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/ASTReader.h"
52 #include "clang/Serialization/ContinuousRangeMap.h"
53 #include "clang/Serialization/Module.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/Bitcode/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 *GetTypeSourceInfo() {
123       return Record.getTypeSourceInfo();
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     void ReadQualifierInfo(QualifierInfo &Info) {
149       Record.readQualifierInfo(Info);
150     }
151 
152     void ReadDeclarationNameLoc(DeclarationNameLoc &DNLoc, DeclarationName Name) {
153       Record.readDeclarationNameLoc(DNLoc, Name);
154     }
155 
156     serialization::SubmoduleID readSubmoduleID() {
157       if (Record.getIdx() == Record.size())
158         return 0;
159 
160       return Record.getGlobalSubmoduleID(Record.readInt());
161     }
162 
163     Module *readModule() {
164       return Record.getSubmodule(readSubmoduleID());
165     }
166 
167     void ReadCXXRecordDefinition(CXXRecordDecl *D, bool Update);
168     void ReadCXXDefinitionData(struct CXXRecordDecl::DefinitionData &Data,
169                                const CXXRecordDecl *D);
170     void MergeDefinitionData(CXXRecordDecl *D,
171                              struct CXXRecordDecl::DefinitionData &&NewDD);
172     void ReadObjCDefinitionData(struct ObjCInterfaceDecl::DefinitionData &Data);
173     void MergeDefinitionData(ObjCInterfaceDecl *D,
174                              struct ObjCInterfaceDecl::DefinitionData &&NewDD);
175     void ReadObjCDefinitionData(struct ObjCProtocolDecl::DefinitionData &Data);
176     void MergeDefinitionData(ObjCProtocolDecl *D,
177                              struct ObjCProtocolDecl::DefinitionData &&NewDD);
178 
179     static DeclContext *getPrimaryDCForAnonymousDecl(DeclContext *LexicalDC);
180 
181     static NamedDecl *getAnonymousDeclForMerging(ASTReader &Reader,
182                                                  DeclContext *DC,
183                                                  unsigned Index);
184     static void setAnonymousDeclForMerging(ASTReader &Reader, DeclContext *DC,
185                                            unsigned Index, NamedDecl *D);
186 
187     /// Results from loading a RedeclarableDecl.
188     class RedeclarableResult {
189       Decl *MergeWith;
190       GlobalDeclID FirstID;
191       bool IsKeyDecl;
192 
193     public:
194       RedeclarableResult(Decl *MergeWith, GlobalDeclID FirstID, bool IsKeyDecl)
195           : MergeWith(MergeWith), FirstID(FirstID), IsKeyDecl(IsKeyDecl) {}
196 
197       /// Retrieve the first ID.
198       GlobalDeclID getFirstID() const { return FirstID; }
199 
200       /// Is this declaration a key declaration?
201       bool isKeyDecl() const { return IsKeyDecl; }
202 
203       /// Get a known declaration that this should be merged with, if
204       /// any.
205       Decl *getKnownMergeTarget() const { return MergeWith; }
206     };
207 
208     /// Class used to capture the result of searching for an existing
209     /// declaration of a specific kind and name, along with the ability
210     /// to update the place where this result was found (the declaration
211     /// chain hanging off an identifier or the DeclContext we searched in)
212     /// if requested.
213     class FindExistingResult {
214       ASTReader &Reader;
215       NamedDecl *New = nullptr;
216       NamedDecl *Existing = nullptr;
217       bool AddResult = false;
218       unsigned AnonymousDeclNumber = 0;
219       IdentifierInfo *TypedefNameForLinkage = nullptr;
220 
221     public:
222       FindExistingResult(ASTReader &Reader) : Reader(Reader) {}
223 
224       FindExistingResult(ASTReader &Reader, NamedDecl *New, NamedDecl *Existing,
225                          unsigned AnonymousDeclNumber,
226                          IdentifierInfo *TypedefNameForLinkage)
227           : Reader(Reader), New(New), Existing(Existing), AddResult(true),
228             AnonymousDeclNumber(AnonymousDeclNumber),
229             TypedefNameForLinkage(TypedefNameForLinkage) {}
230 
231       FindExistingResult(FindExistingResult &&Other)
232           : Reader(Other.Reader), New(Other.New), Existing(Other.Existing),
233             AddResult(Other.AddResult),
234             AnonymousDeclNumber(Other.AnonymousDeclNumber),
235             TypedefNameForLinkage(Other.TypedefNameForLinkage) {
236         Other.AddResult = false;
237       }
238 
239       FindExistingResult &operator=(FindExistingResult &&) = delete;
240       ~FindExistingResult();
241 
242       /// Suppress the addition of this result into the known set of
243       /// names.
244       void suppress() { AddResult = false; }
245 
246       operator NamedDecl*() const { return Existing; }
247 
248       template<typename T>
249       operator T*() const { return dyn_cast_or_null<T>(Existing); }
250     };
251 
252     static DeclContext *getPrimaryContextForMerging(ASTReader &Reader,
253                                                     DeclContext *DC);
254     FindExistingResult findExisting(NamedDecl *D);
255 
256   public:
257     ASTDeclReader(ASTReader &Reader, ASTRecordReader &Record,
258                   ASTReader::RecordLocation Loc,
259                   DeclID thisDeclID, SourceLocation ThisDeclLoc)
260         : Reader(Reader), Record(Record), Loc(Loc), ThisDeclID(thisDeclID),
261           ThisDeclLoc(ThisDeclLoc) {}
262 
263     template <typename T> static
264     void AddLazySpecializations(T *D,
265                                 SmallVectorImpl<serialization::DeclID>& IDs) {
266       if (IDs.empty())
267         return;
268 
269       // FIXME: We should avoid this pattern of getting the ASTContext.
270       ASTContext &C = D->getASTContext();
271 
272       auto *&LazySpecializations = D->getCommonPtr()->LazySpecializations;
273 
274       if (auto &Old = LazySpecializations) {
275         IDs.insert(IDs.end(), Old + 1, Old + 1 + Old[0]);
276         llvm::sort(IDs);
277         IDs.erase(std::unique(IDs.begin(), IDs.end()), IDs.end());
278       }
279 
280       auto *Result = new (C) serialization::DeclID[1 + IDs.size()];
281       *Result = IDs.size();
282       std::copy(IDs.begin(), IDs.end(), Result + 1);
283 
284       LazySpecializations = Result;
285     }
286 
287     template <typename DeclT>
288     static Decl *getMostRecentDeclImpl(Redeclarable<DeclT> *D);
289     static Decl *getMostRecentDeclImpl(...);
290     static Decl *getMostRecentDecl(Decl *D);
291 
292     template <typename DeclT>
293     static void attachPreviousDeclImpl(ASTReader &Reader,
294                                        Redeclarable<DeclT> *D, Decl *Previous,
295                                        Decl *Canon);
296     static void attachPreviousDeclImpl(ASTReader &Reader, ...);
297     static void attachPreviousDecl(ASTReader &Reader, Decl *D, Decl *Previous,
298                                    Decl *Canon);
299 
300     template <typename DeclT>
301     static void attachLatestDeclImpl(Redeclarable<DeclT> *D, Decl *Latest);
302     static void attachLatestDeclImpl(...);
303     static void attachLatestDecl(Decl *D, Decl *latest);
304 
305     template <typename DeclT>
306     static void markIncompleteDeclChainImpl(Redeclarable<DeclT> *D);
307     static void markIncompleteDeclChainImpl(...);
308 
309     /// Determine whether this declaration has a pending body.
310     bool hasPendingBody() const { return HasPendingBody; }
311 
312     void ReadFunctionDefinition(FunctionDecl *FD);
313     void Visit(Decl *D);
314 
315     void UpdateDecl(Decl *D, SmallVectorImpl<serialization::DeclID> &);
316 
317     static void setNextObjCCategory(ObjCCategoryDecl *Cat,
318                                     ObjCCategoryDecl *Next) {
319       Cat->NextClassCategory = Next;
320     }
321 
322     void VisitDecl(Decl *D);
323     void VisitPragmaCommentDecl(PragmaCommentDecl *D);
324     void VisitPragmaDetectMismatchDecl(PragmaDetectMismatchDecl *D);
325     void VisitTranslationUnitDecl(TranslationUnitDecl *TU);
326     void VisitNamedDecl(NamedDecl *ND);
327     void VisitLabelDecl(LabelDecl *LD);
328     void VisitNamespaceDecl(NamespaceDecl *D);
329     void VisitUsingDirectiveDecl(UsingDirectiveDecl *D);
330     void VisitNamespaceAliasDecl(NamespaceAliasDecl *D);
331     void VisitTypeDecl(TypeDecl *TD);
332     RedeclarableResult VisitTypedefNameDecl(TypedefNameDecl *TD);
333     void VisitTypedefDecl(TypedefDecl *TD);
334     void VisitTypeAliasDecl(TypeAliasDecl *TD);
335     void VisitUnresolvedUsingTypenameDecl(UnresolvedUsingTypenameDecl *D);
336     RedeclarableResult VisitTagDecl(TagDecl *TD);
337     void VisitEnumDecl(EnumDecl *ED);
338     RedeclarableResult VisitRecordDeclImpl(RecordDecl *RD);
339     void VisitRecordDecl(RecordDecl *RD) { VisitRecordDeclImpl(RD); }
340     RedeclarableResult VisitCXXRecordDeclImpl(CXXRecordDecl *D);
341     void VisitCXXRecordDecl(CXXRecordDecl *D) { VisitCXXRecordDeclImpl(D); }
342     RedeclarableResult VisitClassTemplateSpecializationDeclImpl(
343                                             ClassTemplateSpecializationDecl *D);
344 
345     void VisitClassTemplateSpecializationDecl(
346         ClassTemplateSpecializationDecl *D) {
347       VisitClassTemplateSpecializationDeclImpl(D);
348     }
349 
350     void VisitClassTemplatePartialSpecializationDecl(
351                                      ClassTemplatePartialSpecializationDecl *D);
352     void VisitClassScopeFunctionSpecializationDecl(
353                                        ClassScopeFunctionSpecializationDecl *D);
354     RedeclarableResult
355     VisitVarTemplateSpecializationDeclImpl(VarTemplateSpecializationDecl *D);
356 
357     void VisitVarTemplateSpecializationDecl(VarTemplateSpecializationDecl *D) {
358       VisitVarTemplateSpecializationDeclImpl(D);
359     }
360 
361     void VisitVarTemplatePartialSpecializationDecl(
362         VarTemplatePartialSpecializationDecl *D);
363     void VisitTemplateTypeParmDecl(TemplateTypeParmDecl *D);
364     void VisitValueDecl(ValueDecl *VD);
365     void VisitEnumConstantDecl(EnumConstantDecl *ECD);
366     void VisitUnresolvedUsingValueDecl(UnresolvedUsingValueDecl *D);
367     void VisitDeclaratorDecl(DeclaratorDecl *DD);
368     void VisitFunctionDecl(FunctionDecl *FD);
369     void VisitCXXDeductionGuideDecl(CXXDeductionGuideDecl *GD);
370     void VisitCXXMethodDecl(CXXMethodDecl *D);
371     void VisitCXXConstructorDecl(CXXConstructorDecl *D);
372     void VisitCXXDestructorDecl(CXXDestructorDecl *D);
373     void VisitCXXConversionDecl(CXXConversionDecl *D);
374     void VisitFieldDecl(FieldDecl *FD);
375     void VisitMSPropertyDecl(MSPropertyDecl *FD);
376     void VisitIndirectFieldDecl(IndirectFieldDecl *FD);
377     RedeclarableResult VisitVarDeclImpl(VarDecl *D);
378     void VisitVarDecl(VarDecl *VD) { VisitVarDeclImpl(VD); }
379     void VisitImplicitParamDecl(ImplicitParamDecl *PD);
380     void VisitParmVarDecl(ParmVarDecl *PD);
381     void VisitDecompositionDecl(DecompositionDecl *DD);
382     void VisitBindingDecl(BindingDecl *BD);
383     void VisitNonTypeTemplateParmDecl(NonTypeTemplateParmDecl *D);
384     DeclID VisitTemplateDecl(TemplateDecl *D);
385     RedeclarableResult VisitRedeclarableTemplateDecl(RedeclarableTemplateDecl *D);
386     void VisitClassTemplateDecl(ClassTemplateDecl *D);
387     void VisitBuiltinTemplateDecl(BuiltinTemplateDecl *D);
388     void VisitVarTemplateDecl(VarTemplateDecl *D);
389     void VisitFunctionTemplateDecl(FunctionTemplateDecl *D);
390     void VisitTemplateTemplateParmDecl(TemplateTemplateParmDecl *D);
391     void VisitTypeAliasTemplateDecl(TypeAliasTemplateDecl *D);
392     void VisitUsingDecl(UsingDecl *D);
393     void VisitUsingPackDecl(UsingPackDecl *D);
394     void VisitUsingShadowDecl(UsingShadowDecl *D);
395     void VisitConstructorUsingShadowDecl(ConstructorUsingShadowDecl *D);
396     void VisitLinkageSpecDecl(LinkageSpecDecl *D);
397     void VisitExportDecl(ExportDecl *D);
398     void VisitFileScopeAsmDecl(FileScopeAsmDecl *AD);
399     void VisitImportDecl(ImportDecl *D);
400     void VisitAccessSpecDecl(AccessSpecDecl *D);
401     void VisitFriendDecl(FriendDecl *D);
402     void VisitFriendTemplateDecl(FriendTemplateDecl *D);
403     void VisitStaticAssertDecl(StaticAssertDecl *D);
404     void VisitBlockDecl(BlockDecl *BD);
405     void VisitCapturedDecl(CapturedDecl *CD);
406     void VisitEmptyDecl(EmptyDecl *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 mergeTemplatePattern(RedeclarableTemplateDecl *D,
426                               RedeclarableTemplateDecl *Existing,
427                               DeclID DsID, bool IsKeyDecl);
428 
429     ObjCTypeParamList *ReadObjCTypeParamList();
430 
431     // FIXME: Reorder according to DeclNodes.td?
432     void VisitObjCMethodDecl(ObjCMethodDecl *D);
433     void VisitObjCTypeParamDecl(ObjCTypeParamDecl *D);
434     void VisitObjCContainerDecl(ObjCContainerDecl *D);
435     void VisitObjCInterfaceDecl(ObjCInterfaceDecl *D);
436     void VisitObjCIvarDecl(ObjCIvarDecl *D);
437     void VisitObjCProtocolDecl(ObjCProtocolDecl *D);
438     void VisitObjCAtDefsFieldDecl(ObjCAtDefsFieldDecl *D);
439     void VisitObjCCategoryDecl(ObjCCategoryDecl *D);
440     void VisitObjCImplDecl(ObjCImplDecl *D);
441     void VisitObjCCategoryImplDecl(ObjCCategoryImplDecl *D);
442     void VisitObjCImplementationDecl(ObjCImplementationDecl *D);
443     void VisitObjCCompatibleAliasDecl(ObjCCompatibleAliasDecl *D);
444     void VisitObjCPropertyDecl(ObjCPropertyDecl *D);
445     void VisitObjCPropertyImplDecl(ObjCPropertyImplDecl *D);
446     void VisitOMPThreadPrivateDecl(OMPThreadPrivateDecl *D);
447     void VisitOMPAllocateDecl(OMPAllocateDecl *D);
448     void VisitOMPDeclareReductionDecl(OMPDeclareReductionDecl *D);
449     void VisitOMPDeclareMapperDecl(OMPDeclareMapperDecl *D);
450     void VisitOMPRequiresDecl(OMPRequiresDecl *D);
451     void VisitOMPCapturedExprDecl(OMPCapturedExprDecl *D);
452   };
453 
454 } // namespace clang
455 
456 namespace {
457 
458 /// Iterator over the redeclarations of a declaration that have already
459 /// been merged into the same redeclaration chain.
460 template<typename DeclT>
461 class MergedRedeclIterator {
462   DeclT *Start;
463   DeclT *Canonical = nullptr;
464   DeclT *Current = nullptr;
465 
466 public:
467   MergedRedeclIterator() = default;
468   MergedRedeclIterator(DeclT *Start) : Start(Start), Current(Start) {}
469 
470   DeclT *operator*() { return Current; }
471 
472   MergedRedeclIterator &operator++() {
473     if (Current->isFirstDecl()) {
474       Canonical = Current;
475       Current = Current->getMostRecentDecl();
476     } else
477       Current = Current->getPreviousDecl();
478 
479     // If we started in the merged portion, we'll reach our start position
480     // eventually. Otherwise, we'll never reach it, but the second declaration
481     // we reached was the canonical declaration, so stop when we see that one
482     // again.
483     if (Current == Start || Current == Canonical)
484       Current = nullptr;
485     return *this;
486   }
487 
488   friend bool operator!=(const MergedRedeclIterator &A,
489                          const MergedRedeclIterator &B) {
490     return A.Current != B.Current;
491   }
492 };
493 
494 } // namespace
495 
496 template <typename DeclT>
497 static llvm::iterator_range<MergedRedeclIterator<DeclT>>
498 merged_redecls(DeclT *D) {
499   return llvm::make_range(MergedRedeclIterator<DeclT>(D),
500                           MergedRedeclIterator<DeclT>());
501 }
502 
503 uint64_t ASTDeclReader::GetCurrentCursorOffset() {
504   return Loc.F->DeclsCursor.GetCurrentBitNo() + Loc.F->GlobalBitOffset;
505 }
506 
507 void ASTDeclReader::ReadFunctionDefinition(FunctionDecl *FD) {
508   if (Record.readInt())
509     Reader.DefinitionSource[FD] = Loc.F->Kind == ModuleKind::MK_MainFile;
510   if (auto *CD = dyn_cast<CXXConstructorDecl>(FD)) {
511     CD->setNumCtorInitializers(Record.readInt());
512     if (CD->getNumCtorInitializers())
513       CD->CtorInitializers = ReadGlobalOffset();
514   }
515   // Store the offset of the body so we can lazily load it later.
516   Reader.PendingBodies[FD] = GetCurrentCursorOffset();
517   HasPendingBody = true;
518 }
519 
520 void ASTDeclReader::Visit(Decl *D) {
521   DeclVisitor<ASTDeclReader, void>::Visit(D);
522 
523   // At this point we have deserialized and merged the decl and it is safe to
524   // update its canonical decl to signal that the entire entity is used.
525   D->getCanonicalDecl()->Used |= IsDeclMarkedUsed;
526   IsDeclMarkedUsed = false;
527 
528   if (auto *DD = dyn_cast<DeclaratorDecl>(D)) {
529     if (auto *TInfo = DD->getTypeSourceInfo())
530       Record.readTypeLoc(TInfo->getTypeLoc());
531   }
532 
533   if (auto *TD = dyn_cast<TypeDecl>(D)) {
534     // We have a fully initialized TypeDecl. Read its type now.
535     TD->setTypeForDecl(Reader.GetType(DeferredTypeID).getTypePtrOrNull());
536 
537     // If this is a tag declaration with a typedef name for linkage, it's safe
538     // to load that typedef now.
539     if (NamedDeclForTagDecl)
540       cast<TagDecl>(D)->TypedefNameDeclOrQualifier =
541           cast<TypedefNameDecl>(Reader.GetDecl(NamedDeclForTagDecl));
542   } else if (auto *ID = dyn_cast<ObjCInterfaceDecl>(D)) {
543     // if we have a fully initialized TypeDecl, we can safely read its type now.
544     ID->TypeForDecl = Reader.GetType(DeferredTypeID).getTypePtrOrNull();
545   } else if (auto *FD = dyn_cast<FunctionDecl>(D)) {
546     // FunctionDecl's body was written last after all other Stmts/Exprs.
547     // We only read it if FD doesn't already have a body (e.g., from another
548     // module).
549     // FIXME: Can we diagnose ODR violations somehow?
550     if (Record.readInt())
551       ReadFunctionDefinition(FD);
552   }
553 }
554 
555 void ASTDeclReader::VisitDecl(Decl *D) {
556   if (D->isTemplateParameter() || D->isTemplateParameterPack() ||
557       isa<ParmVarDecl>(D)) {
558     // We don't want to deserialize the DeclContext of a template
559     // parameter or of a parameter of a function template immediately.   These
560     // entities might be used in the formulation of its DeclContext (for
561     // example, a function parameter can be used in decltype() in trailing
562     // return type of the function).  Use the translation unit DeclContext as a
563     // placeholder.
564     GlobalDeclID SemaDCIDForTemplateParmDecl = ReadDeclID();
565     GlobalDeclID LexicalDCIDForTemplateParmDecl = ReadDeclID();
566     if (!LexicalDCIDForTemplateParmDecl)
567       LexicalDCIDForTemplateParmDecl = SemaDCIDForTemplateParmDecl;
568     Reader.addPendingDeclContextInfo(D,
569                                      SemaDCIDForTemplateParmDecl,
570                                      LexicalDCIDForTemplateParmDecl);
571     D->setDeclContext(Reader.getContext().getTranslationUnitDecl());
572   } else {
573     auto *SemaDC = ReadDeclAs<DeclContext>();
574     auto *LexicalDC = ReadDeclAs<DeclContext>();
575     if (!LexicalDC)
576       LexicalDC = SemaDC;
577     DeclContext *MergedSemaDC = Reader.MergedDeclContexts.lookup(SemaDC);
578     // Avoid calling setLexicalDeclContext() directly because it uses
579     // Decl::getASTContext() internally which is unsafe during derialization.
580     D->setDeclContextsImpl(MergedSemaDC ? MergedSemaDC : SemaDC, LexicalDC,
581                            Reader.getContext());
582   }
583   D->setLocation(ThisDeclLoc);
584   D->setInvalidDecl(Record.readInt());
585   if (Record.readInt()) { // hasAttrs
586     AttrVec Attrs;
587     Record.readAttributes(Attrs);
588     // Avoid calling setAttrs() directly because it uses Decl::getASTContext()
589     // internally which is unsafe during derialization.
590     D->setAttrsImpl(Attrs, Reader.getContext());
591   }
592   D->setImplicit(Record.readInt());
593   D->Used = Record.readInt();
594   IsDeclMarkedUsed |= D->Used;
595   D->setReferenced(Record.readInt());
596   D->setTopLevelDeclInObjCContainer(Record.readInt());
597   D->setAccess((AccessSpecifier)Record.readInt());
598   D->FromASTFile = true;
599   bool ModulePrivate = Record.readInt();
600 
601   // Determine whether this declaration is part of a (sub)module. If so, it
602   // may not yet be visible.
603   if (unsigned SubmoduleID = readSubmoduleID()) {
604     // Store the owning submodule ID in the declaration.
605     D->setModuleOwnershipKind(
606         ModulePrivate ? Decl::ModuleOwnershipKind::ModulePrivate
607                       : Decl::ModuleOwnershipKind::VisibleWhenImported);
608     D->setOwningModuleID(SubmoduleID);
609 
610     if (ModulePrivate) {
611       // Module-private declarations are never visible, so there is no work to
612       // do.
613     } else if (Reader.getContext().getLangOpts().ModulesLocalVisibility) {
614       // If local visibility is being tracked, this declaration will become
615       // hidden and visible as the owning module does.
616     } else if (Module *Owner = Reader.getSubmodule(SubmoduleID)) {
617       // Mark the declaration as visible when its owning module becomes visible.
618       if (Owner->NameVisibility == Module::AllVisible)
619         D->setVisibleDespiteOwningModule();
620       else
621         Reader.HiddenNamesMap[Owner].push_back(D);
622     }
623   } else if (ModulePrivate) {
624     D->setModuleOwnershipKind(Decl::ModuleOwnershipKind::ModulePrivate);
625   }
626 }
627 
628 void ASTDeclReader::VisitPragmaCommentDecl(PragmaCommentDecl *D) {
629   VisitDecl(D);
630   D->setLocation(ReadSourceLocation());
631   D->CommentKind = (PragmaMSCommentKind)Record.readInt();
632   std::string Arg = ReadString();
633   memcpy(D->getTrailingObjects<char>(), Arg.data(), Arg.size());
634   D->getTrailingObjects<char>()[Arg.size()] = '\0';
635 }
636 
637 void ASTDeclReader::VisitPragmaDetectMismatchDecl(PragmaDetectMismatchDecl *D) {
638   VisitDecl(D);
639   D->setLocation(ReadSourceLocation());
640   std::string Name = ReadString();
641   memcpy(D->getTrailingObjects<char>(), Name.data(), Name.size());
642   D->getTrailingObjects<char>()[Name.size()] = '\0';
643 
644   D->ValueStart = Name.size() + 1;
645   std::string Value = ReadString();
646   memcpy(D->getTrailingObjects<char>() + D->ValueStart, Value.data(),
647          Value.size());
648   D->getTrailingObjects<char>()[D->ValueStart + Value.size()] = '\0';
649 }
650 
651 void ASTDeclReader::VisitTranslationUnitDecl(TranslationUnitDecl *TU) {
652   llvm_unreachable("Translation units are not serialized");
653 }
654 
655 void ASTDeclReader::VisitNamedDecl(NamedDecl *ND) {
656   VisitDecl(ND);
657   ND->setDeclName(Record.readDeclarationName());
658   AnonymousDeclNumber = Record.readInt();
659 }
660 
661 void ASTDeclReader::VisitTypeDecl(TypeDecl *TD) {
662   VisitNamedDecl(TD);
663   TD->setLocStart(ReadSourceLocation());
664   // Delay type reading until after we have fully initialized the decl.
665   DeferredTypeID = Record.getGlobalTypeID(Record.readInt());
666 }
667 
668 ASTDeclReader::RedeclarableResult
669 ASTDeclReader::VisitTypedefNameDecl(TypedefNameDecl *TD) {
670   RedeclarableResult Redecl = VisitRedeclarable(TD);
671   VisitTypeDecl(TD);
672   TypeSourceInfo *TInfo = GetTypeSourceInfo();
673   if (Record.readInt()) { // isModed
674     QualType modedT = Record.readType();
675     TD->setModedTypeSourceInfo(TInfo, modedT);
676   } else
677     TD->setTypeSourceInfo(TInfo);
678   // Read and discard the declaration for which this is a typedef name for
679   // linkage, if it exists. We cannot rely on our type to pull in this decl,
680   // because it might have been merged with a type from another module and
681   // thus might not refer to our version of the declaration.
682   ReadDecl();
683   return Redecl;
684 }
685 
686 void ASTDeclReader::VisitTypedefDecl(TypedefDecl *TD) {
687   RedeclarableResult Redecl = VisitTypedefNameDecl(TD);
688   mergeRedeclarable(TD, Redecl);
689 }
690 
691 void ASTDeclReader::VisitTypeAliasDecl(TypeAliasDecl *TD) {
692   RedeclarableResult Redecl = VisitTypedefNameDecl(TD);
693   if (auto *Template = ReadDeclAs<TypeAliasTemplateDecl>())
694     // Merged when we merge the template.
695     TD->setDescribedAliasTemplate(Template);
696   else
697     mergeRedeclarable(TD, Redecl);
698 }
699 
700 ASTDeclReader::RedeclarableResult ASTDeclReader::VisitTagDecl(TagDecl *TD) {
701   RedeclarableResult Redecl = VisitRedeclarable(TD);
702   VisitTypeDecl(TD);
703 
704   TD->IdentifierNamespace = Record.readInt();
705   TD->setTagKind((TagDecl::TagKind)Record.readInt());
706   if (!isa<CXXRecordDecl>(TD))
707     TD->setCompleteDefinition(Record.readInt());
708   TD->setEmbeddedInDeclarator(Record.readInt());
709   TD->setFreeStanding(Record.readInt());
710   TD->setCompleteDefinitionRequired(Record.readInt());
711   TD->setBraceRange(ReadSourceRange());
712 
713   switch (Record.readInt()) {
714   case 0:
715     break;
716   case 1: { // ExtInfo
717     auto *Info = new (Reader.getContext()) TagDecl::ExtInfo();
718     ReadQualifierInfo(*Info);
719     TD->TypedefNameDeclOrQualifier = Info;
720     break;
721   }
722   case 2: // TypedefNameForAnonDecl
723     NamedDeclForTagDecl = ReadDeclID();
724     TypedefNameForLinkage = Record.getIdentifierInfo();
725     break;
726   default:
727     llvm_unreachable("unexpected tag info kind");
728   }
729 
730   if (!isa<CXXRecordDecl>(TD))
731     mergeRedeclarable(TD, Redecl);
732   return Redecl;
733 }
734 
735 void ASTDeclReader::VisitEnumDecl(EnumDecl *ED) {
736   VisitTagDecl(ED);
737   if (TypeSourceInfo *TI = GetTypeSourceInfo())
738     ED->setIntegerTypeSourceInfo(TI);
739   else
740     ED->setIntegerType(Record.readType());
741   ED->setPromotionType(Record.readType());
742   ED->setNumPositiveBits(Record.readInt());
743   ED->setNumNegativeBits(Record.readInt());
744   ED->setScoped(Record.readInt());
745   ED->setScopedUsingClassTag(Record.readInt());
746   ED->setFixed(Record.readInt());
747 
748   ED->setHasODRHash(true);
749   ED->ODRHash = Record.readInt();
750 
751   // If this is a definition subject to the ODR, and we already have a
752   // definition, merge this one into it.
753   if (ED->isCompleteDefinition() &&
754       Reader.getContext().getLangOpts().Modules &&
755       Reader.getContext().getLangOpts().CPlusPlus) {
756     EnumDecl *&OldDef = Reader.EnumDefinitions[ED->getCanonicalDecl()];
757     if (!OldDef) {
758       // This is the first time we've seen an imported definition. Look for a
759       // local definition before deciding that we are the first definition.
760       for (auto *D : merged_redecls(ED->getCanonicalDecl())) {
761         if (!D->isFromASTFile() && D->isCompleteDefinition()) {
762           OldDef = D;
763           break;
764         }
765       }
766     }
767     if (OldDef) {
768       Reader.MergedDeclContexts.insert(std::make_pair(ED, OldDef));
769       ED->setCompleteDefinition(false);
770       Reader.mergeDefinitionVisibility(OldDef, ED);
771       if (OldDef->getODRHash() != ED->getODRHash())
772         Reader.PendingEnumOdrMergeFailures[OldDef].push_back(ED);
773     } else {
774       OldDef = ED;
775     }
776   }
777 
778   if (auto *InstED = ReadDeclAs<EnumDecl>()) {
779     auto TSK = (TemplateSpecializationKind)Record.readInt();
780     SourceLocation POI = ReadSourceLocation();
781     ED->setInstantiationOfMemberEnum(Reader.getContext(), InstED, TSK);
782     ED->getMemberSpecializationInfo()->setPointOfInstantiation(POI);
783   }
784 }
785 
786 ASTDeclReader::RedeclarableResult
787 ASTDeclReader::VisitRecordDeclImpl(RecordDecl *RD) {
788   RedeclarableResult Redecl = VisitTagDecl(RD);
789   RD->setHasFlexibleArrayMember(Record.readInt());
790   RD->setAnonymousStructOrUnion(Record.readInt());
791   RD->setHasObjectMember(Record.readInt());
792   RD->setHasVolatileMember(Record.readInt());
793   RD->setNonTrivialToPrimitiveDefaultInitialize(Record.readInt());
794   RD->setNonTrivialToPrimitiveCopy(Record.readInt());
795   RD->setNonTrivialToPrimitiveDestroy(Record.readInt());
796   RD->setParamDestroyedInCallee(Record.readInt());
797   RD->setArgPassingRestrictions((RecordDecl::ArgPassingKind)Record.readInt());
798   return Redecl;
799 }
800 
801 void ASTDeclReader::VisitValueDecl(ValueDecl *VD) {
802   VisitNamedDecl(VD);
803   // For function declarations, defer reading the type in case the function has
804   // a deduced return type that references an entity declared within the
805   // function.
806   if (isa<FunctionDecl>(VD))
807     DeferredTypeID = Record.getGlobalTypeID(Record.readInt());
808   else
809     VD->setType(Record.readType());
810 }
811 
812 void ASTDeclReader::VisitEnumConstantDecl(EnumConstantDecl *ECD) {
813   VisitValueDecl(ECD);
814   if (Record.readInt())
815     ECD->setInitExpr(Record.readExpr());
816   ECD->setInitVal(Record.readAPSInt());
817   mergeMergeable(ECD);
818 }
819 
820 void ASTDeclReader::VisitDeclaratorDecl(DeclaratorDecl *DD) {
821   VisitValueDecl(DD);
822   DD->setInnerLocStart(ReadSourceLocation());
823   if (Record.readInt()) { // hasExtInfo
824     auto *Info = new (Reader.getContext()) DeclaratorDecl::ExtInfo();
825     ReadQualifierInfo(*Info);
826     DD->DeclInfo = Info;
827   }
828   QualType TSIType = Record.readType();
829   DD->setTypeSourceInfo(
830       TSIType.isNull() ? nullptr
831                        : Reader.getContext().CreateTypeSourceInfo(TSIType));
832 }
833 
834 void ASTDeclReader::VisitFunctionDecl(FunctionDecl *FD) {
835   RedeclarableResult Redecl = VisitRedeclarable(FD);
836   VisitDeclaratorDecl(FD);
837 
838   // Attach a type to this function. Use the real type if possible, but fall
839   // back to the type as written if it involves a deduced return type.
840   if (FD->getTypeSourceInfo() &&
841       FD->getTypeSourceInfo()->getType()->castAs<FunctionType>()
842                              ->getReturnType()->getContainedAutoType()) {
843     // We'll set up the real type in Visit, once we've finished loading the
844     // function.
845     FD->setType(FD->getTypeSourceInfo()->getType());
846     Reader.PendingFunctionTypes.push_back({FD, DeferredTypeID});
847   } else {
848     FD->setType(Reader.GetType(DeferredTypeID));
849   }
850   DeferredTypeID = 0;
851 
852   ReadDeclarationNameLoc(FD->DNLoc, FD->getDeclName());
853   FD->IdentifierNamespace = Record.readInt();
854 
855   // FunctionDecl's body is handled last at ASTDeclReader::Visit,
856   // after everything else is read.
857 
858   FD->setStorageClass(static_cast<StorageClass>(Record.readInt()));
859   FD->setInlineSpecified(Record.readInt());
860   FD->setImplicitlyInline(Record.readInt());
861   FD->setVirtualAsWritten(Record.readInt());
862   FD->setPure(Record.readInt());
863   FD->setHasInheritedPrototype(Record.readInt());
864   FD->setHasWrittenPrototype(Record.readInt());
865   FD->setDeletedAsWritten(Record.readInt());
866   FD->setTrivial(Record.readInt());
867   FD->setTrivialForCall(Record.readInt());
868   FD->setDefaulted(Record.readInt());
869   FD->setExplicitlyDefaulted(Record.readInt());
870   FD->setHasImplicitReturnZero(Record.readInt());
871   FD->setConstexpr(Record.readInt());
872   FD->setUsesSEHTry(Record.readInt());
873   FD->setHasSkippedBody(Record.readInt());
874   FD->setIsMultiVersion(Record.readInt());
875   FD->setLateTemplateParsed(Record.readInt());
876 
877   FD->setCachedLinkage(static_cast<Linkage>(Record.readInt()));
878   FD->EndRangeLoc = ReadSourceLocation();
879 
880   FD->ODRHash = Record.readInt();
881   FD->setHasODRHash(true);
882 
883   switch ((FunctionDecl::TemplatedKind)Record.readInt()) {
884   case FunctionDecl::TK_NonTemplate:
885     mergeRedeclarable(FD, Redecl);
886     break;
887   case FunctionDecl::TK_FunctionTemplate:
888     // Merged when we merge the template.
889     FD->setDescribedFunctionTemplate(ReadDeclAs<FunctionTemplateDecl>());
890     break;
891   case FunctionDecl::TK_MemberSpecialization: {
892     auto *InstFD = ReadDeclAs<FunctionDecl>();
893     auto TSK = (TemplateSpecializationKind)Record.readInt();
894     SourceLocation POI = ReadSourceLocation();
895     FD->setInstantiationOfMemberFunction(Reader.getContext(), InstFD, TSK);
896     FD->getMemberSpecializationInfo()->setPointOfInstantiation(POI);
897     mergeRedeclarable(FD, Redecl);
898     break;
899   }
900   case FunctionDecl::TK_FunctionTemplateSpecialization: {
901     auto *Template = ReadDeclAs<FunctionTemplateDecl>();
902     auto TSK = (TemplateSpecializationKind)Record.readInt();
903 
904     // Template arguments.
905     SmallVector<TemplateArgument, 8> TemplArgs;
906     Record.readTemplateArgumentList(TemplArgs, /*Canonicalize*/ true);
907 
908     // Template args as written.
909     SmallVector<TemplateArgumentLoc, 8> TemplArgLocs;
910     SourceLocation LAngleLoc, RAngleLoc;
911     bool HasTemplateArgumentsAsWritten = Record.readInt();
912     if (HasTemplateArgumentsAsWritten) {
913       unsigned NumTemplateArgLocs = Record.readInt();
914       TemplArgLocs.reserve(NumTemplateArgLocs);
915       for (unsigned i = 0; i != NumTemplateArgLocs; ++i)
916         TemplArgLocs.push_back(Record.readTemplateArgumentLoc());
917 
918       LAngleLoc = ReadSourceLocation();
919       RAngleLoc = ReadSourceLocation();
920     }
921 
922     SourceLocation POI = ReadSourceLocation();
923 
924     ASTContext &C = Reader.getContext();
925     TemplateArgumentList *TemplArgList
926       = TemplateArgumentList::CreateCopy(C, TemplArgs);
927     TemplateArgumentListInfo TemplArgsInfo(LAngleLoc, RAngleLoc);
928     for (unsigned i = 0, e = TemplArgLocs.size(); i != e; ++i)
929       TemplArgsInfo.addArgument(TemplArgLocs[i]);
930 
931     MemberSpecializationInfo *MSInfo = nullptr;
932     if (Record.readInt()) {
933       auto *FD = ReadDeclAs<FunctionDecl>();
934       auto TSK = (TemplateSpecializationKind)Record.readInt();
935       SourceLocation POI = ReadSourceLocation();
936 
937       MSInfo = new (C) MemberSpecializationInfo(FD, TSK);
938       MSInfo->setPointOfInstantiation(POI);
939     }
940 
941     FunctionTemplateSpecializationInfo *FTInfo =
942         FunctionTemplateSpecializationInfo::Create(
943             C, FD, Template, TSK, TemplArgList,
944             HasTemplateArgumentsAsWritten ? &TemplArgsInfo : nullptr, POI,
945             MSInfo);
946     FD->TemplateOrSpecialization = FTInfo;
947 
948     if (FD->isCanonicalDecl()) { // if canonical add to template's set.
949       // The template that contains the specializations set. It's not safe to
950       // use getCanonicalDecl on Template since it may still be initializing.
951       auto *CanonTemplate = ReadDeclAs<FunctionTemplateDecl>();
952       // Get the InsertPos by FindNodeOrInsertPos() instead of calling
953       // InsertNode(FTInfo) directly to avoid the getASTContext() call in
954       // FunctionTemplateSpecializationInfo's Profile().
955       // We avoid getASTContext because a decl in the parent hierarchy may
956       // be initializing.
957       llvm::FoldingSetNodeID ID;
958       FunctionTemplateSpecializationInfo::Profile(ID, TemplArgs, C);
959       void *InsertPos = nullptr;
960       FunctionTemplateDecl::Common *CommonPtr = CanonTemplate->getCommonPtr();
961       FunctionTemplateSpecializationInfo *ExistingInfo =
962           CommonPtr->Specializations.FindNodeOrInsertPos(ID, InsertPos);
963       if (InsertPos)
964         CommonPtr->Specializations.InsertNode(FTInfo, InsertPos);
965       else {
966         assert(Reader.getContext().getLangOpts().Modules &&
967                "already deserialized this template specialization");
968         mergeRedeclarable(FD, ExistingInfo->getFunction(), Redecl);
969       }
970     }
971     break;
972   }
973   case FunctionDecl::TK_DependentFunctionTemplateSpecialization: {
974     // Templates.
975     UnresolvedSet<8> TemplDecls;
976     unsigned NumTemplates = Record.readInt();
977     while (NumTemplates--)
978       TemplDecls.addDecl(ReadDeclAs<NamedDecl>());
979 
980     // Templates args.
981     TemplateArgumentListInfo TemplArgs;
982     unsigned NumArgs = Record.readInt();
983     while (NumArgs--)
984       TemplArgs.addArgument(Record.readTemplateArgumentLoc());
985     TemplArgs.setLAngleLoc(ReadSourceLocation());
986     TemplArgs.setRAngleLoc(ReadSourceLocation());
987 
988     FD->setDependentTemplateSpecialization(Reader.getContext(),
989                                            TemplDecls, TemplArgs);
990     // These are not merged; we don't need to merge redeclarations of dependent
991     // template friends.
992     break;
993   }
994   }
995 
996   // Read in the parameters.
997   unsigned NumParams = Record.readInt();
998   SmallVector<ParmVarDecl *, 16> Params;
999   Params.reserve(NumParams);
1000   for (unsigned I = 0; I != NumParams; ++I)
1001     Params.push_back(ReadDeclAs<ParmVarDecl>());
1002   FD->setParams(Reader.getContext(), Params);
1003 }
1004 
1005 void ASTDeclReader::VisitObjCMethodDecl(ObjCMethodDecl *MD) {
1006   VisitNamedDecl(MD);
1007   if (Record.readInt()) {
1008     // Load the body on-demand. Most clients won't care, because method
1009     // definitions rarely show up in headers.
1010     Reader.PendingBodies[MD] = GetCurrentCursorOffset();
1011     HasPendingBody = true;
1012     MD->setSelfDecl(ReadDeclAs<ImplicitParamDecl>());
1013     MD->setCmdDecl(ReadDeclAs<ImplicitParamDecl>());
1014   }
1015   MD->setInstanceMethod(Record.readInt());
1016   MD->setVariadic(Record.readInt());
1017   MD->setPropertyAccessor(Record.readInt());
1018   MD->setDefined(Record.readInt());
1019   MD->setOverriding(Record.readInt());
1020   MD->setHasSkippedBody(Record.readInt());
1021 
1022   MD->setIsRedeclaration(Record.readInt());
1023   MD->setHasRedeclaration(Record.readInt());
1024   if (MD->hasRedeclaration())
1025     Reader.getContext().setObjCMethodRedeclaration(MD,
1026                                        ReadDeclAs<ObjCMethodDecl>());
1027 
1028   MD->setDeclImplementation((ObjCMethodDecl::ImplementationControl)Record.readInt());
1029   MD->setObjCDeclQualifier((Decl::ObjCDeclQualifier)Record.readInt());
1030   MD->setRelatedResultType(Record.readInt());
1031   MD->setReturnType(Record.readType());
1032   MD->setReturnTypeSourceInfo(GetTypeSourceInfo());
1033   MD->DeclEndLoc = ReadSourceLocation();
1034   unsigned NumParams = Record.readInt();
1035   SmallVector<ParmVarDecl *, 16> Params;
1036   Params.reserve(NumParams);
1037   for (unsigned I = 0; I != NumParams; ++I)
1038     Params.push_back(ReadDeclAs<ParmVarDecl>());
1039 
1040   MD->setSelLocsKind((SelectorLocationsKind)Record.readInt());
1041   unsigned NumStoredSelLocs = Record.readInt();
1042   SmallVector<SourceLocation, 16> SelLocs;
1043   SelLocs.reserve(NumStoredSelLocs);
1044   for (unsigned i = 0; i != NumStoredSelLocs; ++i)
1045     SelLocs.push_back(ReadSourceLocation());
1046 
1047   MD->setParamsAndSelLocs(Reader.getContext(), Params, SelLocs);
1048 }
1049 
1050 void ASTDeclReader::VisitObjCTypeParamDecl(ObjCTypeParamDecl *D) {
1051   VisitTypedefNameDecl(D);
1052 
1053   D->Variance = Record.readInt();
1054   D->Index = Record.readInt();
1055   D->VarianceLoc = ReadSourceLocation();
1056   D->ColonLoc = ReadSourceLocation();
1057 }
1058 
1059 void ASTDeclReader::VisitObjCContainerDecl(ObjCContainerDecl *CD) {
1060   VisitNamedDecl(CD);
1061   CD->setAtStartLoc(ReadSourceLocation());
1062   CD->setAtEndRange(ReadSourceRange());
1063 }
1064 
1065 ObjCTypeParamList *ASTDeclReader::ReadObjCTypeParamList() {
1066   unsigned numParams = Record.readInt();
1067   if (numParams == 0)
1068     return nullptr;
1069 
1070   SmallVector<ObjCTypeParamDecl *, 4> typeParams;
1071   typeParams.reserve(numParams);
1072   for (unsigned i = 0; i != numParams; ++i) {
1073     auto *typeParam = ReadDeclAs<ObjCTypeParamDecl>();
1074     if (!typeParam)
1075       return nullptr;
1076 
1077     typeParams.push_back(typeParam);
1078   }
1079 
1080   SourceLocation lAngleLoc = ReadSourceLocation();
1081   SourceLocation rAngleLoc = ReadSourceLocation();
1082 
1083   return ObjCTypeParamList::create(Reader.getContext(), lAngleLoc,
1084                                    typeParams, rAngleLoc);
1085 }
1086 
1087 void ASTDeclReader::ReadObjCDefinitionData(
1088          struct ObjCInterfaceDecl::DefinitionData &Data) {
1089   // Read the superclass.
1090   Data.SuperClassTInfo = GetTypeSourceInfo();
1091 
1092   Data.EndLoc = ReadSourceLocation();
1093   Data.HasDesignatedInitializers = Record.readInt();
1094 
1095   // Read the directly referenced protocols and their SourceLocations.
1096   unsigned NumProtocols = Record.readInt();
1097   SmallVector<ObjCProtocolDecl *, 16> Protocols;
1098   Protocols.reserve(NumProtocols);
1099   for (unsigned I = 0; I != NumProtocols; ++I)
1100     Protocols.push_back(ReadDeclAs<ObjCProtocolDecl>());
1101   SmallVector<SourceLocation, 16> ProtoLocs;
1102   ProtoLocs.reserve(NumProtocols);
1103   for (unsigned I = 0; I != NumProtocols; ++I)
1104     ProtoLocs.push_back(ReadSourceLocation());
1105   Data.ReferencedProtocols.set(Protocols.data(), NumProtocols, ProtoLocs.data(),
1106                                Reader.getContext());
1107 
1108   // Read the transitive closure of protocols referenced by this class.
1109   NumProtocols = Record.readInt();
1110   Protocols.clear();
1111   Protocols.reserve(NumProtocols);
1112   for (unsigned I = 0; I != NumProtocols; ++I)
1113     Protocols.push_back(ReadDeclAs<ObjCProtocolDecl>());
1114   Data.AllReferencedProtocols.set(Protocols.data(), NumProtocols,
1115                                   Reader.getContext());
1116 }
1117 
1118 void ASTDeclReader::MergeDefinitionData(ObjCInterfaceDecl *D,
1119          struct ObjCInterfaceDecl::DefinitionData &&NewDD) {
1120   // FIXME: odr checking?
1121 }
1122 
1123 void ASTDeclReader::VisitObjCInterfaceDecl(ObjCInterfaceDecl *ID) {
1124   RedeclarableResult Redecl = VisitRedeclarable(ID);
1125   VisitObjCContainerDecl(ID);
1126   DeferredTypeID = Record.getGlobalTypeID(Record.readInt());
1127   mergeRedeclarable(ID, Redecl);
1128 
1129   ID->TypeParamList = ReadObjCTypeParamList();
1130   if (Record.readInt()) {
1131     // Read the definition.
1132     ID->allocateDefinitionData();
1133 
1134     ReadObjCDefinitionData(ID->data());
1135     ObjCInterfaceDecl *Canon = ID->getCanonicalDecl();
1136     if (Canon->Data.getPointer()) {
1137       // If we already have a definition, keep the definition invariant and
1138       // merge the data.
1139       MergeDefinitionData(Canon, std::move(ID->data()));
1140       ID->Data = Canon->Data;
1141     } else {
1142       // Set the definition data of the canonical declaration, so other
1143       // redeclarations will see it.
1144       ID->getCanonicalDecl()->Data = ID->Data;
1145 
1146       // We will rebuild this list lazily.
1147       ID->setIvarList(nullptr);
1148     }
1149 
1150     // Note that we have deserialized a definition.
1151     Reader.PendingDefinitions.insert(ID);
1152 
1153     // Note that we've loaded this Objective-C class.
1154     Reader.ObjCClassesLoaded.push_back(ID);
1155   } else {
1156     ID->Data = ID->getCanonicalDecl()->Data;
1157   }
1158 }
1159 
1160 void ASTDeclReader::VisitObjCIvarDecl(ObjCIvarDecl *IVD) {
1161   VisitFieldDecl(IVD);
1162   IVD->setAccessControl((ObjCIvarDecl::AccessControl)Record.readInt());
1163   // This field will be built lazily.
1164   IVD->setNextIvar(nullptr);
1165   bool synth = Record.readInt();
1166   IVD->setSynthesize(synth);
1167 }
1168 
1169 void ASTDeclReader::ReadObjCDefinitionData(
1170          struct ObjCProtocolDecl::DefinitionData &Data) {
1171     unsigned NumProtoRefs = Record.readInt();
1172     SmallVector<ObjCProtocolDecl *, 16> ProtoRefs;
1173     ProtoRefs.reserve(NumProtoRefs);
1174     for (unsigned I = 0; I != NumProtoRefs; ++I)
1175       ProtoRefs.push_back(ReadDeclAs<ObjCProtocolDecl>());
1176     SmallVector<SourceLocation, 16> ProtoLocs;
1177     ProtoLocs.reserve(NumProtoRefs);
1178     for (unsigned I = 0; I != NumProtoRefs; ++I)
1179       ProtoLocs.push_back(ReadSourceLocation());
1180     Data.ReferencedProtocols.set(ProtoRefs.data(), NumProtoRefs,
1181                                  ProtoLocs.data(), Reader.getContext());
1182 }
1183 
1184 void ASTDeclReader::MergeDefinitionData(ObjCProtocolDecl *D,
1185          struct ObjCProtocolDecl::DefinitionData &&NewDD) {
1186   // FIXME: odr checking?
1187 }
1188 
1189 void ASTDeclReader::VisitObjCProtocolDecl(ObjCProtocolDecl *PD) {
1190   RedeclarableResult Redecl = VisitRedeclarable(PD);
1191   VisitObjCContainerDecl(PD);
1192   mergeRedeclarable(PD, Redecl);
1193 
1194   if (Record.readInt()) {
1195     // Read the definition.
1196     PD->allocateDefinitionData();
1197 
1198     ReadObjCDefinitionData(PD->data());
1199 
1200     ObjCProtocolDecl *Canon = PD->getCanonicalDecl();
1201     if (Canon->Data.getPointer()) {
1202       // If we already have a definition, keep the definition invariant and
1203       // merge the data.
1204       MergeDefinitionData(Canon, std::move(PD->data()));
1205       PD->Data = Canon->Data;
1206     } else {
1207       // Set the definition data of the canonical declaration, so other
1208       // redeclarations will see it.
1209       PD->getCanonicalDecl()->Data = PD->Data;
1210     }
1211     // Note that we have deserialized a definition.
1212     Reader.PendingDefinitions.insert(PD);
1213   } else {
1214     PD->Data = PD->getCanonicalDecl()->Data;
1215   }
1216 }
1217 
1218 void ASTDeclReader::VisitObjCAtDefsFieldDecl(ObjCAtDefsFieldDecl *FD) {
1219   VisitFieldDecl(FD);
1220 }
1221 
1222 void ASTDeclReader::VisitObjCCategoryDecl(ObjCCategoryDecl *CD) {
1223   VisitObjCContainerDecl(CD);
1224   CD->setCategoryNameLoc(ReadSourceLocation());
1225   CD->setIvarLBraceLoc(ReadSourceLocation());
1226   CD->setIvarRBraceLoc(ReadSourceLocation());
1227 
1228   // Note that this category has been deserialized. We do this before
1229   // deserializing the interface declaration, so that it will consider this
1230   /// category.
1231   Reader.CategoriesDeserialized.insert(CD);
1232 
1233   CD->ClassInterface = ReadDeclAs<ObjCInterfaceDecl>();
1234   CD->TypeParamList = ReadObjCTypeParamList();
1235   unsigned NumProtoRefs = Record.readInt();
1236   SmallVector<ObjCProtocolDecl *, 16> ProtoRefs;
1237   ProtoRefs.reserve(NumProtoRefs);
1238   for (unsigned I = 0; I != NumProtoRefs; ++I)
1239     ProtoRefs.push_back(ReadDeclAs<ObjCProtocolDecl>());
1240   SmallVector<SourceLocation, 16> ProtoLocs;
1241   ProtoLocs.reserve(NumProtoRefs);
1242   for (unsigned I = 0; I != NumProtoRefs; ++I)
1243     ProtoLocs.push_back(ReadSourceLocation());
1244   CD->setProtocolList(ProtoRefs.data(), NumProtoRefs, ProtoLocs.data(),
1245                       Reader.getContext());
1246 
1247   // Protocols in the class extension belong to the class.
1248   if (NumProtoRefs > 0 && CD->ClassInterface && CD->IsClassExtension())
1249     CD->ClassInterface->mergeClassExtensionProtocolList(
1250         (ObjCProtocolDecl *const *)ProtoRefs.data(), NumProtoRefs,
1251         Reader.getContext());
1252 }
1253 
1254 void ASTDeclReader::VisitObjCCompatibleAliasDecl(ObjCCompatibleAliasDecl *CAD) {
1255   VisitNamedDecl(CAD);
1256   CAD->setClassInterface(ReadDeclAs<ObjCInterfaceDecl>());
1257 }
1258 
1259 void ASTDeclReader::VisitObjCPropertyDecl(ObjCPropertyDecl *D) {
1260   VisitNamedDecl(D);
1261   D->setAtLoc(ReadSourceLocation());
1262   D->setLParenLoc(ReadSourceLocation());
1263   QualType T = Record.readType();
1264   TypeSourceInfo *TSI = GetTypeSourceInfo();
1265   D->setType(T, TSI);
1266   D->setPropertyAttributes(
1267       (ObjCPropertyDecl::PropertyAttributeKind)Record.readInt());
1268   D->setPropertyAttributesAsWritten(
1269       (ObjCPropertyDecl::PropertyAttributeKind)Record.readInt());
1270   D->setPropertyImplementation(
1271       (ObjCPropertyDecl::PropertyControl)Record.readInt());
1272   DeclarationName GetterName = Record.readDeclarationName();
1273   SourceLocation GetterLoc = ReadSourceLocation();
1274   D->setGetterName(GetterName.getObjCSelector(), GetterLoc);
1275   DeclarationName SetterName = Record.readDeclarationName();
1276   SourceLocation SetterLoc = ReadSourceLocation();
1277   D->setSetterName(SetterName.getObjCSelector(), SetterLoc);
1278   D->setGetterMethodDecl(ReadDeclAs<ObjCMethodDecl>());
1279   D->setSetterMethodDecl(ReadDeclAs<ObjCMethodDecl>());
1280   D->setPropertyIvarDecl(ReadDeclAs<ObjCIvarDecl>());
1281 }
1282 
1283 void ASTDeclReader::VisitObjCImplDecl(ObjCImplDecl *D) {
1284   VisitObjCContainerDecl(D);
1285   D->setClassInterface(ReadDeclAs<ObjCInterfaceDecl>());
1286 }
1287 
1288 void ASTDeclReader::VisitObjCCategoryImplDecl(ObjCCategoryImplDecl *D) {
1289   VisitObjCImplDecl(D);
1290   D->CategoryNameLoc = ReadSourceLocation();
1291 }
1292 
1293 void ASTDeclReader::VisitObjCImplementationDecl(ObjCImplementationDecl *D) {
1294   VisitObjCImplDecl(D);
1295   D->setSuperClass(ReadDeclAs<ObjCInterfaceDecl>());
1296   D->SuperLoc = ReadSourceLocation();
1297   D->setIvarLBraceLoc(ReadSourceLocation());
1298   D->setIvarRBraceLoc(ReadSourceLocation());
1299   D->setHasNonZeroConstructors(Record.readInt());
1300   D->setHasDestructors(Record.readInt());
1301   D->NumIvarInitializers = Record.readInt();
1302   if (D->NumIvarInitializers)
1303     D->IvarInitializers = ReadGlobalOffset();
1304 }
1305 
1306 void ASTDeclReader::VisitObjCPropertyImplDecl(ObjCPropertyImplDecl *D) {
1307   VisitDecl(D);
1308   D->setAtLoc(ReadSourceLocation());
1309   D->setPropertyDecl(ReadDeclAs<ObjCPropertyDecl>());
1310   D->PropertyIvarDecl = ReadDeclAs<ObjCIvarDecl>();
1311   D->IvarLoc = ReadSourceLocation();
1312   D->setGetterCXXConstructor(Record.readExpr());
1313   D->setSetterCXXAssignment(Record.readExpr());
1314 }
1315 
1316 void ASTDeclReader::VisitFieldDecl(FieldDecl *FD) {
1317   VisitDeclaratorDecl(FD);
1318   FD->Mutable = Record.readInt();
1319 
1320   if (auto ISK = static_cast<FieldDecl::InitStorageKind>(Record.readInt())) {
1321     FD->InitStorage.setInt(ISK);
1322     FD->InitStorage.setPointer(ISK == FieldDecl::ISK_CapturedVLAType
1323                                    ? Record.readType().getAsOpaquePtr()
1324                                    : Record.readExpr());
1325   }
1326 
1327   if (auto *BW = Record.readExpr())
1328     FD->setBitWidth(BW);
1329 
1330   if (!FD->getDeclName()) {
1331     if (auto *Tmpl = ReadDeclAs<FieldDecl>())
1332       Reader.getContext().setInstantiatedFromUnnamedFieldDecl(FD, Tmpl);
1333   }
1334   mergeMergeable(FD);
1335 }
1336 
1337 void ASTDeclReader::VisitMSPropertyDecl(MSPropertyDecl *PD) {
1338   VisitDeclaratorDecl(PD);
1339   PD->GetterId = Record.getIdentifierInfo();
1340   PD->SetterId = Record.getIdentifierInfo();
1341 }
1342 
1343 void ASTDeclReader::VisitIndirectFieldDecl(IndirectFieldDecl *FD) {
1344   VisitValueDecl(FD);
1345 
1346   FD->ChainingSize = Record.readInt();
1347   assert(FD->ChainingSize >= 2 && "Anonymous chaining must be >= 2");
1348   FD->Chaining = new (Reader.getContext())NamedDecl*[FD->ChainingSize];
1349 
1350   for (unsigned I = 0; I != FD->ChainingSize; ++I)
1351     FD->Chaining[I] = ReadDeclAs<NamedDecl>();
1352 
1353   mergeMergeable(FD);
1354 }
1355 
1356 ASTDeclReader::RedeclarableResult ASTDeclReader::VisitVarDeclImpl(VarDecl *VD) {
1357   RedeclarableResult Redecl = VisitRedeclarable(VD);
1358   VisitDeclaratorDecl(VD);
1359 
1360   VD->VarDeclBits.SClass = (StorageClass)Record.readInt();
1361   VD->VarDeclBits.TSCSpec = Record.readInt();
1362   VD->VarDeclBits.InitStyle = Record.readInt();
1363   VD->VarDeclBits.ARCPseudoStrong = Record.readInt();
1364   if (!isa<ParmVarDecl>(VD)) {
1365     VD->NonParmVarDeclBits.IsThisDeclarationADemotedDefinition =
1366         Record.readInt();
1367     VD->NonParmVarDeclBits.ExceptionVar = Record.readInt();
1368     VD->NonParmVarDeclBits.NRVOVariable = Record.readInt();
1369     VD->NonParmVarDeclBits.CXXForRangeDecl = Record.readInt();
1370     VD->NonParmVarDeclBits.ObjCForDecl = Record.readInt();
1371     VD->NonParmVarDeclBits.IsInline = Record.readInt();
1372     VD->NonParmVarDeclBits.IsInlineSpecified = Record.readInt();
1373     VD->NonParmVarDeclBits.IsConstexpr = Record.readInt();
1374     VD->NonParmVarDeclBits.IsInitCapture = Record.readInt();
1375     VD->NonParmVarDeclBits.PreviousDeclInSameBlockScope = Record.readInt();
1376     VD->NonParmVarDeclBits.ImplicitParamKind = Record.readInt();
1377     VD->NonParmVarDeclBits.EscapingByref = Record.readInt();
1378   }
1379   auto VarLinkage = Linkage(Record.readInt());
1380   VD->setCachedLinkage(VarLinkage);
1381 
1382   // Reconstruct the one piece of the IdentifierNamespace that we need.
1383   if (VD->getStorageClass() == SC_Extern && VarLinkage != NoLinkage &&
1384       VD->getLexicalDeclContext()->isFunctionOrMethod())
1385     VD->setLocalExternDecl();
1386 
1387   if (uint64_t Val = Record.readInt()) {
1388     VD->setInit(Record.readExpr());
1389     if (Val > 1) { // IsInitKnownICE = 1, IsInitNotICE = 2, IsInitICE = 3
1390       EvaluatedStmt *Eval = VD->ensureEvaluatedStmt();
1391       Eval->CheckedICE = true;
1392       Eval->IsICE = Val == 3;
1393     }
1394   }
1395 
1396   if (VD->hasAttr<BlocksAttr>() && VD->getType()->getAsCXXRecordDecl()) {
1397     Expr *CopyExpr = Record.readExpr();
1398     if (CopyExpr)
1399       Reader.getContext().setBlockVarCopyInit(VD, CopyExpr, Record.readInt());
1400   }
1401 
1402   if (VD->getStorageDuration() == SD_Static && Record.readInt())
1403     Reader.DefinitionSource[VD] = Loc.F->Kind == ModuleKind::MK_MainFile;
1404 
1405   enum VarKind {
1406     VarNotTemplate = 0, VarTemplate, StaticDataMemberSpecialization
1407   };
1408   switch ((VarKind)Record.readInt()) {
1409   case VarNotTemplate:
1410     // Only true variables (not parameters or implicit parameters) can be
1411     // merged; the other kinds are not really redeclarable at all.
1412     if (!isa<ParmVarDecl>(VD) && !isa<ImplicitParamDecl>(VD) &&
1413         !isa<VarTemplateSpecializationDecl>(VD))
1414       mergeRedeclarable(VD, Redecl);
1415     break;
1416   case VarTemplate:
1417     // Merged when we merge the template.
1418     VD->setDescribedVarTemplate(ReadDeclAs<VarTemplateDecl>());
1419     break;
1420   case StaticDataMemberSpecialization: { // HasMemberSpecializationInfo.
1421     auto *Tmpl = ReadDeclAs<VarDecl>();
1422     auto TSK = (TemplateSpecializationKind)Record.readInt();
1423     SourceLocation POI = ReadSourceLocation();
1424     Reader.getContext().setInstantiatedFromStaticDataMember(VD, Tmpl, TSK,POI);
1425     mergeRedeclarable(VD, Redecl);
1426     break;
1427   }
1428   }
1429 
1430   return Redecl;
1431 }
1432 
1433 void ASTDeclReader::VisitImplicitParamDecl(ImplicitParamDecl *PD) {
1434   VisitVarDecl(PD);
1435 }
1436 
1437 void ASTDeclReader::VisitParmVarDecl(ParmVarDecl *PD) {
1438   VisitVarDecl(PD);
1439   unsigned isObjCMethodParam = Record.readInt();
1440   unsigned scopeDepth = Record.readInt();
1441   unsigned scopeIndex = Record.readInt();
1442   unsigned declQualifier = Record.readInt();
1443   if (isObjCMethodParam) {
1444     assert(scopeDepth == 0);
1445     PD->setObjCMethodScopeInfo(scopeIndex);
1446     PD->ParmVarDeclBits.ScopeDepthOrObjCQuals = declQualifier;
1447   } else {
1448     PD->setScopeInfo(scopeDepth, scopeIndex);
1449   }
1450   PD->ParmVarDeclBits.IsKNRPromoted = Record.readInt();
1451   PD->ParmVarDeclBits.HasInheritedDefaultArg = Record.readInt();
1452   if (Record.readInt()) // hasUninstantiatedDefaultArg.
1453     PD->setUninstantiatedDefaultArg(Record.readExpr());
1454 
1455   // FIXME: If this is a redeclaration of a function from another module, handle
1456   // inheritance of default arguments.
1457 }
1458 
1459 void ASTDeclReader::VisitDecompositionDecl(DecompositionDecl *DD) {
1460   VisitVarDecl(DD);
1461   auto **BDs = DD->getTrailingObjects<BindingDecl *>();
1462   for (unsigned I = 0; I != DD->NumBindings; ++I)
1463     BDs[I] = ReadDeclAs<BindingDecl>();
1464 }
1465 
1466 void ASTDeclReader::VisitBindingDecl(BindingDecl *BD) {
1467   VisitValueDecl(BD);
1468   BD->Binding = Record.readExpr();
1469 }
1470 
1471 void ASTDeclReader::VisitFileScopeAsmDecl(FileScopeAsmDecl *AD) {
1472   VisitDecl(AD);
1473   AD->setAsmString(cast<StringLiteral>(Record.readExpr()));
1474   AD->setRParenLoc(ReadSourceLocation());
1475 }
1476 
1477 void ASTDeclReader::VisitBlockDecl(BlockDecl *BD) {
1478   VisitDecl(BD);
1479   BD->setBody(cast_or_null<CompoundStmt>(Record.readStmt()));
1480   BD->setSignatureAsWritten(GetTypeSourceInfo());
1481   unsigned NumParams = Record.readInt();
1482   SmallVector<ParmVarDecl *, 16> Params;
1483   Params.reserve(NumParams);
1484   for (unsigned I = 0; I != NumParams; ++I)
1485     Params.push_back(ReadDeclAs<ParmVarDecl>());
1486   BD->setParams(Params);
1487 
1488   BD->setIsVariadic(Record.readInt());
1489   BD->setBlockMissingReturnType(Record.readInt());
1490   BD->setIsConversionFromLambda(Record.readInt());
1491   BD->setDoesNotEscape(Record.readInt());
1492   BD->setCanAvoidCopyToHeap(Record.readInt());
1493 
1494   bool capturesCXXThis = Record.readInt();
1495   unsigned numCaptures = Record.readInt();
1496   SmallVector<BlockDecl::Capture, 16> captures;
1497   captures.reserve(numCaptures);
1498   for (unsigned i = 0; i != numCaptures; ++i) {
1499     auto *decl = ReadDeclAs<VarDecl>();
1500     unsigned flags = Record.readInt();
1501     bool byRef = (flags & 1);
1502     bool nested = (flags & 2);
1503     Expr *copyExpr = ((flags & 4) ? Record.readExpr() : nullptr);
1504 
1505     captures.push_back(BlockDecl::Capture(decl, byRef, nested, copyExpr));
1506   }
1507   BD->setCaptures(Reader.getContext(), captures, capturesCXXThis);
1508 }
1509 
1510 void ASTDeclReader::VisitCapturedDecl(CapturedDecl *CD) {
1511   VisitDecl(CD);
1512   unsigned ContextParamPos = Record.readInt();
1513   CD->setNothrow(Record.readInt() != 0);
1514   // Body is set by VisitCapturedStmt.
1515   for (unsigned I = 0; I < CD->NumParams; ++I) {
1516     if (I != ContextParamPos)
1517       CD->setParam(I, ReadDeclAs<ImplicitParamDecl>());
1518     else
1519       CD->setContextParam(I, ReadDeclAs<ImplicitParamDecl>());
1520   }
1521 }
1522 
1523 void ASTDeclReader::VisitLinkageSpecDecl(LinkageSpecDecl *D) {
1524   VisitDecl(D);
1525   D->setLanguage((LinkageSpecDecl::LanguageIDs)Record.readInt());
1526   D->setExternLoc(ReadSourceLocation());
1527   D->setRBraceLoc(ReadSourceLocation());
1528 }
1529 
1530 void ASTDeclReader::VisitExportDecl(ExportDecl *D) {
1531   VisitDecl(D);
1532   D->RBraceLoc = ReadSourceLocation();
1533 }
1534 
1535 void ASTDeclReader::VisitLabelDecl(LabelDecl *D) {
1536   VisitNamedDecl(D);
1537   D->setLocStart(ReadSourceLocation());
1538 }
1539 
1540 void ASTDeclReader::VisitNamespaceDecl(NamespaceDecl *D) {
1541   RedeclarableResult Redecl = VisitRedeclarable(D);
1542   VisitNamedDecl(D);
1543   D->setInline(Record.readInt());
1544   D->LocStart = ReadSourceLocation();
1545   D->RBraceLoc = ReadSourceLocation();
1546 
1547   // Defer loading the anonymous namespace until we've finished merging
1548   // this namespace; loading it might load a later declaration of the
1549   // same namespace, and we have an invariant that older declarations
1550   // get merged before newer ones try to merge.
1551   GlobalDeclID AnonNamespace = 0;
1552   if (Redecl.getFirstID() == ThisDeclID) {
1553     AnonNamespace = ReadDeclID();
1554   } else {
1555     // Link this namespace back to the first declaration, which has already
1556     // been deserialized.
1557     D->AnonOrFirstNamespaceAndInline.setPointer(D->getFirstDecl());
1558   }
1559 
1560   mergeRedeclarable(D, Redecl);
1561 
1562   if (AnonNamespace) {
1563     // Each module has its own anonymous namespace, which is disjoint from
1564     // any other module's anonymous namespaces, so don't attach the anonymous
1565     // namespace at all.
1566     auto *Anon = cast<NamespaceDecl>(Reader.GetDecl(AnonNamespace));
1567     if (!Record.isModule())
1568       D->setAnonymousNamespace(Anon);
1569   }
1570 }
1571 
1572 void ASTDeclReader::VisitNamespaceAliasDecl(NamespaceAliasDecl *D) {
1573   RedeclarableResult Redecl = VisitRedeclarable(D);
1574   VisitNamedDecl(D);
1575   D->NamespaceLoc = ReadSourceLocation();
1576   D->IdentLoc = ReadSourceLocation();
1577   D->QualifierLoc = Record.readNestedNameSpecifierLoc();
1578   D->Namespace = ReadDeclAs<NamedDecl>();
1579   mergeRedeclarable(D, Redecl);
1580 }
1581 
1582 void ASTDeclReader::VisitUsingDecl(UsingDecl *D) {
1583   VisitNamedDecl(D);
1584   D->setUsingLoc(ReadSourceLocation());
1585   D->QualifierLoc = Record.readNestedNameSpecifierLoc();
1586   ReadDeclarationNameLoc(D->DNLoc, D->getDeclName());
1587   D->FirstUsingShadow.setPointer(ReadDeclAs<UsingShadowDecl>());
1588   D->setTypename(Record.readInt());
1589   if (auto *Pattern = ReadDeclAs<NamedDecl>())
1590     Reader.getContext().setInstantiatedFromUsingDecl(D, Pattern);
1591   mergeMergeable(D);
1592 }
1593 
1594 void ASTDeclReader::VisitUsingPackDecl(UsingPackDecl *D) {
1595   VisitNamedDecl(D);
1596   D->InstantiatedFrom = ReadDeclAs<NamedDecl>();
1597   auto **Expansions = D->getTrailingObjects<NamedDecl *>();
1598   for (unsigned I = 0; I != D->NumExpansions; ++I)
1599     Expansions[I] = ReadDeclAs<NamedDecl>();
1600   mergeMergeable(D);
1601 }
1602 
1603 void ASTDeclReader::VisitUsingShadowDecl(UsingShadowDecl *D) {
1604   RedeclarableResult Redecl = VisitRedeclarable(D);
1605   VisitNamedDecl(D);
1606   D->Underlying = ReadDeclAs<NamedDecl>();
1607   D->IdentifierNamespace = Record.readInt();
1608   D->UsingOrNextShadow = ReadDeclAs<NamedDecl>();
1609   auto *Pattern = ReadDeclAs<UsingShadowDecl>();
1610   if (Pattern)
1611     Reader.getContext().setInstantiatedFromUsingShadowDecl(D, Pattern);
1612   mergeRedeclarable(D, Redecl);
1613 }
1614 
1615 void ASTDeclReader::VisitConstructorUsingShadowDecl(
1616     ConstructorUsingShadowDecl *D) {
1617   VisitUsingShadowDecl(D);
1618   D->NominatedBaseClassShadowDecl = ReadDeclAs<ConstructorUsingShadowDecl>();
1619   D->ConstructedBaseClassShadowDecl = ReadDeclAs<ConstructorUsingShadowDecl>();
1620   D->IsVirtual = Record.readInt();
1621 }
1622 
1623 void ASTDeclReader::VisitUsingDirectiveDecl(UsingDirectiveDecl *D) {
1624   VisitNamedDecl(D);
1625   D->UsingLoc = ReadSourceLocation();
1626   D->NamespaceLoc = ReadSourceLocation();
1627   D->QualifierLoc = Record.readNestedNameSpecifierLoc();
1628   D->NominatedNamespace = ReadDeclAs<NamedDecl>();
1629   D->CommonAncestor = ReadDeclAs<DeclContext>();
1630 }
1631 
1632 void ASTDeclReader::VisitUnresolvedUsingValueDecl(UnresolvedUsingValueDecl *D) {
1633   VisitValueDecl(D);
1634   D->setUsingLoc(ReadSourceLocation());
1635   D->QualifierLoc = Record.readNestedNameSpecifierLoc();
1636   ReadDeclarationNameLoc(D->DNLoc, D->getDeclName());
1637   D->EllipsisLoc = ReadSourceLocation();
1638   mergeMergeable(D);
1639 }
1640 
1641 void ASTDeclReader::VisitUnresolvedUsingTypenameDecl(
1642                                                UnresolvedUsingTypenameDecl *D) {
1643   VisitTypeDecl(D);
1644   D->TypenameLocation = ReadSourceLocation();
1645   D->QualifierLoc = Record.readNestedNameSpecifierLoc();
1646   D->EllipsisLoc = ReadSourceLocation();
1647   mergeMergeable(D);
1648 }
1649 
1650 void ASTDeclReader::ReadCXXDefinitionData(
1651     struct CXXRecordDecl::DefinitionData &Data, const CXXRecordDecl *D) {
1652   // Note: the caller has deserialized the IsLambda bit already.
1653   Data.UserDeclaredConstructor = Record.readInt();
1654   Data.UserDeclaredSpecialMembers = Record.readInt();
1655   Data.Aggregate = Record.readInt();
1656   Data.PlainOldData = Record.readInt();
1657   Data.Empty = Record.readInt();
1658   Data.Polymorphic = Record.readInt();
1659   Data.Abstract = Record.readInt();
1660   Data.IsStandardLayout = Record.readInt();
1661   Data.IsCXX11StandardLayout = Record.readInt();
1662   Data.HasBasesWithFields = Record.readInt();
1663   Data.HasBasesWithNonStaticDataMembers = Record.readInt();
1664   Data.HasPrivateFields = Record.readInt();
1665   Data.HasProtectedFields = Record.readInt();
1666   Data.HasPublicFields = Record.readInt();
1667   Data.HasMutableFields = Record.readInt();
1668   Data.HasVariantMembers = Record.readInt();
1669   Data.HasOnlyCMembers = Record.readInt();
1670   Data.HasInClassInitializer = Record.readInt();
1671   Data.HasUninitializedReferenceMember = Record.readInt();
1672   Data.HasUninitializedFields = Record.readInt();
1673   Data.HasInheritedConstructor = Record.readInt();
1674   Data.HasInheritedAssignment = Record.readInt();
1675   Data.NeedOverloadResolutionForCopyConstructor = Record.readInt();
1676   Data.NeedOverloadResolutionForMoveConstructor = Record.readInt();
1677   Data.NeedOverloadResolutionForMoveAssignment = Record.readInt();
1678   Data.NeedOverloadResolutionForDestructor = Record.readInt();
1679   Data.DefaultedCopyConstructorIsDeleted = Record.readInt();
1680   Data.DefaultedMoveConstructorIsDeleted = Record.readInt();
1681   Data.DefaultedMoveAssignmentIsDeleted = Record.readInt();
1682   Data.DefaultedDestructorIsDeleted = Record.readInt();
1683   Data.HasTrivialSpecialMembers = Record.readInt();
1684   Data.HasTrivialSpecialMembersForCall = Record.readInt();
1685   Data.DeclaredNonTrivialSpecialMembers = Record.readInt();
1686   Data.DeclaredNonTrivialSpecialMembersForCall = Record.readInt();
1687   Data.HasIrrelevantDestructor = Record.readInt();
1688   Data.HasConstexprNonCopyMoveConstructor = Record.readInt();
1689   Data.HasDefaultedDefaultConstructor = Record.readInt();
1690   Data.DefaultedDefaultConstructorIsConstexpr = Record.readInt();
1691   Data.HasConstexprDefaultConstructor = Record.readInt();
1692   Data.HasNonLiteralTypeFieldsOrBases = Record.readInt();
1693   Data.ComputedVisibleConversions = Record.readInt();
1694   Data.UserProvidedDefaultConstructor = Record.readInt();
1695   Data.DeclaredSpecialMembers = Record.readInt();
1696   Data.ImplicitCopyConstructorCanHaveConstParamForVBase = Record.readInt();
1697   Data.ImplicitCopyConstructorCanHaveConstParamForNonVBase = Record.readInt();
1698   Data.ImplicitCopyAssignmentHasConstParam = Record.readInt();
1699   Data.HasDeclaredCopyConstructorWithConstParam = Record.readInt();
1700   Data.HasDeclaredCopyAssignmentWithConstParam = Record.readInt();
1701   Data.ODRHash = Record.readInt();
1702   Data.HasODRHash = true;
1703 
1704   if (Record.readInt())
1705     Reader.DefinitionSource[D] = Loc.F->Kind == ModuleKind::MK_MainFile;
1706 
1707   Data.NumBases = Record.readInt();
1708   if (Data.NumBases)
1709     Data.Bases = ReadGlobalOffset();
1710   Data.NumVBases = Record.readInt();
1711   if (Data.NumVBases)
1712     Data.VBases = ReadGlobalOffset();
1713 
1714   Record.readUnresolvedSet(Data.Conversions);
1715   Record.readUnresolvedSet(Data.VisibleConversions);
1716   assert(Data.Definition && "Data.Definition should be already set!");
1717   Data.FirstFriend = ReadDeclID();
1718 
1719   if (Data.IsLambda) {
1720     using Capture = LambdaCapture;
1721 
1722     auto &Lambda = static_cast<CXXRecordDecl::LambdaDefinitionData &>(Data);
1723     Lambda.Dependent = Record.readInt();
1724     Lambda.IsGenericLambda = Record.readInt();
1725     Lambda.CaptureDefault = Record.readInt();
1726     Lambda.NumCaptures = Record.readInt();
1727     Lambda.NumExplicitCaptures = Record.readInt();
1728     Lambda.ManglingNumber = Record.readInt();
1729     Lambda.ContextDecl = ReadDeclID();
1730     Lambda.Captures = (Capture *)Reader.getContext().Allocate(
1731         sizeof(Capture) * Lambda.NumCaptures);
1732     Capture *ToCapture = Lambda.Captures;
1733     Lambda.MethodTyInfo = GetTypeSourceInfo();
1734     for (unsigned I = 0, N = Lambda.NumCaptures; I != N; ++I) {
1735       SourceLocation Loc = ReadSourceLocation();
1736       bool IsImplicit = Record.readInt();
1737       auto Kind = static_cast<LambdaCaptureKind>(Record.readInt());
1738       switch (Kind) {
1739       case LCK_StarThis:
1740       case LCK_This:
1741       case LCK_VLAType:
1742         *ToCapture++ = Capture(Loc, IsImplicit, Kind, nullptr,SourceLocation());
1743         break;
1744       case LCK_ByCopy:
1745       case LCK_ByRef:
1746         auto *Var = ReadDeclAs<VarDecl>();
1747         SourceLocation EllipsisLoc = ReadSourceLocation();
1748         *ToCapture++ = Capture(Loc, IsImplicit, Kind, Var, EllipsisLoc);
1749         break;
1750       }
1751     }
1752   }
1753 }
1754 
1755 void ASTDeclReader::MergeDefinitionData(
1756     CXXRecordDecl *D, struct CXXRecordDecl::DefinitionData &&MergeDD) {
1757   assert(D->DefinitionData &&
1758          "merging class definition into non-definition");
1759   auto &DD = *D->DefinitionData;
1760 
1761   if (DD.Definition != MergeDD.Definition) {
1762     // Track that we merged the definitions.
1763     Reader.MergedDeclContexts.insert(std::make_pair(MergeDD.Definition,
1764                                                     DD.Definition));
1765     Reader.PendingDefinitions.erase(MergeDD.Definition);
1766     MergeDD.Definition->setCompleteDefinition(false);
1767     Reader.mergeDefinitionVisibility(DD.Definition, MergeDD.Definition);
1768     assert(Reader.Lookups.find(MergeDD.Definition) == Reader.Lookups.end() &&
1769            "already loaded pending lookups for merged definition");
1770   }
1771 
1772   auto PFDI = Reader.PendingFakeDefinitionData.find(&DD);
1773   if (PFDI != Reader.PendingFakeDefinitionData.end() &&
1774       PFDI->second == ASTReader::PendingFakeDefinitionKind::Fake) {
1775     // We faked up this definition data because we found a class for which we'd
1776     // not yet loaded the definition. Replace it with the real thing now.
1777     assert(!DD.IsLambda && !MergeDD.IsLambda && "faked up lambda definition?");
1778     PFDI->second = ASTReader::PendingFakeDefinitionKind::FakeLoaded;
1779 
1780     // Don't change which declaration is the definition; that is required
1781     // to be invariant once we select it.
1782     auto *Def = DD.Definition;
1783     DD = std::move(MergeDD);
1784     DD.Definition = Def;
1785     return;
1786   }
1787 
1788   // FIXME: Move this out into a .def file?
1789   bool DetectedOdrViolation = false;
1790 #define OR_FIELD(Field) DD.Field |= MergeDD.Field;
1791 #define MATCH_FIELD(Field) \
1792     DetectedOdrViolation |= DD.Field != MergeDD.Field; \
1793     OR_FIELD(Field)
1794   MATCH_FIELD(UserDeclaredConstructor)
1795   MATCH_FIELD(UserDeclaredSpecialMembers)
1796   MATCH_FIELD(Aggregate)
1797   MATCH_FIELD(PlainOldData)
1798   MATCH_FIELD(Empty)
1799   MATCH_FIELD(Polymorphic)
1800   MATCH_FIELD(Abstract)
1801   MATCH_FIELD(IsStandardLayout)
1802   MATCH_FIELD(IsCXX11StandardLayout)
1803   MATCH_FIELD(HasBasesWithFields)
1804   MATCH_FIELD(HasBasesWithNonStaticDataMembers)
1805   MATCH_FIELD(HasPrivateFields)
1806   MATCH_FIELD(HasProtectedFields)
1807   MATCH_FIELD(HasPublicFields)
1808   MATCH_FIELD(HasMutableFields)
1809   MATCH_FIELD(HasVariantMembers)
1810   MATCH_FIELD(HasOnlyCMembers)
1811   MATCH_FIELD(HasInClassInitializer)
1812   MATCH_FIELD(HasUninitializedReferenceMember)
1813   MATCH_FIELD(HasUninitializedFields)
1814   MATCH_FIELD(HasInheritedConstructor)
1815   MATCH_FIELD(HasInheritedAssignment)
1816   MATCH_FIELD(NeedOverloadResolutionForCopyConstructor)
1817   MATCH_FIELD(NeedOverloadResolutionForMoveConstructor)
1818   MATCH_FIELD(NeedOverloadResolutionForMoveAssignment)
1819   MATCH_FIELD(NeedOverloadResolutionForDestructor)
1820   MATCH_FIELD(DefaultedCopyConstructorIsDeleted)
1821   MATCH_FIELD(DefaultedMoveConstructorIsDeleted)
1822   MATCH_FIELD(DefaultedMoveAssignmentIsDeleted)
1823   MATCH_FIELD(DefaultedDestructorIsDeleted)
1824   OR_FIELD(HasTrivialSpecialMembers)
1825   OR_FIELD(HasTrivialSpecialMembersForCall)
1826   OR_FIELD(DeclaredNonTrivialSpecialMembers)
1827   OR_FIELD(DeclaredNonTrivialSpecialMembersForCall)
1828   MATCH_FIELD(HasIrrelevantDestructor)
1829   OR_FIELD(HasConstexprNonCopyMoveConstructor)
1830   OR_FIELD(HasDefaultedDefaultConstructor)
1831   MATCH_FIELD(DefaultedDefaultConstructorIsConstexpr)
1832   OR_FIELD(HasConstexprDefaultConstructor)
1833   MATCH_FIELD(HasNonLiteralTypeFieldsOrBases)
1834   // ComputedVisibleConversions is handled below.
1835   MATCH_FIELD(UserProvidedDefaultConstructor)
1836   OR_FIELD(DeclaredSpecialMembers)
1837   MATCH_FIELD(ImplicitCopyConstructorCanHaveConstParamForVBase)
1838   MATCH_FIELD(ImplicitCopyConstructorCanHaveConstParamForNonVBase)
1839   MATCH_FIELD(ImplicitCopyAssignmentHasConstParam)
1840   OR_FIELD(HasDeclaredCopyConstructorWithConstParam)
1841   OR_FIELD(HasDeclaredCopyAssignmentWithConstParam)
1842   MATCH_FIELD(IsLambda)
1843 #undef OR_FIELD
1844 #undef MATCH_FIELD
1845 
1846   if (DD.NumBases != MergeDD.NumBases || DD.NumVBases != MergeDD.NumVBases)
1847     DetectedOdrViolation = true;
1848   // FIXME: Issue a diagnostic if the base classes don't match when we come
1849   // to lazily load them.
1850 
1851   // FIXME: Issue a diagnostic if the list of conversion functions doesn't
1852   // match when we come to lazily load them.
1853   if (MergeDD.ComputedVisibleConversions && !DD.ComputedVisibleConversions) {
1854     DD.VisibleConversions = std::move(MergeDD.VisibleConversions);
1855     DD.ComputedVisibleConversions = true;
1856   }
1857 
1858   // FIXME: Issue a diagnostic if FirstFriend doesn't match when we come to
1859   // lazily load it.
1860 
1861   if (DD.IsLambda) {
1862     // FIXME: ODR-checking for merging lambdas (this happens, for instance,
1863     // when they occur within the body of a function template specialization).
1864   }
1865 
1866   if (D->getODRHash() != MergeDD.ODRHash) {
1867     DetectedOdrViolation = true;
1868   }
1869 
1870   if (DetectedOdrViolation)
1871     Reader.PendingOdrMergeFailures[DD.Definition].push_back(
1872         {MergeDD.Definition, &MergeDD});
1873 }
1874 
1875 void ASTDeclReader::ReadCXXRecordDefinition(CXXRecordDecl *D, bool Update) {
1876   struct CXXRecordDecl::DefinitionData *DD;
1877   ASTContext &C = Reader.getContext();
1878 
1879   // Determine whether this is a lambda closure type, so that we can
1880   // allocate the appropriate DefinitionData structure.
1881   bool IsLambda = Record.readInt();
1882   if (IsLambda)
1883     DD = new (C) CXXRecordDecl::LambdaDefinitionData(D, nullptr, false, false,
1884                                                      LCD_None);
1885   else
1886     DD = new (C) struct CXXRecordDecl::DefinitionData(D);
1887 
1888   CXXRecordDecl *Canon = D->getCanonicalDecl();
1889   // Set decl definition data before reading it, so that during deserialization
1890   // when we read CXXRecordDecl, it already has definition data and we don't
1891   // set fake one.
1892   if (!Canon->DefinitionData)
1893     Canon->DefinitionData = DD;
1894   D->DefinitionData = Canon->DefinitionData;
1895   ReadCXXDefinitionData(*DD, D);
1896 
1897   // We might already have a different definition for this record. This can
1898   // happen either because we're reading an update record, or because we've
1899   // already done some merging. Either way, just merge into it.
1900   if (Canon->DefinitionData != DD) {
1901     MergeDefinitionData(Canon, std::move(*DD));
1902     return;
1903   }
1904 
1905   // Mark this declaration as being a definition.
1906   D->setCompleteDefinition(true);
1907 
1908   // If this is not the first declaration or is an update record, we can have
1909   // other redeclarations already. Make a note that we need to propagate the
1910   // DefinitionData pointer onto them.
1911   if (Update || Canon != D)
1912     Reader.PendingDefinitions.insert(D);
1913 }
1914 
1915 ASTDeclReader::RedeclarableResult
1916 ASTDeclReader::VisitCXXRecordDeclImpl(CXXRecordDecl *D) {
1917   RedeclarableResult Redecl = VisitRecordDeclImpl(D);
1918 
1919   ASTContext &C = Reader.getContext();
1920 
1921   enum CXXRecKind {
1922     CXXRecNotTemplate = 0, CXXRecTemplate, CXXRecMemberSpecialization
1923   };
1924   switch ((CXXRecKind)Record.readInt()) {
1925   case CXXRecNotTemplate:
1926     // Merged when we merge the folding set entry in the primary template.
1927     if (!isa<ClassTemplateSpecializationDecl>(D))
1928       mergeRedeclarable(D, Redecl);
1929     break;
1930   case CXXRecTemplate: {
1931     // Merged when we merge the template.
1932     auto *Template = ReadDeclAs<ClassTemplateDecl>();
1933     D->TemplateOrInstantiation = Template;
1934     if (!Template->getTemplatedDecl()) {
1935       // We've not actually loaded the ClassTemplateDecl yet, because we're
1936       // currently being loaded as its pattern. Rely on it to set up our
1937       // TypeForDecl (see VisitClassTemplateDecl).
1938       //
1939       // Beware: we do not yet know our canonical declaration, and may still
1940       // get merged once the surrounding class template has got off the ground.
1941       DeferredTypeID = 0;
1942     }
1943     break;
1944   }
1945   case CXXRecMemberSpecialization: {
1946     auto *RD = ReadDeclAs<CXXRecordDecl>();
1947     auto TSK = (TemplateSpecializationKind)Record.readInt();
1948     SourceLocation POI = ReadSourceLocation();
1949     MemberSpecializationInfo *MSI = new (C) MemberSpecializationInfo(RD, TSK);
1950     MSI->setPointOfInstantiation(POI);
1951     D->TemplateOrInstantiation = MSI;
1952     mergeRedeclarable(D, Redecl);
1953     break;
1954   }
1955   }
1956 
1957   bool WasDefinition = Record.readInt();
1958   if (WasDefinition)
1959     ReadCXXRecordDefinition(D, /*Update*/false);
1960   else
1961     // Propagate DefinitionData pointer from the canonical declaration.
1962     D->DefinitionData = D->getCanonicalDecl()->DefinitionData;
1963 
1964   // Lazily load the key function to avoid deserializing every method so we can
1965   // compute it.
1966   if (WasDefinition) {
1967     DeclID KeyFn = ReadDeclID();
1968     if (KeyFn && D->isCompleteDefinition())
1969       // FIXME: This is wrong for the ARM ABI, where some other module may have
1970       // made this function no longer be a key function. We need an update
1971       // record or similar for that case.
1972       C.KeyFunctions[D] = KeyFn;
1973   }
1974 
1975   return Redecl;
1976 }
1977 
1978 void ASTDeclReader::VisitCXXDeductionGuideDecl(CXXDeductionGuideDecl *D) {
1979   D->setExplicitSpecifier(Record.readExplicitSpec());
1980   VisitFunctionDecl(D);
1981   D->setIsCopyDeductionCandidate(Record.readInt());
1982 }
1983 
1984 void ASTDeclReader::VisitCXXMethodDecl(CXXMethodDecl *D) {
1985   VisitFunctionDecl(D);
1986 
1987   unsigned NumOverridenMethods = Record.readInt();
1988   if (D->isCanonicalDecl()) {
1989     while (NumOverridenMethods--) {
1990       // Avoid invariant checking of CXXMethodDecl::addOverriddenMethod,
1991       // MD may be initializing.
1992       if (auto *MD = ReadDeclAs<CXXMethodDecl>())
1993         Reader.getContext().addOverriddenMethod(D, MD->getCanonicalDecl());
1994     }
1995   } else {
1996     // We don't care about which declarations this used to override; we get
1997     // the relevant information from the canonical declaration.
1998     Record.skipInts(NumOverridenMethods);
1999   }
2000 }
2001 
2002 void ASTDeclReader::VisitCXXConstructorDecl(CXXConstructorDecl *D) {
2003   // We need the inherited constructor information to merge the declaration,
2004   // so we have to read it before we call VisitCXXMethodDecl.
2005   D->setExplicitSpecifier(Record.readExplicitSpec());
2006   if (D->isInheritingConstructor()) {
2007     auto *Shadow = ReadDeclAs<ConstructorUsingShadowDecl>();
2008     auto *Ctor = ReadDeclAs<CXXConstructorDecl>();
2009     *D->getTrailingObjects<InheritedConstructor>() =
2010         InheritedConstructor(Shadow, Ctor);
2011   }
2012 
2013   VisitCXXMethodDecl(D);
2014 }
2015 
2016 void ASTDeclReader::VisitCXXDestructorDecl(CXXDestructorDecl *D) {
2017   VisitCXXMethodDecl(D);
2018 
2019   if (auto *OperatorDelete = ReadDeclAs<FunctionDecl>()) {
2020     CXXDestructorDecl *Canon = D->getCanonicalDecl();
2021     auto *ThisArg = Record.readExpr();
2022     // FIXME: Check consistency if we have an old and new operator delete.
2023     if (!Canon->OperatorDelete) {
2024       Canon->OperatorDelete = OperatorDelete;
2025       Canon->OperatorDeleteThisArg = ThisArg;
2026     }
2027   }
2028 }
2029 
2030 void ASTDeclReader::VisitCXXConversionDecl(CXXConversionDecl *D) {
2031   D->setExplicitSpecifier(Record.readExplicitSpec());
2032   VisitCXXMethodDecl(D);
2033 }
2034 
2035 void ASTDeclReader::VisitImportDecl(ImportDecl *D) {
2036   VisitDecl(D);
2037   D->ImportedAndComplete.setPointer(readModule());
2038   D->ImportedAndComplete.setInt(Record.readInt());
2039   auto *StoredLocs = D->getTrailingObjects<SourceLocation>();
2040   for (unsigned I = 0, N = Record.back(); I != N; ++I)
2041     StoredLocs[I] = ReadSourceLocation();
2042   Record.skipInts(1); // The number of stored source locations.
2043 }
2044 
2045 void ASTDeclReader::VisitAccessSpecDecl(AccessSpecDecl *D) {
2046   VisitDecl(D);
2047   D->setColonLoc(ReadSourceLocation());
2048 }
2049 
2050 void ASTDeclReader::VisitFriendDecl(FriendDecl *D) {
2051   VisitDecl(D);
2052   if (Record.readInt()) // hasFriendDecl
2053     D->Friend = ReadDeclAs<NamedDecl>();
2054   else
2055     D->Friend = GetTypeSourceInfo();
2056   for (unsigned i = 0; i != D->NumTPLists; ++i)
2057     D->getTrailingObjects<TemplateParameterList *>()[i] =
2058         Record.readTemplateParameterList();
2059   D->NextFriend = ReadDeclID();
2060   D->UnsupportedFriend = (Record.readInt() != 0);
2061   D->FriendLoc = ReadSourceLocation();
2062 }
2063 
2064 void ASTDeclReader::VisitFriendTemplateDecl(FriendTemplateDecl *D) {
2065   VisitDecl(D);
2066   unsigned NumParams = Record.readInt();
2067   D->NumParams = NumParams;
2068   D->Params = new TemplateParameterList*[NumParams];
2069   for (unsigned i = 0; i != NumParams; ++i)
2070     D->Params[i] = Record.readTemplateParameterList();
2071   if (Record.readInt()) // HasFriendDecl
2072     D->Friend = ReadDeclAs<NamedDecl>();
2073   else
2074     D->Friend = GetTypeSourceInfo();
2075   D->FriendLoc = ReadSourceLocation();
2076 }
2077 
2078 DeclID ASTDeclReader::VisitTemplateDecl(TemplateDecl *D) {
2079   VisitNamedDecl(D);
2080 
2081   DeclID PatternID = ReadDeclID();
2082   auto *TemplatedDecl = cast_or_null<NamedDecl>(Reader.GetDecl(PatternID));
2083   TemplateParameterList *TemplateParams = Record.readTemplateParameterList();
2084   // FIXME handle associated constraints
2085   D->init(TemplatedDecl, TemplateParams);
2086 
2087   return PatternID;
2088 }
2089 
2090 ASTDeclReader::RedeclarableResult
2091 ASTDeclReader::VisitRedeclarableTemplateDecl(RedeclarableTemplateDecl *D) {
2092   RedeclarableResult Redecl = VisitRedeclarable(D);
2093 
2094   // Make sure we've allocated the Common pointer first. We do this before
2095   // VisitTemplateDecl so that getCommonPtr() can be used during initialization.
2096   RedeclarableTemplateDecl *CanonD = D->getCanonicalDecl();
2097   if (!CanonD->Common) {
2098     CanonD->Common = CanonD->newCommon(Reader.getContext());
2099     Reader.PendingDefinitions.insert(CanonD);
2100   }
2101   D->Common = CanonD->Common;
2102 
2103   // If this is the first declaration of the template, fill in the information
2104   // for the 'common' pointer.
2105   if (ThisDeclID == Redecl.getFirstID()) {
2106     if (auto *RTD = ReadDeclAs<RedeclarableTemplateDecl>()) {
2107       assert(RTD->getKind() == D->getKind() &&
2108              "InstantiatedFromMemberTemplate kind mismatch");
2109       D->setInstantiatedFromMemberTemplate(RTD);
2110       if (Record.readInt())
2111         D->setMemberSpecialization();
2112     }
2113   }
2114 
2115   DeclID PatternID = VisitTemplateDecl(D);
2116   D->IdentifierNamespace = Record.readInt();
2117 
2118   mergeRedeclarable(D, Redecl, PatternID);
2119 
2120   // If we merged the template with a prior declaration chain, merge the common
2121   // pointer.
2122   // FIXME: Actually merge here, don't just overwrite.
2123   D->Common = D->getCanonicalDecl()->Common;
2124 
2125   return Redecl;
2126 }
2127 
2128 void ASTDeclReader::VisitClassTemplateDecl(ClassTemplateDecl *D) {
2129   RedeclarableResult Redecl = VisitRedeclarableTemplateDecl(D);
2130 
2131   if (ThisDeclID == Redecl.getFirstID()) {
2132     // This ClassTemplateDecl owns a CommonPtr; read it to keep track of all of
2133     // the specializations.
2134     SmallVector<serialization::DeclID, 32> SpecIDs;
2135     ReadDeclIDList(SpecIDs);
2136     ASTDeclReader::AddLazySpecializations(D, SpecIDs);
2137   }
2138 
2139   if (D->getTemplatedDecl()->TemplateOrInstantiation) {
2140     // We were loaded before our templated declaration was. We've not set up
2141     // its corresponding type yet (see VisitCXXRecordDeclImpl), so reconstruct
2142     // it now.
2143     Reader.getContext().getInjectedClassNameType(
2144         D->getTemplatedDecl(), D->getInjectedClassNameSpecialization());
2145   }
2146 }
2147 
2148 void ASTDeclReader::VisitBuiltinTemplateDecl(BuiltinTemplateDecl *D) {
2149   llvm_unreachable("BuiltinTemplates are not serialized");
2150 }
2151 
2152 /// TODO: Unify with ClassTemplateDecl version?
2153 ///       May require unifying ClassTemplateDecl and
2154 ///        VarTemplateDecl beyond TemplateDecl...
2155 void ASTDeclReader::VisitVarTemplateDecl(VarTemplateDecl *D) {
2156   RedeclarableResult Redecl = VisitRedeclarableTemplateDecl(D);
2157 
2158   if (ThisDeclID == Redecl.getFirstID()) {
2159     // This VarTemplateDecl owns a CommonPtr; read it to keep track of all of
2160     // the specializations.
2161     SmallVector<serialization::DeclID, 32> SpecIDs;
2162     ReadDeclIDList(SpecIDs);
2163     ASTDeclReader::AddLazySpecializations(D, SpecIDs);
2164   }
2165 }
2166 
2167 ASTDeclReader::RedeclarableResult
2168 ASTDeclReader::VisitClassTemplateSpecializationDeclImpl(
2169     ClassTemplateSpecializationDecl *D) {
2170   RedeclarableResult Redecl = VisitCXXRecordDeclImpl(D);
2171 
2172   ASTContext &C = Reader.getContext();
2173   if (Decl *InstD = ReadDecl()) {
2174     if (auto *CTD = dyn_cast<ClassTemplateDecl>(InstD)) {
2175       D->SpecializedTemplate = CTD;
2176     } else {
2177       SmallVector<TemplateArgument, 8> TemplArgs;
2178       Record.readTemplateArgumentList(TemplArgs);
2179       TemplateArgumentList *ArgList
2180         = TemplateArgumentList::CreateCopy(C, TemplArgs);
2181       auto *PS =
2182           new (C) ClassTemplateSpecializationDecl::
2183                                              SpecializedPartialSpecialization();
2184       PS->PartialSpecialization
2185           = cast<ClassTemplatePartialSpecializationDecl>(InstD);
2186       PS->TemplateArgs = ArgList;
2187       D->SpecializedTemplate = PS;
2188     }
2189   }
2190 
2191   SmallVector<TemplateArgument, 8> TemplArgs;
2192   Record.readTemplateArgumentList(TemplArgs, /*Canonicalize*/ true);
2193   D->TemplateArgs = TemplateArgumentList::CreateCopy(C, TemplArgs);
2194   D->PointOfInstantiation = ReadSourceLocation();
2195   D->SpecializationKind = (TemplateSpecializationKind)Record.readInt();
2196 
2197   bool writtenAsCanonicalDecl = Record.readInt();
2198   if (writtenAsCanonicalDecl) {
2199     auto *CanonPattern = ReadDeclAs<ClassTemplateDecl>();
2200     if (D->isCanonicalDecl()) { // It's kept in the folding set.
2201       // Set this as, or find, the canonical declaration for this specialization
2202       ClassTemplateSpecializationDecl *CanonSpec;
2203       if (auto *Partial = dyn_cast<ClassTemplatePartialSpecializationDecl>(D)) {
2204         CanonSpec = CanonPattern->getCommonPtr()->PartialSpecializations
2205             .GetOrInsertNode(Partial);
2206       } else {
2207         CanonSpec =
2208             CanonPattern->getCommonPtr()->Specializations.GetOrInsertNode(D);
2209       }
2210       // If there was already a canonical specialization, merge into it.
2211       if (CanonSpec != D) {
2212         mergeRedeclarable<TagDecl>(D, CanonSpec, Redecl);
2213 
2214         // This declaration might be a definition. Merge with any existing
2215         // definition.
2216         if (auto *DDD = D->DefinitionData) {
2217           if (CanonSpec->DefinitionData)
2218             MergeDefinitionData(CanonSpec, std::move(*DDD));
2219           else
2220             CanonSpec->DefinitionData = D->DefinitionData;
2221         }
2222         D->DefinitionData = CanonSpec->DefinitionData;
2223       }
2224     }
2225   }
2226 
2227   // Explicit info.
2228   if (TypeSourceInfo *TyInfo = GetTypeSourceInfo()) {
2229     auto *ExplicitInfo =
2230         new (C) ClassTemplateSpecializationDecl::ExplicitSpecializationInfo;
2231     ExplicitInfo->TypeAsWritten = TyInfo;
2232     ExplicitInfo->ExternLoc = ReadSourceLocation();
2233     ExplicitInfo->TemplateKeywordLoc = ReadSourceLocation();
2234     D->ExplicitInfo = ExplicitInfo;
2235   }
2236 
2237   return Redecl;
2238 }
2239 
2240 void ASTDeclReader::VisitClassTemplatePartialSpecializationDecl(
2241                                     ClassTemplatePartialSpecializationDecl *D) {
2242   RedeclarableResult Redecl = VisitClassTemplateSpecializationDeclImpl(D);
2243 
2244   D->TemplateParams = Record.readTemplateParameterList();
2245   D->ArgsAsWritten = Record.readASTTemplateArgumentListInfo();
2246 
2247   // These are read/set from/to the first declaration.
2248   if (ThisDeclID == Redecl.getFirstID()) {
2249     D->InstantiatedFromMember.setPointer(
2250       ReadDeclAs<ClassTemplatePartialSpecializationDecl>());
2251     D->InstantiatedFromMember.setInt(Record.readInt());
2252   }
2253 }
2254 
2255 void ASTDeclReader::VisitClassScopeFunctionSpecializationDecl(
2256                                     ClassScopeFunctionSpecializationDecl *D) {
2257   VisitDecl(D);
2258   D->Specialization = ReadDeclAs<CXXMethodDecl>();
2259   if (Record.readInt())
2260     D->TemplateArgs = Record.readASTTemplateArgumentListInfo();
2261 }
2262 
2263 void ASTDeclReader::VisitFunctionTemplateDecl(FunctionTemplateDecl *D) {
2264   RedeclarableResult Redecl = VisitRedeclarableTemplateDecl(D);
2265 
2266   if (ThisDeclID == Redecl.getFirstID()) {
2267     // This FunctionTemplateDecl owns a CommonPtr; read it.
2268     SmallVector<serialization::DeclID, 32> SpecIDs;
2269     ReadDeclIDList(SpecIDs);
2270     ASTDeclReader::AddLazySpecializations(D, SpecIDs);
2271   }
2272 }
2273 
2274 /// TODO: Unify with ClassTemplateSpecializationDecl version?
2275 ///       May require unifying ClassTemplate(Partial)SpecializationDecl and
2276 ///        VarTemplate(Partial)SpecializationDecl with a new data
2277 ///        structure Template(Partial)SpecializationDecl, and
2278 ///        using Template(Partial)SpecializationDecl as input type.
2279 ASTDeclReader::RedeclarableResult
2280 ASTDeclReader::VisitVarTemplateSpecializationDeclImpl(
2281     VarTemplateSpecializationDecl *D) {
2282   RedeclarableResult Redecl = VisitVarDeclImpl(D);
2283 
2284   ASTContext &C = Reader.getContext();
2285   if (Decl *InstD = ReadDecl()) {
2286     if (auto *VTD = dyn_cast<VarTemplateDecl>(InstD)) {
2287       D->SpecializedTemplate = VTD;
2288     } else {
2289       SmallVector<TemplateArgument, 8> TemplArgs;
2290       Record.readTemplateArgumentList(TemplArgs);
2291       TemplateArgumentList *ArgList = TemplateArgumentList::CreateCopy(
2292           C, TemplArgs);
2293       auto *PS =
2294           new (C)
2295           VarTemplateSpecializationDecl::SpecializedPartialSpecialization();
2296       PS->PartialSpecialization =
2297           cast<VarTemplatePartialSpecializationDecl>(InstD);
2298       PS->TemplateArgs = ArgList;
2299       D->SpecializedTemplate = PS;
2300     }
2301   }
2302 
2303   // Explicit info.
2304   if (TypeSourceInfo *TyInfo = GetTypeSourceInfo()) {
2305     auto *ExplicitInfo =
2306         new (C) VarTemplateSpecializationDecl::ExplicitSpecializationInfo;
2307     ExplicitInfo->TypeAsWritten = TyInfo;
2308     ExplicitInfo->ExternLoc = ReadSourceLocation();
2309     ExplicitInfo->TemplateKeywordLoc = ReadSourceLocation();
2310     D->ExplicitInfo = ExplicitInfo;
2311   }
2312 
2313   SmallVector<TemplateArgument, 8> TemplArgs;
2314   Record.readTemplateArgumentList(TemplArgs, /*Canonicalize*/ true);
2315   D->TemplateArgs = TemplateArgumentList::CreateCopy(C, TemplArgs);
2316   D->PointOfInstantiation = ReadSourceLocation();
2317   D->SpecializationKind = (TemplateSpecializationKind)Record.readInt();
2318   D->IsCompleteDefinition = Record.readInt();
2319 
2320   bool writtenAsCanonicalDecl = Record.readInt();
2321   if (writtenAsCanonicalDecl) {
2322     auto *CanonPattern = ReadDeclAs<VarTemplateDecl>();
2323     if (D->isCanonicalDecl()) { // It's kept in the folding set.
2324       // FIXME: If it's already present, merge it.
2325       if (auto *Partial = dyn_cast<VarTemplatePartialSpecializationDecl>(D)) {
2326         CanonPattern->getCommonPtr()->PartialSpecializations
2327             .GetOrInsertNode(Partial);
2328       } else {
2329         CanonPattern->getCommonPtr()->Specializations.GetOrInsertNode(D);
2330       }
2331     }
2332   }
2333 
2334   return Redecl;
2335 }
2336 
2337 /// TODO: Unify with ClassTemplatePartialSpecializationDecl version?
2338 ///       May require unifying ClassTemplate(Partial)SpecializationDecl and
2339 ///        VarTemplate(Partial)SpecializationDecl with a new data
2340 ///        structure Template(Partial)SpecializationDecl, and
2341 ///        using Template(Partial)SpecializationDecl as input type.
2342 void ASTDeclReader::VisitVarTemplatePartialSpecializationDecl(
2343     VarTemplatePartialSpecializationDecl *D) {
2344   RedeclarableResult Redecl = VisitVarTemplateSpecializationDeclImpl(D);
2345 
2346   D->TemplateParams = Record.readTemplateParameterList();
2347   D->ArgsAsWritten = Record.readASTTemplateArgumentListInfo();
2348 
2349   // These are read/set from/to the first declaration.
2350   if (ThisDeclID == Redecl.getFirstID()) {
2351     D->InstantiatedFromMember.setPointer(
2352         ReadDeclAs<VarTemplatePartialSpecializationDecl>());
2353     D->InstantiatedFromMember.setInt(Record.readInt());
2354   }
2355 }
2356 
2357 void ASTDeclReader::VisitTemplateTypeParmDecl(TemplateTypeParmDecl *D) {
2358   VisitTypeDecl(D);
2359 
2360   D->setDeclaredWithTypename(Record.readInt());
2361 
2362   if (Record.readInt())
2363     D->setDefaultArgument(GetTypeSourceInfo());
2364 }
2365 
2366 void ASTDeclReader::VisitNonTypeTemplateParmDecl(NonTypeTemplateParmDecl *D) {
2367   VisitDeclaratorDecl(D);
2368   // TemplateParmPosition.
2369   D->setDepth(Record.readInt());
2370   D->setPosition(Record.readInt());
2371   if (D->isExpandedParameterPack()) {
2372     auto TypesAndInfos =
2373         D->getTrailingObjects<std::pair<QualType, TypeSourceInfo *>>();
2374     for (unsigned I = 0, N = D->getNumExpansionTypes(); I != N; ++I) {
2375       new (&TypesAndInfos[I].first) QualType(Record.readType());
2376       TypesAndInfos[I].second = GetTypeSourceInfo();
2377     }
2378   } else {
2379     // Rest of NonTypeTemplateParmDecl.
2380     D->ParameterPack = Record.readInt();
2381     if (Record.readInt())
2382       D->setDefaultArgument(Record.readExpr());
2383   }
2384 }
2385 
2386 void ASTDeclReader::VisitTemplateTemplateParmDecl(TemplateTemplateParmDecl *D) {
2387   VisitTemplateDecl(D);
2388   // TemplateParmPosition.
2389   D->setDepth(Record.readInt());
2390   D->setPosition(Record.readInt());
2391   if (D->isExpandedParameterPack()) {
2392     auto **Data = D->getTrailingObjects<TemplateParameterList *>();
2393     for (unsigned I = 0, N = D->getNumExpansionTemplateParameters();
2394          I != N; ++I)
2395       Data[I] = Record.readTemplateParameterList();
2396   } else {
2397     // Rest of TemplateTemplateParmDecl.
2398     D->ParameterPack = Record.readInt();
2399     if (Record.readInt())
2400       D->setDefaultArgument(Reader.getContext(),
2401                             Record.readTemplateArgumentLoc());
2402   }
2403 }
2404 
2405 void ASTDeclReader::VisitTypeAliasTemplateDecl(TypeAliasTemplateDecl *D) {
2406   VisitRedeclarableTemplateDecl(D);
2407 }
2408 
2409 void ASTDeclReader::VisitStaticAssertDecl(StaticAssertDecl *D) {
2410   VisitDecl(D);
2411   D->AssertExprAndFailed.setPointer(Record.readExpr());
2412   D->AssertExprAndFailed.setInt(Record.readInt());
2413   D->Message = cast_or_null<StringLiteral>(Record.readExpr());
2414   D->RParenLoc = ReadSourceLocation();
2415 }
2416 
2417 void ASTDeclReader::VisitEmptyDecl(EmptyDecl *D) {
2418   VisitDecl(D);
2419 }
2420 
2421 std::pair<uint64_t, uint64_t>
2422 ASTDeclReader::VisitDeclContext(DeclContext *DC) {
2423   uint64_t LexicalOffset = ReadLocalOffset();
2424   uint64_t VisibleOffset = ReadLocalOffset();
2425   return std::make_pair(LexicalOffset, VisibleOffset);
2426 }
2427 
2428 template <typename T>
2429 ASTDeclReader::RedeclarableResult
2430 ASTDeclReader::VisitRedeclarable(Redeclarable<T> *D) {
2431   DeclID FirstDeclID = ReadDeclID();
2432   Decl *MergeWith = nullptr;
2433 
2434   bool IsKeyDecl = ThisDeclID == FirstDeclID;
2435   bool IsFirstLocalDecl = false;
2436 
2437   uint64_t RedeclOffset = 0;
2438 
2439   // 0 indicates that this declaration was the only declaration of its entity,
2440   // and is used for space optimization.
2441   if (FirstDeclID == 0) {
2442     FirstDeclID = ThisDeclID;
2443     IsKeyDecl = true;
2444     IsFirstLocalDecl = true;
2445   } else if (unsigned N = Record.readInt()) {
2446     // This declaration was the first local declaration, but may have imported
2447     // other declarations.
2448     IsKeyDecl = N == 1;
2449     IsFirstLocalDecl = true;
2450 
2451     // We have some declarations that must be before us in our redeclaration
2452     // chain. Read them now, and remember that we ought to merge with one of
2453     // them.
2454     // FIXME: Provide a known merge target to the second and subsequent such
2455     // declaration.
2456     for (unsigned I = 0; I != N - 1; ++I)
2457       MergeWith = ReadDecl();
2458 
2459     RedeclOffset = ReadLocalOffset();
2460   } else {
2461     // This declaration was not the first local declaration. Read the first
2462     // local declaration now, to trigger the import of other redeclarations.
2463     (void)ReadDecl();
2464   }
2465 
2466   auto *FirstDecl = cast_or_null<T>(Reader.GetDecl(FirstDeclID));
2467   if (FirstDecl != D) {
2468     // We delay loading of the redeclaration chain to avoid deeply nested calls.
2469     // We temporarily set the first (canonical) declaration as the previous one
2470     // which is the one that matters and mark the real previous DeclID to be
2471     // loaded & attached later on.
2472     D->RedeclLink = Redeclarable<T>::PreviousDeclLink(FirstDecl);
2473     D->First = FirstDecl->getCanonicalDecl();
2474   }
2475 
2476   auto *DAsT = static_cast<T *>(D);
2477 
2478   // Note that we need to load local redeclarations of this decl and build a
2479   // decl chain for them. This must happen *after* we perform the preloading
2480   // above; this ensures that the redeclaration chain is built in the correct
2481   // order.
2482   if (IsFirstLocalDecl)
2483     Reader.PendingDeclChains.push_back(std::make_pair(DAsT, RedeclOffset));
2484 
2485   return RedeclarableResult(MergeWith, FirstDeclID, IsKeyDecl);
2486 }
2487 
2488 /// Attempts to merge the given declaration (D) with another declaration
2489 /// of the same entity.
2490 template<typename T>
2491 void ASTDeclReader::mergeRedeclarable(Redeclarable<T> *DBase,
2492                                       RedeclarableResult &Redecl,
2493                                       DeclID TemplatePatternID) {
2494   // If modules are not available, there is no reason to perform this merge.
2495   if (!Reader.getContext().getLangOpts().Modules)
2496     return;
2497 
2498   // If we're not the canonical declaration, we don't need to merge.
2499   if (!DBase->isFirstDecl())
2500     return;
2501 
2502   auto *D = static_cast<T *>(DBase);
2503 
2504   if (auto *Existing = Redecl.getKnownMergeTarget())
2505     // We already know of an existing declaration we should merge with.
2506     mergeRedeclarable(D, cast<T>(Existing), Redecl, TemplatePatternID);
2507   else if (FindExistingResult ExistingRes = findExisting(D))
2508     if (T *Existing = ExistingRes)
2509       mergeRedeclarable(D, Existing, Redecl, TemplatePatternID);
2510 }
2511 
2512 /// "Cast" to type T, asserting if we don't have an implicit conversion.
2513 /// We use this to put code in a template that will only be valid for certain
2514 /// instantiations.
2515 template<typename T> static T assert_cast(T t) { return t; }
2516 template<typename T> static T assert_cast(...) {
2517   llvm_unreachable("bad assert_cast");
2518 }
2519 
2520 /// Merge together the pattern declarations from two template
2521 /// declarations.
2522 void ASTDeclReader::mergeTemplatePattern(RedeclarableTemplateDecl *D,
2523                                          RedeclarableTemplateDecl *Existing,
2524                                          DeclID DsID, bool IsKeyDecl) {
2525   auto *DPattern = D->getTemplatedDecl();
2526   auto *ExistingPattern = Existing->getTemplatedDecl();
2527   RedeclarableResult Result(/*MergeWith*/ ExistingPattern,
2528                             DPattern->getCanonicalDecl()->getGlobalID(),
2529                             IsKeyDecl);
2530 
2531   if (auto *DClass = dyn_cast<CXXRecordDecl>(DPattern)) {
2532     // Merge with any existing definition.
2533     // FIXME: This is duplicated in several places. Refactor.
2534     auto *ExistingClass =
2535         cast<CXXRecordDecl>(ExistingPattern)->getCanonicalDecl();
2536     if (auto *DDD = DClass->DefinitionData) {
2537       if (ExistingClass->DefinitionData) {
2538         MergeDefinitionData(ExistingClass, std::move(*DDD));
2539       } else {
2540         ExistingClass->DefinitionData = DClass->DefinitionData;
2541         // We may have skipped this before because we thought that DClass
2542         // was the canonical declaration.
2543         Reader.PendingDefinitions.insert(DClass);
2544       }
2545     }
2546     DClass->DefinitionData = ExistingClass->DefinitionData;
2547 
2548     return mergeRedeclarable(DClass, cast<TagDecl>(ExistingPattern),
2549                              Result);
2550   }
2551   if (auto *DFunction = dyn_cast<FunctionDecl>(DPattern))
2552     return mergeRedeclarable(DFunction, cast<FunctionDecl>(ExistingPattern),
2553                              Result);
2554   if (auto *DVar = dyn_cast<VarDecl>(DPattern))
2555     return mergeRedeclarable(DVar, cast<VarDecl>(ExistingPattern), Result);
2556   if (auto *DAlias = dyn_cast<TypeAliasDecl>(DPattern))
2557     return mergeRedeclarable(DAlias, cast<TypedefNameDecl>(ExistingPattern),
2558                              Result);
2559   llvm_unreachable("merged an unknown kind of redeclarable template");
2560 }
2561 
2562 /// Attempts to merge the given declaration (D) with another declaration
2563 /// of the same entity.
2564 template<typename T>
2565 void ASTDeclReader::mergeRedeclarable(Redeclarable<T> *DBase, T *Existing,
2566                                       RedeclarableResult &Redecl,
2567                                       DeclID TemplatePatternID) {
2568   auto *D = static_cast<T *>(DBase);
2569   T *ExistingCanon = Existing->getCanonicalDecl();
2570   T *DCanon = D->getCanonicalDecl();
2571   if (ExistingCanon != DCanon) {
2572     assert(DCanon->getGlobalID() == Redecl.getFirstID() &&
2573            "already merged this declaration");
2574 
2575     // Have our redeclaration link point back at the canonical declaration
2576     // of the existing declaration, so that this declaration has the
2577     // appropriate canonical declaration.
2578     D->RedeclLink = Redeclarable<T>::PreviousDeclLink(ExistingCanon);
2579     D->First = ExistingCanon;
2580     ExistingCanon->Used |= D->Used;
2581     D->Used = false;
2582 
2583     // When we merge a namespace, update its pointer to the first namespace.
2584     // We cannot have loaded any redeclarations of this declaration yet, so
2585     // there's nothing else that needs to be updated.
2586     if (auto *Namespace = dyn_cast<NamespaceDecl>(D))
2587       Namespace->AnonOrFirstNamespaceAndInline.setPointer(
2588           assert_cast<NamespaceDecl*>(ExistingCanon));
2589 
2590     // When we merge a template, merge its pattern.
2591     if (auto *DTemplate = dyn_cast<RedeclarableTemplateDecl>(D))
2592       mergeTemplatePattern(
2593           DTemplate, assert_cast<RedeclarableTemplateDecl*>(ExistingCanon),
2594           TemplatePatternID, Redecl.isKeyDecl());
2595 
2596     // If this declaration is a key declaration, make a note of that.
2597     if (Redecl.isKeyDecl())
2598       Reader.KeyDecls[ExistingCanon].push_back(Redecl.getFirstID());
2599   }
2600 }
2601 
2602 /// ODR-like semantics for C/ObjC allow us to merge tag types and a structural
2603 /// check in Sema guarantees the types can be merged (see C11 6.2.7/1 or C89
2604 /// 6.1.2.6/1). Although most merging is done in Sema, we need to guarantee
2605 /// that some types are mergeable during deserialization, otherwise name
2606 /// lookup fails. This is the case for EnumConstantDecl.
2607 static bool allowODRLikeMergeInC(NamedDecl *ND) {
2608   if (!ND)
2609     return false;
2610   // TODO: implement merge for other necessary decls.
2611   if (isa<EnumConstantDecl>(ND))
2612     return true;
2613   return false;
2614 }
2615 
2616 /// Attempts to merge the given declaration (D) with another declaration
2617 /// of the same entity, for the case where the entity is not actually
2618 /// redeclarable. This happens, for instance, when merging the fields of
2619 /// identical class definitions from two different modules.
2620 template<typename T>
2621 void ASTDeclReader::mergeMergeable(Mergeable<T> *D) {
2622   // If modules are not available, there is no reason to perform this merge.
2623   if (!Reader.getContext().getLangOpts().Modules)
2624     return;
2625 
2626   // ODR-based merging is performed in C++ and in some cases (tag types) in C.
2627   // Note that C identically-named things in different translation units are
2628   // not redeclarations, but may still have compatible types, where ODR-like
2629   // semantics may apply.
2630   if (!Reader.getContext().getLangOpts().CPlusPlus &&
2631       !allowODRLikeMergeInC(dyn_cast<NamedDecl>(static_cast<T*>(D))))
2632     return;
2633 
2634   if (FindExistingResult ExistingRes = findExisting(static_cast<T*>(D)))
2635     if (T *Existing = ExistingRes)
2636       Reader.getContext().setPrimaryMergedDecl(static_cast<T *>(D),
2637                                                Existing->getCanonicalDecl());
2638 }
2639 
2640 void ASTDeclReader::VisitOMPThreadPrivateDecl(OMPThreadPrivateDecl *D) {
2641   VisitDecl(D);
2642   unsigned NumVars = D->varlist_size();
2643   SmallVector<Expr *, 16> Vars;
2644   Vars.reserve(NumVars);
2645   for (unsigned i = 0; i != NumVars; ++i) {
2646     Vars.push_back(Record.readExpr());
2647   }
2648   D->setVars(Vars);
2649 }
2650 
2651 void ASTDeclReader::VisitOMPAllocateDecl(OMPAllocateDecl *D) {
2652   VisitDecl(D);
2653   unsigned NumVars = D->varlist_size();
2654   unsigned NumClauses = D->clauselist_size();
2655   SmallVector<Expr *, 16> Vars;
2656   Vars.reserve(NumVars);
2657   for (unsigned i = 0; i != NumVars; ++i) {
2658     Vars.push_back(Record.readExpr());
2659   }
2660   D->setVars(Vars);
2661   SmallVector<OMPClause *, 8> Clauses;
2662   Clauses.reserve(NumClauses);
2663   OMPClauseReader ClauseReader(Record);
2664   for (unsigned I = 0; I != NumClauses; ++I)
2665     Clauses.push_back(ClauseReader.readClause());
2666   D->setClauses(Clauses);
2667 }
2668 
2669 void ASTDeclReader::VisitOMPRequiresDecl(OMPRequiresDecl * D) {
2670   VisitDecl(D);
2671   unsigned NumClauses = D->clauselist_size();
2672   SmallVector<OMPClause *, 8> Clauses;
2673   Clauses.reserve(NumClauses);
2674   OMPClauseReader ClauseReader(Record);
2675   for (unsigned I = 0; I != NumClauses; ++I)
2676     Clauses.push_back(ClauseReader.readClause());
2677   D->setClauses(Clauses);
2678 }
2679 
2680 void ASTDeclReader::VisitOMPDeclareReductionDecl(OMPDeclareReductionDecl *D) {
2681   VisitValueDecl(D);
2682   D->setLocation(ReadSourceLocation());
2683   Expr *In = Record.readExpr();
2684   Expr *Out = Record.readExpr();
2685   D->setCombinerData(In, Out);
2686   Expr *Combiner = Record.readExpr();
2687   D->setCombiner(Combiner);
2688   Expr *Orig = Record.readExpr();
2689   Expr *Priv = Record.readExpr();
2690   D->setInitializerData(Orig, Priv);
2691   Expr *Init = Record.readExpr();
2692   auto IK = static_cast<OMPDeclareReductionDecl::InitKind>(Record.readInt());
2693   D->setInitializer(Init, IK);
2694   D->PrevDeclInScope = ReadDeclID();
2695 }
2696 
2697 void ASTDeclReader::VisitOMPDeclareMapperDecl(OMPDeclareMapperDecl *D) {
2698   VisitValueDecl(D);
2699   D->setLocation(ReadSourceLocation());
2700   Expr *MapperVarRefE = Record.readExpr();
2701   D->setMapperVarRef(MapperVarRefE);
2702   D->VarName = Record.readDeclarationName();
2703   D->PrevDeclInScope = ReadDeclID();
2704   unsigned NumClauses = D->clauselist_size();
2705   SmallVector<OMPClause *, 8> Clauses;
2706   Clauses.reserve(NumClauses);
2707   OMPClauseReader ClauseReader(Record);
2708   for (unsigned I = 0; I != NumClauses; ++I)
2709     Clauses.push_back(ClauseReader.readClause());
2710   D->setClauses(Clauses);
2711 }
2712 
2713 void ASTDeclReader::VisitOMPCapturedExprDecl(OMPCapturedExprDecl *D) {
2714   VisitVarDecl(D);
2715 }
2716 
2717 //===----------------------------------------------------------------------===//
2718 // Attribute Reading
2719 //===----------------------------------------------------------------------===//
2720 
2721 namespace {
2722 class AttrReader {
2723   ModuleFile *F;
2724   ASTReader *Reader;
2725   const ASTReader::RecordData &Record;
2726   unsigned &Idx;
2727 
2728 public:
2729   AttrReader(ModuleFile &F, ASTReader &Reader,
2730              const ASTReader::RecordData &Record, unsigned &Idx)
2731       : F(&F), Reader(&Reader), Record(Record), Idx(Idx) {}
2732 
2733   const uint64_t &readInt() { return Record[Idx++]; }
2734 
2735   SourceRange readSourceRange() {
2736     return Reader->ReadSourceRange(*F, Record, Idx);
2737   }
2738 
2739   Expr *readExpr() { return Reader->ReadExpr(*F); }
2740 
2741   std::string readString() {
2742     return Reader->ReadString(Record, Idx);
2743   }
2744 
2745   TypeSourceInfo *getTypeSourceInfo() {
2746     return Reader->GetTypeSourceInfo(*F, Record, Idx);
2747   }
2748 
2749   IdentifierInfo *getIdentifierInfo() {
2750     return Reader->GetIdentifierInfo(*F, Record, Idx);
2751   }
2752 
2753   VersionTuple readVersionTuple() {
2754     return ASTReader::ReadVersionTuple(Record, Idx);
2755   }
2756 
2757   template <typename T> T *GetLocalDeclAs(uint32_t LocalID) {
2758     return cast_or_null<T>(Reader->GetLocalDecl(*F, LocalID));
2759   }
2760 };
2761 }
2762 
2763 Attr *ASTReader::ReadAttr(ModuleFile &M, const RecordData &Rec,
2764                           unsigned &Idx) {
2765   AttrReader Record(M, *this, Rec, Idx);
2766   auto V = Record.readInt();
2767   if (!V)
2768     return nullptr;
2769 
2770   Attr *New = nullptr;
2771   // Kind is stored as a 1-based integer because 0 is used to indicate a null
2772   // Attr pointer.
2773   auto Kind = static_cast<attr::Kind>(V - 1);
2774   SourceRange Range = Record.readSourceRange();
2775   ASTContext &Context = getContext();
2776 
2777 #include "clang/Serialization/AttrPCHRead.inc"
2778 
2779   assert(New && "Unable to decode attribute?");
2780   return New;
2781 }
2782 
2783 /// Reads attributes from the current stream position.
2784 void ASTReader::ReadAttributes(ASTRecordReader &Record, AttrVec &Attrs) {
2785   for (unsigned I = 0, E = Record.readInt(); I != E; ++I)
2786     Attrs.push_back(Record.readAttr());
2787 }
2788 
2789 //===----------------------------------------------------------------------===//
2790 // ASTReader Implementation
2791 //===----------------------------------------------------------------------===//
2792 
2793 /// Note that we have loaded the declaration with the given
2794 /// Index.
2795 ///
2796 /// This routine notes that this declaration has already been loaded,
2797 /// so that future GetDecl calls will return this declaration rather
2798 /// than trying to load a new declaration.
2799 inline void ASTReader::LoadedDecl(unsigned Index, Decl *D) {
2800   assert(!DeclsLoaded[Index] && "Decl loaded twice?");
2801   DeclsLoaded[Index] = D;
2802 }
2803 
2804 /// Determine whether the consumer will be interested in seeing
2805 /// this declaration (via HandleTopLevelDecl).
2806 ///
2807 /// This routine should return true for anything that might affect
2808 /// code generation, e.g., inline function definitions, Objective-C
2809 /// declarations with metadata, etc.
2810 static bool isConsumerInterestedIn(ASTContext &Ctx, Decl *D, bool HasBody) {
2811   // An ObjCMethodDecl is never considered as "interesting" because its
2812   // implementation container always is.
2813 
2814   // An ImportDecl or VarDecl imported from a module map module will get
2815   // emitted when we import the relevant module.
2816   if (isPartOfPerModuleInitializer(D)) {
2817     auto *M = D->getImportedOwningModule();
2818     if (M && M->Kind == Module::ModuleMapModule &&
2819         Ctx.DeclMustBeEmitted(D))
2820       return false;
2821   }
2822 
2823   if (isa<FileScopeAsmDecl>(D) ||
2824       isa<ObjCProtocolDecl>(D) ||
2825       isa<ObjCImplDecl>(D) ||
2826       isa<ImportDecl>(D) ||
2827       isa<PragmaCommentDecl>(D) ||
2828       isa<PragmaDetectMismatchDecl>(D))
2829     return true;
2830   if (isa<OMPThreadPrivateDecl>(D) || isa<OMPDeclareReductionDecl>(D) ||
2831       isa<OMPDeclareMapperDecl>(D) || isa<OMPAllocateDecl>(D))
2832     return !D->getDeclContext()->isFunctionOrMethod();
2833   if (const auto *Var = dyn_cast<VarDecl>(D))
2834     return Var->isFileVarDecl() &&
2835            (Var->isThisDeclarationADefinition() == VarDecl::Definition ||
2836             OMPDeclareTargetDeclAttr::isDeclareTargetDeclaration(Var));
2837   if (const auto *Func = dyn_cast<FunctionDecl>(D))
2838     return Func->doesThisDeclarationHaveABody() || HasBody;
2839 
2840   if (auto *ES = D->getASTContext().getExternalSource())
2841     if (ES->hasExternalDefinitions(D) == ExternalASTSource::EK_Never)
2842       return true;
2843 
2844   return false;
2845 }
2846 
2847 /// Get the correct cursor and offset for loading a declaration.
2848 ASTReader::RecordLocation
2849 ASTReader::DeclCursorForID(DeclID ID, SourceLocation &Loc) {
2850   GlobalDeclMapType::iterator I = GlobalDeclMap.find(ID);
2851   assert(I != GlobalDeclMap.end() && "Corrupted global declaration map");
2852   ModuleFile *M = I->second;
2853   const DeclOffset &DOffs =
2854       M->DeclOffsets[ID - M->BaseDeclID - NUM_PREDEF_DECL_IDS];
2855   Loc = TranslateSourceLocation(*M, DOffs.getLocation());
2856   return RecordLocation(M, DOffs.BitOffset);
2857 }
2858 
2859 ASTReader::RecordLocation ASTReader::getLocalBitOffset(uint64_t GlobalOffset) {
2860   auto I = GlobalBitOffsetsMap.find(GlobalOffset);
2861 
2862   assert(I != GlobalBitOffsetsMap.end() && "Corrupted global bit offsets map");
2863   return RecordLocation(I->second, GlobalOffset - I->second->GlobalBitOffset);
2864 }
2865 
2866 uint64_t ASTReader::getGlobalBitOffset(ModuleFile &M, uint32_t LocalOffset) {
2867   return LocalOffset + M.GlobalBitOffset;
2868 }
2869 
2870 static bool isSameTemplateParameterList(const TemplateParameterList *X,
2871                                         const TemplateParameterList *Y);
2872 
2873 /// Determine whether two template parameters are similar enough
2874 /// that they may be used in declarations of the same template.
2875 static bool isSameTemplateParameter(const NamedDecl *X,
2876                                     const NamedDecl *Y) {
2877   if (X->getKind() != Y->getKind())
2878     return false;
2879 
2880   if (const auto *TX = dyn_cast<TemplateTypeParmDecl>(X)) {
2881     const auto *TY = cast<TemplateTypeParmDecl>(Y);
2882     return TX->isParameterPack() == TY->isParameterPack();
2883   }
2884 
2885   if (const auto *TX = dyn_cast<NonTypeTemplateParmDecl>(X)) {
2886     const auto *TY = cast<NonTypeTemplateParmDecl>(Y);
2887     return TX->isParameterPack() == TY->isParameterPack() &&
2888            TX->getASTContext().hasSameType(TX->getType(), TY->getType());
2889   }
2890 
2891   const auto *TX = cast<TemplateTemplateParmDecl>(X);
2892   const auto *TY = cast<TemplateTemplateParmDecl>(Y);
2893   return TX->isParameterPack() == TY->isParameterPack() &&
2894          isSameTemplateParameterList(TX->getTemplateParameters(),
2895                                      TY->getTemplateParameters());
2896 }
2897 
2898 static NamespaceDecl *getNamespace(const NestedNameSpecifier *X) {
2899   if (auto *NS = X->getAsNamespace())
2900     return NS;
2901   if (auto *NAS = X->getAsNamespaceAlias())
2902     return NAS->getNamespace();
2903   return nullptr;
2904 }
2905 
2906 static bool isSameQualifier(const NestedNameSpecifier *X,
2907                             const NestedNameSpecifier *Y) {
2908   if (auto *NSX = getNamespace(X)) {
2909     auto *NSY = getNamespace(Y);
2910     if (!NSY || NSX->getCanonicalDecl() != NSY->getCanonicalDecl())
2911       return false;
2912   } else if (X->getKind() != Y->getKind())
2913     return false;
2914 
2915   // FIXME: For namespaces and types, we're permitted to check that the entity
2916   // is named via the same tokens. We should probably do so.
2917   switch (X->getKind()) {
2918   case NestedNameSpecifier::Identifier:
2919     if (X->getAsIdentifier() != Y->getAsIdentifier())
2920       return false;
2921     break;
2922   case NestedNameSpecifier::Namespace:
2923   case NestedNameSpecifier::NamespaceAlias:
2924     // We've already checked that we named the same namespace.
2925     break;
2926   case NestedNameSpecifier::TypeSpec:
2927   case NestedNameSpecifier::TypeSpecWithTemplate:
2928     if (X->getAsType()->getCanonicalTypeInternal() !=
2929         Y->getAsType()->getCanonicalTypeInternal())
2930       return false;
2931     break;
2932   case NestedNameSpecifier::Global:
2933   case NestedNameSpecifier::Super:
2934     return true;
2935   }
2936 
2937   // Recurse into earlier portion of NNS, if any.
2938   auto *PX = X->getPrefix();
2939   auto *PY = Y->getPrefix();
2940   if (PX && PY)
2941     return isSameQualifier(PX, PY);
2942   return !PX && !PY;
2943 }
2944 
2945 /// Determine whether two template parameter lists are similar enough
2946 /// that they may be used in declarations of the same template.
2947 static bool isSameTemplateParameterList(const TemplateParameterList *X,
2948                                         const TemplateParameterList *Y) {
2949   if (X->size() != Y->size())
2950     return false;
2951 
2952   for (unsigned I = 0, N = X->size(); I != N; ++I)
2953     if (!isSameTemplateParameter(X->getParam(I), Y->getParam(I)))
2954       return false;
2955 
2956   return true;
2957 }
2958 
2959 /// Determine whether the attributes we can overload on are identical for A and
2960 /// B. Will ignore any overloadable attrs represented in the type of A and B.
2961 static bool hasSameOverloadableAttrs(const FunctionDecl *A,
2962                                      const FunctionDecl *B) {
2963   // Note that pass_object_size attributes are represented in the function's
2964   // ExtParameterInfo, so we don't need to check them here.
2965 
2966   llvm::FoldingSetNodeID Cand1ID, Cand2ID;
2967   auto AEnableIfAttrs = A->specific_attrs<EnableIfAttr>();
2968   auto BEnableIfAttrs = B->specific_attrs<EnableIfAttr>();
2969 
2970   for (auto Pair : zip_longest(AEnableIfAttrs, BEnableIfAttrs)) {
2971     Optional<EnableIfAttr *> Cand1A = std::get<0>(Pair);
2972     Optional<EnableIfAttr *> Cand2A = std::get<1>(Pair);
2973 
2974     // Return false if the number of enable_if attributes is different.
2975     if (!Cand1A || !Cand2A)
2976       return false;
2977 
2978     Cand1ID.clear();
2979     Cand2ID.clear();
2980 
2981     (*Cand1A)->getCond()->Profile(Cand1ID, A->getASTContext(), true);
2982     (*Cand2A)->getCond()->Profile(Cand2ID, B->getASTContext(), true);
2983 
2984     // Return false if any of the enable_if expressions of A and B are
2985     // different.
2986     if (Cand1ID != Cand2ID)
2987       return false;
2988   }
2989   return true;
2990 }
2991 
2992 /// Determine whether the two declarations refer to the same entity.
2993 static bool isSameEntity(NamedDecl *X, NamedDecl *Y) {
2994   assert(X->getDeclName() == Y->getDeclName() && "Declaration name mismatch!");
2995 
2996   if (X == Y)
2997     return true;
2998 
2999   // Must be in the same context.
3000   //
3001   // Note that we can't use DeclContext::Equals here, because the DeclContexts
3002   // could be two different declarations of the same function. (We will fix the
3003   // semantic DC to refer to the primary definition after merging.)
3004   if (!declaresSameEntity(cast<Decl>(X->getDeclContext()->getRedeclContext()),
3005                           cast<Decl>(Y->getDeclContext()->getRedeclContext())))
3006     return false;
3007 
3008   // Two typedefs refer to the same entity if they have the same underlying
3009   // type.
3010   if (const auto *TypedefX = dyn_cast<TypedefNameDecl>(X))
3011     if (const auto *TypedefY = dyn_cast<TypedefNameDecl>(Y))
3012       return X->getASTContext().hasSameType(TypedefX->getUnderlyingType(),
3013                                             TypedefY->getUnderlyingType());
3014 
3015   // Must have the same kind.
3016   if (X->getKind() != Y->getKind())
3017     return false;
3018 
3019   // Objective-C classes and protocols with the same name always match.
3020   if (isa<ObjCInterfaceDecl>(X) || isa<ObjCProtocolDecl>(X))
3021     return true;
3022 
3023   if (isa<ClassTemplateSpecializationDecl>(X)) {
3024     // No need to handle these here: we merge them when adding them to the
3025     // template.
3026     return false;
3027   }
3028 
3029   // Compatible tags match.
3030   if (const auto *TagX = dyn_cast<TagDecl>(X)) {
3031     const auto *TagY = cast<TagDecl>(Y);
3032     return (TagX->getTagKind() == TagY->getTagKind()) ||
3033       ((TagX->getTagKind() == TTK_Struct || TagX->getTagKind() == TTK_Class ||
3034         TagX->getTagKind() == TTK_Interface) &&
3035        (TagY->getTagKind() == TTK_Struct || TagY->getTagKind() == TTK_Class ||
3036         TagY->getTagKind() == TTK_Interface));
3037   }
3038 
3039   // Functions with the same type and linkage match.
3040   // FIXME: This needs to cope with merging of prototyped/non-prototyped
3041   // functions, etc.
3042   if (const auto *FuncX = dyn_cast<FunctionDecl>(X)) {
3043     const auto *FuncY = cast<FunctionDecl>(Y);
3044     if (const auto *CtorX = dyn_cast<CXXConstructorDecl>(X)) {
3045       const auto *CtorY = cast<CXXConstructorDecl>(Y);
3046       if (CtorX->getInheritedConstructor() &&
3047           !isSameEntity(CtorX->getInheritedConstructor().getConstructor(),
3048                         CtorY->getInheritedConstructor().getConstructor()))
3049         return false;
3050     }
3051 
3052     if (FuncX->isMultiVersion() != FuncY->isMultiVersion())
3053       return false;
3054 
3055     // Multiversioned functions with different feature strings are represented
3056     // as separate declarations.
3057     if (FuncX->isMultiVersion()) {
3058       const auto *TAX = FuncX->getAttr<TargetAttr>();
3059       const auto *TAY = FuncY->getAttr<TargetAttr>();
3060       assert(TAX && TAY && "Multiversion Function without target attribute");
3061 
3062       if (TAX->getFeaturesStr() != TAY->getFeaturesStr())
3063         return false;
3064     }
3065 
3066     ASTContext &C = FuncX->getASTContext();
3067     auto GetTypeAsWritten = [](const FunctionDecl *FD) {
3068       // Map to the first declaration that we've already merged into this one.
3069       // The TSI of redeclarations might not match (due to calling conventions
3070       // being inherited onto the type but not the TSI), but the TSI type of
3071       // the first declaration of the function should match across modules.
3072       FD = FD->getCanonicalDecl();
3073       return FD->getTypeSourceInfo() ? FD->getTypeSourceInfo()->getType()
3074                                      : FD->getType();
3075     };
3076     QualType XT = GetTypeAsWritten(FuncX), YT = GetTypeAsWritten(FuncY);
3077     if (!C.hasSameType(XT, YT)) {
3078       // We can get functions with different types on the redecl chain in C++17
3079       // if they have differing exception specifications and at least one of
3080       // the excpetion specs is unresolved.
3081       auto *XFPT = XT->getAs<FunctionProtoType>();
3082       auto *YFPT = YT->getAs<FunctionProtoType>();
3083       if (C.getLangOpts().CPlusPlus17 && XFPT && YFPT &&
3084           (isUnresolvedExceptionSpec(XFPT->getExceptionSpecType()) ||
3085            isUnresolvedExceptionSpec(YFPT->getExceptionSpecType())) &&
3086           C.hasSameFunctionTypeIgnoringExceptionSpec(XT, YT))
3087         return true;
3088       return false;
3089     }
3090     return FuncX->getLinkageInternal() == FuncY->getLinkageInternal() &&
3091            hasSameOverloadableAttrs(FuncX, FuncY);
3092   }
3093 
3094   // Variables with the same type and linkage match.
3095   if (const auto *VarX = dyn_cast<VarDecl>(X)) {
3096     const auto *VarY = cast<VarDecl>(Y);
3097     if (VarX->getLinkageInternal() == VarY->getLinkageInternal()) {
3098       ASTContext &C = VarX->getASTContext();
3099       if (C.hasSameType(VarX->getType(), VarY->getType()))
3100         return true;
3101 
3102       // We can get decls with different types on the redecl chain. Eg.
3103       // template <typename T> struct S { static T Var[]; }; // #1
3104       // template <typename T> T S<T>::Var[sizeof(T)]; // #2
3105       // Only? happens when completing an incomplete array type. In this case
3106       // when comparing #1 and #2 we should go through their element type.
3107       const ArrayType *VarXTy = C.getAsArrayType(VarX->getType());
3108       const ArrayType *VarYTy = C.getAsArrayType(VarY->getType());
3109       if (!VarXTy || !VarYTy)
3110         return false;
3111       if (VarXTy->isIncompleteArrayType() || VarYTy->isIncompleteArrayType())
3112         return C.hasSameType(VarXTy->getElementType(), VarYTy->getElementType());
3113     }
3114     return false;
3115   }
3116 
3117   // Namespaces with the same name and inlinedness match.
3118   if (const auto *NamespaceX = dyn_cast<NamespaceDecl>(X)) {
3119     const auto *NamespaceY = cast<NamespaceDecl>(Y);
3120     return NamespaceX->isInline() == NamespaceY->isInline();
3121   }
3122 
3123   // Identical template names and kinds match if their template parameter lists
3124   // and patterns match.
3125   if (const auto *TemplateX = dyn_cast<TemplateDecl>(X)) {
3126     const auto *TemplateY = cast<TemplateDecl>(Y);
3127     return isSameEntity(TemplateX->getTemplatedDecl(),
3128                         TemplateY->getTemplatedDecl()) &&
3129            isSameTemplateParameterList(TemplateX->getTemplateParameters(),
3130                                        TemplateY->getTemplateParameters());
3131   }
3132 
3133   // Fields with the same name and the same type match.
3134   if (const auto *FDX = dyn_cast<FieldDecl>(X)) {
3135     const auto *FDY = cast<FieldDecl>(Y);
3136     // FIXME: Also check the bitwidth is odr-equivalent, if any.
3137     return X->getASTContext().hasSameType(FDX->getType(), FDY->getType());
3138   }
3139 
3140   // Indirect fields with the same target field match.
3141   if (const auto *IFDX = dyn_cast<IndirectFieldDecl>(X)) {
3142     const auto *IFDY = cast<IndirectFieldDecl>(Y);
3143     return IFDX->getAnonField()->getCanonicalDecl() ==
3144            IFDY->getAnonField()->getCanonicalDecl();
3145   }
3146 
3147   // Enumerators with the same name match.
3148   if (isa<EnumConstantDecl>(X))
3149     // FIXME: Also check the value is odr-equivalent.
3150     return true;
3151 
3152   // Using shadow declarations with the same target match.
3153   if (const auto *USX = dyn_cast<UsingShadowDecl>(X)) {
3154     const auto *USY = cast<UsingShadowDecl>(Y);
3155     return USX->getTargetDecl() == USY->getTargetDecl();
3156   }
3157 
3158   // Using declarations with the same qualifier match. (We already know that
3159   // the name matches.)
3160   if (const auto *UX = dyn_cast<UsingDecl>(X)) {
3161     const auto *UY = cast<UsingDecl>(Y);
3162     return isSameQualifier(UX->getQualifier(), UY->getQualifier()) &&
3163            UX->hasTypename() == UY->hasTypename() &&
3164            UX->isAccessDeclaration() == UY->isAccessDeclaration();
3165   }
3166   if (const auto *UX = dyn_cast<UnresolvedUsingValueDecl>(X)) {
3167     const auto *UY = cast<UnresolvedUsingValueDecl>(Y);
3168     return isSameQualifier(UX->getQualifier(), UY->getQualifier()) &&
3169            UX->isAccessDeclaration() == UY->isAccessDeclaration();
3170   }
3171   if (const auto *UX = dyn_cast<UnresolvedUsingTypenameDecl>(X))
3172     return isSameQualifier(
3173         UX->getQualifier(),
3174         cast<UnresolvedUsingTypenameDecl>(Y)->getQualifier());
3175 
3176   // Namespace alias definitions with the same target match.
3177   if (const auto *NAX = dyn_cast<NamespaceAliasDecl>(X)) {
3178     const auto *NAY = cast<NamespaceAliasDecl>(Y);
3179     return NAX->getNamespace()->Equals(NAY->getNamespace());
3180   }
3181 
3182   return false;
3183 }
3184 
3185 /// Find the context in which we should search for previous declarations when
3186 /// looking for declarations to merge.
3187 DeclContext *ASTDeclReader::getPrimaryContextForMerging(ASTReader &Reader,
3188                                                         DeclContext *DC) {
3189   if (auto *ND = dyn_cast<NamespaceDecl>(DC))
3190     return ND->getOriginalNamespace();
3191 
3192   if (auto *RD = dyn_cast<CXXRecordDecl>(DC)) {
3193     // Try to dig out the definition.
3194     auto *DD = RD->DefinitionData;
3195     if (!DD)
3196       DD = RD->getCanonicalDecl()->DefinitionData;
3197 
3198     // If there's no definition yet, then DC's definition is added by an update
3199     // record, but we've not yet loaded that update record. In this case, we
3200     // commit to DC being the canonical definition now, and will fix this when
3201     // we load the update record.
3202     if (!DD) {
3203       DD = new (Reader.getContext()) struct CXXRecordDecl::DefinitionData(RD);
3204       RD->setCompleteDefinition(true);
3205       RD->DefinitionData = DD;
3206       RD->getCanonicalDecl()->DefinitionData = DD;
3207 
3208       // Track that we did this horrible thing so that we can fix it later.
3209       Reader.PendingFakeDefinitionData.insert(
3210           std::make_pair(DD, ASTReader::PendingFakeDefinitionKind::Fake));
3211     }
3212 
3213     return DD->Definition;
3214   }
3215 
3216   if (auto *ED = dyn_cast<EnumDecl>(DC))
3217     return ED->getASTContext().getLangOpts().CPlusPlus? ED->getDefinition()
3218                                                       : nullptr;
3219 
3220   // We can see the TU here only if we have no Sema object. In that case,
3221   // there's no TU scope to look in, so using the DC alone is sufficient.
3222   if (auto *TU = dyn_cast<TranslationUnitDecl>(DC))
3223     return TU;
3224 
3225   return nullptr;
3226 }
3227 
3228 ASTDeclReader::FindExistingResult::~FindExistingResult() {
3229   // Record that we had a typedef name for linkage whether or not we merge
3230   // with that declaration.
3231   if (TypedefNameForLinkage) {
3232     DeclContext *DC = New->getDeclContext()->getRedeclContext();
3233     Reader.ImportedTypedefNamesForLinkage.insert(
3234         std::make_pair(std::make_pair(DC, TypedefNameForLinkage), New));
3235     return;
3236   }
3237 
3238   if (!AddResult || Existing)
3239     return;
3240 
3241   DeclarationName Name = New->getDeclName();
3242   DeclContext *DC = New->getDeclContext()->getRedeclContext();
3243   if (needsAnonymousDeclarationNumber(New)) {
3244     setAnonymousDeclForMerging(Reader, New->getLexicalDeclContext(),
3245                                AnonymousDeclNumber, New);
3246   } else if (DC->isTranslationUnit() &&
3247              !Reader.getContext().getLangOpts().CPlusPlus) {
3248     if (Reader.getIdResolver().tryAddTopLevelDecl(New, Name))
3249       Reader.PendingFakeLookupResults[Name.getAsIdentifierInfo()]
3250             .push_back(New);
3251   } else if (DeclContext *MergeDC = getPrimaryContextForMerging(Reader, DC)) {
3252     // Add the declaration to its redeclaration context so later merging
3253     // lookups will find it.
3254     MergeDC->makeDeclVisibleInContextImpl(New, /*Internal*/true);
3255   }
3256 }
3257 
3258 /// Find the declaration that should be merged into, given the declaration found
3259 /// by name lookup. If we're merging an anonymous declaration within a typedef,
3260 /// we need a matching typedef, and we merge with the type inside it.
3261 static NamedDecl *getDeclForMerging(NamedDecl *Found,
3262                                     bool IsTypedefNameForLinkage) {
3263   if (!IsTypedefNameForLinkage)
3264     return Found;
3265 
3266   // If we found a typedef declaration that gives a name to some other
3267   // declaration, then we want that inner declaration. Declarations from
3268   // AST files are handled via ImportedTypedefNamesForLinkage.
3269   if (Found->isFromASTFile())
3270     return nullptr;
3271 
3272   if (auto *TND = dyn_cast<TypedefNameDecl>(Found))
3273     return TND->getAnonDeclWithTypedefName(/*AnyRedecl*/true);
3274 
3275   return nullptr;
3276 }
3277 
3278 /// Find the declaration to use to populate the anonymous declaration table
3279 /// for the given lexical DeclContext. We only care about finding local
3280 /// definitions of the context; we'll merge imported ones as we go.
3281 DeclContext *
3282 ASTDeclReader::getPrimaryDCForAnonymousDecl(DeclContext *LexicalDC) {
3283   // For classes, we track the definition as we merge.
3284   if (auto *RD = dyn_cast<CXXRecordDecl>(LexicalDC)) {
3285     auto *DD = RD->getCanonicalDecl()->DefinitionData;
3286     return DD ? DD->Definition : nullptr;
3287   }
3288 
3289   // For anything else, walk its merged redeclarations looking for a definition.
3290   // Note that we can't just call getDefinition here because the redeclaration
3291   // chain isn't wired up.
3292   for (auto *D : merged_redecls(cast<Decl>(LexicalDC))) {
3293     if (auto *FD = dyn_cast<FunctionDecl>(D))
3294       if (FD->isThisDeclarationADefinition())
3295         return FD;
3296     if (auto *MD = dyn_cast<ObjCMethodDecl>(D))
3297       if (MD->isThisDeclarationADefinition())
3298         return MD;
3299   }
3300 
3301   // No merged definition yet.
3302   return nullptr;
3303 }
3304 
3305 NamedDecl *ASTDeclReader::getAnonymousDeclForMerging(ASTReader &Reader,
3306                                                      DeclContext *DC,
3307                                                      unsigned Index) {
3308   // If the lexical context has been merged, look into the now-canonical
3309   // definition.
3310   auto *CanonDC = cast<Decl>(DC)->getCanonicalDecl();
3311 
3312   // If we've seen this before, return the canonical declaration.
3313   auto &Previous = Reader.AnonymousDeclarationsForMerging[CanonDC];
3314   if (Index < Previous.size() && Previous[Index])
3315     return Previous[Index];
3316 
3317   // If this is the first time, but we have parsed a declaration of the context,
3318   // build the anonymous declaration list from the parsed declaration.
3319   auto *PrimaryDC = getPrimaryDCForAnonymousDecl(DC);
3320   if (PrimaryDC && !cast<Decl>(PrimaryDC)->isFromASTFile()) {
3321     numberAnonymousDeclsWithin(PrimaryDC, [&](NamedDecl *ND, unsigned Number) {
3322       if (Previous.size() == Number)
3323         Previous.push_back(cast<NamedDecl>(ND->getCanonicalDecl()));
3324       else
3325         Previous[Number] = cast<NamedDecl>(ND->getCanonicalDecl());
3326     });
3327   }
3328 
3329   return Index < Previous.size() ? Previous[Index] : nullptr;
3330 }
3331 
3332 void ASTDeclReader::setAnonymousDeclForMerging(ASTReader &Reader,
3333                                                DeclContext *DC, unsigned Index,
3334                                                NamedDecl *D) {
3335   auto *CanonDC = cast<Decl>(DC)->getCanonicalDecl();
3336 
3337   auto &Previous = Reader.AnonymousDeclarationsForMerging[CanonDC];
3338   if (Index >= Previous.size())
3339     Previous.resize(Index + 1);
3340   if (!Previous[Index])
3341     Previous[Index] = D;
3342 }
3343 
3344 ASTDeclReader::FindExistingResult ASTDeclReader::findExisting(NamedDecl *D) {
3345   DeclarationName Name = TypedefNameForLinkage ? TypedefNameForLinkage
3346                                                : D->getDeclName();
3347 
3348   if (!Name && !needsAnonymousDeclarationNumber(D)) {
3349     // Don't bother trying to find unnamed declarations that are in
3350     // unmergeable contexts.
3351     FindExistingResult Result(Reader, D, /*Existing=*/nullptr,
3352                               AnonymousDeclNumber, TypedefNameForLinkage);
3353     Result.suppress();
3354     return Result;
3355   }
3356 
3357   DeclContext *DC = D->getDeclContext()->getRedeclContext();
3358   if (TypedefNameForLinkage) {
3359     auto It = Reader.ImportedTypedefNamesForLinkage.find(
3360         std::make_pair(DC, TypedefNameForLinkage));
3361     if (It != Reader.ImportedTypedefNamesForLinkage.end())
3362       if (isSameEntity(It->second, D))
3363         return FindExistingResult(Reader, D, It->second, AnonymousDeclNumber,
3364                                   TypedefNameForLinkage);
3365     // Go on to check in other places in case an existing typedef name
3366     // was not imported.
3367   }
3368 
3369   if (needsAnonymousDeclarationNumber(D)) {
3370     // This is an anonymous declaration that we may need to merge. Look it up
3371     // in its context by number.
3372     if (auto *Existing = getAnonymousDeclForMerging(
3373             Reader, D->getLexicalDeclContext(), AnonymousDeclNumber))
3374       if (isSameEntity(Existing, D))
3375         return FindExistingResult(Reader, D, Existing, AnonymousDeclNumber,
3376                                   TypedefNameForLinkage);
3377   } else if (DC->isTranslationUnit() &&
3378              !Reader.getContext().getLangOpts().CPlusPlus) {
3379     IdentifierResolver &IdResolver = Reader.getIdResolver();
3380 
3381     // Temporarily consider the identifier to be up-to-date. We don't want to
3382     // cause additional lookups here.
3383     class UpToDateIdentifierRAII {
3384       IdentifierInfo *II;
3385       bool WasOutToDate = false;
3386 
3387     public:
3388       explicit UpToDateIdentifierRAII(IdentifierInfo *II) : II(II) {
3389         if (II) {
3390           WasOutToDate = II->isOutOfDate();
3391           if (WasOutToDate)
3392             II->setOutOfDate(false);
3393         }
3394       }
3395 
3396       ~UpToDateIdentifierRAII() {
3397         if (WasOutToDate)
3398           II->setOutOfDate(true);
3399       }
3400     } UpToDate(Name.getAsIdentifierInfo());
3401 
3402     for (IdentifierResolver::iterator I = IdResolver.begin(Name),
3403                                    IEnd = IdResolver.end();
3404          I != IEnd; ++I) {
3405       if (NamedDecl *Existing = getDeclForMerging(*I, TypedefNameForLinkage))
3406         if (isSameEntity(Existing, D))
3407           return FindExistingResult(Reader, D, Existing, AnonymousDeclNumber,
3408                                     TypedefNameForLinkage);
3409     }
3410   } else if (DeclContext *MergeDC = getPrimaryContextForMerging(Reader, DC)) {
3411     DeclContext::lookup_result R = MergeDC->noload_lookup(Name);
3412     for (DeclContext::lookup_iterator I = R.begin(), E = R.end(); I != E; ++I) {
3413       if (NamedDecl *Existing = getDeclForMerging(*I, TypedefNameForLinkage))
3414         if (isSameEntity(Existing, D))
3415           return FindExistingResult(Reader, D, Existing, AnonymousDeclNumber,
3416                                     TypedefNameForLinkage);
3417     }
3418   } else {
3419     // Not in a mergeable context.
3420     return FindExistingResult(Reader);
3421   }
3422 
3423   // If this declaration is from a merged context, make a note that we need to
3424   // check that the canonical definition of that context contains the decl.
3425   //
3426   // FIXME: We should do something similar if we merge two definitions of the
3427   // same template specialization into the same CXXRecordDecl.
3428   auto MergedDCIt = Reader.MergedDeclContexts.find(D->getLexicalDeclContext());
3429   if (MergedDCIt != Reader.MergedDeclContexts.end() &&
3430       MergedDCIt->second == D->getDeclContext())
3431     Reader.PendingOdrMergeChecks.push_back(D);
3432 
3433   return FindExistingResult(Reader, D, /*Existing=*/nullptr,
3434                             AnonymousDeclNumber, TypedefNameForLinkage);
3435 }
3436 
3437 template<typename DeclT>
3438 Decl *ASTDeclReader::getMostRecentDeclImpl(Redeclarable<DeclT> *D) {
3439   return D->RedeclLink.getLatestNotUpdated();
3440 }
3441 
3442 Decl *ASTDeclReader::getMostRecentDeclImpl(...) {
3443   llvm_unreachable("getMostRecentDecl on non-redeclarable declaration");
3444 }
3445 
3446 Decl *ASTDeclReader::getMostRecentDecl(Decl *D) {
3447   assert(D);
3448 
3449   switch (D->getKind()) {
3450 #define ABSTRACT_DECL(TYPE)
3451 #define DECL(TYPE, BASE)                               \
3452   case Decl::TYPE:                                     \
3453     return getMostRecentDeclImpl(cast<TYPE##Decl>(D));
3454 #include "clang/AST/DeclNodes.inc"
3455   }
3456   llvm_unreachable("unknown decl kind");
3457 }
3458 
3459 Decl *ASTReader::getMostRecentExistingDecl(Decl *D) {
3460   return ASTDeclReader::getMostRecentDecl(D->getCanonicalDecl());
3461 }
3462 
3463 template<typename DeclT>
3464 void ASTDeclReader::attachPreviousDeclImpl(ASTReader &Reader,
3465                                            Redeclarable<DeclT> *D,
3466                                            Decl *Previous, Decl *Canon) {
3467   D->RedeclLink.setPrevious(cast<DeclT>(Previous));
3468   D->First = cast<DeclT>(Previous)->First;
3469 }
3470 
3471 namespace clang {
3472 
3473 template<>
3474 void ASTDeclReader::attachPreviousDeclImpl(ASTReader &Reader,
3475                                            Redeclarable<VarDecl> *D,
3476                                            Decl *Previous, Decl *Canon) {
3477   auto *VD = static_cast<VarDecl *>(D);
3478   auto *PrevVD = cast<VarDecl>(Previous);
3479   D->RedeclLink.setPrevious(PrevVD);
3480   D->First = PrevVD->First;
3481 
3482   // We should keep at most one definition on the chain.
3483   // FIXME: Cache the definition once we've found it. Building a chain with
3484   // N definitions currently takes O(N^2) time here.
3485   if (VD->isThisDeclarationADefinition() == VarDecl::Definition) {
3486     for (VarDecl *CurD = PrevVD; CurD; CurD = CurD->getPreviousDecl()) {
3487       if (CurD->isThisDeclarationADefinition() == VarDecl::Definition) {
3488         Reader.mergeDefinitionVisibility(CurD, VD);
3489         VD->demoteThisDefinitionToDeclaration();
3490         break;
3491       }
3492     }
3493   }
3494 }
3495 
3496 static bool isUndeducedReturnType(QualType T) {
3497   auto *DT = T->getContainedDeducedType();
3498   return DT && !DT->isDeduced();
3499 }
3500 
3501 template<>
3502 void ASTDeclReader::attachPreviousDeclImpl(ASTReader &Reader,
3503                                            Redeclarable<FunctionDecl> *D,
3504                                            Decl *Previous, Decl *Canon) {
3505   auto *FD = static_cast<FunctionDecl *>(D);
3506   auto *PrevFD = cast<FunctionDecl>(Previous);
3507 
3508   FD->RedeclLink.setPrevious(PrevFD);
3509   FD->First = PrevFD->First;
3510 
3511   // If the previous declaration is an inline function declaration, then this
3512   // declaration is too.
3513   if (PrevFD->isInlined() != FD->isInlined()) {
3514     // FIXME: [dcl.fct.spec]p4:
3515     //   If a function with external linkage is declared inline in one
3516     //   translation unit, it shall be declared inline in all translation
3517     //   units in which it appears.
3518     //
3519     // Be careful of this case:
3520     //
3521     // module A:
3522     //   template<typename T> struct X { void f(); };
3523     //   template<typename T> inline void X<T>::f() {}
3524     //
3525     // module B instantiates the declaration of X<int>::f
3526     // module C instantiates the definition of X<int>::f
3527     //
3528     // If module B and C are merged, we do not have a violation of this rule.
3529     FD->setImplicitlyInline(true);
3530   }
3531 
3532   auto *FPT = FD->getType()->getAs<FunctionProtoType>();
3533   auto *PrevFPT = PrevFD->getType()->getAs<FunctionProtoType>();
3534   if (FPT && PrevFPT) {
3535     // If we need to propagate an exception specification along the redecl
3536     // chain, make a note of that so that we can do so later.
3537     bool IsUnresolved = isUnresolvedExceptionSpec(FPT->getExceptionSpecType());
3538     bool WasUnresolved =
3539         isUnresolvedExceptionSpec(PrevFPT->getExceptionSpecType());
3540     if (IsUnresolved != WasUnresolved)
3541       Reader.PendingExceptionSpecUpdates.insert(
3542           {Canon, IsUnresolved ? PrevFD : FD});
3543 
3544     // If we need to propagate a deduced return type along the redecl chain,
3545     // make a note of that so that we can do it later.
3546     bool IsUndeduced = isUndeducedReturnType(FPT->getReturnType());
3547     bool WasUndeduced = isUndeducedReturnType(PrevFPT->getReturnType());
3548     if (IsUndeduced != WasUndeduced)
3549       Reader.PendingDeducedTypeUpdates.insert(
3550           {cast<FunctionDecl>(Canon),
3551            (IsUndeduced ? PrevFPT : FPT)->getReturnType()});
3552   }
3553 }
3554 
3555 } // namespace clang
3556 
3557 void ASTDeclReader::attachPreviousDeclImpl(ASTReader &Reader, ...) {
3558   llvm_unreachable("attachPreviousDecl on non-redeclarable declaration");
3559 }
3560 
3561 /// Inherit the default template argument from \p From to \p To. Returns
3562 /// \c false if there is no default template for \p From.
3563 template <typename ParmDecl>
3564 static bool inheritDefaultTemplateArgument(ASTContext &Context, ParmDecl *From,
3565                                            Decl *ToD) {
3566   auto *To = cast<ParmDecl>(ToD);
3567   if (!From->hasDefaultArgument())
3568     return false;
3569   To->setInheritedDefaultArgument(Context, From);
3570   return true;
3571 }
3572 
3573 static void inheritDefaultTemplateArguments(ASTContext &Context,
3574                                             TemplateDecl *From,
3575                                             TemplateDecl *To) {
3576   auto *FromTP = From->getTemplateParameters();
3577   auto *ToTP = To->getTemplateParameters();
3578   assert(FromTP->size() == ToTP->size() && "merged mismatched templates?");
3579 
3580   for (unsigned I = 0, N = FromTP->size(); I != N; ++I) {
3581     NamedDecl *FromParam = FromTP->getParam(I);
3582     NamedDecl *ToParam = ToTP->getParam(I);
3583 
3584     if (auto *FTTP = dyn_cast<TemplateTypeParmDecl>(FromParam))
3585       inheritDefaultTemplateArgument(Context, FTTP, ToParam);
3586     else if (auto *FNTTP = dyn_cast<NonTypeTemplateParmDecl>(FromParam))
3587       inheritDefaultTemplateArgument(Context, FNTTP, ToParam);
3588     else
3589       inheritDefaultTemplateArgument(
3590               Context, cast<TemplateTemplateParmDecl>(FromParam), ToParam);
3591   }
3592 }
3593 
3594 void ASTDeclReader::attachPreviousDecl(ASTReader &Reader, Decl *D,
3595                                        Decl *Previous, Decl *Canon) {
3596   assert(D && Previous);
3597 
3598   switch (D->getKind()) {
3599 #define ABSTRACT_DECL(TYPE)
3600 #define DECL(TYPE, BASE)                                                  \
3601   case Decl::TYPE:                                                        \
3602     attachPreviousDeclImpl(Reader, cast<TYPE##Decl>(D), Previous, Canon); \
3603     break;
3604 #include "clang/AST/DeclNodes.inc"
3605   }
3606 
3607   // If the declaration was visible in one module, a redeclaration of it in
3608   // another module remains visible even if it wouldn't be visible by itself.
3609   //
3610   // FIXME: In this case, the declaration should only be visible if a module
3611   //        that makes it visible has been imported.
3612   D->IdentifierNamespace |=
3613       Previous->IdentifierNamespace &
3614       (Decl::IDNS_Ordinary | Decl::IDNS_Tag | Decl::IDNS_Type);
3615 
3616   // If the declaration declares a template, it may inherit default arguments
3617   // from the previous declaration.
3618   if (auto *TD = dyn_cast<TemplateDecl>(D))
3619     inheritDefaultTemplateArguments(Reader.getContext(),
3620                                     cast<TemplateDecl>(Previous), TD);
3621 }
3622 
3623 template<typename DeclT>
3624 void ASTDeclReader::attachLatestDeclImpl(Redeclarable<DeclT> *D, Decl *Latest) {
3625   D->RedeclLink.setLatest(cast<DeclT>(Latest));
3626 }
3627 
3628 void ASTDeclReader::attachLatestDeclImpl(...) {
3629   llvm_unreachable("attachLatestDecl on non-redeclarable declaration");
3630 }
3631 
3632 void ASTDeclReader::attachLatestDecl(Decl *D, Decl *Latest) {
3633   assert(D && Latest);
3634 
3635   switch (D->getKind()) {
3636 #define ABSTRACT_DECL(TYPE)
3637 #define DECL(TYPE, BASE)                                  \
3638   case Decl::TYPE:                                        \
3639     attachLatestDeclImpl(cast<TYPE##Decl>(D), Latest); \
3640     break;
3641 #include "clang/AST/DeclNodes.inc"
3642   }
3643 }
3644 
3645 template<typename DeclT>
3646 void ASTDeclReader::markIncompleteDeclChainImpl(Redeclarable<DeclT> *D) {
3647   D->RedeclLink.markIncomplete();
3648 }
3649 
3650 void ASTDeclReader::markIncompleteDeclChainImpl(...) {
3651   llvm_unreachable("markIncompleteDeclChain on non-redeclarable declaration");
3652 }
3653 
3654 void ASTReader::markIncompleteDeclChain(Decl *D) {
3655   switch (D->getKind()) {
3656 #define ABSTRACT_DECL(TYPE)
3657 #define DECL(TYPE, BASE)                                             \
3658   case Decl::TYPE:                                                   \
3659     ASTDeclReader::markIncompleteDeclChainImpl(cast<TYPE##Decl>(D)); \
3660     break;
3661 #include "clang/AST/DeclNodes.inc"
3662   }
3663 }
3664 
3665 /// Read the declaration at the given offset from the AST file.
3666 Decl *ASTReader::ReadDeclRecord(DeclID ID) {
3667   unsigned Index = ID - NUM_PREDEF_DECL_IDS;
3668   SourceLocation DeclLoc;
3669   RecordLocation Loc = DeclCursorForID(ID, DeclLoc);
3670   llvm::BitstreamCursor &DeclsCursor = Loc.F->DeclsCursor;
3671   // Keep track of where we are in the stream, then jump back there
3672   // after reading this declaration.
3673   SavedStreamPosition SavedPosition(DeclsCursor);
3674 
3675   ReadingKindTracker ReadingKind(Read_Decl, *this);
3676 
3677   // Note that we are loading a declaration record.
3678   Deserializing ADecl(this);
3679 
3680   DeclsCursor.JumpToBit(Loc.Offset);
3681   ASTRecordReader Record(*this, *Loc.F);
3682   ASTDeclReader Reader(*this, Record, Loc, ID, DeclLoc);
3683   unsigned Code = DeclsCursor.ReadCode();
3684 
3685   ASTContext &Context = getContext();
3686   Decl *D = nullptr;
3687   switch ((DeclCode)Record.readRecord(DeclsCursor, Code)) {
3688   case DECL_CONTEXT_LEXICAL:
3689   case DECL_CONTEXT_VISIBLE:
3690     llvm_unreachable("Record cannot be de-serialized with ReadDeclRecord");
3691   case DECL_TYPEDEF:
3692     D = TypedefDecl::CreateDeserialized(Context, ID);
3693     break;
3694   case DECL_TYPEALIAS:
3695     D = TypeAliasDecl::CreateDeserialized(Context, ID);
3696     break;
3697   case DECL_ENUM:
3698     D = EnumDecl::CreateDeserialized(Context, ID);
3699     break;
3700   case DECL_RECORD:
3701     D = RecordDecl::CreateDeserialized(Context, ID);
3702     break;
3703   case DECL_ENUM_CONSTANT:
3704     D = EnumConstantDecl::CreateDeserialized(Context, ID);
3705     break;
3706   case DECL_FUNCTION:
3707     D = FunctionDecl::CreateDeserialized(Context, ID);
3708     break;
3709   case DECL_LINKAGE_SPEC:
3710     D = LinkageSpecDecl::CreateDeserialized(Context, ID);
3711     break;
3712   case DECL_EXPORT:
3713     D = ExportDecl::CreateDeserialized(Context, ID);
3714     break;
3715   case DECL_LABEL:
3716     D = LabelDecl::CreateDeserialized(Context, ID);
3717     break;
3718   case DECL_NAMESPACE:
3719     D = NamespaceDecl::CreateDeserialized(Context, ID);
3720     break;
3721   case DECL_NAMESPACE_ALIAS:
3722     D = NamespaceAliasDecl::CreateDeserialized(Context, ID);
3723     break;
3724   case DECL_USING:
3725     D = UsingDecl::CreateDeserialized(Context, ID);
3726     break;
3727   case DECL_USING_PACK:
3728     D = UsingPackDecl::CreateDeserialized(Context, ID, Record.readInt());
3729     break;
3730   case DECL_USING_SHADOW:
3731     D = UsingShadowDecl::CreateDeserialized(Context, ID);
3732     break;
3733   case DECL_CONSTRUCTOR_USING_SHADOW:
3734     D = ConstructorUsingShadowDecl::CreateDeserialized(Context, ID);
3735     break;
3736   case DECL_USING_DIRECTIVE:
3737     D = UsingDirectiveDecl::CreateDeserialized(Context, ID);
3738     break;
3739   case DECL_UNRESOLVED_USING_VALUE:
3740     D = UnresolvedUsingValueDecl::CreateDeserialized(Context, ID);
3741     break;
3742   case DECL_UNRESOLVED_USING_TYPENAME:
3743     D = UnresolvedUsingTypenameDecl::CreateDeserialized(Context, ID);
3744     break;
3745   case DECL_CXX_RECORD:
3746     D = CXXRecordDecl::CreateDeserialized(Context, ID);
3747     break;
3748   case DECL_CXX_DEDUCTION_GUIDE:
3749     D = CXXDeductionGuideDecl::CreateDeserialized(Context, ID);
3750     break;
3751   case DECL_CXX_METHOD:
3752     D = CXXMethodDecl::CreateDeserialized(Context, ID);
3753     break;
3754   case DECL_CXX_CONSTRUCTOR:
3755     D = CXXConstructorDecl::CreateDeserialized(Context, ID, Record.readInt());
3756     break;
3757   case DECL_CXX_DESTRUCTOR:
3758     D = CXXDestructorDecl::CreateDeserialized(Context, ID);
3759     break;
3760   case DECL_CXX_CONVERSION:
3761     D = CXXConversionDecl::CreateDeserialized(Context, ID);
3762     break;
3763   case DECL_ACCESS_SPEC:
3764     D = AccessSpecDecl::CreateDeserialized(Context, ID);
3765     break;
3766   case DECL_FRIEND:
3767     D = FriendDecl::CreateDeserialized(Context, ID, Record.readInt());
3768     break;
3769   case DECL_FRIEND_TEMPLATE:
3770     D = FriendTemplateDecl::CreateDeserialized(Context, ID);
3771     break;
3772   case DECL_CLASS_TEMPLATE:
3773     D = ClassTemplateDecl::CreateDeserialized(Context, ID);
3774     break;
3775   case DECL_CLASS_TEMPLATE_SPECIALIZATION:
3776     D = ClassTemplateSpecializationDecl::CreateDeserialized(Context, ID);
3777     break;
3778   case DECL_CLASS_TEMPLATE_PARTIAL_SPECIALIZATION:
3779     D = ClassTemplatePartialSpecializationDecl::CreateDeserialized(Context, ID);
3780     break;
3781   case DECL_VAR_TEMPLATE:
3782     D = VarTemplateDecl::CreateDeserialized(Context, ID);
3783     break;
3784   case DECL_VAR_TEMPLATE_SPECIALIZATION:
3785     D = VarTemplateSpecializationDecl::CreateDeserialized(Context, ID);
3786     break;
3787   case DECL_VAR_TEMPLATE_PARTIAL_SPECIALIZATION:
3788     D = VarTemplatePartialSpecializationDecl::CreateDeserialized(Context, ID);
3789     break;
3790   case DECL_CLASS_SCOPE_FUNCTION_SPECIALIZATION:
3791     D = ClassScopeFunctionSpecializationDecl::CreateDeserialized(Context, ID);
3792     break;
3793   case DECL_FUNCTION_TEMPLATE:
3794     D = FunctionTemplateDecl::CreateDeserialized(Context, ID);
3795     break;
3796   case DECL_TEMPLATE_TYPE_PARM:
3797     D = TemplateTypeParmDecl::CreateDeserialized(Context, ID);
3798     break;
3799   case DECL_NON_TYPE_TEMPLATE_PARM:
3800     D = NonTypeTemplateParmDecl::CreateDeserialized(Context, ID);
3801     break;
3802   case DECL_EXPANDED_NON_TYPE_TEMPLATE_PARM_PACK:
3803     D = NonTypeTemplateParmDecl::CreateDeserialized(Context, ID,
3804                                                     Record.readInt());
3805     break;
3806   case DECL_TEMPLATE_TEMPLATE_PARM:
3807     D = TemplateTemplateParmDecl::CreateDeserialized(Context, ID);
3808     break;
3809   case DECL_EXPANDED_TEMPLATE_TEMPLATE_PARM_PACK:
3810     D = TemplateTemplateParmDecl::CreateDeserialized(Context, ID,
3811                                                      Record.readInt());
3812     break;
3813   case DECL_TYPE_ALIAS_TEMPLATE:
3814     D = TypeAliasTemplateDecl::CreateDeserialized(Context, ID);
3815     break;
3816   case DECL_STATIC_ASSERT:
3817     D = StaticAssertDecl::CreateDeserialized(Context, ID);
3818     break;
3819   case DECL_OBJC_METHOD:
3820     D = ObjCMethodDecl::CreateDeserialized(Context, ID);
3821     break;
3822   case DECL_OBJC_INTERFACE:
3823     D = ObjCInterfaceDecl::CreateDeserialized(Context, ID);
3824     break;
3825   case DECL_OBJC_IVAR:
3826     D = ObjCIvarDecl::CreateDeserialized(Context, ID);
3827     break;
3828   case DECL_OBJC_PROTOCOL:
3829     D = ObjCProtocolDecl::CreateDeserialized(Context, ID);
3830     break;
3831   case DECL_OBJC_AT_DEFS_FIELD:
3832     D = ObjCAtDefsFieldDecl::CreateDeserialized(Context, ID);
3833     break;
3834   case DECL_OBJC_CATEGORY:
3835     D = ObjCCategoryDecl::CreateDeserialized(Context, ID);
3836     break;
3837   case DECL_OBJC_CATEGORY_IMPL:
3838     D = ObjCCategoryImplDecl::CreateDeserialized(Context, ID);
3839     break;
3840   case DECL_OBJC_IMPLEMENTATION:
3841     D = ObjCImplementationDecl::CreateDeserialized(Context, ID);
3842     break;
3843   case DECL_OBJC_COMPATIBLE_ALIAS:
3844     D = ObjCCompatibleAliasDecl::CreateDeserialized(Context, ID);
3845     break;
3846   case DECL_OBJC_PROPERTY:
3847     D = ObjCPropertyDecl::CreateDeserialized(Context, ID);
3848     break;
3849   case DECL_OBJC_PROPERTY_IMPL:
3850     D = ObjCPropertyImplDecl::CreateDeserialized(Context, ID);
3851     break;
3852   case DECL_FIELD:
3853     D = FieldDecl::CreateDeserialized(Context, ID);
3854     break;
3855   case DECL_INDIRECTFIELD:
3856     D = IndirectFieldDecl::CreateDeserialized(Context, ID);
3857     break;
3858   case DECL_VAR:
3859     D = VarDecl::CreateDeserialized(Context, ID);
3860     break;
3861   case DECL_IMPLICIT_PARAM:
3862     D = ImplicitParamDecl::CreateDeserialized(Context, ID);
3863     break;
3864   case DECL_PARM_VAR:
3865     D = ParmVarDecl::CreateDeserialized(Context, ID);
3866     break;
3867   case DECL_DECOMPOSITION:
3868     D = DecompositionDecl::CreateDeserialized(Context, ID, Record.readInt());
3869     break;
3870   case DECL_BINDING:
3871     D = BindingDecl::CreateDeserialized(Context, ID);
3872     break;
3873   case DECL_FILE_SCOPE_ASM:
3874     D = FileScopeAsmDecl::CreateDeserialized(Context, ID);
3875     break;
3876   case DECL_BLOCK:
3877     D = BlockDecl::CreateDeserialized(Context, ID);
3878     break;
3879   case DECL_MS_PROPERTY:
3880     D = MSPropertyDecl::CreateDeserialized(Context, ID);
3881     break;
3882   case DECL_CAPTURED:
3883     D = CapturedDecl::CreateDeserialized(Context, ID, Record.readInt());
3884     break;
3885   case DECL_CXX_BASE_SPECIFIERS:
3886     Error("attempt to read a C++ base-specifier record as a declaration");
3887     return nullptr;
3888   case DECL_CXX_CTOR_INITIALIZERS:
3889     Error("attempt to read a C++ ctor initializer record as a declaration");
3890     return nullptr;
3891   case DECL_IMPORT:
3892     // Note: last entry of the ImportDecl record is the number of stored source
3893     // locations.
3894     D = ImportDecl::CreateDeserialized(Context, ID, Record.back());
3895     break;
3896   case DECL_OMP_THREADPRIVATE:
3897     D = OMPThreadPrivateDecl::CreateDeserialized(Context, ID, Record.readInt());
3898     break;
3899   case DECL_OMP_ALLOCATE: {
3900     unsigned NumVars = Record.readInt();
3901     unsigned NumClauses = Record.readInt();
3902     D = OMPAllocateDecl::CreateDeserialized(Context, ID, NumVars, NumClauses);
3903     break;
3904   }
3905   case DECL_OMP_REQUIRES:
3906     D = OMPRequiresDecl::CreateDeserialized(Context, ID, Record.readInt());
3907     break;
3908   case DECL_OMP_DECLARE_REDUCTION:
3909     D = OMPDeclareReductionDecl::CreateDeserialized(Context, ID);
3910     break;
3911   case DECL_OMP_DECLARE_MAPPER:
3912     D = OMPDeclareMapperDecl::CreateDeserialized(Context, ID, Record.readInt());
3913     break;
3914   case DECL_OMP_CAPTUREDEXPR:
3915     D = OMPCapturedExprDecl::CreateDeserialized(Context, ID);
3916     break;
3917   case DECL_PRAGMA_COMMENT:
3918     D = PragmaCommentDecl::CreateDeserialized(Context, ID, Record.readInt());
3919     break;
3920   case DECL_PRAGMA_DETECT_MISMATCH:
3921     D = PragmaDetectMismatchDecl::CreateDeserialized(Context, ID,
3922                                                      Record.readInt());
3923     break;
3924   case DECL_EMPTY:
3925     D = EmptyDecl::CreateDeserialized(Context, ID);
3926     break;
3927   case DECL_OBJC_TYPE_PARAM:
3928     D = ObjCTypeParamDecl::CreateDeserialized(Context, ID);
3929     break;
3930   }
3931 
3932   assert(D && "Unknown declaration reading AST file");
3933   LoadedDecl(Index, D);
3934   // Set the DeclContext before doing any deserialization, to make sure internal
3935   // calls to Decl::getASTContext() by Decl's methods will find the
3936   // TranslationUnitDecl without crashing.
3937   D->setDeclContext(Context.getTranslationUnitDecl());
3938   Reader.Visit(D);
3939 
3940   // If this declaration is also a declaration context, get the
3941   // offsets for its tables of lexical and visible declarations.
3942   if (auto *DC = dyn_cast<DeclContext>(D)) {
3943     std::pair<uint64_t, uint64_t> Offsets = Reader.VisitDeclContext(DC);
3944     if (Offsets.first &&
3945         ReadLexicalDeclContextStorage(*Loc.F, DeclsCursor, Offsets.first, DC))
3946       return nullptr;
3947     if (Offsets.second &&
3948         ReadVisibleDeclContextStorage(*Loc.F, DeclsCursor, Offsets.second, ID))
3949       return nullptr;
3950   }
3951   assert(Record.getIdx() == Record.size());
3952 
3953   // Load any relevant update records.
3954   PendingUpdateRecords.push_back(
3955       PendingUpdateRecord(ID, D, /*JustLoaded=*/true));
3956 
3957   // Load the categories after recursive loading is finished.
3958   if (auto *Class = dyn_cast<ObjCInterfaceDecl>(D))
3959     // If we already have a definition when deserializing the ObjCInterfaceDecl,
3960     // we put the Decl in PendingDefinitions so we can pull the categories here.
3961     if (Class->isThisDeclarationADefinition() ||
3962         PendingDefinitions.count(Class))
3963       loadObjCCategories(ID, Class);
3964 
3965   // If we have deserialized a declaration that has a definition the
3966   // AST consumer might need to know about, queue it.
3967   // We don't pass it to the consumer immediately because we may be in recursive
3968   // loading, and some declarations may still be initializing.
3969   PotentiallyInterestingDecls.push_back(
3970       InterestingDecl(D, Reader.hasPendingBody()));
3971 
3972   return D;
3973 }
3974 
3975 void ASTReader::PassInterestingDeclsToConsumer() {
3976   assert(Consumer);
3977 
3978   if (PassingDeclsToConsumer)
3979     return;
3980 
3981   // Guard variable to avoid recursively redoing the process of passing
3982   // decls to consumer.
3983   SaveAndRestore<bool> GuardPassingDeclsToConsumer(PassingDeclsToConsumer,
3984                                                    true);
3985 
3986   // Ensure that we've loaded all potentially-interesting declarations
3987   // that need to be eagerly loaded.
3988   for (auto ID : EagerlyDeserializedDecls)
3989     GetDecl(ID);
3990   EagerlyDeserializedDecls.clear();
3991 
3992   while (!PotentiallyInterestingDecls.empty()) {
3993     InterestingDecl D = PotentiallyInterestingDecls.front();
3994     PotentiallyInterestingDecls.pop_front();
3995     if (isConsumerInterestedIn(getContext(), D.getDecl(), D.hasPendingBody()))
3996       PassInterestingDeclToConsumer(D.getDecl());
3997   }
3998 }
3999 
4000 void ASTReader::loadDeclUpdateRecords(PendingUpdateRecord &Record) {
4001   // The declaration may have been modified by files later in the chain.
4002   // If this is the case, read the record containing the updates from each file
4003   // and pass it to ASTDeclReader to make the modifications.
4004   serialization::GlobalDeclID ID = Record.ID;
4005   Decl *D = Record.D;
4006   ProcessingUpdatesRAIIObj ProcessingUpdates(*this);
4007   DeclUpdateOffsetsMap::iterator UpdI = DeclUpdateOffsets.find(ID);
4008 
4009   SmallVector<serialization::DeclID, 8> PendingLazySpecializationIDs;
4010 
4011   if (UpdI != DeclUpdateOffsets.end()) {
4012     auto UpdateOffsets = std::move(UpdI->second);
4013     DeclUpdateOffsets.erase(UpdI);
4014 
4015     // Check if this decl was interesting to the consumer. If we just loaded
4016     // the declaration, then we know it was interesting and we skip the call
4017     // to isConsumerInterestedIn because it is unsafe to call in the
4018     // current ASTReader state.
4019     bool WasInteresting =
4020         Record.JustLoaded || isConsumerInterestedIn(getContext(), D, false);
4021     for (auto &FileAndOffset : UpdateOffsets) {
4022       ModuleFile *F = FileAndOffset.first;
4023       uint64_t Offset = FileAndOffset.second;
4024       llvm::BitstreamCursor &Cursor = F->DeclsCursor;
4025       SavedStreamPosition SavedPosition(Cursor);
4026       Cursor.JumpToBit(Offset);
4027       unsigned Code = Cursor.ReadCode();
4028       ASTRecordReader Record(*this, *F);
4029       unsigned RecCode = Record.readRecord(Cursor, Code);
4030       (void)RecCode;
4031       assert(RecCode == DECL_UPDATES && "Expected DECL_UPDATES record!");
4032 
4033       ASTDeclReader Reader(*this, Record, RecordLocation(F, Offset), ID,
4034                            SourceLocation());
4035       Reader.UpdateDecl(D, PendingLazySpecializationIDs);
4036 
4037       // We might have made this declaration interesting. If so, remember that
4038       // we need to hand it off to the consumer.
4039       if (!WasInteresting &&
4040           isConsumerInterestedIn(getContext(), D, Reader.hasPendingBody())) {
4041         PotentiallyInterestingDecls.push_back(
4042             InterestingDecl(D, Reader.hasPendingBody()));
4043         WasInteresting = true;
4044       }
4045     }
4046   }
4047   // Add the lazy specializations to the template.
4048   assert((PendingLazySpecializationIDs.empty() || isa<ClassTemplateDecl>(D) ||
4049           isa<FunctionTemplateDecl>(D) || isa<VarTemplateDecl>(D)) &&
4050          "Must not have pending specializations");
4051   if (auto *CTD = dyn_cast<ClassTemplateDecl>(D))
4052     ASTDeclReader::AddLazySpecializations(CTD, PendingLazySpecializationIDs);
4053   else if (auto *FTD = dyn_cast<FunctionTemplateDecl>(D))
4054     ASTDeclReader::AddLazySpecializations(FTD, PendingLazySpecializationIDs);
4055   else if (auto *VTD = dyn_cast<VarTemplateDecl>(D))
4056     ASTDeclReader::AddLazySpecializations(VTD, PendingLazySpecializationIDs);
4057   PendingLazySpecializationIDs.clear();
4058 
4059   // Load the pending visible updates for this decl context, if it has any.
4060   auto I = PendingVisibleUpdates.find(ID);
4061   if (I != PendingVisibleUpdates.end()) {
4062     auto VisibleUpdates = std::move(I->second);
4063     PendingVisibleUpdates.erase(I);
4064 
4065     auto *DC = cast<DeclContext>(D)->getPrimaryContext();
4066     for (const auto &Update : VisibleUpdates)
4067       Lookups[DC].Table.add(
4068           Update.Mod, Update.Data,
4069           reader::ASTDeclContextNameLookupTrait(*this, *Update.Mod));
4070     DC->setHasExternalVisibleStorage(true);
4071   }
4072 }
4073 
4074 void ASTReader::loadPendingDeclChain(Decl *FirstLocal, uint64_t LocalOffset) {
4075   // Attach FirstLocal to the end of the decl chain.
4076   Decl *CanonDecl = FirstLocal->getCanonicalDecl();
4077   if (FirstLocal != CanonDecl) {
4078     Decl *PrevMostRecent = ASTDeclReader::getMostRecentDecl(CanonDecl);
4079     ASTDeclReader::attachPreviousDecl(
4080         *this, FirstLocal, PrevMostRecent ? PrevMostRecent : CanonDecl,
4081         CanonDecl);
4082   }
4083 
4084   if (!LocalOffset) {
4085     ASTDeclReader::attachLatestDecl(CanonDecl, FirstLocal);
4086     return;
4087   }
4088 
4089   // Load the list of other redeclarations from this module file.
4090   ModuleFile *M = getOwningModuleFile(FirstLocal);
4091   assert(M && "imported decl from no module file");
4092 
4093   llvm::BitstreamCursor &Cursor = M->DeclsCursor;
4094   SavedStreamPosition SavedPosition(Cursor);
4095   Cursor.JumpToBit(LocalOffset);
4096 
4097   RecordData Record;
4098   unsigned Code = Cursor.ReadCode();
4099   unsigned RecCode = Cursor.readRecord(Code, Record);
4100   (void)RecCode;
4101   assert(RecCode == LOCAL_REDECLARATIONS && "expected LOCAL_REDECLARATIONS record!");
4102 
4103   // FIXME: We have several different dispatches on decl kind here; maybe
4104   // we should instead generate one loop per kind and dispatch up-front?
4105   Decl *MostRecent = FirstLocal;
4106   for (unsigned I = 0, N = Record.size(); I != N; ++I) {
4107     auto *D = GetLocalDecl(*M, Record[N - I - 1]);
4108     ASTDeclReader::attachPreviousDecl(*this, D, MostRecent, CanonDecl);
4109     MostRecent = D;
4110   }
4111   ASTDeclReader::attachLatestDecl(CanonDecl, MostRecent);
4112 }
4113 
4114 namespace {
4115 
4116   /// Given an ObjC interface, goes through the modules and links to the
4117   /// interface all the categories for it.
4118   class ObjCCategoriesVisitor {
4119     ASTReader &Reader;
4120     ObjCInterfaceDecl *Interface;
4121     llvm::SmallPtrSetImpl<ObjCCategoryDecl *> &Deserialized;
4122     ObjCCategoryDecl *Tail = nullptr;
4123     llvm::DenseMap<DeclarationName, ObjCCategoryDecl *> NameCategoryMap;
4124     serialization::GlobalDeclID InterfaceID;
4125     unsigned PreviousGeneration;
4126 
4127     void add(ObjCCategoryDecl *Cat) {
4128       // Only process each category once.
4129       if (!Deserialized.erase(Cat))
4130         return;
4131 
4132       // Check for duplicate categories.
4133       if (Cat->getDeclName()) {
4134         ObjCCategoryDecl *&Existing = NameCategoryMap[Cat->getDeclName()];
4135         if (Existing &&
4136             Reader.getOwningModuleFile(Existing)
4137                                           != Reader.getOwningModuleFile(Cat)) {
4138           // FIXME: We should not warn for duplicates in diamond:
4139           //
4140           //   MT     //
4141           //  /  \    //
4142           // ML  MR   //
4143           //  \  /    //
4144           //   MB     //
4145           //
4146           // If there are duplicates in ML/MR, there will be warning when
4147           // creating MB *and* when importing MB. We should not warn when
4148           // importing.
4149           Reader.Diag(Cat->getLocation(), diag::warn_dup_category_def)
4150             << Interface->getDeclName() << Cat->getDeclName();
4151           Reader.Diag(Existing->getLocation(), diag::note_previous_definition);
4152         } else if (!Existing) {
4153           // Record this category.
4154           Existing = Cat;
4155         }
4156       }
4157 
4158       // Add this category to the end of the chain.
4159       if (Tail)
4160         ASTDeclReader::setNextObjCCategory(Tail, Cat);
4161       else
4162         Interface->setCategoryListRaw(Cat);
4163       Tail = Cat;
4164     }
4165 
4166   public:
4167     ObjCCategoriesVisitor(ASTReader &Reader,
4168                           ObjCInterfaceDecl *Interface,
4169                           llvm::SmallPtrSetImpl<ObjCCategoryDecl *> &Deserialized,
4170                           serialization::GlobalDeclID InterfaceID,
4171                           unsigned PreviousGeneration)
4172         : Reader(Reader), Interface(Interface), Deserialized(Deserialized),
4173           InterfaceID(InterfaceID), PreviousGeneration(PreviousGeneration) {
4174       // Populate the name -> category map with the set of known categories.
4175       for (auto *Cat : Interface->known_categories()) {
4176         if (Cat->getDeclName())
4177           NameCategoryMap[Cat->getDeclName()] = Cat;
4178 
4179         // Keep track of the tail of the category list.
4180         Tail = Cat;
4181       }
4182     }
4183 
4184     bool operator()(ModuleFile &M) {
4185       // If we've loaded all of the category information we care about from
4186       // this module file, we're done.
4187       if (M.Generation <= PreviousGeneration)
4188         return true;
4189 
4190       // Map global ID of the definition down to the local ID used in this
4191       // module file. If there is no such mapping, we'll find nothing here
4192       // (or in any module it imports).
4193       DeclID LocalID = Reader.mapGlobalIDToModuleFileGlobalID(M, InterfaceID);
4194       if (!LocalID)
4195         return true;
4196 
4197       // Perform a binary search to find the local redeclarations for this
4198       // declaration (if any).
4199       const ObjCCategoriesInfo Compare = { LocalID, 0 };
4200       const ObjCCategoriesInfo *Result
4201         = std::lower_bound(M.ObjCCategoriesMap,
4202                            M.ObjCCategoriesMap + M.LocalNumObjCCategoriesInMap,
4203                            Compare);
4204       if (Result == M.ObjCCategoriesMap + M.LocalNumObjCCategoriesInMap ||
4205           Result->DefinitionID != LocalID) {
4206         // We didn't find anything. If the class definition is in this module
4207         // file, then the module files it depends on cannot have any categories,
4208         // so suppress further lookup.
4209         return Reader.isDeclIDFromModule(InterfaceID, M);
4210       }
4211 
4212       // We found something. Dig out all of the categories.
4213       unsigned Offset = Result->Offset;
4214       unsigned N = M.ObjCCategories[Offset];
4215       M.ObjCCategories[Offset++] = 0; // Don't try to deserialize again
4216       for (unsigned I = 0; I != N; ++I)
4217         add(cast_or_null<ObjCCategoryDecl>(
4218               Reader.GetLocalDecl(M, M.ObjCCategories[Offset++])));
4219       return true;
4220     }
4221   };
4222 
4223 } // namespace
4224 
4225 void ASTReader::loadObjCCategories(serialization::GlobalDeclID ID,
4226                                    ObjCInterfaceDecl *D,
4227                                    unsigned PreviousGeneration) {
4228   ObjCCategoriesVisitor Visitor(*this, D, CategoriesDeserialized, ID,
4229                                 PreviousGeneration);
4230   ModuleMgr.visit(Visitor);
4231 }
4232 
4233 template<typename DeclT, typename Fn>
4234 static void forAllLaterRedecls(DeclT *D, Fn F) {
4235   F(D);
4236 
4237   // Check whether we've already merged D into its redeclaration chain.
4238   // MostRecent may or may not be nullptr if D has not been merged. If
4239   // not, walk the merged redecl chain and see if it's there.
4240   auto *MostRecent = D->getMostRecentDecl();
4241   bool Found = false;
4242   for (auto *Redecl = MostRecent; Redecl && !Found;
4243        Redecl = Redecl->getPreviousDecl())
4244     Found = (Redecl == D);
4245 
4246   // If this declaration is merged, apply the functor to all later decls.
4247   if (Found) {
4248     for (auto *Redecl = MostRecent; Redecl != D;
4249          Redecl = Redecl->getPreviousDecl())
4250       F(Redecl);
4251   }
4252 }
4253 
4254 void ASTDeclReader::UpdateDecl(Decl *D,
4255    llvm::SmallVectorImpl<serialization::DeclID> &PendingLazySpecializationIDs) {
4256   while (Record.getIdx() < Record.size()) {
4257     switch ((DeclUpdateKind)Record.readInt()) {
4258     case UPD_CXX_ADDED_IMPLICIT_MEMBER: {
4259       auto *RD = cast<CXXRecordDecl>(D);
4260       // FIXME: If we also have an update record for instantiating the
4261       // definition of D, we need that to happen before we get here.
4262       Decl *MD = Record.readDecl();
4263       assert(MD && "couldn't read decl from update record");
4264       // FIXME: We should call addHiddenDecl instead, to add the member
4265       // to its DeclContext.
4266       RD->addedMember(MD);
4267       break;
4268     }
4269 
4270     case UPD_CXX_ADDED_TEMPLATE_SPECIALIZATION:
4271       // It will be added to the template's lazy specialization set.
4272       PendingLazySpecializationIDs.push_back(ReadDeclID());
4273       break;
4274 
4275     case UPD_CXX_ADDED_ANONYMOUS_NAMESPACE: {
4276       auto *Anon = ReadDeclAs<NamespaceDecl>();
4277 
4278       // Each module has its own anonymous namespace, which is disjoint from
4279       // any other module's anonymous namespaces, so don't attach the anonymous
4280       // namespace at all.
4281       if (!Record.isModule()) {
4282         if (auto *TU = dyn_cast<TranslationUnitDecl>(D))
4283           TU->setAnonymousNamespace(Anon);
4284         else
4285           cast<NamespaceDecl>(D)->setAnonymousNamespace(Anon);
4286       }
4287       break;
4288     }
4289 
4290     case UPD_CXX_ADDED_VAR_DEFINITION: {
4291       auto *VD = cast<VarDecl>(D);
4292       VD->NonParmVarDeclBits.IsInline = Record.readInt();
4293       VD->NonParmVarDeclBits.IsInlineSpecified = Record.readInt();
4294       uint64_t Val = Record.readInt();
4295       if (Val && !VD->getInit()) {
4296         VD->setInit(Record.readExpr());
4297         if (Val > 1) { // IsInitKnownICE = 1, IsInitNotICE = 2, IsInitICE = 3
4298           EvaluatedStmt *Eval = VD->ensureEvaluatedStmt();
4299           Eval->CheckedICE = true;
4300           Eval->IsICE = Val == 3;
4301         }
4302       }
4303       break;
4304     }
4305 
4306     case UPD_CXX_POINT_OF_INSTANTIATION: {
4307       SourceLocation POI = Record.readSourceLocation();
4308       if (auto *VTSD = dyn_cast<VarTemplateSpecializationDecl>(D)) {
4309         VTSD->setPointOfInstantiation(POI);
4310       } else if (auto *VD = dyn_cast<VarDecl>(D)) {
4311         VD->getMemberSpecializationInfo()->setPointOfInstantiation(POI);
4312       } else {
4313         auto *FD = cast<FunctionDecl>(D);
4314         if (auto *FTSInfo = FD->TemplateOrSpecialization
4315                     .dyn_cast<FunctionTemplateSpecializationInfo *>())
4316           FTSInfo->setPointOfInstantiation(POI);
4317         else
4318           FD->TemplateOrSpecialization.get<MemberSpecializationInfo *>()
4319               ->setPointOfInstantiation(POI);
4320       }
4321       break;
4322     }
4323 
4324     case UPD_CXX_INSTANTIATED_DEFAULT_ARGUMENT: {
4325       auto *Param = cast<ParmVarDecl>(D);
4326 
4327       // We have to read the default argument regardless of whether we use it
4328       // so that hypothetical further update records aren't messed up.
4329       // TODO: Add a function to skip over the next expr record.
4330       auto *DefaultArg = Record.readExpr();
4331 
4332       // Only apply the update if the parameter still has an uninstantiated
4333       // default argument.
4334       if (Param->hasUninstantiatedDefaultArg())
4335         Param->setDefaultArg(DefaultArg);
4336       break;
4337     }
4338 
4339     case UPD_CXX_INSTANTIATED_DEFAULT_MEMBER_INITIALIZER: {
4340       auto *FD = cast<FieldDecl>(D);
4341       auto *DefaultInit = Record.readExpr();
4342 
4343       // Only apply the update if the field still has an uninstantiated
4344       // default member initializer.
4345       if (FD->hasInClassInitializer() && !FD->getInClassInitializer()) {
4346         if (DefaultInit)
4347           FD->setInClassInitializer(DefaultInit);
4348         else
4349           // Instantiation failed. We can get here if we serialized an AST for
4350           // an invalid program.
4351           FD->removeInClassInitializer();
4352       }
4353       break;
4354     }
4355 
4356     case UPD_CXX_ADDED_FUNCTION_DEFINITION: {
4357       auto *FD = cast<FunctionDecl>(D);
4358       if (Reader.PendingBodies[FD]) {
4359         // FIXME: Maybe check for ODR violations.
4360         // It's safe to stop now because this update record is always last.
4361         return;
4362       }
4363 
4364       if (Record.readInt()) {
4365         // Maintain AST consistency: any later redeclarations of this function
4366         // are inline if this one is. (We might have merged another declaration
4367         // into this one.)
4368         forAllLaterRedecls(FD, [](FunctionDecl *FD) {
4369           FD->setImplicitlyInline();
4370         });
4371       }
4372       FD->setInnerLocStart(ReadSourceLocation());
4373       ReadFunctionDefinition(FD);
4374       assert(Record.getIdx() == Record.size() && "lazy body must be last");
4375       break;
4376     }
4377 
4378     case UPD_CXX_INSTANTIATED_CLASS_DEFINITION: {
4379       auto *RD = cast<CXXRecordDecl>(D);
4380       auto *OldDD = RD->getCanonicalDecl()->DefinitionData;
4381       bool HadRealDefinition =
4382           OldDD && (OldDD->Definition != RD ||
4383                     !Reader.PendingFakeDefinitionData.count(OldDD));
4384       RD->setParamDestroyedInCallee(Record.readInt());
4385       RD->setArgPassingRestrictions(
4386           (RecordDecl::ArgPassingKind)Record.readInt());
4387       ReadCXXRecordDefinition(RD, /*Update*/true);
4388 
4389       // Visible update is handled separately.
4390       uint64_t LexicalOffset = ReadLocalOffset();
4391       if (!HadRealDefinition && LexicalOffset) {
4392         Record.readLexicalDeclContextStorage(LexicalOffset, RD);
4393         Reader.PendingFakeDefinitionData.erase(OldDD);
4394       }
4395 
4396       auto TSK = (TemplateSpecializationKind)Record.readInt();
4397       SourceLocation POI = ReadSourceLocation();
4398       if (MemberSpecializationInfo *MSInfo =
4399               RD->getMemberSpecializationInfo()) {
4400         MSInfo->setTemplateSpecializationKind(TSK);
4401         MSInfo->setPointOfInstantiation(POI);
4402       } else {
4403         auto *Spec = cast<ClassTemplateSpecializationDecl>(RD);
4404         Spec->setTemplateSpecializationKind(TSK);
4405         Spec->setPointOfInstantiation(POI);
4406 
4407         if (Record.readInt()) {
4408           auto *PartialSpec =
4409               ReadDeclAs<ClassTemplatePartialSpecializationDecl>();
4410           SmallVector<TemplateArgument, 8> TemplArgs;
4411           Record.readTemplateArgumentList(TemplArgs);
4412           auto *TemplArgList = TemplateArgumentList::CreateCopy(
4413               Reader.getContext(), TemplArgs);
4414 
4415           // FIXME: If we already have a partial specialization set,
4416           // check that it matches.
4417           if (!Spec->getSpecializedTemplateOrPartial()
4418                    .is<ClassTemplatePartialSpecializationDecl *>())
4419             Spec->setInstantiationOf(PartialSpec, TemplArgList);
4420         }
4421       }
4422 
4423       RD->setTagKind((TagTypeKind)Record.readInt());
4424       RD->setLocation(ReadSourceLocation());
4425       RD->setLocStart(ReadSourceLocation());
4426       RD->setBraceRange(ReadSourceRange());
4427 
4428       if (Record.readInt()) {
4429         AttrVec Attrs;
4430         Record.readAttributes(Attrs);
4431         // If the declaration already has attributes, we assume that some other
4432         // AST file already loaded them.
4433         if (!D->hasAttrs())
4434           D->setAttrsImpl(Attrs, Reader.getContext());
4435       }
4436       break;
4437     }
4438 
4439     case UPD_CXX_RESOLVED_DTOR_DELETE: {
4440       // Set the 'operator delete' directly to avoid emitting another update
4441       // record.
4442       auto *Del = ReadDeclAs<FunctionDecl>();
4443       auto *First = cast<CXXDestructorDecl>(D->getCanonicalDecl());
4444       auto *ThisArg = Record.readExpr();
4445       // FIXME: Check consistency if we have an old and new operator delete.
4446       if (!First->OperatorDelete) {
4447         First->OperatorDelete = Del;
4448         First->OperatorDeleteThisArg = ThisArg;
4449       }
4450       break;
4451     }
4452 
4453     case UPD_CXX_RESOLVED_EXCEPTION_SPEC: {
4454       FunctionProtoType::ExceptionSpecInfo ESI;
4455       SmallVector<QualType, 8> ExceptionStorage;
4456       Record.readExceptionSpec(ExceptionStorage, ESI);
4457 
4458       // Update this declaration's exception specification, if needed.
4459       auto *FD = cast<FunctionDecl>(D);
4460       auto *FPT = FD->getType()->castAs<FunctionProtoType>();
4461       // FIXME: If the exception specification is already present, check that it
4462       // matches.
4463       if (isUnresolvedExceptionSpec(FPT->getExceptionSpecType())) {
4464         FD->setType(Reader.getContext().getFunctionType(
4465             FPT->getReturnType(), FPT->getParamTypes(),
4466             FPT->getExtProtoInfo().withExceptionSpec(ESI)));
4467 
4468         // When we get to the end of deserializing, see if there are other decls
4469         // that we need to propagate this exception specification onto.
4470         Reader.PendingExceptionSpecUpdates.insert(
4471             std::make_pair(FD->getCanonicalDecl(), FD));
4472       }
4473       break;
4474     }
4475 
4476     case UPD_CXX_DEDUCED_RETURN_TYPE: {
4477       auto *FD = cast<FunctionDecl>(D);
4478       QualType DeducedResultType = Record.readType();
4479       Reader.PendingDeducedTypeUpdates.insert(
4480           {FD->getCanonicalDecl(), DeducedResultType});
4481       break;
4482     }
4483 
4484     case UPD_DECL_MARKED_USED:
4485       // Maintain AST consistency: any later redeclarations are used too.
4486       D->markUsed(Reader.getContext());
4487       break;
4488 
4489     case UPD_MANGLING_NUMBER:
4490       Reader.getContext().setManglingNumber(cast<NamedDecl>(D),
4491                                             Record.readInt());
4492       break;
4493 
4494     case UPD_STATIC_LOCAL_NUMBER:
4495       Reader.getContext().setStaticLocalNumber(cast<VarDecl>(D),
4496                                                Record.readInt());
4497       break;
4498 
4499     case UPD_DECL_MARKED_OPENMP_THREADPRIVATE:
4500       D->addAttr(OMPThreadPrivateDeclAttr::CreateImplicit(Reader.getContext(),
4501                                                           ReadSourceRange()));
4502       break;
4503 
4504     case UPD_DECL_MARKED_OPENMP_ALLOCATE: {
4505       auto AllocatorKind =
4506           static_cast<OMPAllocateDeclAttr::AllocatorTypeTy>(Record.readInt());
4507       Expr *Allocator = Record.readExpr();
4508       SourceRange SR = ReadSourceRange();
4509       D->addAttr(OMPAllocateDeclAttr::CreateImplicit(
4510           Reader.getContext(), AllocatorKind, Allocator, SR));
4511       break;
4512     }
4513 
4514     case UPD_DECL_EXPORTED: {
4515       unsigned SubmoduleID = readSubmoduleID();
4516       auto *Exported = cast<NamedDecl>(D);
4517       Module *Owner = SubmoduleID ? Reader.getSubmodule(SubmoduleID) : nullptr;
4518       Reader.getContext().mergeDefinitionIntoModule(Exported, Owner);
4519       Reader.PendingMergedDefinitionsToDeduplicate.insert(Exported);
4520       break;
4521     }
4522 
4523     case UPD_DECL_MARKED_OPENMP_DECLARETARGET:
4524       D->addAttr(OMPDeclareTargetDeclAttr::CreateImplicit(
4525           Reader.getContext(),
4526           static_cast<OMPDeclareTargetDeclAttr::MapTypeTy>(Record.readInt()),
4527           ReadSourceRange()));
4528       break;
4529 
4530     case UPD_ADDED_ATTR_TO_RECORD:
4531       AttrVec Attrs;
4532       Record.readAttributes(Attrs);
4533       assert(Attrs.size() == 1);
4534       D->addAttr(Attrs[0]);
4535       break;
4536     }
4537   }
4538 }
4539