!fixup add clarifying note as suggested, thanks!

Author: fhahn

clang/lib/CodeGen/CodeGenTBAA.cpp

@@ -235,6 +235,12 @@ llvm::MDNode *CodeGenTBAA::getTypeInfoHelper(const Type *Ty) {
       // mangled names, meaning the metadata emitted below would incorrectly
       // mark them as no-alias. Use AnyPtr for such types in both C and C++, as
       // C and C++ types may be visible when doing LTO.
+      //
+      // Note that using AnyPtr is overly conservative. We could summarize the
+      // members of the type, as per the C compatibility rule in the future.
+      // This also covers anonymous structs and unions, which have a different
+      // compatibility rule, but it doesn't matter because you can never have a
+      // pointer to an anonymous struct or union.
       const auto *RT = Ty->getAs<RecordType>();
       if (RT && !RT->getDecl()->getDeclName())
         return AnyPtr;