[clang] [APINotes] Support fields of C/C++ structs (PR #104088)

[Saleem Abdulrasool via cfe-commits]

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@@ -1252,6 +1282,81 @@ bool APINotesReader::Implementation::readCXXMethodBlock(
   return false;
 }
 
+bool APINotesReader::Implementation::readFieldBlock(
+    llvm::BitstreamCursor &Cursor, llvm::SmallVectorImpl<uint64_t> &Scratch) {
+  if (Cursor.EnterSubBlock(FIELD_BLOCK_ID))
+    return true;
+
+  llvm::Expected<llvm::BitstreamEntry> MaybeNext = Cursor.advance();
+  if (!MaybeNext) {
+    // FIXME this drops the error on the floor.
+    consumeError(MaybeNext.takeError());
+    return false;
+  }
+  llvm::BitstreamEntry Next = MaybeNext.get();
+  while (Next.Kind != llvm::BitstreamEntry::EndBlock) {
+    if (Next.Kind == llvm::BitstreamEntry::Error)
+      return true;
+
+    if (Next.Kind == llvm::BitstreamEntry::SubBlock) {
+      // Unknown sub-block, possibly for use by a future version of the
+      // API notes format.
+      if (Cursor.SkipBlock())
+        return true;
+
+      MaybeNext = Cursor.advance();
+      if (!MaybeNext) {
+        // FIXME this drops the error on the floor.
+        consumeError(MaybeNext.takeError());
+        return false;
+      }
+      Next = MaybeNext.get();
+      continue;
+    }
+
+    Scratch.clear();
+    llvm::StringRef BlobData;
+    llvm::Expected<unsigned> MaybeKind =
+        Cursor.readRecord(Next.ID, Scratch, &BlobData);
+    if (!MaybeKind) {
+      // FIXME this drops the error on the floor.
+      consumeError(MaybeKind.takeError());
+      return false;
+    }
+    unsigned Kind = MaybeKind.get();
+    switch (Kind) {
+    case field_block::FIELD_DATA: {
+      // Already saw C++ method table.
----------------
compnerd wrote:

I'm not sure I understand the comment. This is for a struct field, how does the method table factor in?

https://github.com/llvm/llvm-project/pull/104088