Check R8 usage before grabbing proguard outputs from ctx.outputs

Fixes #343

stacked-branch: fix-proguard-outputs

Author: pswaminathan

rules/android_binary/impl.bzl

@@ -799,7 +799,7 @@ def _process_optimize(ctx, validation_ctx, deploy_ctx, packaged_resources_ctx, b
             # Proguard map from shrinking is the final output.
             proguard_output_map = ctx.actions.declare_file(ctx.label.name + "_proguard.map")
 
-    if ctx.attr._generate_proguard_outputs:
+    if not acls.use_r8(str(ctx.label)) and ctx.attr._generate_proguard_outputs:
         proguard_output_jar = ctx.outputs.proguard_jar
         proguard_output_config = ctx.outputs.proguard_config
     else:

test/rules/android_binary/r8_integration/BUILD

@@ -10,6 +10,7 @@ py_test(
         "//test/rules/android_binary/r8_integration/java/com/basicapp:basic_app_R8_no_shrink",
         "//test/rules/android_binary/r8_integration/java/com/basicapp:basic_app_R8_shrink",
         "//test/rules/android_binary/r8_integration/java/com/basicapp:basic_app_no_R8",
+        "//test/rules/android_binary/r8_integration/java/com/basicapp:basic_app_select_R8_genmap",
         "@androidsdk//:dexdump",
     ],
 )

test/rules/android_binary/r8_integration/java/com/basicapp/BUILD

@@ -16,24 +16,41 @@ load("//rules:rules.bzl", "android_binary", "android_library")
         proguard_specs = specs,
         resource_files = glob(["res/**"]),
         shrink_resources = shrink,
+        proguard_generate_mapping = genmap,
         visibility = ["//test/rules/android_binary/r8_integration:__pkg__"],
         deps = [
             ":basic_lib",
             ":lib_with_specs",
         ],
     )
-    for name, specs, shrink in [
+    for name, specs, shrink, genmap in [
         (
             "basic_app_R8_shrink",
             ["proguard.cfg"],
             True,
+            False,
         ),
         (
             "basic_app_R8_no_shrink",
             ["proguard.cfg"],
             False,
+            False,
+        ),
+        (
+            "basic_app_no_R8",
+            [],
+            False,
+            False,
+        ),
+        (
+            "basic_app_select_R8_genmap",
+            select({
+                ":is_c_opt": ["proguard.cfg"],
+                "//conditions:default": [],
+            }),
+            True,
+            True,
         ),
-        ("basic_app_no_R8", [], False),
     ]
 ]
 
@@ -58,3 +75,10 @@ android_library(
     manifest = "AndroidManifest_lib.xml",
     proguard_specs = ["lib2_proguard.cfg"],
 )
+
+config_setting(
+    name = "is_c_opt",
+    values = {
+        "compilation_mode": "opt",
+    },
+)

test/rules/android_binary/r8_integration/r8_integration_test.py

@@ -81,6 +81,14 @@ def test_r8_integration(self):
         expect_unused_activity_class=False,
     )
 
+    # No R8 when run in default test mode (non-opt),
+    # so unused resources and unused classes should be in the app
+    self._r8_integration_check(
+        "basic_app_select_R8_genmap.apk",
+        expect_unused_activity_resource=True,
+        expect_unused_activity_class=True,
+    )
+
 
 if __name__ == "__main__":
   dexdump = sys.argv.pop()