[clang] [extract-api] Don't crash for category in libclang APIs

Remove failure conditions for categories in libclang and return empty
content instead.

Differential Revision: https://reviews.llvm.org/D142101

clang/lib/ExtractAPI/Serialization/SymbolGraphSerializer.cpp

@@ -487,6 +487,7 @@ bool generatePathComponents(
   SmallVector<PathComponent, 4> ReverseComponenents;
   ReverseComponenents.emplace_back(Record.USR, Record.Name, Record.getKind());
   const auto *CurrentParent = &Record.ParentInformation;
+  bool FailedToFindParent = false;
   while (CurrentParent && !CurrentParent->empty()) {
     PathComponent CurrentParentComponent(CurrentParent->ParentUSR,
                                          CurrentParent->ParentName,
@@ -509,8 +510,10 @@ bool generatePathComponents(
 
     // The parent record doesn't exist which means the symbol shouldn't be
     // treated as part of the current product.
-    if (!ParentRecord)
-      return true;
+    if (!ParentRecord) {
+      FailedToFindParent = true;
+      break;
+    }
 
     ReverseComponenents.push_back(std::move(CurrentParentComponent));
     CurrentParent = &ParentRecord->ParentInformation;
@@ -519,8 +522,9 @@ bool generatePathComponents(
   for (const auto &PC : reverse(ReverseComponenents))
     ComponentTransformer(PC);
 
-  return false;
+  return FailedToFindParent;
 }
+
 Object serializeParentContext(const PathComponent &PC, Language Lang) {
   Object ParentContextElem;
   ParentContextElem["usr"] = PC.USR;
@@ -533,12 +537,15 @@ template <typename RecordTy>
 Array generateParentContexts(const RecordTy &Record, const APISet &API,
                              Language Lang) {
   Array ParentContexts;
-  if (generatePathComponents(
-          Record, API, [Lang, &ParentContexts](const PathComponent &PC) {
-            ParentContexts.push_back(serializeParentContext(PC, Lang));
-          }))
-    ParentContexts.clear();
-  ParentContexts.pop_back();
+  generatePathComponents(Record, API,
+                         [Lang, &ParentContexts](const PathComponent &PC) {
+                           ParentContexts.push_back(
+                               serializeParentContext(PC, Lang));
+                         });
+
+  // The last component would be the record itself so let's remove it.
+  if (!ParentContexts.empty())
+    ParentContexts.pop_back();
 
   return ParentContexts;
 }
@@ -865,6 +872,9 @@ SymbolGraphSerializer::serializeSingleSymbolSGF(StringRef USR,
   if (!Record)
     return {};
 
+  if (isa<ObjCCategoryRecord>(Record))
+    return {};
+
   Object Root;
   APIIgnoresList EmptyIgnores;
   SymbolGraphSerializer Serializer(API, EmptyIgnores,