1 //===- ExternalASTMerger.cpp - Merging External AST Interface ---*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements the ExternalASTMerger, which vends a combination of
11 // ASTs from several different ASTContext/FileManager pairs
13 //===----------------------------------------------------------------------===//
15 #include "clang/AST/ASTContext.h"
16 #include "clang/AST/Decl.h"
17 #include "clang/AST/DeclCXX.h"
18 #include "clang/AST/DeclObjC.h"
19 #include "clang/AST/DeclTemplate.h"
20 #include "clang/AST/ExternalASTMerger.h"
22 using namespace clang;
26 template <typename T> struct Source {
29 operator T() { return t; }
30 template <typename U = T> U &get() { return t; }
31 template <typename U = T> const U &get() const { return t; }
32 template <typename U> operator Source<U>() { return Source<U>(t); }
35 typedef std::pair<Source<NamedDecl *>, ASTImporter *> Candidate;
37 /// For the given DC, return the DC that is safe to perform lookups on. This is
38 /// the DC we actually want to work with most of the time.
39 const DeclContext *CanonicalizeDC(const DeclContext *DC) {
40 if (isa<LinkageSpecDecl>(DC))
41 return DC->getRedeclContext();
45 Source<const DeclContext *>
46 LookupSameContext(Source<TranslationUnitDecl *> SourceTU, const DeclContext *DC,
47 ASTImporter &ReverseImporter) {
48 DC = CanonicalizeDC(DC);
49 if (DC->isTranslationUnit()) {
52 Source<const DeclContext *> SourceParentDC =
53 LookupSameContext(SourceTU, DC->getParent(), ReverseImporter);
54 if (!SourceParentDC) {
55 // If we couldn't find the parent DC in this TranslationUnit, give up.
58 auto *ND = cast<NamedDecl>(DC);
59 DeclarationName Name = ND->getDeclName();
60 Source<DeclarationName> SourceName = ReverseImporter.Import(Name);
61 DeclContext::lookup_result SearchResult =
62 SourceParentDC.get()->lookup(SourceName.get());
63 size_t SearchResultSize = SearchResult.size();
64 if (SearchResultSize == 0 || SearchResultSize > 1) {
65 // There are two cases here. First, we might not find the name.
66 // We might also find multiple copies, in which case we have no
67 // guarantee that the one we wanted is the one we pick. (E.g.,
68 // if we have two specializations of the same template it is
69 // very hard to determine which is the one you want.)
71 // The Origins map fixes this problem by allowing the origin to be
72 // explicitly recorded, so we trigger that recording by returning
73 // nothing (rather than a possibly-inaccurate guess) here.
76 NamedDecl *SearchResultDecl = SearchResult[0];
77 if (isa<DeclContext>(SearchResultDecl) &&
78 SearchResultDecl->getKind() == DC->getDeclKind())
79 return cast<DeclContext>(SearchResultDecl)->getPrimaryContext();
80 return nullptr; // This type of lookup is unsupported
84 /// A custom implementation of ASTImporter, for ExternalASTMerger's purposes.
86 /// There are several modifications:
88 /// - It enables lazy lookup (via the HasExternalLexicalStorage flag and a few
89 /// others), which instructs Clang to refer to ExternalASTMerger. Also, it
90 /// forces MinimalImport to true, which is necessary to make this work.
91 /// - It maintains a reverse importer for use with names. This allows lookup of
92 /// arbitrary names in the source context.
93 /// - It updates the ExternalASTMerger's origin map as needed whenever a
94 /// it sees a DeclContext.
95 class LazyASTImporter : public ASTImporter {
97 ExternalASTMerger &Parent;
99 const ExternalASTMerger::OriginMap &FromOrigins;
101 llvm::raw_ostream &logs() { return Parent.logs(); }
103 LazyASTImporter(ExternalASTMerger &_Parent, ASTContext &ToContext,
104 FileManager &ToFileManager, ASTContext &FromContext,
105 FileManager &FromFileManager,
106 const ExternalASTMerger::OriginMap &_FromOrigins)
107 : ASTImporter(ToContext, ToFileManager, FromContext, FromFileManager,
108 /*MinimalImport=*/true),
109 Parent(_Parent), Reverse(FromContext, FromFileManager, ToContext,
110 ToFileManager, /*MinimalImport=*/true), FromOrigins(_FromOrigins) {}
112 /// Whenever a DeclContext is imported, ensure that ExternalASTSource's origin
113 /// map is kept up to date. Also set the appropriate flags.
114 Decl *Imported(Decl *From, Decl *To) override {
115 if (auto *ToDC = dyn_cast<DeclContext>(To)) {
116 const bool LoggingEnabled = Parent.LoggingEnabled();
118 logs() << "(ExternalASTMerger*)" << (void*)&Parent
119 << " imported (DeclContext*)" << (void*)ToDC
120 << ", (ASTContext*)" << (void*)&getToContext()
121 << " from (DeclContext*)" << (void*)llvm::cast<DeclContext>(From)
122 << ", (ASTContext*)" << (void*)&getFromContext()
124 Source<DeclContext *> FromDC(
125 cast<DeclContext>(From)->getPrimaryContext());
126 if (FromOrigins.count(FromDC) &&
127 Parent.HasImporterForOrigin(*FromOrigins.at(FromDC).AST)) {
129 logs() << "(ExternalASTMerger*)" << (void*)&Parent
130 << " forced origin (DeclContext*)"
131 << (void*)FromOrigins.at(FromDC).DC
133 << (void*)FromOrigins.at(FromDC).AST
135 Parent.ForceRecordOrigin(ToDC, FromOrigins.at(FromDC));
138 logs() << "(ExternalASTMerger*)" << (void*)&Parent
139 << " maybe recording origin (DeclContext*)" << (void*)FromDC
140 << ", (ASTContext*)" << (void*)&getFromContext()
142 Parent.MaybeRecordOrigin(ToDC, {FromDC, &getFromContext()});
145 if (auto *ToTag = dyn_cast<TagDecl>(To)) {
146 ToTag->setHasExternalLexicalStorage();
147 ToTag->getPrimaryContext()->setMustBuildLookupTable();
148 assert(Parent.CanComplete(ToTag));
149 } else if (auto *ToNamespace = dyn_cast<NamespaceDecl>(To)) {
150 ToNamespace->setHasExternalVisibleStorage();
151 assert(Parent.CanComplete(ToNamespace));
152 } else if (auto *ToContainer = dyn_cast<ObjCContainerDecl>(To)) {
153 ToContainer->setHasExternalLexicalStorage();
154 ToContainer->getPrimaryContext()->setMustBuildLookupTable();
155 assert(Parent.CanComplete(ToContainer));
159 ASTImporter &GetReverse() { return Reverse; }
162 bool HasDeclOfSameType(llvm::ArrayRef<Candidate> Decls, const Candidate &C) {
163 if (isa<FunctionDecl>(C.first.get()))
165 return llvm::any_of(Decls, [&](const Candidate &D) {
166 return C.first.get()->getKind() == D.first.get()->getKind();
172 ASTImporter &ExternalASTMerger::ImporterForOrigin(ASTContext &OriginContext) {
173 for (const std::unique_ptr<ASTImporter> &I : Importers)
174 if (&I->getFromContext() == &OriginContext)
176 llvm_unreachable("We should have an importer for this origin!");
180 LazyASTImporter &LazyImporterForOrigin(ExternalASTMerger &Merger,
181 ASTContext &OriginContext) {
182 return static_cast<LazyASTImporter &>(
183 Merger.ImporterForOrigin(OriginContext));
187 bool ExternalASTMerger::HasImporterForOrigin(ASTContext &OriginContext) {
188 for (const std::unique_ptr<ASTImporter> &I : Importers)
189 if (&I->getFromContext() == &OriginContext)
194 template <typename CallbackType>
195 void ExternalASTMerger::ForEachMatchingDC(const DeclContext *DC,
196 CallbackType Callback) {
197 if (Origins.count(DC)) {
198 ExternalASTMerger::DCOrigin Origin = Origins[DC];
199 LazyASTImporter &Importer = LazyImporterForOrigin(*this, *Origin.AST);
200 Callback(Importer, Importer.GetReverse(), Origin.DC);
202 bool DidCallback = false;
203 for (const std::unique_ptr<ASTImporter> &Importer : Importers) {
204 Source<TranslationUnitDecl *> SourceTU =
205 Importer->getFromContext().getTranslationUnitDecl();
206 ASTImporter &Reverse =
207 static_cast<LazyASTImporter *>(Importer.get())->GetReverse();
208 if (auto SourceDC = LookupSameContext(SourceTU, DC, Reverse)) {
210 if (Callback(*Importer, Reverse, SourceDC))
214 if (!DidCallback && LoggingEnabled())
215 logs() << "(ExternalASTMerger*)" << (void*)this
216 << " asserting for (DeclContext*)" << (const void*)DC
217 << ", (ASTContext*)" << (void*)&Target.AST
219 assert(DidCallback && "Couldn't find a source context matching our DC");
223 void ExternalASTMerger::CompleteType(TagDecl *Tag) {
224 assert(Tag->hasExternalLexicalStorage());
225 ForEachMatchingDC(Tag, [&](ASTImporter &Forward, ASTImporter &Reverse,
226 Source<const DeclContext *> SourceDC) -> bool {
227 auto *SourceTag = const_cast<TagDecl *>(cast<TagDecl>(SourceDC.get()));
228 if (SourceTag->hasExternalLexicalStorage())
229 SourceTag->getASTContext().getExternalSource()->CompleteType(SourceTag);
230 if (!SourceTag->getDefinition())
232 Forward.MapImported(SourceTag, Tag);
233 if (llvm::Error Err = Forward.ImportDefinition_New(SourceTag))
234 llvm::consumeError(std::move(Err));
235 Tag->setCompleteDefinition(SourceTag->isCompleteDefinition());
240 void ExternalASTMerger::CompleteType(ObjCInterfaceDecl *Interface) {
241 assert(Interface->hasExternalLexicalStorage());
243 Interface, [&](ASTImporter &Forward, ASTImporter &Reverse,
244 Source<const DeclContext *> SourceDC) -> bool {
245 auto *SourceInterface = const_cast<ObjCInterfaceDecl *>(
246 cast<ObjCInterfaceDecl>(SourceDC.get()));
247 if (SourceInterface->hasExternalLexicalStorage())
248 SourceInterface->getASTContext().getExternalSource()->CompleteType(
250 if (!SourceInterface->getDefinition())
252 Forward.MapImported(SourceInterface, Interface);
253 if (llvm::Error Err = Forward.ImportDefinition_New(SourceInterface))
254 llvm::consumeError(std::move(Err));
259 bool ExternalASTMerger::CanComplete(DeclContext *Interface) {
260 assert(Interface->hasExternalLexicalStorage() ||
261 Interface->hasExternalVisibleStorage());
262 bool FoundMatchingDC = false;
263 ForEachMatchingDC(Interface,
264 [&](ASTImporter &Forward, ASTImporter &Reverse,
265 Source<const DeclContext *> SourceDC) -> bool {
266 FoundMatchingDC = true;
269 return FoundMatchingDC;
273 bool IsSameDC(const DeclContext *D1, const DeclContext *D2) {
274 if (isa<ObjCContainerDecl>(D1) && isa<ObjCContainerDecl>(D2))
275 return true; // There are many cases where Objective-C is ambiguous.
276 if (auto *T1 = dyn_cast<TagDecl>(D1))
277 if (auto *T2 = dyn_cast<TagDecl>(D2))
278 if (T1->getFirstDecl() == T2->getFirstDecl())
280 return D1 == D2 || D1 == CanonicalizeDC(D2);
284 void ExternalASTMerger::MaybeRecordOrigin(const DeclContext *ToDC,
286 LazyASTImporter &Importer = LazyImporterForOrigin(*this, *Origin.AST);
287 ASTImporter &Reverse = Importer.GetReverse();
288 Source<const DeclContext *> FoundFromDC =
289 LookupSameContext(Origin.AST->getTranslationUnitDecl(), ToDC, Reverse);
290 const bool DoRecord = !FoundFromDC || !IsSameDC(FoundFromDC.get(), Origin.DC);
292 RecordOriginImpl(ToDC, Origin, Importer);
293 if (LoggingEnabled())
294 logs() << "(ExternalASTMerger*)" << (void*)this
295 << (DoRecord ? " decided " : " decided NOT")
296 << " to record origin (DeclContext*)" << (void*)Origin.DC
297 << ", (ASTContext*)" << (void*)&Origin.AST
301 void ExternalASTMerger::ForceRecordOrigin(const DeclContext *ToDC,
303 RecordOriginImpl(ToDC, Origin, ImporterForOrigin(*Origin.AST));
306 void ExternalASTMerger::RecordOriginImpl(const DeclContext *ToDC, DCOrigin Origin,
307 ASTImporter &Importer) {
308 Origins[ToDC] = Origin;
309 Importer.ASTImporter::MapImported(cast<Decl>(Origin.DC), const_cast<Decl*>(cast<Decl>(ToDC)));
312 ExternalASTMerger::ExternalASTMerger(const ImporterTarget &Target,
313 llvm::ArrayRef<ImporterSource> Sources) : LogStream(&llvm::nulls()), Target(Target) {
317 void ExternalASTMerger::AddSources(llvm::ArrayRef<ImporterSource> Sources) {
318 for (const ImporterSource &S : Sources) {
319 assert(&S.AST != &Target.AST);
320 Importers.push_back(llvm::make_unique<LazyASTImporter>(
321 *this, Target.AST, Target.FM, S.AST, S.FM, S.OM));
325 void ExternalASTMerger::RemoveSources(llvm::ArrayRef<ImporterSource> Sources) {
326 if (LoggingEnabled())
327 for (const ImporterSource &S : Sources)
328 logs() << "(ExternalASTMerger*)" << (void*)this
329 << " removing source (ASTContext*)" << (void*)&S.AST
332 std::remove_if(Importers.begin(), Importers.end(),
333 [&Sources](std::unique_ptr<ASTImporter> &Importer) -> bool {
334 for (const ImporterSource &S : Sources) {
335 if (&Importer->getFromContext() == &S.AST)
341 for (OriginMap::iterator OI = Origins.begin(), OE = Origins.end(); OI != OE; ) {
342 std::pair<const DeclContext *, DCOrigin> Origin = *OI;
344 for (const ImporterSource &S : Sources) {
345 if (&S.AST == Origin.second.AST) {
351 OI = Origins.erase(OI);
357 template <typename DeclTy>
358 static bool importSpecializations(DeclTy *D, ASTImporter *Importer) {
359 for (auto *Spec : D->specializations())
360 if (!Importer->Import(Spec))
365 /// Imports specializations from template declarations that can be specialized.
366 static bool importSpecializationsIfNeeded(Decl *D, ASTImporter *Importer) {
367 if (!isa<TemplateDecl>(D))
369 if (auto *FunctionTD = dyn_cast<FunctionTemplateDecl>(D))
370 return importSpecializations(FunctionTD, Importer);
371 else if (auto *ClassTD = dyn_cast<ClassTemplateDecl>(D))
372 return importSpecializations(ClassTD, Importer);
373 else if (auto *VarTD = dyn_cast<VarTemplateDecl>(D))
374 return importSpecializations(VarTD, Importer);
378 bool ExternalASTMerger::FindExternalVisibleDeclsByName(const DeclContext *DC,
379 DeclarationName Name) {
380 llvm::SmallVector<NamedDecl *, 1> Decls;
381 llvm::SmallVector<Candidate, 4> Candidates;
383 auto FilterFoundDecl = [&Candidates](const Candidate &C) {
384 if (!HasDeclOfSameType(Candidates, C))
385 Candidates.push_back(C);
388 ForEachMatchingDC(DC, [&](ASTImporter &Forward, ASTImporter &Reverse,
389 Source<const DeclContext *> SourceDC) -> bool {
390 DeclarationName FromName = Reverse.Import(Name);
391 DeclContextLookupResult Result = SourceDC.get()->lookup(FromName);
392 for (NamedDecl *FromD : Result) {
393 FilterFoundDecl(std::make_pair(FromD, &Forward));
398 if (Candidates.empty())
401 Decls.reserve(Candidates.size());
402 for (const Candidate &C : Candidates) {
403 Decl *LookupRes = C.first.get();
404 ASTImporter *Importer = C.second;
405 NamedDecl *ND = cast_or_null<NamedDecl>(Importer->Import(LookupRes));
407 // If we don't import specialization, they are not available via lookup
408 // because the lookup result is imported TemplateDecl and it does not
409 // reference its specializations until they are imported explicitly.
410 bool IsSpecImportFailed =
411 importSpecializationsIfNeeded(LookupRes, Importer);
412 assert(!IsSpecImportFailed);
413 (void)IsSpecImportFailed;
416 SetExternalVisibleDeclsForName(DC, Name, Decls);
420 void ExternalASTMerger::FindExternalLexicalDecls(
421 const DeclContext *DC, llvm::function_ref<bool(Decl::Kind)> IsKindWeWant,
422 SmallVectorImpl<Decl *> &Result) {
423 ForEachMatchingDC(DC, [&](ASTImporter &Forward, ASTImporter &Reverse,
424 Source<const DeclContext *> SourceDC) -> bool {
425 for (const Decl *SourceDecl : SourceDC.get()->decls()) {
426 if (IsKindWeWant(SourceDecl->getKind())) {
427 Decl *ImportedDecl = Forward.Import(const_cast<Decl *>(SourceDecl));
428 assert(!ImportedDecl || IsSameDC(ImportedDecl->getDeclContext(), DC));