Run R8 on feature module

Author: snazhmudinov

examples/bundle/features/assets/BUILD

@@ -4,18 +4,19 @@ load("@rules_android//rules:rules.bzl", "android_feature_module")
 android_library(
     name = "lib",
     srcs = ["src/FeatureActivity.java"],
-    manifest = "src/AndroidManifest.xml",
     assets = ["src/assets.txt"],
     custom_package = "com.example.bundle.features.assets",
+    manifest = "src/AndroidManifest.xml",
 )
 
 android_feature_module(
     name = "feature_module",
     custom_package = "com.example.bundle.features.assets",
-    manifest = "src/AndroidManifest.xml",
-    title = "asset_feature",
-    library = ":lib",
     feature_name = "asset_feature",
     has_dex = True,
+    library = ":lib",
+    manifest = "src/AndroidManifest.xml",
+    proguard_specs = ["proguard-rules.pro"],
+    title = "asset_feature",
     visibility = ["//visibility:public"],
-)
+)

examples/bundle/features/assets/proguard-rules.pro

@@ -0,0 +1,10 @@
+# Proguard rules for dynamic feature module
+
+# Keep the FeatureActivity class name for launching via Intent
+-keep class com.example.bundle.features.assets.FeatureActivity {
+    <init>();
+}
+
+# Obfuscate everything else
+-optimizationpasses 5
+-allowaccessmodification

rules/android_application/android_feature_module_rule.bzl

@@ -196,6 +196,7 @@ EOF
         "feature_flags": getattr(attrs, "feature_flags", None),
         "$enable_manifest_merging": False,
         "testonly": testonly,
+        "proguard_specs": getattr(attrs, "proguard_specs", []),
     }
     _android_binary(**binary_attrs)
 

rules/android_application/attrs.bzl

@@ -124,6 +124,11 @@ ANDROID_FEATURE_MODULE_ATTRS = dict(
         doc = "android_library target to include as a feature split.",
     ),
     manifest = attr.label(allow_single_file = True),
+    proguard_specs = attr.label_list(
+        allow_empty = True,
+        allow_files = True,
+        doc = "Proguard specification files to apply to this feature module.",
+    ),
     title_id = attr.string(),
     title_lib = attr.string(),
     _feature_module_validation_script = attr.label(