls.empty() && SearchName) {
2641       Name = Importer.HandleNameConflict(Name, DC, IDNS,
2642                                          ConflictingDecls.data(),
2643                                          ConflictingDecls.size());
2644     }
2645   }
2646 
2647   // Create the record declaration.
2648   RecordDecl *D2 = AdoptDecl;
2649   SourceLocation StartLoc = Importer.Import(D->getLocStart());
2650   if (!D2) {
2651     if (isa<CXXRecordDecl>(D)) {
2652       CXXRecordDecl *D2CXX = CXXRecordDecl::Create(Importer.getToContext(),
2653                                                    D->getTagKind(),
2654                                                    DC, StartLoc, Loc,
2655                                                    Name.getAsIdentifierInfo());
2656       D2 = D2CXX;
2657       D2->setAccess(D->getAccess());
2658     } else {
2659       D2 = RecordDecl::Create(Importer.getToContext(), D->getTagKind(),
2660                               DC, StartLoc, Loc, Name.getAsIdentifierInfo());
2661     }
2662 
2663     D2->setQualifierInfo(Importer.Import(D->getQualifierLoc()));
2664     D2->setLexicalDeclContext(LexicalDC);
2665     LexicalDC->addDeclInternal(D2);
2666     if (D->isAnonymousStructOrUnion())
2667       D2->setAnonymousStructOrUnion(true);
2668   }
2669 
2670   Importer.Imported(D, D2);
2671 
2672   if (D->isCompleteDefinition() && ImportDefinition(D, D2, IDK_Default))
2673     return nullptr;
2674 
2675   return D2;
2676 }
2677 
2678 Decl *ASTNodeImporter::VisitEnumConstantDecl(EnumConstantDecl *D) {
2679   // Import the major distinguishing characteristics of this enumerator.
2680   DeclContext *DC, *LexicalDC;
2681   DeclarationName Name;
2682   SourceLocation Loc;
2683   NamedDecl *ToD;
2684   if (ImportDeclParts(D, DC, LexicalDC, Name, ToD, Loc))
2685     return nullptr;
2686   if (ToD)
2687     return ToD;
2688 
2689   QualType T = Importer.Import(D->getType());
2690   if (T.isNull())
2691     return nullptr;
2692 
2693   // Determine whether there are any other declarations with the same name and
2694   // in the same context.
2695   if (!LexicalDC->isFunctionOrMethod()) {
2696     SmallVector<NamedDecl *, 4> ConflictingDecls;
2697     unsigned IDNS = Decl::IDNS_Ordinary;
2698     SmallVector<NamedDecl *, 2> FoundDecls;
2699     DC->getRedeclContext()->localUncachedLookup(Name, FoundDecls);
2700     for (unsigned I = 0, N = FoundDecls.size(); I != N; ++I) {
2701       if (!FoundDecls[I]->isInIdentifierNamespace(IDNS))
2702         continue;
2703 
2704       if (EnumConstantDecl *FoundEnumConstant
2705             = dyn_cast<EnumConstantDecl>(FoundDecls[I])) {
2706         if (IsStructuralMatch(D, FoundEnumConstant))
2707           return Importer.Imported(D, FoundEnumConstant);
2708       }
2709 
2710       ConflictingDecls.push_back(FoundDecls[I]);
2711     }
2712 
2713     if (!ConflictingDecls.empty()) {
2714       Name = Importer.HandleNameConflict(Name, DC, IDNS,
2715                                          ConflictingDecls.data(),
2716                                          ConflictingDecls.size());
2717       if (!Name)
2718         return nullptr;
2719     }
2720   }
2721 
2722   Expr *Init = Importer.Import(D->getInitExpr());
2723   if (D->getInitExpr() && !Init)
2724     return nullptr;
2725 
2726   EnumConstantDecl *ToEnumerator
2727     = EnumConstantDecl::Create(Importer.getToContext(), cast<EnumDecl>(DC), Loc,
2728                                Name.getAsIdentifierInfo(), T,
2729                                Init, D->getInitVal());
2730   ToEnumerator->setAccess(D->getAccess());
2731   ToEnumerator->setLexicalDeclContext(LexicalDC);
2732   Importer.Imported(D, ToEnumerator);
2733   LexicalDC->addDeclInternal(ToEnumerator);
2734   return ToEnumerator;
2735 }
2736 
2737 Decl *ASTNodeImporter::VisitFunctionDecl(FunctionDecl *D) {
2738   // Import the major distinguishing characteristics of this function.
2739   DeclContext *DC, *LexicalDC;
2740   DeclarationName Name;
2741   SourceLocation Loc;
2742   NamedDecl *ToD;
2743   if (ImportDeclParts(D, DC, LexicalDC, Name, ToD, Loc))
2744     return nullptr;
2745   if (ToD)
2746     return ToD;
2747 
2748   // Try to find a function in our own ("to") context with the same name, same
2749   // type, and in the same context as the function we're importing.
2750   if (!LexicalDC->isFunctionOrMethod()) {
2751     SmallVector<NamedDecl *, 4> ConflictingDecls;
2752     unsigned IDNS = Decl::IDNS_Ordinary;
2753     SmallVector<NamedDecl *, 2> FoundDecls;
2754     DC->getRedeclContext()->localUncachedLookup(Name, FoundDecls);
2755     for (unsigned I = 0, N = FoundDecls.size(); I != N; ++I) {
2756       if (!FoundDecls[I]->isInIdentifierNamespace(IDNS))
2757         continue;
2758 
2759       if (FunctionDecl *FoundFunction = dyn_cast<FunctionDecl>(FoundDecls[I])) {
2760         if (FoundFunction->hasExternalFormalLinkage() &&
2761             D->hasExternalFormalLinkage()) {
2762           if (Importer.IsStructurallyEquivalent(D->getType(),
2763                                                 FoundFunction->getType())) {
2764             // FIXME: Actually try to merge the body and other attributes.
2765             return Importer.Imported(D, FoundFunction);
2766           }
2767 
2768           // FIXME: Check for overloading more carefully, e.g., by boosting
2769           // Sema::IsOverload out to the AST library.
2770 
2771           // Function overloading is okay in C++.
2772           if (Importer.getToContext().getLangOpts().CPlusPlus)
2773             continue;
2774 
2775           // Complain about inconsistent function types.
2776           Importer.ToDiag(Loc, diag::err_odr_function_type_inconsistent)
2777             << Name << D->getType() << FoundFunction->getType();
2778           Importer.ToDiag(FoundFunction->getLocation(),
2779                           diag::note_odr_value_here)
2780             << FoundFunction->getType();
2781         }
2782       }
2783 
2784       ConflictingDecls.push_back(FoundDecls[I]);
2785     }
2786 
2787     if (!ConflictingDecls.empty()) {
2788       Name = Importer.HandleNameConflict(Name, DC, IDNS,
2789                                          ConflictingDecls.data(),
2790                                          ConflictingDecls.size());
2791       if (!Name)
2792         return nullptr;
2793     }
2794   }
2795 
2796   DeclarationNameInfo NameInfo(Name, Loc);
2797   // Import additional name location/type info.
2798   ImportDeclarationNameLoc(D->getNameInfo(), NameInfo);
2799 
2800   QualType FromTy = D->getType();
2801   bool usedDifferentExceptionSpec = false;
2802 
2803   if (const FunctionProtoType *
2804         FromFPT = D->getType()->getAs<FunctionProtoType>()) {
2805     FunctionProtoType::ExtProtoInfo FromEPI = FromFPT->getExtProtoInfo();
2806     // FunctionProtoType::ExtProtoInfo's ExceptionSpecDecl can point to the
2807     // FunctionDecl that we are importing the FunctionProtoType for.
2808     // To avoid an infinite recursion when importing, create the FunctionDecl
2809     // with a simplified function type and update it afterwards.
2810     if (FromEPI.ExceptionSpec.SourceDecl ||
2811         FromEPI.ExceptionSpec.SourceTemplate ||
2812         FromEPI.ExceptionSpec.NoexceptExpr) {
2813       FunctionProtoType::ExtProtoInfo DefaultEPI;
2814       FromTy = Importer.getFromContext().getFunctionType(
2815           FromFPT->getReturnType(), FromFPT->getParamTypes(), DefaultEPI);
2816       usedDifferentExceptionSpec = true;
2817     }
2818   }
2819 
2820   // Import the type.
2821   QualType T = Importer.Import(FromTy);
2822   if (T.isNull())
2823     return nullptr;
2824 
2825   // Import the function parameters.
2826   SmallVector<ParmVarDecl *, 8> Parameters;
2827   for (auto P : D->params()) {
2828     ParmVarDecl *ToP = cast_or_null<ParmVarDecl>(Importer.Import(P));
2829     if (!ToP)
2830       return nullptr;
2831 
2832     Parameters.push_back(ToP);
2833   }
2834 
2835   // Create the imported function.
2836   TypeSourceInfo *TInfo = Importer.Import(D->getTypeSourceInfo());
2837   FunctionDecl *ToFunction = nullptr;
2838   SourceLocation InnerLocStart = Importer.Import(D->getInnerLocStart());
2839   if (CXXConstructorDecl *FromConstructor = dyn_cast<CXXConstructorDecl>(D)) {
2840     ToFunction = CXXConstructorDecl::Create(Importer.getToContext(),
2841                                             cast<CXXRecordDecl>(DC),
2842                                             InnerLocStart,
2843                                             NameInfo, T, TInfo,
2844                                             FromConstructor->isExplicit(),
2845                                             D->isInlineSpecified(),
2846                                             D->isImplicit(),
2847                                             D->isConstexpr());
2848   } else if (isa<CXXDestructorDecl>(D)) {
2849     ToFunction = CXXDestructorDecl::Create(Importer.getToContext(),
2850                                            cast<CXXRecordDecl>(DC),
2851                                            InnerLocStart,
2852                                            NameInfo, T, TInfo,
2853                                            D->isInlineSpecified(),
2854                                            D->isImplicit());
2855   } else if (CXXConversionDecl *FromConversion
2856                                            = dyn_cast<CXXConversionDecl>(D)) {
2857     ToFunction = CXXConversionDecl::Create(Importer.getToContext(),
2858                                            cast<CXXRecordDecl>(DC),
2859                                            InnerLocStart,
2860                                            NameInfo, T, TInfo,
2861                                            D->isInlineSpecified(),
2862                                            FromConversion->isExplicit(),
2863                                            D->isConstexpr(),
2864                                            Importer.Import(D->getLocEnd()));
2865   } else if (CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(D)) {
2866     ToFunction = CXXMethodDecl::Create(Importer.getToContext(),
2867                                        cast<CXXRecordDecl>(DC),
2868                                        InnerLocStart,
2869                                        NameInfo, T, TInfo,
2870                                        Method->getStorageClass(),
2871                                        Method->isInlineSpecified(),
2872                                        D->isConstexpr(),
2873                                        Importer.Import(D->getLocEnd()));
2874   } else {
2875     ToFunction = FunctionDecl::Create(Importer.getToContext(), DC,
2876                                       InnerLocStart,
2877                                       NameInfo, T, TInfo, D->getStorageClass(),
2878                                       D->isInlineSpecified(),
2879                                       D->hasWrittenPrototype(),
2880                                       D->isConstexpr());
2881   }
2882 
2883   // Import the qualifier, if any.
2884   ToFunction->setQualifierInfo(Importer.Import(D->getQualifierLoc()));
2885   ToFunction->setAccess(D->getAccess());
2886   ToFunction->setLexicalDeclContext(LexicalDC);
2887   ToFunction->setVirtualAsWritten(D->isVirtualAsWritten());
2888   ToFunction->setTrivial(D->isTrivial());
2889   ToFunction->setPure(D->isPure());
2890   Importer.Imported(D, ToFunction);
2891 
2892   // Set the parameters.
2893   for (unsigned I = 0, N = Parameters.size(); I != N; ++I) {
2894     Parameters[I]->setOwningFunction(ToFunction);
2895     ToFunction->addDeclInternal(Parameters[I]);
2896   }
2897   ToFunction->setParams(Parameters);
2898 
2899   if (usedDifferentExceptionSpec) {
2900     // Update FunctionProtoType::ExtProtoInfo.
2901     QualType T = Importer.Import(D->getType());
2902     if (T.isNull())
2903       return nullptr;
2904     ToFunction->setType(T);
2905   }
2906 
2907   // Import the body, if any.
2908   if (Stmt *FromBody = D->getBody()) {
2909     if (Stmt *ToBody = Importer.Import(FromBody)) {
2910       ToFunction->setBody(ToBody);
2911     }
2912   }
2913 
2914   // FIXME: Other bits to merge?
2915 
2916   // Add this function to the lexical context.
2917   LexicalDC->addDeclInternal(ToFunction);
2918 
2919   return ToFunction;
2920 }
2921 
2922 Decl *ASTNodeImporter::VisitCXXMethodDecl(CXXMethodDecl *D) {
2923   return VisitFunctionDecl(D);
2924 }
2925 
2926 Decl *ASTNodeImporter::VisitCXXConstructorDecl(CXXConstructorDecl *D) {
2927   return VisitCXXMethodDecl(D);
2928 }
2929 
2930 Decl *ASTNodeImporter::VisitCXXDestructorDecl(CXXDestructorDecl *D) {
2931   return VisitCXXMethodDecl(D);
2932 }
2933 
2934 Decl *ASTNodeImporter::VisitCXXConversionDecl(CXXConversionDecl *D) {
2935   return VisitCXXMethodDecl(D);
2936 }
2937 
2938 static unsigned getFieldIndex(Decl *F) {
2939   RecordDecl *Owner = dyn_cast<RecordDecl>(F->getDeclContext());
2940   if (!Owner)
2941     return 0;
2942 
2943   unsigned Index = 1;
2944   for (const auto *D : Owner->noload_decls()) {
2945     if (D == F)
2946       return Index;
2947 
2948     if (isa<FieldDecl>(*D) || isa<IndirectFieldDecl>(*D))
2949       ++Index;
2950   }
2951 
2952   return Index;
2953 }
2954 
2955 Decl *ASTNodeImporter::VisitFieldDecl(FieldDecl *D) {
2956   // Import the major distinguishing characteristics of a variable.
2957   DeclContext *DC, *LexicalDC;
2958   DeclarationName Name;
2959   SourceLocation Loc;
2960   NamedDecl *ToD;
2961   if (ImportDeclParts(D, DC, LexicalDC, Name, ToD, Loc))
2962     return nullptr;
2963   if (ToD)
2964     return ToD;
2965 
2966   // Determine whether we've already imported this field.
2967   SmallVector<NamedDecl *, 2> FoundDecls;
2968   DC->getRedeclContext()->localUncachedLookup(Name, FoundDecls);
2969   for (unsigned I = 0, N = FoundDecls.size(); I != N; ++I) {
2970     if (FieldDecl *FoundField = dyn_cast<FieldDecl>(FoundDecls[I])) {
2971       // For anonymous fields, match up by index.
2972       if (!Name && getFieldIndex(D) != getFieldIndex(FoundField))
2973         continue;
2974 
2975       if (Importer.IsStructurallyEquivalent(D->getType(),
2976                                             FoundField->getType())) {
2977         Importer.Imported(D, FoundField);
2978         return FoundField;
2979       }
2980 
2981       Importer.ToDiag(Loc, diag::err_odr_field_type_inconsistent)
2982         << Name << D->getType() << FoundField->getType();
2983       Importer.ToDiag(FoundField->getLocation(), diag::note_odr_value_here)
2984         << FoundField->getType();
2985       return nullptr;
2986     }
2987   }
2988 
2989   // Import the type.
2990   QualType T = Importer.Import(D->getType());
2991   if (T.isNull())
2992     return nullptr;
2993 
2994   TypeSourceInfo *TInfo = Importer.Import(D->getTypeSourceInfo());
2995   Expr *BitWidth = Importer.Import(D->getBitWidth());
2996   if (!BitWidth && D->getBitWidth())
2997     return nullptr;
2998 
2999   FieldDecl *ToField = FieldDecl::Create(Importer.getToContext(), DC,
3000                                          Importer.Import(D->getInnerLocStart()),
3001                                          Loc, Name.getAsIdentifierInfo(),
3002                                          T, TInfo, BitWidth, D->isMutable(),
3003                                          D->getInClassInitStyle());
3004   ToField->setAccess(D->getAccess());
3005   ToField->setLexicalDeclContext(LexicalDC);
3006   if (ToField->hasInClassInitializer())
3007     ToField->setInClassInitializer(D->getInClassInitializer());
3008   ToField->setImplicit(D->isImplicit());
3009   Importer.Imported(D, ToField);
3010   LexicalDC->addDeclInternal(ToField);
3011   return ToField;
3012 }
3013 
3014 Decl *ASTNodeImporter::VisitIndirectFieldDecl(IndirectFieldDecl *D) {
3015   // Import the major distinguishing characteristics of a variable.
3016   DeclContext *DC, *LexicalDC;
3017   DeclarationName Name;
3018   SourceLocation Loc;
3019   NamedDecl *ToD;
3020   if (ImportDeclParts(D, DC, LexicalDC, Name, ToD, Loc))
3021     return nullptr;
3022   if (ToD)
3023     return ToD;
3024 
3025   // Determine whether we've already imported this field.
3026   SmallVector<NamedDecl *, 2> FoundDecls;
3027   DC->getRedeclContext()->localUncachedLookup(Name, FoundDecls);
3028   for (unsigned I = 0, N = FoundDecls.size(); I != N; ++I) {
3029     if (IndirectFieldDecl *FoundField
3030                                 = dyn_cast<IndirectFieldDecl>(FoundDecls[I])) {
3031       // For anonymous indirect fields, match up by index.
3032       if (!Name && getFieldIndex(D) != getFieldIndex(FoundField))
3033         continue;
3034 
3035       if (Importer.IsStructurallyEquivalent(D->getType(),
3036                                             FoundField->getType(),
3037                                             !Name.isEmpty())) {
3038         Importer.Imported(D, FoundField);
3039         return FoundField;
3040       }
3041 
3042       // If there are more anonymous fields to check, continue.
3043       if (!Name && I < N-1)
3044         continue;
3045 
3046       Importer.ToDiag(Loc, diag::err_odr_field_type_inconsistent)
3047         << Name << D->getType() << FoundField->getType();
3048       Importer.ToDiag(FoundField->getLocation(), diag::note_odr_value_here)
3049         << FoundField->getType();
3050       return nullptr;
3051     }
3052   }
3053 
3054   // Import the type.
3055   QualType T = Importer.Import(D->getType());
3056   if (T.isNull())
3057     return nullptr;
3058 
3059   NamedDecl **NamedChain =
3060     new (Importer.getToContext())NamedDecl*[D->getChainingSize()];
3061 
3062   unsigned i = 0;
3063   for (auto *PI : D->chain()) {
3064     Decl *D = Importer.Import(PI);
3065     if (!D)
3066       return nullptr;
3067     NamedChain[i++] = cast<NamedDecl>(D);
3068   }
3069 
3070   IndirectFieldDecl *ToIndirectField = IndirectFieldDecl::Create(
3071       Importer.getToContext(), DC, Loc, Name.getAsIdentifierInfo(), T,
3072       NamedChain, D->getChainingSize());
3073 
3074   for (const auto *Attr : D->attrs())
3075     ToIndirectField->addAttr(Attr->clone(Importer.getToContext()));
3076 
3077   ToIndirectField->setAccess(D->getAccess());
3078   ToIndirectField->setLexicalDeclContext(LexicalDC);
3079   Importer.Imported(D, ToIndirectField);
3080   LexicalDC->addDeclInternal(ToIndirectField);
3081   return ToIndirectField;
3082 }
3083 
3084 Decl *ASTNodeImporter::VisitObjCIvarDecl(ObjCIvarDecl *D) {
3085   // Import the major distinguishing characteristics of an ivar.
3086   DeclContext *DC, *LexicalDC;
3087   DeclarationName Name;
3088   SourceLocation Loc;
3089   NamedDecl *ToD;
3090   if (ImportDeclParts(D, DC, LexicalDC, Name, ToD, Loc))
3091     return nullptr;
3092   if (ToD)
3093     return ToD;
3094 
3095   // Determine whether we've already imported this ivar
3096   SmallVector<NamedDecl *, 2> FoundDecls;
3097   DC->getRedeclContext()->localUncachedLookup(Name, FoundDecls);
3098   for (unsigned I = 0, N = FoundDecls.size(); I != N; ++I) {
3099     if (ObjCIvarDecl *FoundIvar = dyn_cast<ObjCIvarDecl>(FoundDecls[I])) {
3100       if (Importer.IsStructurallyEquivalent(D->getType(),
3101                                             FoundIvar->getType())) {
3102         Importer.Imported(D, FoundIvar);
3103         return FoundIvar;
3104       }
3105 
3106       Importer.ToDiag(Loc, diag::err_odr_ivar_type_inconsistent)
3107         << Name << D->getType() << FoundIvar->getType();
3108       Importer.ToDiag(FoundIvar->getLocation(), diag::note_odr_value_here)
3109         << FoundIvar->getType();
3110       return nullptr;
3111     }
3112   }
3113 
3114   // Import the type.
3115   QualType T = Importer.Import(D->getType());
3116   if (T.isNull())
3117     return nullptr;
3118 
3119   TypeSourceInfo *TInfo = Importer.Import(D->getTypeSourceInfo());
3120   Expr *BitWidth = Importer.Import(D->getBitWidth());
3121   if (!BitWidth && D->getBitWidth())
3122     return nullptr;
3123 
3124   ObjCIvarDecl *ToIvar = ObjCIvarDecl::Create(Importer.getToContext(),
3125                                               cast<ObjCContainerDecl>(DC),
3126                                        Importer.Import(D->getInnerLocStart()),
3127                                               Loc, Name.getAsIdentifierInfo(),
3128                                               T, TInfo, D->getAccessControl(),
3129                                               BitWidth, D->getSynthesize());
3130   ToIvar->setLexicalDeclContext(LexicalDC);
3131   Importer.Imported(D, ToIvar);
3132   LexicalDC->addDeclInternal(ToIvar);
3133   return ToIvar;
3134 
3135 }
3136 
3137 Decl *ASTNodeImporter::VisitVarDecl(VarDecl *D) {
3138   // Import the major distinguishing characteristics of a variable.
3139   DeclContext *DC, *LexicalDC;
3140   DeclarationName Name;
3141   SourceLocation Loc;
3142   NamedDecl *ToD;
3143   if (ImportDeclParts(D, DC, LexicalDC, Name, ToD, Loc))
3144     return nullptr;
3145   if (ToD)
3146     return ToD;
3147 
3148   // Try to find a variable in our own ("to") context with the same name and
3149   // in the same context as the variable we're importing.
3150   if (D->isFileVarDecl()) {
3151     VarDecl *MergeWithVar = nullptr;
3152     SmallVector<NamedDecl *, 4> ConflictingDecls;
3153     unsigned IDNS = Decl::IDNS_Ordinary;
3154     SmallVector<NamedDecl *, 2> FoundDecls;
3155     DC->getRedeclContext()->localUncachedLookup(Name, FoundDecls);
3156     for (unsigned I = 0, N = FoundDecls.size(); I != N; ++I) {
3157       if (!FoundDecls[I]->isInIdentifierNamespace(IDNS))
3158         continue;
3159 
3160       if (VarDecl *FoundVar = dyn_cast<VarDecl>(FoundDecls[I])) {
3161         // We have found a variable that we may need to merge with. Check it.
3162         if (FoundVar->hasExternalFormalLinkage() &&
3163             D->hasExternalFormalLinkage()) {
3164           if (Importer.IsStructurallyEquivalent(D->getType(),
3165                                                 FoundVar->getType())) {
3166             MergeWithVar = FoundVar;
3167             break;
3168           }
3169 
3170           const ArrayType *FoundArray
3171             = Importer.getToContext().getAsArrayType(FoundVar->getType());
3172           const ArrayType *TArray
3173             = Importer.getToContext().getAsArrayType(D->getType());
3174           if (FoundArray && TArray) {
3175             if (isa<IncompleteArrayType>(FoundArray) &&
3176                 isa<ConstantArrayType>(TArray)) {
3177               // Import the type.
3178               QualType T = Importer.Import(D->getType());
3179               if (T.isNull())
3180                 return nullptr;
3181 
3182               FoundVar->setType(T);
3183               MergeWithVar = FoundVar;
3184               break;
3185             } else if (isa<IncompleteArrayType>(TArray) &&
3186                        isa<ConstantArrayType>(FoundArray)) {
3187               MergeWithVar = FoundVar;
3188               break;
3189             }
3190           }
3191 
3192           Importer.ToDiag(Loc, diag::err_odr_variable_type_inconsistent)
3193             << Name << D->getType() << FoundVar->getType();
3194           Importer.ToDiag(FoundVar->getLocation(), diag::note_odr_value_here)
3195             << FoundVar->getType();
3196         }
3197       }
3198 
3199       ConflictingDecls.push_back(FoundDecls[I]);
3200     }
3201 
3202     if (MergeWithVar) {
3203       // An equivalent variable with external linkage has been found. Link
3204       // the two declarations, then merge them.
3205       Importer.Imported(D, MergeWithVar);
3206 
3207       if (VarDecl *DDef = D->getDefinition()) {
3208         if (VarDecl *ExistingDef = MergeWithVar->getDefinition()) {
3209           Importer.ToDiag(ExistingDef->getLocation(),
3210                           diag::err_odr_variable_multiple_def)
3211             << Name;
3212           Importer.FromDiag(DDef->getLocation(), diag::note_odr_defined_here);
3213         } else {
3214           Expr *Init = Importer.Import(DDef->getInit());
3215           MergeWithVar->setInit(Init);
3216           if (DDef->isInitKnownICE()) {
3217             EvaluatedStmt *Eval = MergeWithVar->ensureEvaluatedStmt();
3218             Eval->CheckedICE = true;
3219             Eval->IsICE = DDef->isInitICE();
3220           }
3221         }
3222       }
3223 
3224       return MergeWithVar;
3225     }
3226 
3227     if (!ConflictingDecls.empty()) {
3228       Name = Importer.HandleNameConflict(Name, DC, IDNS,
3229                                          ConflictingDecls.data(),
3230                                          ConflictingDecls.size());
3231       if (!Name)
3232         return nullptr;
3233     }
3234   }
3235 
3236   // Import the type.
3237   QualType T = Importer.Import(D->getType());
3238   if (T.isNull())
3239     return nullptr;
3240 
3241   // Create the imported variable.
3242   TypeSourceInfo *TInfo = Importer.Import(D->getTypeSourceInfo());
3243   VarDecl *ToVar = VarDecl::Create(Importer.getToContext(), DC,
3244                                    Importer.Import(D->getInnerLocStart()),
3245                                    Loc, Name.getAsIdentifierInfo(),
3246                                    T, TInfo,
3247                                    D->getStorageClass());
3248   ToVar->setQualifierInfo(Importer.Import(D->getQualifierLoc()));
3249   ToVar->setAccess(D->getAccess());
3250   ToVar->setLexicalDeclContext(LexicalDC);
3251   Importer.Imported(D, ToVar);
3252   LexicalDC->addDeclInternal(ToVar);
3253 
3254   if (!D->isFileVarDecl() &&
3255       D->isUsed())
3256     ToVar->setIsUsed();
3257 
3258   // Merge the initializer.
3259   if (ImportDefinition(D, ToVar))
3260     return nullptr;
3261 
3262   return ToVar;
3263 }
3264 
3265 Decl *ASTNodeImporter::VisitImplicitParamDecl(ImplicitParamDecl *D) {
3266   // Parameters are created in the translation unit's context, then moved
3267   // into the function declaration's context afterward.
3268   DeclContext *DC = Importer.getToContext().getTranslationUnitDecl();
3269 
3270   // Import the name of this declaration.
3271   DeclarationName Name = Importer.Import(D->getDeclName());
3272   if (D->getDeclName() && !Name)
3273     return nullptr;
3274 
3275   // Import the location of this declaration.
3276   SourceLocation Loc = Importer.Import(D->getLocation());
3277 
3278   // Import the parameter's type.
3279   QualType T = Importer.Import(D->getType());
3280   if (T.isNull())
3281     return nullptr;
3282 
3283   // Create the imported parameter.
3284   ImplicitParamDecl *ToParm
3285     = ImplicitParamDecl::Create(Importer.getToContext(), DC,
3286                                 Loc, Name.getAsIdentifierInfo(),
3287                                 T);
3288   return Importer.Imported(D, ToParm);
3289 }
3290 
3291 Decl *ASTNodeImporter::VisitParmVarDecl(ParmVarDecl *D) {
3292   // Parameters are created in the translation unit's context, then moved
3293   // into the function declaration's context afterward.
3294   DeclContext *DC = Importer.getToContext().getTranslationUnitDecl();
3295 
3296   // Import the name of this declaration.
3297   DeclarationName Name = Importer.Import(D->getDeclName());
3298   if (D->getDeclName() && !Name)
3299     return nullptr;
3300 
3301   // Import the location of this declaration.
3302   SourceLocation Loc = Importer.Import(D->getLocation());
3303 
3304   // Import the parameter's type.
3305   QualType T = Importer.Import(D->getType());
3306   if (T.isNull())
3307     return nullptr;
3308 
3309   // Create the imported parameter.
3310   TypeSourceInfo *TInfo = Importer.Import(D->getTypeSourceInfo());
3311   ParmVarDecl *ToParm = ParmVarDecl::Create(Importer.getToContext(), DC,
3312                                      Importer.Import(D->getInnerLocStart()),
3313                                             Loc, Name.getAsIdentifierInfo(),
3314                                             T, TInfo, D->getStorageClass(),
3315                                             /*FIXME: Default argument*/nullptr);
3316   ToParm->setHasInheritedDefaultArg(D->hasInheritedDefaultArg());
3317 
3318   if (D->isUsed())
3319     ToParm->setIsUsed();
3320 
3321   return Importer.Imported(D, ToParm);
3322 }
3323 
3324 Decl *ASTNodeImporter::VisitObjCMethodDecl(ObjCMethodDecl *D) {
3325   // Import the major distinguishing characteristics of a method.
3326   DeclContext *DC, *LexicalDC;
3327   DeclarationName Name;
3328   SourceLocation Loc;
3329   NamedDecl *ToD;
3330   if (ImportDeclParts(D, DC, LexicalDC, Name, ToD, Loc))
3331     return nullptr;
3332   if (ToD)
3333     return ToD;
3334 
3335   SmallVector<NamedDecl *, 2> FoundDecls;
3336   DC->getRedeclContext()->localUncachedLookup(Name, FoundDecls);
3337   for (unsigned I = 0, N = FoundDecls.size(); I != N; ++I) {
3338     if (ObjCMethodDecl *FoundMethod = dyn_cast<ObjCMethodDecl>(FoundDecls[I])) {
3339       if (FoundMethod->isInstanceMethod() != D->isInstanceMethod())
3340         continue;
3341 
3342       // Check return types.
3343       if (!Importer.IsStructurallyEquivalent(D->getReturnType(),
3344                                              FoundMethod->getReturnType())) {
3345         Importer.ToDiag(Loc, diag::err_odr_objc_method_result_type_inconsistent)
3346             << D->isInstanceMethod() << Name << D->getReturnType()
3347             << FoundMethod->getReturnType();
3348         Importer.ToDiag(FoundMethod->getLocation(),
3349                         diag::note_odr_objc_method_here)
3350           << D->isInstanceMethod() << Name;
3351         return nullptr;
3352       }
3353 
3354       // Check the number of parameters.
3355       if (D->param_size() != FoundMethod->param_size()) {
3356         Importer.ToDiag(Loc, diag::err_odr_objc_method_num_params_inconsistent)
3357           << D->isInstanceMethod() << Name
3358           << D->param_size() << FoundMethod->param_size();
3359         Importer.ToDiag(FoundMethod->getLocation(),
3360                         diag::note_odr_objc_method_here)
3361           << D->isInstanceMethod() << Name;
3362         return nullptr;
3363       }
3364 
3365       // Check parameter types.
3366       for (ObjCMethodDecl::param_iterator P = D->param_begin(),
3367              PEnd = D->param_end(), FoundP = FoundMethod->param_begin();
3368            P != PEnd; ++P, ++FoundP) {
3369         if (!Importer.IsStructurallyEquivalent((*P)->getType(),
3370                                                (*FoundP)->getType())) {
3371           Importer.FromDiag((*P)->getLocation(),
3372                             diag::err_odr_objc_method_param_type_inconsistent)
3373             << D->isInstanceMethod() << Name
3374             << (*P)->getType() << (*FoundP)->getType();
3375           Importer.ToDiag((*FoundP)->getLocation(), diag::note_odr_value_here)
3376             << (*FoundP)->getType();
3377           return nullptr;
3378         }
3379       }
3380 
3381       // Check variadic/non-variadic.
3382       // Check the number of parameters.
3383       if (D->isVariadic() != FoundMethod->isVariadic()) {
3384         Importer.ToDiag(Loc, diag::err_odr_objc_method_variadic_inconsistent)
3385           << D->isInstanceMethod() << Name;
3386         Importer.ToDiag(FoundMethod->getLocation(),
3387                         diag::note_odr_objc_method_here)
3388           << D->isInstanceMethod() << Name;
3389         return nullptr;
3390       }
3391 
3392       // FIXME: Any other bits we need to merge?
3393       return Importer.Imported(D, FoundMethod);
3394     }
3395   }
3396 
3397   // Import the result type.
3398   QualType ResultTy = Importer.Import(D->getReturnType());
3399   if (ResultTy.isNull())
3400     return nullptr;
3401 
3402   TypeSourceInfo *ReturnTInfo = Importer.Import(D->getReturnTypeSourceInfo());
3403 
3404   ObjCMethodDecl *ToMethod = ObjCMethodDecl::Create(
3405       Importer.getToContext(), Loc, Importer.Import(D->getLocEnd()),
3406       Name.getObjCSelector(), ResultTy, ReturnTInfo, DC, D->isInstanceMethod(),
3407       D->isVariadic(), D->isPropertyAccessor(), D->isImplicit(), D->isDefined(),
3408       D->getImplementationControl(), D->hasRelatedResultType());
3409 
3410   // FIXME: When we decide to merge method definitions, we'll need to
3411   // deal with implicit parameters.
3412 
3413   // Import the parameters
3414   SmallVector<ParmVarDecl *, 5> ToParams;
3415   for (auto *FromP : D->params()) {
3416     ParmVarDecl *ToP = cast_or_null<ParmVarDecl>(Importer.Import(FromP));
3417     if (!ToP)
3418       return nullptr;
3419 
3420     ToParams.push_back(ToP);
3421   }
3422 
3423   // Set the parameters.
3424   for (unsigned I = 0, N = ToParams.size(); I != N; ++I) {
3425     ToParams[I]->setOwningFunction(ToMethod);
3426     ToMethod->addDeclInternal(ToParams[I]);
3427   }
3428   SmallVector<SourceLocation, 12> SelLocs;
3429   D->getSelectorLocs(SelLocs);
3430   ToMethod->setMethodParams(Importer.getToContext(), ToParams, SelLocs);
3431 
3432   ToMethod->setLexicalDeclContext(LexicalDC);
3433   Importer.Imported(D, ToMethod);
3434   LexicalDC->addDeclInternal(ToMethod);
3435   return ToMethod;
3436 }
3437 
3438 Decl *ASTNodeImporter::VisitObjCTypeParamDecl(ObjCTypeParamDecl *D) {
3439   // Import the major distinguishing characteristics of a category.
3440   DeclContext *DC, *LexicalDC;
3441   DeclarationName Name;
3442   SourceLocation Loc;
3443   NamedDecl *ToD;
3444   if (ImportDeclParts(D, DC, LexicalDC, Name, ToD, Loc))
3445     return nullptr;
3446   if (ToD)
3447     return ToD;
3448 
3449   TypeSourceInfo *BoundInfo = Importer.Import(D->getTypeSourceInfo());
3450   if (!BoundInfo)
3451     return nullptr;
3452 
3453   ObjCTypeParamDecl *Result = ObjCTypeParamDecl::Create(
3454                                 Importer.getToContext(), DC,
3455                                 D->getVariance(),
3456                                 Importer.Import(D->getVarianceLoc()),
3457                                 D->getIndex(),
3458                                 Importer.Import(D->getLocation()),
3459                                 Name.getAsIdentifierInfo(),
3460                                 Importer.Import(D->getColonLoc()),
3461                                 BoundInfo);
3462   Importer.Imported(D, Result);
3463   Result->setLexicalDeclContext(LexicalDC);
3464   return Result;
3465 }
3466 
3467 Decl *ASTNodeImporter::VisitObjCCategoryDecl(ObjCCategoryDecl *D) {
3468   // Import the major distinguishing characteristics of a category.
3469   DeclContext *DC, *LexicalDC;
3470   DeclarationName Name;
3471   SourceLocation Loc;
3472   NamedDecl *ToD;
3473   if (ImportDeclParts(D, DC, LexicalDC, Name, ToD, Loc))
3474     return nullptr;
3475   if (ToD)
3476     return ToD;
3477 
3478   ObjCInterfaceDecl *ToInterface
3479     = cast_or_null<ObjCInterfaceDecl>(Importer.Import(D->getClassInterface()));
3480   if (!ToInterface)
3481     return nullptr;
3482 
3483   // Determine if we've already encountered this category.
3484   ObjCCategoryDecl *MergeWithCategory
3485     = ToInterface->FindCategoryDeclaration(Name.getAsIdentifierInfo());
3486   ObjCCategoryDecl *ToCategory = MergeWithCategory;
3487   if (!ToCategory) {
3488     ToCategory = ObjCCategoryDecl::Create(Importer.getToContext(), DC,
3489                                           Importer.Import(D->getAtStartLoc()),
3490                                           Loc,
3491                                        Importer.Import(D->getCategoryNameLoc()),
3492                                           Name.getAsIdentifierInfo(),
3493                                           ToInterface,
3494                                           /*TypeParamList=*/nullptr,
3495                                        Importer.Import(D->getIvarLBraceLoc()),
3496                                        Importer.Import(D->getIvarRBraceLoc()));
3497     ToCategory->setLexicalDeclContext(LexicalDC);
3498     LexicalDC->addDeclInternal(ToCategory);
3499     Importer.Imported(D, ToCategory);
3500     // Import the type parameter list after calling Imported, to avoid
3501     // loops when bringing in their DeclContext.
3502     ToCategory->setTypeParamList(ImportObjCTypeParamList(
3503                                    D->getTypeParamList()));
3504 
3505     // Import protocols
3506     SmallVector<ObjCProtocolDecl *, 4> Protocols;
3507     SmallVector<SourceLocation, 4> ProtocolLocs;
3508     ObjCCategoryDecl::protocol_loc_iterator FromProtoLoc
3509       = D->protocol_loc_begin();
3510     for (ObjCCategoryDecl::protocol_iterator FromProto = D->protocol_begin(),
3511                                           FromProtoEnd = D->protocol_end();
3512          FromProto != FromProtoEnd;
3513          ++FromProto, ++FromProtoLoc) {
3514       ObjCProtocolDecl *ToProto
3515         = cast_or_null<ObjCProtocolDecl>(Importer.Import(*FromProto));
3516       if (!ToProto)
3517         return nullptr;
3518       Protocols.push_back(ToProto);
3519       ProtocolLocs.push_back(Importer.Import(*FromProtoLoc));
3520     }
3521 
3522     // FIXME: If we're merging, make sure that the protocol list is the same.
3523     ToCategory->setProtocolList(Protocols.data(), Protocols.size(),
3524                                 ProtocolLocs.data(), Importer.getToContext());
3525 
3526   } else {
3527     Importer.Imported(D, ToCategory);
3528   }
3529 
3530   // Import all of the members of this category.
3531   ImportDeclContext(D);
3532 
3533   // If we have an implementation, import it as well.
3534   if (D->getImplementation()) {
3535     ObjCCategoryImplDecl *Impl
3536       = cast_or_null<ObjCCategoryImplDecl>(
3537                                        Importer.Import(D->getImplementation()));
3538     if (!Impl)
3539       return nullptr;
3540 
3541     ToCategory->setImplementation(Impl);
3542   }
3543 
3544   return ToCategory;
3545 }
3546 
3547 bool ASTNodeImporter::ImportDefinition(ObjCProtocolDecl *From,
3548                                        ObjCProtocolDecl *To,
3549                                        ImportDefinitionKind Kind) {
3550   if (To->getDefinition()) {
3551     if (shouldForceImportDeclContext(Kind))
3552       ImportDeclContext(From);
3553     return false;
3554   }
3555 
3556   // Start the protocol definition
3557   To->startDefinition();
3558 
3559   // Import protocols
3560   SmallVector<ObjCProtocolDecl *, 4> Protocols;
3561   SmallVector<SourceLocation, 4> ProtocolLocs;
3562   ObjCProtocolDecl::protocol_loc_iterator
3563   FromProtoLoc = From->protocol_loc_begin();
3564   for (ObjCProtocolDecl::protocol_iterator FromProto = From->protocol_begin(),
3565                                         FromProtoEnd = From->protocol_end();
3566        FromProto != FromProtoEnd;
3567        ++FromProto, ++FromProtoLoc) {
3568     ObjCProtocolDecl *ToProto
3569       = cast_or_null<ObjCProtocolDecl>(Importer.Import(*FromProto));
3570     if (!ToProto)
3571       return true;
3572     Protocols.push_back(ToProto);
3573     ProtocolLocs.push_back(Importer.Import(*FromProtoLoc));
3574   }
3575 
3576   // FIXME: If we're merging, make sure that the protocol list is the same.
3577   To->setProtocolList(Protocols.data(), Protocols.size(),
3578                       ProtocolLocs.data(), Importer.getToContext());
3579 
3580   if (shouldForceImportDeclContext(Kind)) {
3581     // Import all of the members of this protocol.
3582     ImportDeclContext(From, /*ForceImport=*/true);
3583   }
3584   return false;
3585 }
3586 
3587 Decl *ASTNodeImporter::VisitObjCProtocolDecl(ObjCProtocolDecl *D) {
3588   // If this protocol has a definition in the translation unit we're coming
3589   // from, but this particular declaration is not that definition, import the
3590   // definition and map to that.
3591   ObjCProtocolDecl *Definition = D->getDefinition();
3592   if (Definition && Definition != D) {
3593     Decl *ImportedDef = Importer.Import(Definition);
3594     if (!ImportedDef)
3595       return nullptr;
3596 
3597     return Importer.Imported(D, ImportedDef);
3598   }
3599 
3600   // Import the major distinguishing characteristics of a protocol.
3601   DeclContext *DC, *LexicalDC;
3602   DeclarationName Name;
3603   SourceLocation Loc;
3604   NamedDecl *ToD;
3605   if (ImportDeclParts(D, DC, LexicalDC, Name, ToD, Loc))
3606     return nullptr;
3607   if (ToD)
3608     return ToD;
3609 
3610   ObjCProtocolDecl *MergeWithProtocol = nullptr;
3611   SmallVector<NamedDecl *, 2> FoundDecls;
3612   DC->getRedeclContext()->localUncachedLookup(Name, FoundDecls);
3613   for (unsigned I = 0, N = FoundDecls.size(); I != N; ++I) {
3614     if (!FoundDecls[I]->isInIdentifierNamespace(Decl::IDNS_ObjCProtocol))
3615       continue;
3616 
3617     if ((MergeWithProtocol = dyn_cast<ObjCProtocolDecl>(FoundDecls[I])))
3618       break;
3619   }
3620 
3621   ObjCProtocolDecl *ToProto = MergeWithProtocol;
3622   if (!ToProto) {
3623     ToProto = ObjCProtocolDecl::Create(Importer.getToContext(), DC,
3624                                        Name.getAsIdentifierInfo(), Loc,
3625                                        Importer.Import(D->getAtStartLoc()),
3626                                        /*PrevDecl=*/nullptr);
3627     ToProto->setLexicalDeclContext(LexicalDC);
3628     LexicalDC->addDeclInternal(ToProto);
3629   }
3630 
3631   Importer.Imported(D, ToProto);
3632 
3633   if (D->isThisDeclarationADefinition() && ImportDefinition(D, ToProto))
3634     return nullptr;
3635 
3636   return ToProto;
3637 }
3638 
3639 Decl *ASTNodeImporter::VisitLinkageSpecDecl(LinkageSpecDecl *D) {
3640   DeclContext *DC = Importer.ImportContext(D->getDeclContext());
3641   DeclContext *LexicalDC = Importer.ImportContext(D->getLexicalDeclContext());
3642 
3643   SourceLocation ExternLoc = Importer.Import(D->getExternLoc());
3644   SourceLocation LangLoc = Importer.Import(D->getLocation());
3645 
3646   bool HasBraces = D->hasBraces();
3647 
3648   LinkageSpecDecl *ToLinkageSpec =
3649     LinkageSpecDecl::Create(Importer.getToContext(),
3650                             DC,
3651                             ExternLoc,
3652                             LangLoc,
3653                             D->getLanguage(),
3654                             HasBraces);
3655 
3656   if (HasBraces) {
3657     SourceLocation RBraceLoc = Importer.Import(D->getRBraceLoc());
3658     ToLinkageSpec->setRBraceLoc(RBraceLoc);
3659   }
3660 
3661   ToLinkageSpec->setLexicalDeclContext(LexicalDC);
3662   LexicalDC->addDeclInternal(ToLinkageSpec);
3663 
3664   Importer.Imported(D, ToLinkageSpec);
3665 
3666   return ToLinkageSpec;
3667 }
3668 
3669 bool ASTNodeImporter::ImportDefinition(ObjCInterfaceDecl *From,
3670                                        ObjCInterfaceDecl *To,
3671                                        ImportDefinitionKind Kind) {
3672   if (To->getDefinition()) {
3673     // Check consistency of superclass.
3674     ObjCInterfaceDecl *FromSuper = From->getSuperClass();
3675     if (FromSuper) {
3676       FromSuper = cast_or_null<ObjCInterfaceDecl>(Importer.Import(FromSuper));
3677       if (!FromSuper)
3678         return true;
3679     }
3680 
3681     ObjCInterfaceDecl *ToSuper = To->getSuperClass();
3682     if ((bool)FromSuper != (bool)ToSuper ||
3683         (FromSuper && !declaresSameEntity(FromSuper, ToSuper))) {
3684       Importer.ToDiag(To->getLocation(),
3685                       diag::err_odr_objc_superclass_inconsistent)
3686         << To->getDeclName();
3687       if (ToSuper)
3688         Importer.ToDiag(To->getSuperClassLoc(), diag::note_odr_objc_superclass)
3689           << To->getSuperClass()->getDeclName();
3690       else
3691         Importer.ToDiag(To->getLocation(),
3692                         diag::note_odr_objc_missing_superclass);
3693       if (From->getSuperClass())
3694         Importer.FromDiag(From->getSuperClassLoc(),
3695                           diag::note_odr_objc_superclass)
3696         << From->getSuperClass()->getDeclName();
3697       else
3698         Importer.FromDiag(From->getLocation(),
3699                           diag::note_odr_objc_missing_superclass);
3700     }
3701 
3702     if (shouldForceImportDeclContext(Kind))
3703       ImportDeclContext(From);
3704     return false;
3705   }
3706 
3707   // Start the definition.
3708   To->startDefinition();
3709 
3710   // If this class has a superclass, import it.
3711   if (From->getSuperClass()) {
3712     TypeSourceInfo *SuperTInfo = Importer.Import(From->getSuperClassTInfo());
3713     if (!SuperTInfo)
3714       return true;
3715 
3716     To->setSuperClass(SuperTInfo);
3717   }
3718 
3719   // Import protocols
3720   SmallVector<ObjCProtocolDecl *, 4> Protocols;
3721   SmallVector<SourceLocation, 4> ProtocolLocs;
3722   ObjCInterfaceDecl::protocol_loc_iterator
3723   FromProtoLoc = From->protocol_loc_begin();
3724 
3725   for (ObjCInterfaceDecl::protocol_iterator FromProto = From->protocol_begin(),
3726                                          FromProtoEnd = From->protocol_end();
3727        FromProto != FromProtoEnd;
3728        ++FromProto, ++FromProtoLoc) {
3729     ObjCProtocolDecl *ToProto
3730       = cast_or_null<ObjCProtocolDecl>(Importer.Import(*FromProto));
3731     if (!ToProto)
3732       return true;
3733     Protocols.push_back(ToProto);
3734     ProtocolLocs.push_back(Importer.Import(*FromProtoLoc));
3735   }
3736 
3737   // FIXME: If we're merging, make sure that the protocol list is the same.
3738   To->setProtocolList(Protocols.data(), Protocols.size(),
3739                       ProtocolLocs.data(), Importer.getToContext());
3740 
3741   // Import categories. When the categories themselves are imported, they'll
3742   // hook themselves into this interface.
3743   for (auto *Cat : From->known_categories())
3744     Importer.Import(Cat);
3745 
3746   // If we have an @implementation, import it as well.
3747   if (From->getImplementation()) {
3748     ObjCImplementationDecl *Impl = cast_or_null<ObjCImplementationDecl>(
3749                                      Importer.Import(From->getImplementation()));
3750     if (!Impl)
3751       return true;
3752 
3753     To->setImplementation(Impl);
3754   }
3755 
3756   if (shouldForceImportDeclContext(Kind)) {
3757     // Import all of the members of this class.
3758     ImportDeclContext(From, /*ForceImport=*/true);
3759   }
3760   return false;
3761 }
3762 
3763 ObjCTypeParamList *
3764 ASTNodeImporter::ImportObjCTypeParamList(ObjCTypeParamList *list) {
3765   if (!list)
3766     return nullptr;
3767 
3768   SmallVector<ObjCTypeParamDecl *, 4> toTypeParams;
3769   for (auto fromTypeParam : *list) {
3770     auto toTypeParam = cast_or_null<ObjCTypeParamDecl>(
3771                          Importer.Import(fromTypeParam));
3772     if (!toTypeParam)
3773       return nullptr;
3774 
3775     toTypeParams.push_back(toTypeParam);
3776   }
3777 
3778   return ObjCTypeParamList::create(Importer.getToContext(),
3779                                    Importer.Import(list->getLAngleLoc()),
3780                                    toTypeParams,
3781                                    Importer.Import(list->getRAngleLoc()));
3782 }
3783 
3784 Decl *ASTNodeImporter::VisitObjCInterfaceDecl(ObjCInterfaceDecl *D) {
3785   // If this class has a definition in the translation unit we're coming from,
3786   // but this particular declaration is not that definition, import the
3787   // definition and map to that.
3788   ObjCInterfaceDecl *Definition = D->getDefinition();
3789   if (Definition && Definition != D) {
3790     Decl *ImportedDef = Importer.Import(Definition);
3791     if (!ImportedDef)
3792       return nullptr;
3793 
3794     return Importer.Imported(D, ImportedDef);
3795   }
3796 
3797   // Import the major distinguishing characteristics of an @interface.
3798   DeclContext *DC, *LexicalDC;
3799   DeclarationName Name;
3800   SourceLocation Loc;
3801   NamedDecl *ToD;
3802   if (ImportDeclParts(D, DC, LexicalDC, Name, ToD, Loc))
3803     return nullptr;
3804   if (ToD)
3805     return ToD;
3806 
3807   // Look for an existing interface with the same name.
3808   ObjCInterfaceDecl *MergeWithIface = nullptr;
3809   SmallVector<NamedDecl *, 2> FoundDecls;
3810   DC->getRedeclContext()->localUncachedLookup(Name, FoundDecls);
3811   for (unsigned I = 0, N = FoundDecls.size(); I != N; ++I) {
3812     if (!FoundDecls[I]->isInIdentifierNamespace(Decl::IDNS_Ordinary))
3813       continue;
3814 
3815     if ((MergeWithIface = dyn_cast<ObjCInterfaceDecl>(FoundDecls[I])))
3816       break;
3817   }
3818 
3819   // Create an interface declaration, if one does not already exist.
3820   ObjCInterfaceDecl *ToIface = MergeWithIface;
3821   if (!ToIface) {
3822     ToIface = ObjCInterfaceDecl::Create(Importer.getToContext(), DC,
3823                                         Importer.Import(D->getAtStartLoc()),
3824                                         Name.getAsIdentifierInfo(),
3825                                         /*TypeParamList=*/nullptr,
3826                                         /*PrevDecl=*/nullptr, Loc,
3827                                         D->isImplicitInterfaceDecl());
3828     ToIface->setLexicalDeclContext(LexicalDC);
3829     LexicalDC->addDeclInternal(ToIface);
3830   }
3831   Importer.Imported(D, ToIface);
3832   // Import the type parameter list after calling Imported, to avoid
3833   // loops when bringing in their DeclContext.
3834   ToIface->setTypeParamList(ImportObjCTypeParamList(
3835                               D->getTypeParamListAsWritten()));
3836 
3837   if (D->isThisDeclarationADefinition() && ImportDefinition(D, ToIface))
3838     return nullptr;
3839 
3840   return ToIface;
3841 }
3842 
3843 Decl *ASTNodeImporter::VisitObjCCategoryImplDecl(ObjCCategoryImplDecl *D) {
3844   ObjCCategoryDecl *Category = cast_or_null<ObjCCategoryDecl>(
3845                                         Importer.Import(D->getCategoryDecl()));
3846   if (!Category)
3847     return nullptr;
3848 
3849   ObjCCategoryImplDecl *ToImpl = Category->getImplementation();
3850   if (!ToImpl) {
3851     DeclContext *DC = Importer.ImportContext(D->getDeclContext());
3852     if (!DC)
3853       return nullptr;
3854 
3855     SourceLocation CategoryNameLoc = Importer.Import(D->getCategoryNameLoc());
3856     ToImpl = ObjCCategoryImplDecl::Create(Importer.getToContext(), DC,
3857                                           Importer.Import(D->getIdentifier()),
3858                                           Category->getClassInterface(),
3859                                           Importer.Import(D->getLocation()),
3860                                           Importer.Import(D->getAtStartLoc()),
3861                                           CategoryNameLoc);
3862 
3863     DeclContext *LexicalDC = DC;
3864     if (D->getDeclContext() != D->getLexicalDeclContext()) {
3865       LexicalDC = Importer.ImportContext(D->getLexicalDeclContext());
3866       if (!LexicalDC)
3867         return nullptr;
3868 
3869       ToImpl->setLexicalDeclContext(LexicalDC);
3870     }
3871 
3872     LexicalDC->addDeclInternal(ToImpl);
3873     Category->setImplementation(ToImpl);
3874   }
3875 
3876   Importer.Imported(D, ToImpl);
3877   ImportDeclContext(D);
3878   return ToImpl;
3879 }
3880 
3881 Decl *ASTNodeImporter::VisitObjCImplementationDecl(ObjCImplementationDecl *D) {
3882   // Find the corresponding interface.
3883   ObjCInterfaceDecl *Iface = cast_or_null<ObjCInterfaceDecl>(
3884                                        Importer.Import(D->getClassInterface()));
3885   if (!Iface)
3886     return nullptr;
3887 
3888   // Import the superclass, if any.
3889   ObjCInterfaceDecl *Super = nullptr;
3890   if (D->getSuperClass()) {
3891     Super = cast_or_null<ObjCInterfaceDecl>(
3892                                           Importer.Import(D->getSuperClass()));
3893     if (!Super)
3894       return nullptr;
3895   }
3896 
3897   ObjCImplementationDecl *Impl = Iface->getImplementation();
3898   if (!Impl) {
3899     // We haven't imported an implementation yet. Create a new @implementation
3900     // now.
3901     Impl = ObjCImplementationDecl::Create(Importer.getToContext(),
3902                                   Importer.ImportContext(D->getDeclContext()),
3903                                           Iface, Super,
3904                                           Importer.Import(D->getLocation()),
3905                                           Importer.Import(D->getAtStartLoc()),
3906                                           Importer.Import(D->getSuperClassLoc()),
3907                                           Importer.Import(D->getIvarLBraceLoc()),
3908                                           Importer.Import(D->getIvarRBraceLoc()));
3909 
3910     if (D->getDeclContext() != D->getLexicalDeclContext()) {
3911       DeclContext *LexicalDC
3912         = Importer.ImportContext(D->getLexicalDeclContext());
3913       if (!LexicalDC)
3914         return nullptr;
3915       Impl->setLexicalDeclContext(LexicalDC);
3916     }
3917 
3918     // Associate the implementation with the class it implements.
3919     Iface->setImplementation(Impl);
3920     Importer.Imported(D, Iface->getImplementation());
3921   } else {
3922     Importer.Imported(D, Iface->getImplementation());
3923 
3924     // Verify that the existing @implementation has the same superclass.
3925     if ((Super && !Impl->getSuperClass()) ||
3926         (!Super && Impl->getSuperClass()) ||
3927         (Super && Impl->getSuperClass() &&
3928          !declaresSameEntity(Super->getCanonicalDecl(),
3929                              Impl->getSuperClass()))) {
3930       Importer.ToDiag(Impl->getLocation(),
3931                       diag::err_odr_objc_superclass_inconsistent)
3932         << Iface->getDeclName();
3933       // FIXME: It would be nice to have the location of the superclass
3934       // below.
3935       if (Impl->getSuperClass())
3936         Importer.ToDiag(Impl->getLocation(),
3937                         diag::note_odr_objc_superclass)
3938         << Impl->getSuperClass()->getDeclName();
3939       else
3940         Importer.ToDiag(Impl->getLocation(),
3941                         diag::note_odr_objc_missing_superclass);
3942       if (D->getSuperClass())
3943         Importer.FromDiag(D->getLocation(),
3944                           diag::note_odr_objc_superclass)
3945         << D->getSuperClass()->getDeclName();
3946       else
3947         Importer.FromDiag(D->getLocation(),
3948                           diag::note_odr_objc_missing_superclass);
3949       return nullptr;
3950     }
3951   }
3952 
3953   // Import all of the members of this @implementation.
3954   ImportDeclContext(D);
3955 
3956   return Impl;
3957 }
3958 
3959 Decl *ASTNodeImporter::VisitObjCPropertyDecl(ObjCPropertyDecl *D) {
3960   // Import the major distinguishing characteristics of an @property.
3961   DeclContext *DC, *LexicalDC;
3962   DeclarationName Name;
3963   SourceLocation Loc;
3964   NamedDecl *ToD;
3965   if (ImportDeclParts(D, DC, LexicalDC, Name, ToD, Loc))
3966     return nullptr;
3967   if (ToD)
3968     return ToD;
3969 
3970   // Check whether we have already imported this property.
3971   SmallVector<NamedDecl *, 2> FoundDecls;
3972   DC->getRedeclContext()->localUncachedLookup(Name, FoundDecls);
3973   for (unsigned I = 0, N = FoundDecls.size(); I != N; ++I) {
3974     if (ObjCPropertyDecl *FoundProp
3975                                 = dyn_cast<ObjCPropertyDecl>(FoundDecls[I])) {
3976       // Check property types.
3977       if (!Importer.IsStructurallyEquivalent(D->getType(),
3978                                              FoundProp->getType())) {
3979         Importer.ToDiag(Loc, diag::err_odr_objc_property_type_inconsistent)
3980           << Name << D->getType() << FoundProp->getType();
3981         Importer.ToDiag(FoundProp->getLocation(), diag::note_odr_value_here)
3982           << FoundProp->getType();
3983         return nullptr;
3984       }
3985 
3986       // FIXME: Check property attributes, getters, setters, etc.?
3987 
3988       // Consider these properties to be equivalent.
3989       Importer.Imported(D, FoundProp);
3990       return FoundProp;
3991     }
3992   }
3993 
3994   // Import the type.
3995   TypeSourceInfo *TSI = Importer.Import(D->getTypeSourceInfo());
3996   if (!TSI)
3997     return nullptr;
3998 
3999   // Create the new property.
4000   ObjCPropertyDecl *ToProperty
4001     = ObjCPropertyDecl::Create(Importer.getToContext(), DC, Loc,
4002                                Name.getAsIdentifierInfo(),
4003                                Importer.Import(D->getAtLoc()),
4004                                Importer.Import(D->getLParenLoc()),
4005                                Importer.Import(D->getType()),
4006                                TSI,
4007                                D->getPropertyImplementation());
4008   Importer.Imported(D, ToProperty);
4009   ToProperty->setLexicalDeclContext(LexicalDC);
4010   LexicalDC->addDeclInternal(ToProperty);
4011 
4012   ToProperty->setPropertyAttributes(D->getPropertyAttributes());
4013   ToProperty->setPropertyAttributesAsWritten(
4014                                       D->getPropertyAttributesAsWritten());
4015   ToProperty->setGetterName(Importer.Import(D->getGetterName()));
4016   ToProperty->setSetterName(Importer.Import(D->getSetterName()));
4017   ToProperty->setGetterMethodDecl(
4018      cast_or_null<ObjCMethodDecl>(Importer.Import(D->getGetterMethodDecl())));
4019   ToProperty->setSetterMethodDecl(
4020      cast_or_null<ObjCMethodDecl>(Importer.Import(D->getSetterMethodDecl())));
4021   ToProperty->setPropertyIvarDecl(
4022        cast_or_null<ObjCIvarDecl>(Importer.Import(D->getPropertyIvarDecl())));
4023   return ToProperty;
4024 }
4025 
4026 Decl *ASTNodeImporter::VisitObjCPropertyImplDecl(ObjCPropertyImplDecl *D) {
4027   ObjCPropertyDecl *Property = cast_or_null<ObjCPropertyDecl>(
4028                                         Importer.Import(D->getPropertyDecl()));
4029   if (!Property)
4030     return nullptr;
4031 
4032   DeclContext *DC = Importer.ImportContext(D->getDeclContext());
4033   if (!DC)
4034     return nullptr;
4035 
4036   // Import the lexical declaration context.
4037   DeclContext *LexicalDC = DC;
4038   if (D->getDeclContext() != D->getLexicalDeclContext()) {
4039     LexicalDC = Importer.ImportContext(D->getLexicalDeclContext());
4040     if (!LexicalDC)
4041       return nullptr;
4042   }
4043 
4044   ObjCImplDecl *InImpl = dyn_cast<ObjCImplDecl>(LexicalDC);
4045   if (!InImpl)
4046     return nullptr;
4047 
4048   // Import the ivar (for an @synthesize).
4049   ObjCIvarDecl *Ivar = nullptr;
4050   if (D->getPropertyIvarDecl()) {
4051     Ivar = cast_or_null<ObjCIvarDecl>(
4052                                     Importer.Import(D->getPropertyIvarDecl()));
4053     if (!Ivar)
4054       return nullptr;
4055   }
4056 
4057   ObjCPropertyImplDecl *ToImpl
4058     = InImpl->FindPropertyImplDecl(Property->getIdentifier());
4059   if (!ToImpl) {
4060     ToImpl = ObjCPropertyImplDecl::Create(Importer.getToContext(), DC,
4061                                           Importer.Import(D->getLocStart()),
4062                                           Importer.Import(D->getLocation()),
4063                                           Property,
4064                                           D->getPropertyImplementation(),
4065                                           Ivar,
4066                                   Importer.Import(D->getPropertyIvarDeclLoc()));
4067     ToImpl->setLexicalDeclContext(LexicalDC);
4068     Importer.Imported(D, ToImpl);
4069     LexicalDC->addDeclInternal(ToImpl);
4070   } else {
4071     // Check that we have the same kind of property implementation (@synthesize
4072     // vs. @dynamic).
4073     if (D->getPropertyImplementation() != ToImpl->getPropertyImplementation()) {
4074       Importer.ToDiag(ToImpl->getLocation(),
4075                       diag::err_odr_objc_property_impl_kind_inconsistent)
4076         << Property->getDeclName()
4077         << (ToImpl->getPropertyImplementation()
4078                                               == ObjCPropertyImplDecl::Dynamic);
4079       Importer.FromDiag(D->getLocation(),
4080                         diag::note_odr_objc_property_impl_kind)
4081         << D->getPropertyDecl()->getDeclName()
4082         << (D->getPropertyImplementation() == ObjCPropertyImplDecl::Dynamic);
4083       return nullptr;
4084     }
4085 
4086     // For @synthesize, check that we have the same
4087     if (D->getPropertyImplementation() == ObjCPropertyImplDecl::Synthesize &&
4088         Ivar != ToImpl->getPropertyIvarDecl()) {
4089       Importer.ToDiag(ToImpl->getPropertyIvarDeclLoc(),
4090                       diag::err_odr_objc_synthesize_ivar_inconsistent)
4091         << Property->getDeclName()
4092         << ToImpl->getPropertyIvarDecl()->getDeclName()
4093         << Ivar->getDeclName();
4094       Importer.FromDiag(D->getPropertyIvarDeclLoc(),
4095                         diag::note_odr_objc_synthesize_ivar_here)
4096         << D->getPropertyIvarDecl()->getDeclName();
4097       return nullptr;
4098     }
4099 
4100     // Merge the existing implementation with the new implementation.
4101     Importer.Imported(D, ToImpl);
4102   }
4103 
4104   return ToImpl;
4105 }
4106 
4107 Decl *ASTNodeImporter::VisitTemplateTypeParmDecl(TemplateTypeParmDecl *D) {
4108   // For template arguments, we adopt the translation unit as our declaration
4109   // context. This context will be fixed when the actual template declaration
4110   // is created.
4111 
4112   // FIXME: Import default argument.
4113   return TemplateTypeParmDecl::Create(Importer.getToContext(),
4114                               Importer.getToContext().getTranslationUnitDecl(),
4115                                       Importer.Import(D->getLocStart()),
4116                                       Importer.Import(D->getLocation()),
4117                                       D->getDepth(),
4118                                       D->getIndex(),
4119                                       Importer.Import(D->getIdentifier()),
4120                                       D->wasDeclaredWithTypename(),
4121                                       D->isParameterPack());
4122 }
4123 
4124 Decl *
4125 ASTNodeImporter::VisitNonTypeTemplateParmDecl(NonTypeTemplateParmDecl *D) {
4126   // Import the name of this declaration.
4127   DeclarationName Name = Importer.Import(D->getDeclName());
4128   if (D->getDeclName() && !Name)
4129     return nullptr;
4130 
4131   // Import the location of this declaration.
4132   SourceLocation Loc = Importer.Import(D->getLocation());
4133 
4134   // Import the type of this declaration.
4135   QualType T = Importer.Import(D->getType());
4136   if (T.isNull())
4137     return nullptr;
4138 
4139   // Import type-source information.
4140   TypeSourceInfo *TInfo = Importer.Import(D->getTypeSourceInfo());
4141   if (D->getTypeSourceInfo() && !TInfo)
4142     return nullptr;
4143 
4144   // FIXME: Import default argument.
4145 
4146   return NonTypeTemplateParmDecl::Create(Importer.getToContext(),
4147                                Importer.getToContext().getTranslationUnitDecl(),
4148                                          Importer.Import(D->getInnerLocStart()),
4149                                          Loc, D->getDepth(), D->getPosition(),
4150                                          Name.getAsIdentifierInfo(),
4151                                          T, D->isParameterPack(), TInfo);
4152 }
4153 
4154 Decl *
4155 ASTNodeImporter::VisitTemplateTemplateParmDecl(TemplateTemplateParmDecl *D) {
4156   // Import the name of this declaration.
4157   DeclarationName Name = Importer.Import(D->getDeclName());
4158   if (D->getDeclName() && !Name)
4159     return nullptr;
4160 
4161   // Import the location of this declaration.
4162   SourceLocation Loc = Importer.Import(D->getLocation());
4163 
4164   // Import template parameters.
4165   TemplateParameterList *TemplateParams
4166     = ImportTemplateParameterList(D->getTemplateParameters());
4167   if (!TemplateParams)
4168     return nullptr;
4169 
4170   // FIXME: Import default argument.
4171 
4172   return TemplateTemplateParmDecl::Create(Importer.getToContext(),
4173                               Importer.getToContext().getTranslationUnitDecl(),
4174                                           Loc, D->getDepth(), D->getPosition(),
4175                                           D->isParameterPack(),
4176                                           Name.getAsIdentifierInfo(),
4177                                           TemplateParams);
4178 }
4179 
4180 Decl *ASTNodeImporter::VisitClassTemplateDecl(ClassTemplateDecl *D) {
4181   // If this record has a definition in the translation unit we're coming from,
4182   // but this particular declaration is not that definition, import the
4183   // definition and map to that.
4184   CXXRecordDecl *Definition
4185     = cast_or_null<CXXRecordDecl>(D->getTemplatedDecl()->getDefinition());
4186   if (Definition && Definition != D->getTemplatedDecl()) {
4187     Decl *ImportedDef
4188       = Importer.Import(Definition->getDescribedClassTemplate());
4189     if (!ImportedDef)
4190       return nullptr;
4191 
4192     return Importer.Imported(D, ImportedDef);
4193   }
4194 
4195   // Import the major distinguishing characteristics of this class template.
4196   DeclContext *DC, *LexicalDC;
4197   DeclarationName Name;
4198   SourceLocation Loc;
4199   NamedDecl *ToD;
4200   if (ImportDeclParts(D, DC, LexicalDC, Name, ToD, Loc))
4201     return nullptr;
4202   if (ToD)
4203     return ToD;
4204 
4205   // We may already have a template of the same name; try to find and match it.
4206   if (!DC->isFunctionOrMethod()) {
4207     SmallVector<NamedDecl *, 4> ConflictingDecls;
4208     SmallVector<NamedDecl *, 2> FoundDecls;
4209     DC->getRedeclContext()->localUncachedLookup(Name, FoundDecls);
4210     for (unsigned I = 0, N = FoundDecls.size(); I != N; ++I) {
4211       if (!FoundDecls[I]->isInIdentifierNamespace(Decl::IDNS_Ordinary))
4212         continue;
4213 
4214       Decl *Found = FoundDecls[I];
4215       if (ClassTemplateDecl *FoundTemplate
4216                                         = dyn_cast<ClassTemplateDecl>(Found)) {
4217         if (IsStructuralMatch(D, FoundTemplate)) {
4218           // The class templates structurally match; call it the same template.
4219           // FIXME: We may be filling in a forward declaration here. Handle
4220           // this case!
4221           Importer.Imported(D->getTemplatedDecl(),
4222                             FoundTemplate->getTemplatedDecl());
4223           return Importer.Imported(D, FoundTemplate);
4224         }
4225       }
4226 
4227       ConflictingDecls.push_back(FoundDecls[I]);
4228     }
4229 
4230     if (!ConflictingDecls.empty()) {
4231       Name = Importer.HandleNameConflict(Name, DC, Decl::IDNS_Ordinary,
4232                                          ConflictingDecls.data(),
4233                                          ConflictingDecls.size());
4234     }
4235 
4236     if (!Name)
4237       return nullptr;
4238   }
4239 
4240   CXXRecordDecl *DTemplated = D->getTemplatedDecl();
4241 
4242   // Create the declaration that is being templated.
4243   SourceLocation StartLoc = Importer.Import(DTemplated->getLocStart());
4244   SourceLocation IdLoc = Importer.Import(DTemplated->getLocation());
4245   CXXRecordDecl *D2Templated = CXXRecordDecl::Create(Importer.getToContext(),
4246                                                      DTemplated->getTagKind(),
4247                                                      DC, StartLoc, IdLoc,
4248                                                    Name.getAsIdentifierInfo());
4249   D2Templated->setAccess(DTemplated->getAccess());
4250   D2Templated->setQualifierInfo(Importer.Import(DTemplated->getQualifierLoc()));
4251   D2Templated->setLexicalDeclContext(LexicalDC);
4252 
4253   // Create the class template declaration itself.
4254   TemplateParameterList *TemplateParams
4255     = ImportTemplateParameterList(D->getTemplateParameters());
4256   if (!TemplateParams)
4257     return nullptr;
4258 
4259   ClassTemplateDecl *D2 = ClassTemplateDecl::Create(Importer.getToContext(), DC,
4260                                                     Loc, Name, TemplateParams,
4261                                                     D2Templated,
4262                                                     /*PrevDecl=*/nullptr);
4263   D2Templated->setDescribedClassTemplate(D2);
4264 
4265   D2->setAccess(D->getAccess());
4266   D2->setLexicalDeclContext(LexicalDC);
4267   LexicalDC->addDeclInternal(D2);
4268 
4269   // Note the relationship between the class templates.
4270   Importer.Imported(D, D2);
4271   Importer.Imported(DTemplated, D2Templated);
4272 
4273   if (DTemplated->isCompleteDefinition() &&
4274       !D2Templated->isCompleteDefinition()) {
4275     // FIXME: Import definition!
4276   }
4277 
4278   return D2;
4279 }
4280 
4281 Decl *ASTNodeImporter::VisitClassTemplateSpecializationDecl(
4282                                           ClassTemplateSpecializationDecl *D) {
4283   // If this record has a definition in the translation unit we're coming from,
4284   // but this particular declaration is not that definition, import the
4285   // definition and map to that.
4286   TagDecl *Definition = D->getDefinition();
4287   if (Definition && Definition != D) {
4288     Decl *ImportedDef = Importer.Import(Definition);
4289     if (!ImportedDef)
4290       return nullptr;
4291 
4292     return Importer.Imported(D, ImportedDef);
4293   }
4294 
4295   ClassTemplateDecl *ClassTemplate
4296     = cast_or_null<ClassTemplateDecl>(Importer.Import(
4297                                                  D->getSpecializedTemplate()));
4298   if (!ClassTemplate)
4299     return nullptr;
4300 
4301   // Import the context of this declaration.
4302   DeclContext *DC = ClassTemplate->getDeclContext();
4303   if (!DC)
4304     return nullptr;
4305 
4306   DeclContext *LexicalDC = DC;
4307   if (D->getDeclContext() != D->getLexicalDeclContext()) {
4308     LexicalDC = Importer.ImportContext(D->getLexicalDeclContext());
4309     if (!LexicalDC)
4310       return nullptr;
4311   }
4312 
4313   // Import the location of this declaration.
4314   SourceLocation StartLoc = Importer.Import(D->getLocStart());
4315   SourceLocation IdLoc = Importer.Import(D->getLocation());
4316 
4317   // Import template arguments.
4318   SmallVector<TemplateArgument, 2> TemplateArgs;
4319   if (ImportTemplateArguments(D->getTemplateArgs().data(),
4320                               D->getTemplateArgs().size(),
4321                               TemplateArgs))
4322     return nullptr;
4323 
4324   // Try to find an existing specialization with these template arguments.
4325   void *InsertPos = nullptr;
4326   ClassTemplateSpecializationDecl *D2
4327     = ClassTemplate->findSpecialization(TemplateArgs, InsertPos);
4328   if (D2) {
4329     // We already have a class template specialization with these template
4330     // arguments.
4331 
4332     // FIXME: Check for specialization vs. instantiation errors.
4333 
4334     if (RecordDecl *FoundDef = D2->getDefinition()) {
4335       if (!D->isCompleteDefinition() || IsStructuralMatch(D, FoundDef)) {
4336         // The record types structurally match, or the "from" translation
4337         // unit only had a forward declaration anyway; call it the same
4338         // function.
4339         return Importer.Imported(D, FoundDef);
4340       }
4341     }
4342   } else {
4343     // Create a new specialization.
4344     D2 = ClassTemplateSpecializationDecl::Create(Importer.getToContext(),
4345                                                  D->getTagKind(), DC,
4346                                                  StartLoc, IdLoc,
4347                                                  ClassTemplate,
4348                                                  TemplateArgs.data(),
4349                                                  TemplateArgs.size(),
4350                                                  /*PrevDecl=*/nullptr);
4351     D2->setSpecializationKind(D->getSpecializationKind());
4352 
4353     // Add this specialization to the class template.
4354     ClassTemplate->AddSpecialization(D2, InsertPos);
4355 
4356     // Import the qualifier, if any.
4357     D2->setQualifierInfo(Importer.Import(D->getQualifierLoc()));
4358 
4359     // Add the specialization to this context.
4360     D2->setLexicalDeclContext(LexicalDC);
4361     LexicalDC->addDeclInternal(D2);
4362   }
4363   Importer.Imported(D, D2);
4364 
4365   if (D->isCompleteDefinition() && ImportDefinition(D, D2))
4366     return nullptr;
4367 
4368   return D2;
4369 }
4370 
4371 Decl *ASTNodeImporter::VisitVarTemplateDecl(VarTemplateDecl *D) {
4372   // If this variable has a definition in the translation unit we're coming
4373   // from,
4374   // but this particular declaration is not that definition, import the
4375   // definition and map to that.
4376   VarDecl *Definition =
4377       cast_or_null<VarDecl>(D->getTemplatedDecl()->getDefinition());
4378   if (Definition && Definition != D->getTemplatedDecl()) {
4379     Decl *ImportedDef = Importer.Import(Definition->getDescribedVarTemplate());
4380     if (!ImportedDef)
4381       return nullptr;
4382 
4383     return Importer.Imported(D, ImportedDef);
4384   }
4385 
4386   // Import the major distinguishing characteristics of this variable template.
4387   DeclContext *DC, *LexicalDC;
4388   DeclarationName Name;
4389   SourceLocation Loc;
4390   NamedDecl *ToD;
4391   if (ImportDeclParts(D, DC, LexicalDC, Name, ToD, Loc))
4392     return nullptr;
4393   if (ToD)
4394     return ToD;
4395 
4396   // We may already have a template of the same name; try to find and match it.
4397   assert(!DC->isFunctionOrMethod() &&
4398          "Variable templates cannot be declared at function scope");
4399   SmallVector<NamedDecl *, 4> ConflictingDecls;
4400   SmallVector<NamedDecl *, 2> FoundDecls;
4401   DC->getRedeclContext()->localUncachedLookup(Name, FoundDecls);
4402   for (unsigned I = 0, N = FoundDecls.size(); I != N; ++I) {
4403     if (!FoundDecls[I]->isInIdentifierNamespace(Decl::IDNS_Ordinary))
4404       continue;
4405 
4406     Decl *Found = FoundDecls[I];
4407     if (VarTemplateDecl *FoundTemplate = dyn_cast<VarTemplateDecl>(Found)) {
4408       if (IsStructuralMatch(D, FoundTemplate)) {
4409         // The variable templates structurally match; call it the same template.
4410         Importer.Imported(D->getTemplatedDecl(),
4411                           FoundTemplate->getTemplatedDecl());
4412         return Importer.Imported(D, FoundTemplate);
4413       }
4414     }
4415 
4416     ConflictingDecls.push_back(FoundDecls[I]);
4417   }
4418 
4419   if (!ConflictingDecls.empty()) {
4420     Name = Importer.HandleNameConflict(Name, DC, Decl::IDNS_Ordinary,
4421                                        ConflictingDecls.data(),
4422                                        ConflictingDecls.size());
4423   }
4424 
4425   if (!Name)
4426     return nullptr;
4427 
4428   VarDecl *DTemplated = D->getTemplatedDecl();
4429 
4430   // Import the type.
4431   QualType T = Importer.Import(DTemplated->getType());
4432   if (T.isNull())
4433     return nullptr;
4434 
4435   // Create the declaration that is being templated.
4436   SourceLocation StartLoc = Importer.Import(DTemplated->getLocStart());
4437   SourceLocation IdLoc = Importer.Import(DTemplated->getLocation());
4438   TypeSourceInfo *TInfo = Importer.Import(DTemplated->getTypeSourceInfo());
4439   VarDecl *D2Templated = VarDecl::Create(Importer.getToContext(), DC, StartLoc,
4440                                          IdLoc, Name.getAsIdentifierInfo(), T,
4441                                          TInfo, DTemplated->getStorageClass());
4442   D2Templated->setAccess(DTemplated->getAccess());
4443   D2Templated->setQualifierInfo(Importer.Import(DTemplated->getQualifierLoc()));
4444   D2Templated->setLexicalDeclContext(LexicalDC);
4445 
4446   // Importer.Imported(DTemplated, D2Templated);
4447   // LexicalDC->addDeclInternal(D2Templated);
4448 
4449   // Merge the initializer.
4450   if (ImportDefinition(DTemplated, D2Templated))
4451     return nullptr;
4452 
4453   // Create the variable template declaration itself.
4454   TemplateParameterList *TemplateParams =
4455       ImportTemplateParameterList(D->getTemplateParameters());
4456   if (!TemplateParams)
4457     return nullptr;
4458 
4459   VarTemplateDecl *D2 = VarTemplateDecl::Create(
4460       Importer.getToContext(), DC, Loc, Name, TemplateParams, D2Templated);
4461   D2Templated->setDescribedVarTemplate(D2);
4462 
4463   D2->setAccess(D->getAccess());
4464   D2->setLexicalDeclContext(LexicalDC);
4465   LexicalDC->addDeclInternal(D2);
4466 
4467   // Note the relationship between the variable templates.
4468   Importer.Imported(D, D2);
4469   Importer.Imported(DTemplated, D2Templated);
4470 
4471   if (DTemplated->isThisDeclarationADefinition() &&
4472       !D2Templated->isThisDeclarationADefinition()) {
4473     // FIXME: Import definition!
4474   }
4475 
4476   return D2;
4477 }
4478 
4479 Decl *ASTNodeImporter::VisitVarTemplateSpecializationDecl(
4480     VarTemplateSpecializationDecl *D) {
4481   // If this record has a definition in the translation unit we're coming from,
4482   // but this particular declaration is not that definition, import the
4483   // definition and map to that.
4484   VarDecl *Definition = D->getDefinition();
4485   if (Definition && Definition != D) {
4486     Decl *ImportedDef = Importer.Import(Definition);
4487     if (!ImportedDef)
4488       return nullptr;
4489 
4490     return Importer.Imported(D, ImportedDef);
4491   }
4492 
4493   VarTemplateDecl *VarTemplate = cast_or_null<VarTemplateDecl>(
4494       Importer.Import(D->getSpecializedTemplate()));
4495   if (!VarTemplate)
4496     return nullptr;
4497 
4498   // Import the context of this declaration.
4499   DeclContext *DC = VarTemplate->getDeclContext();
4500   if (!DC)
4501     return nullptr;
4502 
4503   DeclContext *LexicalDC = DC;
4504   if (D->getDeclContext() != D->getLexicalDeclContext()) {
4505     LexicalDC = Importer.ImportContext(D->getLexicalDeclContext());
4506     if (!LexicalDC)
4507       return nullptr;
4508   }
4509 
4510   // Import the location of this declaration.
4511   SourceLocation StartLoc = Importer.Import(D->getLocStart());
4512   SourceLocation IdLoc = Importer.Import(D->getLocation());
4513 
4514   // Import template arguments.
4515   SmallVector<TemplateArgument, 2> TemplateArgs;
4516   if (ImportTemplateArguments(D->getTemplateArgs().data(),
4517                               D->getTemplateArgs().size(), TemplateArgs))
4518     return nullptr;
4519 
4520   // Try to find an existing specialization with these template arguments.
4521   void *InsertPos = nullptr;
4522   VarTemplateSpecializationDecl *D2 = VarTemplate->findSpecialization(
4523       TemplateArgs, InsertPos);
4524   if (D2) {
4525     // We already have a variable template specialization with these template
4526     // arguments.
4527 
4528     // FIXME: Check for specialization vs. instantiation errors.
4529 
4530     if (VarDecl *FoundDef = D2->getDefinition()) {
4531       if (!D->isThisDeclarationADefinition() ||
4532           IsStructuralMatch(D, FoundDef)) {
4533         // The record types structurally match, or the "from" translation
4534         // unit only had a forward declaration anyway; call it the same
4535         // variable.
4536         return Importer.Imported(D, FoundDef);
4537       }
4538     }
4539   } else {
4540 
4541     // Import the type.
4542     QualType T = Importer.Import(D->getType());
4543     if (T.isNull())
4544       return nullptr;
4545     TypeSourceInfo *TInfo = Importer.Import(D->getTypeSourceInfo());
4546 
4547     // Create a new specialization.
4548     D2 = VarTemplateSpecializationDecl::Create(
4549         Importer.getToContext(), DC, StartLoc, IdLoc, VarTemplate, T, TInfo,
4550         D->getStorageClass(), TemplateArgs.data(), TemplateArgs.size());
4551     D2->setSpecializationKind(D->getSpecializationKind());
4552     D2->setTemplateArgsInfo(D->getTemplateArgsInfo());
4553 
4554     // Add this specialization to the class template.
4555     VarTemplate->AddSpecialization(D2, InsertPos);
4556 
4557     // Import the qualifier, if any.
4558     D2->setQualifierInfo(Importer.Import(D->getQualifierLoc()));
4559 
4560     // Add the specialization to this context.
4561     D2->setLexicalDeclContext(LexicalDC);
4562     LexicalDC->addDeclInternal(D2);
4563   }
4564   Importer.Imported(D, D2);
4565 
4566   if (D->isThisDeclarationADefinition() && ImportDefinition(D, D2))
4567     return nullptr;
4568 
4569   return D2;
4570 }
4571 
4572 //----------------------------------------------------------------------------
4573 // Import Statements
4574 //----------------------------------------------------------------------------
4575 
4576 DeclGroupRef ASTNodeImporter::ImportDeclGroup(DeclGroupRef DG) {
4577   if (DG.isNull())
4578     return DeclGroupRef::Create(Importer.getToContext(), nullptr, 0);
4579   size_t NumDecls = DG.end() - DG.begin();
4580   SmallVector<Decl *, 1> ToDecls(NumDecls);
4581   auto &_Importer = this->Importer;
4582   std::transform(DG.begin(), DG.end(), ToDecls.begin(),
4583     [&_Importer](Decl *D) -> Decl * {
4584       return _Importer.Import(D);
4585     });
4586   return DeclGroupRef::Create(Importer.getToContext(),
4587                               ToDecls.begin(),
4588                               NumDecls);
4589 }
4590 
4591  Stmt *ASTNodeImporter::VisitStmt(Stmt *S) {
4592    Importer.FromDiag(S->getLocStart(), diag::err_unsupported_ast_node)
4593      << S->getStmtClassName();
4594    return nullptr;
4595  }
4596 
4597 Stmt *ASTNodeImporter::VisitDeclStmt(DeclStmt *S) {
4598   DeclGroupRef ToDG = ImportDeclGroup(S->getDeclGroup());
4599   for (Decl *ToD : ToDG) {
4600     if (!ToD)
4601       return nullptr;
4602   }
4603   SourceLocation ToStartLoc = Importer.Import(S->getStartLoc());
4604   SourceLocation ToEndLoc = Importer.Import(S->getEndLoc());
4605   return new (Importer.getToContext()) DeclStmt(ToDG, ToStartLoc, ToEndLoc);
4606 }
4607 
4608 Stmt *ASTNodeImporter::VisitNullStmt(NullStmt *S) {
4609   SourceLocation ToSemiLoc = Importer.Import(S->getSemiLoc());
4610   return new (Importer.getToContext()) NullStmt(ToSemiLoc,
4611                                                 S->hasLeadingEmptyMacro());
4612 }
4613 
4614 Stmt *ASTNodeImporter::VisitCompoundStmt(CompoundStmt *S) {
4615   SmallVector<Stmt *, 4> ToStmts(S->size());
4616   auto &_Importer = this->Importer;
4617   std::transform(S->body_begin(), S->body_end(), ToStmts.begin(),
4618     [&_Importer](Stmt *CS) -> Stmt * {
4619       return _Importer.Import(CS);
4620     });
4621   for (Stmt *ToS : ToStmts) {
4622     if (!ToS)
4623       return nullptr;
4624   }
4625   SourceLocation ToLBraceLoc = Importer.Import(S->getLBracLoc());
4626   SourceLocation ToRBraceLoc = Importer.Import(S->getRBracLoc());
4627   return new (Importer.getToContext()) CompoundStmt(Importer.getToContext(),
4628                                                     ToStmts,
4629                                                     ToLBraceLoc, ToRBraceLoc);
4630 }
4631 
4632 Stmt *ASTNodeImporter::VisitCaseStmt(CaseStmt *S) {
4633   Expr *ToLHS = Importer.Import(S->getLHS());
4634   if (!ToLHS)
4635     return nullptr;
4636   Expr *ToRHS = Importer.Import(S->getRHS());
4637   if (!ToRHS && S->getRHS())
4638     return nullptr;
4639   SourceLocation ToCaseLoc = Importer.Import(S->getCaseLoc());
4640   SourceLocation ToEllipsisLoc = Importer.Import(S->getEllipsisLoc());
4641   SourceLocation ToColonLoc = Importer.Import(S->getColonLoc());
4642   return new (Importer.getToContext()) CaseStmt(ToLHS, ToRHS,
4643                                                 ToCaseLoc, ToEllipsisLoc,
4644                                                 ToColonLoc);
4645 }
4646 
4647 Stmt *ASTNodeImporter::VisitDefaultStmt(DefaultStmt *S) {
4648   SourceLocation ToDefaultLoc = Importer.Import(S->getDefaultLoc());
4649   SourceLocation ToColonLoc = Importer.Import(S->getColonLoc());
4650   Stmt *ToSubStmt = Importer.Import(S->getSubStmt());
4651   if (!ToSubStmt && S->getSubStmt())
4652     return nullptr;
4653   return new (Importer.getToContext()) DefaultStmt(ToDefaultLoc, ToColonLoc,
4654                                                    ToSubStmt);
4655 }
4656 
4657 Stmt *ASTNodeImporter::VisitLabelStmt(LabelStmt *S) {
4658   SourceLocation ToIdentLoc = Importer.Import(S->getIdentLoc());
4659   LabelDecl *ToLabelDecl =
4660     cast_or_null<LabelDecl>(Importer.Import(S->getDecl()));
4661   if (!ToLabelDecl && S->getDecl())
4662     return nullptr;
4663   Stmt *ToSubStmt = Importer.Import(S->getSubStmt());
4664   if (!ToSubStmt && S->getSubStmt())
4665     return nullptr;
4666   return new (Importer.getToContext()) LabelStmt(ToIdentLoc, ToLabelDecl,
4667                                                  ToSubStmt);
4668 }
4669 
4670 Stmt *ASTNodeImporter::VisitAttributedStmt(AttributedStmt *S) {
4671   SourceLocation ToAttrLoc = Importer.Import(S->getAttrLoc());
4672   ArrayRef<const Attr*> FromAttrs(S->getAttrs());
4673   SmallVector<const Attr *, 1> ToAttrs(FromAttrs.size());
4674   ASTContext &_ToContext = Importer.getToContext();
4675   std::transform(FromAttrs.begin(), FromAttrs.end(), ToAttrs.begin(),
4676     [&_ToContext](const Attr *A) -> const Attr * {
4677       return A->clone(_ToContext);
4678     });
4679   for (const Attr *ToA : ToAttrs) {
4680     if (!ToA)
4681       return nullptr;
4682   }
4683   Stmt *ToSubStmt = Importer.Import(S->getSubStmt());
4684   if (!ToSubStmt && S->getSubStmt())
4685     return nullptr;
4686   return AttributedStmt::Create(Importer.getToContext(), ToAttrLoc,
4687                                 ToAttrs, ToSubStmt);
4688 }
4689 
4690 Stmt *ASTNodeImporter::VisitIfStmt(IfStmt *S) {
4691   SourceLocation ToIfLoc = Importer.Import(S->getIfLoc());
4692   VarDecl *ToConditionVariable = nullptr;
4693   if (VarDecl *FromConditionVariable = S->getConditionVariable()) {
4694     ToConditionVariable =
4695       dyn_cast_or_null<VarDecl>(Importer.Import(FromConditionVariable));
4696     if (!ToConditionVariable)
4697       return nullptr;
4698   }
4699   Expr *ToCondition = Importer.Import(S->getCond());
4700   if (!ToCondition && S->getCond())
4701     return nullptr;
4702   Stmt *ToThenStmt = Importer.Import(S->getThen());
4703   if (!ToThenStmt && S->getThen())
4704     return nullptr;
4705   SourceLocation ToElseLoc = Importer.Import(S->getElseLoc());
4706   Stmt *ToElseStmt = Importer.Import(S->getElse());
4707   if (!ToElseStmt && S->getElse())
4708     return nullptr;
4709   return new (Importer.getToContext()) IfStmt(Importer.getToContext(),
4710                                               ToIfLoc, ToConditionVariable,
4711                                               ToCondition, ToThenStmt,
4712                                               ToElseLoc, ToElseStmt);
4713 }
4714 
4715 Stmt *ASTNodeImporter::VisitSwitchStmt(SwitchStmt *S) {
4716   VarDecl *ToConditionVariable = nullptr;
4717   if (VarDecl *FromConditionVariable = S->getConditionVariable()) {
4718     ToConditionVariable =
4719       dyn_cast_or_null<VarDecl>(Importer.Import(FromConditionVariable));
4720     if (!ToConditionVariable)
4721       return nullptr;
4722   }
4723   Expr *ToCondition = Importer.Import(S->getCond());
4724   if (!ToCondition && S->getCond())
4725     return nullptr;
4726   SwitchStmt *ToStmt = new (Importer.getToContext()) SwitchStmt(
4727                          Importer.getToContext(), ToConditionVariable,
4728                          ToCondition);
4729   Stmt *ToBody = Importer.Import(S->getBody());
4730   if (!ToBody && S->getBody())
4731     return nullptr;
4732   ToStmt->setBody(ToBody);
4733   ToStmt->setSwitchLoc(Importer.Import(S->getSwitchLoc()));
4734   // Now we have to re-chain the cases.
4735   SwitchCase *LastChainedSwitchCase = nullptr;
4736   for (SwitchCase *SC = S->getSwitchCaseList(); SC != nullptr;
4737        SC = SC->getNextSwitchCase()) {
4738     SwitchCase *ToSC = dyn_cast_or_null<SwitchCase>(Importer.Import(SC));
4739     if (!ToSC)
4740       return nullptr;
4741     if (LastChainedSwitchCase)
4742       LastChainedSwitchCase->setNextSwitchCase(ToSC);
4743     else
4744       ToStmt->setSwitchCaseList(ToSC);
4745     LastChainedSwitchCase = ToSC;
4746   }
4747   return ToStmt;
4748 }
4749 
4750 Stmt *ASTNodeImporter::VisitWhileStmt(WhileStmt *S) {
4751   VarDecl *ToConditionVariable = nullptr;
4752   if (VarDecl *FromConditionVariable = S->getConditionVariable()) {
4753     ToConditionVariable =
4754       dyn_cast_or_null<VarDecl>(Importer.Import(FromConditionVariable));
4755     if (!ToConditionVariable)
4756       return nullptr;
4757   }
4758   Expr *ToCondition = Importer.Import(S->getCond());
4759   if (!ToCondition && S->getCond())
4760     return nullptr;
4761   Stmt *ToBody = Importer.Import(S->getBody());
4762   if (!ToBody && S->getBody())
4763     return nullptr;
4764   SourceLocation ToWhileLoc = Importer.Import(S->getWhileLoc());
4765   return new (Importer.getToContext()) WhileStmt(Importer.getToContext(),
4766                                                  ToConditionVariable,
4767                                                  ToCondition, ToBody,
4768                                                  ToWhileLoc);
4769 }
4770 
4771 Stmt *ASTNodeImporter::VisitDoStmt(DoStmt *S) {
4772   Stmt *ToBody = Importer.Import(S->getBody());
4773   if (!ToBody && S->getBody())
4774     return nullptr;
4775   Expr *ToCondition = Importer.Import(S->getCond());
4776   if (!ToCondition && S->getCond())
4777     return nullptr;
4778   SourceLocation ToDoLoc = Importer.Import(S->getDoLoc());
4779   SourceLocation ToWhileLoc = Importer.Import(S->getWhileLoc());
4780   SourceLocation ToRParenLoc = Importer.Import(S->getRParenLoc());
4781   return new (Importer.getToContext()) DoStmt(ToBody, ToCondition,
4782                                               ToDoLoc, ToWhileLoc,
4783                                               ToRParenLoc);
4784 }
4785 
4786 Stmt *ASTNodeImporter::VisitForStmt(ForStmt *S) {
4787   Stmt *ToInit = Importer.Import(S->getInit());
4788   if (!ToInit && S->getInit())
4789     return nullptr;
4790   Expr *ToCondition = Importer.Import(S->getCond());
4791   if (!ToCondition && S->getCond())
4792     return nullptr;
4793   VarDecl *ToConditionVariable = nullptr;
4794   if (VarDecl *FromConditionVariable = S->getConditionVariable()) {
4795     ToConditionVariable =
4796       dyn_cast_or_null<VarDecl>(Importer.Import(FromConditionVariable));
4797     if (!ToConditionVariable)
4798       return nullptr;
4799   }
4800   Expr *ToInc = Importer.Import(S->getInc());
4801   if (!ToInc && S->getInc())
4802     return nullptr;
4803   Stmt *ToBody = Importer.Import(S->getBody());
4804   if (!ToBody && S->getBody())
4805     return nullptr;
4806   SourceLocation ToForLoc = Importer.Import(S->getForLoc());
4807   SourceLocation ToLParenLoc = Importer.Import(S->getLParenLoc());
4808   SourceLocation ToRParenLoc = Importer.Import(S->getRParenLoc());
4809   return new (Importer.getToContext()) ForStmt(Importer.getToContext(),
4810                                                ToInit, ToCondition,
4811                                                ToConditionVariable,
4812                                                ToInc, ToBody,
4813                                                ToForLoc, ToLParenLoc,
4814                                                ToRParenLoc);
4815 }
4816 
4817 Stmt *ASTNodeImporter::VisitGotoStmt(GotoStmt *S) {
4818   LabelDecl *ToLabel = nullptr;
4819   if (LabelDecl *FromLabel = S->getLabel()) {
4820     ToLabel = dyn_cast_or_null<LabelDecl>(Importer.Import(FromLabel));
4821     if (!ToLabel)
4822       return nullptr;
4823   }
4824   SourceLocation ToGotoLoc = Importer.Import(S->getGotoLoc());
4825   SourceLocation ToLabelLoc = Importer.Import(S->getLabelLoc());
4826   return new (Importer.getToContext()) GotoStmt(ToLabel,
4827                                                 ToGotoLoc, ToLabelLoc);
4828 }
4829 
4830 Stmt *ASTNodeImporter::VisitIndirectGotoStmt(IndirectGotoStmt *S) {
4831   SourceLocation ToGotoLoc = Importer.Import(S->getGotoLoc());
4832   SourceLocation ToStarLoc = Importer.Import(S->getStarLoc());
4833   Expr *ToTarget = Importer.Import(S->getTarget());
4834   if (!ToTarget && S->getTarget())
4835     return nullptr;
4836   return new (Importer.getToContext()) IndirectGotoStmt(ToGotoLoc, ToStarLoc,
4837                                                         ToTarget);
4838 }
4839 
4840 Stmt *ASTNodeImporter::VisitContinueStmt(ContinueStmt *S) {
4841   SourceLocation ToContinueLoc = Importer.Import(S->getContinueLoc());
4842   return new (Importer.getToContext()) ContinueStmt(ToContinueLoc);
4843 }
4844 
4845 Stmt *ASTNodeImporter::VisitBreakStmt(BreakStmt *S) {
4846   SourceLocation ToBreakLoc = Importer.Import(S->getBreakLoc());
4847   return new (Importer.getToContext()) BreakStmt(ToBreakLoc);
4848 }
4849 
4850 Stmt *ASTNodeImporter::VisitReturnStmt(ReturnStmt *S) {
4851   SourceLocation ToRetLoc = Importer.Import(S->getReturnLoc());
4852   Expr *ToRetExpr = Importer.Import(S->getRetValue());
4853   if (!ToRetExpr && S->getRetValue())
4854     return nullptr;
4855   VarDecl *NRVOCandidate = const_cast<VarDecl*>(S->getNRVOCandidate());
4856   VarDecl *ToNRVOCandidate = cast_or_null<VarDecl>(Importer.Import(NRVOCandidate));
4857   if (!ToNRVOCandidate && NRVOCandidate)
4858     return nullptr;
4859   return new (Importer.getToContext()) ReturnStmt(ToRetLoc, ToRetExpr,
4860                                                   ToNRVOCandidate);
4861 }
4862 
4863 Stmt *ASTNodeImporter::VisitCXXCatchStmt(CXXCatchStmt *S) {
4864   SourceLocation ToCatchLoc = Importer.Import(S->getCatchLoc());
4865   VarDecl *ToExceptionDecl = nullptr;
4866   if (VarDecl *FromExceptionDecl = S->getExceptionDecl()) {
4867     ToExceptionDecl =
4868       dyn_cast_or_null<VarDecl>(Importer.Import(FromExceptionDecl));
4869     if (!ToExceptionDecl)
4870       return nullptr;
4871   }
4872   Stmt *ToHandlerBlock = Importer.Import(S->getHandlerBlock());
4873   if (!ToHandlerBlock && S->getHandlerBlock())
4874     return nullptr;
4875   return new (Importer.getToContext()) CXXCatchStmt(ToCatchLoc,
4876                                                     ToExceptionDecl,
4877                                                     ToHandlerBlock);
4878 }
4879 
4880 Stmt *ASTNodeImporter::VisitCXXTryStmt(CXXTryStmt *S) {
4881   SourceLocation ToTryLoc = Importer.Import(S->getTryLoc());
4882   Stmt *ToTryBlock = Importer.Import(S->getTryBlock());
4883   if (!ToTryBlock && S->getTryBlock())
4884     return nullptr;
4885   SmallVector<Stmt *, 1> ToHandlers(S->getNumHandlers());
4886   for (unsigned HI = 0, HE = S->getNumHandlers(); HI != HE; ++HI) {
4887     CXXCatchStmt *FromHandler = S->getHandler(HI);
4888     if (Stmt *ToHandler = Importer.Import(FromHandler))
4889       ToHandlers[HI] = ToHandler;
4890     else
4891       return nullptr;
4892   }
4893   return CXXTryStmt::Create(Importer.getToContext(), ToTryLoc, ToTryBlock,
4894                             ToHandlers);
4895 }
4896 
4897 Stmt *ASTNodeImporter::VisitCXXForRangeStmt(CXXForRangeStmt *S) {
4898   DeclStmt *ToRange =
4899     dyn_cast_or_null<DeclStmt>(Importer.Import(S->getRangeStmt()));
4900   if (!ToRange && S->getRangeStmt())
4901     return nullptr;
4902   DeclStmt *ToBeginEnd =
4903     dyn_cast_or_null<DeclStmt>(Importer.Import(S->getBeginEndStmt()));
4904   if (!ToBeginEnd && S->getBeginEndStmt())
4905     return nullptr;
4906   Expr *ToCond = Importer.Import(S->getCond());
4907   if (!ToCond && S->getCond())
4908     return nullptr;
4909   Expr *ToInc = Importer.Import(S->getInc());
4910   if (!ToInc && S->getInc())
4911     return nullptr;
4912   DeclStmt *ToLoopVar =
4913     dyn_cast_or_null<DeclStmt>(Importer.Import(S->getLoopVarStmt()));
4914   if (!ToLoopVar && S->getLoopVarStmt())
4915     return nullptr;
4916   Stmt *ToBody = Importer.Import(S->getBody());
4917   if (!ToBody && S->getBody())
4918     return nullptr;
4919   SourceLocation ToForLoc = Importer.Import(S->getForLoc());
4920   SourceLocation ToColonLoc = Importer.Import(S->getColonLoc());
4921   SourceLocation ToRParenLoc = Importer.Import(S->getRParenLoc());
4922   return new (Importer.getToContext()) CXXForRangeStmt(ToRange, ToBeginEnd,
4923                                                        ToCond, ToInc,
4924                                                        ToLoopVar, ToBody,
4925                                                        ToForLoc, ToColonLoc,
4926                                                        ToRParenLoc);
4927 }
4928 
4929 Stmt *ASTNodeImporter::VisitObjCForCollectionStmt(ObjCForCollectionStmt *S) {
4930   Stmt *ToElem = Importer.Import(S->getElement());
4931   if (!ToElem && S->getElement())
4932     return nullptr;
4933   Expr *ToCollect = Importer.Import(S->getCollection());
4934   if (!ToCollect && S->getCollection())
4935     return nullptr;
4936   Stmt *ToBody = Importer.Import(S->getBody());
4937   if (!ToBody && S->getBody())
4938     return nullptr;
4939   SourceLocation ToForLoc = Importer.Import(S->getForLoc());
4940   SourceLocation ToRParenLoc = Importer.Import(S->getRParenLoc());
4941   return new (Importer.getToContext()) ObjCForCollectionStmt(ToElem,
4942                                                              ToCollect,
4943                                                              ToBody, ToForLoc,
4944                                                              ToRParenLoc);
4945 }
4946 
4947 Stmt *ASTNodeImporter::VisitObjCAtCatchStmt(ObjCAtCatchStmt *S) {
4948   SourceLocation ToAtCatchLoc = Importer.Import(S->getAtCatchLoc());
4949   SourceLocation ToRParenLoc = Importer.Import(S->getRParenLoc());
4950   VarDecl *ToExceptionDecl = nullptr;
4951   if (VarDecl *FromExceptionDecl = S->getCatchParamDecl()) {
4952     ToExceptionDecl =
4953       dyn_cast_or_null<VarDecl>(Importer.Import(FromExceptionDecl));
4954     if (!ToExceptionDecl)
4955       return nullptr;
4956   }
4957   Stmt *ToBody = Importer.Import(S->getCatchBody());
4958   if (!ToBody && S->getCatchBody())
4959     return nullptr;
4960   return new (Importer.getToContext()) ObjCAtCatchStmt(ToAtCatchLoc,
4961                                                        ToRParenLoc,
4962                                                        ToExceptionDecl,
4963                                                        ToBody);
4964 }
4965 
4966 Stmt *ASTNodeImporter::VisitObjCAtFinallyStmt(ObjCAtFinallyStmt *S) {
4967   SourceLocation ToAtFinallyLoc = Importer.Import(S->getAtFinallyLoc());
4968   Stmt *ToAtFinallyStmt = Importer.Import(S->getFinallyBody());
4969   if (!ToAtFinallyStmt && S->getFinallyBody())
4970     return nullptr;
4971   return new (Importer.getToContext()) ObjCAtFinallyStmt(ToAtFinallyLoc,
4972                                                          ToAtFinallyStmt);
4973 }
4974 
4975 Stmt *ASTNodeImporter::VisitObjCAtTryStmt(ObjCAtTryStmt *S) {
4976   SourceLocation ToAtTryLoc = Importer.Import(S->getAtTryLoc());
4977   Stmt *ToAtTryStmt = Importer.Import(S->getTryBody());
4978   if (!ToAtTryStmt && S->getTryBody())
4979     return nullptr;
4980   SmallVector<Stmt *, 1> ToCatchStmts(S->getNumCatchStmts());
4981   for (unsigned CI = 0, CE = S->getNumCatchStmts(); CI != CE; ++CI) {
4982     ObjCAtCatchStmt *FromCatchStmt = S->getCatchStmt(CI);
4983     if (Stmt *ToCatchStmt = Importer.Import(FromCatchStmt))
4984       ToCatchStmts[CI] = ToCatchStmt;
4985     else
4986       return nullptr;
4987   }
4988   Stmt *ToAtFinallyStmt = Importer.Import(S->getFinallyStmt());
4989   if (!ToAtFinallyStmt && S->getFinallyStmt())
4990     return nullptr;
4991   return ObjCAtTryStmt::Create(Importer.getToContext(),
4992                                ToAtTryLoc, ToAtTryStmt,
4993                                ToCatchStmts.begin(), ToCatchStmts.size(),
4994                                ToAtFinallyStmt);
4995 }
4996 
4997 Stmt *ASTNodeImporter::VisitObjCAtSynchronizedStmt
4998   (ObjCAtSynchronizedStmt *S) {
4999   SourceLocation ToAtSynchronizedLoc =
5000     Importer.Import(S->getAtSynchronizedLoc());
5001   Expr *ToSynchExpr = Importer.Import(S->getSynchExpr());
5002   if (!ToSynchExpr && S->getSynchExpr())
5003     return nullptr;
5004   Stmt *ToSynchBody = Importer.Import(S->getSynchBody());
5005   if (!ToSynchBody && S->getSynchBody())
5006     return nullptr;
5007   return new (Importer.getToContext()) ObjCAtSynchronizedStmt(
5008     ToAtSynchronizedLoc, ToSynchExpr, ToSynchBody);
5009 }
5010 
5011 Stmt *ASTNodeImporter::VisitObjCAtThrowStmt(ObjCAtThrowStmt *S) {
5012   SourceLocation ToAtThrowLoc = Importer.Import(S->getThrowLoc());
5013   Expr *ToThrow = Importer.Import(S->getThrowExpr());
5014   if (!ToThrow && S->getThrowExpr())
5015     return nullptr;
5016   return new (Importer.getToContext()) ObjCAtThrowStmt(ToAtThrowLoc, ToThrow);
5017 }
5018 
5019 Stmt *ASTNodeImporter::VisitObjCAutoreleasePoolStmt
5020   (ObjCAutoreleasePoolStmt *S) {
5021   SourceLocation ToAtLoc = Importer.Import(S->getAtLoc());
5022   Stmt *ToSubStmt = Importer.Import(S->getSubStmt());
5023   if (!ToSubStmt && S->getSubStmt())
5024     return nullptr;
5025   return new (Importer.getToContext()) ObjCAutoreleasePoolStmt(ToAtLoc,
5026                                                                ToSubStmt);
5027 }
5028 
5029 //----------------------------------------------------------------------------
5030 // Import Expressions
5031 //----------------------------------------------------------------------------
5032 Expr *ASTNodeImporter::VisitExpr(Expr *E) {
5033   Importer.FromDiag(E->getLocStart(), diag::err_unsupported_ast_node)
5034     << E->getStmtClassName();
5035   return nullptr;
5036 }
5037 
5038 Expr *ASTNodeImporter::VisitDeclRefExpr(DeclRefExpr *E) {
5039   ValueDecl *ToD = cast_or_null<ValueDecl>(Importer.Import(E->getDecl()));
5040   if (!ToD)
5041     return nullptr;
5042 
5043   NamedDecl *FoundD = nullptr;
5044   if (E->getDecl() != E->getFoundDecl()) {
5045     FoundD = cast_or_null<NamedDecl>(Importer.Import(E->getFoundDecl()));
5046     if (!FoundD)
5047       return nullptr;
5048   }
5049 
5050   QualType T = Importer.Import(E->getType());
5051   if (T.isNull())
5052     return nullptr;
5053 
5054   DeclRefExpr *DRE = DeclRefExpr::Create(Importer.getToContext(),
5055                                          Importer.Import(E->getQualifierLoc()),
5056                                    Importer.Import(E->getTemplateKeywordLoc()),
5057                                          ToD,
5058                                         E->refersToEnclosingVariableOrCapture(),
5059                                          Importer.Import(E->getLocation()),
5060                                          T, E->getValueKind(),
5061                                          FoundD,
5062                                          /*FIXME:TemplateArgs=*/nullptr);
5063   if (E->hadMultipleCandidates())
5064     DRE->setHadMultipleCandidates(true);
5065   return DRE;
5066 }
5067 
5068 Expr *ASTNodeImporter::VisitIntegerLiteral(IntegerLiteral *E) {
5069   QualType T = Importer.Import(E->getType());
5070   if (T.isNull())
5071     return nullptr;
5072 
5073   return IntegerLiteral::Create(Importer.getToContext(),
5074                                 E->getValue(), T,
5075                                 Importer.Import(E->getLocation()));
5076 }
5077 
5078 Expr *ASTNodeImporter::VisitCharacterLiteral(CharacterLiteral *E) {
5079   QualType T = Importer.Import(E->getType());
5080   if (T.isNull())
5081     return nullptr;
5082 
5083   return new (Importer.getToContext()) CharacterLiteral(E->getValue(),
5084                                                         E->getKind(), T,
5085                                           Importer.Import(E->getLocation()));
5086 }
5087 
5088 Expr *ASTNodeImporter::VisitParenExpr(ParenExpr *E) {
5089   Expr *SubExpr = Importer.Import(E->getSubExpr());
5090   if (!SubExpr)
5091     return nullptr;
5092 
5093   return new (Importer.getToContext())
5094                                   ParenExpr(Importer.Import(E->getLParen()),
5095                                             Importer.Import(E->getRParen()),
5096                                             SubExpr);
5097 }
5098 
5099 Expr *ASTNodeImporter::VisitUnaryOperator(UnaryOperator *E) {
5100   QualType T = Importer.Import(E->getType());
5101   if (T.isNull())
5102     return nullptr;
5103 
5104   Expr *SubExpr = Importer.Import(E->getSubExpr());
5105   if (!SubExpr)
5106     return nullptr;
5107 
5108   return new (Importer.getToContext()) UnaryOperator(SubExpr, E->getOpcode(),
5109                                                      T, E->getValueKind(),
5110                                                      E->getObjectKind(),
5111                                          Importer.Import(E->getOperatorLoc()));
5112 }
5113 
5114 Expr *ASTNodeImporter::VisitUnaryExprOrTypeTraitExpr(
5115                                             UnaryExprOrTypeTraitExpr *E) {
5116   QualType ResultType = Importer.Import(E->getType());
5117 
5118   if (E->isArgumentType()) {
5119     TypeSourceInfo *TInfo = Importer.Import(E->getArgumentTypeInfo());
5120     if (!TInfo)
5121       return nullptr;
5122 
5123     return new (Importer.getToContext()) UnaryExprOrTypeTraitExpr(E->getKind(),
5124                                            TInfo, ResultType,
5125                                            Importer.Import(E->getOperatorLoc()),
5126                                            Importer.Import(E->getRParenLoc()));
5127   }
5128 
5129   Expr *SubExpr = Importer.Import(E->getArgumentExpr());
5130   if (!SubExpr)
5131     return nullptr;
5132 
5133   return new (Importer.getToContext()) UnaryExprOrTypeTraitExpr(E->getKind(),
5134                                           SubExpr, ResultType,
5135                                           Importer.Import(E->getOperatorLoc()),
5136                                           Importer.Import(E->getRParenLoc()));
5137 }
5138 
5139 Expr *ASTNodeImporter::VisitBinaryOperator(BinaryOperator *E) {
5140   QualType T = Importer.Import(E->getType());
5141   if (T.isNull())
5142     return nullptr;
5143 
5144   Expr *LHS = Importer.Import(E->getLHS());
5145   if (!LHS)
5146     return nullptr;
5147 
5148   Expr *RHS = Importer.Import(E->getRHS());
5149   if (!RHS)
5150     return nullptr;
5151 
5152   return new (Importer.getToContext()) BinaryOperator(LHS, RHS, E->getOpcode(),
5153                                                       T, E->getValueKind(),
5154                                                       E->getObjectKind(),
5155                                            Importer.Import(E->getOperatorLoc()),
5156                                                       E->isFPContractable());
5157 }
5158 
5159 Expr *ASTNodeImporter::VisitCompoundAssignOperator(CompoundAssignOperator *E) {
5160   QualType T = Importer.Import(E->getType());
5161   if (T.isNull())
5162     return nullptr;
5163 
5164   QualType CompLHSType = Importer.Import(E->getComputationLHSType());
5165   if (CompLHSType.isNull())
5166     return nullptr;
5167 
5168   QualType CompResultType = Importer.Import(E->getComputationResultType());
5169   if (CompResultType.isNull())
5170     return nullptr;
5171 
5172   Expr *LHS = Importer.Import(E->getLHS());
5173   if (!LHS)
5174     return nullptr;
5175 
5176   Expr *RHS = Importer.Import(E->getRHS());
5177   if (!RHS)
5178     return nullptr;
5179 
5180   return new (Importer.getToContext())
5181                         CompoundAssignOperator(LHS, RHS, E->getOpcode(),
5182                                                T, E->getValueKind(),
5183                                                E->getObjectKind(),
5184                                                CompLHSType, CompResultType,
5185                                            Importer.Import(E->getOperatorLoc()),
5186                                                E->isFPContractable());
5187 }
5188 
5189 static bool ImportCastPath(CastExpr *E, CXXCastPath &Path) {
5190   if (E->path_empty()) return false;
5191 
5192   // TODO: import cast paths
5193   return true;
5194 }
5195 
5196 Expr *ASTNodeImporter::VisitImplicitCastExpr(ImplicitCastExpr *E) {
5197   QualType T = Importer.Import(E->getType());
5198   if (T.isNull())
5199     return nullptr;
5200 
5201   Expr *SubExpr = Importer.Import(E->getSubExpr());
5202   if (!SubExpr)
5203     return nullptr;
5204 
5205   CXXCastPath BasePath;
5206   if (ImportCastPath(E, BasePath))
5207     return nullptr;
5208 
5209   return ImplicitCastExpr::Create(Importer.getToContext(), T, E->getCastKind(),
5210                                   SubExpr, &BasePath, E->getValueKind());
5211 }
5212 
5213 Expr *ASTNodeImporter::VisitCStyleCastExpr(CStyleCastExpr *E) {
5214   QualType T = Importer.Import(E->getType());
5215   if (T.isNull())
5216     return nullptr;
5217 
5218   Expr *SubExpr = Importer.Import(E->getSubExpr());
5219   if (!SubExpr)
5220     return nullptr;
5221 
5222   TypeSourceInfo *TInfo = Importer.Import(E->getTypeInfoAsWritten());
5223   if (!TInfo && E->getTypeInfoAsWritten())
5224     return nullptr;
5225 
5226   CXXCastPath BasePath;
5227   if (ImportCastPath(E, BasePath))
5228     return nullptr;
5229 
5230   return CStyleCastExpr::Create(Importer.getToContext(), T,
5231                                 E->getValueKind(), E->getCastKind(),
5232                                 SubExpr, &BasePath, TInfo,
5233                                 Importer.Import(E->getLParenLoc()),
5234                                 Importer.Import(E->getRParenLoc()));
5235 }
5236 
5237 Expr *ASTNodeImporter::VisitCXXConstructExpr(CXXConstructExpr *E) {
5238   QualType T = Importer.Import(E->getType());
5239   if (T.isNull())
5240     return nullptr;
5241 
5242   CXXConstructorDecl *ToCCD =
5243     dyn_cast<CXXConstructorDecl>(Importer.Import(E->getConstructor()));
5244   if (!ToCCD && E->getConstructor())
5245     return nullptr;
5246 
5247   size_t NumArgs = E->getNumArgs();
5248   SmallVector<Expr *, 1> ToArgs(NumArgs);
5249   ASTImporter &_Importer = Importer;
5250   std::transform(E->arg_begin(), E->arg_end(), ToArgs.begin(),
5251     [&_Importer](Expr *AE) -> Expr * {
5252       return _Importer.Import(AE);
5253     });
5254   for (Expr *ToA : ToArgs) {
5255     if (!ToA)
5256       return nullptr;
5257   }
5258 
5259   return CXXConstructExpr::Create(Importer.getToContext(), T,
5260                                   Importer.Import(E->getLocation()),
5261                                   ToCCD, E->isElidable(),
5262                                   ToArgs, E->hadMultipleCandidates(),
5263                                   E->isListInitialization(),
5264                                   E->isStdInitListInitialization(),
5265                                   E->requiresZeroInitialization(),
5266                                   E->getConstructionKind(),
5267                                   Importer.Import(E->getParenOrBraceRange()));
5268 }
5269 
5270 Expr *ASTNodeImporter::VisitMemberExpr(MemberExpr *E) {
5271   QualType T = Importer.Import(E->getType());
5272   if (T.isNull())
5273     return nullptr;
5274 
5275   Expr *ToBase = Importer.Import(E->getBase());
5276   if (!ToBase && E->getBase())
5277     return nullptr;
5278 
5279   ValueDecl *ToMember = dyn_cast<ValueDecl>(Importer.Import(E->getMemberDecl()));
5280   if (!ToMember && E->getMemberDecl())
5281     return nullptr;
5282 
5283   DeclAccessPair ToFoundDecl = DeclAccessPair::make(
5284     dyn_cast<NamedDecl>(Importer.Import(E->getFoundDecl().getDecl())),
5285     E->getFoundDecl().getAccess());
5286 
5287   DeclarationNameInfo ToMemberNameInfo(
5288     Importer.Import(E->getMemberNameInfo().getName()),
5289     Importer.Import(E->getMemberNameInfo().getLoc()));
5290 
5291   if (E->hasExplicitTemplateArgs()) {
5292     return nullptr; // FIXME: handle template arguments
5293   }
5294 
5295   return MemberExpr::Create(Importer.getToContext(), ToBase,
5296                             E->isArrow(),
5297                             Importer.Import(E->getOperatorLoc()),
5298                             Importer.Import(E->getQualifierLoc()),
5299                             Importer.Import(E->getTemplateKeywordLoc()),
5300                             ToMember, ToFoundDecl, ToMemberNameInfo,
5301                             nullptr, T, E->getValueKind(),
5302                             E->getObjectKind());
5303 }
5304 
5305 Expr *ASTNodeImporter::VisitCallExpr(CallExpr *E) {
5306   QualType T = Importer.Import(E->getType());
5307   if (T.isNull())
5308     return nullptr;
5309 
5310   Expr *ToCallee = Importer.Import(E->getCallee());
5311   if (!ToCallee && E->getCallee())
5312     return nullptr;
5313 
5314   unsigned NumArgs = E->getNumArgs();
5315 
5316   llvm::SmallVector<Expr *, 2> ToArgs(NumArgs);
5317 
5318   for (unsigned ai = 0, ae = NumArgs; ai != ae; ++ai) {
5319     Expr *FromArg = E->getArg(ai);
5320     Expr *ToArg = Importer.Import(FromArg);
5321     if (!ToArg)
5322       return nullptr;
5323     ToArgs[ai] = ToArg;
5324   }
5325 
5326   Expr **ToArgs_Copied = new (Importer.getToContext())
5327     Expr*[NumArgs];
5328 
5329   for (unsigned ai = 0, ae = NumArgs; ai != ae; ++ai)
5330     ToArgs_Copied[ai] = ToArgs[ai];
5331 
5332   return new (Importer.getToContext())
5333     CallExpr(Importer.getToContext(), ToCallee,
5334              ArrayRef<Expr*>(ToArgs_Copied, NumArgs), T, E->getValueKind(),
5335              Importer.Import(E->getRParenLoc()));
5336 }
5337 
5338 ASTImporter::ASTImporter(ASTContext &ToContext, FileManager &ToFileManager,
5339                          ASTContext &FromContext, FileManager &FromFileManager,
5340                          bool MinimalImport)
5341   : ToContext(ToContext), FromContext(FromContext),
5342     ToFileManager(ToFileManager), FromFileManager(FromFileManager),
5343     Minimal(MinimalImport), LastDiagFromFrom(false)
5344 {
5345   ImportedDecls[FromContext.getTranslationUnitDecl()]
5346     = ToContext.getTranslationUnitDecl();
5347 }
5348 
5349 ASTImporter::~ASTImporter() { }
5350 
5351 QualType ASTImporter::Import(QualType FromT) {
5352   if (FromT.isNull())
5353     return QualType();
5354 
5355   const Type *fromTy = FromT.getTypePtr();
5356 
5357   // Check whether we've already imported this type.
5358   llvm::DenseMap<const Type *, const Type *>::iterator Pos
5359     = ImportedTypes.find(fromTy);
5360   if (Pos != ImportedTypes.end())
5361     return ToContext.getQualifiedType(Pos->second, FromT.getLocalQualifiers());
5362 
5363   // Import the type
5364   ASTNodeImporter Importer(*this);
5365   QualType ToT = Importer.Visit(fromTy);
5366   if (ToT.isNull())
5367     return ToT;
5368 
5369   // Record the imported type.
5370   ImportedTypes[fromTy] = ToT.getTypePtr();
5371 
5372   return ToContext.getQualifiedType(ToT, FromT.getLocalQualifiers());
5373 }
5374 
5375 TypeSourceInfo *ASTImporter::Import(TypeSourceInfo *FromTSI) {
5376   if (!FromTSI)
5377     return FromTSI;
5378 
5379   // FIXME: For now we just create a "trivial" type source info based
5380   // on the type and a single location. Implement a real version of this.
5381   QualType T = Import(FromTSI->getType());
5382   if (T.isNull())
5383     return nullptr;
5384 
5385   return ToContext.getTrivialTypeSourceInfo(T,
5386            Import(FromTSI->getTypeLoc().getLocStart()));
5387 }
5388 
5389 Decl *ASTImporter::GetAlreadyImportedOrNull(Decl *FromD) {
5390   llvm::DenseMap<Decl *, Decl *>::iterator Pos = ImportedDecls.find(FromD);
5391   if (Pos != ImportedDecls.end()) {
5392     Decl *ToD = Pos->second;
5393     ASTNodeImporter(*this).ImportDefinitionIfNeeded(FromD, ToD);
5394     return ToD;
5395   } else {
5396     return nullptr;
5397   }
5398 }
5399 
5400 Decl *ASTImporter::Import(Decl *FromD) {
5401   if (!FromD)
5402     return nullptr;
5403 
5404   ASTNodeImporter Importer(*this);
5405 
5406   // Check whether we've already imported this declaration.
5407   llvm::DenseMap<Decl *, Decl *>::iterator Pos = ImportedDecls.find(FromD);
5408   if (Pos != ImportedDecls.end()) {
5409     Decl *ToD = Pos->second;
5410     Importer.ImportDefinitionIfNeeded(FromD, ToD);
5411     return ToD;
5412   }
5413 
5414   // Import the type
5415   Decl *ToD = Importer.Visit(FromD);
5416   if (!ToD)
5417     return nullptr;
5418 
5419   // Record the imported declaration.
5420   ImportedDecls[FromD] = ToD;
5421 
5422   if (TagDecl *FromTag = dyn_cast<TagDecl>(FromD)) {
5423     // Keep track of anonymous tags that have an associated typedef.
5424     if (FromTag->getTypedefNameForAnonDecl())
5425       AnonTagsWithPendingTypedefs.push_back(FromTag);
5426   } else if (TypedefNameDecl *FromTypedef = dyn_cast<TypedefNameDecl>(FromD)) {
5427     // When we've finished transforming a typedef, see whether it was the
5428     // typedef for an anonymous tag.
5429     for (SmallVectorImpl<TagDecl *>::iterator
5430                FromTag = AnonTagsWithPendingTypedefs.begin(),
5431             FromTagEnd = AnonTagsWithPendingTypedefs.end();
5432          FromTag != FromTagEnd; ++FromTag) {
5433       if ((*FromTag)->getTypedefNameForAnonDecl() == FromTypedef) {
5434         if (TagDecl *ToTag = cast_or_null<TagDecl>(Import(*FromTag))) {
5435           // We found the typedef for an anonymous tag; link them.
5436           ToTag->setTypedefNameForAnonDecl(cast<TypedefNameDecl>(ToD));
5437           AnonTagsWithPendingTypedefs.erase(FromTag);
5438           break;
5439         }
5440       }
5441     }
5442   }
5443 
5444   return ToD;
5445 }
5446 
5447 DeclContext *ASTImporter::ImportContext(DeclContext *FromDC) {
5448   if (!FromDC)
5449     return FromDC;
5450 
5451   DeclContext *ToDC = cast_or_null<DeclContext>(Import(cast<Decl>(FromDC)));
5452   if (!ToDC)
5453     return nullptr;
5454 
5455   // When we're using a record/enum/Objective-C class/protocol as a context, we
5456   // need it to have a definition.
5457   if (RecordDecl *ToRecord = dyn_cast<RecordDecl>(ToDC)) {
5458     RecordDecl *FromRecord = cast<RecordDecl>(FromDC);
5459     if (ToRecord->isCompleteDefinition()) {
5460       // Do nothing.
5461     } else if (FromRecord->isCompleteDefinition()) {
5462       ASTNodeImporter(*this).ImportDefinition(FromRecord, ToRecord,
5463                                               ASTNodeImporter::IDK_Basic);
5464     } else {
5465       CompleteDecl(ToRecord);
5466     }
5467   } else if (EnumDecl *ToEnum = dyn_cast<EnumDecl>(ToDC)) {
5468     EnumDecl *FromEnum = cast<EnumDecl>(FromDC);
5469     if (ToEnum->isCompleteDefinition()) {
5470       // Do nothing.
5471     } else if (FromEnum->isCompleteDefinition()) {
5472       ASTNodeImporter(*this).ImportDefinition(FromEnum, ToEnum,
5473                                               ASTNodeImporter::IDK_Basic);
5474     } else {
5475       CompleteDecl(ToEnum);
5476     }
5477   } else if (ObjCInterfaceDecl *ToClass = dyn_cast<ObjCInterfaceDecl>(ToDC)) {
5478     ObjCInterfaceDecl *FromClass = cast<ObjCInterfaceDecl>(FromDC);
5479     if (ToClass->getDefinition()) {
5480       // Do nothing.
5481     } else if (ObjCInterfaceDecl *FromDef = FromClass->getDefinition()) {
5482       ASTNodeImporter(*this).ImportDefinition(FromDef, ToClass,
5483                                               ASTNodeImporter::IDK_Basic);
5484     } else {
5485       CompleteDecl(ToClass);
5486     }
5487   } else if (ObjCProtocolDecl *ToProto = dyn_cast<ObjCProtocolDecl>(ToDC)) {
5488     ObjCProtocolDecl *FromProto = cast<ObjCProtocolDecl>(FromDC);
5489     if (ToProto->getDefinition()) {
5490       // Do nothing.
5491     } else if (ObjCProtocolDecl *FromDef = FromProto->getDefinition()) {
5492       ASTNodeImporter(*this).ImportDefinition(FromDef, ToProto,
5493                                               ASTNodeImporter::IDK_Basic);
5494     } else {
5495       CompleteDecl(ToProto);
5496     }
5497   }
5498 
5499   return ToDC;
5500 }
5501 
5502 Expr *ASTImporter::Import(Expr *FromE) {
5503   if (!FromE)
5504     return nullptr;
5505 
5506   return cast_or_null<Expr>(Import(cast<Stmt>(FromE)));
5507 }
5508 
5509 Stmt *ASTImporter::Import(Stmt *FromS) {
5510   if (!FromS)
5511     return nullptr;
5512 
5513   // Check whether we've already imported this declaration.
5514   llvm::DenseMap<Stmt *, Stmt *>::iterator Pos = ImportedStmts.find(FromS);
5515   if (Pos != ImportedStmts.end())
5516     return Pos->second;
5517 
5518   // Import the type
5519   ASTNodeImporter Importer(*this);
5520   Stmt *ToS = Importer.Visit(FromS);
5521   if (!ToS)
5522     return nullptr;
5523 
5524   // Record the imported declaration.
5525   ImportedStmts[FromS] = ToS;
5526   return ToS;
5527 }
5528 
5529 NestedNameSpecifier *ASTImporter::Import(NestedNameSpecifier *FromNNS) {
5530   if (!FromNNS)
5531     return nullptr;
5532 
5533   NestedNameSpecifier *prefix = Import(FromNNS->getPrefix());
5534 
5535   switch (FromNNS->getKind()) {
5536   case NestedNameSpecifier::Identifier:
5537     if (IdentifierInfo *II = Import(FromNNS->getAsIdentifier())) {
5538       return NestedNameSpecifier::Create(ToContext, prefix, II);
5539     }
5540     return nullptr;
5541 
5542   case NestedNameSpecifier::Namespace:
5543     if (NamespaceDecl *NS =
5544           cast<NamespaceDecl>(Import(FromNNS->getAsNamespace()))) {
5545       return NestedNameSpecifier::Create(ToContext, prefix, NS);
5546     }
5547     return nullptr;
5548 
5549   case NestedNameSpecifier::NamespaceAlias:
5550     if (NamespaceAliasDecl *NSAD =
5551           cast<NamespaceAliasDecl>(Import(FromNNS->getAsNamespaceAlias()))) {
5552       return NestedNameSpecifier::Create(ToContext, prefix, NSAD);
5553     }
5554     return nullptr;
5555 
5556   case NestedNameSpecifier::Global:
5557     return NestedNameSpecifier::GlobalSpecifier(ToContext);
5558 
5559   case NestedNameSpecifier::Super:
5560     if (CXXRecordDecl *RD =
5561             cast<CXXRecordDecl>(Import(FromNNS->getAsRecordDecl()))) {
5562       return NestedNameSpecifier::SuperSpecifier(ToContext, RD);
5563     }
5564     return nullptr;
5565 
5566   case NestedNameSpecifier::TypeSpec:
5567   case NestedNameSpecifier::TypeSpecWithTemplate: {
5568       QualType T = Import(QualType(FromNNS->getAsType(), 0u));
5569       if (!T.isNull()) {
5570         bool bTemplate = FromNNS->getKind() ==
5571                          NestedNameSpecifier::TypeSpecWithTemplate;
5572         return NestedNameSpecifier::Create(ToContext, prefix,
5573                                            bTemplate, T.getTypePtr());
5574       }
5575     }
5576       return nullptr;
5577   }
5578 
5579   llvm_unreachable("Invalid nested name specifier kind");
5580 }
5581 
5582 NestedNameSpecifierLoc ASTImporter::Import(NestedNameSpecifierLoc FromNNS) {
5583   // FIXME: Implement!
5584   return NestedNameSpecifierLoc();
5585 }
5586 
5587 TemplateName ASTImporter::Import(TemplateName From) {
5588   switch (From.getKind()) {
5589   case TemplateName::Template:
5590     if (TemplateDecl *ToTemplate
5591                 = cast_or_null<TemplateDecl>(Import(From.getAsTemplateDecl())))
5592       return TemplateName(ToTemplate);
5593 
5594     return TemplateName();
5595 
5596   case TemplateName::OverloadedTemplate: {
5597     OverloadedTemplateStorage *FromStorage = From.getAsOverloadedTemplate();
5598     UnresolvedSet<2> ToTemplates;
5599     for (OverloadedTemplateStorage::iterator I = FromStorage->begin(),
5600                                              E = FromStorage->end();
5601          I != E; ++I) {
5602       if (NamedDecl *To = cast_or_null<NamedDecl>(Import(*I)))
5603         ToTemplates.addDecl(To);
5604       else
5605         return TemplateName();
5606     }
5607     return ToContext.getOverloadedTemplateName(ToTemplates.begin(),
5608                                                ToTemplates.end());
5609   }
5610 
5611   case TemplateName::QualifiedTemplate: {
5612     QualifiedTemplateName *QTN = From.getAsQualifiedTemplateName();
5613     NestedNameSpecifier *Qualifier = Import(QTN->getQualifier());
5614     if (!Qualifier)
5615       return TemplateName();
5616 
5617     if (TemplateDecl *ToTemplate
5618         = cast_or_null<TemplateDecl>(Import(From.getAsTemplateDecl())))
5619       return ToContext.getQualifiedTemplateName(Qualifier,
5620                                                 QTN->hasTemplateKeyword(),
5621                                                 ToTemplate);
5622 
5623     return TemplateName();
5624   }
5625 
5626   case TemplateName::DependentTemplate: {
5627     DependentTemplateName *DTN = From.getAsDependentTemplateName();
5628     NestedNameSpecifier *Qualifier = Import(DTN->getQualifier());
5629     if (!Qualifier)
5630       return TemplateName();
5631 
5632     if (DTN->isIdentifier()) {
5633       return ToContext.getDependentTemplateName(Qualifier,
5634                                                 Import(DTN->getIdentifier()));
5635     }
5636 
5637     return ToContext.getDependentTemplateName(Qualifier, DTN->getOperator());
5638   }
5639 
5640   case TemplateName::SubstTemplateTemplateParm: {
5641     SubstTemplateTemplateParmStorage *subst
5642       = From.getAsSubstTemplateTemplateParm();
5643     TemplateTemplateParmDecl *param
5644       = cast_or_null<TemplateTemplateParmDecl>(Import(subst->getParameter()));
5645     if (!param)
5646       return TemplateName();
5647 
5648     TemplateName replacement = Import(subst->getReplacement());
5649     if (replacement.isNull()) return TemplateName();
5650 
5651     return ToContext.getSubstTemplateTemplateParm(param, replacement);
5652   }
5653 
5654   case TemplateName::SubstTemplateTemplateParmPack: {
5655     SubstTemplateTemplateParmPackStorage *SubstPack
5656       = From.getAsSubstTemplateTemplateParmPack();
5657     TemplateTemplateParmDecl *Param
5658       = cast_or_null<TemplateTemplateParmDecl>(
5659                                         Import(SubstPack->getParameterPack()));
5660     if (!Param)
5661       return TemplateName();
5662 
5663     ASTNodeImporter Importer(*this);
5664     TemplateArgument ArgPack
5665       = Importer.ImportTemplateArgument(SubstPack->getArgumentPack());
5666     if (ArgPack.isNull())
5667       return TemplateName();
5668 
5669     return ToContext.getSubstTemplateTemplateParmPack(Param, ArgPack);
5670   }
5671   }
5672 
5673   llvm_unreachable("Invalid template name kind");
5674 }
5675 
5676 SourceLocation ASTImporter::Import(SourceLocation FromLoc) {
5677   if (FromLoc.isInvalid())
5678     return SourceLocation();
5679 
5680   SourceManager &FromSM = FromContext.getSourceManager();
5681 
5682   // For now, map everything down to its spelling location, so that we
5683   // don't have to import macro expansions.
5684   // FIXME: Import macro expansions!
5685   FromLoc = FromSM.getSpellingLoc(FromLoc);
5686   std::pair<FileID, unsigned> Decomposed = FromSM.getDecomposedLoc(FromLoc);
5687   SourceManager &ToSM = ToContext.getSourceManager();
5688   FileID ToFileID = Import(Decomposed.first);
5689   if (ToFileID.isInvalid())
5690     return SourceLocation();
5691   SourceLocation ret = ToSM.getLocForStartOfFile(ToFileID)
5692                            .getLocWithOffset(Decomposed.second);
5693   return ret;
5694 }
5695 
5696 SourceRange ASTImporter::Import(SourceRange FromRange) {
5697   return SourceRange(Import(FromRange.getBegin()), Import(FromRange.getEnd()));
5698 }
5699 
5700 FileID ASTImporter::Import(FileID FromID) {
5701   llvm::DenseMap<FileID, FileID>::iterator Pos
5702     = ImportedFileIDs.find(FromID);
5703   if (Pos != ImportedFileIDs.end())
5704     return Pos->second;
5705 
5706   SourceManager &FromSM = FromContext.getSourceManager();
5707   SourceManager &ToSM = ToContext.getSourceManager();
5708   const SrcMgr::SLocEntry &FromSLoc = FromSM.getSLocEntry(FromID);
5709   assert(FromSLoc.isFile() && "Cannot handle macro expansions yet");
5710 
5711   // Include location of this file.
5712   SourceLocation ToIncludeLoc = Import(FromSLoc.getFile().getIncludeLoc());
5713 
5714   // Map the FileID for to the "to" source manager.
5715   FileID ToID;
5716   const SrcMgr::ContentCache *Cache = FromSLoc.getFile().getContentCache();
5717   if (Cache->OrigEntry && Cache->OrigEntry->getDir()) {
5718     // FIXME: We probably want to use getVirtualFile(), so we don't hit the
5719     // disk again
5720     // FIXME: We definitely want to re-use the existing MemoryBuffer, rather
5721     // than mmap the files several times.
5722     const FileEntry *Entry = ToFileManager.getFile(Cache->OrigEntry->getName());
5723     if (!Entry)
5724       return FileID();
5725     ToID = ToSM.createFileID(Entry, ToIncludeLoc,
5726                              FromSLoc.getFile().getFileCharacteristic());
5727   } else {
5728     // FIXME: We want to re-use the existing MemoryBuffer!
5729     const llvm::MemoryBuffer *
5730         FromBuf = Cache->getBuffer(FromContext.getDiagnostics(), FromSM);
5731     std::unique_ptr<llvm::MemoryBuffer> ToBuf
5732       = llvm::MemoryBuffer::getMemBufferCopy(FromBuf->getBuffer(),
5733                                              FromBuf->getBufferIdentifier());
5734     ToID = ToSM.createFileID(std::move(ToBuf),
5735                              FromSLoc.getFile().getFileCharacteristic());
5736   }
5737 
5738 
5739   ImportedFileIDs[FromID] = ToID;
5740   return ToID;
5741 }
5742 
5743 void ASTImporter::ImportDefinition(Decl *From) {
5744   Decl *To = Import(From);
5745   if (!To)
5746     return;
5747 
5748   if (DeclContext *FromDC = cast<DeclContext>(From)) {
5749     ASTNodeImporter Importer(*this);
5750 
5751     if (RecordDecl *ToRecord = dyn_cast<RecordDecl>(To)) {
5752       if (!ToRecord->getDefinition()) {
5753         Importer.ImportDefinition(cast<RecordDecl>(FromDC), ToRecord,
5754                                   ASTNodeImporter::IDK_Everything);
5755         return;
5756       }
5757     }
5758 
5759     if (EnumDecl *ToEnum = dyn_cast<EnumDecl>(To)) {
5760       if (!ToEnum->getDefinition()) {
5761         Importer.ImportDefinition(cast<EnumDecl>(FromDC), ToEnum,
5762                                   ASTNodeImporter::IDK_Everything);
5763         return;
5764       }
5765     }
5766 
5767     if (ObjCInterfaceDecl *ToIFace = dyn_cast<ObjCInterfaceDecl>(To)) {
5768       if (!ToIFace->getDefinition()) {
5769         Importer.ImportDefinition(cast<ObjCInterfaceDecl>(FromDC), ToIFace,
5770                                   ASTNodeImporter::IDK_Everything);
5771         return;
5772       }
5773     }
5774 
5775     if (ObjCProtocolDecl *ToProto = dyn_cast<ObjCProtocolDecl>(To)) {
5776       if (!ToProto->getDefinition()) {
5777         Importer.ImportDefinition(cast<ObjCProtocolDecl>(FromDC), ToProto,
5778                                   ASTNodeImporter::IDK_Everything);
5779         return;
5780       }
5781     }
5782 
5783     Importer.ImportDeclContext(FromDC, true);
5784   }
5785 }
5786 
5787 DeclarationName ASTImporter::Import(DeclarationName FromName) {
5788   if (!FromName)
5789     return DeclarationName();
5790 
5791   switch (FromName.getNameKind()) {
5792   case DeclarationName::Identifier:
5793     return Import(FromName.getAsIdentifierInfo());
5794 
5795   case DeclarationName::ObjCZeroArgSelector:
5796   case DeclarationName::ObjCOneArgSelector:
5797   case DeclarationName::ObjCMultiArgSelector:
5798     return Import(FromName.getObjCSelector());
5799 
5800   case DeclarationName::CXXConstructorName: {
5801     QualType T = Import(FromName.getCXXNameType());
5802     if (T.isNull())
5803       return DeclarationName();
5804 
5805     return ToContext.DeclarationNames.getCXXConstructorName(
5806                                                ToContext.getCanonicalType(T));
5807   }
5808 
5809   case DeclarationName::CXXDestructorName: {
5810     QualType T = Import(FromName.getCXXNameType());
5811     if (T.isNull())
5812       return DeclarationName();
5813 
5814     return ToContext.DeclarationNames.getCXXDestructorName(
5815                                                ToContext.getCanonicalType(T));
5816   }
5817 
5818   case DeclarationName::CXXConversionFunctionName: {
5819     QualType T = Import(FromName.getCXXNameType());
5820     if (T.isNull())
5821       return DeclarationName();
5822 
5823     return ToContext.DeclarationNames.getCXXConversionFunctionName(
5824                                                ToContext.getCanonicalType(T));
5825   }
5826 
5827   case DeclarationName::CXXOperatorName:
5828     return ToContext.DeclarationNames.getCXXOperatorName(
5829                                           FromName.getCXXOverloadedOperator());
5830 
5831   case DeclarationName::CXXLiteralOperatorName:
5832     return ToContext.DeclarationNames.getCXXLiteralOperatorName(
5833                                    Import(FromName.getCXXLiteralIdentifier()));
5834 
5835   case DeclarationName::CXXUsingDirective:
5836     // FIXME: STATICS!
5837     return DeclarationName::getUsingDirectiveName();
5838   }
5839 
5840   llvm_unreachable("Invalid DeclarationName Kind!");
5841 }
5842 
5843 IdentifierInfo *ASTImporter::Import(const IdentifierInfo *FromId) {
5844   if (!FromId)
5845     return nullptr;
5846 
5847   return &ToContext.Idents.get(FromId->getName());
5848 }
5849 
5850 Selector ASTImporter::Import(Selector FromSel) {
5851   if (FromSel.isNull())
5852     return Selector();
5853 
5854   SmallVector<IdentifierInfo *, 4> Idents;
5855   Idents.push_back(Import(FromSel.getIdentifierInfoForSlot(0)));
5856   for (unsigned I = 1, N = FromSel.getNumArgs(); I < N; ++I)
5857     Idents.push_back(Import(FromSel.getIdentifierInfoForSlot(I)));
5858   return ToContext.Selectors.getSelector(FromSel.getNumArgs(), Idents.data());
5859 }
5860 
5861 DeclarationName ASTImporter::HandleNameConflict(DeclarationName Name,
5862                                                 DeclContext *DC,
5863                                                 unsigned IDNS,
5864                                                 NamedDecl **Decls,
5865                                                 unsigned NumDecls) {
5866   return Name;
5867 }
5868 
5869 DiagnosticBuilder ASTImporter::ToDiag(SourceLocation Loc, unsigned DiagID) {
5870   if (LastDiagFromFrom)
5871     ToContext.getDiagnostics().notePriorDiagnosticFrom(
5872       FromContext.getDiagnostics());
5873   LastDiagFromFrom = false;
5874   return ToContext.getDiagnostics().Report(Loc, DiagID);
5875 }
5876 
5877 DiagnosticBuilder ASTImporter::FromDiag(SourceLocation Loc, unsigned DiagID) {
5878   if (!LastDiagFromFrom)
5879     FromContext.getDiagnostics().notePriorDiagnosticFrom(
5880       ToContext.getDiagnostics());
5881   LastDiagFromFrom = true;
5882   return FromContext.getDiagnostics().Report(Loc, DiagID);
5883 }
5884 
5885 void ASTImporter::CompleteDecl (Decl *D) {
5886   if (ObjCInterfaceDecl *ID = dyn_cast<ObjCInterfaceDecl>(D)) {
5887     if (!ID->getDefinition())
5888       ID->startDefinition();
5889   }
5890   else if (ObjCProtocolDecl *PD = dyn_cast<ObjCProtocolDecl>(D)) {
5891     if (!PD->getDefinition())
5892       PD->startDefinition();
5893   }
5894   else if (TagDecl *TD = dyn_cast<TagDecl>(D)) {
5895     if (!TD->getDefinition() && !TD->isBeingDefined()) {
5896       TD->startDefinition();
5897       TD->setCompleteDefinition(true);
5898     }
5899   }
5900   else {
5901     assert (0 && "CompleteDecl called on a Decl that can't be completed");
5902   }
5903 }
5904 
5905 Decl *ASTImporter::Imported(Decl *From, Decl *To) {
5906   ImportedDecls[From] = To;
5907   return To;
5908 }
5909 
5910 bool ASTImporter::IsStructurallyEquivalent(QualType From, QualType To,
5911                                            bool Complain) {
5912   llvm::DenseMap<const Type *, const Type *>::iterator Pos
5913    = ImportedTypes.find(From.getTypePtr());
5914   if (Pos != ImportedTypes.end() && ToContext.hasSameType(Import(From), To))
5915     return true;
5916 
5917   StructuralEquivalenceContext Ctx(FromContext, ToContext, NonEquivalentDecls,
5918                                    false, Complain);
5919   return Ctx.IsStructurallyEquivalent(From, To);
5920 }
5921