RRO: Added partition policies for overlays

<overlayable> tags can now have policy elements that indicate which
partition the overlay apk must reside on in order to be allowed to
overlay a resource. This change only adds parsing of <policy> and
encoding of policy in the proto ResourceTable. A later change will add
the encoding of policy and overlayable in the binary APK.

<overlayable>
  <policy type="system|vendor|product|product_services|public" >
    <item type="string" name="oof" />
  </policy>
</overlayable>

Bug: 110869880
Test: make aapt2_tests
Change-Id: I8d4ed7b0e01f981149c6e3190af1681073b79b03
diff --git a/tools/aapt2/Debug.cpp b/tools/aapt2/Debug.cpp
index 0a517ab..0bc5221 100644
--- a/tools/aapt2/Debug.cpp
+++ b/tools/aapt2/Debug.cpp
@@ -306,8 +306,29 @@
             break;
         }
 
-        if (entry->overlayable) {
-          printer->Print(" OVERLAYABLE");
+        for (size_t i = 0; i < entry->overlayable_declarations.size(); i++) {
+          printer->Print((i == 0) ? " " : "|");
+          printer->Print("OVERLAYABLE");
+
+          if (entry->overlayable_declarations[i].policy) {
+            switch (entry->overlayable_declarations[i].policy.value()) {
+              case Overlayable::Policy::kProduct:
+                printer->Print("_PRODUCT");
+                break;
+              case Overlayable::Policy::kProductServices:
+                printer->Print("_PRODUCT_SERVICES");
+                break;
+              case Overlayable::Policy::kSystem:
+                printer->Print("_SYSTEM");
+                break;
+              case Overlayable::Policy::kVendor:
+                printer->Print("_VENDOR");
+                break;
+              case Overlayable::Policy::kPublic:
+                printer->Print("_PUBLIC");
+                break;
+            }
+          }
         }
 
         printer->Println();
diff --git a/tools/aapt2/ResourceParser.cpp b/tools/aapt2/ResourceParser.cpp
index 9a3f14c..4f25e09 100644
--- a/tools/aapt2/ResourceParser.cpp
+++ b/tools/aapt2/ResourceParser.cpp
@@ -99,7 +99,7 @@
   ResourceId id;
   Visibility::Level visibility_level = Visibility::Level::kUndefined;
   bool allow_new = false;
-  bool overlayable = false;
+  std::vector<Overlayable> overlayable_declarations;
 
   std::string comment;
   std::unique_ptr<Value> value;
@@ -133,11 +133,8 @@
     }
   }
 
-  if (res->overlayable) {
-    Overlayable overlayable;
-    overlayable.source = res->source;
-    overlayable.comment = res->comment;
-    if (!table->SetOverlayable(res->name, overlayable, diag)) {
+  for (auto& overlayable : res->overlayable_declarations) {
+    if (!table->AddOverlayable(res->name, overlayable, diag)) {
       return false;
     }
   }
@@ -673,7 +670,7 @@
   if (can_be_bag) {
     const auto bag_iter = elToBagMap.find(resource_type);
     if (bag_iter != elToBagMap.end()) {
-      // Ensure we have a name (unless this is a <public-group>).
+      // Ensure we have a name (unless this is a <public-group> or <overlayable>).
       if (resource_type != "public-group" && resource_type != "overlayable") {
         if (!maybe_name) {
           diag_->Error(DiagMessage(out_resource->source)
@@ -1062,74 +1059,137 @@
 bool ResourceParser::ParseOverlayable(xml::XmlPullParser* parser, ParsedResource* out_resource) {
   if (out_resource->config != ConfigDescription::DefaultConfig()) {
     diag_->Warn(DiagMessage(out_resource->source)
-                << "ignoring configuration '" << out_resource->config << "' for <overlayable> tag");
+                    << "ignoring configuration '" << out_resource->config
+                    << "' for <overlayable> tag");
   }
 
-  if (Maybe<StringPiece> maybe_policy = xml::FindNonEmptyAttribute(parser, "policy")) {
-    const StringPiece& policy = maybe_policy.value();
-    if (policy != "system") {
-      diag_->Error(DiagMessage(out_resource->source)
-                   << "<overlayable> has invalid policy '" << policy << "'");
-      return false;
-    }
-  }
+  std::string comment;
+  std::vector<Overlayable::Policy> policies;
 
   bool error = false;
-  const size_t depth = parser->depth();
-  while (xml::XmlPullParser::NextChildNode(parser, depth)) {
-    if (parser->event() != xml::XmlPullParser::Event::kStartElement) {
-      // Skip text/comments.
+  const size_t start_depth = parser->depth();
+  while (xml::XmlPullParser::IsGoodEvent(parser->Next())) {
+    xml::XmlPullParser::Event event = parser->event();
+    if (event == xml::XmlPullParser::Event::kEndElement && parser->depth() == start_depth) {
+      // Break the loop when exiting the overyabale element
+      break;
+    } else if (event == xml::XmlPullParser::Event::kEndElement
+               && parser->depth() == start_depth + 1) {
+      // Clear the current policies when exiting the policy element
+      policies.clear();
+      continue;
+    } else if (event == xml::XmlPullParser::Event::kComment) {
+      // Get the comment of individual item elements
+      comment = parser->comment();
+      continue;
+    } else if (event != xml::XmlPullParser::Event::kStartElement) {
+      // Skip to the next element
       continue;
     }
 
     const Source item_source = source_.WithLine(parser->line_number());
-    const std::string& element_namespace = parser->element_namespace();
     const std::string& element_name = parser->element_name();
+    const std::string& element_namespace = parser->element_namespace();
+
     if (element_namespace.empty() && element_name == "item") {
-      Maybe<StringPiece> maybe_name = xml::FindNonEmptyAttribute(parser, "name");
-      if (!maybe_name) {
-        diag_->Error(DiagMessage(item_source)
-                     << "<item> within an <overlayable> tag must have a 'name' attribute");
+      if (!ParseOverlayableItem(parser, policies, comment, out_resource)) {
         error = true;
-        continue;
       }
-
-      Maybe<StringPiece> maybe_type = xml::FindNonEmptyAttribute(parser, "type");
-      if (!maybe_type) {
-        diag_->Error(DiagMessage(item_source)
-                     << "<item> within an <overlayable> tag must have a 'type' attribute");
+    } else if (element_namespace.empty() && element_name == "policy") {
+      if (!policies.empty()) {
+        // If the policy list is not empty, then we are currently inside a policy element
+        diag_->Error(DiagMessage(item_source) << "<policy> blocks cannot be recursively nested");
         error = true;
-        continue;
+        break;
+      } else if (Maybe<StringPiece> maybe_type = xml::FindNonEmptyAttribute(parser, "type")) {
+        // Parse the polices separated by vertical bar characters to allow for specifying multiple
+        // policies at once
+        for (StringPiece part : util::Tokenize(maybe_type.value(), '|')) {
+          StringPiece trimmed_part = util::TrimWhitespace(part);
+          if (trimmed_part == "public") {
+            policies.push_back(Overlayable::Policy::kPublic);
+          } else if (trimmed_part == "product") {
+            policies.push_back(Overlayable::Policy::kProduct);
+          } else if (trimmed_part == "product_services") {
+            policies.push_back(Overlayable::Policy::kProductServices);
+          } else if (trimmed_part == "system") {
+            policies.push_back(Overlayable::Policy::kSystem);
+          } else if (trimmed_part == "vendor") {
+            policies.push_back(Overlayable::Policy::kVendor);
+          } else {
+            diag_->Error(DiagMessage(out_resource->source)
+                             << "<policy> has unsupported type '" << trimmed_part << "'");
+            error = true;
+            continue;
+          }
+        }
       }
-
-      const ResourceType* type = ParseResourceType(maybe_type.value());
-      if (type == nullptr) {
-        diag_->Error(DiagMessage(out_resource->source)
-                     << "invalid resource type '" << maybe_type.value()
-                     << "' in <item> within an <overlayable>");
-        error = true;
-        continue;
-      }
-
-      ParsedResource child_resource;
-      child_resource.name.type = *type;
-      child_resource.name.entry = maybe_name.value().to_string();
-      child_resource.source = item_source;
-      child_resource.overlayable = true;
-      if (options_.visibility) {
-        child_resource.visibility_level = options_.visibility.value();
-      }
-      out_resource->child_resources.push_back(std::move(child_resource));
-
-      xml::XmlPullParser::SkipCurrentElement(parser);
     } else if (!ShouldIgnoreElement(element_namespace, element_name)) {
-      diag_->Error(DiagMessage(item_source) << ":" << element_name << ">");
+      diag_->Error(DiagMessage(item_source) << "invalid element <" << element_name << "> in "
+                                            << " <overlayable>");
       error = true;
+      break;
     }
   }
+
   return !error;
 }
 
+bool ResourceParser::ParseOverlayableItem(xml::XmlPullParser* parser,
+                                          const std::vector<Overlayable::Policy>& policies,
+                                          const std::string& comment,
+                                          ParsedResource* out_resource) {
+  const Source item_source = source_.WithLine(parser->line_number());
+
+  Maybe<StringPiece> maybe_name = xml::FindNonEmptyAttribute(parser, "name");
+  if (!maybe_name) {
+    diag_->Error(DiagMessage(item_source)
+                     << "<item> within an <overlayable> tag must have a 'name' attribute");
+    return false;
+  }
+
+  Maybe<StringPiece> maybe_type = xml::FindNonEmptyAttribute(parser, "type");
+  if (!maybe_type) {
+    diag_->Error(DiagMessage(item_source)
+                     << "<item> within an <overlayable> tag must have a 'type' attribute");
+    return false;
+  }
+
+  const ResourceType* type = ParseResourceType(maybe_type.value());
+  if (type == nullptr) {
+    diag_->Error(DiagMessage(out_resource->source)
+                     << "invalid resource type '" << maybe_type.value()
+                     << "' in <item> within an <overlayable>");
+    return false;
+  }
+
+  ParsedResource child_resource;
+  child_resource.name.type = *type;
+  child_resource.name.entry = maybe_name.value().to_string();
+  child_resource.source = item_source;
+
+  if (policies.empty()) {
+    Overlayable overlayable;
+    overlayable.source = item_source;
+    overlayable.comment = comment;
+    child_resource.overlayable_declarations.push_back(overlayable);
+  } else {
+    for (Overlayable::Policy policy : policies) {
+      Overlayable overlayable;
+      overlayable.policy = policy;
+      overlayable.source = item_source;
+      overlayable.comment = comment;
+      child_resource.overlayable_declarations.push_back(overlayable);
+    }
+  }
+
+  if (options_.visibility) {
+    child_resource.visibility_level = options_.visibility.value();
+  }
+  out_resource->child_resources.push_back(std::move(child_resource));
+  return true;
+}
+
 bool ResourceParser::ParseAddResource(xml::XmlPullParser* parser, ParsedResource* out_resource) {
   if (ParseSymbolImpl(parser, out_resource)) {
     out_resource->visibility_level = Visibility::Level::kUndefined;
diff --git a/tools/aapt2/ResourceParser.h b/tools/aapt2/ResourceParser.h
index 06bb0c9..ebacd6f 100644
--- a/tools/aapt2/ResourceParser.h
+++ b/tools/aapt2/ResourceParser.h
@@ -96,6 +96,10 @@
   bool ParseSymbolImpl(xml::XmlPullParser* parser, ParsedResource* out_resource);
   bool ParseSymbol(xml::XmlPullParser* parser, ParsedResource* out_resource);
   bool ParseOverlayable(xml::XmlPullParser* parser, ParsedResource* out_resource);
+  bool ParseOverlayableItem(xml::XmlPullParser* parser,
+                            const std::vector<Overlayable::Policy>& policies,
+                            const std::string& comment,
+                            ParsedResource* out_resource);
   bool ParseAddResource(xml::XmlPullParser* parser, ParsedResource* out_resource);
   bool ParseAttr(xml::XmlPullParser* parser, ParsedResource* out_resource);
   bool ParseAttrImpl(xml::XmlPullParser* parser, ParsedResource* out_resource, bool weak);
diff --git a/tools/aapt2/ResourceParser_test.cpp b/tools/aapt2/ResourceParser_test.cpp
index 0dff664..c6f29ac 100644
--- a/tools/aapt2/ResourceParser_test.cpp
+++ b/tools/aapt2/ResourceParser_test.cpp
@@ -891,56 +891,162 @@
   ASSERT_TRUE(TestParse(R"(<string name="foo">%1$s %n %2$s</string>)"));
 }
 
-TEST_F(ResourceParserTest, ParseOverlayableTagWithSystemPolicy) {
-  std::string input = R"(
-      <overlayable policy="illegal_policy">
-        <item type="string" name="foo" />
-      </overlayable>)";
-  EXPECT_FALSE(TestParse(input));
-
-  input = R"(
-      <overlayable policy="system">
-        <item name="foo" />
-      </overlayable>)";
-  EXPECT_FALSE(TestParse(input));
-
-  input = R"(
-      <overlayable policy="system">
-        <item type="attr" />
-      </overlayable>)";
-  EXPECT_FALSE(TestParse(input));
-
-  input = R"(
-      <overlayable policy="system">
-        <item type="bad_type" name="foo" />
-      </overlayable>)";
-  EXPECT_FALSE(TestParse(input));
-
-  input = R"(<overlayable policy="system" />)";
+TEST_F(ResourceParserTest, ParseOverlayable) {
+  std::string input = R"(<overlayable />)";
   EXPECT_TRUE(TestParse(input));
 
-  input = R"(<overlayable />)";
-  EXPECT_TRUE(TestParse(input));
-
-  input = R"(
-      <overlayable policy="system">
-        <item type="string" name="foo" />
-        <item type="dimen" name="foo" />
-      </overlayable>)";
-  ASSERT_TRUE(TestParse(input));
-
   input = R"(
       <overlayable>
-        <item type="string" name="bar" />
+        <item type="string" name="foo" />
+        <item type="drawable" name="bar" />
       </overlayable>)";
   ASSERT_TRUE(TestParse(input));
 
-  Maybe<ResourceTable::SearchResult> search_result =
-      table_.FindResource(test::ParseNameOrDie("string/bar"));
+  auto search_result = table_.FindResource(test::ParseNameOrDie("string/foo"));
   ASSERT_TRUE(search_result);
   ASSERT_THAT(search_result.value().entry, NotNull());
   EXPECT_THAT(search_result.value().entry->visibility.level, Eq(Visibility::Level::kUndefined));
-  EXPECT_TRUE(search_result.value().entry->overlayable);
+  EXPECT_THAT(search_result.value().entry->overlayable_declarations.size(), Eq(1));
+  EXPECT_FALSE(search_result.value().entry->overlayable_declarations[0].policy);
+
+  search_result = table_.FindResource(test::ParseNameOrDie("drawable/bar"));
+  ASSERT_TRUE(search_result);
+  ASSERT_THAT(search_result.value().entry, NotNull());
+  EXPECT_THAT(search_result.value().entry->visibility.level, Eq(Visibility::Level::kUndefined));
+  EXPECT_THAT(search_result.value().entry->overlayable_declarations.size(), Eq(1));
+  EXPECT_FALSE(search_result.value().entry->overlayable_declarations[0].policy);
+}
+
+TEST_F(ResourceParserTest, ParseOverlayablePolicy) {
+  std::string input = R"(<overlayable />)";
+  EXPECT_TRUE(TestParse(input));
+
+  input = R"(
+      <overlayable>
+        <item type="string" name="foo" />
+        <policy type="product">
+          <item type="string" name="bar" />
+        </policy>
+        <policy type="product_services">
+          <item type="string" name="baz" />
+        </policy>
+        <policy type="system">
+          <item type="string" name="fiz" />
+        </policy>
+        <policy type="vendor">
+          <item type="string" name="fuz" />
+        </policy>
+        <policy type="public">
+          <item type="string" name="faz" />
+        </policy>
+      </overlayable>)";
+  ASSERT_TRUE(TestParse(input));
+
+  auto search_result = table_.FindResource(test::ParseNameOrDie("string/foo"));
+  ASSERT_TRUE(search_result);
+  ASSERT_THAT(search_result.value().entry, NotNull());
+  EXPECT_THAT(search_result.value().entry->visibility.level, Eq(Visibility::Level::kUndefined));
+  EXPECT_THAT(search_result.value().entry->overlayable_declarations.size(), Eq(1));
+  EXPECT_FALSE(search_result.value().entry->overlayable_declarations[0].policy);
+
+  search_result = table_.FindResource(test::ParseNameOrDie("string/bar"));
+  ASSERT_TRUE(search_result);
+  ASSERT_THAT(search_result.value().entry, NotNull());
+  EXPECT_THAT(search_result.value().entry->visibility.level, Eq(Visibility::Level::kUndefined));
+  EXPECT_THAT(search_result.value().entry->overlayable_declarations.size(), Eq(1));
+  EXPECT_THAT(search_result.value().entry->overlayable_declarations[0].policy,
+              Eq(Overlayable::Policy::kProduct));
+
+  search_result = table_.FindResource(test::ParseNameOrDie("string/baz"));
+  ASSERT_TRUE(search_result);
+  ASSERT_THAT(search_result.value().entry, NotNull());
+  EXPECT_THAT(search_result.value().entry->visibility.level, Eq(Visibility::Level::kUndefined));
+  EXPECT_THAT(search_result.value().entry->overlayable_declarations.size(), Eq(1));
+  EXPECT_THAT(search_result.value().entry->overlayable_declarations[0].policy,
+              Eq(Overlayable::Policy::kProductServices));
+
+  search_result = table_.FindResource(test::ParseNameOrDie("string/fiz"));
+  ASSERT_TRUE(search_result);
+  ASSERT_THAT(search_result.value().entry, NotNull());
+  EXPECT_THAT(search_result.value().entry->visibility.level, Eq(Visibility::Level::kUndefined));
+  EXPECT_THAT(search_result.value().entry->overlayable_declarations.size(), Eq(1));
+  EXPECT_THAT(search_result.value().entry->overlayable_declarations[0].policy,
+              Eq(Overlayable::Policy::kSystem));
+
+  search_result = table_.FindResource(test::ParseNameOrDie("string/fuz"));
+  ASSERT_TRUE(search_result);
+  ASSERT_THAT(search_result.value().entry, NotNull());
+  EXPECT_THAT(search_result.value().entry->visibility.level, Eq(Visibility::Level::kUndefined));
+  EXPECT_THAT(search_result.value().entry->overlayable_declarations.size(), Eq(1));
+  EXPECT_THAT(search_result.value().entry->overlayable_declarations[0].policy,
+              Eq(Overlayable::Policy::kVendor));
+
+  search_result = table_.FindResource(test::ParseNameOrDie("string/faz"));
+  ASSERT_TRUE(search_result);
+  ASSERT_THAT(search_result.value().entry, NotNull());
+  EXPECT_THAT(search_result.value().entry->visibility.level, Eq(Visibility::Level::kUndefined));
+  EXPECT_THAT(search_result.value().entry->overlayable_declarations.size(), Eq(1));
+  EXPECT_THAT(search_result.value().entry->overlayable_declarations[0].policy,
+              Eq(Overlayable::Policy::kPublic));
+}
+
+TEST_F(ResourceParserTest, ParseOverlayableBadPolicyError) {
+  std::string input = R"(
+      <overlayable>
+        <policy type="illegal_policy">
+          <item type="string" name="foo" />
+        </policy>
+      </overlayable>)";
+  EXPECT_FALSE(TestParse(input));
+
+  input = R"(
+      <overlayable>
+        <policy type="product">
+          <item name="foo" />
+        </policy>
+      </overlayable>)";
+  EXPECT_FALSE(TestParse(input));
+
+  input = R"(
+      <overlayable>
+        <policy type="vendor">
+          <item type="string" />
+        </policy>
+      </overlayable>)";
+  EXPECT_FALSE(TestParse(input));
+}
+
+TEST_F(ResourceParserTest, ParseOverlayableMultiplePolicy) {
+  std::string input = R"(
+      <overlayable>
+        <policy type="vendor|product_services">
+          <item type="string" name="foo" />
+        </policy>
+        <policy type="product|system">
+          <item type="string" name="bar" />
+        </policy>
+      </overlayable>)";
+  ASSERT_TRUE(TestParse(input));
+
+  auto search_result = table_.FindResource(test::ParseNameOrDie("string/foo"));
+  ASSERT_TRUE(search_result);
+  ASSERT_THAT(search_result.value().entry, NotNull());
+  EXPECT_THAT(search_result.value().entry->visibility.level, Eq(Visibility::Level::kUndefined));
+  EXPECT_THAT(search_result.value().entry->overlayable_declarations.size(), Eq(2));
+  EXPECT_THAT(search_result.value().entry->overlayable_declarations[0].policy,
+              Eq(Overlayable::Policy::kVendor));
+  EXPECT_THAT(search_result.value().entry->overlayable_declarations[1].policy,
+              Eq(Overlayable::Policy::kProductServices));
+
+  search_result = table_.FindResource(test::ParseNameOrDie("string/bar"));
+  ASSERT_TRUE(search_result);
+  ASSERT_THAT(search_result.value().entry, NotNull());
+  EXPECT_THAT(search_result.value().entry->visibility.level, Eq(Visibility::Level::kUndefined));
+  EXPECT_THAT(search_result.value().entry->overlayable_declarations.size(), Eq(2));
+  EXPECT_THAT(search_result.value().entry->overlayable_declarations[0].policy,
+              Eq(Overlayable::Policy::kProduct));
+  EXPECT_THAT(search_result.value().entry->overlayable_declarations[1].policy,
+              Eq(Overlayable::Policy::kSystem));
 }
 
 TEST_F(ResourceParserTest, DuplicateOverlayableIsError) {
@@ -950,6 +1056,85 @@
         <item type="string" name="foo" />
       </overlayable>)";
   EXPECT_FALSE(TestParse(input));
+
+  input = R"(
+      <overlayable>
+        <item type="string" name="foo" />
+      </overlayable>
+      <overlayable>
+        <item type="string" name="foo" />
+      </overlayable>)";
+  EXPECT_FALSE(TestParse(input));
+
+  input = R"(
+      <overlayable">
+        <policy type="product">
+          <item type="string" name="foo" />
+          <item type="string" name="foo" />
+        </policy>
+      </overlayable>)";
+  EXPECT_FALSE(TestParse(input));
+
+  input = R"(
+      <overlayable>
+        <policy type="product">
+          <item type="string" name="foo" />
+        </policy>
+      </overlayable>
+
+      <overlayable>
+        <policy type="product">
+          <item type="string" name="foo" />
+        </policy>
+      </overlayable>)";
+  EXPECT_FALSE(TestParse(input));
+}
+
+TEST_F(ResourceParserTest, PolicyAndNonPolicyOverlayableError) {
+  std::string input = R"(
+        <overlayable policy="product">
+          <item type="string" name="foo" />
+        </overlayable>
+        <overlayable policy="">
+          <item type="string" name="foo" />
+        </overlayable>)";
+  EXPECT_FALSE(TestParse(input));
+
+  input = R"(
+        <overlayable policy="">
+          <item type="string" name="foo" />
+        </overlayable>
+        <overlayable policy="product">
+          <item type="string" name="foo" />
+        </overlayable>)";
+  EXPECT_FALSE(TestParse(input));
+}
+
+TEST_F(ResourceParserTest, DuplicateOverlayableMultiplePolicyError) {
+  std::string input = R"(
+      <overlayable>
+        <policy type="vendor|product">
+          <item type="string" name="foo" />
+        </policy>
+      </overlayable>
+      <overlayable>
+        <policy type="product_services|vendor">
+          <item type="string" name="foo" />
+        </policy>
+      </overlayable>)";
+  EXPECT_FALSE(TestParse(input));
+}
+
+TEST_F(ResourceParserTest, NestPolicyInOverlayableError) {
+  std::string input = R"(
+      <overlayable>
+        <policy type="vendor|product">
+          <policy type="product_services">
+            <item type="string" name="foo" />
+          </policy>
+        </policy>
+      </overlayable>)";
+  EXPECT_FALSE(TestParse(input));
 }
 
 TEST_F(ResourceParserTest, ParseIdItem) {
diff --git a/tools/aapt2/ResourceTable.cpp b/tools/aapt2/ResourceTable.cpp
index 056a27b..bc8a4d1 100644
--- a/tools/aapt2/ResourceTable.cpp
+++ b/tools/aapt2/ResourceTable.cpp
@@ -625,17 +625,17 @@
   return true;
 }
 
-bool ResourceTable::SetOverlayable(const ResourceNameRef& name, const Overlayable& overlayable,
+bool ResourceTable::AddOverlayable(const ResourceNameRef& name, const Overlayable& overlayable,
                                    IDiagnostics* diag) {
-  return SetOverlayableImpl(name, overlayable, ResourceNameValidator, diag);
+  return AddOverlayableImpl(name, overlayable, ResourceNameValidator, diag);
 }
 
-bool ResourceTable::SetOverlayableMangled(const ResourceNameRef& name,
+bool ResourceTable::AddOverlayableMangled(const ResourceNameRef& name,
                                           const Overlayable& overlayable, IDiagnostics* diag) {
-  return SetOverlayableImpl(name, overlayable, SkipNameValidator, diag);
+  return AddOverlayableImpl(name, overlayable, SkipNameValidator, diag);
 }
 
-bool ResourceTable::SetOverlayableImpl(const ResourceNameRef& name, const Overlayable& overlayable,
+bool ResourceTable::AddOverlayableImpl(const ResourceNameRef& name, const Overlayable& overlayable,
                                        NameValidator name_validator, IDiagnostics* diag) {
   CHECK(diag != nullptr);
 
@@ -646,13 +646,28 @@
   ResourceTablePackage* package = FindOrCreatePackage(name.package);
   ResourceTableType* type = package->FindOrCreateType(name.type);
   ResourceEntry* entry = type->FindOrCreateEntry(name.entry);
-  if (entry->overlayable) {
-    diag->Error(DiagMessage(overlayable.source)
-                << "duplicate overlayable declaration for resource '" << name << "'");
-    diag->Error(DiagMessage(entry->overlayable.value().source) << "previous declaration here");
-    return false;
+
+  for (auto& overlayable_declaration : entry->overlayable_declarations) {
+    // An overlayable resource cannot be declared twice with the same policy
+    if (overlayable.policy == overlayable_declaration.policy) {
+      diag->Error(DiagMessage(overlayable.source)
+                    << "duplicate overlayable declaration for resource '" << name << "'");
+      diag->Error(DiagMessage(overlayable_declaration.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 (!overlayable.policy || !overlayable_declaration.policy) {
+      diag->Error(DiagMessage(overlayable.source)
+                    << "overlayable resource '" << name << "'"
+                    << " declared once with a policy and once with no policy");
+      diag->Error(DiagMessage(overlayable_declaration.source) << "previous declaration here");
+      return false;
+    }
   }
-  entry->overlayable = overlayable;
+
+  entry->overlayable_declarations.push_back(overlayable);
   return true;
 }
 
@@ -688,7 +703,7 @@
         new_entry->id = entry->id;
         new_entry->visibility = entry->visibility;
         new_entry->allow_new = entry->allow_new;
-        new_entry->overlayable = entry->overlayable;
+        new_entry->overlayable_declarations = entry->overlayable_declarations;
 
         for (const auto& config_value : entry->values) {
           ResourceConfigValue* new_value =
diff --git a/tools/aapt2/ResourceTable.h b/tools/aapt2/ResourceTable.h
index 1917d7e..3dd0a769 100644
--- a/tools/aapt2/ResourceTable.h
+++ b/tools/aapt2/ResourceTable.h
@@ -57,8 +57,27 @@
   std::string comment;
 };
 
-// The policy dictating whether an entry is overlayable at runtime by RROs.
+// Represents a declaration that a resource is overayable at runtime.
 struct Overlayable {
+  // Represents the types overlays that are allowed to overlay the resource.
+  enum class Policy {
+    // The resource can be overlaid by any overlay.
+    kPublic,
+
+    // The resource can be overlaid by any overlay on the system partition.
+    kSystem,
+
+    // The resource can be overlaid by any overlay on the vendor partition.
+    kVendor,
+
+    // The resource can be overlaid by any overlay on the product partition.
+    kProduct,
+
+    // The resource can be overlaid by any overlay on the product services partition.
+    kProductServices,
+  };
+
+  Maybe<Policy> policy;
   Source source;
   std::string comment;
 };
@@ -96,7 +115,8 @@
 
   Maybe<AllowNew> allow_new;
 
-  Maybe<Overlayable> overlayable;
+  // The declarations of this resource as overlayable for RROs
+  std::vector<Overlayable> overlayable_declarations;
 
   // The resource's values for each configuration.
   std::vector<std::unique_ptr<ResourceConfigValue>> values;
@@ -226,9 +246,9 @@
   bool SetVisibilityWithIdMangled(const ResourceNameRef& name, const Visibility& visibility,
                                   const ResourceId& res_id, IDiagnostics* diag);
 
-  bool SetOverlayable(const ResourceNameRef& name, const Overlayable& overlayable,
+  bool AddOverlayable(const ResourceNameRef& name, const Overlayable& overlayable,
                       IDiagnostics* diag);
-  bool SetOverlayableMangled(const ResourceNameRef& name, const Overlayable& overlayable,
+  bool AddOverlayableMangled(const ResourceNameRef& name, const Overlayable& overlayable,
                              IDiagnostics* diag);
 
   bool SetAllowNew(const ResourceNameRef& name, const AllowNew& allow_new, IDiagnostics* diag);
@@ -303,7 +323,7 @@
   bool SetAllowNewImpl(const ResourceNameRef& name, const AllowNew& allow_new,
                        NameValidator name_validator, IDiagnostics* diag);
 
-  bool SetOverlayableImpl(const ResourceNameRef& name, const Overlayable& overlayable,
+  bool AddOverlayableImpl(const ResourceNameRef& name, const Overlayable& overlayable,
                           NameValidator name_validator, IDiagnostics* diag);
 
   bool SetSymbolStateImpl(const ResourceNameRef& name, const ResourceId& res_id,
diff --git a/tools/aapt2/ResourceTable_test.cpp b/tools/aapt2/ResourceTable_test.cpp
index 05c6f15..7c28f07 100644
--- a/tools/aapt2/ResourceTable_test.cpp
+++ b/tools/aapt2/ResourceTable_test.cpp
@@ -242,21 +242,69 @@
   ASSERT_THAT(result.value().entry->allow_new.value().comment, StrEq("second"));
 }
 
-TEST(ResourceTableTest, SetOverlayable) {
+TEST(ResourceTableTest, AddOverlayable) {
   ResourceTable table;
   const ResourceName name = test::ParseNameOrDie("android:string/foo");
 
   Overlayable overlayable;
-
+  overlayable.policy = Overlayable::Policy::kProduct;
   overlayable.comment = "first";
-  ASSERT_TRUE(table.SetOverlayable(name, overlayable, test::GetDiagnostics()));
+  ASSERT_TRUE(table.AddOverlayable(name, overlayable, test::GetDiagnostics()));
   Maybe<ResourceTable::SearchResult> result = table.FindResource(name);
   ASSERT_TRUE(result);
-  ASSERT_TRUE(result.value().entry->overlayable);
-  ASSERT_THAT(result.value().entry->overlayable.value().comment, StrEq("first"));
+  ASSERT_THAT(result.value().entry->overlayable_declarations.size(), Eq(1));
+  ASSERT_THAT(result.value().entry->overlayable_declarations[0].comment, StrEq("first"));
+  ASSERT_THAT(result.value().entry->overlayable_declarations[0].policy,
+              Eq(Overlayable::Policy::kProduct));
 
-  overlayable.comment = "second";
-  ASSERT_FALSE(table.SetOverlayable(name, overlayable, test::GetDiagnostics()));
+  Overlayable overlayable2;
+  overlayable2.comment = "second";
+  overlayable2.policy = Overlayable::Policy::kProductServices;
+  ASSERT_TRUE(table.AddOverlayable(name, overlayable2, test::GetDiagnostics()));
+  result = table.FindResource(name);
+  ASSERT_TRUE(result);
+  ASSERT_THAT(result.value().entry->overlayable_declarations.size(), Eq(2));
+  ASSERT_THAT(result.value().entry->overlayable_declarations[0].comment, StrEq("first"));
+  ASSERT_THAT(result.value().entry->overlayable_declarations[0].policy,
+              Eq(Overlayable::Policy::kProduct));
+  ASSERT_THAT(result.value().entry->overlayable_declarations[1].comment, StrEq("second"));
+  ASSERT_THAT(result.value().entry->overlayable_declarations[1].policy,
+              Eq(Overlayable::Policy::kProductServices));
+}
+
+TEST(ResourceTableTest, AddDuplicateOverlayableFail) {
+  ResourceTable table;
+  const ResourceName name = test::ParseNameOrDie("android:string/foo");
+
+  Overlayable overlayable;
+  overlayable.policy = Overlayable::Policy::kProduct;
+  ASSERT_TRUE(table.AddOverlayable(name, overlayable, test::GetDiagnostics()));
+
+  Overlayable overlayable2;
+  overlayable2.policy = Overlayable::Policy::kProduct;
+  ASSERT_FALSE(table.AddOverlayable(name, overlayable2, test::GetDiagnostics()));
+}
+
+TEST(ResourceTableTest, AddOverlayablePolicyAndNoneFirstFail) {
+  ResourceTable table;
+  const ResourceName name = test::ParseNameOrDie("android:string/foo");
+
+  ASSERT_TRUE(table.AddOverlayable(name, {}, test::GetDiagnostics()));
+
+  Overlayable overlayable2;
+  overlayable2.policy = Overlayable::Policy::kProduct;
+  ASSERT_FALSE(table.AddOverlayable(name, overlayable2, test::GetDiagnostics()));
+}
+
+TEST(ResourceTableTest, AddOverlayablePolicyAndNoneLastFail) {
+  ResourceTable table;
+  const ResourceName name = test::ParseNameOrDie("android:string/foo");
+
+  Overlayable overlayable;
+  overlayable.policy = Overlayable::Policy::kProduct;
+  ASSERT_TRUE(table.AddOverlayable(name, overlayable, test::GetDiagnostics()));
+
+  ASSERT_FALSE(table.AddOverlayable(name, {}, test::GetDiagnostics()));
 }
 
 TEST(ResourceTableTest, AllowDuplictaeResourcesNames) {
diff --git a/tools/aapt2/Resources.proto b/tools/aapt2/Resources.proto
index d7a3771..bf9fe49 100644
--- a/tools/aapt2/Resources.proto
+++ b/tools/aapt2/Resources.proto
@@ -133,13 +133,25 @@
   string comment = 2;
 }
 
-// Whether a resource is overlayable by runtime resource overlays (RRO).
+// Represents a declaration that a resource is overayable at runtime.
 message Overlayable {
+  enum Policy {
+    NONE = 0;
+    PUBLIC = 1;
+    SYSTEM = 2;
+    VENDOR = 3;
+    PRODUCT = 4;
+    PRODUCT_SERVICES = 5;
+  }
+
   // Where this declaration was defined in source.
   Source source = 1;
 
   // Any comment associated with the declaration.
   string comment = 2;
+
+  // The policy of the overlayable declaration
+  Policy policy = 3;
 }
 
 // An entry ID in the range [0x0000, 0xffff].
@@ -169,7 +181,7 @@
   AllowNew allow_new = 4;
 
   // Whether this resource can be overlaid by a runtime resource overlay (RRO).
-  Overlayable overlayable = 5;
+  repeated Overlayable overlayable = 5;
 
   // The set of values defined for this entry, each corresponding to a different
   // configuration/variant.
diff --git a/tools/aapt2/format/binary/BinaryResourceParser.cpp b/tools/aapt2/format/binary/BinaryResourceParser.cpp
index 3a39a6b..ed70fb3 100644
--- a/tools/aapt2/format/binary/BinaryResourceParser.cpp
+++ b/tools/aapt2/format/binary/BinaryResourceParser.cpp
@@ -398,7 +398,7 @@
       if (type_spec_flags & ResTable_typeSpec::SPEC_OVERLAYABLE) {
         Overlayable overlayable;
         overlayable.source = source_.WithLine(0);
-        if (!table_->SetOverlayableMangled(name, overlayable, diag_)) {
+        if (!table_->AddOverlayableMangled(name, overlayable, diag_)) {
           return false;
         }
       }
diff --git a/tools/aapt2/format/binary/TableFlattener.cpp b/tools/aapt2/format/binary/TableFlattener.cpp
index 8641a7c..8a86f63a 100644
--- a/tools/aapt2/format/binary/TableFlattener.cpp
+++ b/tools/aapt2/format/binary/TableFlattener.cpp
@@ -446,7 +446,7 @@
         config_masks[entry->id.value()] |= util::HostToDevice32(ResTable_typeSpec::SPEC_PUBLIC);
       }
 
-      if (entry->overlayable) {
+      if (!entry->overlayable_declarations.empty()) {
         config_masks[entry->id.value()] |=
             util::HostToDevice32(ResTable_typeSpec::SPEC_OVERLAYABLE);
       }
diff --git a/tools/aapt2/format/binary/TableFlattener_test.cpp b/tools/aapt2/format/binary/TableFlattener_test.cpp
index af19b98..cd1414c7e 100644
--- a/tools/aapt2/format/binary/TableFlattener_test.cpp
+++ b/tools/aapt2/format/binary/TableFlattener_test.cpp
@@ -634,7 +634,7 @@
           .AddSimple("com.app.test:integer/overlayable", ResourceId(0x7f020000))
           .Build();
 
-  ASSERT_TRUE(table->SetOverlayable(test::ParseNameOrDie("com.app.test:integer/overlayable"),
+  ASSERT_TRUE(table->AddOverlayable(test::ParseNameOrDie("com.app.test:integer/overlayable"),
                                     Overlayable{}, test::GetDiagnostics()));
 
   ResTable res_table;
diff --git a/tools/aapt2/format/proto/ProtoDeserialize.cpp b/tools/aapt2/format/proto/ProtoDeserialize.cpp
index d1b2fdb..f612914 100644
--- a/tools/aapt2/format/proto/ProtoDeserialize.cpp
+++ b/tools/aapt2/format/proto/ProtoDeserialize.cpp
@@ -437,15 +437,37 @@
         entry->allow_new = std::move(allow_new);
       }
 
-      if (pb_entry.has_overlayable()) {
-        const pb::Overlayable& pb_overlayable = pb_entry.overlayable();
-
+      for (const pb::Overlayable& pb_overlayable : pb_entry.overlayable()) {
         Overlayable overlayable;
+        switch (pb_overlayable.policy()) {
+          case pb::Overlayable::NONE:
+            overlayable.policy = {};
+            break;
+          case pb::Overlayable::PUBLIC:
+            overlayable.policy = Overlayable::Policy::kPublic;
+            break;
+          case pb::Overlayable::PRODUCT:
+            overlayable.policy = Overlayable::Policy::kProduct;
+            break;
+          case pb::Overlayable::PRODUCT_SERVICES:
+            overlayable.policy = Overlayable::Policy::kProductServices;
+            break;
+          case pb::Overlayable::SYSTEM:
+            overlayable.policy = Overlayable::Policy::kSystem;
+            break;
+          case pb::Overlayable::VENDOR:
+            overlayable.policy = Overlayable::Policy::kVendor;
+            break;
+          default:
+            *out_error = "unknown overlayable policy";
+            return false;
+        }
+
         if (pb_overlayable.has_source()) {
           DeserializeSourceFromPb(pb_overlayable.source(), src_pool, &overlayable.source);
         }
         overlayable.comment = pb_overlayable.comment();
-        entry->overlayable = std::move(overlayable);
+        entry->overlayable_declarations.push_back(overlayable);
       }
 
       ResourceId resid(pb_package.package_id().id(), pb_type.type_id().id(),
diff --git a/tools/aapt2/format/proto/ProtoSerialize.cpp b/tools/aapt2/format/proto/ProtoSerialize.cpp
index 7e35ea7..f1e96d6 100644
--- a/tools/aapt2/format/proto/ProtoSerialize.cpp
+++ b/tools/aapt2/format/proto/ProtoSerialize.cpp
@@ -310,11 +310,31 @@
           pb_allow_new->set_comment(entry->allow_new.value().comment);
         }
 
-        if (entry->overlayable) {
-          pb::Overlayable* pb_overlayable = pb_entry->mutable_overlayable();
-          SerializeSourceToPb(entry->overlayable.value().source, &source_pool,
+        for (const Overlayable& overlayable : entry->overlayable_declarations) {
+          pb::Overlayable* pb_overlayable = pb_entry->add_overlayable();
+          if (overlayable.policy) {
+            switch (overlayable.policy.value()) {
+              case Overlayable::Policy::kPublic:
+                pb_overlayable->set_policy(pb::Overlayable::PUBLIC);
+                break;
+              case Overlayable::Policy::kProduct:
+                pb_overlayable->set_policy(pb::Overlayable::PRODUCT);
+                break;
+              case Overlayable::Policy::kProductServices:
+                pb_overlayable->set_policy(pb::Overlayable::PRODUCT_SERVICES);
+                break;
+              case Overlayable::Policy::kSystem:
+                pb_overlayable->set_policy(pb::Overlayable::SYSTEM);
+                break;
+              case Overlayable::Policy::kVendor:
+                pb_overlayable->set_policy(pb::Overlayable::VENDOR);
+                break;
+            }
+          }
+
+          SerializeSourceToPb(overlayable.source, &source_pool,
                               pb_overlayable->mutable_source());
-          pb_overlayable->set_comment(entry->overlayable.value().comment);
+          pb_overlayable->set_comment(overlayable.comment);
         }
 
         for (const std::unique_ptr<ResourceConfigValue>& config_value : entry->values) {
diff --git a/tools/aapt2/format/proto/ProtoSerialize_test.cpp b/tools/aapt2/format/proto/ProtoSerialize_test.cpp
index 3c4d41a..95dbbeb 100644
--- a/tools/aapt2/format/proto/ProtoSerialize_test.cpp
+++ b/tools/aapt2/format/proto/ProtoSerialize_test.cpp
@@ -93,7 +93,7 @@
       util::make_unique<Reference>(expected_ref), context->GetDiagnostics()));
 
   // Make an overlayable resource.
-  ASSERT_TRUE(table->SetOverlayable(test::ParseNameOrDie("com.app.a:integer/overlayable"),
+  ASSERT_TRUE(table->AddOverlayable(test::ParseNameOrDie("com.app.a:integer/overlayable"),
                                     Overlayable{}, test::GetDiagnostics()));
 
   pb::ResourceTable pb_table;
@@ -106,7 +106,7 @@
 
   ResourceTable new_table;
   std::string error;
-  ASSERT_TRUE(DeserializeTableFromPb(pb_table, &files, &new_table, &error));
+  ASSERT_TRUE(DeserializeTableFromPb(pb_table, &files, &new_table, &error)) << error;
   EXPECT_THAT(error, IsEmpty());
 
   Id* new_id = test::GetValue<Id>(&new_table, "com.app.a:id/foo");
@@ -160,7 +160,8 @@
       new_table.FindResource(test::ParseNameOrDie("com.app.a:integer/overlayable"));
   ASSERT_TRUE(search_result);
   ASSERT_THAT(search_result.value().entry, NotNull());
-  EXPECT_TRUE(search_result.value().entry->overlayable);
+  EXPECT_THAT(search_result.value().entry->overlayable_declarations.size(), Eq(1));
+  EXPECT_FALSE(search_result.value().entry->overlayable_declarations[0].policy);
 }
 
 TEST(ProtoSerializeTest, SerializeAndDeserializeXml) {
@@ -464,4 +465,59 @@
       "night-xhdpi-stylus-keysexposed-qwerty-navhidden-dpad-300x200-v23");
 }
 
+TEST(ProtoSerializeTest, SerializeAndDeserializeOverlayable) {
+  std::unique_ptr<IAaptContext> context = test::ContextBuilder().Build();
+  std::unique_ptr<ResourceTable> table =
+      test::ResourceTableBuilder()
+          .AddOverlayable("com.app.a:bool/foo", Overlayable::Policy::kSystem)
+          .AddOverlayable("com.app.a:bool/foo", Overlayable::Policy::kProduct)
+          .AddOverlayable("com.app.a:bool/bar", Overlayable::Policy::kProductServices)
+          .AddOverlayable("com.app.a:bool/bar", Overlayable::Policy::kVendor)
+          .AddOverlayable("com.app.a:bool/baz", Overlayable::Policy::kPublic)
+          .AddOverlayable("com.app.a:bool/biz", {})
+          .AddValue("com.app.a:bool/fiz", ResourceUtils::TryParseBool("true"))
+          .Build();
+
+  pb::ResourceTable pb_table;
+  SerializeTableToPb(*table, &pb_table, context->GetDiagnostics());
+
+  MockFileCollection files;
+  ResourceTable new_table;
+  std::string error;
+  ASSERT_TRUE(DeserializeTableFromPb(pb_table, &files, &new_table, &error));
+  EXPECT_THAT(error, IsEmpty());
+
+  Maybe<ResourceTable::SearchResult> result =
+      new_table.FindResource(test::ParseNameOrDie("com.app.a:bool/foo"));
+  ASSERT_TRUE(result);
+  ASSERT_THAT(result.value().entry->overlayable_declarations.size(), Eq(2));
+  EXPECT_THAT(result.value().entry->overlayable_declarations[0].policy,
+              Eq(Overlayable::Policy::kSystem));
+  EXPECT_THAT(result.value().entry->overlayable_declarations[1].policy,
+              Eq(Overlayable::Policy::kProduct));
+
+  result = new_table.FindResource(test::ParseNameOrDie("com.app.a:bool/bar"));
+  ASSERT_TRUE(result);
+  ASSERT_THAT(result.value().entry->overlayable_declarations.size(), Eq(2));
+  EXPECT_THAT(result.value().entry->overlayable_declarations[0].policy,
+              Eq(Overlayable::Policy::kProductServices));
+  EXPECT_THAT(result.value().entry->overlayable_declarations[1].policy,
+              Eq(Overlayable::Policy::kVendor));
+
+  result = new_table.FindResource(test::ParseNameOrDie("com.app.a:bool/baz"));
+  ASSERT_TRUE(result);
+  ASSERT_THAT(result.value().entry->overlayable_declarations.size(), Eq(1));
+  EXPECT_THAT(result.value().entry->overlayable_declarations[0].policy,
+              Eq(Overlayable::Policy::kPublic));
+
+  result = new_table.FindResource(test::ParseNameOrDie("com.app.a:bool/biz"));
+  ASSERT_TRUE(result);
+  ASSERT_THAT(result.value().entry->overlayable_declarations.size(), Eq(1));
+  EXPECT_FALSE(result.value().entry->overlayable_declarations[0].policy);
+
+  result = new_table.FindResource(test::ParseNameOrDie("com.app.a:bool/fiz"));
+  ASSERT_TRUE(result);
+  EXPECT_THAT(result.value().entry->overlayable_declarations.size(), Eq(0));
+}
+
 }  // namespace aapt
diff --git a/tools/aapt2/link/TableMerger.cpp b/tools/aapt2/link/TableMerger.cpp
index afb8ae0..d777e22 100644
--- a/tools/aapt2/link/TableMerger.cpp
+++ b/tools/aapt2/link/TableMerger.cpp
@@ -101,7 +101,7 @@
   return true;
 }
 
-static bool MergeEntry(IAaptContext* context, const Source& src, bool overlay,
+static bool MergeEntry(IAaptContext* context, const Source& src,
                        ResourceEntry* dst_entry, ResourceEntry* src_entry,
                        bool strict_visibility) {
   if (strict_visibility
@@ -134,17 +134,35 @@
     dst_entry->allow_new = std::move(src_entry->allow_new);
   }
 
-  if (src_entry->overlayable) {
-    if (dst_entry->overlayable && !overlay) {
-      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;
+  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;
+      }
     }
-    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;
 }
 
@@ -244,7 +262,7 @@
         continue;
       }
 
-      if (!MergeEntry(context_, src, overlay, dst_entry, src_entry.get(), options_.strict_visibility)) {
+      if (!MergeEntry(context_, src, dst_entry, src_entry.get(), options_.strict_visibility)) {
         error = true;
         continue;
       }
diff --git a/tools/aapt2/link/TableMerger_test.cpp b/tools/aapt2/link/TableMerger_test.cpp
index 79a734b..d6579d3 100644
--- a/tools/aapt2/link/TableMerger_test.cpp
+++ b/tools/aapt2/link/TableMerger_test.cpp
@@ -436,4 +436,97 @@
               Eq(make_value(Reference(test::ParseNameOrDie("com.app.a:style/OverlayParent")))));
 }
 
+TEST_F(TableMergerTest, AddOverlayable) {
+  std::unique_ptr<ResourceTable> table_a =
+      test::ResourceTableBuilder()
+          .SetPackageId("com.app.a", 0x7f)
+          .AddOverlayable("bool/foo", Overlayable::Policy::kProduct)
+          .Build();
+
+  std::unique_ptr<ResourceTable> table_b =
+      test::ResourceTableBuilder()
+          .SetPackageId("com.app.a", 0x7f)
+          .AddOverlayable("bool/foo", Overlayable::Policy::kProductServices)
+          .Build();
+
+  ResourceTable final_table;
+  TableMergerOptions options;
+  options.auto_add_overlay = true;
+  TableMerger merger(context_.get(), &final_table, options);
+  ASSERT_TRUE(merger.Merge({}, table_a.get(), false /*overlay*/));
+  ASSERT_TRUE(merger.Merge({}, table_b.get(), false /*overlay*/));
+
+  const ResourceName name = test::ParseNameOrDie("com.app.a:bool/foo");
+  Maybe<ResourceTable::SearchResult> result = final_table.FindResource(name);
+  ASSERT_TRUE(result);
+  ASSERT_THAT(result.value().entry->overlayable_declarations.size(), Eq(2));
+  ASSERT_THAT(result.value().entry->overlayable_declarations[0].policy,
+              Eq(Overlayable::Policy::kProduct));
+  ASSERT_THAT(result.value().entry->overlayable_declarations[1].policy,
+              Eq(Overlayable::Policy::kProductServices));
+}
+
+TEST_F(TableMergerTest, AddDuplicateOverlayableFail) {
+  std::unique_ptr<ResourceTable> table_a =
+      test::ResourceTableBuilder()
+          .SetPackageId("com.app.a", 0x7f)
+          .AddOverlayable("bool/foo", Overlayable::Policy::kProduct)
+          .Build();
+
+  std::unique_ptr<ResourceTable> table_b =
+      test::ResourceTableBuilder()
+          .SetPackageId("com.app.a", 0x7f)
+          .AddOverlayable("bool/foo", Overlayable::Policy::kProduct)
+          .Build();
+
+  ResourceTable final_table;
+  TableMergerOptions options;
+  options.auto_add_overlay = true;
+  TableMerger merger(context_.get(), &final_table, options);
+  ASSERT_TRUE(merger.Merge({}, table_a.get(), false /*overlay*/));
+  ASSERT_FALSE(merger.Merge({}, table_b.get(), false /*overlay*/));
+}
+
+TEST_F(TableMergerTest, AddOverlayablePolicyAndNoneFirstFail) {
+  std::unique_ptr<ResourceTable> table_a =
+      test::ResourceTableBuilder()
+          .SetPackageId("com.app.a", 0x7f)
+          .AddOverlayable("bool/foo", {})
+          .Build();
+
+  std::unique_ptr<ResourceTable> table_b =
+      test::ResourceTableBuilder()
+          .SetPackageId("com.app.a", 0x7f)
+          .AddOverlayable("bool/foo", Overlayable::Policy::kProduct)
+          .Build();
+
+  ResourceTable final_table;
+  TableMergerOptions options;
+  options.auto_add_overlay = true;
+  TableMerger merger(context_.get(), &final_table, options);
+  ASSERT_TRUE(merger.Merge({}, table_a.get(), false /*overlay*/));
+  ASSERT_FALSE(merger.Merge({}, table_b.get(), false /*overlay*/));
+}
+
+TEST_F(TableMergerTest, AddOverlayablePolicyAndNoneLastFail) {
+  std::unique_ptr<ResourceTable> table_a =
+      test::ResourceTableBuilder()
+          .SetPackageId("com.app.a", 0x7f)
+          .AddOverlayable("bool/foo", Overlayable::Policy::kProduct)
+          .Build();
+
+  std::unique_ptr<ResourceTable> table_b =
+      test::ResourceTableBuilder()
+          .SetPackageId("com.app.a", 0x7f)
+          .AddOverlayable("bool/foo", {})
+          .Build();
+
+  ResourceTable final_table;
+  TableMergerOptions options;
+  options.auto_add_overlay = true;
+  TableMerger merger(context_.get(), &final_table, options);
+  ASSERT_TRUE(merger.Merge({}, table_a.get(), false /*overlay*/));
+  ASSERT_FALSE(merger.Merge({}, table_b.get(), false /*overlay*/));
+}
+
 }  // namespace aapt
diff --git a/tools/aapt2/test/Builders.cpp b/tools/aapt2/test/Builders.cpp
index f33ae31..03b59e0 100644
--- a/tools/aapt2/test/Builders.cpp
+++ b/tools/aapt2/test/Builders.cpp
@@ -135,6 +135,15 @@
   return *this;
 }
 
+ResourceTableBuilder& ResourceTableBuilder::AddOverlayable(const StringPiece& name,
+                                                           const Maybe<Overlayable::Policy> p) {
+  ResourceName res_name = ParseNameOrDie(name);
+  Overlayable overlayable;
+  overlayable.policy = p;
+  CHECK(table_->AddOverlayable(res_name, overlayable, GetDiagnostics()));
+  return *this;
+}
+
 StringPool* ResourceTableBuilder::string_pool() {
   return &table_->string_pool;
 }
diff --git a/tools/aapt2/test/Builders.h b/tools/aapt2/test/Builders.h
index 9159599..d68c24d 100644
--- a/tools/aapt2/test/Builders.h
+++ b/tools/aapt2/test/Builders.h
@@ -73,6 +73,8 @@
                                  const ResourceId& id, std::unique_ptr<Value> value);
   ResourceTableBuilder& SetSymbolState(const android::StringPiece& name, const ResourceId& id,
                                        Visibility::Level level, bool allow_new = false);
+  ResourceTableBuilder& AddOverlayable(const android::StringPiece& name,
+                                       Maybe<Overlayable::Policy> policy);
 
   StringPool* string_pool();
   std::unique_ptr<ResourceTable> Build();