[clang][ExtractAPI] Add support for namespaces

[evelez7]

Summary

Serialize namespaces, nested namespaces, and class relationships inside them.

Depends on D157076

[evelez7]

Remove unnecessary line break.

[evelez7]

Note that this doesn't handle anonymous namespaces. Similar problems arise with anonymous classes/structs, being worked on.

[dang]

clang/include/clang/ExtractAPI/API.h

1135

Can we get rid of these types of changes to keep the commit history. In general we don't reformat code as part of a bigger patch.

[evelez7]

Revert extraneous formatting in API.h

[dang]

clang/include/clang/ExtractAPI/ExtractAPIVisitor.h

38

I think this should compute both the parent decl and its USR.

[evelez7]

Move DetermineParentDecl to determineParentRecord in APIVisitor as a private method.

Easier to just let it fetch the record for us and return nullptr if the parent is the translation unit.
Also we don't have to cast the Decls to their most derived form for the USR.

[dang]

LGTM

clang/include/clang/ExtractAPI/API.h

 // Classes deriving from APIRecord need to have USR be the first constructor
 // argument. This is so that they are compatible with `addTopLevelRecord`
 // defined in API.cpp
 /// The base representation of an API record. Holds common symbol information.
 struct APIRecord {
   /// Discriminator for LLVM-style RTTI (dyn_cast<> et al.)
   enum RecordKind {
     RK_Unknown,
+    RK_Namespace,
     RK_GlobalFunction,
     RK_GlobalFunctionTemplate,
     RK_GlobalFunctionTemplateSpecialization,
     RK_GlobalVariable,
     RK_GlobalVariableTemplate,
     RK_GlobalVariableTemplateSpecialization,
     RK_GlobalVariableTemplatePartialSpecialization,
     RK_EnumConstant,
public:
 
   APIRecord(RecordKind Kind, StringRef USR, StringRef Name)
       : USR(USR), Name(Name), Kind(Kind) {}
 
   // Pure virtual destructor to make APIRecord abstract
   virtual ~APIRecord() = 0;
 };
 
+struct NamespaceRecord : APIRecord {
+  NamespaceRecord(StringRef USR, StringRef Name, PresumedLoc Loc,
+                  AvailabilitySet Availabilities, LinkageInfo Linkage,
+                  const DocComment &Comment, DeclarationFragments Declaration,
+                  DeclarationFragments SubHeading, bool IsFromSystemHeader)
+      : APIRecord(RK_Namespace, USR, Name, Loc, std::move(Availabilities),
+                  Linkage, Comment, Declaration, SubHeading,
+                  IsFromSystemHeader) {}
+
+  static bool classof(const APIRecord *Record) {
+    return Record->getKind() == RK_Namespace;
+  }
+};
+
 /// This holds information associated with global functions.
 struct GlobalFunctionRecord : APIRecord {
   FunctionSignature Signature;
 
   GlobalFunctionRecord(StringRef USR, StringRef Name, PresumedLoc Loc,
                        AvailabilitySet Availabilities, LinkageInfo Linkage,
                        const DocComment &Comment,
                        DeclarationFragments Declaration,
struct ObjCContainerRecord : APIRecord {
 
   virtual ~ObjCContainerRecord() = 0;
 };
 
 struct CXXClassRecord : APIRecord {
   SmallVector<std::unique_ptr<CXXFieldRecord>> Fields;
   SmallVector<std::unique_ptr<CXXMethodRecord>> Methods;
   SmallVector<SymbolReference> Bases;
+  AccessControl Access;
 
   CXXClassRecord(StringRef USR, StringRef Name, PresumedLoc Loc,
                  AvailabilitySet Availabilities, const DocComment &Comment,
                  DeclarationFragments Declaration,
                  DeclarationFragments SubHeading, RecordKind Kind,
-                 bool IsFromSystemHeader)
+                 AccessControl Access, bool IsFromSystemHeader)
       : APIRecord(Kind, USR, Name, Loc, std::move(Availabilities),
                   LinkageInfo::none(), Comment, Declaration, SubHeading,
-                  IsFromSystemHeader) {}
+                  IsFromSystemHeader),
+        Access(Access) {}
 
   static bool classof(const APIRecord *Record) {
     return (Record->getKind() == RK_CXXClass);
   }
 
 private:
   virtual void anchor();
 };
 
 struct ClassTemplateRecord : CXXClassRecord {
   Template Templ;
 
   ClassTemplateRecord(StringRef USR, StringRef Name, PresumedLoc Loc,
                       AvailabilitySet Availabilities, const DocComment &Comment,
                       DeclarationFragments Declaration,
                       DeclarationFragments SubHeading, Template Template,
-                      bool IsFromSystemHeader)
+                      AccessControl Access, bool IsFromSystemHeader)
       : CXXClassRecord(USR, Name, Loc, std::move(Availabilities), Comment,
-                       Declaration, SubHeading, RK_ClassTemplate,
+                       Declaration, SubHeading, RK_ClassTemplate, Access,
                        IsFromSystemHeader),
         Templ(Template) {}
 
   static bool classof(const APIRecord *Record) {
     return Record->getKind() == RK_ClassTemplate;
   }
 };
 
 struct ClassTemplateSpecializationRecord : CXXClassRecord {
-  ClassTemplateSpecializationRecord(StringRef USR, StringRef Name,
-                                    PresumedLoc Loc,
-                                    AvailabilitySet Availabilities,
-                                    const DocComment &Comment,
-                                    DeclarationFragments Declaration,
-                                    DeclarationFragments SubHeading,
-                                    bool IsFromSystemHeader)
+  ClassTemplateSpecializationRecord(
+      StringRef USR, StringRef Name, PresumedLoc Loc,
+      AvailabilitySet Availabilities, const DocComment &Comment,
+      DeclarationFragments Declaration, DeclarationFragments SubHeading,
+      AccessControl Access, bool IsFromSystemHeader)
       : CXXClassRecord(USR, Name, Loc, std::move(Availabilities), Comment,
                        Declaration, SubHeading, RK_ClassTemplateSpecialization,
-                       IsFromSystemHeader) {}
+                       Access, IsFromSystemHeader) {}
 
   static bool classof(const APIRecord *Record) {
     return Record->getKind() == RK_ClassTemplateSpecialization;
   }
 };
 
 struct ClassTemplatePartialSpecializationRecord : CXXClassRecord {
   Template Templ;
   ClassTemplatePartialSpecializationRecord(
       StringRef USR, StringRef Name, PresumedLoc Loc,
       AvailabilitySet Availabilities, const DocComment &Comment,
       DeclarationFragments Declaration, DeclarationFragments SubHeading,
-      Template Template, bool IsFromSystemHeader)
+      Template Template, AccessControl Access, bool IsFromSystemHeader)
       : CXXClassRecord(USR, Name, Loc, std::move(Availabilities), Comment,
                        Declaration, SubHeading, RK_ClassTemplateSpecialization,
-                       IsFromSystemHeader),
+                       Access, IsFromSystemHeader),
         Templ(Template) {}
 
   static bool classof(const APIRecord *Record) {
     return Record->getKind() == RK_ClassTemplatePartialSpecialization;
   }
 };
 
 struct ConceptRecord : APIRecord {

 template <>
 struct has_function_signature<ObjCMethodRecord> : public std::true_type {};
 template <>
 struct has_function_signature<ObjCInstanceMethodRecord>
     : public std::true_type {};
 template <>
 struct has_function_signature<ObjCClassMethodRecord> : public std::true_type {};
 template <>
 struct has_function_signature<CXXInstanceMethodRecord> : public std::true_type {};
 template <>
 struct has_function_signature<CXXStaticMethodRecord> : public std::true_type {};
 template <>
 struct has_function_signature<CXXMethodTemplateRecord> : public std::true_type {
 };
 template <>
 struct has_function_signature<CXXMethodTemplateSpecializationRecord>
     : public std::true_type {};
 
 template <typename RecordTy> struct has_access : public std::false_type {};
 template <> struct has_access<CXXInstanceMethodRecord> : public std::true_type {};
 template <> struct has_access<CXXStaticMethodRecord> : public std::true_type {};
 template <> struct has_access<CXXFieldRecord> : public std::true_type {};
 template <>
 struct has_access<CXXMethodTemplateRecord> : public std::true_type {};
 template <>
 struct has_access<CXXMethodTemplateSpecializationRecord>
     : public std::true_type {};
 template <>
 struct has_access<CXXFieldTemplateRecord> : public std::true_type {};
+template <> struct has_access<CXXClassRecord> : public std::true_type {};
+template <> struct has_access<ClassTemplateRecord> : public std::true_type {};
+template <>
+struct has_access<ClassTemplateSpecializationRecord> : public std::true_type {};
+template <>
+struct has_access<ClassTemplatePartialSpecializationRecord>
+    : public std::true_type {};
 
 template <typename RecordTy> struct has_template : public std::false_type {};
 template <> struct has_template<ClassTemplateRecord> : public std::true_type {};
 template <>
 struct has_template<ClassTemplatePartialSpecializationRecord>
     : public std::true_type {};
 template <> struct has_template<ConceptRecord> : public std::true_type {};
 template <>
struct has_function_signature<GlobalFunctionTemplateRecord>
     : public std::true_type {};
 template <>
 struct has_function_signature<GlobalFunctionTemplateSpecializationRecord>
     : public std::true_type {};
 
 /// APISet holds the set of API records collected from given inputs.
 class APISet {
 public:
+  NamespaceRecord *addNamespace(APIRecord *Parent, StringRef Name,
+                                StringRef USR, PresumedLoc Loc,
+                                AvailabilitySet Availability,
+                                LinkageInfo Linkage, const DocComment &Comment,
+                                DeclarationFragments Declaration,
+                                DeclarationFragments SubHeading,
+                                bool IsFromSystemHeaderg);
   /// Create and add a global variable record into the API set.
   ///
   /// Note: the caller is responsible for keeping the StringRef \p Name and
   /// \p USR alive. APISet::copyString provides a way to copy strings into
   /// APISet itself, and APISet::recordUSR(const Decl *D) is a helper method
   /// to generate the USR for \c D and keep it alive in APISet.
   GlobalVariableRecord *
   addGlobalVar(StringRef Name, StringRef USR, PresumedLoc Loc,
CXXFieldRecord *addCXXField(APIRecord *CXXClass, StringRef Name,
                               AccessControl Access, bool IsFromSystemHeader);
 
   CXXFieldTemplateRecord *addCXXFieldTemplate(
       APIRecord *Parent, StringRef Name, StringRef USR, PresumedLoc Loc,
       AvailabilitySet Availability, const DocComment &Comment,
       DeclarationFragments Declaration, DeclarationFragments SubHeading,
       AccessControl Access, Template Template, bool IsFromSystemHeader);
 
-  CXXClassRecord *
-  addCXXClass(StringRef Name, StringRef USR, PresumedLoc Loc,
-              AvailabilitySet Availability, const DocComment &Comment,
-              DeclarationFragments Declaration, DeclarationFragments SubHeading,
-              APIRecord::RecordKind Kind, bool IsFromSystemHeader);
+  CXXClassRecord *addCXXClass(APIRecord *Parent, StringRef Name, StringRef USR,
+                              PresumedLoc Loc, AvailabilitySet Availability,
+                              const DocComment &Comment,
+                              DeclarationFragments Declaration,
+                              DeclarationFragments SubHeading,
+                              APIRecord::RecordKind Kind, AccessControl Access,
+                              bool IsFromSystemHeader);
 
   ClassTemplateRecord *
-  addClassTemplate(StringRef Name, StringRef USR, PresumedLoc Loc,
-                   AvailabilitySet Availability, const DocComment &Comment,
-                   DeclarationFragments Declaration,
+  addClassTemplate(APIRecord *Parent, StringRef Name, StringRef USR,
+                   PresumedLoc Loc, AvailabilitySet Availability,
+                   const DocComment &Comment, DeclarationFragments Declaration,
                    DeclarationFragments SubHeading, Template Template,
-                   bool IsFromSystemHeader);
+                   AccessControl Access, bool IsFromSystemHeader);
 
   ClassTemplateSpecializationRecord *addClassTemplateSpecialization(
-      StringRef Name, StringRef USR, PresumedLoc Loc,
+      APIRecord *Parent, StringRef Name, StringRef USR, PresumedLoc Loc,
       AvailabilitySet Availability, const DocComment &Comment,
       DeclarationFragments Declaration, DeclarationFragments SubHeading,
-      bool IsFromSystemHeader);
+      AccessControl Access, bool IsFromSystemHeader);
 
   ClassTemplatePartialSpecializationRecord *
   addClassTemplatePartialSpecialization(
-      StringRef Name, StringRef USR, PresumedLoc Loc,
+      APIRecord *Parent, StringRef Name, StringRef USR, PresumedLoc Loc,
       AvailabilitySet Availability, const DocComment &Comment,
       DeclarationFragments Declaration, DeclarationFragments SubHeading,
-      Template Template, bool IsFromSystemHeader);
+      Template Template, AccessControl Access, bool IsFromSystemHeader);
 
   GlobalVariableTemplateSpecializationRecord *
   addGlobalVariableTemplateSpecialization(
       StringRef Name, StringRef USR, PresumedLoc Loc,
       AvailabilitySet Availability, LinkageInfo Linkage,
       const DocComment &Comment, DeclarationFragments Declaration,
       DeclarationFragments SubHeading, bool IsFromSystemHeader);
 
public:
   using RecordMap = llvm::MapVector<StringRef, std::unique_ptr<RecordTy>>;
 
   /// Get the target triple for the ExtractAPI invocation.
   const llvm::Triple &getTarget() const { return Target; }
 
   /// Get the language used by the APIs.
   Language getLanguage() const { return Lang; }
 
+  const RecordMap<NamespaceRecord> &getNamespaces() const { return Namespaces; }
   const RecordMap<GlobalFunctionRecord> &getGlobalFunctions() const {
     return GlobalFunctions;
   }
   const RecordMap<GlobalFunctionTemplateRecord> &
   getGlobalFunctionTemplates() const {
     return GlobalFunctionTemplates;
   }
   const RecordMap<GlobalFunctionTemplateSpecializationRecord> &
private:
   ///
   /// Note: The main use for this is being able to deduplicate strings.
   llvm::BumpPtrAllocator StringAllocator;
 
   const llvm::Triple Target;
   const Language Lang;
 
   llvm::DenseMap<StringRef, APIRecord *> USRBasedLookupTable;
+  RecordMap<NamespaceRecord> Namespaces;
   RecordMap<GlobalFunctionRecord> GlobalFunctions;
   RecordMap<GlobalFunctionTemplateRecord> GlobalFunctionTemplates;
   RecordMap<GlobalFunctionTemplateSpecializationRecord>
       GlobalFunctionTemplateSpecializations;
   RecordMap<GlobalVariableRecord> GlobalVariables;
   RecordMap<GlobalVariableTemplateRecord> GlobalVariableTemplates;
   RecordMap<GlobalVariableTemplateSpecializationRecord>
       GlobalVariableTemplateSpecializations;

clang/include/clang/ExtractAPI/DeclarationFragments.h

public:
   /// CXXMethodDecl, and ObjCMethodDecl are exactly the same, but they do not
   /// share a common base. This template helps reuse the code.
   template <typename FunctionT>
   static FunctionSignature getFunctionSignature(const FunctionT *Function);
 
   static AccessControl getAccessControl(const Decl *Decl) {
     switch (Decl->getAccess()) {
     case AS_public:
+    case AS_none:
       return AccessControl("public");
     case AS_private:
       return AccessControl("private");
     case AS_protected:
       return AccessControl("protected");
-    case AS_none:
-      return AccessControl("none");
     }
     llvm_unreachable("Unhandled access control");
   }
 
+  static DeclarationFragments
+  getFragmentsForNamespace(const NamespaceDecl *Decl);
+
   /// Build DeclarationFragments for a variable declaration VarDecl.
   static DeclarationFragments getFragmentsForVar(const VarDecl *);
 
   static DeclarationFragments getFragmentsForVarTemplate(const VarDecl *);
 
   /// Build DeclarationFragments for a function declaration FunctionDecl.
   static DeclarationFragments getFragmentsForFunction(const FunctionDecl *);
 

clang/include/clang/ExtractAPI/ExtractAPIVisitor.h

 #include "clang/Index/USRGeneration.h"
 #include "llvm/ADT/StringRef.h"
 #include <type_traits>
 
 namespace clang {
 namespace extractapi {
 namespace impl {
 
 template <typename Derived>
 class ExtractAPIVisitorBase : public RecursiveASTVisitor<Derived> {
 protected:
   ExtractAPIVisitorBase(ASTContext &Context, APISet &API)
       : Context(Context), API(API) {}
 
 public:
   const APISet &getAPI() const { return API; }
 
public:
   bool WalkUpFromVarTemplateSpecializationDecl(
       const VarTemplateSpecializationDecl *Decl);
 
   bool WalkUpFromVarTemplatePartialSpecializationDecl(
       const VarTemplatePartialSpecializationDecl *Decl);
 
   bool WalkUpFromFunctionTemplateDecl(const FunctionTemplateDecl *Decl);
 
+  bool WalkUpFromNamespaceDecl(const NamespaceDecl *Decl);
+
+  bool VisitNamespaceDecl(const NamespaceDecl *Decl);
+
   bool VisitRecordDecl(const RecordDecl *Decl);
 
   bool VisitCXXRecordDecl(const CXXRecordDecl *Decl);
 
   bool VisitCXXMethodDecl(const CXXMethodDecl *Decl);
 
   bool VisitFieldDecl(const FieldDecl *Decl);
 
for (const auto BaseSpecifier : Decl->bases()) {
             BaseSpecifier.getType().getTypePtr()->getAsCXXRecordDecl();
         BaseClass.Name = BaseClassDecl->getName();
         BaseClass.USR = API.recordUSR(BaseClassDecl);
       }
       Bases.emplace_back(BaseClass);
     }
     return Bases;
   }
+
+  APIRecord *determineParentRecord(const DeclContext *Context) {
+    SmallString<128> ParentUSR;
+    if (Context->getDeclKind() == Decl::TranslationUnit)
+      return nullptr;
+
+    index::generateUSRForDecl(dyn_cast<Decl>(Context), ParentUSR);
+
+    APIRecord *Parent = API.findRecordForUSR(ParentUSR);
+    return Parent;
+  }
 };
 
 template <typename T>
 static void modifyRecords(const T &Records, const StringRef &Name) {
   for (const auto &Record : Records) {
     if (Name == Record.second.get()->Name) {
       auto &DeclFragment = Record.second->Declaration;
       DeclFragment.insert(DeclFragment.begin(), " ",

 template <typename Derived>
 bool ExtractAPIVisitorBase<Derived>::WalkUpFromFunctionTemplateDecl(
     const FunctionTemplateDecl *Decl) {
   getDerivedExtractAPIVisitor().VisitFunctionTemplateDecl(Decl);
   return true;
 }
 
 template <typename Derived>
+bool ExtractAPIVisitorBase<Derived>::WalkUpFromNamespaceDecl(
+    const NamespaceDecl *Decl) {
+  getDerivedExtractAPIVisitor().VisitNamespaceDecl(Decl);
+  return true;
+}
+
+template <typename Derived>
+bool ExtractAPIVisitorBase<Derived>::VisitNamespaceDecl(
+    const NamespaceDecl *Decl) {
+
+  if (!getDerivedExtractAPIVisitor().shouldDeclBeIncluded(Decl))
+    return true;
+  if (Decl->isAnonymousNamespace())
+    return true;
+  StringRef Name = Decl->getName();
+  StringRef USR = API.recordUSR(Decl);
+  LinkageInfo Linkage = Decl->getLinkageAndVisibility();
+  PresumedLoc Loc =
+      Context.getSourceManager().getPresumedLoc(Decl->getLocation());
+  DocComment Comment;
+  if (auto *RawComment =
+          getDerivedExtractAPIVisitor().fetchRawCommentForDecl(Decl))
+    Comment = RawComment->getFormattedLines(Context.getSourceManager(),
+                                            Context.getDiagnostics());
+
+  // Build declaration fragments and sub-heading for the struct.
+  DeclarationFragments Declaration =
+      DeclarationFragmentsBuilder::getFragmentsForNamespace(Decl);
+  DeclarationFragments SubHeading =
+      DeclarationFragmentsBuilder::getSubHeading(Decl);
+  APIRecord *Parent = determineParentRecord(Decl->getDeclContext());
+  API.addNamespace(Parent, Name, USR, Loc, AvailabilitySet(Decl), Linkage,
+                   Comment, Declaration, SubHeading, isInSystemHeader(Decl));
+
+  return true;
+}
+
+template <typename Derived>
 bool ExtractAPIVisitorBase<Derived>::VisitRecordDecl(const RecordDecl *Decl) {
   if (!getDerivedExtractAPIVisitor().shouldDeclBeIncluded(Decl))
     return true;
   // Collect symbol information.
   StringRef Name = Decl->getName();
   if (Name.empty())
     Name = getTypedefName(Decl);
   if (Name.empty())
bool ExtractAPIVisitorBase<Derived>::VisitCXXRecordDecl(
 
   APIRecord::RecordKind Kind;
   if (Decl->isUnion())
     Kind = APIRecord::RecordKind::RK_Union;
   else if (Decl->isStruct())
     Kind = APIRecord::RecordKind::RK_Struct;
   else
     Kind = APIRecord::RecordKind::RK_CXXClass;
+  auto Access = DeclarationFragmentsBuilder::getAccessControl(Decl);
 
+  APIRecord *Parent = determineParentRecord(Decl->getDeclContext());
   CXXClassRecord *CXXClassRecord;
   if (Decl->getDescribedClassTemplate()) {
     // Inject template fragments before class fragments.
     Declaration.insert(
         Declaration.begin(),
         DeclarationFragmentsBuilder::getFragmentsForRedeclarableTemplate(
             Decl->getDescribedClassTemplate()));
     CXXClassRecord = API.addClassTemplate(
-        Name, USR, Loc, AvailabilitySet(Decl), Comment, Declaration, SubHeading,
-        Template(Decl->getDescribedClassTemplate()), isInSystemHeader(Decl));
+        Parent, Name, USR, Loc, AvailabilitySet(Decl), Comment, Declaration,
+        SubHeading, Template(Decl->getDescribedClassTemplate()), Access,
+        isInSystemHeader(Decl));
   } else
-    CXXClassRecord =
-        API.addCXXClass(Name, USR, Loc, AvailabilitySet(Decl), Comment,
-                        Declaration, SubHeading, Kind, isInSystemHeader(Decl));
+    CXXClassRecord = API.addCXXClass(
+        Parent, Name, USR, Loc, AvailabilitySet(Decl), Comment, Declaration,
+        SubHeading, Kind, Access, isInSystemHeader(Decl));
 
   CXXClassRecord->Bases = getBases(Decl);
 
   return true;
 }
 
 template <typename Derived>
 bool ExtractAPIVisitorBase<Derived>::VisitCXXMethodDecl(
if (auto *RawComment =
     Comment = RawComment->getFormattedLines(Context.getSourceManager(),
                                             Context.getDiagnostics());
   DeclarationFragments Declaration =
       DeclarationFragmentsBuilder::getFragmentsForClassTemplateSpecialization(
           Decl);
   DeclarationFragments SubHeading =
       DeclarationFragmentsBuilder::getSubHeading(Decl);
 
+  APIRecord *Parent = determineParentRecord(Decl->getDeclContext());
   auto *ClassTemplateSpecializationRecord = API.addClassTemplateSpecialization(
-      Name, USR, Loc, AvailabilitySet(Decl), Comment, Declaration, SubHeading,
+      Parent, Name, USR, Loc, AvailabilitySet(Decl), Comment, Declaration,
+      SubHeading, DeclarationFragmentsBuilder::getAccessControl(Decl),
       isInSystemHeader(Decl));
 
   ClassTemplateSpecializationRecord->Bases = getBases(Decl);
 
   return true;
 }
 
 template <typename Derived>
if (auto *RawComment =
           getDerivedExtractAPIVisitor().fetchRawCommentForDecl(Decl))
     Comment = RawComment->getFormattedLines(Context.getSourceManager(),
                                             Context.getDiagnostics());
   DeclarationFragments Declaration = DeclarationFragmentsBuilder::
       getFragmentsForClassTemplatePartialSpecialization(Decl);
   DeclarationFragments SubHeading =
       DeclarationFragmentsBuilder::getSubHeading(Decl);
 
+  APIRecord *Parent = determineParentRecord(Decl->getDeclContext());
   auto *ClassTemplatePartialSpecRecord =
       API.addClassTemplatePartialSpecialization(
-          Name, USR, Loc, AvailabilitySet(Decl), Comment, Declaration,
-          SubHeading, Template(Decl), isInSystemHeader(Decl));
+          Parent, Name, USR, Loc, AvailabilitySet(Decl), Comment, Declaration,
+          SubHeading, Template(Decl),
+          DeclarationFragmentsBuilder::getAccessControl(Decl),
+          isInSystemHeader(Decl));
 
   ClassTemplatePartialSpecRecord->Bases = getBases(Decl);
 
   return true;
 }
 
 template <typename Derived>
 bool ExtractAPIVisitorBase<Derived>::VisitVarTemplateDecl(

clang/include/clang/ExtractAPI/Serialization/SerializerBase.h

 
 namespace clang {
 namespace extractapi {
 
 /// The base interface of visitors for API information.
 template <typename Derived> class APISetVisitor {
 public:
   void traverseAPISet() {
+    getDerived()->traverseNamespaces();
+
     getDerived()->traverseGlobalVariableRecords();
 
     getDerived()->traverseGlobalFunctionRecords();
 
     getDerived()->traverseEnumRecords();
 
     getDerived()->traverseStaticFieldRecords();
 
void traverseAPISet() {
 
     getDerived()->traverseObjCCategories();
 
     getDerived()->traverseMacroDefinitionRecords();
 
     getDerived()->traverseTypedefRecords();
   }
 
+  void traverseNamespaces() {
+    for (const auto &Namespace : API.getNamespaces())
+      getDerived()->visitNamespaceRecord(*Namespace.second);
+  }
+
   void traverseGlobalFunctionRecords() {
     for (const auto &GlobalFunction : API.getGlobalFunctions())
       getDerived()->visitGlobalFunctionRecord(*GlobalFunction.second);
   }
 
   void traverseGlobalVariableRecords() {
     for (const auto &GlobalVariable : API.getGlobalVariables())
       getDerived()->visitGlobalVariableRecord(*GlobalVariable.second);
for (const auto &Macro : API.getMacros())
       getDerived()->visitMacroDefinitionRecord(*Macro.second);
   }
 
   void traverseTypedefRecords() {
     for (const auto &Typedef : API.getTypedefs())
       getDerived()->visitTypedefRecord(*Typedef.second);
   }
 
+  void visitNamespaceRecord(const NamespaceRecord &Record){};
+
   /// Visit a global function record.
   void visitGlobalFunctionRecord(const GlobalFunctionRecord &Record){};
 
   /// Visit a global variable record.
   void visitGlobalVariableRecord(const GlobalVariableRecord &Record){};
 
   /// Visit an enum record.
   void visitEnumRecord(const EnumRecord &Record){};

clang/include/clang/ExtractAPI/Serialization/SymbolGraphSerializer.h

protected:
   /// Note: This should be consulted before emitting a symbol.
   const APIIgnoresList &IgnoresList;
 
   SymbolGraphSerializerOption Options;
 
   llvm::StringSet<> visitedCategories;
 
 public:
+  void visitNamespaceRecord(const NamespaceRecord &Record);
+
   /// Visit a global function record.
   void visitGlobalFunctionRecord(const GlobalFunctionRecord &Record);
 
   /// Visit a global variable record.
   void visitGlobalVariableRecord(const GlobalVariableRecord &Record);
 
   /// Visit an enum record.
   void visitEnumRecord(const EnumRecord &Record);

clang/lib/ExtractAPI/API.cpp

RecordTy *addTopLevelRecord(DenseMap<StringRef, APIRecord *> &USRLookupTable,
 
   auto *Record = Result.first->second.get();
   USRLookupTable.insert({USR, Record});
   return Record;
 }
 
 } // namespace
 
+NamespaceRecord *
+APISet::addNamespace(APIRecord *Parent, StringRef Name, StringRef USR,
+                     PresumedLoc Loc, AvailabilitySet Availability,
+                     LinkageInfo Linkage, const DocComment &Comment,
+                     DeclarationFragments Declaration,
+                     DeclarationFragments SubHeading, bool IsFromSystemHeader) {
+  auto *Record = addTopLevelRecord(
+      USRBasedLookupTable, Namespaces, USR, Name, Loc, std::move(Availability),
+      Linkage, Comment, Declaration, SubHeading, IsFromSystemHeader);
+
+  if (Parent)
+    Record->ParentInformation = APIRecord::HierarchyInformation(
+        Parent->USR, Parent->Name, Parent->getKind(), Parent);
+  return Record;
+}
+
 GlobalVariableRecord *
 APISet::addGlobalVar(StringRef Name, StringRef USR, PresumedLoc Loc,
                      AvailabilitySet Availabilities, LinkageInfo Linkage,
                      const DocComment &Comment, DeclarationFragments Fragments,
                      DeclarationFragments SubHeading, bool IsFromSystemHeader) {
   return addTopLevelRecord(USRBasedLookupTable, GlobalVariables, USR, Name, Loc,
                            std::move(Availabilities), Linkage, Comment,
                            Fragments, SubHeading, IsFromSystemHeader);
auto *Record =
                         SubHeading, Access, Template, IsFromSystemHeader);
   Record->ParentInformation = APIRecord::HierarchyInformation(
       Parent->USR, Parent->Name, Parent->getKind(), Parent);
 
   return Record;
 }
 
 CXXClassRecord *
-APISet::addCXXClass(StringRef Name, StringRef USR, PresumedLoc Loc,
-                    AvailabilitySet Availabilities, const DocComment &Comment,
-                    DeclarationFragments Declaration,
+APISet::addCXXClass(APIRecord *Parent, StringRef Name, StringRef USR,
+                    PresumedLoc Loc, AvailabilitySet Availabilities,
+                    const DocComment &Comment, DeclarationFragments Declaration,
                     DeclarationFragments SubHeading, APIRecord::RecordKind Kind,
-                    bool IsFromSystemHeader) {
-  return addTopLevelRecord(USRBasedLookupTable, CXXClasses, USR, Name, Loc,
-                           std::move(Availabilities), Comment, Declaration,
-                           SubHeading, Kind, IsFromSystemHeader);
+                    AccessControl Access, bool IsFromSystemHeader) {
+  auto *Record =
+      addTopLevelRecord(USRBasedLookupTable, CXXClasses, USR, Name, Loc,
+                        SubHeading, Kind, Access, IsFromSystemHeader);
+  if (Parent)
+    Record->ParentInformation = APIRecord::HierarchyInformation(
+        Parent->USR, Parent->Name, Parent->getKind(), Parent);
+  return Record;
 }
 
 ClassTemplateRecord *APISet::addClassTemplate(
-    StringRef Name, StringRef USR, PresumedLoc Loc,
+    APIRecord *Parent, StringRef Name, StringRef USR, PresumedLoc Loc,
     AvailabilitySet Availability, const DocComment &Comment,
     DeclarationFragments Declaration, DeclarationFragments SubHeading,
-    Template Template, bool IsFromSystemHeader) {
-
-  return addTopLevelRecord(USRBasedLookupTable, ClassTemplates, USR, Name, Loc,
-                           std::move(Availability), Comment, Declaration,
-                           SubHeading, Template, IsFromSystemHeader);
+    Template Template, AccessControl Access, bool IsFromSystemHeader) {
+  auto *Record =
+      addTopLevelRecord(USRBasedLookupTable, ClassTemplates, USR, Name, Loc,
+                        SubHeading, Template, Access, IsFromSystemHeader);
+  if (Parent)
+    Record->ParentInformation = APIRecord::HierarchyInformation(
+        Parent->USR, Parent->Name, Parent->getKind(), Parent);
+  return Record;
 }
 
 ClassTemplateSpecializationRecord *APISet::addClassTemplateSpecialization(
-    StringRef Name, StringRef USR, PresumedLoc Loc,
+    APIRecord *Parent, StringRef Name, StringRef USR, PresumedLoc Loc,
     AvailabilitySet Availability, const DocComment &Comment,
     DeclarationFragments Declaration, DeclarationFragments SubHeading,
-    bool IsFromSystemHeader) {
-  return addTopLevelRecord(USRBasedLookupTable, ClassTemplateSpecializations,
-                           USR, Name, Loc, std::move(Availability), Comment,
-                           Declaration, SubHeading, IsFromSystemHeader);
+    AccessControl Access, bool IsFromSystemHeader) {
+  auto *Record =
+      addTopLevelRecord(USRBasedLookupTable, ClassTemplateSpecializations, USR,
+                        Name, Loc, std::move(Availability), Comment,
+                        Declaration, SubHeading, Access, IsFromSystemHeader);
+  if (Parent)
+    Record->ParentInformation = APIRecord::HierarchyInformation(
+        Parent->USR, Parent->Name, Parent->getKind(), Parent);
+  return Record;
 }
 
 ClassTemplatePartialSpecializationRecord *
 APISet::addClassTemplatePartialSpecialization(
-    StringRef Name, StringRef USR, PresumedLoc Loc,
+    APIRecord *Parent, StringRef Name, StringRef USR, PresumedLoc Loc,
     AvailabilitySet Availability, const DocComment &Comment,
     DeclarationFragments Declaration, DeclarationFragments SubHeading,
-    Template Template, bool IsFromSystemHeader) {
-  return addTopLevelRecord(USRBasedLookupTable,
-                           ClassTemplatePartialSpecializations, USR, Name, Loc,
-                           std::move(Availability), Comment, Declaration,
-                           SubHeading, Template, IsFromSystemHeader);
+    Template Template, AccessControl Access, bool IsFromSystemHeader) {
+  auto *Record = addTopLevelRecord(
+      USRBasedLookupTable, ClassTemplatePartialSpecializations, USR, Name, Loc,
+      std::move(Availability), Comment, Declaration, SubHeading, Template,
+      Access, IsFromSystemHeader);
+  if (Parent)
+    Record->ParentInformation = APIRecord::HierarchyInformation(
+        Parent->USR, Parent->Name, Parent->getKind(), Parent);
+  return Record;
 }
 
 GlobalVariableTemplateSpecializationRecord *
 APISet::addGlobalVariableTemplateSpecialization(
     StringRef Name, StringRef USR, PresumedLoc Loc,
     AvailabilitySet Availability, LinkageInfo Linkage,
     const DocComment &Comment, DeclarationFragments Declaration,
     DeclarationFragments SubHeading, bool IsFromSystemHeader) {

clang/lib/ExtractAPI/DeclarationFragments.cpp

DeclarationFragments DeclarationFragmentsBuilder::getFragmentsForType(
   //  pointer to const int
   // ```
   if (SQT.Ty->isAnyPointerType())
     return TypeFragments.appendSpace().append(std::move(QualsFragments));
 
   return QualsFragments.appendSpace().append(std::move(TypeFragments));
 }
 
+DeclarationFragments DeclarationFragmentsBuilder::getFragmentsForNamespace(
+    const NamespaceDecl *Decl) {
+  DeclarationFragments Fragments;
+  Fragments.append("namespace", DeclarationFragments::FragmentKind::Keyword);
+  if (!Decl->isAnonymousNamespace())
+    Fragments.appendSpace().append(
+        Decl->getName(), DeclarationFragments::FragmentKind::Identifier);
+  return Fragments.append(";", DeclarationFragments::FragmentKind::Text);
+}
+
 DeclarationFragments
 DeclarationFragmentsBuilder::getFragmentsForVar(const VarDecl *Var) {
   DeclarationFragments Fragments;
   if (Var->isConstexpr())
     Fragments.append("constexpr", DeclarationFragments::FragmentKind::Keyword)
         .appendSpace();
 
   StorageClass SC = Var->getStorageClass();

clang/lib/ExtractAPI/Serialization/SymbolGraphSerializer.cpp

auto AddLangPrefix = [&Lang](StringRef S) -> std::string {
     return (getLanguageName(Lang) + "." + S).str();
   };
 
   Object Kind;
   switch (RK) {
   case APIRecord::RK_Unknown:
     llvm_unreachable("Records should have an explicit kind");
     break;
+  case APIRecord::RK_Namespace:
+    Kind["identifier"] = AddLangPrefix("namespace");
+    Kind["displayName"] = "Namespace";
+    break;
   case APIRecord::RK_GlobalFunction:
     Kind["identifier"] = AddLangPrefix("func");
     Kind["displayName"] = "Function";
     break;
   case APIRecord::RK_GlobalFunctionTemplate:
     Kind["identifier"] = AddLangPrefix("func");
     Kind["displayName"] = "Function Template";
     break;
void SymbolGraphSerializer::serializeRelationship(RelationshipKind Kind,
   Relationship["source"] = Source.USR;
   Relationship["target"] = Target.USR;
   Relationship["targetFallback"] = Target.Name;
   Relationship["kind"] = getRelationshipString(Kind);
 
   Relationships.emplace_back(std::move(Relationship));
 }
 
+void SymbolGraphSerializer::visitNamespaceRecord(
+    const NamespaceRecord &Record) {
+  auto Namespace = serializeAPIRecord(Record);
+  if (!Namespace)
+    return;
+  Symbols.emplace_back(std::move(*Namespace));
+  if (!Record.ParentInformation.empty())
+    serializeRelationship(RelationshipKind::MemberOf, Record,
+                          Record.ParentInformation.ParentRecord);
+}
+
 void SymbolGraphSerializer::visitGlobalFunctionRecord(
     const GlobalFunctionRecord &Record) {
   auto Obj = serializeAPIRecord(Record);
   if (!Obj)
     return;
 
   Symbols.emplace_back(std::move(*Obj));
 }

 void SymbolGraphSerializer::visitCXXClassRecord(const CXXClassRecord &Record) {
   auto Class = serializeAPIRecord(Record);
   if (!Class)
     return;
 
   Symbols.emplace_back(std::move(*Class));
   for (const auto Base : Record.Bases)
     serializeRelationship(RelationshipKind::InheritsFrom, Record, Base);
+  if (!Record.ParentInformation.empty())
+    serializeRelationship(RelationshipKind::MemberOf, Record,
+                          Record.ParentInformation.ParentRecord);
 }
 
 void SymbolGraphSerializer::visitClassTemplateRecord(
     const ClassTemplateRecord &Record) {
   auto Class = serializeAPIRecord(Record);
   if (!Class)
     return;
 
   Symbols.emplace_back(std::move(*Class));
   for (const auto Base : Record.Bases)
     serializeRelationship(RelationshipKind::InheritsFrom, Record, Base);
+  if (!Record.ParentInformation.empty())
+    serializeRelationship(RelationshipKind::MemberOf, Record,
+                          Record.ParentInformation.ParentRecord);
 }
 
 void SymbolGraphSerializer::visitClassTemplateSpecializationRecord(
     const ClassTemplateSpecializationRecord &Record) {
   auto Class = serializeAPIRecord(Record);
   if (!Class)
     return;
 
   Symbols.emplace_back(std::move(*Class));
 
   for (const auto Base : Record.Bases)
     serializeRelationship(RelationshipKind::InheritsFrom, Record, Base);
+  if (!Record.ParentInformation.empty())
+    serializeRelationship(RelationshipKind::MemberOf, Record,
+                          Record.ParentInformation.ParentRecord);
 }
 
 void SymbolGraphSerializer::visitClassTemplatePartialSpecializationRecord(
     const ClassTemplatePartialSpecializationRecord &Record) {
   auto Class = serializeAPIRecord(Record);
   if (!Class)
     return;
 
   Symbols.emplace_back(std::move(*Class));
 
   for (const auto Base : Record.Bases)
     serializeRelationship(RelationshipKind::InheritsFrom, Record, Base);
+  if (!Record.ParentInformation.empty())
+    serializeRelationship(RelationshipKind::MemberOf, Record,
+                          Record.ParentInformation.ParentRecord);
 }
 
 void SymbolGraphSerializer::visitCXXInstanceMethodRecord(
     const CXXInstanceMethodRecord &Record) {
   auto InstanceMethod = serializeAPIRecord(Record);
   if (!InstanceMethod)
     return;
 

clang/test/ExtractAPI/namespace.cpp

+// RUN: rm -rf %t
+// RUN: split-file %s %t
+// RUN: sed -e "s@INPUT_DIR@%{/t:regex_replacement}@g" \
+// RUN: %t/reference.output.json.in >> %t/reference.output.json
+// RUN: %clang_cc1 -std=c++20 -extract-api -triple arm64-apple-macosx \
+// RUN:   -x c++-header %t/input.h -o %t/output.json -verify
+
+// Generator version is not consistent across test runs, normalize it.
+// RUN: sed -e "s@\"generator\": \".*\"@\"generator\": \"?\"@g" \
+// RUN: %t/output.json >> %t/output-normalized.json
+// RUN: diff %t/reference.output.json %t/output-normalized.json
+
+//--- input.h
+namespace Foo {
+  class Bar { };
+}
+
+/// expected-no-diagnostics
+
+//--- reference.output.json.in
+{
+  "metadata": {
+    "formatVersion": {
+      "major": 0,
+      "minor": 5,
+      "patch": 3
+    },
+    "generator": "?"
+  },
+  "module": {
+    "name": "",
+    "platform": {
+      "architecture": "arm64",
+      "operatingSystem": {
+        "minimumVersion": {
+          "major": 11,
+          "minor": 0,
+          "patch": 0
+        },
+        "name": "macosx"
+      },
+      "vendor": "apple"
+    }
+  },
+  "relationships": [
+    {
+      "kind": "memberOf",
+      "source": "c:@N@Foo@S@Bar",
+      "target": "c:@N@Foo",
+      "targetFallback": "Foo"
+    }
+  ],
+  "symbols": [
+    {
+      "accessLevel": "public",
+      "declarationFragments": [
+        {
+          "kind": "keyword",
+          "spelling": "namespace"
+        },
+        {
+          "kind": "text",
+          "spelling": " "
+        },
+        {
+          "kind": "identifier",
+          "spelling": "Foo"
+        },
+        {
+          "kind": "text",
+          "spelling": ";"
+        }
+      ],
+      "identifier": {
+        "interfaceLanguage": "c++",
+        "precise": "c:@N@Foo"
+      },
+      "kind": {
+        "displayName": "Namespace",
+        "identifier": "c++.namespace"
+      },
+      "location": {
+        "position": {
+          "character": 11,
+          "line": 1
+        },
+        "uri": "file://INPUT_DIR/input.h"
+      },
+      "names": {
+        "navigator": [
+          {
+            "kind": "identifier",
+            "spelling": "Foo"
+          }
+        ],
+        "subHeading": [
+          {
+            "kind": "identifier",
+            "spelling": "Foo"
+          }
+        ],
+        "title": "Foo"
+      },
+      "pathComponents": [
+        "Foo"
+      ]
+    },
+    {
+      "accessLevel": "public",
+      "declarationFragments": [
+        {
+          "kind": "keyword",
+          "spelling": "class"
+        },
+        {
+          "kind": "text",
+          "spelling": " "
+        },
+        {
+          "kind": "identifier",
+          "spelling": "Bar"
+        },
+        {
+          "kind": "text",
+          "spelling": ";"
+        }
+      ],
+      "identifier": {
+        "interfaceLanguage": "c++",
+        "precise": "c:@N@Foo@S@Bar"
+      },
+      "kind": {
+        "displayName": "Class",
+        "identifier": "c++.class"
+      },
+      "location": {
+        "position": {
+          "character": 9,
+          "line": 2
+        },
+        "uri": "file://INPUT_DIR/input.h"
+      },
+      "names": {
+        "navigator": [
+          {
+            "kind": "identifier",
+            "spelling": "Bar"
+          }
+        ],
+        "subHeading": [
+          {
+            "kind": "identifier",
+            "spelling": "Bar"
+          }
+        ],
+        "title": "Bar"
+      },
+      "pathComponents": [
+        "Foo",
+        "Bar"
+      ]
+    }
+  ]
+}

clang/test/ExtractAPI/nested_namespaces.cpp

+// RUN: rm -rf %t
+// RUN: split-file %s %t
+// RUN: sed -e "s@INPUT_DIR@%{/t:regex_replacement}@g" \
+// RUN: %t/reference.output.json.in >> %t/reference.output.json
+// RUN: %clang_cc1 -std=c++20 -extract-api -triple arm64-apple-macosx \
+// RUN:   -x c++-header %t/input.h -o %t/output.json -verify
+
+// Generator version is not consistent across test runs, normalize it.
+// RUN: sed -e "s@\"generator\": \".*\"@\"generator\": \"?\"@g" \
+// RUN: %t/output.json >> %t/output-normalized.json
+// RUN: diff %t/reference.output.json %t/output-normalized.json
+
+//--- input.h
+namespace Foo {
+  namespace Bar { }
+}
+
+/// expected-no-diagnostics
+
+//--- reference.output.json.in
+{
+  "metadata": {
+    "formatVersion": {
+      "major": 0,
+      "minor": 5,
+      "patch": 3
+    },
+    "generator": "?"
+  },
+  "module": {
+    "name": "",
+    "platform": {
+      "architecture": "arm64",
+      "operatingSystem": {
+        "minimumVersion": {
+          "major": 11,
+          "minor": 0,
+          "patch": 0
+        },
+        "name": "macosx"
+      },
+      "vendor": "apple"
+    }
+  },
+  "relationships": [
+    {
+      "kind": "memberOf",
+      "source": "c:@N@Foo@N@Bar",
+      "target": "c:@N@Foo",
+      "targetFallback": "Foo"
+    }
+  ],
+  "symbols": [
+    {
+      "accessLevel": "public",
+      "declarationFragments": [
+        {
+          "kind": "keyword",
+          "spelling": "namespace"
+        },
+        {
+          "kind": "text",
+          "spelling": " "
+        },
+        {
+          "kind": "identifier",
+          "spelling": "Foo"
+        },
+        {
+          "kind": "text",
+          "spelling": ";"
+        }
+      ],
+      "identifier": {
+        "interfaceLanguage": "c++",
+        "precise": "c:@N@Foo"
+      },
+      "kind": {
+        "displayName": "Namespace",
+        "identifier": "c++.namespace"
+      },
+      "location": {
+        "position": {
+          "character": 11,
+          "line": 1
+        },
+        "uri": "file://INPUT_DIR/input.h"
+      },
+      "names": {
+        "navigator": [
+          {
+            "kind": "identifier",
+            "spelling": "Foo"
+          }
+        ],
+        "subHeading": [
+          {
+            "kind": "identifier",
+            "spelling": "Foo"
+          }
+        ],
+        "title": "Foo"
+      },
+      "pathComponents": [
+        "Foo"
+      ]
+    },
+    {
+      "accessLevel": "public",
+      "declarationFragments": [
+        {
+          "kind": "keyword",
+          "spelling": "namespace"
+        },
+        {
+          "kind": "text",
+          "spelling": " "
+        },
+        {
+          "kind": "identifier",
+          "spelling": "Bar"
+        },
+        {
+          "kind": "text",
+          "spelling": ";"
+        }
+      ],
+      "identifier": {
+        "interfaceLanguage": "c++",
+        "precise": "c:@N@Foo@N@Bar"
+      },
+      "kind": {
+        "displayName": "Namespace",
+        "identifier": "c++.namespace"
+      },
+      "location": {
+        "position": {
+          "character": 13,
+          "line": 2
+        },
+        "uri": "file://INPUT_DIR/input.h"
+      },
+      "names": {
+        "navigator": [
+          {
+            "kind": "identifier",
+            "spelling": "Bar"
+          }
+        ],
+        "subHeading": [
+          {
+            "kind": "identifier",
+            "spelling": "Bar"
+          }
+        ],
+        "title": "Bar"
+      },
+      "pathComponents": [
+        "Foo",
+        "Bar"
+      ]
+    }
+  ]
+}