diff --git a/libs/androidfw/tests/AssetManager2_test.cpp b/libs/androidfw/tests/AssetManager2_test.cpp
index 3118009fef902..f1cc569f7d4ed 100644
--- a/libs/androidfw/tests/AssetManager2_test.cpp
+++ b/libs/androidfw/tests/AssetManager2_test.cpp
@@ -386,6 +386,38 @@ TEST_F(AssetManager2Test, ResolveReferenceToBag) {
EXPECT_EQ(basic::R::array::integerArray1, last_ref);
}
+TEST_F(AssetManager2Test, ResolveDeepIdReference) {
+ AssetManager2 assetmanager;
+ assetmanager.SetApkAssets({basic_assets_.get()});
+
+ // Set up the resource ids
+ const uint32_t high_ref = assetmanager
+ .GetResourceId("@id/high_ref", "values", "com.android.basic");
+ ASSERT_NE(high_ref, 0u);
+ const uint32_t middle_ref = assetmanager
+ .GetResourceId("@id/middle_ref", "values", "com.android.basic");
+ ASSERT_NE(middle_ref, 0u);
+ const uint32_t low_ref = assetmanager
+ .GetResourceId("@id/low_ref", "values", "com.android.basic");
+ ASSERT_NE(low_ref, 0u);
+
+ // Retrieve the most shallow resource
+ Res_value value;
+ ResTable_config config;
+ uint32_t flags;
+ ApkAssetsCookie cookie = assetmanager.GetResource(high_ref, false /*may_be_bag*/,
+ 0 /*density_override*/,
+ &value, &config, &flags);
+ ASSERT_NE(kInvalidCookie, cookie);
+ EXPECT_EQ(Res_value::TYPE_REFERENCE, value.dataType);
+ EXPECT_EQ(middle_ref, value.data);
+
+ // Check that resolving the reference resolves to the deepest id
+ uint32_t last_ref = high_ref;
+ assetmanager.ResolveReference(cookie, &value, &config, &flags, &last_ref);
+ EXPECT_EQ(last_ref, low_ref);
+}
+
TEST_F(AssetManager2Test, KeepLastReferenceIdUnmodifiedIfNoReferenceIsResolved) {
AssetManager2 assetmanager;
assetmanager.SetApkAssets({basic_assets_.get()});
diff --git a/libs/androidfw/tests/data/basic/basic.apk b/libs/androidfw/tests/data/basic/basic.apk
index 1733b6a165464..b721ebfde4459 100644
Binary files a/libs/androidfw/tests/data/basic/basic.apk and b/libs/androidfw/tests/data/basic/basic.apk differ
diff --git a/libs/androidfw/tests/data/basic/res/values/values.xml b/libs/androidfw/tests/data/basic/res/values/values.xml
index b3435629265bb..d4b2683c62e18 100644
--- a/libs/androidfw/tests/data/basic/res/values/values.xml
+++ b/libs/androidfw/tests/data/basic/res/values/values.xml
@@ -78,4 +78,8 @@
+
+ - @id/middle_ref
+ - @id/low_ref
+
diff --git a/tools/aapt2/ResourceParser.cpp b/tools/aapt2/ResourceParser.cpp
index 1b6f8827291bf..19c6c3107e7c7 100644
--- a/tools/aapt2/ResourceParser.cpp
+++ b/tools/aapt2/ResourceParser.cpp
@@ -586,7 +586,29 @@ bool ResourceParser::ParseResource(xml::XmlPullParser* parser,
out_resource->name.type = ResourceType::kId;
out_resource->name.entry = maybe_name.value().to_string();
- out_resource->value = util::make_unique();
+
+ // Ids either represent a unique resource id or reference another resource id
+ auto item = ParseItem(parser, out_resource, resource_format);
+ if (!item) {
+ return false;
+ }
+
+ String* empty = ValueCast(out_resource->value.get());
+ if (empty && *empty->value == "") {
+ // If no inner element exists, represent a unique identifier
+ out_resource->value = util::make_unique();
+ } else {
+ // If an inner element exists, the inner element must be a reference to
+ // another resource id
+ Reference* ref = ValueCast(out_resource->value.get());
+ if (!ref || ref->name.value().type != ResourceType::kId) {
+ diag_->Error(DiagMessage(out_resource->source)
+ << "<" << parser->element_name()
+ << "> inner element must either be a resource reference or empty");
+ return false;
+ }
+ }
+
return true;
}
diff --git a/tools/aapt2/ResourceParser_test.cpp b/tools/aapt2/ResourceParser_test.cpp
index fc1aeaa58fe2e..c12b9fac5704f 100644
--- a/tools/aapt2/ResourceParser_test.cpp
+++ b/tools/aapt2/ResourceParser_test.cpp
@@ -933,4 +933,32 @@ TEST_F(ResourceParserTest, DuplicateOverlayableIsError) {
EXPECT_FALSE(TestParse(input));
}
+TEST_F(ResourceParserTest, ParseIdItem) {
+ std::string input = R"(
+ - @id/bar
+
+ )";
+ ASSERT_TRUE(TestParse(input));
+
+ ASSERT_THAT(test::GetValue(&table_, "id/foo"), NotNull());
+ ASSERT_THAT(test::GetValue(&table_, "id/bar"), NotNull());
+ ASSERT_THAT(test::GetValue(&table_, "id/baz"), NotNull());
+
+ // Reject attribute references
+ input = R"(- ?attr/bar"
)";
+ ASSERT_FALSE(TestParse(input));
+
+ // Reject non-references
+ input = R"(- 0x7f010001
)";
+ ASSERT_FALSE(TestParse(input));
+ input = R"(- @drawable/my_image
)";
+ ASSERT_FALSE(TestParse(input));
+ input = R"( )";
+ ASSERT_FALSE(TestParse(input));
+
+ // Ids that reference other resource ids cannot be public
+ input = R"(@id/bar6)";
+ ASSERT_FALSE(TestParse(input));
+}
+
} // namespace aapt