xref: /freebsd/contrib/llvm-project/clang/lib/Serialization/ASTReaderDecl.cpp (revision 0d8fe2373503aeac48492f28073049a8bfa4feb5)
1 //===- ASTReaderDecl.cpp - Decl Deserialization ---------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file implements the ASTReader::readDeclRecord method, which is the
10 // entrypoint for loading a decl.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "ASTCommon.h"
15 #include "ASTReaderInternals.h"
16 #include "clang/AST/ASTContext.h"
17 #include "clang/AST/Attr.h"
18 #include "clang/AST/AttrIterator.h"
19 #include "clang/AST/Decl.h"
20 #include "clang/AST/DeclBase.h"
21 #include "clang/AST/DeclCXX.h"
22 #include "clang/AST/DeclFriend.h"
23 #include "clang/AST/DeclObjC.h"
24 #include "clang/AST/DeclOpenMP.h"
25 #include "clang/AST/DeclTemplate.h"
26 #include "clang/AST/DeclVisitor.h"
27 #include "clang/AST/DeclarationName.h"
28 #include "clang/AST/Expr.h"
29 #include "clang/AST/ExternalASTSource.h"
30 #include "clang/AST/LambdaCapture.h"
31 #include "clang/AST/NestedNameSpecifier.h"
32 #include "clang/AST/OpenMPClause.h"
33 #include "clang/AST/Redeclarable.h"
34 #include "clang/AST/Stmt.h"
35 #include "clang/AST/TemplateBase.h"
36 #include "clang/AST/Type.h"
37 #include "clang/AST/UnresolvedSet.h"
38 #include "clang/Basic/AttrKinds.h"
39 #include "clang/Basic/ExceptionSpecificationType.h"
40 #include "clang/Basic/IdentifierTable.h"
41 #include "clang/Basic/LLVM.h"
42 #include "clang/Basic/Lambda.h"
43 #include "clang/Basic/LangOptions.h"
44 #include "clang/Basic/Linkage.h"
45 #include "clang/Basic/Module.h"
46 #include "clang/Basic/PragmaKinds.h"
47 #include "clang/Basic/SourceLocation.h"
48 #include "clang/Basic/Specifiers.h"
49 #include "clang/Sema/IdentifierResolver.h"
50 #include "clang/Serialization/ASTBitCodes.h"
51 #include "clang/Serialization/ASTRecordReader.h"
52 #include "clang/Serialization/ContinuousRangeMap.h"
53 #include "clang/Serialization/ModuleFile.h"
54 #include "llvm/ADT/DenseMap.h"
55 #include "llvm/ADT/FoldingSet.h"
56 #include "llvm/ADT/STLExtras.h"
57 #include "llvm/ADT/SmallPtrSet.h"
58 #include "llvm/ADT/SmallVector.h"
59 #include "llvm/ADT/iterator_range.h"
60 #include "llvm/Bitstream/BitstreamReader.h"
61 #include "llvm/Support/Casting.h"
62 #include "llvm/Support/ErrorHandling.h"
63 #include "llvm/Support/SaveAndRestore.h"
64 #include <algorithm>
65 #include <cassert>
66 #include <cstdint>
67 #include <cstring>
68 #include <string>
69 #include <utility>
70 
71 using namespace clang;
72 using namespace serialization;
73 
74 //===----------------------------------------------------------------------===//
75 // Declaration deserialization
76 //===----------------------------------------------------------------------===//
77 
78 namespace clang {
79 
80   class ASTDeclReader : public DeclVisitor<ASTDeclReader, void> {
81     ASTReader &Reader;
82     ASTRecordReader &Record;
83     ASTReader::RecordLocation Loc;
84     const DeclID ThisDeclID;
85     const SourceLocation ThisDeclLoc;
86 
87     using RecordData = ASTReader::RecordData;
88 
89     TypeID DeferredTypeID = 0;
90     unsigned AnonymousDeclNumber;
91     GlobalDeclID NamedDeclForTagDecl = 0;
92     IdentifierInfo *TypedefNameForLinkage = nullptr;
93 
94     bool HasPendingBody = false;
95 
96     ///A flag to carry the information for a decl from the entity is
97     /// used. We use it to delay the marking of the canonical decl as used until
98     /// the entire declaration is deserialized and merged.
99     bool IsDeclMarkedUsed = false;
100 
101     uint64_t GetCurrentCursorOffset();
102 
103     uint64_t ReadLocalOffset() {
104       uint64_t LocalOffset = Record.readInt();
105       assert(LocalOffset < Loc.Offset && "offset point after current record");
106       return LocalOffset ? Loc.Offset - LocalOffset : 0;
107     }
108 
109     uint64_t ReadGlobalOffset() {
110       uint64_t Local = ReadLocalOffset();
111       return Local ? Record.getGlobalBitOffset(Local) : 0;
112     }
113 
114     SourceLocation readSourceLocation() {
115       return Record.readSourceLocation();
116     }
117 
118     SourceRange readSourceRange() {
119       return Record.readSourceRange();
120     }
121 
122     TypeSourceInfo *readTypeSourceInfo() {
123       return Record.readTypeSourceInfo();
124     }
125 
126     serialization::DeclID readDeclID() {
127       return Record.readDeclID();
128     }
129 
130     std::string readString() {
131       return Record.readString();
132     }
133 
134     void readDeclIDList(SmallVectorImpl<DeclID> &IDs) {
135       for (unsigned I = 0, Size = Record.readInt(); I != Size; ++I)
136         IDs.push_back(readDeclID());
137     }
138 
139     Decl *readDecl() {
140       return Record.readDecl();
141     }
142 
143     template<typename T>
144     T *readDeclAs() {
145       return Record.readDeclAs<T>();
146     }
147 
148     serialization::SubmoduleID readSubmoduleID() {
149       if (Record.getIdx() == Record.size())
150         return 0;
151 
152       return Record.getGlobalSubmoduleID(Record.readInt());
153     }
154 
155     Module *readModule() {
156       return Record.getSubmodule(readSubmoduleID());
157     }
158 
159     void ReadCXXRecordDefinition(CXXRecordDecl *D, bool Update);
160     void ReadCXXDefinitionData(struct CXXRecordDecl::DefinitionData &Data,
161                                const CXXRecordDecl *D);
162     void MergeDefinitionData(CXXRecordDecl *D,
163                              struct CXXRecordDecl::DefinitionData &&NewDD);
164     void ReadObjCDefinitionData(struct ObjCInterfaceDecl::DefinitionData &Data);
165     void MergeDefinitionData(ObjCInterfaceDecl *D,
166                              struct ObjCInterfaceDecl::DefinitionData &&NewDD);
167     void ReadObjCDefinitionData(struct ObjCProtocolDecl::DefinitionData &Data);
168     void MergeDefinitionData(ObjCProtocolDecl *D,
169                              struct ObjCProtocolDecl::DefinitionData &&NewDD);
170 
171     static DeclContext *getPrimaryDCForAnonymousDecl(DeclContext *LexicalDC);
172 
173     static NamedDecl *getAnonymousDeclForMerging(ASTReader &Reader,
174                                                  DeclContext *DC,
175                                                  unsigned Index);
176     static void setAnonymousDeclForMerging(ASTReader &Reader, DeclContext *DC,
177                                            unsigned Index, NamedDecl *D);
178 
179     /// Results from loading a RedeclarableDecl.
180     class RedeclarableResult {
181       Decl *MergeWith;
182       GlobalDeclID FirstID;
183       bool IsKeyDecl;
184 
185     public:
186       RedeclarableResult(Decl *MergeWith, GlobalDeclID FirstID, bool IsKeyDecl)
187           : MergeWith(MergeWith), FirstID(FirstID), IsKeyDecl(IsKeyDecl) {}
188 
189       /// Retrieve the first ID.
190       GlobalDeclID getFirstID() const { return FirstID; }
191 
192       /// Is this declaration a key declaration?
193       bool isKeyDecl() const { return IsKeyDecl; }
194 
195       /// Get a known declaration that this should be merged with, if
196       /// any.
197       Decl *getKnownMergeTarget() const { return MergeWith; }
198     };
199 
200     /// Class used to capture the result of searching for an existing
201     /// declaration of a specific kind and name, along with the ability
202     /// to update the place where this result was found (the declaration
203     /// chain hanging off an identifier or the DeclContext we searched in)
204     /// if requested.
205     class FindExistingResult {
206       ASTReader &Reader;
207       NamedDecl *New = nullptr;
208       NamedDecl *Existing = nullptr;
209       bool AddResult = false;
210       unsigned AnonymousDeclNumber = 0;
211       IdentifierInfo *TypedefNameForLinkage = nullptr;
212 
213     public:
214       FindExistingResult(ASTReader &Reader) : Reader(Reader) {}
215 
216       FindExistingResult(ASTReader &Reader, NamedDecl *New, NamedDecl *Existing,
217                          unsigned AnonymousDeclNumber,
218                          IdentifierInfo *TypedefNameForLinkage)
219           : Reader(Reader), New(New), Existing(Existing), AddResult(true),
220             AnonymousDeclNumber(AnonymousDeclNumber),
221             TypedefNameForLinkage(TypedefNameForLinkage) {}
222 
223       FindExistingResult(FindExistingResult &&Other)
224           : Reader(Other.Reader), New(Other.New), Existing(Other.Existing),
225             AddResult(Other.AddResult),
226             AnonymousDeclNumber(Other.AnonymousDeclNumber),
227             TypedefNameForLinkage(Other.TypedefNameForLinkage) {
228         Other.AddResult = false;
229       }
230 
231       FindExistingResult &operator=(FindExistingResult &&) = delete;
232       ~FindExistingResult();
233 
234       /// Suppress the addition of this result into the known set of
235       /// names.
236       void suppress() { AddResult = false; }
237 
238       operator NamedDecl*() const { return Existing; }
239 
240       template<typename T>
241       operator T*() const { return dyn_cast_or_null<T>(Existing); }
242     };
243 
244     static DeclContext *getPrimaryContextForMerging(ASTReader &Reader,
245                                                     DeclContext *DC);
246     FindExistingResult findExisting(NamedDecl *D);
247 
248   public:
249     ASTDeclReader(ASTReader &Reader, ASTRecordReader &Record,
250                   ASTReader::RecordLocation Loc,
251                   DeclID thisDeclID, SourceLocation ThisDeclLoc)
252         : Reader(Reader), Record(Record), Loc(Loc), ThisDeclID(thisDeclID),
253           ThisDeclLoc(ThisDeclLoc) {}
254 
255     template <typename T> static
256     void AddLazySpecializations(T *D,
257                                 SmallVectorImpl<serialization::DeclID>& IDs) {
258       if (IDs.empty())
259         return;
260 
261       // FIXME: We should avoid this pattern of getting the ASTContext.
262       ASTContext &C = D->getASTContext();
263 
264       auto *&LazySpecializations = D->getCommonPtr()->LazySpecializations;
265 
266       if (auto &Old = LazySpecializations) {
267         IDs.insert(IDs.end(), Old + 1, Old + 1 + Old[0]);
268         llvm::sort(IDs);
269         IDs.erase(std::unique(IDs.begin(), IDs.end()), IDs.end());
270       }
271 
272       auto *Result = new (C) serialization::DeclID[1 + IDs.size()];
273       *Result = IDs.size();
274       std::copy(IDs.begin(), IDs.end(), Result + 1);
275 
276       LazySpecializations = Result;
277     }
278 
279     template <typename DeclT>
280     static Decl *getMostRecentDeclImpl(Redeclarable<DeclT> *D);
281     static Decl *getMostRecentDeclImpl(...);
282     static Decl *getMostRecentDecl(Decl *D);
283 
284     static void mergeInheritableAttributes(ASTReader &Reader, Decl *D,
285                                            Decl *Previous);
286 
287     template <typename DeclT>
288     static void attachPreviousDeclImpl(ASTReader &Reader,
289                                        Redeclarable<DeclT> *D, Decl *Previous,
290                                        Decl *Canon);
291     static void attachPreviousDeclImpl(ASTReader &Reader, ...);
292     static void attachPreviousDecl(ASTReader &Reader, Decl *D, Decl *Previous,
293                                    Decl *Canon);
294 
295     template <typename DeclT>
296     static void attachLatestDeclImpl(Redeclarable<DeclT> *D, Decl *Latest);
297     static void attachLatestDeclImpl(...);
298     static void attachLatestDecl(Decl *D, Decl *latest);
299 
300     template <typename DeclT>
301     static void markIncompleteDeclChainImpl(Redeclarable<DeclT> *D);
302     static void markIncompleteDeclChainImpl(...);
303 
304     /// Determine whether this declaration has a pending body.
305     bool hasPendingBody() const { return HasPendingBody; }
306 
307     void ReadFunctionDefinition(FunctionDecl *FD);
308     void Visit(Decl *D);
309 
310     void UpdateDecl(Decl *D, SmallVectorImpl<serialization::DeclID> &);
311 
312     static void setNextObjCCategory(ObjCCategoryDecl *Cat,
313                                     ObjCCategoryDecl *Next) {
314       Cat->NextClassCategory = Next;
315     }
316 
317     void VisitDecl(Decl *D);
318     void VisitPragmaCommentDecl(PragmaCommentDecl *D);
319     void VisitPragmaDetectMismatchDecl(PragmaDetectMismatchDecl *D);
320     void VisitTranslationUnitDecl(TranslationUnitDecl *TU);
321     void VisitNamedDecl(NamedDecl *ND);
322     void VisitLabelDecl(LabelDecl *LD);
323     void VisitNamespaceDecl(NamespaceDecl *D);
324     void VisitUsingDirectiveDecl(UsingDirectiveDecl *D);
325     void VisitNamespaceAliasDecl(NamespaceAliasDecl *D);
326     void VisitTypeDecl(TypeDecl *TD);
327     RedeclarableResult VisitTypedefNameDecl(TypedefNameDecl *TD);
328     void VisitTypedefDecl(TypedefDecl *TD);
329     void VisitTypeAliasDecl(TypeAliasDecl *TD);
330     void VisitUnresolvedUsingTypenameDecl(UnresolvedUsingTypenameDecl *D);
331     RedeclarableResult VisitTagDecl(TagDecl *TD);
332     void VisitEnumDecl(EnumDecl *ED);
333     RedeclarableResult VisitRecordDeclImpl(RecordDecl *RD);
334     void VisitRecordDecl(RecordDecl *RD) { VisitRecordDeclImpl(RD); }
335     RedeclarableResult VisitCXXRecordDeclImpl(CXXRecordDecl *D);
336     void VisitCXXRecordDecl(CXXRecordDecl *D) { VisitCXXRecordDeclImpl(D); }
337     RedeclarableResult VisitClassTemplateSpecializationDeclImpl(
338                                             ClassTemplateSpecializationDecl *D);
339 
340     void VisitClassTemplateSpecializationDecl(
341         ClassTemplateSpecializationDecl *D) {
342       VisitClassTemplateSpecializationDeclImpl(D);
343     }
344 
345     void VisitClassTemplatePartialSpecializationDecl(
346                                      ClassTemplatePartialSpecializationDecl *D);
347     void VisitClassScopeFunctionSpecializationDecl(
348                                        ClassScopeFunctionSpecializationDecl *D);
349     RedeclarableResult
350     VisitVarTemplateSpecializationDeclImpl(VarTemplateSpecializationDecl *D);
351 
352     void VisitVarTemplateSpecializationDecl(VarTemplateSpecializationDecl *D) {
353       VisitVarTemplateSpecializationDeclImpl(D);
354     }
355 
356     void VisitVarTemplatePartialSpecializationDecl(
357         VarTemplatePartialSpecializationDecl *D);
358     void VisitTemplateTypeParmDecl(TemplateTypeParmDecl *D);
359     void VisitValueDecl(ValueDecl *VD);
360     void VisitEnumConstantDecl(EnumConstantDecl *ECD);
361     void VisitUnresolvedUsingValueDecl(UnresolvedUsingValueDecl *D);
362     void VisitDeclaratorDecl(DeclaratorDecl *DD);
363     void VisitFunctionDecl(FunctionDecl *FD);
364     void VisitCXXDeductionGuideDecl(CXXDeductionGuideDecl *GD);
365     void VisitCXXMethodDecl(CXXMethodDecl *D);
366     void VisitCXXConstructorDecl(CXXConstructorDecl *D);
367     void VisitCXXDestructorDecl(CXXDestructorDecl *D);
368     void VisitCXXConversionDecl(CXXConversionDecl *D);
369     void VisitFieldDecl(FieldDecl *FD);
370     void VisitMSPropertyDecl(MSPropertyDecl *FD);
371     void VisitMSGuidDecl(MSGuidDecl *D);
372     void VisitTemplateParamObjectDecl(TemplateParamObjectDecl *D);
373     void VisitIndirectFieldDecl(IndirectFieldDecl *FD);
374     RedeclarableResult VisitVarDeclImpl(VarDecl *D);
375     void VisitVarDecl(VarDecl *VD) { VisitVarDeclImpl(VD); }
376     void VisitImplicitParamDecl(ImplicitParamDecl *PD);
377     void VisitParmVarDecl(ParmVarDecl *PD);
378     void VisitDecompositionDecl(DecompositionDecl *DD);
379     void VisitBindingDecl(BindingDecl *BD);
380     void VisitNonTypeTemplateParmDecl(NonTypeTemplateParmDecl *D);
381     DeclID VisitTemplateDecl(TemplateDecl *D);
382     void VisitConceptDecl(ConceptDecl *D);
383     void VisitRequiresExprBodyDecl(RequiresExprBodyDecl *D);
384     RedeclarableResult VisitRedeclarableTemplateDecl(RedeclarableTemplateDecl *D);
385     void VisitClassTemplateDecl(ClassTemplateDecl *D);
386     void VisitBuiltinTemplateDecl(BuiltinTemplateDecl *D);
387     void VisitVarTemplateDecl(VarTemplateDecl *D);
388     void VisitFunctionTemplateDecl(FunctionTemplateDecl *D);
389     void VisitTemplateTemplateParmDecl(TemplateTemplateParmDecl *D);
390     void VisitTypeAliasTemplateDecl(TypeAliasTemplateDecl *D);
391     void VisitUsingDecl(UsingDecl *D);
392     void VisitUsingPackDecl(UsingPackDecl *D);
393     void VisitUsingShadowDecl(UsingShadowDecl *D);
394     void VisitConstructorUsingShadowDecl(ConstructorUsingShadowDecl *D);
395     void VisitLinkageSpecDecl(LinkageSpecDecl *D);
396     void VisitExportDecl(ExportDecl *D);
397     void VisitFileScopeAsmDecl(FileScopeAsmDecl *AD);
398     void VisitImportDecl(ImportDecl *D);
399     void VisitAccessSpecDecl(AccessSpecDecl *D);
400     void VisitFriendDecl(FriendDecl *D);
401     void VisitFriendTemplateDecl(FriendTemplateDecl *D);
402     void VisitStaticAssertDecl(StaticAssertDecl *D);
403     void VisitBlockDecl(BlockDecl *BD);
404     void VisitCapturedDecl(CapturedDecl *CD);
405     void VisitEmptyDecl(EmptyDecl *D);
406     void VisitLifetimeExtendedTemporaryDecl(LifetimeExtendedTemporaryDecl *D);
407 
408     std::pair<uint64_t, uint64_t> VisitDeclContext(DeclContext *DC);
409 
410     template<typename T>
411     RedeclarableResult VisitRedeclarable(Redeclarable<T> *D);
412 
413     template<typename T>
414     void mergeRedeclarable(Redeclarable<T> *D, RedeclarableResult &Redecl,
415                            DeclID TemplatePatternID = 0);
416 
417     template<typename T>
418     void mergeRedeclarable(Redeclarable<T> *D, T *Existing,
419                            RedeclarableResult &Redecl,
420                            DeclID TemplatePatternID = 0);
421 
422     template<typename T>
423     void mergeMergeable(Mergeable<T> *D);
424 
425     void mergeMergeable(LifetimeExtendedTemporaryDecl *D);
426 
427     void mergeTemplatePattern(RedeclarableTemplateDecl *D,
428                               RedeclarableTemplateDecl *Existing,
429                               DeclID DsID, bool IsKeyDecl);
430 
431     ObjCTypeParamList *ReadObjCTypeParamList();
432 
433     // FIXME: Reorder according to DeclNodes.td?
434     void VisitObjCMethodDecl(ObjCMethodDecl *D);
435     void VisitObjCTypeParamDecl(ObjCTypeParamDecl *D);
436     void VisitObjCContainerDecl(ObjCContainerDecl *D);
437     void VisitObjCInterfaceDecl(ObjCInterfaceDecl *D);
438     void VisitObjCIvarDecl(ObjCIvarDecl *D);
439     void VisitObjCProtocolDecl(ObjCProtocolDecl *D);
440     void VisitObjCAtDefsFieldDecl(ObjCAtDefsFieldDecl *D);
441     void VisitObjCCategoryDecl(ObjCCategoryDecl *D);
442     void VisitObjCImplDecl(ObjCImplDecl *D);
443     void VisitObjCCategoryImplDecl(ObjCCategoryImplDecl *D);
444     void VisitObjCImplementationDecl(ObjCImplementationDecl *D);
445     void VisitObjCCompatibleAliasDecl(ObjCCompatibleAliasDecl *D);
446     void VisitObjCPropertyDecl(ObjCPropertyDecl *D);
447     void VisitObjCPropertyImplDecl(ObjCPropertyImplDecl *D);
448     void VisitOMPThreadPrivateDecl(OMPThreadPrivateDecl *D);
449     void VisitOMPAllocateDecl(OMPAllocateDecl *D);
450     void VisitOMPDeclareReductionDecl(OMPDeclareReductionDecl *D);
451     void VisitOMPDeclareMapperDecl(OMPDeclareMapperDecl *D);
452     void VisitOMPRequiresDecl(OMPRequiresDecl *D);
453     void VisitOMPCapturedExprDecl(OMPCapturedExprDecl *D);
454   };
455 
456 } // namespace clang
457 
458 namespace {
459 
460 /// Iterator over the redeclarations of a declaration that have already
461 /// been merged into the same redeclaration chain.
462 template<typename DeclT>
463 class MergedRedeclIterator {
464   DeclT *Start;
465   DeclT *Canonical = nullptr;
466   DeclT *Current = nullptr;
467 
468 public:
469   MergedRedeclIterator() = default;
470   MergedRedeclIterator(DeclT *Start) : Start(Start), Current(Start) {}
471 
472   DeclT *operator*() { return Current; }
473 
474   MergedRedeclIterator &operator++() {
475     if (Current->isFirstDecl()) {
476       Canonical = Current;
477       Current = Current->getMostRecentDecl();
478     } else
479       Current = Current->getPreviousDecl();
480 
481     // If we started in the merged portion, we'll reach our start position
482     // eventually. Otherwise, we'll never reach it, but the second declaration
483     // we reached was the canonical declaration, so stop when we see that one
484     // again.
485     if (Current == Start || Current == Canonical)
486       Current = nullptr;
487     return *this;
488   }
489 
490   friend bool operator!=(const MergedRedeclIterator &A,
491                          const MergedRedeclIterator &B) {
492     return A.Current != B.Current;
493   }
494 };
495 
496 } // namespace
497 
498 template <typename DeclT>
499 static llvm::iterator_range<MergedRedeclIterator<DeclT>>
500 merged_redecls(DeclT *D) {
501   return llvm::make_range(MergedRedeclIterator<DeclT>(D),
502                           MergedRedeclIterator<DeclT>());
503 }
504 
505 uint64_t ASTDeclReader::GetCurrentCursorOffset() {
506   return Loc.F->DeclsCursor.GetCurrentBitNo() + Loc.F->GlobalBitOffset;
507 }
508 
509 void ASTDeclReader::ReadFunctionDefinition(FunctionDecl *FD) {
510   if (Record.readInt()) {
511     Reader.DefinitionSource[FD] =
512         Loc.F->Kind == ModuleKind::MK_MainFile ||
513         Reader.getContext().getLangOpts().BuildingPCHWithObjectFile;
514   }
515   if (auto *CD = dyn_cast<CXXConstructorDecl>(FD)) {
516     CD->setNumCtorInitializers(Record.readInt());
517     if (CD->getNumCtorInitializers())
518       CD->CtorInitializers = ReadGlobalOffset();
519   }
520   // Store the offset of the body so we can lazily load it later.
521   Reader.PendingBodies[FD] = GetCurrentCursorOffset();
522   HasPendingBody = true;
523 }
524 
525 void ASTDeclReader::Visit(Decl *D) {
526   DeclVisitor<ASTDeclReader, void>::Visit(D);
527 
528   // At this point we have deserialized and merged the decl and it is safe to
529   // update its canonical decl to signal that the entire entity is used.
530   D->getCanonicalDecl()->Used |= IsDeclMarkedUsed;
531   IsDeclMarkedUsed = false;
532 
533   if (auto *DD = dyn_cast<DeclaratorDecl>(D)) {
534     if (auto *TInfo = DD->getTypeSourceInfo())
535       Record.readTypeLoc(TInfo->getTypeLoc());
536   }
537 
538   if (auto *TD = dyn_cast<TypeDecl>(D)) {
539     // We have a fully initialized TypeDecl. Read its type now.
540     TD->setTypeForDecl(Reader.GetType(DeferredTypeID).getTypePtrOrNull());
541 
542     // If this is a tag declaration with a typedef name for linkage, it's safe
543     // to load that typedef now.
544     if (NamedDeclForTagDecl)
545       cast<TagDecl>(D)->TypedefNameDeclOrQualifier =
546           cast<TypedefNameDecl>(Reader.GetDecl(NamedDeclForTagDecl));
547   } else if (auto *ID = dyn_cast<ObjCInterfaceDecl>(D)) {
548     // if we have a fully initialized TypeDecl, we can safely read its type now.
549     ID->TypeForDecl = Reader.GetType(DeferredTypeID).getTypePtrOrNull();
550   } else if (auto *FD = dyn_cast<FunctionDecl>(D)) {
551     // FunctionDecl's body was written last after all other Stmts/Exprs.
552     // We only read it if FD doesn't already have a body (e.g., from another
553     // module).
554     // FIXME: Can we diagnose ODR violations somehow?
555     if (Record.readInt())
556       ReadFunctionDefinition(FD);
557   }
558 }
559 
560 void ASTDeclReader::VisitDecl(Decl *D) {
561   if (D->isTemplateParameter() || D->isTemplateParameterPack() ||
562       isa<ParmVarDecl>(D) || isa<ObjCTypeParamDecl>(D)) {
563     // We don't want to deserialize the DeclContext of a template
564     // parameter or of a parameter of a function template immediately.   These
565     // entities might be used in the formulation of its DeclContext (for
566     // example, a function parameter can be used in decltype() in trailing
567     // return type of the function).  Use the translation unit DeclContext as a
568     // placeholder.
569     GlobalDeclID SemaDCIDForTemplateParmDecl = readDeclID();
570     GlobalDeclID LexicalDCIDForTemplateParmDecl = readDeclID();
571     if (!LexicalDCIDForTemplateParmDecl)
572       LexicalDCIDForTemplateParmDecl = SemaDCIDForTemplateParmDecl;
573     Reader.addPendingDeclContextInfo(D,
574                                      SemaDCIDForTemplateParmDecl,
575                                      LexicalDCIDForTemplateParmDecl);
576     D->setDeclContext(Reader.getContext().getTranslationUnitDecl());
577   } else {
578     auto *SemaDC = readDeclAs<DeclContext>();
579     auto *LexicalDC = readDeclAs<DeclContext>();
580     if (!LexicalDC)
581       LexicalDC = SemaDC;
582     DeclContext *MergedSemaDC = Reader.MergedDeclContexts.lookup(SemaDC);
583     // Avoid calling setLexicalDeclContext() directly because it uses
584     // Decl::getASTContext() internally which is unsafe during derialization.
585     D->setDeclContextsImpl(MergedSemaDC ? MergedSemaDC : SemaDC, LexicalDC,
586                            Reader.getContext());
587   }
588   D->setLocation(ThisDeclLoc);
589   D->InvalidDecl = Record.readInt();
590   if (Record.readInt()) { // hasAttrs
591     AttrVec Attrs;
592     Record.readAttributes(Attrs);
593     // Avoid calling setAttrs() directly because it uses Decl::getASTContext()
594     // internally which is unsafe during derialization.
595     D->setAttrsImpl(Attrs, Reader.getContext());
596   }
597   D->setImplicit(Record.readInt());
598   D->Used = Record.readInt();
599   IsDeclMarkedUsed |= D->Used;
600   D->setReferenced(Record.readInt());
601   D->setTopLevelDeclInObjCContainer(Record.readInt());
602   D->setAccess((AccessSpecifier)Record.readInt());
603   D->FromASTFile = true;
604   bool ModulePrivate = Record.readInt();
605 
606   // Determine whether this declaration is part of a (sub)module. If so, it
607   // may not yet be visible.
608   if (unsigned SubmoduleID = readSubmoduleID()) {
609     // Store the owning submodule ID in the declaration.
610     D->setModuleOwnershipKind(
611         ModulePrivate ? Decl::ModuleOwnershipKind::ModulePrivate
612                       : Decl::ModuleOwnershipKind::VisibleWhenImported);
613     D->setOwningModuleID(SubmoduleID);
614 
615     if (ModulePrivate) {
616       // Module-private declarations are never visible, so there is no work to
617       // do.
618     } else if (Reader.getContext().getLangOpts().ModulesLocalVisibility) {
619       // If local visibility is being tracked, this declaration will become
620       // hidden and visible as the owning module does.
621     } else if (Module *Owner = Reader.getSubmodule(SubmoduleID)) {
622       // Mark the declaration as visible when its owning module becomes visible.
623       if (Owner->NameVisibility == Module::AllVisible)
624         D->setVisibleDespiteOwningModule();
625       else
626         Reader.HiddenNamesMap[Owner].push_back(D);
627     }
628   } else if (ModulePrivate) {
629     D->setModuleOwnershipKind(Decl::ModuleOwnershipKind::ModulePrivate);
630   }
631 }
632 
633 void ASTDeclReader::VisitPragmaCommentDecl(PragmaCommentDecl *D) {
634   VisitDecl(D);
635   D->setLocation(readSourceLocation());
636   D->CommentKind = (PragmaMSCommentKind)Record.readInt();
637   std::string Arg = readString();
638   memcpy(D->getTrailingObjects<char>(), Arg.data(), Arg.size());
639   D->getTrailingObjects<char>()[Arg.size()] = '\0';
640 }
641 
642 void ASTDeclReader::VisitPragmaDetectMismatchDecl(PragmaDetectMismatchDecl *D) {
643   VisitDecl(D);
644   D->setLocation(readSourceLocation());
645   std::string Name = readString();
646   memcpy(D->getTrailingObjects<char>(), Name.data(), Name.size());
647   D->getTrailingObjects<char>()[Name.size()] = '\0';
648 
649   D->ValueStart = Name.size() + 1;
650   std::string Value = readString();
651   memcpy(D->getTrailingObjects<char>() + D->ValueStart, Value.data(),
652          Value.size());
653   D->getTrailingObjects<char>()[D->ValueStart + Value.size()] = '\0';
654 }
655 
656 void ASTDeclReader::VisitTranslationUnitDecl(TranslationUnitDecl *TU) {
657   llvm_unreachable("Translation units are not serialized");
658 }
659 
660 void ASTDeclReader::VisitNamedDecl(NamedDecl *ND) {
661   VisitDecl(ND);
662   ND->setDeclName(Record.readDeclarationName());
663   AnonymousDeclNumber = Record.readInt();
664 }
665 
666 void ASTDeclReader::VisitTypeDecl(TypeDecl *TD) {
667   VisitNamedDecl(TD);
668   TD->setLocStart(readSourceLocation());
669   // Delay type reading until after we have fully initialized the decl.
670   DeferredTypeID = Record.getGlobalTypeID(Record.readInt());
671 }
672 
673 ASTDeclReader::RedeclarableResult
674 ASTDeclReader::VisitTypedefNameDecl(TypedefNameDecl *TD) {
675   RedeclarableResult Redecl = VisitRedeclarable(TD);
676   VisitTypeDecl(TD);
677   TypeSourceInfo *TInfo = readTypeSourceInfo();
678   if (Record.readInt()) { // isModed
679     QualType modedT = Record.readType();
680     TD->setModedTypeSourceInfo(TInfo, modedT);
681   } else
682     TD->setTypeSourceInfo(TInfo);
683   // Read and discard the declaration for which this is a typedef name for
684   // linkage, if it exists. We cannot rely on our type to pull in this decl,
685   // because it might have been merged with a type from another module and
686   // thus might not refer to our version of the declaration.
687   readDecl();
688   return Redecl;
689 }
690 
691 void ASTDeclReader::VisitTypedefDecl(TypedefDecl *TD) {
692   RedeclarableResult Redecl = VisitTypedefNameDecl(TD);
693   mergeRedeclarable(TD, Redecl);
694 }
695 
696 void ASTDeclReader::VisitTypeAliasDecl(TypeAliasDecl *TD) {
697   RedeclarableResult Redecl = VisitTypedefNameDecl(TD);
698   if (auto *Template = readDeclAs<TypeAliasTemplateDecl>())
699     // Merged when we merge the template.
700     TD->setDescribedAliasTemplate(Template);
701   else
702     mergeRedeclarable(TD, Redecl);
703 }
704 
705 ASTDeclReader::RedeclarableResult ASTDeclReader::VisitTagDecl(TagDecl *TD) {
706   RedeclarableResult Redecl = VisitRedeclarable(TD);
707   VisitTypeDecl(TD);
708 
709   TD->IdentifierNamespace = Record.readInt();
710   TD->setTagKind((TagDecl::TagKind)Record.readInt());
711   if (!isa<CXXRecordDecl>(TD))
712     TD->setCompleteDefinition(Record.readInt());
713   TD->setEmbeddedInDeclarator(Record.readInt());
714   TD->setFreeStanding(Record.readInt());
715   TD->setCompleteDefinitionRequired(Record.readInt());
716   TD->setBraceRange(readSourceRange());
717 
718   switch (Record.readInt()) {
719   case 0:
720     break;
721   case 1: { // ExtInfo
722     auto *Info = new (Reader.getContext()) TagDecl::ExtInfo();
723     Record.readQualifierInfo(*Info);
724     TD->TypedefNameDeclOrQualifier = Info;
725     break;
726   }
727   case 2: // TypedefNameForAnonDecl
728     NamedDeclForTagDecl = readDeclID();
729     TypedefNameForLinkage = Record.readIdentifier();
730     break;
731   default:
732     llvm_unreachable("unexpected tag info kind");
733   }
734 
735   if (!isa<CXXRecordDecl>(TD))
736     mergeRedeclarable(TD, Redecl);
737   return Redecl;
738 }
739 
740 void ASTDeclReader::VisitEnumDecl(EnumDecl *ED) {
741   VisitTagDecl(ED);
742   if (TypeSourceInfo *TI = readTypeSourceInfo())
743     ED->setIntegerTypeSourceInfo(TI);
744   else
745     ED->setIntegerType(Record.readType());
746   ED->setPromotionType(Record.readType());
747   ED->setNumPositiveBits(Record.readInt());
748   ED->setNumNegativeBits(Record.readInt());
749   ED->setScoped(Record.readInt());
750   ED->setScopedUsingClassTag(Record.readInt());
751   ED->setFixed(Record.readInt());
752 
753   ED->setHasODRHash(true);
754   ED->ODRHash = Record.readInt();
755 
756   // If this is a definition subject to the ODR, and we already have a
757   // definition, merge this one into it.
758   if (ED->isCompleteDefinition() &&
759       Reader.getContext().getLangOpts().Modules &&
760       Reader.getContext().getLangOpts().CPlusPlus) {
761     EnumDecl *&OldDef = Reader.EnumDefinitions[ED->getCanonicalDecl()];
762     if (!OldDef) {
763       // This is the first time we've seen an imported definition. Look for a
764       // local definition before deciding that we are the first definition.
765       for (auto *D : merged_redecls(ED->getCanonicalDecl())) {
766         if (!D->isFromASTFile() && D->isCompleteDefinition()) {
767           OldDef = D;
768           break;
769         }
770       }
771     }
772     if (OldDef) {
773       Reader.MergedDeclContexts.insert(std::make_pair(ED, OldDef));
774       ED->setCompleteDefinition(false);
775       Reader.mergeDefinitionVisibility(OldDef, ED);
776       if (OldDef->getODRHash() != ED->getODRHash())
777         Reader.PendingEnumOdrMergeFailures[OldDef].push_back(ED);
778     } else {
779       OldDef = ED;
780     }
781   }
782 
783   if (auto *InstED = readDeclAs<EnumDecl>()) {
784     auto TSK = (TemplateSpecializationKind)Record.readInt();
785     SourceLocation POI = readSourceLocation();
786     ED->setInstantiationOfMemberEnum(Reader.getContext(), InstED, TSK);
787     ED->getMemberSpecializationInfo()->setPointOfInstantiation(POI);
788   }
789 }
790 
791 ASTDeclReader::RedeclarableResult
792 ASTDeclReader::VisitRecordDeclImpl(RecordDecl *RD) {
793   RedeclarableResult Redecl = VisitTagDecl(RD);
794   RD->setHasFlexibleArrayMember(Record.readInt());
795   RD->setAnonymousStructOrUnion(Record.readInt());
796   RD->setHasObjectMember(Record.readInt());
797   RD->setHasVolatileMember(Record.readInt());
798   RD->setNonTrivialToPrimitiveDefaultInitialize(Record.readInt());
799   RD->setNonTrivialToPrimitiveCopy(Record.readInt());
800   RD->setNonTrivialToPrimitiveDestroy(Record.readInt());
801   RD->setHasNonTrivialToPrimitiveDefaultInitializeCUnion(Record.readInt());
802   RD->setHasNonTrivialToPrimitiveDestructCUnion(Record.readInt());
803   RD->setHasNonTrivialToPrimitiveCopyCUnion(Record.readInt());
804   RD->setParamDestroyedInCallee(Record.readInt());
805   RD->setArgPassingRestrictions((RecordDecl::ArgPassingKind)Record.readInt());
806   return Redecl;
807 }
808 
809 void ASTDeclReader::VisitValueDecl(ValueDecl *VD) {
810   VisitNamedDecl(VD);
811   // For function declarations, defer reading the type in case the function has
812   // a deduced return type that references an entity declared within the
813   // function.
814   if (isa<FunctionDecl>(VD))
815     DeferredTypeID = Record.getGlobalTypeID(Record.readInt());
816   else
817     VD->setType(Record.readType());
818 }
819 
820 void ASTDeclReader::VisitEnumConstantDecl(EnumConstantDecl *ECD) {
821   VisitValueDecl(ECD);
822   if (Record.readInt())
823     ECD->setInitExpr(Record.readExpr());
824   ECD->setInitVal(Record.readAPSInt());
825   mergeMergeable(ECD);
826 }
827 
828 void ASTDeclReader::VisitDeclaratorDecl(DeclaratorDecl *DD) {
829   VisitValueDecl(DD);
830   DD->setInnerLocStart(readSourceLocation());
831   if (Record.readInt()) { // hasExtInfo
832     auto *Info = new (Reader.getContext()) DeclaratorDecl::ExtInfo();
833     Record.readQualifierInfo(*Info);
834     Info->TrailingRequiresClause = Record.readExpr();
835     DD->DeclInfo = Info;
836   }
837   QualType TSIType = Record.readType();
838   DD->setTypeSourceInfo(
839       TSIType.isNull() ? nullptr
840                        : Reader.getContext().CreateTypeSourceInfo(TSIType));
841 }
842 
843 void ASTDeclReader::VisitFunctionDecl(FunctionDecl *FD) {
844   RedeclarableResult Redecl = VisitRedeclarable(FD);
845   VisitDeclaratorDecl(FD);
846 
847   // Attach a type to this function. Use the real type if possible, but fall
848   // back to the type as written if it involves a deduced return type.
849   if (FD->getTypeSourceInfo() &&
850       FD->getTypeSourceInfo()->getType()->castAs<FunctionType>()
851                              ->getReturnType()->getContainedAutoType()) {
852     // We'll set up the real type in Visit, once we've finished loading the
853     // function.
854     FD->setType(FD->getTypeSourceInfo()->getType());
855     Reader.PendingFunctionTypes.push_back({FD, DeferredTypeID});
856   } else {
857     FD->setType(Reader.GetType(DeferredTypeID));
858   }
859   DeferredTypeID = 0;
860 
861   FD->DNLoc = Record.readDeclarationNameLoc(FD->getDeclName());
862   FD->IdentifierNamespace = Record.readInt();
863 
864   // FunctionDecl's body is handled last at ASTDeclReader::Visit,
865   // after everything else is read.
866 
867   FD->setStorageClass(static_cast<StorageClass>(Record.readInt()));
868   FD->setInlineSpecified(Record.readInt());
869   FD->setImplicitlyInline(Record.readInt());
870   FD->setVirtualAsWritten(Record.readInt());
871   // We defer calling `FunctionDecl::setPure()` here as for methods of
872   // `CXXTemplateSpecializationDecl`s, we may not have connected up the
873   // definition (which is required for `setPure`).
874   const bool Pure = Record.readInt();
875   FD->setHasInheritedPrototype(Record.readInt());
876   FD->setHasWrittenPrototype(Record.readInt());
877   FD->setDeletedAsWritten(Record.readInt());
878   FD->setTrivial(Record.readInt());
879   FD->setTrivialForCall(Record.readInt());
880   FD->setDefaulted(Record.readInt());
881   FD->setExplicitlyDefaulted(Record.readInt());
882   FD->setHasImplicitReturnZero(Record.readInt());
883   FD->setConstexprKind(static_cast<ConstexprSpecKind>(Record.readInt()));
884   FD->setUsesSEHTry(Record.readInt());
885   FD->setHasSkippedBody(Record.readInt());
886   FD->setIsMultiVersion(Record.readInt());
887   FD->setLateTemplateParsed(Record.readInt());
888 
889   FD->setCachedLinkage(static_cast<Linkage>(Record.readInt()));
890   FD->EndRangeLoc = readSourceLocation();
891 
892   FD->ODRHash = Record.readInt();
893   FD->setHasODRHash(true);
894 
895   if (FD->isDefaulted()) {
896     if (unsigned NumLookups = Record.readInt()) {
897       SmallVector<DeclAccessPair, 8> Lookups;
898       for (unsigned I = 0; I != NumLookups; ++I) {
899         NamedDecl *ND = Record.readDeclAs<NamedDecl>();
900         AccessSpecifier AS = (AccessSpecifier)Record.readInt();
901         Lookups.push_back(DeclAccessPair::make(ND, AS));
902       }
903       FD->setDefaultedFunctionInfo(FunctionDecl::DefaultedFunctionInfo::Create(
904           Reader.getContext(), Lookups));
905     }
906   }
907 
908   switch ((FunctionDecl::TemplatedKind)Record.readInt()) {
909   case FunctionDecl::TK_NonTemplate:
910     mergeRedeclarable(FD, Redecl);
911     break;
912   case FunctionDecl::TK_FunctionTemplate:
913     // Merged when we merge the template.
914     FD->setDescribedFunctionTemplate(readDeclAs<FunctionTemplateDecl>());
915     break;
916   case FunctionDecl::TK_MemberSpecialization: {
917     auto *InstFD = readDeclAs<FunctionDecl>();
918     auto TSK = (TemplateSpecializationKind)Record.readInt();
919     SourceLocation POI = readSourceLocation();
920     FD->setInstantiationOfMemberFunction(Reader.getContext(), InstFD, TSK);
921     FD->getMemberSpecializationInfo()->setPointOfInstantiation(POI);
922     mergeRedeclarable(FD, Redecl);
923     break;
924   }
925   case FunctionDecl::TK_FunctionTemplateSpecialization: {
926     auto *Template = readDeclAs<FunctionTemplateDecl>();
927     auto TSK = (TemplateSpecializationKind)Record.readInt();
928 
929     // Template arguments.
930     SmallVector<TemplateArgument, 8> TemplArgs;
931     Record.readTemplateArgumentList(TemplArgs, /*Canonicalize*/ true);
932 
933     // Template args as written.
934     SmallVector<TemplateArgumentLoc, 8> TemplArgLocs;
935     SourceLocation LAngleLoc, RAngleLoc;
936     bool HasTemplateArgumentsAsWritten = Record.readInt();
937     if (HasTemplateArgumentsAsWritten) {
938       unsigned NumTemplateArgLocs = Record.readInt();
939       TemplArgLocs.reserve(NumTemplateArgLocs);
940       for (unsigned i = 0; i != NumTemplateArgLocs; ++i)
941         TemplArgLocs.push_back(Record.readTemplateArgumentLoc());
942 
943       LAngleLoc = readSourceLocation();
944       RAngleLoc = readSourceLocation();
945     }
946 
947     SourceLocation POI = readSourceLocation();
948 
949     ASTContext &C = Reader.getContext();
950     TemplateArgumentList *TemplArgList
951       = TemplateArgumentList::CreateCopy(C, TemplArgs);
952     TemplateArgumentListInfo TemplArgsInfo(LAngleLoc, RAngleLoc);
953     for (unsigned i = 0, e = TemplArgLocs.size(); i != e; ++i)
954       TemplArgsInfo.addArgument(TemplArgLocs[i]);
955 
956     MemberSpecializationInfo *MSInfo = nullptr;
957     if (Record.readInt()) {
958       auto *FD = readDeclAs<FunctionDecl>();
959       auto TSK = (TemplateSpecializationKind)Record.readInt();
960       SourceLocation POI = readSourceLocation();
961 
962       MSInfo = new (C) MemberSpecializationInfo(FD, TSK);
963       MSInfo->setPointOfInstantiation(POI);
964     }
965 
966     FunctionTemplateSpecializationInfo *FTInfo =
967         FunctionTemplateSpecializationInfo::Create(
968             C, FD, Template, TSK, TemplArgList,
969             HasTemplateArgumentsAsWritten ? &TemplArgsInfo : nullptr, POI,
970             MSInfo);
971     FD->TemplateOrSpecialization = FTInfo;
972 
973     if (FD->isCanonicalDecl()) { // if canonical add to template's set.
974       // The template that contains the specializations set. It's not safe to
975       // use getCanonicalDecl on Template since it may still be initializing.
976       auto *CanonTemplate = readDeclAs<FunctionTemplateDecl>();
977       // Get the InsertPos by FindNodeOrInsertPos() instead of calling
978       // InsertNode(FTInfo) directly to avoid the getASTContext() call in
979       // FunctionTemplateSpecializationInfo's Profile().
980       // We avoid getASTContext because a decl in the parent hierarchy may
981       // be initializing.
982       llvm::FoldingSetNodeID ID;
983       FunctionTemplateSpecializationInfo::Profile(ID, TemplArgs, C);
984       void *InsertPos = nullptr;
985       FunctionTemplateDecl::Common *CommonPtr = CanonTemplate->getCommonPtr();
986       FunctionTemplateSpecializationInfo *ExistingInfo =
987           CommonPtr->Specializations.FindNodeOrInsertPos(ID, InsertPos);
988       if (InsertPos)
989         CommonPtr->Specializations.InsertNode(FTInfo, InsertPos);
990       else {
991         assert(Reader.getContext().getLangOpts().Modules &&
992                "already deserialized this template specialization");
993         mergeRedeclarable(FD, ExistingInfo->getFunction(), Redecl);
994       }
995     }
996     break;
997   }
998   case FunctionDecl::TK_DependentFunctionTemplateSpecialization: {
999     // Templates.
1000     UnresolvedSet<8> TemplDecls;
1001     unsigned NumTemplates = Record.readInt();
1002     while (NumTemplates--)
1003       TemplDecls.addDecl(readDeclAs<NamedDecl>());
1004 
1005     // Templates args.
1006     TemplateArgumentListInfo TemplArgs;
1007     unsigned NumArgs = Record.readInt();
1008     while (NumArgs--)
1009       TemplArgs.addArgument(Record.readTemplateArgumentLoc());
1010     TemplArgs.setLAngleLoc(readSourceLocation());
1011     TemplArgs.setRAngleLoc(readSourceLocation());
1012 
1013     FD->setDependentTemplateSpecialization(Reader.getContext(),
1014                                            TemplDecls, TemplArgs);
1015     // These are not merged; we don't need to merge redeclarations of dependent
1016     // template friends.
1017     break;
1018   }
1019   }
1020 
1021   // Defer calling `setPure` until merging above has guaranteed we've set
1022   // `DefinitionData` (as this will need to access it).
1023   FD->setPure(Pure);
1024 
1025   // Read in the parameters.
1026   unsigned NumParams = Record.readInt();
1027   SmallVector<ParmVarDecl *, 16> Params;
1028   Params.reserve(NumParams);
1029   for (unsigned I = 0; I != NumParams; ++I)
1030     Params.push_back(readDeclAs<ParmVarDecl>());
1031   FD->setParams(Reader.getContext(), Params);
1032 }
1033 
1034 void ASTDeclReader::VisitObjCMethodDecl(ObjCMethodDecl *MD) {
1035   VisitNamedDecl(MD);
1036   if (Record.readInt()) {
1037     // Load the body on-demand. Most clients won't care, because method
1038     // definitions rarely show up in headers.
1039     Reader.PendingBodies[MD] = GetCurrentCursorOffset();
1040     HasPendingBody = true;
1041   }
1042   MD->setSelfDecl(readDeclAs<ImplicitParamDecl>());
1043   MD->setCmdDecl(readDeclAs<ImplicitParamDecl>());
1044   MD->setInstanceMethod(Record.readInt());
1045   MD->setVariadic(Record.readInt());
1046   MD->setPropertyAccessor(Record.readInt());
1047   MD->setSynthesizedAccessorStub(Record.readInt());
1048   MD->setDefined(Record.readInt());
1049   MD->setOverriding(Record.readInt());
1050   MD->setHasSkippedBody(Record.readInt());
1051 
1052   MD->setIsRedeclaration(Record.readInt());
1053   MD->setHasRedeclaration(Record.readInt());
1054   if (MD->hasRedeclaration())
1055     Reader.getContext().setObjCMethodRedeclaration(MD,
1056                                        readDeclAs<ObjCMethodDecl>());
1057 
1058   MD->setDeclImplementation((ObjCMethodDecl::ImplementationControl)Record.readInt());
1059   MD->setObjCDeclQualifier((Decl::ObjCDeclQualifier)Record.readInt());
1060   MD->setRelatedResultType(Record.readInt());
1061   MD->setReturnType(Record.readType());
1062   MD->setReturnTypeSourceInfo(readTypeSourceInfo());
1063   MD->DeclEndLoc = readSourceLocation();
1064   unsigned NumParams = Record.readInt();
1065   SmallVector<ParmVarDecl *, 16> Params;
1066   Params.reserve(NumParams);
1067   for (unsigned I = 0; I != NumParams; ++I)
1068     Params.push_back(readDeclAs<ParmVarDecl>());
1069 
1070   MD->setSelLocsKind((SelectorLocationsKind)Record.readInt());
1071   unsigned NumStoredSelLocs = Record.readInt();
1072   SmallVector<SourceLocation, 16> SelLocs;
1073   SelLocs.reserve(NumStoredSelLocs);
1074   for (unsigned i = 0; i != NumStoredSelLocs; ++i)
1075     SelLocs.push_back(readSourceLocation());
1076 
1077   MD->setParamsAndSelLocs(Reader.getContext(), Params, SelLocs);
1078 }
1079 
1080 void ASTDeclReader::VisitObjCTypeParamDecl(ObjCTypeParamDecl *D) {
1081   VisitTypedefNameDecl(D);
1082 
1083   D->Variance = Record.readInt();
1084   D->Index = Record.readInt();
1085   D->VarianceLoc = readSourceLocation();
1086   D->ColonLoc = readSourceLocation();
1087 }
1088 
1089 void ASTDeclReader::VisitObjCContainerDecl(ObjCContainerDecl *CD) {
1090   VisitNamedDecl(CD);
1091   CD->setAtStartLoc(readSourceLocation());
1092   CD->setAtEndRange(readSourceRange());
1093 }
1094 
1095 ObjCTypeParamList *ASTDeclReader::ReadObjCTypeParamList() {
1096   unsigned numParams = Record.readInt();
1097   if (numParams == 0)
1098     return nullptr;
1099 
1100   SmallVector<ObjCTypeParamDecl *, 4> typeParams;
1101   typeParams.reserve(numParams);
1102   for (unsigned i = 0; i != numParams; ++i) {
1103     auto *typeParam = readDeclAs<ObjCTypeParamDecl>();
1104     if (!typeParam)
1105       return nullptr;
1106 
1107     typeParams.push_back(typeParam);
1108   }
1109 
1110   SourceLocation lAngleLoc = readSourceLocation();
1111   SourceLocation rAngleLoc = readSourceLocation();
1112 
1113   return ObjCTypeParamList::create(Reader.getContext(), lAngleLoc,
1114                                    typeParams, rAngleLoc);
1115 }
1116 
1117 void ASTDeclReader::ReadObjCDefinitionData(
1118          struct ObjCInterfaceDecl::DefinitionData &Data) {
1119   // Read the superclass.
1120   Data.SuperClassTInfo = readTypeSourceInfo();
1121 
1122   Data.EndLoc = readSourceLocation();
1123   Data.HasDesignatedInitializers = Record.readInt();
1124 
1125   // Read the directly referenced protocols and their SourceLocations.
1126   unsigned NumProtocols = Record.readInt();
1127   SmallVector<ObjCProtocolDecl *, 16> Protocols;
1128   Protocols.reserve(NumProtocols);
1129   for (unsigned I = 0; I != NumProtocols; ++I)
1130     Protocols.push_back(readDeclAs<ObjCProtocolDecl>());
1131   SmallVector<SourceLocation, 16> ProtoLocs;
1132   ProtoLocs.reserve(NumProtocols);
1133   for (unsigned I = 0; I != NumProtocols; ++I)
1134     ProtoLocs.push_back(readSourceLocation());
1135   Data.ReferencedProtocols.set(Protocols.data(), NumProtocols, ProtoLocs.data(),
1136                                Reader.getContext());
1137 
1138   // Read the transitive closure of protocols referenced by this class.
1139   NumProtocols = Record.readInt();
1140   Protocols.clear();
1141   Protocols.reserve(NumProtocols);
1142   for (unsigned I = 0; I != NumProtocols; ++I)
1143     Protocols.push_back(readDeclAs<ObjCProtocolDecl>());
1144   Data.AllReferencedProtocols.set(Protocols.data(), NumProtocols,
1145                                   Reader.getContext());
1146 }
1147 
1148 void ASTDeclReader::MergeDefinitionData(ObjCInterfaceDecl *D,
1149          struct ObjCInterfaceDecl::DefinitionData &&NewDD) {
1150   // FIXME: odr checking?
1151 }
1152 
1153 void ASTDeclReader::VisitObjCInterfaceDecl(ObjCInterfaceDecl *ID) {
1154   RedeclarableResult Redecl = VisitRedeclarable(ID);
1155   VisitObjCContainerDecl(ID);
1156   DeferredTypeID = Record.getGlobalTypeID(Record.readInt());
1157   mergeRedeclarable(ID, Redecl);
1158 
1159   ID->TypeParamList = ReadObjCTypeParamList();
1160   if (Record.readInt()) {
1161     // Read the definition.
1162     ID->allocateDefinitionData();
1163 
1164     ReadObjCDefinitionData(ID->data());
1165     ObjCInterfaceDecl *Canon = ID->getCanonicalDecl();
1166     if (Canon->Data.getPointer()) {
1167       // If we already have a definition, keep the definition invariant and
1168       // merge the data.
1169       MergeDefinitionData(Canon, std::move(ID->data()));
1170       ID->Data = Canon->Data;
1171     } else {
1172       // Set the definition data of the canonical declaration, so other
1173       // redeclarations will see it.
1174       ID->getCanonicalDecl()->Data = ID->Data;
1175 
1176       // We will rebuild this list lazily.
1177       ID->setIvarList(nullptr);
1178     }
1179 
1180     // Note that we have deserialized a definition.
1181     Reader.PendingDefinitions.insert(ID);
1182 
1183     // Note that we've loaded this Objective-C class.
1184     Reader.ObjCClassesLoaded.push_back(ID);
1185   } else {
1186     ID->Data = ID->getCanonicalDecl()->Data;
1187   }
1188 }
1189 
1190 void ASTDeclReader::VisitObjCIvarDecl(ObjCIvarDecl *IVD) {
1191   VisitFieldDecl(IVD);
1192   IVD->setAccessControl((ObjCIvarDecl::AccessControl)Record.readInt());
1193   // This field will be built lazily.
1194   IVD->setNextIvar(nullptr);
1195   bool synth = Record.readInt();
1196   IVD->setSynthesize(synth);
1197 }
1198 
1199 void ASTDeclReader::ReadObjCDefinitionData(
1200          struct ObjCProtocolDecl::DefinitionData &Data) {
1201     unsigned NumProtoRefs = Record.readInt();
1202     SmallVector<ObjCProtocolDecl *, 16> ProtoRefs;
1203     ProtoRefs.reserve(NumProtoRefs);
1204     for (unsigned I = 0; I != NumProtoRefs; ++I)
1205       ProtoRefs.push_back(readDeclAs<ObjCProtocolDecl>());
1206     SmallVector<SourceLocation, 16> ProtoLocs;
1207     ProtoLocs.reserve(NumProtoRefs);
1208     for (unsigned I = 0; I != NumProtoRefs; ++I)
1209       ProtoLocs.push_back(readSourceLocation());
1210     Data.ReferencedProtocols.set(ProtoRefs.data(), NumProtoRefs,
1211                                  ProtoLocs.data(), Reader.getContext());
1212 }
1213 
1214 void ASTDeclReader::MergeDefinitionData(ObjCProtocolDecl *D,
1215          struct ObjCProtocolDecl::DefinitionData &&NewDD) {
1216   // FIXME: odr checking?
1217 }
1218 
1219 void ASTDeclReader::VisitObjCProtocolDecl(ObjCProtocolDecl *PD) {
1220   RedeclarableResult Redecl = VisitRedeclarable(PD);
1221   VisitObjCContainerDecl(PD);
1222   mergeRedeclarable(PD, Redecl);
1223 
1224   if (Record.readInt()) {
1225     // Read the definition.
1226     PD->allocateDefinitionData();
1227 
1228     ReadObjCDefinitionData(PD->data());
1229 
1230     ObjCProtocolDecl *Canon = PD->getCanonicalDecl();
1231     if (Canon->Data.getPointer()) {
1232       // If we already have a definition, keep the definition invariant and
1233       // merge the data.
1234       MergeDefinitionData(Canon, std::move(PD->data()));
1235       PD->Data = Canon->Data;
1236     } else {
1237       // Set the definition data of the canonical declaration, so other
1238       // redeclarations will see it.
1239       PD->getCanonicalDecl()->Data = PD->Data;
1240     }
1241     // Note that we have deserialized a definition.
1242     Reader.PendingDefinitions.insert(PD);
1243   } else {
1244     PD->Data = PD->getCanonicalDecl()->Data;
1245   }
1246 }
1247 
1248 void ASTDeclReader::VisitObjCAtDefsFieldDecl(ObjCAtDefsFieldDecl *FD) {
1249   VisitFieldDecl(FD);
1250 }
1251 
1252 void ASTDeclReader::VisitObjCCategoryDecl(ObjCCategoryDecl *CD) {
1253   VisitObjCContainerDecl(CD);
1254   CD->setCategoryNameLoc(readSourceLocation());
1255   CD->setIvarLBraceLoc(readSourceLocation());
1256   CD->setIvarRBraceLoc(readSourceLocation());
1257 
1258   // Note that this category has been deserialized. We do this before
1259   // deserializing the interface declaration, so that it will consider this
1260   /// category.
1261   Reader.CategoriesDeserialized.insert(CD);
1262 
1263   CD->ClassInterface = readDeclAs<ObjCInterfaceDecl>();
1264   CD->TypeParamList = ReadObjCTypeParamList();
1265   unsigned NumProtoRefs = Record.readInt();
1266   SmallVector<ObjCProtocolDecl *, 16> ProtoRefs;
1267   ProtoRefs.reserve(NumProtoRefs);
1268   for (unsigned I = 0; I != NumProtoRefs; ++I)
1269     ProtoRefs.push_back(readDeclAs<ObjCProtocolDecl>());
1270   SmallVector<SourceLocation, 16> ProtoLocs;
1271   ProtoLocs.reserve(NumProtoRefs);
1272   for (unsigned I = 0; I != NumProtoRefs; ++I)
1273     ProtoLocs.push_back(readSourceLocation());
1274   CD->setProtocolList(ProtoRefs.data(), NumProtoRefs, ProtoLocs.data(),
1275                       Reader.getContext());
1276 
1277   // Protocols in the class extension belong to the class.
1278   if (NumProtoRefs > 0 && CD->ClassInterface && CD->IsClassExtension())
1279     CD->ClassInterface->mergeClassExtensionProtocolList(
1280         (ObjCProtocolDecl *const *)ProtoRefs.data(), NumProtoRefs,
1281         Reader.getContext());
1282 }
1283 
1284 void ASTDeclReader::VisitObjCCompatibleAliasDecl(ObjCCompatibleAliasDecl *CAD) {
1285   VisitNamedDecl(CAD);
1286   CAD->setClassInterface(readDeclAs<ObjCInterfaceDecl>());
1287 }
1288 
1289 void ASTDeclReader::VisitObjCPropertyDecl(ObjCPropertyDecl *D) {
1290   VisitNamedDecl(D);
1291   D->setAtLoc(readSourceLocation());
1292   D->setLParenLoc(readSourceLocation());
1293   QualType T = Record.readType();
1294   TypeSourceInfo *TSI = readTypeSourceInfo();
1295   D->setType(T, TSI);
1296   D->setPropertyAttributes((ObjCPropertyAttribute::Kind)Record.readInt());
1297   D->setPropertyAttributesAsWritten(
1298       (ObjCPropertyAttribute::Kind)Record.readInt());
1299   D->setPropertyImplementation(
1300       (ObjCPropertyDecl::PropertyControl)Record.readInt());
1301   DeclarationName GetterName = Record.readDeclarationName();
1302   SourceLocation GetterLoc = readSourceLocation();
1303   D->setGetterName(GetterName.getObjCSelector(), GetterLoc);
1304   DeclarationName SetterName = Record.readDeclarationName();
1305   SourceLocation SetterLoc = readSourceLocation();
1306   D->setSetterName(SetterName.getObjCSelector(), SetterLoc);
1307   D->setGetterMethodDecl(readDeclAs<ObjCMethodDecl>());
1308   D->setSetterMethodDecl(readDeclAs<ObjCMethodDecl>());
1309   D->setPropertyIvarDecl(readDeclAs<ObjCIvarDecl>());
1310 }
1311 
1312 void ASTDeclReader::VisitObjCImplDecl(ObjCImplDecl *D) {
1313   VisitObjCContainerDecl(D);
1314   D->setClassInterface(readDeclAs<ObjCInterfaceDecl>());
1315 }
1316 
1317 void ASTDeclReader::VisitObjCCategoryImplDecl(ObjCCategoryImplDecl *D) {
1318   VisitObjCImplDecl(D);
1319   D->CategoryNameLoc = readSourceLocation();
1320 }
1321 
1322 void ASTDeclReader::VisitObjCImplementationDecl(ObjCImplementationDecl *D) {
1323   VisitObjCImplDecl(D);
1324   D->setSuperClass(readDeclAs<ObjCInterfaceDecl>());
1325   D->SuperLoc = readSourceLocation();
1326   D->setIvarLBraceLoc(readSourceLocation());
1327   D->setIvarRBraceLoc(readSourceLocation());
1328   D->setHasNonZeroConstructors(Record.readInt());
1329   D->setHasDestructors(Record.readInt());
1330   D->NumIvarInitializers = Record.readInt();
1331   if (D->NumIvarInitializers)
1332     D->IvarInitializers = ReadGlobalOffset();
1333 }
1334 
1335 void ASTDeclReader::VisitObjCPropertyImplDecl(ObjCPropertyImplDecl *D) {
1336   VisitDecl(D);
1337   D->setAtLoc(readSourceLocation());
1338   D->setPropertyDecl(readDeclAs<ObjCPropertyDecl>());
1339   D->PropertyIvarDecl = readDeclAs<ObjCIvarDecl>();
1340   D->IvarLoc = readSourceLocation();
1341   D->setGetterMethodDecl(readDeclAs<ObjCMethodDecl>());
1342   D->setSetterMethodDecl(readDeclAs<ObjCMethodDecl>());
1343   D->setGetterCXXConstructor(Record.readExpr());
1344   D->setSetterCXXAssignment(Record.readExpr());
1345 }
1346 
1347 void ASTDeclReader::VisitFieldDecl(FieldDecl *FD) {
1348   VisitDeclaratorDecl(FD);
1349   FD->Mutable = Record.readInt();
1350 
1351   if (auto ISK = static_cast<FieldDecl::InitStorageKind>(Record.readInt())) {
1352     FD->InitStorage.setInt(ISK);
1353     FD->InitStorage.setPointer(ISK == FieldDecl::ISK_CapturedVLAType
1354                                    ? Record.readType().getAsOpaquePtr()
1355                                    : Record.readExpr());
1356   }
1357 
1358   if (auto *BW = Record.readExpr())
1359     FD->setBitWidth(BW);
1360 
1361   if (!FD->getDeclName()) {
1362     if (auto *Tmpl = readDeclAs<FieldDecl>())
1363       Reader.getContext().setInstantiatedFromUnnamedFieldDecl(FD, Tmpl);
1364   }
1365   mergeMergeable(FD);
1366 }
1367 
1368 void ASTDeclReader::VisitMSPropertyDecl(MSPropertyDecl *PD) {
1369   VisitDeclaratorDecl(PD);
1370   PD->GetterId = Record.readIdentifier();
1371   PD->SetterId = Record.readIdentifier();
1372 }
1373 
1374 void ASTDeclReader::VisitMSGuidDecl(MSGuidDecl *D) {
1375   VisitValueDecl(D);
1376   D->PartVal.Part1 = Record.readInt();
1377   D->PartVal.Part2 = Record.readInt();
1378   D->PartVal.Part3 = Record.readInt();
1379   for (auto &C : D->PartVal.Part4And5)
1380     C = Record.readInt();
1381 
1382   // Add this GUID to the AST context's lookup structure, and merge if needed.
1383   if (MSGuidDecl *Existing = Reader.getContext().MSGuidDecls.GetOrInsertNode(D))
1384     Reader.getContext().setPrimaryMergedDecl(D, Existing->getCanonicalDecl());
1385 }
1386 
1387 void ASTDeclReader::VisitTemplateParamObjectDecl(TemplateParamObjectDecl *D) {
1388   VisitValueDecl(D);
1389   D->Value = Record.readAPValue();
1390 
1391   // Add this template parameter object to the AST context's lookup structure,
1392   // and merge if needed.
1393   if (TemplateParamObjectDecl *Existing =
1394           Reader.getContext().TemplateParamObjectDecls.GetOrInsertNode(D))
1395     Reader.getContext().setPrimaryMergedDecl(D, Existing->getCanonicalDecl());
1396 }
1397 
1398 void ASTDeclReader::VisitIndirectFieldDecl(IndirectFieldDecl *FD) {
1399   VisitValueDecl(FD);
1400 
1401   FD->ChainingSize = Record.readInt();
1402   assert(FD->ChainingSize >= 2 && "Anonymous chaining must be >= 2");
1403   FD->Chaining = new (Reader.getContext())NamedDecl*[FD->ChainingSize];
1404 
1405   for (unsigned I = 0; I != FD->ChainingSize; ++I)
1406     FD->Chaining[I] = readDeclAs<NamedDecl>();
1407 
1408   mergeMergeable(FD);
1409 }
1410 
1411 ASTDeclReader::RedeclarableResult ASTDeclReader::VisitVarDeclImpl(VarDecl *VD) {
1412   RedeclarableResult Redecl = VisitRedeclarable(VD);
1413   VisitDeclaratorDecl(VD);
1414 
1415   VD->VarDeclBits.SClass = (StorageClass)Record.readInt();
1416   VD->VarDeclBits.TSCSpec = Record.readInt();
1417   VD->VarDeclBits.InitStyle = Record.readInt();
1418   VD->VarDeclBits.ARCPseudoStrong = Record.readInt();
1419   if (!isa<ParmVarDecl>(VD)) {
1420     VD->NonParmVarDeclBits.IsThisDeclarationADemotedDefinition =
1421         Record.readInt();
1422     VD->NonParmVarDeclBits.ExceptionVar = Record.readInt();
1423     VD->NonParmVarDeclBits.NRVOVariable = Record.readInt();
1424     VD->NonParmVarDeclBits.CXXForRangeDecl = Record.readInt();
1425     VD->NonParmVarDeclBits.ObjCForDecl = Record.readInt();
1426     VD->NonParmVarDeclBits.IsInline = Record.readInt();
1427     VD->NonParmVarDeclBits.IsInlineSpecified = Record.readInt();
1428     VD->NonParmVarDeclBits.IsConstexpr = Record.readInt();
1429     VD->NonParmVarDeclBits.IsInitCapture = Record.readInt();
1430     VD->NonParmVarDeclBits.PreviousDeclInSameBlockScope = Record.readInt();
1431     VD->NonParmVarDeclBits.ImplicitParamKind = Record.readInt();
1432     VD->NonParmVarDeclBits.EscapingByref = Record.readInt();
1433   }
1434   auto VarLinkage = Linkage(Record.readInt());
1435   VD->setCachedLinkage(VarLinkage);
1436 
1437   // Reconstruct the one piece of the IdentifierNamespace that we need.
1438   if (VD->getStorageClass() == SC_Extern && VarLinkage != NoLinkage &&
1439       VD->getLexicalDeclContext()->isFunctionOrMethod())
1440     VD->setLocalExternDecl();
1441 
1442   if (uint64_t Val = Record.readInt()) {
1443     VD->setInit(Record.readExpr());
1444     if (Val != 1) {
1445       EvaluatedStmt *Eval = VD->ensureEvaluatedStmt();
1446       Eval->HasConstantInitialization = (Val & 2) != 0;
1447       Eval->HasConstantDestruction = (Val & 4) != 0;
1448     }
1449   }
1450 
1451   if (VD->hasAttr<BlocksAttr>() && VD->getType()->getAsCXXRecordDecl()) {
1452     Expr *CopyExpr = Record.readExpr();
1453     if (CopyExpr)
1454       Reader.getContext().setBlockVarCopyInit(VD, CopyExpr, Record.readInt());
1455   }
1456 
1457   if (VD->getStorageDuration() == SD_Static && Record.readInt()) {
1458     Reader.DefinitionSource[VD] =
1459         Loc.F->Kind == ModuleKind::MK_MainFile ||
1460         Reader.getContext().getLangOpts().BuildingPCHWithObjectFile;
1461   }
1462 
1463   enum VarKind {
1464     VarNotTemplate = 0, VarTemplate, StaticDataMemberSpecialization
1465   };
1466   switch ((VarKind)Record.readInt()) {
1467   case VarNotTemplate:
1468     // Only true variables (not parameters or implicit parameters) can be
1469     // merged; the other kinds are not really redeclarable at all.
1470     if (!isa<ParmVarDecl>(VD) && !isa<ImplicitParamDecl>(VD) &&
1471         !isa<VarTemplateSpecializationDecl>(VD))
1472       mergeRedeclarable(VD, Redecl);
1473     break;
1474   case VarTemplate:
1475     // Merged when we merge the template.
1476     VD->setDescribedVarTemplate(readDeclAs<VarTemplateDecl>());
1477     break;
1478   case StaticDataMemberSpecialization: { // HasMemberSpecializationInfo.
1479     auto *Tmpl = readDeclAs<VarDecl>();
1480     auto TSK = (TemplateSpecializationKind)Record.readInt();
1481     SourceLocation POI = readSourceLocation();
1482     Reader.getContext().setInstantiatedFromStaticDataMember(VD, Tmpl, TSK,POI);
1483     mergeRedeclarable(VD, Redecl);
1484     break;
1485   }
1486   }
1487 
1488   return Redecl;
1489 }
1490 
1491 void ASTDeclReader::VisitImplicitParamDecl(ImplicitParamDecl *PD) {
1492   VisitVarDecl(PD);
1493 }
1494 
1495 void ASTDeclReader::VisitParmVarDecl(ParmVarDecl *PD) {
1496   VisitVarDecl(PD);
1497   unsigned isObjCMethodParam = Record.readInt();
1498   unsigned scopeDepth = Record.readInt();
1499   unsigned scopeIndex = Record.readInt();
1500   unsigned declQualifier = Record.readInt();
1501   if (isObjCMethodParam) {
1502     assert(scopeDepth == 0);
1503     PD->setObjCMethodScopeInfo(scopeIndex);
1504     PD->ParmVarDeclBits.ScopeDepthOrObjCQuals = declQualifier;
1505   } else {
1506     PD->setScopeInfo(scopeDepth, scopeIndex);
1507   }
1508   PD->ParmVarDeclBits.IsKNRPromoted = Record.readInt();
1509   PD->ParmVarDeclBits.HasInheritedDefaultArg = Record.readInt();
1510   if (Record.readInt()) // hasUninstantiatedDefaultArg.
1511     PD->setUninstantiatedDefaultArg(Record.readExpr());
1512 
1513   // FIXME: If this is a redeclaration of a function from another module, handle
1514   // inheritance of default arguments.
1515 }
1516 
1517 void ASTDeclReader::VisitDecompositionDecl(DecompositionDecl *DD) {
1518   VisitVarDecl(DD);
1519   auto **BDs = DD->getTrailingObjects<BindingDecl *>();
1520   for (unsigned I = 0; I != DD->NumBindings; ++I) {
1521     BDs[I] = readDeclAs<BindingDecl>();
1522     BDs[I]->setDecomposedDecl(DD);
1523   }
1524 }
1525 
1526 void ASTDeclReader::VisitBindingDecl(BindingDecl *BD) {
1527   VisitValueDecl(BD);
1528   BD->Binding = Record.readExpr();
1529 }
1530 
1531 void ASTDeclReader::VisitFileScopeAsmDecl(FileScopeAsmDecl *AD) {
1532   VisitDecl(AD);
1533   AD->setAsmString(cast<StringLiteral>(Record.readExpr()));
1534   AD->setRParenLoc(readSourceLocation());
1535 }
1536 
1537 void ASTDeclReader::VisitBlockDecl(BlockDecl *BD) {
1538   VisitDecl(BD);
1539   BD->setBody(cast_or_null<CompoundStmt>(Record.readStmt()));
1540   BD->setSignatureAsWritten(readTypeSourceInfo());
1541   unsigned NumParams = Record.readInt();
1542   SmallVector<ParmVarDecl *, 16> Params;
1543   Params.reserve(NumParams);
1544   for (unsigned I = 0; I != NumParams; ++I)
1545     Params.push_back(readDeclAs<ParmVarDecl>());
1546   BD->setParams(Params);
1547 
1548   BD->setIsVariadic(Record.readInt());
1549   BD->setBlockMissingReturnType(Record.readInt());
1550   BD->setIsConversionFromLambda(Record.readInt());
1551   BD->setDoesNotEscape(Record.readInt());
1552   BD->setCanAvoidCopyToHeap(Record.readInt());
1553 
1554   bool capturesCXXThis = Record.readInt();
1555   unsigned numCaptures = Record.readInt();
1556   SmallVector<BlockDecl::Capture, 16> captures;
1557   captures.reserve(numCaptures);
1558   for (unsigned i = 0; i != numCaptures; ++i) {
1559     auto *decl = readDeclAs<VarDecl>();
1560     unsigned flags = Record.readInt();
1561     bool byRef = (flags & 1);
1562     bool nested = (flags & 2);
1563     Expr *copyExpr = ((flags & 4) ? Record.readExpr() : nullptr);
1564 
1565     captures.push_back(BlockDecl::Capture(decl, byRef, nested, copyExpr));
1566   }
1567   BD->setCaptures(Reader.getContext(), captures, capturesCXXThis);
1568 }
1569 
1570 void ASTDeclReader::VisitCapturedDecl(CapturedDecl *CD) {
1571   VisitDecl(CD);
1572   unsigned ContextParamPos = Record.readInt();
1573   CD->setNothrow(Record.readInt() != 0);
1574   // Body is set by VisitCapturedStmt.
1575   for (unsigned I = 0; I < CD->NumParams; ++I) {
1576     if (I != ContextParamPos)
1577       CD->setParam(I, readDeclAs<ImplicitParamDecl>());
1578     else
1579       CD->setContextParam(I, readDeclAs<ImplicitParamDecl>());
1580   }
1581 }
1582 
1583 void ASTDeclReader::VisitLinkageSpecDecl(LinkageSpecDecl *D) {
1584   VisitDecl(D);
1585   D->setLanguage((LinkageSpecDecl::LanguageIDs)Record.readInt());
1586   D->setExternLoc(readSourceLocation());
1587   D->setRBraceLoc(readSourceLocation());
1588 }
1589 
1590 void ASTDeclReader::VisitExportDecl(ExportDecl *D) {
1591   VisitDecl(D);
1592   D->RBraceLoc = readSourceLocation();
1593 }
1594 
1595 void ASTDeclReader::VisitLabelDecl(LabelDecl *D) {
1596   VisitNamedDecl(D);
1597   D->setLocStart(readSourceLocation());
1598 }
1599 
1600 void ASTDeclReader::VisitNamespaceDecl(NamespaceDecl *D) {
1601   RedeclarableResult Redecl = VisitRedeclarable(D);
1602   VisitNamedDecl(D);
1603   D->setInline(Record.readInt());
1604   D->LocStart = readSourceLocation();
1605   D->RBraceLoc = readSourceLocation();
1606 
1607   // Defer loading the anonymous namespace until we've finished merging
1608   // this namespace; loading it might load a later declaration of the
1609   // same namespace, and we have an invariant that older declarations
1610   // get merged before newer ones try to merge.
1611   GlobalDeclID AnonNamespace = 0;
1612   if (Redecl.getFirstID() == ThisDeclID) {
1613     AnonNamespace = readDeclID();
1614   } else {
1615     // Link this namespace back to the first declaration, which has already
1616     // been deserialized.
1617     D->AnonOrFirstNamespaceAndInline.setPointer(D->getFirstDecl());
1618   }
1619 
1620   mergeRedeclarable(D, Redecl);
1621 
1622   if (AnonNamespace) {
1623     // Each module has its own anonymous namespace, which is disjoint from
1624     // any other module's anonymous namespaces, so don't attach the anonymous
1625     // namespace at all.
1626     auto *Anon = cast<NamespaceDecl>(Reader.GetDecl(AnonNamespace));
1627     if (!Record.isModule())
1628       D->setAnonymousNamespace(Anon);
1629   }
1630 }
1631 
1632 void ASTDeclReader::VisitNamespaceAliasDecl(NamespaceAliasDecl *D) {
1633   RedeclarableResult Redecl = VisitRedeclarable(D);
1634   VisitNamedDecl(D);
1635   D->NamespaceLoc = readSourceLocation();
1636   D->IdentLoc = readSourceLocation();
1637   D->QualifierLoc = Record.readNestedNameSpecifierLoc();
1638   D->Namespace = readDeclAs<NamedDecl>();
1639   mergeRedeclarable(D, Redecl);
1640 }
1641 
1642 void ASTDeclReader::VisitUsingDecl(UsingDecl *D) {
1643   VisitNamedDecl(D);
1644   D->setUsingLoc(readSourceLocation());
1645   D->QualifierLoc = Record.readNestedNameSpecifierLoc();
1646   D->DNLoc = Record.readDeclarationNameLoc(D->getDeclName());
1647   D->FirstUsingShadow.setPointer(readDeclAs<UsingShadowDecl>());
1648   D->setTypename(Record.readInt());
1649   if (auto *Pattern = readDeclAs<NamedDecl>())
1650     Reader.getContext().setInstantiatedFromUsingDecl(D, Pattern);
1651   mergeMergeable(D);
1652 }
1653 
1654 void ASTDeclReader::VisitUsingPackDecl(UsingPackDecl *D) {
1655   VisitNamedDecl(D);
1656   D->InstantiatedFrom = readDeclAs<NamedDecl>();
1657   auto **Expansions = D->getTrailingObjects<NamedDecl *>();
1658   for (unsigned I = 0; I != D->NumExpansions; ++I)
1659     Expansions[I] = readDeclAs<NamedDecl>();
1660   mergeMergeable(D);
1661 }
1662 
1663 void ASTDeclReader::VisitUsingShadowDecl(UsingShadowDecl *D) {
1664   RedeclarableResult Redecl = VisitRedeclarable(D);
1665   VisitNamedDecl(D);
1666   D->Underlying = readDeclAs<NamedDecl>();
1667   D->IdentifierNamespace = Record.readInt();
1668   D->UsingOrNextShadow = readDeclAs<NamedDecl>();
1669   auto *Pattern = readDeclAs<UsingShadowDecl>();
1670   if (Pattern)
1671     Reader.getContext().setInstantiatedFromUsingShadowDecl(D, Pattern);
1672   mergeRedeclarable(D, Redecl);
1673 }
1674 
1675 void ASTDeclReader::VisitConstructorUsingShadowDecl(
1676     ConstructorUsingShadowDecl *D) {
1677   VisitUsingShadowDecl(D);
1678   D->NominatedBaseClassShadowDecl = readDeclAs<ConstructorUsingShadowDecl>();
1679   D->ConstructedBaseClassShadowDecl = readDeclAs<ConstructorUsingShadowDecl>();
1680   D->IsVirtual = Record.readInt();
1681 }
1682 
1683 void ASTDeclReader::VisitUsingDirectiveDecl(UsingDirectiveDecl *D) {
1684   VisitNamedDecl(D);
1685   D->UsingLoc = readSourceLocation();
1686   D->NamespaceLoc = readSourceLocation();
1687   D->QualifierLoc = Record.readNestedNameSpecifierLoc();
1688   D->NominatedNamespace = readDeclAs<NamedDecl>();
1689   D->CommonAncestor = readDeclAs<DeclContext>();
1690 }
1691 
1692 void ASTDeclReader::VisitUnresolvedUsingValueDecl(UnresolvedUsingValueDecl *D) {
1693   VisitValueDecl(D);
1694   D->setUsingLoc(readSourceLocation());
1695   D->QualifierLoc = Record.readNestedNameSpecifierLoc();
1696   D->DNLoc = Record.readDeclarationNameLoc(D->getDeclName());
1697   D->EllipsisLoc = readSourceLocation();
1698   mergeMergeable(D);
1699 }
1700 
1701 void ASTDeclReader::VisitUnresolvedUsingTypenameDecl(
1702                                                UnresolvedUsingTypenameDecl *D) {
1703   VisitTypeDecl(D);
1704   D->TypenameLocation = readSourceLocation();
1705   D->QualifierLoc = Record.readNestedNameSpecifierLoc();
1706   D->EllipsisLoc = readSourceLocation();
1707   mergeMergeable(D);
1708 }
1709 
1710 void ASTDeclReader::ReadCXXDefinitionData(
1711     struct CXXRecordDecl::DefinitionData &Data, const CXXRecordDecl *D) {
1712   #define FIELD(Name, Width, Merge) \
1713   Data.Name = Record.readInt();
1714   #include "clang/AST/CXXRecordDeclDefinitionBits.def"
1715 
1716   // Note: the caller has deserialized the IsLambda bit already.
1717   Data.ODRHash = Record.readInt();
1718   Data.HasODRHash = true;
1719 
1720   if (Record.readInt()) {
1721     Reader.DefinitionSource[D] =
1722         Loc.F->Kind == ModuleKind::MK_MainFile ||
1723         Reader.getContext().getLangOpts().BuildingPCHWithObjectFile;
1724   }
1725 
1726   Data.NumBases = Record.readInt();
1727   if (Data.NumBases)
1728     Data.Bases = ReadGlobalOffset();
1729   Data.NumVBases = Record.readInt();
1730   if (Data.NumVBases)
1731     Data.VBases = ReadGlobalOffset();
1732 
1733   Record.readUnresolvedSet(Data.Conversions);
1734   Data.ComputedVisibleConversions = Record.readInt();
1735   if (Data.ComputedVisibleConversions)
1736     Record.readUnresolvedSet(Data.VisibleConversions);
1737   assert(Data.Definition && "Data.Definition should be already set!");
1738   Data.FirstFriend = readDeclID();
1739 
1740   if (Data.IsLambda) {
1741     using Capture = LambdaCapture;
1742 
1743     auto &Lambda = static_cast<CXXRecordDecl::LambdaDefinitionData &>(Data);
1744     Lambda.Dependent = Record.readInt();
1745     Lambda.IsGenericLambda = Record.readInt();
1746     Lambda.CaptureDefault = Record.readInt();
1747     Lambda.NumCaptures = Record.readInt();
1748     Lambda.NumExplicitCaptures = Record.readInt();
1749     Lambda.HasKnownInternalLinkage = Record.readInt();
1750     Lambda.ManglingNumber = Record.readInt();
1751     D->setDeviceLambdaManglingNumber(Record.readInt());
1752     Lambda.ContextDecl = readDeclID();
1753     Lambda.Captures = (Capture *)Reader.getContext().Allocate(
1754         sizeof(Capture) * Lambda.NumCaptures);
1755     Capture *ToCapture = Lambda.Captures;
1756     Lambda.MethodTyInfo = readTypeSourceInfo();
1757     for (unsigned I = 0, N = Lambda.NumCaptures; I != N; ++I) {
1758       SourceLocation Loc = readSourceLocation();
1759       bool IsImplicit = Record.readInt();
1760       auto Kind = static_cast<LambdaCaptureKind>(Record.readInt());
1761       switch (Kind) {
1762       case LCK_StarThis:
1763       case LCK_This:
1764       case LCK_VLAType:
1765         *ToCapture++ = Capture(Loc, IsImplicit, Kind, nullptr,SourceLocation());
1766         break;
1767       case LCK_ByCopy:
1768       case LCK_ByRef:
1769         auto *Var = readDeclAs<VarDecl>();
1770         SourceLocation EllipsisLoc = readSourceLocation();
1771         *ToCapture++ = Capture(Loc, IsImplicit, Kind, Var, EllipsisLoc);
1772         break;
1773       }
1774     }
1775   }
1776 }
1777 
1778 void ASTDeclReader::MergeDefinitionData(
1779     CXXRecordDecl *D, struct CXXRecordDecl::DefinitionData &&MergeDD) {
1780   assert(D->DefinitionData &&
1781          "merging class definition into non-definition");
1782   auto &DD = *D->DefinitionData;
1783 
1784   if (DD.Definition != MergeDD.Definition) {
1785     // Track that we merged the definitions.
1786     Reader.MergedDeclContexts.insert(std::make_pair(MergeDD.Definition,
1787                                                     DD.Definition));
1788     Reader.PendingDefinitions.erase(MergeDD.Definition);
1789     MergeDD.Definition->setCompleteDefinition(false);
1790     Reader.mergeDefinitionVisibility(DD.Definition, MergeDD.Definition);
1791     assert(Reader.Lookups.find(MergeDD.Definition) == Reader.Lookups.end() &&
1792            "already loaded pending lookups for merged definition");
1793   }
1794 
1795   auto PFDI = Reader.PendingFakeDefinitionData.find(&DD);
1796   if (PFDI != Reader.PendingFakeDefinitionData.end() &&
1797       PFDI->second == ASTReader::PendingFakeDefinitionKind::Fake) {
1798     // We faked up this definition data because we found a class for which we'd
1799     // not yet loaded the definition. Replace it with the real thing now.
1800     assert(!DD.IsLambda && !MergeDD.IsLambda && "faked up lambda definition?");
1801     PFDI->second = ASTReader::PendingFakeDefinitionKind::FakeLoaded;
1802 
1803     // Don't change which declaration is the definition; that is required
1804     // to be invariant once we select it.
1805     auto *Def = DD.Definition;
1806     DD = std::move(MergeDD);
1807     DD.Definition = Def;
1808     return;
1809   }
1810 
1811   bool DetectedOdrViolation = false;
1812 
1813   #define FIELD(Name, Width, Merge) Merge(Name)
1814   #define MERGE_OR(Field) DD.Field |= MergeDD.Field;
1815   #define NO_MERGE(Field) \
1816     DetectedOdrViolation |= DD.Field != MergeDD.Field; \
1817     MERGE_OR(Field)
1818   #include "clang/AST/CXXRecordDeclDefinitionBits.def"
1819   NO_MERGE(IsLambda)
1820   #undef NO_MERGE
1821   #undef MERGE_OR
1822 
1823   if (DD.NumBases != MergeDD.NumBases || DD.NumVBases != MergeDD.NumVBases)
1824     DetectedOdrViolation = true;
1825   // FIXME: Issue a diagnostic if the base classes don't match when we come
1826   // to lazily load them.
1827 
1828   // FIXME: Issue a diagnostic if the list of conversion functions doesn't
1829   // match when we come to lazily load them.
1830   if (MergeDD.ComputedVisibleConversions && !DD.ComputedVisibleConversions) {
1831     DD.VisibleConversions = std::move(MergeDD.VisibleConversions);
1832     DD.ComputedVisibleConversions = true;
1833   }
1834 
1835   // FIXME: Issue a diagnostic if FirstFriend doesn't match when we come to
1836   // lazily load it.
1837 
1838   if (DD.IsLambda) {
1839     // FIXME: ODR-checking for merging lambdas (this happens, for instance,
1840     // when they occur within the body of a function template specialization).
1841   }
1842 
1843   if (D->getODRHash() != MergeDD.ODRHash) {
1844     DetectedOdrViolation = true;
1845   }
1846 
1847   if (DetectedOdrViolation)
1848     Reader.PendingOdrMergeFailures[DD.Definition].push_back(
1849         {MergeDD.Definition, &MergeDD});
1850 }
1851 
1852 void ASTDeclReader::ReadCXXRecordDefinition(CXXRecordDecl *D, bool Update) {
1853   struct CXXRecordDecl::DefinitionData *DD;
1854   ASTContext &C = Reader.getContext();
1855 
1856   // Determine whether this is a lambda closure type, so that we can
1857   // allocate the appropriate DefinitionData structure.
1858   bool IsLambda = Record.readInt();
1859   if (IsLambda)
1860     DD = new (C) CXXRecordDecl::LambdaDefinitionData(D, nullptr, false, false,
1861                                                      LCD_None);
1862   else
1863     DD = new (C) struct CXXRecordDecl::DefinitionData(D);
1864 
1865   CXXRecordDecl *Canon = D->getCanonicalDecl();
1866   // Set decl definition data before reading it, so that during deserialization
1867   // when we read CXXRecordDecl, it already has definition data and we don't
1868   // set fake one.
1869   if (!Canon->DefinitionData)
1870     Canon->DefinitionData = DD;
1871   D->DefinitionData = Canon->DefinitionData;
1872   ReadCXXDefinitionData(*DD, D);
1873 
1874   // We might already have a different definition for this record. This can
1875   // happen either because we're reading an update record, or because we've
1876   // already done some merging. Either way, just merge into it.
1877   if (Canon->DefinitionData != DD) {
1878     MergeDefinitionData(Canon, std::move(*DD));
1879     return;
1880   }
1881 
1882   // Mark this declaration as being a definition.
1883   D->setCompleteDefinition(true);
1884 
1885   // If this is not the first declaration or is an update record, we can have
1886   // other redeclarations already. Make a note that we need to propagate the
1887   // DefinitionData pointer onto them.
1888   if (Update || Canon != D)
1889     Reader.PendingDefinitions.insert(D);
1890 }
1891 
1892 ASTDeclReader::RedeclarableResult
1893 ASTDeclReader::VisitCXXRecordDeclImpl(CXXRecordDecl *D) {
1894   RedeclarableResult Redecl = VisitRecordDeclImpl(D);
1895 
1896   ASTContext &C = Reader.getContext();
1897 
1898   enum CXXRecKind {
1899     CXXRecNotTemplate = 0, CXXRecTemplate, CXXRecMemberSpecialization
1900   };
1901   switch ((CXXRecKind)Record.readInt()) {
1902   case CXXRecNotTemplate:
1903     // Merged when we merge the folding set entry in the primary template.
1904     if (!isa<ClassTemplateSpecializationDecl>(D))
1905       mergeRedeclarable(D, Redecl);
1906     break;
1907   case CXXRecTemplate: {
1908     // Merged when we merge the template.
1909     auto *Template = readDeclAs<ClassTemplateDecl>();
1910     D->TemplateOrInstantiation = Template;
1911     if (!Template->getTemplatedDecl()) {
1912       // We've not actually loaded the ClassTemplateDecl yet, because we're
1913       // currently being loaded as its pattern. Rely on it to set up our
1914       // TypeForDecl (see VisitClassTemplateDecl).
1915       //
1916       // Beware: we do not yet know our canonical declaration, and may still
1917       // get merged once the surrounding class template has got off the ground.
1918       DeferredTypeID = 0;
1919     }
1920     break;
1921   }
1922   case CXXRecMemberSpecialization: {
1923     auto *RD = readDeclAs<CXXRecordDecl>();
1924     auto TSK = (TemplateSpecializationKind)Record.readInt();
1925     SourceLocation POI = readSourceLocation();
1926     MemberSpecializationInfo *MSI = new (C) MemberSpecializationInfo(RD, TSK);
1927     MSI->setPointOfInstantiation(POI);
1928     D->TemplateOrInstantiation = MSI;
1929     mergeRedeclarable(D, Redecl);
1930     break;
1931   }
1932   }
1933 
1934   bool WasDefinition = Record.readInt();
1935   if (WasDefinition)
1936     ReadCXXRecordDefinition(D, /*Update*/false);
1937   else
1938     // Propagate DefinitionData pointer from the canonical declaration.
1939     D->DefinitionData = D->getCanonicalDecl()->DefinitionData;
1940 
1941   // Lazily load the key function to avoid deserializing every method so we can
1942   // compute it.
1943   if (WasDefinition) {
1944     DeclID KeyFn = readDeclID();
1945     if (KeyFn && D->isCompleteDefinition())
1946       // FIXME: This is wrong for the ARM ABI, where some other module may have
1947       // made this function no longer be a key function. We need an update
1948       // record or similar for that case.
1949       C.KeyFunctions[D] = KeyFn;
1950   }
1951 
1952   return Redecl;
1953 }
1954 
1955 void ASTDeclReader::VisitCXXDeductionGuideDecl(CXXDeductionGuideDecl *D) {
1956   D->setExplicitSpecifier(Record.readExplicitSpec());
1957   VisitFunctionDecl(D);
1958   D->setIsCopyDeductionCandidate(Record.readInt());
1959 }
1960 
1961 void ASTDeclReader::VisitCXXMethodDecl(CXXMethodDecl *D) {
1962   VisitFunctionDecl(D);
1963 
1964   unsigned NumOverridenMethods = Record.readInt();
1965   if (D->isCanonicalDecl()) {
1966     while (NumOverridenMethods--) {
1967       // Avoid invariant checking of CXXMethodDecl::addOverriddenMethod,
1968       // MD may be initializing.
1969       if (auto *MD = readDeclAs<CXXMethodDecl>())
1970         Reader.getContext().addOverriddenMethod(D, MD->getCanonicalDecl());
1971     }
1972   } else {
1973     // We don't care about which declarations this used to override; we get
1974     // the relevant information from the canonical declaration.
1975     Record.skipInts(NumOverridenMethods);
1976   }
1977 }
1978 
1979 void ASTDeclReader::VisitCXXConstructorDecl(CXXConstructorDecl *D) {
1980   // We need the inherited constructor information to merge the declaration,
1981   // so we have to read it before we call VisitCXXMethodDecl.
1982   D->setExplicitSpecifier(Record.readExplicitSpec());
1983   if (D->isInheritingConstructor()) {
1984     auto *Shadow = readDeclAs<ConstructorUsingShadowDecl>();
1985     auto *Ctor = readDeclAs<CXXConstructorDecl>();
1986     *D->getTrailingObjects<InheritedConstructor>() =
1987         InheritedConstructor(Shadow, Ctor);
1988   }
1989 
1990   VisitCXXMethodDecl(D);
1991 }
1992 
1993 void ASTDeclReader::VisitCXXDestructorDecl(CXXDestructorDecl *D) {
1994   VisitCXXMethodDecl(D);
1995 
1996   if (auto *OperatorDelete = readDeclAs<FunctionDecl>()) {
1997     CXXDestructorDecl *Canon = D->getCanonicalDecl();
1998     auto *ThisArg = Record.readExpr();
1999     // FIXME: Check consistency if we have an old and new operator delete.
2000     if (!Canon->OperatorDelete) {
2001       Canon->OperatorDelete = OperatorDelete;
2002       Canon->OperatorDeleteThisArg = ThisArg;
2003     }
2004   }
2005 }
2006 
2007 void ASTDeclReader::VisitCXXConversionDecl(CXXConversionDecl *D) {
2008   D->setExplicitSpecifier(Record.readExplicitSpec());
2009   VisitCXXMethodDecl(D);
2010 }
2011 
2012 void ASTDeclReader::VisitImportDecl(ImportDecl *D) {
2013   VisitDecl(D);
2014   D->ImportedModule = readModule();
2015   D->setImportComplete(Record.readInt());
2016   auto *StoredLocs = D->getTrailingObjects<SourceLocation>();
2017   for (unsigned I = 0, N = Record.back(); I != N; ++I)
2018     StoredLocs[I] = readSourceLocation();
2019   Record.skipInts(1); // The number of stored source locations.
2020 }
2021 
2022 void ASTDeclReader::VisitAccessSpecDecl(AccessSpecDecl *D) {
2023   VisitDecl(D);
2024   D->setColonLoc(readSourceLocation());
2025 }
2026 
2027 void ASTDeclReader::VisitFriendDecl(FriendDecl *D) {
2028   VisitDecl(D);
2029   if (Record.readInt()) // hasFriendDecl
2030     D->Friend = readDeclAs<NamedDecl>();
2031   else
2032     D->Friend = readTypeSourceInfo();
2033   for (unsigned i = 0; i != D->NumTPLists; ++i)
2034     D->getTrailingObjects<TemplateParameterList *>()[i] =
2035         Record.readTemplateParameterList();
2036   D->NextFriend = readDeclID();
2037   D->UnsupportedFriend = (Record.readInt() != 0);
2038   D->FriendLoc = readSourceLocation();
2039 }
2040 
2041 void ASTDeclReader::VisitFriendTemplateDecl(FriendTemplateDecl *D) {
2042   VisitDecl(D);
2043   unsigned NumParams = Record.readInt();
2044   D->NumParams = NumParams;
2045   D->Params = new TemplateParameterList*[NumParams];
2046   for (unsigned i = 0; i != NumParams; ++i)
2047     D->Params[i] = Record.readTemplateParameterList();
2048   if (Record.readInt()) // HasFriendDecl
2049     D->Friend = readDeclAs<NamedDecl>();
2050   else
2051     D->Friend = readTypeSourceInfo();
2052   D->FriendLoc = readSourceLocation();
2053 }
2054 
2055 DeclID ASTDeclReader::VisitTemplateDecl(TemplateDecl *D) {
2056   VisitNamedDecl(D);
2057 
2058   DeclID PatternID = readDeclID();
2059   auto *TemplatedDecl = cast_or_null<NamedDecl>(Reader.GetDecl(PatternID));
2060   TemplateParameterList *TemplateParams = Record.readTemplateParameterList();
2061   D->init(TemplatedDecl, TemplateParams);
2062 
2063   return PatternID;
2064 }
2065 
2066 void ASTDeclReader::VisitConceptDecl(ConceptDecl *D) {
2067   VisitTemplateDecl(D);
2068   D->ConstraintExpr = Record.readExpr();
2069   mergeMergeable(D);
2070 }
2071 
2072 void ASTDeclReader::VisitRequiresExprBodyDecl(RequiresExprBodyDecl *D) {
2073 }
2074 
2075 ASTDeclReader::RedeclarableResult
2076 ASTDeclReader::VisitRedeclarableTemplateDecl(RedeclarableTemplateDecl *D) {
2077   RedeclarableResult Redecl = VisitRedeclarable(D);
2078 
2079   // Make sure we've allocated the Common pointer first. We do this before
2080   // VisitTemplateDecl so that getCommonPtr() can be used during initialization.
2081   RedeclarableTemplateDecl *CanonD = D->getCanonicalDecl();
2082   if (!CanonD->Common) {
2083     CanonD->Common = CanonD->newCommon(Reader.getContext());
2084     Reader.PendingDefinitions.insert(CanonD);
2085   }
2086   D->Common = CanonD->Common;
2087 
2088   // If this is the first declaration of the template, fill in the information
2089   // for the 'common' pointer.
2090   if (ThisDeclID == Redecl.getFirstID()) {
2091     if (auto *RTD = readDeclAs<RedeclarableTemplateDecl>()) {
2092       assert(RTD->getKind() == D->getKind() &&
2093              "InstantiatedFromMemberTemplate kind mismatch");
2094       D->setInstantiatedFromMemberTemplate(RTD);
2095       if (Record.readInt())
2096         D->setMemberSpecialization();
2097     }
2098   }
2099 
2100   DeclID PatternID = VisitTemplateDecl(D);
2101   D->IdentifierNamespace = Record.readInt();
2102 
2103   mergeRedeclarable(D, Redecl, PatternID);
2104 
2105   // If we merged the template with a prior declaration chain, merge the common
2106   // pointer.
2107   // FIXME: Actually merge here, don't just overwrite.
2108   D->Common = D->getCanonicalDecl()->Common;
2109 
2110   return Redecl;
2111 }
2112 
2113 void ASTDeclReader::VisitClassTemplateDecl(ClassTemplateDecl *D) {
2114   RedeclarableResult Redecl = VisitRedeclarableTemplateDecl(D);
2115 
2116   if (ThisDeclID == Redecl.getFirstID()) {
2117     // This ClassTemplateDecl owns a CommonPtr; read it to keep track of all of
2118     // the specializations.
2119     SmallVector<serialization::DeclID, 32> SpecIDs;
2120     readDeclIDList(SpecIDs);
2121     ASTDeclReader::AddLazySpecializations(D, SpecIDs);
2122   }
2123 
2124   if (D->getTemplatedDecl()->TemplateOrInstantiation) {
2125     // We were loaded before our templated declaration was. We've not set up
2126     // its corresponding type yet (see VisitCXXRecordDeclImpl), so reconstruct
2127     // it now.
2128     Reader.getContext().getInjectedClassNameType(
2129         D->getTemplatedDecl(), D->getInjectedClassNameSpecialization());
2130   }
2131 }
2132 
2133 void ASTDeclReader::VisitBuiltinTemplateDecl(BuiltinTemplateDecl *D) {
2134   llvm_unreachable("BuiltinTemplates are not serialized");
2135 }
2136 
2137 /// TODO: Unify with ClassTemplateDecl version?
2138 ///       May require unifying ClassTemplateDecl and
2139 ///        VarTemplateDecl beyond TemplateDecl...
2140 void ASTDeclReader::VisitVarTemplateDecl(VarTemplateDecl *D) {
2141   RedeclarableResult Redecl = VisitRedeclarableTemplateDecl(D);
2142 
2143   if (ThisDeclID == Redecl.getFirstID()) {
2144     // This VarTemplateDecl owns a CommonPtr; read it to keep track of all of
2145     // the specializations.
2146     SmallVector<serialization::DeclID, 32> SpecIDs;
2147     readDeclIDList(SpecIDs);
2148     ASTDeclReader::AddLazySpecializations(D, SpecIDs);
2149   }
2150 }
2151 
2152 ASTDeclReader::RedeclarableResult
2153 ASTDeclReader::VisitClassTemplateSpecializationDeclImpl(
2154     ClassTemplateSpecializationDecl *D) {
2155   RedeclarableResult Redecl = VisitCXXRecordDeclImpl(D);
2156 
2157   ASTContext &C = Reader.getContext();
2158   if (Decl *InstD = readDecl()) {
2159     if (auto *CTD = dyn_cast<ClassTemplateDecl>(InstD)) {
2160       D->SpecializedTemplate = CTD;
2161     } else {
2162       SmallVector<TemplateArgument, 8> TemplArgs;
2163       Record.readTemplateArgumentList(TemplArgs);
2164       TemplateArgumentList *ArgList
2165         = TemplateArgumentList::CreateCopy(C, TemplArgs);
2166       auto *PS =
2167           new (C) ClassTemplateSpecializationDecl::
2168                                              SpecializedPartialSpecialization();
2169       PS->PartialSpecialization
2170           = cast<ClassTemplatePartialSpecializationDecl>(InstD);
2171       PS->TemplateArgs = ArgList;
2172       D->SpecializedTemplate = PS;
2173     }
2174   }
2175 
2176   SmallVector<TemplateArgument, 8> TemplArgs;
2177   Record.readTemplateArgumentList(TemplArgs, /*Canonicalize*/ true);
2178   D->TemplateArgs = TemplateArgumentList::CreateCopy(C, TemplArgs);
2179   D->PointOfInstantiation = readSourceLocation();
2180   D->SpecializationKind = (TemplateSpecializationKind)Record.readInt();
2181 
2182   bool writtenAsCanonicalDecl = Record.readInt();
2183   if (writtenAsCanonicalDecl) {
2184     auto *CanonPattern = readDeclAs<ClassTemplateDecl>();
2185     if (D->isCanonicalDecl()) { // It's kept in the folding set.
2186       // Set this as, or find, the canonical declaration for this specialization
2187       ClassTemplateSpecializationDecl *CanonSpec;
2188       if (auto *Partial = dyn_cast<ClassTemplatePartialSpecializationDecl>(D)) {
2189         CanonSpec = CanonPattern->getCommonPtr()->PartialSpecializations
2190             .GetOrInsertNode(Partial);
2191       } else {
2192         CanonSpec =
2193             CanonPattern->getCommonPtr()->Specializations.GetOrInsertNode(D);
2194       }
2195       // If there was already a canonical specialization, merge into it.
2196       if (CanonSpec != D) {
2197         mergeRedeclarable<TagDecl>(D, CanonSpec, Redecl);
2198 
2199         // This declaration might be a definition. Merge with any existing
2200         // definition.
2201         if (auto *DDD = D->DefinitionData) {
2202           if (CanonSpec->DefinitionData)
2203             MergeDefinitionData(CanonSpec, std::move(*DDD));
2204           else
2205             CanonSpec->DefinitionData = D->DefinitionData;
2206         }
2207         D->DefinitionData = CanonSpec->DefinitionData;
2208       }
2209     }
2210   }
2211 
2212   // Explicit info.
2213   if (TypeSourceInfo *TyInfo = readTypeSourceInfo()) {
2214     auto *ExplicitInfo =
2215         new (C) ClassTemplateSpecializationDecl::ExplicitSpecializationInfo;
2216     ExplicitInfo->TypeAsWritten = TyInfo;
2217     ExplicitInfo->ExternLoc = readSourceLocation();
2218     ExplicitInfo->TemplateKeywordLoc = readSourceLocation();
2219     D->ExplicitInfo = ExplicitInfo;
2220   }
2221 
2222   return Redecl;
2223 }
2224 
2225 void ASTDeclReader::VisitClassTemplatePartialSpecializationDecl(
2226                                     ClassTemplatePartialSpecializationDecl *D) {
2227   // We need to read the template params first because redeclarable is going to
2228   // need them for profiling
2229   TemplateParameterList *Params = Record.readTemplateParameterList();
2230   D->TemplateParams = Params;
2231   D->ArgsAsWritten = Record.readASTTemplateArgumentListInfo();
2232 
2233   RedeclarableResult Redecl = VisitClassTemplateSpecializationDeclImpl(D);
2234 
2235   // These are read/set from/to the first declaration.
2236   if (ThisDeclID == Redecl.getFirstID()) {
2237     D->InstantiatedFromMember.setPointer(
2238       readDeclAs<ClassTemplatePartialSpecializationDecl>());
2239     D->InstantiatedFromMember.setInt(Record.readInt());
2240   }
2241 }
2242 
2243 void ASTDeclReader::VisitClassScopeFunctionSpecializationDecl(
2244                                     ClassScopeFunctionSpecializationDecl *D) {
2245   VisitDecl(D);
2246   D->Specialization = readDeclAs<CXXMethodDecl>();
2247   if (Record.readInt())
2248     D->TemplateArgs = Record.readASTTemplateArgumentListInfo();
2249 }
2250 
2251 void ASTDeclReader::VisitFunctionTemplateDecl(FunctionTemplateDecl *D) {
2252   RedeclarableResult Redecl = VisitRedeclarableTemplateDecl(D);
2253 
2254   if (ThisDeclID == Redecl.getFirstID()) {
2255     // This FunctionTemplateDecl owns a CommonPtr; read it.
2256     SmallVector<serialization::DeclID, 32> SpecIDs;
2257     readDeclIDList(SpecIDs);
2258     ASTDeclReader::AddLazySpecializations(D, SpecIDs);
2259   }
2260 }
2261 
2262 /// TODO: Unify with ClassTemplateSpecializationDecl version?
2263 ///       May require unifying ClassTemplate(Partial)SpecializationDecl and
2264 ///        VarTemplate(Partial)SpecializationDecl with a new data
2265 ///        structure Template(Partial)SpecializationDecl, and
2266 ///        using Template(Partial)SpecializationDecl as input type.
2267 ASTDeclReader::RedeclarableResult
2268 ASTDeclReader::VisitVarTemplateSpecializationDeclImpl(
2269     VarTemplateSpecializationDecl *D) {
2270   RedeclarableResult Redecl = VisitVarDeclImpl(D);
2271 
2272   ASTContext &C = Reader.getContext();
2273   if (Decl *InstD = readDecl()) {
2274     if (auto *VTD = dyn_cast<VarTemplateDecl>(InstD)) {
2275       D->SpecializedTemplate = VTD;
2276     } else {
2277       SmallVector<TemplateArgument, 8> TemplArgs;
2278       Record.readTemplateArgumentList(TemplArgs);
2279       TemplateArgumentList *ArgList = TemplateArgumentList::CreateCopy(
2280           C, TemplArgs);
2281       auto *PS =
2282           new (C)
2283           VarTemplateSpecializationDecl::SpecializedPartialSpecialization();
2284       PS->PartialSpecialization =
2285           cast<VarTemplatePartialSpecializationDecl>(InstD);
2286       PS->TemplateArgs = ArgList;
2287       D->SpecializedTemplate = PS;
2288     }
2289   }
2290 
2291   // Explicit info.
2292   if (TypeSourceInfo *TyInfo = readTypeSourceInfo()) {
2293     auto *ExplicitInfo =
2294         new (C) VarTemplateSpecializationDecl::ExplicitSpecializationInfo;
2295     ExplicitInfo->TypeAsWritten = TyInfo;
2296     ExplicitInfo->ExternLoc = readSourceLocation();
2297     ExplicitInfo->TemplateKeywordLoc = readSourceLocation();
2298     D->ExplicitInfo = ExplicitInfo;
2299   }
2300 
2301   SmallVector<TemplateArgument, 8> TemplArgs;
2302   Record.readTemplateArgumentList(TemplArgs, /*Canonicalize*/ true);
2303   D->TemplateArgs = TemplateArgumentList::CreateCopy(C, TemplArgs);
2304   D->PointOfInstantiation = readSourceLocation();
2305   D->SpecializationKind = (TemplateSpecializationKind)Record.readInt();
2306   D->IsCompleteDefinition = Record.readInt();
2307 
2308   bool writtenAsCanonicalDecl = Record.readInt();
2309   if (writtenAsCanonicalDecl) {
2310     auto *CanonPattern = readDeclAs<VarTemplateDecl>();
2311     if (D->isCanonicalDecl()) { // It's kept in the folding set.
2312       // FIXME: If it's already present, merge it.
2313       if (auto *Partial = dyn_cast<VarTemplatePartialSpecializationDecl>(D)) {
2314         CanonPattern->getCommonPtr()->PartialSpecializations
2315             .GetOrInsertNode(Partial);
2316       } else {
2317         CanonPattern->getCommonPtr()->Specializations.GetOrInsertNode(D);
2318       }
2319     }
2320   }
2321 
2322   return Redecl;
2323 }
2324 
2325 /// TODO: Unify with ClassTemplatePartialSpecializationDecl version?
2326 ///       May require unifying ClassTemplate(Partial)SpecializationDecl and
2327 ///        VarTemplate(Partial)SpecializationDecl with a new data
2328 ///        structure Template(Partial)SpecializationDecl, and
2329 ///        using Template(Partial)SpecializationDecl as input type.
2330 void ASTDeclReader::VisitVarTemplatePartialSpecializationDecl(
2331     VarTemplatePartialSpecializationDecl *D) {
2332   TemplateParameterList *Params = Record.readTemplateParameterList();
2333   D->TemplateParams = Params;
2334   D->ArgsAsWritten = Record.readASTTemplateArgumentListInfo();
2335 
2336   RedeclarableResult Redecl = VisitVarTemplateSpecializationDeclImpl(D);
2337 
2338   // These are read/set from/to the first declaration.
2339   if (ThisDeclID == Redecl.getFirstID()) {
2340     D->InstantiatedFromMember.setPointer(
2341         readDeclAs<VarTemplatePartialSpecializationDecl>());
2342     D->InstantiatedFromMember.setInt(Record.readInt());
2343   }
2344 }
2345 
2346 void ASTDeclReader::VisitTemplateTypeParmDecl(TemplateTypeParmDecl *D) {
2347   VisitTypeDecl(D);
2348 
2349   D->setDeclaredWithTypename(Record.readInt());
2350 
2351   if (Record.readBool()) {
2352     NestedNameSpecifierLoc NNS = Record.readNestedNameSpecifierLoc();
2353     DeclarationNameInfo DN = Record.readDeclarationNameInfo();
2354     ConceptDecl *NamedConcept = Record.readDeclAs<ConceptDecl>();
2355     const ASTTemplateArgumentListInfo *ArgsAsWritten = nullptr;
2356     if (Record.readBool())
2357         ArgsAsWritten = Record.readASTTemplateArgumentListInfo();
2358     Expr *ImmediatelyDeclaredConstraint = Record.readExpr();
2359     D->setTypeConstraint(NNS, DN, /*FoundDecl=*/nullptr, NamedConcept,
2360                          ArgsAsWritten, ImmediatelyDeclaredConstraint);
2361     if ((D->ExpandedParameterPack = Record.readInt()))
2362       D->NumExpanded = Record.readInt();
2363   }
2364 
2365   if (Record.readInt())
2366     D->setDefaultArgument(readTypeSourceInfo());
2367 }
2368 
2369 void ASTDeclReader::VisitNonTypeTemplateParmDecl(NonTypeTemplateParmDecl *D) {
2370   VisitDeclaratorDecl(D);
2371   // TemplateParmPosition.
2372   D->setDepth(Record.readInt());
2373   D->setPosition(Record.readInt());
2374   if (D->hasPlaceholderTypeConstraint())
2375     D->setPlaceholderTypeConstraint(Record.readExpr());
2376   if (D->isExpandedParameterPack()) {
2377     auto TypesAndInfos =
2378         D->getTrailingObjects<std::pair<QualType, TypeSourceInfo *>>();
2379     for (unsigned I = 0, N = D->getNumExpansionTypes(); I != N; ++I) {
2380       new (&TypesAndInfos[I].first) QualType(Record.readType());
2381       TypesAndInfos[I].second = readTypeSourceInfo();
2382     }
2383   } else {
2384     // Rest of NonTypeTemplateParmDecl.
2385     D->ParameterPack = Record.readInt();
2386     if (Record.readInt())
2387       D->setDefaultArgument(Record.readExpr());
2388   }
2389 }
2390 
2391 void ASTDeclReader::VisitTemplateTemplateParmDecl(TemplateTemplateParmDecl *D) {
2392   VisitTemplateDecl(D);
2393   // TemplateParmPosition.
2394   D->setDepth(Record.readInt());
2395   D->setPosition(Record.readInt());
2396   if (D->isExpandedParameterPack()) {
2397     auto **Data = D->getTrailingObjects<TemplateParameterList *>();
2398     for (unsigned I = 0, N = D->getNumExpansionTemplateParameters();
2399          I != N; ++I)
2400       Data[I] = Record.readTemplateParameterList();
2401   } else {
2402     // Rest of TemplateTemplateParmDecl.
2403     D->ParameterPack = Record.readInt();
2404     if (Record.readInt())
2405       D->setDefaultArgument(Reader.getContext(),
2406                             Record.readTemplateArgumentLoc());
2407   }
2408 }
2409 
2410 void ASTDeclReader::VisitTypeAliasTemplateDecl(TypeAliasTemplateDecl *D) {
2411   VisitRedeclarableTemplateDecl(D);
2412 }
2413 
2414 void ASTDeclReader::VisitStaticAssertDecl(StaticAssertDecl *D) {
2415   VisitDecl(D);
2416   D->AssertExprAndFailed.setPointer(Record.readExpr());
2417   D->AssertExprAndFailed.setInt(Record.readInt());
2418   D->Message = cast_or_null<StringLiteral>(Record.readExpr());
2419   D->RParenLoc = readSourceLocation();
2420 }
2421 
2422 void ASTDeclReader::VisitEmptyDecl(EmptyDecl *D) {
2423   VisitDecl(D);
2424 }
2425 
2426 void ASTDeclReader::VisitLifetimeExtendedTemporaryDecl(
2427     LifetimeExtendedTemporaryDecl *D) {
2428   VisitDecl(D);
2429   D->ExtendingDecl = readDeclAs<ValueDecl>();
2430   D->ExprWithTemporary = Record.readStmt();
2431   if (Record.readInt()) {
2432     D->Value = new (D->getASTContext()) APValue(Record.readAPValue());
2433     D->getASTContext().addDestruction(D->Value);
2434   }
2435   D->ManglingNumber = Record.readInt();
2436   mergeMergeable(D);
2437 }
2438 
2439 std::pair<uint64_t, uint64_t>
2440 ASTDeclReader::VisitDeclContext(DeclContext *DC) {
2441   uint64_t LexicalOffset = ReadLocalOffset();
2442   uint64_t VisibleOffset = ReadLocalOffset();
2443   return std::make_pair(LexicalOffset, VisibleOffset);
2444 }
2445 
2446 template <typename T>
2447 ASTDeclReader::RedeclarableResult
2448 ASTDeclReader::VisitRedeclarable(Redeclarable<T> *D) {
2449   DeclID FirstDeclID = readDeclID();
2450   Decl *MergeWith = nullptr;
2451 
2452   bool IsKeyDecl = ThisDeclID == FirstDeclID;
2453   bool IsFirstLocalDecl = false;
2454 
2455   uint64_t RedeclOffset = 0;
2456 
2457   // 0 indicates that this declaration was the only declaration of its entity,
2458   // and is used for space optimization.
2459   if (FirstDeclID == 0) {
2460     FirstDeclID = ThisDeclID;
2461     IsKeyDecl = true;
2462     IsFirstLocalDecl = true;
2463   } else if (unsigned N = Record.readInt()) {
2464     // This declaration was the first local declaration, but may have imported
2465     // other declarations.
2466     IsKeyDecl = N == 1;
2467     IsFirstLocalDecl = true;
2468 
2469     // We have some declarations that must be before us in our redeclaration
2470     // chain. Read them now, and remember that we ought to merge with one of
2471     // them.
2472     // FIXME: Provide a known merge target to the second and subsequent such
2473     // declaration.
2474     for (unsigned I = 0; I != N - 1; ++I)
2475       MergeWith = readDecl();
2476 
2477     RedeclOffset = ReadLocalOffset();
2478   } else {
2479     // This declaration was not the first local declaration. Read the first
2480     // local declaration now, to trigger the import of other redeclarations.
2481     (void)readDecl();
2482   }
2483 
2484   auto *FirstDecl = cast_or_null<T>(Reader.GetDecl(FirstDeclID));
2485   if (FirstDecl != D) {
2486     // We delay loading of the redeclaration chain to avoid deeply nested calls.
2487     // We temporarily set the first (canonical) declaration as the previous one
2488     // which is the one that matters and mark the real previous DeclID to be
2489     // loaded & attached later on.
2490     D->RedeclLink = Redeclarable<T>::PreviousDeclLink(FirstDecl);
2491     D->First = FirstDecl->getCanonicalDecl();
2492   }
2493 
2494   auto *DAsT = static_cast<T *>(D);
2495 
2496   // Note that we need to load local redeclarations of this decl and build a
2497   // decl chain for them. This must happen *after* we perform the preloading
2498   // above; this ensures that the redeclaration chain is built in the correct
2499   // order.
2500   if (IsFirstLocalDecl)
2501     Reader.PendingDeclChains.push_back(std::make_pair(DAsT, RedeclOffset));
2502 
2503   return RedeclarableResult(MergeWith, FirstDeclID, IsKeyDecl);
2504 }
2505 
2506 /// Attempts to merge the given declaration (D) with another declaration
2507 /// of the same entity.
2508 template<typename T>
2509 void ASTDeclReader::mergeRedeclarable(Redeclarable<T> *DBase,
2510                                       RedeclarableResult &Redecl,
2511                                       DeclID TemplatePatternID) {
2512   // If modules are not available, there is no reason to perform this merge.
2513   if (!Reader.getContext().getLangOpts().Modules)
2514     return;
2515 
2516   // If we're not the canonical declaration, we don't need to merge.
2517   if (!DBase->isFirstDecl())
2518     return;
2519 
2520   auto *D = static_cast<T *>(DBase);
2521 
2522   if (auto *Existing = Redecl.getKnownMergeTarget())
2523     // We already know of an existing declaration we should merge with.
2524     mergeRedeclarable(D, cast<T>(Existing), Redecl, TemplatePatternID);
2525   else if (FindExistingResult ExistingRes = findExisting(D))
2526     if (T *Existing = ExistingRes)
2527       mergeRedeclarable(D, Existing, Redecl, TemplatePatternID);
2528 }
2529 
2530 /// "Cast" to type T, asserting if we don't have an implicit conversion.
2531 /// We use this to put code in a template that will only be valid for certain
2532 /// instantiations.
2533 template<typename T> static T assert_cast(T t) { return t; }
2534 template<typename T> static T assert_cast(...) {
2535   llvm_unreachable("bad assert_cast");
2536 }
2537 
2538 /// Merge together the pattern declarations from two template
2539 /// declarations.
2540 void ASTDeclReader::mergeTemplatePattern(RedeclarableTemplateDecl *D,
2541                                          RedeclarableTemplateDecl *Existing,
2542                                          DeclID DsID, bool IsKeyDecl) {
2543   auto *DPattern = D->getTemplatedDecl();
2544   auto *ExistingPattern = Existing->getTemplatedDecl();
2545   RedeclarableResult Result(/*MergeWith*/ ExistingPattern,
2546                             DPattern->getCanonicalDecl()->getGlobalID(),
2547                             IsKeyDecl);
2548 
2549   if (auto *DClass = dyn_cast<CXXRecordDecl>(DPattern)) {
2550     // Merge with any existing definition.
2551     // FIXME: This is duplicated in several places. Refactor.
2552     auto *ExistingClass =
2553         cast<CXXRecordDecl>(ExistingPattern)->getCanonicalDecl();
2554     if (auto *DDD = DClass->DefinitionData) {
2555       if (ExistingClass->DefinitionData) {
2556         MergeDefinitionData(ExistingClass, std::move(*DDD));
2557       } else {
2558         ExistingClass->DefinitionData = DClass->DefinitionData;
2559         // We may have skipped this before because we thought that DClass
2560         // was the canonical declaration.
2561         Reader.PendingDefinitions.insert(DClass);
2562       }
2563     }
2564     DClass->DefinitionData = ExistingClass->DefinitionData;
2565 
2566     return mergeRedeclarable(DClass, cast<TagDecl>(ExistingPattern),
2567                              Result);
2568   }
2569   if (auto *DFunction = dyn_cast<FunctionDecl>(DPattern))
2570     return mergeRedeclarable(DFunction, cast<FunctionDecl>(ExistingPattern),
2571                              Result);
2572   if (auto *DVar = dyn_cast<VarDecl>(DPattern))
2573     return mergeRedeclarable(DVar, cast<VarDecl>(ExistingPattern), Result);
2574   if (auto *DAlias = dyn_cast<TypeAliasDecl>(DPattern))
2575     return mergeRedeclarable(DAlias, cast<TypedefNameDecl>(ExistingPattern),
2576                              Result);
2577   llvm_unreachable("merged an unknown kind of redeclarable template");
2578 }
2579 
2580 /// Attempts to merge the given declaration (D) with another declaration
2581 /// of the same entity.
2582 template<typename T>
2583 void ASTDeclReader::mergeRedeclarable(Redeclarable<T> *DBase, T *Existing,
2584                                       RedeclarableResult &Redecl,
2585                                       DeclID TemplatePatternID) {
2586   auto *D = static_cast<T *>(DBase);
2587   T *ExistingCanon = Existing->getCanonicalDecl();
2588   T *DCanon = D->getCanonicalDecl();
2589   if (ExistingCanon != DCanon) {
2590     assert(DCanon->getGlobalID() == Redecl.getFirstID() &&
2591            "already merged this declaration");
2592 
2593     // Have our redeclaration link point back at the canonical declaration
2594     // of the existing declaration, so that this declaration has the
2595     // appropriate canonical declaration.
2596     D->RedeclLink = Redeclarable<T>::PreviousDeclLink(ExistingCanon);
2597     D->First = ExistingCanon;
2598     ExistingCanon->Used |= D->Used;
2599     D->Used = false;
2600 
2601     // When we merge a namespace, update its pointer to the first namespace.
2602     // We cannot have loaded any redeclarations of this declaration yet, so
2603     // there's nothing else that needs to be updated.
2604     if (auto *Namespace = dyn_cast<NamespaceDecl>(D))
2605       Namespace->AnonOrFirstNamespaceAndInline.setPointer(
2606           assert_cast<NamespaceDecl*>(ExistingCanon));
2607 
2608     // When we merge a template, merge its pattern.
2609     if (auto *DTemplate = dyn_cast<RedeclarableTemplateDecl>(D))
2610       mergeTemplatePattern(
2611           DTemplate, assert_cast<RedeclarableTemplateDecl*>(ExistingCanon),
2612           TemplatePatternID, Redecl.isKeyDecl());
2613 
2614     // If this declaration is a key declaration, make a note of that.
2615     if (Redecl.isKeyDecl())
2616       Reader.KeyDecls[ExistingCanon].push_back(Redecl.getFirstID());
2617   }
2618 }
2619 
2620 /// ODR-like semantics for C/ObjC allow us to merge tag types and a structural
2621 /// check in Sema guarantees the types can be merged (see C11 6.2.7/1 or C89
2622 /// 6.1.2.6/1). Although most merging is done in Sema, we need to guarantee
2623 /// that some types are mergeable during deserialization, otherwise name
2624 /// lookup fails. This is the case for EnumConstantDecl.
2625 static bool allowODRLikeMergeInC(NamedDecl *ND) {
2626   if (!ND)
2627     return false;
2628   // TODO: implement merge for other necessary decls.
2629   if (isa<EnumConstantDecl>(ND))
2630     return true;
2631   return false;
2632 }
2633 
2634 /// Attempts to merge LifetimeExtendedTemporaryDecl with
2635 /// identical class definitions from two different modules.
2636 void ASTDeclReader::mergeMergeable(LifetimeExtendedTemporaryDecl *D) {
2637   // If modules are not available, there is no reason to perform this merge.
2638   if (!Reader.getContext().getLangOpts().Modules)
2639     return;
2640 
2641   LifetimeExtendedTemporaryDecl *LETDecl = D;
2642 
2643   LifetimeExtendedTemporaryDecl *&LookupResult =
2644       Reader.LETemporaryForMerging[std::make_pair(
2645           LETDecl->getExtendingDecl(), LETDecl->getManglingNumber())];
2646   if (LookupResult)
2647     Reader.getContext().setPrimaryMergedDecl(LETDecl,
2648                                              LookupResult->getCanonicalDecl());
2649   else
2650     LookupResult = LETDecl;
2651 }
2652 
2653 /// Attempts to merge the given declaration (D) with another declaration
2654 /// of the same entity, for the case where the entity is not actually
2655 /// redeclarable. This happens, for instance, when merging the fields of
2656 /// identical class definitions from two different modules.
2657 template<typename T>
2658 void ASTDeclReader::mergeMergeable(Mergeable<T> *D) {
2659   // If modules are not available, there is no reason to perform this merge.
2660   if (!Reader.getContext().getLangOpts().Modules)
2661     return;
2662 
2663   // ODR-based merging is performed in C++ and in some cases (tag types) in C.
2664   // Note that C identically-named things in different translation units are
2665   // not redeclarations, but may still have compatible types, where ODR-like
2666   // semantics may apply.
2667   if (!Reader.getContext().getLangOpts().CPlusPlus &&
2668       !allowODRLikeMergeInC(dyn_cast<NamedDecl>(static_cast<T*>(D))))
2669     return;
2670 
2671   if (FindExistingResult ExistingRes = findExisting(static_cast<T*>(D)))
2672     if (T *Existing = ExistingRes)
2673       Reader.getContext().setPrimaryMergedDecl(static_cast<T *>(D),
2674                                                Existing->getCanonicalDecl());
2675 }
2676 
2677 void ASTDeclReader::VisitOMPThreadPrivateDecl(OMPThreadPrivateDecl *D) {
2678   Record.readOMPChildren(D->Data);
2679   VisitDecl(D);
2680 }
2681 
2682 void ASTDeclReader::VisitOMPAllocateDecl(OMPAllocateDecl *D) {
2683   Record.readOMPChildren(D->Data);
2684   VisitDecl(D);
2685 }
2686 
2687 void ASTDeclReader::VisitOMPRequiresDecl(OMPRequiresDecl * D) {
2688   Record.readOMPChildren(D->Data);
2689   VisitDecl(D);
2690 }
2691 
2692 void ASTDeclReader::VisitOMPDeclareReductionDecl(OMPDeclareReductionDecl *D) {
2693   VisitValueDecl(D);
2694   D->setLocation(readSourceLocation());
2695   Expr *In = Record.readExpr();
2696   Expr *Out = Record.readExpr();
2697   D->setCombinerData(In, Out);
2698   Expr *Combiner = Record.readExpr();
2699   D->setCombiner(Combiner);
2700   Expr *Orig = Record.readExpr();
2701   Expr *Priv = Record.readExpr();
2702   D->setInitializerData(Orig, Priv);
2703   Expr *Init = Record.readExpr();
2704   auto IK = static_cast<OMPDeclareReductionDecl::InitKind>(Record.readInt());
2705   D->setInitializer(Init, IK);
2706   D->PrevDeclInScope = readDeclID();
2707 }
2708 
2709 void ASTDeclReader::VisitOMPDeclareMapperDecl(OMPDeclareMapperDecl *D) {
2710   Record.readOMPChildren(D->Data);
2711   VisitValueDecl(D);
2712   D->VarName = Record.readDeclarationName();
2713   D->PrevDeclInScope = readDeclID();
2714 }
2715 
2716 void ASTDeclReader::VisitOMPCapturedExprDecl(OMPCapturedExprDecl *D) {
2717   VisitVarDecl(D);
2718 }
2719 
2720 //===----------------------------------------------------------------------===//
2721 // Attribute Reading
2722 //===----------------------------------------------------------------------===//
2723 
2724 namespace {
2725 class AttrReader {
2726   ASTRecordReader &Reader;
2727 
2728 public:
2729   AttrReader(ASTRecordReader &Reader) : Reader(Reader) {}
2730 
2731   uint64_t readInt() {
2732     return Reader.readInt();
2733   }
2734 
2735   SourceRange readSourceRange() {
2736     return Reader.readSourceRange();
2737   }
2738 
2739   SourceLocation readSourceLocation() {
2740     return Reader.readSourceLocation();
2741   }
2742 
2743   Expr *readExpr() { return Reader.readExpr(); }
2744 
2745   std::string readString() {
2746     return Reader.readString();
2747   }
2748 
2749   TypeSourceInfo *readTypeSourceInfo() {
2750     return Reader.readTypeSourceInfo();
2751   }
2752 
2753   IdentifierInfo *readIdentifier() {
2754     return Reader.readIdentifier();
2755   }
2756 
2757   VersionTuple readVersionTuple() {
2758     return Reader.readVersionTuple();
2759   }
2760 
2761   OMPTraitInfo *readOMPTraitInfo() { return Reader.readOMPTraitInfo(); }
2762 
2763   template <typename T> T *GetLocalDeclAs(uint32_t LocalID) {
2764     return Reader.GetLocalDeclAs<T>(LocalID);
2765   }
2766 };
2767 }
2768 
2769 Attr *ASTRecordReader::readAttr() {
2770   AttrReader Record(*this);
2771   auto V = Record.readInt();
2772   if (!V)
2773     return nullptr;
2774 
2775   Attr *New = nullptr;
2776   // Kind is stored as a 1-based integer because 0 is used to indicate a null
2777   // Attr pointer.
2778   auto Kind = static_cast<attr::Kind>(V - 1);
2779   ASTContext &Context = getContext();
2780 
2781   IdentifierInfo *AttrName = Record.readIdentifier();
2782   IdentifierInfo *ScopeName = Record.readIdentifier();
2783   SourceRange AttrRange = Record.readSourceRange();
2784   SourceLocation ScopeLoc = Record.readSourceLocation();
2785   unsigned ParsedKind = Record.readInt();
2786   unsigned Syntax = Record.readInt();
2787   unsigned SpellingIndex = Record.readInt();
2788 
2789   AttributeCommonInfo Info(AttrName, ScopeName, AttrRange, ScopeLoc,
2790                            AttributeCommonInfo::Kind(ParsedKind),
2791                            AttributeCommonInfo::Syntax(Syntax), SpellingIndex);
2792 
2793 #include "clang/Serialization/AttrPCHRead.inc"
2794 
2795   assert(New && "Unable to decode attribute?");
2796   return New;
2797 }
2798 
2799 /// Reads attributes from the current stream position.
2800 void ASTRecordReader::readAttributes(AttrVec &Attrs) {
2801   for (unsigned I = 0, E = readInt(); I != E; ++I)
2802     Attrs.push_back(readAttr());
2803 }
2804 
2805 //===----------------------------------------------------------------------===//
2806 // ASTReader Implementation
2807 //===----------------------------------------------------------------------===//
2808 
2809 /// Note that we have loaded the declaration with the given
2810 /// Index.
2811 ///
2812 /// This routine notes that this declaration has already been loaded,
2813 /// so that future GetDecl calls will return this declaration rather
2814 /// than trying to load a new declaration.
2815 inline void ASTReader::LoadedDecl(unsigned Index, Decl *D) {
2816   assert(!DeclsLoaded[Index] && "Decl loaded twice?");
2817   DeclsLoaded[Index] = D;
2818 }
2819 
2820 /// Determine whether the consumer will be interested in seeing
2821 /// this declaration (via HandleTopLevelDecl).
2822 ///
2823 /// This routine should return true for anything that might affect
2824 /// code generation, e.g., inline function definitions, Objective-C
2825 /// declarations with metadata, etc.
2826 static bool isConsumerInterestedIn(ASTContext &Ctx, Decl *D, bool HasBody) {
2827   // An ObjCMethodDecl is never considered as "interesting" because its
2828   // implementation container always is.
2829 
2830   // An ImportDecl or VarDecl imported from a module map module will get
2831   // emitted when we import the relevant module.
2832   if (isPartOfPerModuleInitializer(D)) {
2833     auto *M = D->getImportedOwningModule();
2834     if (M && M->Kind == Module::ModuleMapModule &&
2835         Ctx.DeclMustBeEmitted(D))
2836       return false;
2837   }
2838 
2839   if (isa<FileScopeAsmDecl>(D) ||
2840       isa<ObjCProtocolDecl>(D) ||
2841       isa<ObjCImplDecl>(D) ||
2842       isa<ImportDecl>(D) ||
2843       isa<PragmaCommentDecl>(D) ||
2844       isa<PragmaDetectMismatchDecl>(D))
2845     return true;
2846   if (isa<OMPThreadPrivateDecl>(D) || isa<OMPDeclareReductionDecl>(D) ||
2847       isa<OMPDeclareMapperDecl>(D) || isa<OMPAllocateDecl>(D) ||
2848       isa<OMPRequiresDecl>(D))
2849     return !D->getDeclContext()->isFunctionOrMethod();
2850   if (const auto *Var = dyn_cast<VarDecl>(D))
2851     return Var->isFileVarDecl() &&
2852            (Var->isThisDeclarationADefinition() == VarDecl::Definition ||
2853             OMPDeclareTargetDeclAttr::isDeclareTargetDeclaration(Var));
2854   if (const auto *Func = dyn_cast<FunctionDecl>(D))
2855     return Func->doesThisDeclarationHaveABody() || HasBody;
2856 
2857   if (auto *ES = D->getASTContext().getExternalSource())
2858     if (ES->hasExternalDefinitions(D) == ExternalASTSource::EK_Never)
2859       return true;
2860 
2861   return false;
2862 }
2863 
2864 /// Get the correct cursor and offset for loading a declaration.
2865 ASTReader::RecordLocation
2866 ASTReader::DeclCursorForID(DeclID ID, SourceLocation &Loc) {
2867   GlobalDeclMapType::iterator I = GlobalDeclMap.find(ID);
2868   assert(I != GlobalDeclMap.end() && "Corrupted global declaration map");
2869   ModuleFile *M = I->second;
2870   const DeclOffset &DOffs =
2871       M->DeclOffsets[ID - M->BaseDeclID - NUM_PREDEF_DECL_IDS];
2872   Loc = TranslateSourceLocation(*M, DOffs.getLocation());
2873   return RecordLocation(M, DOffs.getBitOffset(M->DeclsBlockStartOffset));
2874 }
2875 
2876 ASTReader::RecordLocation ASTReader::getLocalBitOffset(uint64_t GlobalOffset) {
2877   auto I = GlobalBitOffsetsMap.find(GlobalOffset);
2878 
2879   assert(I != GlobalBitOffsetsMap.end() && "Corrupted global bit offsets map");
2880   return RecordLocation(I->second, GlobalOffset - I->second->GlobalBitOffset);
2881 }
2882 
2883 uint64_t ASTReader::getGlobalBitOffset(ModuleFile &M, uint64_t LocalOffset) {
2884   return LocalOffset + M.GlobalBitOffset;
2885 }
2886 
2887 static bool isSameTemplateParameterList(const ASTContext &C,
2888                                         const TemplateParameterList *X,
2889                                         const TemplateParameterList *Y);
2890 
2891 /// Determine whether two template parameters are similar enough
2892 /// that they may be used in declarations of the same template.
2893 static bool isSameTemplateParameter(const NamedDecl *X,
2894                                     const NamedDecl *Y) {
2895   if (X->getKind() != Y->getKind())
2896     return false;
2897 
2898   if (const auto *TX = dyn_cast<TemplateTypeParmDecl>(X)) {
2899     const auto *TY = cast<TemplateTypeParmDecl>(Y);
2900     if (TX->isParameterPack() != TY->isParameterPack())
2901       return false;
2902     if (TX->hasTypeConstraint() != TY->hasTypeConstraint())
2903       return false;
2904     const TypeConstraint *TXTC = TX->getTypeConstraint();
2905     const TypeConstraint *TYTC = TY->getTypeConstraint();
2906     if (!TXTC != !TYTC)
2907       return false;
2908     if (TXTC && TYTC) {
2909       if (TXTC->getNamedConcept() != TYTC->getNamedConcept())
2910         return false;
2911       if (TXTC->hasExplicitTemplateArgs() != TYTC->hasExplicitTemplateArgs())
2912         return false;
2913       if (TXTC->hasExplicitTemplateArgs()) {
2914         const auto *TXTCArgs = TXTC->getTemplateArgsAsWritten();
2915         const auto *TYTCArgs = TYTC->getTemplateArgsAsWritten();
2916         if (TXTCArgs->NumTemplateArgs != TYTCArgs->NumTemplateArgs)
2917           return false;
2918         llvm::FoldingSetNodeID XID, YID;
2919         for (const auto &ArgLoc : TXTCArgs->arguments())
2920           ArgLoc.getArgument().Profile(XID, X->getASTContext());
2921         for (const auto &ArgLoc : TYTCArgs->arguments())
2922           ArgLoc.getArgument().Profile(YID, Y->getASTContext());
2923         if (XID != YID)
2924           return false;
2925       }
2926     }
2927     return true;
2928   }
2929 
2930   if (const auto *TX = dyn_cast<NonTypeTemplateParmDecl>(X)) {
2931     const auto *TY = cast<NonTypeTemplateParmDecl>(Y);
2932     return TX->isParameterPack() == TY->isParameterPack() &&
2933            TX->getASTContext().hasSameType(TX->getType(), TY->getType());
2934   }
2935 
2936   const auto *TX = cast<TemplateTemplateParmDecl>(X);
2937   const auto *TY = cast<TemplateTemplateParmDecl>(Y);
2938   return TX->isParameterPack() == TY->isParameterPack() &&
2939          isSameTemplateParameterList(TX->getASTContext(),
2940                                      TX->getTemplateParameters(),
2941                                      TY->getTemplateParameters());
2942 }
2943 
2944 static NamespaceDecl *getNamespace(const NestedNameSpecifier *X) {
2945   if (auto *NS = X->getAsNamespace())
2946     return NS;
2947   if (auto *NAS = X->getAsNamespaceAlias())
2948     return NAS->getNamespace();
2949   return nullptr;
2950 }
2951 
2952 static bool isSameQualifier(const NestedNameSpecifier *X,
2953                             const NestedNameSpecifier *Y) {
2954   if (auto *NSX = getNamespace(X)) {
2955     auto *NSY = getNamespace(Y);
2956     if (!NSY || NSX->getCanonicalDecl() != NSY->getCanonicalDecl())
2957       return false;
2958   } else if (X->getKind() != Y->getKind())
2959     return false;
2960 
2961   // FIXME: For namespaces and types, we're permitted to check that the entity
2962   // is named via the same tokens. We should probably do so.
2963   switch (X->getKind()) {
2964   case NestedNameSpecifier::Identifier:
2965     if (X->getAsIdentifier() != Y->getAsIdentifier())
2966       return false;
2967     break;
2968   case NestedNameSpecifier::Namespace:
2969   case NestedNameSpecifier::NamespaceAlias:
2970     // We've already checked that we named the same namespace.
2971     break;
2972   case NestedNameSpecifier::TypeSpec:
2973   case NestedNameSpecifier::TypeSpecWithTemplate:
2974     if (X->getAsType()->getCanonicalTypeInternal() !=
2975         Y->getAsType()->getCanonicalTypeInternal())
2976       return false;
2977     break;
2978   case NestedNameSpecifier::Global:
2979   case NestedNameSpecifier::Super:
2980     return true;
2981   }
2982 
2983   // Recurse into earlier portion of NNS, if any.
2984   auto *PX = X->getPrefix();
2985   auto *PY = Y->getPrefix();
2986   if (PX && PY)
2987     return isSameQualifier(PX, PY);
2988   return !PX && !PY;
2989 }
2990 
2991 /// Determine whether two template parameter lists are similar enough
2992 /// that they may be used in declarations of the same template.
2993 static bool isSameTemplateParameterList(const ASTContext &C,
2994                                         const TemplateParameterList *X,
2995                                         const TemplateParameterList *Y) {
2996   if (X->size() != Y->size())
2997     return false;
2998 
2999   for (unsigned I = 0, N = X->size(); I != N; ++I)
3000     if (!isSameTemplateParameter(X->getParam(I), Y->getParam(I)))
3001       return false;
3002 
3003   const Expr *XRC = X->getRequiresClause();
3004   const Expr *YRC = Y->getRequiresClause();
3005   if (!XRC != !YRC)
3006     return false;
3007   if (XRC) {
3008     llvm::FoldingSetNodeID XRCID, YRCID;
3009     XRC->Profile(XRCID, C, /*Canonical=*/true);
3010     YRC->Profile(YRCID, C, /*Canonical=*/true);
3011     if (XRCID != YRCID)
3012       return false;
3013   }
3014 
3015   return true;
3016 }
3017 
3018 /// Determine whether the attributes we can overload on are identical for A and
3019 /// B. Will ignore any overloadable attrs represented in the type of A and B.
3020 static bool hasSameOverloadableAttrs(const FunctionDecl *A,
3021                                      const FunctionDecl *B) {
3022   // Note that pass_object_size attributes are represented in the function's
3023   // ExtParameterInfo, so we don't need to check them here.
3024 
3025   llvm::FoldingSetNodeID Cand1ID, Cand2ID;
3026   auto AEnableIfAttrs = A->specific_attrs<EnableIfAttr>();
3027   auto BEnableIfAttrs = B->specific_attrs<EnableIfAttr>();
3028 
3029   for (auto Pair : zip_longest(AEnableIfAttrs, BEnableIfAttrs)) {
3030     Optional<EnableIfAttr *> Cand1A = std::get<0>(Pair);
3031     Optional<EnableIfAttr *> Cand2A = std::get<1>(Pair);
3032 
3033     // Return false if the number of enable_if attributes is different.
3034     if (!Cand1A || !Cand2A)
3035       return false;
3036 
3037     Cand1ID.clear();
3038     Cand2ID.clear();
3039 
3040     (*Cand1A)->getCond()->Profile(Cand1ID, A->getASTContext(), true);
3041     (*Cand2A)->getCond()->Profile(Cand2ID, B->getASTContext(), true);
3042 
3043     // Return false if any of the enable_if expressions of A and B are
3044     // different.
3045     if (Cand1ID != Cand2ID)
3046       return false;
3047   }
3048   return true;
3049 }
3050 
3051 /// Determine whether the two declarations refer to the same entity.pr
3052 static bool isSameEntity(NamedDecl *X, NamedDecl *Y) {
3053   assert(X->getDeclName() == Y->getDeclName() && "Declaration name mismatch!");
3054 
3055   if (X == Y)
3056     return true;
3057 
3058   // Must be in the same context.
3059   //
3060   // Note that we can't use DeclContext::Equals here, because the DeclContexts
3061   // could be two different declarations of the same function. (We will fix the
3062   // semantic DC to refer to the primary definition after merging.)
3063   if (!declaresSameEntity(cast<Decl>(X->getDeclContext()->getRedeclContext()),
3064                           cast<Decl>(Y->getDeclContext()->getRedeclContext())))
3065     return false;
3066 
3067   // Two typedefs refer to the same entity if they have the same underlying
3068   // type.
3069   if (const auto *TypedefX = dyn_cast<TypedefNameDecl>(X))
3070     if (const auto *TypedefY = dyn_cast<TypedefNameDecl>(Y))
3071       return X->getASTContext().hasSameType(TypedefX->getUnderlyingType(),
3072                                             TypedefY->getUnderlyingType());
3073 
3074   // Must have the same kind.
3075   if (X->getKind() != Y->getKind())
3076     return false;
3077 
3078   // Objective-C classes and protocols with the same name always match.
3079   if (isa<ObjCInterfaceDecl>(X) || isa<ObjCProtocolDecl>(X))
3080     return true;
3081 
3082   if (isa<ClassTemplateSpecializationDecl>(X)) {
3083     // No need to handle these here: we merge them when adding them to the
3084     // template.
3085     return false;
3086   }
3087 
3088   // Compatible tags match.
3089   if (const auto *TagX = dyn_cast<TagDecl>(X)) {
3090     const auto *TagY = cast<TagDecl>(Y);
3091     return (TagX->getTagKind() == TagY->getTagKind()) ||
3092       ((TagX->getTagKind() == TTK_Struct || TagX->getTagKind() == TTK_Class ||
3093         TagX->getTagKind() == TTK_Interface) &&
3094        (TagY->getTagKind() == TTK_Struct || TagY->getTagKind() == TTK_Class ||
3095         TagY->getTagKind() == TTK_Interface));
3096   }
3097 
3098   // Functions with the same type and linkage match.
3099   // FIXME: This needs to cope with merging of prototyped/non-prototyped
3100   // functions, etc.
3101   if (const auto *FuncX = dyn_cast<FunctionDecl>(X)) {
3102     const auto *FuncY = cast<FunctionDecl>(Y);
3103     if (const auto *CtorX = dyn_cast<CXXConstructorDecl>(X)) {
3104       const auto *CtorY = cast<CXXConstructorDecl>(Y);
3105       if (CtorX->getInheritedConstructor() &&
3106           !isSameEntity(CtorX->getInheritedConstructor().getConstructor(),
3107                         CtorY->getInheritedConstructor().getConstructor()))
3108         return false;
3109     }
3110 
3111     if (FuncX->isMultiVersion() != FuncY->isMultiVersion())
3112       return false;
3113 
3114     // Multiversioned functions with different feature strings are represented
3115     // as separate declarations.
3116     if (FuncX->isMultiVersion()) {
3117       const auto *TAX = FuncX->getAttr<TargetAttr>();
3118       const auto *TAY = FuncY->getAttr<TargetAttr>();
3119       assert(TAX && TAY && "Multiversion Function without target attribute");
3120 
3121       if (TAX->getFeaturesStr() != TAY->getFeaturesStr())
3122         return false;
3123     }
3124 
3125     ASTContext &C = FuncX->getASTContext();
3126 
3127     const Expr *XRC = FuncX->getTrailingRequiresClause();
3128     const Expr *YRC = FuncY->getTrailingRequiresClause();
3129     if (!XRC != !YRC)
3130       return false;
3131     if (XRC) {
3132       llvm::FoldingSetNodeID XRCID, YRCID;
3133       XRC->Profile(XRCID, C, /*Canonical=*/true);
3134       YRC->Profile(YRCID, C, /*Canonical=*/true);
3135       if (XRCID != YRCID)
3136         return false;
3137     }
3138 
3139     auto GetTypeAsWritten = [](const FunctionDecl *FD) {
3140       // Map to the first declaration that we've already merged into this one.
3141       // The TSI of redeclarations might not match (due to calling conventions
3142       // being inherited onto the type but not the TSI), but the TSI type of
3143       // the first declaration of the function should match across modules.
3144       FD = FD->getCanonicalDecl();
3145       return FD->getTypeSourceInfo() ? FD->getTypeSourceInfo()->getType()
3146                                      : FD->getType();
3147     };
3148     QualType XT = GetTypeAsWritten(FuncX), YT = GetTypeAsWritten(FuncY);
3149     if (!C.hasSameType(XT, YT)) {
3150       // We can get functions with different types on the redecl chain in C++17
3151       // if they have differing exception specifications and at least one of
3152       // the excpetion specs is unresolved.
3153       auto *XFPT = XT->getAs<FunctionProtoType>();
3154       auto *YFPT = YT->getAs<FunctionProtoType>();
3155       if (C.getLangOpts().CPlusPlus17 && XFPT && YFPT &&
3156           (isUnresolvedExceptionSpec(XFPT->getExceptionSpecType()) ||
3157            isUnresolvedExceptionSpec(YFPT->getExceptionSpecType())) &&
3158           C.hasSameFunctionTypeIgnoringExceptionSpec(XT, YT))
3159         return true;
3160       return false;
3161     }
3162 
3163     return FuncX->getLinkageInternal() == FuncY->getLinkageInternal() &&
3164            hasSameOverloadableAttrs(FuncX, FuncY);
3165   }
3166 
3167   // Variables with the same type and linkage match.
3168   if (const auto *VarX = dyn_cast<VarDecl>(X)) {
3169     const auto *VarY = cast<VarDecl>(Y);
3170     if (VarX->getLinkageInternal() == VarY->getLinkageInternal()) {
3171       ASTContext &C = VarX->getASTContext();
3172       if (C.hasSameType(VarX->getType(), VarY->getType()))
3173         return true;
3174 
3175       // We can get decls with different types on the redecl chain. Eg.
3176       // template <typename T> struct S { static T Var[]; }; // #1
3177       // template <typename T> T S<T>::Var[sizeof(T)]; // #2
3178       // Only? happens when completing an incomplete array type. In this case
3179       // when comparing #1 and #2 we should go through their element type.
3180       const ArrayType *VarXTy = C.getAsArrayType(VarX->getType());
3181       const ArrayType *VarYTy = C.getAsArrayType(VarY->getType());
3182       if (!VarXTy || !VarYTy)
3183         return false;
3184       if (VarXTy->isIncompleteArrayType() || VarYTy->isIncompleteArrayType())
3185         return C.hasSameType(VarXTy->getElementType(), VarYTy->getElementType());
3186     }
3187     return false;
3188   }
3189 
3190   // Namespaces with the same name and inlinedness match.
3191   if (const auto *NamespaceX = dyn_cast<NamespaceDecl>(X)) {
3192     const auto *NamespaceY = cast<NamespaceDecl>(Y);
3193     return NamespaceX->isInline() == NamespaceY->isInline();
3194   }
3195 
3196   // Identical template names and kinds match if their template parameter lists
3197   // and patterns match.
3198   if (const auto *TemplateX = dyn_cast<TemplateDecl>(X)) {
3199     const auto *TemplateY = cast<TemplateDecl>(Y);
3200     return isSameEntity(TemplateX->getTemplatedDecl(),
3201                         TemplateY->getTemplatedDecl()) &&
3202            isSameTemplateParameterList(TemplateX->getASTContext(),
3203                                        TemplateX->getTemplateParameters(),
3204                                        TemplateY->getTemplateParameters());
3205   }
3206 
3207   // Fields with the same name and the same type match.
3208   if (const auto *FDX = dyn_cast<FieldDecl>(X)) {
3209     const auto *FDY = cast<FieldDecl>(Y);
3210     // FIXME: Also check the bitwidth is odr-equivalent, if any.
3211     return X->getASTContext().hasSameType(FDX->getType(), FDY->getType());
3212   }
3213 
3214   // Indirect fields with the same target field match.
3215   if (const auto *IFDX = dyn_cast<IndirectFieldDecl>(X)) {
3216     const auto *IFDY = cast<IndirectFieldDecl>(Y);
3217     return IFDX->getAnonField()->getCanonicalDecl() ==
3218            IFDY->getAnonField()->getCanonicalDecl();
3219   }
3220 
3221   // Enumerators with the same name match.
3222   if (isa<EnumConstantDecl>(X))
3223     // FIXME: Also check the value is odr-equivalent.
3224     return true;
3225 
3226   // Using shadow declarations with the same target match.
3227   if (const auto *USX = dyn_cast<UsingShadowDecl>(X)) {
3228     const auto *USY = cast<UsingShadowDecl>(Y);
3229     return USX->getTargetDecl() == USY->getTargetDecl();
3230   }
3231 
3232   // Using declarations with the same qualifier match. (We already know that
3233   // the name matches.)
3234   if (const auto *UX = dyn_cast<UsingDecl>(X)) {
3235     const auto *UY = cast<UsingDecl>(Y);
3236     return isSameQualifier(UX->getQualifier(), UY->getQualifier()) &&
3237            UX->hasTypename() == UY->hasTypename() &&
3238            UX->isAccessDeclaration() == UY->isAccessDeclaration();
3239   }
3240   if (const auto *UX = dyn_cast<UnresolvedUsingValueDecl>(X)) {
3241     const auto *UY = cast<UnresolvedUsingValueDecl>(Y);
3242     return isSameQualifier(UX->getQualifier(), UY->getQualifier()) &&
3243            UX->isAccessDeclaration() == UY->isAccessDeclaration();
3244   }
3245   if (const auto *UX = dyn_cast<UnresolvedUsingTypenameDecl>(X))
3246     return isSameQualifier(
3247         UX->getQualifier(),
3248         cast<UnresolvedUsingTypenameDecl>(Y)->getQualifier());
3249 
3250   // Namespace alias definitions with the same target match.
3251   if (const auto *NAX = dyn_cast<NamespaceAliasDecl>(X)) {
3252     const auto *NAY = cast<NamespaceAliasDecl>(Y);
3253     return NAX->getNamespace()->Equals(NAY->getNamespace());
3254   }
3255 
3256   return false;
3257 }
3258 
3259 /// Find the context in which we should search for previous declarations when
3260 /// looking for declarations to merge.
3261 DeclContext *ASTDeclReader::getPrimaryContextForMerging(ASTReader &Reader,
3262                                                         DeclContext *DC) {
3263   if (auto *ND = dyn_cast<NamespaceDecl>(DC))
3264     return ND->getOriginalNamespace();
3265 
3266   if (auto *RD = dyn_cast<CXXRecordDecl>(DC)) {
3267     // Try to dig out the definition.
3268     auto *DD = RD->DefinitionData;
3269     if (!DD)
3270       DD = RD->getCanonicalDecl()->DefinitionData;
3271 
3272     // If there's no definition yet, then DC's definition is added by an update
3273     // record, but we've not yet loaded that update record. In this case, we
3274     // commit to DC being the canonical definition now, and will fix this when
3275     // we load the update record.
3276     if (!DD) {
3277       DD = new (Reader.getContext()) struct CXXRecordDecl::DefinitionData(RD);
3278       RD->setCompleteDefinition(true);
3279       RD->DefinitionData = DD;
3280       RD->getCanonicalDecl()->DefinitionData = DD;
3281 
3282       // Track that we did this horrible thing so that we can fix it later.
3283       Reader.PendingFakeDefinitionData.insert(
3284           std::make_pair(DD, ASTReader::PendingFakeDefinitionKind::Fake));
3285     }
3286 
3287     return DD->Definition;
3288   }
3289 
3290   if (auto *ED = dyn_cast<EnumDecl>(DC))
3291     return ED->getASTContext().getLangOpts().CPlusPlus? ED->getDefinition()
3292                                                       : nullptr;
3293 
3294   // We can see the TU here only if we have no Sema object. In that case,
3295   // there's no TU scope to look in, so using the DC alone is sufficient.
3296   if (auto *TU = dyn_cast<TranslationUnitDecl>(DC))
3297     return TU;
3298 
3299   return nullptr;
3300 }
3301 
3302 ASTDeclReader::FindExistingResult::~FindExistingResult() {
3303   // Record that we had a typedef name for linkage whether or not we merge
3304   // with that declaration.
3305   if (TypedefNameForLinkage) {
3306     DeclContext *DC = New->getDeclContext()->getRedeclContext();
3307     Reader.ImportedTypedefNamesForLinkage.insert(
3308         std::make_pair(std::make_pair(DC, TypedefNameForLinkage), New));
3309     return;
3310   }
3311 
3312   if (!AddResult || Existing)
3313     return;
3314 
3315   DeclarationName Name = New->getDeclName();
3316   DeclContext *DC = New->getDeclContext()->getRedeclContext();
3317   if (needsAnonymousDeclarationNumber(New)) {
3318     setAnonymousDeclForMerging(Reader, New->getLexicalDeclContext(),
3319                                AnonymousDeclNumber, New);
3320   } else if (DC->isTranslationUnit() &&
3321              !Reader.getContext().getLangOpts().CPlusPlus) {
3322     if (Reader.getIdResolver().tryAddTopLevelDecl(New, Name))
3323       Reader.PendingFakeLookupResults[Name.getAsIdentifierInfo()]
3324             .push_back(New);
3325   } else if (DeclContext *MergeDC = getPrimaryContextForMerging(Reader, DC)) {
3326     // Add the declaration to its redeclaration context so later merging
3327     // lookups will find it.
3328     MergeDC->makeDeclVisibleInContextImpl(New, /*Internal*/true);
3329   }
3330 }
3331 
3332 /// Find the declaration that should be merged into, given the declaration found
3333 /// by name lookup. If we're merging an anonymous declaration within a typedef,
3334 /// we need a matching typedef, and we merge with the type inside it.
3335 static NamedDecl *getDeclForMerging(NamedDecl *Found,
3336                                     bool IsTypedefNameForLinkage) {
3337   if (!IsTypedefNameForLinkage)
3338     return Found;
3339 
3340   // If we found a typedef declaration that gives a name to some other
3341   // declaration, then we want that inner declaration. Declarations from
3342   // AST files are handled via ImportedTypedefNamesForLinkage.
3343   if (Found->isFromASTFile())
3344     return nullptr;
3345 
3346   if (auto *TND = dyn_cast<TypedefNameDecl>(Found))
3347     return TND->getAnonDeclWithTypedefName(/*AnyRedecl*/true);
3348 
3349   return nullptr;
3350 }
3351 
3352 /// Find the declaration to use to populate the anonymous declaration table
3353 /// for the given lexical DeclContext. We only care about finding local
3354 /// definitions of the context; we'll merge imported ones as we go.
3355 DeclContext *
3356 ASTDeclReader::getPrimaryDCForAnonymousDecl(DeclContext *LexicalDC) {
3357   // For classes, we track the definition as we merge.
3358   if (auto *RD = dyn_cast<CXXRecordDecl>(LexicalDC)) {
3359     auto *DD = RD->getCanonicalDecl()->DefinitionData;
3360     return DD ? DD->Definition : nullptr;
3361   }
3362 
3363   // For anything else, walk its merged redeclarations looking for a definition.
3364   // Note that we can't just call getDefinition here because the redeclaration
3365   // chain isn't wired up.
3366   for (auto *D : merged_redecls(cast<Decl>(LexicalDC))) {
3367     if (auto *FD = dyn_cast<FunctionDecl>(D))
3368       if (FD->isThisDeclarationADefinition())
3369         return FD;
3370     if (auto *MD = dyn_cast<ObjCMethodDecl>(D))
3371       if (MD->isThisDeclarationADefinition())
3372         return MD;
3373   }
3374 
3375   // No merged definition yet.
3376   return nullptr;
3377 }
3378 
3379 NamedDecl *ASTDeclReader::getAnonymousDeclForMerging(ASTReader &Reader,
3380                                                      DeclContext *DC,
3381                                                      unsigned Index) {
3382   // If the lexical context has been merged, look into the now-canonical
3383   // definition.
3384   auto *CanonDC = cast<Decl>(DC)->getCanonicalDecl();
3385 
3386   // If we've seen this before, return the canonical declaration.
3387   auto &Previous = Reader.AnonymousDeclarationsForMerging[CanonDC];
3388   if (Index < Previous.size() && Previous[Index])
3389     return Previous[Index];
3390 
3391   // If this is the first time, but we have parsed a declaration of the context,
3392   // build the anonymous declaration list from the parsed declaration.
3393   auto *PrimaryDC = getPrimaryDCForAnonymousDecl(DC);
3394   if (PrimaryDC && !cast<Decl>(PrimaryDC)->isFromASTFile()) {
3395     numberAnonymousDeclsWithin(PrimaryDC, [&](NamedDecl *ND, unsigned Number) {
3396       if (Previous.size() == Number)
3397         Previous.push_back(cast<NamedDecl>(ND->getCanonicalDecl()));
3398       else
3399         Previous[Number] = cast<NamedDecl>(ND->getCanonicalDecl());
3400     });
3401   }
3402 
3403   return Index < Previous.size() ? Previous[Index] : nullptr;
3404 }
3405 
3406 void ASTDeclReader::setAnonymousDeclForMerging(ASTReader &Reader,
3407                                                DeclContext *DC, unsigned Index,
3408                                                NamedDecl *D) {
3409   auto *CanonDC = cast<Decl>(DC)->getCanonicalDecl();
3410 
3411   auto &Previous = Reader.AnonymousDeclarationsForMerging[CanonDC];
3412   if (Index >= Previous.size())
3413     Previous.resize(Index + 1);
3414   if (!Previous[Index])
3415     Previous[Index] = D;
3416 }
3417 
3418 ASTDeclReader::FindExistingResult ASTDeclReader::findExisting(NamedDecl *D) {
3419   DeclarationName Name = TypedefNameForLinkage ? TypedefNameForLinkage
3420                                                : D->getDeclName();
3421 
3422   if (!Name && !needsAnonymousDeclarationNumber(D)) {
3423     // Don't bother trying to find unnamed declarations that are in
3424     // unmergeable contexts.
3425     FindExistingResult Result(Reader, D, /*Existing=*/nullptr,
3426                               AnonymousDeclNumber, TypedefNameForLinkage);
3427     Result.suppress();
3428     return Result;
3429   }
3430 
3431   DeclContext *DC = D->getDeclContext()->getRedeclContext();
3432   if (TypedefNameForLinkage) {
3433     auto It = Reader.ImportedTypedefNamesForLinkage.find(
3434         std::make_pair(DC, TypedefNameForLinkage));
3435     if (It != Reader.ImportedTypedefNamesForLinkage.end())
3436       if (isSameEntity(It->second, D))
3437         return FindExistingResult(Reader, D, It->second, AnonymousDeclNumber,
3438                                   TypedefNameForLinkage);
3439     // Go on to check in other places in case an existing typedef name
3440     // was not imported.
3441   }
3442 
3443   if (needsAnonymousDeclarationNumber(D)) {
3444     // This is an anonymous declaration that we may need to merge. Look it up
3445     // in its context by number.
3446     if (auto *Existing = getAnonymousDeclForMerging(
3447             Reader, D->getLexicalDeclContext(), AnonymousDeclNumber))
3448       if (isSameEntity(Existing, D))
3449         return FindExistingResult(Reader, D, Existing, AnonymousDeclNumber,
3450                                   TypedefNameForLinkage);
3451   } else if (DC->isTranslationUnit() &&
3452              !Reader.getContext().getLangOpts().CPlusPlus) {
3453     IdentifierResolver &IdResolver = Reader.getIdResolver();
3454 
3455     // Temporarily consider the identifier to be up-to-date. We don't want to
3456     // cause additional lookups here.
3457     class UpToDateIdentifierRAII {
3458       IdentifierInfo *II;
3459       bool WasOutToDate = false;
3460 
3461     public:
3462       explicit UpToDateIdentifierRAII(IdentifierInfo *II) : II(II) {
3463         if (II) {
3464           WasOutToDate = II->isOutOfDate();
3465           if (WasOutToDate)
3466             II->setOutOfDate(false);
3467         }
3468       }
3469 
3470       ~UpToDateIdentifierRAII() {
3471         if (WasOutToDate)
3472           II->setOutOfDate(true);
3473       }
3474     } UpToDate(Name.getAsIdentifierInfo());
3475 
3476     for (IdentifierResolver::iterator I = IdResolver.begin(Name),
3477                                    IEnd = IdResolver.end();
3478          I != IEnd; ++I) {
3479       if (NamedDecl *Existing = getDeclForMerging(*I, TypedefNameForLinkage))
3480         if (isSameEntity(Existing, D))
3481           return FindExistingResult(Reader, D, Existing, AnonymousDeclNumber,
3482                                     TypedefNameForLinkage);
3483     }
3484   } else if (DeclContext *MergeDC = getPrimaryContextForMerging(Reader, DC)) {
3485     DeclContext::lookup_result R = MergeDC->noload_lookup(Name);
3486     for (DeclContext::lookup_iterator I = R.begin(), E = R.end(); I != E; ++I) {
3487       if (NamedDecl *Existing = getDeclForMerging(*I, TypedefNameForLinkage))
3488         if (isSameEntity(Existing, D))
3489           return FindExistingResult(Reader, D, Existing, AnonymousDeclNumber,
3490                                     TypedefNameForLinkage);
3491     }
3492   } else {
3493     // Not in a mergeable context.
3494     return FindExistingResult(Reader);
3495   }
3496 
3497   // If this declaration is from a merged context, make a note that we need to
3498   // check that the canonical definition of that context contains the decl.
3499   //
3500   // FIXME: We should do something similar if we merge two definitions of the
3501   // same template specialization into the same CXXRecordDecl.
3502   auto MergedDCIt = Reader.MergedDeclContexts.find(D->getLexicalDeclContext());
3503   if (MergedDCIt != Reader.MergedDeclContexts.end() &&
3504       MergedDCIt->second == D->getDeclContext())
3505     Reader.PendingOdrMergeChecks.push_back(D);
3506 
3507   return FindExistingResult(Reader, D, /*Existing=*/nullptr,
3508                             AnonymousDeclNumber, TypedefNameForLinkage);
3509 }
3510 
3511 template<typename DeclT>
3512 Decl *ASTDeclReader::getMostRecentDeclImpl(Redeclarable<DeclT> *D) {
3513   return D->RedeclLink.getLatestNotUpdated();
3514 }
3515 
3516 Decl *ASTDeclReader::getMostRecentDeclImpl(...) {
3517   llvm_unreachable("getMostRecentDecl on non-redeclarable declaration");
3518 }
3519 
3520 Decl *ASTDeclReader::getMostRecentDecl(Decl *D) {
3521   assert(D);
3522 
3523   switch (D->getKind()) {
3524 #define ABSTRACT_DECL(TYPE)
3525 #define DECL(TYPE, BASE)                               \
3526   case Decl::TYPE:                                     \
3527     return getMostRecentDeclImpl(cast<TYPE##Decl>(D));
3528 #include "clang/AST/DeclNodes.inc"
3529   }
3530   llvm_unreachable("unknown decl kind");
3531 }
3532 
3533 Decl *ASTReader::getMostRecentExistingDecl(Decl *D) {
3534   return ASTDeclReader::getMostRecentDecl(D->getCanonicalDecl());
3535 }
3536 
3537 void ASTDeclReader::mergeInheritableAttributes(ASTReader &Reader, Decl *D,
3538                                                Decl *Previous) {
3539   InheritableAttr *NewAttr = nullptr;
3540   ASTContext &Context = Reader.getContext();
3541   const auto *IA = Previous->getAttr<MSInheritanceAttr>();
3542 
3543   if (IA && !D->hasAttr<MSInheritanceAttr>()) {
3544     NewAttr = cast<InheritableAttr>(IA->clone(Context));
3545     NewAttr->setInherited(true);
3546     D->addAttr(NewAttr);
3547   }
3548 }
3549 
3550 template<typename DeclT>
3551 void ASTDeclReader::attachPreviousDeclImpl(ASTReader &Reader,
3552                                            Redeclarable<DeclT> *D,
3553                                            Decl *Previous, Decl *Canon) {
3554   D->RedeclLink.setPrevious(cast<DeclT>(Previous));
3555   D->First = cast<DeclT>(Previous)->First;
3556 }
3557 
3558 namespace clang {
3559 
3560 template<>
3561 void ASTDeclReader::attachPreviousDeclImpl(ASTReader &Reader,
3562                                            Redeclarable<VarDecl> *D,
3563                                            Decl *Previous, Decl *Canon) {
3564   auto *VD = static_cast<VarDecl *>(D);
3565   auto *PrevVD = cast<VarDecl>(Previous);
3566   D->RedeclLink.setPrevious(PrevVD);
3567   D->First = PrevVD->First;
3568 
3569   // We should keep at most one definition on the chain.
3570   // FIXME: Cache the definition once we've found it. Building a chain with
3571   // N definitions currently takes O(N^2) time here.
3572   if (VD->isThisDeclarationADefinition() == VarDecl::Definition) {
3573     for (VarDecl *CurD = PrevVD; CurD; CurD = CurD->getPreviousDecl()) {
3574       if (CurD->isThisDeclarationADefinition() == VarDecl::Definition) {
3575         Reader.mergeDefinitionVisibility(CurD, VD);
3576         VD->demoteThisDefinitionToDeclaration();
3577         break;
3578       }
3579     }
3580   }
3581 }
3582 
3583 static bool isUndeducedReturnType(QualType T) {
3584   auto *DT = T->getContainedDeducedType();
3585   return DT && !DT->isDeduced();
3586 }
3587 
3588 template<>
3589 void ASTDeclReader::attachPreviousDeclImpl(ASTReader &Reader,
3590                                            Redeclarable<FunctionDecl> *D,
3591                                            Decl *Previous, Decl *Canon) {
3592   auto *FD = static_cast<FunctionDecl *>(D);
3593   auto *PrevFD = cast<FunctionDecl>(Previous);
3594 
3595   FD->RedeclLink.setPrevious(PrevFD);
3596   FD->First = PrevFD->First;
3597 
3598   // If the previous declaration is an inline function declaration, then this
3599   // declaration is too.
3600   if (PrevFD->isInlined() != FD->isInlined()) {
3601     // FIXME: [dcl.fct.spec]p4:
3602     //   If a function with external linkage is declared inline in one
3603     //   translation unit, it shall be declared inline in all translation
3604     //   units in which it appears.
3605     //
3606     // Be careful of this case:
3607     //
3608     // module A:
3609     //   template<typename T> struct X { void f(); };
3610     //   template<typename T> inline void X<T>::f() {}
3611     //
3612     // module B instantiates the declaration of X<int>::f
3613     // module C instantiates the definition of X<int>::f
3614     //
3615     // If module B and C are merged, we do not have a violation of this rule.
3616     FD->setImplicitlyInline(true);
3617   }
3618 
3619   auto *FPT = FD->getType()->getAs<FunctionProtoType>();
3620   auto *PrevFPT = PrevFD->getType()->getAs<FunctionProtoType>();
3621   if (FPT && PrevFPT) {
3622     // If we need to propagate an exception specification along the redecl
3623     // chain, make a note of that so that we can do so later.
3624     bool IsUnresolved = isUnresolvedExceptionSpec(FPT->getExceptionSpecType());
3625     bool WasUnresolved =
3626         isUnresolvedExceptionSpec(PrevFPT->getExceptionSpecType());
3627     if (IsUnresolved != WasUnresolved)
3628       Reader.PendingExceptionSpecUpdates.insert(
3629           {Canon, IsUnresolved ? PrevFD : FD});
3630 
3631     // If we need to propagate a deduced return type along the redecl chain,
3632     // make a note of that so that we can do it later.
3633     bool IsUndeduced = isUndeducedReturnType(FPT->getReturnType());
3634     bool WasUndeduced = isUndeducedReturnType(PrevFPT->getReturnType());
3635     if (IsUndeduced != WasUndeduced)
3636       Reader.PendingDeducedTypeUpdates.insert(
3637           {cast<FunctionDecl>(Canon),
3638            (IsUndeduced ? PrevFPT : FPT)->getReturnType()});
3639   }
3640 }
3641 
3642 } // namespace clang
3643 
3644 void ASTDeclReader::attachPreviousDeclImpl(ASTReader &Reader, ...) {
3645   llvm_unreachable("attachPreviousDecl on non-redeclarable declaration");
3646 }
3647 
3648 /// Inherit the default template argument from \p From to \p To. Returns
3649 /// \c false if there is no default template for \p From.
3650 template <typename ParmDecl>
3651 static bool inheritDefaultTemplateArgument(ASTContext &Context, ParmDecl *From,
3652                                            Decl *ToD) {
3653   auto *To = cast<ParmDecl>(ToD);
3654   if (!From->hasDefaultArgument())
3655     return false;
3656   To->setInheritedDefaultArgument(Context, From);
3657   return true;
3658 }
3659 
3660 static void inheritDefaultTemplateArguments(ASTContext &Context,
3661                                             TemplateDecl *From,
3662                                             TemplateDecl *To) {
3663   auto *FromTP = From->getTemplateParameters();
3664   auto *ToTP = To->getTemplateParameters();
3665   assert(FromTP->size() == ToTP->size() && "merged mismatched templates?");
3666 
3667   for (unsigned I = 0, N = FromTP->size(); I != N; ++I) {
3668     NamedDecl *FromParam = FromTP->getParam(I);
3669     NamedDecl *ToParam = ToTP->getParam(I);
3670 
3671     if (auto *FTTP = dyn_cast<TemplateTypeParmDecl>(FromParam))
3672       inheritDefaultTemplateArgument(Context, FTTP, ToParam);
3673     else if (auto *FNTTP = dyn_cast<NonTypeTemplateParmDecl>(FromParam))
3674       inheritDefaultTemplateArgument(Context, FNTTP, ToParam);
3675     else
3676       inheritDefaultTemplateArgument(
3677               Context, cast<TemplateTemplateParmDecl>(FromParam), ToParam);
3678   }
3679 }
3680 
3681 void ASTDeclReader::attachPreviousDecl(ASTReader &Reader, Decl *D,
3682                                        Decl *Previous, Decl *Canon) {
3683   assert(D && Previous);
3684 
3685   switch (D->getKind()) {
3686 #define ABSTRACT_DECL(TYPE)
3687 #define DECL(TYPE, BASE)                                                  \
3688   case Decl::TYPE:                                                        \
3689     attachPreviousDeclImpl(Reader, cast<TYPE##Decl>(D), Previous, Canon); \
3690     break;
3691 #include "clang/AST/DeclNodes.inc"
3692   }
3693 
3694   // If the declaration was visible in one module, a redeclaration of it in
3695   // another module remains visible even if it wouldn't be visible by itself.
3696   //
3697   // FIXME: In this case, the declaration should only be visible if a module
3698   //        that makes it visible has been imported.
3699   D->IdentifierNamespace |=
3700       Previous->IdentifierNamespace &
3701       (Decl::IDNS_Ordinary | Decl::IDNS_Tag | Decl::IDNS_Type);
3702 
3703   // If the declaration declares a template, it may inherit default arguments
3704   // from the previous declaration.
3705   if (auto *TD = dyn_cast<TemplateDecl>(D))
3706     inheritDefaultTemplateArguments(Reader.getContext(),
3707                                     cast<TemplateDecl>(Previous), TD);
3708 
3709   // If any of the declaration in the chain contains an Inheritable attribute,
3710   // it needs to be added to all the declarations in the redeclarable chain.
3711   // FIXME: Only the logic of merging MSInheritableAttr is present, it should
3712   // be extended for all inheritable attributes.
3713   mergeInheritableAttributes(Reader, D, Previous);
3714 }
3715 
3716 template<typename DeclT>
3717 void ASTDeclReader::attachLatestDeclImpl(Redeclarable<DeclT> *D, Decl *Latest) {
3718   D->RedeclLink.setLatest(cast<DeclT>(Latest));
3719 }
3720 
3721 void ASTDeclReader::attachLatestDeclImpl(...) {
3722   llvm_unreachable("attachLatestDecl on non-redeclarable declaration");
3723 }
3724 
3725 void ASTDeclReader::attachLatestDecl(Decl *D, Decl *Latest) {
3726   assert(D && Latest);
3727 
3728   switch (D->getKind()) {
3729 #define ABSTRACT_DECL(TYPE)
3730 #define DECL(TYPE, BASE)                                  \
3731   case Decl::TYPE:                                        \
3732     attachLatestDeclImpl(cast<TYPE##Decl>(D), Latest); \
3733     break;
3734 #include "clang/AST/DeclNodes.inc"
3735   }
3736 }
3737 
3738 template<typename DeclT>
3739 void ASTDeclReader::markIncompleteDeclChainImpl(Redeclarable<DeclT> *D) {
3740   D->RedeclLink.markIncomplete();
3741 }
3742 
3743 void ASTDeclReader::markIncompleteDeclChainImpl(...) {
3744   llvm_unreachable("markIncompleteDeclChain on non-redeclarable declaration");
3745 }
3746 
3747 void ASTReader::markIncompleteDeclChain(Decl *D) {
3748   switch (D->getKind()) {
3749 #define ABSTRACT_DECL(TYPE)
3750 #define DECL(TYPE, BASE)                                             \
3751   case Decl::TYPE:                                                   \
3752     ASTDeclReader::markIncompleteDeclChainImpl(cast<TYPE##Decl>(D)); \
3753     break;
3754 #include "clang/AST/DeclNodes.inc"
3755   }
3756 }
3757 
3758 /// Read the declaration at the given offset from the AST file.
3759 Decl *ASTReader::ReadDeclRecord(DeclID ID) {
3760   unsigned Index = ID - NUM_PREDEF_DECL_IDS;
3761   SourceLocation DeclLoc;
3762   RecordLocation Loc = DeclCursorForID(ID, DeclLoc);
3763   llvm::BitstreamCursor &DeclsCursor = Loc.F->DeclsCursor;
3764   // Keep track of where we are in the stream, then jump back there
3765   // after reading this declaration.
3766   SavedStreamPosition SavedPosition(DeclsCursor);
3767 
3768   ReadingKindTracker ReadingKind(Read_Decl, *this);
3769 
3770   // Note that we are loading a declaration record.
3771   Deserializing ADecl(this);
3772 
3773   auto Fail = [](const char *what, llvm::Error &&Err) {
3774     llvm::report_fatal_error(Twine("ASTReader::readDeclRecord failed ") + what +
3775                              ": " + toString(std::move(Err)));
3776   };
3777 
3778   if (llvm::Error JumpFailed = DeclsCursor.JumpToBit(Loc.Offset))
3779     Fail("jumping", std::move(JumpFailed));
3780   ASTRecordReader Record(*this, *Loc.F);
3781   ASTDeclReader Reader(*this, Record, Loc, ID, DeclLoc);
3782   Expected<unsigned> MaybeCode = DeclsCursor.ReadCode();
3783   if (!MaybeCode)
3784     Fail("reading code", MaybeCode.takeError());
3785   unsigned Code = MaybeCode.get();
3786 
3787   ASTContext &Context = getContext();
3788   Decl *D = nullptr;
3789   Expected<unsigned> MaybeDeclCode = Record.readRecord(DeclsCursor, Code);
3790   if (!MaybeDeclCode)
3791     llvm::report_fatal_error(
3792         "ASTReader::readDeclRecord failed reading decl code: " +
3793         toString(MaybeDeclCode.takeError()));
3794   switch ((DeclCode)MaybeDeclCode.get()) {
3795   case DECL_CONTEXT_LEXICAL:
3796   case DECL_CONTEXT_VISIBLE:
3797     llvm_unreachable("Record cannot be de-serialized with readDeclRecord");
3798   case DECL_TYPEDEF:
3799     D = TypedefDecl::CreateDeserialized(Context, ID);
3800     break;
3801   case DECL_TYPEALIAS:
3802     D = TypeAliasDecl::CreateDeserialized(Context, ID);
3803     break;
3804   case DECL_ENUM:
3805     D = EnumDecl::CreateDeserialized(Context, ID);
3806     break;
3807   case DECL_RECORD:
3808     D = RecordDecl::CreateDeserialized(Context, ID);
3809     break;
3810   case DECL_ENUM_CONSTANT:
3811     D = EnumConstantDecl::CreateDeserialized(Context, ID);
3812     break;
3813   case DECL_FUNCTION:
3814     D = FunctionDecl::CreateDeserialized(Context, ID);
3815     break;
3816   case DECL_LINKAGE_SPEC:
3817     D = LinkageSpecDecl::CreateDeserialized(Context, ID);
3818     break;
3819   case DECL_EXPORT:
3820     D = ExportDecl::CreateDeserialized(Context, ID);
3821     break;
3822   case DECL_LABEL:
3823     D = LabelDecl::CreateDeserialized(Context, ID);
3824     break;
3825   case DECL_NAMESPACE:
3826     D = NamespaceDecl::CreateDeserialized(Context, ID);
3827     break;
3828   case DECL_NAMESPACE_ALIAS:
3829     D = NamespaceAliasDecl::CreateDeserialized(Context, ID);
3830     break;
3831   case DECL_USING:
3832     D = UsingDecl::CreateDeserialized(Context, ID);
3833     break;
3834   case DECL_USING_PACK:
3835     D = UsingPackDecl::CreateDeserialized(Context, ID, Record.readInt());
3836     break;
3837   case DECL_USING_SHADOW:
3838     D = UsingShadowDecl::CreateDeserialized(Context, ID);
3839     break;
3840   case DECL_CONSTRUCTOR_USING_SHADOW:
3841     D = ConstructorUsingShadowDecl::CreateDeserialized(Context, ID);
3842     break;
3843   case DECL_USING_DIRECTIVE:
3844     D = UsingDirectiveDecl::CreateDeserialized(Context, ID);
3845     break;
3846   case DECL_UNRESOLVED_USING_VALUE:
3847     D = UnresolvedUsingValueDecl::CreateDeserialized(Context, ID);
3848     break;
3849   case DECL_UNRESOLVED_USING_TYPENAME:
3850     D = UnresolvedUsingTypenameDecl::CreateDeserialized(Context, ID);
3851     break;
3852   case DECL_CXX_RECORD:
3853     D = CXXRecordDecl::CreateDeserialized(Context, ID);
3854     break;
3855   case DECL_CXX_DEDUCTION_GUIDE:
3856     D = CXXDeductionGuideDecl::CreateDeserialized(Context, ID);
3857     break;
3858   case DECL_CXX_METHOD:
3859     D = CXXMethodDecl::CreateDeserialized(Context, ID);
3860     break;
3861   case DECL_CXX_CONSTRUCTOR:
3862     D = CXXConstructorDecl::CreateDeserialized(Context, ID, Record.readInt());
3863     break;
3864   case DECL_CXX_DESTRUCTOR:
3865     D = CXXDestructorDecl::CreateDeserialized(Context, ID);
3866     break;
3867   case DECL_CXX_CONVERSION:
3868     D = CXXConversionDecl::CreateDeserialized(Context, ID);
3869     break;
3870   case DECL_ACCESS_SPEC:
3871     D = AccessSpecDecl::CreateDeserialized(Context, ID);
3872     break;
3873   case DECL_FRIEND:
3874     D = FriendDecl::CreateDeserialized(Context, ID, Record.readInt());
3875     break;
3876   case DECL_FRIEND_TEMPLATE:
3877     D = FriendTemplateDecl::CreateDeserialized(Context, ID);
3878     break;
3879   case DECL_CLASS_TEMPLATE:
3880     D = ClassTemplateDecl::CreateDeserialized(Context, ID);
3881     break;
3882   case DECL_CLASS_TEMPLATE_SPECIALIZATION:
3883     D = ClassTemplateSpecializationDecl::CreateDeserialized(Context, ID);
3884     break;
3885   case DECL_CLASS_TEMPLATE_PARTIAL_SPECIALIZATION:
3886     D = ClassTemplatePartialSpecializationDecl::CreateDeserialized(Context, ID);
3887     break;
3888   case DECL_VAR_TEMPLATE:
3889     D = VarTemplateDecl::CreateDeserialized(Context, ID);
3890     break;
3891   case DECL_VAR_TEMPLATE_SPECIALIZATION:
3892     D = VarTemplateSpecializationDecl::CreateDeserialized(Context, ID);
3893     break;
3894   case DECL_VAR_TEMPLATE_PARTIAL_SPECIALIZATION:
3895     D = VarTemplatePartialSpecializationDecl::CreateDeserialized(Context, ID);
3896     break;
3897   case DECL_CLASS_SCOPE_FUNCTION_SPECIALIZATION:
3898     D = ClassScopeFunctionSpecializationDecl::CreateDeserialized(Context, ID);
3899     break;
3900   case DECL_FUNCTION_TEMPLATE:
3901     D = FunctionTemplateDecl::CreateDeserialized(Context, ID);
3902     break;
3903   case DECL_TEMPLATE_TYPE_PARM: {
3904     bool HasTypeConstraint = Record.readInt();
3905     D = TemplateTypeParmDecl::CreateDeserialized(Context, ID,
3906                                                  HasTypeConstraint);
3907     break;
3908   }
3909   case DECL_NON_TYPE_TEMPLATE_PARM: {
3910     bool HasTypeConstraint = Record.readInt();
3911     D = NonTypeTemplateParmDecl::CreateDeserialized(Context, ID,
3912                                                     HasTypeConstraint);
3913     break;
3914   }
3915   case DECL_EXPANDED_NON_TYPE_TEMPLATE_PARM_PACK: {
3916     bool HasTypeConstraint = Record.readInt();
3917     D = NonTypeTemplateParmDecl::CreateDeserialized(Context, ID,
3918                                                     Record.readInt(),
3919                                                     HasTypeConstraint);
3920     break;
3921   }
3922   case DECL_TEMPLATE_TEMPLATE_PARM:
3923     D = TemplateTemplateParmDecl::CreateDeserialized(Context, ID);
3924     break;
3925   case DECL_EXPANDED_TEMPLATE_TEMPLATE_PARM_PACK:
3926     D = TemplateTemplateParmDecl::CreateDeserialized(Context, ID,
3927                                                      Record.readInt());
3928     break;
3929   case DECL_TYPE_ALIAS_TEMPLATE:
3930     D = TypeAliasTemplateDecl::CreateDeserialized(Context, ID);
3931     break;
3932   case DECL_CONCEPT:
3933     D = ConceptDecl::CreateDeserialized(Context, ID);
3934     break;
3935   case DECL_REQUIRES_EXPR_BODY:
3936     D = RequiresExprBodyDecl::CreateDeserialized(Context, ID);
3937     break;
3938   case DECL_STATIC_ASSERT:
3939     D = StaticAssertDecl::CreateDeserialized(Context, ID);
3940     break;
3941   case DECL_OBJC_METHOD:
3942     D = ObjCMethodDecl::CreateDeserialized(Context, ID);
3943     break;
3944   case DECL_OBJC_INTERFACE:
3945     D = ObjCInterfaceDecl::CreateDeserialized(Context, ID);
3946     break;
3947   case DECL_OBJC_IVAR:
3948     D = ObjCIvarDecl::CreateDeserialized(Context, ID);
3949     break;
3950   case DECL_OBJC_PROTOCOL:
3951     D = ObjCProtocolDecl::CreateDeserialized(Context, ID);
3952     break;
3953   case DECL_OBJC_AT_DEFS_FIELD:
3954     D = ObjCAtDefsFieldDecl::CreateDeserialized(Context, ID);
3955     break;
3956   case DECL_OBJC_CATEGORY:
3957     D = ObjCCategoryDecl::CreateDeserialized(Context, ID);
3958     break;
3959   case DECL_OBJC_CATEGORY_IMPL:
3960     D = ObjCCategoryImplDecl::CreateDeserialized(Context, ID);
3961     break;
3962   case DECL_OBJC_IMPLEMENTATION:
3963     D = ObjCImplementationDecl::CreateDeserialized(Context, ID);
3964     break;
3965   case DECL_OBJC_COMPATIBLE_ALIAS:
3966     D = ObjCCompatibleAliasDecl::CreateDeserialized(Context, ID);
3967     break;
3968   case DECL_OBJC_PROPERTY:
3969     D = ObjCPropertyDecl::CreateDeserialized(Context, ID);
3970     break;
3971   case DECL_OBJC_PROPERTY_IMPL:
3972     D = ObjCPropertyImplDecl::CreateDeserialized(Context, ID);
3973     break;
3974   case DECL_FIELD:
3975     D = FieldDecl::CreateDeserialized(Context, ID);
3976     break;
3977   case DECL_INDIRECTFIELD:
3978     D = IndirectFieldDecl::CreateDeserialized(Context, ID);
3979     break;
3980   case DECL_VAR:
3981     D = VarDecl::CreateDeserialized(Context, ID);
3982     break;
3983   case DECL_IMPLICIT_PARAM:
3984     D = ImplicitParamDecl::CreateDeserialized(Context, ID);
3985     break;
3986   case DECL_PARM_VAR:
3987     D = ParmVarDecl::CreateDeserialized(Context, ID);
3988     break;
3989   case DECL_DECOMPOSITION:
3990     D = DecompositionDecl::CreateDeserialized(Context, ID, Record.readInt());
3991     break;
3992   case DECL_BINDING:
3993     D = BindingDecl::CreateDeserialized(Context, ID);
3994     break;
3995   case DECL_FILE_SCOPE_ASM:
3996     D = FileScopeAsmDecl::CreateDeserialized(Context, ID);
3997     break;
3998   case DECL_BLOCK:
3999     D = BlockDecl::CreateDeserialized(Context, ID);
4000     break;
4001   case DECL_MS_PROPERTY:
4002     D = MSPropertyDecl::CreateDeserialized(Context, ID);
4003     break;
4004   case DECL_MS_GUID:
4005     D = MSGuidDecl::CreateDeserialized(Context, ID);
4006     break;
4007   case DECL_TEMPLATE_PARAM_OBJECT:
4008     D = TemplateParamObjectDecl::CreateDeserialized(Context, ID);
4009     break;
4010   case DECL_CAPTURED:
4011     D = CapturedDecl::CreateDeserialized(Context, ID, Record.readInt());
4012     break;
4013   case DECL_CXX_BASE_SPECIFIERS:
4014     Error("attempt to read a C++ base-specifier record as a declaration");
4015     return nullptr;
4016   case DECL_CXX_CTOR_INITIALIZERS:
4017     Error("attempt to read a C++ ctor initializer record as a declaration");
4018     return nullptr;
4019   case DECL_IMPORT:
4020     // Note: last entry of the ImportDecl record is the number of stored source
4021     // locations.
4022     D = ImportDecl::CreateDeserialized(Context, ID, Record.back());
4023     break;
4024   case DECL_OMP_THREADPRIVATE: {
4025     Record.skipInts(1);
4026     unsigned NumChildren = Record.readInt();
4027     Record.skipInts(1);
4028     D = OMPThreadPrivateDecl::CreateDeserialized(Context, ID, NumChildren);
4029     break;
4030   }
4031   case DECL_OMP_ALLOCATE: {
4032     unsigned NumClauses = Record.readInt();
4033     unsigned NumVars = Record.readInt();
4034     Record.skipInts(1);
4035     D = OMPAllocateDecl::CreateDeserialized(Context, ID, NumVars, NumClauses);
4036     break;
4037   }
4038   case DECL_OMP_REQUIRES: {
4039     unsigned NumClauses = Record.readInt();
4040     Record.skipInts(2);
4041     D = OMPRequiresDecl::CreateDeserialized(Context, ID, NumClauses);
4042     break;
4043   }
4044   case DECL_OMP_DECLARE_REDUCTION:
4045     D = OMPDeclareReductionDecl::CreateDeserialized(Context, ID);
4046     break;
4047   case DECL_OMP_DECLARE_MAPPER: {
4048     unsigned NumClauses = Record.readInt();
4049     Record.skipInts(2);
4050     D = OMPDeclareMapperDecl::CreateDeserialized(Context, ID, NumClauses);
4051     break;
4052   }
4053   case DECL_OMP_CAPTUREDEXPR:
4054     D = OMPCapturedExprDecl::CreateDeserialized(Context, ID);
4055     break;
4056   case DECL_PRAGMA_COMMENT:
4057     D = PragmaCommentDecl::CreateDeserialized(Context, ID, Record.readInt());
4058     break;
4059   case DECL_PRAGMA_DETECT_MISMATCH:
4060     D = PragmaDetectMismatchDecl::CreateDeserialized(Context, ID,
4061                                                      Record.readInt());
4062     break;
4063   case DECL_EMPTY:
4064     D = EmptyDecl::CreateDeserialized(Context, ID);
4065     break;
4066   case DECL_LIFETIME_EXTENDED_TEMPORARY:
4067     D = LifetimeExtendedTemporaryDecl::CreateDeserialized(Context, ID);
4068     break;
4069   case DECL_OBJC_TYPE_PARAM:
4070     D = ObjCTypeParamDecl::CreateDeserialized(Context, ID);
4071     break;
4072   }
4073 
4074   assert(D && "Unknown declaration reading AST file");
4075   LoadedDecl(Index, D);
4076   // Set the DeclContext before doing any deserialization, to make sure internal
4077   // calls to Decl::getASTContext() by Decl's methods will find the
4078   // TranslationUnitDecl without crashing.
4079   D->setDeclContext(Context.getTranslationUnitDecl());
4080   Reader.Visit(D);
4081 
4082   // If this declaration is also a declaration context, get the
4083   // offsets for its tables of lexical and visible declarations.
4084   if (auto *DC = dyn_cast<DeclContext>(D)) {
4085     std::pair<uint64_t, uint64_t> Offsets = Reader.VisitDeclContext(DC);
4086     if (Offsets.first &&
4087         ReadLexicalDeclContextStorage(*Loc.F, DeclsCursor, Offsets.first, DC))
4088       return nullptr;
4089     if (Offsets.second &&
4090         ReadVisibleDeclContextStorage(*Loc.F, DeclsCursor, Offsets.second, ID))
4091       return nullptr;
4092   }
4093   assert(Record.getIdx() == Record.size());
4094 
4095   // Load any relevant update records.
4096   PendingUpdateRecords.push_back(
4097       PendingUpdateRecord(ID, D, /*JustLoaded=*/true));
4098 
4099   // Load the categories after recursive loading is finished.
4100   if (auto *Class = dyn_cast<ObjCInterfaceDecl>(D))
4101     // If we already have a definition when deserializing the ObjCInterfaceDecl,
4102     // we put the Decl in PendingDefinitions so we can pull the categories here.
4103     if (Class->isThisDeclarationADefinition() ||
4104         PendingDefinitions.count(Class))
4105       loadObjCCategories(ID, Class);
4106 
4107   // If we have deserialized a declaration that has a definition the
4108   // AST consumer might need to know about, queue it.
4109   // We don't pass it to the consumer immediately because we may be in recursive
4110   // loading, and some declarations may still be initializing.
4111   PotentiallyInterestingDecls.push_back(
4112       InterestingDecl(D, Reader.hasPendingBody()));
4113 
4114   return D;
4115 }
4116 
4117 void ASTReader::PassInterestingDeclsToConsumer() {
4118   assert(Consumer);
4119 
4120   if (PassingDeclsToConsumer)
4121     return;
4122 
4123   // Guard variable to avoid recursively redoing the process of passing
4124   // decls to consumer.
4125   SaveAndRestore<bool> GuardPassingDeclsToConsumer(PassingDeclsToConsumer,
4126                                                    true);
4127 
4128   // Ensure that we've loaded all potentially-interesting declarations
4129   // that need to be eagerly loaded.
4130   for (auto ID : EagerlyDeserializedDecls)
4131     GetDecl(ID);
4132   EagerlyDeserializedDecls.clear();
4133 
4134   while (!PotentiallyInterestingDecls.empty()) {
4135     InterestingDecl D = PotentiallyInterestingDecls.front();
4136     PotentiallyInterestingDecls.pop_front();
4137     if (isConsumerInterestedIn(getContext(), D.getDecl(), D.hasPendingBody()))
4138       PassInterestingDeclToConsumer(D.getDecl());
4139   }
4140 }
4141 
4142 void ASTReader::loadDeclUpdateRecords(PendingUpdateRecord &Record) {
4143   // The declaration may have been modified by files later in the chain.
4144   // If this is the case, read the record containing the updates from each file
4145   // and pass it to ASTDeclReader to make the modifications.
4146   serialization::GlobalDeclID ID = Record.ID;
4147   Decl *D = Record.D;
4148   ProcessingUpdatesRAIIObj ProcessingUpdates(*this);
4149   DeclUpdateOffsetsMap::iterator UpdI = DeclUpdateOffsets.find(ID);
4150 
4151   SmallVector<serialization::DeclID, 8> PendingLazySpecializationIDs;
4152 
4153   if (UpdI != DeclUpdateOffsets.end()) {
4154     auto UpdateOffsets = std::move(UpdI->second);
4155     DeclUpdateOffsets.erase(UpdI);
4156 
4157     // Check if this decl was interesting to the consumer. If we just loaded
4158     // the declaration, then we know it was interesting and we skip the call
4159     // to isConsumerInterestedIn because it is unsafe to call in the
4160     // current ASTReader state.
4161     bool WasInteresting =
4162         Record.JustLoaded || isConsumerInterestedIn(getContext(), D, false);
4163     for (auto &FileAndOffset : UpdateOffsets) {
4164       ModuleFile *F = FileAndOffset.first;
4165       uint64_t Offset = FileAndOffset.second;
4166       llvm::BitstreamCursor &Cursor = F->DeclsCursor;
4167       SavedStreamPosition SavedPosition(Cursor);
4168       if (llvm::Error JumpFailed = Cursor.JumpToBit(Offset))
4169         // FIXME don't do a fatal error.
4170         llvm::report_fatal_error(
4171             "ASTReader::loadDeclUpdateRecords failed jumping: " +
4172             toString(std::move(JumpFailed)));
4173       Expected<unsigned> MaybeCode = Cursor.ReadCode();
4174       if (!MaybeCode)
4175         llvm::report_fatal_error(
4176             "ASTReader::loadDeclUpdateRecords failed reading code: " +
4177             toString(MaybeCode.takeError()));
4178       unsigned Code = MaybeCode.get();
4179       ASTRecordReader Record(*this, *F);
4180       if (Expected<unsigned> MaybeRecCode = Record.readRecord(Cursor, Code))
4181         assert(MaybeRecCode.get() == DECL_UPDATES &&
4182                "Expected DECL_UPDATES record!");
4183       else
4184         llvm::report_fatal_error(
4185             "ASTReader::loadDeclUpdateRecords failed reading rec code: " +
4186             toString(MaybeCode.takeError()));
4187 
4188       ASTDeclReader Reader(*this, Record, RecordLocation(F, Offset), ID,
4189                            SourceLocation());
4190       Reader.UpdateDecl(D, PendingLazySpecializationIDs);
4191 
4192       // We might have made this declaration interesting. If so, remember that
4193       // we need to hand it off to the consumer.
4194       if (!WasInteresting &&
4195           isConsumerInterestedIn(getContext(), D, Reader.hasPendingBody())) {
4196         PotentiallyInterestingDecls.push_back(
4197             InterestingDecl(D, Reader.hasPendingBody()));
4198         WasInteresting = true;
4199       }
4200     }
4201   }
4202   // Add the lazy specializations to the template.
4203   assert((PendingLazySpecializationIDs.empty() || isa<ClassTemplateDecl>(D) ||
4204           isa<FunctionTemplateDecl>(D) || isa<VarTemplateDecl>(D)) &&
4205          "Must not have pending specializations");
4206   if (auto *CTD = dyn_cast<ClassTemplateDecl>(D))
4207     ASTDeclReader::AddLazySpecializations(CTD, PendingLazySpecializationIDs);
4208   else if (auto *FTD = dyn_cast<FunctionTemplateDecl>(D))
4209     ASTDeclReader::AddLazySpecializations(FTD, PendingLazySpecializationIDs);
4210   else if (auto *VTD = dyn_cast<VarTemplateDecl>(D))
4211     ASTDeclReader::AddLazySpecializations(VTD, PendingLazySpecializationIDs);
4212   PendingLazySpecializationIDs.clear();
4213 
4214   // Load the pending visible updates for this decl context, if it has any.
4215   auto I = PendingVisibleUpdates.find(ID);
4216   if (I != PendingVisibleUpdates.end()) {
4217     auto VisibleUpdates = std::move(I->second);
4218     PendingVisibleUpdates.erase(I);
4219 
4220     auto *DC = cast<DeclContext>(D)->getPrimaryContext();
4221     for (const auto &Update : VisibleUpdates)
4222       Lookups[DC].Table.add(
4223           Update.Mod, Update.Data,
4224           reader::ASTDeclContextNameLookupTrait(*this, *Update.Mod));
4225     DC->setHasExternalVisibleStorage(true);
4226   }
4227 }
4228 
4229 void ASTReader::loadPendingDeclChain(Decl *FirstLocal, uint64_t LocalOffset) {
4230   // Attach FirstLocal to the end of the decl chain.
4231   Decl *CanonDecl = FirstLocal->getCanonicalDecl();
4232   if (FirstLocal != CanonDecl) {
4233     Decl *PrevMostRecent = ASTDeclReader::getMostRecentDecl(CanonDecl);
4234     ASTDeclReader::attachPreviousDecl(
4235         *this, FirstLocal, PrevMostRecent ? PrevMostRecent : CanonDecl,
4236         CanonDecl);
4237   }
4238 
4239   if (!LocalOffset) {
4240     ASTDeclReader::attachLatestDecl(CanonDecl, FirstLocal);
4241     return;
4242   }
4243 
4244   // Load the list of other redeclarations from this module file.
4245   ModuleFile *M = getOwningModuleFile(FirstLocal);
4246   assert(M && "imported decl from no module file");
4247 
4248   llvm::BitstreamCursor &Cursor = M->DeclsCursor;
4249   SavedStreamPosition SavedPosition(Cursor);
4250   if (llvm::Error JumpFailed = Cursor.JumpToBit(LocalOffset))
4251     llvm::report_fatal_error(
4252         "ASTReader::loadPendingDeclChain failed jumping: " +
4253         toString(std::move(JumpFailed)));
4254 
4255   RecordData Record;
4256   Expected<unsigned> MaybeCode = Cursor.ReadCode();
4257   if (!MaybeCode)
4258     llvm::report_fatal_error(
4259         "ASTReader::loadPendingDeclChain failed reading code: " +
4260         toString(MaybeCode.takeError()));
4261   unsigned Code = MaybeCode.get();
4262   if (Expected<unsigned> MaybeRecCode = Cursor.readRecord(Code, Record))
4263     assert(MaybeRecCode.get() == LOCAL_REDECLARATIONS &&
4264            "expected LOCAL_REDECLARATIONS record!");
4265   else
4266     llvm::report_fatal_error(
4267         "ASTReader::loadPendingDeclChain failed reading rec code: " +
4268         toString(MaybeCode.takeError()));
4269 
4270   // FIXME: We have several different dispatches on decl kind here; maybe
4271   // we should instead generate one loop per kind and dispatch up-front?
4272   Decl *MostRecent = FirstLocal;
4273   for (unsigned I = 0, N = Record.size(); I != N; ++I) {
4274     auto *D = GetLocalDecl(*M, Record[N - I - 1]);
4275     ASTDeclReader::attachPreviousDecl(*this, D, MostRecent, CanonDecl);
4276     MostRecent = D;
4277   }
4278   ASTDeclReader::attachLatestDecl(CanonDecl, MostRecent);
4279 }
4280 
4281 namespace {
4282 
4283   /// Given an ObjC interface, goes through the modules and links to the
4284   /// interface all the categories for it.
4285   class ObjCCategoriesVisitor {
4286     ASTReader &Reader;
4287     ObjCInterfaceDecl *Interface;
4288     llvm::SmallPtrSetImpl<ObjCCategoryDecl *> &Deserialized;
4289     ObjCCategoryDecl *Tail = nullptr;
4290     llvm::DenseMap<DeclarationName, ObjCCategoryDecl *> NameCategoryMap;
4291     serialization::GlobalDeclID InterfaceID;
4292     unsigned PreviousGeneration;
4293 
4294     void add(ObjCCategoryDecl *Cat) {
4295       // Only process each category once.
4296       if (!Deserialized.erase(Cat))
4297         return;
4298 
4299       // Check for duplicate categories.
4300       if (Cat->getDeclName()) {
4301         ObjCCategoryDecl *&Existing = NameCategoryMap[Cat->getDeclName()];
4302         if (Existing &&
4303             Reader.getOwningModuleFile(Existing)
4304                                           != Reader.getOwningModuleFile(Cat)) {
4305           // FIXME: We should not warn for duplicates in diamond:
4306           //
4307           //   MT     //
4308           //  /  \    //
4309           // ML  MR   //
4310           //  \  /    //
4311           //   MB     //
4312           //
4313           // If there are duplicates in ML/MR, there will be warning when
4314           // creating MB *and* when importing MB. We should not warn when
4315           // importing.
4316           Reader.Diag(Cat->getLocation(), diag::warn_dup_category_def)
4317             << Interface->getDeclName() << Cat->getDeclName();
4318           Reader.Diag(Existing->getLocation(), diag::note_previous_definition);
4319         } else if (!Existing) {
4320           // Record this category.
4321           Existing = Cat;
4322         }
4323       }
4324 
4325       // Add this category to the end of the chain.
4326       if (Tail)
4327         ASTDeclReader::setNextObjCCategory(Tail, Cat);
4328       else
4329         Interface->setCategoryListRaw(Cat);
4330       Tail = Cat;
4331     }
4332 
4333   public:
4334     ObjCCategoriesVisitor(ASTReader &Reader,
4335                           ObjCInterfaceDecl *Interface,
4336                           llvm::SmallPtrSetImpl<ObjCCategoryDecl *> &Deserialized,
4337                           serialization::GlobalDeclID InterfaceID,
4338                           unsigned PreviousGeneration)
4339         : Reader(Reader), Interface(Interface), Deserialized(Deserialized),
4340           InterfaceID(InterfaceID), PreviousGeneration(PreviousGeneration) {
4341       // Populate the name -> category map with the set of known categories.
4342       for (auto *Cat : Interface->known_categories()) {
4343         if (Cat->getDeclName())
4344           NameCategoryMap[Cat->getDeclName()] = Cat;
4345 
4346         // Keep track of the tail of the category list.
4347         Tail = Cat;
4348       }
4349     }
4350 
4351     bool operator()(ModuleFile &M) {
4352       // If we've loaded all of the category information we care about from
4353       // this module file, we're done.
4354       if (M.Generation <= PreviousGeneration)
4355         return true;
4356 
4357       // Map global ID of the definition down to the local ID used in this
4358       // module file. If there is no such mapping, we'll find nothing here
4359       // (or in any module it imports).
4360       DeclID LocalID = Reader.mapGlobalIDToModuleFileGlobalID(M, InterfaceID);
4361       if (!LocalID)
4362         return true;
4363 
4364       // Perform a binary search to find the local redeclarations for this
4365       // declaration (if any).
4366       const ObjCCategoriesInfo Compare = { LocalID, 0 };
4367       const ObjCCategoriesInfo *Result
4368         = std::lower_bound(M.ObjCCategoriesMap,
4369                            M.ObjCCategoriesMap + M.LocalNumObjCCategoriesInMap,
4370                            Compare);
4371       if (Result == M.ObjCCategoriesMap + M.LocalNumObjCCategoriesInMap ||
4372           Result->DefinitionID != LocalID) {
4373         // We didn't find anything. If the class definition is in this module
4374         // file, then the module files it depends on cannot have any categories,
4375         // so suppress further lookup.
4376         return Reader.isDeclIDFromModule(InterfaceID, M);
4377       }
4378 
4379       // We found something. Dig out all of the categories.
4380       unsigned Offset = Result->Offset;
4381       unsigned N = M.ObjCCategories[Offset];
4382       M.ObjCCategories[Offset++] = 0; // Don't try to deserialize again
4383       for (unsigned I = 0; I != N; ++I)
4384         add(cast_or_null<ObjCCategoryDecl>(
4385               Reader.GetLocalDecl(M, M.ObjCCategories[Offset++])));
4386       return true;
4387     }
4388   };
4389 
4390 } // namespace
4391 
4392 void ASTReader::loadObjCCategories(serialization::GlobalDeclID ID,
4393                                    ObjCInterfaceDecl *D,
4394                                    unsigned PreviousGeneration) {
4395   ObjCCategoriesVisitor Visitor(*this, D, CategoriesDeserialized, ID,
4396                                 PreviousGeneration);
4397   ModuleMgr.visit(Visitor);
4398 }
4399 
4400 template<typename DeclT, typename Fn>
4401 static void forAllLaterRedecls(DeclT *D, Fn F) {
4402   F(D);
4403 
4404   // Check whether we've already merged D into its redeclaration chain.
4405   // MostRecent may or may not be nullptr if D has not been merged. If
4406   // not, walk the merged redecl chain and see if it's there.
4407   auto *MostRecent = D->getMostRecentDecl();
4408   bool Found = false;
4409   for (auto *Redecl = MostRecent; Redecl && !Found;
4410        Redecl = Redecl->getPreviousDecl())
4411     Found = (Redecl == D);
4412 
4413   // If this declaration is merged, apply the functor to all later decls.
4414   if (Found) {
4415     for (auto *Redecl = MostRecent; Redecl != D;
4416          Redecl = Redecl->getPreviousDecl())
4417       F(Redecl);
4418   }
4419 }
4420 
4421 void ASTDeclReader::UpdateDecl(Decl *D,
4422    llvm::SmallVectorImpl<serialization::DeclID> &PendingLazySpecializationIDs) {
4423   while (Record.getIdx() < Record.size()) {
4424     switch ((DeclUpdateKind)Record.readInt()) {
4425     case UPD_CXX_ADDED_IMPLICIT_MEMBER: {
4426       auto *RD = cast<CXXRecordDecl>(D);
4427       // FIXME: If we also have an update record for instantiating the
4428       // definition of D, we need that to happen before we get here.
4429       Decl *MD = Record.readDecl();
4430       assert(MD && "couldn't read decl from update record");
4431       // FIXME: We should call addHiddenDecl instead, to add the member
4432       // to its DeclContext.
4433       RD->addedMember(MD);
4434       break;
4435     }
4436 
4437     case UPD_CXX_ADDED_TEMPLATE_SPECIALIZATION:
4438       // It will be added to the template's lazy specialization set.
4439       PendingLazySpecializationIDs.push_back(readDeclID());
4440       break;
4441 
4442     case UPD_CXX_ADDED_ANONYMOUS_NAMESPACE: {
4443       auto *Anon = readDeclAs<NamespaceDecl>();
4444 
4445       // Each module has its own anonymous namespace, which is disjoint from
4446       // any other module's anonymous namespaces, so don't attach the anonymous
4447       // namespace at all.
4448       if (!Record.isModule()) {
4449         if (auto *TU = dyn_cast<TranslationUnitDecl>(D))
4450           TU->setAnonymousNamespace(Anon);
4451         else
4452           cast<NamespaceDecl>(D)->setAnonymousNamespace(Anon);
4453       }
4454       break;
4455     }
4456 
4457     case UPD_CXX_ADDED_VAR_DEFINITION: {
4458       auto *VD = cast<VarDecl>(D);
4459       VD->NonParmVarDeclBits.IsInline = Record.readInt();
4460       VD->NonParmVarDeclBits.IsInlineSpecified = Record.readInt();
4461       uint64_t Val = Record.readInt();
4462       if (Val && !VD->getInit()) {
4463         VD->setInit(Record.readExpr());
4464         if (Val != 1) {
4465           EvaluatedStmt *Eval = VD->ensureEvaluatedStmt();
4466           Eval->HasConstantInitialization = (Val & 2) != 0;
4467           Eval->HasConstantDestruction = (Val & 4) != 0;
4468         }
4469       }
4470       break;
4471     }
4472 
4473     case UPD_CXX_POINT_OF_INSTANTIATION: {
4474       SourceLocation POI = Record.readSourceLocation();
4475       if (auto *VTSD = dyn_cast<VarTemplateSpecializationDecl>(D)) {
4476         VTSD->setPointOfInstantiation(POI);
4477       } else if (auto *VD = dyn_cast<VarDecl>(D)) {
4478         VD->getMemberSpecializationInfo()->setPointOfInstantiation(POI);
4479       } else {
4480         auto *FD = cast<FunctionDecl>(D);
4481         if (auto *FTSInfo = FD->TemplateOrSpecialization
4482                     .dyn_cast<FunctionTemplateSpecializationInfo *>())
4483           FTSInfo->setPointOfInstantiation(POI);
4484         else
4485           FD->TemplateOrSpecialization.get<MemberSpecializationInfo *>()
4486               ->setPointOfInstantiation(POI);
4487       }
4488       break;
4489     }
4490 
4491     case UPD_CXX_INSTANTIATED_DEFAULT_ARGUMENT: {
4492       auto *Param = cast<ParmVarDecl>(D);
4493 
4494       // We have to read the default argument regardless of whether we use it
4495       // so that hypothetical further update records aren't messed up.
4496       // TODO: Add a function to skip over the next expr record.
4497       auto *DefaultArg = Record.readExpr();
4498 
4499       // Only apply the update if the parameter still has an uninstantiated
4500       // default argument.
4501       if (Param->hasUninstantiatedDefaultArg())
4502         Param->setDefaultArg(DefaultArg);
4503       break;
4504     }
4505 
4506     case UPD_CXX_INSTANTIATED_DEFAULT_MEMBER_INITIALIZER: {
4507       auto *FD = cast<FieldDecl>(D);
4508       auto *DefaultInit = Record.readExpr();
4509 
4510       // Only apply the update if the field still has an uninstantiated
4511       // default member initializer.
4512       if (FD->hasInClassInitializer() && !FD->getInClassInitializer()) {
4513         if (DefaultInit)
4514           FD->setInClassInitializer(DefaultInit);
4515         else
4516           // Instantiation failed. We can get here if we serialized an AST for
4517           // an invalid program.
4518           FD->removeInClassInitializer();
4519       }
4520       break;
4521     }
4522 
4523     case UPD_CXX_ADDED_FUNCTION_DEFINITION: {
4524       auto *FD = cast<FunctionDecl>(D);
4525       if (Reader.PendingBodies[FD]) {
4526         // FIXME: Maybe check for ODR violations.
4527         // It's safe to stop now because this update record is always last.
4528         return;
4529       }
4530 
4531       if (Record.readInt()) {
4532         // Maintain AST consistency: any later redeclarations of this function
4533         // are inline if this one is. (We might have merged another declaration
4534         // into this one.)
4535         forAllLaterRedecls(FD, [](FunctionDecl *FD) {
4536           FD->setImplicitlyInline();
4537         });
4538       }
4539       FD->setInnerLocStart(readSourceLocation());
4540       ReadFunctionDefinition(FD);
4541       assert(Record.getIdx() == Record.size() && "lazy body must be last");
4542       break;
4543     }
4544 
4545     case UPD_CXX_INSTANTIATED_CLASS_DEFINITION: {
4546       auto *RD = cast<CXXRecordDecl>(D);
4547       auto *OldDD = RD->getCanonicalDecl()->DefinitionData;
4548       bool HadRealDefinition =
4549           OldDD && (OldDD->Definition != RD ||
4550                     !Reader.PendingFakeDefinitionData.count(OldDD));
4551       RD->setParamDestroyedInCallee(Record.readInt());
4552       RD->setArgPassingRestrictions(
4553           (RecordDecl::ArgPassingKind)Record.readInt());
4554       ReadCXXRecordDefinition(RD, /*Update*/true);
4555 
4556       // Visible update is handled separately.
4557       uint64_t LexicalOffset = ReadLocalOffset();
4558       if (!HadRealDefinition && LexicalOffset) {
4559         Record.readLexicalDeclContextStorage(LexicalOffset, RD);
4560         Reader.PendingFakeDefinitionData.erase(OldDD);
4561       }
4562 
4563       auto TSK = (TemplateSpecializationKind)Record.readInt();
4564       SourceLocation POI = readSourceLocation();
4565       if (MemberSpecializationInfo *MSInfo =
4566               RD->getMemberSpecializationInfo()) {
4567         MSInfo->setTemplateSpecializationKind(TSK);
4568         MSInfo->setPointOfInstantiation(POI);
4569       } else {
4570         auto *Spec = cast<ClassTemplateSpecializationDecl>(RD);
4571         Spec->setTemplateSpecializationKind(TSK);
4572         Spec->setPointOfInstantiation(POI);
4573 
4574         if (Record.readInt()) {
4575           auto *PartialSpec =
4576               readDeclAs<ClassTemplatePartialSpecializationDecl>();
4577           SmallVector<TemplateArgument, 8> TemplArgs;
4578           Record.readTemplateArgumentList(TemplArgs);
4579           auto *TemplArgList = TemplateArgumentList::CreateCopy(
4580               Reader.getContext(), TemplArgs);
4581 
4582           // FIXME: If we already have a partial specialization set,
4583           // check that it matches.
4584           if (!Spec->getSpecializedTemplateOrPartial()
4585                    .is<ClassTemplatePartialSpecializationDecl *>())
4586             Spec->setInstantiationOf(PartialSpec, TemplArgList);
4587         }
4588       }
4589 
4590       RD->setTagKind((TagTypeKind)Record.readInt());
4591       RD->setLocation(readSourceLocation());
4592       RD->setLocStart(readSourceLocation());
4593       RD->setBraceRange(readSourceRange());
4594 
4595       if (Record.readInt()) {
4596         AttrVec Attrs;
4597         Record.readAttributes(Attrs);
4598         // If the declaration already has attributes, we assume that some other
4599         // AST file already loaded them.
4600         if (!D->hasAttrs())
4601           D->setAttrsImpl(Attrs, Reader.getContext());
4602       }
4603       break;
4604     }
4605 
4606     case UPD_CXX_RESOLVED_DTOR_DELETE: {
4607       // Set the 'operator delete' directly to avoid emitting another update
4608       // record.
4609       auto *Del = readDeclAs<FunctionDecl>();
4610       auto *First = cast<CXXDestructorDecl>(D->getCanonicalDecl());
4611       auto *ThisArg = Record.readExpr();
4612       // FIXME: Check consistency if we have an old and new operator delete.
4613       if (!First->OperatorDelete) {
4614         First->OperatorDelete = Del;
4615         First->OperatorDeleteThisArg = ThisArg;
4616       }
4617       break;
4618     }
4619 
4620     case UPD_CXX_RESOLVED_EXCEPTION_SPEC: {
4621       SmallVector<QualType, 8> ExceptionStorage;
4622       auto ESI = Record.readExceptionSpecInfo(ExceptionStorage);
4623 
4624       // Update this declaration's exception specification, if needed.
4625       auto *FD = cast<FunctionDecl>(D);
4626       auto *FPT = FD->getType()->castAs<FunctionProtoType>();
4627       // FIXME: If the exception specification is already present, check that it
4628       // matches.
4629       if (isUnresolvedExceptionSpec(FPT->getExceptionSpecType())) {
4630         FD->setType(Reader.getContext().getFunctionType(
4631             FPT->getReturnType(), FPT->getParamTypes(),
4632             FPT->getExtProtoInfo().withExceptionSpec(ESI)));
4633 
4634         // When we get to the end of deserializing, see if there are other decls
4635         // that we need to propagate this exception specification onto.
4636         Reader.PendingExceptionSpecUpdates.insert(
4637             std::make_pair(FD->getCanonicalDecl(), FD));
4638       }
4639       break;
4640     }
4641 
4642     case UPD_CXX_DEDUCED_RETURN_TYPE: {
4643       auto *FD = cast<FunctionDecl>(D);
4644       QualType DeducedResultType = Record.readType();
4645       Reader.PendingDeducedTypeUpdates.insert(
4646           {FD->getCanonicalDecl(), DeducedResultType});
4647       break;
4648     }
4649 
4650     case UPD_DECL_MARKED_USED:
4651       // Maintain AST consistency: any later redeclarations are used too.
4652       D->markUsed(Reader.getContext());
4653       break;
4654 
4655     case UPD_MANGLING_NUMBER:
4656       Reader.getContext().setManglingNumber(cast<NamedDecl>(D),
4657                                             Record.readInt());
4658       break;
4659 
4660     case UPD_STATIC_LOCAL_NUMBER:
4661       Reader.getContext().setStaticLocalNumber(cast<VarDecl>(D),
4662                                                Record.readInt());
4663       break;
4664 
4665     case UPD_DECL_MARKED_OPENMP_THREADPRIVATE:
4666       D->addAttr(OMPThreadPrivateDeclAttr::CreateImplicit(
4667           Reader.getContext(), readSourceRange(),
4668           AttributeCommonInfo::AS_Pragma));
4669       break;
4670 
4671     case UPD_DECL_MARKED_OPENMP_ALLOCATE: {
4672       auto AllocatorKind =
4673           static_cast<OMPAllocateDeclAttr::AllocatorTypeTy>(Record.readInt());
4674       Expr *Allocator = Record.readExpr();
4675       SourceRange SR = readSourceRange();
4676       D->addAttr(OMPAllocateDeclAttr::CreateImplicit(
4677           Reader.getContext(), AllocatorKind, Allocator, SR,
4678           AttributeCommonInfo::AS_Pragma));
4679       break;
4680     }
4681 
4682     case UPD_DECL_EXPORTED: {
4683       unsigned SubmoduleID = readSubmoduleID();
4684       auto *Exported = cast<NamedDecl>(D);
4685       Module *Owner = SubmoduleID ? Reader.getSubmodule(SubmoduleID) : nullptr;
4686       Reader.getContext().mergeDefinitionIntoModule(Exported, Owner);
4687       Reader.PendingMergedDefinitionsToDeduplicate.insert(Exported);
4688       break;
4689     }
4690 
4691     case UPD_DECL_MARKED_OPENMP_DECLARETARGET: {
4692       auto MapType = Record.readEnum<OMPDeclareTargetDeclAttr::MapTypeTy>();
4693       auto DevType = Record.readEnum<OMPDeclareTargetDeclAttr::DevTypeTy>();
4694       unsigned Level = Record.readInt();
4695       D->addAttr(OMPDeclareTargetDeclAttr::CreateImplicit(
4696           Reader.getContext(), MapType, DevType, Level, readSourceRange(),
4697           AttributeCommonInfo::AS_Pragma));
4698       break;
4699     }
4700 
4701     case UPD_ADDED_ATTR_TO_RECORD:
4702       AttrVec Attrs;
4703       Record.readAttributes(Attrs);
4704       assert(Attrs.size() == 1);
4705       D->addAttr(Attrs[0]);
4706       break;
4707     }
4708   }
4709 }
4710