Refactor policy parsing

This change removes the ability for an overlayable resource to be
defined in multiple policy blocks within the same overlayable. This
change also changes aapt2 to use a bit mask to keep track of the parsed
policies.

Bug: 110869880
Bug: 120298168
Test: aapt2_tests
Change-Id: Ie26cd913f94a16c0b312f222bccfa48f62feceaa
diff --git a/tools/aapt2/link/TableMerger.cpp b/tools/aapt2/link/TableMerger.cpp
index d777e22..22e1723 100644
--- a/tools/aapt2/link/TableMerger.cpp
+++ b/tools/aapt2/link/TableMerger.cpp
@@ -134,35 +134,21 @@
     dst_entry->allow_new = std::move(src_entry->allow_new);
   }
 
-  for (auto& src_overlayable : src_entry->overlayable_declarations) {
-    for (auto& dst_overlayable : dst_entry->overlayable_declarations) {
-      // An overlayable resource cannot be declared twice with the same policy
-      if (src_overlayable.policy == dst_overlayable.policy) {
-        context->GetDiagnostics()->Error(DiagMessage(src_overlayable.source)
-                                             << "duplicate overlayable declaration for resource '"
-                                             << src_entry->name << "'");
-        context->GetDiagnostics()->Error(DiagMessage(dst_overlayable.source)
-                                             << "previous declaration here");
-        return false;
-      }
-
-      // An overlayable resource cannot be declared once with a policy and without a policy because
-      // the policy becomes unused
-      if (!src_overlayable.policy || !dst_overlayable.policy) {
-        context->GetDiagnostics()->Error(DiagMessage(src_overlayable.source)
-                                             << "overlayable resource '" << src_entry->name
-                                             << "' declared once with a policy and once with no "
-                                             << "policy");
-        context->GetDiagnostics()->Error(DiagMessage(dst_overlayable.source)
-                                             << "previous declaration here");
-        return false;
-      }
+  if (src_entry->overlayable) {
+    if (dst_entry->overlayable) {
+      // Do not allow a resource with an overlayable declaration to have that overlayable
+      // declaration redefined
+      context->GetDiagnostics()->Error(DiagMessage(src_entry->overlayable.value().source)
+                                       << "duplicate overlayable declaration for resource '"
+                                       << src_entry->name << "'");
+      context->GetDiagnostics()->Error(DiagMessage(dst_entry->overlayable.value().source)
+                                       << "previous declaration here");
+      return false;
+    } else {
+      dst_entry->overlayable = std::move(src_entry->overlayable);
     }
   }
 
-  dst_entry->overlayable_declarations.insert(dst_entry->overlayable_declarations.end(),
-                                             src_entry->overlayable_declarations.begin(),
-                                             src_entry->overlayable_declarations.end());
   return true;
 }