Merge "Revert "Revert "Allow libz to have stub even though it's not an ...""

cc/vndk.go

@@ -309,7 +309,13 @@ func processVndkLibrary(mctx android.BottomUpMutatorContext, m *Module) {
 		panic(err)
 	}
 
-	if m.HasStubsVariants() {
+	if m.HasStubsVariants() && name != "libz" {
+		// b/155456180 libz is the ONLY exception here. We don't want to make
+		// libz an LLNDK library because we in general can't guarantee that
+		// libz will behave consistently especially about the compression.
+		// i.e. the compressed output might be different across releases.
+		// As the library is an external one, it's risky to keep the compatibility
+		// promise if it becomes an LLNDK.
 		mctx.PropertyErrorf("vndk.enabled", "This library provides stubs. Shouldn't be VNDK. Consider making it as LLNDK")
 	}