[clang][ExtractAPI] Stop dropping fields of nested anonymous record types when they aren't attached to variable declaration (llvm#104600)

- Introduce primitives for removing records from `APISet` and managing
the record chain of `RecordContext`
- Detect nested anonymous record types and remove them from the `APISet`
after they have been fully traversed and transfer ownership of child
records to the parent context (if any)

Author: daniel-grumberg

clang/include/clang/ExtractAPI/API.h

@@ -19,21 +19,13 @@
 #define LLVM_CLANG_EXTRACTAPI_API_H
 
 #include "clang/AST/Availability.h"
-#include "clang/AST/Decl.h"
 #include "clang/AST/DeclBase.h"
-#include "clang/AST/DeclObjC.h"
 #include "clang/AST/RawCommentList.h"
 #include "clang/Basic/SourceLocation.h"
-#include "clang/Basic/Specifiers.h"
 #include "clang/ExtractAPI/DeclarationFragments.h"
-#include "llvm/ADT/ArrayRef.h"
-#include "llvm/ADT/MapVector.h"
-#include "llvm/ADT/StringRef.h"
+#include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/Support/Allocator.h"
 #include "llvm/Support/Casting.h"
-#include "llvm/Support/Compiler.h"
-#include "llvm/Support/ErrorHandling.h"
-#include "llvm/Support/raw_ostream.h"
 #include "llvm/TargetParser/Triple.h"
 #include <cstddef>
 #include <iterator>
@@ -328,6 +320,8 @@ class RecordContext {
   /// chain.
   void stealRecordChain(RecordContext &Other);
 
+  void removeFromRecordChain(APIRecord *Record);
+
   APIRecord::RecordKind getKind() const { return Kind; }
 
   struct record_iterator {
@@ -1426,10 +1420,15 @@ class APISet {
   typename std::enable_if_t<std::is_base_of_v<APIRecord, RecordTy>, RecordTy> *
   createRecord(StringRef USR, StringRef Name, CtorArgsContTy &&...CtorArgs);
 
-  ArrayRef<const APIRecord *> getTopLevelRecords() const {
-    return TopLevelRecords;
+  auto getTopLevelRecords() const {
+    return llvm::iterator_range<decltype(TopLevelRecords)::iterator>(
+        TopLevelRecords);
   }
 
+  void removeRecord(StringRef USR);
+
+  void removeRecord(APIRecord *Record);
+
   APISet(const llvm::Triple &Target, Language Lang,
          const std::string &ProductName)
       : Target(Target), Lang(Lang), ProductName(ProductName) {}
@@ -1456,7 +1455,7 @@ class APISet {
   // lives in the BumpPtrAllocator.
   using APIRecordStoredPtr = std::unique_ptr<APIRecord, APIRecordDeleter>;
   llvm::DenseMap<StringRef, APIRecordStoredPtr> USRBasedLookupTable;
-  std::vector<const APIRecord *> TopLevelRecords;
+  llvm::SmallPtrSet<const APIRecord *, 32> TopLevelRecords;
 
 public:
   const std::string ProductName;
@@ -1482,7 +1481,7 @@ APISet::createRecord(StringRef USR, StringRef Name,
             dyn_cast_if_present<RecordContext>(Record->Parent.Record))
       ParentContext->addToRecordChain(Record);
     else
-      TopLevelRecords.push_back(Record);
+      TopLevelRecords.insert(Record);
   } else {
     Record = dyn_cast<RecordTy>(Result.first->second.get());
   }

clang/include/clang/ExtractAPI/ExtractAPIVisitor.h

@@ -23,13 +23,11 @@
 #include "clang/AST/RecursiveASTVisitor.h"
 #include "clang/Basic/LLVM.h"
 #include "clang/Basic/Module.h"
-#include "clang/Basic/SourceManager.h"
 #include "clang/Basic/Specifiers.h"
 #include "clang/ExtractAPI/API.h"
 #include "clang/ExtractAPI/DeclarationFragments.h"
 #include "clang/ExtractAPI/TypedefUnderlyingTypeResolver.h"
 #include "clang/Index/USRGeneration.h"
-#include "llvm/ADT/SmallString.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/Casting.h"
 #include <type_traits>
@@ -40,6 +38,8 @@ namespace impl {
 
 template <typename Derived>
 class ExtractAPIVisitorBase : public RecursiveASTVisitor<Derived> {
+  using Base = RecursiveASTVisitor<Derived>;
+
 protected:
   ExtractAPIVisitorBase(ASTContext &Context, APISet &API)
       : Context(Context), API(API) {}
@@ -81,8 +81,10 @@ class ExtractAPIVisitorBase : public RecursiveASTVisitor<Derived> {
 
   bool VisitNamespaceDecl(const NamespaceDecl *Decl);
 
+  bool TraverseRecordDecl(RecordDecl *Decl);
   bool VisitRecordDecl(const RecordDecl *Decl);
 
+  bool TraverseCXXRecordDecl(CXXRecordDecl *Decl);
   bool VisitCXXRecordDecl(const CXXRecordDecl *Decl);
 
   bool VisitCXXMethodDecl(const CXXMethodDecl *Decl);
@@ -240,7 +242,7 @@ class ExtractAPIVisitorBase : public RecursiveASTVisitor<Derived> {
 
   bool isEmbeddedInVarDeclarator(const TagDecl &D) {
     return D.getName().empty() && getTypedefName(&D).empty() &&
-           D.isEmbeddedInDeclarator();
+           D.isEmbeddedInDeclarator() && !D.isFreeStanding();
   }
 
   void maybeMergeWithAnonymousTag(const DeclaratorDecl &D,
@@ -252,8 +254,10 @@ class ExtractAPIVisitorBase : public RecursiveASTVisitor<Derived> {
     clang::index::generateUSRForDecl(Tag, TagUSR);
     if (auto *Record = llvm::dyn_cast_if_present<TagRecord>(
             API.findRecordForUSR(TagUSR))) {
-      if (Record->IsEmbeddedInVarDeclarator)
+      if (Record->IsEmbeddedInVarDeclarator) {
         NewRecordContext->stealRecordChain(*Record);
+        API.removeRecord(Record);
+      }
     }
   }
 };
@@ -548,6 +552,19 @@ bool ExtractAPIVisitorBase<Derived>::VisitNamespaceDecl(
   return true;
 }
 
+template <typename Derived>
+bool ExtractAPIVisitorBase<Derived>::TraverseRecordDecl(RecordDecl *Decl) {
+  bool Ret = Base::TraverseRecordDecl(Decl);
+
+  if (!isEmbeddedInVarDeclarator(*Decl) && Decl->isAnonymousStructOrUnion()) {
+    SmallString<128> USR;
+    index::generateUSRForDecl(Decl, USR);
+    API.removeRecord(USR);
+  }
+
+  return Ret;
+}
+
 template <typename Derived>
 bool ExtractAPIVisitorBase<Derived>::VisitRecordDecl(const RecordDecl *Decl) {
   if (!getDerivedExtractAPIVisitor().shouldDeclBeIncluded(Decl))
@@ -588,6 +605,20 @@ bool ExtractAPIVisitorBase<Derived>::VisitRecordDecl(const RecordDecl *Decl) {
   return true;
 }
 
+template <typename Derived>
+bool ExtractAPIVisitorBase<Derived>::TraverseCXXRecordDecl(
+    CXXRecordDecl *Decl) {
+  bool Ret = Base::TraverseCXXRecordDecl(Decl);
+
+  if (!isEmbeddedInVarDeclarator(*Decl) && Decl->isAnonymousStructOrUnion()) {
+    SmallString<128> USR;
+    index::generateUSRForDecl(Decl, USR);
+    API.removeRecord(USR);
+  }
+
+  return Ret;
+}
+
 template <typename Derived>
 bool ExtractAPIVisitorBase<Derived>::VisitCXXRecordDecl(
     const CXXRecordDecl *Decl) {

clang/lib/ExtractAPI/API.cpp

@@ -13,8 +13,6 @@
 //===----------------------------------------------------------------------===//
 
 #include "clang/ExtractAPI/API.h"
-#include "clang/AST/RawCommentList.h"
-#include "clang/Index/USRGeneration.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/ErrorHandling.h"
 #include <memory>
@@ -60,6 +58,10 @@ bool RecordContext::IsWellFormed() const {
 
 void RecordContext::stealRecordChain(RecordContext &Other) {
   assert(IsWellFormed());
+  // Other's record chain is empty, nothing to do
+  if (Other.First == nullptr && Other.Last == nullptr)
+    return;
+
   // If we don't have an empty chain append Other's chain into ours.
   if (First)
     Last->NextInContext = Other.First;
@@ -68,6 +70,10 @@ void RecordContext::stealRecordChain(RecordContext &Other) {
 
   Last = Other.Last;
 
+  for (auto *StolenRecord = Other.First; StolenRecord != nullptr;
+       StolenRecord = StolenRecord->getNextInContext())
+    StolenRecord->Parent = SymbolReference(cast<APIRecord>(this));
+
   // Delete Other's chain to ensure we don't accidentally traverse it.
   Other.First = nullptr;
   Other.Last = nullptr;
@@ -85,6 +91,22 @@ void RecordContext::addToRecordChain(APIRecord *Record) const {
   Last = Record;
 }
 
+void RecordContext::removeFromRecordChain(APIRecord *Record) {
+  APIRecord *Prev = nullptr;
+  for (APIRecord *Curr = First; Curr != Record; Curr = Curr->NextInContext)
+    Prev = Curr;
+
+  if (Prev)
+    Prev->NextInContext = Record->NextInContext;
+  else
+    First = Record->NextInContext;
+
+  if (Last == Record)
+    Last = Prev;
+
+  Record->NextInContext = nullptr;
+}
+
 APIRecord *APISet::findRecordForUSR(StringRef USR) const {
   if (USR.empty())
     return nullptr;
@@ -114,6 +136,33 @@ SymbolReference APISet::createSymbolReference(StringRef Name, StringRef USR,
   return SymbolReference(copyString(Name), copyString(USR), copyString(Source));
 }
 
+void APISet::removeRecord(StringRef USR) {
+  auto Result = USRBasedLookupTable.find(USR);
+  if (Result != USRBasedLookupTable.end()) {
+    auto *Record = Result->getSecond().get();
+    auto &ParentReference = Record->Parent;
+    auto *ParentRecord = const_cast<APIRecord *>(ParentReference.Record);
+    if (!ParentRecord)
+      ParentRecord = findRecordForUSR(ParentReference.USR);
+
+    if (auto *ParentCtx = llvm::cast_if_present<RecordContext>(ParentRecord)) {
+      ParentCtx->removeFromRecordChain(Record);
+      if (auto *RecordAsCtx = llvm::dyn_cast<RecordContext>(Record))
+        ParentCtx->stealRecordChain(*RecordAsCtx);
+    } else {
+      TopLevelRecords.erase(Record);
+      if (auto *RecordAsCtx = llvm::dyn_cast<RecordContext>(Record)) {
+        for (const auto *Child = RecordAsCtx->First; Child != nullptr;
+             Child = Child->getNextInContext())
+          TopLevelRecords.insert(Child);
+      }
+    }
+    USRBasedLookupTable.erase(Result);
+  }
+}
+
+void APISet::removeRecord(APIRecord *Record) { removeRecord(Record->USR); }
+
 APIRecord::~APIRecord() {}
 TagRecord::~TagRecord() {}
 RecordRecord::~RecordRecord() {}

clang/lib/ExtractAPI/Serialization/SymbolGraphSerializer.cpp

@@ -673,14 +673,6 @@ bool SymbolGraphSerializer::shouldSkip(const APIRecord *Record) const {
   if (Record->Availability.isUnconditionallyUnavailable())
     return true;
 
-  // Filter out symbols without a name as we can generate correct symbol graphs
-  // for them. In practice these are anonymous record types that aren't attached
-  // to a declaration.
-  if (auto *Tag = dyn_cast<TagRecord>(Record)) {
-    if (Tag->IsEmbeddedInVarDeclarator)
-      return true;
-  }
-
   // Filter out symbols prefixed with an underscored as they are understood to
   // be symbols clients should not use.
   if (Record->Name.starts_with("_"))

clang/test/ExtractAPI/anonymous_record_no_typedef.c

@@ -163,4 +163,16 @@ enum {
 // GLOBALOTHERCASE-NEXT:   "GlobalOtherCase"
 // GLOBALOTHERCASE-NEXT: ]
 
+// RUN: FileCheck %s --input-file %t/output.symbols.json --check-prefix VEC
+union Vector {
+  struct {
+    float X;
+    float Y;
+  };
+  float Data[2];
+};
+// VEC-DAG: "!testRelLabel": "memberOf $ c:@U@Vector@FI@Data $ c:@U@Vector"
+// VEC-DAG: "!testRelLabel": "memberOf $ c:@U@Vector@Sa@FI@X $ c:@U@Vector"
+// VEC-DAG: "!testRelLabel": "memberOf $ c:@U@Vector@Sa@FI@Y $ c:@U@Vector"
+
 // expected-no-diagnostics