[nullability] Add clarifying comment.

PiperOrigin-RevId: 576852498
Change-Id: I1cac0864c9b3d264ec0b9cc81ee52799ca8ef984
diff --git a/nullability/pointer_nullability_analysis.cc b/nullability/pointer_nullability_analysis.cc
index b0fa9e6..337bffd 100644
--- a/nullability/pointer_nullability_analysis.cc
+++ b/nullability/pointer_nullability_analysis.cc
@@ -473,6 +473,7 @@
     StorageLocation *Loc = RecordLoc->getChild(*member);
     PointerVal = dyn_cast<PointerValue>(State.Env.getValue(*Loc));
   } else {
+    // Use value that may have been set by the builtin transfer function.
     PointerVal = getPointerValueFromExpr(MCE, State.Env);
   }
   if (PointerVal) {