Encoding of <overlayable> and <policy>

This change defines two new chunks for encoding overlayable information.
RES_TABLE_OVERLAYABLE_POLICY_TYPE contains flags that represent
restrictions enforced on overlays that try to overlay a specific set of
resource ids. The chunk header is followed by ResTable_ref for each id
that belongs to the policy type. A policy chunk will be created for
every unique combination of policies that are defined in overlayable
declarations.

RES_TABLE_OVERLAYABLE_TYPE holds policy blocks. Since <overlayable>
does not currently have any attributes, only one overlayable block is
encoded in an APK.

This change also removes the SPEC_OVERLAYABLE flag because the runtime
does not use the flag, and the overlayable chunk encoding renders it
obsolete.

Bug: 110869880
Bug: 117545186
Test: libandroidfw_tests and aapt2_tests
Change-Id: I45ae9bf4176699f14c85e2b7a2e8560185d8a0b8

1 files changed, 10 insertions, 1 deletions

diff --git a/tools/aapt2/link/ReferenceLinker.cpp b/tools/aapt2/link/ReferenceLinker.cpp
index 3a5d5858254d..1b6626a8dfe9 100644
--- a/tools/aapt2/link/ReferenceLinker.cpp
+++ b/tools/aapt2/link/ReferenceLinker.cpp
@@ -368,7 +368,16 @@ bool ReferenceLinker::Consume(IAaptContext* context, ResourceTable* table) {
         // Symbol state information may be lost if there is no value for the resource.
         if (entry->visibility.level != Visibility::Level::kUndefined && entry->values.empty()) {
           context->GetDiagnostics()->Error(DiagMessage(entry->visibility.source)
-                                           << "no definition for declared symbol '" << name << "'");
+                                               << "no definition for declared symbol '" << name
+                                               << "'");
+          error = true;
+        }
+
+        // Ensure that definitions for values declared as overlayable exist
+        if (!entry->overlayable_declarations.empty() && entry->values.empty()) {
+          context->GetDiagnostics()->Error(DiagMessage(entry->overlayable_declarations[0].source)
+                                           << "no definition for overlayable symbol '"
+                                           << name << "'");
           error = true;
         }